A four jaw chuck

Abstract

The utility model relates to a four -jaw clamping forceps belongs to clamping forceps technical field, including the shell, shell fixed setting is in the base, is fixedly set with the transition sleeve at the shell front end opening, is fixedly set with the front end cover at transition sleeve front side, is fixedly set with the back end cover at the shell rear end opening, the back end of front end cover and the front end of back end cover mutual contact, be provided with four sliding slots between the contact surface of front end cover and back end cover, each sliding slot inside is slidably set with a pawl along the radial of shell, is provided with first inclined plane on the side end face of pawl far away from shell axis, is slidably set with the piston in the shell, and the piston is located between shell and back end cover, is provided with four second inclined planes on the piston, four second inclined planes on the piston respectively with first inclined plane on four pawls slide contact, solved the current drill pipe clamping equipment clamping force uneven, corresponding speed is slow, poor adaptability, the problem of insufficient sealing.

Description

Technical Field

[0001] This utility model belongs to the field of clamping pliers technology, specifically relating to a four-jaw clamping pliers. Background Technology

[0002] In the fields of oil drilling, geological exploration, and machining, the clamping and fixing of drill pipes is a key part of the operation. Traditional clamping devices mostly use mechanical thread locking, hydraulic chucks, or manual clamps, which have the following shortcomings: (1) Uneven clamping force: Mechanical clamping relies on manual operation, which can easily lead to uneven distribution of clamping force, causing the drill pipe to slip or be damaged on the surface; (2) Slow response speed: Hydraulic chucks have a complex structure, require additional hydraulic system support, and have a complicated operation process and delayed response; (3) Poor adaptability: Existing clamps have limited compatibility with changes in drill pipe diameter, and it is time-consuming and labor-intensive to replace the chuck or adjust the structure; (4) Insufficient sealing: After long-term use, the hydraulic oil chamber is prone to leakage due to sealing failure, which affects the clamping stability.

[0003] Therefore, there is an urgent need for a four-jaw clamp with a compact structure, uniform clamping force, rapid response, and reliable sealing to meet the requirements for efficient and precise drill pipe fixing. Utility Model Content

[0004] This invention overcomes the shortcomings of the prior art by proposing a four-jaw clamping clamp, which solves the problems of uneven clamping force, slow response speed, poor adaptability, and insufficient sealing of current drill pipe clamping equipment.

[0005] To achieve the above objectives, this utility model is implemented through the following technical solution.

[0006] A four-jaw clamp includes a housing, which is fixedly mounted on a base. A transition sleeve is fixedly mounted at the front opening of the housing, and a front end cover is fixedly mounted at the front side of the transition sleeve. A rear end cover is fixedly mounted at the rear opening of the housing. The rear end of the front end cover and the front end of the rear end cover are in contact with each other. Four sliding grooves are provided between the contact surfaces of the front end cover and the rear end cover. A jaw is slidably mounted inside each sliding groove along the radial direction of the housing. A first inclined surface is provided on the end face of the jaw away from the axis of the housing. A piston is slidably mounted inside the housing, located between the housing and the rear end cover. Four second inclined surfaces are provided on the piston, and the four second inclined surfaces on the piston are in sliding contact with the first inclined surfaces on the four jaws, respectively.

[0007] Furthermore, a fixing ear plate is fixedly installed on the left and right sides of the outer surface of the shell; a set of mounting seats is fixedly installed on the left and right sides of the upper end face of the base. The two fixing ear plates on the shell are respectively inserted into the two sets of mounting seats on the upper end face of the base, and a mounting pin is inserted between the fixing ear plates and the mounting seats.

