JP2006326665A - Method and apparatus for straightening warping of flange of forging work piece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for straightening the warping of a flange in a forging work piece suitable to stable settlement of the straightening force. <P>SOLUTION: In a lower die 5, a supporting part 21A for supporting a flange W1 in the forging work piece W from the lower surface along to the lower surface shape is arranged, and in an upper die 6, a stripper 28 formed along the upper surface shape of the flange W1 in the forging work piece W and coming into contact with the upper surface of the flange W1 at a step on the way of the die-closing, and a straightening retainer 29 projectively energized at the lower die side with springs 38 and attachable to the stripper 28 from the back surface side, are arranged. Then, pressurizing force is applied to the stripper 28 by abutting the straightening retainer 29 on the back surface of the stripper 28 since just before the finishing of the die casting. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flange warpage correction method and a correction device for a forged workpiece when a workpiece having a flange on the outer peripheral side represented by a wheel hub of an axle is manufactured by multistage forging, and in particular, a through hole is provided on the inner peripheral side. The present invention relates to a method and apparatus for correcting flange warpage of a forged workpiece.

  When an annular workpiece having a flange on the outer peripheral side and a through hole on the inner peripheral side is manufactured by multistage forging, generally, for example, the outer shape of the forged workpiece including the flange is finished in the third step. In the subsequent piercing step arranged in the fourth step, the inner peripheral through hole is formed. In the case of closed forging in which the punch of the upper die enters into the lower die that has been carved, the finish molding is performed at the outer periphery of the flange and the side of the die-sculpted surface of the lower die when knocking out the forged workpiece after molding. Since the forged workpiece is pushed up while contacting with each other, the flange is warped to the lower mold side due to the frictional resistance of both.

As a method for correcting such distortion and improving the shape accuracy, a method of correcting the distortion by a coining process using a work punch and a receiving die has been proposed (see Patent Document 1). This is because of the trim molding process in which the through hole is punched out by the shearing action of the trim die and the piercing punch in the process of lowering the upper die, and the receiving die is die-based immediately before the upper die reaches the bottom dead center position following the trim molding. In addition, a coining process is provided to press and restrain the product shape portion from above and below by the receiving die and the work punch until each of the work punches bottoms out to reach the bottom dead center position. .
JP 2001-347335 A

  However, in the above conventional example, the product is sandwiched between the receiving die and the work punch to correct the product warp (coining), and the correction force (correction amount) varies depending on the position of the bottom dead center of the press. Subtle adjustment of the bottom dead center position was necessary.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a flange warpage straightening method and a straightening device for a forged workpiece suitable for ensuring a stable straightening force.

  The present invention provides a flange warpage straightening device that presses a flange provided on the outer peripheral side of a forging work in the thickness direction by a press stroke of the forging die to obtain its shape accuracy. A support portion that is supported from the lower surface along the upper surface is formed along the upper surface shape of the flange of the forged workpiece on the upper die, and a stripper that comes into contact with the upper surface of the flange from an intermediate stage of mold closing and an elastic member on the lower die side A straightening retainer which is urged and is able to come into contact with the stripper from the back side is disposed, and the straightening retainer is brought into contact with the backside of the stripper immediately before the closing of the mold to apply pressure to the stripper.

  Therefore, in the present invention, the lower mold is provided with a support portion for supporting the flange of the forged workpiece from the lower surface along the shape of the lower surface, the upper die is formed along the upper surface shape of the flange of the forged workpiece, and the mold is closed A stripper that comes into contact with the upper surface of the flange from the stage, and a correction retainer that is urged toward the lower mold side by an elastic member and that can come into contact with the stripper from the back side are arranged, and the correction retainer is installed immediately before the end of mold closing. Since the pressing force is applied to the stripper in contact with the stripper back, the correction force (correction amount) must be secured stably without being affected by the movement of the press ram, that is, the position of the press bottom dead center. Therefore, the flange can be stably corrected without causing the flange to be crushed or insufficiently corrected.

