JPH03251416A - Vacuum mold and its molding process - Google Patents

Abstract

PURPOSE:To obtain the molded object which has high quality and no void, while the evacuated state in mold clamping is perfectly held by achieving the evacuation by way of the through hole formed on a top force. CONSTITUTION:When a bottom force is temporally stopped at the position before the completion of mold clamping, a first transverse sealing part 15 is connected to a first vertical surface 7 of a top force 1. Then, a through hole 9 is positioned inside of the first transverse sealing part 15, and communicates with the cavity 20 formed by each recessed part 6, 10 of each mold 1, 11. The evacuation of the inner part of the cavity 20 is carried out by operating the vacuum pump connected to the through hole 9, and mold clamping is finished by moving the bottom force 11. Since the through hole 9 is positioned between each transverse sealing parts 15 and 16 and is closed, the deaerated state of the cavity 20 and the sprue 2 near vacuum is held, and injection molding is carried out by feeding resin into the cavity from a nozzle 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum mold and a molding method thereof, and in particular, in injection molding and reaction injection molding, by degassing from the through hole of the stopper mold, This invention relates to novel improvements for better molding of resins with low viscosity that tend to generate bubbles.

[Conventional technology]

There are various vacuum molds and molding methods of this type that have been used in the past, but the most typical ones are generally those that utilize the ejector turbine part of the mold to degas. The inside of the cavity was kept in a near-vacuum state.

[Problems to be Solved by the Invention] Since the Juto vacuum mold and its molding method were configured as described above, the following problems existed.

In other words, if the viscosity of the resin material during molding is low, the resin will flow between the mold and the ejector turbine, and in this state the resin material will be assimilated, resulting in almost no clearance between the ejector turbine and the mold, and as a result, the cavity The effectiveness of the vacuum inside the room had decreased significantly.

Therefore, especially in the case of a resin material with low viscosity, voids in which air bubbles remain are generated in the molded product, resulting in a significantly low yield.

The present invention has been made to solve the above-mentioned problems, and in particular, in injection molding and reaction injection molding, by removing air from the through holes of the upper mold, the generation of low-viscosity air bubbles can be prevented. It is an object of the present invention to provide a vacuum mold and a molding method thereof that can easily mold resin.

[Means to solve the problem]

A vacuum mold according to the present invention is a vacuum mold in which a cavity formed by an upper mold and a lower mold is kept in a vacuum state, and resin is supplied into the cavity.
It includes a through hole formed in the upper mold and a seal part formed in the lower mold, and the cavity part formed when each of the molds is joined is brought into a vacuum state through the through hole. This is a configuration designed to do this.

More specifically, the structure includes a seal portion provided at the nozzle touch portion of the upper mold.

Furthermore, a vacuum mold forming method according to another invention is such that a cavity formed by a stopper mold and a lower mold is evacuated, and resin is supplied into the cavity. a first step of temporarily stopping mold clamping of each of the molds, and deaerating the inside of the cavity through a through hole formed in the first mold in this temporarily stopped state; After the process is completed, the method includes a second process of closing each of the molds and supplying resin into the cavity.

[For production]

In the vacuum mold and the molding method thereof according to the present invention, a through hole is formed in the upper mold, a seal part is formed in the lower mold, and a seal part is provided in the nozzle touch part of the upper mold. Therefore, by joining the nozzle to the nozzle touch part, the nozzle and the upper mold are tightly connected, and in this state, the mold is clamped, and the mold is temporarily stopped at a position slightly (several millimeters) before mold clamping is completed. do.

The air in the cavity formed between each mold is removed (degassed) through the through hole of one mold, thereby creating a vacuum state in the cavity, and after the degassing is completed, the molds are clamped.

In this state where the mold clamping is completed, the through holes are located between the seal parts of the lower mold, so the vacuum state within the cavity is maintained, and resin is supplied from the nozzle into the cavity.

Thereafter, after holding pressure and cooling (or heating), each mold is opened to take out the molded product.

〔Example〕

Hereinafter, preferred embodiments of the vacuum mold and molding method thereof according to the present invention will be described in detail with reference to the drawings.

Figures 1 to 3 show the vacuum mold according to the present invention; Figure 1 is a sectional view showing the open state, Figure 2 is a sectional view showing the mold clamping is temporarily stopped, and Figure 3 is the mold. It is a sectional view showing a state in which the tightening is completed.

What is indicated by the reference numeral 1 in the figure is an upper mold, and a seal portion 4 is formed in a nozzle touch portion 3 that communicates with the sprue portion 2 of this upper mold 1. A nozzle 5 of a molding machine (not shown) is disposed in contact therewith.

A first fourth part 6 communicating with the sprue part 2 is formed inside the upper mold, and a wall part 6εt of the first recess 6 has a first parting surface having a first vertical surface 7. 8 is formed, and a through hole 9 formed in the horizontal direction is formed in this vertical surface 7.

A lower mold 11 having a second fourth part 10 corresponding to the first four part 6 is movably disposed below the upper mold 1. Seal part 1
A second parting surface having 2] 3 is formed.

A second padding surface continuously formed on the second padding surface 13.
A first horizontal seal portion 15 and a second horizontal seal portion 16 are provided on the vertical surface 14 and are spaced apart from each other in the vertical direction.

