JPH068349A - Method for molding rubber product - Google Patents

Abstract

PURPOSE:To mold a rubber product pref. in both of productivity and quality because the weighing of a material can be automated and the quality of a molded product is enhanced and material loss is almost eliminated. CONSTITUTION:A material (m) is weighed to be injected into a mold 11 having a shape almost same to that of a product by an injection molding means 1. The unvulcanized intermediate molded product A1 thus formed is taken out of the mold 11 to be transferred to a mold 21 having the same shape as the product and molded and vulcanized by a compression molding means 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the measurement, molding, and molding of materials.
The present invention relates to a method for molding a rubber product including vulcanization.

[0002]

2. Description of the Related Art As a molding method for rubber products and resin products,
It is well known that there are compression molding and injection molding.

The compression molding is a method in which a powder or a small piece of material is weighed and placed in a cavity such as a mold, and is heated while being pressurized (including vulcanization, curing and solidification). Since the pressure can be applied uniformly to the material, there are few restrictions on the material, including the fact that orientation is difficult to occur, and there are advantages such as almost no material loss and low equipment costs, but the material is measured step by step. It is difficult to automate because it must be done, and there is a disadvantage in terms of productivity.

On the other hand, in injection molding, the material is heated and fluidized by a rotating screw and the like, and then the material is injected (including vulcanization) by injecting the material into the mold at a high pressure from a nozzle at the tip of the material. In the case of injection molding, it is possible to automatically measure the material based on the amount of movement of the screw, etc. , More often obtained by injection molding. However, the pressure (injection pressure) for molding acts on the material inside the cavity only from the gate, so it is easy for orientation to occur in the molded product and defects such as weld lines to occur. And in terms of quality, it is generally said that it does not reach the compression molding method. Transfer molding, which is a molding method having an intermediate property between compression molding and injection molding, has the same quality disadvantage for the same reason.

However, in recent years, as a kind of injection molding method,
A molding method called injection compression molding has been developed. This is a method in which the mold is compressed immediately after the material is injected from the nozzle into the mold to reduce the internal volume. Since a uniform pressure can be applied in the mold by a method in which the principle of compression molding is combined with the injection molding method, it is possible to provide a molded product quality equivalent to that of the compression molding method.

[0006]

Another drawback of the injection molding method is that there is a large amount of material loss, in addition to the problem of quality including restrictions on materials. This is because the material remains in the sprue and runner gate parts of the mold, and the remaining material cannot be reused and must be disposed of, resulting in material loss. Even in the case of the above-mentioned injection compression molding method, the material left in the runner or the like and vulcanized is still a loss, and this point is not improved at all.

As described above, in the conventional molding methods such as injection molding, compression molding, transfer molding, and the like, there are always problems associated with quality and production cost.

An object of the present invention is to provide a molding method for a rubber product or the like, which is capable of automating the material measurement, has a high quality of the molded product, and has almost no material loss-in terms of both productivity and quality. is there.

[0009]

According to the method for molding a rubber product or the like according to the present invention, an unvulcanized state is obtained by measuring and injecting a material into a mold corresponding to the general shape of the product using injection molding means. Then, the material (intermediately molded product before being made into a product) is taken out from the mold, transferred into a mold corresponding to the product shape, and then molded and vulcanized by compression molding means.

[0010]

In the molding method of the present invention, as described above, the rubber material (unvulcanized rubber) for molding in the mold in the first step.
Is injected to shape the general shape of the product, and then it is transferred to an unvulcanized mold for the process, and compression molding is performed to obtain a desired product shape and vulcanization. In other words, in the process of, the injection molding means is used to measure and measure a predetermined amount of material.
Although it is injected to form a rough shape, vulcanization is prevented from proceeding due to temperature adjustment in the mold. In the other step, the original molding and vulcanization for producing the product are performed by applying pressure and heating in the transferred mold.

From the above points, this molding method has
It has the following features. That is, 1) The amount of material corresponding to the volume of the product is determined by the measuring function of the injection molding means (it is generally possible to give the function to the screw or plunger for injection as described above). It is automatically weighed and injected.
In other words, the metering of the material can be automated and efficient as in the case of normal injection molding methods.

2) Since the unvulcanized material is molded and vulcanized by being pressed and heated in the same manner as the compression molding, the quality of the obtained molded product (product) depends on the compression molding method. It is as good as. That is, since uniform pressure acts on the entire mold, the orientation is small and defects such as weld lines are unlikely to occur. In this regard, there are few material restrictions on the object to be molded.