  Hereinafter, a flange warpage correction method and correction device for a forged workpiece according to the present invention will be described based on an embodiment shown in FIGS. FIG. 1 is a partial cross-sectional view of a multistage forging machine to which the present invention is applied, FIG. 2 is an enlarged cross-sectional view of a main part of a flange warpage correction apparatus for forging workpieces, and FIG. 4 to 6 are sectional views showing the operation state of the flange warpage correction apparatus together with the operation of the forging die in the final process of the forging machine, and FIG. 7 is a view of the forging mold in the finish forming process. It is sectional drawing which shows an operation state.

  FIG. 1 shows a forging die constituting a finish forming process and a piercing process of a multistage forging machine. First, the forging die and the finish forming method in the finish forming step will be described, and then the forging die and the piercing method in the piercing forming step will be described.

  The forging die 1 in the finish forming step includes a finish die 10 (hereinafter, only referred to as a die) having a die carving space 11, a die holder 13 for fixing the die 10 to the die base 12, and a die base in the die carving space 11 of the die 10. A lower die 2 comprising a cylindrical knockout punch 14 facing from the side 12 and a lower movable punch 15 slidably disposed in the knockout punch 14 is fixed to the base side of the press machine. Each of the lower movable punch 15 and the knockout punch 14 includes a driving mechanism (not shown) that protrudes from the base side of the press machine into the mold carving space 11. The upper die 3 fixed to the ram of the press machine includes a cylindrical punch 16 that presses the workpiece W by fitting into the die-sculpting space 11 of the die 10, a punch holder 18A that holds and fixes the punch 16 to the punch case 17, and A tightening ring 18B and an upper movable punch 19 slidably disposed in the punch 16 are provided. The upper movable punch 19 is provided with a drive mechanism (not shown) that protrudes toward the mold carving space independently of the ram.

  In the finish forming step, the workpiece W put in the die-sculpting space 11 of the die 10 is supported by the lower-side movable punch 15 and the knock-out punch 14 located on the surface of the die-sculpting space 11 of the die 10 and the retracted position. Next, the upper die 3 is lowered in the die closing direction by lowering the ram, the tip of the punch 16 is pushed into the die carving space 11 of the die 10, and the workpiece W inserted into the die carving space 11 is sealed in the die carving space 11. It is plastically deformed by forging and formed along the surface of the die-sculpting space 11. Eventually, the upper movable punch 19 and the lower movable punch 15 are pushed into the mold engraving space 11 so that the surface of the workpiece W is brought into contact with the entire surface of the mold engraving space 11 for finish forming. Is executed.

  After the completion of molding, the upper die 3 is raised by the ram to open the die, and the knockout punch 14 of the lower die 2 is raised along with the die opening, so that the molding workpiece W is detached from the die-sculpting space 11 of the die 10. . In the process of knockout, each outer surface of the workpiece W is in close contact with the surface of the die-sculpting space 11, so that the outer circumferential surface of the flange W1 protruding from the outer periphery of the workpiece W as shown in FIG. It detaches upward while rubbing against the side surface of the mold carving space 11. For this reason, as shown in FIG. 7B, the outer periphery of the flange W1 may be distorted and deformed downward. That is, as the surface of the mold carving space 11 becomes rough due to wear, the frictional resistance with the workpiece W increases, and the frequency of occurrence of distortion deformation of the flange W1 increases.

