A power transmission device

Abstract

The application discloses a power transmission device, which comprises a rotating shaft, a long sliding cylinder, a connecting flange, an expansion coupling sleeve, a hollow shaft, a copper sleeve, a short sliding cylinder, a magnet disc, an adjusting mechanism, a power assembly, a bearing seat, a load and a base, wherein the power assembly, the adjusting mechanism, the bearing seat and the load are connected with the base, the rotating shaft is fixed in the axial position by two bearing seats and a clasp spring, the magnet disc, the long sliding cylinder, the copper sleeve, the connecting flange, the hollow shaft and the short sliding cylinder are connected with the rotating shaft, one end of the rotating shaft is connected with the load, the power assembly is not rigidly connected with the magnet disc, the power assembly transmits power to the magnet disc, the magnet disc can be axially moved on the rotating shaft and can be co-rotated with the shaft through the adjustment of the adjusting mechanism, and the torque transmission is realized. The application has the advantages of simple structure, stability and reliability, small power transmission loss, and smooth stepless speed regulation through the fine adjustment of the adjusting mechanism and the adjustment of the rotating speed of one side of the magnet disc.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power transmission, in particular to a power transmission device. BACKGROUND

[0002] The permanent magnet speed regulator is an energy-saving speed regulating device, which transmits the rotating speed and torque between the power shaft and the output shaft by the interaction of the conductor rotor and the magnet rotor, and can adjust the output rotating speed and torque by adjusting the air gap between the conductor rotor and the magnet rotor. Compared with the traditional gear box variable speed transmission, the permanent magnet speed regulator is more energy-saving and environmentally friendly, has obvious advantages such as simple and reliable, strong environmental adaptability, no electromagnetic interference, large speed regulating range, etc.

[0003] Most of the currently used disc type permanent magnet speed regulators have complex structure and no stall protection measures. The movement of the power transmission mechanism in the axial direction is usually completed by the contact friction between the wear-resistant ring and the load shaft. When the wear-resistant ring is consumed after long-time wear, a gap will be generated between the wear-resistant ring and the shaft, which makes the bearing installed therein unstable, greatly reduces the service life of the bearing, and the replacement of the bearing and the wear-resistant ring is not convenient, which brings inconvenience to the maintenance work. SUMMARY

[0004] The technical problem to be solved by the present application is the problem of too fast wear and tear of the bearing in the power transmission mechanism of the ordinary disc type permanent magnet speed regulator and the lack of stall protection measures. A power transmission device is provided, which adjusts the air gap and transmits power by using the characteristics of the cooperation between the ball and the ball groove on the shaft through the adjusting mechanism, and ensures that the magnet rotor has a certain movement space for automatically moving away from the conductor rotor when stalling to prevent the magnet rotor from overheating and demagnetizing. The present application has the advantages of simple structure, easy installation and high reliability.

