CN110524288B

CN110524288B - Clamping fixture with oil supply system for machine tool spindle

Info

Publication number: CN110524288B
Application number: CN201910714355.XA
Authority: CN
Inventors: 唐东雷
Original assignee: Jinshang Precision Machine Tool Zhejiang Co ltd
Current assignee: Jinshang Precision Machine Tool Zhejiang Co ltd
Priority date: 2019-08-03
Filing date: 2019-08-03
Publication date: 2022-12-09
Anticipated expiration: 2039-08-03
Also published as: CN110524288A

Abstract

The invention discloses a clamping fixture with an oil supply system for a machine tool spindle, which relates to the field of machine tool parts and comprises a base fixedly connected to a machine tool body, a pressing mechanism connected to the base and used for tightly pressing an outer ring of a workpiece against the base, a mandrel coaxially connected to the spindle and rotating along with the spindle, and an oil supply system for driving the pressing mechanism, wherein one end, away from the spindle, of the mandrel is circumferentially fixed with an inner ring of the workpiece and drives the inner ring of the workpiece to rotate, the pressing mechanism comprises a rotary hydraulic cylinder fixedly connected to the base and a pressing plate connected to the rotary hydraulic cylinder and used for tightly pressing the outer ring of the workpiece against the base, and the oil supply system controls the rotary hydraulic cylinder to drive the pressing plate to tightly press or separate from the outer ring of the workpiece. The invention provides a clamping fixture for a machine tool spindle, which can improve the machining precision of parts.

Description

Clamping fixture with oil supply system for machine tool spindle

Technical Field

The invention relates to machine tool parts, in particular to a clamping fixture with an oil supply system for a machine tool spindle.

Background

The hub bearing is one of the key parts of the automobile, and the main functions of the hub bearing are to bear the weight and provide accurate guidance for the rotation of the hub, so that the hub bearing is required to bear not only axial load but also radial load.

The existing hub bearing unit comprises an inner flange and an outer flange which are connected in a rotating mode, and a ball arranged between the inner flange and the outer flange, and the automobile hub bearing with the fixing assembly disclosed by the Chinese patent publication No. CN208595158U comprises a hub bearing outer ring, a hub bearing inner ring sleeved on the inner side of the hub bearing outer ring, two groups of annular arranging grooves corresponding to each other are arranged on the inner side surface of the hub bearing outer ring and the outer side surface of the hub bearing inner ring, a plurality of steel balls are arranged in the annular arranging grooves, sealing ring assemblies are arranged at two ends of the hub bearing inner ring, and the sealing ring assemblies are in contact with the inner wall of the hub bearing outer ring. In the production and manufacturing process, in order to match the installation requirements in the later stage, the end face of the inner ring of the hub bearing needs to be machined, the end face of the inner ring of the hub bearing can only be machined before the whole assembly by the common machining mode due to the limitation of a machining tool, then the outer ring and the inner ring of the hub bearing are assembled, and because assembly errors exist in the assembly process, the size relation between the inner ring of the hub bearing and the outer ring of the hub bearing can be influenced due to the assembly errors, and further the subsequent actual installation and use are influenced.

Disclosure of Invention

The invention aims to provide a clamping fixture with an oil supply system for a machine tool spindle, which is convenient for fixing one of two relatively rotating parts and enabling the other part to rotate in machining, and avoids influence on product use caused by later assembly errors of the two parts.

The technical purpose of the invention is realized by the following technical scheme: the clamping fixture comprises a base fixedly connected to a machine tool body, a pressing mechanism connected to the base and abutting a workpiece outer ring against the base, a mandrel coaxially connected to the main shaft and rotating along with the main shaft, and an oil supply system for driving the pressing mechanism.

