JP2017164774A - Method and apparatus for manufacturing press-formed article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a press-formed article which has high formed height by hot-stamping, and a press apparatus.SOLUTION: The method for manufacturing a press-formed article comprises a preparation step, a heating step, and a hot-stamping step. In the preparation step, a blank S composed of a metal sheet is prepared. In the heating step, the blank S is heated. In the hot-stamping step, the heated blank S is pressed by a press apparatus 1 thereby obtaining a press-formed article having an opening 13. In the hot-stamping step, the opening 13 is provided in the blank S during the period from working start of the blank S by the press apparatus 1 to working end.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a press-formed product having an opening and a manufacturing apparatus therefor. More specifically, the present invention relates to a method for manufacturing a press-molded product suitable for an automobile door inner panel and a manufacturing apparatus therefor.

  There is hot stamping as a method of manufacturing a press-formed product. Hot stamping hot presses a blank material. In hot stamping, a press-molded product is quenched at the same time as the press work is completed. Thereby, a high-strength press-formed product is manufactured.

  A method of manufacturing a press-formed product having an opening by hot stamping is disclosed in International Publication No. 2014/181882 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2005-138111 (Patent Document 2).

  In the manufacturing method of Patent Document 1, after blank material is pressed by hot stamping, an opening is punched out from a press-formed product. During punching, the temperature of the press-formed product is controlled within an appropriate range. Thus, Patent Document 1 discloses that delayed fracture of the punched portion is suppressed.

  In the manufacturing method of Patent Document 2, a blank is pressed by hot stamping, and then an opening is punched out from a press-formed product. When the mold reaches bottom dead center, the punched part is not cooled. Therefore, Patent Document 2 describes that even a high-strength press-formed product can be easily punched.

International Publication No. 2014/181882 JP 2005-138111 A

  However, in the manufacturing methods of Patent Documents 1 and 2, the opening is punched after the press working by hot stamping is completed. That is, the forming form by hot stamping in Patent Documents 1 and 2 is drawing from beginning to end. In the drawing by hot stamping, the edge of the blank is preferentially cooled during press working. Therefore, it is difficult for the material of the edge of the blank material to flow. Therefore, when the hot stamping is formed by drawing, when a press-formed product having a high forming height is manufactured, the press-formed product is likely to be cracked.

  The objective of this invention is providing the manufacturing method and press apparatus of a press-molded article with high molding height by hot stamping.

  A method for manufacturing a press-formed product according to an embodiment of the present invention includes a preparation step, a heating step, and a hot stamping step. In the preparation step, a blank material made of a metal plate is prepared. In the heating step, the blank material is heated. In the hot stamping process, the heated blank material is pressed by a press device. In the hot stamping step, a press-formed product having an opening is obtained. In the hot stamping step, an opening is provided in the blank material between the start of processing of the blank material by the press device and the end of processing.

  A press device according to an embodiment of the present invention includes a die, a blade, a punch, and a blank holder. The die has a bottom surface. The blade is disposed on the bottom surface of the die. The punch faces the bottom surface of the die. The blank holder sandwiches the blank material with the die. The press apparatus manufactures a press-formed product having an opening by hot stamping.

  The method and apparatus for producing a press-formed product according to the present invention can produce a press-formed product having a high molding height.

FIG. 1 is a perspective view showing a press-formed product of the first embodiment. FIG. 2 is a cross-sectional view of the press device according to the first embodiment. FIG. 3 shows the stage of drawing in the hot stamping process of the first embodiment. FIG. 4 shows the stage of stretch flange molding in the hot stamping process of the first embodiment. FIG. 5 shows a forming bottom dead center stage in the hot stamping process of the first embodiment. FIG. 6 is a cross-sectional view of the side door of the automobile. FIG. 7 is a perspective view of the door inner panel. FIG. 8 is a cross-sectional view showing the pressing apparatus according to the second embodiment. FIG. 9 shows the stage of drawing in the hot stamping process of the second embodiment. FIG. 10 shows the stage of stretch flange molding in the hot stamping process of the second embodiment. FIG. 11 shows the stage of forming bottom dead center in the hot stamping process of the second embodiment.

