JP3970606B2 - Foam mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foam mold used for making a foam molded article such as an automobile seat cushion.
[0002]
[Prior art]
Shock absorbing side impact pads and the like installed in automobile seat cushions and automobile doors are made by foaming by injecting a foaming material such as urethane foam into a foaming mold. Since foaming raw materials such as urethane foam are foamed and cured while generating gas, excess foaming gas that does not contribute to the foamed molded product must be discharged out of the mold. Here, if the vent hole is simply provided in the upper mold, not only unnecessary gas but also the raw material being foamed will leak from the vent hole during foam molding. Further, the burr of the foam that has leaked around the gas vent hole and solidified becomes a lump and firmly adheres to the upper mold, and the removal operation becomes troublesome.
For this reason, conventionally, for example, a method has been adopted in which a number of minute vent holes are formed in the upper mold and discharged out of the mold. In addition, a foaming mold has been used in which the upper mold is made into a split surface, or a hole of about 3 mmφ is formed in the upper mold, and this hole is covered with a breathable material.
[0003]
[Problems to be solved by the invention]
However, in the method of providing the minute holes described above, it is difficult to clean the urethane clogged in the holes. Foaming molds are injection of foaming raw material → mold closing → foaming molding → mold opening → product demolding → removal of burrs, cleaning process, etc. Usually, the process moves in line, and it is difficult to remove the urethane clogged in the holes of the moving foaming mold.
In addition, the use of the upper mold as a split surface complicates the mold, increases the mold cost, and further increases the parting line, resulting in poor moldability. Covering the above-mentioned holes with a breathable material also incurs additional material costs and requires the work of setting the breathable material.
The present applicant has also invented and proposed several foaming molds that have been devised for degassing (JP-A-7-68572, JP-A-11-19953, etc.). However, although all of them achieved a certain result, the initial cost was high due to the large scale and complicated structure.
[0004]
The present invention solves the above-mentioned problems, and provides a foam molding die that can be reliably degassed with a simple structure and can be extremely easily cleaned such as removing burrs after product demolding. The purpose is to do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the gist of the invention described in claim 1 is that a foam molding die having an upper die and a lower die is formed by penetrating from the inside of the die to the outside of the die. A plate-shaped shielding plate capable of securing a gap between the air hole and the upper mold surface and covering the air hole from the cavity side, and the shielding plate is connected to the upper mold via a hinge shaft. And when the shielding plate is held on the upper mold so as to cover the vent hole, the inside of the mold and the outside of the mold are electrically connected through the gap and the vent hole. It is in the characteristic foam mold.
[0006]
As in the first aspect of the invention, when the vent plate and the shielding plate are provided and the shielding plate secures a gap between the upper mold surface and covers the vent hole and is held by the upper die, In the foam molding stage, surplus foaming gas can escape from the mold through the gap and the vent hole, while the foaming raw material can be kept in the gap so as not to reach the vent hole. Since the foaming raw material does not enter the ventilation hole, the deburring work after product demolding becomes easy . When the shielding plate is suspended from the upper mold via the hinge shaft, the work of covering or opening the vent hole with the shielding plate becomes easier .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the foaming mold according to the present invention will be described in detail.
1 to 8 show one embodiment of a foam molding die according to the present invention. FIG. 1 is a cross-sectional view of a foam molding die in which a foaming raw material is injected in a mold open state, and FIG. FIG. 3 is an enlarged view of a portion A in FIG. 2 and FIG. 4 is an enlarged view corresponding to FIG. 3 in a state in which the shielding plate is removed from the vent hole after product demolding. FIG. 5 is an enlarged view of a portion A different from FIG. 3, FIGS. 6 and 7 are enlarged views of the portion A of another embodiment, and FIG. 8 is a perspective view around the shielding plate of another embodiment. FIG. 9 shows a cross-sectional view around another type of shielding plate.
[0008]
The foaming mold of the present invention is used to mold a foamed molded article 5 such as a seat cushion, and is composed of a split mold divided into a lower mold 2 and an upper mold 1 (FIG. 1). The upper die 1 is hinged at one side edge of the lower die 2 so that the upper die 1 can be rotated around the support shaft G, and the upper die 1 is closed to form a product-shaped cavity C (FIG. 2). . The mold surface 11 of the upper mold 1 is provided with a concave portion corresponding to the convex portion for the foam molded product 5 above the mold mating surface. The concave portion has a certain flat mold surface 11a, and a vent 12 is formed through the mold from the inside of the mold to the outside of the mold surface 11a of the concave portion. A plurality of vent holes 12 can be provided (see FIG. 5).
