[0001]The present disclosure relates to burring method and burring apparatus.
BACKGROUND
[0002]The burring method of forming a cylindrical flange on the workpiece, such as a material metal plate formed of the prepared hole (through-hole), typically, by extruding by punching a peripheral portion of the prepared hole in the material metal sheet, to form a flange. Further, for example, in JP-A-2014-172089, by forming the shape of the tip portion of the punch substantially conical shape, for low ductile high strength steel plate or the like, the tip of the flange (periphery of the prepared hole thereby suppressing the occurrence of cracking in). As the burring process, is disclosed in JP-A-6-087039 discloses another.
Summary of the Invention
Problems that the Invention is to Solve
[0003]
　However, in Japanese Unexamined Patent Publication No. 2014-172089, the need to appropriately set the shape of the tip of the punch with respect to the prepared hole of the material metal sheet, is complicated shape of the punch. Therefore, in the burring process, it is desirable to be able to suppress the occurrence of cracks at the tip of the flange with a simple configuration.
[0004]
　The present disclosure, in consideration of the above circumstances, and an object thereof is to provide a burring method and burring apparatus occurrence of cracks can be suppressed with a simple structure at the tip of the flange.
Means for Solving the Problems
[0005]
　Burring method of one aspect of the present disclosure, the punch is positioned on one side of the thickness direction of the through holes are formed plate-like member to be processed, the said one side of the thickness direction of the workpiece is as the pad on the opposite side is located, the arrangement step of arranging the workpiece, in a pressurized state a peripheral portion of the through hole in the thickness direction of the workpiece by said said punch pad, and a extrusion forming a flange by extruding a peripheral portion of the through hole by the punch said punch said is relatively moved to the opposite side of the workpiece.
[0006]
　Burring apparatus of another aspect of the present disclosure is disposed on one side of the thickness direction of the through holes are formed plate-like workpiece, opposite to the one side of the thickness direction of the workpiece a punch for forming a flange by extruding a peripheral portion of the through hole in the workpiece by the to the side is moved relative to the workpiece, the other side of the thickness direction of the workpiece in disposed and the punch facing to, and a pad for pressing a peripheral portion of the through hole in the workpiece with the punch in the extrusion process of the punch relative to the workpiece.
[0007]
　Burring apparatus of still another aspect of the present disclosure, a punch having at least a peripheral portion a flat top surface, a holder disposed around the punch, is arranged to face the holder, the punch side a die having an opening with the housing part, is disposed in the housing portion is movable in the pressing direction, and a pad having a surface facing the top surface of the punch.
Effect of the invention
[0008]
　According to the present disclosure, it is possible to provide a burring method and burring apparatus capable of suppressing the occurrence of cracks at the tip of the flange with a simple configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
[1] Figure 1 is a sectional view showing a main portion of the burring apparatus used in burring processing method according to the first embodiment.
[Figure 2A] Figure 2A is a cross-sectional view showing a first step of burring method according to the first embodiment.
[Figure 2B] Figure 2B is a sectional view showing the middle of the second step of the burring process.
[Figure 2C] FIG 2C is a cross-sectional view showing the end of the second step of the burring process.
FIG. 3 is a perspective view showing a burring parts subjected to the burring by burring apparatus shown in FIG.
[Figure 4A] Figure 4A is a cross-sectional view showing a state before burring in burring method of Comparative Example.
[Figure 4B] Figure 4B is a cross-sectional view showing a state after burring in burring method of Comparative Example.
FIG. 5 is a perspective view showing a state in which cracks were generated in the distal end portion of the flange that are burring by burring method of Comparative Example.
FIG. 6 is a sectional view showing a main portion of the burring apparatus used in burring processing method according to the second embodiment.
[7] FIG. 7 is a sectional view showing an enlarged during the second step of the burring method according to the second embodiment partially.
FIG. 8, in the second step of the burring method according to the first embodiment, is a cross-sectional view for explaining the shearing of the material metal sheet by the pad.
[9] FIG. 9 is a sectional view showing an example of a variation of the pad shown in Figure 1.
FIG 10A] FIG 10A is a sectional view for explaining an example of a case of forming an inclined portion on the entire outer peripheral surface of the pad.
[FIG. 10B] FIG 10B is a sectional view for explaining an example of a case of forming an inclined portion on a part of the outer peripheral surface of the pad.
[FIG. 10C] FIG 10C is a sectional view for explaining an example of a case of forming an inclined portion that is curved on a part of the outer peripheral surface of the pad.
[11] FIG 11 is a cross-sectional view showing the main parts of a modification of the burring apparatus used in burring processing method according to the first embodiment.
DESCRIPTION OF THE INVENTION
[0010]
(First Embodiment)
　Hereinafter, with reference to FIGS. 1 to 5 will be described burring method according to the first embodiment. The burring process, by performing burring the material metal plate 10 as a pilot hole is formed "workpiece", to produce a burring part 12 having a substantially cylindrical flange 14. Here, the "pilot hole" refers to a through hole penetrating the material metal plate 10 in the thickness direction. Hereinafter, first, the configuration of the material metal plate 10 and the burring part 12. Next will be described burring apparatus 20 used in burring. Then, thereafter, it will be described burring process. Note that like the same members in the drawings are denoted by the same reference numerals, those described above for the same parts in the following discussion are appropriately omitted.
[0011]
(Material metal plate 10 and the burring for the part 12)
　will be described burring part 12 with reference to FIG. The arrow A shows the one side in the thickness direction of the burring part 12, an arrow B is opposite to the one side in the thickness direction of the burring parts 12, i.e., burring part 12 shown in FIG. 3 It shows the other side of the thickness direction.
[0012]
　Burring parts 12, for example, tensile strength is formed by high-strength steel sheet of more than 440 MPa. In this embodiment, high-strength steel sheet constituting the burring parts 12, tensile strength as an example is and thickness is 2.9mm by 590 MPa. The burring part 12 by burring, a flange 14 which projects in the thickness direction to the other side. The inner diameter D1 of the flange 14 is 60mm, for example. Incidentally, as shown in FIG. 1, the burring the material before the metal plate 10, a circular lower hole 10A is formed in order to form the flange 14. The inner diameter d of the lower hole 10A is 36mm as an example. That is, in the burring process and burring apparatus of the present embodiment, forming a flange 14 with a hole expansion ratio ((D1-d) / d) is 0.67. The shape of the prepared hole 10A is not limited to a circular shape, for example, it may be formed in an elliptical shape.
[0013]
(For burring device 20)
　with reference to FIG. 1, it will be described burring apparatus 20. The arrow A shown in FIG. 1 shows the device under the burring apparatus 20, arrows B show the device upper burring apparatus 20. Then, the thickness direction of the vertical direction of the apparatus and the material metal plate 10 match. Incidentally, the upper side in the drawing, are as defined for the lower description, the vertical direction in the figure may be not coincide with the vertical direction.
[0014]
　Flanging apparatus 20 includes a punch 22 and the holder 24 constituting the device lower part of the burring apparatus 20 is configured to include a pad 26 and die 28 constituting the apparatus upper part of the burring apparatus 20, the . Then, a punch 22 and the holder 24, the pad 26 and the die 28, by placing the material metal plate 10 between, so that applying burring to the material metal plate 10.
[0015]
　Upper surface of the holder 24 is a mounting surface for the material metal plate 10 is placed. When the material metal plate 10 is installed on the upper surface of the holder 24 is configured so that the position relative to the holder 24 of the material metal sheet 10 is determined. As the arrangement, for example, a pin for positioning the upper surface of the holder 24 (not shown) provided, configured to form a hole for positioning the pins in the material metal plate 10 is inserted (not shown) and the like. On the upper surface of the holder 24, the punch housing portion 24A for housing the punch 22 at a position corresponding to the lower hole 10A of the material metal sheet 10 is formed. The punch accommodating portion 24A is formed in a concave shape which is opened to the device upper side. In other words, the holder 24 has a punch accommodating section 24A which is open to the apparatus above. Further, the punch accommodating portion 24A is formed in a circular shape as viewed from the upper side. Also, as in the modified example of the burring apparatus 20 shown in FIG. 11, the lower end of the holder 24, the holder pressurizing device 60 may be connected. Holder pressurizing device 60, for example a gas cushion, a hydraulic device, a spring, and is configured by an electric drive apparatus or the like.
