JP7248283B2 - Manufacturing method of torsion beam - Google Patents

Description

The present invention relates to a method of manufacturing a torsion beam used in a torsion beam suspension system for a vehicle.

For example, a torsion beam type suspension device provided in a vehicle includes a metal torsion beam extending in the vehicle width direction and two arms fixed to both ends of the torsion beam. and a wheel is supported on this arm.

In recent years, there has been a demand for further weight reduction of vehicles from the viewpoint of improving fuel efficiency. In a torsion beam type suspension system, it is possible to reduce the weight of the torsion beam by molding the pipe into a predetermined shape. Higher shipping costs.

Therefore, as disclosed in Patent Documents 1 and 2, for example, a torsion beam manufacturing factory performs a process of forming a plate material into a pipe shape in a pipe-making process, and then forming it into a torsion beam of a predetermined shape. is considered to be performed continuously. If the material is made of plate material, it can be stacked and transported, so the transportation efficiency is high. Also, the plate material can be cut from the coil material at the torsion beam manufacturing factory, and either method is compared to transporting pipes. Transportation costs can be reduced.

Patent Literatures 1 and 2 disclose a method of obtaining a product shape by using a flat material and performing a multi-stage press molding process. In both methods, after molding by press working, the ends of the material are butted and welded.

Japanese Patent No. 5235924 JP-A-7-186654

By the way, as in Patent Documents 1 and 2, when the ends of the plate material are welded after press working, the weld quality is a major factor that affects the fatigue strength of the product. For example, when the ends of a material cut by a press machine are butted against each other, the material may warp due to springback, and a gap may be formed at the butted portion. If there is a gap during welding, it is not possible to obtain a predetermined thickness of the welded portion, and the required cross-sectional area of the welded portion cannot be secured, resulting in reduced fatigue strength of the product and unstable weld quality.

The present invention has been made in view of this point, and its object is to obtain a cylindrical torsion beam by pressing a plate material and then butting and welding the ends of the plate material to each other. To improve and stabilize the welding quality of a welded part.

In order to achieve the above object, a first invention provides a method of manufacturing a torsion beam used in a torsion beam type suspension device for a vehicle, in which the central portion in the width direction of a plate member is bulged in the longitudinal direction to form a bulge portion. a bending step of bending one side plate portion and the other side plate portion of the plate material positioned so as to sandwich the bulging portion in the bulging direction of the bulging portion; When forming the plate material into a tubular shape by press working including an end portion bending step of bringing the one end portion of the one side plate portion and the other end portion of the other side plate portion closer to each other, the plate material is formed into a tubular shape after the end portion bending step . One end and the other end of the coining process, in the coining process, the one side plate portion is pushed in a direction approaching the other side plate portion by a first side mold, and the other side plate portion is pushed by a second side metal mold By pressing the mold in a direction approaching the one side plate portion, the one end portion and the one side plate portion are projected onto the ridge portion provided on the upper mold so as to protrude between the one end portion and the other end portion and extend in the longitudinal direction. After the other end is abutted and the coining process is performed, the one end and the other end of the plate material are abutted and welded.

According to this configuration, since the one end and the other end of the plate material are strongly compressed before welding, warping of the plate material due to springback is suppressed, and the shapes of the butted portions of the one end and the other end match. do. After that, the one end portion and the other end portion of the plate material are butted and welded together, thereby making it difficult to form a gap between the one end portion and the other end portion. As a result, a predetermined thickness of the welded portion is obtained, so that the necessary cross-sectional area of the welded portion is ensured.

Further , after forming the bulging portion in the plate material, the one side plate portion and the other side plate portion of the plate material positioned so as to sandwich the bulging portion are bent in the bulging direction of the bulging portion, and then one end portion of the one side plate portion is curved. and the other end of the other side plate can be brought close to each other. After the one end of the one side plate portion and the other end of the other side plate portion are brought close to each other, the one end portion and the other end portion are coined, so that the shape of the one end portion and the other end portion approximates the shape of the final product. It becomes possible to perform coining processing in stages, and the shape accuracy of the one end and the other end increases.

