CN112247172A

CN112247172A - Hydraulic four-jaw double-acting centering chuck

Info

Publication number: CN112247172A
Application number: CN202011324568.0A
Authority: CN
Inventors: 曲玲; 杨清涛
Original assignee: Yantai Zhonghe Machine Tool Accessories Co ltd
Current assignee: Yantai Zhonghe Machine Tool Accessories Co ltd
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2021-01-22

Abstract

The invention relates to a hydraulic four-jaw double-acting centering chuck which comprises a chuck body, clamping jaws, a sliding seat, a T-shaped block, a first wedge sleeve and a second wedge sleeve, wherein the sliding seat is slidably arranged on the chuck body, the clamping jaws are indirectly fixed on the sliding seat through the T-shaped block, two opposite clamping jaws in the four clamping jaws form a group, the first wedge sleeve and the second wedge sleeve are arranged in the chuck body, a cylindrical cavity is formed in the chuck body, the first wedge sleeve is in wedge fit with one group of clamping jaws and then slidably arranged in the cylindrical cavity, the upper end of the first wedge sleeve is provided with a square cavity, the second wedge sleeve is in wedge fit with the other group of clamping jaws and then slidably arranged in the square cavity, and a lathe is provided with a same-side double-acting oil cylinder which respectively and independently pulls the first wedge sleeve and the second wedge sleeve to drive the two groups of clamping jaws. The two groups of clamping jaws form a double-acting effect, and are respectively clamped from the side surface of the breaking hammer cylinder body, so that the requirement of an operator on adjusting the positions of the clamping jaws is reduced, and meanwhile, the service life of the oil cylinder can be prolonged.

Description

Hydraulic four-jaw double-acting centering chuck

Technical Field

The invention relates to the technical field of tool fixtures, in particular to a hydraulic four-jaw double-acting centering chuck.

Background

The breaking hammer is a common engineering machine in building construction, the appearance of a breaking hammer cylinder body is a cuboid, an inner hole needing to be processed is arranged in the breaking hammer cylinder body, and the center of the inner hole and the center of the cuboid are eccentric.

At present, the eccentric inner hole on the cylinder body of the breaking hammer is machined in China, a four-jaw self-centering hydraulic chuck is generally adopted, clamping is carried out from four side faces of the cylinder body, the breaking hammer cylinder body is cuboid, the machined inner hole is located at the eccentric position of the cylinder body, an operator needs to adjust the positions of the four jaws according to the size of a workpiece, meanwhile, a cushion block needs to be added on the jaws to be matched with the eccentric position of the machined inner hole, the requirement on the operator is higher, the operation time is longer, and the low working efficiency is caused.

The cylinder body height of quartering hammer is higher usually, needs bigger clamping-force during the jack catch centre gripping, and a jack catch clamping-force is provided by a hydro-cylinder usually to a chuck, when making the clamping-force increase, must improve hydro-cylinder pressure, receives the influence of hydro-cylinder self, and hydro-cylinder pressure is limited, and the pressure of improvement is limited, leads to the centre gripping effect of jack catch poor.

Disclosure of Invention

Aiming at the defects in the prior art when an eccentric hole on a breaking hammer cylinder body is processed, firstly, when the breaking hammer cylinder body is clamped by the clamping jaws, the clamping jaws are complex to adjust, the operation time is long, the requirement on an operator is high, the working efficiency is low, and secondly, the clamping force of the clamping jaws is difficult to improve, and the clamping effect is poor, the invention provides the hydraulic four-jaw double-centering chuck, which can respectively and independently control the movement of two groups of opposite clamping jaws to form a double-acting effect, respectively clamp from the side surface of the breaking hammer cylinder body, reduce the time for the operator to adjust the clamping jaws, also reduce the requirement on the operator, greatly improve the working efficiency, simultaneously, respectively pull the two groups of clamping jaws to independently move by the double-acting oil cylinder to clamp the breaking hammer cylinder body, increase the clamping force of the chuck by one time, compared with the traditional hydraulic four-jaw chuck, the double-acting oil cylinder can achieve, the service life of the oil cylinder is greatly prolonged.