[0016]
　Punch 22 is formed in a substantially cylindrical shape to the vertical direction of the apparatus axis direction (direction along the axis 22AL described later). Incidentally, FIG. 1 shows the axis 22AL of the punch 22 by a one-dot chain line. Further, the press direction of the burring apparatus 20 is the direction along the axis 22AL of the punch.
　Further, the punch 22 is accommodated in the punch accommodating section 24A. The outer diameter D3 of the punch 22 is the same size as the inner diameter D1 of the flange 14 of the burring part 12. That is, in this embodiment, the outer diameter D3 of the punch 22 is 60 mm. Further, the lower end of the punch 22, the mobile device 30 is connected as an example of punching the mobile device. Punch 22 is configured to be relatively moved in the vertical direction of the apparatus relative to the holder 24 by the moving device 30. Specifically, the punch 22 is movable in the axial direction by the moving device 30. The mobile device 30 includes, for example, is configured by a hydraulic cylinder.
　Here, in the installed state the material metal plate 10 to the holder 24, pilot hole 10A of the material metal sheet 10 is placed on the punch 22 coaxially.
　Incidentally, the above embodiment is merely an example, and the lower hole 10A and the punch 22 may not be arranged coaxially. However, in order to uniformly burring the periphery 10B of the lower hole 10A, it is desirable to overlap the axis of the center of gravity and the punch 22 of the prepared hole 10A.
[0017]
　The top surface of the punch 22 (excluding described below shoulder 22A, the pad 26 facing the surface) is a punch surface 22B. Punch surface 22B is formed along a plane perpendicular to vertical direction of the apparatus. During burring punch surface 22B is parallel with the lower surface of the material metal plate 10 installed in the holder 24 (one side surface in the thickness direction). Thus, the mobile device 30 punch surface 22B of the punch 22 is in the state of being disposed on the lower surface flush with the material metal plate 10, the punch surface 22B abuts in terms to the lower surface of the material metal sheet 10. Further, at the boundary portion between the outer peripheral surface of the punch 22 (the outer peripheral surface of the body) the top surface (punch surface 22B), an arc-shaped cross section of the shoulder portion 22A is formed.
[0018]
　Die 28 is disposed in the apparatus above the holder 24 is opposed to the holder 24 in the vertical direction of the apparatus. The die 28 is connected to the moving device 34 as an example of a die moving device. Mobile device 34 is movable in the die 28 in the vertical direction of the apparatus. The flanging device 20, by the die 28 is moved to the device bottom, it has a material metal sheet 10 in the configuration sandwiching the vertical direction of the apparatus by the die 28 and the holder 24. Further, on the lower surface of the die 28, the pad housing portion 28A as the "accommodating section" for accommodating the pad 26 at a position corresponding to the lower hole 10A of the material metal sheet 10 is formed. The pad housing portion 28A is formed in a concave shape which is opened to the device bottom. In other words, the die 28 has a pad accommodating portion 28A which is open to the apparatus bottom. The pad housing portion 28A is formed in a circular shape as viewed from the bottom, it is arranged above the punch accommodating part 24A coaxially. The inner diameter of the pad housing portion 28A is substantially the same as the outer diameter D2 of the flange 14 of the burring part 12 after processing (see FIG. 3).
[0019]
　Pad 26 is formed a vertical direction of the apparatus in a cylindrical shape whose axial direction. The pad 26 is housed in the pad receiving portion 28A. Thus, the pad 26 is disposed opposite to the punch 22 in the thickness direction of the material metal plate 10. The pad 26 is disposed below the hole 10A and the punch 22 coaxially of the material metal sheet 10. The upper end portion of the pad 26, the pad pressure device 32 is connected. Pad pressing device 32, for example a gas cushion, a hydraulic device, a spring, and is configured by an electric drive apparatus or the like. Accordingly, pads 26 are relatively movably connected to the apparatus vertically relative to the die 28 by the pad pressure device 32. The lower surface of the pad 26 (i.e., surface facing the punch surfaces 22B and vertical direction of the apparatus of the punch 22) is a pad surface 26A. Pad surface 26A is formed along a plane perpendicular to vertical direction of the apparatus. During burring, pad surface 26A is (a surface in the thickness direction one side) the upper surface of the material metal plate 10 installed on the holder 24 and parallel to the punch surface 22B of the punch 22. As described above, although pad 26 is connected to the die 28 (integrated) by the pad pressure device 32, the pad 26 and the pad pressing device 32, the die 28, to constitute a separately it may be. For example, be configured as holes penetrating the pad accommodating portion 28A in the vertical direction of the apparatus, the pad 26 and the pad pressure device 32, the die 28 may be configured to separately.
　The pad 26, the pad surface 26A is movable from the back side of the pad housing portion 28A (device upper side) to the position corresponding to the opening surface 28B of at least the pad housing portion 28A.
[0020]
　Pad 26 is intended to press the peripheral portion 10B of the prepared hole 10A of the material metal sheet 10. The inner diameter d of the lower hole 10A is determined depending on the flange height of the burring parts. To accommodate to the inner diameter d of any prepared hole 10A, an outer diameter D5 of the pad 26 is desirably larger. However, the pad 26 to move in the pad receiving portion 28A, the outer diameter D5 of the pad 26 is smaller than the inner diameter D7 of the pad housing portion 28A. For example, the outer diameter D5 of the pad 26 is the same dimension as the outer diameter D4 of the punch surface 22B of the punch 22 (in this embodiment, the outer diameter D5 is 50mm, for example). In addition, the pad surface 26A of the pad 26, the surface treatment such as hardening and nitriding and surface enhancement coating, etc. is applied, the surface hardened layer is formed. This is because the pad surface 26A relaxes from being damaged by rubbing against the edge of the lower hole 10A of the material metal sheet 10.
[0021]
　As shown in FIG. 1, burring apparatus 20 further comprises a control unit 36 ​​for controlling the moving device 30 and the mobile device 34. The controller 36, by the punch 22 and the pad 26, at least one of the mobile device 30 and mobile device 34 to pressurize the thickness direction of the material metal plate 10 the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10 to control. At this time the pad 26 is moved to a position that matches the opening surface 28B of the pad housing portion 28A by the pad pressure device 32. The control device 36 is in the pressurized state, the punch 22 punches 22 is moved relative to the material metal plate 10 of the thickness direction to the other side as shown in Figure 2B of the prepared hole 10A the peripheral portion 10B is extruded to form a flange 14 (see FIG. 2C), controls at least one of the mobile device 30 and mobile device 34.
[0022]
　Incidentally, burring apparatus of one embodiment of the present disclosure can be classified into the following (A) ~ (C). As can all processing of (A) ~ (C), burring device 20, the mobile device 30, the mobile device 34 may include all of the holder pressure device 60.
(A) the holder 24 is fixed, the die 28 is lowered by the moving device 34, to restrain the material metal plate 10. Punch 22 is raised to burring by the mobile device 30.
(B) the die 28 is fixed, the holder pressurizing device 60 under the holder 24 (see FIG. 11) is connected, the holder 24 by the holder pressurizing device 60 restrains material metal plate 10 rises. Punch 22 is raised to burring by the mobile device 30.
Holder pressurizing device 60 under the (C) holder 24 (see FIG. 11) is connected, die 28 is lowered by the moving device 34, a holder 24 which is pressed upward by the holder pressurizing device 60 to restrain the material metal plate 10 in the die 28. Punch 22 is fixed and the die 28 is lowered by the moving device 34, the holder 24 is pushed by the die 28, material metal plate 10 constrained by the die 28 and the holder 24 is burring lowered.
