JP2003146240A - Sub-frame for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum or aluminum alloy sub-frame for an automobile capable of being easily mounted on a frame even when a slight manufacturing error exists in a sub-frame body. SOLUTION: A collar member 10 is arranged at the end of the sub-frame body 11 for connecting the sub-frame to an automobile body frame. The collar member 10 has a cylindrical portion 12 into which a bolt is inserted and a flat portion 13 formed extending outward to both ends of the cylindrical portion in the axial direction. The collar member is welded at the flat portion 13 to the body 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile subframe on which an engine or the like is mounted and which is fixed to a vehicle body frame (hereinafter referred to as a body frame) of an automobile, and more particularly to a collar member which is a connecting portion with the body frame. The present invention relates to an improved automobile subframe.

[0002]

2. Description of the Related Art An automobile subframe is attached to a lower portion of a body frame before and after the vehicle. For example, in a front wheel steering rear wheel drive (FR) vehicle, a front subframe attached to a front portion of a vehicle body is The rear suspension and the differential gear are mounted on the rear subframe to which the engine and the front suspension are mounted and which is mounted on the rear part of the vehicle body. A power train is configured by the subframe to which the engine or the like is attached, and a body frame is mounted on and connected to the powertrain. Therefore, the subframe receives vibrations from the road surface during traveling via the suspension, a large load is applied to the subframe via the suspension, and the connecting portion between the subframe and the body frame receives the dynamic load. It must be able to withstand.

On the other hand, in order to reduce the weight of an automobile, it has been proposed to manufacture a frame and a subframe from aluminum or an aluminum alloy (hereinafter collectively referred to as an aluminum material) (Japanese Patent Laid-Open No. 2000-238657, Japanese Patent Laid-Open No. 2000-238657). 200
0-177621 etc.).

FIG. 3 shows the shape of a conventional general subframe. In this sub-frame, collar members 2 are provided at four corners of the main body 1. For example, a cushion rubber bush is press-fitted into the collar member 2, and a rod-shaped fastening member such as a bolt is inserted inside the collar member. The subframe is fixed to the body frame by a fastening member. Generally, the main body 1 is formed in a frame shape by welding and joining a plurality of frame members to each other as shown in FIG.
This sub-frame is required to have high dimensional accuracy as a whole, and in particular, high precision is required for the center distances a, b and c of the collar member 2 which is a mounting portion to the frame.

4A and 4B show a state in which the collar member 2 is joined to the tip of the main body 1 by welding 7. Body 1
Is processed into an arc shape so that its edge surrounds approximately half of the collar member 2. The collar member 2 is fitted into this curved portion, and the end portion of the main body 1 and the collar member 2 form a T-joint. Are formed and are fixed by one-sided welding 7.

FIG. 5 is a perspective view showing a method of attaching the sub-frame 4 and the frame 3. The cushioning rubber bush 5 is press-fitted into the cylindrical portion 2 of the collar member 5, and the bolt 6 is inserted inside thereof, and the bolt 6 is attached to the mounting hole shaft of the body frame 3 (also the cushioning rubber bush is press-fitted therein). In most cases) and place the nut 8 above the body frame 3.
The sub-frame 4 is fixed to the body frame 3 by screwing the sub-frame 4 onto the bolt 6.

[0007]

However, when a subframe is manufactured by assembling a frame member made of an aluminum material into a frame shape by welding, the aluminum material has a higher springback after forming than the steel material and thermal strain of welding. Is large, the dimension after welding easily deviates from the design value, and the conventional sub-frame 1 has a problem that the dimension error is large. In particular, in order to attach the sub-frame to the body frame, it is necessary that the center distances a, b, c of the collar members 2 match the design values with high accuracy. Since it is arranged at the end portion, there is a drawback that a dimensional error due to distortion is remarkably expressed with respect to the center interval of the collar member 2. In an extreme case, the subframe may be attached to the body frame. become unable.

Conventionally, in order to prevent this irregularity in shape, a large number of holders are used to prevent a gap from being formed in the groove of the welded portion before the frame member is welded, and further, after welding, a special Although it is corrected by using a jig, there is a problem that these processes are inefficient in production and complicate the manufacturing process.

The present invention has been made in view of the above problems, and even if there is a slight manufacturing error in the subframe body, it can be easily attached to the frame for an automobile made of aluminum or aluminum alloy. It is intended to provide subframes.

[0010]

An automobile subframe according to the present invention is an automobile subframe made of aluminum or aluminum alloy, and has a subframe main body and a collar member for connecting to the automobile body frame. The collar member has a cylindrical portion into which a rod-shaped fixture is inserted, and flat portions formed so as to extend outward at both axial end portions of the cylindrical portion, and the collar member is It is characterized in that the flat portion is fixed to the main body by welding.

In this automobile sub-frame, the collar member can be bent to form a flat portion by electromagnetically expanding both ends of a cylindrical member.

In the collar member, for example, a pair of the flat portions are arranged so as to sandwich the main body, and the flat portions are fillet welded to the surface of the main body to fix the collar member to the main body. Has been done.

