The heating plates of the presses are rectangular plates. They are made from solid steel plates, ground and milled on all sides. The set consists of two plates. The number of heaters in the mold is determined by its mass (or heat transfer surface area), operating temperature and heater power. Heating plates can be heating elements, ohmic or induction.
The Orenburg plant of pressing machines produces heating plates for hydraulic press brands DG, DE, P, PB.
The heating plates of the presses are rectangular steel plates with a thickness of 70 mm. They are made from solid steel plates, ground and milled on all sides.
The heating plate consists of two parts fastened together, in one of which grooves are milled for laying heating elements (heating elements). The power of one heating element is from 0.8 to 1.0 kW, voltage is 110 V. The plates have grooves for placing heating elements with a diameter of 13 mm. Two heaters connected in series are installed on one phase.
The quality of plastic products is greatly influenced by the temperature at which they are made. Temperature regime mold depends on the structure of the processed material and features technological process chosen to receive this product.
The set consists of two plates. The number of heaters in the mold is determined by its mass (or heat transfer surface area), operating temperature and heater power. Depending on the required heating power, 6 or 12 heating elements are installed on each plate. Contact clamps are covered with casings.
For heating molds, electric heaters are mainly used, based on the use of resistance elements of various designs. The space around the spiral is securely isolated, which increases its service life. The electric heater is located in the thickness of the mold at a distance of 30-50 mm from the forming surface, because at a closer location, local overheating is possible, which will lead to the marriage of products.
Temperature control of heating plates is ensured by the use of thermocouples THC. A heat-resistant wire laid in a metal hose safely connects the plates to the cabinet.
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For heating removable molds heating plates, in which channels are drilled for the location of tubular electric heaters. The hotplates are attached to the press plates via thermal pads to reduce heat transfer to the press. For stationary molds, heating plates are attached to the bottom of the die and to the top of the punch.
Recently, induction heating of molds by electric current of industrial frequency has become widespread. With induction heating, power consumption is reduced, mold heating time is reduced, and the service life of electric heaters is increased.
For purchase inquiries heating plates for presses contact via form feedback or by phone numbers listed in the contacts.
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Form of payment, order of delivery, guarantee of heating plates:
- The sale is carried out on the terms of 50% prepayment when ordering plates for production and 100% prepayment if they are in stock.
- Delivery is carried out transport companies Supplier or Buyer by agreement, as well as by railway transport.
- Transportation costs for the delivery of goods are paid by the Buyer.
- Warranty for all new products 12 months, for products after overhaul 6 months.
Please note that the information on the site is not a public offer.
When designing molds for hot pressing, the determining factors are the geometric shape and dimensions of the product, as well as the method of heating and the conditions for creating a protective atmosphere. Hot pressing produces products of mostly simple shapes, so the design of the mold is simple. The main difficulty lies in
boron of the mold material, which must have sufficient strength at the pressing temperatures, must not react with the powder to be pressed.
At pressing temperatures of 500...600 °C, it is possible to use heat-resistant steels nickel based. AT this case high pressing pressures (150...800 MPa) can be used. To prevent the connection of the pressed powder with the inner walls of the matrix and reduce friction, the shaping surfaces are coated with a high-temperature lubricant. However, the choice of lubricants is limited, since almost all of them volatilize during the hot pressing process. Mica and graphite are mainly used as lubricants.
Mica is used at low pressing temperatures. Graphite retains high anti-friction properties at high temperatures. It is used in the form of a suspension of flake or silver graphite in glycerin or liquid glass. Combined molds are also used from a graphite matrix lined inside with low-carbon steel, and the steel insert is chromium-plated to avoid interaction with the matrix graphite. For the manufacture of dies and punches operating at pressing temperatures (800 ... 900 ° C), it is possible to use hard alloys. In the case of high temperatures of hot pressing (2500...2600 °C), the only material for molds is graphite. Compared with other materials, it has good electrical characteristics, is easy to process, and creates a protective atmosphere on the surface of the product by burning out during hot pressing. Since the pressing force decreases with increasing process temperature, the strength of graphite matrices is in most cases quite sufficient.