By adopting the technical scheme, before processing, the workpiece outer ring and the workpiece inner ring are assembled firstly, then the workpiece outer ring is tightly abutted to the side wall of the base through the pressing mechanism, the pressing plate can be driven to rotate under the action of the rotary hydraulic cylinder and apply abutting force tightly to the side wall of the base to the workpiece outer ring, the pressing plate is driven to rotate through the rotary hydraulic cylinder, and then the workpiece is convenient to feed and discharge, the installation space of the workpiece is prevented from being blocked by the pressing plate, the contact area between the pressing plate and the workpiece outer ring can be increased by utilizing the pressing plate, the stability during abutting is improved, meanwhile, the workpiece inner ring and the mandrel are fixedly connected in the circumferential direction, so that the workpiece inner ring can be driven to rotate around the self axial direction of the workpiece inner ring under the driving of the main shaft, a machine tool can conveniently process the end face of the workpiece inner ring, the size relation between the workpiece outer ring and the workpiece inner ring can be determined after processing is completed, the precision processing is convenient, the original processed size precision is prevented from being influenced by the assembling error between the inner part and the outer ring and the inner part and the outer part are independently processed, and the inner part and the outer part are more convenient to process.

The invention is further configured to: the rotary hydraulic cylinder comprises a cylinder body fixedly connected to the base, a piston which is connected to the cylinder body in an axial sliding mode along the center of the cylinder body and rotates around the center of the cylinder body in an axial mode, a retainer fixedly connected to the cylinder body, and steel balls arranged between the retainer and the piston, wherein a spiral groove used for embedding the rolling steel balls is formed in the outer wall of the piston arranged in the cylinder body, and the piston is divided into two oil cavities.

By adopting the technical scheme, when oil is filled in one of the oil cavities, the piston is pushed to move in the cylinder body, and because the steel balls in the retainer are embedded in the spiral grooves rolling in the piston, when the piston moves along the center axial direction of the cylinder body, the piston can rotate around the self axial direction by utilizing the acting force of the steel balls on the spiral grooves in the moving process, so that the pressing plate is driven to rotate, and the pressing plate can move while rotating to apply the abutting force on the workpiece.

The invention is further configured to: the oil supply system comprises a hydraulic station, a first oil pipe and a second oil pipe which are communicated with the hydraulic station, an electromagnetic valve which is communicated with the first oil pipe and the second oil pipe, and an upper oil pipe and a lower oil pipe, wherein one end of the upper oil pipe and one end of the lower oil pipe are communicated with the electromagnetic valve, and the other end of the upper oil pipe and the other end of the lower oil pipe are respectively communicated with one oil cavity.

Through adopting above-mentioned technical scheme, utilize the hydraulic oil that the hydraulic pressure station provided certain pressure, rely on the solenoid valve can control oil pipe or oil pipe down and lead to oil to one of them oil pocket respectively to control piston rotates and drives the clamp plate and rotate and remove, realizes supporting tightly or breaking away from the work piece outer lane, and then is convenient for control the motion of clamp plate, reaches better effect that compresses tightly.

The invention is further configured to: the upper oil pipe and the lower oil pipe are arranged on the base and the cylinder body in a penetrating mode.

Through adopting above-mentioned technical scheme, with the pipe that oils that transmits and oil pipe let in to base and cylinder body down, oil pipe wears to establish and influences the exterior space and use about avoiding externally, reaches more reasonable oil circuit and arranges.

The invention is further configured to: the pressing plate is detachably connected with the piston rod.

By adopting the technical scheme, the shape of the pressing plate is changed according to the different shapes of the actual workpieces.

The invention is further configured to: and one end of the mandrel, which is far away from the main shaft, is fixedly connected with a driving spline sleeve which is circumferentially fixed with the inner ring of the workpiece.

By adopting the technical scheme, the spline sleeve is convenient for circumferentially fixing the mandrel and the workpiece inner ring, and the workpiece inner ring can be driven to rotate when the mandrel is driven by the main shaft.

The invention is further configured to: the outer wall of the driving spline sleeve is provided with a spline which is circumferentially fixed with the inner ring of the workpiece, the inner wall of the driving spline sleeve is provided with a key groove which is axially arranged, and the outer wall of the mandrel is connected with a key which is embedded in the key groove.

