Patent ID: 12194523

DESCRIPTION OF EMBODIMENTS

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

(Pressed Component Shape)

The pressed component shape after press forming targeted by this embodiment has a cross-sectional shape, such as a U-shaped cross section, a hat-shaped cross section, or an L-shaped cross section, having at least a top sheet portion and a side wall portion continuous to at least one of both sides in the left and right width direction via a first bent portion. Further, the pressed component shape is a shape having one or two or more curved portions in which the top sheet portion is curved to project or to be recessed in a side view along the longitudinal direction in one place or two or more places in the longitudinal direction in the direction intersecting the cross section (sheet width direction). In the case of the hat-shaped cross section, the pressed component shape is a shape in which a flange portion also follows the curve of the top sheet portion in a side view along the longitudinal direction.

Herein, this embodiment relates to a technology suitable for manufacturing a pressed component using a metal sheet containing a difficult-to-form member having poor ductility and a poor Lankford Value, such as a high-tensile steel sheet and an aluminum alloy sheet having a tensile strength of 590 MPa or more.

The description that the top sheet portion is curved to project or to be recessed in a side view refers to a case where the top sheet portion is curved to project or to be recessed in the sheet thickness direction of the top sheet portion along the longitudinal direction.

This embodiment describes a target pressed component shape1after press forming taking, as an example, a case of performing forming into the pressed component shape1having a hat-shaped cross section and having curved portions10in two places along the longitudinal direction as illustrated inFIG.1. More specifically, this embodiment exemplifies, as the target pressed component shape1, a case of a hat-shaped cross section and having a curved portion10A where a top sheet portion1A is curved to be recessed (bent downward) and a curved portion10B where the top sheet portion1A is curved to project (bent upward) in two places along the longitudinal direction as illustrated inFIG.1. However, in this embodiment, the curved portion10may be formed in one place or the curved portions10may be formed in three or more places. Even when the curved portions10are formed in two or more places, a shape may be acceptable in which the curved portions10in the two places adjacent to each other are curved in the same direction.

It should be noted that the dimensions illustrated inFIG.1are the dimensions in Examples and do not limit the present invention at all.

(Configuration)

A method for manufacturing a pressed component of this embodiment includes a preliminary forming step2and a component forming step3as illustrated inFIG.2.

<Preliminary Forming Step2>

The preliminary forming step2is a step of obtaining a metal sheet for main forming difficult to cause wrinkles by applying preliminary forming before main forming to the metal sheet.

The preliminary forming step2has a first step2A of giving, to a flat metal sheet, a curved shape following the curves of the curved portions10provided in the pressed component shape1along the longitudinal direction of the pressed component shape1and a second step2B of forming first beads4aand second beads4bat positions where a first bent portion1dand a second bent portion1eare formed, respectively. The first beads4aand the second beads4beach continuously or partially extend along the longitudinal direction.

The second step2B may be a step of forming only either the first beads4aor the second beads4b. Further, the first beads4aand the second beads4bmay be arranged such that the formation positions of the first beads4aand the formation positions of the second beads4bdo not overlap with each other in the longitudinal direction.

The preliminary forming step2may include only the second step2B.

In this specification, the “beads continuously or partially extending along the longitudinal direction” includes a case where the beads are continuously formed over the entire length in the longitudinal direction of the metal sheet4and a case where the beads are formed in a part along the longitudinal direction of the metal sheet4. A plurality of beads may be formed at intervals along the longitudinal direction of the metal sheet4. For example, when the pressed component shape1has two or more of the curved portions10, the beads may be continuously formed in two or more places where the curved portions10are formed or the beads may be individually formed for each of the curved portions10.

FIG.6illustrates an example of the cross-sectional shapes of the first beads4aand the second beads4b. The example illustrated inFIG.6is an example in which the first beads4aand the second beads4bare constituted by a full bead.