[0023]
　In burring apparatus 20, when the pad 26 is moved to the apparatus lower by pad pressing device 32, the pad 26 a peripheral portion 10B of the prepared hole 10A in the material metal plate 10 (pad surface 26A) and the punch 22 (punch It is configured to pressurize the vertical direction of the apparatus (the thickness direction of the material metal plate 10) by the surface 22B). Specifically, the pad surface 26A of the pad 26, in close contact with the upper surface of the peripheral portion 10B of the prepared hole 10A in the material metal plate 10, the punch surface 22B of the punch 22, the peripheral edge of the prepared hole 10A in the material metal plate 10 in close contact with the lower surface of 10B, substantially the entire periphery 10B of the prepared hole 10A in the material metal plate 10 is adapted to be pressurized by the pad 26 and the punch 22. In the present embodiment, of the peripheral portion 10B of the prepared hole 10A in the material metal plate 10 is configured so that the end portion 10C of at least the lower hole 10A side is pressurized by the pad 26 and the punch 22. Incidentally, pressure against the material metal plate 10 by the pad 26 and the punch 22 is appropriately set depending on the thickness and material of the material metal sheet 10. That is, in the second step of the burring process to be described later, an end portion 10C of the peripheral portion 10B of the prepared hole 10A of the material metal sheet 10 is relatively moved while sliding between the pads 26 and punch 22 eventually burring as the flange 14 to the part 12 is formed, the pressure is set appropriately.
[0024]
　(For burring method)
　will be described next burring method in the first embodiment. Burring method includes a first step of an example of the "placement step" described below, and a second step of an example of the "extrusion process", a.
[0025]
　As shown in FIGS. 1 and 2A, in a first step, located punch 22 is on one side in the thickness direction of the material metal plate 10, the side opposite to the one side in the thickness direction of the material metal sheet 10 ( as the pad 26 on the other side) is located, the material metal sheet 10 is arranged.
　At this time, the punch surface 22B of the upper surface and is flush with the punch surface 22B and the holder 24 of the punch 22 or the punch 22, is below the upper surface of the holder 24. In this state, it placed (set) the material metal plate 10 formed of the lower hole 10A on the holder 24. Specifically, the center of the pilot hole 10A of the material metal sheet 10 is in a state of being placed on the punch 22 coaxially installed (set) the material metal plate 10 on the holder 24.
[0026]
　Then, moving the die 28 to the apparatus bottom or raising the holder 24, to hold the material the metal plate 10 by the die 28 and the holder 24. That is, portions other than the peripheral portion 10B of the prepared hole 10A in the material metal plate 10 is sandwiched by the die 28 and the holder 24.
[0027]
　Further, in this state, the pad 26 is moved to the apparatus lower by pad pressing device 32, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10, the pad 26 (pad surface 26A) and the punch 22 (punch surface by 22B), pressurizing the vertical direction of the apparatus (the thickness direction of the material metal plate 10). That is, in this embodiment, in a first step, the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 is pressed by the pad 26 and the punch 22. In other words, the initial second step described below, the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 is pressed sandwiched pressurized by the pad 26 and the punch 22. In the case where the punch surface 22B of the punch 22 is below the upper surface of the holder 24, the upper surface of the punch surface 22B and the holder 24 of the punch 22 after the flush, the lower hole 10A at the material metal plate 10 pressurizing the vertical direction of the apparatus by a peripheral portion 10B pad 26 and the punch 22.
[0028]
　In the second step, from the state shown in FIG. 2A, against the pressure applied by the pad pressing device 32 is moved relatively to device upper against the die 28 and the holder 24 of the punch 22 by the moving device 30. At this time, while a pressurized state for the peripheral portion 10B of the prepared hole 10A of the material metal sheet 10 is maintained by the punch 22 and the pad 26, the punch 22 and the pad 26 is moved to the apparatus upward against the die 28 and the holder 24 . Further, at this time, the peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10 which is pressurized by the punch 22 and the pad 26, while being extruded into the apparatus the upper by the punch 22, will be formed in a tubular shape (see FIG. 2B ). Specifically, the peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10, a vertical cross section, is bent in a substantially S-shape by a shoulder portion of the shoulder portion 22A and the die 28 of the punch 22. Also, with the movement of the device the upper punch 22 and the pad 26, the inner peripheral surface of the prepared hole 10A moves between the punch 22 and the pad 26 outward in the radial direction of the punch 22. That is, (while being enlarged) pilot hole 10A gradually spread while the peripheral portion 10B of the lower hole portion 10A is gradually formed into a cylindrical shape. Finally, the end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, exits between the punch 22 and the pad 26, the punch 22 and the pad 26 with respect to the peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10 pressurized state by is canceled.
If the punch 22 and the die 28 is moved relatively the same manner, it burring like. In the second step, the punch 22 is fixed, also lowers the die 28 can have similar burring.
[0029]
　As shown in Figure 2C, at the end of the second step, inserting the end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, after exit between the punch 22 and the pad 26, the punch 22 on the inner side of the flange 14 is It is. The end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, when the exit between the punch 22 and the pad 26, the flange 14 is located radially outwardly of the pad 26. Therefore, the pad 26 by the pressure applied by the pad pressing device 32 is moved relatively apparatus bottom side of the punch 22. Thus, flange 14 is formed on the burring part 12.
[0030]
　Next, the operation and effect of this embodiment will be described in comparison with the burring method of the comparative example. In the burring method of Comparative Example, by using a burring processing apparatus not equipped with a pad 26 and the pad pressing apparatus 32 of the present embodiment, it is subjected to burring the material metal plate 10. In the following burring apparatus of the comparative example of the members has the same configuration as the burring apparatus 20 of the present embodiment, it is denoted by the same reference numerals.
[0031]
　As shown in FIG. 4A, in the burring method of the comparative example, as in the present embodiment, the upper surface of the punch surface 22B and the holder 24 of the punch 22 is below flush or top. In this state, it placed (set) the material metal plate 10 formed of the lower hole 10A on the holder 24. Furthermore, to move the die 28 to the apparatus bottom or raising the holder 24, to hold the material the metal plate 10 by the die 28 and the holder 24.
[0032]
　Then, as shown in Figure 4B, to move the punch 22 by the moving device 30 to a relatively apparatus upper against the die 28 and the holder 24. Or moving the die 28 and the holder 24 to the device bottom by the mobile device 34. At this time, the peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10, is extruded into the apparatus the upper by the punch 22, the flange 14 is formed on the material the metal plate 10.
[0033]
　Here, in the burring process, for forming the tubular flange 14 is extruded peripheral portion 10B of the prepared hole 10A formed in the material metal sheet 10 by the punch 22, the tip portion of the flange 14 after molding (hereinafter referred referred to as "tip 14A".) it is stretched in the circumferential direction of the flange 14. That is, the molding of the flange 14 by the punch 22 is a so-called stretch flangeability (be formed into an extended state the flange). Then, the material metal sheet 10 has a tensile strength of more than 440 MPa (in this embodiment, 590 MPa) and high strength steel sheet, the ductility of the material metal sheet 10 is relatively low. Therefore, as shown in FIG. 5, the high strength steel sheet and a tensile strength 590MPa plate thickness 2.9 mm, when subjected to burring of the comparative example of the hole expanding ratio 0.67 cracking the tip portion 14A of the flange 14 after molding (see a portion of FIG. 5) is generated.
[0034]
　In contrast, in the burring process of the first embodiment, as described above, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10, the plate thickness direction of the material metal sheet 10 by the punch 22 and the pad 26 while pressing to form a flange 14 on. Under hydrostatic pressure imparting compressive force from the surrounding material, it is known that the ductility of the material is increased. Thus, by compressing the peripheral portion 10B of the prepared hole 10A in the material metal plate 10, it is possible to increase the ductility at the peripheral portion 10B of the prepared hole 10A at the time of molding the flange 14. In the present embodiment, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10 are pressurized in the thickness direction of the material metal sheet 10 by the punch 22 and the pad 26. Accordingly, since the acts thickness direction of the compressive force to the peripheral portion 10B of the lower hole 10A, it is possible to the peripheral edge portion 10B of the prepared hole 10A and the pseudo hydrostatic pressure. Therefore, as compared with the comparative example, it is possible to form the flange 14 in a state of high ductility of the peripheral portion 10B of the prepared hole 10A in the material metal plate 10. In other words, in the burring method of this embodiment, as compared with the comparative example, it is possible to perform high stretch flangeability of critical hole expansion rate. As a result, it is possible to suppress the even using a relatively low material ductility, such as high-strength steel sheet, cracks on the tip portion 14A of the flange 14 after molding occurs. Thus, the shape of the punch 22 without the shape corresponding to the lower hole 10A of the material metal plate 10, it is possible to suppress cracking at the tip 14A of the flange 14 after molding. Note that under hydrostatic pressure, when brought into flooded material, but refers to a state where uniform pressure is applied to the material from the surrounding material by water pressure, in this disclosure, without flooding the material, large if the state that applies a compressive force from the surrounding under pressure in the material is referred to as "under hydrostatic pressure."
