JP2005349433A - Forming method and forming device for press formed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method for a press formed article where the corner part of a stepped flange can be sharply formed by increasing the fluidity of the material. <P>SOLUTION: In a state where the bottom part 12b of a work 12 previously formed into a cut shape in a prestage is inserted an inner punch 9b and a movable pad 10b, the bottom part 12b of the work 12 is press-fitted into a cavity 13 of a fixed die 10a by an inner punch 9b, and, at the time when the corner part 12c of the work 12 reaches a tapered face 10e formed at the fixed die 10a, while pressurizing the corner part 12c by the tapered face 10e, simultaneously, the edge face of the flange 12a in the work 12 is pressurized by an outer punch 9b, thus the material is made to flow through a corner forming part 9f in the inner punch 9b, so as to form a step part 12d. Since the material can be filled into the corner forming part 9f while suppressing the sagging of the material, the step part 12d having a sharp corner part can be formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for forming a press-formed product having a stepped flange.

  2. Description of the Related Art Conventionally, for example, parts such as a transmission and a clutch of an automobile use a press-formed product obtained by forming a plate material such as a steel plate into a drum shape.

These press-molded products are drawn by dividing the plate material into a plurality of processes (refer to Patent Document 1). However, since the corner portion R becomes large and sagging occurs during molding, highly accurate press-molded products. There are problems such as difficult to obtain.
JP-A-11-169980.

  In order to improve such a problem, for example, Patent Document 2 proposes a method for forming a part in which it is desired to reduce the occurrence of sagging in a corner portion.

In the part molding method described in Patent Document 2, when the plate material is drawn into a drum shape in the previous step, the bottom part of the part is sandwiched between the movable punch and the movable pad while pressing the inner flange end face of the primary processed part. Next, the end face of the inner flange is pressed with a movable pressure punch, and the inner flange and the outer flange are pressed in opposite directions to form the material, so that the material flows to the corner of the outer flange from at least two directions. The corner part of the outer flange is formed at a substantially right angle, and since the material that has flowed in two directions collides with the corner part to suppress the sagging, a good quality part without sagging in the corner part is obtained. It is supposed to be.
JP-A-8-309469 (Japanese Patent No. 3398922).

  The component molding method described in Patent Document 2 attempts to cause the material to flow in the corner portion by pressing the end face of the inner flange in one direction with a movable pressure punch.

  For this reason, the molding method described in Patent Document 2 is effective when the material is allowed to flow only at the corner portion of the outer flange of the component and the corner portion is molded at a substantially right angle, as shown in FIG. In the case of a stepped flange having a plurality of corner portions, if the corner portion a is formed so as to be substantially perpendicular, the flow of the material cannot be said to be sufficient, and defects such as curling up and overlapping of the material in the corner portions b and c. The corner portion a cannot be formed at a substantially right angle, and the wall thickness of the corner portions b and c is insufficient and a predetermined strength cannot be obtained.

  In particular, when the press-formed product is a clutch drum used for a clutch, since the piston d is slidably accommodated between the corner portion a and the corner portion b, the corner portion a is not right-angled but R. In order to ensure the effective stroke S of the piston d, the distance between the corner part a and the corner part b must be increased. As a result, the length of the clutch drum in the axial direction becomes longer, resulting in a larger part. In addition, there is a problem in that the cost of parts becomes high.

  The present invention has been made in order to improve such a conventional problem. A molding method and a molding apparatus for a press-molded product capable of sharply molding a corner portion of a stepped flange by increasing fluidity of a material. It is intended to provide.

  The press-molded product molding method of the present invention comprises an upper die comprising an inner punch elastically supported by a die cushion, and a ring-shaped outer punch provided on the outer periphery of the inner punch. And a lower pad made of a movable pad elastically supported by a die cushion and a fixed die provided on the outer periphery of the movable pad, wherein the bottom of the workpiece is an inner punch. With the inner punch sandwiched between the movable pads, the bottom of the workpiece is press-fitted into the cavity of the fixed die, and when the corner of the workpiece reaches the tapered surface formed on the fixed die, the corner is cut by the tapered surface. By pressing the flange end surface of the workpiece with the outer punch at the same time while squeezing, the material flows to the corner molding part of the inner punch, It is obtained so as to mold a stepped portion having a sharp corner portion on the inner peripheral surface of the over click.

  By the above method, it is possible to fill the material in the corner forming part of the inner punch while suppressing the material sagging, and thus it is possible to form a stepped part having a sharp corner part on the inner peripheral surface of the work. For example, by applying the molded product to a clutch drum of a clutch that is an automobile part, a predetermined effective piston stroke can be secured without increasing the axial length of the clutch drum. Since the device itself does not increase in size, the parts cost can be reduced.