The vacuum mold according to the present invention is constructed as described above, and the vacuum molding method thereof will be explained below.

First, before molding, as shown in FIG. 1, the upper mold 1 and the lower mold 11 are separated, and the nozzle 5 is tightly fitted to the nozzle touch part 3 via the seal part 4. .

Next, as shown in FIG. 2, when the mold is clamped and the lower mold 11 is temporarily stopped at a position (approximately several millimeters) before the mold clamping is completed, the first horizontal seal portion 15 or the upper mold 1 At this time, the through hole 9 is in contact with the first vertical surface 7 of the first horizontal seal portion 15.
, and each recess 6 of each mold 1, 11
．． ]0 is in communication with the cavity portion 20 formed by.

In the above-mentioned state, the vacuum pump (not shown) connected to the through hole 9 is operated to evacuate the cavity 20, that is, to evacuate it, and after completing the degassing for a predetermined time, the vacuum pump (not shown) connected to the through hole 9 is operated. Mold clamping is completed by moving the lower mold] 1 as shown in FIG.

When this mold clamping is completed, the through hole 9 is located between the horizontal seal portions 15 and 1.6 and is in a closed state, so that the cavity portion 20 and the sprue portion 2 are evacuated to a near vacuum state. Injection molding is performed by supplying resin from the nozzle 5 into the cavity 20 while maintaining the air condition.

After that, after well-known pressure holding and cooling (or heating), each mold 1
, 11 to return to the state shown in FIG. 1, and the molded product can be taken out.

Next, an example of the above-mentioned vacuum forming method carried out in-house by the present applicant will be described.

Experimental Example 1 Molding with PΔ66 was performed using an injection molding machine with a mold clamping force of 800 tons. Molded product is 40 cmX 40 clnX
It is a flat plate of O,2cI^. Injection pressure 600KH/
Under the molding conditions of c+n2, injection time of 4 seconds, and resin temperature of 290° C., the distance before the mold clamping shown in FIG. 2 was set to 5+n+n, and the vacuum was drawn for 10 seconds.

In this molding process, molded products with and without vacuum evacuation were investigated. In the case of molded products with vacuum evacuation, the resin wrapped around well and no voids were observed at all, but in normal molding without vacuum evacuation, the resin wrapped around poorly, especially in some corners. became rusty.

Experimental Example 2 Epoxy was molded using reaction injection molding (RIM). The molded product is 60 c+nX 60 CIIIX
It is 0.3 cm thick and contains 4 Qu+t% of glass fiber reinforcement (glass mat). The epoxy injection amount was 180 g/sec, and the liquid temperature was 50~
The temperature was 70°C, and the injection pressure was 30-50 Kg7cm2.

Moreover, the mold clamping force is 40 tons. The evacuation time shown in FIG. 2 was 15 seconds.

RIM molding was performed with and without vacuuming, and the molded products were investigated. When vacuuming was applied, no voids were observed on the cross section or surface of the molded product, but when vacuuming was not performed, voids were observed on the surface or part of the cross section of the molded product. was seen.

〔Effect of the invention〕

Since the vacuum mold and the molding method thereof according to the present invention are configured as described above, the following effects can be obtained.

In other words, since vacuum can be drawn through the through holes formed in the upper mold, a vacuum state is completely ensured during mold clamping, and a high-quality molded product with no voids can be obtained. .

Moreover, not only injection molding but also 5RIN (reaction injection molding for i-building) in which reinforcing materials are added in RIM molding can prevent the generation of voids and can perform molding with a high yield.

[Brief explanation of drawings]

Figures 1 to 3 show the vacuum mold according to the present invention; Figure 1 is a sectional view showing the open state, Figure 2 is a sectional view showing the mold clamping is temporarily stopped, and Figure 3 is the mold. It is a sectional view showing a state in which the tightening is completed. 1 is an upper mold, 3 is a nozzle touch part, 4 is a seal part, 8 is a parting surface, 9 is a through hole, 11 is a lower mold, 15 is a seal part, and 20 is a cavity part.

Claims (3)

[Claims] (1) A vacuum mold in which the inside of the cavity part (20) formed by the upper mold (1) and the lower mold (11) is brought into a vacuum state, and resin is supplied into the cavity part (20). The mold includes a through hole (9) formed in the upper mold (1) and a seal part (15) formed in the lower mold (11),
A vacuum mold characterized in that the cavity portion (20) formed when the molds (1, 11) are joined is brought into a vacuum state through the through hole (9). (2) The vacuum mold according to claim 1, further comprising a sealing part (4) provided at the nozzle touch part (3) of the upper mold (1). (3) A vacuum mold which is configured to make the inside of the cavity part (20) formed by the upper mold (1) and the lower mold (11) into a vacuum state and supply resin into the cavity part (20). In the mold forming method, the mold clamping of each of the molds (1, 11) is temporarily stopped, and in this suspended state, the through hole (
a first step of deaerating the inside of the cavity (20) through a step 9), and after the first step, closing each of the molds (1, 11) to fill the cavity (20) with resin. A vacuum mold forming method characterized by comprising a second step of supplying.