[0009]
The hole diameter α of the vent hole 12 is set in a range of, for example, 0.1 mmφ to 10 mmφ (FIG. 4). The vent hole 12 is a so-called vent hole that discharges excess foaming gas out of the mold in the foam molding step. However, according to the present invention, even if the hole diameter is as small as 0.1 mmφ as described later, In addition, there is no problem because the vent hole 12 is not clogged with urethane resin. Further, according to the present invention, since the raw material being foamed together with unnecessary gas does not leak through the vent hole 12 during foam molding, the vent hole 12 having a large hole diameter of about 10 mmφ can be obtained.
[0010]
A plate-shaped shielding plate 3 that can be covered from the cavity C side is attached to the vent hole 12. The shielding plate 3 is suspended from the upper mold 1 through a hinge shaft 41 so as to be rotatable. Further, the shielding plate 3 covers the vent hole 12 by the magnetic force of the magnet 6 and is held by the upper mold 1. Yes.
Here, the shielding plate 3 is a ferromagnetic metal plate (including an alloy plate) attracted by a magnet 6 such as iron, nickel, or cobalt having a certain degree of rigidity. The shielding plate 3 is a square steel plate having a thickness t in the range of 1.0 mm to 3.2 mm, for example. A hinge fitting is attached to one side of the shielding plate 3, and the shielding plate 3 is suspended from the mold surface 11 a via the hinge shaft 41. The shielding plate 3 does not move up and down and left and right by the hinge shaft 41, but can freely rotate. The pores 12 are set to come.
[0011]
The shielding plate 3 hits the mold surface 11a at the time of foam molding. The plate surface 31 facing the mold surface 11a is formed with a raised portion 32 that partially rises, and the shielding plate 3 is rotated. The shielding plate 3 and the mold surface 11a cannot be brought into close contact with each other even when they are brought into contact with the mold surface 11a of the upper mold 1. The number of the raised portions 32 is not particularly limited (see FIG. 8). When the shielding plate 3 is applied to the mold surface 11a of the upper mold 1, a gap is formed between the shielding plate 3 and the mold surface 11a of the upper mold 1 by the raised portion 32, and excess foam gas in the cavity C is formed during foam molding. A structure that allows escape from the mold. The width ε of the gap is preferably substantially constant over the entire area of the shielding plate 3. When the shielding plate 3 is largely inclined with the gap width ε different between the hinge side and the projecting end side away from the hinge mounting portion, the foaming raw material 5a together with the surplus foam gas from the greatly inclined gap side. This leaks out of the mold and interferes with the gas venting structure.
The specific value of the gap width ε is determined by the type such as the viscosity of the foam raw material 5a, the shape of the foam molded product 5, the foam molding conditions such as foam pressure, and the like.
[0012]
Further, when the shielding plate 3 is rotated and applied to the mold surface 11 a of the upper mold 1, the magnet 6 is disposed on the mold surface 11 a side of the upper mold 1 facing the shielding plate 3 at a portion near the protruding end 33 side of the shielding plate 3. Are buried (FIG. 3). In the present embodiment, the magnet 6 is also embedded at a location close to the vent hole 12. The shielding plate 3 that covers the vent hole 12 and is applied to the upper mold surface 11 a is held by the upper mold 1 by magnetic attraction of these magnets 6.
[0013]
The magnet 6 is a cube and may be of any shape, but its one end surface is made to substantially coincide with the mold surface 11 a of the upper mold 1. The material of the magnet 6 may be a natural magnet such as magnetite, a metal magnet such as chromium steel or high cobalt steel, and a ceramic magnet 6 such as alnico or rare earth magnet. Also, a plastic magnet or rubber magnet in which magnetic powder is dispersed in plastic, rubber, or the like may be used. A suitable magnet is preferably a magnet having a large force for magnetically attracting the ferromagnetic shielding plate 3, and specifically, a magnet having a large residual magnetic flux density, coercive force, maximum energy product, and the like. If a good material is selected from these magnetic properties, it is a rare earth material such as samarium cobalt or neodymium iron boron, and it can be obtained at a relatively low price recently. Of course, the present invention is sufficiently satisfied even with a ferrite magnet. The magnet 6 formed of a ferrite magnet satisfies the requirements of a small size and lower cost, and has an ability to hold the shielding plate 3 by suction.
