JP2000263563A - Method and apparatus for foam molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pour a foaming raw material without pouring pattern without generating an air reservoir in a mold and to make a density entirely uniform by pouring the material from an inlet of a mold, clamping the mold and then foam solidifying the material in the state that the mold is held at a lower pressure than an atmospheric pressure therein. SOLUTION: A predetermined amount of urethane raw material liquid 45 is poured by a pouring head 5 in a mold 4. A dog of a lower portion of a lower mold 3 is kicked to fill the air in an air bag 11, the mold 3 is raised, the molds 2, 3 are sealed and locked by a mold opening/closing device. The air is sucked from the mold by a pressure reducing device 9 to reduce an internal pressure than an atmospheric pressure. When a predetermined time is elapsed, the liquid 45 is foamed, expanded, and arrived at a top of the mold 3. A dog is kicked to draw the air in the bag 11 to lower the mold 3, and locking of the molds 2, 3 is released by the opening/closing device, and a product is taken out. Thus, an input of a complicated pouring pattern to a pouring robot is eliminated, a fault such as a flash, lack or the like is obviated, and the density can be made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam molding method and a foam molding apparatus, and more particularly, to a method for producing a urethane pad used for a seat cushion of a four-wheeled automobile or a motorcycle, and a method for producing the urethane pad. The present invention relates to a molding device used for:

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional automobile seat 101 has a headrest 102 provided at an upper portion thereof,
The vehicle includes a seat back 103 to which the headrest 102 is attached and which is disposed vertically, and a seat cushion 104 which is disposed substantially horizontally. As shown in FIG. 9, the lower portion of the seat cushion 104 is supported by a frame 105, and a urethane pad 104a serving as a main body and a skin (also referred to as a cover) disposed on an outer surface of the urethane pad 104a are provided. 104b). The urethane pad 104a
The lower part of the main part 106 is formed in a convex shape toward the frame 105, and the upper part is formed with a main part 106 substantially in the center in the vehicle width direction, and side parts 107, 1 on both sides of the main part 106.
07 is formed so as to protrude upward.

Next, a method of forming the urethane pad 104a will be described. Conventional molding methods are described in, for example, JP-A-9-286030 and JP-A-10-17522.
7, JP-A-10-24432, JP-A-10-24
-175226 and JP-A-10-17625
As described in Japanese Unexamined Patent Publication, the upper mold is opened, a urethane raw material is injected into the lower mold, and then the upper mold is closed to foam and harden. 10 to 14 show a conventional foam molding apparatus described in the above-mentioned publications and the like. This molding device 110
The molding die 11 includes an upper die 111 and a lower die 112, and the upper die 111 is supported by the lower die 112 so as to be openable and closable.
3 and a robot (not shown) for injecting the urethane raw material liquid 114 into the lower mold 112. An injection head 115 is attached to the end of the arm of the robot, and the injection head 115 receives two types of raw material liquids 114 from a raw material liquid supply source (not shown) via a hose 116.
5.

A procedure for forming a conventional urethane pad using the forming apparatus 110 will be described. First, the upper die 111 is opened by operating the opening / closing device 117 shown in FIG. 11, and in this state, the urethane raw material liquid 114 is injected into the lower die 112 from the injection head 115 as shown in FIG. Next, the upper mold 111 is closed by the opening / closing device 117,
The urethane pad 10 is formed by foaming urethane.
4a is produced.

[0005]

As described above, since the lower side of the urethane pad 104a (see FIG. 9) is convex downward, as shown in FIG.
The internal space 120 of the upper die 111 of the molding die 113 for molding the urethane pad 104a is formed in a curved shape protruding upward. Therefore, in the molding die 113 having such a structure, the internal air 121 is formed by the mating surfaces (also referred to as sealing surfaces) 111 a and 11 of the upper die 111 and the lower die 112.
2a, the air pool 122 is generated in the upper portion of the upper mold 111, and the urethane pad 104a has a shape along the inner peripheral surface of the upper mold 111.
However, there was a problem that molding was not possible.