[0005] The technical scheme of the present application is realized by the following power transmission device, which comprises a rotating shaft, a long sliding cylinder, a hollow shaft, a copper sleeve, a magnet disc, a short sliding cylinder, a power assembly, an adjusting mechanism and a load. One end of the rotating shaft is connected with the load, and the other end is connected with the magnet disc through the long sliding cylinder, the hollow shaft, the copper sleeve and the short sliding cylinder. The power assembly is arranged between the magnet disc and the rotating shaft with an active air gap. The adjusting mechanism is arranged on the rotating shaft and between the load and the magnet disc. The adjusting mechanism is connected with the long sliding cylinder and adjusts the axial position of the magnet disc on the rotating shaft. Two first ball grooves are arranged on the same plane on one end of the rotating shaft close to the magnet disc. Two first snap spring grooves are arranged on the other end of the rotating shaft close to the load, and the snap springs are arranged in the first snap spring grooves. The function of the snap springs is to limit the axial movement of the rotating shaft. The magnet disc is connected with the rotating shaft and can move axially. The long sliding cylinder is a sleeve with a flange. A counterbore is arranged on the flange end of the long sliding cylinder. Two second snap ring grooves are arranged on the other end of the long sliding cylinder away from the flange end, and the outer surface of the long sliding cylinder is smooth. Two rows of ball channels are arranged on the inner wall of the long sliding cylinder. The long cylinder balls can freely roll in the channels. The long cylinder balls are arranged in the long sliding cylinder from the end without the flange and are sealed by the long cylinder dustproof sealing ring. The two rows of long cylinder balls correspond to the positions of the first ball grooves. The long cylinder balls are uniformly arranged on the inner wall of the sleeve and protrude from the inner wall. The long sliding cylinder is arranged on the rotating shaft along the first ball grooves. The hollow shaft is connected with the long sliding cylinder through the first connecting piece, the second connecting piece and the third connecting piece. A stepped groove is arranged in the hollow shaft to accommodate the copper sleeve. The stepped groove is arranged on the flange end of the long sliding cylinder. A limiting piece is arranged on the end of the hollow shaft close to the magnet disc. Two second ball grooves are arranged on the same plane on the surface of the hollow shaft. The outer surface of the copper sleeve is in contact with the stepped groove of the hollow shaft. The length of the copper sleeve corresponds to the depth of the stepped groove. The inner surface of the copper sleeve is in contact with the rotating shaft, i.e. the rotating shaft slides in the copper sleeve. The short sliding cylinder is a sleeve with a flange. A counterbore is arranged on the flange end of the short sliding cylinder. The short sliding cylinder is fixed opposite to the magnet disc. Two rows of ball channels are arranged on the inner wall of the short sliding cylinder. The short cylinder balls can freely roll in the channels. The short cylinder balls are arranged in the short sliding cylinder from the end without the flange and are sealed by the short cylinder dustproof sealing ring. The positions of the short cylinder balls correspond to the positions of the two ball grooves. The short cylinder balls are uniformly arranged on the inner wall of the sleeve and protrude from the inner wall. The short sliding cylinder is sleeved on the hollow shaft along the second ball grooves. The short sliding cylinder can move axially along the hollow shaft and rotate with the hollow shaft. The axial movement of the short sliding cylinder can automatically move away the magnet disc carried by the short sliding cylinder when the load is locked, so as to prevent the device from overheating and demagnetizing the magnet.

[0006] The further limited technical scheme of the present application is:

[0007] The power assembly comprises a copper ring, a steel disc, an expansion coupling sleeve and a motor.

[0008] The adjusting mechanism comprises two bearings, an inner cylinder, bearing end covers, a handle, an outer cylinder and a wear-resistant packing ring.

[0009] The load is a centrifugal fan, and the torque transmission device further comprises two bearing seats and a base.

[0010] Compared with the prior art, the present application has the following beneficial effects:

[0011] The technical scheme of the present application realizes linear cooperation of the ball and the ball groove, so that the magnet disc can realize axial displacement and torque transmission, the overall friction resistance of the device is small, the power loss is small, the device is convenient to use, the bearing life can be greatly improved, and the movement of the magnet disc on the copper sleeve driven by the short sliding cylinder can avoid the situation that the temperature rises due to the unchanged air gap when the load is blocked, and the magnet demagnetization.

[0012] Compared with the wear-resistant ring made of polytetrafluoroethylene, the present application has small wear and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structural schematic view of the torque transmission device of the present application.

[0014] Figure 2 Enlarged view of the long slide cylinder AB of the present invention.

[0015] Figure 3 Structure diagram of the power shaft assembly of the present invention.

[0016] Figure 4 Structure diagram of the magnet disc of the present invention (already split).

[0017] Figure 5 Structure diagram of the adjusting mechanism of the present invention.

[0018] Figure 6 Structure diagram of the overall appearance of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the embodiments of the present invention. Figures 1-6 The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the embodiments of the present invention.

[0020] Obviously, the described embodiments are only some of the embodiments of the present invention, but not all the embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present invention, in addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present invention, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements, and for those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0023] Embodiment 1

[0024] The power transmission device provided in the embodiment, like the power transmission device provided in the embodiment, is characterized in that Figure 1 and Figure 6As shown, including the rotating shaft 1, long sliding cylinder 2, hollow shaft 3, copper sleeve 4, magnet disc 5, short sliding cylinder 6, power shaft assembly 7, adjusting mechanism 8, load 9, two bearing seats 10 and base 11.

[0025] Rotating shaft 1 end in copper sleeve 4, the other end connected to the load, that is, with the fan blades of centrifugal fan, rotating shaft 1 diameter maximum section between the bearing end surface of two bearing seats 10, and by the shaft spring into the corresponding first snap spring slot 1b fixed shaft position, while limiting the axial movement of the shaft, rotating shaft 1 is divided into two sections, the diameter from large to small: with hollow shaft 3 connected to a section, a section connected to the load 9.

[0026] As shown in Figure 1 and Figure 2 long sliding cylinder 2 is a long cylinder, one end with flange, flange end is provided with evenly distributed countersunk bolt hole, and the flange end does not contact with the magnet disc 5, its far from the flange end is provided with two second snap ring groove 2b containing outer snap spring, for the axial positioning of bearing 8a, long sliding cylinder 2 outer surface is smooth surface, its inner wall is provided with two rows of ball channel, long cylinder ball 2a can freely roll in the channel, long cylinder ball 2a is installed by the end without flange and sealed by screw with long cylinder dustproof sealing ring 2c, two rows of long cylinder ball 2a correspond to the position of the first ball groove 1a, long cylinder ball 2a is uniformly embedded in the sleeve inner wall and protrudes from the inner wall, long sliding cylinder 2 is sleeved on the rotating shaft 1 along the first ball groove 1a, which can move axially along the rotating shaft 1 and can also transmit torque to rotate with the rotating shaft 1.

[0027] Hollow shaft 3 one end inside opening ladder slot containing copper sleeve 4, its purpose is to facilitate the rotating shaft 1 more convenient for axial movement, reduce friction resistance, hollow shaft 3 the other end surface is provided with a section of thread, hollow shaft 3 surface is provided with two second ball groove 3a located in the same plane, for the axial movement and transmission of torque of short sliding cylinder 6, hollow shaft 3 and long sliding cylinder 2 is connected by first connecting piece 2d, second connecting piece 3d and third connecting piece 3b, third connecting piece 3b is provided as an expansion sleeve, second connecting piece 3d is provided as a disc type flange, hollow in the middle, the inner circle is in contact with the outer circle of expansion sleeve, and the flange is provided with evenly distributed countersunk bolt hole, first connecting piece 2d is also provided as a disc type flange, hollow in the middle, the inner circle is matched with the countersunk hole of long sliding cylinder 2 flange end, the outer circle is matched with the countersunk hole of second connecting piece 3d, hollow shaft 3 groove end is installed in the inner circle of expansion sleeve, second connecting piece 3d is installed in the outer circle of expansion sleeve, second connecting piece 3d and first connecting piece 2d are connected by bolts, first connecting piece 2d and long sliding cylinder 2 are also connected by bolts.

[0028] The copper sleeve 4 is a straight cylinder graphite copper sleeve, which is assembled in the stepped groove of the hollow shaft 3, and the length is the same as the groove depth, and the design purpose is to better perform axial displacement of the rotating shaft 1, and the graphite component can play a good lubricating effect.

[0029] The short sliding cylinder 6 is a sleeve with a flange, the flange end is provided with a countersunk bolt hole, the inner wall of the short sliding cylinder 6 is provided with two rows of short cylinder balls 6a which are closely arranged and can be circularly rolled respectively, a passage is opened in the inner wall, the short cylinder balls 6a are loaded from the end without the flange and are sealed by the short cylinder dustproof sealing ring 6b, the position corresponds to the two second ball grooves 3a, the short cylinder balls 6a are uniformly arranged in the inner wall of the sleeve and protrude from a part of the inner wall, the short sliding cylinder 6 is sleeved on the hollow shaft 3 along the second ball groove 3a, can move axially along the hollow shaft 3 and rotate with the hollow shaft 3, drives the magnet disc 5 to move axially, the axial displacement of one end is completed by the limiting piece 3c, and the axial displacement of the other end is completed by the connecting piece 3b, and the design purpose of this section of displacement is to consider that when the load is blocked, the copper ring 7a and the magnet disc 5 generate a slip speed difference for a long time, the temperature of the equipment rises, the permanent magnet 5b demagnetizes, and this section of displacement can make the load when blocked, the magnet disc 5 automatically moves away from the copper ring 7a, so as to increase the air gap and reduce the heat generated by the interaction.

