JP6240244B2 - Cold forging die and cold forging method - Google Patents

Description

  The present invention relates to a cold forging die and a cold forging method.

  As a conventional cold forging die and method, a male die having a pressing punch pin and a female die having a work accommodating portion are provided, and a workpiece accommodated in the female die is pressed with a male punch pin, A mold and a method for forming a hole in a workpiece are known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2000-42474

As shown in FIGS. 3A to 3C, a conventional cold forging die and method includes a sleeve 92 in which a workpiece W is accommodated in an accommodation hole 93 of a female die 95 and a punch pin 91 is inserted. The workpiece W is pressed while approaching the female die 95 and the punch pin 91 is projected from the tip reference surface 92a of the sleeve 92, and back pressure is applied to the workpiece W by the back pressure pin 96, and the punch W 91 is projected to the workpiece W by a predetermined amount. A long hole J corresponding to the dimension S was formed, and a bottomed cylindrical forged product V having the long hole J as shown in FIG. 4 was formed.
That is, it is necessary to project the punch pin 91 from the tip reference surface 92a of the sleeve 92 by the same length as the depth dimension of the hole to be formed. However, if the predetermined protruding dimension S of the punch pin 91 is too long, the punch pin 91 may be buckled and damaged. For example, when the workpiece W is S45C (carbon steel), the predetermined projecting dimension S of the punch pin 91 is limited to 5 times or less the diameter dimension d91 of the punch pin 91. Further, a hole deeper (longer) than the long hole J corresponding to the predetermined projecting dimension S of the punch pin 91 could not be provided.

  Accordingly, the present invention provides a cold forging die and a cold forging method capable of forming a hole with ease and surely and stably, and capable of forming a deep hole having a depth dimension longer than the protruding dimension of the punch pin. The purpose is to provide.

In order to achieve the above object, a cold forging die of the present invention comprises a male die comprising a punch pin and a sleeve having a diameter larger than that of the punch pin and having a hole into which the punch pin is inserted. and, further, a first hole to accommodate a workpiece, and a second hole of smaller diameter than said first hole, and a reduced-diameter throttle portion for connecting the starting end and the second hole of the first hole, the A work mold having a female mold with a back pressure pin disposed in the second hole, and pressing the work in the first hole with the tip reference surface of the sleeve; Further, the punch pin is advanced from the reference end surface of the sleeve to a predetermined protruding dimension , the tip of the punch pin is protruded to a position deeper than the end of the first hole, and the back part of the workpiece is opened to the second hole. And push the back pressure pin into the back of the workpiece with the back pressure pin. By applying a, and configured to form a long hole and a bottom wall portion which corresponds to the predetermined protruding dimension to the work, further work in the front end reference face while maintaining the predetermined protruding dimension of the punch pin and pressed by the back pressure pin in a state where the workpiece has granted back pressure to press write Mutotomoni workpiece to the second hole is retracted with a large reverse speed than the pressing forward speed of the sleeve, of the punch pin A columnar space is formed in the workpiece on the tip side, and a deep hole having a depth longer than the predetermined protruding dimension is formed.

Further, the cold forging method of the present invention provides a male die provided with a punch pin and a sleeve having a diameter larger than the punch pin and having a hole into which the punch pin is inserted, and accommodates a workpiece. first hole and, the second hole of smaller diameter than the first hole, the first hole of the termination and the work molding hole having a reduced diameter throttle portion, the connecting the starting end of the second hole for provided with a, a female having a back pressure pin that will be disposed in the second hole provided to accommodate the workpiece in the first hole, presses the workpiece leading end reference surface of the sleeve, and the The punch pin is advanced from the reference end surface of the sleeve to a predetermined protruding dimension , the tip of the punch pin is protruded to a position deeper than the end of the first hole, and the back part of the work is brought close to the opening of the second hole. Applying back pressure with the back pressure pin while pushing down to form the bottom wall Rutotomoni, forming a long hole corresponding to the predetermined protruding dimension to the work, subsequently, while maintaining the predetermined protruding dimension of the punch pin, to press the workpiece at the front end reference face, the workpiece second While pushing into the hole, the back pressure pin is retracted while applying a back pressure to the work at a retreat speed larger than the pressing advance speed of the sleeve, and a columnar space is formed in the work on the tip side of the punch pin. In this method, a deep hole having a depth longer than the predetermined protruding dimension is formed.

