JPH10305446A - Manufacture of foam molded body and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve productivity and reduce the generation of product defects such as the formation of thin walls, cracks and sections of demonstrating the filling of physical disorder locally by not only eliminating the pan handling work but also improving the fluidity of a foaming raw material in a mold. SOLUTION: A molding material shielding sheet 11 of ventilation properties is brought into contact with and retained in the contact state on an inner mold of a vent hole formed on a top force 3 of a split molding tool 1 through the suction force following the operation of a vacuum suction device to exhaust only gas and in-mold residual air to the outside of a mold while preventing the leakage of the foam molding material to the outside of the mold and carry out the given foam molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a foam molded article such as polyurethane foam used as a cushion body of a vehicle seat or a seat back, for example, and more particularly, to a split molding die. TECHNICAL FIELD The present invention relates to a method for producing a foamed molded article having a predetermined shape by injecting a foaming raw material into a mold and foaming the foamed material into a mold surface shape, and a production apparatus used for the production.

[0002]

2. Description of the Related Art In a split mold used in the production of this kind of foamed molded article, a gas generated at the time of foaming and residual air in the mold do not cause a defective product such as a missing wall or a cavity in the foamed molded article. In order to achieve this, a vent hole for allowing the gas and residual air to escape from the inside of the mold to the outside of the mold is generally formed in the upper mold.

[0003] However, in the case of the general configuration in which only the vent hole is formed in the upper mold as described above, gas and residual air are allowed to escape from the mold only by the foaming pressure of the foaming material. When the vent hole is small, it is difficult to smoothly release the gas that continues to be released for several minutes from the start of the foaming reaction to the outside of the mold, and the gas is accumulated in the mold and the pressure in the mold rises above a certain level. As a result, underfill and cracks are likely to occur. In addition, if the vent holes are enlarged to make it easier for gas and residual air to escape to the outside of the mold, or if countless vent holes are formed in the upper mold, the foam molding material leaks out of the mold through the vent holes. If the material leaks and the leaked molding material (commonly called bread) remains attached to the mold, the finish of the next foam molded product deteriorates.
It is necessary to manually remove the bread every foam molding cycle, and the work and time required for the bread taking operation require a longer molding cycle and a costly disposal of the removed bread. .

Further, in order to solve the above-mentioned problems, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-232832, a vent hole provided in an upper mold is formed of the same material as that of a foam molded article. Japanese Patent Application Laid-Open No. Hei 1-2-23250 discloses a method in which only gas and air are released from the mold with a sheet piece interposed therebetween, and the foam molding material is impregnated into the sheet piece and cured to prevent leakage from the mold. And JP-A-3-1
As disclosed in Japanese Unexamined Patent Publication No. 32311, the vent hole is closed by using a breathable synthetic paper instead of a sheet piece made of a foamed molding material, and gas and residual air in the mold are released to the outside of the mold. A material for blocking the passage of a material, and further disclosed in JP-A-5-116157 and JP-A-5-116157
As disclosed in JP-A-116158, a vent hole is closed using a foam-forming deaeration sheet made of a laminate of a fibrous sheet and an open-cell sheet, and the foam molding material leaks out of the mold. And the like, in which gas and residual air in the mold are discharged to the outside of the mold through a deaeration sheet while preventing the occurrence of such problems.

[0005]

However, among the above-mentioned prior arts, those using a sheet piece made of the same material as the foam molding material can eliminate the need for material loss and panning work after molding. On the other hand, since the foam molding material impregnated in the sheet piece is hardened and integrated with the final foam molded body, the integrated part is harder than the other parts and is locally localized in terms of cushioning and the like. There is a drawback that it will give a sense of incongruity, and when using other air-permeable synthetic paper or a deaerated sheet made of a laminate, use double-sided adhesive tape when attaching them,
Since special mounting means such as sandwiching and fixing between split molds are adopted, it takes time and effort to replace such synthetic paper and deaeration sheet, and the synthetic paper and deaeration sheet are also required. Therefore, it is difficult to maintain the molded product in a close contact state so as not to rise from the mold surface, and therefore, there is a problem that the finish of a predetermined foamed molded product is likely to be deteriorated.

