JP5374431B2 - Bumper reinforcement and hook bracket mounting structure - Google Patents

Description

  The present invention relates to a structure for mounting a bumper reinforcement and a hook bracket.

  Hooks attached to automobiles are mainly used for fixing (tie-down) when placed on a ship, and a large tensile load is applied obliquely downward. When aluminum alloy extruded material with a rectangular cross section is used as a bumper reinforcement to reduce the weight of the vehicle body, the hook bracket is fixed to the bumper reinforcement using the high rigidity of the rectangular cross section, and hooked by the bumper reinforcement. A method of supporting tensile load has been proposed.

  For example, in Patent Document 1, holes are formed in the front and rear walls of the bumper reinforcement, a shaft portion of a hook bracket having a flange at the rear end is passed through the holes from the rear side, and a front end portion of the shaft portion is formed in a hole in the front wall. And the flange is brought into contact with the rear wall of the rear wall of the bumper reinforcement, and a rivet is fastened to the rear wall. It is attached to the reinforcement. The flange protrudes from the shaft portion in the vertical direction of the vehicle body. In addition, in patent document 1, when a hook bracket consists of an aluminum alloy extrusion material, it attaches so that an extrusion direction may become the longitudinal direction of bumper reinforcement with respect to bumper reinforcement.

  Further, in Patent Document 2, holes are formed in the front and rear walls of the bumper reinforcement, and hook brackets having flanges near the front end of the shaft portion and right and left of the rear end are passed through the holes in the rear wall from the rear side of the bumper reinforcement. The front end of the shaft is protruded forward from the hole in the front wall, the collar near the front end is brought into contact with the back of the front wall, and the collar at the rear end is brought into contact with the back of the rear wall. The protruding front end is welded to the front wall, and the rear end is welded to the rear wall, thereby attaching the hook bracket to the bumper reinforcement. The collar protrudes from the shaft portion to the left and right in the longitudinal direction of the bumper reinforcement. In Patent Document 2, the hook bracket is made of an aluminum alloy extruded material, and is attached to the bumper reinforcement so that the extrusion direction is the vertical direction of the vehicle body.

Japanese Patent Laying-Open No. 2005-271859 (FIG. 2) JP 2006-36158 A (FIGS. 1 and 2)

  In both of the mounting structures disclosed in Patent Documents 1 and 2, the hook bracket shaft portion protruding forward of the front wall and the front wall front surface of the bumper reinforcement are directly fillet welded. For this reason, for example, when a large load is applied to the hook bracket due to tie-down, a large force is applied to separate the welded portion, and the vicinity of the welded portion of the front wall of the bumper reinforcement is deformed or the welded portion is The problem may arise that the tie-down load cannot be supported due to peeling. In addition, the fact that the weld line length cannot be increased in the welded part is also a cause of insufficient strength of the welded part and peeling when a heavy load is applied.

  The present invention has been made in view of such problems of the prior art, and has as its main object to prevent the deformation of the front wall of the bumper reinforcement and the separation of the welded part during tie-down.

The present invention is a bumper reinforcement having a hollow cross section made of an aluminum alloy extruded material, and made of an aluminum alloy extruded material, penetrating holes formed in the front wall and the rear wall of the bumper reinforcement, and welded to the front wall and the rear wall. In the hook bracket attachment part structure attached in the above, the hook bracket is formed such that the longitudinal direction of the bumper reinforcement is the extrusion direction, and a rib protruding upward is formed at or near the front end of the shaft part on which the internal thread is formed, A shaft portion of the hook bracket passes through a hole formed in the front wall and the rear wall from the front side, the rib is in contact with the front surface of the front wall, and a peripheral edge of the rib is welded to the front wall. It is characterized by.
In the present invention, “front” means the collision surface side, and “rear” means the vehicle body side.

In the mounting portion structure, it is desirable that the bumper reinforcement has a middle rib that connects the front wall and the rear wall, and the position of the middle rib overlaps with a welded portion on the periphery of the rib in the vehicle body height direction.
Moreover, it is desirable that a fillet be formed between the rib and the shaft portion on the front side of the rib of the hook bracket.
The hook bracket can be attached at any position in the vehicle width direction of the bumper reinforcement. For example, in the case where inclined portions bent toward the vehicle body are formed at both ends of the bumper reinforcement in the vehicle width direction, the hook bracket can be attached to the inclined portion in the vehicle longitudinal direction.

