Precise clamp for machine tool

Abstract

The invention discloses a machine tool precision clamp, and relates to the technical field of clamps, the machine tool precision clamp comprises a clamp seat, the clamp seat is of a cylindrical structure, the machine tool precision clamp further comprises a fixing seat installed on the outer side of the clamp seat, a transmission assembly and a clamping assembly, the transmission assembly and the clamping assembly are installed in the clamp seat, and a workpiece is arranged on the outer side of the clamping assembly. The transmission base and the clamping arms are arranged on one side of the clamping base, the transmission base is of a triangular structure, the transmission base can rotate around one angle of the transmission base, the transmission base can drive the clamping arms to move when rotating, the clamping arms extrude a workpiece from inside to outside, and therefore the workpiece is clamped and fixed; the angular position of the transmission seat serving as a fulcrum can be adaptively adjusted to adjust the rotation range of the clamping arm, so that the application range of the device to workpieces of different specifications can be widened.

Description

Technical Field

[0001] The invention relates to the technical field of fixtures, and in particular to a precision fixture for machine tools. Background Art

[0002] In the machining of mechanical parts, we will come into contact with the machining of many sleeve parts. Some sleeve parts have very high requirements for machining precision. When clamping the workpiece with an ordinary three-jaw chuck, it often cannot meet the position accuracy requirements and causes the workpiece to deform greatly, affecting the machining precision and causing the workpiece to be scrapped. Especially when clamping and fixing annular workpieces, it is difficult to achieve accurate positioning.

[0003] For example, a push-type expansion sleeve fine turning fixture with the publication number CN113458440B is used to solve the technical problem that the existing gear inner cavity end face positioning fixture cannot be installed. It includes a flange, a push rod, an expansion sleeve positioning cone, a bonding expansion sleeve, multiple retraction springs, a push sleeve, a threaded adjustment sleeve and multiple threaded pins; the front end of the push rod extends into the central hole of the flange, and the rear end of the push rod extends out of the large end of the flange; the positioning cone small end of the expansion sleeve positioning cone is connected to the small end of the flange by bolts, and multiple external splines are arranged on the large end flange; the bonding expansion sleeve is arranged on the expansion sleeve positioning cone; multiple retraction springs are arranged between the front end face of the bonding expansion sleeve and the rear end face of the large end flange; the push sleeve is arranged on the small end of the flange, and an axially extending waist-shaped hole is arranged on the side wall of the small end of the flange. One end of the threaded pin passing through the waist-shaped hole is connected to the push sleeve, and the other end is connected to the front end of the push rod. The threaded adjustment sleeve is arranged on the push sleeve and is threadedly connected to the push sleeve.

[0004] Although the above technical solution can achieve the clamping and fixing of the annular workpiece by expanding, its clamping range is limited, its adaptability to workpieces of different specifications is poor, and it is difficult to achieve quick installation and quick removal when processing batches of workpieces.

[0005] Therefore, it is necessary to invent a machine tool precision fixture to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a precision fixture for machine tools to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a precision fixture for machine tools, comprising a clamping seat, the clamping seat being arranged as a cylindrical structure, a fixing seat installed on the outside of the clamping seat, a transmission assembly and a clamping assembly installed inside the clamping seat, a workpiece being arranged on the outside of the clamping assembly; The fixing seat is used to assist in positioning the workpiece, the fixing seat is arranged as an annular structure, and the fixing seat is sleeved and installed on the outer side of the clamping seat; The transmission assembly is used to drive the clamping assembly to move, and the transmission assembly includes two transmission seats, both of which are arranged in a triangular structure, and both of which are installed at one end of the inner part of the clamping seat, and a connecting groove is provided at one end of the transmission seat away from the clamping seat, and a driving assembly and an adjusting assembly are installed at one end of the transmission seat close to the inner part of the clamping seat; The clamping assembly is used to clamp the workpiece from the inside out, and the clamping assembly includes a clamping arm, a connecting seat is fixedly provided at the bottom end of the clamping arm, and the connecting seat corresponds to the connecting groove, and a tensioning assembly is installed at the top end of the clamping arm.

[0008] Preferably, the driving assembly is used to push the transmission seat to rotate to achieve the driving of the clamping arm. The driving assembly includes a movable arm and a movable seat. Two movable arms are provided, and the two movable arms are respectively rotatably installed on one end of the two transmission seats close to each other. The movable seat is rotatably installed between the two movable arms, and the movable seat is slidably installed inside the clamping seat.

