Press Forming Apparatus and Production Method for Formed Product

The present invention relates to a press forming apparatus and a production method for a formed product.

From the viewpoint of weight reduction and higher strength of automobiles, formed products made of high-tensile strength steel sheets have been used for structural members of a vehicle body (for example, members that constitute frames). Specifically, for example, a formed productthat has a closed sectional shape as illustrated inand a hat-shaped formed productas illustrated inare used.

The formed productthat has a closed sectional shape illustrated inincludes plate-like flange portionsandvertical wall portionsandand a top plate portionThe formed producthas a closed sectional shape, and the flange portionand the top plate portionare provided to face each other and the vertical wall portionand the vertical wall portionare provided to face each other.

The formed productdescribed above can be produced by using, for example, roll forming or press forming. However, when roll forming is used as disclosed in Patent Document 1, it is necessary to arrange a plurality of rollers in line, which leads to a large forming apparatus.

In the meantime, when press forming is used, it is possible to construct a smaller forming apparatus than the case of using roll forming. However, to produce a formed product that includes a flange portion facing a top plate portion as in the formed product, a problem of the requirement of a core or an increase in the number of processes arises. In this case, production efficiency for formed products degrades.

Here, the hat-shaped formed productillustrated incan be produced without using a core through typical bending forming or draw forming using well-known dies. However, as illustrated in, in the case in which protruding portionsand(for example, hollow cylindrical portions formed by burring) that protrude inward are provided on a pair of vertical wall portionsandthe protruding portionsandmust be prevented from contacting a die during shaping. It is therefore difficult to produce the formed productthat includes the protruding portionsandthrough typical bending forming or draw forming using well-known dies. Note that the protruding portionsandmay also be referred to as recessed portions because they are viewed as recessed portions from outside.

Accordingly, an objective of the present invention is to provide a press forming apparatus and a production method, with which formed products can efficiently be produced.

According to the present invention, it is possible to efficiently produce formed products.

A press forming apparatus and a production method for a formed product according to embodiments of the present invention will now be described with reference to drawings.

First, a formed product produced by using a press forming apparatus according to a first embodiment of the present invention will be briefly described.is a view illustrating an example of a formed product produced by using the press forming apparatus according to the first embodiment of the present invention.

As illustrated in, a formed producthas a closed sectional shape. In the embodiment, the formed productincludes plate-like flange portionsandplate-like vertical wall portionsandand a top plate portionThe flange portionsandand the top plate portioneach have a flat plate shape.

In the embodiment, the flange portionis overlaid on the flange portionsuch that the formed producthas a closed sectional shape. The vertical wall portionis provided to extend upward in a bent manner from an edge of the flange portionThe vertical wall portionis provided to extend upward in a bent manner from an edge of the flange portionon the flange portionThe top plate portionis provided to connect an upper edge of the vertical wall portionwith an upper edge of the vertical wall portion

In the embodiment, the vertical wall portionsandand the top plate portionare curved in an arc shape when viewed from above (when viewed from the thickness direction of the top plate portion). In the flange portionfour through-holes(see) for inserting support portionsdescribed later (see) are formed in a portion that faces the top plate portion

is a schematic view illustrating a press forming apparatus according to the first embodiment of the present invention. More specifically,illustrates a press forming apparatus that can produce the formed productillustrated in.

Here, in, when a blank is subjected to press forming, a direction in which a first die set (punch) or a second die set (die) moves is indicated by an arrow X (hereinafter, denoted as a “press direction X”), and the width direction of the press forming apparatus is indicated by an arrow Y (hereinafter, denoted as a “width direction Y”). The width direction Y is a direction perpendicular to the press direction X. Furthermore, a direction that intersects the press direction X and the width direction Y is indicated by an arrow Z (hereinafter, denoted as an “intersecting direction Z”). In the embodiment, the intersecting direction Z is a direction perpendicular to the press direction X and the width direction Y.

Although detailed description will be omitted, materials as in well-known dies can be used to produce each component of the press forming apparatus. Each component of the press forming apparatus can be driven by drive mechanisms as in well-known press machines (electric cylinder, hydraulic cylinder, gas cushion apparatus).

