JP2020069495A - Molding method for press molded product - Google Patents

Abstract

To reduce time and effort in modifying a shape of a trim product to facilitate increase in thickness of a tubular component and reduce costs.SOLUTION: In the molding method for a press molded product in which a work-piece 2 made of a metal plate is subjected to bending-molding to butt upper ends 12d thereof to each other, so that a tabular component 1 curved in a direction crossing a longitudinal direction is subjected to press molding, rectangular heat marks 50 are formed, at equal intervals in the longitudinal direction of the tubular component 1, at an end part side of a flange part 14 of a drawn product 3 and at a position corresponding to a butted part 1a side in the tubular component 1, so that the heat marks 50 evaluate a state of the butted part 1a.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for forming a tubular press-formed product.

  As a method of molding a tubular part having a circular cross section, a trim product cut into a predetermined shape is press-molded by a U-bending die to form an intermediate molded product having a U-shaped cross section, and then the intermediate molded product is subjected to O A so-called UO bending method is known in which press molding is performed with a bending mold, and ends of an intermediate molded product are butted against each other to form a tube (for example, refer to Patent Document 1 below).

JP, 2014-4626, A

  As the above-mentioned O-bending step, as shown in FIGS. 4A to 4E, for example, an intermediate molded product 5 obtained by processing a flat plate-shaped work by U-bending or the like is set in the lower mold 32. Then, by lowering and pressing the upper die 31 against the intermediate molded product 5, the shoulder bending portion 12a of the intermediate molded product 5 is curved, and the upper ends 12d are abutted against each other {Fig. 4 (A) to Fig. 4 ( See C)}. From this state, the upper mold 31 is further pressed against the intermediate molded product 5 to generate internal stress due to the abutment of the upper ends 12d. Then, due to this internal stress, the shoulder bending portion 12a is stuck to the molding surface 31a of the upper die 31, and the cross section of the intermediate molded product 5 can be molded into the tubular part 1 along the molding surface 3a {FIG. D) to FIG. 4E}.

  In the above-mentioned O-bending, in order to stretch the shoulder bending portion to the upper mold and accurately shape each cross section of the work into a desired tubular shape, the end portions are appropriate in each cross section in the longitudinal direction of the tubular part. It is important to be matched with.

  For this reason, work is performed to improve the accuracy of butting the ends of the tubular parts. Specifically, by evaluating the gap between the ends of the prototype tubular part and the state of the butting, and correcting the shape of the trim product, the accuracy of the butting of the ends is improved, and the molding accuracy of the tubular part is improved. Work is done.

  However, when the abutting portion is curved in a direction intersecting the longitudinal direction of the tubular component (for example, see the abutting portion 1a of the tubular component 1 in FIG. 1A), the end of the trim product forming the abutting portion is Since each bending step expands and contracts along the longitudinal direction, even if a location where a gap is created in the butted portion of the tubular part after molding is found, this location corresponds to which part of the trim product I didn't know what it was, and it was difficult to properly correct the shape of the trim item. Therefore, it is necessary to repeat the cycle of forming the tubular part-> checking the butted part-> correcting the trim product-> forming the tubular part again, resulting in a high manufacturing cost.

  Under such circumstances, it is an object of the present invention to facilitate the manufacturing of the tubular component and reduce the cost by reducing the labor of correcting the shape of the work.

  MEANS TO SOLVE THE PROBLEM In order to solve the above-mentioned subject, this invention bend-molds the workpiece which consists of a metal plate, and press-molds for press-molding the tubular component curved in the direction which intersects with a longitudinal direction by abutting end parts. A method of molding an article, characterized in that a marking is formed at a predetermined position on the end side of the work before bending.

  According to the present invention, the positional relationship between the abutting portions of the end portions can be made to correspond to each other before and after bending by the marking formed in advance on the end portion side of the work. Therefore, since the end shape can be easily corrected, the accuracy of butting the end portions at the time of O-bending can be improved, and the number of corrections can be reduced.

  In addition, by comparing the shapes of the markings before and after bending, it is possible to visually confirm the deformation direction of the end-side member of the tubular part and to quantitatively evaluate the amount of deformation. The shape of the part can be easily modified.

  ADVANTAGE OF THE INVENTION According to this invention, the effort of the correction | amendment of the shape of a workpiece | work can be reduced, manufacture of a tubular component can be facilitated, and manufacturing cost can be reduced.

(A) is a perspective view of a tubular component, (B) is a plan view thereof, and (C) is a side view thereof. (A)-(F) is sectional drawing which shows the procedure of the molding method of a tubular component. (A)-(D) is sectional drawing which shows an intermediate bending process. (A)-(E) is sectional drawing which shows an O bending process, and shows the shape change of the intermediate molded product in the XX cross section of FIG. 1 (B). It is a figure which shows the marking applied to the cut part of a flange part. It is a top view of a tubular part in the state where marking was given. It is a figure which shows the change of the marking before and behind bending.

  Embodiments of the present invention will be described below with reference to the drawings.

  In this embodiment, a method of forming the tubular part (press-formed product) 1 shown in FIG. 1 by press forming is shown. The tubular component 1 is formed by abutting the ends of metal plates to form a tubular shape. In the following description, for convenience, the side where the abutting portion 1a of the tubular component 1 is located is the upper side and the opposite side is the lower side, and the direction orthogonal to the longitudinal direction and the vertical direction of the tubular component 1 is the width direction.

  The tubular part 1 has a modified cross section (non-circular cross section). As shown in FIG. 1 (A), the tubular component 1 of this embodiment has a substantially rectangular cross section, and the cross sectional shape changes in the longitudinal direction. Specifically, the opening on the one end side of the tubular component 1 forms a substantially circular shape in which the vertical dimension and the width dimension are substantially equal, and the opening on the other end side of the tubular component 1 is larger than the vertical dimension. It has a flat shape with a large dimension in the width direction. The longitudinal intermediate portion of the tubular component 1 is smoothly continuous while gradually changing its cross-sectional shape from one end to the other end. The tubular component 1 has a bottom portion 1b, a pair of side portions 1c rising upward from both ends in the width direction of the bottom portion 1b, and a pair of upper portions 1d extending inward in the width direction from the upper ends of the pair of side portions 1c. The end portions of the pair of upper portions 1d are butted against each other to form the butted portion 1a. A bent portion (hereinafter referred to as "bottom bent portion 1e") is provided at a boundary between the bottom portion 1b and each side portion 1c, and a bent portion (hereinafter, referred to as "bottom bent portion 1e") is provided at a boundary between each side portion 1c and each upper portion 1d. The shoulder bent portion 1f ") is provided. The tubular component 1 of this embodiment is curved in a direction intersecting the longitudinal direction (vertical direction and width direction), and specifically, shown in a plan view in FIG. 1 (B) and in FIG. 1 (C). It is curved in any of the side views.

  As shown in FIG. 2, the work 2 of the present embodiment is subjected to a drawing process, a marking process, a cutting process, a U bending process, an intermediate bending process, an O bending process, and a welding process, so that the work 2 is a flat plate. The tubular component 1 is finally molded from the state through each intermediate molded product. It should be noted that FIG. 2 shows only the shape change in the vicinity of the opening on the other end side of the tubular component 1 which has a flat shape.

  In the drawing step, the flat work 2 shown in FIG. 2 (A) is pressed against a drawing die (not shown) to form a drawn product 3 as shown in FIG. 2 (B). The draw-formed product 3 has 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 flange portion 14 extending from both ends of each vertical wall portion 12 in the width direction. .. A bottom bent portion 13 is provided at the boundary between the bottom portion 11 and each vertical wall portion 12. The shape of the lower part (bottom 11 and bottom bend 13) of the draw-formed product 3 is substantially the same as the shape of the lower part (bottom 1b and bottom bend 1e) of the tubular part 1 of the finished product. That is, the bottom portion 11 and the bottom bending portion 13 of the draw-formed product 3 have different cross-sectional shapes in the longitudinal direction and are curved in both plan view and side view.

  In the marking step, heat marks to be described later are applied in the longitudinal direction of each flange portion 14. In the cutting step, as shown in FIG. 2C, the end portion side of each flange portion 14 is cut into a desired length along the longitudinal direction (the front and back direction of the drawing sheet) by laser processing, and trimmed. Form item 4.

  In the U-bending process, the flange portion 14 of the trim product 4 is pressed by a U-bending die (not shown) to be bent and formed on the vertical wall portion 12 side. As a result, as shown in FIG. 2D, an intermediate molded product 5 having a substantially U-shaped cross section is obtained. The intermediate molded product 5 has 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 bottom bent portion 13.

  In the intermediate bending step, the intermediate molded product 5 is pressed to form the shoulder bent portion 12a on the vertical wall portion 12 of the intermediate molded product 5. As shown in FIG. 3, an intermediate bending die 20 for performing an intermediate bending step on the intermediate molded product 5 is composed of an upper die 21 and a lower die 22 that can approach and separate from each other. In the present embodiment, the lower mold 22 is a fixed mold, and the upper mold 21 is a movable mold that is moved up and down by a driving unit (not shown). It should be noted that FIG. 3 shows only the shape change of the portion of the intermediate molded product 5 corresponding to the vicinity of the opening on the other end side having the flat shape.

  The upper mold 21 is provided below each inclined surface 21a, and a pair of inclined surfaces 21a inclined toward each other as it goes upward, a pair of locking surfaces 21b extending downward from the upper end of each inclined surface 21a. And a pair of shoulder bending portion forming surfaces 21c. The pair of locking surfaces 21b is provided on a locking portion 21d that is provided integrally with or separately from the main body portion 21e of the upper die 21. In the illustrated example, the main body portion 21e and the locking portion 21d are provided separately. The shoulder bending portion forming surface 21c is smoothly continuous with the lower end of the inclined surface 21a. The lower mold 22 is provided with a recess 22a in which the intermediate molded product 5 is set. The recess 22a has the same shape as the lower portion (the bottom portion 11 and the bottom bent portion 13) of the intermediate molded product 5.

  In the intermediate bending step, first, as shown in FIG. 3A, the bottom portion 11 of the intermediate molded product 5 is set in the recess 22a of the lower mold 22. Then, by lowering the upper mold 21, and pushing the upper ends 12d of the pair of vertical wall portions 12 of the intermediate molded product 5 downward by the upper mold 21, as shown in FIG. The upper end 12d of 12 is guided inward in the width direction along the inclined surface 21a of the upper die 21, the pair of vertical wall portions 12 incline inward in the width direction, and the upper end 12d abuts on the locking surface 21b of the upper die 21. As a result, the upper ends 12d of the pair of vertical wall portions 12 are restricted from moving further inward in the width direction (sides closer to each other) in a state where the upper ends 12d are separated from each other in the width direction. When the upper mold 21 is further lowered in this state, the vertical wall portion 12 is compressed in the longitudinal direction to cause buckling, and the middle portion of the vertical wall portion 12 bulges outward (see FIG. 3 (C)). }. When the upper die 21 is further lowered, the bulging portion of the vertical wall portion 12 is pressed against the shoulder bending portion forming surface 21c of the upper die 21, thereby forming the shoulder bending portion 12a in the middle portion of the vertical wall portion 12. {See FIG. 3D}.

  As shown in FIG. 2 (E), in the pair of vertical wall portions 12 of the thus-formed intermediate molded product 5, shoulder bending portions 12a, side portions 12b extending downward from the shoulder bending portions 12a, and shoulder bending portions are formed. An inclined portion 12c extending obliquely upward from 12a is provided. The shoulder bending portion 12a has the same shape as a part of the shoulder bending portion 1f of the finished tubular component 1, and in the illustrated example, has an arc shape having the same curvature as the shoulder bending portion 1f of the tubular component 1. ..

  In the O-bending process, the intermediate molded product 5 that has been subjected to the intermediate bending process is further pressed, the ends of the intermediate molded product 5 are abutted against each other, and the tubular component 1 is molded {see FIG. 2 (F)}. As shown in FIG. 4, an O-bending mold 30 for performing an O-bending process on the intermediate molded product 5 is composed of an upper mold 31 and a lower mold 32 that can approach and separate from each other. In the illustrated example, the lower mold 32 is a fixed mold, and the upper mold 31 is a movable mold that is moved up and down by a driving unit (not shown). The lower die 32 is provided with a recess 32a for setting the bottom portion 11 of the intermediate molded product 5. The upper die 31 is provided with a molding surface 31a. In the cross section shown in FIG. 4, the molding surface 31a of the upper die 31 has the same shape as the upper portion (the upper portion 1d and the shoulder bending portion 1f) of the tubular component 1 which is the finished product.