[0008] Furthermore, the front end cover includes a first ring and a first cylinder. The first ring is fixedly sleeved on the outside of the front end opening of the first cylinder. The first ring of the front end cover is located in front of the front end opening of the outer shell, and the first cylinder of the front end cover is inserted into the inside of the front end opening of the outer shell. The rear end cover includes a second ring and a second cylinder. The second ring is fixedly sleeved on the outside of the rear end opening of the second cylinder. The second ring of the rear end cover is located behind the rear end opening of the outer shell, and the second cylinder of the rear end cover is inserted into the inside of the rear end opening of the outer shell. The second ring of the rear end cover is in contact with the rear end opening of the outer shell. The fixing bolt passes through the second ring of the rear end cover and is screwed onto the rear end face of the outer shell, thereby fixing the rear end cover to the outer shell. The rear end of the first cylinder of the front end cover and the front end of the second cylinder of the rear end cover are in contact with each other.

[0009] Furthermore, the transition sleeve includes a third ring and a third cylinder. The second ring is fixedly sleeved on the outside of the front opening of the third cylinder. The third ring of the transition sleeve is located between the front opening of the outer shell and the first ring of the front cover, and the third ring of the transition sleeve is in contact with both the front opening of the outer shell and the first ring of the front cover. The third cylinder of the transition sleeve is located inside the front opening of the outer shell, and the third cylinder of the transition sleeve is located between the inner wall of the front opening of the outer shell and the outer wall of the first cylinder of the front cover, with the outer wall of the third cylinder of the transition sleeve in contact with the inner wall of the front opening of the outer shell. The fixing bolt passes through the first ring of the front cover and the third ring of the transition sleeve in sequence and is screwed onto the front face of the outer shell, thereby fixing the front cover, the transition sleeve and the outer shell together.

[0010] Furthermore, the piston includes a fourth ring and a fourth cylinder, with the fourth ring fixedly sleeved on the middle of the outer side of the fourth cylinder; the inner wall of the fourth cylinder of the piston contacts the outer wall of the first cylinder of the front end cover and the outer wall of the second cylinder of the rear end cover; four circular array of abutment grooves are provided inside the front end opening of the fourth cylinder of the piston, and the inner wall of the abutment groove is the second inclined surface; one outer end of each of the four claws is respectively engaged in the four abutment grooves of the piston, and the first inclined surface of the outer side of the claw slides in contact with the second inclined surface at the inner wall of the abutment groove.

[0011] Furthermore, a fifth ring is fixedly installed inside the rear opening of the outer casing. The inner wall of the fifth ring is in sliding contact with the outer wall of the fourth cylinder of the piston located behind the fourth ring, and the inner wall of the third cylinder of the transition sleeve is in sliding contact with the outer wall of the fourth cylinder of the piston located in front of the fourth ring.

[0012] Furthermore, the inner region of the outer shell between the fifth ring and the third cylinder of the transition sleeve is the movable cavity, and the fourth ring of the piston is located inside the movable cavity. The outer wall of the fourth ring of the piston is in sliding contact with the inner wall of the movable cavity. The inner region of the movable cavity in front of the fourth ring is the front oil cavity, and the inner region of the movable cavity behind the fourth ring is the rear oil cavity. The front oil cavity and the rear oil cavity are isolated by the fourth ring.

[0013] Furthermore, an oil inlet block is fixedly installed on the upper part of the outer side of the outer shell, and an oil inlet and an oil return port are provided on the oil inlet block; an oil inlet channel and an oil return channel are provided inside the outer shell, with the two ends of the oil inlet channel connected to the oil inlet on the oil inlet block and the rear oil cavity respectively, and the two ends of the oil return channel connected to the oil return port on the oil inlet block and the front oil cavity respectively.

[0014] Furthermore, a front guide copper sleeve is provided at the front opening of the first cylinder of the front cover. The front guide copper sleeve includes a sixth cylinder and a sixth ring. The sixth ring is fixedly sleeved on the outside of the front opening of the sixth cylinder and is located in front of the front opening of the first cylinder of the front cover. The sixth cylinder is inserted into the inside of the front opening of the first cylinder of the front cover. The front fixing ring presses the sixth ring into the front opening of the first cylinder of the front cover. The fixing bolt passes through the front fixing ring and is screwed to the front face of the front cover, thereby fixing the front guide copper sleeve on the front cover.

