JP2000107873A - Joining method of aluminum alloy made arm member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen a strength reduction in a joined part and to secure high dimensional precision. SOLUTION: In a joining method of aluminum alloy made arm members wherein a relative rotation is stopped and an upset pressure is imparted after mutual joining boundary surfaces are heated by friction by imparting the relative rotation and a frictional pressure to a first member and a second member made of an aluminum alloy and the first member is brought into frictional press-contact with the second member in the joining boundary surfaces, the time in the heat generation process by friction is set to 0.1-1.0 sec, the upset pressure is set to 12-20 Kgf/mm2, the number of rotation of the relative rotation is set to 800-1200 rpm and then joining is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining an aluminum alloy arm member used as, for example, a vehicle suspension arm.

[0002]

2. Description of the Related Art Conventionally, steel materials have been used for suspension arms (e.g., upper arm, lower arm, etc.) mounted on vehicles. In recent years, however, aluminum alloys have been actively used due to the need for lighter vehicles. Is underway. In general, a suspension arm made of an aluminum alloy often has an integral shape formed by hot forging. In hot forging, since there is almost no internal defect and the strength is stable, there is a problem that the reliability is high but the cost is high.

[0003] In addition, in various casting methods (for example, gravity casting, low pressure casting, die casting, squeeze casting, etc.), an integral shape can be manufactured at a relatively low cost, but internal defects such as pinholes and cracks are liable to occur. There is a problem in static strength and durability. Further, a welded structure of a pipe material and a ring material formed by wrought material is also possible, but in the case of aluminum alloy, a general welding method (for example, MIG welding,
When TIG welding or the like is employed, the strength of the welded portion is reduced due to the influence of heat, and it is necessary to increase the wall thickness in consideration of the reduced strength due to internal defects and the like. As a result, the effect of reducing the weight is reduced. There is a problem.

On the other hand, there is a friction welding method widely used mainly for iron-based materials as a joining method of pipe materials and rod materials. In this friction welding method, after applying relative rotation and friction pressure to the first member and the second member to be joined to generate frictional heat at the mutual joining interface, the relative rotation is stopped and upset pressure is applied, The first member and the second member are friction-welded at the joining interface, and have the following advantages.

[0005] That is, since bonding can be performed at a temperature equal to or lower than the melting point, it is possible to obtain a bonded portion that is less affected by heat. Since the joint generates plastic flow and is discharged as burrs, there are very few internal defects. Since joining can be performed in a short time, there is no need for a welding rod or a high-precision groove shape, and there is no equipment consumable part, construction can be performed at low cost.

[0006]

However, when joining aluminum alloy members by the friction welding method, sufficient joining strength can be obtained even if the friction welding conditions of the iron members are applied as they are. Can not. That is, the aluminum alloy has a higher thermal conductivity than iron, and thus is easily affected by heat, and the strength of the joint is lower than that of the base metal. In addition, aluminum alloy is softer than iron and has a higher coefficient of thermal expansion, so that thermal distortion is increased. Therefore, variation in offset is large, and high dimensional accuracy cannot be secured.

The present invention has been devised in view of the above problems, and has been made to solve the problem of providing a method of joining an aluminum alloy arm member which can reduce a decrease in strength of a joined portion and ensure high dimensional accuracy. It should be a task to be done.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found optimum conditions for joining aluminum alloy arm members by friction welding. completed. That is, according to the first aspect of the present invention, the first member and the second member made of an aluminum alloy are subjected to relative rotation and frictional pressure to generate frictional heat at the mutual joining interface, and then the relative rotation is stopped and the upset is performed. A method of joining an aluminum alloy arm member by applying pressure and friction-welding the first member and the second member at the joining interface, wherein the time of the friction heating step is set to 0.
1 to 1.0 second, and the upset pressure is 12 to 20 k
gf / mm ² , and the relative rotation speed is 800 to 1
A means of performing the operation at 200 rpm is employed.