One of the above objects of the present invention is achieved by the following technical solutions:

a hydraulic four-jaw double-acting centering chuck comprises a chuck body, clamping jaws, a sliding seat, a T-shaped block, a first wedge core sleeve and a second wedge core sleeve, wherein a sliding groove is formed in the upper end face of a cylindrical cavity chuck body, the sliding seat is slidably arranged in the sliding groove, first comb teeth are formed in the upper end face of the sliding seat, second comb teeth are formed in the lower end face of each clamping jaw, the clamping jaws are indirectly fixed on the sliding seat through the T-shaped block, the first comb teeth and the second comb teeth are meshed, the cylindrical cavity clamping jaws comprise a first clamping jaw, a second clamping jaw, a third clamping jaw and a fourth clamping jaw, the first clamping jaw and the third clamping jaw are oppositely arranged, the second clamping jaw and the fourth clamping jaw are oppositely arranged, a cylindrical cavity is formed in the cylindrical cavity chuck body, first wedge-shaped T-shaped grooves are formed in two ends of the first wedge core sleeve, oblique wedge-shaped T-shaped keys are respectively arranged at the inner ends of the first clamping jaw and the third clamping jaw, the upper end of the first wedge core sleeve is provided with a square cavity, the upper end of the second wedge core sleeve is located inside the square cavity, the lower end of the second wedge core sleeve is correspondingly inserted into a central long hole I of the first wedge core sleeve, two ends of the second wedge core sleeve are provided with inclined wedge type T-shaped grooves II, the inner ends of the second clamping jaw and the fourth clamping jaw are provided with inclined wedge type T-shaped keys II, the second wedge core sleeve is slidably installed in the first wedge core sleeve after the T-shaped grooves II and the T-shaped keys are matched, a power cylinder is installed on a lathe, and the cylindrical cavity power cylinder respectively and independently pulls the first wedge core sleeve and the second wedge core sleeve to respectively and independently drive two groups of opposite clamping jaws to move.

Two opposite direction jaws in four jaws constitute a set of separately, first jaw and third jaw are a set of, second jaw and fourth jaw are a set of, through wedge cover one and wedge cover two, independently promote two sets of jaws respectively and remove the tight work piece of clamp, form double acting effect, add man-hour to the eccentric orfice on the damaged hammer cylinder body, jaw position control is convenient simple, reduced the requirement to the operator, shorten the adjustment time, greatly improved work efficiency, the centre gripping is effectual simultaneously, centre gripping quartering hammer cylinder body that can be stable.

Preferably, the power cylinder is a double-acting cylinder on the same side and comprises a large piston rod and a small piston rod, the piston parts of the large piston rod and the small piston rod are movably arranged in the inner cavity of the cylinder body of the double-acting cylinder in a penetrating mode, the upper end of the small piston rod extends into the center long hole of the first wedge sleeve, the upper end of the small piston rod and the lower end of the second wedge sleeve are fixedly connected through the same long bolt, the upper end of the large piston rod is in threaded connection with the lower end of the first wedge sleeve to pull the first wedge sleeve, the double-acting cylinder respectively pulls the two groups of clamping jaws to independently move to clamp the breaking hammer cylinder body, the clamping force of the chuck is increased by one time, compared with a traditional hydraulic four-jaw chuck, the double-acting cylinder can achieve a stable clamping effect when being maintained at normal pressure, the pressure of the cylinder does not need to be.

Preferably, the height of the upper end of the second wedge core sleeve is smaller than the depth of the square cavity, a sliding space is formed between the bottom surface of the upper end of the second wedge core sleeve and the bottom surface of the square cavity, a gap is reserved between the bottom surface of the upper end of the second wedge core sleeve and the bottom surface of the square cavity, the sliding space is formed, the second wedge core sleeve slides along the side surface of the square cavity all the time, and the stability during sliding is enhanced.

Preferably, the dustproof cover is arranged on the disk body, the dustproof cover is located at the center of the upper end face of the disk body, a dustproof cover plate is arranged on the outer side of the dustproof cover, the upper end of the dustproof cover plate is abutted to the edge of the dustproof cover, a first sealing groove is formed in the position, corresponding to the dustproof cover plate, of the edge of the dustproof cover, a first dustproof strip is arranged inside the first sealing groove, a blocking cover is arranged in the middle of the dustproof cover and corresponding to a second wedge sleeve, and the upper end, located inside the dustproof cover, of the blocking cover is fixed to the dustproof cover through bolts.