[0015] Furthermore, a rear guide copper sleeve is provided at the rear end opening of the second cylinder of the rear end cover. The rear guide copper sleeve includes a seventh cylinder and a seventh ring. The seventh ring is fixedly sleeved on the outside of the rear end opening of the seventh cylinder. The seventh ring is located on the rear side of the rear end opening of the second cylinder of the rear end cover. The seventh cylinder is inserted into the inside of the rear end opening of the second cylinder of the rear end cover. The rear fixing ring presses the seventh ring to the rear side of the rear end opening of the second cylinder of the rear end cover. The fixing bolt passes through the rear fixing ring and is screwed to the rear end face of the rear end cover, thereby fixing the rear guide copper sleeve on the rear end cover.

[0016] The beneficial effects of this utility model compared to the prior art are as follows:

[0017] (1) The drill rod is quickly clamped and released by four radially sliding jaws in conjunction with double inclined planes (first inclined plane and second inclined plane). The clamping force is evenly distributed to avoid slippage or eccentricity. The double straightening design of the front guide copper sleeve and the rear guide copper sleeve ensures that the drill rod is always coaxial with the outer shell axis during the clamping process, thus improving the positioning accuracy.

[0018] (2) The jaws adopt a square block structure with replaceable anti-slip patterned arc grooves, which can be used to adapt to drill rods of different diameters and are easy to replace; the outer shell is connected to the base pin through the fixed ear plate, which is convenient for overall disassembly or installation and can adapt to diverse operating scenarios.

[0019] (3) The independently designed oil inlet and return channels control the rear oil chamber and the front oil chamber respectively, pushing the piston to slide in both directions. The inclined plane transmission mechanism efficiently converts the axial motion into radial clamping force, which is sensitive and has low energy consumption.

[0020] (4) The first sealing ring embedded in the fifth ring and the second sealing ring embedded in the transition sleeve form a double sealing barrier to prevent hydraulic oil leakage; the guide copper sleeve is made of wear-resistant material to reduce the sliding friction between the piston and the claw and extend the service life of key components.

[0021] (5) The outer shell, front and rear end covers and transition sleeve are fixedly connected by bolts, which makes disassembly and assembly simple and facilitates the maintenance or replacement of internal components; the integrated oil inlet block integrates the oil circuit interface, which simplifies the external pipeline layout and reduces the space occupied by the equipment.

[0022] This invention significantly improves the efficiency, accuracy, and reliability of drill pipe clamping, making it suitable for high-intensity, high-frequency industrial operating environments. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the overall structure of this utility model. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the overall structure of this utility model. Figure 2 ;

[0026] Figure 3 This is a front view of the entire utility model;

[0027] Figure 4 yes Figure 3 AA section view in the middle;

[0028] Figure 5 yes Figure 4 BB section view in the middle;

[0029] Figure 6 This is a schematic diagram of the outer shell structure. Figure 1 ;

[0030] Figure 7 This is a schematic diagram of the outer shell structure. Figure 2 ;

[0031] Figure 8 This is a schematic diagram of the rear cover structure. Figure 1 ;

[0032] Figure 9 This is a schematic diagram of the rear cover structure. Figure 2 ;

[0033] Figure 10 This is a structural diagram of the front cover. Figure 1 ;

[0034] Figure 11 This is a structural diagram of the front cover. Figure 2 ;

[0035] Figure 12 This is a schematic diagram of the transition sleeve structure. Figure 1 ;

[0036] Figure 13 This is a schematic diagram of the transition sleeve structure. Figure 2 ;

[0037] Figure 14 This is a schematic diagram of the piston structure. Figure 1 ;

[0038] Figure 15 This is a schematic diagram of the piston structure. Figure 2 ;