In the present invention, the time of the friction heating step is a time during which a relative rotation and friction pressure are applied to the first member and the second member to generate frictional heat at the mutual joining interface. A more preferable range of the time of the friction heating step is 0.1.
2 to 0.7 seconds. Further, the upset pressure refers to a pressure applied to the joining interface during or after the relative rotation of the first member and the second member is stopped after the friction heating process is completed. A more preferable range of the upset pressure is 1
It is 4 to 18 kgf / mm ² . Further, the rotation speed of the relative rotation refers to the rotation speed of the relative rotation between the first member and the second member during the friction heating process.

[0010] The aluminum alloy arm member of the present invention
In the joining method, the time of the friction heating step is set to a predetermined range (0.
(1 to 1.0 seconds)
The sound is suppressed as much as possible. Also, set the upset pressure within a certain range.
Enclosure (12-20 kgf / mm ^TwoBy raising
Promotes plastic flow in the softened part formed by frictional heating
And discharge it as burrs, which reduces the
As a result, a joint with a small decrease in strength can be obtained.
Further, the rotational speed of the relative rotation is set to a predetermined range (800 to 12).
00 rpm), fine calorie control
Is possible, and the variation in the shift allowance is suppressed.
Dimensional accuracy is secured.

Therefore, according to the method for joining aluminum alloy arm members of the present invention, a decrease in strength of the joined portion can be reduced and high dimensional accuracy can be secured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an arm member joined by the joining method according to the present embodiment, and FIG.
FIG. 2 is a sectional view taken along line II-II. The method for joining arm members according to the present embodiment is applied to a suspension arm of an automobile as shown in FIGS. 1 and 2. The connecting portion 2 and the bearing portion 3 made of an alloy are friction-welded under predetermined conditions.

The arm member 1 is formed of an aluminum alloy (A6061) in a pipe shape (outside diameter: 20 mm, inside diameter: 16 mm, length: 230 mm).
The connecting portion 2 is formed in a U-shape from an aluminum alloy (A6061), and a distal end surface of a cylindrical (diameter: 20 mm) joining portion 21 protruding from an outer surface of a central portion thereof is formed in one end of the arm body 1. Joined to the end face.

The bearing 3 is entirely formed of an aluminum alloy (A6061), and has a cylindrical portion 31 and a pair of legs 32, 32 extending from the outer peripheral surface of the cylindrical portion 31.
An arm body 1 is formed by connecting the distal ends of the two legs 32, 32 to each other.
Square plate (20 mm x 32 mm,
(Thickness: 5 mm). The cylindrical portion 31 of the bearing portion 3 has an inner cylindrical member 35 coaxially arranged at a distance inside the cylindrical portion 31 and a vulcanized adhesive between the cylindrical portion 31 and the inner cylindrical member 35. It is mounted before the cylindrical rubber elastic body 36 interposed therebetween is friction-welded.

In this embodiment, the spindle device grips one member rotatably on the distal end side, and grips the other member in opposition to the one member, and applies friction pressure and upset pressure to both works. The joint 21 of the connecting portion 2 is friction-welded to one end surface of the arm body 1 using a brake-type friction welding machine having a pressure applying device capable of applying the pressure.
The joining portion 33 of the bearing 3 is friction-welded to the other end surface of the bearing 3.

First, when the arm body 1 as the first member and the connecting portion 2 as the second member are joined, for example, the arm device 1 is gripped by the spindle device, and the joining portion is attached to the end face of the arm body 1. The connecting portion 2 is gripped by the pressure applying device so that 21 faces each other. And the number of rotations is 800-
By operating the spindle device and the pressure applying device set within the range of 1200 rpm, respectively, the arm body 1
And, relative rotation and frictional pressure are applied to the connecting portion 2 to generate frictional heat at the mutual joint interface. The time of the friction heating step is set within a range of 0.1 to 1.0 second.

Thereafter, the rotation of the spindle device is suddenly stopped, and the pressure applying device is operated to apply an upset pressure to the arm body 1 and the connecting portion 2 within a range of 12 to 20 kgf / mm ² . Thereby, the arm main body 1 and the connecting portion 2 are friction-welded at the joint interface. Next, when the arm body 1 as the first member and the bearing portion 3 as the second member are joined, the rotation of the relative rotation is performed in the same manner as when the arm body 1 and the connecting portion 2 are friction-welded. The number, the time of the friction heating step and the upset pressure are set in the above-mentioned predetermined ranges.