[0035]
　Further, in the burring process of the first embodiment, at least the end portion 10C of the peripheral portion 10B of the prepared hole 10A in the material metal sheet 10, pressed in the thickness direction of the material metal sheet 10 by the punch 22 and the pad 26 while to form a flange 14. Therefore, it is possible to form the flange 14 in a state of high ductility of the end portion 10C of the peripheral portion 10B of the prepared hole 10A in the material metal plate 10, that the crack in the distal end portion 14A of the flange 14 after molding occurs it can be further suppressed.
[0036]
　Then, according to the burring method of the first embodiment, and the tensile strength at 590MPa plate thickness with respect to high strength steel sheet of 2.9 mm, subjected to burring processing to the hole expanding ratio 0.67 also, cracks at the tip portion 14A of the flange 14 after molding has been confirmed that not occur. Furthermore, the tensile strength thickness and at 980MPa even for high-strength steel sheet of 2.9 mm, a crack in the distal end portion 14A of the flange 14 after molding has been confirmed that not occur.
[0037]
　In the first embodiment, the initial second step, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10 are pressurized in the thickness direction of the material metal sheet 10 by the punch 22 and the pad 26 . Therefore, from the forming initial flange 14 by the punch 22, it can be molded flange 14 while increasing the ductility of the peripheral portion 10B of the prepared hole 10A in the material metal plate 10. Accordingly, cracks can be effectively suppressed at the tip 14A of the flange 14 after molding.
[0038]
　Furthermore, in the first embodiment, by pressurizing the peripheral portion 10B of the prepared hole 10A in the material metal sheet 10 by the punch 22 and the pad 26 can be suppressed cracking at the tip 14A of the flange 14. Therefore, as has been burring method described in the background art, without the shape corresponding to the lower hole 10A to the shape of the punch 22 in the material metal sheet 10, it can be suppressed cracking at the tip 14A of the flange 14. Thus, cracking of the suppression in the tip portion 14A of the flange 14, it is possible to realize a high device configuration versatility.
[0039]
(Second Embodiment)
　Hereinafter, a burring method of the second embodiment will be described with reference to FIGS. In the second embodiment, it is subjected to burring the material metal plate 10 with a different device than the burring apparatus 20 of the first embodiment. Hereinafter, described burring apparatus 50 of the second embodiment, will next be described burring method of the second embodiment.
[0040]
(Burring apparatus 50)
　as shown in FIG. 6, the burring apparatus 50 is configured similarly to the first embodiment of the burring apparatus 20 with the following exceptions. In the following description, the burring apparatus 50, parts that are configured similarly to the burring apparatus 20 are denoted by the same reference numerals.
[0041]
　The punch surface 22B of the punch 22, a substantially disc-shaped spacer 52 (also referred to as shim) is provided, the spacer 52 is fixed to the punch 22. The spacer 52 is disposed on the punch 22 and coaxially, the outer diameter D6 of the spacer 52 is smaller than the inner diameter d of the lower hole 10A of the material metal sheet 10. Thus, in the installed state the material metal plate 10 to the burring apparatus 50 has a configuration in which the spacer 52 inside the lower hole 10A of the material metal sheet 10 is arranged. Further, in the above installation condition, the spacer 52 is interposed between the punch 22 and the pad 26.
[0042]
　Further, the thickness t of the spacer 52 is the predetermined thickness thinner than the thickness of the material metal sheet 10 (in this embodiment, the thickness of the plate thickness t is the material the metal plate 10 of the spacer 52 (2. about 66% of 9mm) (a 1.9mm)). That is, in a state in which the material metal plate 10 is installed to the burring apparatus 50, the spacer 52 does not protrude into the apparatus above the upper surface of the material metal sheet 10. Further, the thickness t of the spacer 52, the clearance C is smaller than the radial punch 22 and the die 28. The predetermined thickness of the spacer 52 may calculate the like simulating the reduction in thickness of the flange 14 from the hole expanding ratio of the flange 14 in burring, are determined based on the thickness of the flange 14 of the rear plate thickness reduction that. Specifically, the thickness t of the spacer 52 is slightly thinner thickness relative to the thickness of the flange 14 of the decreased thickness. That is, although details will be described later, the thickness t of the spacer 52 is greater with respect to the plate thickness of the flange 14 after plate thickness reduction, in the later of the second step of the burring process to be described later, the pads 26 and pressure drops for the material metal sheet 10 by punching 22. On the other hand, the thickness t of the flange 14, when the extremely thin compared to the thickness of the flange 14 of the back plate thickness reduction may impose vent to the tip portion 14A of the flange 14 after molding occurs. Therefore, the thickness t of the street spacer 52 is slightly thinner thickness relative to the thickness of the flange 14 of the decreased thickness.
[0043]
　Next, a description will be given burring method of the second embodiment. Burring method of the second embodiment, like the first embodiment, the first step of an example of the "placement step", a second step of an example of the "extrusion process", Yu doing.
[0044]
　As shown in FIG. 6, in a first step, the punch 22 is positioned on one side in the thickness direction of the material metal plate 10, the side opposite to the one side in the thickness direction of the material metal plate 10 (the other side) as the pad 26 is located, the material metal sheet 10 is arranged.
　The upper surface and the flush punch surface 22B and the holder 24 of the punch 22 or the punch surface 22B, is below the upper surface of the holder 24. In this state, it placed (set) the material metal plate 10 formed of the lower hole 10A on the holder 24. Specifically, the pilot hole 10A of the material metal sheet 10 is in a state of being placed on the punch 22 and the coaxial installation material metal plate 10 on the holder 24 to (set). Further, at this time, along with the spacer 52 inside the lower hole 10A of the material metal sheet 10 is arranged, the spacer 52 is not protruded device above the top surface of the material metal sheet 10.
[0045]
　Then, moving the die 28 to the apparatus bottom or raising the holder 24, to hold the material the metal plate 10 by the die 28 and the holder 24. Specifically, the portion other than the peripheral portion 10B of the prepared hole 10A in the material metal plate 10 is sandwiched by the die 28 and the holder 24. Instead of moving the die 28 to the device bottom, raising the holder 24 may sandwich the material metal plate 10 in the die 28 and the holder 24.
[0046]
　Further, in this state, the pad 26 is moved to the apparatus lower by pad pressing device 32 presses the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 downward. Further, the punch 22 is to be in contact with the underside of the material metal plate 10, raising the punch 22 until it contacts the material metal plate 10. At this time, since the spacer 52 does not protrude into the apparatus above the upper surface of the material metal sheet 10, between the pad surface 26A of the upper surface and the pad 26 of the spacer 52, a gap is formed. Thus, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10, by the pad 26 and the punch 22 is pressurized in the vertical direction of the apparatus (the thickness direction of the material metal plate 10). That is, in the second embodiment, in a first step, the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 is pressed by the pad 26 and the punch 22. In other words, the initial second step described below, the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 is pressed by the pad 26 and the punch 22.
[0047]
　In the second step, from the state shown in FIG. 6, against the pressure applied by the pad pressing device 32 is moved into the apparatus upward against the die 28 and the holder 24 of the punch 22 by the moving device 30. Alternatively, while holding the material metal plate 10 in the die 28 and the holder 24, the die 28 is lowered by the moving device 34. At this time, while a pressurized state for the peripheral portion 10B of the prepared hole 10A of the material metal sheet 10 is maintained by the punch 22 and the pad 26, the punch 22 and the pad 26 is moved to the apparatus upward against the die 28 and the holder 24 . Further, at this time, the peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10 which is pressurized by the punch 22 and the pad 26, while being extruded into the apparatus the upper by the punch 22, will be formed in a tubular shape (see FIG. 7 ). And, although not shown, the end of the second step, the end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, exits between the punch 22 and the pad 26, the peripheral edge of the prepared hole 10A of the material metal sheet 10 pressurized by the punch 22 and the pad 26 for the section 10B is released. Further, the peripheral edge portion 10B of the lower hole portion 10A is, after exit between the punch 22 and the pad 26, the punch 22 is inserted into the flange 14. Further, the end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, when the exit between the punch 22 and the pad 26, the flange 14 is located radially outwardly of the pad 26, by the pad pressing device 32 pressurized pad 26 is moved relatively apparatus bottom side of the punch 22 by the pressure.