Herein, the beads4a,4bof this embodiment have a shape in which the cross section of a bent shape extends in a direction intersecting the cross section (longitudinal direction (longitudinal direction of the top sheet portion of the metal sheet4)). The beads4a,4bcontain a full bead or a half bead having a stepped cross-sectional shape.

For the curved shape following the curves of the curved portions10provided in the pressed component shape1, a profile shape in a side view of the top sheet portion1A of the pressed component shape1(for example, profile shape along the longitudinal direction of an edge line portion formed by the first bent portion1d) is adopted. The curvature radius of the curved portions10of the curved shape given to the metal sheet4in a side view is preferably set to be equal to the curvature radius of the curved portions10provided in the pressed component shape1. A difference between the curvature radius of the curved portions10of the curved shape given to the metal sheet4and the curvature radius of the curved portions10provided in the pressed component shape1is preferably set to be ±10% or less of the curvature radius of the curved portions10provided in the pressed component shape1, for example.

The first bent portion1dcorresponds to the cross section of an edge line portion1D formed between the top sheet portion1A and a vertical wall portion. The edge line portion1D is bent to project upward. The second bent portion1ecorresponds to the cross section of an edge line portion1E formed between the vertical wall portion and a flange portion1C. The edge line portion1E is bent to be recessed upward.

Herein, the second step2B may have a processing configuration of forming only either the first beads4aor the second beads4b.

In this embodiment, the first step2A and the second step2B are carried out by pressing using one die.

As illustrated inFIG.3, the die to be used has forming surfaces20,21of an upper die (die) and a lower die (punch), respectively, given with the same curves as the curved shape of the pressed component shape1in a side view. The pressed component shape1of this embodiment has a shape of having the curved portion10A in which the top sheet portion1A is bent to be recessed (bent downward) and the curved portion10B in which the top sheet portion1A is bent to project (bent upward). The forming surfaces20,21of the upper die (die) and the lower die (punch), respectively, have a surface shape having a portion in which the top sheet portion1A is bent to be recessed (bent downward) and a portion in which the top sheet portion1A is bent to project (bent upward) according to the shape following the shape in a side view.

Thus, the metal sheet4is given with the same curved shape in the width direction (same direction as the width direction of the pressed component shape1), for example.

The curved shape in a side view of the forming surfaces20,21of the upper die (die) and the lower die (punch), respectively, is preferably equal to the curved shape in the top sheet portion1A in a side view in the pressed component shape1.

In usual, the curved shape of the top sheet portion1A and the curved shape of the flange portion1C in a side view along the longitudinal direction are equal or substantially equal to each other. Therefore, the curved shape in a side view of the forming surfaces of the upper die (die) and the lower die (punch) may have a shape following the curved shape of the top sheet portion1A along the longitudinal direction. When the curved shape of the top sheet portion1A and the curved shape of the flange portion1C in a side view are different from each other, the curved shapes at the surface position where the top sheet portion1A is formed and the surface position where the flange portion1C is formed may have different shapes. In this case, the difference in the curved shape may be absorbed by the forming surfaces forming the vertical wall portion.

Further, the forming surfaces20,21of the upper die (die) and the lower die (punch) have bead shapes20a,21afollowing the first beads4aand the bead shapes20b,21bfollowing the second beads4b, respectively, extending along the positions where the first bent portion1dand the second bent portion1eare formed, i.e., along the longitudinal direction. The positions where the first bead shapes20a,21aand the second bead shapes20b,21bare formed are positions contactable with a punch shoulder edge line portion and a die shoulder edge line portion of a die in the component forming step3in the component forming step3.

Herein, the first beads4apreferably have a shape of projecting in the same direction as the projection direction of the first bent portion1d(a shape of projecting upward in the cross section) (seeFIG.6).

The bead height of the first beads4ais preferably twice or more the sheet thickness of the metal sheet4. The upper limit of the bead height of the first beads4ais 20 mm.

The second beads4bpreferably have a shape of projecting in the same direction as the projection direction of the second bent portion1e(a shape bent downward) (seeFIG.6).