Preferably, a second sealing groove is formed in the upper end face of the disc body on two sides of the sliding seat, and a second dust strip is mounted inside the second sealing groove.

Through adding and establishing shield, dust-proof cover board and dust strip one and dust strip two, can form good sealed to disk body up end, prevent effectively that foreign matters such as dust, the iron powder that the cutting produced lead to inside getting into the disk body, form good protection to the spare part of disk body inside.

Preferably, the clamping surfaces of the clamping jaw and the workpiece are fixedly provided with an insert, a cushion block is arranged between the insert and the clamping jaw, when the position of the clamping jaw is adjusted, when the offset and the tooth pitch of the comb teeth form an integer multiple relation, the clamping jaw can be adjusted by moving the comb teeth, when the offset and the tooth pitch of the comb teeth do not form an integer multiple relation, the cushion blocks with different thicknesses can be additionally arranged to adjust, and finally the eccentric requirement is met.

In summary, the invention includes at least one of the following beneficial technical effects:

1. the double-acting oil cylinder is matched with the first wedge core sleeve and the second wedge core sleeve to form a double-acting effect, two groups of opposite clamping jaws move independently to clamp a workpiece respectively, an operator adjusts the position of each clamping jaw independently according to the offset, and the comb teeth at different positions are adjusted to be meshed, so that the requirement on the operator is greatly reduced, the clamping jaw position is adjusted conveniently and quickly, the time for adjusting the clamping jaws is effectively shortened, the working efficiency is improved, meanwhile, the double-acting oil cylinder pulls the two groups of clamping jaws to move independently to clamp the breaking hammer cylinder body respectively, the clamping force of the clamping chuck is doubled compared with that of a traditional hydraulic four-jaw clamping chuck, the stable clamping effect can be achieved when the double-acting oil cylinder is maintained at normal pressure, the oil cylinder pressure does not need to be increased, and the service;

2. when the offset and the tooth pitch are not integral multiples, the adjustment requirement is difficult to meet only by adjusting the meshing of the comb teeth at different positions, and the cushion blocks with different thicknesses are additionally arranged for adjustment to meet the eccentric requirement;

3. the upper end face of the tray body is provided with the dustproof cover, the dustproof cover plate, the first dustproof strip and the second dustproof strip, so that the upper end face of the tray body can be well sealed, foreign matters such as dust and iron powder generated by cutting can be effectively prevented from entering the tray body, and parts in the tray body can be well protected.

Drawings

FIG. 1 is a perspective view of the present invention;

FIG. 2 is an exploded view showing the positional relationship of various components on the tray body;

FIG. 3 is a perspective view of the tray body;

FIG. 4 is a schematic view of the combination of the first and second wedge sleeve;

FIG. 5 is a perspective view of a first wedge sleeve;

FIG. 6 is a perspective view of a second wedge sleeve;

FIG. 7 is a schematic cross-sectional view showing a first wedge sleeve and a second wedge sleeve pulling manner;

FIG. 8 is a schematic cross-sectional view showing the pulling of the second and fourth jaws;

FIG. 9 is a schematic cross-sectional view showing a third jaw pulling pattern of the first jaw;

fig. 10 is a schematic diagram showing the working state of the jaws.

In the figure, 1, a disc body; 2. a claw; 3. a slide base; 4. a T-shaped block; 5. sleeving a wedge core I; 6. a second wedge core sleeve; 7. a chute; 8. comb teeth I; 9. comb teeth II; 10. a T-shaped block; 11. a first jaw; 12. a second jaw; 13. a third jaw; 14. a fourth jaw; 15. a cylindrical cavity; 16. a first T-shaped groove; 17. a T-shaped bond I; 18. a square cavity; 19. a first central long hole; 20. a T-shaped groove II; 21. a T-shaped bond II; 22. a large piston rod; 23. a small piston rod; 24. a dust cover; 25. a dust-proof cover plate; 26. a first sealing groove; 27. a first dust strip; 28. blocking the cover; 29. a second sealing groove; 30. a second dust strip; 31. an insert; 32. cushion blocks; 33. a T-shaped long slot; 34. a fitting groove; 35. a yielding groove; 36. an annular groove; 37. an O-shaped ring; 38. a power cylinder; 39. and a second central long hole.