By adopting the technical scheme, the driving spline housing and the mandrel are circumferentially fixed, the driving spline housing can be synchronously driven to rotate when the mandrel rotates, the driving spline housing can be replaced according to the diameter of the inner ring of an actual workpiece, and the application range of the driving spline housing is expanded.

The invention is further configured to: still including can dismantle connect in the main shaft terminal surface and be coaxial connection pad with the main shaft, the dabber can be dismantled and connect in the connection pad, the dabber is coaxial with the connection pad, the connection pad is arranged in inside and being relative rotation with the base of base.

Through adopting above-mentioned technical scheme, rely on the connection pad can be convenient for fix the dabber to make the dabber keep being coaxial with the connection pad, thereby when connecting work piece inner circle in the dabber, make the work piece keep being coaxial with the dabber, can promote the clamping precision of work piece, and then promote the precision of processing.

In conclusion, the invention has the following beneficial effects: utilize rotary hydraulic cylinder to drive the clamp plate and rotate the limit and remove, realize supporting the work piece outer lane tightly in the base, in step, utilize the drive spline housing to be fixed in the dabber with work piece inner lane circumference, then by the rotation of main shaft drive work piece inner lane, keep the work piece outer lane stable still simultaneously, and then be convenient for utilize the cutter of lathe to process the terminal surface of work piece inner lane, be different from alone to the size relation that the part processing can influence the part because of the assembly error of work piece outer lane inner lane, promoted the size precision of final part.

Drawings

FIG. 1 is a side view of the present embodiment;

FIG. 2 is an enlarged view of section I of FIG. 1;

FIG. 3 is a cross-sectional view of the rotary cylinder of the present embodiment;

FIG. 4 is a schematic view of an oil system;

fig. 5 is a schematic view of the projection of the present embodiment toward the end surface of the main shaft.

Reference numerals: 1. a base; 2. a hold-down mechanism; 21. a rotary hydraulic cylinder; 211. a cylinder body; 212. a piston; 213. a holder; 214. steel balls; 215. a helical groove; 22. pressing a plate; 3. a mandrel; 4. an oil supply system; 41. a hydraulic station; 42. a first oil pipe; 43. a second oil pipe; 44. an electromagnetic valve; 45. feeding an oil pipe; 451. oiling a main pipe; 452. oiling branch pipes; 46. discharging an oil pipe; 461. a main oil drain pipe; 462. an oil discharge branch pipe; 5. an oil chamber; 6. a driving spline housing; 61. a spline; 7. a keyway; 8. a key; 9. a connecting disc; 10. positioning blocks; 11. a machine tool; 12. a spindle housing; 13. a main shaft; 111. a large circular truncated cone; 112. a small round table; 14. locking the nut; 15. a gas path main pipe; 16. a gas path branch pipe; 17. a piston body; 18. a rod is arranged; 19. a lower rod; 20. a rotating groove; 23. an upper guide groove; 24. a middle guide groove; 25. a lower guide groove; 26. an inner ring of a workpiece; 27. and (5) workpiece outer ring.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The clamping fixture with the oil supply system 4 for the machine tool spindle is shown in figure 1 and comprises a base 1 fixedly connected to the side wall of a main shaft shell 12 of a machine tool 11, a connecting disc 9 which is coaxial with the main shaft 13 is fixedly connected to the end face of the main shaft 13, a mandrel 3 which is coaxial with the main shaft 13 is fixedly connected to the end face of the connecting disc 9, which is far away from the main shaft 13, one end, away from the main shaft 13, of a workpiece inner ring 26 and the mandrel 3 is circumferentially fixed and synchronous, a pressing mechanism 2 used for abutting a workpiece outer ring 27 against the side wall of the base 1 is fixedly installed on the end face of the base 1, therefore, in the machining process, the workpiece inner ring 26 is driven by the main shaft 13 to rotate around the axial direction of the workpiece inner ring 26, meanwhile, the workpiece outer ring 27 is kept stable, and machining of the end face of the workpiece inner ring 26 by a cutter of the machine tool 11 is facilitated.