  The method for manufacturing a press-formed product according to the present embodiment includes a preparation process, a heating process, and a hot stamping process. In the preparation step, a blank material made of a metal plate is prepared. In the heating step, the blank material is heated. In the hot stamping process, the heated blank material is pressed by a press device. In the hot stamping step, a press-formed product having an opening is obtained. In the hot stamping step, an opening is provided in the blank material between the start of processing of the blank material by the press device and the end of processing.

  In the manufacturing method of the present embodiment, an opening is provided in the blank material during press working by hot stamping. That is, the molding form until the opening is provided in the blank material is drawing, and the molding form after the opening is provided is stretch flange molding. Thereby, the molding height by stretch flange molding is added to the molding height by drawing. Therefore, the molding height of the press-molded product can be increased as compared with the case where the blank is formed only by drawing or the case where the blank is formed only by stretch flange molding.

  As described above, the drawing height is low in the drawing by hot stamping. Therefore, in the hot stamping process, it is preferable that the opening is provided before the blank material is processed to a height of 50% of the molding height of the press-formed product. Thereby, more than half of the molding height of the press-molded product is molded by stretch flange molding suitable for hot stamping. Therefore, the molding height of the press-molded product can be increased while suppressing cracking of the press-molded product.

  The press device used in the above-described hot stamping process preferably includes a die, a blade disposed on the bottom surface of the die, a punch, and a blank holder. In this case, the opening of the blank is provided by a die blade.

  The blade of the above-mentioned press device preferably includes a heating device. The heating device heats the blade. In this case, even if a blank material contacts a blade, a blank material is hard to be cooled. Therefore, it is difficult for the material flow by stretch flange molding to be hindered.

  The press device according to the present embodiment includes a die, a blade, a punch, and a blank holder. The die has a bottom surface. The blade is disposed on the bottom surface of the die toward the punch. The punch faces the bottom surface of the die. The blank holder sandwiches the blank material with the die. The press apparatus manufactures a press-formed product having an opening by hot stamping.

  The press apparatus according to the present embodiment performs hot stamping. The pressing device includes a blade on the bottom surface of the die. The blade penetrates the blank material being processed before the mold reaches the bottom dead center. Thereby, an opening is provided. After the opening is provided, the blank is stretched and flanged.

  In hot stamping, the stretch flange molding can increase the molding height of the press-molded product than the draw molding. More than half of the molding height is preferably formed by stretch flange molding. Therefore, it is preferable that the height of the blade of the above-described press device is at least half of the depth of the die. The blade preferably includes a heating device. The heating device heats the blade.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[First Embodiment]
[Press-formed product]
FIG. 1 is a perspective view showing a press-formed product of the first embodiment. A press-formed product as shown in FIG. 1 or a part having a shape part as shown in FIG. The press-formed product 16 includes a top plate portion 17, a vertical wall portion 18, and a flange portion 19. The top plate portion 17 is circular. The top plate portion 17 has an opening portion 17A. The outer edge of the top plate portion 17 is connected to the vertical wall portion 18. The vertical wall portion 18 has a cylindrical shape. The flange portion 19 is connected to the vertical wall portion 18.

  When a press-molded product 16 as shown in FIG. 1 is formed from a flat blank material, drawing molding or stretch flange molding (bending molding) is performed. The molding height of the press-formed product 16 refers to the distance between the flange portion 19 and the top plate portion 17.

[Pressing equipment]
FIG. 2 is a cross-sectional view of the press device according to the first embodiment. The press device 1 includes a punch 4 and a blank holder 5 as an upper die. The press apparatus 1 includes a die 2 as a lower mold. The press device 1 includes a blade 3. The press apparatus 1 manufactures a press-formed product having an opening as shown in FIG.

  The die 2 has a bottom surface 6. On the bottom surface 6 of the die 2, the shape of the top plate portion 17 of the press-formed product shown in FIG. 1 is formed.