For the manufacture of molds, graphite with a fine-grained structure and no residual porosity is used, otherwise the pressed powder may penetrate into the pores, which degrades the quality of products due to increased friction between the walls of the mold and the powder.
Since the service life of graphite molds is rather short and it is extremely difficult to completely avoid carburization of pressed products, a special multi-component nitrate has been developed.
Kel alloy for molds in which powders of titanium, zirconium, thorium and other metals are pressed. The strength of the alloy at a temperature of 950 ... 1000 ° C is approximately 40-50 times higher than the strength of pure titanium. For the manufacture of molds, oxides and silicates of refractory metals, in particular zirconium oxide, are also used.
There are the following methods of electric heating of powders during hot pressing:
P direct heating by passing an electric current directly through the mold or compressible powder;
P indirect heating by passing current through various resistance elements surrounding the mold;
P direct heating of the mold and powder with high frequency currents (HF) or induction heating;
P indirect induction heating of the shell in which the mold is placed.
The hot pressing mold is developed depending on the heating method. On fig. 3.22 shows the designs of molds for double-sided hot pressing in combination with heating.
Rice. 3.22. Design diagrams of molds for double-sided hot pressing in combination with heating: a- indirect heating; 6 - direct heating when current is supplied to the punches; in - simple heating when current is applied to the matrix; G - induction heating of graphite matrix; d - induction heating of the powder in a ceramic mold; 1 - heater; 2 - powder; 3 - briquette; 4 - matrix; 5,6 - punches; 7 - insulation; 8 - graphite contact; 9 - graphite punch; 10 - graphite matrix; 11 - ceramics; 12 - inductor; 13 - ceramic punch; 14 - ceramic matrix
With indirect heating (Fig. 3.22, a) the design of the mold becomes more complicated due to the need to use additional heaters. With direct heating of punches by passing current (Fig. 3.22, b) possible overheating of the punches and, as a result, curvature. Current supply to the matrix (Fig. 3.22, in) provides more uniform heating of the powder, but the mold is structurally more complicated. Induction heating of the graphite matrix is used (Figure 3.22, G) and a ceramic matrix (Figure 3.22, E).
The invention relates to a mold containing the first part, including a body (111), with which the molding zone (112) is connected to form a mechanical interface (115) between the specified molding zone and the housing, and containing inductors (132) located in the so-called longitudinal direction in the cavities (131) between said interface (115) and the molding zone (112), and a cooling device (140) located on the interface between the molding zone and the housing. EFFECT: invention makes it possible to exclude temperature gradients, which lead to mold deformation. 14 w.p. f-ly, 6 ill.
The invention relates to a mold with rapid heating and cooling. In particular, the invention relates to a device for induction heating and rapid cooling of a mold intended for injection molding of a plastic material or metal in a liquid or pasty state.
Document EP 1894442, filed in the name of the Applicant, describes a mold equipped with an induction heating device and a cooling device due to the circulation of a heat transfer fluid. This known device contains a mold consisting of a fixed part and a movable part. Each of the parts is configured to accommodate an induction heating circuit and a cooling circuit. Each of these parts contains a body to which is connected a part that forms a molding surface that gives the final shape to the part cast in this mold. For each part of the mold, the molding surface is a heated and cooled surface, while said surface comes into contact with the material of the molded part. The inductors are installed in the cavities under the said molding surface. Most often, these cavities are made by cutting grooves on the underside of said molding zone at the interface between this zone and the mold body. The cooling circuit is made in the form of channels drilled in the body and more remote from the molding surface. This cooling circuit simultaneously cools this body, which in a common embodiment is made of a material that is not very sensitive to induction heating, and cools the mold surface. Finally, the body of each part is mechanically connected to the stand.
This configuration gives good results but is difficult to use when the mold is large or when the mold surface has complex shape. Under these conditions, the temperature gradients that appear both during heating and during cooling lead to deformation of the mold as a whole, on the one hand, and, in particular, to differential deformation between the molding zone and the body, this differential deformation leads to poor contact between these two elements and degrades the quality of cooling by creating thermal barriers between these two elements.
