In modern construction - even multi-storey, even cottage, even commercial, even residential - systems of passive and active ventilation, air heating and air purification are widely used.
If earlier voids were specially left in ceilings and walls for these purposes, today ventilation communications are laid using ventilation ducts (they are also called air ducts, ventilation pipes). These are special tubular hollow structures that allow you to distribute supply air and remove polluted air.
Types of air ducts
The production of ventilation ducts can become quite profitable business, but first you need to decide what specific types of structures you want to produce. Air ducts can be classified according to different criteria. So, depending on the shape, round and rectangular are distinguished. ventilation ducts, based on the material used, the structures can be plastic, steel (galvanized or stainless steel), aluminum, polyester, thermoplastic, silicone, fiberglass and so on.
Availability special properties air ducts are divided into fire retardant, stainless and others, according to the connection method - into those that have special fasteners and those that are connected using nipples. There are two main types of ventilation ducts: flexible (they are also called frame) and rigid.
Choosing which ducts to produce
Manufacturing ventilation pipes rectangular or round shape made of aluminum or steel is the easiest option. Such structures are faster and easier to install than plastic ones, and also have a lower cost, they do not rust, are fire retardant, and have low aerodynamic resistance.
Installation of ventilation with such air ducts can be carried out at enterprises, offices, sports, educational, cultural and entertainment institutions, organizations Catering and in general in any buildings where there are large premises, during the operation of which active air exchange is expected.
Making flexible ventilation ducts is a more complex process. They can only be used in specific conditions, for example, in rooms with a complex configuration or in buildings where ventilation installation using large galvanized ventilation pipes is not possible. Also, such structures are used in rooms where it is impossible to provide active ventilation systems, for example, hoods to remove hot air and acid vapors.
The cost of manufacturing ventilation pipes from rigid materials will be less, but it is necessary to start production with them not for this reason, but because you can quickly implement such air ducts.
Production process
Structures of any kind are made on special automatic machines. In fact, the production process is a conventional roll forming operations. We will not talk in detail about how to make a ventilation duct. After all, this is not done manually, but with the help of technical devices. Therefore, the most important task for you, if you want to create a successfully functioning enterprise, is to choose good equipment for the production of ventilation.
We take into account important parameters
When choosing fixed assets, be guided by the main parameters of air ducts: stiffness, area and cross-sectional shape (based on the degree of demand in the market). We have already talked about rigidity, so everything is clear with this. Flexible ventilation ducts can be sold more expensive than rigid ones, but they are also less in demand.
As for the area and shape of the section, here the matter with the choice is more complicated. Different indicators will depend on what specific designs you will use, for example, the speed of the air flow, and, consequently, the level of noise emitted by this flow in case the speed standards are exceeded.
Other selection factors
The production of round ventilation ducts is less laborious, since they are fastened with clip-on nipples. Also, such air ducts are faster and easier to install, because they do not have protruding parts. They are durable and, due to their more natural shape, create less aerodynamic drag.
At the same time, rectangular ventilation pipes show the best indoor airflow when a large cross-sectional area is required or when installation is carried out in difficult conditions, for example, above suspended ceilings.
The manufacture of round and rectangular ventilation ducts is carried out from the same materials: either aluminum with a thickness of half a millimeter to a millimeter, or galvanized steel. According to statistics, their sales volume is also almost equal, they are in the same demand.
And yet, if you want to make your business more successful, purchase ventilation production equipment, which includes lines for the production of both round and rectangular pipes. What kind of cars do you need?
We equip the workshop for the production of air ducts
So, technological line for the manufacture of ventilation ducts of any section should include:
- feeding device;
- automatic machine for unwinding metal rolled sheet;
- apparatus for straightening a sheet (the technology allows a diagonal deviation of both the blank sheet and the air duct itself by 0.8 mm - if the ventilation pipe has a strong geometry violation, then a lot of noise will be emitted from the air flow, so modern technology in without fail includes dressing device);
- industrial numerical control system;
- guillotine that cuts off the finished duct.
The line used for the production of rectangular and round ventilation pipes differs only in that in the first case, the shaping units are corner cutting devices, a rib stiffening system, an automatic sheet bender equipped with a rotary beam, and in the second case, rolling rollers.
Process line cost
The production of ventilation ducts is quite expensive. A line for the manufacture of circular ducts (provided that the manufacturer is domestic) will cost about one and a half million rubles.
The cost of the line for the production of rectangular ventilation pipes will be from 1.8 million rubles and more. That is, in order to purchase both lines, you need to have in stock no less, but 3.3 million rubles by the most minimal standards.
Payback period
But there is also good news. Profitability in this area of business is quite high. And if you sell a linear meter at a price of 120-3000 rubles (depending on the diameter of the pipes), then even if you work in one shift five days a week, you can recoup the costs in six months.
Development prospects
The production of ventilation ducts is a promising business. Having adjusted technological process, you can expand your business and also engage in the manufacture of connecting and fastening fittings for pipes: plugs, nipples, "umbrellas", tie-ins, mounting perforated tape and more. Such products can be made from substandard goods, scraps and other waste.
In addition, try to enrich the product range: start making rigid plastic, polyester, silicone, flexible PVC, rubber and other air ducts. This will allow you to at least occupy a regional market segment in the field of ventilation systems.
Having worked steadily for at least six months and having thoroughly prepared the technological base, you can engage, among other things, in organizing services for the design and installation of ventilation systems. To do this, you will need to hire engineers who specialize in heat and gas supply work.
These are sought-after specialists at the present time, so get ready that their work will not be cheap at all. Also among the employees you will need installers, but their work is not valued so highly, it is believed that these are low-skilled workers, and sometimes they may not be qualified at all. Having recruited staff, you can offer services for the installation of ventilation systems.
With a question proper organization ventilation, a person encounters both during the construction of a small house in the country, and during the construction of industrial workshops, and during the arrangement office buildings. For each case, you can choose the best ventilation option, but the use of galvanized steel air ducts can be considered a universal solution in any situation.
About the advantages of galvanizing
In general, they can be made from the following materials:
- plastic - the price of such a solution is minimal, but the scope is limited to private construction;
- aluminum - they are corrosion resistant, but aluminum is a rather ductile metal, so such ventilation ducts do not tolerate possible loads;
- from galvanized steel - practically have no flaws;
- from improvised materials. For example, an air duct can be built even from ordinary thick, well-fitted boards.
Note! Plank ventilation ducts can only be recommended for ventilation of outbuildings, such as cellars or basements in the country.
Galvanized ventilation ducts can be used almost without restrictions. They can easily cope with the transportation of hot air or vapors of aggressive substances. In addition, steel is able to withstand high temperatures while maintaining sufficient strength.
Plastic is completely incapable of withstanding prolonged exposure to elevated temperatures, and it cannot oppose anything to the effects of chemicals. The only advantage of this material is its low weight and ease of installation.
Ventilation pipes made of galvanized steel can withstand without reducing the technical and operational performance:
- temperature around +80ᵒС – without time limit;
Note! For the safety of personnel, air ducts transporting hot air are usually equipped with a heat-insulating layer.
- within a short time, the air temperature may rise up to +200ᵒС. even in the event of a fire at the enterprise, the ventilation system will not allow the area to smoke;
- galvanized pipes for ventilation do not require additional protection from humidity. A thin layer of zinc coating prevents corrosion.
Note! Even if the integrity of the zinc layer is violated, for example, by cutting a self-tapping screw, the steel still remains protected. The fact is that steel and zinc form a galvanic couple, and as a result of a chemical reaction, a thin oxide film covers the cut.
Methods for the production of galvanized air ducts
The technology directly depends on the cross-sectional shape of the pipe.
Ventilation pipes can be:
- round section– optimal aerodynamic characteristics;
- square or rectangular section- slightly worse aerodynamics, but easier to install due to flat surfaces.
The raw material for the manufacture of galvanized air ducts is thin sheet galvanized steel. As a rule, the thickness of the sheet does not exceed 1.0 mm, this provides a balance between acceptable weight and sufficiently high rigidity.