  The blade 3 is disposed on the bottom surface 6 of the die 2. The blade 3 protrudes toward the punch 4. The material of the blade 3 may be a material for a general punching tool. The blade 3 penetrates the blank material S during pressing. Thereby, the opening 17A of the press-formed product 16 shown in FIG. 1 is provided. The press apparatus 1 performs hot stamping. In hot stamping, a heated blank is pressed. The heated blank material has high ductility.

  When the blank material S comes into contact with the blade 3, the blank material S is extracted by the blade 3. Therefore, in order to maintain the ductility of the blank S during the press working, the blade 3 is preferably heated. In this case, the blade 3 is provided with a hole for accommodating a heating device such as a cartridge heater. Moreover, when using the heated blade 3, it is preferable that the heat insulating material 7 is arrange | positioned between the blade 3 and the bottom face 6 of the die | dye 2. FIG. This is because the die 2 has a low temperature in order to quench the press-formed product. The height of the blade 3 from the bottom surface 6 of the die 2 is preferably at least half of the molding height. This is because, as will be described later, in hot stamping, the molding height by stretch flange molding is higher than the molding height by drawing. Here, the molding height of the press-molded product corresponds to the distance between the flat portion 15 of the die 2 and the bottom surface 6.

  The punch 4 faces the bottom surface 6 of the die 2. The punch 4 has a recess 9 in a region facing the blade 3. The punch 4 is formed with the shapes of the top plate portion 17 and the vertical wall portion 18 of the press-formed product shown in FIG. The punch 4 pushes the blank material S into the bottom surface 6 of the die 2. FIG. 2 shows a case where the punch 4 has a blade 14. However, the punch 4 may not have the blade 14. When an opening can be provided in the blank S with only the blade 3 disposed on the bottom surface 6 of the die 2, the blade 14 of the punch 4 is not necessary. Note that, similarly to the blade 3 disposed on the bottom surface 6 of the die 2, it is preferable that a heat insulating material 7 be disposed between the blade 14 of the punch 4 and the punch 4.

  The blank holder 5 is disposed outside the punch 4. The blank holder 5 faces the die 2. The blank holder 5 and the die 2 sandwich the blank material S. In the blank holder 5, the shape of the flange portion 19 of the press-formed product 16 shown in FIG. 1 is formed.

  The die 2, the punch 4 and the blank holder 5 have a cooling path inside. A cooling medium such as cooling water flows through the cooling path. The die 2, the punch 4 and the blank holder 5 are cooled by a cooling medium. Thereby, a press-molded product can be quenched at the bottom dead center.

  The punch 4 and the blank holder 5 are supported by the upper mold holder 10. The upper mold holder 10 is attached to a slide (not shown). A pressure member 11 is provided between the punch 4 and the blank holder 5 and the upper mold holder 10. The pressurizing member is a hydraulic cylinder, a gas cylinder, a spring, rubber, or the like. The die 2 is fixed to the lower mold holder 12. The lower mold holder 12 is attached to a bolster plate (not shown).

  Here, the press apparatus 1 is not limited to the case shown in FIG. For example, the punch 4 and the blank holder 5 may be attached to individually movable slides. Moreover, in FIG. 2, the case where the press apparatus 1 has the punch 4 and the blank holder 5 on the apparatus upper side, and has the die | dye 2 on the apparatus lower side is shown. However, these arrangements are not limited to the case shown in FIG. In the press apparatus 1, the arrangement of the punch 4 and the blank holder 5 and the die 2 may be reversed upside down. In short, the punch 4 and the blank holder 5 may be configured to move relative to the die 2.

[Production method]
The method for manufacturing a press-formed product according to the first embodiment includes a preparation process, a heating process, and a hot stamping process. In the hot stamping process, the blank material is quenched. Therefore, it is preferable that the blank material is a steel plate. Hereinafter, the case where a press-formed product is manufactured from a blank made of a steel plate will be described.

[Preparation process]
In the preparation step, a blank material made of a steel plate is prepared. The blank material is obtained by cutting a steel plate coil into a predetermined dimension. The blank made of a steel plate is preferably contained in mass% and carbon (C): 0.11% or more. This is because when the blank material contains 0.11% by mass or more of carbon, the strength of the press-formed product after hot stamping is increased. However, even if the carbon content of the blank is less than 0.11% by mass, the strength of the press-formed product is higher than that of the blank by quenching.