The bead height of the second beads4bis preferably twice or more the sheet thickness of the metal sheet4. The upper limit of the bead height of the second beads4bis 20 mm.

In the preliminary forming step2, the metal sheet4is press formed using the upper and the lower die above, so that the metal sheet4is obtained which includes the first beads4aand the second beads4bcurved along the longitudinal direction and extending along the longitudinal direction.

<Component Forming Step3>

The component forming step3is a main forming step of forming the metal sheet4processed in the preliminary forming step into the target pressed component shape1.

The component forming step3includes press forming the metal sheet4after the processing in the preliminary forming step2using a die having forming surfaces22,23as illustrated inFIG.4to obtain a pressed component of the target pressed component shape1.

FIG.4exemplifies a case where the die has a pad24holding the position where the top sheet portion1A is formed of the metal sheet4. More specifically, this example exemplifies a case where bending forming is adopted as the press forming. However, the component forming step3may adopt stamping in which the top sheet portion1A is not held by the pad24.

Herein, the preliminary forming step2constitutes at least either the first preliminary forming step or the second preliminary forming step. The component forming step3constitutes at least either the first component forming step or the second component forming step.

(Operations and Others)

In this embodiment, the preliminary forming step2carries out processing of giving the curved shape (shape of being curved in the sheet thickness direction) along the longitudinal direction to the metal sheet4and processing of giving at least either the first beads4aor the second beads4bto the metal sheet4(FIG.3) as preliminary forming.

At this time, when the metal sheet4is pressed with the upper die and the lower die for the preliminary forming step2, the metal sheet4is first transformed into the curved shape along the forming surfaces20,21of the upper die and the lower die, respectively, as the upper die relatively approaches the lower die. Further, the upper die relatively approaches the lower die and moves to the bottom dead center, so that the first beads4aand the second beads4bare press formed in the metal sheet4in the state of the curved sheet shape. More specifically, the formation of the beads4a,4bis carried out after the curved shape is given to the metal sheet4.

By the formation of the first beads4aand the second beads4bextending in the longitudinal direction after the curved shape is given, springback along the longitudinal direction during die release of the curved shape given as the first step2A is kept small.

The metal sheet4in the preliminary forming step2becomes higher in shape rigidity in the longitudinal direction by giving the beads4a,4b.

Next, when the metal sheet4after the preliminary forming step2is pressed in the component forming step3to have a U-shaped cross section or a hat-shaped cross section having the curved portions10vertically curved in a side view, the metal sheet4has a higher shape rigidity in the longitudinal direction due to the beads4a,4b, and therefore the generation of wrinkles due to buckling is suppressed.

Herein, when the metal sheet4containing a flat sheet is press formed into the component shape having the curved portions10vertically curved in a side view, the expansion in the longitudinal direction occurs on the top sheet portion1A side (projection side) and the contraction in the longitudinal direction occurs on the flange portion1C side (recess side) in the curved portion10projecting toward the top sheet portion1A side as illustrated inFIG.5. In the curved portion10recessed toward the top sheet portion1A side, the contraction in the longitudinal direction occurs on the top sheet portion1A side (recess side) and the expansion in the longitudinal direction occurs on the flange portion1C side (projection side).

Then, a material movement occurs in the longitudinal direction on the top sheet portion1A side and the flange portion1C side with the expansion and contraction, causing the generation of wrinkles. For example, when the bending forming in which the top sheet portion1A is restrained is adopted, there is a risk of the generation of wrinkles due to buckling in the curved portion10projecting toward the top sheet portion1A in the flange portion1C where the material freely moves. When the drawing is adopted, the flange portion1C is restrained, and therefore there is a risk of the generation of wrinkles due to buckling in the curved portion10recessed toward the top sheet portion1A in the top sheet portion1A where the material freely moves. When the stamping is adopted, the material freely moves in both the top sheet portion1A and the flange portion1C, and therefore there is a risk of the generation of wrinkles in the top sheet portion1A and the flange portion1C.