The objective of the invention is to eliminate the above disadvantages inherent in known technical solutions by creating a mold containing the first part, which includes a body with which the molding zone is connected, forming a mechanical interface between the said molding zone and the housing, and containing inductors, located in the so-called longitudinal direction in the cavities between said interface and the molding zone, and a cooling device located on the interface between the molding zone and the housing. Thus, since the heating and cooling devices are located as close as possible to the interface, differential deformations do not affect the thermal conductivity between the heating and cooling devices and the forming zone. The inductors can be easily installed in shallow grooves that form cavities after the mold zone is connected to the body, thus reducing the cost of machining such a mold.
Preferably, the invention is carried out in accordance with the embodiments described below, which should be considered separately or in any technically feasible combination.
Preferably, according to an exemplary embodiment, the inventive mold comprises, at the interface between the body and the molding zone, a tape made of a heat-conducting material and configured to compensate for differences in shape between the molding zone and the housing.
According to a particular embodiment, the tape is made of graphite.
According to a version of this embodiment, said tape is made of Ni.
According to another version of this embodiment, said tape is made of Cu.
Preferably, said tape is soldered to the forming zone.
According to a second embodiment compatible with the first, the inductors are inserted into hermetic shells that can withstand temperatures of at least 250° C. and the cooling device comprises a heat transfer fluid flowing in cavities around the inductors.
According to the third embodiment, the cooling device uses the circulation of the dielectric fluid in the cavities around the inductors.
Preferably the dielectric fluid is an electrically insulating oil.
According to the fourth embodiment, the cooling device comprises a cavity filled with a fluid that can change phase under the action of temperature, and whose latent heat of phase change is sufficient to absorb the heat of the molding zone at a certain temperature.
According to the fifth embodiment, the cooling device injects gas into the cavities around the inductors.
Preferably, the gas is injected in a transverse direction relative to the longitudinal direction. Thus, a swirl is formed in the air flow, which contributes to heat exchanges. This swirl depends on the gas injection pressure and on the angle between the injection channel and the longitudinal direction of the cavities.
Preferably, according to this last embodiment, the cooling device of the inventive mold comprises several gas injection points along the length of the cavity in the longitudinal direction.
Preferably the gas is air at a pressure greater than 80 bar. The use of air as a cooling fluid simplifies the use of the device, in particular with regard to sealing problems.
According to a particular embodiment, the inventive mold contains a second induction circuit spaced from the first one relative to the interface and powered by a separate generator.
According to a preferred embodiment, the body and the mold zone are made of an INVAR-type iron-Fe-nickel-Ni alloy whose Curie point is close to the transformation temperature of the cast material. Thus, if the material of the body and mold zone is ferromagnetic, that is, sensitive to induction heating, it has a low coefficient of expansion. When the temperature of the material approaches the Curie point when the material is heated, it becomes less sensitive to induction heating. Thus, this embodiment makes it possible to control the differential expansion of the body and the forming zone, and between the body and the mechanical support of said body on the press.
In FIG. 1 shown general example implementation of the claimed mold, cross-sectional view;
in fig. 2 shows a claimed mold according to an embodiment comprising a belt between the mold zone and the body, in cross section;
in fig. 3 shows the first part of a mold according to an embodiment of the invention, where the cooling device comprises a cavity filled with a material that can change phase at a given temperature by absorbing the latent heat of phase change, a cross-sectional view;
in fig. 4 shows part of the claimed mold according to an embodiment of the invention, in which cooling occurs due to the circulation of a heat transfer fluid in the cavities in which the inductors are located, a cross-sectional view;
in fig. 5 shows an exemplary embodiment of a part of the claimed mold containing a cooling device by means of transverse injection of gas under pressure in the cavities in which the inductors are located, a cross-sectional view, while in the sectional plane SS the orientation of the injectors is shown in a longitudinal section;
in fig. 6 shows an exemplary embodiment of a part of the claimed mold containing two spaced apart and separate induction circuits, a cross-sectional view.