The manufacture of ventilation from galvanization is carried out according to one of 2 methods:
- in the case of a round section, either spiral-wound technology is used, or simple rolling of sheet metal, followed by a seam connection of the edges;
- for profile air ducts, only one technology is used - a galvanized sheet is passed through a series of rollers, which give it the desired shape. Then the edges of the future ventilation duct are connected.
Spiral wound technology
Differs in extremely high productivity, in a minute the machine processes about 60 m strips. The production of galvanized ventilation using this technology consists in the fact that the machine simply bends a steel strip so that a round pipe is obtained.
At the same time, adjacent turns are overlapped, due to strong tension, the edge of the strip is slightly deformed and the tightness of the connection is achieved.
In addition to high performance, pipes produced using this technology are characterized by high rigidity. The helical seam plays the role of a stiffener, so that in equal conditions such air ducts will withstand a greater load than its longitudinal counterpart.
Longitudinal pipes
Ventilation galvanized pipes produced using this technology, in terms of technical and operational indicators, almost do not differ from spiral-wound pipes. They just have a little less rigidity.
The entire process can be divided into 3 stages:
- a strip of the desired length is cut;
- it is passed through a series of rollers;
- joining adjacent edges of the metal.
As for the profile pipeline, quite often everything is prepared at the ends of the section for the subsequent flange connection. The same technology is used to manufacture ventilation ducts from galvanized steel.
Elements of galvanized ventilation
When installing the ventilation system, you will need not only galvanized ventilation ducts, but also a number of shaped elements. For example, bends at different angles of rotation, plugs, gratings, tees, etc. Without these elements, installation is simply impossible.
Elbows
This is one of the most common types of shaped elements, used in cases where it is necessary to ensure a smooth turn of the duct. The main characteristic of the branch is the angle of rotation, options are available that provide rotation by an angle from 15ᵒ to 90ᵒ.
Note! Galvanized ventilation will work much worse if the duct turns many times at a large angle. This reduces the airflow rate.
As for the production of bends, a strip of variable width is used for this. Due to the unequal width, when bent, its ring width is different. The entire branch consists of several such rings, by adjusting the width of the strips, theoretically, any angle of the branch can be obtained, but for convenience they are produced in increments of 15ᵒ.
ventilation duct
Strictly speaking, a ventilation duct is just a vertical rectangular or square duct in which several ducts with a smaller cross section are placed. Depending on the operating conditions, plastic, aluminum or galvanized ventilation ducts can be used.
If you mentally cut this structure across, then the observer will see not 1, but 3 channels. The largest one is a common ventilation duct, and 2 smaller ones ensure the removal of unpleasant odors from the underlying apartment. As a rule, 1 outlet is used in the kitchen and 1 in the bathroom or toilet.
Considering small area kitchens and bathrooms of most apartments, many people are thinking about how to minimize the box area and make it invisible. Galvanized ventilation ducts can help with this.
Note! Residents of multi-storey buildings are often mistaken, considering the ventilation box as their property, and demolish it. If the case comes to trial in court, then the unfortunate builders will have to restore the destroyed with their own hands.
Other shaped elements
In addition to bends, when installing ventilation, you may need such shaped elements as:
- transitions or ducks - used to shift the duct. In parallel with the displacement, by reducing the diameter, it is possible to adjust the speed of the air flow;
- plugs - used if necessary to block the free end of the pipe;
- gates - control devices;
- fire dampers;
- crosses and tees - serve to create complex nodes of the ventilation network;
- nipples - used when installing pipes;
- galvanized steel ventilation grilles - used to protect against insects, small animals and debris from the ventilation duct entering the room.
About mounting technology
As for fixing the channel to the walls or ceiling, you can get by with ordinary clamps or even just hang the pipe on a metal tape. In industrial buildings, for laying an air duct, a bracket is embedded in the wall, and the pipe rests on it.
Note! If the air velocity is high, then fixing the duct with clamps or with metal tape will not provide sufficient rigidity. The pipe will rattle, so you need a more secure mount.
Special attention should be paid to the tightness of the joints of individual sections.
The connection can be made in several ways:
- nipple. The nipple itself is a section of a pipe of a slightly smaller diameter, it is simply inserted into the duct with force and rotated. The instruction for making a socket connection looks the same, with the only difference being that the diameter of the socket is larger than the diameter of the duct;
- flanged- the strength of the joint is achieved by simply tightening the bolts;
- folded- a reliable joint is provided due to the joint deformation of the metal of different pipe sections.
For the manufacture of air ducts, metal, non-metallic and metal-plastic materials are used, as well as building structures. Materials for the manufacture of air ducts are selected depending on the characteristics of the medium transported through the air ducts.
| Materials for air ducts | ||
| Characteristics of the transported medium | Products and materials | |
| Air with a temperature not exceeding 80°C with a relative importance of not more than 60% | Concrete, reinforced concrete and gypsum ventilation blocks; plasterboard, gypsum concrete and wood concrete boxes; thin-sheet, galvanized, roofing, sheet, rolled, cold-rolled steel; fiberglass; paper and cardboard; other materials that meet the requirements of the specified environment | |
| The same, with a relative humidity of more than 60% | Concrete and reinforced concrete blocks; thin-sheet galvanized, sheet steel, sheet aluminum; plastic pipes and plates; fiberglass; paper and cardboard with appropriate impregnation; other materials that meet the requirements of the specified environment | |
| Air mixture with reactive gases, vapors and dust | Ceramic and pipes; plastic pipes and boxes; blocks of acid-resistant concrete and plastic concrete; metal-plastic; Sheet steel; fiberglass; paper and cardboard with protective coatings and impregnation corresponding to the transported medium; other materials that meet the requirements of the specified environment | |
Note: Air ducts made of cold-rolled and hot-rolled steel sheets must have a coating that is resistant to the transported medium.
Carbon steel of ordinary quality according to the rolling method is hot-rolled, if the workpiece is preheated, and cold-rolled, i.e. without heating the workpiece. According to the thickness, such steel is subdivided into thick sheets - 4 mm thick or more and thin sheets - up to 3.9 mm thick. Sheet steel with a thickness of 0.35 to 0.8 mm is called roofing.
sheet hot rolled steel manufactured in sheets 0.4...16 mm thick, 500...3800 mm wide, 1200... ...9000 mm long and in rolls 1.2...12 mm thick, 500...2200 wide mm. They are used for the manufacture of air ducts for general ventilation and aspiration.
Sheet cold rolled steel are produced in sheets with a thickness of 0.35 ... 0.65 mm and in rolls with a thickness of 0.35 ... 3 mm. Used for the production of spiral-seam air ducts.
Galvanized sheet steel produced with a double-sided galvanized coating that protects steel from corrosion, in sheets 0.5 ... 3.0 mm thick, 710 ... 1500 mm wide. Used for the manufacture of only folded air ducts.
Thin sheet cold rolled carbon steel use a width of 100 ... 1250 mm, a thickness of 0.6 ... 2 mm.
Cold rolled low carbon steel strip thickness of 0.05 ... 4 mm, width up to 450 mm is used for the manufacture of spiral lock air ducts.
In the manufacture of air ducts and parts of ventilation systems, structural materials are widely used - sectional and shaped steel, as well as rolled aluminum.
flat steel produced in widths from 12 to 200 mm, thicknesses from 4 to 16 mm. These products are supplied in coils or strips, depending on the size. Flanges and fasteners are made from strip steel.
Angle Equal Shelf Steel profiles No. 2 ... No. 16 are made, which corresponds to the width of the shelf in centimeters; the thickness of such steel is from 3 to 20 mm. Frames, duct flanges are made of steel.
Non-ferrous metals
Aluminum- silver-white, light (ρ = 2700 kg/m3) and ductile metal. Interacting with atmospheric oxygen, aluminum is covered with a thin and durable film of aluminum oxide, which well protects the metal from corrosion. Folded and welded air ducts are made of aluminum.
