JPH06126756A - Foam forming die - Google Patents

Abstract

PURPOSE:To maintain a gas pressure in a cavity at a specified level until foaming ends and thereby prevent a finished product from becoming deformed by providing a foam pressure adjustment valve which block the outer end part of a product cavity during die clamping and adheres to a plane where a top force and a bottom force fit together and a pressing means which presses the adjustment valve on either of the top force or the bottom force near the outer end part. CONSTITUTION:A core material 5 is arranged in a top force 1 and a skin material 4 in a bottom force 2. Further, a foaming agent liquid is injected into a product cavity 3 and the forces are clamped. A foaming pressure in the cavity increases gradually as a foaming agent 6 developes into a foam. Consequently, the foaming pressure adjustment valve 9 of a parting part is pushed up, overcoming the energizing force of a spring 10. Next, a foaming action takes place in a state where the energizing force of the spring 10 and a foaming pressure are in equilibrium, and an excess foaming material is squeezed out of the parting part to form a squeezed-out part 11. For this reason, a gas pressure in the cavity 3 is maintained at a specified level until the foaming action terminates, so that the having of a molding die 1, 2 need not be opened during foaming and thus a product is prevented from becoming deformed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foaming mold for molding polyurethane foam and the like, and more particularly to a foaming mold equipped with a foaming pressure adjusting means for adjusting the pressure during foaming.

[0002]

2. Description of the Related Art When an integral foam molded article (for example, a product made of a skin material, a foam material, and a core material) is molded using a foam molding die, the gas generated during foam molding must be appropriately discharged outside the molding die. The gas of is encapsulated in the product, and the gas expands rapidly at the time of demolding, so the part where the strength of the product is weak, for example, the boundary between the skin material and the foam material is torn without being able to withstand the internal pressure,
Gas accumulates there, causing problems such as blistering on the surface.

Therefore, in order to reduce the gas pressure generated during foam molding, various methods as exemplified below have been proposed. A method of forming a vent hole in the core material during the curing time (for example, JP-A-63-109018, JP-A-63-1).
(See JP 20609). A method of interrupting the mold closing during the curing time, opening the mold slightly and opening it to the atmosphere.

The method based on FIG. 5 will be described in more detail. With the upper mold 1 and the lower mold 2 opened, the core materials 5 and 5'are arranged at predetermined positions of the upper mold 1, and the skin material 4 is arranged at predetermined positions of the lower mold 2. Next, the foam material liquid is injected into the product cavity 3, the mold is closed before foaming, and the upper mold 1 and the lower mold 2 are fixed by the clamps 7 and 7 '. After the foamed material 6 reaches a predetermined hardness, the pin 8 is pressed in the direction of the thick arrow in the figure to make a hole in the core material 5, and gas is released from this hole.

The method based on FIG. 6 will be described in more detail. The method up to the step of injecting the foaming material liquid into the product cavity 3 to foam the same is the same as the method shown in FIG. After the foamed material 6 has reached a predetermined hardness, the clamps 7 and 7'are removed, the mold is slightly opened and the atmosphere is released to release the gas.

[0006]

However, the above methods and methods have the following drawbacks. Disadvantage of method: The gas is released from the perforated hole, so that the gas releasing area is small, and a large number of holes are required to efficiently remove the gas. However, when a large number of holes are formed in the core material, the strength is reduced. Further, there are many geometrical restrictions on the molding die and the product, for example, the pin 8'cannot be installed at the position shown in the drawing even if the core material 5'is perforated in FIG. Disadvantage of method: The mold is slightly opened and the gas is released by opening to the atmosphere, so when the mold is opened, the foam material 6 expands due to the foaming pressure, for example, as shown in FIG. 7 (the mold closed state is shown in FIG. 6). The widths of the points A (parting surface) and the points B (product part) are widened like the widths of the points C and D in FIG.
The product is too thick. In this case, there is also a method of pushing down the upper mold 1 in order to reduce the thickness of the product part,
Since the product is compressed and becomes hard, it cannot be pushed down to the state shown in FIG.

The present invention is intended to solve the above-mentioned problems of the prior art. The object of the present invention is to enable easy degassing during foam molding without being affected by the shape of the product. Another object of the present invention is to provide a foaming mold that does not cause defects such as strength reduction and deformation of the product when degassing is performed.

[0008]

That is, the foaming mold of the present invention comprises an upper mold, a lower mold, and an upper mold side or a lower mold side in the vicinity of an outer end portion of a product cavity formed by the upper mold and the lower mold. And a foaming pressure adjusting means for adjusting the pressure at the time of foam molding, which foaming pressure adjusting means closes the outer end portion of the product cavity at the time of mold clamping and at the same time the upper or lower mold matching surface. And a pressing means for pressing the foaming pressure adjusting valve against the mold matching surface with a predetermined pressure.

The foaming pressure adjusting means is located in the vicinity of the outer end of the product cavity, that is, at the position of the mold mating surface between the upper mold and the lower mold on the outside in contact with the product cavity. It can be provided on the upper mold side and the lower mold side).

More specifically, the foaming pressure adjusting valve is provided between the product cavity and the outer surface of the molding die, and has a shape that allows the over-foaming pressure in the product cavity during molding to escape to the outside of the mold. It is said that The size, shape, number, installation place, etc. are appropriately selected according to the size and shape of the product to be molded. For example, it is convenient that the foaming pressure regulating valve has a size and a shape such that it can be housed in the upper mold or the lower mold near the outer end of the product cavity, which facilitates the molding work. Examples of the shape of the foaming pressure adjusting valve include a block shape, but are not limited to this. If the number of the foaming pressure adjusting valves is too large, the structure of the foaming mold becomes too complicated. Therefore, it is advisable to reduce the foaming pressure as much as possible so that the foaming pressure can be satisfactorily released.

