JP2017030038A - Method for manufacturing press-formed product and press-forming mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a press-formed product having a ridge line part without generation of defective forming and surface defective property, and a press-forming mold therefor.SOLUTION: A method for manufacturing a press-formed product having a process in which a plate material 10 is prepared, a first press process in which a product part 11 of the plate material 10 is formed into an intermediate shape B, and a second press process in which the intermediate shape B is formed into a target shape A, in which a tip curvature radius r of a sharpest ridge line part 2 and a thickness t of the plate material 10 satisfy the following relation (1): t≤r≤10t, lengths l1, l2 of a border line L1 of the intermediate shape B and a border line L2 of the target shape A and a tip arc length s of the sharpest ridge line part satisfy the relation (2): |l2-l1|≤s/2, and a maximum value hmax and a minimum value hmin of a maximum distance h in a press stroke direction of the border lines L1, L2 satisfy the relation (3): hmax-hmin≤5t.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a press-formed product having a ridge line portion on a design surface, and a press-molding die for manufacturing the press-formed product. Although the technical field of this invention is not specifically limited, For example, it can apply to a motor vehicle member.

  For example, an outer panel for an automobile door is generally produced by press forming a metal plate material. The outer panel is a part that determines the design of an automobile. For example, a design having a ridge line portion with a small radius of curvature called a character line is used. One or a plurality of such ridge lines are present in the outer panel, and furthermore, a concave part formed in the handle attachment site and a design that approaches or interferes with the mainstream, and therefore, advanced press molding technology is required. Yes.

  In Patent Document 1, the first mold is used to pre-form the edge portion at a predetermined position, and other parts are formed into a final shape, and then the second mold is used to finalize the edge portion. A press forming method of a metal plate material to be formed into a shape is disclosed. The edge diameter formed by the first mold is about 2 to 10 times the final shape, and is formed into a predetermined size by two-stage deep drawing.

  Patent Document 2 discloses a press molding method for an outer panel in which a design concave portion extending in the longitudinal direction of the vehicle body is provided in the outer design surface, and a design convex portion such as a character line is provided along the side edge. . Since such design recesses start at the end of molding, the tension from the outer periphery of the panel is not transmitted, and if the tension is set high in order to improve the shape accuracy, the design projections will be broken or misaligned. Occurs. For this reason, in the method of Patent Document 2, the blank outer peripheral portion is sandwiched between the molding auxiliary convex portion and the molding auxiliary concave portion corresponding to the design concave portion at the initial stage of molding, and the blank central portion is previously aligned with the outer design surface. It is bent and deformed.

German Patent Application Publication No. 10201111219 JP 2014-28379 A

  In the outer panel design, the ridge portion is required to be sharp, and the curvature radius of the tip tends to be smaller. In addition, there is a design that emphasizes sharpness by providing a concave curved surface shape called reverse warp at the periphery of the ridge line portion. In that case, it is not easy to form the ridge line portion into a desired sharp shape after preforming a shape including a concave curved surface shape by the method of Patent Document 1, and molding defects such as cracks and wrinkles are likely to occur. In addition, when the concave curved surface shape is formed together with the ridge line portion, surface property defects such as line deviation are likely to occur.

  The line shift is caused by the material of the ridge line portion flowing and deformed in the process of forming the concave curved surface shape of the peripheral edge or the concave portion of the handle attachment portion after the ridge line portion is formed. Such a line shift is more apparent as the radius of curvature at the tip of the ridge line portion is smaller. Moreover, the method of patent document 2 is a countermeasure to the design recessed part which crosses an outer panel, and it was difficult to eliminate the line | wire shift | offset | difference resulting from the concave curved surface shape and concave part near the ridgeline part.

  The present invention has been made in view of such a background, and in press molding of an outer panel or the like having a ridge line portion with a small radius of curvature, due to the ridge line portion and the concavo-convex shape in the vicinity thereof, cracks, wrinkles, line misalignment, etc. An object of the present invention is to provide a method for producing a high-quality press-molded product by preventing the occurrence of molding defects and surface texture defects, and a press mold used for the method.

One aspect of the present invention is a method for producing a press-formed product having a target shape having one or more ridge lines on the design surface,
A step of preparing a plate part for obtaining a product part constituting the press-formed product and a peripheral part surrounding the product part;
A first pressing step of forming the product portion of the plate material into an intermediate shape by press molding;
A second pressing step of forming the intermediate shape into the target shape by press molding,
The tip curvature radius r at the sharpest ridge line portion having the smallest tip curvature radius among the one or more ridge line portions in the target shape, and the thickness t of the plate material are as follows:
Formula (1): t ≦ r ≦ 10t is satisfied,
In the state where the intermediate shape and the target shape are overlapped with the positions of the respective outer peripheral edges being matched, the intermediate shape appears in a cross section perpendicular to the longitudinal direction of the sharpest ridge line portion when viewed from the press stroke direction. About the contour line L1 and the contour line L2 of the target shape,
The length l1 of the contour line L1, the length l2 of the contour line L2, and the tip arc length s in the sharpest ridge line part are:
Formula (2): | l2-l1 | ≦ s / 2 is satisfied,
And, when the maximum distance h in the press stroke direction between the contour line L1 and the contour line L2 is determined in all the cross sections in the entire length range of the sharpest ridge line portion, the maximum value hmax and the minimum value hmin , And the thickness t of the plate material is
In the method for manufacturing a press-formed product, the target shape and the intermediate shape are set so as to satisfy the formula (3): hmax−hmin ≦ 5t.