[0014]
By the way, it is preferable that the shielding plate 3 has a minimum distance r of at least 10 mm from the ventilation hole 12 in a state of covering the ventilation hole 12 to the outer peripheral edge 38 of the shielding plate 3 (see FIG. 8). If it is smaller than 10 mm, it is necessary to strictly adjust the gap width ε, and the shielding plate 3 and the upper portion that are formed when the shielding plate 3 is rotated about the hinge shaft 41 and applied to the mold surface 11 a of the upper die 1. The gap width ε with the mold surface 11a is preferably in the range of 0.01 mm to 1 mm. When the gap width ε is smaller than 0.01 mm, it is difficult to remove excess foam gas from the mold during foam molding. On the other hand, if the gap width ε is larger than 1 mm, there is a problem that the shielding plate 3 must be made larger than necessary.
[0015]
With respect to the gap secured between the mold surface 11a of the upper mold 1 and the shielding plate 3, in the present embodiment, a raised portion 32 is formed on the shielding plate 3 side as shown in FIGS. However, the gap can be provided by management based on the surface roughness of the shielding plate 3 or the upper mold surface 11a without particularly forming the raised portion 32. The surface roughness indicating the roughness of the surface of the shielding plate 3 or the upper mold surface 11a includes types such as a centerline average roughness Ra and a maximum height Rmax. For example, the centerline average roughness Ra Thus, when the shielding plate 3 is held on the upper mold 1 so as to cover the vent hole 12, the inside of the mold and the outside of the mold are electrically connected through the gap and the vent hole 12.
Further, by adjusting the flatness of the mold surface 11a or the shielding plate 3, a predetermined gap is provided when the shielding plate 3 is held on the upper mold surface 11a by covering the vent hole 12 as shown in FIG. You can also. By managing and adjusting the deviation from the geometrical plane generated on the mold surface 11a and the shielding plate 3, a clearance width ε of about 0.01 mm to 1 mm is secured and the shielding plate 3 is placed on the upper mold surface 11a. Hold it. With respect to the mold surface 11a and the shielding plate 3, a desired gap can be easily set by managing the flatness which is the size of the opening from the geometric plane.
In FIG. 5, the shielding plate 3 is suspended from the upper mold 1 so as to be rotatable using a hinge 4 that is a known hinge. Since the attachment plate thickness of the hinge hinge 4 is thick, the recess 16 is formed in the upper mold 1 and the hinge fittings 4a and 4b are fixed thereto. A symbol M indicates a screw for attaching the hinge fittings 4 a and 4 b to the upper mold 1 or the shielding plate 3.
[0016]
Further, in the present embodiment, the raised portion 32 is formed on the shielding plate 3 side as described above, but it can also be formed on the mold surface 11a side of the upper mold 1 as shown in FIG. Of course, it may be formed on both the plate surface 31 of the shielding plate 3 and the mold surface 11 a of the upper mold 1. FIG. 6 shows another embodiment of the foaming mold in which the raised portion 13 is formed on the mold surface 11 a of the upper mold 1. The shielding plate 3 is rotated around the hinge shaft 41, and the shielding plate 3 covers the vent hole 12. A predetermined gap is secured when the magnet 1 is held by magnetic attraction. When the raised portion 13 is formed on the mold surface 11a of the upper mold 1, the raised portion 13 may be formed by bonding and bonding a separate product to the mold surface 11a. Of course, the raised portion 13 is covered with the shielding plate 3 as described above. When the surface roughness of the upper mold surface 11a around the vent hole 12 is made rough and substituted, and the shield plate 3 covers the vent hole 12 and is held by the upper mold 1, it is between the shield plate 3 and the mold surface 11a. A necessary gap may be formed.
[0017]
As for the hinge 4, as shown in FIG. 7, the base end 39 of the shielding plate 3 is wound around the hinge shaft 41, the hinge shaft 41 is attached to the hinge fitting, and the shielding plate 3 is suspended from the upper mold 1 so as to be rotatable. You may make it do.
