The present invention relates to a weld joint obtained by joining one end of a wrought material formed of one of aluminum and an aluminum alloy to an end part of an aluminum alloy cast member.
Weld structures formed by joining an aluminum alloy wrought material to an aluminum alloy cast member have been used in actual practice. The technique disclosed in Patent Literature 1 is a conventional technique relating to such a weld structure.
The weld structure described in Patent Literature 1 is a subframe. The subframe is manufactured by welding a lid body to a frame body. The frame body is an aluminum alloy cast member, and the lid body is an aluminum alloy wrought material.
The lid body is welded to the frame body along the entire circumference. Because so-called full circumference welding is performed, the welding length is considerably increased and the welding cost is raised. In addition, the welding strain is increased, and the correction cost for correcting the strain is also increased. Manufacturing expenses for the weld structure described in Patent Literature 1 are therefore increased.
A conventional structure whose manufacturing expenses can be made lower than those in Patent Literature 1 is described based on
As one way to reduce the weight of a vehicle, the cast members 101, 102 are made to be aluminum alloy cast members, and aluminum or aluminum alloy wrought materials are used for the wrought materials 103, 104.
Gaps 106, 106 must be provided to an inserting portion in order to smoothly insert the wrought material 103 in the cast member 101.
The cast member 101 is a casting, and therefore inevitably contains gas. In addition, the melting point of the aluminum alloy casting is lower than the melting point of the aluminum alloy wrought material.
When lap-fillet MIG welding is performed under such conditions, the molten metal runs (leaks) from the gaps 106, 106. In addition, the wrought material 103 is more difficult to melt than the cast member 101.
Ensuring a throat 108 in a bead 107 becomes difficult when these main factors overlap. Defects such as insufficient strength and degraded quality of the weld part 105 occur when the throat 108 is insufficient.
Patent Literature
Patent Literature 1: JP-A 2004-210013
An object of the present invention is to provide a technique capable of preventing insufficient strength and degraded quality of a weld joint obtained by joining one end of an aluminum or aluminum alloy wrought material to an end part of an aluminum alloy cast member.
According to the present invention, there is provided a weld joint of an aluminum alloy member obtained by joining an end part of a wrought material formed of one of aluminum or an aluminum alloy to one end of a cast member formed of an aluminum alloy, wherein the cast member has a chamfer extending from an upper surface of the cast member toward a lower surface until a midway of a thickness of the cast member, and an inserting portion extending along a lower surface of the wrought material from a lower end of the chamfer toward a distal end of the cast member, a distance from the lower end of the chamfer to an end face at one end part of the wrought material is set at 1.0 to 1.7 times a thickness of the wrought material, the chamfer is inclined so that a groove angle with the end face at one end of the wrought material is 15 to 45°, and the groove is welded to cause the inserting portion to act as a backing metal.
In the present invention, there is no concern that molten metal will leak out because an inserting portion assumes the role of a backing metal. The high-melting wrought material can be fully melted because molten metal accumulates in the groove. As a result, strength can be increased and a high-quality weld joint can be obtained.
Embodiments of the present invention will be described below with reference to the attached drawings.
An embodiment of the present invention will be described with reference to the drawings.
A pre-weld structure 10 is formed of an aluminum alloy cast member 11 and an aluminum or aluminum alloy wrought material 12, as shown in
A pre-weld groove shape is described in
An end part of the cast member 11 is cut on an incline in the thickness direction to a height H from an upper surface 11a toward a lower surface 11b, as shown in
The slope 14 is inclined so that a groove angle θ is 15 to 45° in relation to an end face 12a of the wrought material 12.
The wrought material 12 is separated from the slope 14 so that a root space L is obtained in which the bottom of the groove is 1.0 to 1.7 times the thickness T of the wrought material 12.
The height H of the slope 14 is somewhat greater than the thickness T of the wrought material 12, as shown in
When MIG welding is performed on the groove in this form, there is no concern that molten metal will leak out because the inserting portion 13 assumes the role of a backing metal. The high-melting wrought material can be fully melted because molten metal accumulates in the groove. As a result, a bead 15 such as the one shown in
The evaluation of the bead 15 was confirmed by an experiment.
An experimental example according to the present invention will be described below. The present invention is not limited to the experimental example.
Sample material:
Groove form:
Welding conditions:
Verification of groove angle:
Welding was performed under the above conditions, and the joint efficiency of the resulting joint was calculated. The results are shown in
The best results were produced at θ=30°, as shown in
Verification of the outer-face difference (H−T):
The relationship between the thickness T of the wrought material 12 shown in
The horizontal axis in
Verification of the root space L:
Welding was performed under the above conditions, and the joint efficiency of the resulting joint was calculated. The results are shown in
The solid line in
Assuming that the required joint efficiency is 70%, the joint efficiency in the case of the solid line will exceed 70% if the root space is 1.0 (the wrought material thickness was set to 1.0) or greater.
An opening of 0.5 to 1.0 mm is preferred to facilitate insertion of the cast member 11 in the wrought material 12 in
When the opening is 1.0 mm, the joint efficiency declines and falls below 70% at the horizontal axis point of 1.7, as shown by the dashed line.
A root space having points “a” to “b” shown in
An example in which the weld joint of the present invention is used in the subframe of a vehicle is described in
The subframe 20 as a structure is formed of a front cross part 21 and a rear cross part 22 extending in the crosswise direction of the vehicle, front arm parts 23, 24 extending from both ends of the front cross part 21, rear arm parts 25, 26 extending from both ends of the rear cross part 22, and a left longitudinal part 27 and a right longitudinal part 28 extending in the longitudinal direction of the vehicle and connecting with the front cross part 21 and the rear cross part 22, as shown in
The front cross part 21 and the rear cross part 22, the front arm parts 23, 24 and the rear arm parts 25, 26, and the left longitudinal part 27 and the right longitudinal part 28 are cast members based on an aluminum alloy.
The front cross part 21 is a channel shape that opens downward, as shown in
As a countermeasure, a reinforcing plate 29 is added to the widthwise center part of the front cross part 21, as shown in
The reinforcing plate 29 is a wrought material formed of one of aluminum or an aluminum alloy. The reinforcing plate 29 is brought against and welded to the front cross part 21 with the aim of covering the downward opening of the front cross part 21, which is a cast member, as shown in
The center part is reinforced by the reinforcing plate 29 in the same manner as the front cross part 22, and the left and right longitudinal parts 27, 28 shown in
The weld joint of the present invention is appropriate for a subframe of a vehicle, but may be used in other weld structures.
The weld joint of the present invention is appropriate for a subframe of a vehicle.
10 Structure
11 Cast member
12 Wrought material
12
a End part of wrought material
13 Inserting portion
14 Slope
15 Bead
L Root space
T Wrought material thickness
θ Groove angle
Number | Date | Country | Kind |
---|---|---|---|
2009-099265 | Apr 2009 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2010/056766 | 4/15/2010 | WO | 00 | 10/14/2011 |