  Another aspect of the present invention is a press mold used in the first pressing step in the method for manufacturing a press molded product, wherein the press mold has a pair of molding surfaces corresponding to the intermediate shape. It is in.

  According to the method for manufacturing a press-formed product, a product part having a sharpest ridge line part that satisfies the formula (1) and has a radius of curvature of the tip of 10 times or less of the plate thickness is obtained by the first press process and the second press process. By two-stage molding, it can be manufactured while preventing the occurrence of defects during molding. Here, the intermediate shape formed in the first press step and the target shape formed in the second press step are different in the lengths of the contour lines L1 and L2 appearing in the cross section of the sharpest ridge line portion. Smaller is better and can prevent cracking and wrinkling due to insufficient expansion of the plate material or excess meat. Moreover, when it exists in the relationship of the front-end | tip circular arc length s of a sharpest ridgeline part and Formula (2), it can be set as the range which is not visually recognized as a line | wire deviation, suppressing the flow of material.

  Further, the maximum distance h of the contour lines L1 and L2 appearing in the cross section viewed from the press stroke direction corresponds to the forming height in the second pressing step. When the maximum value and the minimum value of the maximum distance h are within the range of the formula (3) in the range of the total length of the sharpest ridge line part, the molding from the intermediate shape to the target shape proceeds uniformly as a whole. Material flow is suppressed. For this reason, the sharpest ridge line portion can be formed well over the entire length, and the formed portion can be prevented from being pulled in at the time of forming around it and causing a line shift.

  Therefore, it is possible to improve the quality of a press-molded product by molding a sharp ridge line part or a product part having a concavo-convex shape without causing molding defects or surface property defects. Such a method for manufacturing a press-molded product can be easily realized by using a press mold having a pair of molding surfaces corresponding to the intermediate shape in the first press step.

  As described above, according to the above manufacturing method, an outer panel having a ridge line portion with a small radius of curvature is press-molded without causing molding defects or surface property defects, and a high-quality press without cracks, wrinkles, or line deviations. A molded product can be obtained. Such a method for manufacturing a press-molded product can be easily realized by using a press mold having a pair of molding surfaces corresponding to the intermediate shape in the first press step.

Schematic for demonstrating the process of preparing a press-molded article and a board | plate material for the manufacture in embodiment. Schematic for demonstrating the 1st press process using the 1st press mold in embodiment. Schematic for demonstrating the 2nd press process using the 2nd press molding die in embodiment. Schematic which shows the state which piled up the product part of the target shape and the product part of intermediate shape in embodiment. The front view which shows the example of the target shape of the product part of a press-formed product in an Example. FIG. 6 is a cross-sectional view taken along the line II of FIG. II-II sectional view taken on the line of FIG. The front view which shows the example of the intermediate shape of the product part of the press-formed product in Example 1. FIG. III-III sectional view taken on the line of FIG. The IV-IV sectional view taken on the line of FIG. Schematic which shows the state which piled up the product part of the target shape of FIG. 6, and the product part of the intermediate shape of FIG. The principal part enlarged view of FIG. Schematic which shows the state which piled up the product part of the target shape of FIG. 7, and the product part of the intermediate shape of FIG. The principal part enlarged view of FIG. In Example 1, the figure which shows the result of having measured the contour line length of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the contour line length of an intermediate | middle shape about the full length of a ridgeline part. In Example 1, the figure which shows the difference of the contour line length of the target shape and intermediate | middle shape in the cross section of the longitudinal direction of a ridgeline part about the full length of a ridgeline part. In Example 1, the figure which shows the result of having measured the minimum value of the curvature radius of the contour line of the target shape in the longitudinal cross section of a ridgeline part, and the contour line of an intermediate shape with the full length of the ridgeline part. In Example 1, the figure which shows the result of having measured the maximum distance of the contour line of the target shape of the target shape of a press stroke direction in the longitudinal cross section of a ridgeline part, and the outline of an intermediate shape with the full length of the ridgeline part. The main part enlarged view which shows the state which piled up the product part of the target shape in the II sectional view of FIG. 5 and the intermediate-shaped product part corresponded in the III-III sectional view of FIG. The main part enlarged view which shows the state which piled up the product part of the target shape in the II-II sectional view of FIG. 5 and the intermediate-shaped product part equivalent to the IV-IV sectional view of FIG. The figure which shows the result of having measured the outline length of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the outline line length of an intermediate | middle shape in the comparative example 1, about the full length of a ridgeline part. The figure which shows the difference of the contour line length of the target shape and intermediate | middle shape in the cross section of the longitudinal direction of a ridgeline part about the full length of a ridgeline part in the comparative example 1. FIG. The figure which shows the result of having measured the minimum value of the curvature radius of the contour line of the target shape in the longitudinal cross section of a ridgeline part, and the contour line of an intermediate shape in the comparative example 1 with the full length of the ridgeline part. The figure which shows the result of having measured the maximum distance of the contour line of the target shape of the target shape of a press stroke direction in a longitudinal direction cross section of a ridgeline part, and the outline of an intermediate shape in the comparative example 1 with the full length of the ridgeline part. The main part enlarged view which shows the state which piled up the product part of the target shape in the II sectional view of FIG. 5 and the intermediate-shaped product part equivalent to the III-III sectional view of FIG. The main part enlarged view which shows the state which piled up the product part of the target shape in the II-II sectional view of FIG. 5 and the intermediate-shaped product part corresponded in the IV-IV sectional view of FIG. The figure which shows the result of having measured the outline length of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the outline line length of an intermediate | middle shape in the comparative example 2, about the full length of a ridgeline part. The figure which shows the difference of the contour line length of the target shape and intermediate | middle shape in the cross section of the longitudinal direction of a ridgeline part about the full length of a ridgeline part in the comparative example 2. FIG. The figure which shows the result of having measured the minimum value of the curvature radius of the contour line of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the contour line of an intermediate shape in the comparative example 2 with the full length of the ridgeline part. The figure which shows the result of having measured the maximum distance of the contour line of the target shape of the press stroke direction in the cross section of the longitudinal direction of a ridgeline part, and the outline of an intermediate shape in the comparative example 2 with the full length of the ridgeline part. The main part enlarged view which shows the state which piled up the product part of the target shape in the II sectional view of FIG. 5 and the intermediate-shaped product part corresponded in the III-III sectional view of FIG. The main part enlarged view which shows the state which piled up the product part of the target shape in the II-II sectional view of FIG. 5 and the intermediate-shaped product part equivalent to the IV-IV sectional view of FIG. The figure which shows the result of having measured the outline length of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the outline line length of an intermediate | middle shape in the comparative example 3, about the full length of a ridgeline part. The figure which shows the difference of the contour line length of the target shape and intermediate | middle shape in the cross section of the longitudinal direction of a ridgeline part about the full length of a ridgeline part in the comparative example 3. The figure which shows the result of having measured the minimum value of the curvature radius of the contour line of the target shape in the cross section of the longitudinal direction of a ridgeline part, and the contour line of an intermediate shape in the comparative example 3 with the full length of the ridgeline part. In Comparative Example 3, the figure which shows the result of having measured the maximum distance of the contour line of the target shape of the press stroke direction in the longitudinal direction cross section of a ridgeline part, and the outline of an intermediate shape with the full length of the ridgeline part. The front view which shows the example of the target shape of the product part of the press molded product in Example 2. FIG. The schematic diagram which shows the state which piled up the product part of the target shape and the product part of intermediate shape in the VV sectional view of FIG. The principal part enlarged view of FIG. The principal part enlarged view which shows the state which piled up the product part of the target shape and the product part of intermediate shape in the VI-VI line cross section of FIG. The front view which shows the example of the target shape of the product part of a press molded product in Example 3. FIG. The front view which shows the example of the target shape of the product part of a press-molded product in Example 4. FIG. The front view which shows the target shape example of the product part of a press-molded product in Example 5. FIG. The principal part enlarged view which shows the state which piled up the product part of the target shape and the product part of intermediate shape in the VII-VII line cross section of FIG.