[0048]
　Thus, also in the second embodiment, the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10, while being pressed by the punch 22 and the pad 26, the flange 14 is formed on the material the metal plate 10. Thus, also in the second embodiment, as in the first embodiment, it is possible to suppress the occurrence of cracks at the tip 14A of the flange 14.
[0049]
　In the second embodiment, the spacer 52 to the punch surface 22B of the punch 22 is fixed, a spacer 52 is interposed between the punch 22 and the pad 26. Thus, the distal end portion 14A of the flange 14 after molding, that scrap is generated can be suppressed. This point will be described in comparison with the first embodiment.
[0050]
　In the first embodiment, no spacer 52 is provided on the punch surface 22B of the punch 22. Therefore, as shown in FIG. 8, the end of the second step, when the end portion 10C of the peripheral portion 10B of the lower hole portion 10A is, it exits between the punch 22 and the pad 26, the pad 26 is a pad pressure device 32 by moving the relative device lower relative punch 22. Then, when the movement to the device below the pad 26, the outer peripheral edge of the pad surface 26A of the pad 26 acts to shear the substantially entire inner circumferential surface of the prepared hole 10A of the material metal sheet 10 (in FIG. 8 Referring b portion shown). Thus, by the inner peripheral surface of the prepared hole 10A of the material metal sheet 10 is sheared, or caused filamentous scrap (shear Kas) is on the tip portion 14A of the flange 14 after molding, the tip end surface of the flange 14 there is a possibility that shear marks remain. In addition, when scrap is generated, the punch 22 and pad 26 by scrap is likely damaged. Then, in the first embodiment, although the cracks on the tip portion 14A of the flange 14 does not occur, it was confirmed that some scrap is generated.
[0051]
　In contrast, in the second embodiment, the spacer 52 is provided on the punch surface 22B of the punch 22. At the end of the second step, the end portion 10C of the peripheral portion 10B of the prepared hole 10A, when exiting between the punch 22 and the pad 26, like the above, the punch 22 pad 26 by the pad pressure device 32 moving relatively to device lower relative. However, in the second embodiment, since the spacer 52 is provided between the punch 22 and the pad 26, as compared with the first embodiment, the relative movement amount is small with respect to the punch 22 of the pad 26 . Therefore, the outer peripheral edge of the pad surface 26A of the pad 26 can be prevented from shearing the entire inner peripheral surface of the prepared hole 10A of the material metal sheet 10. Thus, the scum vent to the tip portion 14A of the flange 14 after molding (shear residue) can be prevented from occurring, it is possible to reduce the shearing trace at the tip face of the flange 14. Further, by suppressing the generation of scrap, it is possible to prevent the punch 22 and pad 26 by scrap being damaged.
[0052]
　Then, in the second embodiment, 2.5mm plate thickness t, 2.0 mm, was subjected to experiments with a spacer 52 which is varied with 1.9 mm, even in the spacer 52 in any thickness, that there is no occurrence of scrap it has been confirmed. Incidentally, in the case where the thickness t of the spacer 52 and 1.9 mm (predetermined thickness), which crack the tip portion 14A of the flange 14 does not occur, 2.5mm plate thickness t of the spacer 52, 2. when a 0mm, the cracking was confirmed at the tip portion 14A of the flange 14. This is because, as described above, when forming the flange 14 by the punch 22, the flange 14 is flanged elongation, thickness of the flange 14 is reduced as compared with the plate thickness of the material metal plate 10 before forming. The thickness t of the spacer 52 is greater with respect to the plate thickness of the flange 14 after plate thickness reduction, the end portion 10C of the peripheral portion 10B of the lower hole 10A, between the punch 22 and the pad 26 before exiting, pad surface 26A of the pad 26 is in contact with the upper surface of the spacer 52, pressure against the material metal plate 10 by the pad 26 and the punch 22 is lowered. Therefore, thicker 2.5mm than the plate thickness of the plate thickness predetermined spacer 52, when a 2.0mm is cracking occurs in the distal end portion 14A of the flange 14. Thus, in consideration of the thickness of the flange 14 of the rear plate thickness reduction, by setting appropriately the thickness of the spacer 52 to a predetermined thickness, while preventing cracking at the tip 14A of the flange 14, scrap it is possible to suppress the occurrence.
[0053]
　In the second embodiment, the outer diameter D5 of the pad 26 is the same dimension as the outer diameter D3 of the punch 22. Therefore, as shown in FIG. 7, in a second step, it is possible to end portion 10C of the peripheral portion 10B of the lower hole 10A to slow the timing escaping between the punch 22 and the pad 26. Thus, to the vicinity of the molding completion of the flange 14 by the punch 22, it is possible to pressurize the raw material metal plate 10 by the pad 26 and the punch 22. Thus, it is possible to further suppress the cracking at the tip 14A of the flange 14. Incidentally, the same effect as the above can be obtained even in the configuration of the first embodiment.
[0054]
　Further, the outer diameter D5 of the pad 26, by the outer diameter D3 than the dimension of the punch 22, can be suppressed by the above-mentioned scrap is generated. That is, the outer diameter D5 of the pad 26 by the outer diameter D3 than the dimension of the punch 22, and upon completion of the forming flange 14 by the punch 22, and the end portion 10C of the peripheral portion 10B of the prepared hole 10A punch 22 pad and when exiting between 26, but substantially the same time. Thus, when the pad 26 is moved to the device lower, peripheral edge portion 10B of the prepared hole 10A of the material metal sheet 10 is molded been moved radially outward of the punch 22 as the flange 14. Thus, the outer peripheral edge of the pad surface 26A of the pad 26 are prevented from shearing the inner peripheral surface of the prepared hole 10A of the material metal sheet 10. Therefore, it is possible to further suppress the generation of scrap.
[0055]
　In the second embodiment, the thickness t of the spacer 52 is smaller than the clearance C in the radial direction of the punch 22 and the die 28, but the thickness t may be not clearance C or more. In this case, it is possible to squeeze simultaneously flange and burring.
[0056]
(Modification of the pad 26)
　Next, with reference to FIG. 9, a description will be given of a variation of the pad 26. 9, illustrated as an example of applying the present modification to the burring apparatus 20 of the first embodiment. Further, in FIG. 9, parts that are configured in the same manner as the first embodiment are denoted by the same reference numerals. In this modification, the inclined surface 26A1 is formed in the radially outer portion of the pad surface 26A of the pad 26 (the portion of the outer peripheral side). The inclined surface 26A1 is inclined to the device upward (direction away from the punch 22) as it approaches the radially outer pad surface 26A. Then, in the state where the holding material metal plate 10 with the punch 22 and the pad 26, the end portion 10C of the peripheral portion 10B of the prepared hole 10A of the material metal sheet 10 comes into contact with the inclined surface 26A1. This makes it possible to maintain the first step to the end of the second step, the sandwiched state between the punch 22 and the pad 26 relative to the end 10C of the lower hole 10A at the material metal plate 10.
[0057]
　That is, when machining the flange 14 to the material metal plate 10, sheet thickness reduction rate of the end portion 10C of the lower hole 10A at the material metal sheet 10 is considered to be the most increased. Then, as in the first embodiment and the second embodiment, in the state where the nip the peripheral edge portion 10B of the prepared hole 10A in the material metal plate 10 in a flat-shaped pad surface 26A and the punch surface 22B, at the end of the second step, there is a possibility that the gap between the micro occurs between the end portion 10C of the pad surface 26A and the lower hole 10A. In this case, the punch by 22 and the pad 26, there is a possibility that it becomes impossible to effectively sandwich the end portion 10C of the lower hole 10A. In contrast, by forming an inclined surface 26A1 to the pad surface 26A, the inclined surface 26A1 and the punch surface 22B, by holding the end portion 10C of the lower hole 10A at the material metal plate 10, the first step until the end of the second step, it is possible to maintain the sandwiched state between the punch 22 and the pad 26 relative to the end 10C of the lower hole 10A at the material metal plate 10. This allows effectively suppressing the occurrence of cracks at the tip 14A of the flange 14. Incidentally, in the case of applying the modification to the second embodiment will configure the spacer 52 is fixed to the punch surface 22B of the punch 22.