In addition , the ridge portion of the upper mold is arranged between the one end and the other end of the plate material, and the one end and the other end are abutted against the ridge to perform the coining process. It becomes possible to align the shapes of the part and the other end.

In addition, it becomes possible to carry out coining by surely abutting the one end and the other end against the ridges of the mold on one side and the mold on the other side.

In addition, by bringing the one side plate portion and the other side plate portion into contact with the one side molding surface and the other side molding surface of the upper mold, it is possible to form one end and the other end of the plate material as intended during coining. become.

A second aspect of the invention is characterized in that, in the coining process, the one end portion and the other end portion are butted against one of the protrusions.

According to this configuration, it is possible to make the shape of the one end portion and the other end portion uniform while simplifying the structure of the upper mold .

According to the first invention, when forming a plate into a tubular shape by pressing, one end and the other end of the plate are coined, and then the one end and the other end of the plate are butted and welded. Therefore, the welding quality of the welded portion can be improved and stabilized.

Further , after bending the one side plate portion and the other side plate portion positioned so as to sandwich the bulging portion formed in the plate material, one end portion of the one side plate portion and the other end portion of the other side plate portion are brought close to each other, and then the coining is performed. Since processing can be performed, the shape accuracy of the one end and the other end can be improved, and the welding quality can be further improved.

In addition , since coining can be performed by the ridge portion of the upper mold disposed between the one end and the other end of the plate material, the shape of the one end and the other end can be made uniform, and the welding quality can be improved. can be further enhanced.

In addition, by moving the one side mold and the other side mold toward each other, the one end portion and the other end portion of the plate material can be reliably brought into contact with the ridges for coining.

Also, by bringing the one side plate portion and the other side plate portion of the plate material into contact with the one side molding surface and the other side molding surface of the upper mold, the one end portion and the other end portion of the plate material can be formed as intended.

According to the second invention, the one end and the other end of the plate are abutted against one protrusion of the upper mold. The shape of the part can be aligned .

1 is a perspective view showing part of a torsion beam type suspension device having a torsion beam formed by a manufacturing method according to an embodiment of the present invention; FIG. It is the figure which looked at the torsion beam from the downward direction. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 4B is a cross-sectional view for explaining the procedure of a bulging portion forming step for forming a bulging portion, FIG. 4A showing a mold open state, and FIG. 4B showing a molding completion state; It is a perspective view of a board|plate material after a bulging part formation process. It is the figure which looked at the board|plate material after a trimming process from the downward direction. 7A and 7B are cross-sectional views illustrating the outline of a bending step, in which FIG. 7A shows a mold open state and FIG. 7B shows a molding completed state; It is a perspective view of the board|plate material after a bending process. FIG. 9B is a cross-sectional view for explaining the point of the end bending process, FIG. 9A showing a mold open state, and FIG. 9B showing a molding completed state. It is a perspective view of the board|plate material after an end bending process. FIG. 11A is a cross-sectional view for explaining the point of the coining process, FIG. 11A shows the mold opening state, and FIG. 11B shows the molding completion state. It is a perspective view of the board|plate material after a coining process. 13A and 13B are cross-sectional views for explaining the procedure of the final molding process, in which FIG. 13A shows a mold open state and FIG. 13B shows a molding completed state;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. It should be noted that the following description of preferred embodiments is essentially merely illustrative, and is not intended to limit the invention, its applications, or its uses. In this embodiment, the front side of the vehicle is simply referred to as "front" and the rear side of the vehicle is simply referred to as "rear". The vehicle width direction is also referred to as the left-right direction, where "left" is the left side of the vehicle and "right" is the right side of the vehicle.