As illustrated in, a press forming apparatusaccording to the embodiment includes a first die setprovided on one side in the press direction X and a second die setprovided on the other side in the press direction X. That is, the first die setand the second die setare provided in positions to face each other in the press direction X. The first die setand the second die setperform relative movement in the press direction X. In the embodiment, the first die setincludes a punch, and the second die setincludes a dieand a pad.

is a schematic view illustrating a positional relationship among the punch, the die, and the pad. Here,is a view of the press forming apparatusviewed from above. As illustrated inand, the punchincludes a first support surfaceand a punch portionthat protrudes from the first support surface. In the embodiment, the first support surfacefaces the other side (second die setside) in the press direction X. The punch portionprotrudes from the first support surfacetoward the other side in the press direction X. When viewed from the second die setside in the press direction X, the punch portionfaces a wall surfaceof the die, which will be described later. In the embodiment, the punch portionincludes a plurality of support portionsthat protrude from the first support surfacetoward the other side in the press direction X. The support portionmay be referred to as a protruding portion.

The support portionsare spaced apart from each other and provided to be aligned in a curved shape when viewed from the second die setside in the press direction X. In the embodiment, each support portionis formed in a circular column shape to have a side surfaceof a circular section. Note that the shape of the support portionillustrated inis only one example and the shape of the support portionis not limited to the above example. As illustrated indescribed later, although it is preferable that the top portion of each support portionhas a flat shape, it may have a spherical crown shape.

In the embodiment, the side surfaceof the punch portionis constituted of a plurality of side surfacesof the plurality of support portions. When viewed from the second die setside in the press direction X, the side surfaceof the punch portionincludes an openingopened on the wall surfaceside of the die, which will be described later. In the embodiment, the side surfaceof the punch portionincludes a plurality of openingsIn the embodiment, the side surfacesof two adjacent support portionsare arranged so as to be spaced apart with the openingin between. In other words, two adjacent support portionsare arranged so as to be spaced apart with the openingin between. Here, in the embodiment, the openingis also opened on the second die setside in the press direction X. Furthermore, in the embodiment, the openingis formed to pass through between two adjacent support portionsin the width direction Y.

The first support surfaceextends on both sides of at least each support portionin the intersecting direction Z. As illustrated in, in the embodiment, the first support surfaceextends at least between the support portionsand on both sides of the plurality of support portionsin an arrangement direction A of the plurality of support portions. Note that, in the present specification, the arrangement direction A refers to a direction along a line (a curve in the example of) obtained by connecting the centers of the support portionswhen viewed from the second die setside (above) in the press direction X.

As illustrated in, the dieincludes a press surfaceand a wall surfacethat is continuous with the press surface. In the embodiment, the press surfacefaces the one side (first die setside) in the press direction X. The wall surfaceextends from an edge of the press surfaceto the other side (opposite to the first die set) in the press direction X. The press surfaceis provided on one side of the punch portion(the plurality of support portions) in the width direction Y. In the embodiment, the press surfaceis disposed so as to be out of position from a position to face the punch portionin the press direction X. The wall surfaceis positioned between the punch portion(the plurality of support portions) and the press surfacein the width direction Y.

The press surfaceand the wall surfaceare provided, with respect to each support portion, to extend from the one side to the other side of the support portionin the intersecting direction Z. In the embodiment, as illustrated in, the press surfaceand the wall surfaceare provided to extend along the arrangement direction A and from one side to the other side of the plurality of support portionsin the arrangement direction A. Furthermore, in the embodiment, when viewed from the first die setside in the press direction X, the wall surfaceis curved in an arc shape to protrude toward the one side in the width direction Y.

Referring to, in the press direction X, the dieis provided to be capable of approaching and withdrawing relative to the first support surfaceof the punch. That is, the press surfaceand the wall surfaceare capable of approaching and withdrawing relative to the first support surfacein the press direction X.

As illustrated in, the padis disposed in a position to face the punch portion(the plurality of support portions) in the press direction X. In the embodiment, the padincludes a second support surfacethat faces the punch portion(the plurality of support portions) in the press direction X. The second support surfaceis provided, with respect to each support portion, to extend from the one side to the other side of the support portionsin the intersecting direction Z. In the embodiment, as illustrated in, the second support surfaceis provided to extend from the one side to the other side of the plurality of support portionsin the arrangement direction A.

Referring to, in the press direction X, the padis provided to be capable of approaching and withdrawing relative to the punch portion(the plurality of support portions) of the punch. That is, the second support surfaceis capable of approaching and withdrawing relative to the plurality of support portionsin the press direction X.