The base 1 is disc-shaped, two ends of the base are penetrated through, a large circular table 111 and a small circular table 112 which are cylindrical are respectively formed on two end surfaces of the base 1, and the position, close to the edge, of the large circular table 111 is fixedly connected to the side wall of the main shaft shell 12 of the machine tool 11 through seven bolts. An inward-concave installation space is formed in one side, facing the main shaft 13, of the large circular table 111, a disc-shaped connecting disc 9 is fixedly connected to the end face of the main shaft 13 through bolts and is arranged in the installation space, after the disc-shaped connecting disc is installed, the connecting disc 9 and the main shaft 13 are kept coaxial, a mandrel 3 which is coaxial with the main shaft 13 is fixedly connected to the center of the connecting disc 9 through bolts, one end, far away from the connecting disc 9, of the mandrel 3 extends out of the small circular table 112, a driving spline housing 6 is fixedly connected to one end, far away from the connecting disc 9, of the mandrel 3 in the circumferential direction, and a spline 61 which is meshed with the workpiece inner ring 26 and fixed in the circumferential direction is formed on the outer wall of the driving spline housing 6 as shown in a combined drawing 2. In order to promote the connection stability of drive spline housing 6 and dabber 3, set up along its axial keyway 7 at drive spline housing 6 inner wall, and be provided with the key 8 of inlaying in keyway 7 at the outer wall of dabber 3, be interference fit between keyway 7 and the key 8, be convenient for realize that drive spline housing 6 and dabber 3's circumference is fixed, then can drive spline housing 6 and rotate under dabber 3's drive, when need changing drive spline housing 6 according to actual product, beat drive spline housing 6 from dabber 3 down, the rethread is more changed key 8 and is installed not unidimensional drive spline housing 6 and come to be suitable for not unidimensional work piece. In the machining process, the driving spline housing 6 and the workpiece inner ring 26 are circumferentially fixed, and the workpiece inner ring 26 is driven by the main shaft 13 to axially rotate around the workpiece inner ring 26.

Referring to fig. 1, in order to tightly fix the workpiece outer ring 27 when the workpiece inner ring 26 is driven to rotate, the pressing mechanism 2 includes two rotary hydraulic cylinders 21 fixedly installed on an end surface of the base 1 on a side away from the spindle 13, each rotary hydraulic cylinder 21 includes a cylindrical cylinder body 211 fixedly connected to the base 1, a central axis of the cylinder body 211 is parallel to a central axis of the mandrel 3, as shown in fig. 3, a piston 212 is slidably connected to the cylinder body 211 along a central axis thereof, the piston 212 includes a piston body 17 disposed inside the cylinder body 211, an upper rod 18 and a lower rod 19 connected to upper and lower end surfaces of the piston body 17, the entire piston 212 is rotatably connected to the cylinder body 211 around its own axis, the upper rod 18 is inserted into the end surface of the cylinder body 211, a seal ring or a seal gasket is disposed between an outer wall of the upper rod 18 and an inner wall of the cylinder body 211, a pressing plate 22 is sleeved on a top end of the upper rod 18 extending out of the cylinder body 211, the upper rod 18 is inserted into the pressing plate 22 and is threadedly connected with a lock nut 14, so as to fix the pressing plate 22 and different shapes of the actual workpieces can be replaced. In order to synchronously rotate while the piston 212 moves, a retainer 213 is fixed at a position close to the bottom end of the cylinder body 211, a rotating groove 20 for the lower rod 19 to be inserted and penetrated is formed in the center of the retainer 213, a plurality of steel balls 214 are connected to the side wall of the rotating groove 20 in a rolling manner along the circumferential direction of the rotating groove on the same plane, synchronously, spiral grooves 215 corresponding to the steel balls 214 one by one are formed in the outer wall of the lower rod 19 along the circumferential direction of the outer wall of the lower rod 19, the spiral grooves 215 are divided into an upper guide groove 23 extending along the axial direction of the lower rod 19, a middle guide groove 24 spirally formed in the outer wall of the lower rod 19 and communicated with the bottom end of the upper guide groove 23, and a lower guide groove 25 communicated with the bottom end of the middle guide groove 24 and extending to the bottom end of the lower rod 19, and when the steel balls 214 are positioned in the lower guide groove 25, the steel balls 214 abut against the bottom end surface of the lower rod 19. A sealing gasket (not marked in the figure) is arranged between the outer wall of the lower rod 19 and the side wall of the rotating groove 20 and above the steel balls 214. The outer edge of the piston body 17 is embedded with a sealing ring which is in sealing fit with the inner wall of the cylinder body 211, the piston body 17 divides the interior of the cylinder body 211 into an upper oil chamber 5 and a lower oil chamber 5 which are not communicated, and the piston body 17 can keep the upper oil chamber 5 and the lower oil chamber 5 separated when moving and rotating in the cylinder body 211. When the rotary hydraulic cylinder 21 rotates and moves the pressing plate 22, the pressing plate 22 can be inserted between the workpiece inner ring 26 and the workpiece outer ring 27, and a pressing force toward the base 1 is applied to the workpiece outer ring 27.