FIG. 1 shows part of a torsion beam suspension system 20 having a torsion beam 1 according to an embodiment of the invention. This torsion beam type suspension device 20 is used for a rear wheel suspension device of an automobile as a vehicle. It has a left arm 2 and a right arm 2 extending in directions. A bush 3 is provided at the vehicle front end of each arm 2, and each arm 2 is attached to the vehicle body via the bush 3 so as to be vertically swingable. On the other hand, a wheel support member 4 that supports a wheel is attached to the vehicle rear end of each arm 2 . Further, the arms 2 are each provided with a spring support 5 for receiving a spring (not shown). The structure of the torsion beam type suspension device 20 is not limited to the structure described above, but includes at least the torsion beam 1 and the left and right arms 2, 2, and the torsion beam 1 receives a torsional force due to the swinging of the left and right arms 2, 2. Any structure is acceptable.

The torsion beam 1 is a hollow torsion beam having a closed cross-sectional structure, and is a member that receives a torsional force as described above. In this embodiment, the case where the torsion beam 1 is tubular, that is, is configured by a hollow member will be described. The material of the torsion beam 1 can be, for example, a general structural carbon steel plate (metal plate), but is not limited to this. can be used as a torsion beam 1. Details of the manufacturing method of the torsion beam 1 will be described later.

Both ends (left and right ends) 1a, 1a of the torsion beam 1 in the vehicle width direction are substantially entirely open. Thus, the torsion beam 1 can also be called a cylindrical member or a tubular shape with both ends in the longitudinal direction opened. Both end portions 1a, 1a of the torsion beam 1 are welded to inner wall portions in the width direction of the left arm 2 and the right arm 2, respectively.

As shown in FIG. 2 , the predetermined region of the vehicle width direction intermediate portion of the torsion beam 1 has substantially the same cross-sectional shape, and the predetermined region of the vehicle width direction intermediate portion is the same cross-sectional portion 11 . On the other hand, the left side of the same cross-section portion 11 of the torsion beam 1 is a soft side portion 12 whose cross section gradually expands toward the left end portion of the torsion beam 1, and the right side of the same cross-section portion 11 of the torsion beam 1 is the torsion beam. A rough side portion 12 whose cross section gradually expands toward the right end portion of 1 is formed. The left rough edge portion 12 is continuous with the left end portion of the same cross-sectional portion 11 , and the right rough edge portion 12 is continuous with the right end portion of the same cross-sectional portion 11 . The expansion direction of the cross section of the soft side portion 12 is the vertical direction and the vehicle front-rear direction. Therefore, the cross-sectional shape of the same cross-sectional portion 11 of the torsion beam 1 is smaller than the left end portion and the right end portion of the torsion beam 1 .

As shown in FIG. 3, the lower wall portion of the torsion beam 1 is formed to have a bulging portion 10 that bulges upward and opens downward. The bulging portion 10 is formed continuously in the vehicle width direction on at least the same cross-sectional portion 11 of the torsion beam 1, and can also be called a concave portion. The left side of the bulging portion 10 reaches the left soft side portion 12 , and the right side of the bulging portion 10 reaches the right soft side portion 12 . In each soft side portion 12, the depth of the bulging portion 10 is gradually shallower than that of the same cross-sectional portion 11, and the bulging portion 10 is not formed on both end portions 1a and the lower wall portions in the vicinity thereof. The depth of the bulging portion 10 corresponds to the vertical dimension of the bulging portion 10 . The torsion rigidity of the torsion beam 1 can be optimized by forming a cross-sectional shape similar to a substantially U-shape or a substantially V-shape that opens downward.

The width of the bulging portion 10 corresponds to the dimension of the bulging portion 10 in the front-rear direction. The width of the bulging portion 10 becomes wider as it approaches the open portion of the bulging portion 10 (lower end portion of the bulging portion 10). Therefore, the lower wall portion of the torsion beam 1 has a cross-sectional shape similar to a substantially U-shape or a substantially V-shape in which the portion where the bulging portion 10 is formed opens downward.

