CN113997179A

CN113997179A - Mechanical maintenance equipment of polishing

Info

Publication number: CN113997179A
Application number: CN202111313842.9A
Authority: CN
Inventors: 温秀梅
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-11-08
Filing date: 2021-11-08
Publication date: 2022-02-01
Anticipated expiration: 2041-11-08
Also published as: CN113997179B

Abstract

The invention discloses mechanical maintenance polishing equipment, which relates to the technical field of mechanical maintenance, and comprises a support frame and a polishing platform arranged at the upper end of the support frame, wherein the polishing platform is in a semi-enclosed box-shaped structure; a motor is arranged in the polishing table, a polishing disc is arranged at the output end of the motor, a top plate is arranged at one side, close to the motor, of the upper end of the polishing table, a transparent cover plate is arranged at one side, close to the polishing disc, of the upper end of the polishing table, and one side of the transparent cover plate is rotatably connected to the top plate through a hinge; the other side of the transparent cover plate passes through the clamping protrusion, the end part of the clamping protrusion is provided with a clamping ball, and the upper end of the side wall of the polishing table is provided with a clamping groove matched with the clamping ball. The polishing equipment provided by the invention improves the polishing stability of the maintenance device and the cleanliness of the polishing platform on the one hand, and improves the polishing quality and effect; on the other hand, the safety of the polishing device is improved, and the probability of polishing safety accidents is avoided.

Description

Mechanical maintenance equipment of polishing

Technical Field

The invention belongs to the technical field of mechanical maintenance, and particularly relates to mechanical maintenance polishing equipment.

Background

Sanding, which is one of surface modification techniques, generally refers to a processing method for changing physical properties of a material surface by friction with the aid of a rough object (sand paper or the like containing particles of relatively high hardness) mainly for the purpose of obtaining a specific surface roughness.

At present often need polish the device of maintenance in the mechanical maintenance process, and present polishing is mostly polished on the polisher through artifical handheld device, the phenomenon of arm shake appears easily during manual operation, the stability of polishing is not enough, lead to the quality reduction of polishing of device, and the security that artifical handheld device was polished is relatively poor, and simultaneously, the crushed aggregates when polishing splashes and is difficult for collecting the influence effect of polishing, we provide a mechanical maintenance equipment of polishing for this reason.

Disclosure of Invention

The invention aims to provide mechanical maintenance polishing equipment aiming at the problems that most of the existing polishing equipment is easy to shake arms when being manually operated, the polishing stability is insufficient, the polishing quality of devices is reduced, and the polishing safety of manually holding the devices is poor.

The invention is realized by the following technical scheme: a mechanical maintenance polishing device comprises a support frame and a polishing platform arranged at the upper end of the support frame, wherein the polishing platform is of a semi-enclosed box-shaped structure; a motor is arranged in the polishing table, a polishing disc is arranged at the output end of the motor, a top plate is arranged at one side, close to the motor, of the upper end of the polishing table, a transparent cover plate is arranged at one side, close to the polishing disc, of the upper end of the polishing table, and one side of the transparent cover plate is rotatably connected to the top plate through a hinge; the other side of the transparent cover plate passes through a clamping protrusion, a clamping ball is arranged at the end part of the clamping protrusion, and a clamping groove matched with the clamping ball is arranged at the upper end of the side wall of the grinding table;

the outer wall of one side, close to the polishing piece, of the polishing platform is provided with a rotating mechanism, the rotating mechanism is provided with a first connecting rod, the end part of the first connecting rod is provided with a limiting sleeve, a second connecting rod is transversely arranged in the limiting sleeve in a sliding manner, and the upper end and the lower end of the limiting sleeve are provided with limiting switch assemblies for fixing the second connecting rod;

a rotating shaft is arranged at one end, away from the limiting sleeve, of the second connecting rod, a fixing ring is fixedly connected to the end portion of the rotating shaft, a polishing rod is slidably connected to the interior of the fixing ring, a handle is arranged at the outer side end of the polishing rod, and a fixing mechanism for fixing a maintenance device is arranged at the inner side end of the polishing rod;

the fixing mechanism comprises a fixing disc, one surface of the fixing disc is fixedly connected to the end part of the grinding rod, the other surface of the fixing disc is provided with a fixing groove, the outer side wall of the fixing groove is provided with a plurality of threaded rods, the threaded rods are in threaded connection with the outer side wall of the fixing groove, the inner side ends of the threaded rods are rotatably connected with a clamping plate through bearings, and the outer side ends of the threaded rods are provided with fixing buttons; .