In contrast thereto, in the component forming step3of this embodiment, the first beads4aand the second beads4bas illustrated inFIG.6are formed in advance in the metal sheet4, so that the shape rigidity in the longitudinal direction of the metal sheet4increases. As a result, in the press forming in the component forming step3, the generation of wrinkles due to buckling to the metal sheet4is suppressed and the deformation of the edge line portion1D between the top sheet portion1A and the side wall portion1B and the edge line portion1E between the side wall portion1B and the flange portion1C is prevented.

Therefore, in this embodiment, the flange surface is formed by the movement in parallel to the press direction with respect to the top sheet portion1A as illustrated inFIG.7, and the material movement causing wrinkles is suppressed in the press forming in the component forming step3.

Further, by giving the curved shape along the longitudinal direction to the metal sheet4in advance, the flange surface is formed by the movement in parallel to the press direction with respect to the top sheet portion1A, and the material movement causing wrinkles is further suppressed in the press forming.

(Modification)

(1) The description above exemplifies the case where the first step2A and the second step2B of the preliminary forming step2are carried out with one die.

The first step2A and the second step2B may be carried out using individual dies for the steps. However, in this case, it is preferable that the curved shape is given to the metal sheet4in the first step2A, and then the beads4a,4bare given in the second step2B.

(2) The description above exemplifies the case where both the steps of the first step2A and the second step2B are carried out in the preliminary forming step2. It may acceptable that the first step2A is omitted and only the second step2B (step of forming the beads) is carried out in the preliminary forming step2. It may be acceptable that the curved shape of being curved in the vertical direction in a side view and the bending at the first bent portion1dand the second bent portion1epositions along the width direction are carried out in the component forming step3.

(3) The description above exemplifies the case where the first beads4aand the second beads4bare formed in the entire positions where the edge line portions1D,1E containing the first bent portion1dand the second bent portion1e, respectively, are formed, but the first beads4aand the second beads4bmay be partially provided at the corresponding positions of the edge line portions1D,1E, respectively, along the longitudinal direction.

In this case, it is preferable that the beads are formed in at least a first estimation region where it is estimated that wrinkles are generated in the top sheet portion1A when the metal sheet4containing a flat sheet is press formed into the pressed component shape1and a second estimation region where it is estimated that wrinkles are generated in the flange portion1C when the metal sheet4containing a flat sheet is press formed into the pressed component shape1.

At this time, it is preferable to include a first estimation region acquisition unit6and a second estimation region acquisition unit7as illustrated inFIG.8.

The first estimation region acquisition unit6carries out processing of obtaining the first estimation region where it is estimated that wrinkles are generated in the top sheet portion1A when the metal sheet4containing a flat sheet is press formed into the pressed component shape1.

The second estimation region acquisition unit7carries out processing of obtaining the second estimation region where it is estimated that wrinkles are generated in the flange portion1C when the metal sheet4containing a flat sheet is press formed into the pressed component shape1.

The processing by the first estimation region acquisition unit6and the second estimation region acquisition unit7may be carried out by forming analysis using a computer or may include actually carrying out the press forming.

Further, the wrinkles in the forming are generated in the curved portion10on the side where the material gathers of the curved portions10, and therefore the curved portion10where the top sheet portion1A is curved to be recessed may be simply estimated as the first estimation region and the curved portion10where the top sheet portion1A is curved to project may be simply estimated as the second estimation region.

(Effects)

This embodiment exhibits the following effects.

(1) In this embodiment, the method for manufacturing a pressed component includes forming the metal sheet4into the pressed component shape1having: the cross section having the top sheet portion1A and the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section, and the method includes: the first preliminary forming step having the step of forming, to the metal sheet4, the first beads4acontinuously or partially extending along the longitudinal direction at the position where the first bent portion1dis formed; and the first component forming step of forming the metal sheet4after the first preliminary forming step into the pressed component shape1.

