JP2020163398A - Cylindrical component and manufacturing method for the same - Google Patents

Abstract

To prevent poor welding of butted parts, in forming a cylindrical component by butting edges having recessed portions formed by trimming to each other.SOLUTION: In a trimming step, end parts of a metal plate (a bottom part molded product 3) are cut off in a first cutting step and in a second cutting step respectively, and recessed portions 21a are formed between a first cut line 21 and a second cut line 21 formed in the cutting steps respectively. Subsequently, a bending step is performed so that when end parts of the metal plate (a trimmed product 4) are butted to each other, the recessed portions 21a formed at both end parts do not overlap with each other in an extending direction of the butted parts 7a.SELECTED DRAWING: Figure 9

Description

The present invention relates to a tubular part and a method for manufacturing the same.

Patent Document 1 below discloses a method of forming a tubular part having a circular cross section by a UO bending molding method. Specifically, first, in the U bending step, the metal plate is press-formed into a U-shaped cross section. In the subsequent O-bending step, a metal plate 101 having a U-shaped cross section is set on the lower mold 120 (see FIG. 10 (A)), and the upper mold 110 is lowered to abut the upper ends of the pair of vertical wall portions 101a against each other. (See FIG. 10 (B)). After that, by further lowering the upper mold 110, each vertical wall portion 101a is buckled and curved outward (see FIG. 10C), and pressed against the molding surface of the upper mold 110 to form a cylinder having a circular cross section. The shaped part 130 is molded (see FIG. 10 (D)).

Further, Patent Document 2 below describes a method of molding a tubular part having a different diameter cross section by UO bending. Specifically, between the U-bending step and the O-bending step, an intermediate bending step of forming a bent portion on the vertical wall portion of the work having a U-shaped cross section is provided.

Japanese Unexamined Patent Publication No. 2014-4626 JP-A-2018-161678

When forming a tubular part by UO bending molding, a trimming step of punching a metal plate into a predetermined shape is usually provided before the U bending step. At this time, if the work is large or has a curved shape, trimming may be performed in a plurality of cutting steps. For example, in the first cutting step shown in FIG. 11, both ends of the long side 201 of the rectangular metal plate 200 are punched out with a die 210, and then as shown in FIG. 12, the long side is punched in the second cutting step. By punching out the central portion of 201 with a die 220, the metal plate 200 is cut along the long side 201. In the illustrated example, the recess 202a is provided at the central end of the cutting line 202 obtained by the first cutting step. As a result, even if the position of the punching die 220 with respect to the metal plate 200 is slightly deviated in the width direction of the metal plate 200 (vertical direction in FIG. 12) in the second cutting step, the cutting line 203 of the second cutting step Can be crossed with the edge of the recess 202a of the cutting line 202 in the first cutting step to reliably connect both cutting lines 202 and 203 (see FIG. 13).

In this case, the trimmed metal plate 200 has a recess 202a at the boundary between the cutting lines 202 and 203. When such a metal plate 200 is UO-bent and the long sides of the metal plate 200 are butted against each other as shown in FIG. 14, a gap formed by a pair of recesses 202a is formed in the butted portion. If such a large gap is formed, welding defects may occur when the butt portion is welded in the subsequent welding process.

Therefore, an object of the present invention is to prevent welding defects of the butt portion when forming a tubular part by abutting the edges having recesses formed by trimming.

In order to solve the above problems, the present invention comprises a trimming step of punching a metal plate into a predetermined shape, a bending step of bending the metal plate subjected to the trimming step into a tubular shape and abutting the ends thereof, and the metal plate. It is a method of manufacturing a tubular part having a welding step of welding the abutting portions of the ends of the metal plate, and in the trimming step, the end portion of the metal plate is cut in a plurality of cutting steps. , A recess is formed at the boundary of the cutting line formed in each cutting step, and when the ends of the metal plate are butted against each other in the bending step, the recesses formed at both ends of the butted portion are formed. Provided is a method for manufacturing a tubular part that does not overlap in the extending direction.

