JP2016193442A - Press-molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press-molding device applicable even to any manufacture of a circular pipe and a square pipe, without causing a flaw on a surface of a metallic plate material as a workpiece, and without causing even positional dislocation of a bending line in bending processing time such as square pipe manufacturing time.SOLUTION: A press-molding device of the present invention is the press-molding device for bending a metallic plate material, and comprises an upper metal mold and two rotary rolls provided in a lower part of the upper metal mold and placed on a roll holder. The respective two rotary rolls include a plate-like support part having a plurality of projection parts of extending in a line shape in the axial direction of the rotary rolls, and a movable angle range formed against a horizontal plane by a surface of contacting with an apex part of the plurality of projection parts, is 0-60°.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an apparatus for press forming used when manufacturing a circular tube, a square tube or the like from a metal plate material such as a steel plate. In addition, although the metal plate material made into object by this invention is mentioned as a representative material, it is the meaning containing metal plate materials, such as not only this but an aluminum plate, a copper plate, or a titanium plate. Below, a steel plate is taken up as a typical metal plate material, and explanation is advanced centering on the case where this is press-molded and a square steel pipe is manufactured.

  In recent years, for the purpose of reducing construction costs, application to column materials of round steel pipes and square steel pipes has been promoted. Among these, a square steel pipe is a so-called “roll-formed square steel pipe” in which a steel sheet is once formed into a round steel pipe, and the seam portion is welded to the round steel pipe to form a square by further roll forming. . Such a roll-formed square steel pipe is generally applied to a relatively thin steel plate having a thickness of about 6 to 22 mm. On the other hand, when manufacturing a square steel pipe using a thick plate having a steel plate thickness exceeding 20 mm, the corner portion of the square steel pipe is press-formed, and then the seam portion is welded. "Is common.

  The manufacturing procedure of the above press-formed square steel pipe will be described with reference to the drawings. First, as shown in FIG. 1, two bending lines 3 and 3 indicated by broken lines are set in a portion having a width W / 4 from both ends of a steel plate 10 having a width W. Then, both sides of the steel plate 10 are bent by press forming along the bending lines 3 and 3. At this time, as shown in FIG. 2, while the steel plate 10 is supported by the two rotating rolls 2 and 2, the tip portion of the upper mold 1 is applied to the bending line 3 from the top of the steel plate 10 [FIG. 2 (a)]. Then, the upper mold 1 is pushed down, and the steel plate 10 is bent into a V shape and press-formed [FIG. 2 (b)]. Although not shown in FIG. 2, the upper mold 1 is a long object corresponding to the length direction of the steel plate 10.

  The press molding as described above is performed on both sides along the bending lines 3 and 3 to obtain a half-shaped molded part 4 as shown in FIG. A pair of such molded parts 4 is prepared, and as shown in FIG. 3B, the press-formed square steel pipe 5 is manufactured by stacking two facing parts 6 and 6 so as to face each other.

  In the manufacturing procedure shown in FIGS. 1 to 3, a press-formed square steel pipe 5 is manufactured by forming a pair of half-shaped molded parts 4 and then welding the two welded portions 6 and 6. The procedure for manufacturing the press-formed square steel pipe 5 is not limited to the above-described procedure. For example, as shown in FIG. 4A, a single steel plate 10 is press-formed along four bend lines 3 to form a square steel tube. As shown in FIG. 4B, a procedure for manufacturing a press-formed square steel pipe 5 by welding at one welded portion 6 is also known.

  Whichever manufacturing procedure is employed, it is necessary to effectively press the steel sheet along the predetermined bending line 3. However, when the press-formed square steel pipe 5 is manufactured by the press-forming apparatus having the rotating roll as described above, there are the following problems.

  FIG. 5 is a diagram for explaining a situation in which a problem occurs when press molding. FIG. 5A basically corresponds to FIG. 2A described above except that the holders 7 and 7 holding the two rotating rolls 2 and 2 are shown, and the corresponding parts are the same. The reference numerals are attached.