[0009] Preferably, a transmission rod is fixedly mounted on one end of the movable seat, and the transmission rod is slidably mounted inside the clamp seat, and a locking screw is rotatably mounted on one end of the transmission rod, and the locking screw is threadedly mounted on one end of the clamp seat.

[0010] Preferably, the adjustment component is used to adjust the rotation range of the transmission seat to improve the adaptability of the clamping arm to different workpieces. The adjustment component includes a positioning seat, a limit seat, an arc surface and a positioning rod. The positioning seat is rotatably installed at one end of the transmission seat, and the positioning seat is configured as an arc structure. The limit seat is fixedly installed inside the clamping seat. The arc surface is opened on one side of the limit seat, and the arc surface corresponds to the positioning seat. The positioning rod is rotatably installed in the middle of the positioning seat.

[0011] Preferably, a positioning frame is installed on the outer side of the positioning seat, and the positioning frame is slidably installed inside the clamping seat. A strip groove is opened through the inside of the positioning frame, and the strip groove corresponds to the positioning rod.

[0012] Preferably, an extension plate is fixedly mounted on one end of the positioning frame, a positioning ear is fixedly mounted on one end of the extension plate, a positioning bolt is fixedly mounted on one end of the positioning ear, and the positioning bolt is fixedly mounted on the outer side of the clamp seat.

[0013] Preferably, the tensioning assembly is used to achieve rapid positioning between the clamping arm and the workpiece, and the tensioning assembly includes an eccentric wheel, a rotating shaft, a swing arm and a positioning arm, the eccentric wheel is installed at the top end of the clamping arm, the rotating shaft is fixedly installed on the inner side of the eccentric wheel, and the rotating shaft is rotatably installed at the top end of the clamping arm, the swing arm is rotatably installed at one end of the rotating shaft, and the positioning arm is rotatably installed at the bottom end of the swing arm.

[0014] Preferably, the tensioning assembly also includes a positioning pin, a slide groove, a tooth groove, a socket and an insert block, the positioning pin is rotatably installed at the bottom end of the positioning arm, the slide groove is opened in the middle of the clamping arm, the tooth groove is opened on the inner side of the slide groove, and the tooth groove is set as an oblique groove, the socket is rotatably installed in the middle of the positioning pin, and the socket is slidably installed inside the slide groove, the insert block is plug-in installed inside the socket, and one end of the insert block is set as an oblique structure corresponding to the tooth groove, a spring is installed between the insert block and the socket, a through groove is opened through the inner wall of one side of the socket, a shift block is slidably installed inside the through groove, and the shift block is fixedly installed on the outer side of the plug block.

[0015] Preferably, the tensioning assembly also includes a connecting rod, a pressure arm and a shift rod, the connecting rod is rotatably mounted on the bottom end of the swing arm, the pressure arm is rotatably mounted on the outside of the clamp arm, and the outside of the pressure arm is fitted with the outside of the connecting rod, and the shift rod is fixedly mounted on the bottom end of the pressure arm.

[0016] Preferably, a rubber gasket is installed around the outer side of the eccentric wheel, and the cross-section of the rubber gasket is set to a semicircular structure.

[0017] Technical effects and advantages of the present invention: 1. The present invention arranges a transmission seat and a clamping arm on one side of the clamping seat. The transmission seat is arranged in a triangular structure, and the transmission seat can rotate around one corner. When the transmission seat rotates, the clamping arm can drive the movement of the clamping arm, so that the clamping arm squeezes the workpiece from the inside to the outside to achieve clamping and fixing of the workpiece. In addition, the angular position of the transmission seat as a fulcrum can be adaptively adjusted to adjust the rotation range of the clamping arm, thereby improving the adaptability of the device to workpieces of different specifications. 2. The present invention provides an eccentric wheel at one end of the clamp arm, and the eccentric wheel can rotate at the top end of the clamp arm, and can increase its squeezing force on the inner wall of the workpiece during the rotation process, so as to achieve the effect of improving the clamp arm's clamping stability on the workpiece. A rubber gasket is provided on the outer side of the eccentric wheel, and the cross section of the rubber gasket is set to a semicircular structure. The semicircular structure design allows the rubber gasket to deform after being squeezed by the workpiece, thereby achieving contact protection between the eccentric wheel and the workpiece and improving the clamping stability of the workpiece; 3. The present invention sets a rotating shaft in the middle of the eccentric wheel, and a swing arm and a positioning arm are set at one end of the rotating shaft. The swing arm, the positioning arm and the support arm form a triangular structure. A connecting rod is set between the positioning arm and the swing arm, and a pressure arm is set on one side of the connecting rod. The connecting rod can be squeezed by pulling the pressure arm to drive the positioning arm and the swing arm to move, so that the triangular structure changes. At this time, the swing arm can drive the rotating shaft to rotate, so as to drive the eccentric wheel to rotate, so as to realize rapid clamping of the workpiece. When batch processing of multiple workpieces is performed, the clamping and release of the workpiece can be achieved by only adjusting the position of the eccentric wheel without adjusting the position of the support arm, so as to improve the processing efficiency of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a side schematic diagram of the overall structure of the present invention.