Further, in order to solve the above-mentioned problems, the present invention is a tubular part formed by welding the abutting portions of the ends of a metal plate rounded into a tubular shape, and both ends of the metal plate abutting each other. Provided is a tubular component in which recesses are formed in each of the recesses and the recesses are arranged so as not to overlap in the extending direction of the abutting portion.

In this way, by arranging the recesses provided at both ends of the metal plates that abut each other so as not to overlap in the extending direction of the abutting portion, the width of the gap formed in the abutting portion can be maximized. Since it can be suppressed to one piece, welding defects at the butt portion due to a large gap can be prevented.

(A) is a plan view of a tubular part manufactured by the method according to an embodiment of the present invention (viewed from the direction A in FIG. B), and (B) is a side view (from the direction B in FIG. A). (View) and (C) are the same sectional views (CC sectional views of FIG. B). (A) to (G) are diagrams showing the manufacturing process of the tubular part. (A) is a plan view of the bottom molded product (a view seen from the A direction in FIG. B), (B) is a side view (a view seen from the B direction in FIG. A), and (C) is a sectional view (C). It is CC cross-sectional view of FIG. B). It is a top view of a quasi-trim product. It is an enlarged view of the V part of FIG. It is a top view of the trim product. (A) to (D) are cross-sectional views showing the procedure of the intermediate bending step. (A) to (C) are cross-sectional views showing the procedure of the O bending process. It is a top view of the O bending molded product. (A) to (D) are sectional views of the O bending process in the conventional UO bending molding. It is a top view which shows the state of performing trimming (the first cutting step) on a metal plate. It is a top view which shows the state of performing trimming (second cutting step) on a metal plate. It is a top view of the metal plate after trimming. FIG. 3 is a plan view showing a state in which the metal plate of FIG. 13 is bent and the ends are butted against each other.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In this embodiment, the manufacturing method of the tubular part 1 shown in FIG. 1 is shown. The tubular component 1 is used as the left and right trailing arms of the rear suspension of the vehicle. The tubular part 1 has a deformed cross section (non-circular cross section), and in the present embodiment, the cross-sectional shape of the tubular part 1 changes in the longitudinal direction. Further, the tubular component 1 is curved in the longitudinal direction, and in the illustrated example, it is curved in both the plan view shown in FIG. 1 (A) and the side view shown in FIG. 1 (B). The tubular component 1 is formed by bending a metal plate into a tubular shape, abutting the ends thereof, and joining the abutting portions 1a with a welded portion 1g. In the following description, for convenience, the side where the butt portion 1a of the tubular part 1 is located is referred to as an upper side, and the opposite side is referred to as a lower side.

As shown in FIG. 1C, the tubular component 1 is composed of a bottom portion 1b, a pair of side portions 1c rising upward from both ends in the width direction (left-right direction in the figure) of the bottom portion 1b, and a pair of side portions 1c. It has a pair of upper parts 1d extending inward in the width direction from the upper end. The butt portion 1a in which the ends of the pair of upper portions 1d are butted against each other is joined by the welded portion 1g. A bent portion (hereinafter referred to as “bottom bent portion 1e”) is provided at the boundary between the bottom portion 1b and each side portion 1c, and a bent portion (hereinafter referred to as “bending portion”) is provided at the boundary between each side portion 1c and each upper portion 1d. Shoulder bending portion 1f ”) is provided.

As shown in FIG. 2, the tubular component 1 has a bottom forming step of forming a bottom on a flat metal plate 2, a trimming step of trimming the bottom molded product 3, and a U bending step of forming a U bend on the trim product 4. , U-bending molded product 5 is subjected to an intermediate bending step, an intermediate bending molded product 6 is subjected to an O-bending step, and an O-bending molded product 7 is welded.