The front portion of the upper wall portion of the torsion beam 1 is inclined downward toward the front or curved so as to be located downward toward the front side, and a bulging portion 10 is formed in the lower wall portion of the torsion beam 1. extending along the section. A gap is formed between the inner surface of the front portion and the inner surface of the lower wall portion of the torsion beam 1 where the bulging portion 10 is formed. Further, the rear portion of the upper wall portion of the torsion beam 1 is inclined downward toward the rear or curved downward toward the rear side, forming a bulging portion 10 in the lower wall portion of the torsion beam 1. It extends along the cut part. A gap is formed between the inner surface of the rear portion and the inner surface of the portion of the lower wall portion of the torsion beam 1 where the bulging portion 10 is formed.

The front and rear portions of the upper wall portion of the torsion beam 1 are inclined or curved so that the closer they come to the lower end portion, the longer the separation distance in the front-rear direction, so as to correspond to the cross-sectional shape of the bulging portion 10 . ing. By forming the upper wall portion of the torsion beam 1 in this manner, the cross-sectional shape of the portion of the torsion beam 1 where the bulging portion 10 is formed is substantially open downward as a whole including the upper wall portion and the lower wall portion. It has a cross-sectional shape that approximates a U-shape or a substantially V-shape.

A front bulging portion 1 d is formed between the front portion of the upper wall portion of the torsion beam 1 and the front side of the bulging portion 10 . A rear bulging portion 1 e is formed between the rear portion of the upper wall portion of the torsion beam 1 and the rear side of the bulging portion 10 . Both the front bulging portion 1d and the rear bulging portion 1e are shaped to bulge downward.

At the upper end of the upper wall of the torsion beam 1, one end and the other end of the plate material forming the torsion beam 1 are butt-welded.

(Manufacturing method of torsion beam 1)
Next, a method of manufacturing the torsion beam 1 used in the torsion beam type suspension device 20 will be described. The manufacturing method of the torsion beam 1 is roughly divided into a bulging portion forming process, a trimming process, a bending process, an end bending process, a coining process, a final forming process, and a welding process. By performing these steps, when the plate material 100 is formed into a tubular shape by press working, the one end portion 101a and the other end portion 102a (shown in FIG. 8) of the plate material 100 are coined. It becomes possible to butt and weld the one end 101a and the other end 102a. The method of manufacturing the torsion beam 1 may include steps other than these steps.

4A and 4B are cross-sectional views for explaining the procedure for forming the bulging portion 10. FIG. 4A shows the mold opening state, and FIG. 4B shows the molding completion state. In the bulging portion forming step, a lower bulging portion forming mold 30 and an upper bulging portion forming mold 31 are used. The lower bulging portion forming mold 30 is a fixed mold, and the bulging portion forming upper mold 31 is a movable mold. The bulging portion forming upper mold 31 is driven in the vertical direction (the direction toward and away from the bulging portion forming lower mold 30) by a mold driving device (not shown), and the mold opening position shown in FIG. 4A and the mold opening position shown in FIG. It is switched to the mold closing position (molding completion position) shown in 4B.

The upper surface of the lower mold 30 for forming the bulging portion is used as a molding surface, and a convex surface 30a for molding the bulging portion 10 is formed on this molding surface. The lower surface of the upper mold 31 for forming the bulging portion is used as a molding surface, and a concave surface 31a for molding the bulging portion 10 is formed on this molding surface.

As shown in FIG. 4A, after the upper mold 31 for forming the bulging portion is lifted to the mold opening position, the plate material 100 as the material of the torsion beam 1 is separated from the lower mold 30 for forming the bulging portion and the bulging portion. It is arranged between the upper mold 31 for forming. The plate material 100 is a flat plate, and may be cut to a predetermined size in advance, or may be cut out from a coil material at a torsion beam manufacturing factory. By using a plate as the material for the torsion beam 1, the transportation cost can be reduced compared to the transportation of a pipe. The plate member 100 may be slightly curved or bent.