[0020] Figure 3 It is a schematic cross-sectional view of the overall structure of the present invention.

[0021] Figure 4 It is a schematic cross-sectional view of the overall structure of the present invention.

[0022] Figure 5 It is a schematic diagram of the structure of the clamping assembly of the present invention.

[0023] Figure 6 It is a schematic cross-sectional view of the clamping assembly structure of the present invention.

[0024] Figure 7 It is a schematic diagram of the transmission assembly structure of the present invention.

[0025] Figure 8 It is a schematic diagram of the interior of the clamping seat structure of the present invention.

[0026] Fig. 9 It is a schematic diagram of the movable seat structure of the present invention.

[0027] Fig.10 It is a schematic diagram of the positioning seat structure of the present invention.

[0028] In the figure: 1, clamping seat; 2, fixing seat; 3, transmission assembly; 4, clamping assembly; 5, workpiece; 31, transmission seat; 311, connecting groove; 32, movable arm; 33, movable seat; 331, transmission rod; 332, locking screw; 34, positioning seat; 341, limiting seat; 342, arc surface; 343, positioning rod; 344, positioning frame; 345, strip groove; 346, extension plate; 3 47. Positioning ear; 348. Positioning bolt; 41. Clamp arm; 411. Connecting seat; 42. Eccentric wheel; 421. Rubber gasket; 43. Rotating shaft; 44. Swing arm; 45. Positioning arm; 451. Positioning pin; 452. Slide groove; 453. Tooth groove; 454. Socket; 455. Insert block; 456. Through groove; 457. Push block; 46. Connecting rod; 461. Press arm; 462. Push rod. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides Figures 1 to 10 A machine tool precision fixture shown includes a clamping seat 1, which is configured as a cylindrical structure, a fixing seat 2 installed outside the clamping seat 1, a transmission assembly 3 and a clamping assembly 4 installed inside the clamping seat 1, and a workpiece 5 is arranged outside the clamping assembly 4; The fixing seat 2 is used to assist in positioning the workpiece 5. The fixing seat 2 is configured as a ring structure, and the fixing seat 2 is sleeved and installed on the outer side of the clamping seat 1. The transmission assembly 3 is used to drive the clamping assembly 4 to move. The transmission assembly 3 includes two transmission seats 31. The two transmission seats 31 are both arranged in a triangular structure and are both installed at one end of the inner part of the clamping seat 1. A connecting groove 311 is provided at one end of the transmission seat 31 away from the clamping seat 1. A driving assembly and an adjusting assembly are installed at one end of the transmission seat 31 close to the inner part of the clamping seat 1. The driving assembly is used to drive the transmission seat 31 to rotate so as to drive the clamping arm 41. The driving assembly includes a movable arm 32 and a movable seat 33. Two movable arms 32 are provided, and the two movable arms 32 are respectively rotatably mounted on one end of the two transmission seats 31 close to each other, and the movable seat 33 is rotatably mounted between the two movable arms 32, and the movable seat 33 is slidably mounted inside the clamping seat 1; In addition, a transmission rod 331 is fixedly installed at one end of the movable seat 33, and the transmission rod 331 is slidably installed inside the clamping seat 1. A locking screw 332 is rotatably installed at one end of the transmission rod 331, and the locking screw 332 is threadedly installed at one end of the clamping seat 1. The locking screw 332 can drive the movable seat 33 to move, thereby driving the transmission seat 31 to rotate. The adjustment component is used to adjust the rotation range of the transmission seat 31 to improve the adaptability of the clamping arm 41 to different workpieces 5. The adjustment component includes a positioning seat 34, a limiting seat 341, an arc surface 342 and a positioning rod 343. The positioning seat 34 is rotatably mounted on one end of the transmission seat 31, and the positioning seat 34 is set as an arc structure. The limiting seat 341 is fixedly installed inside the clamping seat 1. The arc surface 342 is opened on one side of the limiting seat 