  According to the present invention, deep holes can be reliably formed without performing machining such as gun drilling, and productivity such as manufacturing cost and yield can be improved. There is no need to project the punch pin to the limit, damage due to buckling can be prevented, and a forged product can be produced easily and stably. Deep holes can be formed using one set of molds (male mold and female mold) without transferring the workpiece to another mold. For example, a deep hole can be formed only by pressing once with a press machine, and mass production can be easily and stably performed.

It is front sectional drawing which shows one Embodiment of this invention, (a) is front sectional drawing of a shaping preparation state, (b) is front sectional drawing of the state immediately after completion | finish of a punch pin protrusion, (c) FIG. 6 is a front sectional view in a state where pressing by a sleeve is in progress; FIG. It is a front sectional view showing an example of a forged product. It is sectional front view for demonstrating a prior art, (a) is front sectional drawing of a molding preparation state, (b) is front sectional drawing of the state before the press start by a punch pin, (c) is a punch pin. It is front sectional drawing of a state immediately after completion | finish of press by. It is front sectional drawing which shows an example of the forged product shape | molded by the prior art.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
The cold forging die according to the present invention includes a punch pin 1 and a sleeve 2 having a diameter larger than that of the punch pin 1 and having a hole 20 into which the punch pin 1 is inserted, as shown in FIG. A male mold 3 is provided.
Further, the first hole 51 for receiving the workpiece W, the second hole 52 having a smaller diameter than the first hole 51 and communicating with the inner part of the first hole 51, and the second hole 52 are disposed. A female mold 5 having a back pressure pin 55 for applying a back pressure to the workpiece W pressed by the male mold 3 is provided.
For example, the male mold 3 is disposed on the press moving board side (upper board side) of a press machine or the like, and the female mold 5 is disposed on the fixed board side (lower board side) of the press machine.
Further, the punch pin 1, the sleeve 2 (the hole 20 thereof), the first hole 51, the second hole 52, and the back pressure pin 55 are disposed coaxially (disposed on the reference axis L). ).

Further, as shown in FIGS. 1B to 1D, the punch pin 1 slides in the axial center L direction into the hole 20 of the sleeve 2 so that it can project from the reference end surface 21 of the sleeve 2 by a predetermined projecting dimension S. Insert freely.
In the illustrated example, the punch pin 1 has a straight round bar shape in which a range of a predetermined projecting dimension S projecting from the tip reference surface 21 of the sleeve 2 (molding tip portion) has a circular cross section.
Further, the distal end portion 2 a of the sleeve 2 is set to a size that can be inserted while being in sliding contact with the inner surface of the first hole 51.

  Then, as shown in FIG. 1B, when the tip 11 of the punch pin 1 protrudes from the tip reference surface 21 of the sleeve 2 by a predetermined protruding dimension S, as shown in FIGS. 1C and 1D, The sleeve 2 and the punch pin 1 are configured to advance integrally (relatively not moving in the direction of the axis L) while the predetermined protruding dimension S of the punch pin 1 is maintained.

As a structure in which the punch pin 1 and the sleeve 2 advance integrally, for example, in a molding preparation state (a state in which the punch pin 1 and the sleeve 2 are separated from the first hole 51) in FIG. The base end portion (upper end portion) of the punch pin 1 is protruded from the base end portion (upper portion) of the sleeve 2, and the base end portion of the punch pin 1 is fixed to a male base member (not shown).
Further, in the molding preparation state, the sleeve 2 is attached to the pressing base member so as to be slidable in the axis L direction (vertical direction), and the lower surface (pressing surface) of the pressing base member and the base end surface (upper surface) of the sleeve 2 ) Are arranged with a predetermined separation dimension that is the same as the predetermined protrusion dimension S.
Then, as the male base member advances (lowers) by the press machine, the punch pin 1 advances, and when the tip 11 of the punch pin 1 protrudes from the tip reference surface 21 of the sleeve 2 by the predetermined protruding dimension S, The pressing surface of the base member is in contact with the base end surface of the sleeve 2 so that the male base member advances the punch pin 1 and the sleeve 2 integrally (simultaneously).
Alternatively, when the punch pin 1 protrudes from the sleeve 2 by a predetermined projecting dimension S, the tip diameter-reduced taper surface provided on the outer surface of the punch pin 1 contacts the tip diameter-reduced taper surface provided in the hole 20 of the sleeve 2, You may comprise so that the punch pin 1 and the sleeve 2 may advance integrally.

  In the female die 5, a work forming hole is constituted by the first hole 51, the second hole 52, and the reduced diameter restricting portion 60 formed between the first hole 51 and the second hole 52. The female die 5 includes a female die member (female base member) 50 having a workpiece forming hole and a back pressure pin 55.

  The first hole 51 and the second hole 52 have a straight inner surface having a vertical cross section, and a terminal 61 of the vertical inner surface of the first hole 51 and a start end 62 of the straight inner surface of the second hole 52 are provided. The diameter-reduced throttle part (reduced-diameter taper part) 60 is formed by connecting the surfaces with an inclined longitudinal section. Further, the (depth) of the second hole 52 is formed longer than the first hole 51 (depth). The cross-sectional shape (size) of the second hole 52 is formed to be equivalent to the cross-sectional shape (size) of the forged product W ′ (see FIG. 2) to be formed. The cross-sectional shape of the first hole 51 is formed in a similar shape having a smaller size than the cross-sectional shape of the second hole 52.

  The back pressure pin 55 can be retracted while applying a predetermined back pressure to the workpiece W by back pressure generating and retracting means such as an actuator (for example, a hydraulic cylinder or an air cylinder) or an elastic biasing member (for example, a coil spring). It is disposed in the second hole 52.

Next, the operation of the cold forging die and the cold forging method according to the present invention will be described by taking as an example the case of forming a bottomed cylindrical forged product W ′ as shown in FIG.
As described above, the male mold 3 and the female mold 5 are provided and installed in a pressing force generating means such as a press machine, so that the male mold 3 and the female mold 5 can be relatively close to each other in the reference axis L direction. To do. Then, the workpiece W is accommodated in the first hole 51 of the female die 5 (molding preparation step).

The punch pin 1 and the sleeve 2 are brought close to the workpiece W by the pressing force generating means.
As shown in FIG. 1B, the tip 2a of the sleeve 2 is inserted into the first hole 51, and the workpiece W in the first hole 51 is pressed by the tip reference surface 21 of the sleeve 2 (work W and tip And the punch pin 1 protrudes from the tip reference surface 21 of the sleeve 2 to a predetermined projecting dimension S, and the workpiece W is extended in the direction of the axis L as a whole. In the reduced diameter drawn portion 60, a long hole J corresponding to the predetermined projecting dimension S is formed (cold forging) in the work W (first forming step).

  In addition, in the first molding step (punch pressing step), the tip 11 of the punch pin 1 is projected to a position (back) deeper than the end 61 of the first hole 51, and the tip of the punch pin 1 moves the inner part of the workpiece W first. While pushing into the vicinity of the opening (near the top) of the two holes 52, back pressure is applied by the back pressure pin 55 to form the bottom wall e. Further, the tip reference surface 21 of the sleeve 2 prevents the workpiece W from jumping out of the first hole 51.

By projecting the tip 11 of the punch pin 1 deeper than the end 61 of the first hole 51, the bottom wall portion e can be formed in advance so as to have a strong strength. In the second molding step (sleeve pressing step) described later, It is possible to prevent the shape of the bottom wall e and the inner diameter in the vicinity of the bottom wall e from collapsing, and a predetermined deep hole inner diameter dw (see FIG. 2) is obtained.
In other words, it can be said that the first forming step is an intermediate cylindrical body forming step in which the workpiece W is formed into an intermediate cylindrical body E having a long hole J and a bottom wall portion e corresponding to the predetermined protruding dimension S. Also, the end 61 of the first hole 51 can be said to be the stop start end 61 of the reduced diameter stop portion 60.

Then, as shown in FIG. 1 (b), the tip 11 of the punch pin 1 protrudes (presses and advances) by a predetermined protruding dimension S from the tip reference surface 21 of the sleeve 2 to form a long hole J. As shown in FIG. 1 (c), the punch pin 1 and the sleeve 2 are advanced integrally (simultaneously) while keeping the predetermined protrusion dimension S of the punch pin 1 (in a state where the predetermined protrusion dimension S is maintained). The workpiece W (intermediate cylindrical body E) is pressed by the tip reference surface 21, and the workpiece W is pushed into the second hole 52 along the punch pin 1, and the cylinder is formed between the outer surface of the punch pin 1 and the inner surface of the second hole 52. The cylindrical wall portion f is stretched and formed in an extruded shape toward the tip 11 side (downward) of the punch pin 1 while forming the shape wall portion f, and the back pressure pin has a retreat speed larger than the pressing advance speed of the sleeve 2. Retract 55 while applying back pressure to work W (bottom wall e) , At the tip 11 of the punch pin 1 (in the second hole 52) to form a columnar space K in the work W.
Then, as shown in FIGS. 1C to 1D, a deep hole Q having a depth dimension H longer than the predetermined projecting dimension S is formed (cold forging) while the columnar space K is stretch-molded ( Second molding step).
After forming the deep hole Q, the punch pin 1 and the sleeve 2 are retracted (raised), and the forged product W ′ is taken out from the female die 5 (takeout step).

  Here, for ease of explanation, the first molding process and the second molding process are called separately. However, the first and second molding processes are performed continuously, and the punch pins 1 are female. The die member 50 for mold (the first hole 51 and the second hole 52) and the lower plate of the press machine always move forward (lower). That is, the punch pin 1 is a process that can be molded only once (without stopping or retracting), and the manufacturing process is, for example, one process that is performed only once with a press.

Here, conventionally, as shown in FIGS. 3C and 4, the workpiece W (forged product V) is only formed with a long hole J having a predetermined protruding dimension S of the punch pin 1, and is long. The length of the hole J (predetermined protrusion dimension S) is 5 times the diameter dimension d91 (hole diameter dimension) of the conventional punch pin 91 when the material of the workpiece W is S45C (carbon steel).
However, according to the present invention, as shown in FIGS. 1D and 2, it is possible to form a deep hole Q that is longer than the predetermined protruding dimension S of the punch pin 1. Moreover, the depth dimension H of the deep hole Q can be formed to be 7 times or more the diameter dimension d1 of the punch pin 1 when the material of the workpiece W is S45C. (In the case of S45C, it is possible to mold a hole that is 1.4 times deeper than the conventional one.)
In other words, the predetermined projecting dimension S of the punch pin 1 can be shortened (in the case of S45C, it can be reduced to about 72% or less as compared with the prior art), and damage due to buckling can be prevented and durability can be improved.

  In the present invention, the design can be changed, and the male mold 3 and the female mold 5 may be provided so that the reference axis L is horizontal or inclined. It is only necessary that the male mold 3 and the female mold 5 are relatively close to and away from each other in the direction of the reference axis L. The male mold 3 may be provided on the fixed platen side and the female die 5 may be provided on the pressing and moving plate side. The cross-sectional shape of the hole 20 of the punch pin 1 and the sleeve 2 is not limited to a circle, and may be an ellipse, a rectangle, a polygon, a gear shape, or the like. Moreover, the cross-sectional shape of the 1st hole 51 and the 2nd hole 52 is free, such as elliptical shape, a rectangular shape, a polygonal shape, and a gear shape. When the cross-sectional shape of the punch pin 1 is non-circular, the diameter d1 of the punch pin 1 assumes a circular shape having the same area as the area of the non-circular cross-sectional shape, and refers to the assumed circular diameter size. When the direction of the arrow Na along the reference axis L is referred to as the axial center direction Na, the forward movement of the punch pin 1 and the sleeve 2 and the backward movement of the back pressure pin 55 are advanced in the axial direction Na. .

  As described above, the cold forging die of the present invention includes the male die 3 including the punch pin 1 and the sleeve 2 having the hole 20 having a diameter larger than that of the punch pin 1 and into which the punch pin 1 is inserted. And a female die 5 having a first hole 51 that accommodates the workpiece W, and a second hole 52 that communicates with the inner part of the first hole 51 and has a smaller diameter than the first hole 51, The workpiece W in the first hole 51 is pressed by the tip reference surface 21 of the sleeve 2, and the punch pin 1 is projected from the tip reference surface 21 of the sleeve 2 to the predetermined projection dimension S, so that the workpiece W corresponds to the predetermined projection dimension S. A long hole J is formed, and the workpiece W is pressed by the tip reference surface 21 in a state in which the predetermined projecting dimension S of the punch pin 1 is maintained, the workpiece W is pushed into the second hole 52, and on the tip 11 side of the punch pin 1 A columnar space K is formed in the workpiece W, and the depth dimension H is longer than the predetermined projecting dimension S. Since the deep hole Q is formed, the deep hole Q can be reliably formed without performing machining such as gun drilling, and productivity such as manufacturing cost and yield can be improved. It is not necessary to project the punch pin 1 to the limit, damage due to buckling can be prevented, and the forged product W ′ can be produced easily and stably. The deep hole Q can be formed using one set of molds (male mold 3 and female mold 5) without transferring the workpiece W to another mold. For example, the deep hole Q can be formed only by performing pressing by a press once, and mass production can be easily and stably performed.

  Further, the cold forging method of the present invention includes a male die 3 including a punch pin 1 and a sleeve 2 having a hole 20 having a diameter larger than that of the punch pin 1 and into which the punch pin 1 is inserted, and A second hole 52 having a diameter smaller than that of the first hole 51 and a work that is disposed in the second hole 52 and pressed by the male die 3 are communicated with the inner part of the first hole 51 for accommodating the work W. A female die 5 having a back pressure pin 55 for applying a back pressure to W is provided, the work W is accommodated in the first hole 51, the work W is pressed by the tip reference surface 21 of the sleeve 2, and The punch pin 1 is protruded from the tip reference surface 21 of the sleeve 2 to a predetermined protrusion dimension S to form a long hole J corresponding to the predetermined protrusion dimension S in the workpiece W, and subsequently the predetermined protrusion dimension S of the punch pin 1 is maintained. While pressing the workpiece W at the tip reference surface 21 and pushing the workpiece W into the second hole 52, The back pressure pin 55 is retracted while applying a back pressure to the work W at a retreating speed larger than the pressing advance speed of the leave 2, and a predetermined space portion K is formed in the work W on the tip 11 side of the punch pin 1. Since the deep hole Q with a depth dimension H longer than the protruding dimension S is formed, the deep hole Q can be reliably formed without performing machining such as gun drilling, and productivity such as manufacturing cost and yield is improved. it can. It is not necessary to project the punch pin 1 to the limit, damage due to buckling can be prevented, and the forged product W ′ can be produced easily and stably. The deep hole Q can be formed using one set of molds (male mold 3 and female mold 5) without transferring the workpiece W to another mold. For example, the deep hole Q can be formed only by performing pressing by a press once, and mass production can be easily and stably performed.

1 punch pin 2 sleeve 3 male mold 5 female mold
11 Tip
20 holes
21 Tip reference surface
51 1st hole
52 2nd hole
55 Back pressure pin
60 diameter reduction part
61 termination
62 Beginning
e Bottom wall H Depth dimension J Long hole K Column space Q Deep hole S Projection dimension W Workpiece

Claims (2)

A male die (3) comprising a punch pin (1) and a sleeve (2) having a diameter (20) larger than that of the punch pin (1) and having a hole (20) into which the punch pin (1) is inserted. And
Furthermore, the workpiece first hole for accommodating the (W) (51), the diameter of the second hole (52) than said first hole (51), and terminating (61) of said first hole (51) above A back pressure disposed in the second hole (52), including a work forming hole portion having a reduced diameter restricting portion (60) connecting the start end (62) of the second hole (52). Comprising a female mold (5) with a pin (55);
The workpiece (W) in the first hole (51) is pressed by the tip reference surface (21) of the sleeve (2), and the punch pin (1) from the tip reference surface (21) of the sleeve (2). Is advanced to a predetermined projecting dimension (S), and the tip (11) of the punch pin (1) is projected to a position deeper than the terminal end (61) of the first hole (51), so that the back part of the workpiece (W) Is pushed into the vicinity of the opening of the second hole (52), and back pressure is applied to the back of the work (W) by the back pressure pin (55), so that the predetermined projecting dimension (S) is applied to the work (W). ) And a bottom wall portion (e) corresponding to the front end reference surface (21) while maintaining the predetermined projecting dimension (S) of the punch pin (1). ) by pressing the workpiece (W) at, with the back pressure of the workpiece (W) to write Mutotomoni workpiece (W) push said second hole (52) The back pressure pin to which state (55) is retracted with a large reverse speed than the pressing forward speed of the sleeve (2), the workpiece (W) to the tip (11) side of the punch pin (1) A cold forging die characterized by forming a columnar space (K) and forming a deep hole (Q) having a depth dimension (H) longer than the predetermined protruding dimension (S). There is provided a male die (3) comprising a punch pin (1) and a sleeve (2) having a hole (20) having a diameter larger than that of the punch pin (1) and having the punch pin (1) inserted therein. and a work (W) first hole (51) for accommodating, the small-diameter second hole (52) than the first hole (51), said first hole end (61 (51) ) And a diameter reducing portion (60) for connecting the start end (62) of the second hole (52), and a work forming hole portion disposed in the second hole (52). back pressure pin (55) female with a (5) provided that,
The workpiece (W) is accommodated in the first hole (51), the workpiece (W) is pressed by the tip reference surface (21) of the sleeve (2), and the tip reference surface (21 of the sleeve (2) is ), The punch pin (1) is advanced to a predetermined protruding dimension (S), and the tip (11) of the punch pin (1) is protruded to a position deeper than the end (61) of the first hole (51), While pressing the back part of the work (W) into the vicinity of the opening of the second hole (52), back pressure is applied by the back pressure pin (55) to form the bottom wall part (e), and the work (W ) to form a long hole corresponding to the predetermined protruding dimension (S) (J), subsequently while maintaining the predetermined protruding dimension of the (S) of the punch pin (1), to the front end reference face (21) The workpiece (W) is pressed to push the sleeve (2) while pushing the workpiece (W) into the second hole (52). The back pressure pin (55) is retracted while applying a back pressure to the work (W) at a retreat speed greater than the advance speed, and a columnar shape is formed in the work (W) on the tip (11) side of the punch pin (1). A cold forging method, wherein a deep hole (Q) having a depth dimension (H) longer than the predetermined projecting dimension (S) is formed while forming a space (K).

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