[Heating process]
In the heating step, the blank material is heated by a heating device (not shown). The blank material is preferably heated to the A1 transformation point or higher of the material. It is more preferable that the blank is heated to the A3 transformation point or higher. In hot stamping, the formed press-molded product is quenched at the same time as the blank material is pressed. If a blank material heated to a point A1 or higher is quenched, the metal structure of the press-formed product after quenching becomes martensite and has high strength. The heating temperature is, for example, 700 to 900 ° C. The heating temperature is appropriately set depending on the material, the difficulty of molding, and the like. Moreover, when a blank material is heated, the ductility of a blank material will become high. Therefore, a press-formed product having a complicated shape can be formed.

[Hot stamping process]
3 to 5 are sectional views showing the hot stamping process of the present embodiment. FIG. 3 shows the stage of drawing. FIG. 4 shows the stage of stretch flange molding. FIG. 5 shows the stage of molding bottom dead center. The hot stamping process proceeds in the order of FIGS.

  With reference to FIG. 3, the heated blank S is placed in the press device 1. After the blank material S is arranged, the slide descends. The blank material S is sandwiched between the blank holder 5 and the die 2. However, the distance between the blank holder 5 and the die 2 is preferably larger than the thickness of the blank material S. That is, a gap is provided between the blank material S and the blank holder 5. The size of the gap is, for example, 0.1 mm. When the blank holder 5 contacts the blank material S, the area | region which contacts the blank holder 5 of the blank material S is cooled before the blank material S is pressed. Therefore, while the blank material S is being drawn, the material of the blank material S hardly flows into the bottom surface 6 side of the die 2. In this case, the blank material S is easily broken. Therefore, it is preferable that a slight gap is provided between the blank holder 5 and the blank material S.

  As shown in FIG. 3, the punch 4 is pushed into the die 2 while the blank material S is sandwiched between the blank holder 5 and the die 2. Thereby, the processing of the blank material S is started. As shown in FIG. 3, in the hot stamping process of this embodiment, the blank material S is first drawn. The drawing of the blank material S continues from the start of processing until the opening is provided in the blank material S by the blade 3.

  Referring to FIG. 4, when the slide is further lowered, the blade 3 penetrates the blank material S. Thereby, the opening 13 is provided in the blank S. At this time, the punch 4 has not reached the molding bottom dead center. That is, the processing of the blank material S by the press device 1 is not finished.

  The slide is further lowered, and the blank material S provided with the opening 13 is pressed. At this time, the opening 13 of the blank S expands as the punch 4 is pushed in (see the arrow in FIG. 4). This is because, at this stage, the vicinity of the opening 13 of the blank material S is high in temperature, and therefore has high ductility. That is, after the opening 13 is provided in the blank material S, the blank material S is stretch-flange-molded. Stretch flange molding of the blank material S continues after the opening 13 is provided in the blank material S until the end of processing.

  With reference to FIG. 5, when the punch 4 reaches the bottom dead center of the molding, the processing of the blank S is finished, and the press-formed product P is obtained. In addition, the press-formed product P comes into contact with the die 2 and the punch 4 at the bottom dead center. Thereby, the press-formed product P is quenched.

  In short, in the hot stamping process of this embodiment, both drawing and stretch flange forming are performed on the blank material during press working. Thereby, the molding height by stretch flange molding is added to the molding height by drawing. Therefore, the molding height of the press-molded product of the present embodiment is higher than the molding height of the press-molded product molded only by draw molding or molded only by stretch flange molding.

  Further, as described above, when the blank material is drawn by hot stamping, cracks are likely to occur. Therefore, when producing a press-molded product having a high molding height by hot stamping, stretch flange molding is applied. However, when stretch flange molding is applied from the start of processing, it is necessary to provide an opening or the like in the blank material in advance. That is, it is necessary to add a process of providing an opening in the blank material before the hot stamping process. In the manufacturing method of the present embodiment, an opening is provided in the blank material during press working by hot stamping. Therefore, the manufacturing method of this embodiment does not require a separate process for providing an opening, and has high production efficiency.