  In order to produce the press-formed square steel pipe 5 (hereinafter, simply referred to as “square steel pipe 5”) as described above, when the steel plate 10 is press-formed, the position of the bending line 3 is in the width direction of the steel plate. It is asymmetric. Moreover, the two rotating rolls 2 and 2 are only put on the holders 7 and 7, respectively, and the rotating properties of the rotating rolls 2 and 2 are unstable. Therefore, a rotation amount difference occurs between the two rotary rolls 2 and 2 during press molding. As a result, it is not always press-molded at the position of the normal bending line 3 shown in FIG. 2 (b), and the position A where the position of the bending line 3 is slightly shifted as shown in FIG. 5 (b). Thus, the steel plate 10 is bent. When such a situation occurs, a regular press-formed product cannot be manufactured stably. Further, since the amount of deviation is not stable, press molding cannot be performed in anticipation of the amount of deviation.

  In a conventional press molding apparatus, a configuration that does not use a rotating roll is also known. That is, the upper mold and the lower mold having a groove portion corresponding to the tip shape of the upper mold are press-molded by sandwiching the steel sheet, and are pressed into a shape corresponding to the upper mold and the lower mold. There is a device. If press molding is performed with an apparatus having such a configuration, problems such as those when a rotating roll is used are unlikely to occur. However, in the case of press molding using the apparatus having such a configuration, the steel plate is pressed against the groove shoulder portion of the lower mold at the initial stage of press molding, and the surface of the steel plate is likely to be crushed or scratched by surface contact. There is another problem. Such wrinkles become conspicuous on the surface of the steel sheet, and after that, it is necessary to adjust the surface properties of the steel sheet by a grinder treatment.

  On the other hand, when manufacturing a press-formed circular steel pipe (hereinafter sometimes simply referred to as “circular steel pipe”), the shape of the tip of the upper mold 1 shown in FIGS. Is generally press-molded using the same apparatus as described above. However, when a circular steel pipe is manufactured by press forming, it is necessary to press form while feeding in the width direction at a pitch of several tens of millimeters from one end of the steel plate to the other end. In order to carry out such “feeding”, it is common to provide a rotary drive mechanism in association with the rotary roll, and press forming while controlling the feed amount of the rotary roll by this rotary drive mechanism.

  The press forming apparatus for manufacturing a circular steel pipe having a rotating roll is common except for the apparatus configuration for manufacturing a square steel pipe, the difference in the shape of the tip of the upper mold 1, and the presence or absence of a rotation drive mechanism. Yes. For these reasons, it is expected to realize a press forming apparatus that can be applied to the production of both square steel pipes and round steel pipes. However, in the past, the press forming apparatus using a rotating roll has not realized a press forming apparatus that can be applied to the production of either a square steel pipe or a circular steel pipe.

  Various press forming apparatuses have been proposed so far. For example, Patent Document 1 proposes a press molding apparatus as shown in FIG. This press molding apparatus is called a rocker die system. The press forming apparatus shown in FIG. 6 is for manufacturing a circular steel pipe by a so-called “UO press method”. In this apparatus, as shown in FIG. 6, a punch 11 that moves in a vertical direction and a rocker die 13 that is placed on a rocker bracket 12 and that can rotate around a shaft 18, and the distance between the left and right rocker dies 13, 13 is as follows. By moving the left and right rocker brackets 12 and 12, they are set at appropriate intervals in advance.

  At the initial stage of press molding, the steel plate 16 as the workpiece is bent along the punch 11 with the upper shoe 14 of the rocker die 13 as a fulcrum. Next, when the steel plate 16 comes into contact with the lower shoe 15 of the rocker die as a fulcrum, the rocker die 13 rotates about the shaft 18 through the load from the punch 11 as shown by the broken line in FIG. Is bent along the punch 11, and the press molding is finished while considering the spring back after unloading.