Preferably, slewing mechanism includes knob, screw rod, baffle and connecting axle, the one end fixed connection of connecting axle is on the lateral wall of platform of polishing, the other end of connecting axle is equipped with the screw hole, the baffle sets up on the lateral surface of connecting axle, the one end that stop collar was kept away from to the head rod is equipped with the connecting hole, the head rod cup joints the tip at the connecting axle through the connecting hole, a side of knob is equipped with outstanding screw rod, the knob passes through screw rod threaded connection in the screw hole of connecting axle to it is fixed with it with head rod clamp between knob and baffle.

Preferably, the opposite side surfaces of the baffle plate and the knob are respectively provided with a tooth protrusion, and the tooth protrusions on the baffle plate and the knob are opposite in direction, so that the first connecting rod is conveniently and stably fixed on the rotating mechanism.

Preferably, the limit switch subassembly includes the limiting plate, the up end and the lower terminal surface of stop collar all are equipped with the barrel groove, the barrel inslot is equipped with the pivot, the lower terminal surface fixedly connected with adapter sleeve of limiting plate, the adapter sleeve rotates and connects on the limiting plate, the up end and the lower terminal surface of second connecting rod all are equipped with the spacing groove, the one end joint of limiting plate is in the spacing inslot of second connecting rod, the other end of limiting plate extends to the outside of stop collar, pass through spring coupling between the extension end of limiting plate and the lateral surface of stop collar.

Preferably, the limiting plate is a flat obtuse-angle bending plate, and the width of the limiting plate is smaller than that of the bucket groove.

Preferably, the lower end surface of the polishing platform is provided with an aggregate funnel below the polishing sheet, the lower end of the aggregate funnel is provided with a discharge pipe, and the discharge pipe is provided with a discharge valve.

Preferably, the clamping ball is composed of two hemispherical elastic pieces, the maximum distance between the two hemispherical elastic pieces is greater than the width of the clamping groove, and the minimum distance between the two hemispherical elastic pieces is smaller than the width of the clamping groove; when the transparent cover plate is closed, the lowest ends of the two hemispherical elastic pieces are inserted into the clamping grooves, and the width of each clamping groove is smaller than the maximum distance between the two hemispherical elastic pieces, so that the two hemispherical elastic pieces are drawn together in the descending process, the outer side walls of the two hemispherical elastic pieces are tightly clamped on the two side walls of the clamping grooves, and the transparent cover plate is clamped on the polishing table.

Preferably, the support frame comprises a bottom plate and a support column, the support column is fixedly connected to the upper end face of the bottom plate, and the bottom plate is fixed on the ground through a fixing screw.

Preferably, the diameter of the polishing rod is smaller than the inner diameter of the fixing ring, a fastening bolt is arranged on the outer side of the fixing ring, the fastening bolt is in threaded connection with the outer wall of the fixing ring, and the lower end of the fastening bolt penetrates through the outer wall of the fixing ring; when the polishing rod is used, the polishing rod can rotate in the fixing ring, so that the fixed maintenance device can be rotationally polished, and the polishing rod can also be fixed to stably polish the maintenance device.

Compared with the prior art, the invention has the following advantages:

1. when the device is used, a maintenance device needing to be polished is fixed on the fixed disc of the polishing rod, the positions of the first connecting rod and the second connecting rod are adjusted to enable the polishing rod to be at a proper polishing height, the motor is started to drive the polishing disc to rotate, a user holds the handle of the polishing rod by hand, the maintenance device on the polishing rod is aligned with the polishing disc to be polished, the polishing stability is higher through the support of the first connecting rod and the second connecting rod, the phenomenon that the device is easy to shake when the user holds the device by hand is avoided, and the polishing effect and the quality of the device are improved.

2. According to the invention, the grinding rod is used for fixing the maintenance device, so that the phenomenon that a safety accident is easy to occur when a user holds the device for grinding is avoided.

3. According to the invention, the transparent cover plate capable of being opened in a rotating mode is arranged at the upper end of the polishing table, and the transparent cover plate can be clamped on the side surface of the polishing table when in use, so that the polishing table forms a semi-enclosed box body, crushed materials generated during polishing can not splash, and the transparent cover plate is convenient for a user to observe the polishing condition of a device.

4. According to the invention, the material collecting funnel is arranged on the lower end surface of the polishing table, so that the crushed materials generated during polishing of the device can be conveniently collected, the cleanliness of the polishing table is improved, and the influence of the crushed materials on the polishing quality of the device is avoided.

In conclusion, the polishing equipment provided by the invention improves the polishing stability of the maintenance device and the cleanliness of the polishing platform, and improves the polishing quality and effect; on the other hand, the safety of the polishing device is improved, and the probability of polishing safety accidents is avoided.

Drawings

FIG. 1 is a schematic structural view of a mechanical maintenance polishing apparatus;

FIG. 2 is a schematic view of an open state of a mechanical maintenance polishing apparatus;

FIG. 3 is a schematic diagram of the structure of a first connecting rod and a second connecting rod of a mechanical maintenance polishing apparatus;

FIG. 4 is a block diagram of a limit switch assembly of a mechanical maintenance polishing apparatus;

FIG. 5 is a block diagram of a grinding rod of a mechanical maintenance grinding apparatus;

FIG. 6 is a block diagram of a rotating mechanism of a mechanical maintenance polishing apparatus;

fig. 7 is a top view of a clamp boss of a mechanical maintenance grinding apparatus.

Reference numbers in the figures: 1. a base plate; 2. a support pillar; 3. a polishing table; 4. a motor; 5. a top plate; 6. a transparent cover plate; 61. clamping convex; 62. blocking the ball; 63. a card slot; 7. a hinge; 8. grinding the sheets; 9. a rotating mechanism; 91. a knob; 92. a screw; 93. a baffle plate; 94. a connecting shaft; 10. a first connecting rod; 101. connecting holes; 11. a limiting sleeve; 111. a limiting plate; 112. a through groove; 113. a spring; 114. a rotating shaft; 115. connecting sleeves; 12. a second connecting rod; 121. a limiting groove; 122. a fixing ring; 123. fastening a bolt; 124. a rotating shaft; 13. an aggregate funnel; 14. grinding the rod; 141. a handle; 142. fixing the disc; 143. a splint; 144. a threaded rod; 145. fixing grooves; 146. and fixing the button.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

Referring to fig. 1-7, a mechanical maintenance polishing device comprises a support frame and a polishing platform 3 arranged at the upper end of the support frame, wherein the polishing platform 3 is in a semi-enclosed box-shaped structure; a motor 4 is arranged in the polishing platform 3, a polishing disc 8 is arranged at the output end of the motor 4, a top plate 5 is arranged at one side, close to the motor 4, of the upper end of the polishing platform 3, a transparent cover plate 6 is arranged at one side, close to the polishing disc 8, of the upper end of the polishing platform 3, and one side of the transparent cover plate 6 is rotatably connected to the top plate 5 through a hinge 7; the other side of the transparent cover plate 6 passes through a clamping protrusion 61, a clamping ball 62 is arranged at the end part of the clamping protrusion 61, and a clamping groove 63 matched with the clamping ball 62 is arranged at the upper end of the side wall of the polishing table 3;

the outer wall of one side, close to the polishing sheet 8, of the polishing table 3 is provided with a rotating mechanism 9, the rotating mechanism 9 is provided with a first connecting rod 10, the end part of the first connecting rod 10 is provided with a limiting sleeve 11, a second connecting rod 12 is transversely arranged in the limiting sleeve 11 in a sliding manner, and the upper end and the lower end of the limiting sleeve 11 are provided with limiting switch assemblies for fixing the second connecting rod 12;