  The forging die 4 in the piercing process includes a receiving die 20 (hereinafter, only a die) including a die-sculpting space 21 having the same shape as that of the die 10 in the finish forming process in a range up to a portion contacting the lower surface of the flange W1 of the workpiece W. The lower die 5 comprising a die holder 23 for fixing the die 20 to the die base 22 and a cylindrical knockout punch 24 facing the die engraving space 21 of the die 20 from the die base 22 side is fixed to the base side of the press machine. Prepare. The knockout punch 24 includes a knockout pin 25 that is driven by a driving mechanism (not shown) that protrudes from the base side of the press machine into the mold carving space 21. The upper die 6 fixed to the ram of the press machine is in contact with the upper surface of the flange W1 of the workpiece W put into the die 20 and presses the flange W1 against the flat surface portion 21A of the die carving space 21 of the die 20; A piercing punch 26 that is inserted into the center of the workpiece W on the die 20 to perform piercing, a punch case 27 that supports the piercing punch 26 and the stripper 28, and a punch case 27 that can be moved forward and backward. And a straightening retainer 29 that contacts the stripper 28 and presses the stripper 28 in the middle of lowering.

  As shown in FIG. 3, the punch case 27 includes a plurality of stepped through holes 30 having a small diameter on the lower mold 5 side provided at equal intervals around the pierce punch 26. An extension cylinder 31 having a large diameter on the upper end side away from the lower mold 5 is slidably accommodated in the cylinder 30, and a stepped through-hole 32 having a small diameter on the lower mold 5 side is also provided in the extension cylinder 31. The stripper pin 33 is slidably inserted, and the stripper 28 is fixed to the tip of the lower die 5 side of the stripper pin 33. The stripper pin 33 is provided with a piston 34 slidable on the inner surface of the large diameter hole of the stepped through hole 32 of the extension cylinder 31. A compression spring 35 is interposed between the stripper 28 and the extension cylinder 31, and the stripper 28 is urged against the extension cylinder 31 so as to protrude toward the lower mold 5, and the step of the piston 34 and the extension cylinder 31 is performed. The stripper 28 can be protruded toward the lower die 5 until the stepped portion of the stepped through hole 32 is engaged, and the extension cylinder 31 is moved toward the lower die 5 in the stepped through hole 30 of the punch case 27. By descending, the stripper 28 can be further projected to the lower mold 5 side.

  As shown in detail in FIG. 2, the straightening retainer 29 is slidable in a plurality of receiving holes 37 that are opened around the piercing punch 26 of the punch case 27 toward the lower mold 5 and provided at equal intervals. It is inserted and pressed from the back by a compression spring 38 as an elastic member inserted into the receiving hole 37 and pressed in a direction protruding from the receiving hole 37. The through hole 39 at the center of the straightening retainer 29 is formed as a stepped hole having a large diameter portion and a small diameter portion, and the shaft portion of the restraining rod 40 with the head fitted to the large diameter portion passes through the small diameter hole and is accommodated. The bottom of the hole 37 is fixed with a screw or the like. For this reason, the straightening retainer 29 is biased in the protruding direction by the compression spring 38 on the back surface, but the stepped portion between the head and the shaft portion of the restraining rod 40 has a large diameter portion and a small diameter of the stepped hole 39. By engaging the stepped part between the two parts, further protrusion is restrained. In this case, the compression spring 38 inserted in the back surface of the straightening retainer 29 is set in a compressed state to give a preload, and the straightening retainer 29 protrudes from the bottom surface of the punch case 27 by a length defined by the restraining rod 40. It has become.

  The piercing forming operation and the correcting operation in the piercing forming process for the forged workpiece W including the flange W1 that has undergone distortion deformation in the finishing forming process, that is, the flange warping correcting method and the correcting device for the forging work having the above-described configuration will be described below. .

  In the mold open state, the ram and the upper mold 6 are raised, and the lower mold 5 exposes the mold carving space 21 so that the upper side of the die 20 (receiving die) is released.

  First, a forged workpiece W that has been finish-formed by a finish-forming process by a conveying device (not shown) is put into the die-sculpting space 21 of the die 20. The charged forged workpiece W is accommodated in a die-sculpting space 21 having the same shape as that in the finish molding process, and is placed in a locate state in which the flange portion W1 is in contact with a flat surface portion 21A formed around the die-sculpting space 21. .

