JP5380955B2 - Method for molding impact absorbing material and molding die - Google Patents

Description

The present invention relates to a method for molding an impact absorbing material and a molding die, and more particularly to a method for molding an impact absorbing material suitable for use as an impact absorbing material for automobiles, particularly a collision energy absorbing pad, and a molding die.

  As a shock absorber for automobiles, a large number of shock absorbers having uniform shock absorption characteristics throughout the shock absorber are manufactured.

  Japanese Patent Application Laid-Open No. 2002-193056 describes a vehicle shock absorber having partially different shock absorption characteristics. In the same issue, the inside of the mold is divided into two sections by a wall-shaped partition that stands up from the bottom of the mold, and foam raw materials having substantially the same foaming speed are supplied to each section for foam molding. Foams molded from the foam raw material supplied to each compartment have different shock absorption characteristics. Note that the wall-shaped partition portion does not reach the ceiling surface in the mold, and each foam is molded so as to be directly coupled at the upper portion in the mold. Thereby, the impact-absorbing material which is integrally molded as a whole and has two portions having different impact-absorbing characteristics is molded.

  In the shock absorbing material molded by this method, a deep groove derived from the partition portion exists between the two portions. Therefore, there is a possibility of cracking along the groove when the shock absorber is attached to the vehicle.

  Further, the foam of the one part and the foam of the other part are in contact with each other in the upper region of the partition part in the mold and are integrally connected, but the boundary surface where both contact is always above the partition part. Instead, it may be shifted to one section due to the difference in foaming speed between the two sections.

  For this reason, there is a demand for an impact absorbing material in which the position of the boundary surface between the two portions is constant and there is almost no groove between the two portions.

  If the partitioning portion is lowered, the groove becomes shallower and the strength in the vicinity of the connecting portion between one part and the other part increases, but the foamed foam materials in both sections are easily mixed during foam molding. As a result, the desired impact absorption characteristics may not be obtained, or cracking may occur easily.

  Furthermore, in the case of hard foamed resin, fine stress adjustment can be adjusted by the pack rate. However, in the case of molding by integral foaming, the ratio of the two types of pack rate needs to be constant, so the actual pack rate is It is impossible to adjust the stress.

[Another conventional example]
As a method of forming a part with different shock absorption characteristics in a part of the shock absorbing material, a method of reducing stress by scraping the back surface after creating the shock absorbing material, and a special form of non-foaming resin (polyethylene resin, etc.) Molded. However, these methods are laborious and costly. In addition, since the degree of freedom in design is reduced, free product development is hindered.

  In general, since the parts to which the shock absorbing material is attached are very crowded, it is desired that the shock absorbing material be small while having the ability to absorb the shock. In addition, the need for safety, which had been uniform until now, has been subdivided as a result of the increased need for safety against collisions. Absorbers are sought.

  Although foamed resin molded products by two-color molding are widely known, most of them are soft foamed resin molded products. In the case of a soft foamed resin, the boundary surface is not separated by the resin liquid entering (impregnating) the first foamed resin during the second molding. On the other hand, in the two-color molding of the hard foamed resin, the boundary surface is easily separated because the second resin liquid does not penetrate into the first foamed resin. By utilizing this property, it is possible to generate stress at a predetermined position in a rigid foamed resin molded product. Since a predetermined stress is required at a predetermined position, a difference in stress depending on the position is strictly required in an impact absorbing material using a hard foamed resin, particularly a collision energy absorbing pad. Therefore, positioning is very important when two-color molding is performed on a rigid foamed resin molded product.

  A method of locking one resin molded product with a protrusion or a pressing plate during two-color molding is well known as follows.

  In Japanese Utility Model Laid-Open No. 4-128812, one molded product is locked to the mold with a pin, but there is a disadvantage that the foamed resin molded product is locked to the mold in a deformed state. In the same reference, the projection of the pin is inserted into the through hole of the foamed resin.