Since vulcanization is not carried out in the mold of the step 3), the material is not vulcanized even at the sprue and runner gate portions necessary for injection. This means that the material remaining in those parts has not been vulcanized, so it will enter the mold (cavity) together with the newly injected material in the next process using the same mold, and part of the product It means that it will not be a loss.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be introduced with reference to FIGS. This example shows a vibration-proof shaft support member having a structure shown in FIG. 2C, that is, a rubber (NR) cushioning material between an inner cylinder i made of metal and an outer cylinder o made of metal. (Rubber material) A rubber product A2 in which u2 is integrated is obtained.
1 and 2 show the steps of molding the product A2.
From (a) to (b) and (c), and also to Fig. 2 (a), (b), and
(c) is a schematic diagram in order. The molding method of the product A2 will be described below with reference to these drawings.

As a first step, first, as shown in FIG. 1 (a), an injection molding means 1 including an injection device 2 and a mold 11 is used, and an intermediate molded product A1 (not yet formed into the above product A2) is used. Finished product).

The injection device 2 used in the process of FIG. 1 (a) has a screw 3 for plasticizing a rubber material (raw material).
And a plunger 4 for measuring and injecting the plasticized material are independently provided in separate cylinders. In this device 2, 1) First, the valve 5 is closed, and the rubber material originally granular is heated by the screw 3 (80-
90 ° C) · Plasticize the material by kneading,
2) Next, open the valve 5, send the semi-fluid material m into the cylinder (injection pot) of the plunger 4, and measure it based on the moving amount of the plunger 4. 3) Open the valve 5 again The material m is measured and injected in such a manner that the material m is injected from the nozzle 6 by closing and closing the plunger 4 with a hydraulic cylinder (not shown). The amount of the material m injected at one time by this measurement is matched with the volume amount of the rubber material u2 in the rubber product A2 (FIG. 2 (c)) to be finally obtained.

The mold 11 includes a fixed mold plate 12 including a sprue bushing 13, a runner 14a and a gate 14.
A combination of another fixed mold plate 14 having b, and a split mold plate 15 that can slide along the guide portion 14c of the mold plate 14 to the left and right in the drawing is used. This mold 1
In using 1, the mold plate 15 is first opened right and left, the above-mentioned inner cylinder i is inserted, the mold plate 15 is closed again, and then the nozzle 6 of the injection device 2 is sprue bushed 13.
Then, the material m is injected by pressing. The injected material m is
From the sprue 13a of the bush 13 passes through the runner 14a and the gate 14b and enters the cavity 15a of the template 15. In this embodiment, the vulcanization temperature of rubber (NR rubber) is about 180 ° C., while the material m in the mold 11 is m.
Is adjusted to about 80 ° C by adjusting the temperature.

After the step of FIG. 1A, the template 15 of the die 11
The intermediate molded product A1 shown in (b) can be taken out by opening. The intermediate molded product A1 is one in which an unvulcanized rubber material u1 is attached to the outer peripheral surface of the inner cylinder i.
Has the same amount as the rubber material u2 of the product A2 and has a similar shape (simpler than u2).

In the subsequent second step, the intermediate molded product A1 is subjected to compression molding in the manner shown in FIGS. 1 (c), 2 (a) and 2 (b). The compression molding is performed using the compression molding means 20 including a mold 21 and a mold clamping (press) mechanism (not shown) shown in the drawing.

First, as shown in FIG. 1 (c), the outer cylinder o is inserted into the middle mold 23 and the lower mold 24 separated from the upper mold 22, and the above-mentioned intermediate molded product A1 is set. Continued Figure 2
As shown in (a), the mold 21 is closed, the mold clamping mechanism applies pressure from above and below, and the mold 21 is heated. After keeping the temperature of the mold 21 at 180 ° C. for about 3 minutes,
As shown in (b), the mold 21 is opened and the product A2 is taken out. The upper and lower end portions of the rubber material u1 in the above-mentioned intermediate molded product A1 are
A round protrusion 22a of the upper die 22 and a similar protrusion 24 of the lower die 24
2a is pressed and molded, and vulcanization proceeds in that state, so that the product A2 thus obtained has a shape as shown in FIG. 2 (c) having recesses in the upper and lower ends of the rubber material u2. Since it is vulcanized, the rubber material u2 has appropriate hardness and strength, and the adhesive force with the inner cylinder i and the outer cylinder o is also strong.

FIG. 3 schematically shows, as another embodiment, a molding procedure for a rubber product B2 comprising a rubber material v2 having a cross-sectional shape as shown in FIG. 3 (d), an inner cylinder j and a disk p. . This product B2 is manufactured as follows.