341, and the arc surface 342 corresponds to the positioning seat 34. The positioning rod 343 is rotatably mounted in the middle of the positioning seat 34; In addition, a positioning frame 344 is installed on the outer side of the positioning seat 34, and the positioning frame 344 is slidably installed inside the clamping seat 1. A strip groove 345 is opened inside the positioning frame 344, and the strip groove 345 corresponds to the positioning rod 343. The positioning frame 344 can drive the positioning rod 343 to move through the strip groove 345, thereby driving the positioning seat 34 to move; Moreover, an extension plate 346 is fixedly installed at one end of the positioning frame 344, a positioning ear 347 is fixedly installed at one end of the extension plate 346, a positioning bolt 348 is fixedly installed at one end of the positioning ear 347, and the positioning bolt 348 is fixedly installed on the outer side of the clamping seat 1, and the positioning bolt 348 can fix the position of the positioning frame 344; The clamping assembly 4 is used to clamp the workpiece 5 from the inside out. The clamping assembly 4 includes a clamping arm 41. A connecting seat 411 is fixedly provided at the bottom end of the clamping arm 41. The connecting seat 411 corresponds to the connecting groove 311. A tensioning assembly is installed at the top end of the clamping arm 41. The tensioning assembly is used to realize the rapid positioning between the clamping arm 41 and the workpiece 5. The tensioning assembly includes an eccentric wheel 42, a rotating shaft 43, a swing arm 44 and a positioning arm 45. The eccentric wheel 42 is installed at the top of the clamping arm 41, the rotating shaft 43 is fixedly installed on the inner side of the eccentric wheel 42, and the rotating shaft 43 is rotatably installed at the top of the clamping arm 41, the swing arm 44 is rotatably installed at one end of the rotating shaft 43, and the positioning arm 45 is rotatably installed at the bottom end of the swing arm 44; The tensioning assembly also includes a positioning pin 451, a slide groove 452, a tooth groove 453, a socket 454 and an insert block 455. The positioning pin 451 is rotatably mounted on the bottom end of the positioning arm 45. The slide groove 452 is opened in the middle of the clamping arm 41. The tooth groove 453 is opened on the inner side of the slide groove 452, and the tooth groove 453 is set as an oblique groove. The socket 454 is rotatably mounted on the middle of the positioning pin 451, and the socket 454 is slidably mounted inside the slide groove 452. The insert block 455 is plugged and installed. The insert block 455 is arranged inside the socket 454, and one end of the insert block 455 is arranged as an oblique structure corresponding to the tooth groove 453, a spring is arranged between the insert block 455 and the socket 454, a through groove 456 is penetrated through the inner wall of one side of the socket 454, a shift block 457 is slidably arranged inside the through groove 456, and the shift block 457 is fixedly arranged on the outer side of the insert block 455, and the shift block 457 can drive the insert block 455 to move, so as to quickly release the cooperation between the insert block 455 and the tooth groove 453; The tensioning assembly further includes a connecting rod 46, a pressure arm 461 and a lever 462. The connecting rod 46 is rotatably mounted on the bottom end of the swing arm 44. The pressure arm 461 is rotatably mounted on the outer side of the clamp arm 41, and the outer side of the pressure arm 461 is in contact with the outer side of the connecting rod 46. The lever 462 and the pressure arm 461 can drive the connecting rod 46 to move through a lever action to reduce the force when adjusting the position of the eccentric wheel 42. In addition, a rubber gasket 421 is installed around the outer side of the eccentric wheel 42, and the cross-section of the rubber gasket 421 is set to a semicircular structure. The design of the semicircular structure allows the rubber gasket 421 to deform after being squeezed by the workpiece 5, thereby achieving contact protection between the eccentric wheel 42 and the workpiece 5 while improving the clamping stability of the workpiece 5.