[0030] As shown in Figure 4 , the magnet disc 5 is composed of a disc body 5a, a permanent magnet 5b and a cover plate 5c. The center of the disc body 5a is a through hole, and a plurality of uniformly distributed threaded holes are arranged around the center. The permanent magnet 5b is placed in the uniformly distributed recess of the disc body 5a. The cover plate 5c is used to press the permanent magnet 5b and is connected with the disc body 5a through bolts. The center of the disc body 5a is provided with a circular groove for accommodating the limiting piece 3c, and the groove surface is close to one end of the power assembly 7. The limiting piece 3c is designed as a locking nut, which is matched with the threaded end of the hollow shaft 3. The locking nut does not contact the disc body 5a. This structure design is to consider the overall aesthetics and the convenience of installation. The permanent magnet material in the magnet disc is a neodymium iron boron permanent magnet. Compared with other permanent magnets, it has strong magnetic attraction and strong magnetic force transmission, and is suitable for use as a permanent magnet material in a magnetic rotor. The neodymium iron boron permanent magnet is a known product on the market and can be directly purchased. Further, there are many manufacturers selling neodymium iron boron permanent magnets, and the technical solution is not limited to a specific manufacturer.

[0031] As shown in Figure 3 , the power shaft assembly 7 includes a copper ring 7a, a steel disc 7b, an expansion coupling 7c and a motor 7d. The motor 7d is connected and fixed with the base 11 through bolts. The copper ring 7a is connected with the steel disc 7b through bolts, and the surface of the copper ring 7a is opposite to the cover plate 6c of the magnet disc 6 and is provided with an active air gap distance of 5-15 mm. The steel disc 7b is connected and fixed with the motor shaft through the expansion coupling 7c. The expansion coupling 7c has large torque transmission and small space occupation, and can also limit the axial displacement of the steel disc 7b. Compared with the key connection, it is more convenient and simple.

[0032] As shown in Figure 5 and Figure 6 , the adjusting mechanism 8 includes two bearings 8a, an inner cylinder 8b, a bearing end cover 8c, a handle 8d, an outer cylinder 8e, and a wear-resistant packing ring 8f. The inner cylinder is cylindrical, with bearing seat holes at both ends, hollow in the middle. The outer rings of the two bearings 8a are installed in the bearing seat holes at both ends of the inner cylinder 8b, and the inner rings of the two bearings 8a are installed on the outer surface of the long sliding cylinder 2, aligned with the second clamping ring groove 2b. The axial movement of the bearings is limited by shaft clamps. Considering the characteristics of high speed and bearing a small amount of radial and axial load, the bearings 8a are deep groove ball bearings, which also connect the adjusting mechanism 8 to the long sliding cylinder 2. The bearing end cover 8c is connected to both ends of the inner cylinder 8b by bolts. The outer surface of the inner cylinder 8b at the end away from the long sliding cylinder 2 is provided with a threaded hole. The handle 8d is cylindrical, with a threaded hole at one end that matches the threaded hole on the outer surface of the inner cylinder 8b. The outer cylinder 8e is a flanged cylinder, with the flange connected to the base 11 by bolts. The inner cylinder 8b is located inside the outer cylinder 8e and has a gap with the inner wall of the outer cylinder 8. The two are in contact and move through the wear-resistant packing ring 8f. The design of the wear-resistant packing ring is to make the structure more compact and increase the moving friction of the inner cylinder 8b to prevent accidental movement. The outer cylinder 8e has a curved slot, and the handle 8d passes through the slot and can move in the slot. By moving the handle 8d in the slot, the inner cylinder is moved. The inner cylinder 8e moves the long sliding cylinder 2 through the bearings 8a, which ultimately moves the magnet disc 5, changing the air gap and adjusting the speed and torque of the rotating shaft 1.

[0033] As shown in Figure 6 , the two bearing seats 10 and the load 9 are fixed to the base 11 by bolts. The bearing seat 10 is a standard UCPH vertical bearing seat, and the load 9 is a centrifugal fan. Both the bearing seat 10 and the centrifugal fan are known products in the technical field and can be purchased directly. Further, there are many manufacturers selling centrifugal fans and standard UCPH bearing seats, and the technical solution does not limit the specific manufacturer.