As shown in FIG. 1, according to the first embodiment, the claimed mold comprises a first part 101 and a second part 102. The following description will refer to the first part 101. The person skilled in the art can easily apply the embodiments described for this first part 101 to the second part of said mold . According to this exemplary embodiment, the first part 101 is fixed to a mechanical stand 120. Said first mold part comprises a body 111 which is fixed to this mechanical stand 12 and, at its distal end relative to said stand 120, comprises a mold zone 112 connected to said body. 111 with a mechanical fastener (not shown). Thus, there is a mechanical interface 115 between the body and the mold zone. made by cutting grooves on the inside of the molding zone. Cooling device 140, shown here schematically, is also located at interface 115.
As shown in FIG. 2, according to the exemplary embodiment, the inventive mold comprises a band 215 between the interface 115 and the cooler. This tape is made of graphite, nickel Ni or copper Cu, is thermally conductive and can compensate for shape differences between the molding zone 112 and the body 111 at the interface 115 to ensure uniform contact between the body and the molding zone, as well as to ensure good thermal conductivity between them. . The material of the tape is selected depending on the temperature reached during molding. Preferably, the tape is soldered at the interface between the mold zone and the body after the mold is closed, using a mold heating device for soldering. Thus, shape adaptation is ideal.
As shown in FIG. 3, according to another embodiment, the cooling device comprises a cavity 341, 342 which is filled with a material capable of changing phase at a certain temperature, this phase change being accompanied by the absorption of excess latent heat. The phase change is melting or evaporation. Said material is, for example, water.
As shown in FIG. 4, according to another embodiment of the claimed mold, each inductor 132 is placed in a heat-resistant sealed shell 431. Depending on the temperature that the inductors must create, such a shell 431 is made of glass or silica, and it preferably has a closed porosity so that at the same time be airtight and withstand thermal shock when refrigerated. If the temperature reached by the inductors during operation is limited, for example, for the molding of certain plastic materials, said sheath is made of a heat-shrinkable polymer, for example, polytetrafluoroethylene (PTFE or Teflon®) for operating temperatures of inductors up to 260°C. Thus, the cooling device provides for the circulation of a heat transfer fluid, for example water, in the cavities 131 in which the inductors are located, while these inductors are isolated from contact with the heat transfer fluid by their hermetic sheath.
Alternatively, the heat transfer fluid is a dielectric fluid, such as dielectric oil. This type of product is put on the market, in particular, for cooling transformers. In this case, there is no need for electrical isolation of the inductors 132.
As shown in FIG. 5, according to another embodiment, cooling is carried out by injecting gas into the cavity 131 in which the inductors 132 are installed. To improve the cooling efficiency, gas is injected at a pressure of about 80 bar (80.times.10.sup.5 Pa) through several channels 541 evenly distributed in the longitudinal direction. along the inductors 132. Thus, injection is carried out at several points along the inductors through the injection channels 542 transversely to said inductors 132.
In longitudinal section along the SS, the injection channel 542 is oriented so that the direction of the fluid jet in the cavity of the inductor has a component parallel to the longitudinal direction. Thus, by appropriate selection of the discharge angle, efficient cooling is obtained by circulation with a swirl of gas along the inductor 132.
Temperature gradients occurring in particular in a housing mounted on a mechanical stand can lead to warping of the device or to differential strain stresses. Therefore, according to the preferred embodiment, the body 111 and the mold zone 112 are made of an iron-nickel alloy containing 64% iron and 36% nickel, called INVAR and having a low coefficient of thermal expansion at a temperature below the Curie temperature of this material when it is in a ferromagnetic state. , that is, it is sensitive to induction heating.
As shown in FIG. 2, according to the last embodiment, compatible with the previous embodiments, the mold includes a second row 632 of inductors spaced from the first row. The first 132 and second 632 rows of inductors are connected to two different generators. The heat is thus dynamically distributed between the two rows of inductors in order to limit the deformations of the mold parts generated by thermal expansion in combination with thermal gradients occurring in the heating and cooling phase.
1. A mold containing the first part, including a body (111), with which the molding zone (112) is connected to form a mechanical interface (115) between the specified molding zone and the housing, and containing inductors (132) located in the so-called longitudinal direction in the cavities (131) between said interface (115) and the molding zone (112), and a cooling device (140) located on the interface between the molding zone and the housing.
