JP2007030480A - Mold for foam molding and foam molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for foam molding which allows an excess gas in the mold to be vented during foam molding by a simple mechanism, and a method for foam molding using this mold for foam molding. <P>SOLUTION: A valve device 2 for venting is provided in an upper mold 1. The valve device 2 has a cylindrical housing 3, a valve body 4 installed in the housing 3, an advancing and retreating body 5 screwed to the back end side of the housing 3, and a spring 6 intervening between the valve body 4 and the advancing and retreating body 5 under a power storing condition. At the tip side of the housing 3, a valve seat part 3a overhanging in a brim shape in the centripetal direction is provided, and a central hole 3b is provided at the center of this valve seat part 3a. When the gas pressure in the mold becomes higher than a specified value, the valve body 4 is retreated to the back end side of the housing 3, and the valve is opened. When the gas pressure becomes lower than the spring pressure, the valve body 4 is pushed by the spring 6, it seats on the valve seat part 3a, and the valve is closed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a foam molding die for performing foam molding of polyurethane foam molded articles constituting automobile seats, interior materials, building materials, and the like, and a foam molding method using the foam molding die. .

  In order to produce a molded body such as a urethane foam molded article for automobile seats, an aluminum mold or a resin mold having a shape that can be opened and closed, which is normally required in advance, has physical properties required therein. For example, a polyurethane foam stock solution is injected and foamed to be molded.

  The injected polyurethane foam stock solution is foamed by the heat while passing through the heating tunnel or with reaction heat, and during this time, air in the mold or carbon dioxide gas or other blowing agent gas generated during the reaction is generated. appear. This gas is discharged from a vent hole for venting provided in the upper die or a parting portion of the upper die and the lower die.

  When a cushion body or the like is produced by this method, surplus urethane foam is discharged together with the gas from the vent hole for venting provided in the upper mold. This is called vent hole waste, but the generation of vent hole waste is a waste of raw materials, and it is very difficult for the line operator to completely remove the waste from the vent hole of the mold during operation. Requires a lot of effort or time.

Japanese Patent Application Laid-Open No. 9-57765 discloses that a pressure switch that is operated by a gas pressure applied to a vent hole is used, and that a gas discharge valve from the vent hole is controlled to open and close by this pressure switch. According to this mold for foam molding, when the gas pressure in the mold becomes higher than the predetermined pressure, the valve opens and excess gas is released outside the mold, and the resin is prevented from entering the vent hole. Is done.
JP-A-9-57765

  A mechanism comprising a pressure switch and a valve or the like controlled by the pressure switch as disclosed in Japanese Patent Laid-Open No. 9-57765 is expensive.

  An object of the present invention is to provide a foam molding die capable of discharging excess gas in a mold at the time of foam molding by a simple mechanism, and a foam molding method using the foam molding die. To do.

  The foam molding mold according to claim 1, wherein the foam molding mold includes a vent hole for discharging gas from the mold and a valve device for opening and closing the vent hole. The valve body is urged in the valve closing direction by a spring, and when the gas pressure in the mold exceeds a predetermined pressure, the valve body retreats and opens, and when the gas pressure becomes lower than the predetermined pressure, the valve body Is configured to be closed by a spring.

  According to a second aspect of the present invention, there is provided a foam molding die according to the first aspect, further comprising spring pressure adjusting means for adjusting a biasing force of the valve body by the spring.

  According to a third aspect of the present invention, there is provided a mold for foam molding according to the second aspect, wherein the spring pressure adjusting means is an advancing / retracting body capable of advancing / retreating in the direction of expansion / contraction of the spring.

  According to a fourth aspect of the present invention, there is provided a mold for foam molding according to any one of the first to third aspects, wherein the valve device is disposed in a cylindrical housing and movably in the axial direction of the cylinder in the housing. A valve body, a valve seat portion provided on one end side in the cylinder axis direction of the housing, on which the valve body can be seated, and a cylinder axis center on the other end side in the cylinder axis direction of the housing It is characterized by comprising an advancing / retracting body attached so as to be capable of adjusting the position in the linear direction, and the spring interposed between the advancing / retreating body and the valve body in a state of accumulating force.

  According to a fifth aspect of the present invention, there is provided a foam molding die according to the fourth aspect, wherein the advance / retreat body is attached to the other end side of the housing so as to be position-adjustable.

  According to a sixth aspect of the present invention, there is provided a foam molding die according to the fourth or fifth aspect, wherein the advance / retreat body is provided with a gas vent hole communicating with the inside and outside of the housing.

  The foam molding die according to claim 7 is the mold according to any one of claims 4 to 7, wherein the valve seat portion has an inward saddle shape having a central hole communicating the inside of the housing and the inside of the die at the center. The valve body is provided with a projecting shaft inserted into the central hole, and when the valve body is seated on the valve seat portion, the tip surface of the projecting shaft is the housing. It is characterized by being substantially flush with the end face on the one end side.

  The foam mold according to claim 8 is the mold according to claim 7, wherein the housing is provided on the mold such that an end surface of the one end side is substantially flush with an inner surface of the mold. It is a feature.

  A foam molding method according to a ninth aspect is characterized in that a foam molded article is molded using the foam molding die according to any one of the first to eighth aspects.

  In the foam molding die and the foam molding method of the present invention, when the gas pressure in the mold becomes higher than a predetermined pressure, the valve body is pushed back by this gas pressure to open, and the gas is opened. Is discharged out of the mold. When the gas pressure in the mold becomes lower than the predetermined pressure, the valve is closed, and a material such as resin is prevented from entering the vent hole.

  The valve device used in the present invention is simple in structure and low in cost.

  According to the second aspect of the present invention, by adjusting the urging force by the spring, the predetermined pressure serving as the reference value for opening and closing the valve body can be adjusted.

  As in the third aspect, the configuration using the advancing / retreating body as the means for adjusting the spring pressure is simple and low-cost.

  The configuration of the valve device of claim 4 is also simple and low cost. In this valve device, when the movement of the valve body becomes poor, the movement of the valve body can be recovered by pushing or pushing the valve body. In this case, the housing serves as a guide for the valve body.

  As in claim 5, when the advance / retreat body is screwed into the housing, the spring pressure can be easily adjusted by turning the advance / retreat body to advance / retreat.

  According to the sixth aspect of the present invention, the gas can be discharged out of the mold by providing a gas vent hole in the advance / retreat body.

  When the valve body is positioned at the forward limit where the valve body is seated on the valve seat portion, the surface of the molded product can be obtained by making the front end surface of the projecting shaft of the valve body substantially flush with the front end surface of the housing. It will be smooth.

  As described in claim 8, the surface of the molded product can be made smooth by making the front end surface of the housing substantially flush with the inner surface of the mold.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a cross-sectional view in the vicinity of a vent hole of a foam molding die according to an embodiment.

  In FIG. 1, the mold includes an upper mold 1 and a lower mold (not shown), and the upper mold 1 is provided with a valve device 2 for venting gas. The valve device 2 includes a cylindrical housing 3, a valve body 4 installed in the housing 3, an advancing / retracting body 5 screwed to the rear end side (upper end side in the figure) of the housing 3, A spring (coil spring in this embodiment) 6 interposed between the body 4 and the advancing / retracting body 5 in an accumulated state is provided.

  The housing 3 is fixedly attached to the valve device installation hole 7 penetrating the upper mold 1 by screwing or welding. A valve seat portion 3a is provided on the distal end side of the housing 3 so as to project in a bowl shape in the centripetal direction. A central hole 3b is provided in the center of the valve seat portion 3a. As shown, the front end surface of the housing 3 is substantially flush with the inner surface of the upper mold 1.

  The valve body 4 includes a disk-shaped main body 4a, a protruding shaft 4b protruding from the center of the lower surface of the main body 4a, and a shaft body 4c protruding from the center of the upper surface of the main body 4a. The protruding shaft 4b is inserted into the central hole 3b. The spring 6 is in contact with the upper surface of the main body 4a. The main body 4a may be disk-shaped or polygonal disk-shaped. Moreover, there is no restriction | limiting in particular in the cross-sectional shape of the protruding shaft 4b and the center hole 3a, and it can be set as various shapes, such as circular (including an oval shape) and polygonal shape.

  The advancing / retracting body 5 is provided with a gas vent hole 5a extending vertically.

  When the main body 4a is pressed against the valve seat portion 3a by the spring 6 (valve closed state), the lower surface of the main body 4a is in close contact with the valve seat portion 3a over the entire circumference. At this time, the front end surface (lower end surface) of the projecting shaft 4 b is flush with the front end surface (lower end surface) of the housing 3. There is a slight gap between the outer peripheral surface of the projecting shaft 4b and the inner peripheral surface of the central hole 3b. There is also a slight gap between the outer peripheral surface of the main body 4 a and the inner peripheral surface of the housing 3.

  In this valve device 2, the gas pressure in the mold acting on the valve body 4 via the central hole 3 b is larger than the urging force (spring pressure) applied to the valve body 4 from the spring 6. Then, this gas pressure causes the valve body 4 to retreat toward the rear end side of the housing 3 against the spring pressure. Thereby, the main body 4a of the valve body 4 is separated from the valve seat portion 3a, and the central hole 3b and the gas vent hole 5a communicate with each other through the housing 3. When this gas pressure becomes smaller than the spring pressure, the main body 4a is pushed by the spring 6 and is seated on the valve seat portion 3a, and the central hole 3b is closed.

  In this embodiment, when the advance / retract body 5 is turned, the advance / retreat body 5 advances / retreats in the axial direction of the housing 3, and the compression amount of the spring 6 by the advance / retreat body 5 and the valve body 4 changes. Thereby, it is possible to adjust the urging force applied from the spring 6 to the valve body 4.

  Next, the molding procedure of the foam molded product using the foam molding die provided with the valve device 2 having such a configuration will be described.

  Prior to foam molding, when the gas pressure in the mold becomes higher than a predetermined value, the spring 6 is attached so that the valve body 4 moves backward against the biasing force of the spring 6 by this gas pressure. Adjust the power.

  In performing foam molding, first, in a state in which the valve body 4 is closed, the inner surface of the upper mold 1 and the lower mold including the distal end surface of the projecting shaft 4 b of the valve body 4 and the distal end surface of the housing 3. A release agent is applied to the inner surface of the mold. Next, a stock solution such as urethane is poured into the lower mold, and after the upper mold 1 and the lower mold are clamped, the stock solution is foamed.

  During the foaming of the stock solution, the gas pressure in the mold rises due to the expansion of the stock solution and the generation of gas from the foaming agent and the like contained in the stock solution. When the gas pressure becomes higher than a predetermined value, the valve body 4 is retracted and opened by the gas pressure, and the gas is discharged out of the mold through the central hole 3a and the gas vent hole 5a. Thereafter, when the gas pressure in the mold becomes lower than the predetermined value, the valve body 4 is pushed by the spring 6 and is seated on the valve seat portion 3a to be closed. This prevents foamed resin or the like from entering the central hole 3a.

  After the foamed resin is cured, the mold is opened and the foam molded product is taken out.

  In this foam molding die, the valve device 2 has a simple structure and is low in cost.

  In this embodiment, by turning the advance / retreat body 5 to advance / retreat the advance / retreat body 5 in the axial direction of the housing 3, the gas pressure in the mold that becomes the reference value for opening / closing the valve body 4 can be easily adjusted. A predetermined value can be set.

  In this embodiment, since the housing 3 serves as a guide for the advancement / retraction of the valve body 4, the advancement / retraction of the valve body 4 is smooth. When the movement of the valve body 4 is deteriorated, the movement of the valve body 4 can be recovered by pushing or pushing the valve body 4 with a rod or the like through the central hole 3b or the gas vent hole 5a. it can.

  In this embodiment, when the valve body 4 is in a closed state, the distal end surface of the projecting shaft 4b of the valve body 4, the distal end surface of the housing 3, and the inner surface of the upper mold 1 are flush with each other. Therefore, the surface of the molded product becomes smooth.

  FIG. 2 is a cross-sectional view of a vent hole portion of a foam molding die according to another embodiment.

  The valve device 2 ′ of this embodiment is also screwed to the cylindrical housing 3, the valve body 4 ′ installed in the housing 3, and the rear end side (upper end side in the figure) of the housing 3. It has an advancing / retracting body 5 and a spring 6 interposed between the valve body 4 ′ and the advancing / retreating body 5 in an accumulated state. Further, an inwardly saddle-like valve seat portion 3a ′ on which the main body 4a of the valve body 4 ′ is seated is provided at the front end side of the housing 3, and a central hole 3b is provided at the center of the valve seat portion 3a ′. It has been. A protruding shaft 4b protruding from the center of the lower surface of the main body 4a is inserted into the central hole 3b.

  In this embodiment, the valve seat portion 3 a ′ has a tapered shape that gradually narrows from the rear end side of the housing 3 toward the front end side (downward in the drawing). Further, the distal end side of the main body 4a of the valve body 4 ′ seated on the valve seat portion 3a ′ (the step surface between the side peripheral surface of the main body 4a and the side peripheral surface of the protruding shaft 4b) is also formed on the valve seat portion 3a ′. It has a taper shape (substantially truncated cone shape) having the same taper angle.

  The other configuration of the valve device 2 'is the same as that of the valve device 2 shown in FIG. 1, and the same reference numerals denote the same parts.

  In this valve device 2 ′, the valve seat portion 3a ′ and the distal end side of the main body 4a of the valve body 4 ′ are tapered so that the main body 4a is seated on the valve seat portion 3a ′. Adhesiveness between the main body 4a and the valve seat portion 3a ′ is improved.

  Each of the above embodiments shows an example of the present invention, and the present invention is not limited to each of the above embodiments.

  For example, in the above embodiment, the advancement / retraction body 5 is attached to the rear end side of the housing 3 by screwing, and the advancement / retraction body 5 is rotated to advance / retreat in the axial direction of the housing 3. Although the configuration is such that the urging force can be adjusted, the configuration of the urging force adjusting mechanism of the spring 6 is not limited to this. Further, the mechanism for adjusting the biasing force of the spring 6 may be omitted. In this case, for example, after the spring 6 having a predetermined spring constant is arranged in the housing 3, a non-moving body may be fixed to the rear end side of the housing 3 by press fitting or the like to hold the spring 6. .

  In the above embodiment, the front end surface of the projecting shaft 4 b is flush with the front end surface of the housing 3, but the front end surface of the projecting shaft 4 b may protrude from the front end surface of the housing 3. It may be recessed from the front end surface to the outside of the mold. The front end surface of the housing 3 may also protrude from the inner surface of the mold, or may be recessed from the inner surface of the mold to the outer side of the mold.

It is sectional drawing of the vent hole vicinity of the metal mold | die for foam molding which concerns on embodiment. It is sectional drawing of the vent hole vicinity of the metal mold | die for foam molding which concerns on another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper mold | type 2,2 'Valve apparatus 3 Housing 3a, 3a' Valve seat part 3b Center hole 4,4 'Valve body 4a Main body 4b Projection shaft 5 Advancement / retraction body 5a Gas vent hole 6 Spring

Claims (9)

In a foam mold having a vent hole for discharging gas from the mold and a valve device for opening and closing the vent hole,
The valve device urges the valve body in a valve closing direction with a spring, and when the gas pressure in the mold becomes equal to or higher than a predetermined pressure, the valve body retreats and opens, and the gas pressure is higher than the predetermined pressure. A foam molding die characterized in that the valve body is closed by a spring when it is lowered.   2. The foam molding die according to claim 1, further comprising spring pressure adjusting means for adjusting a biasing force of the valve body by the spring.   3. The foam molding die according to claim 2, wherein the spring pressure adjusting means is an advancing / retracting body capable of advancing / retreating in the expansion / contraction direction of the spring. The valve device according to any one of claims 1 to 3,
A tubular housing;
A valve body arranged in the housing so as to be movable in the axial direction of the cylinder axis;
A valve seat portion provided on one end side of the housing in the cylinder axis direction, on which the valve body can be seated;
An advancing and retracting body attached to the other end side of the housing in the cylinder axis direction so that the position in the cylinder axis direction can be adjusted;
A foam molding die, comprising the spring interposed between the advancement / retraction body and the valve body in an accumulated state.   5. The mold for foam molding according to claim 4, wherein the advancing / retracting body is attached to the other end side of the housing by screwing so that the position thereof can be adjusted.   6. The mold for foam molding according to claim 4, wherein the advance / retreat body is provided with a gas vent hole communicating with the inside and outside of the housing. In any one of Claims 4 thru | or 7, the said valve seat part is an inward saddle shape which has the center hole which connects the inside of a housing and the inside of a metal mold | die in the center,
The valve body is provided with a protruding shaft inserted into the central hole,
A foam molding die, wherein the tip end surface of the projecting shaft is substantially flush with the end surface on the one end side of the housing when the valve body is seated on the valve seat portion.   8. The foam molding die according to claim 7, wherein the housing is provided on the mold such that an end surface on the one end side thereof is substantially flush with an inner surface of the mold.   A foam molding method comprising molding a foam molded article using the foam molding die according to any one of claims 1 to 8.

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