Next, a production method for a formed product will be described. In the production method according to the embodiment, a pre-processed blank is subjected to press forming by using the press forming apparatusdescribed above to produce the formed product. The following is a specific description.

is a view illustrating a blank used as a starting material in the production method according to the embodiment. As illustrated in, a blankincludes a first plate-like portiona second plate-like portionand a third plate-like portion

The first plate-like portionhas a flat plate shape. A plurality of through-holesis formed in the first plate-like portionIn the embodiment, the plurality of through-holesis provided such that they correspond to the plurality of support portions(see) of the first die set(see). Here, the through-holeis not limited to circular in shape and may be formed in any size and shape to the extent that the support portioncan be inserted. Accordingly, the through-holemay have any other shape such as an elliptic shape or a polygonal shape. The relationship between the through-holeand the support portionwill be described later.

The second plate-like portionhas a flat plate shape and is provided to face the first plate-like portionin the thickness direction of the first plate-like portionFurthermore, the second plate-like portionis provided so as to be spaced apart from the first plate-like portionin the thickness direction of the first plate-like portionThe third plate-like portionis provided to extend in the thickness direction of the first plate-like portionso as to connect an edge of the first plate-like portionwith an edge of the second plate-like portionIn the embodiment, the third plate-like portionis a portion corresponding to the vertical wall portion(see) of the formed product(see) and is curved in an arc shape when viewed from the thickness direction of the first plate-like portion

Although the material and the dimensions of the blankare not particularly limited, for example, a sheet material (for example, steel sheet) that has a tensile strength of 270 MPa or more and a thickness of 0.5 to 5 mm can be used to produce the blank. Although the production method for the blankis not particularly limited, it is possible to produce the blank, for example, by using a well-known press forming apparatus to subject a plate material with a plurality of through-holesformed therein to press forming.

shows views for describing the production method according to the embodiment. Here, in, components of the press forming apparatusand the blankare simplified. Furthermore,illustrates the press forming apparatusand the blankas viewed from the intersecting direction Z.

When the blankis subjected to press forming, as illustrated in(a), the blankis first placed on the first support surfaceof the first die setsuch that the punch portion(the plurality of support portions) crosses the first plate-like portionfrom first die setside in the press direction X and supports the second plate-like portionMore specifically, the first plate-like portionis supported by the first support surfacesuch that the third plate-like portionis located on the other side of the punch portion(the plurality of support portions) in the width direction Y and the support portionsof the punch portionprotrude through the through-holestoward the second plate-like portionside with respect to the first plate-like portion

Next, as illustrated in, the pad(second support surface) is moved to the one side (first die setside) in the press direction X, so that the second plate-like portionis clamped between the punch portion(the plurality of support portions) and the second support surface. Note that, in the embodiment, the state illustrated incorresponds to the state of “supporting the first plate-like portion by the first support surface from the side of the first die set and supporting the second plate-like portion by the punch portion crossing the first plate-like portion in the press direction from the side of the first die set”.

Next, as illustrated in the views (b), (c), and (d) of, the die(press surface) is moved from the other side (second die setside) to the one side (first die setside) in the press direction X relative to the top portion of the punch portion(the plurality of support portions). Consequently, a portion of the second plate-like portionon the one side with respect to the punch portion(the plurality of support portions) in the width direction Y is pressed to the one side (first die setside) in the press direction X. As a result, the second plate-like portionis subjected to bending deformation and the formed productis completed. In the embodiment, at a forming bottom dead center of the relative movement between the first die setand the second die setin the press direction X (the state illustrated in), the wall surfaceof the diefaces the side surfaceof the punch portionwith part of the second plate-like portionin between. Furthermore, at the forming bottom dead center, the wall surfaceof the diefaces at least one openingin the width direction Y. In the embodiment, at the forming bottom dead center, the wall surfacefaces the plurality of openingsin the width direction Y.

Finally, the second die set(dieand pad) is moved to the other side in the press direction X, and the formed productis taken out from the press forming apparatus.

As described above, according to the press forming apparatusaccording to the embodiment, when the formed product, which includes a plate-like portion (flange portion) facing the top plate portionis to be produced from the blank, the portion to be the top plate portionin the second plate-like portionof the blankcan be supported by the punch portion(support portions) from the first plate-like portionside. This makes it possible to shape the vertical wall portionand the flange portionby simple bending with the press surfaceand the wall surfaceof the second die set. In this case, it is not necessary to use a core to produce the formed product, and it is possible to avoid an increase in the number of processes. As a result, it is possible to efficiently produce the formed product.

Here, when the formed productproduced as described above is to be used as a structural member for automobile, the through-holemay be utilized as a drainage hole or may be closed by a patch or the like. Furthermore, to secure sufficient rigidity of surrounding portions of the through-hole, the portion at which the through-holeis formed may be subjected to burring, a patch or the like for stiffening may be applied to peripheral edge portions of the through-hole, or the wall thickness may be increased in the peripheral edge portions of the through-hole.