[0039] Figure 16 This is a schematic diagram of the chuck's structure. Figure 1 ;

[0040] Figure 17 This is a schematic diagram of the chuck's structure. Figure 2 ;

[0041] Among them, 1 is the outer shell, 2 is the transition sleeve, 3 is the front end cover, 4 is the rear end cover, 5 is the claw, 6 is the piston, 7 is the first inclined surface, 8 is the second inclined surface, 9 is the fixed ear plate, 10 is the mounting base, 11 is the mounting pin, 12 is the first cylinder, 13 is the first ring, 14 is the second cylinder, 15 is the second ring, 16 is the fixing bolt, 17 is the third ring, 18 is the third cylinder, 19 is the fourth ring, 20 is the fourth cylinder, 21 is the abutment groove, 22 is the fifth ring, 23 is the first sealing ring, 24 is the second sealing ring, 25 is the front oil cavity, 26 is the rear oil cavity, 27 is the oil inlet block, 28 is the oil inlet channel, 29 is the oil return channel, 30 is the front guide copper sleeve, 31 is the front fixing ring, 32 is the rear guide copper sleeve, 33 is the rear fixing ring, 34 is the sliding groove, and 35 is the base. Detailed Implementation

[0042] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, this utility model will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it. The technical solution of this utility model will be described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0043] like Figure 1As shown in Figure 17, this utility model provides a four-jaw clamp, including a housing 1, which is fixedly mounted on a base 35. A transition sleeve 2 is fixedly mounted at the front opening of the housing 1, and a front end cover 3 is fixedly mounted on the front side of the transition sleeve 2. A rear end cover 4 is fixedly mounted at the rear opening of the housing 1. The rear end of the front end cover 3 and the front end of the rear end cover 4 are in contact with each other. Four sliding grooves 34 are provided between the contact surfaces of the front end cover 3 and the rear end cover 4. A claw 5 is slidably mounted inside each sliding groove 34 along the radial direction of the housing 1. A first inclined surface 7 is provided on the end face of the claw 5 away from the axis of the housing 1. A piston 6 is slidably mounted inside the housing 1, located between the housing 1 and the rear end cover 4. Four second inclined surfaces 8 are provided on the piston 6, and the four second inclined surfaces 8 on the piston 6 are in sliding contact with the first inclined surfaces 7 on the four claws 5 respectively.

[0044] The outer shell 1 is a cylindrical structure with openings on both the front and rear sides. A fixing lug 9 is fixedly installed on the left and right sides of the outer surface of the outer shell 1. The base 35 is a horizontally arranged square plate structure. A set of mounting seats 10 is fixedly installed on the left and right sides of the upper end face of the base 35. The two fixing lugs 9 on the outer shell 1 are respectively inserted into the two sets of mounting seats 10 on the upper end face of the base 35. A mounting pin 11 is inserted between the interlocking fixing lugs 9 and the mounting seats 10. A cotter pin is inserted into the end of the mounting pin 11, thereby fixing the outer shell 1 and the base 35 together.

[0045] The front cover 3 includes a first ring 13 and a first cylinder 12. The first ring 13 is fixedly sleeved on the outside of the front opening of the first cylinder 12. The first ring 13 of the front cover 3 is located in front of the front opening of the outer shell 1, and the first cylinder 12 of the front cover 3 is inserted into the inside of the front opening of the outer shell 1.

[0046] The rear end cover 4 includes a second ring 15 and a second cylinder 14. The second ring 15 is fixedly sleeved on the outside of the rear end opening of the second cylinder 14. The second ring 15 of the rear end cover 4 is located behind the rear end opening of the outer shell 1, and the second cylinder 14 of the rear end cover 4 is inserted into the inside of the rear end opening of the outer shell 1. The second ring 15 of the rear end cover 4 is in contact with the rear end opening of the outer shell 1. The fixing bolt 16 passes through the second ring 15 of the rear end cover 4 and is screwed onto the rear end face of the outer shell 1, thereby fixing the rear end cover 4 to the outer shell 1.