[0058]
　In the first embodiment and the second embodiment, the initial second step, and pressurizing the peripheral portion 10B of the prepared hole 10A in the material metal sheet 10 by the punch 22 and the pad 26. That is, from the viewpoint of increasing the ductility of the material metal sheet 10 during the molding of the flange 14, it is desirable to apply pressure from the initial second step the material metal sheet 10, material metal plate by punching 22 and the pad 26 10 start timing of the pressure applied to may be slow. That is, from the middle of the second step may be pressurized peripheral portion 10B of the prepared hole 10A in the material metal sheet 10 by the punch 22 and the pad 26. For example, at the beginning of the second step may be a gap between the pad surface 26A and the material metal plate 10 of the pad 26. In this case, in the second step, that the punch 22 is moved to the device upper peripheral portion 10B of the prepared hole 10A together with the punch 22 is pushed into the apparatus above, the peripheral portion 10B of the prepared hole 10A pad 26 It abuts. Thus, from the middle of the second step, the peripheral edge portion 10B of the prepared hole 10A in the material metal sheet 10 is pressed by the punch 22 and the pad 26. That is, at least, during a period from after a predetermined period starting extrusion punch 22 relative to the material the metal plate 10 to the peripheral edge portion 10B of the prepared hole 10A exits between the punch 22 and the pad 26, the prepared hole by the punch 22 and the pad 26 a peripheral portion 10B of 10A may be configured to pressurize.
[0059]
　Then, in the first embodiment, was conducted an experiment of varying the gap, the gap is up to 0 mm ~ 3 mm, crack tip 14A of the flange 14 has been confirmed that not occur. On the other hand, when the 4mm clearance is cracking at the tip portion 14A of the flange 14 it was confirmed to occur. That is, the material and thickness of the material metal sheet 10, in consideration of the hole expanding ratio of the flange 14, at the beginning of the second step, a gap is provided between the pad surface 26A and the material metal plate 10 of the pad 26 it may be.
[0060]
　In the first embodiment, the outer diameter D5 of the pad 26 is the same dimension as the outer diameter D4 of the punch surface 22B. Alternatively, the outer diameter D5 of the pad 26, and may be less outer diameter D3 of the punch 22 at the outer diameter D4 or more punch surface 22B. Furthermore, in the second embodiment, the outer diameter D5 of the pad 26 is the same dimension as the outer diameter D3 of the punch 22. Alternatively, in the second embodiment, the outer diameter D5 of the pad 26, and may be less outer diameter D3 of the punch 22 at the outer diameter D4 or more punch surface 22B. That is, to the extent that debris vent to the tip portion 14A of the flange 14 does not occur, the outer diameter D5 of the pad 26 may be changed. First embodiment, in either of the second embodiment, the outer diameter D5 of the pad 26 has an outer diameter D4 or more punch faces 22B, it is preferably not more than the outer diameter D3 of the punch 22. To as long as possible reduction of the material metal sheet 10 in the burring in the punch 22 and the pad 26 has an outer diameter D5 of the pad 26 or more is required outside diameter D4 of the punch surface 22B. However, the outer diameter D5 and a greater than an outer diameter D4, in the case where the outer diameter D5 and an outer diameter D4 equals the time that pressure the material metal plate 10 does not change. When taking out the burring part 12 from the burring apparatus 20 or burring apparatus 50, to avoid the tip portion 14A and the pad 26 of the flange interferes, outer diameter D5 is preferably less than or equal to the outer diameter D3.
[0061]
　Further, in the first embodiment and the second embodiment, "reduced diameter portion has an outer peripheral edge of the pad surface 26A of the pad 26 is substantially at right angles formed, which reduce the diameter of the outer diameter of the pad surface 26A an inclined portion of a "may be formed on the outer peripheral edge. For example, as shown in FIG. 10A, in the vertical cross section, it is formed an inclined portion 26B which is inclined linearly radially inwardly of the pad 26 in accordance with the entire outer peripheral surface of the pad 26 toward the punch 22 side good. The inclined portion 26B are overlapped at the shoulder portion 22A and the vertical direction of the apparatus of the punches 22. Further, as shown in FIG. 10B, in the vertical cross section, to form an inclined portion 26B which is inclined linearly radially inwardly of the pad 26 in accordance with a portion of the outer peripheral surface toward the punch 22 of the pad 26 it may be. Furthermore, as shown in FIG. 10C, the vertical cross section, to form an inclined portion 26B which is inclined in a curved shape radially inwardly of the pad 26 in accordance with the portion of the outer peripheral surface of the pad 26 toward the punch 22 side it may be. Thus, when the pad 26 is moved to the device under the relative punch 22, it is possible to prevent the outer peripheral surface of the pad 26 is to shear the inner peripheral surface of the prepared hole 10A of the material metal sheet 10.
[0062]
　Further, in the first embodiment and the second embodiment, the punch 22 is configured to have a flat top surface (upper surface), the punch 22 is at least the peripheral portion is only to have a flat top surface Bayoi.
[0063]
　In the second embodiment, the spacer 52 is provided on the punch surface 22B of the punch 22, it may be configured to provide a spacer 52 to the pad surface 26A of the pad 26.
[0064]
　In the second embodiment, the spacer 52 is a substantially disk-shaped, a configuration are disposed coaxially of the punch 22, to place the punch 22 coaxial spacers 52 as substantially circular ring plate-shaped it may be.
[0065]
　Further, in the first embodiment and the second embodiment, the entire punch 22 is formed in a cylindrical shape, the present disclosure is not limited to this structure. For example, it may be configured to only the portion of the punch face 22B side of the punch 22 is formed in a cylindrical shape. Further, in the first embodiment and the second embodiment, the entire pad 26 is formed in a cylindrical shape, the present disclosure is not limited to this structure. For example, it may be configured to only part of the pad surface 26A side of the pad 26 is formed in a cylindrical shape.
[0066]
　Further, in the first embodiment and the second embodiment, the flange 14 is formed in a cylindrical shape burring parts 12, the shape of the flange 14 is not limited to this. For example, the flange 14 may be formed in rectangular tubular. In this case, the punch 22 is formed in a rectangular pillar. Further, the flange 14 may be formed in a bottomed cylindrical shape. Specifically, a flange portion extending from the distal end portion 14A of the flange 14 radially inward of the flange 14 may be formed. In this case, the state shown in Figure 2B, the end of the second step of the burring process.
[0067]
　In the first embodiment and the second embodiment has been described as an example of applying the burring the material metal sheet 10, the processing member burring is performed is not limited thereto. For example, when performing a burring the press-molded article after the press molding may be applied a burring method of the first embodiment and the second embodiment. In this case, the press molded product corresponding to the "workpiece" of this embodiment.
[0068]
　Incidentally, disclosure of 2016 January 21, Japanese Patent Application No. 2016-009531, filed on, the entirety of which is incorporated herein by reference.
　All documents described herein, patent applications, and technical standards, each individual publication, patent application, and that the technical specification is incorporated by reference to the same extent as if marked specifically and individually, It incorporated by reference herein.
[0069]
　Relates above embodiments, the following additional statements are further disclosed.
[0070]
　　(Supplementary Note 1)
　punch is positioned on one side of the thickness direction of the through holes are formed plate-shaped workpiece, the pad on the opposite side to position said one side in the thickness direction of the workpiece as such, the arrangement step of arranging the workpiece,
　in a state where the periphery is pressurized in the thickness direction of the workpiece of the through hole in said workpiece by said said punch pad, the punch , an extrusion process for forming a flange by extruding a peripheral portion of the through hole by the punch is relatively moved to the opposite side with respect to the workpiece a
　burring method comprising.
[0071]
　　(Supplementary Note 2)
　burring method of statement 1, pressurizing the peripheral portion of the through hole from an initial of the extrusion process by the punch and the pad in the thickness direction of the workpiece.
