JPH0832508B2 - Bumper made of synthetic resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a synthetic resin bumper and a method for manufacturing the same, and more specifically, to improve efficiency by performing primary and secondary injections twice with a single injection machine. TECHNICAL FIELD The present invention relates to a synthetic resin bumper that can be easily manufactured, is easy to assemble, has a good shape, is lightweight, and is excellent in strength, cushioning property, and restoring property, and a manufacturing method thereof.

[Prior Art and Problems] Conventionally, a synthetic resin bumper has a fascia (outer member) such as coated surface polypropylene, and a foamed polyurethane or a synthetic resin honeycomb structure as a collision energy absorbing member arranged inside thereof. In addition, a box-shaped body made of metal or synthetic resin or a backup beam having a substantially U-shaped cross-section as a rigid body is arranged inside it, or a box-shaped body made of all FRP is usually used. there were.

However, since these conventional synthetic resin bumpers have a multi-layered structure, the structure is complicated, and the productivity is low and there is a problem in cost.

Specifically, a conventional synthetic resin bumper is, for example, shown in FIG. 7 (described in Japanese Utility Model Publication No. 63-951) or FIG.
3-19375).

Although it looks like a simple structure in Fig. 7, the manufacturing process is such that the outer member and the inner member are molded separately, and the joints 50 and 50 are vibration welded by stacking them, so the cycle time is long. In addition, since the product bumper has poor rigidity, it tends to hang down due to gravity G or a light collision, and when the collision energy is large, it tends to buckle without being supported, and there is also a problem in restoration.

On the other hand, the one in Fig. 8 does not hang down, but has a four-layer structure, has a complicated structure, has a large number of parts, takes a long cycle time due to parts matching and bolting, etc. If the box-shaped body 60 made of a thin steel plate or FRP is crushed by a slightly strong impact, it cannot be reused anymore, and therefore, there is a problem that it is poor in resilience.

Therefore, the present inventors have come up with the idea that one of the inventors has already proposed a mold slide method (Japanese Patent Laid-Open No. 62-87315) to manufacture a synthetic resin bumper, and as a result of earnest research improvements. The present invention has been completed.

[Object of the Invention] An object of the present invention is to have a light weight, a proper strength (absorption of collision energy, a buffering property and a restoring property), a high degree of freedom in design in terms of aesthetics and aerodynamic characteristics, and easy assembly. It is to provide a synthetic resin bumper that has a good shape and is excellent in mass productivity.

Another object of the present invention is to provide a synthetic resin bumper which is easy to assemble and which can prevent sticking and deformation of the upper portion of the outer member.

[Structure of the Invention] According to the present invention, in the synthetic resin bumper in which an outer member having a substantially U-shaped cross section and an inner member having a substantially U-shaped cross section that is opposite to the outer member are fixed, the inner member 3 is It has a cross-section supporting arm 3C extending from the rear end to the outer member 2 upper rear end vicinity 2D, and the supporting arm 3C rear end 3D, outer member upper rear end vicinity 2D, and inner member lower end tip flange portion 3B and outer. Near the lower end of the member A pair of parallel linear abutments or overlapping parts 5C, 5 which are almost horizontal when viewed from the front of the flange part 2B.
There is provided a synthetic resin bumper, characterized in that B is formed by secondary injection molding and joining with a synthetic resin having substantially the same composition as the outer member and the inner member, respectively.

 The present invention will be described in detail below with reference to examples.

[Embodiment] FIGS. 1 and 2 are sectional views of Embodiments 1 and 2 of the present invention, respectively (see FIG.
-I ', II-II' sectional view). Further, FIGS. 3 and 4 are cross-sectional views of essential parts showing another embodiment of the support arm tip joint part. FIG. 5 is a partially sectional front view of the embodiment, and FIG. 6 is a plan view of the same.

In FIGS. 1, 2, 3, 4, 5 and 6, 1 is a synthetic resin bumper common to the embodiments 1 and 2 of the present invention, 2 is an outer member (facia), and the main section is an inverted U-shape Are doing An inner member 3 has a U-shaped main cross section. However, the inside of the inner member 3 is reinforced by vertical ribs 6A and horizontal ribs 6B which are orthogonal to each other. A skirt portion 4 is formed integrally with the outer member. Reference numeral 8 is an air intake port to the engine room. The bumper 1 is fixed when the inner flange portions (fitting female portions) 2A, 2A of the outer member 2 and the flange portion 3A of the inner member 3 are fitted, and the flange portion 2B of the outer member 2 and the inner member 3 are fixed. Where the flange portion 3B is superposed, the inner member and the outer member are fused (bonded) with a molten synthetic resin having the same composition (hereinafter referred to as a molten resin). These are the joints 5A, 5
It is B. The joint part (fitting part) 5A is a horizontal rib 6 in the middle stage.
Both B and B may be joined to each other with a certain expansion and contraction allowance, or can be replaced with the joining portion (fusion portion) 5B.
However, when the joint portion 5B is used as the fitting portion 5A, it may be necessary to provide the joint portion 5B separately.

