JPS61144313A - Manufacture of precise molded article - Google Patents

Abstract

PURPOSE:To improve the external appearance of a molded article by preventing generation of a bubble and sink, by eliminating a reduction of a volume of resin based on curing and shrinking of the same to be generated during the curing of the resin by improving filling density. CONSTITUTION:A resin reservoir part 5 is fitted on a resin casting opening, and a vent opening and a reservoir part 11 are provided respectively on the external circumferential part of a molded article part and the vent opening. A pipe 6 is joined with the resin reservoir part 5 and air is fed to the pipe. As for the resin reservoir part 11, the upper part of the same is sealed up tightly and the whole of a device is depressurized within a pressure reducing tank at the time of casting. The liquid resin is casted within the resin reservoir part 5 under this state. As for a quantity of the resin to be casted, it is so prepared that an appropriate quantity of the resin is left behind in the resin reservoir part 5. The resin in casted within a molded-article part 2 of a molding tool in this manner and the device is restored to a state of normal pressure. In this instance, the resin remains to the resin rservoir part 11 also by shifting the same to the part 11. The resin is made to cure by heating the same by keeping a state as it is by applying continuously predetermined air pressure of more than 0.01kg/cm<2> to the resin reservoir part 5 from a pipe 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a liquid resin and uses a vacuum casting method to achieve precise dimensional accuracy and surface accuracy, and is free from warping and internal distortion. The present invention relates to a method for manufacturing a disc-shaped molded product.

[Prior art]

A casting method is generally used as a method for curing a liquid resin to obtain a molded article, and one type of the method is a vacuum casting method. In this method, microscopic air bubbles contained in the liquid resin are removed in advance under reduced pressure, and then this liquid resin is injected into a mold under reduced pressure, and by bringing the pressure to normal pressure, the resin is molded by the pressure at that time. This is to be filled inside.

The vacuum casting method (1) removes air bubbles, (2) removes the air layer on the inner surface of the mold to obtain a molded product with good transferability from the mold, and (3) returns the pressure from reduced pressure to normal pressure. The advantage is that the pressure applied at the time allows the resin to fill even the smallest details within the mold.

However, when molding a disc-shaped molded product with a thickness of 0.5 to 3III that requires precise dimensional accuracy using the vacuum casting method, the molded product may not be satisfactory due to localized minute bubbles remaining and sink marks. is often not available. In other words, even if the mold is completely filled with resin, the filling density may be low, or due to shrinkage of the resin during curing, circular sink marks may occur near the resin injection hole or on the outer periphery. . Furthermore, the resin in the resinous portion of the injection part is sucked into the board due to resin contraction, resulting in uneven flow. Alternatively, extremely small air bubbles remaining in the resin may expand and remain in the molded product. Although such sink marks and bubbles may appear to be normal when visually observed, they are discovered when magnified and observed more precisely, and often become a problem for precision molded products.

[Purpose of the invention]

The present invention was completed after studying to solve these problems, and the present invention will be described below.

[Structure of the invention]

A resin injection port is provided at a position above the center of the molded product part in a mold for molding a disc-shaped molded product, a vent hole is provided at one or more locations on the outer periphery of the molded product part, and a vent hole is provided at one or more locations on the outer periphery of the molded product part. There is a resin measuring section connected to each on the ventro and a resin measuring section that communicates with each other, and the process of injecting liquid resin from the resin injection port into the mold under reduced pressure.
This is a method for manufacturing a precision molded product, characterized by having a step of curing a liquid resin while applying an air pressure of 4/d or higher.

As a method of applying air pressure to the resin measuring section, there is a method of connecting a pipe that feeds air to the resin section 19 and continuing to send air at a predetermined pressure, or a method of applying a predetermined pressure to the resin measuring section and sealing it. etc. In the latter case, it is also pressurized by expansion of sealed air due to heating during curing. As an example, seal the upper part of 19 parts of resin on the ventro side,
A method is adopted in which a predetermined pressure is applied only to the resin 19 portion on the resin injection port side.

The steps of the present invention will be specifically explained using the drawings.

(1), is the mold, (2) is the molded part of the mold, (
3) is a resin injection port provided on the center of the molded part, (5)
) is 19 parts of resin installed on the resin injection port. 9 is a vent hole provided on the outer periphery of the molded product, and aTJ is a resin 19 portion attached to the vent hole. Figure 1 shows the case where a pipe (6) is connected to the resin retaining part (5) and air is sent to this pipe. Figure 2 shows a case where a pipe (6) is connected to the upper part of the resin 19 part (5), air pressure is applied through this pipe (6), and then this pipe is sealed with an appropriate means (for example, a cock (7), etc.) It is.

In FIGS. 1 and 2, the upper part of the resin 19 part aυ attached to the pentrol is sealed. During casting, the entire apparatus shown in the figure is evacuated in a vacuum tank. In this state, 19 parts (5) of K liquid resin is injected.

The amount of resin injected must be such that an appropriate amount of 19 parts (5) K of resin remains when the mold is filled with the resin. In this manner, the resin is poured into the molded part (2) of the mold. Next, in the case of FIG. 1, the apparatus is returned to normal pressure.

At this time, the resin also migrates to and remains in the resin retainer portion I on the ventro side. Next, 19 parts of resin (5) K from the pipe (7)
O, 01m? A predetermined air pressure of /- or more is applied, and the resin is cured by heating in this state.

In addition, in FIG. 2, the pipe (7) of the device in FIG.
Opening/closing means such as K cock (hereinafter simply referred to as cock) (8
) is provided. In this case, the liquid resin is poured into the molded part (2) of the mold (1) in the same manner as in the case shown in Fig. 1 above, and then a predetermined air pressure of 0.01 kf/- or more is applied from the pipe (7). After addition, the cock (8) is closed to seal the resin 19 part (5) and the molded part (2).

In this state, heat is applied to harden the resin.

Incidentally, the ventro is usually provided with two ICs in symmetrical positions as shown in the figure, but three or more ICs may be provided in symmetrical positions, or in some cases, only one IC may be provided.

The air pressure during resin curing is o, o1kq/d or more, but
If strict characteristics are required for #, α5kf/- or less is preferable. This is because if it exceeds o, skq/d, minute internal strain may occur during curing of the resin.

〔Effect of the invention〕

According to the method of the present invention, by applying air pressure to one or both of the resin retaining parts, the filling density of the liquid resin is increased, and the volume reduction due to the curing shrinkage of the resin that occurs during curing is reduced by 19 parts of the resin. Refilled with resin. Furthermore, since the resin injection port is located above the center of the disc-shaped molded part and the vent hole is located on the outer periphery of the molded part, the resin flows in a well-balanced manner within the molded part and hardens uniformly. Therefore, the generation of bubbles and sink marks is prevented. The obtained molded product has an excellent appearance, and since the pressurizing force of air is small, the internal distortion is very small and the strength is high.

〔Example〕

A disc-shaped molded product with a diameter of 150 mm and a thickness of 1.5 m was molded using a two-component liquid epoxy resin. First, the resin and curing agent are thoroughly mixed, and the molded product part (2) K of the mold under reduced pressure is passed through the injection port (3) from the resin part (6) in Fig. 1.
Injected. At this time, the resin part a1 on the ventro side is also filled with resin. After that, the pressure was returned to normal, and while air pressure of 1 kg, /J was flowing through the pipe (6), the temperature was 9
The resin was cured for 5 hours at 0°C. The resulting disc-shaped molded product has a uniform thickness, a smooth surface, and no bubbles or sink marks.
Internal strain was also very small.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic sectional views showing embodiments of the present invention.

Claims (1)

[Claims] A resin injection port is provided at a position above the center of the molded product part in a mold for molding a disc-shaped molded product, a vent hole is provided at one or more locations on the outer periphery of the molded product part, and a vent hole is provided at one or more locations on the outer periphery of the molded product part, and a vent hole is provided at one or more locations on the outer periphery of the molded product part. There is a resin holding part connected to each on the ventro and a resin holding part, and in the process of injecting liquid resin from the resin injection port into the mold under reduced pressure, 0.01k is added to the resin holding part.
A method for manufacturing a precision molded product, comprising the step of curing a liquid resin while applying an air pressure of g/cm^2 or more.