JP2008272818A - Friction welding structure and axle housing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving bending strength of a friction welding structure. <P>SOLUTION: In the axle-housing, an axle end part 18 and an axle tube part 14 are joined by friction welding. The axle end part 18 includes an annular first ring projection 18a that axially extends and an annular second ring projection 18b that has a diameter larger than that of the first ring projection 18a and axially extends. The axle tube part 14 has a tip end face annularly formed. The tip end face of the first ring projection 18a is joined with that of the axle tube part 14 by friction welding. A support member 22 is interposed between the second ring projection 18b and the axle tube part 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction welding structure in which metal members are joined to each other by friction welding, and an axle housing using the friction welding structure.

  Conventionally, as an axle housing applied to a rigid axle suspension for a vehicle, a differential case portion in which a differential gear is accommodated, an axle tube portion into which an axle shaft is inserted, and the like are known to be joined together by welding.

One welding method used for such an axle housing is friction welding. In friction welding, one side of a member is rotated, the other member is pressed against the rotating member end surface, the rotation is suddenly stopped at a place where plastic deformation is likely to occur due to the frictional heat generated at that time, and the member is pressed with a higher pressure. It is the method of joining by. Friction welding has advantages such as being able to perform high-precision bonding with relatively simple work and being suitable for bonding different materials (for example, see Patent Documents 1 to 3 for friction welding).
JP 2005-271015 A JP 11-1118080 A JP 2005-81351 A

  By the way, the axle housing is a member located under a so-called unsprung portion of the vehicle, so that its weight is a so-called unsprung weight. If the unsprung weight increases, the ride comfort and ground contact of the vehicle will be affected. Therefore, it is preferable to make the axle housing as light as possible.

  In order to reduce the weight of the axle housing, the present inventor is diligently researching and developing an axle housing in which various dissimilar metals are joined by friction welding, and the friction welding structure using a combination of dissimilar metals has high torsional strength. However, he recognized the problem that bending strength was relatively weak.

  This invention is made | formed in view of such a condition, The objective is to provide the technique which improves the bending strength of a friction welding structure.

  In order to solve the above-described problem, a friction welding structure according to an aspect of the present invention is a friction welding structure in which a first member and a second member are joined by friction welding, and the friction between the first member and the second member. A support member that contacts the first member and the second member is provided at a position different from the joining position.

  According to this aspect, since the support member that contacts the first member and the second member is provided at a position different from the friction joining position of the first member and the second member, the friction occurs when the support member is not provided. Since the bending stress generated at the joining position can be distributed to the contact position of the support member, the bending stress at the friction joining position can be reduced. Thereby, the bending strength as the whole friction welding structure can be improved.

  The first member and the second member may be made of different metals. As described above, the friction welding structure using a combination of different metals has high torsional strength but relatively low bending strength. Therefore, the friction welding structure according to the present invention is particularly effective when the first member and the second member are dissimilar metals.

  The first member has an annular first annular protrusion that extends in the axial direction, and an annular second annular protrusion that extends in the axial direction and has a larger diameter than the first annular protrusion, The tip surface of the second member is formed in an annular shape, and the tip surface of the first annular protrusion is joined to the tip surface of the second member by friction welding, and the second annular protrusion and the second member are joined together. A support member may be interposed therebetween. Further, the first annular protrusion may be formed shorter in the axial direction than the second annular protrusion.

  In this case, when no support member is provided, the bending stress generated at the friction joint position between the tip surface of the first annular protrusion and the tip surface of the second member can be distributed to the contact position of the support member. The bending stress of can be reduced. Thereby, the bending strength as the whole friction welding structure can be improved.

  Another aspect of the present invention is an axle housing. This axle housing is an axle housing configured by joining together a differential case part, a pair of left and right axle tube parts provided in the differential case part, and an axle end part provided at an end of the axle tube part. The differential case part and the axle tube part, and the axle tube part and the axle end part are joined by the above-described friction welding structure.

  According to this aspect, it is possible to configure the axle housing in which the bending strength of the joining position between the differential case part and the axle tube part and the joining position between the axle tube part and the axle end part is improved.

  The axle tube portion may be formed of an iron-based material, and the differential case portion and the axle end portion may be formed of an aluminum-based material. In this case, the axle housing can be reduced in weight by forming the differential case portion and the axle end portion with an aluminum-based material that is lighter than the iron-based material. Thereby, since the unsprung weight can be reduced, it is possible to improve the riding comfort, ground contact and fuel consumption of the vehicle.

  According to the present invention, the bending strength of the friction welding structure can be improved.

  FIG. 1 is a view showing an axle housing 10 according to an embodiment of the present invention. An axle housing 10 shown in FIG. 1 is a rear axle housing used on the rear wheel side of a vehicle. The axle housing 10 includes a differential case portion 12, a pair of left and right axle tube portions 14 and 16 provided in the differential case portion 12, and axle end portions 18 and 20 provided at respective end portions of the axle tube portions 14 and 16. It is configured by joining together.

