JP5724429B2 - Bumper for vehicle and molding method thereof - Google Patents

Description

  The present invention relates to a synthetic resin vehicle bumper, and more particularly to a vehicle bumper in which a side molding is fitted and mounted from a bumper center to a bumper side, and a molding method thereof.

  As for the vehicle bumper, for example, as shown in Patent Document 1, a synthetic resin vehicle bumper in which a bumper center and a bumper side are integrally injection-molded is mainly used.

JP 2010-30491 A

  Among vehicle bumpers made of synthetic resin (hereinafter simply referred to as “resin bumpers”), those with side moldings to enhance the design effect, the molding groove is extended in the length direction from the bumper center to the bumper side. The side molding is fitted and attached to the molding fitting groove.

  A plurality of clips are integrally molded on the side molding, and a plurality of fastening holes are formed on the bottom of the molding fitting groove corresponding to the clips, and the clips are press-fitted into the fastening holes. By engaging, the side molding is firmly fixed in the molding fitting groove.

  In the injection molding of the resin bumper, a plurality of gates are concentrated on the portion corresponding to the bumper center having a large occupied area, and the mold is molded by filling the molten resin from the gate into the cavity with the required injection pressure. To increase the filling efficiency.

  The fastening hole of the molding fitting groove is formed at the groove bottom by a movable core or the like at the time of injection molding of such a resin bumper. In this case, weld lines are likely to occur when the molten resin wraps around the movable core, and this tendency increases especially at the bumper side far from the gate, making it difficult to reduce the thickness and weight of the resin bumper. It is supposed to be.

  Therefore, the present invention provides a vehicle bumper that can suppress the occurrence of a weld line due to injection molding and can be reduced in thickness and weight without impairing the appearance.

  In the vehicle bumper of the present invention, the bumper center and the bumper side are integrally formed by injection molding, a molding fitting groove is formed from the bumper center to the bumper side, and a side molding is formed in the molding fitting groove. And the side molding can be fixed by a clip through the fixing hole at the bottom of the groove.

And the thickness of the bumper center where multiple gates are concentrated during injection molding is set small, while the thickness of the bumper side is set large so as to have a different thickness distribution . The main feature is that the thickness of the lower region below the plate thickness is set to be smaller than the plate thickness to obtain a different plate thickness distribution .

The method for molding a vehicle bumper according to the present invention includes a molding fitting groove for fitting a side molding from the bumper center to the bumper side, and a clip bumping hole at the groove bottom. The bumper center where the multiple gates are concentrated during injection molding has a different thickness distribution than the bumper side thickness, and the upper side including the molding fitting groove It is characterized by forming with different plate thickness distributions in which the plate thickness of the lower region below it is made smaller than the plate thickness of the region .

  According to the vehicle bumper and the molding method thereof of the present invention, even if the bumper center is set to have a small plate thickness, the molten resin filled from a plurality of gates is molded into the fastening holes at the time of injection molding. Since the fluid flows around the part from multiple directions, the generation of weld lines is suppressed. On the other hand, since the thickness of the bumper side is larger than that of the bumper center, the fluidity of the molten resin from the bumper center side is improved, and the filling behavior around the molding part of the fastening hole becomes smooth, resulting in the generation of weld lines. It is suppressed.

In addition, since the plate thickness of the upper region including the molding fitting groove is different from the plate thickness of the lower region below it, the flow of the molten resin in the lower region is reduced. Even if it is late, the behavior of the molten resin around the molding portion of the fastening hole becomes smooth, and the occurrence of weld lines can be suppressed.
As a result, it is possible to achieve both the overall weight reduction of the bumper and the avoidance of the appearance deterioration due to the generation of the weld line.

The disassembled perspective view which shows the bumper for vehicles made into the object of this invention. The perspective view which shows 1st Embodiment of the bumper for vehicles which concerns on this invention. The side view of the bumper for vehicles shown in FIG. The side view which shows 2nd Embodiment of this invention. The perspective view which shows the stiffening structure of a bumper side. FIG. 6 is a perspective view showing different examples of the stiffener shown in FIG. 5 at (A) and (B).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings by taking a rear bumper as an example.

  A rear bumper 1 shown in FIG. 1 is injection-molded using a polyolefin resin filled with talc, for example, a polypropylene resin, and extends in the vehicle front-rear direction from a bumper center 2 extending in the vehicle width direction. Bumper side 3 is provided.

  Each lower edge of the bumper center 2 and the bumper side 3 is bent toward the vehicle center direction to extend under cover portions 2a and 3a. Further, a tunnel portion 2b straddling the exhaust tail is formed at the lower edge of both sides in the vehicle width direction of the bumper center 2 (see FIGS. 2 and 5).

  A molding fitting groove 4 is formed from the bumper center 2 to the vicinity of the end of the bumper side 3 at the center in the vertical direction of the rear bumper 1.

  By fitting the side molding 6 in the molding fitting groove 4, the design effect of the rear bumper 1 is enhanced.

