JPH0321412A - Reaction injection molding method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention applies pressure to the mold in multiple stages until the clearance of the cavity of the mold in which the preform is housed reaches the final clearance set for the product. -Relates to a reaction injection molding method using preforms that can improve the smoothness of the product surface and the strength of the product by fitting together.

[Conventional technology]

In the conventional reaction injection molding method using a preform, the preform is housed in a cavity with a set clearance for the product, and then the reaction injection molding material is simply injected into this cavity to integrate the product with the preform. is being molded.

[Problem to be solved by the invention]

By the way, in the conventional reaction injection molding method, as mentioned above, the preform is housed in a cavity with a preset clearance for the product, and then the reaction injection molding material is simply injected into this cavity and integrated with the preform. Since the product is to be molded, when the reaction injection molding material is injected into the cavity, this preform prevents the reaction injection molding material from penetrating throughout the cavity, especially to the surface side of the preform. As a result, the rough surface of the preform is exposed on the product surface after molding, reducing the smoothness of the product surface, and uneven penetration of the reaction injection molding material into the preform reduces product strength. Was.

The present invention was made against the background of such prior art, and an object of the present invention is to provide a reaction injection molding method that can improve the smoothness of the product surface and the strength of the product.

[Means to solve the problem]

In the present invention, a preform is first housed in a cavity formed internally and a mold is fitted, the clearance of the cavity at this time is set wider than the set clearance of the product, and then a reaction occurs inside this cavity. It is characterized by injecting the injection molding material and then also pressurizing this mold a predetermined number of times until the clearance of this cavity is the set clearance of the final product, before this reaction injection molding material completely solidifies. The present invention provides a reaction injection molding method.

[Effect]

In the reaction injection molding method of the present invention, a preform is first housed in an internally formed cavity and a mold is fitted therein. The clearance of the cavity at this time is set wider than the set clearance of the product.

A reaction injection molding material is then injected into this cavity.

Then, before the reaction injection molding material completely solidifies, the mold is pressurized a predetermined number of times until the cavity clearance reaches the final product clearance to produce the preform-integrated product. Shape. By doing so, the reaction injection molding material evenly permeates the entire cavity and is sufficiently included in the preform. Therefore, the smoothness of the product surface and the strength of the product can be improved.

〔Example〕

The reaction injection molding method of the present invention will be explained below based on the drawings. In describing this embodiment, a reaction injection molding method for a side panel of an automobile will be taken as an example.

The reaction injection molding apparatus used in the reaction injection molding method according to the embodiment of the present invention is a mold clamping press 10 as shown in FIG.
, mold 20, injection molding machine 30, process controller 4
It is equipped with 0. The mold clamping press machine 10 has a mold 20
A commonly used press machine can be used to press and fit the two.

The mold 20 is a mold for molding a product, and as shown in FIG. 2, a cavity 21 is formed therein to accommodate the preform P during fitting.

Note that as this mold 20, a commonly used mold can be used.

In addition, the mold 20 of this example contains a reaction injection molding material Z.
In order to quickly inject and fill the reaction injection molding material 2 into the cavity 21 during injection, the heating temperature of the mold 20 and the vacuum bomb 22 shown in FIG. A mold temperature control [23] is installed externally.

Further, in this embodiment, as shown in FIG. 2, a sealing member housing groove 24 having a substantially semicircular shape when viewed in cross section is provided around the mold 20 around the cavity 2l, and this sealing member housing groove 24 is provided around the mold 20 around the cavity 2l.
4 is provided with a tubular sealing member 50 that expands the tube and prevents the reaction injection molding material Z from flowing out by injecting a liquid or gaseous tube inflation fluid L such as oil into the interior of the tube. ing.

The material of this tubular seal member 50 is as follows:
For example, heat-resistant and highly expansible rubber such as silicone rubber and fluororubber can be used.

Furthermore, as the preform P, a commonly used preform made of carbon fiber and/or glass fiber, for example, can be used. The injection molding machine 30 has a cavity 21 of this mold 20.
A known injection molding machine can be used for injecting the reaction injection molding material Z into the molding machine.

In addition, the reaction injection molding material Z may be a general injection molding material whose main raw materials are nylon, unsaturated polyester, epoxy resin, cyclopentadiene, polyurethane, etc., or a two-component mixture type that is mixed and reacted immediately before injection. Commonly used reactive materials such as can be used.

The process controller 40 sequentially controls the mold clamping press lO, the mold 20, the vacuum pump 22, the mold temperature controller 23, the injection molding machine 30, and the process controller 40 shown in FIG. As a control device for performing reaction injection molding, a commonly used control device such as a numerical control device can be used.

Next, a reaction injection molding method according to an embodiment of the present invention using the reaction injection molding apparatus according to this embodiment will be explained. In the reaction injection molding method according to the embodiment of the present invention, as shown in FIG. 2, first, a preform P is housed in a cavity 21 formed internally, and a mold 20 is fitted with a mold clamping press IO. .

At this time, the clearance of the cavity 21 shown in FIG. 2 is set wider than the set clearance of the product to improve the fluidity of the reaction injection molding material (resin).