Be convenient for carry out stable positioning to work piece outer lane 27, deviate from connecting pad 9 one side terminal surface at small round platform 112 and pass through locating piece 10 that the center runs through bolt fixedly connected with, locating piece 10 deviates from small round platform 112 one side terminal surface and is on a parallel with main shaft 13 terminal surface, under the effect of clamp plate 22, can support work piece outer lane 27 tightly in work piece outer lane 27 terminal surface steadily.

In order to realize the action of the rotary hydraulic cylinder 21, referring to fig. 4 and 5, the present invention further includes an oil path system, the oil path system includes a hydraulic station 41, the hydraulic station 41 is communicated with a first oil pipe 42 and a second oil pipe 43, the first oil pipe 42 and the second oil pipe 43 are simultaneously communicated with a solenoid valve 44, the solenoid valve 44 selects a two-position four-way valve, the first oil pipe 42 is communicated with an O port of the solenoid valve 44, the second oil pipe 43 is communicated with a P port of the solenoid valve 44, a port a of the solenoid valve 44 is communicated with an upper oil pipe 45, a port B of the solenoid valve 44 is communicated with a lower oil pipe 46, one end of the upper oil pipe 45 away from the solenoid valve 44 is communicated with the oil chamber 5 above the cylinder body 211, one end of the lower oil pipe 46 away from the solenoid valve 44 is communicated with the oil chamber 5 below the cylinder body 211, the upper oil pipe 45 includes an upper oil main pipe 451 (shown in fig. 1) passing through the base 1, the upper oil main pipe 451 is communicated with two upper oil branch pipes 452 (shown in fig. 1) passing through one of the cylinder body 211, the upper oil branch pipe is respectively communicated with the upper oil pipe 452 is communicated with the upper oil chamber 5 of the cylinder body 211, the lower oil main pipe 46 is respectively communicated with one cylinder body 211, the lower oil main pipe 462 passing through the lower oil main pipe 461, and the lower oil main pipe 462 passing through the lower oil main pipe 462, respectively passing through the lower oil main pipe 211, and the lower oil main pipe 462, respectively.

In order to determine the clamping stability of a workpiece, referring to fig. 1, an air path main pipe 15 is arranged in a base 1, the air path main pipe 15 is communicated with two air path branch pipes 16 penetrating through the end face of a small circular table 112, the two air path branch pipes 16 penetrate through the end face of the small circular table 112, which is away from a connecting disc 9, and a connecting line between the centers of the two air path branch pipes 16 passes through the center of the small circular table 112, an opening of one end, away from the air path main pipe 15, of the air path branch pipe 16 is blocked by the end face of a workpiece outer ring 27, so that when a pressing plate 22 tightly presses the workpiece outer ring 27 against the end face of the small circular table 112, gas in the air path branch pipes 16 cannot overflow, a gas pressure detector communicated with the air path main pipe 15 is used for detecting whether the air pressure is stable, if the air pressure is unstable, the gas overflows, the workpiece is not completely tightly pressed against the end face of a positioning block 10, and if the air pressure value is stable, the workpiece is stably clamped.