  The side molding 6 is, for example, divided into three parts, a center part 6A and side parts 6B on both sides, and is injection-molded, and a plurality of clips 7 each projecting to the back side are integrally formed.

  On the other hand, a plurality of fastening holes 5 are formed at the groove bottom of the molding fitting groove 4 corresponding to the clips 7.

  Thus, the side molding 6 can be firmly fixed by fitting the side molding 6 into the molding fitting groove 4 and press-fitting and engaging the clip 7 into the fastening hole 5 at the groove bottom.

  The rear bumper 1 is integrally formed by injection molding as described above, and the fixing hole 5 at the bottom of the molding fitting groove 4 is formed by a die member such as a movable core or a pin.

  During injection molding of the rear bumper 1, since the area occupied by the bumper center 2 is large, a plurality of gates are concentrated on a portion corresponding to the bumper center 2 in order to increase the filling efficiency of the molten resin.

For example, in the example shown in FIGS. 2 and 3, a position G ₁ corresponding to a slightly upper portion of the molding fitting groove 4 in the vehicle width direction central portion of the bumper center 2 and the vehicle width direction center of the rear end of the under cover portion 2 a. and position G ₂ corresponding to the part, and to set the gate position G ₃ corresponding to the mall fitting groove 4 in continuously provided corner of the bumper center 2 and both sides of the bumper side 3.

In this embodiment, as shown in FIGS. 2 and 3, the bumper center in which a plurality of gates (corresponding to G ₁ , G ₂ , and G ₃ positions) is concentrated at the time of injection molding as described above. while smaller the second thickness _{T C,} is set larger the thickness _{T S} of the bumper side _{3 (T C <T S)} , there as different thickness distributions.

Thickness T _C of the bumper center 2, the fluidity of the molten resin during injection molding, and moldability is set as small as possible in consideration of the rigidity of the bumper center 2 after molding.

For example, at the time of injection molding, an arbitrary plate thickness T that allows injection molding with a filling pressure that does not exceed the mold clamping pressure of the molding die and that gives the bumper center 2 an appropriate rigidity without stickiness after molding. Set as _C.

On the other hand, the thickness T _S of the bumper side 3 is slightly thicker set than the plate thickness T _C of the bumper center 2. For example, at the time of injection molding, a smooth filling behavior of the molten resin filled from the gates G _{1 to} G ₃ on the bumper center 2 side can be obtained around the movable core that forms the fixing hole 5, and the curvature after molding is obtained. less bumper side 3 firm rigid no flapping is set as any plate thickness T _S obtained by the time the vibration travel of.

In the Ryabanpa 1 of this embodiment having the above structure, the bumper center 2 even each other is set smaller the thickness T _C, filled during injection molding of a plurality of gate G ₁ ~G ₃ Since the molten resin is caused to flow around the movable core forming the fixing hole 5 from multiple directions, the occurrence of weld lines is suppressed.

On the other hand, the bumper side 3, therefore the thickness T _S is large, the gate G ₁ ~G ₃ fluidity of the molten resin filled is improved from the filling behavior around the movable core to form the fastening holes 5 It becomes smooth and the occurrence of weld lines is suppressed.

As a result, the overall weight reduction of the rear bumper 1 and the weld line around the fastening hole 5 can be achieved by setting the plate thickness distribution T _C <T _{S at} the bumper center 2 having a large occupation area and the bumper side 3. It is possible to achieve compatibility with avoidance of deterioration of the appearance due to the occurrence of.

  FIG. 4 shows a second embodiment of the present invention. In the present embodiment, both the bumper center 2 and the bumper side 3 have plate thicknesses of the upper regions 2U and 3U including the molding fitting grooves 4 and the lower regions 2L and 3L below the upper regions 2U and 3U. The distribution is different.

In the bumper center 2, the plate thickness T _C1 of the lower region 2L is set smaller than the plate thickness T _C of the upper region 2U (T _C > T _C1 ). Further, in the bumper side 3, the plate thickness T _S1 of the lower region 3L is set smaller than the plate thickness T _S of the upper region 3U (T _S > T _S1 ).

Accordingly, different plate thickness distributions (T _S > T _C ≧ T _S1 > T _C1 ) are formed between the upper and lower regions of the bumper center 2 and the upper and lower regions of the bumper side 3.

Further, the bumper side 3, small plate thickness T _S1 of the lower region 3L, to account for the decreased charging efficiency of the molten resin during injection molding due to it, the front and rear of the under cover 3a end of the bumper side 3 It is to set the gate position G ₄ corresponding to the center in the direction.

According to the configuration of the second embodiment, since the plate thicknesses T _C1 and T _S1 of the lower regions 2L and 3L of the bumper center 2 and the bumper side 3 are set small, the flow of the molten resin at the time of injection molding Becomes slower than the upper regions 2U and 3U.

  In the bumper center 2, even if the flow of the molten resin in the lower region 2 </ b> L is slow, the periphery of the movable core that forms the fixing hole 5 enters the upper region 2 </ b> U. Performed smoothly. Thereby, since the association angle of the molten resin around the movable core is widened and the orientation of the talc of the filler is suppressed from becoming non-uniform, the occurrence of weld lines is suppressed. Even when a weld line is generated around the fixing hole 5, the molten resin tends to flow from the upper region 2U side to the lower region 2L side. It can be restricted to the lower region 2L.