As shown in FIG. 4B, when the upper bulging portion forming mold 31 is lowered, the convex surface 30a of the lower bulging portion forming mold 30 and the concave surface of the upper bulging portion forming mold 31 are separated. The plate material 100 is molded by 31a. As a result, the bulging portion 10 is formed by bulging the central portion of the plate member 100 in the width direction (horizontal direction in FIG. 4) along the longitudinal direction. After that, the plate member 100 is removed from the mold. FIG. 5 is a top view of the stripped plate material 100 . The bulging portion 10 extends in the longitudinal direction from the center portion in the width direction of the plate member 100 , is formed so as not to reach both ends in the longitudinal direction of the plate member 100 , and further expands toward the ends in the longitudinal direction of the plate member 100 . Height is low.

Then, a trim process is performed. In the trim process, each part of the plate member 100 is cut along cutting lines indicated by phantom lines in FIG. Conventionally known blades can be used for the trimming process. FIG. 6 is a view of the bulging portion 10 of the plate 100 seen from the side opposite to the bulging direction, and shows the shape after cutting. In this trimming process, the widthwise dimensions of the plate material 100 required to form the final product are defined. The widthwise dimension of the plate member 100 corresponds to the circumference of the torsion beam 1, and in this embodiment, the circumference on both sides in the longitudinal direction is longer than the circumference in the central portion in the longitudinal direction. In addition, notch portions 100a, 100a are formed at both longitudinal edge portions of the plate member 100, respectively. These notch portions 100a, 100a are portions that become positioning portions for positioning the plate member 100 in a post-process.

Further, on the plate material 100 subjected to the trimming process, one side plate portion 101 and the other side plate portion 102 are formed so as to sandwich the bulging portion 10 therebetween. The one side plate portion 101 and the other side plate portion 102 extend along the longitudinal direction of the plate member 100 . In addition, since the bulging portion 10 is positioned between the one side plate portion 101 and the other side plate portion 102, the one side plate portion 101 and the other side plate portion 102 are formed apart from each other in the width direction of the plate material 100. become.

After the trimming process, a bending process is performed. FIG. 7 is a cross-sectional view for explaining the procedure of bending the one side plate portion 101 and the other side plate portion 102 of the plate member 100 positioned so as to sandwich the bulging portion 10 in the bulging direction of the bulging portion 10. FIG. 7A shows the mold opening state, and FIG. 7B shows the molding completion state. In the bending process, a lower mold 32 for bending process and an upper mold 33 for bending process are used. The bending process lower mold 32 is a fixed mold, and the bending process upper mold 33 is a movable mold. The bending process upper mold 33 is driven in the vertical direction (the direction toward and away from the bending process lower mold 32) by a mold driving device (not shown), and the mold opening position shown in FIG. 7A and the mold opening position shown in FIG. It is switched to the closed position (molding completion position).

The upper surface of the lower mold 32 for the bending process is used as a molding surface. A lower forming surface 32a for bending is formed. The lower molding surface 32a has a portion that curves the one side plate portion 101 in the direction of swelling of the swelling portion 10 and a portion that curves the other side plate portion 102 in the direction of swelling of the swelling portion 10, These portions are composed of surfaces extending in the vertical direction. In addition, the lower surface of the upper mold 33 for bending process is used as a molding surface. An upper shaping surface 33a is formed for bending to the side. The upper molding surface 33a also has a portion that curves the one side plate portion 101 in the direction in which the bulging portion 10 expands, and a portion that curves the other side plate portion 102 in the direction in which the bulging portion 10 expands. The portion consists of a vertically extending surface.

First, as shown in FIG. 7A, the upper mold 33 for bending process is raised to the mold opening position. Then, the plate material 100 having the shape shown in FIG. 6 is arranged between the lower mold 32 for bending process and the upper mold 33 for bending process.