a rotating shaft 124 is arranged at one end, away from the limiting sleeve 11, of the second connecting rod 12, a fixing ring 122 is fixedly connected to the end portion of the rotating shaft 124, a polishing rod 14 is slidably connected to the inside of the fixing ring 122, a handle 141 is arranged at the outer side end of the polishing rod 14, and a fixing mechanism for fixing a maintenance device is arranged at the inner side end of the polishing rod 14;

the fixing mechanism comprises a fixing disc 142, one surface of the fixing disc 142 is fixedly connected to the end portion of the grinding rod 14, a fixing groove 145 is formed in the other surface of the fixing disc 142, a plurality of threaded rods 144 are arranged on the outer side wall of the fixing groove 145, the threaded rods 144 are in threaded connection with the outer side wall of the fixing groove 145, the inner side ends of the threaded rods 144 are rotatably connected with a clamping plate 143 through bearings, and fixing buttons 146 are arranged on the outer side ends of the threaded rods 144.

The rotating mechanism 9 comprises a knob 91, a screw 92, a baffle 93 and a connecting shaft 94, one end of the connecting shaft 94 is fixedly connected to the side wall of the grinding table 3, the other end of the connecting shaft 94 is provided with a threaded hole, the baffle 93 is arranged on the outer side surface of the connecting shaft 94, one end, far away from the limiting sleeve 11, of the first connecting rod 10 is provided with a connecting hole 101, the first connecting rod 10 is sleeved at the end part of the connecting shaft 94 through the connecting hole 101, one side surface of the knob 91 is provided with the protruding screw 92, the knob 91 is in threaded hole of the connecting shaft 94 through the screw 92, and the first connecting rod 10 is clamped between the knob 91 and the baffle 93 and is fixed.

The opposite side surfaces of the baffle plate 93 and the knob 91 are respectively provided with a tooth protrusion, and the tooth protrusions on the baffle plate 93 and the knob 91 are opposite in direction, so that the first connecting rod 10 is conveniently and stably fixed on the rotating mechanism 9, and the supporting position of the first connecting rod 10 can be adjusted.

The limit switch assembly comprises a limit plate 111, through grooves 112 are formed in the upper end face and the lower end face of the limit sleeve 11, a rotating shaft 114 is arranged in the through grooves 112, a connecting sleeve 115 is fixedly connected to the lower end face of the limit plate 111, the connecting sleeve 115 is rotatably connected to the limit plate 111, limit grooves 121 are formed in the upper end face and the lower end face of the second connecting rod 12, one end of the limit plate 111 is clamped in the limit groove 121 of the second connecting rod 12, the other end of the limit plate 111 extends to the outer side of the limit sleeve 11, and the extending end of the limit plate 111 is connected with the outer side face of the limit sleeve 11 through a spring 113; during the use, can press the extension end of 11 upper ends of stop collar and the limiting plate 111 of lower extreme, make limiting plate 111 block break away from limiting groove 121 at limiting groove 121 one end perk, remove second connecting rod 12 again, make the tip of second connecting rod 12 remove and polish the piece in the coplanar, loosen limiting plate 111, limiting plate 111's extension end perk under spring 113's elasticity, thereby make limiting plate 111's the other end card once more in limiting groove 121, fixed second connecting rod 12 makes things convenient for polishing of device.

The limiting plate 111 is a flat obtuse-angle bending plate, and the width of the limiting plate 111 is smaller than that of the through groove 112, so that the limiting plate 111 can move conveniently.

The clamping ball 62 is composed of two hemispherical elastic pieces, the clamping groove 63 is a rectangular groove, the maximum distance between the two hemispherical elastic pieces is greater than the width of the clamping groove 63, and the minimum distance between the two hemispherical elastic pieces is smaller than the width of the clamping groove 63; when the transparent cover plate 6 is closed, the lowest ends of the two hemispherical elastic pieces are inserted into the clamping grooves 63, and the width of the clamping grooves 63 is smaller than the maximum distance between the two hemispherical elastic pieces, so that the two hemispherical elastic pieces are drawn together in the descending process, the outer side walls of the two hemispherical elastic pieces are tightly clamped on the two side walls of the clamping grooves 63, and the transparent cover plate 6 is clamped on the polishing table 3.

