JPS62179912A - Molding equipment of synthetic resin molded part - Google Patents

Abstract

PURPOSE:To stably manufacture a product, which is uniform in density and is highly faithful to a mold and develops no defects such as weld and the like, in a short cycle time by a method wherein heating medium and cooling medium are supplied to fluid channels by being changed-over from one medium to the other. CONSTITUTION:When heating medium is supplied to fluid channels 5 by actuating a selector 14 so as to communicate the fluid channels 5 with a heating medium supply pipe 15, the heating medium is filled in the fluid channels 5, 6 and 7 so as to heat a mold cavity 3. When molten synthetic resin is poured in molds 1 and 2 under the state that the mold cavity is heated, the resin flows in least ununiform state without causing curing so as to be filled in the molding cavity at high packing. When air is supplied to the fluid channels 5 by actuating the selector 14 so as to communicate the fluid channels 5 with an air supply pipe 16, the heating medium is discharged outside by the air. When the discharging of the heating medium is completed, the fluid channels 5 and 6 are closed. When cooling medium is supplied to the fluid channels 5 by actuating the selector 14 so as to communicate the fluid channels 5 with a cooling medium supply pipe 17, the cooling medium is filled in the fluid channels 5, 6 and 7 so as to cool the mold cavity 3 in order to quickly harden the molten synthetic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an apparatus for manufacturing synthetic resin molded products. More specifically, the present invention relates to a molding device that heats a mold before molding and cools it after molding to efficiently produce products of good quality.

(Prior Art) Conventionally, a mold used for manufacturing synthetic resin molded products has a molding space 21 between a lower mold 19 and an upper mold 20, as shown in FIG.
and inject molten synthetic resin into this molding space 21,
The resin cools and hardens (a problem to be solved by the invention).In the conventional mold described above, when pouring the molten synthetic resin, mold 1
9. The temperature at 20 is low, which causes the molten synthetic resin to harden during flow, resulting in uneven flow near and far from the gate 22, resulting in a low filling rate, which results in products having problems with uniform density and conformity to the mold. There was a problem that the fidelity was poor and defects such as welds were likely to occur.

Attempts were made to solve this problem by raising the melting temperature of the synthetic resin or increasing the injection pressure, but raising the melting temperature increases the heating time, lengthening the molding cycle time. When the injection pressure is increased, the flow rate increases, which tends to cause bubbles due to air entrainment.Also, since the conventional mold mentioned above is a natural cooling type, it takes time for the molten plastic to harden, which reduces the molding time. There was also a big problem with the length of the cycle.

In order to solve the above-mentioned conventional problems, the present invention uses a mold that is placed under pressure before carving and is cooled after molding. The object of the present invention is to provide a molding apparatus that can stably manufacture products with uniform density, high fidelity to molds, and no defects such as welds in a short cycle time.

(Means for Solving the Problems) The molding apparatus for synthetic resin molded products according to the present invention is shown in FIG.
As shown in FIGS. 7 to 7, a mold 1 with a molding space 3'
2, fluid passages 5, 6.7 provided in the mold 1.2 in close proximity to the molding space 3, and a medium for selectively supplying a heating medium and a cooling medium to the fluid passages 5, 6.7. This configuration includes supply means 14, 15, 16, and 17.

(Function) Before starting molding, the molding apparatus configured as described above operates the switching device 14 of the supply means to communicate the fluid passage 5 with the heating medium supply pipe 15 to supply the heating medium. , the heating medium fills the fluid passages 5, 6.7 and heats the molding space 3, heating the molding space 3 to the appropriate molding temperature in a short time, so at this time, the molten synthetic resin is injected into the molds 1, 2. Then, since the molding spaces 3 of the molds 1 and 2 are maintained at the appropriate temperature for molding, the resin does not harden and flows evenly through the molding spaces 3 from near the gate 4 to far away, and flows into the molding spaces 3 at a high temperature. The product is formed by filling at the filling rate.

Therefore, the fluid passages 5, 6. When the switching device 14 connects the fluid passage 5 to the air supply pipe 16 to supply air, the heating medium in the fluid passages 5, 6, and 7 is discharged to the outside by the air.

When the heating medium is discharged in this way, the fluid passages 5 and 6 are closed, and the switching device 14 connects the fluid passage 5 to the cooling medium supply pipe 1.
7 and supplies a cooling medium, the cooling medium fills the fluid passages 5, 6 and 7, cools the molding space 3, and quickly hardens the filled molten synthetic resin. When the molded product is removed by opening, one cycle of molding is completed.

Therefore, as described above, before molding, the fluid passages 5 of the mold 1.2 are
, 6.7, molds 1 and 2 are heated, and then molding is performed. When the molding is completed, the heating medium is discharged, and a cooling medium is supplied to cool the mold 1.2, and the mold is removed. By repeating the molding operation, it is possible to produce an excellent molded product with high fidelity, uniform density, and no defects such as welds in a short cycle time.

(Example) An example of implementation of the device related to the present invention will be described below based on the drawings.