  In this press molding apparatus, the upper shoe 14 and the lower shoe 15 of the rocker die 13 are arranged on an inclined surface, and are configured to sequentially contact each other during press molding. At the end of press molding, the angle formed between the surface including the upper shoe 14 and the lower shoe 15 of the rocker die 13 and the horizontal plane is set to be larger than 90 ° in consideration of the springback. The upper shoe 14 and the lower shoe 15 are fixed. However, it is disclosed that the upper shoe 14 and the lower shoe 15 may be a rotary type in order to reduce the frictional resistance with the steel plate.

  The press forming apparatus shown in FIG. 6 is an apparatus for manufacturing a circular steel pipe basically by the “UO press method”. In such a configuration, only the upper shoe 14 is in contact with the steel plate in the initial stage of molding, and the positioning of the steel plate becomes unstable. Even if the steel plate is diverted to an apparatus for forming a V-shape, the position of the bending line tends to shift, and the square shape. It cannot be applied as an apparatus for manufacturing steel pipes. Further, although it is disclosed that the upper shoe 14 and the lower shoe 15 shown in FIG. 6 may be of a rotary type, the configuration is different from the configuration in which the rotating roll is held by the roll holder.

  When press forming is performed using an apparatus that does not use a rotating roll, the steel plate is pressed against the groove shoulder of the lower mold at the initial stage of press forming, and the surface of the steel plate is ground or scratched. As described above, there is another problem that is easily attached. Therefore, in recent years, instead of arranging the lower mold, the steel plate 10 is supported by the rotating roll 2 as shown in FIGS. 2 and 5 and pressed from above the steel plate 10 by the upper mold 1 and pressed. Molding methods are mainstream. However, in such a system, when a square steel pipe is manufactured by press forming, the displacement of the bending line 3 due to the difference in the rotation amount of the rotary rolls 2 and 2 as described above also occurs as described above. It is.

  For example, a technique as disclosed in Patent Document 2 has been proposed as a press forming apparatus that does not use a rotating roll and does not wrinkle the surface of a plate material such as a steel plate. The configuration of such a press molding apparatus is shown in FIG. In this press molding apparatus, as shown in FIG. 7A, a lower mold 35 is provided on an upper part of a lower table 23 that moves up and down. The lower mold 35 extends in the longitudinal direction at the center of the upper surface of the lower mold main body 21 to form a U-shaped relief groove 24, and between the relief groove 24 and both shoulders 21 </ b> A of the lower body 21. Arc-shaped grooves 22 are formed on both sides. A half-moon shaped rocking member 27 is mounted in the arc-shaped groove 22, and a plate material receiving member 25 rides on a flat surface of the upper surface of the rocking member 27, and the plate material receiving member 25, the rocking member 27, Are brought into contact with each other at a slope surface 25A formed on the plate receiving member 25, and the swinging member 27 is inclined.

  In such a configuration, as shown in FIG. 7B, as the press bending process (hereinafter, simply referred to as “bending process”) proceeds, the contact surface between the back surface of the plate material 26 and the upper surface of the plate material receiving member 25. Is larger than the frictional force of the contact surface between the gradient surface 25A of the plate material receiving member 25 and the swing member 27, the gradient surface 25A of the plate material receiving member 25 slides on the upper surface of the swing member 27 and is bent. Then, the plate material receiving member 25 follows. For this reason, no scum or the like occurs in the plate material 26 during bending. In addition, since the press molding apparatus having such a configuration basically does not use a rotating roll, the above-described problem of deviation does not occur.

JP 54-132458 A JP-A-8-57541

  In the press molding apparatus shown in FIG. 7, the lower mold 35 and the plate material 26 are not in direct contact with each other, so that the problem of wrinkles due to the lower mold 35 is solved. Further, since the plate material 26 as a workpiece is supported in a state of surface contact by the plate material receiving member 25, there is no problem that the position of the bending line is shifted during bending.