According to the present invention, by welding the peripheral edge of the rib formed on the shaft portion of the hook bracket to the front wall of the bumper reinforcement, the load generated in the vicinity of the welded portion of the front wall is reduced at the time of tie-down or the like. The deformation of the front wall and the peeling of the welded portion can be prevented.
In addition, when the position of the middle rib of the bumper reinforcement overlaps with the welded portion of the rib periphery of the hook bracket in the vehicle body height direction, the load applied to the hook bracket during tie-down etc. is efficiently applied to the middle rib and the rear wall. It is possible to reduce (disperse) the load that is transmitted and is generated in the vicinity of the welded portion, and further to prevent deformation of the front wall and peeling of the welded portion.

It is a top view of bumper reinforcement which attached the hook bracket concerning the present invention. It is the AA arrow sectional drawing. It is the top view (a), side view (b), and front view (c) of the hook bracket. They are a BB arrow line view (a) and CC arrow line view (b) of FIG. It is a figure which shows the welding form different from FIG. It is sectional drawing (a) which shows the welding form and load direction which were assumed by the FEM analysis of the Example, and side view (b), (c) of the welding part vicinity. It is sectional drawing of the hook bracket used as the object of FEM analysis in an Example.

Hereinafter, with reference to FIGS. 1-5, the attachment structure of the bumper reinforcement and hook bracket which concern on this invention is demonstrated.
In FIG. 1, a bumper reinforcement 1 is made of an aluminum alloy extruded material having a hollow cross section, a center portion is parallel to the vehicle width direction, both end portions are bent toward the vehicle body side, and are inclined with respect to the vehicle width direction (inclined portion). 1a, 1a). A hook bracket 2 also made of an aluminum alloy extruded material is fixed to one inclined portion 1a by welding.

  As shown in FIG. 2, the bumper reinforcement 1 has a cross-section of a front wall 3 that becomes a collision surface, a rear wall 4 on the vehicle body side, an upper rib 5 that connects the upper end of the front wall 3 and the upper end of the rear wall 4 substantially horizontally, The lower rib 6 connects the lower end of the front wall 3 and the lower end of the rear wall 4 substantially horizontally, and the middle rib 7 connects the substantially central portion of the front wall 3 and the substantially central portion of the rear wall 4 substantially horizontally. The front wall 3 is arranged substantially vertically, and is composed of an upper front wall 3a and a lower front wall 3b with the middle rib 7 as a boundary. The rear wall 4 is also arranged substantially vertically, and the upper rear wall 4a with the middle rib 7 as a boundary. And the lower rear wall 4b. A substantially quadrangular hole 8 is formed in the lower front wall 3 b, and a substantially quadrangular hole 9 is formed in the lower rear wall 4 b at a position behind the hole 8.

As shown in FIGS. 2 and 3, the hook bracket 2 includes a shaft portion 11 that is fitted into the holes 8 and 9 of the bumper reinforcement 1, and a rib 12 that protrudes upward in the vicinity of the front end of the shaft portion 11. . The back side of the rib 12 is formed substantially vertically, and the fillet 13 having a concave curve is formed between the rib 12 and the shaft portion 11 on the front side of the rib 12.
The hook bracket 2 is cut at a predetermined angle with respect to the extrusion direction. This inclination angle is equal to the inclination angle of the inclined portion 1a of the bumper reinforcement 1 with respect to the vehicle width direction. The rib 12 is formed in parallel with the extrusion direction. A through hole 14 is formed in the shaft portion 11 in the axial direction, and a female screw (not shown in detail) in which a male screw at the tip of the hook is screwed into the inner periphery of the through hole 14 is cut.