This configuration can suppress the generation of wrinkles at least in the top sheet portion1A by forming the first beads4aalong the position where the edge line portion containing a bent portion connecting the top sheet portion1A and the side wall portion1B is formed before performing the press forming into the pressed component shape1having the curved shapes in the upper and lower sides in a side view, so that the shape rigidity along the longitudinal direction in the forming into the pressed component shape1is improved.

(2) The pressed component shape has the cross section having the flange portion continuous to the side wall portion via the second bent portion, and the first preliminary forming step has the step of forming the first beads and the step of forming, to the metal sheet, the second beads continuously or partially extending along the longitudinal direction at the position where the second bent portion is formed.

According to this configuration, the shape rigidity along the longitudinal direction of not only the edge line portion on the top sheet portion1A side but the edge line portion on the flange side is improved, so that the generation of wrinkles not only in the top sheet portion1A but in the flange portion1C can be suppressed.

(3) The first beads and the second beads each partially extend at least at the positions where the curved portions are formed. The position where the curved portion is formed, the position being the formation position of the first beads and the position where the curved portion is formed, the position being the formation position of the second beads, are different from each other.

According to this configuration, the bead formation positions can be suppressed.

(4) The first beads4apreferably have a shape of projecting in the same direction as the projection direction of the first bent portion1d.

According to this configuration, the bead shape of the first beads4acan be easily crushed in the component forming step3. The target pressed component shape1may be a shape in which the beads are formed along an edge line portion connecting the top sheet portion1A and the side wall portion1B.

The top sheet portion1A is a surface serving as a connection portion with another component, and therefore it is preferable that no beads are formed.

(5) The first preliminary forming step may have the step of giving the curves following the curves of the curved portions10along the longitudinal direction to the metal sheet4and the step of forming the first beads4a.

According to this configuration, the first preliminary forming step gives the curved shape together with the first beads4a, so that the shape accuracy in the longitudinal direction is improved, for example.

(6) This embodiment may be configured so that the first estimation region acquisition unit6is included which obtains the first estimation region where it is estimated that wrinkles are generated in the top sheet portion1A when the metal sheet4containing a flat sheet is press formed into the pressed component shape1, and the first preliminary forming step partially forms the first beads4ato the metal sheet4portion corresponding to the bent portion containing a region serving as the first estimation region of the edge line portion formed by the bent portion.

This configuration prevents the giving of the first beads4amore than necessary.

(7) The bead height of the first beads4ais preferably twice or more the sheet thickness of the metal sheet4.

This configuration can certainly improve the shape rigidity in the longitudinal direction.

(8) This embodiment may be configured so that the second estimation region acquisition unit7is included which obtains the second estimation region where it is estimated that wrinkles are generated in the flange portion1C when the metal sheet4containing a flat sheet is press formed into the pressed component shape1, and the first preliminary forming step partially forms the second beads4bto the metal sheet4portion corresponding to the second bent portion1econtaining a region serving as the second estimation region of the edge line portion formed by the second bent portion1e.

This configuration prevents the giving of the second beads4bmore than necessary.

(9) This embodiment may be configured so that the method for manufacturing a pressed component includes forming the metal sheet4into the pressed component shape1having: the cross section having the top sheet portion1A, the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d, and the flange portion1C continuous to the side wall portion1B via the second bent portion1e; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section, and the method includes: the second preliminary forming step of forming, to the metal sheet4, the second beads4bcontinuously or partially extending along the longitudinal direction at the position where the second bent portion1eis formed; and the second component forming step of forming the metal sheet4after the second preliminary forming step into the pressed component shape1.

This configuration can suppress the generation of wrinkles at least in the flange portion1C by forming the second beads4bat the position where the edge line portion containing the bent portion connecting the side wall portion1B and the top sheet portion1A is formed before performing the press forming into the pressed component shape1having the curved shapes in the upper and lower sides in a side view, so that the shape rigidity along the longitudinal direction in the forming into the pressed component shape1is improved.