  Hereinafter, a method for producing a press-molded product and an embodiment according to a press mold will be described with reference to the drawings. The press-formed product has a target shape having one or a plurality of ridge lines on the design surface, and is applied to, for example, an outer panel for automobiles. As shown in FIG. 1, the press-formed product 1 of this embodiment has a target curvature A corresponding to a desired outer panel, and has a small curvature that protrudes to a surface that is a design surface (that is, the upper surface in the figure). A radius ridgeline 2 is provided. The ridge line portion 2 has a linear shape, a curved shape, or an arbitrary linear shape obtained by combining these.

One or a plurality of ridge line portions 2 in the target shape A are, among these ridge line portions 2, the tip curvature radius r in the sharpest ridge line portion having the smallest tip curvature radius and the thickness t of the plate material 10.
Expression (1): t ≦ r ≦ 10t is satisfied.
When the tip curvature radius r of the sharpest ridge line portion is not less than the plate material thickness t and not more than 10 times the plate material thickness t, the ridge line portion 2 has a sharper tip shape and the design is improved.

  Such a press-formed product includes steps shown in FIGS. 1 to 3, that is, a step of preparing a plate material 10 for press molding (hereinafter referred to as a preparation step), and a product portion 11 of the plate material 10 in an intermediate shape B. It is manufactured through a first pressing step for forming and a second pressing step for forming the product part 11 from the intermediate shape B to the target shape A. At this time, by setting a predetermined intermediate shape B with respect to the target shape A, the formability of the sharp ridgeline portion 2 can be improved. Next, details of each step will be described.

  In the preparation step shown in FIG. 1, first, a plate material 10 for obtaining a product part 11 to be a press-formed product 1 and a peripheral part 12 surrounding the product part 11 is prepared. The plate material 10 is a flat metal plate material that is processed into a blank sheet having a predetermined shape corresponding to the target shape A. As the material of the plate member 10, a steel plate or an aluminum alloy plate is preferably used. The thickness t of the plate member 10 is usually preferably in the range of 0.3 mm to 2.5 mm, and varies depending on the material, but the range of 0.5 mm to 2.0 mm is more suitably used as an automobile outer panel material. The The peripheral portion 12 of the plate member 10 is pressed together with the product portion 11 in the first press step of the next step to become a predetermined peripheral shape C.

  As shown in FIG. 2, in the first pressing step, the prepared plate material 10 is press-formed using the first press mold 3, and the product portion 11 of the plate material 10 is formed into an intermediate shape B. The first press mold 3 includes a pair of an upper mold 33 and a lower mold 34 having a pair of molding surfaces 31 and 32 facing each other, and the facing direction (that is, the vertical direction in the figure) is set as the press stroke direction X. The pair of molding surfaces 31 and 32 has a shape corresponding to the intermediate shape B, and has holding surfaces 311 and 321 having a shape corresponding to the peripheral shape C on the outer peripheral portion thereof.