[0047] The rear end of the first cylinder 12 of the front cover 3 is in contact with the front end of the second cylinder 14 of the rear cover 4.

[0048] The sliding groove 34 is a square through hole. The claw 5 is a square block structure, and its outer walls slide in contact with the inner walls of the sliding groove 34. The distance between the front edge of the first inclined surface 7 on the outer side of the claw 5 and the axis of the outer shell 1 is greater than the distance between the rear edge and the axis of the outer shell 1. An arc groove is provided on the end face of the claw 5 near the axis of the outer shell 1, and the inner wall of the arc groove is provided with anti-slip patterns. A limiting block is fixedly provided on both sides of the end face of the claw 5 away from the axis of the outer shell 1, and the two limiting blocks ensure that the claw 5 will not fall out into the front cover 3 and the rear cover 4.

[0049] The transition sleeve 2 includes a third ring 17 and a third cylinder 18. The second ring 15 is fixedly sleeved on the outside of the front opening of the third cylinder 18. The third ring 17 of the transition sleeve 2 is located between the front opening of the outer shell 1 and the first ring 13 of the front cover 3, and the third ring 17 of the transition sleeve 2 is in contact with both the front opening of the outer shell 1 and the first ring 13 of the front cover 3. The third cylinder 18 of the transition sleeve 2 is located inside the front opening of the outer shell 1, and is located between the inner wall of the front opening of the outer shell 1 and the outer wall of the first cylinder 12 of the front cover 3, with the outer wall of the third cylinder 18 of the transition sleeve 2 in contact with the inner wall of the front opening of the outer shell 1. The fixing bolt 16 passes through the first ring 13 of the front cover 3 and the third ring 17 of the transition sleeve 2 in sequence and is screwed onto the front face of the outer shell 1, thereby fixing the front cover 3, the transition sleeve 2 and the outer shell 1 together.

[0050] The piston 6 includes a fourth ring 19 and a fourth cylinder 20. The fourth ring 19 is fixedly sleeved on the middle of the outer side of the fourth cylinder 20. The inner wall of the fourth cylinder 20 of the piston 6 is in contact with the outer wall of the first cylinder 12 of the front end cover 3 and the outer wall of the second cylinder 14 of the rear end cover 4. Four circular array of abutment grooves 21 are provided inside the front end opening of the fourth cylinder 20 of the piston 6. The abutment grooves 21 extend along the axial direction of the piston 6, and the front end of the abutment groove 21 is connected to the front end face of the fourth cylinder 20. The inner wall of the abutment groove 21 is the second inclined surface 8. The outer ends of the four claws 5 are respectively engaged in the four abutment grooves 21 of the piston 6. The first inclined surface 7 on the outer side of the claws 5 is in sliding contact with the second inclined surface 8 on the inner wall of the abutment groove 21.

[0051] A fifth ring 22 is fixedly disposed inside the rear opening of the outer casing 1, and a first sealing ring 23 is embedded in the inner cylindrical surface of the fifth ring 22. The inner wall of the fifth ring 22 is in sliding contact with the outer wall of the fourth cylinder 20 of the piston 6 located behind the fourth ring 19, and the first sealing ring 23 is in sliding contact with the outer wall of the fourth cylinder 20 of the piston 6 located behind the fourth ring 19.

[0052] A second sealing ring 24 is embedded in the rear end of the inner wall of the third cylinder 18 of the transition sleeve 2. The inner wall of the third cylinder 18 of the transition sleeve 2 is in sliding contact with the outer wall of the fourth cylinder 20 of the piston 6 located in front of the fourth ring 19, and the first sealing ring 23 is in sliding contact with the outer wall of the fourth cylinder 20 of the piston 6 located behind the fourth ring 19.