In the bottom molding step, the flat metal plate 2 is press-molded (draw-molded) with a mold to form the bottom-molded product 3 shown in FIG. The bottom molded product 3 includes a bottom portion 11, a pair of vertical wall portions 12 rising upward from both ends in the width direction of the bottom portion 11, and a pair of flange portions 13 extending outward in the width direction from the upper ends of the pair of vertical wall portions 12. Have. A bottom bent portion 14 is provided at the boundary between the bottom portion 11 and each vertical wall portion 12. The shape of the lower portion (bottom portion 11 and bottom bent portion 14) of the bottom molded product 3 is substantially the same as the shape of the lower portion (bottom portion 1b and bottom bent portion 1e) of the tubular part 1 of the finished product.

In the trimming step, the pair of flange portions 13 of the bottom molded product 3 are cut along a cutting line extending in the longitudinal direction. In the present embodiment, as shown in FIG. 3B, the flange portion 13 is not flat, and both ends in the longitudinal direction are curved upward. Since the cutting line provided on the flange portion 13 curved in this way cannot be punched in its entire length at one time, it is cut in a plurality of cutting steps (twice in the illustrated example) in different punching directions. Specifically, a first cutting step of cutting both ends in the longitudinal direction of the flange portion 13 and a second cutting step of cutting the central region of the flange portion 13 are performed.

In the first cutting step, unnecessary portions 13a and 13b shown by scattered points in FIG. 3A are removed by punching both ends in the longitudinal direction of the flange portion 13 with a first cutting die. Specifically, the first cutting die has an upper die that moves up and down along the press direction P shown in FIG. 3 (B), and the upper die has an angle α on one side with respect to the press direction P. A die M1 that can move along the inclined direction Q1 and a die M2 that can move along the direction Q2 that is inclined by an angle β on the opposite side of the press direction P are provided. When the upper die is lowered, the die M1 and M2 punch the flange portion 13 along the Q1 and Q2 directions, respectively, via the cam mechanism to remove unnecessary portions 13a and 13b. As a result, the quasi-trim product 4'shown in FIG. 4 is formed. A cutting line 21 along the longitudinal direction is formed on the flange portion 13 of the semi-trim product 4'by the punching dies M1 and M2. A recess 21a is provided at the end of the cutting line 21 on the central side in the longitudinal direction.

In the second cutting step, the central region of the flange portion 13 of the semi-trim product 4'is punched out by the second cutting die M3 to remove the unnecessary portion 13c shown by the scattered points in FIG. 4 and the trim product 4 (FIG. 6) is formed. At this time, as shown in FIG. 5, since the recess 21a is formed at the end of the cutting line 21, even if the second cutting die M3 is slightly displaced in the width direction (vertical direction in the drawing), the second cutting die M3 is second. The cutting edge M30 of the cutting die M3 can be crossed with the edge of the recess 21a of the cutting line 21. As a result, as shown in FIG. 6, the cutting line 21 formed in the first cutting step and the cutting line 22 formed in the second cutting step can be reliably connected.

By the way, in the trimming step, if the punching direction of the die is greatly inclined with respect to the normal direction of the surface punched by the die (flange portion 13 in this embodiment), the cutting quality cannot be stabilized. .. Therefore, the angle between the punching direction of each die and the normal direction of the surface cut by the die must be within a predetermined range (for example, within 10 °). For example, in the flange portion 13 of FIG. 3B, the range that can be punched by the punching dies M1 and M2 of the first cutting die is indicated by R (M1) and R (M2), and the second cutting die M3 is used. The range of the flange portion 13 that can be cut is indicated by R (M3). In this case, the cuttable ranges R (M1) and R (M2) of the first cutting die M1 and M2 and the cuttable range R (M3) of the second cutting die M3 overlap each other. The shape and punching direction of each die are set, and the recesses 21a (that is, the cutting line 21 by the first cutting die and the cutting line by the second cutting die) formed in the flange portion 13 are formed in these overlapping regions R1 and R2. (Boundary with 22) is provided (see FIG. 6).