After that, as shown in FIG. 7B, when the upper bending process upper mold 33 is lowered, the upper molding surface 33a of the upper bending process upper mold 33 and the lower molding surface 32a of the lower bending process lower mold 32 form a mold. One side plate portion 101 and the other side plate portion 102 of the plate member 100 are curved in the direction in which the bulging portion 10 bulges and extend vertically. After that, the plate member 100 is removed from the mold. FIG. 8 is a view of the demolded plate material 100 viewed from the bulging direction of the bulging portion 10, and the one side plate portion 101 and the other side plate portion 102 are bent in a direction approaching each other. An end portion of the one side plate portion 101 is one end portion 101 a of the plate member 100 , and an end portion of the other side plate portion 102 is the other end portion 102 a of the plate member 100 . Note that the order of the trimming process and the bending process may be changed.

After the bending process, an edge bending process is performed. FIG. 9 shows an end portion bending in which one end portion 101a (shown in FIG. 8) of the one side plate portion 101 of the plate material 100 bent in the bending step and the other end portion 102a (shown in FIG. 8) of the other side plate portion 102 are brought closer to each other. 9A and 9B are cross-sectional views for explaining the outline of the process, in which FIG. 9A shows a mold open state and FIG. 9B shows a molding completed state;

In the end bending process, a lower mold 34, a first side mold 35, a second side mold 36, and a pad 37 are used. The lower mold 34 is a stationary mold. The upper surface of the lower mold 34 is formed with an insertion portion 34a that is inserted into the bulging portion 10 of the plate member 100 and bulges upward. The first side mold 35 and the second side mold 36 are arranged on the upper surface of the lower mold 34 so as to sandwich the insertion portion 34a. The first side mold 35 and the second side mold 36 are moved in the horizontal direction by a driving device, a cam structure, etc. (not shown), and move to the mold opening position shown in FIG. 9A and the mold closing position shown in FIG. 9B. position (molding completion position).

The molding surface 35a of the first side mold 35 is a surface for curving one end portion 101a of the one side plate portion 101 in a direction approaching the other end portion 102a of the other side plate portion 102 . Further, the molding surface 36a of the second side mold 36 is a surface for curving the other end portion 102a of the other side plate portion 102 in a direction approaching the one end portion 101a of the one side plate portion 101 .

The pad 37 is a member inserted between the one side plate portion 101 and the other side plate portion 102 of the plate material 100, supports the one side plate portion 101 from the side opposite to the first side mold 35, and supports the other side plate portion. 102 is supported from the side opposite to the second side mold 36 .

First, as shown in FIG. 9A, the pad 37 is raised, and the first side mold 35 and the second side mold 36 are moved away from each other to reach the mold opening position. 8 is placed on the lower mold 34, and the pad 37 is lowered and inserted between the one side plate portion 101 and the other side plate portion . When inserting the pad 37, the plate member 100 should be elastically deformed in the direction in which the one side plate portion 101 and the other side plate portion 102 are separated from each other.

After that, as shown in FIG. 9B , the first side mold 35 is moved to press the molding surface 35 a against the one side plate portion 101 of the plate material 100 . Also, the second side mold 36 is moved to press the molding surface 36 a against the other side plate portion 102 of the plate material 100 . As a result, the one end portion 101a of the one side plate portion 101 and the other end portion 102a of the other side plate portion 102 of the plate member 100 are curved in a direction approaching each other. After that, the plate member 100 is removed from the mold. When removing the pad 37, the plate member 100 should be elastically deformed in the direction in which the one side plate portion 101 and the other side plate portion 102 are separated from each other. FIG. 10 is a view of the stripped plate 100 viewed from the bulging direction of the bulging portion 10. One end portion 101a of one side plate portion 101 and the other end portion 102a of the other side plate portion 102 are bent in a direction approaching each other. It is

After the edge bending process, a coining process is performed. 11A and 11B are cross-sectional views for explaining the point of the coining process for coining the one end portion 101a and the other end portion 102a of the plate material 100. FIG. 11A shows the mold opening state, and FIG. 11B shows the coining completed state. there is