The pressing means may be any as long as it can press the foaming pressure adjusting valve against the mold matching surface with a predetermined pressure, and specific examples thereof include a spring and an air driving means such as an air cylinder. When using a spring, the biasing force is set appropriately beforehand. When an air cylinder is used, the cylinder is driven based on a signal from a pressure sensor provided in the molding die, if necessary, using a timer or a microcomputer. Alternatively, the plurality of pressing means may be used in combination.

The size and shape of the upper mold and the lower mold are not particularly limited as long as the foaming pressure adjusting means can be provided near the outer end of the product cavity.

[0013]

[Function] When the gas pressure in the product cavity exceeds the predetermined pressure during foam molding, the foam pressure control valve moves to open the outer end of the cavity and the mating surface of the upper or lower mold, and the product cavity is opened. Gas is discharged out of the mold until the gas pressure inside reaches a predetermined value.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

A case of molding the integral foam molded product 9 shown in FIG. 4 will be described with reference to FIGS. In FIG. 4, I-
The I line represents a cutting line, and the state cut along the I-I line is shown in FIG.
This is equivalent to the product section cross section (however, the horizontal orientation is rotated 90 ° to the right for vertical orientation). In FIG. 1, with the upper mold 1 and the lower mold 2 opened, the core materials 5 and 5 ′ are arranged at predetermined positions of the upper mold 1, and the skin material 4 is arranged at the predetermined position of the lower mold 2. Next, the foam material liquid is injected into the product cavity 3, the mold is closed before foaming, and the upper mold 1 and the lower mold 2 are fixed by the clamps 7 and 7 '. As the foam material 6 is formed by foaming, the foaming pressure in the product cavity 3 gradually rises,
As shown in FIG. 2, the foaming pressure adjusting valve 9 is pushed up by overcoming the urging force of the spring 10 which urges the foaming pressure adjusting valve 9 of the parting part.

Next, the foaming proceeds in a state where the urging force of the spring 10 and the foaming pressure are balanced with each other, and the excess foam material protrudes into the parting portion to form the protrusion portion 11. After the foaming is completed, the product is cured, and a predetermined portion indicated by a chain line is trimmed by using a cutter 12 as shown in FIG. Figure 4
As shown in FIG. 3, the protruding portion 11 is joined to the end of the product in a sheet shape, so that trimming is easy and there is no fear of impairing the product shape at this time.

[0017]

As described above, the foaming mold according to the present invention has a foaming pressure control valve that closes the outer end of the product cavity when the mold is clamped and is closely attached to the mating surface of the upper mold or the lower mold. Since there is a foaming pressure adjusting means for adjusting the pressure during foam molding, which consists of a pressing means for pressing the adjusting valve against the mold matching surface with a predetermined pressure, the gas pressure in the product cavity during foam molding has a predetermined pressure. When it exceeds, the foaming pressure control valve moves and the outer end of the cavity that was closed and the mating surface of the upper mold or the lower mold open, and the gas is removed from the molding mold until the gas pressure in the product cavity reaches a specified value. Is released to. Therefore, the gas pressure in the product cavity is maintained at a predetermined pressure until the end of foaming, and since it is not necessary to open the molding die during foaming, there is no problem such as product deformation.

Further, since it is not necessary to open a gas vent hole in the product, the product strength is not lowered, and since it is not necessary to provide a pin for opening the gas vent hole in the mold, the shape relating to the mold and the product Are not subject to any restrictions.

Further, when the molding die of the present invention is used, the trimming is easy because the protruding portion protruding from the end of the product when adjusting the foaming pressure is joined to the end of the product in a sheet form. Moreover, there is no fear of damaging the product shape during trimming.

[Brief description of drawings]

FIG. 1 is an explanatory view when performing integral foam molding using a foam molding die of the present invention.

FIG. 2 is an explanatory view showing a state where a foaming pressure adjusting valve is opened in the case of FIG.

FIG. 3 is an explanatory view when trimming an integral foam-molded product obtained by using the foam-molding die of the present invention.

FIG. 4 is a perspective view of an example of an integral foam molded product.

FIG. 5 is an explanatory diagram of a case where integral foam molding is performed using a conventional foam molding die.

FIG. 6 is an explanatory view when performing integral foam molding using another conventional foam molding die.

FIG. 7 is an explanatory view showing a state where the upper mold is pushed down until the mold is closed in the case of FIG. 6;

[Explanation of symbols]

 1 Upper Mold 2 Lower Mold 3 Product Cavity 4 Skin Material 5, 5'Core Material 6 Foam Material 7, 7 'Clamp 8, 8'Pin 9 Integrated Foam Molded Product 10 Spring 11 Overhanging Part 12 Cutter I-I Line Cutting Line A, Each part of B, C, D products or molds

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B29K 105: 04 B29L 31:58 4F

Claims (1)

[Claims] 1. An upper mold, a lower mold, and for adjusting a pressure at the time of foam molding provided on the upper mold or the lower mold near the outer end of a product cavity formed by the upper mold and the lower mold. The foaming pressure adjusting means includes a foaming pressure adjusting valve that closes the outer end of the product cavity at the time of mold clamping and is closely attached to the upper or lower mold mating surface, and the foaming pressure adjusting means. A foam molding die, comprising: a pressing means for pressing the valve against the mold matching surface with a predetermined pressure.