  The hook bracket 2 has the rib 12 facing upward, the shaft portion 11 is fully inserted into the holes 8 and 9 from the front side, the rear side of the rib 12 is substantially in contact with the central front wall 3a, and the rear end of the shaft portion 11 Is slightly protruding from the rear wall 4 of the bumper reinforcement 1. The shaft portion 11 of the hook bracket 2 is directed in the longitudinal direction of the vehicle body. On the other hand, the pushing direction of the hook bracket 2 is parallel to the inclined portion 1 a of the bumper reinforcement 1.

  The shaft portion 11 and the rib 12 of the hook bracket 2 are welded to the front wall 3 and the rear wall 4 of the bumper reinforcement 1. The shaft 11, the front wall 3 and the rear wall 4 are welded around the holes 8 and 9. As shown in FIGS. 2 and 4 (where dots are added), the welding locations are the peripheral edge (upper and left and right sides) of the rib 12 and the subsequent left and right sides of the shaft portion 11 with respect to the front wall 3 and the rear wall 4. Is the entire circumference of the shaft 11, the welding of the peripheral edge of the rib 12 and the front wall 3 is overlap fillet welding, and the other is T fillet welding.

Since the weld of the peripheral edge of the rib 12 and the front wall 3 is overlapped fillet welding, cracking due to an obliquely downward load at the time of tie-down or the like hardly occurs, and in particular, the tie-down is achieved by the rib 12 extending upward. The downward component of the load at the time is increased, and cracking of the lap fillet weld is less likely to occur. The fillet 14 between the rib 12 and the shaft portion 11 has an action of preventing a crack from being generated between the rib 12 and the shaft portion 11 due to a load during tie-down.
Further, in this example, the tip height of the rib 12 of the hook bracket 2 reaches the vicinity of the middle rib 7 of the bumper reinforcement 1, and the welded portion between the peripheral edge of the rib 12 and the front wall 3 is located at the position of the middle rib 7 and the vehicle body. Overlapping in the height direction. Thereby, the load applied to the hook bracket 2 at the time of tie-down or the like is efficiently transmitted to the middle rib 7 and the rear wall 4, and the load generated in the vicinity of the welded portion can be reduced (dispersed).

FIG. 5 shows another welding form of the bumper reinforcement 1 and the hook bracket 2 and is drawn according to FIG. In this example, the welded portion W is the periphery of the rib 12 (upper and left and right sides) and the lower side of the shaft portion 11 with respect to the front wall 3, and the entire periphery of the shaft portion 11 with respect to the rear wall 4.
In order to increase the welding length, it is desirable to weld the left and right sides of the front wall 3 and the shaft portion 11 as shown in FIG. 4, but if necessary, ribs 12 are attached to the front wall 3 as shown in FIG. There may also be a welding form in which only the periphery of each is welded. Further, the entire circumference of the rib 12 and the shaft portion 11 can be welded to the front wall 3 in order to increase the welding length.
Further, as for the welding of the rear wall 4 and the shaft portion 11, as shown in FIGS.

In order to examine the effect of the mounting structure of the present invention, the maximum stress generated in the welded portion of the front wall of the bumper reinforcement and the vicinity thereof was determined by using FEM analysis at the time of tie-down.
As analysis conditions, the plane and cross-sectional shape of the bumper reinforcement were the shapes shown in FIGS. 1 and 2, and a hook bracket was welded to one inclined portion of the bumper reinforcement. As schematically shown in FIG. 6, the welded portion W on the front wall 3 side of the bumper reinforcement 1 is the entire circumference excluding the lower side of the shaft portion 11 of the hook bracket 2 (including the peripheral edge of the rib if there is a rib). And the welding location W by the side of the rear wall 4 was made into the perimeter of the axial part 11 (When there exists a rib, the periphery of a rib is also included). As the bumper reinforcement 1, a 7000 series aluminum alloy extruded material having a yield strength of 310 MPa, a strength of 365 MPa, and an elongation of 14% was assumed. A load of 5.73 kN was applied to the front end of the hook bracket 2 downward 45 ° downward (arrow direction), and the maximum stress generated on the front wall 3 of the bumper reinforcement 1 was determined. A general-purpose finite element analysis code ABAQUS was used for the FEM analysis.