Before the introduction of the robot, the injection of the urethane raw material liquid 114 was manually performed by an operator. However, the urethane raw material liquid 114 is supplied to the lower mold 112 by an optimal method determined by the shape of the seat pad. It is difficult to perform injection according to the injection pattern, and even if the injection pattern is shifted by only 3 mm, defective products such as underfill, cavities, burrs, and the like may occur. Furthermore, even when the urethane raw material liquid 114 is injected by a robot, considerable experience and intuition are required to find the optimal injection pattern. Repeating the trial many times and teaching the injection pattern to the robot are required. It was also difficult and spent a lot of time and effort.

As shown in FIG. 15, in the cross section of the urethane pad 104a, the inner layer 130, the middle layer 1
Since the density of the urethane pad 104 differs from that of the surface layer part 132, it is difficult to reduce the weight by uniformizing the density of the entire urethane pad 104, and the cost cannot be reduced. For example, the density of the inner layer portion 130 in FIG. 15 is 45 kg / m3, and the density of the middle layer portion 131 is 50 kg / m3.
3. The density of the surface layer 132 is 60 kg / m3.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to prevent the formation of air pockets in a molding die and to inject a foaming raw material regardless of an injection pattern. An object of the present invention is to provide a foam molding method and a foam molding apparatus in which the density is entirely uniform.

[0009]

In order to achieve the above object, a foam molding method according to the present invention comprises the steps of: injecting a foaming material into a molding die from an injection port of the molding die; The foaming material is foamed and hardened while the inside of the molding die is kept at a pressure lower than the atmospheric pressure. The pressure inside the molding die can be made lower than the pressure outside the die by sucking air inside the die. Thereby, for example, when molding a urethane pad, air accumulation does not occur inside the upper mold, it is possible to mold into a good shape, and the entire density is made uniform,
A lightweight urethane pad can be formed.
Uniform density improves product yield,
The sitting comfort of the seat is improved. Furthermore, a non-defective product can be molded without having to control the temperature in the foam molding more strictly than in the conventional case.

Another aspect of the foam molding method according to the present invention is as follows.
The pressure in the molding die is set to 100 to 500 mmHg. A more desirable pressure range is 400 to 450 mmH.
g. Further, the foam molding apparatus according to the present invention comprises a molding die having an injection port and an air vent hole communicating therewith, and a decompression device for sucking air inside the molding die through the air vent hole. And a valve for opening and closing the air vent hole. According to the foam molding apparatus, a foaming material is injected into the molding die from the injection port, an air vent hole is opened by a valve, and the air inside the molding die is suctioned by using the pressure reducing device. The foaming raw material can be foam-hardened while the pressure inside the mold is reduced below the atmospheric pressure. The position of the air vent hole is not particularly limited, for example, in the case of a molding die composed of an upper die and a lower die,
It is preferable to provide it at a substantially central portion of the upper mold. As described above, the pressure inside the mold is 100 to 500 mmHg, and more preferably 400 to 450 mmHg. Air or water is preferable as a drive source of the decompression device. Since the foamed resin can be molded without opening and closing the molding die, molding workability is good. Since the foaming raw material can be injected from the injection port into the inside of the molding die, it is not necessary to perform injection while moving the injection head according to the injection pattern as in the related art, thereby improving workability.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 show an embodiment of a foam molding apparatus 1 according to the present invention. As shown in FIG. 1, the foam molding apparatus 1 includes a foam mold 4 including an upper mold 2 and a lower mold 3, an injection head 5 for injecting a urethane raw material liquid into the foam mold 4, FIG. 4 is a diagram showing an opening / closing lid 7 for opening and closing an injection port 6 formed in the upper mold 2, an air cylinder 8 for opening and closing an air vent hole of the upper mold 2, and reducing the pressure inside the foam molding die 4. An external pressure reducing device 9 is provided.

The foam molding die 4 is mounted on a mold carriage provided on a circuit conveyor line described later, and is used for foaming and hardening a urethane raw material liquid as a foamed raw material, and is used for an automobile seat or the like. To produce a urethane pad. Therefore, the urethane raw material liquid is supplied from a urethane raw material liquid supply source (not shown) to the injection head 5, and is injected from the injection head 5 into the foam molding die 4.

As shown in FIG. 2, the foam molding die 4 is composed of an upper die 2 and a lower die 3 arranged vertically, and the upper die 2 and the lower die 3 are vertically overlapped. Thus, a space (also referred to as a “cavity”) 10 for forming a product is provided therein. For this reason, the upper mold 2 and the lower mold 3 are provided with mating surfaces (also referred to as "seal surfaces") 2a and 3a, respectively, and these mating surfaces 2a and 3a are arranged facing each other. Has been established. As shown in FIG. 11, a large number of airbags 11 which are inflated by air pressure are arranged at the bottom of the lower mold 3, and when the doctor 12 is kicked, an air supply source (not shown) supplies the airbags 11 with these airbags. The lower mold 3 is lifted with air, and the lower mold 3 is lifted with the air. The lower mold 3 is combined with the upper mold 2, and the upper mold 2 and the lower mold 3 are clamped by a mold clamping clamp cylinder (not shown) in a sealed state. It is configured to:

On the other hand, an air vent hole 13 communicating with the cavity 10 in the molding die 4 is formed in the upper mold 2, and a mounting portion 14 having a substantially U-shaped cross section is formed so as to cover the air vent hole 13. Are arranged. The air vent hole 13 is formed in a tapered shape whose cross-sectional shape gradually increases in diameter from the upper surface to the lower side. Further, a side portion of the mounting portion 14 is connected to the pressure reducing device 9, and an air cylinder 8 is provided on an upper surface of the mounting portion 14.
The air cylinder 8 is configured to move the air release valve 15 in the vertical direction. Next, the air circuit shown in FIG. 3 will be described. This air circuit branches from a check valve 21 via an air regulator 20 to a valve opening / closing circuit 22 and a vacuum circuit 23 constituting the pressure reducing device 9. The pipe constituting the valve opening / closing circuit 22 extends upward from the branch point 24 in the drawing, passes through a valve opening / closing section 26 via a regulator 25, and further branches off from the valve opening / closing section 26 into two air release valves. 15 is connected to an air cylinder 8 that moves up and down.

The piping constituting the vacuum circuit 23 extends downward from FIG. 3 from the branch point 24 and passes through a vacuum operating valve 27 to a vacuum machine 28, from which a vacuum regulator 29 is further connected. As described above, it is connected to the mounting portion 14 of the upper mold 2 via the check valve 30. Further, the vacuum regulator 29 is configured so that the air suction strength, that is, the internal pressure of the molding die 3 can be adjusted.

Here, air is used as a power source for the vertical movement of the air release valve 15 and the operation of the pressure reducing device 9 for the following reason. Since the airbag 11 is used for clamping the upper and lower molding dies 4 and the air piping is provided on the molding cart, the air can be effectively used to provide an inexpensive and simple foam molding apparatus. be able to. As compared with the case where electricity is used as a power source, it is possible to provide the foam molding apparatus 1 which can be reduced in weight, has a good appearance, is stable in operation, and has few failures. Note that a decompression device 9 using water pressure instead of air pressure may be used.

As a production line for automobile seats using the foam molding apparatus 1 as described above, for example, FIG. 4 and FIG.
There is something like that shown in In the figure, a plurality of mold carts 41 are arranged at a certain interval on a circuit conveyor line 40, and these mold carts 4
1, a foaming mold 4 (see FIG. 1) is attached to each. In order to manufacture a urethane pad forming an automobile seat using the molding die 4, a urethane raw material liquid is injected into the molding die 4 at a position P in FIG.
2 and the molding die 4 is moved to the mold opening / closing device 4 at the Q position.
Close by 3. The molding cart 41 on the circuit conveyor line 40 is moving clockwise as shown by the arrow direction in FIG. 4, and is set so that the urethane raw material in the molding die 4 is foamed and hardened during the movement. . And
The upper mold 2 (see FIG. 1 or FIG. 2) of the molding die 4 is opened at the R position, and a foamed and cured urethane pad product is taken out. After taking out this product, the mold 4
The operation of applying the release agent to the inside of the mold by the application robot 44 and injecting the urethane raw material liquid into the molding die 4 at the P position is repeated.