Drawings 1 and 2 show a first embodiment for molding a dish-shaped product such as a battery bat.
1 and 2 are an upper mold and a lower mold of the mold, and a dish-shaped molding space 3 that matches the shape of the product is formed between them, and molten synthetic resin is injected into this molding space 3 from a gate 4 to make the product W aged. 5.6.7 is a fluid passage provided in the mold 1.2 in the vicinity of the molding space 3, and the passage 5 on the fluid feeding side is arranged on one side of the molding space 3. , the passage 6 on the delivery side is heated and cooled evenly to the other side of the molding space 3, and fins 8 are sometimes attached to this narrow passage 7 to improve heat conductivity. The fluid passages 5, 6.7 are formed using a low melting point metal between the upper mold 1 and the lower mold 2.
When performing Guicast casting, grooves 9, 10, 11 are inserted from the back side as shown in Fig. 3 into the upper mold 1 and lower mold 2, which are machined from steel, by inserting them as shown in Figs. 1 and 2. , and each of these grooves 9.10.11 contains a fluid passage 5, 6.7, respectively, and a filler 1 is placed in the groove 9.10.11.
2 and fix the IA and body passage 5.6.7, or place a synthetic resin base 13 in a mold 1.2 formed by electroforming or thermal spraying of hard metal as shown in FIG. When molding and joining, the fluid passages 5, 6 and 7 are attached to the platform 13 by means such as inserting them, and usually a vibrator is used, but it is inserted into the grooves 9, 10 and 11. In case of filling with a material, a C-shaped material etc. may be used.

Reference numeral 14 denotes a three-way switching device attached to the fluid passage 5, which connects a heating medium supply pipe 15, an air supply pipe 16, and a cooling medium supply pipe 17. Before molding, supply heating medium to upper and lower molds 1 and 2.
After the molding is completed, air is supplied, the heating medium is removed, and a cooling medium is supplied to cool the upper and lower molds 1.2.

Reference numeral 18 denotes an on-off valve attached to the fluid passage 6, which is opened when supplying the heating medium and cooling medium and when blowing air, and is closed after the medium has been supplied.
It is advantageous to operate synchronously by means of synchronization using fluid pressure or the like.

Figures 6 and 7 show a second embodiment for molding a cylindrical product, and 1 and 2 are an upper mold 1 and a lower mold 2 in the mold, and between them, molding that fits the shape of the product is shown. A space 3 is formed, and a molten synthetic resin is injected into this molding space 3 from a gate 4 to mold the product.

5.6.7 is an annular fluid passage provided in the above-mentioned upper mold 1 and lower mold 2 close to the molding space 3, with the annular passage 5 on the feeding side arranged on the upper side and the annular passage 5 on the feeding side on the lower part. An annular passage 6 is arranged so that these two roads 5.6 are connected by a large number of narrow passages 7 arranged in an annular manner so that the molding space 3 is heated and cooled evenly.

The above-mentioned fluid passages 5, 6.7 are formed by the same means as shown in the first embodiment, and the switching device 13 attached to the fluid passage 5 and the on-off valve attached to the fluid passage 6 are used. The configuration, connection, and operation of 17 are the same as those shown in the first embodiment, so a detailed explanation thereof will be omitted.

Said 1st. In the second embodiment, 85
Using hot water at 7°C as a cooling medium, the hot water is supplied to the fluid passages 5, 6.7 by the switch 13, and the temperature of the molds 1 and 2 is measured after 20 seconds. The temperature of the mold had risen to 75°C.

Next, the switching device 14 blows air into the fluid passages 5, 6. It was down to 'c.

In addition, air was blown into the fluid passages 5, 6.7 by the switching device 13, hot water was supplied after the cold water was discharged, and the temperature of the molds 1, 2 was measured to be 75° C. 20 seconds later.

Therefore, the battery bat shown in FIG. 8 was formed while performing this heating and cooling. As a result, the cycle time required to mold the product was 38 seconds, and heating and cooling were performed at a temperature of 40°C. Compared to the cycle time of conventional molding equipment, which has a temperature of 47°C when the product is opened and taken out, which is 56 seconds, the cycle time can be reduced by 18 seconds.
The product was faithful to the mold, had a uniform density, and no defects such as welds were observed.

In the above embodiments, hot water was used as the heating medium and cold water was used as the cooling medium. However, pressurized steam or a heat medium that can be heated to a higher temperature can be used as the heating medium, and ammonia or ammonia that can be heated to a lower temperature can be used as the cooling medium. Freon and other gases can be used.

(Effects of the Invention) The apparatus for manufacturing synthetic resin molded products according to the present invention heats the mold before molding to improve moldability, and cools the mold after molding to accelerate the hardening of the resin. Cycle time is significantly reduced.

The mold is heated before molding to suppress the hardening of the molten synthetic resin, reduce uneven flow near and far from the gate, and increase the filling rate, resulting in uniform density and high fidelity to the mold.
A product that is free from defects such as welds can be obtained.

Since there is no need to raise the raw material temperature or injection pressure, the heating time is shortened, the molding cycle is improved, and the generation of bubbles due to air entrainment is prevented.

Since the mold is repeatedly heated and cooled at a high speed, dew condensation on the mold due to cooling is prevented, and no molding becomes impossible.

It has the following unique effects.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of the apparatus according to the present invention. FIG. 2 is a plan view showing the arrangement of fluid passages and piping in the same as above. 3 and 4 are longitudinal sectional front views showing other examples of the fluid passage equipment in the same as above. FIG. 5 is a longitudinal sectional front view showing still another example of fluid passage equipment. FIG. 6 is a longitudinal sectional front view showing the second embodiment. FIG. 7 is a cross-sectional plan view of the same as above. FIG. 8 is a perspective view of a product obtained by the same device. FIG. 9 is a longitudinal sectional front view of a conventional molding device. In the figure, 1 and 2 are molds, 3 is a molding space, 5, 6, 7 is a fluid passage, and 14, 15, 16, 17 is a fluid switching supply stage. Mi gong convex diagram I3 7 2 -t, S @ diagram

Claims (1)

[Scope of Claims] A mold forming a molding space, a fluid passage provided in the mold close to the molding space, and a medium supply means for selectively supplying a heating medium and a cooling medium to the fluid passage. A molding device for synthetic resin molded products, characterized in that it is equipped with: