JPH09285927A - Workpiece clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform sure clamping for a crank pin when it is machined and accurate machining. SOLUTION: Workpiece receiving bases 36 for mounting and supporting the journals J1 and J2 of a crankshaft are provided. A clamp roller 63 for clamping the journals J1 and J2 mounted and supported by the workpiece receiving bases 36 therebetween is provided. The workpiece receiving bases 36 and the clamp roller 63 are integrally rotated around positions shifted from the axial centers of the journals J1 and J2. The clamp roller 63 clamps the journals J1 and J2 in two spots separated in the circumferential directions thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for clamping a journal of a crankshaft during machining such as grinding of a crankpin on the crankshaft.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 6, a crankshaft C has journals J1 and J2 at both ends thereof, and a plurality of crankpins P having a predetermined phase difference between the journals J1 and J2. There is. The journals J1 and J2 at both ends are arranged on the journal axis L2 so as to face each other with a space. The crankpin P has a plurality of axis lines L located on the circumference centered around the journal axis line L2.
1, L1-1, L1-2, ... Are arranged above.

When the outer peripheral surface of the crank pin P is ground or polished, the required crank pin P is indexed on the machining axis of the machining position. Then, in this state, the crankshaft C is rotated around the machining axis, and the pin P is subjected to predetermined machining. When machining is performed on another crankpin P, the crankshaft C is indexed and rotated again about the journal axis L2, and another required crankpin P is arranged on the machining axis. .

Therefore, when the crank pin P is processed, the journals J1 and J2 at both ends of the crank shaft C are used.
Is clamped, and in this state, the entire crankshaft C is rotated about the machining axis L1 passing through the pin P.

A conventional arrangement for clamping the journals J1, J2 is shown in FIG. This structure has a work pedestal 101 having an arc-shaped work pedestal surface 100, a clamp shoe 102 located above, and a work pedestal 101.
And a clamp arm 103 for clamping the journals J1 and J2. The journals J1 and J2 placed on the work receiving surface 100 are clamped to a higher pressure through the clamp shoe 102 during the machining of the predetermined crankpin P, and the clamping pressure at the clamp shoe 102 during the indexing rotation before and after machining. Is weakened and rotation of the journals J1 and J2 is allowed.

[0006]

However, in the above-mentioned prior art, the clamp shoe 102 has the journal J.
Since the outer peripheral surfaces of 1 and J2 do not uniformly contact and press at one point or one line, the component force from the pressing portion as a starting point diffuses, and the journals J1 and J2 make the work receiving surface 1
It was easy to move within 00. In particular, at the time of machining, as shown in FIG. 8, the journals J1 and J2 are rotated about the machining axis separated from the axis thereof, that is, the axis L1 of the pin P and revolved about the machining axis. The diffusion direction of changes continuously. Therefore, the crankshaft C
There is a possibility that the entire work may move or vibrate with respect to the receiving surface 100, and proper grinding may not be performed.

Further, when the phase of the crank pin P is indexed, in order to prevent the journals J1 and J2 from falling off the work receiving surface 100, the clamp shoe 102 only weakens the clamp pressure as described above. The state of being in contact with J1 and J2 is maintained. Therefore, by sliding the clamp shoe 102 and the journals J1 and J2, the clamp shoe 10 is attached to the surface of the journals J1 and J2.
There was a problem that a friction mark due to 2 was attached.

An object of the present invention is to solve the above-mentioned conventional problems, to reliably clamp the crankshaft when machining the crankpin, and to perform accurate machining, and to extend the life of the clamp portion. It is to provide a clamp device capable of achieving the above.

[0009]

In order to achieve the above object, the present invention employs the following means. According to a first aspect of the present invention, there is provided work supporting means for placing and supporting a cylindrical work, and clamping means for clamping the work supported on the work supporting means between the work supporting means and the work supporting means. In a work clamp device in which the means and the clamp means are integrally rotated about a position deviated from the axis of the clamped part of the work, the clamp means presses the work at two positions spaced apart in the circumferential direction thereof. It has a pair of clamp parts.

According to a second aspect of the present invention, there is provided work supporting means for placing and supporting a cylindrical work, and clamping means for clamping the work supported on the work supporting means between the work supporting means. , The work supporting means and the clamping means are integrally rotated around a position off the axis of the clamped part of the work,
In a work clamp device that allows a work to be rotated about the axis, the clamp means has a pair of clamp portions that press the work at two locations that are spaced apart in the circumferential direction.