Next, a method of manufacturing a urethane pad of an automobile seat using the molding die 4 of the present embodiment will be described. (1) Injection of foaming raw material (urethane raw material liquid) First, a predetermined amount of urethane raw material liquid 45 is injected into the molding die 4 by the injection head 5 shown in FIG. At this time, it is not necessary to open the upper mold 2 of the molding die 4 as in the related art, and the injection can be performed with the upper mold 2 closed, and the injection can be performed from the injection port 6 provided in the upper mold 2. . (2) Clamping of upper mold and lower mold Next, the doc 1 attached to the lower part of the lower mold 3 shown in FIG.
When the kick 2 is kicked, air enters the airbag 11 and the lower mold 3 rises, and the upper mold 2 and the lower mold 3 are completely sealed and locked by the mold opening / closing device 43 (see FIG. 4).

Then, air is sucked from the inside of the molding die 4 by using the pressure reducing device 9 shown in FIG.
The internal pressure is reduced below atmospheric pressure. That is, as shown in FIG. 3, the second air 51 flows from the branch point 24 to the vacuum machine 28 via the vacuum operation valve 27. On the other hand, when the vacuum operating valve 27 is turned on and the vacuum machine 28 is operated, the first air 50 is sucked from the inside of the molding die 4 into the mounting portion 14 through the air vent hole 13 and the check valve 30 and a vacuum machine 28 through a vacuum regulator 29.
Flow into In the vacuum machine 28, the molding die 4
The first air 50 from the air and the second air 51 from the vacuum actuating valve 27 merge into a third air 52, which is exhausted from the vacuum machine 28. Due to this discharge, the pressure inside the molding die 4 becomes atmospheric pressure 76
The pressure can be reduced below 0 mmHg.

(4) Bubbling of the urethane pad and stop of air suction Next, when a predetermined time (for example, 3 to 20 seconds) has elapsed after the injection of the urethane raw material liquid 45, the urethane raw material liquid 45 is stopped.
Expands and reaches the top of the upper mold 3. During this time,
The following two reactions occur in the urethane raw material liquid 45 in the molding die 4, and thereby a sponge-like urethane pad is generated. Polymerization reaction (urethane bond) Polyol + isocyanate → urethane polymer Foaming reaction Water + isocyanate → carbon dioxide + urea compound The air release valve 15 is supported on the back surface of the upper mold 2 so as to be able to move up and down. As a result, the air suction valve 15 is lifted to stop the air suction. Alternatively, when the foamed urethane pad raises the air release valve 15, the air release hole 13 is closed, and the suction of the first air 50 is stopped. (5) Unlock the upper and lower dies and open the air release valve. When the doc 12 is kicked, the air in the airbag 11 is released and the lower die 3 is lowered. The lock with the mold 3 is released.

(5) Removal of Product In this state, the upper die 2 is opened, and a urethane pad as a product is removed from the molding die 4. (6) Application of Release Agent Thereafter, in preparation for the next production process, a release agent obtained by dissolving wax in a solvent is applied to the upper die 2 and the lower die 3 of the molding die 4 by the release agent application robot 44. I do. Then, by drying and vaporizing the solvent, the inner surface of the molding die 4 is coated with a release agent. The present invention can be applied not only to automobile seats but also to a method for producing a urethane cushion for furniture such as a headrest, a chair or a bed, and a heat insulating material such as a refrigerator.

[0022]

[Embodiments] Next, a case where a urethane pad is molded by using the molding method according to the present invention (Example 1) and a case where it is molded by a conventional molding method (Comparative Example 1) will be described. . The first embodiment uses the molding die 4 shown in FIGS. 6 and 7 and the urethane raw material liquid 4 by a one-point injection method.
5 is a molding method in which the inside of the molding die 4 is depressurized and the urethane pad is foamed. Comparative Example 1 above
Is a conventional molding method in which the urethane raw material liquid 114 is injected into the lower mold 112 in a certain injection pattern using a conventional molding die 113, and urethane is foamed without depressurizing the inside of the molding die 113. It is molded by the method. Table 1 summarizes the molding conditions for both.

[0023]

[Table 1]

As can be seen from this table, the compressive strength of both the urethane pads formed according to Example 1 and Comparative Example 1 is almost the same. However, the density at the center (core) and the weight of the entire urethane pad are smaller in Example 1 than in Comparative Example 1, and the density difference is reduced in the entire urethane pad, thereby achieving a weight reduction of 5.6%. I was able to. In the first embodiment, it is desirable to close the opening / closing lid 7 of the injection port 6 immediately.

[0025]

According to the present invention, when molding a foamed resin, it is not necessary to teach a complicated injection pattern to an injection robot, and a defect such as burrs and underfills and a small amount of dust do not occur. Etc. can be formed. Further, by making the density of the urethane pad uniform, it is possible to reduce the weight of the urethane pad as a whole, and when it is used as an automobile seat, the riding comfort is improved. Furthermore, in producing the urethane pad, burrs are reduced, dust is not generated, the density is uniform, and riding comfort is improved. Further, deburring work is not required, and the number of times of opening and closing of the molding die is reduced, so that molding workability is improved.

[0026]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a foaming mold according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic view showing the entire foam molding apparatus according to the present invention.

FIG. 4 is a plan view showing the entire automobile seat manufacturing equipment employing the foam molding apparatus according to the present invention.

FIG. 5 is a front view of FIG. 4;

FIG. 6 is a perspective view showing a foaming mold used in Examples.

FIG. 7 is a perspective view showing the inside of the molding die of FIG. 6;

FIG. 8 is a perspective view showing an automobile seat.

FIG. 9 is a sectional view taken along line BB of FIG. 8;

FIG. 10 is a perspective view showing a state where a urethane raw material liquid is injected into a conventional molding die.

FIG. 11 is a side view showing the molding die of FIG. 10;

FIG. 12 is a front view showing the molding die of FIG. 10;

FIG. 13 is a plan view showing the molding die of FIG. 10;

FIG. 14 is a cross-sectional view showing a state where a urethane pad is being molded using a conventional molding die.

FIG. 15 is a cross-sectional view showing a density difference of a conventional seat cushion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foam molding device 2 Upper mold 3 Lower mold 4 Foam molding device 5 Injection head 6 Injection port 7 Opening / closing lid 8 Air cylinder 9 Decompression device 10 Void 11 Airbag 12 Doc 13 Air vent hole 14 Mounting part 15 Air vent valve 20 Air Regulator 21 Check valve 22 Valve opening / closing device 23 Vacuum circuit 24 Branch point 25 Regulator 26 Valve opening / closing part 27 Vacuum operating valve 28 Vacuum machine 29 Vacuum regulator 30 Check valve 40 Circuit conveyor 41 Mold cart 42 Injection robot 43 Mold opening / closing device 44 Coating robot 45 Urethane raw material liquid 50 First air 52 Second air 53 Third air

Claims (3)

[Claims] 1. A foaming raw material is injected into a mold from an injection port of a molding die, the mold is clamped, and then the foaming raw material is charged in a state where the inside of the molding die is maintained at a pressure lower than the atmospheric pressure. A foam molding method characterized by foaming and curing. 2. The pressure in the molding die is 100 to 500.
The foam molding method according to claim 1, wherein the pressure is set to mmHg. 3. A molding die having an injection port communicating therewith and an air vent hole, a decompression device for sucking air inside the molding die through the air vent hole, and the air vent hole. A foaming raw material is injected into the molding die from the injection port, the air vent hole is opened by the valve, and the air inside the molding die is sucked by using the pressure reducing device. A foam molding apparatus characterized in that the foaming material is foamed and hardened in a state where the pressure inside the mold is lower than the atmospheric pressure.