Further, when the magnet 6 is embedded and fixed in the upper mold 1 as shown in FIG. 7 to form the raised portion 13 in the upper mold 1, the magnet 6 protrudes from the mold surface 11a by the gap width ε toward the cavity C side. The raised portion 61 may be formed by setting as described above. If the magnet 6 becomes the raised portion 13, the magnet 6 directly contacts the shielding plate 3 and attracts the magnetic force, so that the shielding plate 3 can be reliably held and is more preferable.
[0018]
FIG. 8 shows another embodiment of the foaming mold. When the shielding plate 3 is held by the upper mold 1, the projecting end portion 33 is slightly opened from the mold surface 11 a. After the foam molding is finished, the shield plate 3 is removed from the mold surface 11a after product demolding, and the burrs 7 attached to the back of the shield plate 3 and the upper mold surface 11a are removed. If it exists, the jig | tool 8, such as a spatula, can be inserted in the inclination part 331 of the protrusion part 33, and the removal operation | work of the shielding board 3 from the type | mold surface 11a can be advanced more smoothly.
[0019]
The foaming mold may have a structure for attaching the shielding plate 3 as shown in FIG. In the foaming mold of FIG. 9, the shielding plate 3 is not suspended from the upper die 1 via the hinge shaft 41, and the shielding plate 3 is detachably attached to the upper die 1. The shield plate 3 covers the vent hole 12 and is held by the upper die 1 by magnetic attraction of the magnet 6 embedded in the upper die 1. On the other hand, if the shield plate 3 is peeled off against the magnetic attraction, the upper die 1 is shielded. The entire plate 3 can be removed. However, as described above, it is more preferable that one side edge of the shielding plate 3 is attached to the upper mold 1 via the hinge shaft 41 because the shielding plate 3 can cover the vent hole 12 without causing positional displacement. . The shield plate 3 is hung on the upper die 1 via the hinge shaft 41 even if the shield plate 3 covering the vent hole 12 is removed during the deburring operation after the product is removed, or the attachment is performed again. The structure is more preferable.
[0020]
Next, the manufacturing method of the foam molded product 5 using the foam mold of FIGS. 1-4 is demonstrated including the motion of the shielding board 3, etc. FIG.
First, the mold surface is opened and the mold surface 11a is cleaned by air injection or the like, and the shield plate 3 suspended from the upper mold 1 is rotated around the hinge shaft 41, and the shield plate 3 is held by the upper mold 1 To be. The shielding plate 3 covers the vent hole 12 and is held on the upper mold 1 by magnetic attraction of the magnet 6. Then, a predetermined amount of foaming raw material 5a is injected into the cavity C (FIG. 1).
[0021]
Next, the mold is closed and foam molding is performed. In the foam molding process, the foam material 5a such as urethane foam material fills the cavity C while generating gas, and foams and cures, but excess foam gas (arrow in FIG. 3) passes through the gap and passes through the vent hole 12. Escape out of mold. A part of the foaming raw material 5a also tries to enter the vent hole 12 through the gap, but only fills the gap at the periphery of the shielding plate 3. This is because the resistance is too large for the foaming raw material 5a to pass through the gap as compared with the passage resistance when the foaming gas escapes out of the mold through the gap and the vent hole 12. The foaming raw material 5a having viscoelasticity larger than that of the foaming gas is slow to travel through a narrow gap between the shielding plate 3 and the mold surface 11a of the upper mold 1, and finishes the curing reaction before reaching the vent hole 12, Fill the gap. As the foam pressure in the mold rises, a part of the foamed raw material 5a enters the gap and goes to the vent hole 12, but the curing reaction of the foamed raw material 5a progresses with time and does not reach the vent hole 12 due to gelation. The movement is stopped. Thus, the necessary pressure in the mold is maintained by the self-sealing property of the foam raw material 5a, and the desired foamed molded product 5 is molded (FIG. 2).
[0022]
Thereafter, the mold is opened and the product is removed. Subsequently, the shielding plate 3 held by the upper mold 1 is opened (FIG. 4). If the protruding end 33 of the shielding plate 3 is slightly opened with a jig or the like, the shielding plate 3 is suspended from the upper mold 1 via the hinge shaft 41. When the shielding plate 3 is opened, a thin burr 7 adhering to the gap appears, but this burr 7 does not fill the inside of the vent hole 12 but simply sticks to the upper mold 1 and is easily removed by a scraper or the like. be able to.