According to a third aspect of the present invention, there are provided a pair of main shafts, which are spaced apart and opposed to each other on the first axis and are synchronously rotated by the drive motor, and the pair of main shafts so as to be integrally rotatable. On a second axis parallel to the axis, support means for mounting and supporting journals at both ends of the crankpin, and similarly provided so as to be integrally rotatable with the pair of main shafts, are provided between the journal and the support means. A crankpin clamping device comprising: clamp means for clamping; and indexing means for relative rotation of the crankpin with respect to the main shaft about the second axis to perform phase indexing of the crankpin. The clamp means has a pair of clamp portions that press the work at two positions that are separated from each other in the circumferential direction.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the clamp means is provided with a clamp arm, and a clamp portion is provided at an end of the clamp arm.

According to a fifth aspect of the present invention, in the first to fourth aspects, the pair of clamp bodies comprises a pair of freely rotatable rollers. In claim 6,
According to any one of claims 1 to 5, a clamp pressure lowering means for lowering the clamp pressure in the work clamp state is provided.

According to a seventh aspect of the present invention, in any one of the third to sixth aspects, a lock that locks the clamp body so as not to separate from the outer peripheral surface of the work when the work rotates about the first axis. It has a means.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the work supporting means has an arc surface for placing and supporting the work, and the carbide tip is the same as the arc surface on the arc surface. It is embedded so as to form a surface.

In claim 9, in claim 8,
The arc surface of the work support means is hardened. Therefore, in the first, second, third, and fourth aspects, since the work is clamped at two positions by the clamp portion, the component force generated by the clamp is directed toward the center of the work and is not diffused.

According to the fifth aspect of the present invention, since the roller forming the clamp portion rotates, sliding contact between the clamp portion and the work does not occur. According to the sixth aspect, since the clamp pressure can be reduced, the rotation of the work on the work supporting means can be permitted.

According to the seventh aspect, the clamped state can be locked when the work is rotated around the axis of the crank pin. In the eighth aspect, since the cemented carbide tip and the arcuate surface form the same plane, damage to the cemented carbide tip can be prevented.

In the ninth aspect, it is possible to prevent the arc surface from being damaged.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG.
On the bed 70, slide bases 72 and 73 having a pair of guide rails 71 are fixed. The pair of headstocks 11 and 12 are slidably held by the slide bases 72 and 73, and saddles 74 and 75 are mounted respectively. The spindles 13 and 14 are rotatably supported by the respective headstocks 11 and 12 via bearings 15 so as to be located on the first axis L1.

The clamp devices 16 and 17 are the main shafts 1 described above.
They are attached to the tips of 3 and 14, respectively. As shown in FIG. 2, the clamping devices 16 and 17 clamp the journals J1 and J2 at both ends of the crankshaft C as a work on a second axis L2 parallel to the first axis L1. It should be noted that the distance E1 between the second axis L2 and the first axis L1 is determined by the journal J1 of the crankshaft C1,
It is equal to the distance between the axis of J2 and the center of the pin P. And
In the clamped state of the crankshaft C, one of the crankpins P arranged on the circumference of the main shaft 13,
It is arranged on the same axis as the first axis L1 of 14.

A pair of spindle drive motors 13A and 14A respectively incorporated in the spindle stocks 11 and 12 are composed of both spindles 13 and 14, respectively.
And the crankshaft C held between the clamp devices 16 and 17 is centered on any one of the crankpins P located on the same axis as the first axis L1 of the main shafts 13 and 14. Is rotated. Therefore, the both-end journals J1 and J2 of the crankshaft C revolve around the crankpin P together with the clamp devices 16 and 17. In this revolving state, the grindstone on a grindstone (not shown) is driven to rotate and comes into contact with the crankpin P on the first axis L1, and the outer peripheral surface of the crankpin P is processed for grinding or polishing. It

The phase conversion shaft 18 is rotatably supported by one clamp device 16 on the same axis as the second axis L2. An indexing plate 19 is fixed to the phase conversion shaft 18, and a pin 20 that can be connected to an eccentric hole Ca on one end surface of the crankshaft C is provided on an end surface of the indexing plate 19 so as to project therefrom. A plurality of engaging grooves 19a are formed on the outer circumference of the indexing plate 19.
Are formed at the same predetermined phases as the arrangement phase of the crank pins P.

A cylinder 21 is provided so as to face the peripheral surface of the indexing plate 19, and an engaging body 22 which can be engaged with and disengaged from an engaging groove 19a of the indexing plate 19 is attached to the piston rod of the cylinder 21. ing. Then, by engaging this engaging body 22 with one engaging groove 19a on the indexing plate 19,
Positioning and holding in a state where the indexing plate 19 and the phase conversion shaft 18 are positionally held at the selected indexing angle, and one of the crank pins P is indexed on the first axis L1 passing through the main shafts 13 and 14. To be done.

A spring-biased pusher 23 is provided inside the indexing plate 19 and the phase conversion shaft 18, and the tip of the pusher 23 abuts on one end face of the crankshaft C and is attached to the clamp device 17 on the opposite side. Cylinder 2 provided
The other end surface of the crankshaft C is also pressed by the piston rod in 4, and the crankshaft C is connected to the pin 20 of the index plate 19.

A phase indexing shaft 25 is provided at the center of one main shaft 13.
Is rotatably inserted and supported through a bearing (not shown), and is operatively connected to the phase conversion shaft 18 through a coupling 26. The phase indexing motor 27 is one headstock 1
1, the motor shaft of which is directly connected to the phase indexing shaft 25 via a coupling 28. The phase indexing shaft 25, the phase indexing motor 27, the phase converting shaft 18,
The indexing plate 19, the engaging body 22 and the like constitute indexing means.

The controller 29 controls the both spindle drive motors 13
A, 14A and the phase indexing motor 27 for controlling the operation of the phase indexing motor 27 are executed by the command of the phase indexing mode and the machining mode. That is, in the phase indexing mode, when the spindle drive motors 13A and 14A are stopped or rotating, the phase indexing motor 27 causes the spindle drive motor 13 to move.
The phase indexing shaft 25 is rotated relative to A and 14A.
Are relatively rotated with respect to the main shafts 13 and 14 for phase indexing. Further, in the machining mode, the phase indexing motor 27 and the both spindle drive motors 13A and 14A are synchronously controlled to rotate the phase indexing shaft 25 integrally with the spindles 13 and 14 in the same direction.

As shown in FIGS. 2 and 4, a support base 35 is fixed to the body 31 of the clamp devices 16 and 17, and a work support base 36 constituting a work supporting means is fixed on the support base 35. ing. A work receiving surface 37 having a substantially semi-arcuate shape is formed on the upper surface of the work receiving table 36, and supports the journals J1 and J2 of the crankshaft C. A discharge groove 38 for discharging cutting oil is formed in the center of the work receiving surface 37. The discharge groove 3
A plurality of recesses 39 are formed on both sides of the recess 8.
Inside is a chip 4 that forms the same arcuate surface as the work receiving surface 37.
0 is embedded and fixed. The tip 40 is made of cemented carbide. The work receiving surface 37 is hardened by quenching.

Work support 36 of clamp devices 16 and 17
A cylinder chamber 41 is formed in the lower part of the support base 35, and a piston head 44 biased rightward in the drawing by springs 42 and 43 is accommodated therein. A piston rod 45 is fixed to the piston head 44. When the pressure oil is supplied to the head side chamber 41a of the cylinder chamber 41, the piston head 44 and the piston rod 45 are moved to the left in the drawing.

The body 31 of the clamping device 16, 17
A clamp arm 30 is rotatably supported via a shaft 32 fixed to the clamp arm 30, and a bifurcated support member 34 is rotatably supported by an upper end of the clamp arm 30 via a shaft 33. A shaft 62 is provided at the lower end of the forked portion of the support member 34.
The clamp rollers 63, which form the clamp portion, are rotatably supported via the. The clamp roller 63 is a journal J supported on the work receiving surface 37.
1, 1 and J2 can be clamped from above. The clamp arm 30, the support member 34, the clamp roller 63 and the like constitute a clamp means.

A pin 47 at the lower end of the clamp arm 30
A link 48 is interposed between and the pin 46 at the tip of the piston rod 45. The link 48 is swingably held around the axis of the pin 46, and the crank arm 30 is rotatably connected to one end of the link 48 via a pin 47. When the piston rod 45 moves in and out, the clamp arm 30 is rotated about the shaft 32 via the pin 46, the link 48, and the pin 47.

As shown in FIG. 3, the clamping device 16, 1
A cylinder chamber 50 is formed in the body 31 of No. 7, and a piston head 51 is accommodated inside the cylinder chamber 50. The piston head 51 is biased to the left in the drawing by springs 52 and 53. A piston rod 54 is fixed to the piston head 51. Head side chamber 5 of cylinder chamber 50
0a is supplied with pressure oil, and the piston head 51 and the piston rod 54 are moved to the right in the drawing.

A guide hole 55 is formed in the body 31 on an axis parallel to the axis of the cylinder chamber 50, and a rod 56 is inserted inside the guide hole 55 so as to be movable in the axial direction. A plate 57 is connected between one end of the rod 56 and the piston rod 54.
The piston rod 54 and the piston rod 54 are moved integrally via the plate 57. A positioning hole 58 is formed in the headstock 12, and one end of the rod 56 is fitted into the positioning hole 58 by moving the piston rod 54 to the right in the drawing.

A stopper pin 59 is fixed to the lower portion of the clamp arm 30. The stopper pin 59 faces the piston rod 54. Then, when the piston rod 54 is moved leftward in FIG. 3 by the springs 52 and 53, the piston rod 54 closely faces the stopper pin 59, and the clamp arm 30
The shaft 33 at the upper end of is locked so as not to move in the counterclockwise direction in FIG. 2, that is, in the unclamping direction. The piston rod 54 and the stopper pin 59 constitute a locking means. In the locked state of the crank arm 30, a very small gap h (about 0.1 mm) is formed between the piston rod 54 and the stopper pin 59.

Next, the operation of the apparatus configured as described above will be described. Now, at the time of processing such as grinding of the crank pin P, one of the crank pins P is indexed and arranged on the first axis L1. In this state, the cylinder chamber 41
The pressure oil is supplied to the head side chamber 41a, and the piston rod 45 is projected and moved leftward in the drawing. Therefore, the clamp arm 30 is pivotally arranged around the shaft 32 in the clockwise direction of FIG. 2 via the pin 46, the link 48, and the pin 47, and the clamp roller 63 moves the journals J1 and J2 on the work receiving surface 37. The outer peripheral surface is clamped at two points from above.

Therefore, the crankshaft C is fixed on the work receiving surface 37 at the journals J1 and J2 at both ends thereof. Then, in this state, the clamp devices 16 and 17 are integrally rotated around the first axis L1 by the rotation of the main shafts 13 and 14, and the crank pin P is processed.

At this time, the piston rod 54 of the cylinder chamber 50 is held by the springs 52 and 53 so as to project to the left, and the stopper pin 59 on the clamp arm 30 is held.
Will be closely opposed to. At this time, the gap h between the piston rod 54 and the stopper pin 59 is very small.
Therefore, even if a force in the clamp releasing direction is applied to the clamp arm 30 for some reason such as a decrease in hydraulic pressure, the rotation of the clamp arm 30 is blocked, so that the clamp roller 63 is used. Journal J
The holding states of 1 and J2 can be maintained. Therefore,
There is no risk that the journals J1 and J2 will come off the work receiving surface 37.

In order to finish the machining of a predetermined pin P and perform the machining of another pin P, the crankshaft C is indexed by the relative rotation between the transfer indexing shaft 25 and the main shafts 13 and 14. At this time, the pressure oil in the head-side chamber 41a of the cylinder chamber 41 is released, and the piston rod 45 is acted on by the springs 42 and 43 to the right in FIG. Therefore, the clamp arm 30 has a shaft 32
A turning force is applied in the counterclockwise direction around the center, but since the stopper pin 59 and the piston rod 54 engage with each other, the clamp arm 30 is not rotated, and the clamp pressure by the clamp roller 63 is released. It is only done.

Therefore, for some reason, the cylinder chamber 4
Even if the pressure in 1 is released, the clamp arm 30 is not rotated because the gap h between the stopper pin 59 and the piston rod 54 is as small as about 0.1 mm. Therefore, the clamp roller 63 is
Journals J1 and J2 that never leave J1 or J2
There is no risk that the will come off the work cradle 36. Further, when the pressure in the cylinder chamber 41 is weakened during indexing, the clamp roller 63 does not separate from the journals J1, J2, but the pressing force on the journals J1, J2 is weakened. Therefore, it is possible to prevent the journals J1 and J2 from being damaged by the indexing rotation of the journals J1 and J2.

Therefore, the rotation of the journals J1 and J2 on the work receiving surface 37 is permitted, the crankshaft C is indexed and rotated, and another crankpin P is arranged on the first axis L1. At this time, journals J1, J
The clamp roller 63 is rotated following the rotation of 2.

When the crankshaft C is exchanged for machining another crankshaft C after the predetermined machining of the crankshaft C is completed, the cylinder chamber 50
The pressure oil is supplied to the head-side chamber 50a, and the piston rod 54 is moved to the right (fixed side) in FIG. Therefore, the rod 56 moves to the right (fixed side) through the plate 57.
To the positioning hole 58 on the headstock 12.
And the clamp devices 16 and 17 are non-rotatably fixed. Further, the piston rod 54 is retreated from the area facing the stopper pin 59 by its leftward movement (the side that is separated from the fixed side), and the clamp arm 30 is rotatable in either the clockwise or counterclockwise direction. Become.

In this state, the pressure oil in the cylinder chamber 41 is discharged, and the piston rod 45 is moved to the right by the spring force of the springs 42 and 43, so that the pin 46 and the link 48 are moved.
The clamp arm 30 is rotated counterclockwise via the pin 47 and the clamp roller 63 is largely moved upward. Therefore, the upper portions of the journals J1 and J2 are opened, and the crankshaft C can be replaced.

Therefore, this embodiment has the following effects. (1) Since the journals J1 and J2 of the crankshaft C are pushed toward the center at the two points on the upper side thereof, the journal J
The component forces acting on J1 and J2 are directed to the central portions of the journals J1 and J2. Therefore, journals J1 and J2
Is reliably supported without moving with respect to the work receiving surface 37, and processing such as grinding of the crank pin P can be performed with high accuracy.

(2) When the crankshaft C is rotated about the first axis L1 during the machining of the crankpin P, the stopper pin 59 of the clamp arm 30 is engaged with the piston rod 54 to clamp the clamp arm. Rotation of the clamp roller 6 in the clamp releasing direction is blocked, and the clamp roller 6
3 can be prevented from separating from the journals J1 and J2 to prevent the crankshaft C from coming off the pedestal work 36.

(3) When the crankshaft C is indexed and rotated, the clamp arm 30 merely lowers the pressure between the stopper pin 59 and the piston rod 54, and basically there is no gap. For this reason, only the indexing rotation of the crankshaft C is allowed, and the risk of the crankshaft C coming off from the work pedestal 37 can be prevented as described above.

(4) Since the clamp roller 63 presses the journals J1 and J2, the journal J
Journals J1 and J2 for indexing rotation of J1 and J2
There is no sliding contact with the outer periphery of the journal J
It is possible to prevent scratches and abrasions of 1 and J2 or abrasion of the clamp roller 63 itself.

(5) Since the work receiving surface 37 is hardened by quenching, wear of the work receiving surface 37 can be suppressed. (6) Since the tip 40 forms the same surface as the work receiving surface 37, it is possible to prevent the corners of the tip 40 from being worn and the journals J1 and J2 from being damaged. That is, as shown in FIG. 7, in the conventional device, since the tip 40 was set so as to project from the work receiving surface 100, the corner portion of the tip 40 was damaged due to the indexing rotation of the journals J1 and J2. easy. On the other hand, the corner portion of the tip 40 is rotated by the index J to rotate the journal J.
1 and J2 are formed in an arc shape so as not to be scratched, but the arc disappears due to the wear of the corners,
The edges appear and scratch the journals J1 and J2.

(7) Since the journals J1 and J2 are received by the work receiving surface 37 and the tip 40 which have the same circular arc surface, the wear of the receiving surface of the tip 40 is suppressed and the life of the work receiving table 36 is extended. be able to. That is, as mentioned above,
Conventionally, since the tip 40 is projected from the work receiving surface 100, the contact area between the tip and the work is narrowed, the tip is easily worn, and the life thereof is short.

The present invention may be embodied as follows. (1) With the clamp arm 30 placed in the release position shown by the chain double-dashed line in FIG. 2, retract the support member 34 so that the support member 34 does not interfere with the manipulator or the like for workpiece replacement. Providing means for According to this structure, the work can be exchanged smoothly.

(2) A pair of fixed shoes is provided instead of the clamp roller 63. Even with this configuration,
It is possible to enjoy the effect of preventing the diffusion of component force.