[0006] In addition, in the case of the above prior art,
Similar to the general configuration in which only a vent hole is formed in the upper mold, gas and residual air are released out of the mold through synthetic paper or a degassing sheet only by the foaming pressure of the foaming material. The gas and residual air discharge performance out of the mold is poorer than that of the simple structure, and the foaming material in the mold is slow to move around. Despite the abolition of, improvement in productivity could not be expected.

[0007] The present invention has been made in view of the above-described circumstances, and is intended to not only eliminate the breading operation, but also to improve the fluidity of the foaming raw material in the mold to achieve a remarkable improvement in productivity. It is an object of the present invention to provide a method and an apparatus for manufacturing a foamed molded article which can reduce the occurrence of product defects such as missing parts, cracks, and parts that give a sense of incongruity locally.

[0008]

In order to achieve the above object, a method for producing a foamed molded article according to the present invention according to the first aspect of the present invention comprises the steps of: It is a method of producing a foamed molded article of a predetermined shape by foaming, having air permeability on the inner end side of a vent hole provided in the upper mold of the split mold, and a foam molded material A sheet piece for blocking the passage is provided, the sheet piece is held in contact with the inner end of the vent hole by the operation of the vacuum suction device connected to the vent hole, and the passage of the foam molding material is blocked by the sheet piece. While discharging the gas and air in the molding die to the outside of the molding die.

According to the first aspect of the present invention, by operating the vacuum suction device, the sheet piece can be held in close contact with the inner end of the vent hole via the suction force. While it is possible, the foaming material injected into the mold is positively flowed in the mold to improve the circumference of the entire mold to promote the foaming reaction, and to generate gas accompanying the foaming reaction. The foam molding material can be stopped in the mold while smoothly discharging only the residual air in the mold to the outside of the mold through the sheet piece. This eliminates material loss and the occurrence of bread, which reduces not only the amount of raw materials used, the elimination of bread picking work, and the cost of disposing of bread, but also the accumulation of gas in the mold and the pressure in the mold. Can be efficiently produced without any underfilling or cracking caused by the rise of a certain value.

A manufacturing apparatus for a foamed molded product according to the present invention is divided into at least an upper and lower part, wherein a molding die having a vent hole in an upper die is provided.
A vacuum suction device connected to the vent hole of the upper mold to discharge gas and air in the molding die to the outside of the mold, and abutting against an inner end of the vent hole by a suction force generated by the operation of the vacuum suction device; It is characterized by being provided with a sheet piece that has retained air permeability and blocks passage of the foam molding material, and a control device that controls the operation of the vacuum suction device. According to the manufacturing apparatus having the above-described structure, the conventional molding die is used as it is without any improvement to the existing molding die, and only the vacuum suction device and the above-mentioned sheet piece are separately added. In addition, the same manufacturing method as described above can be easily and economically implemented, and a foamed product having a good finish can be manufactured with high productivity.

Further, in the apparatus for manufacturing a foamed molded article according to the second aspect of the present invention, the vent hole provided in the upper mold may have one central vent hole and a circumferential direction formed around the central vent hole. By using a structure having a plurality of ventilation holes arranged at equal intervals, the suction force caused by the operation of the vacuum suction device is held in contact with the inner end of the vent hole. By dispersing the suction force on the sheet piece over almost the entire surface of the sheet piece, the sheet piece can be stably and closely adhered to the inner end of the vent hole without dropping, and the deformation of the sheet piece can be suppressed. Thus, the finish of the foam molded article can be further improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic perspective view of an apparatus for manufacturing a polyurethane foam seat cushion body applied as an apparatus for manufacturing a foam molded article according to the present invention, and FIG. 2 is a cross-sectional view of an assembled state of a molding die.