(10) The second preliminary forming step may have the step of giving the curves following the curves of the curved portions10along the longitudinal direction to the metal sheet4and the step of forming the second beads4b.

According to this configuration, the second preliminary forming step gives the curved shape together with the second beads4b, and the shape accuracy in the longitudinal direction is improved, for example.

(11) This embodiment may be configured so that the second estimation region acquisition unit7is included which obtains the second estimation region where it is estimated that wrinkles are generated in the flange portion1C when the metal sheet4containing a flat sheet is press formed into the pressed component shape1, and the second preliminary forming step partially forms the second beads4bto the metal sheet4portion corresponding to the second bent portion1econtaining a region serving as the second estimation region of the edge line portion formed by the second bent portion1e.

This configuration prevents the giving of the second beads4bmore than necessary.

(12) The second beads4bpreferably have a shape of being recessed in the same direction as the recessing direction of the second bent portion1e.

According to this configuration, the bead shape of the second beads4bcan be easily crushed in the component forming step3. The target pressed component shape1may be a shape in which the beads are formed along an edge line portion connecting the side wall portion1B and the flange portion1C.

(13) The bead height of the second beads4bis preferably twice or more the sheet thickness of the metal sheet4.

This configuration can certainly improve the shape rigidity in the longitudinal direction.

(14) This embodiment may be configured so that the metal sheet4is to be press formed into the pressed component shape1having: the cross section having the top sheet portion1A and the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section, and the metal sheet4has the first beads4acontinuously or partially extending along the longitudinal direction at the position where the first bent portion1dis formed.

This configuration can suppress wrinkles generated at least in the top sheet portion1A in the press forming into the pressed component shape1having: the cross section having the top sheet portion1A and the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section.

(15) Further, the metal sheet4may be configured to be press formed into the pressed component shape1having the cross section having the flange portion1C continuous to the side wall portion1B via the second bent portion1eand to have the second beads4bextending along the longitudinal direction at the position where the second bent portion1eis formed together with the first beads4a.

This configuration can suppress wrinkles generated in the top sheet portion1A and the flange portion1C in the press forming into the pressed component shape1having: the cross section having the top sheet portion1A and the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section.

(16) Further, the metal sheet4may be configured to have the curves following the curves of the curved portions10along the longitudinal direction.

This configuration improves the shape accuracy in the longitudinal direction in the press forming into the pressed component shape1.

(17) This embodiment may be configured so that the metal sheet4is to be press formed into the pressed component shape1having: the cross section having the top sheet portion1A, the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d, and the flange portion1C continuous to the side wall portion1B via the second bent portion1e; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section, and the metal sheet4has the second beads4bcontinuously or partially extending along the longitudinal direction at the position where the second bent portion1eis formed.

This configuration can suppress wrinkles generated at least in the flange portion1C in the press forming into the pressed component shape1having: the cross section having the top sheet portion1A and the side wall portion1B continuous to at least one side in the width direction of the top sheet portion1A via the first bent portion1d; and having the one or two or more curved portions10in which the top sheet portion1A is curved to project or to be recessed in a side view along the longitudinal direction in the direction intersecting the cross section.

(18) Further, the metal sheet4may be configured to have the curves following the curves of the curved portions10along the longitudinal direction.

This configuration improves the shape accuracy in the longitudinal direction in the press forming into the pressed component shape1.

EXAMPLES

Next, examples of the press forming of the above-described embodiment based on the present invention are described. The present invention is not regulated by the following examples described below.

[Applied Materials]

In this example, a high-tensile steel sheet of 590 MPa or more was used as the metal sheet4.

Specifically, as the metal sheet4, a 590 MPa class steel sheet (590 material), a 980 MPa class steel sheet (980 material), a 1180 MPa class steel sheet (1180 material), and a 1470 MPa class steel sheet (1470 material) were used as shown in Table 1.