Sheets of aluminum and aluminum alloys, produced with a thickness of 0.4 to 10 mm, a width of 400, 500, 600, 800 and 1000 mm, a length of 2000 mm, are used for the manufacture of air ducts and individual parts of ventilation systems.
The corners pressed from aluminum and aluminum alloys let out shelf width from 10 to 250 mm. With the same shelf width, the profiles can be of different thicknesses. Separate elements of network equipment are made from the corners.
Aluminum foil is produced with a thickness of 0.05 to 0.4 mm and is also supplied in rolls. Use foil for flexible corrugated air ducts. The height of the corrugation is 4 mm, the distance between the corrugations is 10 mm. Such air ducts are easily bent and serve for connection to local suctions.
Titanium- silvery-white refractory metal with high corrosion resistance (especially to acids), rather ductile, density ρ=4500 kg/m3. The high strength of titanium alloys is maintained at temperatures from -253 to +500 °C.
Commercially pure titanium grade VT1-00 or VT1-0, as well as low-alloy alloys of increased ductility grade ST4-0 or ST4-1 in the form of sheets with a thickness of 0.4 to 4 mm are used for the manufacture of air ducts. Air ducts made of titanium are usually welded.
Copper- viscous metal of a reddish color, heat and electrically conductive, plastic enough, which allows it to be processed by rolling, stamping, drawing. Copper in its pure form, as a rule, is not used in ventilation systems; usually alloys of copper with other metals are used. An alloy of copper and zinc is called brass. Compared to copper, brass is stronger, more ductile and harder, more resistant to corrosion and, when cast, has good mold filling.
Copper-zinc alloys (brass) are produced in seven grades: L96, L90, L85, L80, L70, L68, L62 (the numbers indicate the average percentage of copper in the alloy). Brass is used to make spark-proof ventilation equipment.
metal plastics
metal-plastic- structural material, which is a low-carbon cold-rolled sheet steel coated with a film. The industry produces metal-plastic of two types: with one- and two-sided coating.
Metal sheet with one-sided coating produced in the form of a steel tape with a thickness of 0.5 ... 1 mm, protected on one side with a polyvinyl chloride film with a thickness of (0.3 ± 0.03) mm. Metal-plastic is supplied in rolls with a strip width of (1000 ± 5) mm, weighing up to 5.5 tons. The outer diameter of the roll is not more than 1500 mm, the inner diameter is (500 ± 50) mm.
Double-sided coated metal is a steel tape with a thickness of 0.5 ... 0.8 mm, both sides of which are protected by a film of modified polyethylene with a thickness of 0.45 mm.
The metal-plastic has the properties inherent in metal and plastics; it is plastic, can be processed on the mechanisms that manufacture seam air ducts.
non-metals
Sheets of plasticized polyvinyl chloride) are made from an unplasticized polyvinyl chloride composition with the addition of auxiliary substances (stabilizers, lubricants, etc.) by film pressing or extrusion.
Sheets of unplasticized polyvinyl chloride are produced with a length of at least 1300 mm, a width of at least 500 mm. The thickness of the sheets depends on their brand and is for sheet vinyl plastic: VI - from 1 to 20 mm; VNE and VP - from 1 to 5 mm; VD - from 1.5 to 3 mm.
Sheet vinyl plastic has high mechanical strength, lends itself well to both manual and mechanical processing on conventional metal and woodworking machines. When heated, it acquires plasticity and is easily molded. After cooling the heated vinyl plastic, all its mechanical properties are restored. Viniplast is an electrically insulating material.
Sheet vinyl plastic is used in the manufacture of air ducts as an anti-corrosion material operating at temperatures from -20 to + 00 ° C.
Polyethylene- Synthetic polymer, dense, characterized by high chemical resistance. Apply at temperatures up to 60 ° C. A film for ventilation ducts is made from high-density polyethylene, which is delivered to the construction site in the form of a roll wound around a sleeve. 300...400 m of film up to 4000 mm wide and 30 to 200 microns thick are wound into a roll.
fiberglass- a material formed by interlacing mutually perpendicular strands of glass fiber. Flexible reinforced air ducts are made from fiberglass SPL impregnated with latex using glue and spring wire made of carbon steel with a diameter of 2 ... 2.5 mm.
textile materials
Types of air ducts
1. Round 2. Rectangular
Rice. 1. Details of duct networks:
1 - straight sections of round air ducts (a) and rectangular (b) sections;
II - branch nodes of round air ducts (in) and rectangular (r) sections;
III - bends and half-bends of round (d) and rectangular air ducts (e) sections;
IV - transitions;
1 - tee;
2 - transition;
3 - crosses;
4 - plug
Rice. 2. Unified details of round ducts: a- straight seam straight part; b - spiral locking straight part; shaped parts: in - bend 90 degrees; G- bend 30, 45, 60 degrees; d - symmetrical transition to B == 400 mm; e- asymmetrical transition from above AT= 400 mm; and- internal nipple, designed to connect the straight parts of the air ducts to each other; h - external nipple, designed to connect the fittings of air ducts to each other; and- end cap
Rice. 3. Unified details of rectangular ducts: a - straight part: fittings; b - bend 90 degrees; in- outlet 45 degrees; G - plug; d - duck; e- transition from a rectangular section to a round one; and - transition from rectangular to rectangular
3. Semi-oval
BUT - minor axis;
AT- major axle
Rice. 5. Shaped parts of semi-oval air ducts:
a - bend 90 degrees:
a1 - vertical;
a2- horizontal;
b - the transition is asymmetric;
in - the transition is symmetrical;
G - nipple internal;
d - plug;
e - tee;
and- insert in a circle;
h - transition from oval to round;
and - transition from oval to rectangular
4. Spiral lock
Rice. 6. Spiral lock air duct
Rice. 7. Installation diagram (a) for the production of spiral lock air ducts:
1 - decoiler,
2 - mechanism for cutting and welding the ends of the tape,
3 - belt degreasing mechanism,
4 - ribbon,
5 - profiling mill,
6 - mold head,
7 - spiral lock pipe
5. Spiral welded
Rice. 8. Spiral welded duct
6. Semi-rigid and textile
Rice. 9. Semi-rigid ducts:
a- schematic diagram of a semi-rigid duct;
b- semi-rigid air duct
Rice. 10. Textile air duct
7. Metal-plastic
Rice. 11. Air duct made of metal-plastic:
a -general form,
b - seam design,
c, g- two-sided and one-sided metal-layer,
1- PVC film,
2 - glue,
3 - steel tape
Seam connections
Rice. 12 Types of seam connections;
a - recumbent fold,
6 - recumbent fold with double cut-off,
c - corner fold,
g - corner seam connection with slotted latches,
d - standing fold,
e-zig connection,
g - rack connection
Rice. 13. Seam connection of round elements on the ridge
Rice. 14. Lying seam
Rice. 15. Standing seam
Rice. 16. Corner rebate
Figure 17. Pittsburgh (Moscow) fold
In the manufacture of air ducts, the sheets are interconnected:
- for welding (butt or overlap)
- on folds
Welded joints
Rice. 1.2.1 Welded joints:
a - butt, 6 - lap
Fig 19. Schemes for welding round ducts:
a - overlap,
6 - along the bent edges on one side,
c - along the bent edges on both sides
Rice. 18. Seam classification:
a - depending on the position of the parts to be welded,
6 - in the direction of efforts,
in - in length,
d - by degree of amplification
Rice. 20. Types of welded joints used in welding metal ducts:
a - a longitudinal seam for round and rectangular air ducts, paintings,
6 - annular seam for round bends,
c - welding of round flanges and fittings of rectangular air ducts,
e - welding of rectangular flanges and fittings,
e - welding of flanges of rectangular and round sections,
g - tacking of flanges of rectangular section,
h - welding of spirally welded air ducts,
and - welding of ventilation ducts
Rice. 21. Scheme of welding a section of a rectangular duct:
a - welding of knots,
6 - tacking the branch to the straight section
Rice. 22. Snap fold
Methods for connecting air ducts to each other
Flange connections
Corner flanges
Rice. 23. Angle steel flange
Flanges made of profiled galvanized tape
Rice. 24. Z-rail flange:
1 - Z-rail;
2 - C-rail;
3 - seal 8 x 15;
4 - inner corner;
5 - decorative corner
Rice. 25. Flange from profile type "tire"
Flat steel flange
Rice. 26. Flange made of strip steel for flanged air ducts with a diameter of 100 ... 375 mm
Sheet steel flange
Rice. 27. Sheet steel flange with flanges
Rice. 28. The position of the closing transverse end
rebate on round air ducts
Wafer connections
Fig.29. Flanged connection of rectangular ducts:
a, b- the sequence of preparation of air ducts;
in- section of the connection;
G- complete connection;
1 - lock profile;
2 - rubber compressor;
3 - kapron corner;
4 - decorative corner;
5 - connecting rail;
6 - stiffening corner
Socket (nipple) connection
Rice. 30. Nipple connection of round ducts
bandage connection
Rice. 31. Bandage connections of links of round air ducts:
a - with rubber seals;
b - with buteprol sealant;
in - on rivets;
g - with inserts during installation:
1 - bandage;
2 - sealant;
3 - steel corners;
5 - branch pipe;
6 - apron;
7 - air duct;
8 - bandage with buteprol sealant;
9 - bottom loop;
10 - buteprol
Telescopic connection
Rice. 32. Telescopic duct connection:
a - on self-cutting screws;
b - using combined rivets;
1 - self-tapping screw;
2 - rivet of one-sided riveting
Rice. 33. Connection of parts with one-sided riveting:
1,2 - details;
3 - rivet body;
4 - rod head;
5 - weakened section of the rod;
6 - riveter or pistol;
7 - collet riveter;
8 - rod.