Thereafter, the reaction injection molding material Z is injected into the cavity 21 from the injection molding machine 30.

Next, before this reaction injection molding material Z is completely solidified, this mold is clamped a predetermined number of times until the clearance of this cavity 2L reaches the set clearance of the final product, as shown in Figure 3. Pressure is increased using a press IO to form a product integrated with the preform P. Note that this clearance adjustment is performed by adjusting the cavity 21 of the reaction injection molding material Z.
It can also be secured by withdrawing a predetermined amount of the tube inflation fluid L from inside the tubular sealing member 50 after injection into the tubular sealing member 50.

Note that the process controller 4 used in this example
As shown in the flowchart of FIG. 4, first, the preform P is stored in the cavity 21 that is formed internally, and the mold 20 is heated to an extent that the sealing properties of the mold 20 can be maintained. The mold 20 is fitted with the mold clamping press 10 at a pressure of . The clearance of the cavity 2l at this time is set to be wider than the set clearance of the product, as described above.

After that, the pressure inside the cavity 21 is reduced with the vacuum bomb 22, and in step 401, if the reduced pressure inside the cavity 2l is less than the preset pressure reduction standard, the sealing condition when the mold 20 is fitted may be poor. The fitting of the mold 20 is restarted from the beginning, and if the reduced pressure inside the cavity 21 is equal to or higher than the preset reduced pressure standard, the reaction injection molding material Z is injected into the cavity 21 using the injection molding machine 30. Shape.

Next, in step 402, this injection molding machine 3
If the injection pressure at 0 is higher than the standard injection pressure, reduce the mold clamping pressure to widen the clearance of the cavity 21, and then perform injection molding again using the injection molding machine 30.
On the other hand, if this injection pressure is lower than the reference injection pressure, the pressure reduction by the vacuum pump 22 is stopped after a predetermined reference injection time or more has elapsed.

Next, the mold clamping pressure of the mold clamping press 10 is increased to the impregnating reference pressure of the reaction injection molding material Z in the preform P to perform secondary pressurization. Note that the clearance of the cavity 21 when this secondary pressurization is applied becomes the set clearance of the product.

Next, in step 404, if the mold clamping pressure of this mold clamping press 10 has not reached the impregnation standard pressure, the mold clamping press 10 further pressurizes until it reaches the impregnation standard pressure. When the mold clamping pressure of the press machine 10 reaches the same pressure as this impregnation reference pressure, this pressure state is maintained.

Next, in step 405, if the mold clamping pressurization time by this mold clamping press 10 has not reached the preset impregnation standard pressurization holding time, it is held until that time is reached; When the pressure holding time is reached, injection of the reaction injection molding material Z by the injection molding machine 30 is stopped, and molding is completed.

Note that the timing at which the injection molding machine 30 stops injecting the reaction injection molding material Z is not limited to the above-mentioned timing, and may be, for example, after the vacuum pump 22 stops reducing the pressure inside the cavity 21 .

By doing so, the reaction injection molding material Z permeates throughout the cavity 21 evenly and satisfactorily impregnates the preform. Therefore, the smoothness of the product surface and the strength of the product can be improved.

Although the reaction injection molding method of the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and even if the structure and operation are changed without changing the gist, the present invention include.

For example, in the embodiment, a reaction injection molding method for molding an automobile side panel is taken as an example, but the present invention is not limited to this and can be applied to molding any product.

In addition, after performing reaction injection molding by pressurizing the molds in multiple stages in this way, the molds are moved slightly apart from each other to create new clearance in the cavity for surface layer molding.
Next, by injecting a reaction injection molding material for surface layer molding into this clearance, it is also possible to manufacture a product with further improved surface smoothness.

〔Effect of the invention〕

Since the reaction injection molding method of the present invention is such a method, the reaction injection molding material evenly permeates the entire cavity and sufficiently impregnates the preform. Therefore, the effects of improving the smoothness of the product surface and improving the product strength can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view of a reaction injection molding apparatus used in a reaction injection molding method according to an embodiment of the present invention, and Fig. 2 shows a primary pressurized state of a mold in a reaction injection molding method according to an embodiment of the present invention. FIG. 3 is an enlarged sectional view of the main part showing the secondary pressurized state of the mold in the reaction injection molding method of the embodiment of the present invention,
FIG. 4 is a diagram showing a flowchart of a reaction injection molding method according to an embodiment of the present invention. Z; Reaction injection molding material P; Preform 10; Clamping press 20; Mold 21; Cavity 30; Injection molding machine 40° Process controller Fig. 1 20 Fig. 2 Fig. 3

Claims (1)

[Claims] (1) First, the preform is housed in the internally formed cavity and the mold is fitted. At this time, the clearance of the cavity is set wider than the set clearance of the product, and then the reaction inside this cavity is made. It is characterized by injecting the injection molding material and then also pressurizing this mold a predetermined number of times until the clearance of this cavity is the set clearance of the final product, before this reaction injection molding material completely solidifies. reaction injection molding method.