  As an example, a change in shape of the intermediate molded product 5 due to O-bending in the XX cross section of FIG. 1B will be described with reference to FIG. When the upper mold 31 is lowered after setting the intermediate molded product 5 in the recess 32a of the lower mold 32, the molding surface 31a of the upper mold 31 comes into contact with the upper end 12d of the vertical wall portion 12 of the intermediate molded product 5 (FIG. 4). See (A)}. When the upper mold 31 is further lowered, the upper end 12d of the vertical wall portion 12 of the intermediate molded product 5 is pushed downward by the upper mold 31, and the shoulder bending portion 12a of the intermediate molded product 5 is further bent, so that the vertical wall portion 12 is formed. The upper ends 12d of the two abut each other {see FIGS. 4B and 4C}. When the upper die 31 is further lowered, the shoulder bending portion 12a of the vertical wall portion 12 is further bent due to internal stress generated by the abutting of the upper ends 12d, and the upper die 31 is deformed so as to approach the forming surface 31a of the upper die 31 to cause bottom death. Immediately before the point, the end regions P of the intermediate molded product 5 become substantially parallel to each other {see FIG. 4 (D)}. Then, by lowering the upper die 31 to the bottom dead center, the entire vertical wall portion 12 is pressed against the molding surface 31a of the upper die 31 in a state where the end portions of the vertical wall portion 12 are stretched to each other, and the tubular component 1 is molded {see FIG. 4 (E)}. Then, the tubular part 1 is completed by welding the butted portion 1a.

  By the way, in the present embodiment, the draw-formed product 3 is marked in the marking step. Specifically, after the drawing process shown in FIG. 2B, a heat mark 50 as a marking is applied as shown in FIG. 5A. The heat mark 50 is formed by continuously forming rectangular shapes alternately projecting on the respective sides so as to cross the cutting line X. In the present embodiment, the width of each rectangular portion of the heat mark 50 is about 10 mm. Set at equal intervals. Note that, in FIG. 5, the cutting line X is described as a substantially horizontal line for convenience, but the cutting line X is not necessarily horizontal, and each cutting position is changed depending on a necessary cutting length at each position in the longitudinal direction (the left-right direction in the drawing). It is determined.

  Then, both ends of the draw-formed product 3 are cut along the cutting line X by the laser processing machine to form the trim product 4 (see FIG. 2C). As a result, as shown in FIG. 5B, substantially rectangular heat marks 50 having the same width are arranged at equal intervals on the end side of the flange portion 14 of the trim product 4.

  The heat mark 50 is formed by irradiating the surface of the flange portion 14 with a laser in a state where the output of the laser processing machine is reduced, and the flange portion 14 provided on both sides in the width direction of the draw-formed product 3 (FIG. 2). (See (B)). By forming the heat mark 50 as a continuous line portion formed so as to cross the cutting line X, the heat mark 50 can be formed by one laser irradiation, and the workability thereof is improved.

  Then, when the tubular component 1 is molded through the above-described bending steps {see FIG. 2 (D) to FIG. 2 (F)}, as shown in FIG. 6, along the abutting portion 1a along the respective upper portions 1d. , A plurality of heat marks 50 are arranged.

  The abutting portion 1a extends in the longitudinal direction of the tubular component 1 and is curved in each direction intersecting the longitudinal direction {vertical direction and width direction, see FIG. 1B and FIG. 1C}. That is, from the state of the trim product 4 (hereinafter, this state is also simply referred to as before bending), the upper end 12d side is curved and formed in these directions by performing each bending process (hereinafter, this state is simply bent). (Also referred to as after molding), the tubular component 1 is molded.