The shape of the formed productis not limited to the above example. For example, the vertical wall portionsandand the top plate portionmay be curved such that they protrude in the opposite direction to the vertical wall portionsandand the top plate portionillustrated inwhen viewed from the thickness direction of the top plate portionIn this case, the shape of any portion of the press forming apparatusmay be altered in any way depending on the shape of the formed product. Specifically, for example, as illustrated in, when viewed from the second die setside in the press direction X, the plurality of support portionsis arranged such that they exhibit a curve that protrudes toward the other side in the width direction Y, and the wall surfaceis provided to protrude toward the other side in the width direction Y.

Furthermore, the vertical wall portionsandand the top plate portionmay also be formed to extend in a linear shape when viewed from the thickness direction of the top plate portionIn this case, although not illustrated, for example, when viewed from the second die setside in the press direction X, the plurality of support portionsis arranged such that they are aligned in a linear shape along the intersecting direction Z, and the wall surfaceis provided to extend in parallel along the intersecting direction Z.

Furthermore, one of the vertical wall portionsandmay be curved in an arc shape and the other may be formed in a linear shape when viewed from the thickness direction of the top plate portionStill in this case, the plurality of support portionsmay be arranged depending on the shape of the vertical wall portionsand

Note that the distance between adjacent support portions, the arrangement of the plurality of support portions, the number of support portions, and the shape and the dimensions of the support portionare not limited to the above example and may be altered in any way depending on the shape, the dimensions, and the like of the formed product to be produced. For example, as illustrated in, the plurality of support portionsmay be provided to align in the width direction Y. Furthermore, as illustrated in, the punch portionof the first die setmay be constituted of one support portion. In this case, only one through-hole may be formed in the first plate-like portionof the blank(see) for inserting one support portion.

Although in the above-described embodiment, description has been made to the case of producing the formed productthat includes the flange portion(see), as illustrated in, a formed productwith no flange portionmay be produced. The same applies to embodiments described later. Here, in, the view (a) illustrates the press forming apparatusin a state in which the second plate-like portionof the blankis clamped by the punch portion(support portions) and the second support surface, the view (b) illustrates the press forming apparatusin a state in which a portion of the second plate-like portionon the one side with respect to the punch portion(support portions) in the width direction Y is pressed to the one side (first die setside) in the press direction X by the press surface, and the view (c) illustrates the press forming apparatuswhen the formed productis to be taken out (during release).

Furthermore, while in the above-described embodiment, part of the flange portionand part of the flange portionare overlaid on each other such that the formed producthas a closed sectional shape, the formed productmay not have a closed sectional shape. For example, a clearance may be formed between the flange portionand the flange portion(vertical wall portion) in a direction in parallel to the width direction of the top plate portionas the formed productillustrated in. Here, the formed productillustrated incan be produced as described below, for example.

shows views for describing a production method for the formed productof. When the formed productinis to be produced, as illustrated in, the blankis placed on the first support surfaceof the first die setas in the case of producing the formed productin. However, the length in the width direction Y of the first plate-like portion(see) of the blank(see) used when the formed productinis to be produced is shorter than the length in the width direction Y of the first plate-like portion(see) of the blank(see) used when the formed productinis to be produced. Furthermore, any through-hole(see) may not be formed in the first plate-like portionof the blank(see) used when the formed productinis to be produced.

In the embodiment, the first plate-like portionis supported by the first support surfacesuch that third plate-like portionis located on the other side of the punch portion(the plurality of support portions) in the width direction Y and the plurality of support portionsprotrudes toward the second plate-like portionside with respect to the first plate-like portionon the one side of the first plate-like portionin the width direction Y.

Next, as illustrated in, the pad(second support surface) is moved to the one side (first die setside) in the press direction X, so that the second plate-like portionis clamped between the punch portion(the plurality of support portions) and the second support surface. Note that, in the embodiment, the state illustrated incorresponds to the state of “supporting the first plate-like portion by the first support surface from the side of the first die set and supporting the second plate-like portion by the punch portion crossing the first plate-like portion in the press direction from the side of the first die set”.

Next, as illustrated in the views (b), (c), and (d) of, the die(press surface) is moved from the other side (second die setside) to the one side (first die setside) in the press direction X relative to the top portion of the punch portion(the plurality of support portions). Consequently, a portion of the second plate-like portionon the one side with respect to the plurality of support portionsin the width direction Y is pressed to the one side (first die setside) in the press direction X, and the formed productillustrated inis completed.