[0034] The motor shaft and the rotating shaft 1 are on the same axis, which is to ensure that the bearing seat 10, the copper ring 7a, the magnet disc 5, and the load 9 are as concentric as possible to reduce the impact of different shaft errors on the stability of the equipment.

[0035] The use process of the embodiment is as follows:

[0036] Before use, the device is assembled first. First, place the base on a flat surface, and install the coil ring 8f into the groove of the outer cylinder 8e. The outer cylinder 8e is fixed on the bracket of the base 11 by bolts, and the curved through slot part is exposed upward. Second, pass the rotating shaft 1 through the outer cylinder 8e and the protrusion for fixing the outer cylinder 8e from left (the side of the motor protrusion) to right. When passing through the first bearing seat 10, the two shafts are sleeved with the circlip at the maximum diameter of the shaft, and continue to pass through the second bearing seat 10. Adjust the position of the bearing seat so that the bearing end faces of the bearing seat are respectively aligned with the circlip grooves 1b. At this time, the two shafts are pushed into the first circlip groove 1b with the circlip. Then, the two bearing seats 10 are fixed on the corresponding positions of the base 11 by bolts. Finally, the torque transmission device and the adjusting mechanism 8 are assembled. First, install the copper sleeve 4 in the stepped groove of the hollow shaft 3, and install the short sliding cylinder 6 along the second ball groove 3a into the hollow shaft 3. Note that the flange end is away from the groove end. Then, the long and short sliding cylinders are assembled separately. The magnet disc 5 is connected to the short sliding cylinder 6 by bolts and is installed on the threaded end of the hollow shaft 3 with a lock nut. Then, the inner ring of the expansion sleeve 3b is sleeved on the hollow shaft 3 and is aligned with the shaft end. The outer ring is installed into the second connecting piece 3d, and the screw on the expansion sleeve is tightened. Then, the first connecting piece 2d is connected to the second connecting piece 3d by bolts. Then, the long sliding cylinder 2 is connected to the first connecting piece 2d by bolts. A bearing end cover 8c is sleeved on the sliding cylinder 2. A bearing 8a is installed on the long sliding cylinder 2, with one end face aligned with the end face of the second circlip groove 2b. At this time, a shaft circlip is installed to fix the bearing 8a. Then, the long cylinder 8b is installed, with one end of the threaded hole on the surface located on the right side. After the first bearing 8c is completely pressed into the inner cylinder 8b, the second bearing 8a is installed and the same shaft circlip is installed. Then, the second bearing end cover 8c is installed, and the two bearing end covers 8c and the inner cylinder 8b are fixed by bolts. Then, the assembled torque transmission device and adjusting mechanism 8 are installed along one end of the first ball groove 1a of the rotating shaft 1, so that the rotating shaft 1 passes through the copper sleeve 4, and the outer ring of the inner cylinder 8b passes through the wear-resistant coil ring 8f. The threaded hole on the surface of the inner cylinder 8b is visible through the curved through slot of the outer cylinder 8e. At this time, the handle 8d is connected to the inner cylinder 8b by threading through the curved through slot. Next, the power assembly 7 is assembled. First, the copper ring 7a and the steel disc 7b are connected by bolts. Then, the expansion coupling sleeve 7c connects the steel disc 7b and the motor shaft. Finally, the motor 7d and the load 9 are installed on the base 11 by bolts. Turn on the power supply, adjust the handle 8d to control the air gap for speed regulation.

[0037] The above examples only illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made on the basis of the technical idea of the present application falls within the protection scope of the present application.