  The first press mold 3 desirably includes a mechanism capable of press-molding the product portion 11 while sandwiching the peripheral portion 12 of the plate material 10 between the pair of holding surfaces 311 and 321. For example, as shown in the drawing, when the holding surface 321 of the lower mold 34 is provided so as to be movable up and down independently of the molding surface 32, the peripheral portion 12 of the plate member 10 is sandwiched in advance between the pair of holding surfaces 311 and 321. Then, by moving the upper mold 31 and the lower mold 32 relative to each other, a shape along the pair of molding surfaces 31 and 32 can be easily provided. The peripheral shape C can be any shape, and here is a shape in which a plurality of irregularities are alternately formed. The peripheral shape C is not limited to such a shape, and may be any shape that does not cause defective molding by reliably holding the peripheral portion 12 of the plate 10 during press molding.

  As shown in FIG. 3, in the second pressing step, the product portion 11 of the plate material 10 molded into the intermediate shape B is further press-molded into the target shape A using the second press molding die 4. The second press mold 4 is composed of a pair of upper mold 43 and lower mold 44 having a pair of molding surfaces 41 and 42 facing each other, and the facing direction (that is, the vertical direction in the figure) is the press stroke direction X. The pair of molding surfaces 41 and 42 has a shape corresponding to the target shape A of the product portion 11.

  In the second pressing step, it is desirable to press-form the product portion 11 without sandwiching the peripheral portion 12 of the plate material 10. In this case, before and after the second pressing step, the peripheral portion 12 of the plate 10 has the same shape (that is, the peripheral shape C), and the molding load can be reduced.

  Here, as described above, when one or more ridge line portions 2 in the target shape A have the sharpest ridge line portions that satisfy the above formula (1), the intermediate shape B in the first pressing step and the second press The target shape A in the process is further set so as to satisfy the following expressions (2) and (3). First, as shown in FIG. 4, the intermediate shape B and the target shape A of the product part 11 are overlapped with the positions of the respective outer peripheral edges being matched. Here, one of the cross sections including an arbitrary apex p of the sharpest ridge line portion and orthogonal to the longitudinal direction of the sharpest ridge line portion when viewed from the press stroke direction X is shown.

Then, for the contour line L1 of the intermediate shape B and the contour line L2 of the target shape A that appear in this cross section, the length L1 of the contour line L1, the length l2 of the contour line L2, and the tip arc length of the sharpest ridge line part s
The contour lines L1 and L2 are determined so as to be in a range satisfying Expression (2): | l2-l1 | ≦ s / 2. The contour lines L1 and L2 are contour lines along the surfaces of the intermediate shape B and the target shape A (that is, the upper surface of the drawing), respectively.

  The second pressing step is a step in which the contour line L1 of the intermediate shape B is formed so as to coincide with the contour line L2 of the target shape A, and the difference between the lengths L1 and L2 of the contour lines L1 and L2 is smaller. Good. In particular, in the target shape A, in the shape having the concavo-convex portion in the vicinity of the ridge line portion 2, if the difference between the lengths L1 and L2 of the contour lines L1 and L2 becomes large, due to the elongation or surplus of the material of the plate material 10 during molding Cracks and wrinkles are likely to occur. Further, line deviation is likely to occur due to the flow of the material of the plate 10. At this time, if the flow of the material is within the range of the tip arc length of the ridge line portion 2, it is considered that the material is not visually recognized as a line shift.

  Therefore, for example, the difference between the lengths L1 and L2 of the contour lines L1 and L2 is set to be equal to or less than the length (that is, s / 2) from the midpoint of the tip arc serving as the sharpest ridge line portion to the edge of the arc. Thus, line deviation can be suppressed. In addition, since the absolute value of the difference between the lengths L1 and L2 of the contour lines L1 and L2 is reduced, cracks due to the elongation of the material of the plate member 10 or wrinkles due to the surplus meat are less likely to occur.

For the contour line L1 of the intermediate shape B and the contour line L2 of the target shape A, the maximum distance h in the press stroke direction between the contour line L1 and the contour line L2 is all cross sections in the range of the entire length of the sharpest ridge line part. , The maximum value hmax and minimum value hmin and the thickness t of the plate 10 are
The contour line L1 and the contour line L2 in each cross section are set so as to satisfy Expression (3): hmax−hmin ≦ 5t.

  Since the maximum distance h between the contour line L1 and the contour line L2 is the press stroke length in each cross section, that is, the molding height, it is preferable that the change is small in all cross sections of the entire length of the sharpest ridge line part, and it is more preferable not to change. preferable. If the change for each cross section is large, the material of the plate 10 flows after contact with the press mold, and line deviation is likely to occur. Therefore, paying attention to the maximum value hmax and the minimum value hmin of the maximum distance h, by setting the contour line L1 of the intermediate shape B so that the difference is not more than 5 times the plate material thickness t, the line deviation is reduced. Can be suppressed. In addition, since the difference in the maximum distance h is reduced, cracks due to the elongation of the material of the plate member 10 or wrinkles due to the surplus meat are less likely to occur.

Preferably, the intermediate shape B has a minimum radius of curvature R of the contour line L1 and a tip radius of curvature r of the sharpest ridgeline portion in all cross sections in the range of the entire length of the sharpest ridgeline portion of the ridgeline portion 2.
It may be set so as to satisfy Expression (4): R ≧ 5r. At this time, the curved surface constituting the product portion 11 after the first pressing step has a sufficiently large radius of curvature with respect to the leading edge radius of curvature r of the sharpest ridge line portion. Therefore, in the second pressing step, the material flow of the plate 10 Even if this occurs, there is little risk of being visually recognized as a line shift.