[0072]
　　(Supplementary Note 3)
　In the above extrusion process, wherein at least an end portion of the periphery of the through-holes in a pressurized state in the thickness direction of the workpiece, relative to the opposite side of the punch relative to the workpiece to move, burring method according to Supplementary note 1 or 2.
[0073]
　　(Supplementary Note 4)
　on the facing surfaces of the punch in the top surface or pad of the punch, said has spacers located inside the through-hole is provided in the extrusion process, the thickness of the spacer of the workpiece thinner than the plate thickness, burring method according to any one of appendices 1 to Appendix 3.
[0074]
　　(Supplementary Note 5)
　the punch and the pad are formed in a cylindrical shape,
　the outer peripheral portion of the top surface of the punch, the punch shoulder part is connected,
　the outer diameter of the pad, equal to or greater than the outer diameter of the top surface in and it is smaller than the outer diameter of the punch, burring method according to any one of appendices 1 to Appendix 4.
[0075]
　　(Supplementary Note 6)
　The pad is formed in a cylindrical shape,
　an outer peripheral surface of the pad, Appendix 1 reduced diameter portion is formed to reduce the diameter of the outer diameter of the opposed surfaces of the punch in the pad- burring method according to any one of appendices 5.
[0076]
　　(Supplementary Note 7)
　the reduced diameter portion, burring method of statement 6 being an inclined portion that is inclined radially inwardly of the pad as it goes into the punch side.
[0077]
　　(Supplementary Note 8)
　disposed on one side of the thickness direction of the through holes are formed plate-shaped workpiece, the relative said workpiece to the opposite side to the one side of the thickness direction of the workpiece relatively and punch the mobile is the fact extruded peripheral portion of the through hole in the workpiece to form a flange, Te
　above with and facing the punch by the opposite side of the plate thickness direction of the workpiece placed, a pad for pressing a peripheral portion of the through hole in the workpiece with the punch in the extrusion process of the punch relative to the workpiece
　burring apparatus having a.
[0078]
　　(Supplementary Note 9)
　said at least an end portion of the periphery of the through-hole pressurized by said said punch pad, burring apparatus according to note 8.
[0079]
　　(Supplementary Note 10)
　The surface facing the top surface or the top surface of the pad of the punch, the spacer is provided,
　the thickness of the spacer is thinner than the thickness of the workpiece, Appendix 8 or Appendix 9 burring apparatus according to.
[0080]
　　(Supplementary Note 11)
　the top side portion of the punch is cylindrical,
　the side facing portion between the top surface of the pad is cylindrical,
　the outer peripheral portion of the top surface of the punch, punch shoulder parts are connected,
　the outer diameter of the pad, burring apparatus according to any one of a smaller than the outer diameter of and the punch on the outside diameter or is appended 8 to Supplementary note 10 of the top surface.
[0081]
　　(Supplementary Note 12)
　The pad is formed in a cylindrical shape,
　the outer peripheral surface of said pad, said appendix 8 reduced diameter portion is formed to reduce the diameter of the outer diameter of the opposing surfaces of the punches in the pad- burring apparatus according to any one of appendices 11.
[0082]
　　(Supplementary Note 13)
　The reduced diameter portion is burring apparatus according to note 12, which is an inclined portion that is inclined radially inwardly of the pad as it goes into the punch side.
[0083]
　　(Supplementary Note 14)
　and the holder disposed around the punch,
　is arranged to face the holder, it opens on the punch side, and a die having a storage portion for storing the pad,
　punch movement for moving the punch at least one device and a die moving device for moving the die,
　and a control device for controlling at least one of the punch moving device and the die moving device
　further comprising a
　said control device, wherein the through hole is formed wherein said punch disposed on one side of the thickness direction of the workpiece, the said pad and said one side of the thickness direction which is arranged on the opposite side of the workpiece, the peripheral edge of the through-holes parts at a pressurized state in the thickness direction of the workpiece, extruding a peripheral portion of the through hole by the punch said punch said is relatively moved to the opposite side of the workpiece So as to form a flange Te, wherein controlling at least one of the punch moving device and the die moving device, burring apparatus according to any one of Appendices 8 to Supplementary Note 13.
[0084]
　　(Supplementary Note 15)
　at least the peripheral portion has a flat top surface, and a punch portion of the top surface is cylindrical,
　and a holder which is disposed around the punch,
　is arranged to face the holder, a die having an accommodating portion having an opening on the punch side,
　is disposed in the housing portion is movable in the pressing direction, a pad having a surface facing the top surface of the punch
　burring apparatus comprising a.
[0085]
　　(Supplementary Note 16)
　the punch is movable in the axial direction,
　the pad is a cylindrical, is disposed in the punch coaxially, it is movable in the axial direction which is the pressing direction, Clause 15 burring device as claimed.
[0086]
　　(Supplementary Note 17)
　The pad is movable at least to a position where the facing surface coincides with the opening surface of the housing portion of the die, burring apparatus according to note 15 or note 16.
[0087]
　　(Supplementary Note 18)
　on said top surface or said opposing surface, a spacer is provided, burring apparatus according to any one of Appendices 15 to Supplementary Note 17.
[0088]
　　(Supplementary Note 19)
　The thickness of the spacer, the punch and the radial direction of the die clearance smaller, burring apparatus according to note 18.
[0089]
　　(Supplementary Note 20)
　The spacer is positioned on the axis of said punch, burring apparatus according to note 18 or note 19.
[0090]
　　(Supplementary Note 21)
　wherein the said opposing surface of the pad, burring apparatus according to any one of the surface-hardened layer is appended 15 to Supplementary Note formed 20.
[0091]
　　(Supplementary Note 22)
　comprises a punch shoulder which is chamfered at a corner between the top surface and the body of the punch, the outer diameter of the pad is equal to or greater than the outer diameter of the top surface and the outer diameter or less under the barrel in it, burring apparatus according to any one of appendices 15 to Supplementary note 21.
[0092]
　　(Supplementary Note 23)
　in the body of the punch side of said pad, inclined portion whose outer diameter decreases toward the said punch side is provided, burring according to any one of Appendices 15 to Supplementary Note 22 processing equipment.
[0093]
　　(Supplementary Note 24)
　the punch shoulder part and said inclined portion are overlapped with the pressing direction, burring apparatus according to note 23 to cite note 22.
[0094]
　　(Supplementary Note 25)
　on the outer peripheral side of the facing surface of the pad, inclined surface inclined in a direction away from said punch toward the outer periphery side of the facing surface is formed, any one of Appendixes 15 to Supplementary Note 22 burring apparatus according to (1).
[0095]
　　(Supplementary Note 26)
　A burring method of forming a cylindrical flange on the workpiece the shaped plate which the lower hole is formed,
　the processed said arranged in the thickness direction on one side of the workpiece punch has the the thickness direction other side of the member is relatively moved relative to the workpiece is extruded peripheral portion of the prepared hole of the extrusion forming of the flange,
　in the extrusion step, the workpiece plate thickness direction and the other disposed and the punch and counter to at side pad, and the punch, by burring method of pressurizing the peripheral portion of the prepared hole in the thickness direction of the workpiece for.
[0096]
　　(Supplementary Note 27)
　A burring apparatus for forming a tubular flange to be processed member like a plate which the lower hole is formed,
　the are arranged in a plate thickness direction on one side of the workpiece, the workpiece and punch the plate thickness direction the other side said by being moved relative to the workpiece is extruded peripheral portion of the pilot hole in the workpiece to form the flange,
　the plate thickness of the workpiece disposed and opposed to the punch in a direction other side, a pad for pressing a peripheral portion of the prepared hole in the workpiece with the punch in the extrusion process of the punch relative to the workpiece
　burring apparatus provided with .
[0097]
　According to the burring apparatus according to burring process or appendix 27 according to note 26, the punch is arranged in a plate thickness direction on one side of the workpiece, the pads are arranged in a plate thickness direction other side of the work member and, punch and pad are disposed to face the thickness direction of the workpiece. Then, in the extrusion step, be moved relative to the workpiece to punch the plate thickness direction other side of the workpiece, is the periphery of the prepared hole in the workpiece is extruded, the workpiece flange is formed.
