JP2016175185A - Molding die for foaming synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding die for foaming a synthetic resin having pressure-regulating means that keeps an internal pressure appropriate and certainly places a piston at a predetermined right position when producing a next product.SOLUTION: A molding die 10 for foaming a synthetic resin includes a vent 37 to discharge an inside foam gas during foaming an injected raw material of the synthetic resin, and pressure regulating means 11 connected to the vent 37. The pressure regulating means 11 has a cylinder 12 equipped with a piston 14. The cylinder 12 has holes (20 and 22) to inject and discharge a gas, in front of and behind a head 14a of the piston 14 respectively. The hole 20 is connected to the vent 37, while the hole 22 is connected to compressed air supply means 46.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a synthetic resin foam molding die, and more particularly to a pressure adjusting means and a synthetic resin foam molding die having a gas vent hole at least partially.

  When producing a synthetic resin foam molded product such as polyurethane foam, after injecting a synthetic resin foam material into a synthetic resin foam molding mold having a predetermined molding space (cavity) and foaming and curing in the molding space By removing the mold, a synthetic resin foam molded article having a predetermined shape is obtained.

  In order to reliably fill the synthetic resin foam material to every corner of the molding space with accurate internal pressure inside the synthetic resin foam molding die, an appropriate gas venting mechanism is provided in the synthetic resin foam molding die, It is necessary to discharge the foaming gas generated during foaming from the molding space and appropriately adjust the pressure (foaming pressure) in the molding space.

  Patent Document 1 discloses a mold for forming a synthetic resin foam having a foaming gas accommodating space 38 and a pressure control means 40. The synthetic resin foam molding die 26 is joined to the lower die 32 covering the open surface of the lower die 32 constituting the main part and the lower die 32, and a product-shaped formation space between the lower die 32. The upper mold 36 and the core mold 34 that form 28 are formed.

A gas vent hole 37 is formed in the upper die 36, and the foaming gas storage space 38 communicates with the molding space 28. When the internal pressure of the foaming gas storage space 28 exceeds a predetermined pressure, the volume is increased. Pressure adjusting means 40 is provided. In the pressure adjusting means 40, the piston 42 is urged toward the connection side with the molding space 28 by a spring 46 in the cylinder 44. When the foaming gas pressure in the foaming gas storage space 38 becomes equal to or higher than a predetermined pressure, the piston 42 slides against the urging force of the spring 46 to form a space for storing new foaming gas. In this way, the expansion of the volume of the foaming gas storage space and the appropriate internal pressure is prevented, thereby preventing the filling failure of the synthetic resin foam material in the molding space.

JP 2011-207082 A

  The pressure adjusting means of Patent Document 1 is configured such that a piston in a cylinder is moved and held at a predetermined position by a spring. Due to long-term use, foreign substances such as release agents and dust adhere to the piston drive shaft and spring, etc., causing the piston operation to become unsmooth. When manufacturing, the position of the piston may not return correctly to the predetermined position. If the position of the piston is not correctly returned to the predetermined position, the foaming gas cannot be removed sufficiently, and defects such as voids have occurred in the demolded synthetic resin foam molded product.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to always adjust the inside of the molding space to an appropriate internal pressure and make sure that the position of the piston is at a predetermined correct position when manufacturing the next product. An object of the present invention is to provide a synthetic resin foam molding die having pressure adjusting means for returning.

  In order to achieve the above object, a synthetic resin foam molding die according to claim 1 is provided with a gas vent hole through which the injected synthetic resin foam material discharges an internal foam gas during foaming, and the gas vent hole. And a pressure control means connected to the cylinder, wherein the pressure control means is a cylinder having a piston, and the cylinder is located in front of and behind the movement range of the head portion of the piston. A hole for injecting and discharging gas, and one of the holes is connected to the gas vent hole, and a pressurized air supply means is connected to the other of the holes. Features.