Detailed Description

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

Referring to fig. 1-3, a hydraulic four-jaw double-acting chuck comprises a disk body 1, the disk body 1 is in a flat cylinder shape and is arranged on a lathe, four sliding grooves 7 which are symmetrically distributed in a cross shape are arranged on the upper end surface of the disk body 1, a sliding seat 3 is slidably arranged in the sliding grooves 7, a jaw 2 is correspondingly fixed on the sliding seat 3, a first comb tooth 8 is arranged on the upper end surface of the sliding seat 3, a second comb tooth 9 is arranged on the lower end surface of the jaw 2, a T-shaped long groove 33 is arranged on the upper end surface of the sliding seat 3 along the length direction, a T-shaped block 4 which is matched with the T-shaped long groove 33 is arranged in the T-shaped long groove 33, the upper end of the T-shaped block 10 protrudes out of the upper end surface of the sliding seat 3, a strip-shaped embedding groove 34 is arranged on the lower end surface of the jaw 2 corresponding to the T-shaped block 4 which protrudes out of the sliding seat 3, the jaw 2 is indirectly fixed, the clamping jaw 2 is connected with the T-shaped block 4 through a bolt with the same length.

Referring to fig. 1-9, the jaws 2 include a first jaw 11, a second jaw 12, a third jaw 13 and a fourth jaw 14, the first jaw 11 and the third jaw 13 are oppositely disposed to jointly form a group of clamping jaws, the second jaw 12 and the fourth jaw 14 are oppositely disposed to jointly form another group of clamping jaws, a cylindrical cavity 15 is formed in the middle of the tray body 1, a wedge sleeve 5 is slidably mounted in the cylindrical cavity 15, the wedge sleeve 5 and two ends of the first jaw 11 and the third jaw 13 corresponding to the wedge T-shaped groove 16 are respectively provided with an oblique wedge T-shaped key 17, the inner ends of the first jaw 11 and the third jaw 13 are respectively provided with an oblique wedge T-shaped key 17, the T-shaped key 17 is slidably mounted in the T-shaped groove 16, the wedge sleeve 5 is pulled, the slide carriage 3 below the first jaw 11 and the third jaw 13 is driven to move by the mutual cooperation of the T-shaped key 17 and the T-shaped groove 16, then the first jaw 11 and the third jaw 13 are driven to move, the upper end of the first wedge sleeve 5 is provided with a square cavity 18, the first wedge sleeve 5 is connected with a second wedge sleeve 6 in a sliding manner, the first wedge sleeve 5 and the second wedge sleeve 6 are coaxial, the lower end of the second wedge sleeve 6 is inserted into a first central long hole 19 of the first wedge sleeve 5, the upper end of the second wedge sleeve 6 is correspondingly arranged in the square cavity 18 and the shape of the second wedge sleeve is matched with that of the square cavity 18, the two ends of the first wedge sleeve 5, corresponding to the second jaw 12 and the fourth jaw 14, are provided with abdicating grooves 35, the two ends of the second wedge sleeve 6 extend out of the abdicating grooves 35 and are provided with a second wedge-shaped T-shaped groove 20, the inner end parts of the second jaw 12 and the fourth jaw 14 are fixedly provided with a second wedge-shaped T-shaped key 21, the second T-shaped key 21 is slidably arranged in the second T-shaped groove 20, the second wedge sleeve 6 is pulled to be matched with the second T-shaped groove 20 through, the sliding base 3 below the second jaw 12 and the fourth jaw 14 is driven to move, and then the second jaw 12 and the fourth jaw 14 are driven to move. The first wedge core sleeve 5 and the second wedge core sleeve 6 are matched with each other, the movement of the two groups of opposite clamping jaws 2 can be controlled independently, a double-acting effect is formed, and the double-action wedge core clamping device is suitable for clamping square workpieces.