In the coining process, a lower mold 40, a first side mold 41, a second side mold 42, and an upper mold 43 are used. The lower mold 40 is a stationary mold. The lower die 40 is formed with an insertion portion 40a to be inserted into the bulging portion 10 of the plate member 100 so as to bulge upward. The first side mold 41 and the second side mold 42 are arranged so as to sandwich the insertion portion 40a of the lower mold 40 . The first side mold 41 and the second side mold 42 are moved obliquely from the position shown in FIG. 11A to the position shown in FIG. and the mold closing position (molding completion position) shown in FIG. 11B. A side surface 41a of the first side mold 41 is a surface (one-side molding surface) that is pressed against the one-side plate portion 101 . A side surface 42 a of the second side mold 42 is a surface (other side molding surface) that is pressed against the other side plate portion 102 .

Further, the upper mold 43 is driven in the vertical direction (in the direction of contacting and separating from the lower mold 40) by a driving device (not shown), and the mold opening position shown in FIG. 11A and the mold closing position (coining completion position) shown in FIG. position). A protrusion 43 a is provided on the lower surface of the upper mold 43 so as to protrude between one end 101 a and the other end 102 a of the plate member 100 and extend in the longitudinal direction of the plate member 100 . Only one ridge portion 43a is provided, and the end surface of one end portion 101a of the plate member 100 is abutted against one side surface 43b of the ridge portion 43a, and the other side surface 43c of the ridge portion 43a is abutted against the other side surface 43c of the plate member 100. The end surface of the other end portion 102a abuts against it. The side surface 41a of the first side mold 41 and the side surface 42a of the second side mold 42 are surfaces positioned so as to sandwich the ridge portion 43a.

First, as shown in FIG. 11A, the upper mold 43 is raised, and the first side mold 41 and the second side mold 42 are moved away from the lower mold 40 to the mold opening position. do. 10 is placed on the lower mold 40, the upper mold 43 is lowered, and the first side mold 41 and the second side mold 42 are It is moved in a direction approaching the mold 40 . Then, the side surface 41 a of the first side mold 41 is pressed against the one side plate portion 101 , and the side surface 42 a of the second side mold 42 is pressed against the other side plate portion 102 .

As shown in FIG. 11B, when the upper die 43 is completely lowered, the ridge 43a is positioned between the one end 101a and the other end 102a of the plate member 100. As shown in FIG. In this state, the side surface 41a of the first side mold 41 is pressed against the one side plate portion 101, and the one side plate portion 101 is pressed in a direction approaching the other side plate portion 102, thereby pushing the one end portion 101a of the plate material 100. It can abut against one side surface 43b of the protrusion 43a. In addition, by pressing the side surface 42a of the second side mold 42 against the other side plate portion 102 and pressing the other side plate portion 102 in a direction approaching the one side plate portion 101, the other end portion 102a of the plate material 100 is projected. It can abut against the other side surface 43c of the streak portion 43a. Thereby, the one end portion 101a and the other end portion 102a of the plate material 100 can be strongly compressed by the upper mold 43, the first side mold 41 and the second side mold 42 for coining. Since the coining process is a processing method for strongly compressing the material, the springback phenomenon of the one end portion 101a and the other end portion 102a of the plate member 100 can be suppressed. Further, by performing coining processing, the shape of the one end portion 101a and the other end portion 102a of the plate material 100 can be made to match, and a gap when butted against each other can be eliminated or minimized.

After the coining process, the final molding process is performed. 13A and 13B are cross-sectional views for explaining the outline of the final forming process for finalizing the shape of the plate material 100. FIG. 13A shows the mold opening state, and FIG. 13B shows the forming completed state.

In the final molding process, a final molding lower mold 45 and a final molding upper mold 46 are used. The final molding lower mold 45 is a fixed mold, and the final molding upper mold 46 is a movable mold. The final molding upper mold 46 is driven in the vertical direction (the direction toward and away from the final molding lower mold 45) by a mold driving device (not shown), and the mold opening position shown in FIG. 13A and the mold opening position shown in FIG. It is switched to the closed position (molding completion position).