  Further, in a state where the outer peripheral edge portion of the contour line L1 of the target shape A and the contour line L2 of the intermediate shape B is overlapped, the apex p of the ridge line portion 2 that becomes the sharpest ridge line portion is the contour line L1 of the intermediate shape B It is desirable that the contour line L1 is located outside (that is, the upper side in the figure) from the apex p. At this time, in the second pressing step, interference between the product part 11 and the second press mold 4 can be prevented.

  Thus, the target shape A having the sharp ridge line portion 2 represented by the above formula (1) is formed by two steps of the first press step and the second press step, and the above formula (2), ( By using the intermediate shape B having the contour line L1 that satisfies 3), the formability can be improved, and the occurrence of cracks, wrinkles, and line deviations can be prevented. Furthermore, by forming the contour line L1 of the intermediate shape B with a curve in which the minimum curvature radius R satisfies the expression (4), the effect of preventing line deviation can be improved. Therefore, it is possible to obtain a press-molded product excellent in design properties free from surface property defects and molding defects.

  The present invention can also be applied to a press-formed product having a ridge line portion on a design surface of a building material, a transport device such as a ship, and a home appliance.

EXAMPLES Hereinafter, although an Example is described, this invention is not limited to these Examples.
Example 1
The press-formed product 1 shown in FIGS. 5 to 7 was manufactured by the above-described steps. The press-formed product 1 is an outer panel of an automobile door, and a 6000 series aluminum alloy plate having a thickness t of 1.0 mm is used as the plate material 10. The product part 11 to be the press-formed product 1 has a door shape having a substantially trapezoidal outer shape A, and one linear ridge line part 2 extending in the horizontal direction on the upper surface. Below the ridge line portion 2, there is an elliptical concave curved surface portion 5 corresponding to the door handle mounting portion. A peripheral portion 12 surrounding the product portion 11 with a substantially constant width is provided on the outer periphery of the product portion 11, and both ends of the ridge line portion 2 reach both end edges of the product portion 11.

  The target shape A has a mountain-shaped cross-sectional shape with the tip of the ridge line portion 2 as the apex p. The radius of curvature r at the tip of the ridgeline 2 that is the sharpest ridgeline is 2.0 mm (that is, r = 2t <10t), which satisfies the above formula (1). For this target shape A, an intermediate shape B shown in FIGS. 8 to 10 was set so as to satisfy the above formulas (2) to (4). 11 to 14 show the contour line L2 of the target shape A and the contour line of the intermediate shape B with respect to a cross section orthogonal to the longitudinal direction of the ridge line portion 2 and not including the concave curved surface portion 5 and a cross section including the concave curved surface portion 5. The state where L1 is overlapped is shown.

  An intermediate shape B indicated by a broken line in the drawing has a contour line L1 that substantially matches the contour line L2 of the target shape A, except for the vicinity of the ridge line portion 2 and the door handle mounting portion. As shown in enlarged view in FIG. 12 and FIG. 14, in the vicinity of the ridge line portion 2, the ridge line 2 has a smooth curved outline L 1 along the target shape A through the vertex p of the ridge line portion 2. The intersection point p1 between the straight line in the press stroke direction passing through the apex p of the portion 2 and the contour line L1 substantially coincides with the apex p or is located outside the apex p (ie, on the upper side in the figure). Further, in the vicinity of the door handle mounting portion, a concave curved surface portion 51 having a substantially similar shape to the concave curved surface portion 5 of the target shape A is provided.

  First, in the preparation step, a plate material 10 obtained by processing an aluminum alloy plate into a blank sheet having a predetermined shape was prepared, and a rust preventive oil was thinly applied to the surface. The plate material 10 has a shape corresponding to the product portion 11 of the target shape A to be the press-formed product 1 and the peripheral portion 12 of the peripheral shape C. Moreover, the 1st press-molding die 3 and the 2nd press-molding die 4 provided with a pair of molding surfaces 31, 32, 41, 42 corresponding to the contour line L1 and the contour line L2 shown in FIGS. (See FIGS. 2 and 3).

  In the first pressing step, the prepared plate material 10 is disposed between the pair of molding surfaces 31 and 32 of the first press mold 3, and the peripheral portion 12 of the plate material 10 is held between the holding surfaces 311 and 321. The product part 11 was press-molded into an intermediate shape B. Next, in the second pressing step, the plate material 10 is disposed between the pair of molding surfaces 41 and 42 of the second press mold 4, and the product portion 11 having the intermediate shape B is formed without sandwiching the peripheral portion 12 of the plate material 10. The press-molded product 1 having the target shape A was manufactured by press molding.

  Here, with respect to the intermediate shape B and the target shape A of the present embodiment, the results of measuring the contour lengths l1 and l2 of the cross section in the press stroke direction in the entire length of the ridgeline portion 2 serving as the sharpest ridgeline portion are shown in FIG. . In FIG. 15, the horizontal axis is the position in the longitudinal direction (unit: mm) starting from one end of the ridge line portion 2, and the vertical axis is the contour line length (unit: mm) of the cross section orthogonal to the longitudinal direction at each position. It is. In FIG. 16, the result of calculating the difference between the contour line lengths 11 and 12 is shown with the position (unit: mm) of the ridge line part 2 as the horizontal axis and the vertical axis as the contour line length difference (unit: mm).