TABLE 1Sheet thicknessYPTSELSteel type(mm)(MPa)(MPa)(%)590 MPa material1.638160829980 MPa material1.66801041161180 MPa material1.68631242121470 MPa material1.6124615098

As the metal sheet4, a flat sheet with a width W of 240 mm, a length L of 387 mm, and a sheet thickness of 1.0 mmt was used.

In this example, the target component shape of a pressed component was set to a shape having a hat-shaped cross section and the curved portions10in two places along the longitudinal direction in a side view as illustrated inFIG.1.

In Comparative Examples, a flat metal sheet was directly press formed into the above-described pressed component shape by forming methods shown in Table 2. In Examples of Invention based on the present invention, a metal sheet was press formed into the above-described pressed component shape by forming methods shown in Table 3. More specifically, in the forming methods of Comparative Examples, the metal sheet containing a flat sheet was press formed into the target pressed component shape1in the component forming step3(main forming step) without the preliminary forming step2. In the forming methods in Examples of Invention based on the present invention, the target pressed component shape was achieved in the component forming step3after performing the preliminary forming step2based on this embodiment. The results are shown in Tables 2 and 3.

Table 2 shows the evaluation results (propriety of forming) of the forming methods of Comparative Examples.

Table 3 shows the evaluation results (propriety of forming) of the forming methods of Examples of Invention.

In the tables, P pressure is a pad pressure and C pressure is a cushion pressure.

TABLE 2Determination of wrinkles590 material980 materialRecessedProjection1180 material1470 materialPCportionProjectionRecessedportionRecessedProjectionRecessedProjectionpres-pres-of topportion ofportion ofofportion ofportion ofportion ofportion ofsuresuresheetflangetop sheetflangetop sheetflangetop sheetflangeStep(t)(t)portionportionportionportionportionportionportionportionComparativeForm——xΔxxxxxxExamplesPad form20—○Δ○x○x○xDrawing—50Δ○x○x○x○

TABLE 3Determination of wrinkles590 material980 material1180 material1470 materialRe-Pro-Re-Pro-Re-Pro-Re-Pro-StepcessedjectioncessedjectioncessedjectioncessedjectionPrelim-Com-Pportionportionportionportionportionportionportionportioninaryponentpres-ofofofofofofofofFirstSecondformingformingsuretop sheetflangetop sheetflangetop sheetflangetop sheetflangeBeadNo.beadbeadstepstep(t)portionportionportionportionportionportionportionportionshape122FormForm—○○○○○○○○FormPad20○○○○○○○○form212FormForm—Δ○x○x○x○FormPad20○○○○○○○○form3—2FormForm—x○x○x○x○FormPad20○○○○○○○○form42—FormForm—○Δ○x○x○xFormPad20○Δ○Δ○x○xform522FormForm—○Δ○x○x○xFormPad20○Δ○Δ○Δ○xform62—FormForm—○x○x○x○xFormPad20○Δ○x○x○xform722FormForm—○○○○○○○○FormPad20○○○○○○○○form

Herein, the evaluation of press formed products was visually performed and was performed in three grades of “∘”, “Δ”, and “x”. The evaluations are shown in Tables 2 and 3.

Specifically, the evaluation was performed as follows: “x” when significant wrinkles were generated, “Δ” when no significant wrinkles were generated but slight wrinkles were formed, and “∘” when no wrinkles were generated.

COMPARATIVE EXAMPLES

In the forming methods of Comparative Examples, as shown in Table 2, when steel sheets with a tensile strength of 980 MPa or more were used, significant wrinkles were generated in at least either the top sheet portion1A or the flange portion1C.

FIG.9illustrates an example of the generation of wrinkles in the top sheet portion1A and the flange portion1C in the case of the stamping using the1180material in Comparative Examples.

Examples of Invention

On the other hand, it was found in Examples of Invention that the generation of wrinkles was improved in the sites where the first beads4aor the second beads4bwere given as compared with Comparative Examples as shown in Table 3.

Herein, the shape after the preliminary forming step2in each Example of Invention is described.