In FIG. 1 and FIG. 2, a molding die 1 is divided into a rectangular box-shaped lower die 2 and an upper die 3 which is pivotally connected to one side of the lower die 2 so as to be swingable and openable. The inside of these split molds 1 is formed in a cavity 4 in the shape of a vehicle seat cushion body. In the lower mold 2 of the split mold 1, a hot water pipe (not shown) called a serpentine pipe through which hot water of about 60 ° C. flows is incorporated as an auxiliary heat source for increasing the foaming efficiency. .

On the other hand, circular female screw holes 5 penetrating inside and outside the mold are formed at a plurality of positions of the upper die 3 of the split molding die 1, and a stainless steel vent hole cylindrical member 6 is screwed into these female screw holes 5. It is fixed. As shown in FIGS. 3 and 4, the vent hole cylindrical member 6 includes one central ventilation hole 7a and four ventilation holes 7b arranged at equal circumferential intervals around the central ventilation hole 7a. The vent hole 7 having a total of 6 mmφ or more is formed.

One end of an intake tube 9 that connects the vent hole 7 to a vacuum suction device (not shown) through a nipple 8 screwed to the cylindrical member 6 at the outer end of the vent hole cylindrical member 6. Are connected to each other, and a control panel 10 as a control device for controlling the operation time and the intake air amount of the vacuum suction device is interposed in the middle of the suction tube 9. Further, separately from the split mold 1, the vacuum suction device, the control panel 10 and the like, the suction force accompanying the operation of the vacuum suction device abuts and is held on the inner end surface of the vent hole cylindrical member 7 and A sheet piece 11 for closing the vent hole 7 is provided.

As the sheet piece 11, a calligraphy paper which has a gas permeability of about 26 liters / cm ² / min and which blocks the passage of urethane material for foam molding is most suitable. Kraft paper, non-woven fabric, polyethylene sheet, masking tape, etc. with air permeability of 50 l / c
What is necessary is just the thing of m < ² > / min or less.

Next, a method of manufacturing a polyurethane foam vehicle seat cushion using the manufacturing apparatus having the above-described configuration will be described. First, a vacuum suction device is operated with the split molding die 1 being opened, and the suction force of the vacuum suction device is used to abut against the inner end surface of the vent hole cylindrical member 6 which is screwed and fixed to the upper die 3. The vent hole 7 is kept closed. In this state, the molding die 1 is closed, and a two-component polyurethane raw material is injected into the cavity 4 and foamed by self-heating due to the two-component reaction and auxiliary heating by a hot water pipe built in the lower die 2.

At this time, since a suction force is acting inside the mold in association with the operation of the vacuum suction device, the polyurethane material injected into the cavity 4 is positively flowed, and flows around the entire area of the cavity 4. Only the gas and the residual air in the mold, which are foamed while being accelerated and are generated by the foaming reaction, smoothly pass through the sheet piece 11, the plurality of ventilation holes 7 a and 7 b forming the vent hole 7, and the suction tube 9. The urethane foam material is stopped in the cavity 4 while being discharged outside. Thus, by discharging only gas and residual air and preventing the urethane foam material from leaking out of the mold from the vent hole 7, material loss is reduced, and the injection amount of the polyurethane raw material can be reduced accordingly. In addition, since there is no occurrence of so-called bread that the polyurethane material leaked out of the mold adheres to the molding die 1, it is possible to eliminate the need for manual bread-panning work, and to make products such as underfill, cavities and cracks. The occurrence of defects can be significantly reduced.

When the foaming in the cavity 4 is almost completed, specifically, about 10 seconds after the mold is closed, the sheet piece 11 is formed by the foam substantially formed in the cavity 4. At this point, the operation of the vacuum suction device is automatically stopped via the control panel 10 at this time, so that the vacuum can be held in close contact with the inner end of the vent hole cylinder 6. Due to the strong suction force accompanying the operation of the suction device, the above-mentioned seat piece 11 is unnecessarily sucked and deformed, which may cause a deformed portion in a part of the vehicle seat cushion body which is a foam molded article. This makes it possible to form a vehicle seat cushion body having a better finish in appearance.