Further, 3C is a support arm that is formed at the same time as the inner member and extends from the rear portion to the vicinity of the rear end portion of the outer member upper portion.

The support arm 3C is fused (bonded) to the vicinity 2D of the rear end of the upper portion 2C of the outer member 2 with the resin having the same composition as that of the primary injection supplied by the secondary injection. It should be noted that this joint may be as shown in FIG. 3 or FIG.

Reference numeral 9 is an air gap that provides an initial cushioning effect when a collision load is applied to the bumper in the direction of the arrow. When the collision load exceeds a certain value, the ribs 6A and 6B are distorted to support the load. The inner member 3 has two stays 7 from behind.
Is strongly connected to and supported by the body or chassis. The characteristic of the bumper of the present invention is that the outer member and the inner member, which are each integrally molded in this way and have a slightly thicker thickness, overlap or contact with each other (a pair of linear joints extending horizontally when viewed from the front) 5B. , 5C are fused by the synthetic resins 5B, 5C having the same composition, and are forming a strong cushioning member as a whole. The bumper of the present invention has a structure in which the collision load is elastically supported by the ribs 6A, 6B (which may be a honeycomb structure) of the inner member, but is separated by the void 9 and the other ribs 6A, 6B, 13 If necessary, a synthetic resin foam such as expanded polystyrene or expanded polyurethane may be injected and foamed into the voids to form a part of the collision energy absorber for further reinforcement.

The rib 13 is the inner member 3 in the case of FIG. 1 and FIG.
Although it is formed at the same time when forming, the upper portion may be fixed to the upper surface 2A of the outer member 2. This also applies to the case of FIG. At that time, the ribs 13 may be simultaneously molded at the time of primary injection (injection for molding the inner member and the outer member), and the joint portions 5B, 5C.
It may be formed at the same time when is injected (secondary injection stage).

FIG. 3 and FIG. 4 are cross-sectional views of essential parts showing another embodiment of the end joint portion. In the case of FIG. 3, the cross section of the joint 5C has a Y-shape, and in the case of FIG. 4, it has a U-shape. For the convenience of design, the joint portion 5C can have other cross sections as well as FIGS. 1, 2, 3, and 4.

These examples of the present invention are manufactured by a so-called mold slide method. That is, a step of molding the outer member 2 and the inner member 3 by primary injection in a pair of opposing molds of a fixed mold and a movable mold, and a mold leaving the outer member 2 and the inner member 3 in their respective female molds. The steps of opening and the step of sliding the movable die to superpose or contact both members to clamp the die, and secondarily injecting a synthetic resin of the same composition between both members to join them together Accordingly, it is manufactured by means of additionally installing a reinforcing member.

Note that the secondary injection resin preferably has the same composition as the primary injection resin, but may not necessarily have the same composition as long as the fusion performance is sufficient, and resins having different compositions may be used.

[Advantages of the Invention] According to the present invention, the present invention is lightweight and has appropriate strength (impact energy absorption, cushioning and restoration), has a high degree of design freedom in terms of aesthetics and aerodynamic characteristics, and is easy to assemble and has a shape. A bumper made of synthetic resin that is excellent in mass productivity is provided. There is also an advantage that the gate can be set easily. The shape is improved because a slight shape error can be absorbed in the fitting portion 5A, and the stickiness and deformation of the upper portion of the outer member can be suppressed.

[Brief description of drawings]

1 and 2 are sectional views of Embodiments 1 and 2 of the present invention (I-
(I ', II-II' sectional view). Further, FIGS. 3 and 4 are cross-sectional views of essential parts showing another embodiment of the tip joint part. FIG. 5 is a partially sectional front view of the embodiment, and FIG. 6 is a plan view of the same. 7 and 8 are sectional views of a conventional example. 1 …… Synthetic resin bumper, 2 …… Outer member, 3 …… Inner member, 2A, 2B, 3A, 3B …… Flange part, 4 …… Skirt part, 5A, 5B, 5C …… Joint part, 3C… … Supporting arm.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-20183 (JP, A) JP-A-2-20184 (JP, A) Actually developed 62-153160 (JP, U)

Claims (1)

[Claims] 1. A synthetic resin bumper comprising an outer member having a substantially U-shaped cross section and an inner member having a substantially U-shaped cross section which is opposite to the outer member fixed to each other. Outer member 2 Upper rear area 2D
It has a cross-section supporting arm 3C extending to a rear end portion 3D of the supporting arm 3C, a rear end portion 2D near the outer member upper portion, an inner member lower end tip flange portion 3B and an outer member lower end portion flange portion 2B.
Is characterized in that a pair of substantially parallel abutting or overlapping portions 5C and 5B, which are substantially horizontal when viewed from the front, are formed by secondary injection molding and joining with a synthetic resin having substantially the same composition as the outer member and the inner member, respectively. Bumper made of synthetic resin.