  By arranging the plurality of heat marks 50 along the abutting portion 1a, the positional relationship between the two in the abutting portion 1a can be made to correspond between before bending and after bending, and the shape of the trim product 4 is changed. Can be corrected exactly. For example, as shown in the enlarged view of FIG. 6, when it is confirmed that there is a gap in the abutting portion 1a at the position corresponding to the third heat mark 50 from the right, the drawing process of the drawn molded product 3 is performed in the cutting step. In the longitudinal direction, reduce the cutting length at the position corresponding to the third heat mark 50 from the right, that is, increase the width of the corresponding portion of the flange portion 14 of the trim product 4 and close the gap of the butting portion 1a. You can As described above, in the present embodiment, by using the heat mark 50 as a reference, it is possible to accurately set the correction portion of the shape of the trim product 4, reduce the number of corrections, and at the same time, to correct the tubular component 1. The molding accuracy can be improved.

  As in the present embodiment, as the marking, by forming the heat marks 50 of equal width at equal intervals on the end side of the flange portion 14 (see FIG. 5 (B)), before and after bending. The positional relationship can be easily taken.

  Further, it is possible to visually confirm the extending direction and the length of the metal material from the shape of the heat mark 50 after the bending. For example, as shown in FIG. 7, when the heat mark 50 (see left side in FIG. 7), which was square before bending, is transformed into a parallelogram shape (see right side in FIG. 7) after bending, the metal material is It can be seen that in this part, the image is stretched to the right in the figure. Then, by confirming the shape of each heat mark 50 formed along the longitudinal direction of the tubular component 1, the deformation direction of the material at each position in the longitudinal direction of the tubular component 1 can be confirmed. Further, by measuring the width of the heat mark 50 after bending, it is possible to know whether the metal material is expanded or contracted by bending, and the expansion / contraction amount can be quantitatively evaluated. For example, if the width A1 of the heat mark 50 before bending is 10 mm, while the width A2 of the heat mark 50 after bending is 12 mm, this portion of the metal material is only 2 mm by bending. You can see that it has been stretched. It is also possible to evaluate a portion where cracking of the metal material is likely to occur depending on the magnitude of the deformation amount.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

  The marking formed on the work is not limited to the heat mark formed by laser processing as in the present embodiment, but marking may be performed by cutting, or a sealing material may be attached. Further, the shape of the heat mark is not limited to the rectangular shape as shown in FIG. 5 (B), but may be an appropriate shape that allows the positional relationship in the longitudinal direction of the workpiece before and after bending to be matched. Can be adopted.

  In the above embodiment, the heat mark is applied before cutting the work (drawing-molded product 3), but the present invention is not limited to this. The timing of applying the heat mark may be before the upper end 12d (see FIG. 4) of the intermediate molded product 5 is curved and molded in the direction intersecting the longitudinal direction of the tubular component 1. For example, the heat mark is applied after the cutting. It can also be applied.

  In the above embodiment, the U-shaped forming process in the manufacturing process of the tubular component 1 includes the drawing process and the U-bending process, but may include only one of them. For example, the flat plate-shaped work 2 {see FIG. 2 (A)} may be molded into a U-shaped intermediate molded product 5 by a U-bending process {see FIG. 2 (D)}. Alternatively, the U-bending step may be omitted, and the vertical wall portion 12 having the depth shown in FIG. 2D may be formed by the drawing step. In this case, a cutting step may be provided after the drawing step to cut unnecessary portions of the flange portion and the vertical wall portion 12 to form a U-shape.

  The tubular component 1 to which the present invention is applied is curved in both a plan view and a side view as shown in FIG. 1 (B) and FIG. 1 (C), and the abutting portion 1a extends in the width direction and the vertical direction. It is not limited to a curved shape. That is, the present invention is applicable if the tubular component 1 curved in any direction intersecting the longitudinal direction, that is, the abutting portion 1a is curved in any direction intersecting the longitudinal direction. You can

DESCRIPTION OF SYMBOLS 1 Tubular component 1a Butt 1b Bottom 1c Side 1d Top 2 Work 3 Drawing 3 Product 4 Trim 5 Intermediate product 11 Bottom 12 Vertical wall 12d Upper end 13 Bottom bending 14 Flange 21 Upper mold 22 Lower mold 31 Upper mold (One mold)
32 Lower mold (other mold)
50 heat mark (marking)
X cutting line

Claims (1)

A method of forming a press-formed product, comprising bending a workpiece made of a metal plate and abutting the ends thereof together to press-form a tubular part curved in a direction intersecting the longitudinal direction,
A method for forming a press-formed product, characterized in that a marking is formed at a predetermined position on the end side of the work before bending.

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