  In Japanese Patent Laid-Open No. 5-24051, the foamed resin molded product is locked to the mold with a pin, but the height of the pin is the same as that of the foamed resin molded product to be attached, and the tip of the molded resin molded product is from this molded product. It protrudes.

  In Japanese Patent Laid-Open No. 5-185439, a foamed resin molded product (pad piece) is locked to a mold with a pin. This pad piece is intended for a liquid barrier.

Japanese Patent Application Laid-Open No. 9-248873 locks the fiber mat with pin-shaped protrusions, but there is no description about foaming molding of resin.
JP2002-193056 4-128812 JP-A 5-24051 JP-A-5-185439 JP 9-248873 A

An object of the present invention is to provide a method and a molding die for an impact absorbing material in which there are no grooves between portions having different physical properties and the boundary surfaces between the portions are constant.

Forming method of the shock absorber of claim 1 is a formed shape how the shock absorber made of rigid polyurethane foam, the shock absorber is for multiple portions different physical properties, which are integrated In the molding method, an insert molded product for constituting a part of the shock absorbing material is held on the inner surface of the mold, and the other part of the shock absorbing material is foam-molded in the mold. A locking portion for holding the insert molded product is provided on the inner surface of the mold, the locking portion is a pin-shaped protrusion, and the locking portion is used as the insert molded product. The insert molded product is held on the inner surface of the mold by being brought into contact with the outer surface of the mold .
According to a second aspect of the present invention, there is provided a method for forming a shock absorber according to the first aspect, wherein the locking portion is provided on a bottom surface in the mold.
According to a third aspect of the present invention, there is provided a method for forming a shock absorber according to the first or second aspect, wherein the shock absorber is an automobile shock absorber.
According to a fourth aspect of the present invention, there is provided a method for forming a shock absorber according to any one of the first to third aspects, wherein the physical property is a shock absorption characteristic.
According to a fifth aspect of the present invention, there is provided a method for forming a shock absorber according to the fourth aspect, wherein the physical property is hardness.

The mold for foam molding according to claim 6 is a mold used in the method for molding an impact absorbing material according to any one of claims 1 to 5 , and is disposed in the mold on the inner surface of the mold. The locking portion made of a pin-shaped protrusion is provided at a position where the outer surface of the insert molded product abuts .

Shock absorber which is molded by a molding method shock absorber of the present invention is one in which the impact absorbing ability can be satisfied even at the boundary portion.

Shock absorber which is molded by a molding method shock absorber of the present invention, Ri Contact stress (physical properties) of a different portion, it is not fragile even at the boundary portion, at multiple sites sought Shock absorption capability is guaranteed.

  In this invention, after manufacturing a small impact-absorbing material (insert molding product) once, it puts into a metal mold | die and manufactures the impact-absorbing material from which a different stress is obtained. Therefore, it is possible to manufacture a shock absorbing material having a plurality of intended shock absorbing characteristics in a single shock absorbing material without mixing the foam agent, and the degree of design freedom is increased.

Engaging portion made of projections for attaching the insert molding which is provided in the mold prevents the insert molding is moved during molding.

Although in practice it is possible the production of the shock absorber by even two-color molding without engaging portion made of projections, since it may move during gas generation and movement insert molded article engagement portion immovably It is necessary to hold in.

  Since the shock absorbing material provided by the present invention has no partition part, the shock absorbing material is free from chipping, the vulnerability to shock is suppressed, and the required ability can be exhibited.

  According to the present invention, since any shape member can be attached, the degree of freedom of design is increased, and there is a possibility that one shock absorber may be sufficient for a portion that conventionally required two or more shock absorbers to be attached. .

  Hereinafter, embodiments will be described with reference to the drawings.

The first figure denotes molding method automobiles for shock absorber Ru engaged in Reference Example, (a), (b) drawing a cross-sectional view of a mold, (c) Figure is a perspective view of a shock absorber It is.