On the other hand, in the bumper side 3, the flow of the molten resin from the upper region 2U including the molding fitting groove 4 of the bumper center 2 shown by the arrow A in FIG. faster than the flow from the gate G ₄ shown in the flow and the arrow C direction from the region 2L to 3L of molten resin toward upward. Thereby, the filling behavior of the molten resin around the movable core that forms the fixing hole 5 is smoothly performed, the association angle is widened, and the talc orientation of the filler is prevented from being non-uniform. For this reason, the generation of weld lines is also suppressed in the bumper side 3. Even when a weld line is generated around the fixing hole 5, the flow of the molten resin toward the end side of the bumper side 3 (left side in FIG. 4) is faster on the upper region 3U side than on the lower region 3L side. Generation of the weld line can be restricted to the lower region 3L below the molding fitting groove 4.

  As a result, even if a weld line occurs, it is restricted to the lower side of the side molding 6 where it is difficult to notice, and in addition to the thickness of the bumper center 2, the thickness of the bumper side 3 is reduced to the thickness of the lower half. It is possible to achieve both reduction in weight and ensuring appearance.

  FIG. 5 shows an example in which the bumper side 3 of the rear bumper 1 configured as described above is stiffened with a stiffener 10.

  The stiffener 10 is made of a polypropylene resin that is the same material as the rear bumper 1, and the stiffener 10 is vertically bonded and fixed to the back surface of the bumper side 3 with a polyolefin-based hot melt.

  FIG. 6A shows an example of the stiffener 10. In this example, the stiffener 10 is formed in a rectangular cylindrical shape, and slits are provided at predetermined intervals in the length direction over the adhesive surface 10a to the back surface of the bumper side 3 and three surfaces on both sides adjacent to the adhesive surface 10a. 10b is formed. Thereby, the shape followability with respect to the curved surface in the vertical direction of the bumper side 3 is imparted.

  FIG. 6B shows another example of the stiffener 10. In this example, a plurality of U-shaped cross sections in the length direction of the stiffener 10 are formed as a continuous structure whose open portions are alternately changed in phase by 180 °. In this way, by changing the phase of the open portion of the U-shaped cross section at 180 ° C., the mold can be punched, and a stiffener 10 having a plurality of rib walls 10c at required intervals in the length direction is obtained. be able to. Further, for the same purpose as in the first example, a slit 10b is provided in a U-shaped continuous portion to give shape followability to the curved surface in the vertical direction of the bumper side 3.

  Since the bumper side 3 is formed as a cross-sectional shape with a small curvature so as to be flush with the fender panel in modeling the vehicle body, the stiffener 10 is bonded vertically to the back side as shown in FIG. Thus, the surface rigidity of the bumper side 3 can be increased.

  Therefore, this stiffening structure is particularly effective when the plate thickness of the substantially lower half of the bumper side 3 is reduced as in the second embodiment shown in FIG.

  Then, as described above, the stiffener 10 is made of the same material as the rear bumper 1 and is bonded by using a homogeneous adhesive, whereby recycling can be performed advantageously.

  In the above embodiment, the rear bumper is exemplified, but it is needless to say that the present invention can be applied to a front bumper.

In the example shown in FIG. 4, the thickness distributions of the upper and lower regions 2U and 2L of the bumper center 2 are different as T _C and T _C1 , but this is limited to the bumper side 3 only. Also good.

1 ... Rya bumper (vehicle bumper)
2 ... bumper center 2U ... upper region 2L ... lower region 3 ... bumper side 3U ... upper region 3L ... lower region 4 ... Mall fitting groove 5 ... fastening hole 6 ... side molding T _C, the T C1 _... bumper Center Thickness T _S , T _S1 ... Bumper side thickness 10 ... Stiffener

Claims (2)

The bumper center and the bumper side are injection-molded integrally, a molding fitting groove is formed from the bumper center to the bumper side, and the molding is fitted to the molding fitting groove to secure the groove bottom. A vehicle bumper capable of fixing the side molding by a clip through a hole,
While setting the plate thickness of the bumper center where a plurality of gates are concentrated during injection molding, set the plate thickness of the bumper side to be a large plate thickness distribution ,
A vehicular bumper characterized in that a plate thickness in a lower region below the plate thickness in an upper region including the molding fitting groove is set to be different from each other to have a different plate thickness distribution . A method of injection-molding a vehicle bumper having a molding fitting groove for fitting a side molding from the bumper center to the bumper side and having a clip fastening hole at the groove bottom,
The thickness of the bumper center where a plurality of gates are concentrated during injection molding is different from the thickness of the bumper side, and a different thickness distribution .
A method for forming a bumper for a vehicle, characterized in that the forming is performed with different plate thickness distributions in which the thickness of the lower region below the thickness of the upper region including the molding fitting groove is made smaller .

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