[0053] The internal region of the outer shell 1 between the fifth ring 22 and the third cylinder 18 of the transition sleeve 2 is a movable cavity. The fourth ring 19 of the piston 6 is located inside the movable cavity, and the outer wall of the fourth ring 19 of the piston 6 is in sliding contact with the inner wall of the movable cavity. The internal region of the movable cavity in front of the fourth ring 19 is the front oil chamber 25, and the internal region of the movable cavity behind the fourth ring 19 is the rear oil chamber 26. The front oil chamber 25 and the rear oil chamber 26 are isolated by the fourth ring 19.

[0054] An oil inlet block 27 is fixedly installed on the upper part of the outer side of the outer casing 1. An oil inlet port and an oil return port are provided on the oil inlet block 27. An oil inlet channel 28 and an oil return channel 29 are provided inside the outer casing 1. The two ends of the oil inlet channel 28 are respectively connected to the oil inlet port on the oil inlet block 27 and the rear oil cavity 26. The two ends of the oil return channel 29 are respectively connected to the oil return port on the oil inlet block 27 and the front oil cavity 25.

[0055] A front guide copper sleeve 30 is provided at the front opening of the first cylinder 12 of the front cover 3. The front guide copper sleeve 30 includes a sixth cylinder and a sixth ring. The sixth ring is fixedly sleeved on the outside of the front opening of the sixth cylinder and is located in front of the front opening of the first cylinder 12 of the front cover 3. The sixth cylinder is inserted into the inside of the front opening of the first cylinder 12 of the front cover 3. A front fixing ring 31 presses the sixth ring against the front opening of the first cylinder 12 of the front cover 3. A fixing bolt 16 passes through the front fixing ring 31 and is screwed onto the front face of the front cover 3, thereby fixing the front guide copper sleeve 30 on the front cover 3.

[0056] A rear guide copper sleeve 32 is provided at the rear end opening of the second cylinder 14 of the rear end cover 4. The rear guide copper sleeve 32 includes a seventh cylinder and a seventh ring. The seventh ring is fixedly sleeved on the outside of the rear end opening of the seventh cylinder and is located behind the rear end opening of the second cylinder 14 of the rear end cover 4. The seventh cylinder is inserted into the inside of the rear end opening of the second cylinder 14 of the rear end cover 4. A rear fixing ring 33 presses the seventh ring to the rear end opening of the second cylinder 14 of the rear end cover 4. A fixing bolt 16 passes through the rear fixing ring 33 and is screwed to the rear end face of the rear end cover 4, thereby fixing the rear guide copper sleeve 32 on the rear end cover 4.

[0057] The working principle of this utility model is as follows:

[0058] After the drill pipe extends into the housing 1, it is straightened by the front guide copper sleeve 30 and the rear guide copper sleeve 32. Then, oil is injected into the oil inlet of the oil inlet block 27. The oil enters the rear oil chamber 26 through the oil inlet channel 28. The pressure inside the rear oil chamber 26 increases, pushing the piston 6 to slide forward. Under the interaction of the first inclined surface 7 and the second inclined surface 8, the four jaws 5 are squeezed, causing the four jaws 5 to slide inward along the radial direction of the housing 1, thereby clamping the drill pipe.

[0059] When the drill pipe needs to be loosened, oil is injected into the return port of the oil block 27, and the oil return channel 29 enters into the front oil chamber 25. The pressure inside the front oil chamber 25 increases, pushing the piston 6 to slide backward. Under the interaction of the first inclined surface 7 and the second inclined surface 8, the pressure on the four jaws 5 is gradually released. In this way, the four jaws 5 can slide outward along the radial direction of the outer shell 1, thereby loosening the drill pipe.

