JPH0374886B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is directed to nylon RIM (Reaction Injection).
This relates to a method for manufacturing rubber molds for reactive liquid resin molding, such as molding. Conventional Technology Conventionally, metal molds have generally been used as molds for nylon RIMs. However, although this metal mold has a large cost advantage over the conventional injection molding method for large items with a relatively simple shape, 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, urethane materials have a heat distortion temperature of 70
℃, even when manufacturing as a prototype,
There was a problem in that it was not possible to perform a real-world test. For this reason, a method of molding nylon RIM material with 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 compacted, making it difficult to obtain the dimensions. was. The present invention solves the above problems, and at the same time designs the outer workpiece in consideration of curing shrinkage of the rubber mold.
The purpose of the present invention is to provide a rubber mold for reactive liquid resin molding, such as a rubber mold for nylon RIM, which provides high dimensional accuracy so that the rubber mold is not deformed due to mold jamming during molding. Means for Solving the Problems The present invention includes a step of manufacturing an outer workpiece calculated and designed to meet desired dimensions, 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 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 view of the master model, and making this metal plate the mating surface of the mold. The master model is inserted into this metal plate to create a master model with a metal plate border, and the male mold of the master model and clay mold or the master model with a metal plate border is installed inside the outer work. A process of pouring rubber material to create a female mold with a flat mating surface, and after the female mold hardens, removing the clay or metal plate and pouring the rubber material again using an outer work to create a male mold. The present invention relates to a method for manufacturing a rubber mold for molding reactive liquid resin, which comprises a step of: Function The outer work takes into account the shrinkage of the rubber material during curing or the expansion due to heat during molding, and sets the outer dimensions of the rubber mold to the desired dimensions. Its function is to enable mold clamping with uniform pressure. The male mold of a master model and a clay mold, or the master model with a metal plate rim, has the effect that the mating surfaces of the male mold and female mold become flat, and this especially causes problems caused by misalignment of the molds. It works to suppress variations in dimensions. Examples Example 1 Examples of the present invention will be described below. Box-shaped master model M as shown in Figure 1
A: 184.4mm, b: 214.8mm, c: 47mm. At this time, rubber mold material (Shin-Etsu Chemical Co., Ltd.)
(manufactured by KE1300) shrinks by 1.14% during curing. Now, if the wall thickness t of the rubber mold material from the external dimensions of the master model is 50 mm, then a′; 284.4 mm,
b′: 314.8mm, c′: 147mm. For convenience, these
Considering the standard dimension L, even after curing shrinkage, the standard dimension L
In order to achieve this, the dimensions must take into account shrinkage, that is, (L/1-0.0114=L/0.9886). i.e. a″; 287.68mm, b″; 318.43mm,
c″: 148.7mm. Next, as shown in Figure 2, a stepped bottom plate (step height h ₁ ) was formed by cutting so that dimensions a″ and b″ would be accurate. The side plate 2 is attached so as to surround the rectangular step from all sides.At this time, the height H of the side plate 2 is equal to the height of the step of the bottom plate 3, _h1 , c'', and the top plate 4, as shown in FIG. The length is the sum of the height of the step _h2 . FIG. 4 shows the master model M using the first outer workpiece 1 obtained in this way.
It shows how to make a rubber mold using clay 6. In Figure 4a, M is the master model, 6
is clay and 7 is 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 in 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, a″ and b″ are the standard dimensions with the coefficient of linear expansion (1.054L). i.e. a″;
299.76, b″; 331.80, c″; 60.08. At this time,
H is the height of the step of the bottom plate h ₁ as in the case of curing shrinkage.
c″, plus the height of the upper plate step _h2.The rubber mold and second outer workpiece obtained as above were left in a thermostatic oven at 150°C for 3 hours. I did. Also,
Components A and B of a nylon RIM material (UX-B, manufactured by Ube Industries, Ltd.) were melted by standing in an oil bath at 90° C. for 1 hour, and mixed in an N ₂ atmosphere. This mixed solution was poured into a rubber mold obtained by the method shown in FIG. 4, and left for 10 minutes to harden. In the obtained molded product shown in FIG. 1, a, b, c, l ₁
~ _l5 was 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 results are shown in Table 1.

【table】

[Table] As can be seen from Table 1, conventionally, deviations from the master dimensions of +0.5% or more have been obtained, whereas with the method of the present invention, deviations from the master dimensions are within a range of 0 to 0.2%. I can see that it is calming down inside. Example 2 Using the master model M of Example 1, Example 1
The first outer skin 1 is produced in the same manner as described above. 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 cut out from the iron plate 8 along the outer periphery of the master model M as shown in FIG. to create a master model 9 with an iron plate border. As shown in Figure 6, first a female mold is made (Figure 6a),
Next, after the female mold has 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 the dimensions of the molded product were measured in the same manner as in Example 1, the same results were obtained; in contrast to the conventional method, where the deviation from the master dimension was +0.5% or more, the method of the present invention It can be seen that the deviation from the dimensions is within 0.0 to 0.2%. Effects of the Invention The present invention has the following effects. (1) Since flat parting is formed using clay or a master model with a metal plate border is used, rubber molds can be flexibly created for master models of various shapes and sizes without changing the outer part. can be manufactured, and the manufacturing time can be shortened. (2) In terms of dimensions, in the conventional rubber mold manufacturing method, the deviation from the master dimension was 0.5% or more, but with the present invention, the dimensional variation can be kept within 0.2%, that is, within 40% of the conventional method. It has the effect of being suppressed.

[Brief explanation of drawings]

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 of producing a flat parting surface using clay. FIG. 5 is a perspective view of the master model with an iron plate border attached. FIG. 6 is a cross-sectional view showing a method of manufacturing a flat parting rubber mold using a master model with an iron plate edge. M...Master model, 1...Outside work, 6...Clay,
7...Silicone rubber material, 8...Metal plate, 9...Master model with metal plate border.

Claims (1)

[Claims] 1 The process of creating an outer workpiece calculated and designed to meet the desired dimensions, taking into account the curing shrinkage of the rubber material and the expansion of the rubber mold at the molding temperature, and the process of creating the outer workpiece, which is calculated and designed to meet the desired dimensions, and the male part of the mold is created using a master model and clay. In the process of making a mold, 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 attached to 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 a male mold of a mold using the master model and clay,
A master model with a metal plate border is placed inside the outer work, and a rubber material is poured in to create a female mold with flat mating surfaces. After the female mold hardens, the clay or metal plate is removed and the outer work is placed. 1. A method for manufacturing a rubber mold for reactive liquid resin molding, comprising the step of again pouring a rubber material into a male mold using a mold.