No. 1 is an example of giving the curved shape and giving the first beads4aand the second beads4bcontaining a full bead to the first bent portion1dand the second bent portion1e, respectively.

The height of the beads4a,4bis five times the sheet thickness. The same applies to the other Examples of Invention.

No. 2 is an example of giving the curved shape, giving the first beads4acontaining a half bead to the first bent portion1d, and giving the second beads4bcontaining a full bead to the second bent portion1e.

No. 3 is an example of giving the curved shape, not forming the first beads4ain the first bent portion1d, and giving the second beads4bcontaining a full bead to the second bent portion1e.

No. 4 is an example of giving the curved shape, forming the first beads4acontaining a full bead in the first bent portion1d, and not forming the second beads4bin the second bent portion1e.

No. 5 is an example of giving the curved shape, giving the first beads4acontaining a half bead to the first bent portion1d, and giving the second beads4bcontaining a half bead to the second bent portion1e.

No. 6 is an example of not giving the curved shape, forming the first beads4acontaining a full bead in the first bent portion1d, and not forming the second beads4bin the second bent portion1e.

No. 7 is an example of giving the curved shape, partially giving the first beads4acontaining a full bead only to the position of the recessed curved portion10A in the first bent portion1d, and partially giving the second beads4bcontaining a full bead along the longitudinal direction only to the position of the projecting curved portion10B in the second bent portion1e. In No. 7, the position where the curved portion10A is formed, which is a position for providing the first beads4a, and the position where the projecting curved portion10B, which is a position for providing the second beads4b, are different from each other in the longitudinal direction.

As is understood from No. 1, when the curved shape was given and the first beads4aand the second beads4beach containing a full bead were given to the first bent portion1dand the second bent portion1e, respectively, no wrinkles were generated in the top sheet portion1A and the flange portion1C.

At this time, even when the first beads4aand the second beads4beach containing a full bead were partially given to only a region where the generation of wrinkles was estimated as in No. 7, no wrinkles were generated in the top sheet portion1A and the flange portion1C.

When the first beads4acontained a half bead and the second beads4bcontained a full bead as in No. 2, no wrinkles were generated in the flange portion1C but, in the stamping, wrinkles were generated in the top sheet portion1A. This is because an improvement of the shape rigidity on the top sheet portion1A side was lower than that in No. 1. However, the degree of wrinkles in the top sheet portion1A was milder than that in Comparative Examples (Table 2), and, even in the case of the half bead, a wrinkle reduction effect was observed.

It was also found that the generation of wrinkles in the flange portion1C was able to be suppressed when only the second beads4bwere provided as in No. 3.

It was also found that the generation of wrinkles in the top sheet portion1A was able to be suppressed when only the first beads4awere provided as in No. 4.

When the first beads4acontained a full bead and the second beads4bcontained a half bead as in No. 5, no wrinkles were generated in the top sheet portion1A but wrinkles were generated in the flange portion1C. This is because an improvement of the shape rigidity on the flange portion1C side was lower than that in No. 1. However, the degree of wrinkles in the flange portion1C was milder than that in Comparative Examples (Table 2), and, even in the case of the half bead, a wrinkle reduction effect was observed.

Herein, the description is given with reference to a limited number of embodiments, but the scope of the invention is not limited thereto and modifications of each embodiment based on the disclosure above are obvious to those skilled in the art.

The entire contents of JP 2020-039600 A (filed Mar. 9, 2020), for which this application claims priority, form part of this disclosure by reference.

REFERENCE SIGNS LIST

1pressed component shape1A top sheet portion1B side wall portion1C flange portion1D,1E edge line portion1dfirst bent portion1esecond bent portion2preliminary forming step (first preliminaryforming step, second preliminary forming step)2A first step2B second step3component forming step (first componentforming step, second component forming step)4metal sheet4afirst bead4bsecond bead6first estimation region acquisition unit7second estimation region acquisition unit10,10A,10B curved portion