[0031] In summary, when the device clamps and fixes the annular workpiece 5, the workpiece 5 is first placed on one side of the clamping seat 1, and then the position of the transmission seat 31 in the transmission assembly 3 is adjusted so that the transmission seat 31 rotates around an angle of its triangular structure. During the rotation process, the transmission seat 31 drives the clamping arm 41 to rotate, so that one end of the clamping arm 41 squeezes the inner wall of the workpiece 5 to achieve clamping and fixing of the workpiece 5. During the clamping process, by adjusting the position of the eccentric wheel 42 so that the eccentric wheel 42 squeezes the inner wall of the workpiece 5, the clamping stability of the device on the workpiece 5 can be improved, and by adjusting the eccentric wheel 42, the workpiece 5 can be quickly installed and disassembled, so as to improve the efficiency of batch processing of multiple workpieces 5. When adjusting the position of the transmission seat 31 to clamp the workpiece 5, by rotating the locking screw 332, the locking screw 332 cooperates with the screw hole at the end of the clamping seat 1, and the transmission rod 331 and the movable seat 33 can be driven to move, and the movable seat 33 can drive the movable arm 32 to move, and the movable arm 32 drives the transmission seat 31 to move, so that the transmission seat 31 rotates around the angle where it is connected to the positioning seat 34; When adjusting the rotation range of the transmission seat 31 to increase the adaptability of the clamping arm 41 to the workpiece 5, by adjusting the position between the positioning bolt 348 and the clamping seat 1, the positioning bolt 348 drives the extension plate 346 and the positioning frame 344 to move, and the positioning frame 344 slides inside the clamping seat 1 and squeezes the positioning rod 343 through the inner wall of the strip groove 345, so that the positioning rod 343 drives the positioning seat 34 to move, and the positioning seat 34 slides along the arc surface 342 to adjust the rotation fulcrum position of the transmission seat 31, thereby adjusting the rotation range of the clamping arm 41, so that the clamping arm 41 can adapt to workpieces 5 of various specifications; When the workpiece 5 is clamped and fixed by the eccentric wheel 42, the lever 462 is pulled so that the lever 462 drives the pressure arm 461 to rotate, and the pressure arm 461 squeezes the connecting rod 46, so that the connecting rod 46 drives the swing arm 44 and the positioning arm 45 to rotate, thereby changing the triangular structure composed of the swing arm 44, the positioning arm 45 and the clamping arm 41. When the swing arm 44 rotates, it can drive the rotating shaft 43 and the eccentric wheel 42 to rotate, so as to adjust the tightening effect of the eccentric wheel 42 on the workpiece 5. In this process, the positioning arm 45 drives the positioning pin 451 and the socket 454 to move, so that the socket 454 can be adjusted. The seat 454 slides in the slide groove 452, and the socket 454 drives the plug block 455 to move. The oblique mouth at one end of the plug block 455 squeezes the tooth groove 453, so that the plug block 455 can slide into the socket 454 to ensure that the socket 454 can slide. After the position adjustment of the eccentric wheel 42 is completed, the plug block 455 engages with the tooth groove 453 under the action of the spring to fix the position of the eccentric wheel 42. By pulling the shift block 457 at one end of the plug block 455 to separate the plug block 455 from the tooth groove 453, the positioning of the eccentric wheel 42 can be released, thereby realizing the rapid disassembly of the workpiece 5.

[0032] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A precision fixture for machine tools, characterized in that: The clamping seat (1) comprises a clamping seat (1) which is arranged as a cylindrical structure, and further comprises a fixing seat (2) installed on the outside of the clamping seat (1), and a transmission assembly (3) and a clamping assembly (4) installed inside the clamping seat (1), wherein a workpiece (5) is arranged on the outside of the clamping assembly (4); The fixing seat (2) is used to assist in positioning the workpiece (5); the fixing seat (2) is arranged as an annular structure, and the fixing seat (2) is sleeved and mounted on the outer side of the clamping seat (1); The transmission assembly (3) is used to drive the clamping assembly (4) to move, and the transmission assembly (3) comprises two transmission seats (31), the two transmission seats (31) are both arranged in a triangular structure, and the two transmission seats (31) are both mounted on one end inside the clamping seat (1), a connection groove (311) is provided on one end of the transmission seat (31) away from the clamping seat (1), and a driving assembly and an adjusting assembly are mounted on one end of the transmission seat (31) close to the inside of the clamping seat (1); The clamping assembly (4) is used to open and clamp the workpiece (5) from the inside out, and the clamping assembly (4) comprises a clamping arm (41), a connecting seat (411) is fixedly provided at the bottom end of the clamping arm (41), and the connecting seat (411) corresponds to the connecting groove (311), and a tensioning assembly is installed at the top end of the clamping arm (41).