At this time, if the recesses 21a provided in the pair of flange portions 13 are all provided at the optimum positions (for example, the center in the longitudinal direction of the overlapping regions R1 and R2), the ends of the workpieces are butted against each other in the subsequent O bending step. At that time, the recesses 21a may overlap each other, and a gap having a width equivalent to two recesses 21a may be formed in the abutting portion 7a of the O-bent molded product 7. Therefore, by shifting at least one of the recesses 21a provided in the pair of flange portions 13 from the optimum position, the position of the recesses 21a in the butt portion 7a of the O-bent molded product 7 can be shifted in the longitudinal direction. In the present embodiment, as shown in FIG. 6, recesses 21a of both flange portions 13 arranged in the overlapping regions R1 and R2 are arranged on both sides of the optimum positions B1 and B2.

In the U-bending step, the trim product 4 shown in FIG. 6 is pressed with a U-bending die (not shown) to form a U-bent molded product 5 (see FIG. 2D) having a substantially U-shaped cross section. Specifically, the flange portion 13 of the trim product 4 is raised by bending molding and arranged on a substantially extended surface of the vertical wall portion 12. Hereinafter, the vertical wall portion 12 and the flange portion 13 arranged on the extension surface thereof are collectively referred to as a “vertical wall portion 12”.

In the intermediate bending step, the U-bending molded product 5 is pressed to form the shoulder bending portion 12a on the vertical wall portion 12 to form the intermediate bending molded product 6 (see FIG. 2 (E)). Specifically, first, as shown in FIG. 7A, the bottom portion 11 of the U-bent molded product 5 is set in the recess 42a of the lower mold 42. Then, by lowering the upper die 41 and pushing the upper end 12d of the pair of vertical wall portions 12 of the U-bent molded product 5 downward with the upper die 41, as shown in FIG. 7B, the pair of vertical walls The upper end 12d of the portion 12 is guided inward in the width direction along the inclined surface 41a of the upper mold 41 and abuts on the locking portion 41d provided on the upper mold 41. When the upper die 41 is further lowered in this state, the vertical wall portion 12 is compressed in the length direction to cause buckling, and the intermediate portion of the vertical wall portion 12 bulges outward {see FIG. 7 (C)}. .. When the upper mold 41 is further lowered, the bulging portion of the vertical wall portion 12 is pressed against the molding surface 41c of the upper mold 41, whereby the shoulder bending portion 12a is formed in the intermediate portion of the vertical wall portion 12 {FIG. 7 See (D)}.

In the O-bending step, the intermediate bending-molded product 6 is pressed to form an O-bending molded product 7 (see FIG. 2 (F)) in which the ends are butted against each other. Specifically, first, as shown in FIG. 8A, the intermediate bending molded product 6 is set in the recess 52a of the lower mold 52. Then, when the upper die 51 is lowered, the upper end 12d of the vertical wall portion 12 of the intermediate bending molded product 6 is pushed downward by the upper die 51, so that the shoulder bending portion 12a is further bent and the upper end of the vertical wall portion 12 is bent. The 12d's abut each other (see FIG. 8B). After that, when the upper mold 51 is further lowered, the entire vertical wall portion 12 is pressed against the molding surface 51a of the upper mold 51, and the O-bent molded product 7 is molded {see FIG. 8 (C)}.

Since the ends (long sides) of the trim product 4 shown in FIG. 6 are butted against each other in the O-bent molded product 7, a recess 21a remains in the butted portion 7a between the ends as shown in FIG. .. In the present embodiment, the recesses 21a provided at the ends abutting each other are arranged so as not to overlap in the longitudinal direction (extending direction of the abutting portion 7a). In other words, when the ends of the work (intermediate bending molded product 6) are butted against each other in the O-bending step, the recesses 21a formed in both ends of the work do not overlap in the longitudinal direction. The position is set.