[0060] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A four-jaw clamping pliers, characterized in that: Includes a housing (1), which is fixedly mounted on a base (35). A transition sleeve (2) is fixedly mounted at the front opening of the housing (1). A front end cover (3) is fixedly mounted on the front side of the transition sleeve (2). A rear end cover (4) is fixedly mounted at the rear opening of the housing (1). The rear end of the front end cover (3) and the front end of the rear end cover (4) are in contact with each other. Four sliding grooves (34) are provided between the contact surfaces of the front end cover (3) and the rear end cover (4). A claw (5) is slidably mounted inside each sliding groove (34) along the radial direction of the housing (1). A first inclined surface (7) is provided on the end face of the claw (5) away from the axis of the housing (1). A piston (6) is slidably mounted inside the housing (1). The piston (6) is located between the housing (1) and the rear end cover (4). Four second inclined surfaces (8) are provided on the piston (6). The four second inclined surfaces (8) on the piston (6) are in sliding contact with the first inclined surfaces (7) on the four claws (5).

2. The four-jaw clamping pliers according to claim 1, characterized in that: A fixed ear plate (9) is fixedly installed on the left and right sides of the outer side of the outer shell (1); a set of mounting seats (10) is fixedly installed on the left and right sides of the upper end face of the base (35). The two fixed ear plates (9) on the outer shell (1) are respectively inserted into the two sets of mounting seats (10) on the upper end face of the base (35). A mounting pin (11) is inserted between the fixed ear plates (9) and the mounting seats (10).

3. A four-jaw clamping pliers according to claim 1, characterized in that: The front end cover (3) includes a first ring (13) and a first cylinder (12). The first ring (13) is fixedly sleeved on the outside of the front end opening of the first cylinder (12). The first ring (13) of the front end cover (3) is located in front of the front end opening of the outer shell (1). The first cylinder (12) of the front end cover (3) is inserted into the inside of the front end opening of the outer shell (1). The rear end cover (4) includes a second ring (15) and a second cylinder (14). The second ring (15) is fixedly sleeved on the outside of the rear end opening of the second cylinder (14). The rear end cover (4) The second ring (15) of the rear end cover (4) is located behind the rear end opening of the outer shell (1), and the second cylinder (14) of the rear end cover (4) is inserted into the inner side of the rear end opening of the outer shell (1); the second ring (15) of the rear end cover (4) is in contact with the rear end opening of the outer shell (1); the fixing bolt (16) passes through the second ring (15) of the rear end cover (4) and is screwed to the rear end face of the outer shell (1), thereby fixing the rear end cover (4) and the outer shell (1) together; the rear end of the first cylinder (12) of the front end cover (3) is in contact with the front end of the second cylinder (14) of the rear end cover (4).

4. A four-jaw clamping pliers according to claim 3, characterized in that: The transition sleeve (2) includes a third ring (17) and a third cylinder (18). The second ring (15) is fixedly sleeved on the outside of the front opening of the third cylinder (18). The third ring (17) of the transition sleeve (2) is located between the front opening of the outer shell (1) and the first ring (13) of the front cover (3), and the third ring (17) of the transition sleeve (2) is in contact with both the front opening of the outer shell (1) and the first ring (13) of the front cover (3). The third cylinder (18) of the transition sleeve (2) is located on the outer shell (1). The front opening is located inside the outer wall of the outer shell (1) and the third cylinder (18) of the transition sleeve (2) is located between the inner wall of the front opening of the outer shell (1) and the outer wall of the first cylinder (12) of the front cover (3). The outer wall of the third cylinder (18) of the transition sleeve (2) is in contact with the inner wall of the front opening of the outer shell (1). The fixing bolt (16) passes through the first ring (13) of the front cover (3) and the third ring (17) of the transition sleeve (2) in sequence and is screwed to the front face of the outer shell (1), thereby fixing the front cover (3), the transition sleeve (2) and the outer shell (1) together.