  Further, the minimum value of the radius of curvature of the contour line L1 of the intermediate shape B (namely, the minimum radius of curvature R) and the minimum value of the radius of curvature of the contour line L2 of the target shape A (namely, the radius of curvature r of the tip of the ridge line portion 2) are obtained. The total length of the ridgeline part 2 was measured. The results are shown in FIG. 17 with the position on the ridge line portion 2 (unit: mm) as the horizontal axis and the vertical axis as the radius of curvature (unit: mm). Further, the maximum distance h in the press stroke direction between the contour line L1 and the contour line L2 is measured with respect to the entire length of the ridge line part 2, and the result is represented by the position of the ridge line part 2 (unit: mm) as the horizontal axis and the vertical axis as the maximum. The distance (unit: mm) is shown in FIG.

  As shown in FIG. 15, in the press-formed product 1 of the present embodiment, the contour line length 11 of the intermediate shape B and the contour line length 12 of the target shape A are substantially the same with respect to the entire length of the ridge line portion 2. At this time, as shown in FIG. 16, the difference between the contour length l1 and the contour length l2 (l2-l1) is as small as 0.18 mm (≦ s / 2 = 0.78 mm). Satisfy (2). As shown in FIG. 17, the minimum radius of curvature R of the contour line L1 of the intermediate shape B is 14.1 mm (≧ 5r = 10 mm), which satisfies the above formula (4). As shown in FIG. 18, the maximum distance h in the press stroke direction between the contour line L1 and the contour line L2 has a minimum value hmin of 4.56 mm and hmax of 4.82 mm, and hmax−hmin = 0.26 mm (≦ 5t = 5 mm) and the above formula (3) is satisfied.

  About the obtained press-molded product 1, the evaluation of the molding result was performed for cracks, wrinkles, and line deviation of the ridge line portion 2. Here, about the crack, the surface of the press-molded product 1 was visually observed, and the product in which the crack was not confirmed was regarded as an acceptable product. For wrinkles, the surface of the press-formed product 1 was visually observed and evaluated for the occurrence of wrinkles. As for the line deviation of the ridge line portion 2, during the initial stage of the second press process, during the time from when the corresponding part of the second press mold 4 comes into contact with the ridge line portion 2 forming position of the plate 10 to the bottom dead center. In addition, the distance that the material at the tip position of the ridge line portion 2 moved relative to the second press mold 4 was measured and evaluated, and 1.0 mm or less was regarded as an acceptable product.

  As a result, the obtained press-formed product 1 had no cracks, no wrinkles, and a maximum line deviation of 0.2 mm, and was an acceptable product for any evaluation item.

(Comparative Example 1)
For comparison, the same press-formed product 1 as in Example 1 was produced in the same manner except that the intermediate shape B with respect to the target shape A was changed. As shown in FIGS. 19 and 20, the intermediate shape B of the present example, which includes the cross section of the door handle mounting portion, has a chevron-shaped contour line L <b> 1, and is formed on the concave curved surface portion 5 of the target shape A. In the corresponding part, the distance in the press stroke direction is large. At this time, in the same manner as in Example 1, the contour length l1 of the intermediate shape B and the contour length l2 of the target shape A, the difference between the contour lengths l1 and l2, and the minimum curvature radius R of the contour line L1 The maximum distance h between the contour line L1 and the contour line L2 was examined with respect to the total length of the ridge line part 2. The results are shown in FIGS.

  As shown in FIGS. 21 to 24, the contour line length l1 of the intermediate shape B and the contour line length l2 of the target shape A substantially coincide with each other, and the difference between the contour line length l1 and the contour line length l1 (12− l1) has a maximum value of 0.71 mm (≦ s / 2 = 0.78 mm), which satisfies the above formula (2). The minimum radius of curvature R of the contour line L1 of the intermediate shape B is 14.1 mm (≧ 5r = 10 mm), which satisfies the above formula (4). The maximum distance h in the press stroke direction between the contour line L1 and the contour line L2, the minimum value hmin is 3.49 mm, hmax is 19.61 mm, hmax−hmin = 16.12 mm (> 5t = 5 mm), Formula (3) is not satisfied.

  Moreover, about the obtained press-molded product 1, evaluation of the molding result was performed for cracks, wrinkles, and line deviation of the ridge line portion 2. As a result, there was no crack, wrinkles were generated, the maximum line displacement amount was 4.0 mm, and the difference in the maximum distance h between the contour line L1 and the contour line L2 was increased, and the line displacement of the ridge line portion 2 was increased. It can be seen that wrinkles are likely to occur.

(Comparative Example 2)
For comparison, the same press-formed product 1 as in Example 1 was produced in the same manner except that the intermediate shape B with respect to the target shape A was changed. As shown in FIGS. 25 and 26, the intermediate shape B of this example is substantially the same shape as the intermediate shape B of Example 1, and the length l1 of the contour line L1 is formed slightly shorter. 27 to 30, the contour length l1 of the intermediate shape B and the contour length l2 of the target shape A, the difference between the contour lengths l1 and l2, the minimum radius of curvature R of the contour line L1, the contour line are shown. The result of having investigated the maximum distance h of L1 and the outline L2 about the full length of the ridgeline part 2 was shown.

  As shown in FIGS. 27 to 30, the contour line length l1 of the intermediate shape B is slightly shorter overall than the contour line length l2 of the target shape A, and the difference between the contour line length l2 and the contour line length l1 ( l2-l1) has a maximum value of 4.1 mm (> s / 2 = 0.78 mm), which does not satisfy the above formula (2). The minimum radius of curvature R of the contour line L1 of the intermediate shape B is 14.1 mm (≧ 5r = 10 mm), which satisfies the above formula (4). The maximum distance h in the press stroke direction between the contour line L1 and the contour line L2, the minimum value hmin is 4.56 mm, hmax is 4.82 mm, hmax−hmin = 0.26 mm (≦ 5t = 5 mm), Expression (3) is satisfied.