Referring to fig. 7-9, a power cylinder 38 is arranged below the disc body 1 corresponding to the positions of the first wedge sleeve 5 and the second wedge sleeve 6, the power cylinder 38 is installed on the lathe, the power cylinder 38 is a double-acting cylinder on the same side and comprises a large piston rod 22 and a small piston rod 23, piston parts of the large piston rod 22 and the small piston rod 23 are movably inserted in a cylinder cavity of the double-acting cylinder, the upper end of the small piston rod 23 extends into a central long hole I19 with the first wedge sleeve 5, the upper ends of the second wedge sleeve 6 and the small piston rod 23 are connected through a same-length bolt, the top of a long bolt is clamped in the central long hole II 39 of the second wedge sleeve 6, the bottom of the long bolt is in threaded connection with the upper end of the small piston rod 23, an internal thread is arranged on the lower section of the central long hole 19 of the first wedge sleeve 5, so that the bottom of the first wedge sleeve 5 is fixed with the top thread pitch of the large piston rod 22, the large piston rod 22 of the power cylinder 38 pulls the, the small piston rod 23 pulls the second wedge core sleeve 6 to respectively and independently work.

The height of the upper end of the second wedge core sleeve 6 is smaller than the depth of the square cavity 18, so that a sliding space is formed between the bottom surface of the upper end of the second wedge core sleeve 6 and the bottom surface of the square cavity 18, a space is reserved between the bottom surface of the upper end of the second wedge core sleeve 6 and the bottom surface of the square cavity 18, the second wedge core sleeve 6 can slide up and down conveniently, the second wedge core sleeve 6 can slide along the side surface of the square cavity 18 all the time, and the stability during sliding is enhanced.

Referring to fig. 1 and 2, a dust cover 24 is arranged at the upper end of the tray body 1 corresponding to the upper opening of the cylindrical cavity 15, the dust cover 24 is fixed on the tray body 1 through bolts, the dust cover 24 is a square dust cover 24 and is located at the central position of the upper end of the tray body 1, four side lines of the dust cover 24 correspond to the positions of the four jaws 2, respectively, a blanking cover 28 is arranged at the center of the dust cover 24 corresponding to the position of the second wedge sleeve 6, the upper end of the blanking cover 28 is fixed on the dust cover 24 through bolts, the lower end of the blanking cover 28 extends into the central long hole 19 of the second wedge sleeve 6 and is in sliding connection with the second wedge sleeve 6, the dust cover 24 and the blanking cover 28 can seal the upper end opening of the tray body 1, foreign matters in the process of processing workpieces can be effectively prevented from entering the interior of the second wedge sleeve 6 and the interior of the tray body 1, parts in the tray body 1 are protected, the dust cover 24 is, the lower extreme of shield 24 board passes through on the bolt fastening slide 3, the upper end of shield 24 board supports with the shield 24 up end and presses, in the in-process that slide 3 removed, on the one hand shield 24 board can cooperate with shield 24 with the clearance seal between shield 24 and the slide 3, guarantee the leakproofness of disk body 1 up end, on the other hand can support and press shield 24, further strengthen the sealed effect of shield 24 and blanking cover 28, rectangular form seal groove 26 has been seted up to the four sides line department of shield 24 up end, seal groove 26 is inside to have installed dust strip 27, shield 24 board upper end supports with dust strip 27 all the time and presses, through the further clearance between shield 24 board of sealed shield 24 board and the shield 24 of dust strip 27.

Referring to fig. 1-3, the upper end of the tray body 1 is provided with two sealing grooves 29 corresponding to the two sides of the sliding seat 3, two dust-proof strips 30 are arranged in the two sealing grooves 29, the two dust-proof strips 30 are fixed on the tray body 1 through bolts, the side surfaces of the two dust-proof strips 30 are tightly attached to the side surfaces of the sliding seat 3 and the dust-proof cover 24, and the two dust-proof strips 30 can effectively prevent foreign matters from entering the tray body 1 through the gap between the sliding seat 3 and the tray body 1.