　Here, in the extrusion process, the peripheral edge of the prepared hole in the workpiece is pressurized in the thickness direction of the workpiece by the punch and the pad. In other words, in the extrusion process, the peripheral edge of the prepared hole in the workpiece is, while being compressed in the thickness direction of the workpiece, the flange is formed. Therefore, it is possible to suppress the occurrence of cracks at the tip of the flange. That is, under hydrostatic pressure to impart a compressive force from the surrounding material, it is known that the ductility of the material is increased. As described above, since the peripheral edge of the prepared hole in the workpiece is compressed in the thickness direction, when the flange of the molding by the punch, to be a peripheral portion of the prepared hole under pseudo hydrostatic pressure it can. Therefore, the peripheral portion as compared with no pressurization, ductility at the peripheral portion becomes higher. Thus, when the flange of the molding, the flange is formed in a state of high ductility of the peripheral portion of the prepared hole can be suppressed generation of a crack tip of the flange. Thus, according to the burring apparatus according to burring process or appendix 27 according to note 26, without a shape corresponding to the shape of the punch under the hole of the workpiece, cracks at the tip of the flange it is possible to suppress the occurrence. In burring method and burring apparatus of the present disclosure, without flooding the material, is called "under hydrostatic pressure" if the state of applying a compressive force from the surrounding atmospheric pressure in the material.
[0098]
　　(Supplementary Note 28)
　and flat top surface, and connected to the punch shoulder part on an outer peripheral portion of said top surface, a columnar punch that is configured to include,
　a holder disposed on the outer peripheral side of the punch,
　the disposed opposite to the punch and the holder, a die having the opened housing portion to the punch side,
　movably disposed within the housing section in the opposite direction with the punch, opposite to said top surface of said punch a pad, having a facing surface disposed to
　burring apparatus having a.

WE CLAIM

[Requested item 1]Punch is located on one side of the thickness direction of the through hole is formed plate-like workpiece such that said pad on the opposite side is positioned in said one side of the thickness direction of the workpiece, the a placement step of placing the workpiece,
　in a pressurized state a peripheral portion of the through hole in the workpiece in the thickness direction of the workpiece by said said punch pad, the processed said punch , an extrusion process for forming a flange by extruding a peripheral portion of the through hole by the punch is relatively moved to the opposite side of the member
　burring method comprising.
[Requested item 2]Burring method of claim 1 for pressurizing the peripheral portion of the through hole in the thickness direction of the workpiece by the punch and the pad from the initial of the extrusion process.
[Requested item 3]
　In the extrusion step, in a state where at least the end portion was pressurized in the thickness direction of the workpiece in the peripheral portion of the through hole, is relatively moved to the opposite side with respect to the workpiece the punch , burring method of claim 1 or claim 2.
[Requested item 4]
　The opposed surfaces of the punch on the top surface or pad of the punch, said has spacers located inside the through-hole is provided in the extrusion process,
　the thickness of the spacer is thinner than the thickness of the workpiece , burring method according to any one of claims 1 to 3.
[Requested item 5]
　It said punch and said pad are formed in a cylindrical shape,
　the outer peripheral portion of the top surface of the punch, the punch shoulder part is connected,
　the outer diameter of the pad, and the punch at equal to or greater than the outer diameter of the top surface of a smaller than the outer diameter, burring method according to any one of claims 1 to 4.
[Requested item 6]
　The pad is formed in a cylindrical shape,
　an outer peripheral surface of the pad, according to claim 1, reduced diameter portion is formed to reduce the diameter of the outer diameter of the opposed surfaces of the punch in the pad - claim 5 burring method according to any one of.
[Requested item 7]
　The reduced diameter portion, burring method of claim 6 which is an inclined portion that is inclined radially inwardly of the pad as it goes into the punch side.
[Requested item 8]
　Are arranged on one side of the thickness direction of the through holes are formed plate-like workpiece, relative to the workpiece to the opposite side to the one side of the thickness direction of the workpiece and punch the by being moved by extruding a peripheral portion of the through hole in the workpiece to form a flange,
　the disposed and the punch and the counter is made in the opposite side of the plate thickness direction of the workpiece, the a pad for pressing a peripheral portion of the through hole in the workpiece with the punch in the extrusion process of the punch against the workpiece
　burring apparatus having a.
[Requested item 9]
　At least an end portion pressed by the said and the punch pad, burring apparatus of claim 8 of the peripheral portion of the through hole.
[Requested item 10]
　The opposing surfaces of the top face on the top surface or the pad of the punch, the spacer is provided,
　the thickness of the spacer is thinner than the thickness of the workpiece, according to claim 8 or claim 9 burring device.
[Requested item 11]
　Top side portion of the punch is the cylindrical,
　surface facing portion between said top surface of said pad is cylindrical,
　the outer peripheral portion of the top surface of the punch, the punch shoulder part is connected and which,
　outside diameter of the pad, burring apparatus according to any one of claims 8 to claim 10 outer diameter or on and in a not more than the outside diameter of the punch of the top surface.
[Requested item 12]
　The pad is formed in a cylindrical shape,
　an outer peripheral surface of the pad according to claim 8 in which the reduced diameter portion is formed to reduce the diameter of the outer diameter of the opposed surfaces of the punch in the pad-claim 11 burring apparatus according to any one of.
[Requested item 13]
　The reduced diameter portion is burring apparatus of claim 12 which is an inclined portion that is inclined radially inwardly of the pad as it goes into the punch side.
[Requested item 14]
　A holder disposed around the punch,
　is arranged to face the holder, it opens on the punch side, and a die having a storage portion for storing the pad,
　punch moving device and said die to move said punch at least one of the die moving device moves, the
　control device for controlling the at least one of the punch moving device and the die moving device,
　further comprising a
　said control device, the workpiece in which the through holes are formed and the punch disposed on one side of the thickness direction of the member, by the said pad disposed on the opposite side to the one side of the thickness direction of the workpiece, the object of the periphery of the through hole in a pressurized state in the thickness direction of the workpiece, the flange the punch peripheral portion of the through hole is extruded by said punch are relatively moved to the opposite side of the workpiece So as to form, the controls at least one of the punch moving device and the die moving device, burring apparatus according to any one of claims 8 to claim 13.
[Requested item 15]
　At least the peripheral portion a flat top surface, and a punch portion of the top surface is cylindrical,
　and a holder which is disposed around the punch,
　is arranged to face the holder, the punch side a die having an opening with the housing part,
　is disposed in the housing portion is movable in the pressing direction, a pad having a surface facing the top surface of the punch
　burring apparatus comprising a.
[Requested item 16]
　The punch is movable in the axial direction,
　the pad has a cylindrical shape, and the disposed punch coaxially, is movable in the axial direction which is the pressing direction, burring of claim 15 processing equipment.
[Requested item 17]
　The pad is movable at least to a position where the facing surface coincides with the opening surface of the housing portion of the die, burring apparatus of claim 15 or claim 16.
[Requested item 18]
　Wherein the top surface or the opposing surface, a spacer is provided, burring apparatus according to any one of claims 15 to claim 17.
[Requested item 19]
　The thickness of the spacer, the punch and radial clearance is smaller than said die, burring apparatus of claim 18.
[Requested item 20]
　The spacer is positioned on the axis of said punch, burring apparatus of claim 18 or claim 19.
[Requested item 21]
　Burring apparatus according to any one of the the said opposite surface in the pad, wherein the surface hardened layer is formed to claim 15 to claim 20.
[Requested item 22]
　Comprising a punch shoulder which is chamfered at a corner between the top surface and the body of the punch, the outer diameter of the pad is smaller than the outer diameter of the outer diameter or on and the barrel of the top surface, wherein burring apparatus according to any one of claims 15 to claim 21.
[Requested item 23]
　The body portion of the punch side of said pad, inclined portion whose outer diameter decreases toward the said punch side is provided, burring apparatus according to any one of claims 15 to claim 22 .
[Requested item 24]
　The punch shoulder part and said inclined portion are overlapped with the pressing direction, burring apparatus of claim 23, quoting Claim 22.
[Requested item 25]
　On the outer circumferential side of the facing surface of the pad, inclined surface inclined in a direction away from said punch toward the outer periphery side of the facing surface is formed, any one of claims 15 to claim 22 burring apparatus according to.