JP2007008036A - Mold assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold assembly constituted so as to suppress the occurrence of a weldline by heating a mold and capable effectively absorbing the expansion/contraction due to the heating/cooling of the mold. <P>SOLUTION: The mold assembly is constituted of a pair of platens 2 and 3 opened and closed relatively, the cavity mold 4 and the core mold 5 respectively embedded in a pair of the platens 2 and 3, the heat source body 9 installed in the cavity mold 4 to heat the cavity mold 4 to a temperature not lower than the thermal deformation temperature of a resin, the water passage 15 provided in the vicinity of the heat source body 9 to cool the cavity mold 4 and the corrugated plate member 25 installed between the side surface of the cavity mold 4 and the platen 2. By this constitution, the expansion/contraction of the cavity mold 4 can be effectively absorbed because the corrugated plate member 25 is bent even if expansion/contraction is produced in the cavity mold 4 by the heating/cooling of the cavity mold 4 and no excess load is applied to the mold assembly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molding tool for resin molding, and more particularly to a molding tool for the purpose of preventing the occurrence of weld lines in molded products.

  A mold apparatus used for general resin molding has a pair of molds, that is, a cavity side mold and a core side mold, and a molten resin is injected into a molding space formed between the two molds. It is the structure which inject | pours and shape | molds.

In such a molding die apparatus, there is a problem that a so-called weld line is generated on the surface of the molded product at a location where the resin flowing at the time of molding joins, and the appearance of the molded product is impaired.
Therefore, conventionally, in order to suppress the occurrence of this weld line, a configuration in which a mold is heated, such as a molding mold apparatus disclosed in Patent Document 1 below, has been proposed. That is, in the molding die apparatus disclosed in Patent Document 1, a heating body is installed in the mold, and a weld line is generated in the molded product by heating the mold to a high temperature with the heating body during molding. I try to prevent that. In this molding die apparatus, a cooling passage is provided in the vicinity of the heating body inside the die, and the heated die is cooled by passing cooling water through the cooling passage. .
JP 2003-33957 A

  In such a mold apparatus, the mold expands when heated to a high temperature, and then contracts when cooled. However, since the conventional mold apparatus is not structured to cope with expansion / contraction by heating / cooling of the mold, an extra burden is placed on the mold apparatus due to repeated expansion / contraction of the mold. There was a concern that it would cause a failure of the device.

  The present invention has been made in view of such a point, and in a molding die apparatus that suppresses generation of a weld line by heating the die, molding capable of absorbing expansion / contraction due to heating / cooling of the die. An object of the present invention is to provide a mold apparatus and solve the above problems.

To achieve the above object, the present invention provides a molding die apparatus for resin molding,
A pair of templates installed to open and close relatively in a state of facing each other;
A cavity side mold and a core side mold mounted so as to be embedded in the pair of mold plates, respectively,
A heat source body that is installed inside the cavity side mold and heats the cavity side mold to a temperature higher than the thermal deformation temperature of the resin;
A water passage that is provided in the vicinity of the heat source body inside the cavity-side mold, and that allows water to flow to cool the cavity-side mold;
A corrugated plate member installed so as to be interposed between a side surface of the cavity side mold and the template, and absorbing expansion / contraction due to heating / cooling of the cavity side mold;
It is provided with.

  In the molding die apparatus of the present invention, the heat source body is installed inside the cavity side mold and the cavity side die is heated to a temperature higher than the thermal deformation temperature of the resin, so that the resin flowing at the time of molding can be obtained. Since fusion occurs at the joining point, no weld line is generated in the molded product, and the resin is faithfully transferred to the mold to obtain a highly accurate molded product.

  In the molding die apparatus of the present invention, the cavity side die is cooled by cooling the cavity side die by providing a water passage inside the cavity side die so that the resin can be rapidly cooled. It is possible to accelerate the solidification of the resin and shorten the cooling time.

  In particular, in the molding die apparatus of this example, the corrugated plate member is installed so as to be interposed between the side surface of the cavity side die and the mold plate, so that the cavity side die is heated / cooled by the cavity side die. Even if expansion / contraction occurs, since the expansion / contraction can be effectively absorbed by the bending of the corrugated plate member, an extra burden is not applied to the molding die apparatus, and the apparatus has a long service life. Can be achieved.

Hereinafter, preferred embodiments of a molding die apparatus according to the present invention will be described in detail with reference to the drawings. In this example, a specific example in which a PC / ABS resin is used as a molding material will be described.
FIG. 1 is a longitudinal sectional view showing the configuration of a molding die apparatus according to the present invention, FIGS. 2 and 3 are explanatory views of the operation of the molding mold apparatus, and FIG. 4 is a view of a cavity side mold in the molding mold apparatus as viewed from below. FIG. 5 is an exploded perspective view showing the configuration of the cavity side mold and its periphery, and FIG. 6 is a longitudinal sectional view showing the detailed configuration of the cavity side mold and the core side mold.