  The differential case part 12 accommodates a differential gear rotatably. The differential case part 12 is formed of an aluminum-based material. The aluminum-based material refers to aluminum or an aluminum alloy in which various elements are alloyed with aluminum. Since the bending force is hardly applied to the differential case portion 12, the weight of the differential case portion 12 can be reduced by using an aluminum material that is lighter than an iron-based material. The differential case portion 12 can be formed by casting or forging. Further, the differential case portion 12 may be subjected to heat treatment such as quenching. Thereby, the intensity | strength of the differential case part 12 can be raised.

  The axle tube portions 14 and 16 are provided so as to extend from the differential case portion 12 to the left and right in the vehicle width direction. The differential case portion 12 and the axle tube portion 14 and the differential case portion 12 and the axle tube portion 16 are joined by a friction welding structure described later with reference to FIG.

  Axle shafts that transmit the driving force from the differential gear to the wheels are inserted into the axle tube portions 14 and 16. The axle tube portions 14 and 16 are formed in a hollow cylindrical shape. The axle tube portions 14 and 16 are made of an iron-based material. The iron-based material refers to an iron-based alloy such as iron or carbon steel. The axle tube portions 14 and 16 may be formed by casting or forging, or may be formed by extrusion or pultrusion. Further, the axle tube portions 14 and 16 may be subjected to heat treatment such as quenching. Thereby, the intensity | strength of the axle tube parts 14 and 16 can be raised.

  Many members, such as a bracket for attaching to the vehicle body, are welded to the axle tube portions 14 and 16. Since a bending stress is generated at a portion where the bracket is welded, an iron-based material having a high bending strength is used. Further, since the bracket is a member that requires strength, it is often formed of an iron-based material. Therefore, weldability can be improved by forming the axle tube parts 14 and 16 with the same kind of iron-based material as the bracket.

  The axle end portions 18 and 20 are joined to the end portions of the axle tube portions 14 and 16, respectively. The axle tube portion 14 and the axle end portion 18 and the axle tube portion 16 and the axle end portion 20 are also joined by a friction welding structure described later with reference to FIG.

  The axle end portions 18 and 20 are formed in a thick cylindrical shape having a wide end portion. The axle end portions 18 and 20 are formed of an aluminum-based material. By using an aluminum-based material, the axle end portions 18 and 20 can be reduced in weight. The axle end portions 18 and 20 can be formed by casting or forging. Further, the axle end portions 18 and 20 may be subjected to heat treatment such as quenching. Thereby, the intensity | strength of the axle end parts 18 and 20 can be raised.

  FIG. 2 is a cross-sectional view showing a joint position 30 between the axle tube portion 14 and the axle end portion 18. As shown in FIG. 2, the axle tube portion 14 has an annular end surface.

  The axle end 18 includes an annular first annular protrusion 18a extending in the axial direction, an annular second annular protrusion 18b having a larger diameter than the first annular protrusion 18a, and extending in the axial direction. Have The first annular protrusion 18a is shorter in the axial direction than the second annular protrusion 18b. The length in the axial direction here refers to the distance from the root portion 18c from which the first annular protrusion 18a and the second annular protrusion 18b protrude to the protruding tip surface.

  In the axle end portion 18, the outer peripheral surface 18d of the first annular projecting portion 18a and the inner peripheral surface 18e of the second annular projecting portion 18b are formed to be separated from each other by a predetermined distance. Further, the outer diameter of the first annular projecting portion 18 a is formed to be substantially equal to the outer diameter of the axle tube portion 14.

  The distal end surface of the first annular protrusion 18a is joined to the distal end surface of the axle tube portion 14 by friction welding. In the friction welding, the annular tip surface of the first annular protrusion 18a and the annular tip surface of the axle tube portion 14 are pressed against each other, and the axle end portion 18 and the axle tube portion 14 are rotated relatively to each other. Frictional heat is generated on the surface, and when heating by the frictional heat reaches a predetermined condition, a larger force is applied and pressed. By joining by friction welding, the axle end part 18 and the axle tube part 14 can be joined without the need to provide another member such as an insert. Further, by friction welding the iron-based material and the aluminum-based material, higher strength can be obtained against torsional force.

  In the present embodiment, the axle end portion 18 and the axle tube portion 14 are brought into contact with each other at a position different from the friction joining position 40 between the distal end surface of the first annular protrusion 18a of the axle end portion 18 and the distal end surface of the axle tube portion 14. A support member 22 is provided.

  The support member 22 includes a cylindrical portion 22a and an annular protruding portion 22b protruding in the axial direction with a predetermined thickness along the inner peripheral edge of the cylindrical portion 22a. The support member 22 is formed of a metal material. The inner diameters of the cylindrical portion 22a and the annular protruding portion 22b are formed to be approximately the same size as the outer diameter of the axle tube portion 14. Further, the outer diameter of the cylindrical portion 22a is larger than the inner diameter of the second annular projecting portion 18b of the axle end portion 18, and is preferably formed to have substantially the same size as the outer diameter of the second annular projecting portion 18b. Further, the outer diameter of the annular projecting portion 22b is formed to be slightly larger than the inner diameter of the second annular projecting portion 18b for press-fitting described later.