  The ram and upper mold 6 are lowered to perform piercing. The piercing punch 26 is lowered by the movement of the ram, and the stripper 28 suspended from the stripper pin 33 and the extension cylinder 31 is also lowered. As the mold closing proceeds, the stripper 28 starts to contact the flange W1 of the workpiece W before the piercing punch 26 contacts the workpiece W.

  As the mold is further closed, the extension cylinder 31 moves back into the punch case 27, the tip of the piercing punch 26 comes into contact with the workpiece W, and piercing is started (see FIG. 3). This piercing process proceeds as the mold is closed. The stripper 28 that is in contact with the flange W <b> 1 of the workpiece W is applied with contact pressure by the compression spring 35 as the extension cylinder 31 moves backward.

  The correction retainer 29 and the stripper 28 begin to come into contact with each other just before the extension cylinder 31 is contracted. When the straightening retainer 29 comes into contact with the stripper 28, as shown in FIG. 4A, the stripper 28 is pressed toward the flange W1 of the workpiece W by the compression load by the compression spring 38 that is compressed with a preload on the back surface. To do. As the ram is lowered, the compression spring 38 starts to be compressed, so that the repulsive force is increased and the pressing force is increased to start correcting the flange W1 of the workpiece W.

  When the ram reaches the bottom dead center, as shown in FIG. 4B, the piercing with the piercing punch 26 is completed, the repulsive force from the compression spring 38 on the back against the straightening retainer 29 is maximized, and the work W by the stripper 28 The straightening force with respect to the flange W1 is also maximized. As the ram rises, as shown in FIG. 5, the compression spring 38 also starts to expand, and the pressing of the workpiece W against the flange W1 by the stripper 28 is also terminated.

  As shown in FIG. 6A, when the ram is further raised, the piercing punch 26 is also pulled out from the workpiece W, and the correction retainer 29 is detached from the upper surface of the stripper 28. When the ram further rises, the piercing punch 26 is completely extracted from the workpiece W, the extension cylinder 31 is extended, and at the stage where it is extended to the maximum, as shown in FIG. It is detached from the upper surface of the flange W1, the knockout punch 24 of the lower die 5 is driven by the knockout pin 25 and pushed upward, and the workpiece W is protruded from the die carving space 21 of the die 20. The ram continues to rise to top dead center and mold opening is complete.

  In the above embodiment, the forging die to be applied is described as being applied to the forging die 4 in the piercing molding process. However, although not illustrated, it may be implemented as a single flange correction die, It may be arranged in the middle of a multistage forging machine or applied to the final process.

  In the above embodiment, the compression spring 38 that biases the straightening retainer 29 is described as being in a preloaded state in which a compression load is applied in advance. In that case, it is preferable to use a compression spring having a high elastic modulus with a large rise in compression load with respect to the ram stroke.

  In the present embodiment, the following effects can be achieved.

  (A) A support portion 21A for supporting the flange W1 of the forged workpiece W from the lower surface along the lower surface shape is disposed on the lower die 5, and the upper die 6 is formed along the upper surface shape of the flange W1 of the forged workpiece W. A stripper 28 that comes into contact with the upper surface of the flange W1 from the middle of mold closing and a straightening retainer 29 that is urged toward the lower mold side by a spring 38 as an elastic member and that can come into contact with the stripper 28 from the back side are disposed. Since the straightening retainer 29 is brought into contact with the back surface of the stripper 28 immediately before the end of mold closing, and the pressing force is applied to the stripper 28, the straightening force (correction amount) is the movement of the press ram, that is, the press is dead. The flange W1 can be secured stably without being affected by the position of the point, and the flange W1 can be stably corrected without causing excessive crushing or insufficient correction of the flange W1. Kill.

  (A) When the spring 38 as an elastic member disposed on the back surface of the straightening retainer 29 is set in a preloaded state in which a compression load is applied in advance, the straightening force (correction load) can be arbitrarily set by setting the compression load. The corrective force according to the thickness of the flange W1 can be obtained.