  As shown in FIG. 1, the molding die apparatus 1 of this example has a pair of upper and lower mold plates 2 and 3 installed so as to be relatively opened and closed while facing each other. A pair of upper and lower molds, that is, a cavity-side mold 4 and a core-side mold 5 are mounted as product inserts so as to be embedded respectively. In this configuration, the mold plates 2 and 3 and the molds 4 and 5 are both made of steel, and are formed between the molds 4 and 5 when the molds 4 and 5 are closed together. Molding is performed by injecting and pouring molten resin into the space 6 from the gate 7 (see FIG. 4).

  In this molding die apparatus 1, the cavity side die 4 is heated to a temperature higher than the heat deformation temperature of the resin for the purpose of preventing the generation of weld lines in the molded product and improving the transferability. That is, in this molding die apparatus 1, a cavity 8 is formed in the cavity side mold 4 in the vicinity of the molding surface, and a heat source body 9 is installed so as to be movable in the cavity 8. The heat source body 9 is configured by incorporating a heater 10 in a copper material. As the heater 10, a high watt cartridge heater incorporating a nichrome wire is preferably used. The heating set temperature of the heater 10 is 300 to 320 ° C. In addition to the high watt cartridge heater, for example, a ceramic heater or a heating element by high frequency induction can be used as the heater.

  The heat source body 9 is connected to the cylinder rod 12a of the air cylinder device 12 via the heat insulating material 11, and can be moved in the vertical direction so as to contact / separate the bottom surface of the cavity 8 by the operation of the air cylinder device 12. It has become. With the heat source body 9 in contact with the bottom surface of the cavity 8, the cavity side mold 4 is heated to about 120 ° C. at which the peripheral portion of the molding surface is equal to or higher than the thermal deformation temperature (about 100 ° C.) of the resin.

  Further, in this molding die apparatus 1, water passages (holes) 14 and 15 are formed so as to pass in the vicinity of the heat source body 9 inside the cavity side die 4. Here, cold water for rapid cooling of the mold (20 to 30 ° C.) and warm water for temperature adjustment (60 to 70 ° C.) are poured into the lower water passage 15 close to the molding surface in a timely manner from the molding surface. A warm water (60 to 70 ° C.) for temperature adjustment is always allowed to flow through the separated upper water passage 14.

  Furthermore, in this molding die apparatus 1, a heat insulating frame 16 installed so as to surround the side surface of the heat source body 9 is embedded in the cavity portion 8 of the cavity side mold 4. The heat insulating frame 16 is a frame formed using a titanium alloy or the like having a low thermal conductivity, and the heat source body 9 is incorporated so as to be movable in the vertical direction along the inner surface of the heat insulating frame 16. By providing the heat insulation frame 16, the heat source body 9 and the water passage 15 are insulated from each other, whereby the cavity side mold 4 is efficiently heated / cooled. Further, by embedding the heat insulating frame 16, the strength of the cavity side mold 4 is maintained, and deformation of the cavity side mold 4 due to internal pressure during molding can be suppressed.

  In addition, two upper and lower water flow grooves 17 and 18 are formed on the outer peripheral surface of the heat insulating frame 16. The water channels 17 and 18 communicate with the water channels 14 and 15, respectively. That is, the lower water channel 18 has cold water (20 to 30 ° C.) for rapid cooling of the mold and hot water for temperature adjustment ( 60-70 ° C.) is flown in a timely manner, and warm water for temperature adjustment (60-70 ° C.) is always allowed to flow through the upper water flow groove 17.

  Furthermore, in this configuration, as shown in FIG. 6, chrome platings 20 and 21 are applied to the opposing surfaces of the heat source body 9 and the heat insulating frame 16, that is, the outer surface of the heat source body 9 and the inner surface of the heat insulating frame 16, respectively. In this case, heat radiation from the heat source body 9 is suppressed by the chromium plating 20 on the outer side surface of the heat source body 9, and radiant heat from the heat source body 9 to the heat insulation frame 16 is reflected by the chromium plating 21 on the inner side surface of the heat insulation frame 16. Thereby, the heat loss of the heat source body 9 is reduced, and a sufficient heating temperature can be supplied to the cavity side mold 4. Further, in the cavity side mold 4, heat transfer grease is applied to the bottom surface of the cavity portion 8 with which the heat source body 9 comes into contact, thereby further improving heat conduction from the heat source body 9 and performing reliable heating. I am doing so.

