CN217045588U

CN217045588U - Tool clamp of thrust bearing in air pressure disc type brake

Info

Publication number: CN217045588U
Application number: CN202221045621.8U
Authority: CN
Inventors: 郑小平; 安明科
Original assignee: Zhejiang Tianyuan Electromechanical Co ltd
Current assignee: Zhejiang Tianyuan Electromechanical Co ltd
Priority date: 2022-04-29
Filing date: 2022-04-29
Publication date: 2022-07-26
Anticipated expiration: 2032-04-29

Abstract

The utility model provides a frock clamp of thrust bearing among air pressure disk brake belongs to anchor clamps technical field. It has solved the problem that production efficiency is low. The novel thrust bearing device comprises a mounting disc which can be fixed on a machine tool spindle, two support plates which are symmetrically arranged on two sides of a center line of the mounting disc, a gap which can be used for placing two thrust seats in a mode that circular arc surfaces are oppositely arranged is formed between the two support plates, one opposite side of each of the two support plates is provided with a cylindrical head which can be inserted into a circular hole in the middle of each thrust seat, the two cylindrical heads are arranged on the same center line, one opposite side of each of the two support plates is also provided with a positioning part which can be used for clamping the thrust seats when the thrust seats are sleeved on the cylindrical heads, so that the length directions of the thrust seats are consistent with the direction of the center line of the mounting disc, and the two support plates are also connected with compression arms which can move along the direction of the center line of the cylindrical heads. The device has the advantages of high production efficiency, high machining precision, high detection efficiency, high detection precision and the like.

Description

Tool clamp of thrust seat in air pressure disc brake

Technical Field

The utility model belongs to the technical field of anchor clamps, a frock clamp of thrust bearing in the air pressure disc brake is related to.

Background

As shown in fig. 1, a thrust bearing 1 (also referred to as a reference seat) is an important component of an air disc brake, and is a substantially rectangular block, a circular hole 1b having two ends penetrating therethrough is formed in the middle of the thrust bearing, and two arc surfaces 1a distributed on two sides of the circular hole are formed on the thrust bearing 1 at one side of the circular hole 1b where one port is located. In the air disc brake, the thrust seat is used to match with the pressure arm, and the matching relationship can refer to the integral caliper air disc brake with the base seat arc guide structure disclosed in patent application No. 201420579413.5.

Because the thrust seat has the characteristic of the arc surface, the machining requirement on the arc surface is very high when the thrust seat is used, so that the finish machining cannot be carried out on a common numerical control machine tool, therefore, in the actual production, the thrust seat is formed by casting firstly, and then the arc surface on the thrust seat is subjected to finish machining by adopting a machining center, but the machining center can only machine one product every time, so the production efficiency is lower; and after the machining is finished, the circular arc surface after the finish machining can be only transferred to a three-coordinate measuring instrument to be detected, so that the time and the labor are wasted, and the detection cost is increased.

SUMMERY OF THE UTILITY MODEL

The utility model aims at the above-mentioned problem that prior art exists, provide a frock clamp of thrust bearing, solved the problem that production efficiency is low.

The purpose of the utility model can be realized by the following technical proposal:

the tool clamp of the thrust seat in the air pressure disc brake comprises a mounting disc capable of being fixed on a machine tool main shaft and is characterized in that two symmetrical support plates arranged on two sides of a center line of the mounting disc are fixed on the mounting disc, a gap capable of allowing two thrust seats to be placed in a mode that arc surfaces are arranged oppositely is arranged between the two support plates, a cylindrical head capable of being inserted into a middle circular hole of the thrust seat and two cylindrical heads are arranged on the same center line of the two support plates, a positioning portion capable of allowing the thrust seat to be clamped into the mounting disc in a mode that the length direction of the positioning portion is consistent with the center line direction of the mounting disc when the thrust seat is sleeved on the cylindrical head is further arranged on one opposite side of the two support plates, and a compression arm capable of moving along the center line direction of the cylindrical head is further connected to the two support plates.

This frock clamp mainly used thrust bearing on the cambered surface finish machining use, place two backup pads respectively with the relative mode that sets up of cambered surface with two thrust bearings, at this in-process, ensure that the cylinder head on two backup pads inserts respectively in two thrust bearing's the round hole and make thrust bearing block to the location portion in the backup pad of place, just so can make the length direction of two thrust bearings unanimous with the central line direction of mounting disc, at last the rethread compresses tightly two thrust bearings with the arm respectively that compresses tightly on two backup pads. After the tool clamp is used for clamping, the arc surfaces on the two thrust seats are just in a right-facing arrangement relationship, so that the two arc surfaces can be simultaneously subjected to finish machining by directly matching with the feeding of a numerical control cutter under the condition that a machine tool spindle drives a mounting disc to rotate at a high speed, on one hand, the machining efficiency is well improved due to the fact that the two thrust seats are machined at one time, and the machining precision in the batch machining process is well guaranteed; on the other hand, the inner diameter dial indicator can be directly used for detection after machining is finished (two ends of the movable measuring head of the inner diameter dial indicator just can abut against two arc surfaces respectively), so that the detection efficiency and the detection precision are improved.

In the above-mentioned frock clamp of thrust bearing in air pressure disc brake, the compressing arms quantity in the same backup pad is two, and two compressing arms in the same backup pad are the same with the distance between the mounting disc and these two compressing arms symmetrical arrangement in the cylinder head both sides in the same backup pad.

Two on the same backup pad compress tightly the arm and the mounting disc between the distance the same and these two compress tightly arm symmetrical arrangement in the cylinder head both sides in same backup pad, mean that two compress tightly the arm and just in time be the both sides that are located thrust bearing middle part round hole when thrust bearing installs in the backup pad, so these two compress tightly the arm just in time just can press the intermediate position department of arc surface place one side on thrust bearing, thereby form more firmly location to thrust bearing in the backup pad, guarantee the machining precision when utilizing this frock clamp to improve production efficiency.

In the tooling fixture for the thrust bearing in the air pressure disc brake, one side of the same supporting plate, which is opposite to the two pressing arms, is respectively provided with the abdicating inclined planes, and the distance between the two abdicating inclined planes is gradually reduced along the direction close to the supporting plate.

The abdicating inclined planes of the two pressing arms connected to the same supporting plate are gradually reduced along the direction close to the supporting plate, so that the abdicating inclined planes between the two corresponding pressing arms on the two supporting plates are gradually increased along the direction close to the central line of the mounting disc, and the abdicating can be carried out on the cutter so as to ensure the processing reliability.

In the above-mentioned frock clamp of thrust bearing in air pressure disc brake, the holddown arm including the body of rod that passes the backup pad of place and link firmly perpendicularly in the body of rod and be close to the one of another backup pad and serve the compact heap, the inclined plane of stepping down sets up on the compact heap, one side that the compact heap is close to the backup pad has the holding surface that parallels with the backup pad.

The rod body is arranged for realizing the connection and the movement of the pressing arm on the supporting plate, and the pressing block is used for realizing the pressing of the pressing arm on the thrust block. The setting of the pressing surface enables two pressing arms and the thrust bearing to be in plane contact, so that the thrust bearing is more uniform in stress, and the machining precision is guaranteed while the production efficiency is improved.

In the tooling fixture for the thrust bearing in the air disc brake, a linkage mechanism is arranged between one ends, far away from the other support plate, of the two rod bodies on the same support plate, and when one of the rod bodies moves towards the direction that the corresponding pressing block is close to the support plate, the other rod body can be driven to move towards the same direction through the linkage mechanism.

The linkage mechanism is arranged, so that the two pressing arms on the same supporting seat can realize linkage clamping of the thrust bearing, the thrust bearing is more uniform in stress and more reliable in positioning, and the machining precision is further guaranteed.

In the tooling fixture for the thrust seat in the air disc brake, a hinged seat is arranged on the other side of the supporting plate between the two rod bodies, the linkage mechanism comprises a swinging rod, the middle part of the swinging rod is hinged in the hinged seat through a pin shaft, a gap is formed between the position, through which the pin shaft passes, of the swinging rod and the swinging rod, a hinged structure is arranged between one of the rod bodies and one end of the swinging rod, the other rod body passes through the other end of the swinging rod and is in threaded connection with an operation nut, and a gap is formed between the part, through which the swinging rod passes, of the rod body and the swinging rod.

The operating nut is rotated towards the direction close to the swinging rod so as to drive the pressing arm in threaded connection with the operating nut to move by utilizing threads to enable the pressing block on the operating nut to be close to the supporting plate, meanwhile, the abutting of the operating nut and the swinging rod also forces the swinging rod to swing around the hinge point to drive the other pressing arm to enable the pressing block on the operating nut to be close to the supporting plate, and thus the two pressing blocks can press the thrust seat on the corresponding supporting plate. Because this frock clamp need cooperate the lathe main shaft to carry out high-speed rotatory, consequently this link gear is as pure mechanical type to compare to the cylinder more be applicable. Meanwhile, a gap is formed between the position, through which the pin shaft penetrates, of the swinging rod and the swinging rod, and a gap is formed between the rod body, through which the swinging rod penetrates, of the swinging rod and the swinging oscillating rod, so that the swinging rod can float to a certain extent in the direction close to the rod body hinged with the swinging rod in the swinging process, the swinging rod is prevented from being clamped and blocked when being driven to slide along with the rod body hinged with the swinging rod, and the reliability is higher.

In the above-mentioned frock clamp of thrust bearing in air disc brake, hinged structure including the breach groove of locating the swing rod tip, threaded connection correspond the connector of body of rod tip and set up the articulated shaft in the breach inslot, the connector is located the breach inslot and the articulated shaft passes the connector.

Through the arrangement, the rod body can form a hinged relation with the swing rod, so that the swing rod can drive the rod body to slide when swinging, and the linkage of the two pressing arms is realized.

And the connector articulates in the breach groove and body of rod and connector threaded connection, means that the staff can pull this body of rod, and the tip of another body of rod has operating nut in spite of threaded connection has operating nut equally but the staff also can pull this body of rod when operating nut does not lean on with the swinging arms, that is to say that the staff can pull two hold-down arms and make two compact heap outwards separate with the thrust bearing, and the thrust bearing just can directly take out like this. The mode of taking out the workpiece means that the action stroke of the two pressing arms from releasing the workpiece to clamping the workpiece along the center line of the cylindrical head is shorter, so that the phenomenon that the swing rod drives the rod body hinged with the swing rod to slide and block when swinging does not occur.

In the above-mentioned frock clamp of thrust bearing in air pressure disc brake, as another technical scheme, the link gear include the connecting rod that connects between the body of rod of two pressure arms and pass the connecting rod middle part and with the backup pad along the operation screw of axial fixity, operation screw and connecting rod threaded connection.

Because the operation screw and the supporting plate are fixed along the axial direction and the operation screw is in threaded connection with the connecting rod, when the operation screw is rotated, the connecting rod can be driven to move through the threads, and thus the two pressing arms can be driven to synchronously press the thrust seat. Because this frock clamp need cooperate the lathe main shaft to carry out high-speed rotatory, consequently this link gear as pure mechanical type compares that the cylinder is more suitable for.

In the above tooling fixture for a thrust bearing in an air disc brake, the positioning portion includes two backer blocks fixed on the support plate, a gap is provided between the two backer blocks for the thrust bearing to be clamped in when the length direction of the thrust bearing is consistent with the direction of the central line of the mounting disc, and a tightening screw which can approach to the other backer block when rotating is in threaded connection with one of the backer blocks.

Through the arrangement, the length direction of the thrust seat can be consistent with the direction of the central line of the mounting disc after the thrust seat is clamped between the two mountain leaning blocks, and then the jacking screw is rotated to enable the end part of the jacking screw to jack tightly at the side part of the thrust seat, so that the positioning effect of the thrust seat can be further improved, and the machining precision is guaranteed.

Compared with the prior art, this frock clamp of thrust bearing among air pressure disk brake has following advantage:

1. the two thrust seats can be clamped simultaneously, and the arc surfaces of the two thrust seats can be just opposite to each other after clamping is finished, so that the two arc surfaces can be simultaneously and finely machined by directly matching with the feeding of a numerical control cutter under the condition that a main shaft of a machine tool drives a mounting disc to rotate at a high speed, the machining efficiency is well improved, and the machining precision in the batch machining process is ensured;

2. after the machining is finished, the inner diameter dial indicator can be directly used for detection (two ends of the movable measuring head of the inner diameter dial indicator just can be respectively abutted against the two arc surfaces), so that the detection efficiency and the detection precision are improved;

3. set up two on the same backup pad and these two hold-down arms and adopt the link gear action, the thrust bearing atress is more even and the location is more reliable, has guaranteed the machining precision when improving production efficiency to clamping efficiency is higher.

Drawings

Figure 1 is a schematic view of a thrust block.

Fig. 2 is a schematic perspective view of a first embodiment of the tooling fixture for a thrust pad in the air disc brake.

Fig. 3 is a sectional view of a first embodiment of the tool holder for a thrust bearing in the air disc brake according to the present invention.

Fig. 4 is a schematic front view of two thrust blocks mounted on a tooling fixture in the first embodiment.

Fig. 5 is a schematic perspective view illustrating two thrust blocks mounted on a tooling fixture according to the first embodiment.

In the figure, 1, a thrust block; 1a, an arc surface; 1b, round holes; 2. installing a disc; 2a, mounting holes; 3. a support plate; 4. a cylindrical head; 5. a pressing arm; 5a, a rod body; 5b, a compression block; 5b1, abdication ramp; 5b2, compression face; 6. a hinged seat; 7. a swing lever; 8. operating the nut; 9. a positioning part; 9a, a backer block; 10. jacking the screw; 11. a pin shaft; 12. a connector; 13. and a hinged shaft.

Detailed Description

The following are specific embodiments of the present invention and the accompanying drawings are used to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

Example one

As shown in fig. 2 and 3, the fixture for the thrust bearing in the air disc brake comprises a mounting disc 2 capable of being fixed on a main shaft of a machine tool, wherein the mounting disc 2 is circular and is provided with a plurality of mounting holes 2a with two ends penetrating through at the position close to the edge. It sets up in its central line both sides and just to the backup pad 3 that sets up to be fixed with two symmetries on mounting disc 2, it can supply two thrust bearing 1 to put into with the relative mode that sets up of arc surface 1a to have between two backup pads 3 the clearance, two backup pads 3 one side relative all have can insert the cylinder head 4 and two cylinder head 4 with the central line setting in the middle part round hole 1b of thrust bearing 1, one side relative still all is equipped with when thrust bearing 1 cover on the cylinder head 4 can supply thrust bearing 1 card to go into the location portion 9 that makes its length direction and mounting disc 2 central line direction unanimous. The positioning part 9 comprises two support blocks 9a fixed on the support plate 3, a gap is arranged between the two support blocks 9a, the thrust seat 1 can be clamped in when the length direction of the gap is consistent with the central line direction of the mounting disc 2, and a jacking screw 10 which can approach to the other support block 9a when rotating is connected to one support block 9a through threads. The two supporting plates 3 are connected with pressing arms 5 which can move along the central line direction of the cylindrical head 4.

Specifically, as shown in fig. 2 and 3, the number of the pressing arms 5 on the same supporting plate 3 is two, the distance between the two pressing arms 5 on the same supporting plate 3 and the mounting plate 2 is the same, and the two pressing arms 5 are symmetrically arranged on two sides of the cylindrical head 4 on the same supporting plate 3. The opposite sides of the two pressing arms 5 on the same supporting plate 3 are respectively provided with an abdicating inclined surface 5b1, and the distance between the two abdicating inclined surfaces 5b1 is gradually reduced along the direction close to the supporting plate 3. Since the receding inclined surfaces 5b1 of the two pressing arms 5 on the same supporting plate 3 decrease gradually in the direction approaching the supporting plate 3, the receding inclined surfaces 5b1 between the two corresponding pressing arms 5 on the two supporting plates 3 increase gradually in the direction approaching the central line of the mounting plate 2.

As shown in fig. 2 and fig. 3, the pressing arm 5 includes a rod 5a passing through the supporting plate 3 and a pressing block 5b perpendicularly fixed to one end of the rod 5a close to the other supporting plate 3, and the receding slope 5b1 is disposed on the pressing block 5 b. The side of the pressing block 5b close to the supporting plate 3 has a pressing surface 5b2 parallel to the supporting plate 3. In this embodiment, a linkage mechanism is disposed between the ends of the rods 5a between the two pressing arms 5 of the same supporting plate 3, which are far away from the other supporting plate 3, and when one of the rods 5a moves toward the supporting plate 3, which makes the corresponding pressing block 5b approach, the other rod 5a can be driven to move in the same direction by the linkage mechanism. In this embodiment, a hinge seat 6 is disposed on the other side of the supporting plate 3 between the two rod bodies 5a, the linkage mechanism includes a swing rod 7 whose middle portion is hinged to the hinge seat 6 through a pin 11, and a gap is formed between a position of the swing rod 7 through which the pin 11 passes and the swing rod 7, a hinge structure is disposed between one of the rod bodies 5a and one end of the swing rod 7, the other rod body 5a passes through the other end of the swing rod 7 and is in threaded connection with an operation nut 8, and a gap is formed between a portion of the rod body 5a passing through the swing rod 7 and the swing rod 7. The hinge structure comprises a notch groove arranged at the end part of the swinging rod 7, a connector 12 in threaded connection with the end part of the corresponding rod body 5a and a hinge shaft 13 arranged in the notch groove, wherein the connector 12 is positioned in the notch groove, and the hinge shaft 13 penetrates through the connector 12.

The tool clamp is mainly used for finish machining of the arc surface 1a on the thrust seat 1, in an initial state, the operation nut 8 is rotated towards the direction away from the swing rod 7 to enable the corresponding pressing arm 5 to be loosened, and at the moment, the other pressing arm 5 on the same supporting plate 3 can also be loosened (the operations are carried out on the two supporting plates 3). Then, the two thrust bearings 1 are respectively placed on the two support plates 3 in a manner that the arc surfaces 1a are oppositely arranged, in the process, the cylindrical heads 4 on the two support plates 3 are respectively inserted into the circular holes 1b of the two thrust bearings 1, and meanwhile, two sides of the two thrust bearings 1 in the width direction are positioned between the two mountain blocks 9 on the same support plate 3. Then, the operating nut 8 is rotated toward the direction close to the swing rod 7 to drive the pressing arm 5 screwed to the operating nut 8 to move by using a screw so that the pressing block 5b on the pressing arm approaches the supporting plate 3, and meanwhile, the abutment of the operating nut 8 and the swing rod 7 also forces the swing rod 7 to swing around the hinge point to drive the other pressing arm 5 to move so that the pressing block 5b on the pressing arm approaches the supporting plate 3, so that the two pressing blocks 5b press the thrust bearing 1 on the corresponding supporting plate 3 (of course, such operation is performed on both supporting plates 3). Finally, the tightening screw 10 is tightened against the side of the corresponding thrust block 1.

Utilize this frock clamp to press from both sides tight back, as shown in fig. 4 and fig. 5, the arc surface 1a of two thrust bearings 1 just in time sets up relatively, so just can cooperate feeding of cutter to process these two arc surfaces 1a simultaneously under the high-speed rotatory circumstances of mounting disc 2 at the lathe main shaft, on the one hand, production efficiency has been improved well, and the machining precision in the batch machining process has been guaranteed well, on the other hand can directly utilize the internal diameter percentage table to detect (the activity volume head both ends of internal diameter percentage table just in time can support respectively on two arc surfaces 1a) and improved detection efficiency after processing is accomplished.

Example two

The structure and principle of this embodiment are basically the same as those of the first embodiment, and the differences are as follows: in this embodiment, the linkage mechanism includes a connecting rod connected between the rod bodies 5a of the two pressing arms 5 and an operating screw passing through the middle of the connecting rod and axially fixed to the support plate 3, and the operating screw is threadedly connected to the connecting rod. Specifically, during setting, a U-shaped block can be fixed on the support plate 3, the head of the operating screw is positioned in the U-shaped block and is abutted against the support plate 3, and the rod part of the operating screw penetrates through the U-shaped block and is in threaded connection with the connecting rod. Because the operating screw and the supporting plate 3 are fixed along the axial direction and the operating screw is in threaded connection with the connecting rod, when the operating screw is rotated, the connecting rod is driven to move through the threads, and thus the two pressing arms 5 can be driven to synchronously press the thrust bearing 1.

EXAMPLE III

The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: in this embodiment, the hinge structure includes a notch groove formed at an end of the swing lever 7, a through hole formed at an end of the corresponding lever body 5a, and a pivot shaft fixed in the notch groove and passing through the through hole at the end of the lever body 5 a.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions for the specific embodiments described herein may be made by those skilled in the art without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims

1. A tool clamp of a thrust seat in an air pressure disc brake comprises a mounting disc (2) which can be fixed on a main shaft of a machine tool, its characterized in that, mounting disc (2) on be fixed with two symmetries and set up in backup pad (3) of its central line both sides, the clearance that can supply two thrust bearing (1) to put into with the mode that arc surface (1a) set up relatively has between two backup pad (3), one side that two backup pad (3) are relative all has cylinder head (4) and two cylinder head (4) with the central line setting in middle part round hole (1b) that can insert thrust bearing (1), one side that two backup pad (3) are relative still all is equipped with and can supplies thrust bearing (1) card to go into when thrust bearing (1) cover on cylinder head (4) and make its length direction and mounting disc (2) central line direction unanimous location portion (9), still all be connected with on two backup pad (3) and to press arm (5) that can follow cylinder head (4) central line direction removal.

2. The tool clamp for the thrust bearing in the air disc brake as recited in claim 1, wherein the number of the pressing arms (5) on the same support plate (3) is two, the distance between the two pressing arms (5) on the same support plate (3) and the mounting disc (2) is the same, and the two pressing arms (5) are symmetrically arranged on two sides of the cylindrical head (4) on the same support plate (3).

3. A tool clamp for a thrust bearing in an air disc brake according to claim 2, wherein the opposite sides of the two pressing arms (5) on the same support plate (3) are respectively provided with an abdicating inclined surface (5b1), and the distance between the two abdicating inclined surfaces (5b1) is gradually reduced along the direction approaching the support plate (3).

4. A tool holder for a thrust bearing in an air disc brake according to claim 3, wherein the pressing arm (5) comprises a rod body (5a) penetrating through the support plate (3) and a pressing block (5b) vertically fixed to one end of the rod body (5a) close to the other support plate (3), the abdicating inclined surface (5b1) is arranged on the pressing block (5b), and one side of the pressing block (5b) close to the support plate (3) is provided with a pressing surface (5b2) parallel to the support plate (3).

5. A tool clamp for a thrust bearing in an air disc brake according to claim 4, characterized in that a linkage mechanism is arranged between the ends of the two rod bodies (5a) on the same support plate (3) far away from the other support plate (3), and when one of the rod bodies (5a) moves towards the direction of the support plate (3) where the corresponding pressing block (5b) is close to, the other rod body (5a) can be driven to move towards the same direction through the linkage mechanism.

6. A tool clamp for a thrust bearing in an air disc brake according to claim 5, wherein a hinge seat (6) is arranged between the two rod bodies (5a) on the other side of the support plate (3), the linkage mechanism comprises a swing rod (7) of which the middle part is hinged in the hinge seat (6) through a pin shaft (11), a gap is formed between the position of the swing rod (7) through which the pin shaft (11) passes and the swing rod (7), a hinge structure is arranged between one of the rod bodies (5a) and one end of the swing rod (7), the other rod body (5a) passes through the other end of the swing rod (7) and is in threaded connection with an operating nut (8), and a gap is formed between the part of the rod body (5a) passing through the swing rod (7) and the swing rod (7).

7. A tool holder for a thrust bearing in an air disc brake according to claim 6, wherein said hinge structure comprises a notch groove formed at an end of the swing lever (7), a connector (12) screwed to an end of the corresponding lever body (5a), and a hinge shaft (13) formed in the notch groove, the connector (12) is located in the notch groove, and the hinge shaft (13) passes through the connector (12).

8. A tool clamp for a thrust bearing in an air disc brake according to claim 5, wherein the linkage mechanism comprises a connecting rod connected between the rod bodies (5a) of the two pressing arms (5) and an operating screw passing through the middle of the connecting rod and axially fixed with the support plate (3), and the operating screw is in threaded connection with the connecting rod.

9. The tool clamp for the thrust bearing in the air pressure disc brake as recited in claim 1, 2, 3, 4 or 5, characterized in that the positioning part (9) comprises two cam blocks (9a) fixed on the support plate (3), a gap is formed between the two cam blocks (9a) for the thrust bearing (1) to be clamped when the length direction of the two cam blocks is consistent with the center line direction of the mounting disc (2), and a tightening screw (10) which can approach to the other cam block (9a) when rotating is connected to one cam block (9a) in a threaded manner.