  However, in such a press forming apparatus, the half-moon shaped rocking member 27 is mounted in the arc-shaped groove 22, and the arc-shaped groove 22 is used in the press forming apparatus for manufacturing a circular steel pipe. Cannot be used as a roll holder. Therefore, in order to manufacture a circular steel pipe using such a press molding apparatus, it is necessary to replace all the parts corresponding to the lower mold.

  The present invention has been made in view of the circumstances as described above, and its purpose is not to cause wrinkles on the surface of a metal plate material as a workpiece, and at the time of bending as in the production of a rectangular tube. It is an object of the present invention to provide a press molding apparatus that can be applied to the production of both circular tubes and rectangular tubes without causing any misalignment of the bending line.

The press molding apparatus of the present invention that has solved the above problems is a press molding apparatus for bending a metal plate material,
The upper mold,
Provided at the bottom of the upper mold, and has two rotating rolls mounted on a roll holder;
Each of the two rotating rolls has a plate material support portion having a plurality of convex portions extending linearly in the axial direction of the rotating roll,
The movable angle range which the surface which contact | connects the top part of the said some convex part makes with respect to a horizontal surface is 0-60 degrees, It is characterized by the above-mentioned.

  In the press molding apparatus of the present invention, the distance between the axes of the two rotary rolls and the distance between the two rotary rolls so that the distance that the tops of the plurality of convex portions slide on the surface during press molding is minimized. It is preferable to set the radius.

  The distance between the axes of the two rotating rolls set as described above is preferably 450 to 600 mm, and the radius of the two rotating rolls is preferably 12.5 to 50 mm. The thickness of the metal plate used at this time is preferably 10 to 60 mm.

  Most preferably, the metal plate material targeted by the press molding apparatus of the present invention is a steel plate.

  According to the present invention, there are an upper mold and two rotating rolls provided on a lower part of the upper mold and placed on a roll holder, each of the two rotating rolls being Since the plate material support portion having a plurality of convex portions extending linearly in the axial direction has a movable angle range of 0 to 60 ° with respect to the horizontal plane, the surface in contact with the top portions of the plurality of convex portions. In addition, it does not cause wrinkles on the surface of the metal plate material, does not cause bending line misalignment during bending as in the production of a square tube, and it can be used for the production of both round and square tubes. A press molding apparatus that can be applied can be realized.

FIG. 1 is an explanatory diagram showing a procedure for manufacturing a press-formed square steel pipe. FIG. 2 is an explanatory view showing a situation where both sides of the steel plate are bent by press forming. FIG. 3 is a view for explaining the shape of a molded part when a press-formed square steel pipe is manufactured. FIG. 4 is an explanatory view showing another manufacturing procedure of a press-formed square steel pipe. FIG. 5 is a diagram for explaining a situation in which a problem occurs during press molding. FIG. 6 is a schematic explanatory view showing an example of a press forming apparatus for manufacturing a circular steel pipe by a so-called “UO press method”. FIG. 7 is a schematic explanatory view showing an example of a conventional press molding apparatus. FIG. 8 is a schematic explanatory view showing an example of the press molding apparatus of the present invention. FIG. 9 is an explanatory view showing a state when bending is performed using the press molding apparatus of the present invention. FIG. 10 is a drawing-substituting photograph showing the situation of contact marks with the convex portion. FIG. 11 is a schematic explanatory diagram illustrating a configuration of a press forming apparatus of a comparative example. FIG. 12 is a drawing-substituting photograph showing the situation of scratches generated by surface contact when the press molding apparatus of the comparative example is used. FIG. 13 is a graph showing the relationship between the roll radius and the sliding distance when the distance L between the axes of the rotating roll is 450 to 600 mm and the thickness of the steel sheet is 10 mm. FIG. 14 is a graph showing the relationship between the roll radius and the sliding distance when the distance between the axes of the rotating rolls is 450 to 600 mm and the thickness of the steel sheet is 20 mm. FIG. 15 is a graph showing the relationship between the roll radius and the sliding distance when the distance between the axes of the rotating roll is 450 to 600 mm and the thickness of the steel sheet is 30 mm. FIG. 16 is a graph showing the relationship between the roll radius and the sliding distance when the distance between the axes of the rotating roll is 450 to 600 mm and the thickness of the steel sheet is 40 mm. FIG. 17 is a graph showing the relationship between the roll radius and the sliding distance when the distance between the axes of the rotating rolls is 450 to 600 mm and the plate thickness of the steel sheet is 50 mm. FIG. 18 is a graph showing the relationship between the roll radius and the sliding distance when the distance between the axes of the rotating rolls is 450 to 600 mm and the thickness of the steel sheet is 60 mm.

  The present inventor is based on a structure in which a metal plate is supported by two rotating rolls placed on a roll holder, and the surface of the metal plate is less likely to be crushed or scratched. In order to realize a press molding apparatus that does not cause the displacement of the bending line at the time of bending as described above and can be applied to the production of both circular tubes and square tubes, the present inventors have studied from various angles. As a result, each of the two rotating rolls has a plate material supporting portion having a plurality of convex portions extending linearly in the axial direction of the rotating roll, and this plate material supporting portion supports a metal plate material as a workpiece, And if the surface which touches the top part of the said several convex part was made into the movable angle range made with respect to a horizontal surface being 0-60 degrees, it discovered that the said objective was achieved wonderfully and completed this invention. . Hereinafter, the structure of the press molding apparatus of this invention is demonstrated in detail based on drawing.

  FIG. 8 is a schematic explanatory view showing an example of the press molding apparatus of the present invention. In FIG. 8, parts corresponding to those of the apparatus shown in FIG. The press forming apparatus shown in FIG. 8 is configured to manufacture a square steel pipe. In the press molding apparatus of the present invention, as shown in FIG. 8, each of the two rotary rolls 2, 2 has a plurality of convex portions 8 a, 8 b extending linearly in the axial direction of the rotary rolls 2, 2. Further, plate material support portions 9 and 9 for supporting the steel plate 10 as a metal plate material by the convex portions 8a and 8b are provided. The plate material support portions 9 and 9 may be fixedly provided on each of the rotary rolls 2 and 2, but may be formed integrally with the rotary rolls 2 and 2.

  In addition, although the top part of the convex parts 8a and 8b extending linearly is represented as a point in FIG. 8, it corresponds to the length of the steel plate 10 in the longitudinal direction (that is, the direction perpendicular to the paper surface of FIG. 8). It has a linear shape extending to Here, the “linear shape extending in the longitudinal direction” does not necessarily need to be a continuous linear shape, and may be an intermittent linear shape. In short, what is necessary is just to be comprised so that the length of the line | wire which connects the top part of a convex part can respond | correspond to the length of the steel plate 10. FIG. In such a configuration, the steel plate 10 and the tops of the convex portions 8a and 8b are in a line contact state. As described above, the plate material support portions 9 and 9 and the steel plate 10 are not in surface contact with each other, so that generation of wrinkles on the surface of the steel plate 10 by the plate material support portions 9 and 9 during press forming can be reduced.

  FIG. 9 shows a state when press molding is performed using the press molding apparatus of the present invention. While pressing the steel plate 10 from above by the upper mold 1, the steel plate 10 supported by the plate material support portions 9, 9 is bent into a V shape. At this time, following the rotation of the rotating rolls 2 and 2, the plate material support portions 9 and 9 are inclined. At the time of press forming, the steel plate 10 is supported by the tops of the plurality of convex portions 8a and 8b provided on the plate material support portions 9 and 9, respectively, so that the position of the steel plate 10 is stabilized and the position of the bending line 3 is maintained. Will not deviate from the target position. That is, when the steel plate 10 is tilted with the progress of press forming, the rotary rolls 2 and 2 are forcibly rotated, so that there is no difference in the amount of rotation between the two rotary rolls 2 and 2. The position of the bend line 3 does not deviate from the target position.

  In the state shown in FIG. 9, an angle θ (the range of this angle θ is “movable”) formed by the surfaces in contact with the tops of the plurality of convex portions 8 a and 8 b provided on the plate material support portions 9 and 9 with respect to the horizontal plane. Is called 60 ° or less. Further, the state shown in FIG. 8 is a state in which the angle θ is 0 °, that is, a state where the surfaces in contact with the tops of the convex portions 8a and 8b coincide with the horizontal plane. In the case of manufacturing a press-formed square steel pipe, the upper limit of the angle θ may be 45 ° or less. However, considering the reduction of springback, and considering the case where it is applied as a press forming apparatus for manufacturing a press-formed circular steel pipe. The upper limit was set to 60 ° or less. That is, in the press molding apparatus of the present invention, the angle θ is set so as to move within a range of 0 ° to 60 °.

  In the press molding apparatus shown in FIGS. 8 and 9, the protrusions provided on the plate material support portions 9 and 9 are each provided with two portions 8 a and 8 b, but the number of the protrusions 8 a and 8 b is two. However, the number is not limited to three and may be three or more. For example, the surface shape of the plate material support portions 9 and 9 on the side in contact with the steel plate 10 may be a wave shape in which a large number of linear protrusions are arranged in parallel. However, if the number of the convex portions 8a and 8b is excessively large, it becomes a state close to the surface contact and causes generation of surface flaws. Therefore, the number of the convex portions 8a and 8b of the plate material support portions 9 and 9 is If the steel plate 10 can be supported, it is preferable that the number is as small as possible. From such a viewpoint, it is preferable that the number of installation locations of the convex portions 8a and 8b is 5 or less in the plate material support portion 9.

  From the viewpoint of supporting the steel plate 10, the shape of the tops of the convex portions 8 a, 8 b of the plate material support portions 9, 9 may be tapered so as to be in line contact with the steel plate 10. However, if the shape is too sharp, the surface of the steel plate 10 tends to be wrinkled. From this point of view, the shape of the tops of the convex portions 8a and 8b of the plate material supporting portions 9 and 9 can be in line contact with the steel plate at the top of the convex portions 8a and 8b as shown in FIGS. It is preferable that the shape is gentle.

  The press forming apparatus shown in FIGS. 8 and 9 assumes a configuration for manufacturing a square steel pipe, but such a configuration can also be applied as a press forming apparatus for manufacturing a circular steel pipe. However, it is necessary to replace the tip portion with the upper mold 1 having a shape for manufacturing a circular steel pipe. In addition, when manufacturing a circular steel pipe, a rotary drive mechanism is required for feeding in the width direction at a pitch of several tens of millimeters from one end of the steel plate to the other end. This rotary drive mechanism is related to a rotary roll. Can be provided.

  In the press molding apparatus of the present invention, the steel plate 10 is supported by the tops of the plurality of convex portions 8a and 8b provided on the plate material support portions 9 and 9, respectively. Although the position 3 does not deviate from the target position, the tops of the protrusions 8a and 8b may still slide slightly from the predetermined position of the steel plate 10. The contact marks between the convex portions 8a and 8b and the steel plate 10 caused by this sliding are not accompanied by the phenomenon of the plate thickness, and there is a problem of the surface property of the product without performing the treatment with a grinder like a scratched surface. Does not occur. Still, from the viewpoint of making the appearance of the product beautiful, the distance that the tops of the plurality of protrusions slide on the steel plate surface during press forming (hereinafter sometimes simply referred to as “sliding distance”) is as much as possible. Smaller is preferable. FIG. 10 (drawing substitute photograph) shows an example of the situation of contact marks with the convex portion.

  FIG. 11 is a schematic explanatory diagram illustrating a configuration of a press forming apparatus of a comparative example. In this apparatus, the plate material support portions 9a and 9a are in a flat plate shape, and are not provided with a plurality of convex portions 8a and 8b as in the apparatus of the present invention. In such an apparatus, the steel plate 10 and the plate material support portions 9a and 9a are in surface contact with each other, so that scratches as described above are likely to occur. FIG. 12 (drawing substitute photograph) shows the state of scratches generated by surface contact when the press molding apparatus shown in FIG. 11 is used. As described above, such wrinkles have unevenness on the surface of the plate material, and then it is necessary to adjust the surface properties of the plate material by a grinder treatment.