  Further, the heat source body 9 has a structure in which the outer peripheral surface of the heater 10 is provided with a copper plate 10a having high heat conductivity and is in close contact with the inner peripheral surface of the heater mounting hole 9a. Can be secured. In addition, although the number of the heaters 10 is one in the heat source body 9 of this example, a configuration in which a plurality of the heaters 10 are provided to increase the heat generation amount may be employed.

  In the molding die apparatus of this example, as shown in FIG. 1, both the dies 4 and 5 are mounted so as to be embedded in the recesses 2a and 3a of the mold plates 2 and 3, respectively. Here, a heat insulating plate 23 is installed between the cavity side mold 4 and the mold plate 2 along five surfaces excluding the molding surface of the cavity side mold 4. This heat insulating plate 23 is made of a high temperature durability grade epoxy resin, and by installing this heat insulating plate 23, heat transfer from the cavity side mold 4 to the mold plate 2 is cut off and efficient heating / cooling is performed. Yes. A heat insulating plate 24 is similarly installed between the core side mold 5 and the mold plate 3 corresponding to the cavity side mold 4.

  Further, a steel corrugated plate member 25 is interposed between the side surface of the cavity side mold 4 and the mold plate 2. As shown in FIG. 4, this corrugated plate member 25 is obtained by processing a steel plate having a required thickness into a corrugated concavo-convex shape. In this example, two corrugated plate members 25 are formed along two mutually orthogonal side surfaces of the cavity side mold 4. A corrugated plate member 25 is disposed. Then, a wedge member 26 is assembled in the recess 2a so that the corrugated plate member 25 is sandwiched between the cavity side mold 4 and is fastened to the mold plate 2 with bolts 27, whereby the cavity side mold 4 is inserted into the recess 2a. It is fixed by pressing against the side.

  By installing such a corrugated member, in the molding die apparatus 1 of this example, even if the cavity side mold 4 is expanded / contracted by heating / cooling of the cavity side mold 4, the corrugated sheet member 25 is This expansion / contraction can be effectively absorbed by bending. In particular, in this example, two corrugated plate members 25 are installed along two mutually orthogonal side surfaces of the cavity side mold 4, so that it is possible to cope with expansion / contraction of the cavity side mold 4 in two directions. . Further, thermal expansion due to a temperature difference between the mold plate 2 and the cavity side mold 4 can be absorbed. The core-side mold 5 corresponding to the cavity-side mold 4 is similarly fixed to the mold plate 3 by the wedge member 29 via the corrugated plate member 28.

  Further, in the molding die apparatus 1 of this example, the molds are aligned by the mold plates 2 and 3. In the closed state where the mold plates 2 and 3 are combined, both the molds 4 and 5 are aligned. A slight gap of about 0.02 to 0.03 mm is formed between them. This gap is a slight gap that does not cause burrs in the molded product. By providing this gap, heat transfer from the cavity side mold 4 to the core side mold 5 is interrupted, so that the cavity side The mold 4 can be efficiently heated.

  Further, in this molding die apparatus 1, gas generated from the molten resin at the time of molding is sucked from the gap between the molds 4 and 5 and forcibly exhausted. That is, in this case, as shown in FIG. 6, an O-ring 30 is installed on the mating surface of the core-side mold 5 to seal the molding space 6 in the mold-closed state. A configuration is adopted in which air is sucked and exhausted from the gap between the molds 2 and 3 by a suction pump through an intake passage 31 provided in the side mold 5, thereby forcing air and gas confined in the weld part. The generation of weld lines is suppressed to prevent the occurrence of other molding defects.

  Molding by the molding die apparatus 1 of the present example configured as described above is performed with the following operation as one cycle. That is, first, the molding die apparatus 1 is in a mold open state in which the mold plates 2 and 3 are separated from each other in the initial state, and the heat source body 9 is separated from the bottom surface of the cavity portion 8 of the cavity side mold 4. It is in. From this initial state, the mold plates 2 and 3 are moved in directions close to each other to bring the mold plates 2 and 3 together into a mold closing state, and simultaneously with this mold closing operation, the air cylinder device 12 is moved forward to move the heat source body 9. It is made to contact the bottom face of the cavity part 8 (state shown in FIG. 1).

  Here, the heat source body 9 is maintained at a set temperature of 300 to 320 ° C. by the heater 10, and when the heat source body 9 contacts the bottom surface of the cavity portion 8 of the cavity side mold 4, the cavity side mold 4. The peripheral portion of the molding surface is heated to about 120 ° C. at which the temperature becomes higher than the thermal deformation temperature (about 100 ° C.) of the resin.

  Then, in the state in which the cavity side mold 4 is heated to a temperature equal to or higher than the thermal deformation temperature of the resin, the molten resin is injected and injected into the molding space 6 between the molds 4 and 5 to perform molding. At this time, since the cavity side mold 4 is heated to a temperature equal to or higher than the heat deformation temperature of the resin, the flowing resin is fused at the joining point, so that a weld line does not occur and the mold is not affected by the resin. Is faithfully transferred and high-precision molding is performed.