7 (a) to 7 (f) show various hook brackets and mounting portion structures that are analyzed. Here, the bumper reinforcement 1 is common to all cases, and the hook bracket 2 is also common to the shaft portion 11 in all cases.
The bracket 2 of the case 1 (FIG. 7A) is related to the present invention, and has a rib 12 protruding upward in the vicinity of the front end of the shaft portion 11, and the rib 12 is formed on the front surface of the front wall 3 of the bumper reinforcement 1. The upper end reaches the height of the middle rib 7.
The bracket 2 of the case 2 (FIG. 7B) is a comparative example, and has a rib 15 protruding upward at the rear end of the shaft portion 11, and the rib 15 is in contact with the back surface of the rear wall 4 of the bumper reinforcement 1. The upper end reaches the vicinity of the middle rib 7.
The bracket 2 of the case 3 (FIG. 7C) is a comparative example, and has ribs 15 and 16 protruding upward and downward at the rear end of the shaft portion 11, and the ribs 15 and 16 are the rear wall 4 of the bumper reinforcement 1. The upper end of the rib 15 reaches the vicinity of the middle rib 7.

The bracket 2 of the case 4 (FIG. 7 (d)) is a comparative example and includes only the shaft portion 11.
The bracket 2 of the case 5 (FIG. 7 (e)) is a comparative example, and has a pair of ribs 17 and 17 (only one is shown) protruding laterally (left and right) at a position near the front end of the shaft portion 11. The ribs 17 are in contact with the back surface of the front wall 3 of the bumper reinforcement 1. The ribs 17 are not welded to the front wall 3.
The bracket 2 of the case 6 (FIG. 7 (f)) is a comparative example, and ribs 18 and 19 projecting upward and downward to a position near the front end of the shaft portion 11, and projecting upward and downward to the rear end of the shaft portion 12. The ribs 15 and 16 are in contact with the back surface of the front wall 3, and the ribs 15 and 16 are in contact with the back surface of the rear wall 4 of the bumper reinforcement 1. The upper ends of the ribs 15 and 18 reach the vicinity of the middle rib 7. The ribs 18 and 19 are not welded to the front wall 3.

Results of the FEM analysis, the maximum stress generated in the welded portion and its vicinity of the front wall of the bumper reinforce, the case 1 is 190kN / mm ^2, the case 2 is 218kN / mm ^2, the case 3 is 215kN / mm ^2, case 4 230kN / mm ^2, case 5 230kN / mm ^2, the case 6 was 215kN / mm ^2. It is understood that the stress generated in the front wall 3 in the case 1 corresponding to the present invention is remarkably low, and the deformation of the front wall and the peeling of the welded portion can be effectively prevented as compared with the cases 2 to 6 which are comparative examples. Is done.

1 Bumper Reinforce 2 Hook Bracket 3 Front Wall 4 Rear Wall 7 Middle Rib 12 Shaft 13 Rib 14 Fillet

Claims (4)

A bumper reinforcement with a hollow cross section made of an aluminum alloy extruded material and an aluminum alloy extruded material, penetrated through holes formed in the front wall and the rear wall of the bumper reinforcement, and attached to the front wall and the rear wall by welding. In the hook bracket mounting portion structure, the hook bracket is formed such that the longitudinal direction of the bumper reinforcement is the extrusion direction, and a rib protruding upward is formed at or near the front end of the shaft portion on which the internal thread is formed. A shaft portion passes through a hole formed in the front wall and the rear wall from the front side, the rib is in contact with the front surface of the front wall, and a peripheral edge of the rib is welded to the front wall. Bumper reinforcement and hook bracket mounting structure. The said bumper reinforcement has a middle rib which connects the said front wall and a rear wall, The position of the said middle rib overlaps with the welding location of the said rib periphery in a vehicle body height direction, It was described in Claim 1 characterized by the above-mentioned. Bumper reinforcement and hook bracket mounting structure. The bumper reinforcement is formed with an inclined portion bent toward the vehicle body at both ends in the vehicle width direction, and the hook bracket is attached to the inclined portion so as to face the vehicle longitudinal direction. Bumper reinforcement and hook bracket mounting structure. The bumper reinforcement and hook bracket attachment structure according to any one of claims 1 to 3, wherein a fillet is formed between the rib and the shaft portion on the front side of the rib of the hook bracket. .

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