The upper surface of the lower die 45 for final molding is used as a molding surface, and a lower molding surface 45a is formed on this molding surface for forming the bulging portion 10 of the plate material 100 into a final shape. The lower surface of the upper mold 46 for final molding is used as a molding surface, and on this molding surface, an upper molding surface 46a is formed for forming the one side plate portion 101 and the other side plate portion 102 of the plate material 100 into the final shape. It is

First, as shown in FIG. 13A, the final molding upper mold 46 is raised to the mold opening position. Then, the plate material 100 having the shape shown in FIG. 12 is placed on the final molding lower mold 32 .

After that, as shown in FIG. 13B, when the upper final molding die 46 is lowered, the upper molding surface 46a of the upper final molding die 46 and the lower molding surface 45a of the lower final molding die 45 The plate material 100 is formed into a final shape. At this time, although not shown, the plate material 100 is pressed from both sides in the longitudinal direction to shape the end faces. After that, the plate member 100 is removed from the mold.

After the final forming process, a welding process is performed. In the welding process, arc welding is performed while the one end portion 101a and the other end portion 102a of the plate material 100 are butted against each other. Since one end portion 101a and the other end portion 102a of the plate member 100 are coined in advance, warping of the plate member 100 due to springback is suppressed, and the shapes of the butted portion of the one end portion 101a and the other end portion 102a match each other. . After that, the one end portion 101a and the other end portion 102a of the plate material 100 are butted and welded together, thereby making it difficult to form a gap between the one end portion 101a and the other end portion 102a. As a result, a predetermined thickness of the welded portion is obtained, so that the necessary cross-sectional area of the welded portion is ensured.

(Action and effect of the embodiment)
As described above, according to the torsion beam manufacturing method according to this embodiment, when forming the plate material 100 into a tubular shape by press working, the one end portion 101a and the other end portion 102a of the plate material 100 are coined, and then, Since the one end portion 101a and the other end portion 102a of the plate member 100 are butt-welded, the welding quality of the welded portion can be improved and stabilized.

After bending the one side plate portion 101 and the other side plate portion 102 so as to sandwich the bulging portion 10 formed in the plate material 100, the one end portion 101a of the one side plate portion 101 and the other end portion 102a of the other side plate portion 102 are joined together. Since the coining process can be performed after bringing them closer together, the shape accuracy of the one end portion 101a and the other end portion 102a can be improved, and the welding quality can be further improved.

The above-described embodiments are merely examples in all respects and should not be construed in a restrictive manner. Furthermore, all modifications and changes within the equivalent range of claims are within the scope of the present invention.

INDUSTRIAL APPLICABILITY As described above, the method of manufacturing a torsion beam according to the present invention can be used, for example, when manufacturing a torsion beam used in a torsion beam type suspension device for a vehicle.

1 torsion beam 2 arm 10 bulging portion 20 torsion beam type suspension device 100 plate member 101 one side plate portion 101a one end portion 102 other side plate portion 102a other end portion

Claims (2)

In a method for manufacturing a torsion beam used in a torsion beam type suspension device for a vehicle,
a bulging portion forming step of forming a bulging portion by bulging a widthwise central portion of the plate material along the longitudinal direction; Pressing including a bending step of bending the bulging portion in a bulging direction, and an end portion bending step of bringing the curved one end portion of the one side plate portion closer to the other end portion of the other side plate portion. When forming the plate material into a tubular shape by, after the end bending step, coining one end and the other end of the plate material,
In the coining process, the one side plate portion is pushed in a direction approaching the other side plate portion by a first side mold, and the other side plate portion is pushed in a direction approaching the one side plate portion by a second side mold. By abutting the one end and the other end against a ridge provided on the upper mold so as to protrude between the one end and the other end and extend in the longitudinal direction,
A method for manufacturing a torsion beam, characterized in that, after the coining process, one end and the other end of the plate material are butted and welded. In the method of manufacturing a torsion beam according to claim 1 ,
The method of manufacturing a torsion beam, wherein in the coining process, the one end portion and the other end portion are abutted against one of the ridges.

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