JPS6253809A - Manufacturing method of rubber mold for reactive liquid resin molding - Google Patents

Abstract

PURPOSE:To shorten a manufacturing period of time by enabling manufacture of a rubber mold to be flexible even if an outer frame is not changed, by providing the titled manufacture with a process manufacturing the outer frame, a male mold and a female mold respectively, and a process manufacturing the female mold by casting a rubber material again by making use of the outer frame after cure of the female mold. CONSTITUTION:Dimensions a'', b'' of a stepped bottom plate 3 are formed precisely by cutting and a side plate 2 is fitted. A height H of the side plate 2 is made into a length obtained by adding a height c'' and further a height h2 of a step of a top plate 4 to a height h1 of a step of a bottom plate 3. A rubber mold is manufactured by using a master model M and clay 6 by making use of a first outer frame 1. Silicone rubber 7 is cast into (a) the same and the clay and first outer frame 1 are removed (b) after cure. Then the silicone rubber 7 is cast into (c) and the master model M is unloaded (d) after cure. Then when the temperature of a rubber material has risen up to the molding temperature of 150 deg.C, a second outer frame is manufactured in anticipation of expansion of the rubber. In this instance, the a'', b'' are made into 1.054L which is obtained in anticipation of a linear expansion coefficient to reference dimensions and the H is made into the length obtained by adding the height c'' and further the height h2 of the step of the top plate to the height h1 of the step of the bottom plate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to
The present invention relates to a method for manufacturing a rubber mold for molding reactive liquid resin, such as injection molding.

Prior Art Conventionally, metal molds have generally been used as molds for nylon RIMs. However, although this metal mold is large and has a relatively simple shape, it has a large cost advantage over the conventional injection molding method, but it has little cost advantage when manufacturing small items with a complex shape. . On the other hand, in the vacuum casting method using urethane material, a rubber mold is used and the shape is complicated, and the manufacturing process ranges from small items to large items, and has a large cost advantage.

However, the heat distortion temperature of urethane material is 70°C.
Even when manufacturing prototypes, there was a problem in that it was not possible to conduct actual operational tests. For this reason,
A method of molding a nylon RIM material using a rubber mold has been devised and studied, taking advantage of these two molding methods.

Problems to be Solved by the Invention However, this method has problems such as the effects of curing and shrinkage of the material for the rubber mold, and the deformation of the rubber mold when it is heated and molded, making it difficult to obtain the dimensions. Ta.

The present invention solves the above-mentioned problems, and at the same time designs the outer work in consideration of curing shrinkage of the rubber mold, and at the same time achieves high dimensional accuracy to prevent the rubber mold from being deformed by molding during molding. The object of the present invention is to provide a rubber mold for molding reactive liquid resin, such as a rubber mold for yRIM.

Means for Solving the Problems The present invention provides a step of manufacturing an outer workpiece calculated and designed to meet desired dimensions, taking into account curing shrinkage of the rubber material and expansion of the rubber mold at the molding temperature; The process of creating a male mold using the master model and clay, or cutting out a metal plate that can be fixed inside the outer work according to the plan of the master model, so that this metal plate becomes the mating surface of the mold. Next, the master model is fitted into this metal plate to create a master model with a metal plate border, and the male mold of the master model and clay or the master model with a metal plate border is installed inside the outer work, and the rubber material is A step in which a female mold with a flat mating surface is created by pouring the rubber material into the mold, and a step in which the clay or metal plate is removed after the female mold hardens, and a male mold is created by pouring the rubber material again using an outer work. The present invention relates to a method for manufacturing a rubber mold for molding reactive liquid resin, characterized by comprising:

The non-working work has the function of setting the outer dimensions of the rubber mold to the desired dimensions by taking into account the shrinkage of the rubber material during curing or the expansion due to heat during molding. Its function is to enable mold clamping with uniform pressure.

A master model and a male mold made of clay, or a master model with a metal plate rim, have the effect that the mating surfaces of the male mold and female mold become flat, and this especially reduces the size of the mold due to misalignment. It works to suppress variations.

Example (Example 1) Examples of the present invention will be described below.

The box-shaped master model M as shown in Fig. 1 is a
: I B4.4MM, b ;21 4.8
M111. O; 47ffff. At this time, rubber mold material (manufactured by Shin-Etsu Chemical, KE1300)
shrinks by a factor of 1.14 according to actual measurements during curing. Now, the thickness t of the silicone rubber from the external dimensions of the master model is 5.
If it is 0, a': 2B4.4M111, b'
; 314.8ffff, c/; 57Jff. For convenience, if these are considered as standard dimensions, in order to maintain the standard dimensions even after curing and shrinkage, the dimensions must take into account the shrinkage, that is, (L/1-0.0114=L10.9886). That is, a″: 2 B 7.
68 ho, b": 318.4371ff, c": 57.6
611! Becomes the shoulder.

Next, as shown in Figure 2, a stepped bottom plate (step height h
1) was formed by cutting so that dimensions a" and b" were accurately obtained. A side plate 2 is attached so as to surround this square step from all sides. At this time, the height H of the side plate 2 is the sum of the step height hl of the bottom plate 3, C'', and the step height h2 of the top plate 4, as shown in Fig. 3. There is.

FIG. 4 shows how to make a rubber mold using the master model M and clay 6 using the first outer workpiece 1 thus obtained. In FIG. 4a, M is a master model, 6 is clay, and 7 is a silicone rubber material.

Pour in the silicone rubber 7 in state a. After confirming that the silicone rubber 7 has hardened, the clay and the first outer work 1 are removed as shown in b. Next, as shown by C, silicone rubber 7 is poured into the removed portion and cured. After curing, the master model M was taken out as shown in d.

Next, when the rubber material rises to the molding temperature (150° C.), a second outer work is prepared by taking into account the expansion of the rubber. At this time as well, a workpiece similar to the first outer frame 1 as shown in FIG. 2 is produced. However, at this time, the coefficient of linear expansion is taken into the standard dimensions a" and b (1,064L). That is, a"; 299.76, b"; 331.
80. c"; 60.08. At this time, H is the sum of the height hl of the bottom plate step, C", and the height h2 of the top plate step, as in the case of curing shrinkage. .

The rubber mold obtained as above and the second outer part were
It was left in a constant temperature bath at 0°C for 3 hours. Also, nylon R
The A and B components of the IM material (manufactured by Ube Industries, Ltd., UX-B) were left in an oil bath at 90'C for 1 hour to melt them, and the N
The mixture was mixed under two atmospheres. This liquid mixture was poured into the rubber mold of the present invention, and left for 10 minutes to harden. The first obtained
In the molded product shown in the figure, a, b, c, 1
1 to 15 were measured.

The measured dimensions were compared with the dimensions of a molded product formed using a rubber mold obtained by a conventional manufacturing method. The result is the first
Shown in the table.

Table 1 As can be seen from Table 1, conventionally, deviations from the master dimensions of +0.54 or more have been obtained.
It can be seen that the method according to the present invention keeps the variation within 0 to 0.2%.

(Example 2) Using the master model M of Example 1, the first outer workpiece 1 is produced in the same manner as in Example 1. Next, according to the plan view of the master model M, a steel plate 8 is cut out along the outer periphery of the master model M, and the master model M is placed on the iron plate 8 as shown in FIG. Inset and create a master model 9 with a steel plate border. This is the 6th
As shown in the figure, first a female mold is made (Fig. 6a), then after the female mold is hardened, the iron plate is removed and a male mold is made (Fig. 6b). After the female mold and male mold were cured (Fig. 6C), the master model M was taken out from the rubber mold. When measuring the dimensions of the molded product in the same manner as in Example 1, the same results were obtained, and the deviation from the master dimension was +0.5 using the conventional method.
In contrast, in the method of the present invention, the deviation from the master dimension is within 0.0 to 0.2 inches.

Effect of the invention According to the present invention, there are the following effects.

(1) Forming a flat parting using clay,
Since a master model with a metal plate edge is used, rubber molds can be flexibly produced for master models of various shapes and sizes without changing the outer mold, and the production time can be shortened. This effect is achieved.

(2) In terms of dimensions, in the conventional rubber mold manufacturing method, the deviation from the master dimension was 0.5% or more, whereas in the present invention, the deviation from the master dimension was within 0.2%, that is, within 40% of the conventional method. It has the effect of suppressing variations.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a master model used in an embodiment of the present invention. FIG. 2 is a perspective view of the outer workpiece used when producing the rubber mold. FIG. 3 is a sectional view of the outer workpiece. FIG. 4 is a cross-sectional view showing a method for producing a planar parting surface using clay. FIG. 6 is a perspective view of the master model with an iron plate border attached. FIG. 6 is a cross-sectional view taken along a-a line showing a method of manufacturing a flat parting rubber mold using a master model with an iron plate with a flap. M...Master model, 1...Outer work, 6...Clay, 7...Silicone rubber material, 8...Metal plate, 9...Master model with metal plate border. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure M ---nf-Motelle Figure 4 Figure 5 δ-Golden Buddha 9-1-...Funai-cho-2 Mass Day Figure 6

Claims (1)

[Claims] Taking into account the curing shrinkage of the rubber material and the expansion of the rubber mold at the molding temperature, the process of creating an outer workpiece calculated and designed to meet the desired dimensions, and the process of creating a male mold using a master model and clay. A metal plate that can be fixed inside the outer work is hollowed out according to the plan view of the master model, and the master model is fitted into this metal plate so that this metal plate becomes the mating surface of the mold, The process of making a master model with a metal plate border, and the process of creating a male mold using the master model and clay, or placing a master model with a metal plate border inside the outer work, pouring rubber material, and making sure that the mating surfaces are flat. A reactive liquid characterized by comprising the steps of making a female mold, and after the female mold hardens, removing the clay or metal plate and pouring a rubber material again using an outer mold to create a male mold. A method of manufacturing a rubber mold for resin molding.