  The inventor has also studied the distance L between the axes of the two rotary rolls 2 and 2 and the radius d of the rotary roll (see FIG. 8) so that the sliding distance can be minimized. As a result, the distance L between the axes of the two rotating rolls (hereinafter sometimes simply referred to as “distance L between axes”) and the radius d of the rotating roll (hereinafter, It has been found that the sliding distance can be minimized by setting the “roll radius d” (sometimes referred to simply as “roll radius d”) to an appropriate range. That is, in the press molding apparatus of the present invention, it is preferable to set the inter-axis distance L and the roll radius d so that the sliding distance of the tops of the plurality of convex portions is minimized.

  The distance L between the axes set as described above is preferably 450 to 600 mm, and the roll radius d is preferably 12.5 to 50 mm. These values are preferably set as described above within a thickness range described below (for example, about 10 to 60 mm), although depending on the thickness of the metal plate material. Further, since the forming load is determined by the strength, length, and thickness of the metal plate, the inter-shaft distance L and the roll radius d are selected within the range of the forming load capacity of the equipment. The molding load can be about 100 to 50000 tons (about 980 to 490000 kN) depending on various conditions, but the molding load assumed from the actual equipment capacity is about 5000 to 15000 tons (about 49000 to 147000 kN). The reason why the preferable ranges of the inter-axis distance L and the roll radius d are set as described above is as follows.

  First, when the distance L between the shafts becomes too small, the metal plate material is pushed into a narrow region, and the molding load increases accordingly. From such a viewpoint, it is preferable that the distance L between the shafts is at least 450 mm. More preferably, it is 480 mm or more. As the inter-shaft distance L is increased, the molding load can be reduced. However, if the inter-shaft distance L is excessively increased, the metal plate material may not be placed between the rotating rolls, and press molding may not be performed. Increasing the distance L between the shafts increases the pushing amount of the upper mold 1 to secure the angle θ, and the sliding distance of the convex portions 8a and 8b on the steel plate 10 increases accordingly. . From such a viewpoint, the inter-axis distance L is preferably 600 mm or less, and more preferably 570 mm or less. In consideration of the size of an actual square tube or circular tube, it is sufficient that the upper limit of the inter-axis distance L is 600 mm or less.

  On the other hand, the roll radius d is preferably as small as possible as the inter-axis distance L decreases and as the plate thickness of the metal plate increases. As a result of investigation by the present inventor, it has been found that the roll radius d capable of reducing the sliding distance is preferably about 12.5 to 50 mm while the inter-shaft distance L is set to 450 to 600 mm. A more preferable range of the roll radius d varies depending on the plate thickness.

  The press molding apparatus of the present invention can be applied to the production of either a press-formed square steel plate or a press-formed circular steel pipe. Of these, press-formed square steel plates are usually intended for cases where the plate thickness is relatively thick (for example, the plate thickness is 20 to 50 mm). However, the press forming apparatus of the present invention is not limited to such a plate thickness, but can be applied to a thickness (for example, 6 to 22 mm) or more of a metal plate material in the case of forming a roll-formed square steel plate. Alternatively, the press forming apparatus of the present invention can also be applied to press forming a thin steel plate having a thickness of less than 6 mm. Among these, the preferable range of plate | board thickness is 10-60 mm. Further, the preferable range of the plate thickness is the same when manufacturing a press-formed circular steel pipe.

  In the above description, the target metal plate material has been described mainly with respect to a steel plate. However, the present invention is not limited to the steel plate, but includes a metal plate material such as an aluminum plate, a copper plate, or a titanium plate. However, in order to effectively demonstrate the ease of bending by the press forming apparatus and the effects of the above apparatus configuration, that is, the effect of reducing surface wrinkles and shifting the position of the bending line, the target metal Most preferably, the plate material is a steel plate.