As described above, according to the arm member joining method of the present embodiment, the time of the friction heating step is reduced to a predetermined range (0.1 to 1.0 second), so that the base material Is minimized and the upset pressure is set within a predetermined range (12 to 20 kgf / mm ² ), so that the plastic flow of the softened part due to the heat is promoted and discharged as burrs, so that the softened region is discharged. A narrow joint can be obtained. As a result, it is possible to complete the joining with less decrease in strength.

When the bearing 3 and the arm main body 1 are subjected to friction welding, the rubber elastic body 36 is preliminarily attached to the bearing 3 so as to be joined in advance because the thermal influence on the base material is small. Therefore, the assembly process can be simplified.
Further, the number of rotations of the relative rotation is within a predetermined range (800 to 12).
(00 rpm), it is possible to finely control the amount of heat, so that variations in the margin can be suppressed and high dimensional accuracy can be secured.

[Test] In order to confirm the excellent effects of the present invention, the friction pressure between the pipe-shaped first member 10 and the prism-shaped second member 20 made of an aluminum alloy (A6061-T6) was determined. The test was performed by changing various conditions such as upset pressure, friction time, upset time, and rotation speed. The friction welding machine used was the same brake type as that of the above embodiment.

As shown in FIG. 3, the first member 10 has an inner diameter d ₁ : 21.6 mm and an outer diameter d ₂ : 2 at the distal end to be joined.
It is formed into a pipe having a length of 8.0 mm and a length of l ₁ : 60.0 mm, and has a diameter D ₁ : 2 at a rear end held by a friction welding machine.
It is formed in a columnar shape having a length of 0.0 mm and a length l _{2 of} 50.0 mm, and has a total length L _{1 of} 150 mm. As shown in FIG. 4, the second member 20 is a square having a length l ₃ : 31.0 mm on one side and a length l ₄ : 15.
The rear end side formed in a prism shape of 0.0 mm and held by the friction welding machine has a diameter D ₂ : 20.0 mm and a length l ₅ : 50.
It is formed in a cylindrical shape of 0 mm and has a total length L _{2 of} 150 m.
m.

[0022]

[Table 1]

As shown in conditions 1 to 9 in Table 1,
When the first member 10 and the second member 20 are friction-welded to each other,
The friction time in the range of 0.1 to 1.5 seconds
And measure the rupture stress at each joint to determine the rupture strength.
Examined. At this time, the other friction welding conditions are as follows:
6kgf / mm^Two, Upset pressure is 16kgf / mm
^Two, Upset time is 4 seconds, rotation speed is 1000rpm
All unified. The results are shown in Table 1 and FIG.

As is clear from Table 1 and FIG. 5, the condition No. for which the friction welding time is relatively long (1.2 to 1.5 seconds)
In the case of 8, 9, the breaking strength was 20 kgf / m in both cases.
m ² and about, it can be seen that sufficient strength can not be obtained. On the other hand, in the case of conditions No. 1 to 7 where the friction welding time is short (0.1 to 1.0 second), the breaking strength is 25 kg in all cases.
The value of f / mm ² or more indicates that sufficient strength can be obtained. In particular, in the case of the conditions Nos. ² to 6, the breaking strength was all 29 kgf / mm ² or more, which is extremely good.

Further, as shown in conditions Nos. 10 to 17 in Table 1, when the first member 10 and the second member 20 are friction-welded, the upset pressure is variously changed in the range of 6 to 20 kgf / mm ² , The breaking stress at the joint was measured to determine the breaking strength. At this time, the friction pressure was the same as the respective upset pressure, and the other friction welding conditions were such that the friction time was 0.4 seconds, the upset time was 4 seconds, and the rotation speed was 1000 rpm. The results are shown in Table 1 and FIG.