  The mold 1 has an upper mold 2 and a lower mold 3, and a locking portion 4 is provided on the bottom surface of the inner surface (cavity surface) of the lower mold 3. The locking portion 4 has a cone shape with a sharp tip.

In order to mold the shock absorber 7, an insert molded product 5 made of hard polyurethane foam or the like previously molded by another mold is placed in the mold 1 and temporarily fixed so as to pierce the locking portion 4. . After supplying the foam molding stock solution R to the remaining space in the lower mold 3, the mold is closed and the stock solution R is foamed by heating or the like, and the insert molded product 5 has physical properties (in this reference example , shock absorption characteristics, concrete Are formed with portions 6 having different hardness. As the stock solution R, a mixed solution of a polyol and a polyisocyanate for forming a rigid polyurethane foam is suitable.

  The foamed shock absorbing material 7 is removed from the mold 1. The shock absorbing material 7 includes a portion derived from the insert molded product 5 and a portion 6 formed by foaming in the mold 1 and has two portions having different shock absorbing characteristics. There is no groove between the insert-molded product 5 of the shock absorber 7 and the foamed portion 6 in the mold 1. Therefore, the shock absorber 7 is not cracked along the groove when attached to the vehicle. Further, since the insert molded product 5 is molded in advance, the boundary surface between the insert molded product 5 and the portion 6 is the outer surface of the portion 6 of the insert molded product 5 and is constant. In addition, since the insert molded product 5 is temporarily fixed by the latching | locking part 4, the insert molded product 5 does not move in the middle of shaping | molding, and can shape | mold the impact-absorbing material 7 with the target characteristic with a sufficient yield. it can.

  In FIG. 1, the locking part 4 is provided on the bottom surface of the inner surface of the lower mold 3, but the locking part 4 may be provided on the side surface of the inner surface of the lower mold 3 as shown in FIG. Although not shown, the locking portions 4 may be provided on the side surface and the bottom surface of the lower die 3, and the locking portions may also be provided on the upper die 2. 2A is a longitudinal sectional view of the mold 1A in the middle of molding, and FIG. 2B is a sectional perspective view of the lower mold.

In the above reference example , the locking portion 4 has a conical shape and pierces the insert molded product 5. However, in the present invention, as shown in FIGS. Jo of Ru provided with a locking portion.

  3 and 4, a pin-shaped locking portion 8 is provided in the lower mold 3 so as to contact the outer surface of the insert molded product 5 and temporarily fix the insert molded product 5. In FIG. 3, the locking portion 8 is provided on the bottom surface of the lower die 3, and in FIG. 4, the locking portion 8 is provided on the side surface of the inner surface of the lower die 3. Although not shown, it may be provided on both the side surface and the bottom surface.

Figure 5 (a) is for showing a reference example Ru streak shape der the locking portion extends a predetermined length along the insert-molded article, the locking portion 9 is a bottom and the inner surface of the lower mold 3 It consists of L-shaped thin plate-shaped protrusions arranged at the corners intersecting with the side surfaces. The insert molded product 10 in FIG. 5 (a) is disposed at one corner of the lower mold 3, and the two locking portions 9, 9 are two orthogonal surfaces 10a, 10b of the insert molded product 10. It is installed so that it may contact. FIG. 5 (b) is a perspective view of the shock absorber 11 molded by the molding method using the mold shown in FIG. 5 (a). It is molded inside.

  In addition, the preferable number of arrangement | positioning and magnitude | size of said latching | locking part are as follows.

Locking portions made of conical protrusions: number 0.01 to ² pieces / cm ²
Height 1-5mm
Diameter of base surface φ1-5mm
Locking portions made of pyramidal projections: number 0.01 to 2 / cm ²
Height 1-5mm
One side of base surface 1-5mm
Pin-shaped locking part: number 0.01 to ² / cm ²
Diameter φ0.1-2mm
Length 1-10mm
Locking part made of wire-shaped protrusion: Height 1-5mm
Width 1-5mm

  The linear locking portion may be linear, curved, or dotted.