2. The mold according to claim 1, characterized in that it contains, at the interface between the body and the molding zone, a tape (215) made of a heat-conducting material and configured to compensate for differences in shape between the molding zone (112) and the housing (111) .
3. Mold according to claim 2, characterized in that the tape (215) is made of graphite.
4. Mold according to claim 2, characterized in that the strip (215) is made of nickel (Ni) or nickel alloy.
5. Mold according to claim 2, characterized in that the tape (215) is made of copper (Cu).
6. The mold according to claim 1, characterized in that the inductors (132) are inserted into sealed shells (431) configured to withstand a temperature of at least 250°C, while the cooling device contains a liquid heat carrier flowing in cavities ( 131) around the inductors (132).
7. Mold according to claim 1, characterized in that the cooling device (140) is configured to circulate a dielectric fluid in the cavities (131) around the inductors (132).
8. A mold according to claim 7, characterized in that the dielectric fluid is an electrically insulating oil.
9. The mold according to claim. 1, characterized in that the cooling device contains a cavity (341, 342) filled with a fluid, made with the ability to change the phase under the influence of temperature, and the latent heat of the phase transition of which is sufficient to absorb the heat of the molding zone (112) at a certain temperature.
10. Mold according to claim 1, characterized in that the cooling device comprises a gas injection device (541, 542) in the cavity (131) around the inductors (132).
11. A mold according to claim 10, characterized in that the injection of gas is carried out by means of injectors (542) located in the transverse direction relative to the longitudinal direction.
12. A mold according to claim 11, characterized in that it contains several injectors (542) for injecting gas along the length of the cavity (131) in the longitudinal direction.
13. A mold according to claim 10, characterized in that the gas is air injected at a pressure exceeding 80 bar (80⋅10 5 Pa).
14. The mold according to claim 1, characterized in that it contains a second induction circuit (632) spaced from the first (132) induction circuit relative to the interface (115) and powered by a separate generator.
15. A mold according to claim 1, characterized in that the body (111) and the molding zone (112) are made of an iron-nickel alloy of the INVAR type.
The invention relates to mechanical engineering, in particular to heat treatment parts, and can be used for the manufacture of inductors for devices for high-frequency hardening of products widely used in various sectors of the national economy.
The invention relates to a mold containing a first part, including a housing, with which the molding zone is connected to form a mechanical interface between the specified molding zone and the housing, and containing inductors located in the so-called longitudinal direction in the cavities between the specified interface and molding zone, and a cooling device located at the interface between the molding zone and the body. EFFECT: invention makes it possible to exclude temperature gradients, which lead to mold deformation. 14 w.p. f-ly, 6 ill.
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Press structure:
Press series PL is a welded steel structure of beams, which provides greater strength, rigidity and reliability of the equipment.
The fixed and movable plates are also a welded steel structure.
The press is equipped with a "rack-and-pinion" system, which makes it possible to ensure the parallelism of the plates during lifting and lowering.
All perimeter presses are equipped with an emergency safety cord. Thanks to this system, the movable platen can be stopped or blocked from either side of the press.
All flat surfaces of the press were processed on CNC metalworking machines, which made it possible to ensure high precision press assembly. 
Types of hot press plates PL:
1. Prefabricated plate
Max. temperature 110°C, max. operating pressure 3-4 kg/cm2, heat carrier pressure 0.5 atm.
Comprises:
A. Aluminum coating for best quality surface and better thermal conductivity.
B. Flat steel sheet.
C. Heating medium coil, water/oil, welded from rectangular tubes
D. Coil reinforcement.
E. Flat steel plate, intermediate plate only
F. Insulating material.
2. Milled steel plates
Max heating temperature 150°C.
Surface pressure up to 10 kg/cm2
3. Perforated cast steel plate
Max. temperature 250°C, max working pressure 30-80 kg/cm2, coolant pressure 10 atm.
Consists of a single steel plate with drilled holes for coolant circulation.
The pressing surface is normally flat and can be coated with aluminum or heat-resistant nylon (mylar) on request; primed and polished surface available for special purposes.
4. Electric stove
Max. temperature 120°C, max working pressure 5 kg/cm2.