The working principle of the embodiment is that the outer ring 27 and the inner ring 26 of the workpiece are assembled, the inner wall of the inner ring 26 of the workpiece is sleeved on the driving spline sleeve 6, the spline 61 and the inner wall of the inner ring 26 of the workpiece are circumferentially fixed, meanwhile, the end surface of the outer ring 27 of the workpiece facing one side of the base 1 abuts against the end surface of the positioning block 10, the electromagnetic valve 44 is controlled to charge oil into one oil cavity 5 in the cylinder body 211, the piston body 17 moves in the cylinder body 211, the piston body 17 rotates around the axial direction of the piston body 17 by the cooperation of the steel balls 214 and the spiral grooves 215 while moving, so that the pressing plate 22 is driven to extend between the outer ring 27 of the workpiece and the inner ring 26 of the workpiece, a thrust facing the direction of the base 1 is applied to the end surface of the outer ring 27 of the workpiece facing away from the base 1, and the outer ring 27 of the workpiece abuts against the end surface of the positioning block 10. The workpiece inner ring 26 is driven to rotate by the rotation of the main shaft 13, so that the end face of the workpiece inner ring 26 is machined by a cutter, after the machining is finished, the electromagnetic valve 44 is controlled to charge oil in another oil cavity 5 in the cylinder body 211, the piston body 17 rotates towards the other direction, and the pressing plate 22 is driven to move towards one side away from the base 1 and move out from between the workpiece inner ring 26 and the workpiece outer ring 27, so that the whole workpiece can be conveniently blanked from the driving spline housing 6.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The utility model provides a clamping anchor clamps for lathe main shaft with oil feeding system, characterized by includes:

a base (1) fixedly connected to the bed of the machine tool (11);

the pressing mechanism (2) is connected with the base (1) and tightly presses the outer ring (27) of the workpiece against the base (1), and the pressing mechanism (2) comprises a rotary hydraulic cylinder (21) fixedly connected with the base (1) and a pressing plate (22) connected with the rotary hydraulic cylinder (21) and used for tightly pressing the outer ring (27) of the workpiece against the base (1);

the mandrel (3) is coaxially connected to the main shaft (13) and rotates along with the main shaft (13), and one end, away from the main shaft (13), of the mandrel (3) is circumferentially fixed with the workpiece inner ring (26) and drives the workpiece inner ring (26) to rotate;

the oil supply system (4) drives the pressing mechanism (2), and the oil supply system (4) controls the rotary hydraulic cylinder (21) to drive the pressing plate (22) to press or separate from the outer ring (27) of the workpiece;

one end of the mandrel (3) far away from the main shaft (13) is fixedly connected with a driving spline sleeve (6) which is circumferentially fixed with a workpiece inner ring (26);

a spline (61) circumferentially fixed with the workpiece inner ring (26) is formed on the outer wall of the driving spline sleeve (6), a key groove (7) formed along the axial direction of the driving spline sleeve is formed on the inner wall of the driving spline sleeve (6), and a key (8) embedded in the key groove (7) is connected to the outer wall of the mandrel (3);

the clamping fixture for the machine tool spindle further comprises a connecting disc (9) which is detachably connected to the end face of the spindle (13) and coaxial with the spindle (13), the mandrel (3) is detachably connected to the connecting disc (9), the mandrel (3) is coaxial with the connecting disc (9), and the connecting disc (9) is arranged in the base (1) and rotates relative to the base (1);

the base (1) is disc-shaped, two ends of the base penetrate through the base, a large circular table (111) and a small circular table (112) which are cylindrical are respectively formed on two end faces of the base (1), and one end, far away from the connecting disc (9), of the mandrel (3) extends out of the small circular table (112);

a positioning block (10) with a center penetrating is fixedly connected to the end face of one side, away from the connecting disc (9), of the small circular table (112) through a bolt, the end face of one side, away from the small circular table (112), of the positioning block (10) is parallel to the end face of the main shaft (13), and the pressing plate (22) can stably abut against the end face of the outer ring (27) of a workpiece;