In the welding step, the butt portion 7a of the O-bent molded product 7 shown in FIG. 9 is welded to complete the tubular part 1 shown in FIG. The welded portion 1 g is formed by, for example, arc welding. The welded portions 1g are provided, for example, along the longitudinal direction of the butt portion 1a, and in the illustrated example, they are provided at a plurality of locations separated in the longitudinal direction. The welded portion 1g is formed so as to fill the recess 21a (gap) formed in the butt portion 7a of the O-bent molded product 7. At this time, by providing the recesses 21a by shifting them in the longitudinal direction as described above, the width of the gap formed in the butt portion 7a of the O-bent molded product 7 can be suppressed to one recess 21a at the maximum, which is caused by the gap. Welding defects are prevented.

The present invention is not limited to the above embodiments. Hereinafter, other embodiments of the present invention will be described, but the same points as those of the above embodiments will be omitted.

In the above embodiment, as shown in FIG. 3C, a pair of flange portions 13 extend straight outward in the width direction from the upper end of the vertical wall portion 12 of the bottom molded product 3. Therefore, in the side view shown in FIG. 3B, the flange portion 13 has a curved shape similar to that of the upper end of the vertical wall portion 12. At this time, since the vertical wall portion 12 of the bottom molded product 3 conforms to the shape of the tubular part 1 of the finished product, the shape can hardly be changed. On the other hand, since the flange portion 13 of the bottom molded product 3 is molded in the subsequent U bending step or the like, the degree of freedom in shape is high. For example, in the side view shown in FIG. 3B, if the shape is changed so that the flange portion 13 (particularly the cutting lines 21 and 22) is curved more gently than the vertical wall portion 12 (that is, the curvature is smaller). Since the flange portion 13 can be easily punched out in the trimming step, the design of the cutting die is facilitated.

Further, in the above embodiment, in the trimming step, the case where the end portion of the metal plate (bottom molded product 3) is cut by dividing it into two cutting steps is shown, but the present invention is not limited to this, and the end portion of the metal plate is not limited to this. May be divided into three or more cutting steps to form a recess at the boundary of the cutting line in each cutting step.

Further, the manufacturing process of the tubular part 1 is not limited to the procedure shown in FIG. For example, if there is no particular need, the intermediate bending step may be omitted and the U bending molded product 5 may be subjected to the O bending step. Alternatively, the intermediate bending step may be performed in multiple stages.

Further, in the above embodiments, the case where the tubular component 1 according to the present invention is a trailing arm of a vehicle is shown, but the present invention is not limited to this. For example, the present invention can be applied to a tubular component such as an intermediate beam connecting the left and right trailing arms, a pillar-to-pillar member, or an impact beam of a door.

1 Cylindrical part 1a Butt part 1g Welded part 2 Metal plate 3 Bottom molded product 4 Trim product 4'Semi-trim product 5 U Bending molded product 6 Intermediate bending molded product 7 O Bending molded product 7a Butting part 11 Bottom 12 Vertical wall part 13 Flange 21 Cutting line 21a Recess 22 Cutting line M1, M2 Die (first cutting die)
M3 Second cutting die P Press direction Q1 Drilling die M1 punching direction Q2 Drilling die M2 punching direction

Claims (2)

A trimming step of punching a metal plate into a predetermined shape, a bending step of bending the metal plate subjected to the trimming step into a tubular shape and abutting the ends, and welding of welding the abutting portions of the ends of the metal plate. A method for manufacturing a tubular part having a process.
In the trimming step, the end portion of the metal plate is cut by dividing it into a plurality of cutting steps, and a recess is formed at the boundary of the cutting line formed in each cutting step.
A method for manufacturing a tubular part so that when the ends of the metal plate are butted against each other in the bending step, the recesses formed at both ends do not overlap in the extending direction of the butted portion. It is a tubular part made by welding the abutment between the ends of a metal plate rolled into a tubular shape.
Recesses are formed at both ends of the metal plates that abut against each other.
A tubular component in which the recesses are arranged so as not to overlap in the extending direction of the abutting portion.

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