  With this configuration, while the synthetic resin foam material is being foam-cured, the piston of the pressure adjusting means is injected with foaming gas from one hole provided in the cylinder, and the piston moves to increase the volume in the cylinder, thereby increasing the molding space. The pressure inside is properly controlled. And after demolding a synthetic resin foaming molded product, air can be inject | poured with a pressurized air supply means from the other hole provided in the cylinder, and the position of a piston can be correctly returned to an initial position. Therefore, when producing the next synthetic resin foam molded product, the position of the fixie is always set to the initial correct position, so it is possible to sufficiently remove the foaming gas in the molding space. There is no generation of voids in resin foam moldings.

  A synthetic resin foam molding die according to a second aspect of the present invention is the synthetic resin foam molding die according to the first aspect, further comprising a cover that covers the drive shaft of the piston. Therefore, since the drive shaft of the piston is covered with a cover, it is possible to prevent foreign substances such as a release agent and dust from adhering to the drive shaft and mixing into the cylinder. It is possible to always operate reliably.

  The synthetic resin foam molding die according to claim 3 is the synthetic resin foam molding die according to claim 2, wherein the cover is transparent or translucent. Therefore, since the drive shaft can be easily confirmed, work efficiency can be improved while preventing foreign matters such as a release agent and dust from adhering to the drive shaft.

  According to the synthetic resin foam molding mold of the present invention, the pressure in the molding space is accurately adjusted by the pressure adjusting means composed of the piston and the cylinder, and the piston position is correctly set to the initial position after demolding. Can be returned. Therefore, the synthetic resin foam molded article does not generate voids, and the quality and yield of the synthetic resin foam molded article can be improved.

FIG. 2 shows a schematic overall configuration diagram (a) and a schematic cross-sectional portion (b) of a pressure adjusting means according to the synthetic resin foam molding die of the present invention. However, FIG. 1B shows a state where the foaming gas is injected into the cylinder. FIG. 3 is a schematic cross-sectional view showing a state in which the piston of the pressure adjusting means is returned to the initial position by the air supply means in the synthetic resin foam molding die of FIG. 1. The schematic sectional drawing at the time of covering the drive shaft of the piston which the pressure adjustment means has exposed in the synthetic resin foaming mold shown in the drawing is shown.

  Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic overall configuration view (a) and a schematic cross-sectional view (b) of a pressure adjusting means according to an embodiment of a synthetic resin foam molding die of the present invention. The pressure adjusting means 11 is connected to the vent hole 37 of the synthetic resin foam molding die 10. The gas vent hole 37 and the pressure adjusting means 11 are connected by a flexible tube 24 having a flexibility that can be freely curved.

  As the synthetic resin foam forming mold 10, a synthetic resin foam molding mold for a cushion pad of an automobile seat is shown as an example. The synthetic resin foam molding die 10 is joined to the lower die 32 so as to cover the lower die 32 and the open surface of the lower die 32, and a product-shaped formation space (cavity) 28 is formed between the lower die 32. An upper mold 36 and a core mold 34 are formed. The upper die 36 is provided with a gas vent hole 37 communicating with the cavity 28.

  The pressure adjusting means 11 is connected in communication with the gas vent hole 37, and is composed of a cylinder 12 and a piston 14. The piston 14 has a head portion 14a and a drive shaft 14b. The cylinder 12 has a cylindrical shape made of metal, and the inner diameter and length are determined depending on the volume of the molding space 28 of the synthetic resin foam molding die 10. The piston 14 reciprocates in the cylinder 12 with an appropriate frictional resistance with the inner wall of the cylinder 12. Stoppers 18-1 and 18-2 are formed for determining a reciprocable range, that is, a stroke length. Outside the range in which the piston 14 can reciprocate, holes (first hole 20 and second hole 22) for injecting and discharging gas are formed in the vicinity of the stoppers 18-1 and 18-2, respectively. .

  The foaming gas generated in the molding space 28 of the synthetic resin foam molding die 10 is injected from the first hole portion 20, and when the pressure reaches a predetermined pressure, the piston 14 moves and absorbs the foaming gas. In FIG. 1B, the inflow path of the foaming gas is indicated by an arrow A.

  When the piston 14 moves to the stopper 18-2, the piston 14 cannot move any further, so that the foaming gas cannot be absorbed. However, the foaming gas generated in the molding space 28 of the synthetic resin foam molding die 10 to be used here. Is determined in advance, the volume determined by the internal volume of the flexible tube 24 up to the pressure adjusting means 11 and the stroke length of the piston 14 of the pressure adjusting means 11 is determined according to the amount.

  FIG. 2 is a schematic cross-sectional view showing the state in which the cylinder 14 is returned to the initial position in the synthetic resin foam molding die 10 of FIG. The piston 14 reaches the stopper 18-2 after absorbing the foaming gas. Pressurized air is fed into the cylinder 12 from the second hole 22 provided in the stopper 18-2 by the pressurized air supply means 46, and the piston 14 is returned to the stopper 18-1. The flow of injected air is indicated by arrow B. Thereby, the pressure adjustment means 11 is set in the state which can absorb foaming gas. That is, since the piston 14 returns to the initial correct position after demolding, the internal pressure of the forming space 28 can be appropriately adjusted even in the production of the next product, and the synthetic resin foam molded product without voids. Can be obtained.

  FIG. 3 is a schematic cross-sectional view in the case where a cover 50 is provided in a portion where the drive shaft 14 b provided in the piston 14 is exposed from the cylinder 12. The cover 50 is made of a substantially cylindrical transparent plastic material, has substantially the same inner diameter as the cylinder 12, and is attached to the end of the cylinder 12 on the second hole 22 side.

  Since the cover 50 is made of a transparent plastic material, the position of the piston 14 can be visually recognized from the outside, and it can be seen at a glance that the foaming gas is normally absorbed and that the piston 14 is reliably returned to the initial position. It can be confirmed with. With this configuration, foreign matters such as a release agent, oil, and dust are prevented from adhering to the drive shaft 14b, and normal operation of the piston 14 is ensured. In the present embodiment, the cover 50 is made of a transparent plastic material so that the drive shaft 16 can be visually recognized from the outside, but may be made of a translucent material.

  According to the synthetic resin foam molding die 10 of the present embodiment, the pressure adjusting means 11 constituted by the cylinder 12 and the piston 14 appropriately absorbs the foaming gas. There are no defects such as voids. In addition, the cylinder 12 is provided with holes 20 and 22 for injecting and exhausting gas at the front and rear of the piston 14, respectively. Therefore, when the mold is removed and the next product is manufactured, the piston 14 is moved to the initial position. It can be set correctly. Moreover, since the transparent cover 50 which covers the drive shaft 14b of the piston 14 is provided, the movement of the piston 14 can be visually recognized from the outside. This prevents the release agent, oil, dust, and the like from adhering to the drive shaft 14b and the movement of the piston 14 from getting worse. Since the drive shaft 14b can be easily confirmed, it can be immediately confirmed that the piston 14 has returned to the initial correct position, work efficiency can be improved, and the yield of products can be improved.

  The present invention is not limited to the above embodiment. That is, various changes can be made without departing from the spirit of the invention. For example, the cylinder is a metal cylindrical shape, but is not limited thereto. You may comprise a transparent plastic material.

DESCRIPTION OF SYMBOLS 10 Mold for synthetic resin foam formation 11 Pressure adjusting means 12 Cylinder 14 Piston 14b Drive shaft 24 Flexible tube 28 Formation space (cavity)
46 Pressurized air supply means 50 Cover

Claims (3)

In the synthetic resin foam molding die having a vent hole for discharging the foamed gas inside the foamed synthetic resin foam material and pressure control means connected to the vent hole,
The pressure control means is a cylinder having a piston,
The cylinder has holes for injecting and discharging gas at the front and rear of the moving range of the head portion of the piston,
Either one of the holes is connected to the vent hole,
A synthetic resin foam molding die, wherein a pressurized air supply means is connected to the other of the holes.   The synthetic resin foam forming mold according to claim 1, further comprising a cover that covers the drive shaft of the piston.   The synthetic resin foam forming mold according to claim 2, wherein the cover is transparent or translucent.

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