assembling a workpiece outer ring (27) and a workpiece inner ring (26), sleeving the inner wall of the workpiece inner ring (26) on a driving spline sleeve (6), circumferentially fixing a spline (61) and the inner wall of the workpiece inner ring (26), enabling the end surface of the workpiece outer ring (27) facing one side of a base (1) to abut against the end surface of a positioning block (10), controlling an electromagnetic valve (44) to fill oil in one oil cavity (5) in a cylinder body (211), enabling a piston body (17) to move in the cylinder body (211), driving a pressing plate (22) to extend between the workpiece outer ring (27) and the workpiece inner ring (26), applying a thrust facing the direction of the base (1) to the end surface of the workpiece outer ring (27) facing away from the base (1), enabling the workpiece outer ring (27) to abut against the end surface of the positioning block (10), driving the workpiece inner ring (26) to rotate by utilizing the rotation of a main shaft (13), processing the end surface of the workpiece inner ring (26) by a cutter, controlling the electromagnetic valve (44) to enable the cylinder body to rotate the oil cavity (211) of a hydraulic cylinder body (21), enabling the other oil cavity (5) to move out of the other workpiece outer ring (27) and the piston body (17) to move towards the other oil filling direction, and driving the workpiece inner ring (17), the whole workpiece is conveniently fed from the driving spline housing (6);

the workpiece is specifically a hub bearing;

in order to determine the clamping stability of a workpiece, an air path main pipe (15) is arranged in a base (1), the air path main pipe (15) is communicated with two air path branch pipes (16) penetrating through the end face of a small circular table (112), the two air path branch pipes (16) penetrate through the end face, deviating from a connecting disc (9), of the small circular table (112), a connecting line between the centers of the two air path branch pipes (16) passes through the circle center of the small circular table (112), an opening, far away from one end of the air path main pipe (15), of each air path branch pipe (16) is blocked by the end face of a workpiece outer ring (27), when the workpiece outer ring (27) is tightly pressed on the end face of the small circular table (112) by a pressing plate (22), gas in the air path branch pipes (16) cannot overflow, whether the air pressure is kept stable or not is detected by an air pressure detector communicated with the air path main pipe (15), if the air pressure is unstable, the phenomenon that the gas overflows exists is indicated, the workpiece is not completely tightly pressed on the end face of a positioning block (10), and if the air pressure value is kept stable, the workpiece is indicated.

2. The clamping jig for a machine tool spindle according to claim 1, characterized in that: the rotary hydraulic cylinder (21) comprises a cylinder body (211) fixedly connected to the base (1), a piston (212) axially and slidably connected to the cylinder body (211) along the center of the cylinder body (211) and axially and rotatably connected to the cylinder body (211) around the center of the cylinder body (211), a retainer (213) fixedly connected to the cylinder body (211), and steel balls (214) arranged between the retainer (213) and the piston (212), wherein a spiral groove (215) used for embedding the steel balls (214) is formed in the outer wall of the piston (212) arranged in the cylinder body (211), and the cylinder body (211) is divided into two oil cavities (5) by the piston (212).

3. The clamping fixture for the machine tool spindle according to claim 2, wherein the oil supply system (4) comprises a hydraulic station (41), a first oil pipe (42) and a second oil pipe (43) which are communicated with the hydraulic station (41), an electromagnetic valve (44) which is communicated with the first oil pipe (42) and the second oil pipe (43), and an upper oil pipe (45) and a lower oil pipe (46) of which one ends are communicated with the electromagnetic valve (44) and the other ends are respectively communicated with one oil cavity (5).

4. The clamping fixture for the machine tool spindle according to claim 3, wherein the upper oil pipe (45) and the lower oil pipe (46) are both arranged through the base (1) and the cylinder body (211).

5. The clamping fixture for a machine tool spindle according to claim 1, wherein the pressure plate (22) is detachably connected to the piston (212).