  Moreover, about the obtained press-molded product 1, evaluation of the molding result was performed for cracks, wrinkles, and line deviation of the ridge line portion 2. As a result, cracks occurred, no wrinkles occurred, and the maximum line deviation amount was 4.18 mm. As a result, the contour line length l1 is shorter than the contour line length l2, and the difference (l2-l1) becomes large, so that the material of the plate member 10 becomes insufficiently stretched at the time of molding, and cracking occurs. It can be seen that the line deviation of the ridge line portion 2 increases due to the material flowing in the process.

(Comparative Example 3)
For comparison, the same press-formed product 1 as in Example 1 was produced in the same manner except that the intermediate shape B with respect to the target shape A was changed. As shown in FIGS. 31 and 32, the intermediate shape B of this example is substantially the same shape as the intermediate shape B of Example 1, and the length l1 of the contour line L1 is formed to be slightly longer. At this time, FIGS. 33 to 36 show the contour length l1 of the intermediate shape B and the contour length l2 of the target shape A, the contour length difference, the minimum radius of curvature R of the contour line L1, the contour line L1 and the contour line. The result of having investigated the maximum distance h of L2 about the full length of the ridgeline part 2 was shown.

  As shown in FIGS. 33 to 36, the contour line length l1 of the intermediate shape B is slightly longer overall than the contour line length l2 of the target shape A, and the difference of the contour line length l2 from the contour line length l1 ( l2-l1) has a minimum value of −4.1 mm (that is, its absolute value is 4.1 mm> s / 2 = 0.78 mm), and does not satisfy the above formula (2). The minimum radius of curvature R of the contour line L1 of the intermediate shape B is 14.1 mm (≧ 5r = 10 mm), which satisfies the above formula (4). The maximum distance h in the press stroke direction between the contour line L1 and the contour line L2, the minimum value hmin is 4.56 mm, hmax is 4.82 mm, hmax−hmin = 0.26 mm (≦ 5t = 5 mm), Expression (3) is satisfied.

  Moreover, about the obtained press-molded product 1, evaluation of the molding result was performed for cracks, wrinkles, and line deviation of the ridge line portion 2. As a result, cracks did not occur, wrinkles occurred, and the maximum line deviation amount was 4.18 mm. As a result, the contour line length l1 is longer than the contour line length l2, and the difference (l2-l1) is increased, resulting in a surplus on the surface of the molded product, wrinkling, and the material in the molding process. It turns out that the line shift of the ridgeline part 2 becomes large by flowing.

(Example 2)
About the press-formed product 1 of Example 1, the target shape A was changed to a shape having a plurality of ridge line portions 2, and the press-formed product 1 was manufactured by the same method except that. As shown in FIGS. 37 to 40, the product portion 11 that is the press-formed product 1 of the present example has a concave curved surface of the door handle mounting portion below the ridge line portion 2 in the target shape A of the first embodiment. It has another ridge line portion 21 extending in parallel across the portion 5.

  The target shape A has apexes p and p ′ at the tips of the two ridge portions 2 and 21, and has a substantially mountain-shaped cross-sectional shape as a whole. The two ridge line portions 2 and 21 have the same tip radius of curvature r of 2.0 mm (that is, r = 2t), and both are the sharpest ridge line portions that satisfy the above formula (1). For this target shape A, an intermediate shape B indicated by a broken line in the figure was set so as to satisfy the above formulas (2) to (4). For the total length of the two ridge lines 2 and 21, the difference between the length l1 of the contour line L1 and the length l2 of the contour line L2 is 1.5 mm or less, and the maximum distance h between the contour line L1 and the contour line L2 is The difference between the minimum value and the maximum value was 5 mm or less, and the minimum curvature radius of the contour line L1 of the intermediate shape B was 14.1 mm. Further, the intersection points p1 and p′1 between the straight line in the press stroke direction passing through the two apexes p and p ′ and the contour line L1 substantially coincide with the apexes p and p ′, respectively, or outside the apex p (that is, in the drawing) Located on the upper side.

The obtained press-formed product 1 was evaluated for the molding results in the same manner as in Example 1. As a result, no cracks, no wrinkles were generated, and the maximum line deviation amount was 0.5 mm. Obtained.
(Examples 3 and 4)
A press-formed product 1 was produced in the same manner as in Example 1 except that the target shape A of the press-formed product 1 was partially changed. As shown in FIG. 41, in Example 3, with respect to the target shape A of Example 1, the ridge line part 2 is formed from the center part of the product part 11 to one end side (that is, the left end side in the figure), and the door handle is attached. It was made into the shape which is not formed in the vicinity of the concave curved surface part 5 of a part. As shown in FIG. 42, in Example 4, only the ridge line portion 21 of Example 2 was formed. For these target shapes A of Examples 3 and 4, the intermediate shape B was set so as to satisfy the above equations (2) to (4).

  Similarly, the obtained press-formed product 1 was evaluated for molding results. As a result, no cracks, no wrinkles were generated, and the maximum amount of line deviation was 0.5 mm.