Plank connection
Fig.34. Plank connection of steel
air ducts:
a - general view;
b - types of slats;
c - T-shaped rails
Production of round ducts
Rice. 2.1. Typical technological layout production area production of air ducts on a seam connection:
a - straight sections;
6 - fittings;
1- container for metal;
2 - marking table;
3 - guillotine shears;
4 - sheet bending mechanism;
5- rolling mechanisms;
6 - roller tables;
7 - containers for flanges;
8 - spot welding machine;
9 - folding mechanisms;
10- mechanisms for flanging;
11 - workbenches;
12 - painting conveyor;
13 - mechanism for
flanging of rectangular air ducts;
14 - welding transformer;
15 - false-sedimentary mechanism;
16 - cutting mechanism;
17 - mechanism for bending curved edges;
18 - sigmachine;
19 - mechanism for upsetting corner folds;
20 - selenium rectifier
Manufacturing sequence
| Working cycle | Operation | Equipment and tools | Operation sketch |
| Marking and cutting blanks | Trim both sides of a standard sheet at a 90° angle (if necessary) | Guillotine shears | |
| Mark the elements of the ventilation blank | Marking table, templates, scriber, ruler, compasses | ||
| Cut corners of elements | Pneumatic manual scissors | ||
| Rectilinear cutting of elements according to the markup | Guillotine shears | ||
| Curvilinear cutting of elements according to the markup | Die cutting mechanism | ||
| Procurement of semi-finished products | Roll rebate (straight) | Seam rolling mechanisms | |
| Roll curved seam and edge | Mechanism for forming curved edges | ||
| Roll (bend) elements of blanks | Rolling mechanisms | ||
| Sheet bending mechanisms | |||
| Cut out elements from the side to form a ridge and corrugation | Mechanisms for the manufacture of bends, ring templates, rollers | ||
| Assembly of elements | Assemble the ventilation blank, close and upset the fold | Seam upsetting mechanism | |
| Assemble the ventilation blank, close and upset the fold | Locksmith workbench; hammer | ||
| Assemble the ventilation blank on the ridges | Mechanism for making taps | ||
| Collect the elements of the parts on the rail and upset | Locksmith workbench, mallet, hammer | ||
| Flanging | |||
| Install the flanges on the ends of the assembled products and flange on the flange mirror or weld | Semi-automatic welding in environment with 2 | ||
| Coloring | Duct painting and drying | Painting conveyor | |
| Packing and marking | |||
| Stacking in a warehouse or in a container |
AIR DUCTS AND TYPICAL PARTS OF VENTILATION SYSTEMS
METAL AIR DUCTS
Air ducts and fittings for them are manufactured in certain sizes and types established by VSN 353-86 "Design and use of air ducts from unified parts", "Temporary normal for metal air ducts of circular cross section for aspiration systems", TU 36-736-78 "Metal air ducts" and SNiP 2.04.05-86 "Heating, ventilation and air conditioning".
When transporting air with a temperature of up to 80 ° C and a relative humidity of up to 60%, air ducts made of hot-rolled or galvanized sheet steel, cold-rolled steel tape, cold-rolled sheet steel, fiberglass, asbestos-cement pipes and ducts are used (air ducts from asbestos-cement structures are not allowed to be used in systems supply ventilation). If the temperature or relative humidity of the air moving through the air ducts is above the specified limits, use galvanized sheet steel, sheet steel of increased thickness (up to 1.5 ... 2 mm), aluminum sheet, plastic pipes and sheets (only at high relative humidity) , fiberglass, asbestos-cement pipes.
In the event that the air mixture contains reactive gases, vapors or dust, metal-plastic, thin-sheet steel of increased thickness (up to 1.5 ... 2 mm) with a protective coating corresponding to the transported medium (perchlorvinyl enamels and varnishes) , plastic and asbestos-cement pipes, boxes and sheets, fiberglass. In some cases, to move an aggressive environment, air ducts made of thin-sheet corrosion-resistant, heat-resistant and heat resistant steels or titanium.
Round ducts. Round air ducts are made with diameters, mm: 100, 125, 160, 200, 250, 315, 355, 400, 450, 500, 560, 630, 710, 800, 900, 1000, 1120, 1250, 1400, 1600, 1800 and 2000; for aspiration and pneumatic transport systems, additional diameters are used, mm: PO, 140, 180, 225 and 280.
For air ducts made of roofing sheet steel, the outer diameter of the air duct is taken as the normalized diameter.
The wall thickness of round air ducts, through which air moves with a temperature of not more than 80 ° C, depends on their diameter.
Air duct diameter, mm. . Up to 200 250...450 500...800
Duct wall thickness, mm............0.5 0.6 0.7
Air duct diameter, mm. . 900...1250 1400 1G00 1800...2000
Duct wall thickness, mm.............1.0 1.2 1.4
Air ducts made of metal-plastic with a one- or two-sided coating are made as spiral locks with a diameter of 100 ... 800 mm, as well as straight-seam. The technology for manufacturing air ducts from a metal layer does not differ from their manufacture from a steel sheet or mite.
Straight sections of round air ducts take a length of 2500, 3000, 4000, 5000 and C000 mm.
Shaped parts of round section are shown in fig. 27. Bends with one link and two glasses and zero-bends (Fig. 27, a, b) with an average radius R-D used for general ventilation systems; for aspiration and pneumatic transport systems, bends are used, consisting of five links and two glasses (Fig. 27, c) with an average radius R \u003d 2D with a branch diameter of more than 315 mm or three links and two glasses with a branch diameter of 315 mm or less.
Stamped bends (Fig. 27, d), which have high aerodynamic properties, are used for general ventilation ventilation systems.
Branch nodes (tees), shown in fig. 27, e, e, -h, i, l, are used only for general ventilation systems, and in fig. 27, g, j, m - for aspiration systems and pneumatic transport.
Unified axial transitions (Fig. 27, n) are standardized in length.
Flexible corrugated metal air ducts (TU 400-2-157-86) are made from the following materials:
Cold-rolled or galvanized low-carbon steel sheet (GOST 503-81 *) with a section of OLxYuOmm;
Cold-rolled strip with a cross section of 0.1 X 100 mm from corrosion-resistant and heat-resistant steel (GOST 4986-79 *);
aluminum rolled soft foil (GOST 618-73 *) 0.1 ... 0.15 mm thick, 100 mm wide.