After that, the split molding die 1 is opened, and the molded vehicle seat cushion body is taken out of the mold 1 together with the above-mentioned seat piece 11, so that a vehicle seat cushion body having a predetermined shape can be obtained. At the time of forming the next vehicle seat cushion body, the vehicle seat cushion body has a good yield by replacing only the above-mentioned seat piece 11 with a new one and repeating the same steps as above.
Also, it can be formed efficiently.

In the above embodiment, the vent hole 7 has one central vent hole 7a and four vent holes 7b arranged at equal intervals in the circumferential direction around the central vent hole 7a. The formed one was used.
As shown in FIG. 5, a vent hole cylindrical member 6 having an annular slit hole 7c may be used. Also in this case, the suction force accompanying the operation of the vacuum suction device is applied to the sheet piece 11. Of the sheet 11
Can be stably adhered to the inner end of the vent hole 7 without dropping the sheet piece 11, and the deformation of the sheet piece 11 can be suppressed to obtain a foam molded article having a good finish.

[0022]

As described above, according to the first aspect of the present invention, the air-permeable material and the passage of the foam molding material are blocked by the suction force accompanying the operation of the vacuum suction device. It is possible to keep the sheet piece in contact with the inner end of the vent hole in a stable and good contact state, and also to improve the circumference of the foaming material injected into the mold to the entire area inside the mold. In addition to eliminating the generation of bread and reducing the amount of raw material used, eliminating the need for bread picking, and eliminating the cost of disposing of bread, the pressure inside the mold exceeds a certain level due to the accumulation of gas in the mold This significantly reduces the occurrence of underfills and cracks due to the rise of the product, as well as the occurrence of product defects such as parts that give a sense of incongruity locally, so that a foamed molded article of a predetermined shape can be efficiently manufactured. To play.

According to the second and third aspects of the present invention, the conventional molding die is used as it is without any need for improvement with respect to the existing molding die, and the vacuum suction device and the above-mentioned structure are used in addition to the conventional molding die. By simply adding the sheet pieces separately, the same manufacturing method as described above can be easily and economically performed, and an effect is obtained in which a foamed product having a good finish can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is an overall schematic perspective view of an apparatus for manufacturing a polyurethane foam-made vehicle seat cushion applied as an apparatus for manufacturing a foam molded article according to the present invention.

FIG. 2 is a sectional view showing an assembled state of a molding die, which is a main part of the apparatus.

FIG. 3 is an enlarged vertical sectional view of a main part.

FIG. 4 is a transverse sectional view taken along line AA of FIG. 3;

FIG. 5 is an enlarged transverse sectional view of a main part showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Split mold 3 Upper mold 7 Vent hole 7a Central ventilation hole 7b Peripheral ventilation hole 10 Control panel (control device) 11 Sheet piece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaya Suzuki 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka Toyo Tire & Rubber Co., Ltd. (72) Inventor Masanobu Sakano 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka No. Toyo Tire & Rubber Co., Ltd.

Claims (3)

[Claims] 1. A method for producing a foam molded article having a predetermined shape by foaming a foaming raw material injected into a split mold into a mold surface shape, wherein the foam material is provided on an upper mold of the split mold. A sheet piece having air permeability and blocking passage of the foamed molding material is provided on the inner end side of the vent hole, and the sheet piece is inserted into the vent hole by operating a vacuum suction device connected to the vent hole. A method for producing a foam molded article, wherein the gas and the air in a molding die are discharged to the outside of the molding die while being held in contact with an end portion and the passage of the foam molding material is blocked by the sheet piece. 2. A molding die having at least an upper and lower portion, wherein a vent hole is provided in an upper die, and gas and air in the molding die connected to the vent hole of the upper die to the outside of the die. A vacuum suction device for discharging, having air permeability held in contact with the inner end of the vent hole by a suction force accompanying the operation of the vacuum suction device, and
An apparatus for manufacturing a foam molded article, comprising: a sheet piece for blocking passage of a foam molding material; and a control device for controlling operation of the vacuum suction device. 3. The foam molding according to claim 2, wherein the vent hole is configured to have one central vent hole and a plurality of vent holes formed around the central vent hole at equal intervals in a circumferential direction. Body manufacturing equipment.