Through additionally arranging the dust cover 24, the dust cover 24 plate, the first dust strip 27 and the second dust strip 30, the upper end face of the disc body 1 can be well sealed, foreign matters such as dust and iron powder generated by cutting can be effectively prevented from entering the disc body 1, and parts in the disc body 1 can be well protected.

Referring to fig. 2, a horizontally closed annular groove 36 is formed in the outer side surface of the lower end of the second wedge sleeve 6, an O-shaped ring 37 is installed inside the annular groove 36, the inner side surface of the first central long hole 19 of the first wedge sleeve 5 abuts against the O-shaped ring 37 and extrudes the O-shaped ring 37, and the O-shaped ring 37 can seal the gap between the first wedge sleeve 5 and the second wedge sleeve 6 to prevent foreign matters from entering, so that the second wedge sleeve 6 has good smoothness in a sliding manner.

Referring to fig. 1 and 10, an insert 31 is arranged on a collision surface of a jaw 2 and a workpiece, a cushion block 32 is arranged between the insert 31 and the side surface of the jaw 2, the cushion block 32 is made of 45 steel, the insert 31 is made of 20CrMnTi, the insert 31 and the cushion block 32 are fixed on the jaw 2 through bolts, the position of the jaw 2 is adjusted by moving the meshing of comb teeth at different positions, the eccentricity requirement is met, when the offset and the comb teeth pitch are in integer multiple relation, the adjustment can be carried out by moving the comb teeth, and when the offset and the comb teeth pitch are not in integer multiple relation, the cushion block 32 with different thicknesses can be added for adjustment. The 20CrMnTi has good low-temperature impact toughness, small processing deformation and quite good fatigue resistance, and can meet the extrusion requirement of the side surface of the cylinder body of the breaking hammer.

Because two sets of opposite jaws 2 move independently respectively to clamp the side face of the cylinder of the breaking hammer, the first jaw 11 and the third jaw 13 are one set, the second jaw 12 and the fourth jaw 14 are one set, a worker can adjust the position of each jaw 2 and add a cushion block 32 independently according to different offset of the side face of the cylinder of the breaking hammer, the first jaw 11 and the third jaw 13 are symmetrically arranged with the center of an eccentric hole, the meshing condition of comb teeth and the thickness of the cushion block 32 are kept consistent during adjustment, and the second jaw 12 and the fourth jaw 14 can adjust the position independently corresponding to the size of a workpiece respectively. Two sets of jack catchs 2 are pressed from both sides tightly from the contralateral surface of quartering hammer cylinder body respectively, reduce the operator and adjust the time of jack catch 2, have also reduced the requirement to the operator, have improved work efficiency greatly.

The working process is as follows: the cylinder body of the breaking hammer is correspondingly arranged at the upper end of the disc body 1, the eccentric hole on the cylinder body of the breaking hammer is aligned with the center of the disc body 1, a worker firstly adjusts the position of the clamping jaw 2 according to the size of the cylinder body of the breaking hammer, adjusts the position of the clamping jaw 2 by moving the comb teeth at different positions, when the tooth pitch of the comb teeth does not meet the adjustment requirement, the eccentric requirement is met by additionally arranging the cushion blocks 32 with different thicknesses, the double-acting oil cylinder respectively and independently drives the two groups of clamping jaws 2 to move to clamp the side face of the breaking hammer cylinder body, the large piston rod 22 pulls the first wedge sleeve 5 to drive the sliding seat 3, the first clamping jaw 11 and the third clamping jaw 13 to move to clamp the left side face and the right side face of the breaking hammer cylinder body, the small piston rod 23 pulls the second wedge sleeve 6 to drive the sliding seat 3, the second clamping jaw 12 and the fourth clamping jaw 14 to move to clamp the front side face and the rear side face of the breaking hammer cylinder body, the breaking hammer cylinder body is finally clamped, and an eccentric hole is machined.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.