The bending radius of flexible corrugated ducts depends on the nominal diameter (Table 34).
Rectangular ducts. Rectangular air ducts are made with side dimensions, mm: 100X150, 150X150, 150X200,
250X250, 300X150, 300X250, 400X250, 400X400, 500X250, 500X400, 500X500, 600X400, 600X500, 600X600, 800X400, 800X500, 800X000, 800X800, 1000X500, 1000X600, 1000X800, 1000x1000, 1250X000,
1250X800, 1250X1000, 1250X1250, 1600X800, 1600ХЮ00, 1600X1250, 1600X1600, 2000ХЮ00, 2000X1250, 2000X1600, 2000x2000, 2500Х X1250, 2500Х1600, 2500x2000, 2500x2500, 3150X1600, 3150x2000, 3150X2500, 3150X3200, 4000x2500, 4000x3150.
Rice. 28. Shaped parts of rectangular air ducts:
a, b - bends with a central angle of 90 and 45 °, o - bend assembled from panels, d..g - unified branch nodes (tees), h - unified transition, / - back of the head, 2 - sidewall. 3 - neck, 4 - base, 5 - passage, 6 - unified transition, 7 - branch, 8 - plug
The wall thickness of rectangular air ducts, through which air with a temperature of up to 80 ° C is mixed, depends on their cross section.
The largest side of the duct section, mm (inclusive) .............. 250 1000 2000
Duct wall thickness, mm... . 0.5 0.7 0.9
To ensure the rigidity of straight sections of air ducts, the standard length of which is 2500 mm, with a section side from 400 to 1000 mm, ridges are made with a step of 200 ... 300 mm along the perimeter of the duct or diagonal bends (bends). With a section side of more than 1000 mm, in addition, external or internal stiffening frames are installed. Diagonal steel corners are usually used as external stiffening frames, and round or oval steel strip inserts with a pitch of 1250 mm are used as internal frames. The stiffening frames must be securely connected to the duct by spot welding or rivets. With a size of one side of the air duct more than 2000 mm, its rigidity is ensured by assembling it from separate panels.
Shaped parts of rectangular section are shown in fig. 28. Branches of rectangular air ducts (Fig. 28, a, b) have a constant neck radius of 150 mm with a branch width of up to 2000 mm. With a larger width, the outlet is assembled from panels (Fig. 28, c).
Rectangular branch nodes (tees) (Fig. 28, d ... g) are assembled from straight sections, branch pipes and unified transitions; sometimes stubs are added to them.
Unified transitions (Fig. 28, h) one-sided with a normalized height of 300, 400, 500, 700 and 900 mm are used to change the cross sections of ducts and branches.
INTRODUCTION
Welding, along with casting and pressure treatment, is the oldest technological operation mastered by man in the Bronze Age during the acquisition of experience in working with metals. Its appearance is associated with the need to connect various parts in the manufacture of tools, military weapons, jewelry and other products.
The first method of welding was forge, which provided a fairly high quality connection at that time, especially when working with ductile metals such as copper. With the advent of bronze (harder and harder to forge), foundry welding arose. During foundry welding, the edges of the parts to be joined were molded with a special earthen mixture and poured with heated liquid metal. This filler metal was fused with the parts and solidified to form a seam. Such compounds have been found on bronze vessels preserved from the times of Ancient Greece and Ancient Rome.
With the advent of iron, the range of metal products used by man increased, so the scope and scope of welding expanded. New types of weapons are being created, the means of protecting a warrior in battle are being improved, chain mail, helmets, and armor are appearing. For example, in the manufacture of chain mail, more than 10 thousand metal rings had to be connected by forge welding. New casting technologies are being developed, knowledge is gradually being acquired related to the heat treatment of steel and giving it different hardness and strength. Often this knowledge was obtained by chance and could not explain the essence of the ongoing processes.
For example, in a manuscript found in the temple of Balgon in Asia, the process known to us as tempering steel is described as follows: "Heat the dagger until it glows like the morning sun in the desert, then cool it to the color of royal purple, sticking the blade into the body muscular slave. The strength of the slave, turning into a dagger, gives it hardness. " Nevertheless, despite the rather primitive knowledge, swords and sabers were made even before our era, which had unique properties and were called Damascus. In order to give the weapon high strength and hardness and at the same time provide plasticity that did not allow the sword to be fragile and break from blows, it was made layered. Alternately, in a certain sequence, hard layers of medium or high carbon steel and soft strips of low carbon steel or pure iron were welded together. The result was a weapon with new properties that cannot be obtained without the use of welding. Subsequently, in the Middle Ages, this technology began to be used for the manufacture of highly efficient, self-sharpening plows and other tools.
Forge and foundry welding for a long time remained the main method of joining metals. These methods fit well into the production technology of that time. The profession of a blacksmith-welder was very honorable and prestigious. However, with the development in the XVIII century. machine production, the need to create metal structures, steam engines, various arrangements has increased dramatically. Known welding methods in many cases ceased to meet the requirements, since the lack of powerful heat sources did not allow uniform heating of large structures to the temperatures required for welding. Riveting became the main method of obtaining permanent joints at that time.
The situation began to change at the beginning of the 20th century. after the creation of sources of electrical energy by the Italian physicist A. Volta. In 1802, the Russian scientist V.V. Petrov discovered the phenomenon of an electric arc and proved the possibility of using it to melt metal. In 1881 Russian inventor N.N. Benardos suggested using an electric arc burning between a carbon electrode and a metal part to melt its edges and connect it to another part. He called this method of joining metals "electrohephaestus" in honor of the ancient Greek blacksmith god. It became possible to connect metal structures of any size and various configurations with a strong welded seam. This is how electric arc welding appeared - an outstanding invention of the 19th century. It immediately found application in the most difficult industry at that time - steam locomotive building. Discovery of N.N. Bernardos in 1888 was improved by his contemporary N.G. Slavyanov, replacing the non-consumable carbon electrode with a consumable metal one. The inventor proposed the use of slag, which protected weld from the air, making it more dense and durable.
In parallel, gas welding developed, in which a flame was used to melt the metal, which was formed during the combustion of a combustible gas (for example, acetylene) mixed with oxygen. At the end of the XIX century. this method of welding was considered even more promising than arc welding, since it did not require powerful sources of energy, and the flame, simultaneously with the melting of the metal, protected it from the surrounding air. This made it possible to get enough good quality welded joints. Around the same time, thermite welding began to be used to connect railroad joints. During the combustion of thermites (a mixture of aluminum or magnesium with iron oxide), pure iron is formed and a large amount of heat is released. A portion of thermite was burned in a refractory crucible, and the melt was poured into the gap between the welded joints.
An important stage in the development of arc welding was the work of the Swedish scientist O. Kelberg, who proposed in 1907 to apply a coating to a metal electrode, which, decomposing during arc burning, provided good protection of the molten metal from air and its alloying with the elements necessary for high-quality welding. After this invention, welding began to find more and more applications in various industries. Of particular importance at that time were the works of the Russian scientist V.P. Vologdin, who created the first department of welding at the Polytechnic Institute of Vladivostok. In 1921, the first welding workshop for the repair of ships was opened in the Far East, and in 1924, the largest bridge across the Amur River was repaired using welding. At the same time, tanks for storing oil with a capacity of 2000 tons were created, a generator for the Dneproges was manufactured by welding, which was twice as light as riveted. In 1926, the first All-Union Conference on Welding was held. In 1928, there were 1,200 arc welding units in the USSR.