  The support member 22 is interposed by being press-fitted into a space between the outer peripheral surface of the axle tube portion 14 and the inner peripheral surface of the second annular projecting portion 18b. When joining the axle end portion 18 to the axle tube portion 14, the axle tube portion 14 is first inserted into the support member 22, and then the front end surface of the first annular projecting portion 18 a of the axle end portion 18 and the axle tube portion. The tip surfaces of 14 are joined by friction welding. Due to the friction welding, burrs 42 are generated in the space between the first annular protrusion 18 a and the second annular protrusion 18 b and the space on the inner peripheral side of the axle end 18. Thereafter, the cylindrical portion 22a of the support member 22 is pressurized in the direction of the axle end portion 18 so that the space between the outer peripheral surface of the axle tube portion 14 and the inner peripheral surface of the second annular projecting portion 18b is increased. The annular protrusion 22b is press-fitted.

  By forming the outer diameter of the cylindrical portion 22a to be larger than the inner diameter of the second annular projecting portion 18b of the axle end portion 18, it can function as a stopper for press-fitting. In order to smoothly press-fit, it is preferable that the outer peripheral portion of the front end surface of the annular protrusion 22b and the inner peripheral portion of the front end surface of the second annular protrusion 18b are chamfered. For example, it is preferable to secure the press-fitting margin of about 10 mm to 20 mm.

  In the present embodiment, since the joining position 30 between the axle tube portion 14 and the axle end portion 18 is configured as described above, when the support member 22 is not provided, the distal end surface of the first annular projecting portion 18a and the axle tube are provided. Since the stress generated at the friction bonding position 40 on the tip end surface of the portion 14 can be distributed to the contact position of the support member 22, the bending stress at the friction bonding position 40 can be reduced. Thereby, the bending strength as the joining position 30 whole can be improved.

  Also at the joining position 32 of the other axle tube portion 16 and the axle end portion 20, the supporting member 24 is used to join by the friction welding structure similar to the joining position 30. Also, the joining positions 34 and 36 of the differential case 12 and the axle tube parts 14 and 16 are joined by the friction welding structure similar to the joining position 30 using the support members 26 and 28. At the joining positions 34 and 36, the first annular projecting portion and the second annular projecting portion similar to the axle end portion 18 are formed at the joining portion of the differential case portion 12.

  According to the axle housing 10 configured as described above, the bending strength at each joint position can be improved by providing the support members 22, 24, 26, and 28 at the joint positions 30, 32, 34, and 36, respectively. . Furthermore, since the differential case portion 12 and the axle end portions 18 and 20 are made of an aluminum-based material that is lighter than an iron-based material, the weight of the axle housing 10 can be reduced. As a result, it is possible to improve the riding comfort, ground contact, and fuel consumption of the vehicle while ensuring the strength required for the axle housing.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  In the above-described embodiment, the axle housing has been described. However, the friction welding structure according to the present embodiment can naturally be applied to other members such as an axle shaft.

  Further, in the above-described embodiment, the friction welding structure for joining the iron-based material and the aluminum-based material has been described. However, the friction welding structure according to the present embodiment may be a combination of other dissimilar metal materials or the same type. The present invention can also be applied to the case of joining other metal materials.

It is a figure which shows the axle housing which concerns on embodiment of this invention. It is sectional drawing which shows the joining position of an axle tube and an axle end part.

Explanation of symbols

  10 Axle housing, 12 Differential case part, 14, 16 Axle tube part, 18, 20 Axle end part, 18a First annular projection part, 18b Second annular projection part, 22, 24, 26, 28 Support member, 30, 32, 34, 36 Joint position.

Claims (6)

A friction welding structure in which the first member and the second member are joined by friction welding,
A friction welding structure, wherein a support member that contacts the first member and the second member is provided at a position different from a friction joining position of the first member and the second member.   The friction welding structure according to claim 1, wherein the first member and the second member are made of different metals. The first member has an annular first annular protrusion that extends in the axial direction, and an annular second annular protrusion that has a larger diameter than the first annular protrusion and extends in the axial direction. And
The second member has a tip surface formed in an annular shape,
The front end surface of the first annular protrusion is joined to the front end surface of the second member by friction welding,
The friction welding structure according to claim 1 or 2, wherein the support member is interposed between the second annular protrusion and the second member.   The friction welding structure according to claim 3, wherein the first annular protrusion is shorter in the axial direction than the second annular protrusion. An axle housing configured by joining together a differential case part, a pair of left and right axle tube parts provided in the differential case part, and an axle end part provided at an end of the axle tube part;
The axle housing, wherein the differential case part and the axle tube part, and the axle tube part and the axle end part are joined by the friction welding structure according to any one of claims 1 to 4.   6. The axle housing according to claim 5, wherein the axle tube portion is formed of an iron-based material, and the differential case portion and the axle end portion are formed of an aluminum-based material.

Images