  As described above, in hot stamping, the molding height by stretch flange molding is higher than the molding height by drawing. Therefore, in the hot stamping process of the present embodiment, it is preferable to form more than half of the molding height of the press-formed product by stretch flange molding. That is, in the hot stamping process, it is preferable that the opening is provided before the blank material is processed to a height of 50% of the molding height of the press-formed product. More preferably, the opening is provided before the blank is processed to a height of 40% of the molding height of the press-formed product.

  In order to maximize the molding height of the press-molded product, it is preferable to increase the molding height by drawing as much as possible and switch to stretch flange molding. That is, it is preferable that the timing of providing the opening in the blank material in the hot stamping process is immediately before the drawing limit of the blank material. The drawing limit refers to a limit at which the blank can be drawn without cracking.

  The drawing limit of the blank material varies depending on the size and material of the blank material. As a method for obtaining the drawing limit of the blank material, for example, there is a thermo-molding coupled analysis. Specifically, the thickness reduction rate of the blank material is analyzed in advance. The aperture limit is determined based on the analysis result.

[Second Embodiment]
The press-formed product of the present embodiment is a product that requires a high molding height. As such a product, there is, for example, a door inner panel for automobiles other than the press-formed product shown in FIG.

[Press-formed product]
FIG. 6 is a cross-sectional view of the side door of the automobile. FIG. 6 is a cross-sectional view of the automobile as viewed from above and below. An automobile door is manufactured mainly by combining a door inner panel 20 and a door outer panel 21. A window, a window driving device, an acoustic speaker, a handle, and the like are attached to the door of the automobile. In order to store these, a space SP is required between the door inner panel 20 and the door outer panel 21. Therefore, for example, the vertical wall portion 22 is provided on the door inner panel 20. It is preferable that the height of the vertical wall portion 22 (the molding height of the door inner panel) can be designed freely. This is because the size of the space SP for storing windows and the like can be designed freely.

  FIG. 7 is a perspective view of the door inner panel. The door inner panel 20 includes a top plate part 23, a vertical wall part 22, a step part 24, and an opening part 25. The door inner panel 20 is made of a metal plate such as a steel plate.

  The planar shape of the top plate portion 23 is a polygon. The upper side of the top plate 23 forms the belt line BL. The vertical wall portion 22 extends from the outer side of the top plate portion 23. The step portion 24 extends outward from the vertical wall portion 22 </ b> A connected to the top plate portion 23. The outer edge of the stepped portion 24 is connected to the vertical wall portion 22B connected to the flange portion 26. The step portion 24 faces the pillar 27 of the vehicle body and seals the inside of the vehicle (see FIG. 6). A sealing member is disposed between the stepped portion 24 and the pillar 27 and the like in order to improve the sealing performance in the vehicle. The opening 25 is provided in the top plate part 23. For example, the above-described acoustic speaker or the like is attached to the opening 25.

  The door inner panel 20 plays a role of ensuring the safety of the passenger. Therefore, it is preferable that the strength of the door inner panel 20 is high. When the door inner panel 20 is a steel plate, the door inner panel 20 may be formed by hot stamping in order to increase the strength of the door inner panel 20. Hereinafter, the case where the door inner panel 20 which has the opening part 25 and the level | step-difference part 24 as shown in FIG. 7 with the manufacturing method of this embodiment is manufactured is demonstrated.

  The second embodiment is based on the first embodiment. Below, description is abbreviate | omitted about the same structure as 1st Embodiment.

[Pressing equipment]
FIG. 8 is a cross-sectional view showing the pressing apparatus according to the second embodiment. The press device 30 according to the second embodiment is different from the first embodiment in that the punch is divided. Like a door inner panel, a complicated shape in which adjacent vertical wall portions have stepped portions is difficult to mold. When a complicated shape is formed with one punch, the door inner panel is likely to be cracked or wrinkled. Therefore, the punch of the second embodiment has the first punch 31 and the second punch 32.