5. A four-jaw clamping pliers according to claim 4, characterized in that: The piston (6) includes a fourth ring (19) and a fourth cylinder (20). The fourth ring (19) is fixedly sleeved on the middle of the outer side of the fourth cylinder (20). The inner wall of the fourth cylinder (20) of the piston (6) is in contact with the outer wall of the first cylinder (12) of the front end cover (3) and the outer wall of the second cylinder (14) of the rear end cover (4). Four circular array of abutment grooves (21) are provided inside the front end opening of the fourth cylinder (20) of the piston (6). The inner wall of the abutment groove (21) is the second inclined surface (8). The outer ends of the four claws (5) are respectively engaged in the four abutment grooves (21) of the piston (6). The first inclined surface (7) on the outer side of the claw (5) is in sliding contact with the second inclined surface (8) on the inner wall of the abutment groove (21).

6. A four-jaw clamping pliers according to claim 5, characterized in that: A fifth ring (22) is fixedly installed inside the rear opening of the outer shell (1). The inner wall of the fifth ring (22) is in sliding contact with the outer wall of the fourth cylinder (20) of the piston (6) located behind the fourth ring (19). The inner wall of the third cylinder (18) of the transition sleeve (2) is in sliding contact with the outer wall of the fourth cylinder (20) of the piston (6) located in front of the fourth ring (19).

7. A four-jaw clamping pliers according to claim 6, characterized in that: The inner region of the outer shell (1) between the fifth ring (22) and the third cylinder (18) of the transition sleeve (2) is the active cavity. The fourth ring (19) of the piston (6) is located inside the active cavity. The outer wall of the fourth ring (19) of the piston (6) slides in contact with the inner wall of the active cavity. The inner region of the active cavity in front of the fourth ring (19) is the front oil cavity (25), and the inner region of the active cavity behind the fourth ring (19) is the rear oil cavity (26). The front oil cavity (25) and the rear oil cavity (26) are isolated by the fourth ring (19).

8. A four-jaw clamping pliers according to claim 7, characterized in that: An oil inlet block (27) is fixedly provided on the upper side of the outer surface of the outer shell (1). An oil inlet and an oil return port are provided on the oil inlet block (27). An oil inlet channel (28) and an oil return channel (29) are provided inside the outer shell (1). The two ends of the oil inlet channel (28) are respectively connected to the oil inlet on the oil inlet block (27) and the rear oil cavity (26). The two ends of the oil return channel (29) are respectively connected to the oil return port on the oil inlet block (27) and the front oil cavity (25).

9. A four-jaw clamping pliers according to claim 3, characterized in that: A front guide copper sleeve (30) is provided at the front opening of the first cylinder (12) of the front cover (3). The front guide copper sleeve (30) includes a sixth cylinder and a sixth ring. The sixth ring is fixedly sleeved on the outside of the front opening of the sixth cylinder. The sixth ring is located in front of the front opening of the first cylinder (12) of the front cover (3). The sixth cylinder is inserted into the inside of the front opening of the first cylinder (12) of the front cover (3). The front fixing ring (31) presses the sixth ring onto the front opening of the first cylinder (12) of the front cover (3). The fixing bolt (16) passes through the front fixing ring (31) and is screwed to the front face of the front cover (3), thereby fixing the front guide copper sleeve (30) on the front cover (3).

10. A four-jaw clamping pliers according to claim 3, characterized in that: A rear guide copper sleeve (32) is provided at the rear end opening of the second cylinder (14) of the rear end cover (4). The rear guide copper sleeve (32) includes a seventh cylinder and a seventh ring. The seventh ring is fixedly sleeved on the outside of the rear end opening of the seventh cylinder. The seventh ring is located on the rear side of the rear end opening of the second cylinder (14) of the rear end cover (4). The seventh cylinder is inserted into the inside of the rear end opening of the second cylinder (14) of the rear end cover (4). The rear fixing ring (33) presses the seventh ring into the rear side of the rear end opening of the second cylinder (14) of the rear end cover (4). The fixing bolt (16) passes through the rear fixing ring (33) and screws into the rear end face of the rear end cover (4), thereby fixing the rear guide copper sleeve (32) on the rear end cover (4).

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