  After this injection molding is completed, the resin is solidified with a certain cooling time in the mold closed state as it is. In this case, immediately before the injection of the resin is completed, the air cylinder device 12 is moved backward to separate the heat source body 9 from the bottom surface of the cavity 8 and to block the heat supply to the cavity side mold 4 (shown in FIG. 2). Status).

  At the same time, the cavity side mold 4 is rapidly cooled by passing cold water (20 to 30 °) through the lower water passage 15 and the water passage groove 18 close to the molding surface of the cavity side mold 4. Solidification of the resin is promoted, and warm water (60 to 70 ° C.) is switched over at an appropriate time so that the cavity side mold 4 is returned to the normal set temperature. It should be noted that warm water (60 to 70 ° C.) for temperature adjustment is always passed through the upper water passage 14 and the water groove 17 away from the molding surface of the cavity side mold 4. The mold 4 can be quickly returned to the normal set temperature.

  Then, after a certain cooling time has passed and the resin is sufficiently solidified, the mold plates 2 and 3 are moved away from each other to be in the mold open state (the state shown in FIG. 3). The molded product 40 is taken out from between. The molded product 40 is taken out by a take-out pin protruding from the core-side mold 5, but the take-out pin is not shown in this example.

The molding operations in the molding die apparatus of the present example as described above are all controlled by a controller provided in the die control panel. Here, the operation relating to the heat source necessary for the temperature control of the mold and water flow is accurately controlled by the timer of the controller (the time chart is shown in FIG. 7).
In addition, the temperature numerical value regarding temperature control of this metal mold | die has illustrated the temperature at the time of using PC / ABS resin as a molding material, and since this temperature changes according to the material of resin, it is illustrated. It is not limited to numerical values.

  As described above, in the molding die apparatus of this example, the heat source body 9 is installed inside the cavity side die 4 and the cavity side die 4 is heated to a temperature higher than the thermal deformation temperature of the resin. As a result, the resin flowing at the time of molding is fused at the joining point, so that a weld line does not occur in the molded product, and the resin is faithfully transferred to the mold to obtain a highly accurate molded product.

  Moreover, in the molding die apparatus of this example, the cavity side die 4 is rapidly cooled by providing the water passage 15 inside the cavity side die 4 to cool the cavity side die 4. Cooling can accelerate the solidification of the resin and shorten the cooling time.

  In particular, in the molding die apparatus of this example, the corrugated plate member 25 is installed so as to be interposed between the side surface of the cavity side mold 4 and the mold plate 2, so that the cavity side mold 4 is heated / cooled. Even if expansion / contraction occurs in the cavity-side mold 4, since the expansion / contraction can be effectively absorbed by the corrugated plate member 25 being bent, an extra burden is placed on the molding die apparatus. This is effective in extending the service life of the apparatus.

  As mentioned above, although the Example of this invention was described, it cannot be overemphasized that this invention can take other various embodiment, without being limited to this Example.

It is a longitudinal cross-sectional view which shows the structure of the shaping die apparatus by this invention. It is operation | movement explanatory drawing of a shaping die apparatus. It is operation | movement explanatory drawing of a shaping die apparatus. It is the top view which looked at the cavity side metal mold | die in a shaping die apparatus from the downward direction. It is a disassembled perspective view which shows the structure of a cavity side metal mold | die and its periphery. It is a longitudinal cross-sectional view which shows the detailed structure of a cavity side metal mold | die and a core side metal mold | die. It is a time chart of the operation | movement regarding a heat source body and water flow.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mold apparatus, 2, 3 ... Template, 4 ... Cavity side metal mold, 5 ... Core side metal mold, 9 ... Heat source body, 15 ... Water passage, 25 ... Corrugated sheet member

Claims (2)

In a molding die device for resin molding,
A pair of templates installed to open and close relatively in a state of facing each other;
A cavity side mold and a core side mold mounted so as to be embedded in the pair of mold plates, respectively,
A heat source body that is installed inside the cavity side mold and heats the cavity side mold to a temperature higher than the thermal deformation temperature of the resin;
A water passage that is provided in the vicinity of the heat source body inside the cavity-side mold, and that allows water to flow to cool the cavity-side mold;
A corrugated plate member installed so as to be interposed between a side surface of the cavity side mold and the template, and absorbing expansion / contraction due to heating / cooling of the cavity side mold;
A molding die apparatus constituted by comprising: In the molding die apparatus according to claim 1,
A molding die apparatus configured by arranging two corrugated plate members along two mutually intersecting side surfaces of the cavity side die.

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