  Using the press molding apparatus of the present invention, the inter-shaft distance L and the roll radius d were investigated so that the sliding distance was minimized. In this investigation, the distance L between the shafts is set to 450 to 600 mm and the plate thickness is set to 10 to 60 mm. Under these conditions, the roll radius d is 12.5 mm, 17.5 mm, 22.5 mm, 27. The change of the sliding distance when changing to 5 mm, 32.5 mm, 37.5 mm, 42.5 mm, 47.5 mm, and 50 mm was investigated. The forming load at this time was assumed that the length of the plate was 15 m, the forming load was 400 to 30000 tons (about 3920 to 294000 kN), and a rectangular steel pipe was manufactured. This experiment is based on FEM (Finite Element Method) simulation.

  The results are shown in Tables 1 to 6 below. Of these, Table 1 shows the relationship between the roll radius and the sliding distance when the plate thickness of the steel sheet is 10 mm. Table 2 shows the relationship between the roll radius and the sliding distance when the steel plate thickness is 20 mm. Table 3 shows the relationship between the roll radius and the sliding distance when the plate thickness of the steel plate is 30 mm. Table 4 shows the relationship between the roll radius and the sliding distance when the plate thickness of the steel plate is 40 mm. Table 5 shows the relationship between the roll radius and the sliding distance when the plate thickness of the steel plate is 50 mm. Table 6 shows the relationship between the roll radius and the sliding distance when the plate thickness of the steel plate is 60 mm.

  FIG. 13 shows the relationship between the roll radius and the sliding distance when the results in Table 1 above, that is, when the distance L between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 10 mm. FIG. 14 shows the relationship between the roll radius and the sliding distance when the results in Table 2 above, that is, when the distance between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 20 mm. FIG. 15 shows the relationship between the roll radius and the sliding distance when the results in Table 3 above, that is, when the distance between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 30 mm. FIG. 16 shows the relationship between the roll radius and the sliding distance when the results in Table 4 above, that is, when the distance between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 40 mm. FIG. 17 shows the relationship between the roll radius and the sliding distance when the results in Table 5, that is, the distance between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 50 mm. FIG. 18 shows the relationship between the roll radius and the sliding distance when the results in Table 6, that is, the distance between the axes is 450 to 600 mm and the plate thickness of the steel sheet is 60 mm.

  As is clear from these results, it can be seen that there is a range between the inter-shaft distance L and the roll radius d that can reduce the sliding distance according to the plate thickness. That is, when the inter-axis distance L is set to 450 to 600 mm, it is understood that the preferable roll radius d that can reduce the sliding distance is 12.5 to 50 mm.

DESCRIPTION OF SYMBOLS 1 Upper metal mold | die 2 Rotating roll 3 Bending line 4 Forming part 5 Press forming square steel pipe 6 Welding part 7 Holder 8a, 8b Convex part 9 Plate material support part 10 Steel plate 11 Punch

Claims (5)

A press forming apparatus for bending a metal plate,
The upper mold,
Provided at the bottom of the upper mold, and has two rotating rolls mounted on a roll holder;
Each of the two rotating rolls has a plate material support portion having a plurality of convex portions extending linearly in the axial direction of the rotating roll,
The press molding apparatus characterized in that a movable angle range formed by a surface in contact with the top of the plurality of convex portions with respect to a horizontal plane is 0 to 60 °.   2. The distance between the axes of the two rotary rolls and the radius of the two rotary rolls are set so that the distance at which the tops of the plurality of convex portions slide on the surface during press molding is minimized. The press molding apparatus described in 1.   The press molding apparatus according to claim 2, wherein a distance between the axes of the two rotary rolls is 450 to 600 mm, and a radius of the two rotary rolls is 12.5 to 50 mm.   The press molding apparatus according to claim 2 or 3, wherein the thickness of the metal plate material is 10 to 60 mm.   The press forming apparatus according to claim 1, wherein the metal plate material is a steel plate.