Consists of a 9mm aluminum plate into which the heating elements are inserted; at the bottom is a base plate with reinforced pipes inside.
Plate heating:
Water boiler, maximum heating temperature 100 C
Oil boiler, maximum heating temperature 120 C
Plates with electric heating, heating elements, maximum heating temperature 120 C
A heat-insulating sheet is placed between the press body and the heating plates. 
Hydraulic system:
- All press cylinders are chrome plated for smooth lifting/lowering and longer seal and piston life.
- The hydraulic system is complemented by a 2-stage oil pump to ensure good noise isolation and better lubrication of rotating parts.
- Quick press open/close hydraulic pump (high pressure 38 l/min), duty cycle pump (low pressure 2.3 l/min)
- central hydraulic unit, equipped with the following mechanical safety valves mounted on the oil tank:
- closing safety valve, it contributes to energy saving and prevents oil from overheating.
- overpressure safety valve, it helps to avoid the situation when there is too high pressure in hydraulic system in the event of an electrical and/or electronic short circuit.
- reverse pressure retention (retaining valve)
- pressure release valve (pre-release valve).
- large volume oil release control magnet.
Control Panel:
All functions of the press are controlled from the main panel. All presses are equipped automatic device pressure recovery. This device allows you to keep a constant predetermined pressure in the press.
All presses are equipped with an opening timer for automatic opening of the plates. From the control panel, the operator can set or change any parameters. Closing of the press plates is carried out by pressing two buttons at the same time, which guarantees the safety of the operator.
Specifications:
- Dimensions of plates 2500 x 1300 mm
- 4 cylinders with a diameter of ø 70 mm
- Stroke 400 mm
- press opening 400 mm
- total pressure 70 tons
- special pressure on 100% of the plate surface 1.5 kg/cm2.
- loading / unloading on both sides 2500 mm
- press opening timer
- safety cord around the entire press
- overall dimensions of the press 3200x1600x1800 mm
- the total weight of the press is about 3000 kg
- CE regulations
Options:
Increased piston stroke up to 650 mm instead of 400 mm
Press control panel LOGIC CONTROL
Manual shutdown of a pair of pistons
Electrical shutdown of a pair of pistons
Collapsible design of the press
Parallelism control around the perimeter of the press
Increasing the heating power
Press preheating system by timer
Press supplied without heating system 
Control panel LODIC CONTROL (PLC):
The main control panel is equipped with a color touch screen digital monitor for quick installation:
temperature indicator, controls the heating temperature of the plates.
pressure force adjustment sensor with automatic pressure recovery system.
main button on/off.
indicator light on/off.
systems for daily adjustment of the heating temperature - new system turning the heating on and off depending on the heating temperature of the press.
the process of achieving and maintaining the specified temperature of the shaping element (mold). Cartridge heaters and flat heaters are used to heat molds. The type of heater is selected based on the shape of the available surface for heating (a cylindrical hole is a cartridge heating element, a flat section is a flat heater, respectively).
Molds are usually used to create batches of standard products. Molds for casting are heated using various heating elements, but the most common are electrical resistance heaters.
Mold Heaters are located depending on its design features, including the height of the matrix and the internal structure. It is recommended to place the heater in the mold body at a distance of 30-50 mm from the inner wall. Placing closer to the inner wall than the recommended distance increases the risk of manufacturing defects.
The calculation of the number of required heaters for heating the mold is based on the following data: mold mass (or heat transfer surface area), working temperature and power of the heating element.
Heating of removable molds for casting is carried out using heating plates containing cartridge heaters.
Cartridge heaters for mold heating
Cartridge heaters for mold heating- heating elements that carry out heating in cylindrical holes. These are contact heaters, therefore they require close contact with the heated surface. The voids are filled with mounting paste.
Spiral heaters for heating molds
Spiral heaters for heating molds- These are heaters that have a high power density with relatively small overall dimensions.
Flat Heaters for Heating Molds
Flat Heaters for Heating Molds– resistance electric heaters with a flat surface, which maintain a given temperature of the melt during casting. During the production of the heater, it is possible to make holes in it of the required size in accordance with the design of the injection mold. Requires a tight fit to the mold when heated.