JPS646272Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a plastic injection mold.

[Conventional technology]

Conventionally, plastic injection molding involves feeding a plastic compound into the cylinder of an injection molding machine, heating it to about 200°C, injecting it into a mold in a molten state, and then cooling it to perform molding. At this time, in order to solidify and cool the injected molten plastic, it is necessary to quickly lower the temperature of the mold, which has risen due to the heat of the molten plastic, to 50 to 60°C, but depending on the shape of the product to be molded, etc. Since the molten plastic flows deeply into the mold, the temperature of the entire mold cannot be made uniform unless the parts that receive more heat from the molten plastic are cooled more strongly than other parts.

Conventionally, when molding such products, the temperature was controlled by flowing a large amount of cooling water through the parts of the mold that received a large amount of heat from the molten plastic.

[Problem that the invention aims to solve] However, even if the above-mentioned mold is used, the temperature of parts with deep recesses or parts with a large number of recesses is difficult to decrease, and the time required to cool the mold is limited. It was getting long. Molding efficiency is limited by the cooling time of the mold, so if the cooling time is long, the time from injection to injection becomes longer, making it impossible to perform efficient molding operations.

[Means for solving problems]

The technical means taken by this invention to solve the above problems is to configure the part of the mold that receives a large amount of heat from the molten plastic as a nest made of a highly thermally conductive material that is different from the entire mold. The reason is that a cooling water flow path is provided in the nest.

[Effect]

Due to the injected molten plastic, parts of the mold that have deep recesses or many recesses become hotter than other parts, but this heat quickly diffuses due to the action of the nest made of high heat conductive material. , the cooling rate will be faster than other parts.

〔Example〕

Hereinafter, embodiments of this invention will be described based on the accompanying drawings.

The illustrated mold is used to manufacture a television cabinet by plastic injection molding, and 1 is a male mold fixed to a mold stand 2, and 3 is a female mold.

As shown in FIG. 1, a recess 4 is formed in the upper surface of the male mold 1 in order to form a protrusion for attaching an electrical component or the like to the inside of the cabinet.
In the vicinity of the recess 4, a metal having high thermal conductivity, such as a copper alloy, is embedded as a nest to form a high thermal conductive portion 5.

6 is a fitting part, which is provided as a nest;
A sleeve pin 7 is provided inside. Since the recess 4 needs to be made very small and thin, this fitting part 6 is formed by forming only this part separately and then fitting it together. The fitting part 6 may be formed of the same metal as the high thermal conductivity part 5.

Each of the high thermal conductivity portions 5 and the fitting portion 6 is formed with a flow passage 8 for passing cooling water.

Next, the usage conditions of the mold according to this invention will be explained.

When the male mold 1 and the female mold 3 are fitted together, a gap 9 is created between the male mold 1 and the female mold 3, as shown in FIG.
When molten plastic is injected into the fitted molds 1 and 3, the molten plastic fills the gap 9 and the recess 4.
However, since both molds 1 and 3 are maintained at a temperature of about 50 to 70°C, the molten plastic is cooled and solidified, and a television cabinet is formed. While the molten plastic that has flowed into the gap 9 and the recess 4 is being cooled, the area near the recess 4 of the male mold 1 receives more heat than the molten plastic, and is at a higher temperature than other parts. However, since the heat in this portion rapidly diffuses within the high heat conduction portion 5 and is dissipated by the cooling water, the cooling rate becomes extremely fast. Therefore, the temperature of both molds 1 and 3 can be lowered uniformly in a short time.

In fact, when we made the same sample (square material) using S55C, a common mold material, and a copper alloy with higher thermal conductivity and hardness than S55C, and compared the cooling rate, we found that it was close to the mold's heat retention temperature. 10~20℃ for the same time
A difference occurred.

In this embodiment, the high thermal conductivity part 5 is formed only in the male mold 1, but if the recessed part 4 is also formed in the female mold 3, the high thermal conductivity part 5 is also formed in the vicinity.
need to be formed.

[Effect of idea]

This invention has the above-mentioned configuration, and the mold can be cooled uniformly and the cooling rate is increased, so the shot speed can be increased, and therefore the molding efficiency can be increased. It has the effect that it can.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a male injection mold according to the invention. FIG. 2 is a plan view of the same part. FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 2, showing the male and female molds fitted together. FIG. 4 is a sectional view taken along the line B-B. 1...male type, 3...female type, 4...concavity, 5...
High thermal conductivity section, 8...channel.

Claims (1)

[Scope of utility model registration request] An injection method characterized in that the part of the mold that receives a large amount of heat from the molten plastic is constructed as a nest made of a highly thermally conductive material different from the mold body, and the nest is provided with a flow path for cooling water. Molding mold.