In 1929, a welding laboratory was opened in Kyiv at the Academy of Sciences of the Ukrainian SSR, which in 1934 was transformed into the Institute of Electric Welding. The institute was headed by a well-known scientist in the field of bridge construction, Professor E.O. Paton, after whom the institute was later named. One of the first major works of the institute was the development in 1939 of automatic submerged arc welding. It made it possible to increase the productivity of the welding process by 6-8 times, improve the quality of the joint, significantly simplify the work of the welder, turning him into an operator for controlling the welding installation. This work of the Institute in 1941 received the State Prize. Submerged arc welding played a huge role during the Great Patriotic War, for the first time in the world becoming the main method of joining armor plates up to 45 mm thick in the manufacture of the T34 tank and up to 120 mm in the manufacture of the IS-2 tank. With a shortage of qualified welders during the war, the increase in welding productivity through automation made it possible to short term significantly increase the production of tanks for the front.
A significant achievement of welding science and technology was the development in 1949 of a fundamentally new method of fusion welding, called electroslag welding. Electroslag welding plays a huge role in the development of heavy engineering, as it allows welding very thick metal (more than 1 m). An example of the use of electroslag welding is the manufacture of a press at Novokramomotorsky Mashinostroitelny Zavod commissioned by France, which can generate a force of 65,000 tons. The press has a height equal to the height of a 12-storey building, and its weight is twice the weight of the Eiffel Tower.
In the 50s. of the last century, industry has mastered the method of arc welding in a carbon dioxide environment, which has recently become the most common welding method and is used in almost all machine-building enterprises.
Welding is actively developing in subsequent years. From 1965 to 1985, the volume of production of welded structures in the USSR increased 7.5 times, the stock of welding equipment - 3.5 times, the output of welding engineers - five times. Welding began to be used for the manufacture of almost all metal structures, machines and structures, completely replacing riveting. For example, the usual a car has more than 5 thousand welded joints. The pipeline, which supplies gas from Siberia to Europe, is also a welded structure with more than 5,000 kilometers of welds. Not a single high-rise building, TV tower or nuclear reactor is manufactured without welding.
In the 70-80s. new methods of welding and thermal cutting are being developed: electron beam, plasma, laser. These methods make a huge contribution to the development of various industries. For example, laser welding allows you to qualitatively connect the smallest parts in microelectronics with a diameter and thickness of 0.01-0.1 mm. The quality is ensured by the sharp focusing of the monochromatic laser beam and the finest dosage of the welding time, which can last from 10 to 6 seconds. Mastering] laser welding made it possible to create a whole series of new element base, which in turn made it possible to manufacture new generations of color televisions, computers, control and navigation systems. Electron-beam welding has become an indispensable technological process in the manufacture of supersonic aircraft and aerospace facilities. The electron beam makes it possible to weld metals up to 200 mm thick with minimal structural deformations and a small heat-affected zone Welding is the main technological process in the manufacture sea vessels, platforms for oil production, submarines. The modern nuclear submarine, which is about 200 m high and 12-storey high, is a fully welded structure made of high-strength steels and titanium alloys.
Without welding, the current achievements in the space field would not have been possible. For example, the final assembly of the missile system is carried out in a welded assembly shop weighing about 60 thousand and 160 m high. The rocket containment system consists of welded towers and masts with a total weight of about 5 thousand tons. All critical structures on the launch pad are also welded. Some of them have to work in very difficult conditions. The impact of a powerful flame at the launch of a rocket takes on a welded flame separator weighing 650 tons, 12 m high. Complex welded structures are fuel storage tanks, a system for supplying it to tanks and the fuel tanks themselves. They must withstand enormous hypothermia. For example, a liquid oxygen tank has a capacity of over 300,000 liters. It is made with a double wall - from stainless and low carbon steel. The diameter of the outer sphere is 22 m. Tanks for liquid hydrogen are designed in a similar way. The pipeline for supplying liquid hydrogen is welded from nickel alloy, it is inside another aluminum alloy pipeline. The pipelines for supplying kerosene and superactive fuel are welded from stainless steel, and the pipeline for supplying oxygen is made of aluminum.
With the help of welding, multi-ton BelAZs and MAZs, tractors, trolleybuses, elevators, cranes, scrapers, refrigerators, televisions and other industrial products and consumer goods are manufactured.
1. TECHNOLOGICAL SECTION
1 Description of the welded structure and its purpose
The fan housing works in particularly harsh conditions. Subjected to direct impact of dynamic and vibration loads.
The fan housing is made up of
Pos 1 Body 1 pc
V \u003d π * D * S * H \u003d 3.14 * 60.5 * 0.8 \u003d 151.98 cc.
Q \u003d ρ * V \u003d 7.85 * 151.98 \u003d 1193.01 gr. = 1.19 kg
Pos 2 Flange 2 pcs.
fan welding deformation arc
V \u003d π * (D out 2. - D int 2) * s \u003d 3.14 * (64.5 2 -60.5 2) * 1 \u003d 1570 cu. cm
Q \u003d ρ * V \u003d 7.85 * 1570 \u003d 12324.5 gr. = 12.33 kg.
Pos 3 Ear 2 pcs
V \u003d h + l + s \u003d 10 * 10 * 0.5 \u003d 50 cu. cm
Q \u003d ρ * V \u003d 7.85 * 50 \u003d 392.5 g \u003d 0.39 kg
Cross-sectional area of the weld
t. sh. \u003d 0.5K² + 1.05K \u003d 0.5 * 6² + 1.05 * 6 \u003d 24.3 sq mm
2 Weldment material justification
Chemical composition of steel
Equivalent carbon content
Ce \u003d Cx + Cp
Сх - chemical equivalent of carbon
Сх = С + Mn/9 + Cr/9 + Mo/12 = 0.16 +1.6/9 + 0.4/9 = 0.38
Ср - correction to carbon equivalent
Cp \u003d 0.005 * S * Cx \u003d 0.005 * 8 * 0.38 \u003d 0.125
Preheat temperature
T p \u003d 350 * \u003d 350 * 0.25 \u003d 126.2 degrees.
1.3 Specification for the fabrication of a welded structure
The fan housing works in particularly harsh conditions. Subjected to direct impact of dynamic and vibration loads.
4 Determining the type of production
The total weight of the spar is 32.07 kg. With a production program of 800 pcs, we select the serial type of production
At serial production type of production is characterized by the use of specialized assembly and welding fixtures, welding of units is carried out on stationary workers
5 Selection and justification of assembly and welding methods
This design is made of 16G2AF steel, which belongs to the group of well-welded steels. When welding, preheating up to 162 degrees and subsequent heat treatment is required.
Steel is welded by all types of welding. The thickness of the parts to be welded is 10 mm, which allows welding in a carbon dioxide environment with wire Sv 08 G2S
1.6 Determination of welding modes
sv \u003d h * 100 / Kp
where: h - penetration depth
Kp - coefficient of proportionality
c in \u003d 0.6 * 10 * 100 / 1.55 \u003d 387 A
Arc voltage
20 + 50* Ib* 10⁻³ / d⁰² V
20 + 50 *387 *10 ⁻³ / 1.6⁰² = 20 + 15.35 = 35.35 V
Welding speed
V sv \u003d K n * I sv / (ρ * F * 100) m / h =
1*387/7.85*24.3*100 = 34.6 m/h
where K n - surfacing coefficient g / A * h ρ is the density of the metal, taken for carbon and low alloy steels, equal to 7.85 g/cm3; F is the cross-sectional area of the deposited metal. mm 2 7 Choice welding consumables
Steel 16G2AF is welded by any type of welding using various kinds welding materials. Therefore, we use wire SV 08 G 2 S for welding. SV 08 G2S wire has good weldability, low emission of welding fumes, and low price. 7.1 Consumption of welding consumables The consumption of electrode wire when welding in CO2 is determined by the formula G e. pr. \u003d 1.1 * M kg M - mass of deposited metal, M = F * ρ * L * 10 -3 kg M t. sh. \u003d 0.243 * 7.85 * 611.94 * 10 -3 \u003d 1.16 kg Consumption of electrode wire G e. pr. \u003d 1.1 * M \u003d 1.1 * 1.16 \u003d 1.28 kg Consumption of carbon dioxide G co2 \u003d 1.5 * G e. pr. \u003d 1.5 * 1.28 \u003d 1.92 kg Electricity consumption W \u003d a * G e. etc. \u003d 8 * 1.28 \u003d 10.24 kW / h a \u003d 5 ... 8 kW * h / kg - specific energy consumption per 1 kg of deposited metal 8 Selection of welding equipment, technological equipment, tools MAGSTER WELDING SYSTEM · Professional welding system with the taken-out 4th roller giving mechanism of the well-known quality Lincoln Electric at the price of the best Russian analogues. · Welding in shielding gases with solid and flux-cored wires. · With success it is applied to welding of structural low-carbon and stainless steels, and also to welding of aluminum and its alloys. · Step-by-step welding voltage adjustment. · Smooth adjustment of giving of a wire. · Gas pre-purging. · Thermal overload protection. · Digital voltage indicator. · High reliability and easy operation. · Synergic system of the welding process - after loading the type of wire and diameter, the feed rate and voltage are matched automatically by the microprocessor, (for mod. 400,500). · Many functional liquid crystal display - displaying the parameters of the welding process (for mod. 400, 500). · Water cooling system (for models with index W) . · All models are equipped with a socket for connecting a gas heater (the heater is supplied separately). · Designed in accordance with IEC 974-1. Protection class IP23 (outdoor operation). · Supplied as ready-to-use kits and include: power source, feeder with transport trolley, connecting cables 5 m, mains cable 5 m, welding torch "MAGNUM" 4.5 m long, work clamp. · AGSTER 400 plus MAGSTER 500 w plus MAGSTER 501 w Maximum power consumption, mains 380 V. 14.7 kW. 17 kW. 16 kW. 24 kW. 24 kW. Welding current at 35% duty cycle. 315 A. 400 A. 400 A. 500 A. 500 A. Welding current at 60% duty cycle. 250 A. 350 A. 350 A. 450 A. 450 A. Welding current at 100% duty cycle. 215 A. 270 A. 270 A. 350 A. 450 A. Output voltage. 19-47 V. 18-40 V. 18-40 V. 19-47 V. 19-47 V. Weight without cables. 88 kg 140 kg 140 kg 140 kg 140 kg TECHNICAL PARAMETERS OF THE WIRE FEEDER · Wire feed speed. 1-17 m/min 1-24 m/min 1-24 m/min 1-24 m/min 1-24 m/min Wire diameters. 0.6-1.2 mm 0.8-1.6 mm 0.8-1.6 mm 0.8-1.6 mm 0.8-1.6 mm Weight without torch. 20 kg. 20 kg. 20 kg. 9 Definition technical standards time for assembly and welding Calculation of technical norms of assembly time and assembly welding.
Parameter Time limit min Time min Source Clean the places for welding from oil, rust and other contaminants. 0.3 per 1 m of the seam Install child pos 2 in fixture. Children's weight 12.33 kg Set children pos. 1 on det pos 2 Grab det poses 1 to det poses 3 for 3 potholders 0.09 1 tack Set children pos. 2 on det pos 1 Children's weight 12.33 Grab det poses 2 to det poses 1 for 3 potholders 0.09 1 tack Install 2 children pos. 3 on det pos 1 Children's weight 0.39 Grab 2 det pos 3 to det pos 1 for 4 potholders 0.09 1 tack Remove the assembly unit and put it on the table of the welder Sat weight units 32.07 kg L seam = 1.9 m 1.72 min / m seam Weld the edges of children pos 1 to each other L seam = 0.32 m 1.72 min / m seam Weld child pos 2 to child pos 1 L seam = 1.9 m 1.72 min / m seam Clean the weld seam from spatter. Lzach = 4.12 m 0.4 min/m seam Worker control, foreman Remove assembly unit Table 1
table 2 Time to install parts (assembly units) when assembling metal structures for welding
Assembly view Part weight, assembly unit fixator Table 3 Tack time
Thickness of metal or legs, mm Tack length, mm Time for one tack, min Time to remove assembly units from the fixture and put them into storage
Basic time for welding 1 m. seam F - cross-sectional area of the weld ρ - specific density of the deposited metal, g / cu. cm. a - deposition coefficient a \u003d 17.1 g / a * hour That. t.sh = = 1.72 min / 1 m seam 10 Calculation of the amount of equipment and its loading Estimated amount of equipment C p = = = 0.09 T gi - the annual complexity of the operation, n-hour; T gi = = = 308.4 n-hour F d o - annual actual fund of equipment operation F d o \u003d (8 * D p + 7 * D s) * n * K p \u003d (8 * 246 + 7 * 7) * 2 * 0.96 \u003d 3872.6 hours D p, D s - the number of working days per year, respectively, with full duration and reduced; n is the number of work shifts per day; K p - coefficient taking into account the time the equipment is under repair (K p \u003d 0.92-0.96). Load factor K z = = = 0.09 Cp is the estimated amount of equipment; Spr - accepted amount of equipment Spr = 1 11 Calculation of the number of employees The number of main workers directly involved in the performance of technological operations is determined by the formula Ch o.r. ===0.19 T g i - annual labor intensity, n-hour; F d r - the annual actual fund of the working time of one worker, in hours; K in - coefficient of performance of production standards (K in \u003d 1.1-1.15) Annual effective fund of working time of one worker F dr \u003d (8 * D p + 7 * D s) * K nev \u003d (8 * 246 + 7 * 7) * 0.88 \u003d 1774.96 hours where D p, D s - the number of working days per year, respectively, with full duration and reduced; K nev - coefficient of absenteeism by good reasons(Knev = 0.88) 12 Methods for dealing with welding deformations The whole complex of measures to combat deformations and stresses can be divided into three groups: Activities that are implemented before welding; Activities in the welding process; Activities carried out after welding. Deformation control measures applied before welding are implemented at the design stage of the welded structure and include the following measures. Structural welding should have a minimum amount of deposited metal. The legs should not exceed the design values, butt welds should be made without cutting edges, if possible, the number and length of welds should be the minimum allowable. It is necessary to use welding methods and modes that provide minimal heat input and a narrow heat-affected zone. In this regard, welding in CO 2 is preferable manual welding, and electron beam and laser welding is preferable to arc welding. Welds should be as symmetrical as possible on the welded structure, it is not recommended to place welds close to each other, to have a large number of intersecting seams, without the need to use asymmetrical grooves. In structures with thin-walled elements, it is advisable to place the seams on rigid elements or near them. In all cases where there is concern that undesirable deformations will occur, the design is carried out in such a way as to ensure the possibility of subsequent straightening. Measures used in the welding process Rational sequence of applying welds, on the structure and along the length. When welding alloy steels and steels with a high carbon content, this can lead to the formation of cracks, so the stiffness of the fasteners must be assigned taking into account the metal being welded. Preliminary deformation of welded parts. Compression or rolling of the weld, which is carried out immediately after welding. In this case, the zone of plastic deformations of the shortening is subjected to plastic upsetting along the thickness. 1.13 Choice of quality control methods The operational control system in welding production includes four operations: control of preparation, assembly, welding process and welded joints. .) Control of the preparation of parts for welding It provides for the control of the processing of the front and back surfaces, as well as the end edges of the parts to be welded. The surfaces of the edges to be welded must be cleaned from dirt, preservative grease, rust and scale, to a width of 20 - 40 mm from the joint. .) Assembly - installation of the parts to be welded in the appropriate position relative to each other when welding tee joints control the perpendicularity of the parts to be welded. When checking the quality of tacks, attention should be paid to the condition of the surface and the height of the tacks. .) Welding process control includes visual observation of the process of metal melting and weld formation, control of the stability of the mode parameters and equipment performance. .) Inspection of welded joints. After welding, welded joints are usually visually inspected. The weld and the heat-affected zone are subjected to inspection. Usually the control is carried out with the naked eye. When detecting surface defects less than 0.1 mm in size, optical devices are used, for example, a magnifier of 4-7 times magnification. The main structural elements of welds are: seam width height of reinforcement and penetration; smooth transition from reinforcement to base metal, etc. 1.14 Safety, fire prevention and environmental protection The harmful effects