  The first punch 31 has a recess 39. A blade 37 may be provided in the recess 39 as in the first embodiment. The first punch 31 is formed with the shape of the top plate portion of the door inner panel. The second punch 32 is disposed outside the first punch 31. The second punch 32 is formed with a stepped portion of the door inner panel. The blank holder 33 is disposed outside the second punch 32. In the blank holder 33, the shape of the flange portion of the door inner panel is formed.

  The die 36 faces the first punch 31, the second punch 32, and the blank holder 35. As in the first embodiment, a blade 35 is disposed on the bottom surface 34 of the die 36.

[Production method]
[Hot stamping process]
9 to 11 are sectional views showing a hot stamping process of the second embodiment. FIG. 9 shows the stage of drawing. FIG. 10 shows the stage of stretch flange molding. FIG. 11 shows the stage of molding bottom dead center. The hot stamping process of the second embodiment proceeds in the order of FIGS.

  Referring to FIG. 9, after the heated blank S is sandwiched between the blank holder 33 and the die 36, first, the step portion of the door inner panel is formed by the second punch 32. At this stage, no opening is provided in the blank S. Therefore, the step portion of the door inner panel is formed by drawing.

  Referring to FIG. 10, after the stepped portion is formed, the top plate portion of the door inner panel is formed by the first punch 31. An opening is provided by the blade 35 while the top plate is being molded. That is, in forming the top plate portion by the first punch 31, the blank material is drawn until an opening is provided, and after the opening is provided, the blank material is stretched and flange formed. Thereby, similarly to 1st Embodiment, compared with the case where a blank material is shape | molded only by drawing or the case where it shape | molds only by stretch flange shaping | molding, the shaping | molding height of a press-molded product can be made higher. That is, the height of the vertical wall portion of the door inner panel can be increased.

  Referring to FIG. 11, when the first punch 31 reaches the bottom dead center for forming, the processing of the blank S is finished, and the door inner panel 20 is obtained. Further, the blank material S comes into contact with the die 36, the first punch 31 and the second punch 32 at the bottom dead center. Thereby, the door inner panel 20 is quenched.

  As described above, the press-formed product of the present embodiment is made of a metal plate. Examples of the metal plate include a steel plate, an aluminum plate, an aluminum alloy plate, a multilayer steel plate, a titanium plate, and a magnesium plate. In the present embodiment, a case where the thickness of the metal plate is constant will be described. Accordingly, the thickness of the press-formed product is also constant over the entire area. Strictly speaking, however, a slight increase or decrease in sheet thickness occurs due to press molding. The metal plate may be a tailored blank.

  The embodiment of the present invention has been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing the above-described embodiment without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 1 Press apparatus 2 Die 3, 14 blades 4 Punch 5 Blank holder 6 Die bottom face 7 Heat insulating material 9 Punch recessed part 13 Opening part 20 Door inner panel S Blank material

Claims (7)

A preparation step of preparing a blank made of a metal plate;
A heating step of heating the blank material;
A hot stamping step of pressing the heated blank material with a pressing device to obtain a press-formed product having an opening, and
In the hot stamping process,
A method for manufacturing a press-formed product, wherein the opening is provided in the blank material between the start of processing of the blank material by the press device and the end of processing. It is a manufacturing method of the press-formed product according to claim 1,
In the hot stamping step, the opening is provided before the blank material is processed to a height of 50% of the molding height of the press-molded product. A method for producing a press-formed product according to claim 1 or 2,
The press device includes a die, a blade disposed on a bottom surface of the die, a punch, and a blank holder.
The said opening part of the said blank material is a manufacturing method of the press molded product provided with the said blade. It is a manufacturing method of the press-formed product according to claim 3,
The blade includes a heating device;
The said heating apparatus is a manufacturing method of the press-molded product which heats the said blade. A press device for producing a press-formed product having an opening by hot stamping,
A die having a bottom surface;
A blade disposed on the bottom surface of the die;
A punch facing the bottom of the die;
And a blank holder for sandwiching a blank material with the die. The press device according to claim 5,
The height of the said blade is a press apparatus which is more than half of the depth of the said die | dye. The press device according to claim 5 or 6,
The blade includes a heating device;
The said heating apparatus is a press apparatus which heats the said blade.

Images