  In addition, defects due to rolling up and overlapping of materials and defects such as local sink marks caused by a shortage of material flowing into the corner molding portion can be prevented. Since a smooth molding surface can be obtained when the material sufficiently flows into the corner molding portion, machining after molding becomes unnecessary, thereby reducing the machining cost.

  In the method for forming a press-formed product according to the present invention, the angle of the taper surface is set to a predetermined angle corresponding to the stepped shape of the workpiece with respect to the axis of the fixed die, and R is formed at the end of the taper surface. The workpiece is formed using a fixed die.

  By the above method, the material can be smoothly flowed to the corner molding part by the tapered surface and the R part, so that the local part caused by the shortage of the material flowing into the corner molding part or the defect due to the curling up or overlapping of the material. This makes it possible to prevent defects such as typical sink marks, and thereby, it becomes possible to easily and economically obtain a press-formed product of good quality without defects.

  In the method for forming a press-formed product of the present invention, the cushioning force of the die cushion that elastically supports the inner punch is several times larger than the cushioning force of the die cushion that elastically supports the movable die.

  By the above method, the inner punch always balances with the cushioning force of the movable pad while maintaining a predetermined pressurizing force, whereby the material that has flowed to the corner molding portion becomes redundant. However, it does not cause defects such as curling up and overlapping of meat, and the material sagging is suppressed, so that a high-quality press-formed product in which the corner portion of the step portion is formed almost at right angles can be obtained. It becomes like this.

  The press-molded product molding method of the present invention comprises an upper die comprising an inner punch elastically supported by a die cushion, and a ring-shaped outer punch provided on the outer periphery of the inner punch. And a lower pad made of a movable pad elastically supported by a die cushion and a fixed die provided on the outer periphery of the movable pad, wherein the bottom of the workpiece is an inner punch. With the inner punch sandwiched between the movable pads, the bottom of the workpiece is press-fitted into the cavity of the fixed die, and when the corner of the workpiece reaches the tapered surface formed on the fixed die, the corner is cut by the tapered surface. By pressing the flange end surface of the workpiece with the outer punch at the same time while squeezing, the material flows to the corner molding part of the inner punch, After forming the stepped portion having a sharp corner portion on the inner peripheral surface of the over-click, it is obtained by the workpiece to perform the overall shape out molding by restriking step.

  According to the above method, in addition to the effects of the first to third aspects, the corner portion on the outer peripheral side of the step portion can be sharply formed, and the molding accuracy of the entire molded product is improved.

  The press-molded product forming apparatus of the present invention comprises an inner punch elastically supported by a die cushion, and a ring-shaped outer punch provided on the outer periphery of the inner punch. A molding apparatus for a press-molded product for press-molding between a mold and a lower mold comprising a movable pad elastically supported by a die cushion and a fixed die provided on the outer periphery of the movable pad, wherein the bottom of the workpiece is With the inner punch sandwiched between the inner punch and the movable pad, the inner punch press-fits the bottom of the workpiece into the cavity of the fixed die, and the corner of the workpiece is formed on a tapered surface formed on the fixed die. Is reached, the flange end surface of the workpiece is pressurized by the outer punch at the same time as the corner portion is squeezed by the tapered surface. Accordingly, the material allowed to flow into the corner molding part of the inner punch, and having the molding portion for molding the stepped portion having a sharp corner portion on the inner peripheral surface of the workpiece.

  Since the material can be filled in the corner forming part of the inner punch while suppressing the sagging of the material by the forming device, a step part having a sharp corner part on the inner peripheral surface of the work can be formed. By applying the formed product to a clutch drum of a clutch, which is an automobile part, for example, a predetermined piston effective stroke can be secured without increasing the axial length of the clutch drum. Since the clutch itself does not increase in size, the cost of parts can be reduced.

  In addition, defects due to rolling up and overlapping of materials and defects such as local sink marks caused by a shortage of material flowing into the corner molding portion can be prevented. Since a smooth molding surface can be obtained when the material sufficiently flows into the corner molding portion, machining after molding becomes unnecessary, thereby reducing the machining cost.

  According to the present invention, it is possible to form a stepped portion having a sharp corner portion on the inner peripheral surface of the workpiece, and by applying the obtained molded product to a clutch drum of a clutch that is an automobile part, for example, The piston effective stroke can be ensured without increasing the axial length of the clutch drum, and the clutch drum and the clutch itself do not increase in size, so that the cost of parts can be reduced.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view of a clutch using a clutch drum, which is a press-molded product molded according to the present invention, FIG. 2 is a sectional view of a molding apparatus for molding a press-molded product, and FIGS. 3 to 8 are steps showing a molding method. FIG.