According to the present invention, when the collar member is welded and joined to the end portion of the main body by the flat portion, the flat portion is formed on the collar member even if the main body has a slight dimensional error. The relative positional relationship between the flat portion and the end portion of the main body can be adjusted, and the dimensional error can be absorbed. Therefore, the central dimension of the collar member can be easily matched with the design value with high accuracy.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. 1 (a) to 1 (c) show an automobile sub-frame according to an embodiment of the present invention. The sub-frame body 11 is an extruded material obtained by extruding an aluminum material into a cylindrical shape or a rectangular tube shape, or welds a plurality of frame members made of a bonding material welded to form the cylindrical shape or the rectangular tube shape. By doing so, the shape is formed as shown in FIG. This frame member has a rectangular tube shape in which liquid pressure is applied to the inside to adjust the cross section, and the end portion is crushed from the outside by a press.

The tip of the main body 11 is cut into a semicircular shape, and the cylindrical portion 12 of the collar member 10 is fitted into the tip of the main body 11. The collar member 10 is the cylindrical portion 1.
The two axial end portions of 2 are expanded and formed, and flat portions 13 are formed at both end portions of the cylindrical portion. This flat portion can be formed by means such as electromagnetic forming or press forming.

FIG. 2 is a sectional view showing an electromagnetic forming method of the collar member 10. A cylindrical material 20 shown by a chain double-dashed line in FIG. 2 is fitted into a ring-shaped jig 21. Jig 21
Has an inner diameter larger than the outer diameter of the material 20, and the collar member 1
It has a height corresponding to the length of the cylindrical portion 12 of zero. Material 2
0 is longer than the length of the collar member 10 and protrudes from the jig 21, and this portion becomes a flat portion by expansion molding.

Then, an electromagnetic coil 22 having an outer diameter smaller than the inner diameter is inserted into the material 20, and by energizing the electromagnetic coil 22, a magnetic field is applied to the material 20 to expand the material 20. Apply force. Then, the portion of the material 20 supported by the jig 21 is deformed along the inner diameter of the jig 21, and the portions not supported by the jig 21 (both axial end portions of the material 20) expand to form a flat portion. 13 is molded. Then, the jig 21 is divided and the collar member 10 is taken out.

The collar member 10 manufactured in this way
The subframe is manufactured by joining the subframe to the subframe main body 11. In this case, FIG.
As shown in (c), the flat portion 13 of the collar member 10 is
The sub-frame main body 11 is superposed on the tip portion and joined by fillet welding. In this case, if there is no dimensional error in the sub-frame main body 11, the flat portion 13 of the collar member 10 and the sub-frame main body 11 may be directly joined as shown in FIG. 1B. When the dimensional error X exists in the main body 11, that is, the subframe main body 1
If the dimension of 1 is less than the required dimension by X due to thermal strain, the flat portion 13 and the sub-frame main body 11 are displaced with the flat portion 13 of the collar member 10 being shifted outward by X.
Fillet welding is recommended. Reference numeral 14 is a welded joint.

As a result, even if the size of the main body 11 is less than the required size, the position of the center line of the collar member 10 can be accurately aligned with the predetermined position. The main body 1
When the length of 1 is expected to be longer than the predetermined dimension, the design dimension of the main body 11 is made shorter than the predetermined value in advance, and even if the length of the main body 11 is longer than the predetermined dimension, the dimensional error Can be absorbed.

In this way, the distance between the centers of the collar members of the subframe can be finished to a predetermined size.
The obtained sub-frame has a cylindrical portion 12 of the collar member 10.
It is possible to fix to the frame by press-fitting a cushioning rubber bush into the inside, further inserting a bolt (not shown), and screwing the bolt into a female screw provided on the frame.

[0021]

As described above, according to the present invention,
Even if there is a slight dimensional error in the manufacturing of the sub-frame body, the dimensional error can be absorbed by adjusting the relative positional relationship between the flat portion of the collar member and the sub-frame body. Therefore, the center-to-center distance of the collar member can be matched with a predetermined dimension with high accuracy, and even if there is a slight manufacturing error in the sub-frame body, it can be easily attached to the frame.

[Brief description of drawings]

1A to 1C are diagrams illustrating subframes according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a method for molding a collar member of a subframe.

FIG. 3 is a perspective view showing a conventional subframe.

4A and 4B are views showing a conventional method for attaching a collar member.

FIG. 5 is a perspective view showing a method of attaching the sub-frame 4 and the frame 3.

[Explanation of symbols] 1, 11: Main body 2, 10: Color member 3: Frame 4: Subframe 12: Cylindrical part 13: Flat part 14: Welded joint

Claims (3)

[Claims] 1. An automobile subframe made of aluminum or aluminum alloy, comprising a subframe body and a collar member for connecting to the automobile body frame, and the collar member is a cylinder into which a rod-shaped fixture is inserted. And a flat portion formed so as to extend outward at both axial ends of the cylindrical portion, the collar member being fixed to the main body by welding at the flat portion. Characteristic automobile subframe. 2. The subframe for an automobile according to claim 1, wherein the collar member has a flat portion formed by bending and bending both ends of a cylindrical member by electromagnetic expansion. 3. The collar member is arranged such that the pair of flat portions sandwiches the main body, and the flat portions are fillet-welded to the surface of the main body to fix the collar member to the main body. The subframe for an automobile according to claim 1 or 2, characterized in that: