TWI623362B - Forging apparatus - Google Patents

Abstract

The invention relates to a forging device. This type of forging device includes a hydraulic circuit (70), which is used to release one of the hydraulic pressures before the die set (12) reaches a bottom dead center in a forging process by hydraulic pressure. Supporting one or more selected ones of a plurality of punches (26, 28), wherein an impact member (40) is provided on a die base (14), and a bypass valve (50) is provided on a punch base ( 16) Upper, used to open and close one flow path of the hydraulic circuit. Immediately before the die seat reaches the bottom dead center in the forging process, the valve member (51) of the impact member moves even in a valve opening direction, thereby mechanically opening the flow path of the hydraulic circuit.

Description

Forging device

The present invention relates to a forging device of this type that includes one configured to support one or more selected ones of the punches by hydraulic pressure and release the hydraulic pressure just before the selected punches reach the bottom dead center Plural punches.

In an extrusion process, a blank material or workpiece is placed on a die and a punch is forced toward the die to thereby subject the workpiece to plastic deformation. During this period, a die assembly composed of the die and the punch bears a relatively large load, and therefore, the service life of the die assembly is relatively short. A technique that can extend the service life of the mold assembly is known, as disclosed in, for example, Japanese Patent (JP-B2) No. 2534899, in which a tablet part is released just before the end of an extrusion process Pressure, thereby reducing the maximum load applied to the mold assembly.

More specifically, an extrusion device disclosed in JP 2534899B2 includes an upper die set equipped with one of a plurality of punches having a tubular punch and slidably disposed in an axial hole or outside of the tubular punch One of the tablet parts around the peripheral surface. The tubular punch is fixed to the upper die set. The tabletting member moves vertically relative to the mold set and is supported by a hydraulic cylinder. The hydraulic cylinder is connected to a hydraulic supply pipe and a hydraulic discharge pipe. The hydraulic supply pipe and the hydraulic discharge pipe are connected to a hydraulic power supply through a valve controlled by a solenoid. Before the end of an extrusion process, the solenoid-controlled valve is operated to switch to a position where the hydraulic pressure is released from the hydraulic cylinder. Therefore, the maximum load applied to the mold assembly is reduced And the service time of the mold assembly is extended accordingly.

The extrusion process includes performing a cold forging process at room temperature and performing a hot forging process at a high temperature. During the cold forging process, temperature changes do not cause any problems and a longer processing time is acceptable. On the other hand, during hot forging, the processing time should preferably be as short as possible, since the plastic processing of a workpiece should be completed while the workpiece is still within a predetermined temperature range.

The valve controlled by the solenoid includes an electromagnetic coil (solenoid) and a plunger that moves when the solenoid is energized. Once a valve opening signal is received, the solenoid is energized to thereby generate electromagnetic force to move the plunger in a desired direction. Due to the accumulation of the time period required for energization, magnetization and movement, solenoid controlled valves usually involve a time delay or lag of about 0.1 second. A special solenoid-controlled valve designed to meet high-speed operation can shorten the valve opening time. However, this particular solenoid-controlled valve system is very expensive and one of the reduced time effects obtained from the same valve is small compared to the increase in cost.

It should be understood that a technique using a solenoid-controlled valve such as disclosed in JP 2534899B2 is suitable for cold forging processes where the tabletting speed is relatively low. However, in the hot forging process performed at a high-pressure sheet speed, it is required that the valve used immediately operates within about 0.01 seconds. Therefore, if a solenoid-controlled valve with a response time of about 0.1 second is used in this hot forging process, the valve opening operation cannot be performed in time, which results in the hydraulic pressure not being released at an appropriate timing.

Therefore, it is an object of the present invention to provide a forging device that can release hydraulic pressure with enhanced reliability even when used in an ultra-high-speed forging process.

According to the present invention, there is provided a forging device including a die set having a plurality of punches and a plurality of punches for supporting the plurality of punches by hydraulic pressure in a manner to release the hydraulic pressure just before the die set reaches a bottom dead center in a forging process One of the hydraulic circuit of any one of the heads, characterized in that the forging device includes a side of one of the flow paths for opening and closing the hydraulic circuit Through valve; the die set includes a die seat supporting a die, and a punch seat equipped with a plurality of punches that can move relatively toward and away from the die seat; an impact member is relatively immovably disposed on the die One of the seat and the punch seat, and the bypass valve is relatively immovably arranged on the other of the die seat and the punch seat; and the die set is about to reach the lower part of the forging process Before the dead point, the impact member moves a valve element of the bypass valve in a valve opening direction to thereby mechanically open the flow path of the hydraulic circuit.

In this configuration, since the hydraulic pressure acting on a specific punch is released immediately before the die set reaches the bottom dead center in the forging process, the material of a workpiece being forged is allowed to flow from the adjacent area into the face of the specific In one of the punches. In view of this divided flow technology, the maximum load acting on a mold assembly at the end of the forging process can be reduced, and one of the mold assemblies can obtain an extended service life. In addition, immediately before the die set reaches the bottom dead center, when the valve element is moved or replaced, the bypass valve is mechanically switched. Therefore, the bypass valve can be operated without a time delay (originally occurred in the case of a valve controlled by a solenoid), and the hydraulic pressure can be released at an appropriate timing, even when an extremely high The tabletting speed is applied during one of the forging processes (such as a hot forging process).

Preferably, the bypass valve is arranged on the punch seat. Conversely, if the bypass valve is disposed on the die seat, the bypass valve is located away from the punch. This configuration requires a long oil pressure circuit connecting the punch and the bypass valve. This long oil pressure circuit will reduce the response capacity of the bypass valve. In addition, at least part of the hydraulic circuit should be formed by a flexible tube. According to the present invention, since the bypass valve is disposed on the punch seat, the bypass valve can be closer to the punch, which will improve the response capability of the bypass valve and avoid the need for a flexible tube.

Preferably, the impact member includes an adjustable height mechanism for adjusting a height of the impact member. In this configuration, when the setting or configuration of the mold set has been changed, the impact member can be easily placed at an expected height required by the mold set.

Preferably, the punch supported by hydraulic pressure is a punch designed to plasticize the least accurate part of the entire area of a workpiece. Since only one of the workpieces is limited The machining part is used to reduce the load on the entire area of the workpiece, so the remaining part of the workpiece can be forged with enhanced accuracy.

10‧‧‧Forging device

12‧‧‧Mould Group

14‧‧‧Mold Block

16‧‧‧Punch Block

18‧‧‧Guide column

19‧‧‧Guide bush

21‧‧‧low holding block

22‧‧‧Mould

23‧‧‧Mold clamp

25‧‧‧Upper holding block

26‧‧‧First punch

27‧‧‧Punch clamp

28‧‧‧Second punch

29‧‧‧Rectangle punch plate

31‧‧‧recess

32‧‧‧Annular cylinder bore

33‧‧‧Ring piston

34‧‧‧piston rod

35‧‧‧ cover

36‧‧‧Oil chamber

40‧‧‧Impact parts

41‧‧‧End flange

42‧‧‧Base parts

43‧‧‧Column parts

50‧‧‧Bypass valve

51‧‧‧Valve element

51a‧‧‧Large diameter part

51b‧‧‧Conical sealing surface

51c‧‧‧small diameter part

51d‧‧‧ docking parts

52‧‧‧Bottom tubular valve housing

53‧‧‧Valve spring

54‧‧‧Bonnet cover

55‧‧‧ Conical seat

56‧‧‧First O-ring

57‧‧‧ Second O-ring

61‧‧‧Processing liquid

62‧‧‧ Reserve oil tank

63‧‧‧High-pressure air source

64‧‧‧Air pipe

65‧‧‧Air pressure regulating valve

70‧‧‧Hydraulic circuit

71‧‧‧First oil path

72‧‧‧First check valve

73‧‧‧Bypass path

74‧‧‧Release valve

75‧‧‧First port

76‧‧‧Second oil path

77‧‧‧Second port

78‧‧‧The third oil path

79‧‧‧Second check valve

90‧‧‧ Height adjustable mechanism

90B‧‧‧ Height adjustable mechanism

91‧‧‧ male screw

92‧‧‧

93‧‧‧lock nut

94‧‧‧Female screw

95‧‧‧ wrench gripper

97‧‧‧Workpiece

101‧‧‧Drive cone pad

102‧‧‧Drive cone pad

103‧‧‧Plane liner

104‧‧‧Electric cylinder

104a‧‧‧Ball screw shaft

105‧‧‧Guide parts

1 is a front view of a forging device according to a preferred embodiment of the present invention, part of which is shown in cross section.

Figure 2 is a cross-sectional view of a bypass valve incorporated in a forging device; Figure 3 is a front view of an impact member of a forging device, part of which is shown in cross-section.

4A and 4B are cross-sectional illustrations of the operation of the bypass valve; FIGS. 5A to 5C are diagrams showing a series of forging steps according to the present invention; and FIG. 6 is a front view of a modified impact member, part of which Shown in cross section.

Hereinafter, a preferred structural embodiment of the present invention will be described in detail with reference to the accompanying drawings, for illustration only.

As shown in FIG. 1, a forging device 10 includes a die set 12 as a main structural element. The die set 12 includes a die seat 14, a punch seat 16 disposed on the die seat 14, a guide post 18 and a guide bush 19 extending vertically upward from the corner portion of the die seat 14, and the guide bush 19 is guided from the punch The corresponding corners of the headstock 16 extend vertically downward to slidably fit the respective guide posts 18.

Therefore, with the guide bush 19 guided by the guide post 18, the punch seat 16 can be moved up and down accurately relative to the die seat 14. In the illustrated embodiment, the die base 14 is a fixed component, and the punch base 16 is a movable component. Alternatively, the die base 14 may constitute a movable part, in which case the punch base constitutes a fixed part. As a further alternative, both the die base 14 and the punch base 16 may constitute movable parts. In any case, the die set 12 is structurally designed to ensure that the punch seat 16 and the die seat 14 can move relative to each other to experience reciprocating motion with a dead center.

A mold 22 is placed on the mold base 14 via a low holding block 21. A mold clamp 23 secures the mold 22 in place.

A first punch 26 is disposed on the punch base 16 via an upper holding block 25. The first punch 26 is fixed in position by a punch clamp 27. A second punch 28 is arranged to pass vertically through the first punch 26. The second punch 28 has a base (upper end in FIG. 1) fixed to a rectangular punch plate 29. The punch plate 29 is movably received in a recess 31 formed in the upper holding block 25.

The punch base 16 has an annular cylinder hole 32 formed therein, and an annular piston 33 is slidably inserted into the annular cylinder hole 32. Plural (two are shown) piston rods 34 extend vertically downward from the piston 33. The piston rod 34 has a distal end (lower end in FIG. 1) fixed to the punch plate 29. When the piston 33 is completely received by the cylinder bore 32, one of the upper opening ends of the cylinder bore 32 is closed by a cover 35, so that a closed oil chamber 36 is defined between the cover 35 and the piston 33.

An impact member 40 is mounted to the mold base 14 and extends vertically in an upward direction. A bypass valve 50 is mounted to the punch seat 16 to be coaxial with the impact member 40. The bypass valve 50 has a valve element 51 protruding vertically in a downward direction.

A reserve oil tank 62 holds a processing liquid 61 therein and is disposed outside the mold base 14. The reserve oil tank 62 is a closed container and has an upper portion connected to an air pipe 64 extending from a high-pressure air source 63. The air pipe 64 has an air pressure adjustment valve 65 for adjusting a second air pressure at a fixed value. The air pressure regulating valve 65 may be provided at any position on the air pipe 64. The air pipe 64 includes a base end, a distal end, and an intermediate portion between the base end and the distal end of the air pipe 64.

The reserve oil tank 62 and the oil chamber 36 are connected by an oil pressure circuit 70. The oil pressure circuit 70 includes: a first oil path 71 which directly connects the reserve oil tank 62 and the oil chamber 36; a first check valve 72 which is arranged to cross the first oil path 71 and is structurally designed to allow processing The liquid 61 only flows in one direction from the reserve oil tank 62 to the oil chamber 36; a bypass path 73, which is connected to the first oil path 71 in a way that bypasses the first check valve 72; a release valve 74, which By design It is placed across the bypass path 73 and is structured to open when the pressure on the side of the oil chamber 36 exceeds a specified pressure (for example, a maximum allowable pressure is higher than a normal pressure); a second oil path 76 from The first oil path 71 branches at a position between the first check valve 72 and the oil chamber 36 and extends to a first port 75 of the bypass valve 50; a third oil path 78, which is connected One of the second port 77 of the bypass valve 50 and the reserve oil tank 62; and a second check valve 79, which are arranged to cross the third oil path 78 and are structurally designed to allow the processing liquid to flow from the second in only one direction The port 77 flows to the reserve tank 62.

The structural details of the bypass valve 50 and the impact member 40 will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the bypass valve 50 includes: a bottom tubular valve housing 52; a valve element 51 that is movably received in the valve housing 52 and freely moves in one of the axial directions of the valve housing 52; a valve The spring 53, which normally pushes the valve element 51 in a valve closing direction; and a valve cover 54, which closes an open end of the valve housing 52 having the valve spring 53 received in the valve housing 52.

The valve housing 52 has a conical valve seat 55 formed integrally therewith, and a first port 75 and a second port 77 formed in the valve housing 52 in a diametrically opposed relationship across the valve seat 55. The valve element 51 has: a large-diameter portion 51a, which is bent backward in the valve housing 52 via a first O-ring 56; and a tapered sealing surface 51b, which is formed at the large-diameter portion for face-to-face contact with the valve seat 55 At one end of 51a; a small-diameter portion 51c having an outer diameter smaller than the outer diameter of the large-diameter portion 51a and extending from one end of the large-diameter portion 51a to the outside of the valve housing 52; and a mating member 51d, which instead Connected to one distal end of the small diameter portion 51c. A second O-ring 57 provides one of the seals between the small diameter portion 51c and the valve housing 52.

The bypass valve 50 shown in FIG. 2 is in a closed state in which a force of the valve spring 53 acting on the valve element 51 causes the sealing surface 51b of the valve element 51 to face the valve seat 55 in face-to-face contact.

As shown in FIG. 3, the impact member 40 includes a base member 42 having an end flange 41, and a cylindrical member 43 extending vertically upward from the base member 42 of the flange. The impact member 40 may be formed as a junction in which the base member 42 and the cylindrical member 43 are directly connected together Structure.

Preferably, the impact member 40 has a height-adjustable mechanism 90. The height-adjustable mechanism 90 is composed of a rod 92 that extends upward from the base member 42 and has a male screw 91 on one of its outer peripheral surfaces, a lock nut 93 that rotates around a base portion of the rod 92, And a female screw 94 screwed into the cylindrical member 43 along one axis thereof.

When the height adjustment of the striking member 40 is to be performed, the locknut 93 is placed downward in an unlocked position separated from the cylindrical member 43. Next, the cylindrical member 43 rotates in a clockwise direction or a counterclockwise direction. In this case, if it is difficult to rotate the cylindrical member 43, an appropriate tool such as a wrench (not shown) may be used. For this, a wrench gripper 95 is formed on the outer peripheral surface of one of the cylindrical members 43. With the wrench gripper 95 gripped by the jaws of the wrench, the wrench is turned to thereby rotate the cylindrical member 43 forcibly. Therefore, the cylindrical member 43 can be moved up and down by rotation until it reaches a desired height.

When the cylindrical member 43 reaches the desired height, the locknut 93 rotates in one direction to move upward from the unlocked position until the cylindrical member 43 is forcibly lifted by the locknut 93. The forced upward movement of the cylindrical member 43 causes the female screw 94 and the male screw 91 to be more tightly engaged, so that a locking or anti-loosening effect can be obtained. When the locknut 93 is rotated, the cylindrical member 43 may rotate with the locknut 93 slightly. This co-rotation can be prevented by rotating the locknut 93 by keeping the cylindrical member 43 in place by using one of the wrenches applied to the wrench gripper 95 to keep it from rotating.

Hereinafter, a hot forging method obtained by using the forging apparatus 10 constructed as described above will be described in detail. In FIG. 1, one of the hydraulic pressures in the reserve oil tank 62 is transmitted to the oil chamber 36 via the first oil path 71 and the first check valve 72 so that the hydraulic pressure in the reserve oil tank 62 and one of the oil chamber 36 are equal to each other . Under this condition, a blank material or workpiece 97 (FIG. 5A) heated to a forging temperature is set in the mold 22. Next, the punch block 16 is lowered at a high speed. In this case, the first punch 26 is supported by the punch seat 16 and the second punch 28 is supported by the hydraulic pressure.

When the punch base 16 starts to move downward, the cylindrical member 43 of the impact member 40 and the bypass The valve elements 51 of the valve 50 are vertically spaced apart from each other by a distance, as shown in FIG. 4A, and the bypass valve 50 is in the closed state as shown in FIG.

The first punch 26 and the second punch 28 extending downward at high speed significantly contact one surface of the workpiece 97, as shown in FIG. 5A, thus causing the workpiece 97 to begin to undergo plastic deformation between the punches 26, 28 and the die 22 . When the first punch 26 and the second punch 28 move further downward, the plastic deformation of the workpiece 97 advances as shown in FIG. 5B.

The further movement of the first punch 26 and the second punch 28 from one of the positions in FIG. 5B leads to a situation in which the die set 12 reaches a bottom dead center during a forging process. In this case, the valve element 51 of the bypass valve 50 is butted with the cylindrical member 43 of the impact member 40. Thereafter, the valve element 51 stays at this height position, but allows the valve housing 52 to continue its downward movement further, so that a gap is created between the valve seat 55 and the sealing surface 51b, thereby allowing the first port 75 to The second ports 77 communicate with each other, as indicated by the arrows shown in FIG. 4B.

Therefore, when the liquid communication is completed, the hydraulic pressure in the oil chamber 36 is continuously released to the second oil path 76, the bypass valve 50, the third oil path 78, and the second check valve 79 (when in an open state) to Reserve oil tank 62. This will cause the second punch 28 to move upward, while the first punch 26 continues its downward movement, as indicated by the outlined arrow shown in FIG. 5C. In this case, the material of the outer peripheral portion of one of the workpieces 97 is forced to flow toward the central portion of one of the workpieces 97. In view of the material flow, the load applied to the die 22 and the first punch 26 and the second punch 28 can be reduced.

The bypass valve 50 shown in FIG. 1 is not completely free from failure or malfunction. If the bypass valve 50 cannot be opened due to a malfunction, the release valve 74 will be opened to thereby release the hydraulic pressure to the reserve tank 62 via the first oil path 71 and the bypass path 73. Therefore, the piston 33 is prevented from being subjected to excessive hydraulic pressure.

Referring back to FIG. 2, there may be a problem in that the valve element 51 rebounds in an upward direction once it abuts the impact member 40. However, since the valve element 51 is normally pushed downward by the valve spring 53, this problem never actually occurs. Therefore, even when a response time of approximately 0.01 second is a major requirement, the bypass valve 50 can still operate normally.

As previously described with reference to FIGS. 5A to 5C, the central portion of the workpiece 97 is plastically deformed or otherwise processed by the second punch 28. The second punch 28 is supported by the hydraulic pressure discussed above with reference to FIG. 1. As shown in FIG. 5C, the peripheral portion of the workpiece 97 shaped by the first punch 26 has enhanced accuracy in shape and size. On the other hand, the accuracy of the shape and size of the center portion of the workpiece 97 is not as high as the accuracy of the center portion of the workpiece that has been shaped by the second punch 28 that is hydraulically supported. The central part of the workpiece 97 is not required to have a higher degree of accuracy in a forged state, because the central part will be machined after forming an axial hole by drilling in a subsequent processing step And finish. Therefore, a specific punch (which is the central part in the illustrated embodiment) of the lowest accuracy part (the central part in the illustrated embodiment) of the entire area for shaping the workpiece 97 by hydraulic support The second punch 28).

In the configuration shown in FIG. 1, the bypass valve 50 may be provided on the die seat 14, in this case, the impact member 40 is provided on the punch seat 16. The second oil path 76 becomes longer due to this modification, which will extend the response time. In addition, at least part of the second oil path 76 should be formed by a flexible tube.

In contrast, according to the illustrated embodiment, since the bypass valve 50 is provided on the punch seat 16, as shown in FIG. 1, the second oil path 76 is relatively short in length and does not require a flexibility tube.

A modified form of one of the height-adjustable mechanisms 90 will be described with reference to FIG. 6. As shown in FIG. 6, the modified height-adjustable mechanism 90B includes: a driving tapered gasket 101 that is integrally formed with or connected to one of the lower ends of the cylindrical member 43; one Drive cone pad 102, which is placed directly under drive cone pad 101; a flat pad 103, which is mounted to mold base 14 and slidably supports drive cone pad 102 thereon; an electric cylinder 104, which is fixedly mounted on the mold base 14 to drive or move the tapered pad 102 in a horizontal direction; and a guide member 105, which is provided on the mold base 14 and when the cylindrical member 43 moves in a vertical direction The cylindrical member 43 is slidably guided.

The electric cylinder 104 has a structure known per se and usually consists of a ball screw shaft 104a, a ball nut (not shown) screwed to the ball screw shaft 104a, and a servo motor for rotating the ball nut (picture (Not shown). Due to this configuration, when the ball nut is rotated by the servo motor, the ball screw shaft 104a performs a linear reciprocating motion with enhanced accuracy. The ball screw shaft 104a of the electric cylinder 104 is connected to the rear end of the driving tapered gasket 102 at an outer end of the electric cylinder 104.

When the ball screw shaft 104a of the electric cylinder 104 pushes and drives the tapered gasket 102 forward (in the direction of one of the right in FIG. 6), the drive tapered gasket 101 drives the tapered gasket 102 to have a flat cone shape The interaction between the surface and one of the flat tapered surfaces of the drive tapered pad 101 moves vertically upward. Therefore, the cylindrical member 43 moves upward. Alternatively, when the cone screw 102 is retracted by the ball screw shaft 104a of the electric cylinder 104 (in one of the directions to the left in FIG. 6), the cone tape 101 is driven to move vertically downward, thus causing a cylindrical shape The member 43 moves downward together with the driving tapered pad 101.

During this period, when the cylindrical member 43 is stably guided by the guide member 105, it can smoothly move up and down without swinging in a radial direction. Since the electric cylinder 104 is suitable for remote control or automatic operation, the setting of the impact member 40 can be performed more easily in response to a change in the setting or configuration of the mold set 12.

When the cylindrical member 43 receives a downward load applied to one of them, the downward load is pushed by the combination of one of the driving tapered pad 101 and the driving tapered pad 102. Therefore, the electric cylinder 104 is not affected by the effect of the downward load. The ball screw mechanism is considered weak when resisting a force, because it is a precise component. However, since the electric cylinder 104 does not bear a downward load, there is no danger of reducing the service life of the electric cylinder 104. In addition, there is no need to increase the rigidity of the electric cylinder 104, and the size and weight of the electric cylinder 104 can be reduced.

The bypass valve 50 and the height-adjustable mechanism 90 should never be limited to the bypass valve and the height-adjustable mechanism in the illustrated embodiment, but can allow various changes or modifications in the structure. Furthermore, the forging device 10 is specifically suitable for use in hot forging, however, when it is used for warm forging Or it can be operated effectively during cold forging.

The impact member 40 may be provided on one of the die seat 14 and the punch seat 16, and the bypass valve 50 is provided on the other of the die seat 14 and the punch seat 16. As an alternative, the impact member 40 or the bypass valve 50 may be provided on the base instead of the mold base 14. The impact member 40 and the bypass valve 50 can be provided at any position of the forging device, as long as the impact member 40 is relatively immovably installed on one of the die seat 14 and the punch seat 16, and the bypass valve 50 is relatively immovable Installed on the other of the die base 14 and the punch base 16.

Claims (5)

A forging device includes a die set (12) with a plurality of punches (26, 28) and a hydraulic pressure to release the die set (12) just before reaching a bottom dead center in a forging process The hydraulic circuit (70) is supported by any one of a plurality of punches in a hydraulic way. The forging device is characterized in that the forging device (10) includes one for opening and closing the hydraulic circuit (70) A bypass valve (50) in one of the flow paths; the die set (12) includes a die seat (14) supporting a die (22), and is equipped with a plurality of punches (26, 28) and can be relatively toward and away from the A die seat (14) while moving a punch seat (16); an impact member (40) is relatively immovably disposed on one of the die seat (14) and the punch seat (16), and the side The through valve is relatively immovable on the other of the die seat (14) and the punch seat (16); and just before the die set (12) reaches the bottom dead center in the forging process, by The impact member (40) moves a valve element (51) of the bypass valve (50) in a valve opening direction to thereby mechanically open the flow path of the hydraulic circuit (70). The forging device according to claim 1, wherein the bypass valve (50) is provided on the punch seat (16). The forging device according to claim 1 or 2, wherein the impact member (40) includes a height-adjustable mechanism (90) for adjusting the height of one of the impact members (40). The forging device according to claim 1 or 2, wherein the punch supported by the hydraulic pressure is a punch (28) designed to shape a part of the entire area of a workpiece (97) that requires the least accuracy. The forging device of claim 3, wherein the punch supported by the hydraulic pressure is a punch (28) designed to shape a part of the entire area of a workpiece (97) that requires accuracy.