  A wet multi-plate clutch, which is a functional part of an automobile, has a clutch drum 1 obtained by press-forming a plate material such as a steel plate as shown in FIG.

  The clutch drum 1 has a flange 1c composed of a large-diameter portion 1a and a small-diameter portion 1b, a step portion 1d between the large-diameter portion 1a and the small-diameter portion 1b of the flange 1c, and a central portion. The opened mounting hole 1e is fixed to the rotating shaft 2, and the clutch drum 1 is rotated integrally with the rotating shaft 2.

  The small-diameter portion 1b of the clutch drum 1 is a cylinder, and the piston 3 is slidably accommodated in the small-diameter portion 1b. The hydraulic pressure in the small-diameter portion 1b is less than the oil passage 2a formed in the rotating shaft 2. The piston 3 is moved to the clutch plate 5 side by the pressure oil supplied into the chamber 4.

  The clutch plate 5 is formed by alternately stacking a plurality of drive plates 5a and driven plates 5b, and the outer peripheral portion of the drive plate 5a is spline-engaged with the inner peripheral surface of the large-diameter portion 1a of the clutch drum 1. .

  The inner peripheral portion of the driven plate 5 b is spline-engaged with a pressure receiving plate 6 that is rotatably supported by the rotary shaft 2, and is between the piston 3 and the pressure receiving plate 6 that is operated by the pressure oil supplied to the hydraulic chamber 4. Thus, the drive plate 5a and the driven plate 5b of the clutch plate 5 are pressed against each other so that the rotational power of the rotary shaft 2 is transmitted to the pressure receiving plate 6 side. When discharged, the return spring 7 returns the piston 3 to its original position, and the transmission of power is cut off.

  The above is a configuration of a wet multi-plate clutch used in, for example, an automatic transmission of an automobile. A press-formed product having a stepped flange is used for the clutch drum 1 used in this clutch.

  The press for molding the clutch drum 1 uses a double-acting press (not shown) in which an upper slide and a lower slide (both not shown) move simultaneously in the contact / separation direction. 8 is composed of an upper mold 9 and a lower mold 10 as shown in FIG.

  The upper die 9 attached to the lower surface of the upper slide of the double-acting press is provided with a ring-shaped outer punch 9a fixed to the lower surface of the upper slide via a die holder (not shown), and slidable in the upper punch 9a. The inner punch 9b is elastically supported by a die cushion (not shown) provided in the upper slide.

  The outer punch 9a has a cylindrical portion 9c whose tip is substantially equal to the plate thickness t of the flange 12a of the workpiece 12. The cylindrical portion 9c can press the end surface of the flange 12a from above.

  A small-diameter portion 9d for forming the step 12d of the workpiece 12 is formed at the tip of the inner punch 9b, and the boundary between the small-diameter portion 9d and the large-diameter portion 9e is formed substantially perpendicular to the axis of the inner punch 9b. The corner forming portion 9f is made.

  The lower die 10 provided on the lower slide side of the press is provided with an annular fixed die 10a fixed to the upper surface of the lower slide via a die holder (not shown), and slidable in the fixed die 10a. The movable pad 10b is elastically supported by a die cushion (not shown) installed in the lower slide.

  The lower inner peripheral surface 10c of the fixed die 10a has a smaller diameter than the outer diameter of the inner punch 9b of the upper die 9, and the movable die 10b is fitted in the lower inner peripheral surface 10c so as to be slidable up and down. Before the work 12 is formed, the upper surface of the fixed die 10a and the upper surface of the movable pad 10b are substantially the same height.

  The upper inner peripheral surface 10d of the fixed die 10a is appropriately selected depending on the shape of the clutch drum 1. For example, a value obtained by doubling the plate thickness t of the flange 12a of the workpiece 12 to the inner diameter of the lower inner peripheral surface 10c is added. A cavity 13 is formed between the outer peripheral surface of the movable pad 10b, which has an inner diameter, and the upper inner peripheral surface 10d of the fixed die 10a.

  On the bottom side of the cavity 13, a tapered surface 10 e having a diameter gradually increasing from the lower inner peripheral surface 10 c side to the upper inner peripheral surface 10 d side is formed on the fixed die 10 side. The side corner portion 12c is squeezed toward the corner forming portion 9f side of the inner punch 9b, and the connecting portion between the upper end of the tapered surface 10e and the upper inner peripheral surface 10d and the lower end of the tapered surface 10e and the lower inner peripheral surface 10c. A small R is formed in the connecting portion.

  The inclination angle θ of the tapered surface 10e is set to about 30 ° with respect to the axis of the fixed die 10a. However, the inclination angle θ is not limited to this angle, and the shape of the step 12d of the workpiece 12 is not limited. An appropriate predetermined shape is selected.

  Next, a method for forming the clutch drum 1 will be described with reference to FIGS.

  First, a plate material made of a steel plate is preformed to obtain a cup-shaped workpiece 12 as shown in FIG.

  Next, when the bottom 12b of the work 12 is placed on the upper surface of the movable pad 10b of the lower mold 10 as shown in FIG. 3 and the work 12 is positioned, the upper and lower slides of the press 12 are moved in the approaching direction to move the upper slide. The inner punch 9b of the upper die 9 attached to the lower surface of the workpiece is inserted into the workpiece 12 from above as shown in FIG. 4, and the bottom 12b of the workpiece 12 is sandwiched between the lower surface of the inner punch 9b and the movable die 10b. Hold.

  When the upper and lower slides are further moved closer in this state, the movable die 10b elastically supported by the die cushion installed in the lower slide starts to descend, so that the work 12 is placed inside the upper portion of the fixed die 10a as shown in FIG. It is press-fitted from above into a cavity 3 formed between the peripheral surface 10d and the outer peripheral surface of the movable pad 10b.

  Thereafter, when the vertical slide further approaches, the corner 12c on the bottom 12b side of the work 12 reaches the tapered surface 10e of the fixed die 10a, and the corner 12c is squeezed toward the corner forming portion 9f of the inner punch 9b by the tapered surface 10e. At the same time, the cylindrical portion 9c of the outer punch 9a provided on the outer peripheral portion of the inner punch 9b comes into contact with the end surface of the flange 12a of the workpiece 12, and the end surface of the flange 12a is added to the tapered surface 10c side as shown by the arrow in FIG. Press.

  As a result, the material of the corner portion 12c of the work 12 flows toward the corner molding portion 9f side of the inner punch 9b, so that the material is filled in the corner molding portion 9f as shown in FIG.

  Further, since the cushioning force of the die cushion that elastically supports the inner punch 9b is set in advance to be several times larger than the cushioning force of the die cushion that elastically supports the movable pad 10b, the inner punch 9b always has a predetermined applied force. While maintaining the pressure, it balances with the cushioning force of the movable pad 10b at an optimum value, so that even if the material that flows to the corner molding portion 9f becomes excessive, Since it does not cause a defect and the sagging of the material is suppressed, a press-formed product with good quality in which the corner portion of the stepped portion 12d is formed substantially at right angles can be obtained.

  When the forming of the workpiece 12 is completed as described above, the upper and lower slides are moved in the separating direction, and the workpiece 12 is knocked out from the mold 8 by the knockout means (not shown), so that the corner portion of the stepped portion 12d is almost A workpiece 12 as shown in FIG. 7 formed at right angles can be obtained. In this state, the outer peripheral side of the step portion 12d of the workpiece 12 is molded at substantially the same angle θ as the tapered surface 10e of the fixed die 10a. Therefore, the entire shape is formed and molded in the restorative process.

  In the overall shape forming, a fixed die 10f having a substantially right angle corresponding to the tapered surface 10e is used to press the step 12d of the workpiece 12 in the vertical direction as shown in FIG. The shape is formed, and the inner peripheral corner portion of the step portion 12d is finished at a substantially right angle in the previous process. When the molded product is used in the clutch drum 1 of the clutch shown in FIG. 1, a predetermined effective stroke is obtained in the piston 3, so that the axial length of the clutch drum 1 is obtained. Therefore, the clutch drum 1 and the clutch itself do not become large, so that the cost of automobile parts can be reduced.

  In addition, defects due to rolling up and overlapping of materials and defects such as local sink marks caused by a shortage of material flowing into the corner molding portion can be prevented. Since a smooth molding surface can be obtained when the material sufficiently flows into the corner molding portion 9f, machining after molding becomes unnecessary, thereby reducing the machining cost.

  When only the corner portion on the inner peripheral side of the step 12d of the workpiece 12 is formed at a substantially right angle, the entire shape forming may be omitted.

  Moreover, although the said embodiment demonstrated the case where the clutch drum 1 was press-molded, while being applicable to the press-formed goods in general which have a stepped flange, the press used for shaping | molding is not limited to a double-acting press. Of course, a single-acting press may be used.

