JPS6031935A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To remove the leakage of a gas from a projecting pin section, and to keep hermetic sealing in a cavity by mounting a material having rubber elasticity so as to surround the periphery of the projecting pin in a mold disk and sealing the projecting pin section. CONSTITUTION:An injection port and a discharge port are each formed between a fixing side mold 2 and a movement side mold 3, and a fluidized resin is sealed through a vacuum injection or pressure injection method or an introducing method as powdered bodies. Post-treatment such as heating can be executed properly to an elastic body. When Teflon mixed silicone resin is injected, the elastic body is cured for 2hr at room temperature, and after-baked for 2hr at 100 deg.C. The thickness of the elastic body sealed in the molds slightly differs by the size and shape of projecting pins 7, but it is brought to normally 0.5-50mm., preferably, 2-6mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection mold apparatus including means for regulating the pressure within the mold cavity prior to injection of molten resin.

Conventionally, in order to adjust the pressure inside the mold cavity, it was necessary to make the mold cavity airtight.
Seal methods used include rings and various other gaskets. However, in order to seal each of the many ejector pins, many steps are required to manufacture the mold.
The mold structure also becomes complicated. In addition, in the method described in Utility Model Application No. 57-78918, in which the chamber housing the ejector plate for integrally operating the ejector pins is made into a sealed structure, when pressurizing the cavity, the volume of the airtight structure chamber is large. It takes a long time to be pressurized, and the consumption of pressurized gas also increases. The same applies to the case where the pressure is reduced.

The present invention provides an airtight structure by sealing an elastic body inside a mold plate having protruding pins, thereby solving the above-mentioned problems. That is, the present invention relates to an injection mold characterized in that a material having rubber-like elasticity is provided inside the mold plate so as to surround the protrusion pin, and the protrusion pin portion is sealed.

Examples of the mold of the present invention will be described below with reference to the drawings.

FIG. 1 shows a mold according to one embodiment of the present invention. In Figure 1, 1 is a plate for fixed side mounting, 2 is a fixed side mold, 3 is a movable side mold, 4 is a receiving plate, 5 is a spacer block, 6 is a plate for movable side mounting, 7 is a protrusion 12 is an external pressure Shows the hole for adding. The elastic body 9 sealed between the mold members 3 and 4 prevents gas from leaking from the protruding pin portion and maintains airtightness within the cavity.

As the elastic material, any elastomer synthetic rubber with good heat aging resistance can be used, regardless of whether it is urethane-based, silicone-based, polyester-based, or fluorine-based. For example, butadiene rubber, butadiene-styrene rubber (SBR), butadiene-acrylonitrile rubber (NBR), chloroprene rubber, butyl rubber, urethane rubber, silicone rubber,
These include acrylic rubber, ethylene-propylene comb, propylene oxide rubber, chlorosulfonated PK, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and the like. Those mixed with reinforcing materials such as glass fiber, carbon fiber, molybdenum disulfide, graphite, and asbestos, and foams of these materials can also be used. In addition to sealing compounds containing the above-mentioned materials as main ingredients, resins used as anaerobic sealants and liquid gas feet can also be used. Preferably, a silicone resin mixed with 10% by weight of Teflon resin is used.

The sealing method is as follows: (1) An injection port and a discharge port are provided between the stationary mold 2 and the movable mold 3 shown in Fig. 1, respectively, and the fluid resin is injected in vacuum, injected under pressure, or in a pressurized vacuum. There are a method of injecting the material, a method of introducing it as a powder, and a method of (3) performing injection molding using a molding machine as it is with a mold structure as shown in FIG. The elastic body can be subjected to post-treatment, such as heating, as appropriate. For example, when Teflon-containing silicone resin is injected, it is cured at room temperature for 2 hours and then after-baked at 100°C for 2 hours.

The thickness of the elastic body sealed in the mold depends on the size of the ejector pin,
Although it varies slightly depending on the shape, it is generally 0.5cm to 50w, more preferably about 2cm to 6cm. In the mold of this example, the average diameter is 41111, and the corners are cut diagonally from a position 3 m from the end surface of the guide hole of each pin used to each protruding pin guide hole, and the elastic body in this part is thickened. This increases the contact area between the ejector pin and the elastic body.

FIG. 2 is a detailed view of the ejector pin portion.

According to the present invention, a plurality of projecting pins can be simultaneously and easily made into an airtight structure. Also, at this time, in order to apply an external force to the sealed rubber-like elastic body and improve airtightness at the pin part, several holes may be drilled in the rubber-like elastic body on the inside of the OIJ song on the outside of the molded product. .

In the embodiment shown in Fig. 3, in advance, a groove on the fixed side with sufficient width and depth for sealing is formed between the plate 1 and the fixed side mold 20 on two, four or more sides, so as to be optically isolated from the product. For example, a hole is machined to the same position as the O-ring or close to it, and a hole is machined from that position to the gap formed to seal the elastic body, thereby forming a sprue for sealing the elastic body. Also, at this time, when making a replacement bushing as shown in Figure 4 and sealing it with an elastic body, no elastic body flows into the product side.
Allow it to flow only to two or four or more sprues.

[Brief explanation of the drawing]

FIG. 1 is an example of a cross section of an injection mold used for carrying out the method of the present invention, and FIG. 2 is a detailed view of the ejector pin portion. FIG. 3 is a sectional view of another embodiment of the mold, and FIG. 4 is a sectional view of a replacement sprue bushing. The symbols in the figure mean the following: 1-m-Fixed side mounting is plate 2-111 Fixed side mold 3--
- Movable side mold 4-11 is plate 5---2÷zu-flick 6---Movable side mounting plate 7
---Ejecting pin 8-11/Lid A and To 9--
- Elastic body 10--0 ring 11-m-Injection or discharge port 12-m-hole for applying external pressure 13-11 sprue bush 14--1 sprue 1st
Figure 3 Figure 4

Claims (1)

[Claims] 1. In an injection mold device that includes a step of adjusting the pressure inside the mold cavity prior to injection of molten resin, an injection molding device that has a sealed structure by sealing an elastic body inside a mold plate having ejector pins. Mold.