Thereafter, the above procedure is repeated for manufacturing the next foam-molded article 5.
[0023]
The foaming mold configured in this way is held so that the shielding plate 3 covers the vent hole 12 provided in the upper die 1 and a gap is formed between the shielding plate 3 and the upper die surface 11a. The foaming gas can be easily escaped from the vent 12 through the gap to achieve reliable air venting. On the other hand, as described above, the foaming material 5a such as urethane foam hermetically seals the inside of the mold by its self-sealing property, and foam molding. The necessary pressure will be maintained. The degassing operation of the foaming gas can be smoothly performed without burdening the mold cost of the foaming mold with a simple structure.
In the foam molding process, the foaming raw material 5a foams and fills the cavity C, and a part of the foam material 5a tries to escape from the vent 12 through the gap. Before reaching the pores 12, the curing reaction is finished and the gap is filled. Therefore, after the foam molding is finished and the product is removed from the mold, the burr 7 accumulated in the gap by opening the shielding plate 3 can be easily removed. Deburring work is extremely easy unlike the conventional method. Since deburring work can be performed smoothly, it can also be used in continuous production lines. There is no running cost for secondary materials.
Further, when the shielding plate 3 is pivotably suspended from the upper mold 1 via the hinge shaft 41, the shielding plate 3 covers the vent hole 12 or shields the burrs 7 after removing the mold. The opening and closing work of opening the plate 3 is facilitated. Since the shielding plate 3 is suspended, it is not lost during the operation.
In addition, when the shielding plate 3 is suspended from the upper mold 1 via the hinge shaft 41 and the shielding plate 3 covers the vent hole 12 by the magnetic force of the magnet 6 and is held by the upper mold 1, the shielding plate 3 is shielded. The opening / closing operation of the plate 3 is further simplified. Unlike the locking means that hooks the shield plate 3 and stops it on the upper die 1, the shield plate 3 is held on the upper die 1 by magnetic attraction, so that it can be easily held only by rotating the shield plate 3 toward the upper die 1, Further, if the shield plate 3 is slightly separated against the magnetic attraction, the shielding plate 3 can be easily separated from the upper mold 1 and the workability is further improved.
[0024]
In addition, in this invention, it is not restricted to what is shown to the said embodiment, According to the objective and a use, it can change variously in the range of this invention. The shape, size, material, and the like of the upper mold 1, the vent hole 12, the lower mold 2, the shielding plate 3, the hinge, and the magnet 6 can be appropriately selected according to the application. For example, instead of the embodiment, the shielding plate 3 may be magnetized, and the magnet 6 provided in the upper mold 1 may be replaced with a ferromagnetic material.
[0025]
【The invention's effect】
As described above, the foaming mold of the present invention has a simple structure and can reliably perform degassing without causing leakage of the foaming raw material to the outside of the mold. Excellent effects such as easy removal and removal.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a foam molding die in which a foam raw material is injected in a mold open state in one form of a foam molding die of the present invention.
FIG. 2 is a cross-sectional view of the foam molding die in a state where the mold is closed from the state of FIG. 1 and foam molding is completed.
FIG. 3 is an enlarged view of a portion A in FIG.
FIG. 4 is an enlarged view corresponding to FIG. 3 in a state in which the shielding plate is removed from the vent hole after product release.
FIG. 5 is an enlarged view of a part A different from FIG. 3;
FIG. 6 is an enlarged view of part A of another embodiment.
FIG. 7 is an enlarged view of part A of another embodiment.
FIG. 8 is a perspective view around another shielding plate.
FIG. 9 is a cross-sectional view around a shielding plate of another form.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper mold | type 11a Mold surface 12 Ventilation hole 13 Raised part 2 Lower mold | type 3 Shielding board 32 Raised part 41 Hinge shaft 6 Magnet

Claims (1)

In a foam molding mold having an upper mold and a lower mold, a clearance is secured between a vent hole formed through the mold surface of the upper mold from inside the mold to the outside of the mold and the mold surface of the upper mold. A plate-shaped shielding plate capable of covering the vent hole from the cavity side, the shielding plate is suspended from the upper mold so as to be rotatable via a hinge shaft, and further covers the vent hole so as to cover the upper mold. Further, when the shielding plate is held, the foam molding die is configured such that the inside of the die and the outside of the die are electrically connected through the gap and the vent hole.

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