  (C) As a forging die to be applied, the flange W1 distortion of the forged workpiece W is adjusted in synchronization with the forging machine by arranging it in the final stage of the multistage forging machine or the subsequent stage of the finish forming process which is closed forging. be able to.

  (D) As the forging die to be applied, the straightening retainer 29 is integrated with the piercing die 4 in the piercing step of the multi-stage forging machine and immediately before the end of closing the die against the stripper 28 of the piercing die 4. If the pressing force is applied to the stripper 28 by contacting the back surface of the stripper 28, it is possible to correct the warp in the existing piercing forming process, there is no need to increase the number of processes, and the productivity of the forged workpiece W is affected. Does not appear.

Sectional drawing of the flange curvature correction apparatus of the forge workpiece | work which shows one Embodiment of this invention. Similarly the expanded sectional view of the principal part of the flange curvature correction apparatus of a forge workpiece. Sectional drawing which applied the flange curvature correction apparatus to the forging die of the last process of a multistage forging machine. Sectional drawing of the operation state which divided and shown operation | movement of the flange curvature correction apparatus to (A) and (B) sequentially with the operation | movement of the forging die of the last process of a forging machine. Sectional drawing of the operation state which showed the action | operation of the flange curvature correction apparatus following FIG. 4 with the action | operation of the forging die of the last process of a forging machine. Sectional drawing of the operation state which divided | segmented and showed operation | movement of the flange curvature correction apparatus following FIG. 5 to (A) and (B) sequentially with the operation | movement of the forging die of the last process of a forging machine. Sectional drawing which shows the action | operation at the time of the knockout of the workpiece | work in a finish shaping | molding process.

Explanation of symbols

1 Finishing mold 2, 5 Lower mold 3, 6 Upper mold 4 Piercing mold 10, 20 Die 11, 21 Die-cutting space 12, 22 Die base 15, 19 Movable punch 16 Punch 17, 27 Punch case 28 Stripper 29 Correction Retainer 38 Compression spring as elastic member

Claims (6)

In the flange warpage straightening device that presses the flange provided on the outer peripheral side of the forging work in the thickness direction by the press stroke of the forging die to obtain the shape accuracy,
Place the support part to support the flange of the forged workpiece from the lower surface along the lower surface shape on the lower mold,
A stripper is formed on the upper die along the top surface shape of the flange of the forged workpiece, and comes into contact with the top surface of the flange from the middle of the mold closing. Arrange a corrective retainer that can be touched,
A flange warpage correction apparatus for a forged workpiece, wherein a pressure is applied to the stripper by bringing the correction retainer into contact with the back surface of the stripper immediately before the end of mold closing.   The forged workpiece flange warpage correction apparatus according to claim 1, wherein the elastic member disposed on the back surface of the straightening retainer is set in a preloaded state in which a compressive load is applied in advance.   The forged workpiece flange warpage correction apparatus according to claim 1, wherein the forging die is arranged in a final step of a multistage forging machine.   3. The apparatus for correcting a warpage of a forged workpiece according to claim 1, wherein the forging die is arranged in a step subsequent to a finish forming step, which is hermetic forging of a multi-stage forging machine.   The forging die is integrated with a piercing mold that performs piercing of a multistage forging machine, and the straightening retainer is brought into contact with the back surface of the piercing mold stripper immediately before the end of mold closing. The apparatus for correcting a warpage of a flange of a forged workpiece according to claim 1 or 2, wherein a pressing force is applied to the stripper. In the flange warpage correction method in which the flange provided on the outer peripheral side of the forging workpiece is pressed in the thickness direction by the press stroke of the forging die and the shape accuracy is determined.
In the piercing process of a multi-stage forging machine, immediately before the end of mold closing, the straightening retainer is brought into contact with the back surface of the stripper, and the pressure is applied from the straightening retainer to the stripper via the elastic member by the stroke of the upper die. A forging work flange flange warping method, characterized in that is pressed against a lower die.

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