JPS63293012A - Monolithic foam molding method - Google Patents

Abstract

PURPOSE:To prevent a dry spot of a cell and a sink void by eliminating breakdown of a film, by supplying air pressure on the backside of an insert after a space between the insert, whose opening part has been closed with the film, and the skin has been filled up with a foamed body. CONSTITUTION:An insert 3 including a film 6 and the skin 4 are set up respectively on a top and bottom forces 1, 2 and mold clamping is performed by casting a predetermined quantity of a foaming stock solution over the skin 4. The roaming stock solution is foamed through heating, the inside of a foaming space is filled with a foamed body, and pressure to be applied to the film 6 is increased rapidly. As cure of t he foamed body 8 from directly after filling up of the same up to directly before complete foaming of the same is incomplete, a dry spot of a cell is apt to occur due to breakdown of the film 6. Therefore, when foaming pressure to be applied to the film 6 is offset by the air pressure by supplying the air pressure to the backside of the insert 3 through an air supply hole 7 provided on the force 1, breakdown of the film 6 can be prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method of molding a foamed molded article of an insert and a skin material, and in particular, sets an insert whose opening is closed with a film and a skin in a mold. The present invention also relates to an integral foam molding method in which a foamed material is foamed in a space between the insert and the skin.

(Prior art) This type of integral foam molding method can suppress the leakage of foam material from the insert opening using a film, and can provide a molded product without molding. (For example, Japanese Patent Application Laid-Open No. 57-120421, Japanese Patent Application Laid-Open No. 81-141)
3525, etc.), in the integral foam molding method, the film is usually 50 to 150 J.
A synthetic resin film having a thickness of L11 is used and is previously applied to the insert by a suitable method such as vacuum forming.

(Problems to be solved by the invention) However, according to the above conventional integral foam molding method,
Since the foaming space is completely sealed by the film, the foaming pressure becomes high. For example, if the insert has a relatively large opening, the film may not be able to withstand the foaming pressure and break. When this kind of film damage occurs, which often happens, the sudden pressure difference causes gas to run all at once through the foam, causing cell roughness on the surface of the foam that comes into contact with the skin, and this cell roughness. Not only will the unevenness be transferred to the skin, leading to a deterioration in surface quality, but also the loss of gas will cause so-called sink voids to occur in the foam, leading to a deterioration in cushioning properties. It was wanted.

(Means for Solving the Problems) The present invention has been made in order to solve the problems of the conventional art as listed in L.The present invention is characterized by the fact that at the latest, the foam is placed in the foam space in the mold. After filling up, air pressure is supplied to the back side of the insert through the hole provided in the mold to offset the foaming pressure applied to the film that closes the opening of the insert.

(Function) In the monolithic foam molding method for L structure acid, the foam fills up the foam space in the mold, increasing the foaming pressure, and even if the foaming pressure destroys the film, the back of the insert Since the air pressure supplied to the sides offsets the foaming pressure, destruction of the film is prevented.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In Fig. 1, 1 is an upper mold, and 2 is a lower mold. An insert 3 is set in advance in the L-shaped 1, and a synthetic resin skin 4 formed by, for example, slush molding is set in the lower mold 2. In the illustrated mold closed state, a desired foaming space 5 is formed between the insert 3 and the skin 4. A synthetic resin film 6 is previously applied to the side of the insert 3 facing the foaming space 5 by a method such as vacuum forming, and the opening 3a of the insert 3 is covered with the film 6. There is.

Further, an air supply hole 7 is bored in a portion of the upper mold 1 corresponding to the opening 3a to communicate the inside of the mold with the outside of the mold.

This hole 7 is connected to an air source (not shown) outside the mold, and a predetermined air pressure is supplied to this.

During foam molding, first insert 3 containing film 6 is placed in upper mold 1 with the mold open.

Set the outer skin 4 on the lower mold 2, and then set the outer skin 4 on the lower mold 2.
Pour a predetermined amount of foaming stock solution (for example, urethane foam stock solution) into F and close the mold. Next, put the closed mold into an oven and heat and maintain it at a temperature of 40 to 60°C, for example. . By this heating and holding, the foaming stock solution foams, and the foam 8 gradually fills up in the foaming space 5. During this time, as shown by the solid line A in FIG. 2, the pressure applied to the film 6, that is, the foaming pressure increases rapidly. This foaming continues even after the fill-up point (point a), and the foaming pressure continues to rapidly increase as shown by the solid line A, and then gradually increases to reach a peak near complete foaming (near point b). It gradually decreases until the mold opening point (0 point).

By the way, the range t from just after the fill-up of the foam 8 (point d) to just before complete foaming (point e) is a range where cell roughness is likely to occur due to destruction of the film 6 because the foam is still incompletely cured. Therefore, this range t
How to prevent the destruction of the film 6 in this process is important in preventing cell roughness. Therefore, in the present invention, the insert is inserted through the air supply hole 7 provided in the upper mold l in the range T (Fig. 2) from the point a when the foam 8 fills up in the foaming space 5 to the point when the foaming is completed. Supply appropriate air pressure to the back side of 3. By supplying this air pressure, the foaming pressure is offset in the film 6 portion, and as a result, the pressure applied to the film 6 appears to be in the upper range pressure, as shown by the broken line B in FIG. destruction is prevented. Incidentally, in conventional integral foam molding, the second
The foaming pressure shown by the solid line A in the figure was applied to the film 6 in one direction, and the film 6 could not be avoided being destroyed.

Note that the above air supply range T may be set at any time as long as it can cover the cell roughness range t.
In order to prevent extreme deformation of the film 6, the starting point is preferably at the latest a point a when the foam 8 fills up in the mold and the foaming pressure increases to a certain extent. In addition, if the end point of the air supply SA Q area is extended to the mold opening point C, communication between the cells will progress and deterioration of surface quality due to air expansion during use can be more reliably prevented. become.

In addition, the timing for supplying and stopping the two-legged air is as follows:
A pressure sensor may be attached to the upper mold 1 or the lower mold 2, and the pressure in the foaming space 5 may be actually detected by this pressure sensor, and the determination may be made using this result as a trigger.

(Effects of the Invention) As explained above in detail, the integral foam molding method according to the present invention supplies air pressure to the back side of the insert at the latest after the foam fills up the foam space in the mold. Since the foaming pressure applied to the film is offset by the foaming pressure applied to the film, the film is not destroyed by one foaming pressure, and molding defects such as cell roughness and sink voids can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a mold for carrying out the integral foam molding method according to the present invention, and FIG. 2 is a cycle diagram showing changes in pressure applied to the film in the integral foam molding method. 1... Upper mold, 2... Lower mold 3... Insert, 3a... Opening 4... Epidermis,
5... Foaming space 6... Film, 7.
... Hole 8 ... Foam

Claims (1)

[Claims] (1) In an integral foam molding method in which an insert whose opening is closed with a film and a skin are set in a mold, and a foam material is foamed in a space between the insert and the skin, the foam is formed in the space at the latest. After filling up,
An integral foam molding method characterized in that air pressure is supplied to the back side of the insert through a hole provided in the mold to offset the foaming pressure applied to the film.