(Example 5)
A press-formed product 1 was produced in the same manner as in Example 1 except that the target shape A of the press-formed product 1 was changed as shown in FIG. The press-formed product 1 of this example is an automobile hood panel, and the product part 11 of the plate member 10 has a substantially quadrangular outer shape that is symmetrical to the left and right, and a peripheral part 12 surrounds the outer periphery thereof. A substantially U-shaped ridge line part 22 is formed in the center part on the outer surface of the product part 11 to be the target shape A, and two linear ridge line parts 23 and 24 are formed in both parts thereof. . The two ridge lines 23 and 24 extend in the short direction of the plate 10 (that is, the vertical direction in the figure) and reach both end edges of the product part 11.

  As shown in FIG. 44, in the target shape A of this example, in one half portion (for example, the right half portion in the figure), the tip ends of the two ridge line portions 22 and 23 are apexes p22 and p23, and a flat central portion. And has a cross-sectional shape that is inclined downward toward the peripheral portion 12. The two ridge line portions 22 and 23 have the same tip radius of curvature r of 2.0 mm (ie, r = 2t), and both are the sharpest ridge line portions that satisfy the above formula (1). For this target shape A, an intermediate shape B indicated by a broken line in the figure was set so as to satisfy the above formulas (2) to (4). For the total length of the two ridge lines 22 and 23, the difference between the length l1 of the contour line L1 and the length l2 of the contour line L2 is 1.5 mm or less, and the maximum distance h between the contour line L1 and the contour line L2 is The difference between the minimum value and the maximum value was 5 mm or less, and the minimum curvature radius R of the contour line L1 of the intermediate shape B was 10 mm or more.

  The obtained press-formed product 1 was evaluated for the molding results in the same manner as in Example 1. As a result, no cracks, no wrinkles were generated, and the maximum line deviation amount was 0.5 mm. Obtained.

(Comparative Example 4)
For comparison, a press-formed product 1 was manufactured in the same manner as in Example 1 except that the intermediate shape B with respect to the target shape A was not set and the first press step was not performed. The prepared plate material 10 was press-molded using the second press-molding die 4 of Example 1, and the product part 11 was molded into the target shape A with the peripheral part 12 sandwiched.

  About the obtained press-molded product 1, the evaluation of the molding result was performed for cracks, wrinkles, and line deviation of the ridge line portion 2. As a result, cracks were observed, and the maximum thickness reduction rate of the molded plate 10 was 20%. There were no wrinkles. In addition, the maximum line deviation amount was 4.0 mm. As described above, when the target shape A having the sharp ridge line portion 2 is formed in one step, any of molding defects such as cracks or wrinkles are likely to occur, and the amount of line deviation is the tip radius of curvature of the ridge line portion 2. It becomes larger than r, and it turns out that it is easy to cause a surface quality defect.

  The manufacturing method of the press-formed product of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Moreover, the said method is applicable not only to the outer panel for motor vehicles but any press-molded product which has a sharp ridgeline part in the design surface.

A Target shape B Intermediate shape C Peripheral shape 1 Press-molded product 10 Plate material 11 Product part 12 Peripheral part 2, 21-24 Ridge line part 3 First press-molding die 31, 32 Pair of molding surfaces 4 Second press-molding die 41, 42 Pair of molding surfaces 5 Concave surface

Claims (7)

A method for producing a press-formed product having a target shape having one or more ridge lines on a design surface,
A step of preparing a plate part for obtaining a product part constituting the press-formed product and a peripheral part surrounding the product part;
A first pressing step of forming the product portion of the plate material into an intermediate shape by press molding;
A second pressing step of forming the intermediate shape into the target shape by press molding,
The tip curvature radius r at the sharpest ridge line portion having the smallest tip curvature radius among the one or more ridge line portions in the target shape, and the thickness t of the plate material are as follows:
Formula (1): t ≦ r ≦ 10t is satisfied,
In the state where the intermediate shape and the target shape are overlapped with the positions of the respective outer peripheral edges being matched, the intermediate shape appears in a cross section perpendicular to the longitudinal direction of the sharpest ridge line portion when viewed from the press stroke direction. About the contour line L1 and the contour line L2 of the target shape,
The length l1 of the contour line L1, the length l2 of the contour line L2, and the tip arc length s of the sharpest ridge line part are:
Formula (2): | l2-l1 | ≦ s / 2 is satisfied,
And, when the maximum distance h in the press stroke direction between the contour line L1 and the contour line L2 is determined in all the cross sections in the entire length range of the sharpest ridge line portion, the maximum value hmax and the minimum value hmin , And the thickness t of the plate material is
The method for manufacturing a press-formed product, wherein the target shape and the intermediate shape are set so as to satisfy the formula (3): hmax−hmin ≦ 5t. The intermediate shape has a minimum curvature radius R of the contour line L1 and a tip curvature radius r.
The method for producing a press-formed product according to claim 1, wherein the method is set so as to satisfy the formula (4): R ≧ 5r.   3. The method for manufacturing a press-formed product according to claim 1, wherein in the first pressing step, the product part is formed into the intermediate shape with the peripheral part sandwiched therebetween.   The said 2nd press process is a manufacturing method of the press-molded product of any one of Claims 1-3 which shape | molds the said intermediate shape in the said target shape in the state which does not clamp the said peripheral part.   The method for producing a press-formed product according to any one of claims 1 to 4, wherein the plate material is a steel plate or an aluminum alloy plate.   The method for manufacturing a press-formed product according to any one of claims 1 to 5, wherein a thickness t of the plate material is 0.3 mm to 2.5 mm.   A press mold used in the first press step in the method for manufacturing a press-formed product according to any one of claims 1 to 6, wherein the press mold has a pair of molding surfaces corresponding to the intermediate shape. Press mold.

Images