  Since the present invention can fill the material in the corner forming portion of the inner punch while suppressing material sagging, a step portion having a sharp corner portion on the inner peripheral surface of the work can be formed and obtained. For example, by applying the molded product to a clutch drum of a clutch that is an automobile part, a predetermined effective piston stroke can be secured without increasing the axial length of the clutch drum. Since it does not increase in size itself, the cost of parts can be reduced, and there are defects such as defects due to rolling up and overlapping of materials, and local sink marks caused by insufficient material flowing into the corner molding part. As a result, it is possible to obtain a good press-formed product with no defects and smoothness by sufficiently flowing the material into the corner molding part. Since the molding surface is obtained, machining after molding becomes unnecessary, whereby for an effect that attained also reduce processing costs, which is ideal for molding method and apparatus of a press molded article having a stepped flange.

It is sectional drawing of the clutch using the clutch drum shape | molded with the shaping | molding apparatus of the press-molded product which becomes embodiment of this invention. It is sectional drawing of the shaping | molding apparatus of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is process drawing which shows the molding method of the press molded product which becomes embodiment of this invention. It is explanatory drawing of the press-molded product obtained by the conventional shaping | molding method.

Explanation of symbols

9 Upper die 9a Outer punch 9b Inner punch 9f Corner molding portion 10 Lower die 10a Fixed die 10b Movable pad 12 Work piece 12a Flange 12b Bottom portion 12c Corner portion 12d Step portion 13 Cavity

Claims (5)

A workpiece preformed in the shape of a cup in the previous process, an upper die consisting of an inner punch elastically supported by a die cushion and a ring-shaped outer punch provided on the outer periphery of the inner punch, and a movable elastically supported by a die cushion A press-molded product forming method in which press forming is performed between a pad and a lower die made of a fixed die provided on an outer periphery of the movable pad, the bottom of the work being sandwiched between the inner punch and the movable pad. With the inner punch, the bottom of the workpiece is press-fitted into the cavity of the fixed die by the inner punch, and when the corner of the workpiece reaches the tapered surface formed on the fixed die, the corner is Simultaneously pressing the flange end surface of the workpiece with the outer punch while squeezing the corner of the inner punch And the material is fluidized to form part, forming method of the press-molded product, which comprises forming a stepped portion having a sharp corner portion on the inner peripheral surface of the workpiece. The angle of the taper surface is set to a predetermined angle corresponding to the shape of the stepped portion of the workpiece with respect to the axis of the fixed die, and a fixed die having an R formed at the end of the taper surface is used. The method for forming a press-formed product according to claim 1, wherein the work is formed. The method for molding a press-formed product according to claim 1 or 2, wherein a cushioning force of a die cushion that elastically supports the inner punch is several times larger than a cushioning force of a die cushion that elastically supports the movable die. A workpiece preformed in the shape of a cup in the previous process, an upper die consisting of an inner punch elastically supported by a die cushion and a ring-shaped outer punch provided on the outer periphery of the inner punch, and a movable elastically supported by a die cushion A press-molded product forming method in which press forming is performed between a pad and a lower die made of a fixed die provided on an outer periphery of the movable pad, the bottom of the work being sandwiched between the inner punch and the movable pad. With the inner punch, the bottom of the workpiece is press-fitted into the cavity of the fixed die by the inner punch, and when the corner of the workpiece reaches the tapered surface formed on the fixed die, the corner is Simultaneously pressing the flange end surface of the workpiece with the outer punch while squeezing the corner of the inner punch A material characterized in that a material is flowed to form a stepped portion having a sharp corner portion on the inner peripheral surface of the workpiece, and then the entire shape of the workpiece is formed by a restructuring process. Molding method for molded products. A workpiece preformed in the shape of a cup in the previous process, an upper die consisting of an inner punch elastically supported by a die cushion and a ring-shaped outer punch provided on the outer periphery of the inner punch, and a movable elastically supported by a die cushion A press-molded product molding apparatus for press-molding between a pad and a lower die comprising a fixed die provided on an outer periphery of the movable pad, wherein the workpiece bottom portion is sandwiched between the inner punch and the movable pad. With the inner punch, the bottom of the workpiece is press-fitted into the cavity of the fixed die by the inner punch, and when the corner of the workpiece reaches the tapered surface formed on the fixed die, the corner is Simultaneously pressing the flange end surface of the workpiece with the outer punch while squeezing the corner of the inner punch And the material is fluidized to form part, the press molded article of a molding apparatus characterized by having a molding portion for molding the stepped portion having a sharp corner portion on the inner peripheral surface of the workpiece.

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