Claims

1. A power transmission device characterized by: The utility model relates to a kind of magnetic bearing, including rotating shaft (1), long sliding cylinder (2), hollow shaft (3), copper bush (4), magnet disc (5), short sliding cylinder (6), power component (7), adjusting mechanism (8) and load (9), rotating shaft (1) one end connects load, one end is connected magnet disc (5) by long sliding cylinder (2), hollow shaft (3), copper bush (4) and short sliding cylinder (6), power component (7) and magnet disc (5) between being equipped with movable air gap, adjusting mechanism (8) is located on rotating shaft (1), and it is located between load (9) and magnet disc (5), adjusting mechanism (8) is connected with long sliding cylinder (2), adjusting magnet disc (5) axial position on rotating shaft (1), rotating shaft (1) is set up two first ball grooves (1a) in the same plane in one end close to magnet disc (5), rotating shaft (1) is set up two first snap spring grooves (1b) of corresponding snap spring in one end close to load (9);Magnet disc (5) is connected between rotating shaft (1), and magnet disc (5) can be axially moved;Long sliding cylinder (2) is sleeve with flange, its flange end is equipped with counterbore, its end away from flange end is opened with two second snap ring grooves (2b) of containing outer snap spring, its outer surface is smooth surface, its inner wall is equipped with two rows of ball channels, long cylinder ball (2a) can be freely moved in channel, long cylinder ball (2a) is loaded by not flange end and is sealed by long cylinder dustproof sealing ring (2c), two rows of long cylinder ball (2a) and first ball groove (1a) position correspond, long cylinder ball (2a) is evenly arranged in long sliding cylinder inner wall and protrudes a part of inner wall, long sliding cylinder (2) is mounted on rotating shaft (1) along first ball groove (1a);Hollow shaft (3) is connected with long sliding cylinder (2) by first connecting piece (2d), second connecting piece (3b) and third connecting piece (3d), hollow shaft (3) one end inside is opened with the stepped groove of containing copper bush (4), and groove face is close to the flange end of long sliding cylinder (2), hollow shaft (3) is equipped with limiting piece (3c) on one side close to magnet disc (5), hollow shaft (3) surface is opened with two second ball grooves (3a) in the same plane;Copper bush (4) its outer surface contacts with the stepped groove of hollow shaft (3), and its length corresponds with stepped groove depth, its inner surface contacts with rotating shaft (1);Short sliding cylinder (6) is sleeve with flange, its flange end is equipped with counterbore, it is fixed opposite with magnet disc (5), short sliding cylinder (6) inner wall is equipped with two rows of ball channels, short cylinder ball (6a) can freely roll in channel, short cylinder ball (6a) is loaded by not flange end and is sealed by short cylinder dustproof sealing ring (6b), position and two second ball grooves (3a) position correspond, short cylinder ball (6a) is evenly arranged in short sliding cylinder inner wall and protrudes a part of inner wall, short sliding cylinder (6) is sleeved on hollow shaft (3) along second ball groove (3a); The power assembly (7) comprises a copper ring (7a), a steel disc (7b), an expansion coupling sleeve (7c) and a motor (7d), the copper ring (7a) is connected with the steel disc (7b), the copper ring (7a) is opposite to the magnet disc (5) and is provided with a movable air gap of 5-15 mm, the steel disc (7b) is connected and fixed with the motor shaft through the expansion coupling sleeve (7c); The power transmission device further comprises two bearing seats (10) and a base (11), the motor (7d), the two bearing seats (10) and the load (9) are fixed on the base (11), and the motor shaft and the rotating shaft (1) are on the same axis; The load (9) is a centrifugal fan.

2. A power transmitting device according to claim 1, characterised in that: The adjusting mechanism (8) comprises two bearings (8a), an inner cylinder (8b), bearing end covers (8c), a handle (8d), an outer cylinder (8e) and a wear-resistant packing ring (8f), the inner cylinder (8b) is in a cylindrical shape, is provided with bearing seat holes at two ends and is hollow in the middle; the two bearings (8a) are arranged in the bearing seat holes at two ends of the inner cylinder (8b), the inner rings of the two bearings (8a) are installed on the outer surface of the long sliding cylinder (2) and are aligned with the second snap ring groove (2b); the bearing end covers (8c) are connected with the two ends of the inner cylinder (8b) through bolts, and the outer surface of the inner cylinder (8b) is provided with a threaded hole at the end far from the long sliding cylinder (2); the handle (8d) is in a cylindrical shape, is provided with a threaded section at one end and is connected with the threaded hole in the outer surface of the inner cylinder (8b); the outer cylinder (8e) is in a flange cylindrical shape, the inner cylinder (8b) is located inside the outer cylinder (8e) and leaves a gap with the inner wall of the outer cylinder (8e), the two are in contact and move through the wear-resistant packing ring (8f), the outer cylinder (8e) is provided with a curved through slot, the handle (8d) passes through the through slot and can move in the slot, and drives the inner cylinder (8b) to axially expand and contract relative to the outer cylinder (8e).

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