[0051]

As described above, the present invention exhibits the following effects. According to claims 1, 2, 3, and 4, since the work is clamped at two positions by the clamp portion, the component force generated by the clamp is directed toward the center of the work and is not diffused. Therefore, the work can be stably supported, and high-precision machining can be performed. Furthermore, since there is no play due to the gap between the journal and the work receiving surface during phase indexing, indexing accuracy is improved.

According to the fifth aspect of the present invention, since the clamp roller rotates, there is no sliding contact between the clamp roller and the work. Therefore, it is possible to prevent the work from being damaged by the foreign matter that has entered between the roller and the work, and also to prevent the roller itself from being worn, so that the durability of the clamp device can be improved.

According to the sixth aspect of the present invention, since the clamping pressure can be lowered, the work on the work supporting means can be easily rotated about its axis, and the work can be indexed smoothly.

According to the seventh aspect, the clamped state can be locked, and the safety during processing can be improved. In the eighth aspect, since the cemented carbide tip and the arcuate surface form the same plane, it is possible to prevent edge formation due to breakage of the cemented carbide tip and prevent damage to the work.

According to the ninth aspect, the arcuate surface can be prevented from being damaged and the durability can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing a crankpin processing machine having a clamp device.

FIG. 2 is a side sectional view showing a clamp device.

FIG. 3 is a cross-sectional view of an essential part showing a clamp device.

FIG. 4 is a perspective view showing a work pedestal.

FIG. 5 is a side view showing the entire clamp device.

FIG. 6 is a front view showing a crankshaft.

FIG. 7 is a side view showing a conventional clamp device.

FIG. 8 is an explanatory diagram showing the revolution state of the journal.

[Explanation of symbols]

16 ... Clamping device, 17 ... Clamping device, 18 ... Phase conversion shaft, 19 ... Indexing plate, 25 ... Phase indexing shaft, 27 ...
Phase indexing motor, 30 ... Clamp arm, 34 ... Support member, 36 ... Work cradle, 37 ... Work receiving surface, 40 ...
Tip, 54 ... Piston rod, 56 ... Rod, 59 ...
Stopper pin, 63 ... Clamp roller, C ... Crank shaft, P ... Crank pin, J1, J2 ... Journal.

Claims (9)

[Claims] 1. A work supporting means for mounting and supporting a cylindrical work, and clamp means for clamping a work supported on the work supporting means between the work supporting means and the work supporting means. In a work clamping device in which the clamping means and the clamping means are integrally rotated about a position deviated from the axis of the clamped part of the workpiece, the clamping means separates the workpiece in the circumferential direction.
A work clamp device having a pair of clamp portions that are pressed at a location. 2. A work supporting means for mounting and supporting a cylindrical work, and a clamping means for clamping a work supported on the work supporting means between the work supporting means and the work supporting means. A workpiece clamping device that allows the workpiece and the clamping means to be integrally rotated about a position off the axis of the clamped portion of the workpiece, and allows the workpiece to be rotated about the axis. The clamping means separates the work in the circumferential direction 2
A work clamp device having a pair of clamp portions that are pressed at a location. 3. A pair of main shafts, which are arranged so as to face each other on a first axis with a space therebetween, and are synchronously rotated by a drive motor, and are provided so as to be integrally rotatable with the pair of main shafts, and are parallel to the first axis. Support means for mounting and supporting the journals at both ends of the crankpin on the second axis, and clamp means provided to be rotatable integrally with the pair of main shafts and clamp the journal between the journals and the support means. And a crank pin clamping device for rotating the crank pin relative to the main shaft about the second axis to index the phase of the crank pin. 2 apart from the circumference
A work clamp device having a pair of clamp portions that are pressed at a location. 4. The clamp means includes a clamp arm and a support member rotatably supported at an end of the clamp arm, and the support member has a clamp portion.
The work clamp device according to any one of 1. 5. The work clamp device according to claim 1, wherein the pair of clamp portions is composed of a pair of freely rotatable rollers. 6. A clamp pressure lowering means for lowering the clamp pressure in a work clamp state is provided.
The work clamp device according to any one of to 5. 7. The method according to claim 3, further comprising locking means for locking the clamp portion so as not to separate from the outer peripheral surface of the work when the work is rotated about the first axis. Work clamp device. 8. The work supporting means has an arcuate surface for placing and supporting the work, and a cemented carbide chip is embedded in the arcuate surface so as to form the same surface as the arcuate surface. Work clamp device according to any one of the above. 9. The work clamp device according to claim 8, wherein the arc surface of the work supporting means is hardened.