As is clear from Table 1 and FIG.
Low set pressure (6 to 8 kgf / mm^Two) Condition No1
In the case of 0 to 11, the breaking strength was 17 kgf /
mm ^TwoIt is understood that the strength is not enough.
You. The upset pressure is relatively low (10 kgf /
mm^Two) In the case of condition No. 12, the breaking strength was 23.3.
kgf / mm^TwoValue is not enough but good
Strength.

On the other hand, when the upset pressure is high (12 to 20)
kgf / mm ² ) In the case of conditions Nos. 13 to 17, the breaking strength shows a value of 25 kgf / mm ² or more, indicating that sufficient strength can be obtained. In particular, condition No. 14
In the case of ~ 16, the breaking strength was 30 kgf / m
m ² or more, a remarkably high strength is obtained as compared with the condition Nos. 10 to 11, and it is extremely good.

[0028]

[Table 2]

Next, as shown in conditions Nos. 1 to 30 in Table 2, when the first member 10 and the second member 20 are friction-welded, the relative rotation speed is variously changed within the range of 800 to 2400 rpm. I checked the approaching cost. At this time, the other friction welding condition is that the friction pressure is 16 kgf / mm.
^{2. The} upset pressure was 16 kgf / mm ² , the friction time was 0.4 seconds, and the upset time was 4 seconds. Note that the measurement of the offset is performed five times at the same rotation speed, and the results are shown in Table 2 and FIG.

As is clear from Table 2 and FIG. 7, the condition No. 16 to high rotational speed (150 to 2400 rpm)
In the case of 30, the maximum value of the shift allowance at each rotation speed is 15
It was 4.1 to 6.0 mm at 00 rpm, 6.2 mm at 2000 rpm, and 8.0 mm at 2400 rpm, and increased as the number of rotations increased. Also, the variation width at each rotation speed increased as the rotation speed increased.

On the other hand, when the rotation speed is low (800 to 1200 rpm)
pm) In the case of the conditions Nos. 1 to 15, the margin was concentrated in the range of 3.7 to 4.8 mm. Thus, it can be seen that the maximum value of the margin is small and the variation width is extremely small as compared with the cases of the conditions Nos. 16 to 30. Therefore, as in conditions Nos.
By lowering the speed to 1200 rpm, the margin can be reduced, and high dimensional accuracy after friction welding can be ensured.

[Brief description of the drawings]

FIG. 1 is a plan view of an arm member joined by a joining method according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an explanatory diagram showing the shape and dimensions of a first member used for a test.

FIG. 4 is an explanatory diagram showing the shape and dimensions of a second member used for a test.

FIG. 5 is a graph showing the relationship between friction time and breaking strength in a test.

FIG. 6 is a graph showing a relationship between an upset pressure and a breaking strength in a test.

FIG. 7 is a graph showing a relationship between a rotational speed and a margin in a test.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arm main body (1st member) 2 ... Connection part (2nd member) 3 ... Bearing part (2nd member) 10 ... 1st member 2
0 ... second member 21 ... joining part 31 ... cylindrical part 32 ... leg
33: Joint 35: Inner tube fitting 36: Rubber elastic body

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Rentaro Kato 3600, Gezu, Kitagaiyama, Komaki, Aichi Prefecture Inside Tokai Rubber Industries Co., Ltd. No. 3600 Tokai Rubber Industries Co., Ltd. (72) Shoichi Sato Inventor 6,224, Kaiyamacho, Sakai-shi, Osaka F-term in Showa Aluminum Co., Ltd. 3D001 AA17 AA18 BA01 DA04 4E067 AA05 BG02 DC03 DC07 EA07

Claims (1)

[Claims] 1. A first member and a second member made of an aluminum alloy.
After applying relative rotation and friction pressure to the members to generate frictional heat at the mutual joining interface, the relative rotation is stopped to apply an upset pressure, and the first member and the second member are frictionally joined at the joining interface. A method of joining an aluminum alloy arm member to be pressed, wherein a time of a friction heating step is 0.1 to 1.0 second, an upset pressure is 12 to 20 kgf / mm ^2, and a rotation speed of the relative rotation is 800 A method of joining aluminum alloy arm members, wherein the method is performed at a speed of 1200 rpm.