First, the inner cylinder j shown in FIG. 3 (a) is inserted into a mold (not shown. Refer to FIG. 1 or FIG. 2 for facilities / apparatus below), and the same procedure as in FIG. 1 (a) is performed. Then, an appropriate amount of rubber material is injected by injection molding means to obtain an intermediate molded product B1 shown in FIG. 3B, that is, an unvulcanized rubber material v1 attached around the inner cylinder j. Subsequently, the intermediate molded product B1 is transferred to the mold of the compression molding means,
As shown in FIG. 3 (c), a hollow disk p is placed at a position outside the rubber material v1.
(See FIG. 1 (c)). According to FIG. 2A, the mold is closed, the rubber material v1 is molded and vulcanized by applying pressure and heat, and the finished product B2 is taken out in the same manner as in FIG. 2B. The original rubber material v1 is considerably deformed according to the shape of the mold in the compression molding means, and the product B
As shown in FIG. 3 (d), the rubber material v2 in No. 2 has a thin U-shaped cross section and is axially symmetric, and has a shape in which the disk p is gripped at the outer portion. However, in the point that the inner side is attached to the outer peripheral surface of the inner cylinder j and the point that the total volume does not change, the rubber material v2
It can be said that they have the same basic shape as the original rubber material v1.

FIG. 4 shows another embodiment of the present invention. In this example, a rubber material w1 is attached around the inner cylinder k shown in FIG.
An intermediate molded product C1 as described above is prepared, and it is unvulcanized and put into a mold of compression molding means and subjected to compression molding including vulcanization to obtain a rubber product C2 shown in (c). In this product C2, the rubber material w2 is integrated around the inner cylinder k, and tapered portions are formed near both ends, but no other member is attached to the outside of the rubber material w2.

In the present invention, a so-called total rubber product having no insert member such as an inner cylinder and an outer cylinder can be molded, and FIG. 5 is a diagram illustrating this.
That is, first, a cylindrical unvulcanized intermediate molded product D1 is formed by using injection molding means. Then, by compression-molding it in another mold, a rubber product D2, that is, an anti-vibration member having a shape that can be easily attached is obtained. Since the intermediate molded product D1 is not vulcanized at that stage and is not integrated with the metal fittings such as the inner cylinder, the intermediate molded product D1 should not be deformed when it is taken out from the mold (injection molding means). You need to be careful.

By the way, although the description has been made mainly on the rubber product, the molding method of the present invention can be applied to the molding of the resin product. However, in the case of resin, since the intermediate molded product at the unvulcanized stage is considerably softer than rubber, considerable effort is required when transferring it from the injection molding means to the compression molding means. In the case of resin, the process called "vulcanization" in the above explanation is called "curing".
Or it should be read as "solidify".

[0026]

According to the method for molding a rubber product or the like of the present invention, preferable molding is possible in terms of both productivity and quality. That is, 1) Since the material can be automatically metered, the production efficiency is high.

2) Regardless of the type of material, it is possible to obtain a molded product with almost no orientation or weld lines.

3) Material loss due to the sprue and runner / gate portions does not occur.

4) There is also an advantage that the cost is directly reduced in terms of equipment, such as a small mold clamping force required, and a molding machine or a mold having a relatively simple structure can be used.

To summarize the above, the molding method of the present invention is
It can be said that the advantages of the injection molding, compression molding, and transfer molding are collected.

[Brief description of drawings]

1A to 1C show, as an embodiment of a molding method of the present invention, a part of a step of molding a rubber product A2 shown in FIG. 2C to be a shaft supporting member in the order of FIGS. 1A to 1C. It is a schematic diagram.

FIG. 2 shows the steps following FIG. 1 for molding product A2,
It shows in order of Fig.2 (a)-(c).

FIG. 3 shows a rubber product B as another embodiment different from FIGS. 1 and 2.
It is a schematic diagram which shows the shaping | molding method of 2 in order of Fig.3 (a)-(d).

FIG. 4 shows a method for molding a rubber product C2 as another example in the order of FIGS. 4 (a) to 4 (c).

[FIG. 5] As still another example, a method for molding a rubber product D2 is shown in the order of FIGS. 5 (a) and 5 (b).

[Explanation of symbols]

 1 Injection Molding Means 11 Mold (mold) 20 Compression Molding Means 21 Mold (mold) A1, B1, C1, D1 Intermediate Molded Products A2, B2, C2, D2 Rubber Products

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area // B29K 21:00 105: 24

Claims (1)

[Claims] 1. A material corresponding to a product shape is obtained by measuring and injecting a material into a mold corresponding to a general shape of a product using injection molding means, and taking out the material in an unvulcanized state from the above mold. A method for molding a rubber product or the like, which comprises moving the material into a mold and then performing compression and vulcanization by means of compression molding.