Claims

1. The utility model provides a hydraulic pressure four-jaw double acting centering chuck, includes disk body (1), jack catch (2), slide (3), T type piece (10), wedge cover one (5) and wedge cover two (6), its characterized in that: the upper end face of the tray body (1) is provided with a sliding groove (7), the sliding seat (3) is arranged in the sliding groove (7) in a sliding mode, the upper end face of the sliding seat (3) is provided with a first comb tooth (8), the lower end face of the clamping jaw (2) is provided with a second comb tooth (9), the clamping jaw (2) is indirectly fixed on the sliding seat (3) through a T-shaped block (10), the first comb tooth (8) is meshed with the second comb tooth (9), the clamping jaw (2) comprises a first clamping jaw (11), a second clamping jaw (12), a third clamping jaw (13) and a fourth clamping jaw (14), the first clamping jaw (11) and the third clamping jaw (13) are oppositely arranged, the second clamping jaw (12) and the fourth clamping jaw (14) are oppositely arranged, a cylindrical cavity (15) is formed in the tray body (1), two ends of the first wedge-shaped sleeve (5) are provided with oblique wedge-shaped first T-shaped grooves (16), and the inner ends of the first clamping jaw (11) and the third clamping, after the T-shaped groove I (16) is matched with the T-shaped key I (17), the wedge core sleeve I (5) is installed in a cylindrical cavity (15) in a sliding mode, a square cavity (18) is formed in the upper end of the wedge core sleeve I (5), the upper end of the wedge core sleeve II (6) is located in the square cavity (18), the lower end of the wedge core sleeve II (6) is correspondingly inserted into a central long hole I (19) of the wedge core sleeve I (5), wedge-shaped T-shaped grooves II (20) are formed in the two ends of the wedge core sleeve II (6), wedge-shaped T-shaped keys II (20) are arranged at the inner ends of the second clamping jaw (12) and the fourth clamping jaw (14), the wedge core sleeve II (6) is installed in the wedge core sleeve I (5) in a sliding mode after the T-shaped grooves II (20) are matched with the T-shaped keys II (21), a power oil cylinder (38) is installed on a lathe, and the power oil cylinder (38) respectively and independently pulls the wedge core sleeve I (5) and the wedge core sleeve II (6, the two groups of opposite clamping jaws (2) are respectively and independently driven to move.

2. A hydraulic four-jaw double-action centering chuck according to claim 1, characterized in that: the power cylinder is a double-acting cylinder on the same side and comprises a large piston rod (22) and a small piston rod (23), piston parts of the large piston rod (22) and the small piston rod (23) are movably arranged in a cylinder inner cavity of the double-acting cylinder in a penetrating mode, the upper end of the small piston rod (23) extends into a central long hole (19) of the first wedge sleeve (5), the upper end of the small piston rod (23) is fixedly connected with the lower end of the second wedge sleeve (6) through a same long bolt, and the upper end of the large piston rod (22) is in threaded connection with the lower end of the first wedge sleeve (5) to pull the first wedge sleeve (5).

3. A hydraulic four-jaw double-action centering chuck according to claim 1, characterized in that: the height of the upper end of the second wedge core sleeve (6) is smaller than the depth of the square cavity (18), and a sliding space is formed between the bottom surface of the upper end of the second wedge core sleeve (6) and the bottom surface of the square cavity (18).

4. A hydraulic four-jaw double-action centering chuck according to claim 1, characterized in that: be provided with shield (24) on disk body (1), shield (24) are located the central point of disk body (1) up end and put the department, shield (24) outside is equipped with shield (25), the upper end and the shield (24) edge of shield (25) support to press, seal groove (26) have been seted up to shield (24) edge position that corresponds shield (25), seal groove (26) internally mounted has dust strip (27), shield (24) middle part corresponds the position of heart of wedge cover two (6) and is equipped with blanking cover (28), the upper end that blanking cover (28) are located shield (24) inside and blanking cover (28) is passed through the bolt fastening on shield (24).

5. A hydraulic four-jaw double-action centering chuck according to claim 1, characterized in that: and a second sealing groove (29) is formed in the upper end face of the disc body (1) on the two sides of the sliding seat (3), and a second dust strip (30) is arranged inside the second sealing groove (29).

6. A hydraulic four-jaw double-action centering chuck according to claim 1, characterized in that: insert blocks (31) are fixed on the clamping surfaces of the clamping jaws (2) and the workpiece, and cushion blocks (32) are arranged between the insert blocks (31) and the clamping jaws (2).