of welding and thermal cutting on a person and industrial injuries during welding are caused by various reasons and can lead to temporary disability, and in unfavorable circumstances, to more serious consequences. Electric current is dangerous to humans, and alternating current is more dangerous than direct current. The degree of danger of electric shock depends mainly on the conditions for including a person in the circuit and the voltage in it, since the strength of the current flowing through the body is inversely proportional to the resistance (according to Ohm's law). For the minimum design resistance of the human body, 1000 ohms are taken. There are two types of electric shock: electric shock and trauma. Damaged by electric shock nervous system, muscles of the chest and ventricles of the heart; paralysis of the respiratory centers and loss of consciousness are possible. Electrical injuries include burns to the skin, muscle tissues, and blood vessels. The light radiation of the arc acting on unprotected organs of vision for 10-30 s within a radius of up to 1 m from the arc can cause severe pain, lacrimation and photophobia. Prolonged exposure to arc light under such conditions can lead to more serious diseases - (electrophthalmia, cataracts). The harmful effect of the rays of the welding arc on the organs of vision affects at a distance of up to 10 m from the place of welding. Harmful substances (gases, vapors, aerosols) are released during welding as a result of physical and chemical processes that occur during the melting and evaporation of the metal being welded, components of electrode coatings and welding fluxes, as well as due to the recombination of gases under the action of high temperature welding heat sources. The air environment in the welding zone is polluted by welding aerosol, which consists mainly of oxides of the metals being welded (iron, manganese, chromium, zinc, lead, etc.), gaseous fluorine compounds, as well as carbon monoxide, nitrogen oxides and ozone. Prolonged exposure to welding aerosol can lead to occupational intoxication, the severity of which depends on the composition and concentration of harmful substances. The explosion hazard is due to the use of oxygen, shielding gases, combustible gases and liquids in welding and cutting, the use of gas generators, compressed gas cylinders, etc. Chemical compounds of acetylene with copper, silver and mercury are explosive. The danger is backstroke in the gas network when working with low-pressure burners and cutters. When repairing used tanks and other containers for storing flammable liquids, special measures are necessary to prevent explosions. Thermal burns, bruises and injuries are caused by the high temperature of welding heat sources and significant heating of the metal during welding and cutting, as well as limited visibility of the surrounding space in connection with the production of work using shields, masks and goggles with light-protective glasses. Unfavorable meteorological conditions affect welders (carvers) - builders and assemblers for more than half the time of the year, since they have to work mainly in the open air. The increased fire hazard during welding and cutting is due to the fact that the melting point of metal and slag significantly exceeds 1000 ° C, and liquid combustible substances, wood, paper, fabrics and other flammable materials ignite at 250-400 ° C. 2. ELECTRICAL SAFETY PRECAUTIONS It is necessary to reliably ground the body of the welding machine or installation, the clamps of the secondary circuit of welding transformers used to connect the return wire, as well as the products and structures to be welded. 2. It is forbidden to use ground loops, pipes of sanitary facilities, metal structures of buildings and technological equipment. (During construction or repair, metal structures and pipelines (without hot water or explosive atmosphere) can be used as a return wire of the welding circuit and only in cases where they are welded.) 4. It is necessary to protect the welding wires from damage. When laying welding wires and each time they are moved, prevent damage to the insulation; contact of wires with water, oil, steel ropes, sleeves (hoses) and pipelines with combustible gases and oxygen, with hot pipelines. Flexible electric wires for controlling the scheme of the welding installation, with their considerable length, must be placed in rubber sleeves or in special flexible multi-link structures. 6. Only electrical personnel are entitled to repair welding equipment. Do not repair live welding equipment. When welding in especially dangerous conditions (inside metal containers, boilers, vessels, pipelines, in tunnels, in closed or basement rooms with high humidity, etc.): welding equipment must be outside of these containers, vessels, etc. electric welding installations must be equipped with a device for automatically switching off the open-circuit voltage or limiting it to a voltage of 12V for no more than 0.5 s after welding is stopped; allocate a safety worker, who must be outside the tank, to monitor the safety of the welder. The welder is provided with a mounting belt with a rope, the end of which must be at least 2 m long in the hands of the insurer. Near the insurer there should be a device (knife switch, contactor) to turn off the mains voltage from the power source of the welding arc. Do not allow welders to arc welding or cutting in wet gloves, shoes and overalls. 9. Cabinets, consoles and beds of contact welding machines, inside which there is equipment with open current-carrying parts under voltage, must have a lock that provides voltage relief when they are opened. Pedal start buttons of contact machines must be grounded and the reliability of the upper guard, which prevents involuntary switching on, must be monitored. 10. In case of electric shock, you must: urgently turn off the current with the nearest switch or separate the victim from current-carrying parts using dry improvised materials (pole, board, etc.) and then put him on a litter; immediately call for medical assistance, given that a delay of more than 5-6 minutes can lead to irreparable consequences; if the victim is unconscious and does not breathe, release him from tight clothing, open his mouth, take measures against falling of the tongue and immediately begin artificial respiration, continuing it until the doctor arrives or normal breathing is restored. 3. PROTECTION AGAINST LIGHT RADIATION To protect the eyes and face of the welder from the light radiation of an electric arc, masks or shields are used, into the viewing holes of which protective glass filters are inserted that absorb ultraviolet rays and a significant part of light and infrared rays. From splashes, drops of molten metal and other contaminants, the light filter is protected from the outside with ordinary clear glass installed in the viewing hole in front of the light filter. Light filters for arc welding methods are selected depending on the type of welding work and the welding current, using the data in Table. 3. When welding in a shielding inert gas environment (especially when welding aluminum in argon), it is necessary to use a darker light filter than when welding with an open arc at the same current strength. Table 3. Light filters for eye protection from arc radiation (OST 21-6-87)
2. To protect the surrounding workers from the light radiation of the welding arc, portable shields or screens made of fireproof materials are used (with a non-permanent workplace of the welder and large products). In stationary conditions and with relatively small sizes of welded products, welding is performed in special booths. 3. To reduce the contrast between the brightness of the arc light, the surface of the walls of the workshop (or cabins) and equipment, it is recommended to paint them in light colors with diffuse reflection of light, and also to ensure good illumination of the surrounding objects. If the eyes are damaged by the light radiation of the arc, you should immediately consult a doctor. If it is not possible to obtain a fast medical care make lotions on the eyes with a weak solution of baking soda or tea leaves. Protection against harmful gas emissions and aerosol To protect the body of welders and cutters from harmful gases and aerosols released during the welding process, it is necessary to use local and general ventilation, supply clean air to the breathing zone, as well as low-toxic materials and processes (for example, use rutile-type coated electrodes, replace welding with coated electrodes for mechanized welding carbon dioxide etc.). 2. When welding and cutting small and medium-sized products on permanent places in workshops or workshops (in booths) it is necessary to use local ventilation with a fixed side and bottom suction (welder table). When welding and cutting products at fixed places in workshops or workshops, local ventilation with an intake funnel mounted on a flexible hose must be used. Ventilation should be performed by supply and exhaust with the supply of fresh air to the welding areas and its heating in cold weather. When working in closed and semi-closed spaces (tanks, tanks, pipes, compartments of sheet structures, etc.), it is necessary to use local suction on a flexible hose to extract harmful substances directly from the place of welding (cutting) or provide general ventilation. If it is impossible to carry out local or general ventilation, clean air is forcibly supplied to the breathing zone of the worker in the amount of (1.7-2.2) 10-3 m3 per 1 s, using a mask or helmet of a special design for this purpose. LITERATURE 1. Kurkin S. A., Nikolaev G. A. Welded structures. - M.: Higher School, 1991. - 398s. Belokon V.M. Production of welded structures. - Mogilev, 1998. - 139s. Blinov A.N., Lyalin K.V. Welded structures - M .: - "Stroyizdat", 1990. - 352s Maslov B.G. Vybornov A.P. production of welded structures -M: Publishing Center "Academy", 2010. - 288 p.
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