2. A machine tool precision fixture according to claim 1, characterized in that: The driving assembly is used to drive the transmission seat (31) to rotate so as to drive the clamping arm (41), and the driving assembly comprises a movable arm (32) and a movable seat (33). Two movable arms (32) are provided, and the two movable arms (32) are respectively rotatably mounted on one end of the two transmission seats (31) close to each other, and the movable seat (33) is rotatably mounted between the two movable arms (32), and the movable seat (33) is slidably mounted inside the clamping seat (1).

3. A machine tool precision fixture according to claim 2, characterized in that: A transmission rod (331) is fixedly mounted on one end of the movable seat (33), and the transmission rod (331) is slidably mounted inside the clamp seat (1); a locking screw (332) is rotatably mounted on one end of the transmission rod (331), and the locking screw (332) is threadedly mounted on one end of the clamp seat (1).

4. The machine tool precision fixture according to claim 1, characterized in that: The adjustment component is used to adjust the rotation range of the transmission seat (31) to improve the adaptability of the clamping arm (41) to different workpieces (5). The adjustment component comprises a positioning seat (34), a limiting seat (341), an arc surface (342) and a positioning rod (343). The positioning seat (34) is rotatably mounted on one end of the transmission seat (31), and the positioning seat (34) is configured as an arc structure. The limiting seat (341) is fixedly mounted inside the clamping seat (1). The arc surface (342) is opened on one side of the limiting seat (341), and the arc surface (342) corresponds to the positioning seat (34). The positioning rod (343) is rotatably mounted on the middle part of the positioning seat (34).

5. A machine tool precision fixture according to claim 4, characterized in that: A positioning frame (344) is installed on the outer side of the positioning seat (34), and the positioning frame (344) is slidably installed inside the clamping seat (1). A strip groove (345) is opened through the interior of the positioning frame (344), and the strip groove (345) corresponds to the positioning rod (343).

6. A machine tool precision fixture according to claim 5, characterized in that: An extension plate (346) is fixedly mounted on one end of the positioning frame (344), a positioning ear (347) is fixedly mounted on one end of the extension plate (346), a positioning bolt (348) is fixedly mounted on one end of the positioning ear (347), and the positioning bolt (348) is fixedly mounted on the outside of the clamping seat (1).

7. The machine tool precision fixture according to claim 1, characterized in that: The tensioning assembly is used to realize rapid positioning between the clamping arm (41) and the workpiece (5), and the tensioning assembly comprises an eccentric wheel (42), a rotating shaft (43), a swing arm (44) and a positioning arm (45), wherein the eccentric wheel (42) is mounted on the top end of the clamping arm (41), the rotating shaft (43) is fixedly mounted on the inner side of the eccentric wheel (42), and the rotating shaft (43) is rotatably mounted on the top end of the clamping arm (41), the swing arm (44) is rotatably mounted on one end of the rotating shaft (43), and the positioning arm (45) is rotatably mounted on the bottom end of the swing arm (44).

8. The precision fixture for machine tools according to claim 7, characterized in that: The tensioning assembly further comprises a positioning pin (451), a slide groove (452), a tooth groove (453), a socket (454) and an insert block (455), wherein the positioning pin (451) is rotatably mounted on the bottom end of the positioning arm (45), the slide groove (452) is arranged in the middle of the clamping arm (41), the tooth groove (453) is arranged on the inner side of the slide groove (452), and the tooth groove (453) is arranged as an oblique groove, and the socket (454) is rotatably mounted on the middle of the positioning pin (451), and the socket (454) is slidably mounted on the inner side of the slide groove (452). The insert block (455) is movably installed inside the slide groove (452), the insert block (455) is plugged and installed inside the socket (454), and one end of the insert block (455) is set as an oblique structure corresponding to the tooth groove (453), a spring is installed between the insert block (455) and the socket (454), a through groove (456) is penetrated through the inner wall of one side of the socket (454), a shift block (457) is slidably installed inside the through groove (456), and the shift block (457) is fixedly installed on the outer side of the insert block (455).

9. The machine tool precision fixture according to claim 7, characterized in that: The tensioning assembly further comprises a connecting rod (46), a pressure arm (461) and a lever (462); the connecting rod (46) is rotatably mounted on the bottom end of the swing arm (44); the pressure arm (461) is rotatably mounted on the outside of the clamping arm (41), and the outside of the pressure arm (461) is in contact with the outside of the connecting rod (46); and the lever (462) is fixedly mounted on the bottom end of the pressure arm (461).

10. The machine tool precision fixture according to claim 7, characterized in that: A rubber gasket (421) is installed around the outer side of the eccentric wheel (42), and the cross section of the rubber gasket (421) is arranged to be a semicircular structure.

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