  The installation location of the locking portion may be the bottom surface or the side surface of the mold, but it is preferable that it is on the bottom surface in consideration of workability.

In the reference example , the locking portion may be a character-like protrusion provided in the cavity. In this case, the insert molded product is provided with a recess to which the character-shaped projection is engaged, and the projection and the recess are engaged to temporarily fix the insert molded product to the mold. In addition, it is preferable that the height of the protrusion is very low and does not affect the function of the shock absorbing material such as chipping.

In the above embodiment, the shock absorbing material is composed of two parts having different shock absorbing characteristics, but may be composed of three or more parts having different shock absorbing characteristics. FIGS. 6A and 6B show an example. As shown in FIG. 6 (a), the insert molded product 13 is temporarily fixed by a pin-shaped locking portion 8 near the center in the left-right direction of the lower mold 3 in the drawing. Supplying a space for foam molding stock R ₁ on the left side of the insert-molded product 13, after supplying the foam-forming stock solution R ₂ on the right side of the space, and closing the mold, foaming by heating or the like of the stock solution R _1, R ₂ Thus, the portions 15 and 16 having different physical properties (in this embodiment, shock absorption characteristics, specifically hardness) from the insert molded product 13 are formed.

  FIG. 6 (b) is a perspective view of the shock absorber 14 formed by the forming method using the mold shown in FIG. 6 (a). The hardness of the parts 15 and 16 molded in the mold may be the same or different.

  In FIG. 6, the shock absorbing material 14 is composed of three parts 13, 15, and 16, but may be composed of four or more parts.

(A), (b) is sectional drawing of the metal mold | die for the shaping | molding of the shock absorber which concerns on a reference example , (c) is a perspective view of the shape | molded shock absorber. It is sectional drawing of the metal mold | die which shows another reference example . It is sectional drawing of the metal mold | die which shows another reference example . It is a cross-sectional view of a mold showing the form of implementation. (A) is sectional drawing of the metal mold | die which shows another reference example , (b) is a perspective view of the shape | molded impact-absorbing material. (A) is sectional drawing of the metal mold | die which shows another embodiment, (b) is a perspective view of the shape | molded impact-absorbing material.

Explanation of symbols

1,1A Mold 2 Upper mold 3 Lower mold 4,8,9 Locking portion 5,10,13 Insert molded product 6,12,15,16 Parts molded in the mold 7,11,14 Shock absorber

Claims (6)

A formed shape how the shock absorber made of rigid polyurethane foam,
The shock absorber is formed by integrating a plurality of portions having different physical properties,
In the molding method, an insert molded product for constituting a part of the shock absorber is held on the inner surface of the mold, and the other part of the shock absorber is foam-molded in the mold. Is,
A locking portion for holding the insert molded product is provided on the inner surface of the mold,
The locking portion is a pin-shaped protrusion,
A method for molding an impact-absorbing material , wherein the insert molded product is held on the inner surface of the mold by bringing the engaging portion into contact with the outer surface of the insert molded product . The method for molding an impact absorbing material according to claim 1, wherein the locking portion is provided on a bottom surface in the mold. 3. The method for forming a shock absorber according to claim 1 , wherein the shock absorber is a shock absorber for automobiles. In any one of claims 1 to 3, the molding method of the shock absorber, wherein said physical property is a shock absorbing properties. 5. The method for molding an impact absorbing material according to claim 4 , wherein the physical property is hardness. In the metal mold | die used for the shaping | molding method of the shock absorber of any one of Claim 1 thru | or 5 ,
For foam molding, wherein the locking portion made of a pin-shaped protrusion is provided at a position of the inner surface of the mold that contacts the outer surface of the insert-molded product disposed in the mold. Mold.

Images