The support frame includes bottom plate 1 and support column 2, and support column 2 fixed connection is at the up end of bottom plate 1, and bottom plate 1 passes through the fixed screw to be fixed subaerial.

The diameter of the grinding rod 14 is smaller than the inner diameter of the fixing ring 122, a fastening bolt 123 is arranged on the outer side of the fixing ring 122, the fastening bolt 123 is in threaded connection with the outer wall of the fixing ring 122, and the lower end of the fastening bolt 123 penetrates through the outer wall of the fixing ring 122; when in use, the polishing rod 14 can rotate in the fixing ring 122 to rotationally polish fixed maintenance devices, and the polishing rod 14 can also be fixed to stably polish the maintenance devices.

Example two

The embodiment is that the following technical solutions are added on the basis of the first embodiment, and the difference is that: the lower end surface of the grinding table 3 is provided with an aggregate funnel 13 below the grinding sheet 8, the lower end of the aggregate funnel 13 is provided with a blanking pipe, and the blanking pipe is provided with a blanking valve.

Through being equipped with the funnel 13 that gathers materials at the lower terminal surface of platform 3 of polishing, the crushed aggregates that produces when conveniently polishing the device is collected and is handled, improves the cleanliness on the platform 3 of polishing, avoids crushed aggregates to influence the quality of polishing of device.

The working principle is as follows: when the polishing device is used, a maintenance device to be polished is fixed on the fixed disc 142 of the polishing rod 14, the positions of the first connecting rod 10 and the second connecting rod 12 are adjusted, the polishing rod 14 is located at a proper polishing height, the motor 4 is started to drive the polishing disc 8 to rotate, a user holds the handle 141 of the polishing rod 14 by hand, the maintenance device on the polishing rod 14 is aligned with the polishing disc 8 to be polished, the polishing device is supported by the first connecting rod 10 and the second connecting rod 12, the polishing stability is higher, the phenomenon that the device is easy to shake when the user holds the device by hand is avoided, and the polishing effect and the quality of the device are improved. According to the invention, the grinding rod 14 is used for fixing the maintenance device, so that the phenomenon that a safety accident is easy to occur when a user holds the device for grinding is avoided. According to the invention, the transparent cover plate 6 capable of being opened in a rotating mode is arranged at the upper end of the polishing table 3, and the transparent cover plate 6 can be clamped on the side face of the polishing table 3 in use, so that the polishing table 3 forms a semi-enclosed box body, crushed aggregates generated in polishing can not splash, and the transparent cover plate is convenient for a user to observe the polishing condition of a device.

In conclusion, the polishing equipment provided by the invention improves the polishing stability of the maintenance device and the cleanliness of the polishing table 3, and improves the polishing quality and effect; on the other hand, the safety of the polishing device is improved, and the probability of polishing safety accidents is avoided.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation. The use of the phrase "comprising one of the elements does not exclude the presence of other like elements in the process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The mechanical maintenance polishing equipment comprises a support frame and a polishing platform (3) arranged at the upper end of the support frame, wherein the polishing platform (3) is of a semi-enclosed box-shaped structure; the method is characterized in that: a motor (4) is arranged in the grinding table (3), a grinding sheet (8) is arranged at the output end of the motor (4), a top plate (5) is arranged at one side, close to the motor (4), of the upper end of the grinding table (3), a transparent cover plate (6) is arranged at one side, close to the grinding sheet (8), of the upper end of the grinding table (3), and one side of the transparent cover plate (6) is rotatably connected to the top plate (5) through a hinge (7); the other side of the transparent cover plate (6) passes through a clamping protrusion (61), a clamping ball (62) is arranged at the end part of the clamping protrusion (61), and a clamping groove (63) matched with the clamping ball (62) is arranged at the upper end of the side wall of the grinding table (3);

the outer wall of one side, close to the polishing disc (8), of the polishing table (3) is provided with a rotating mechanism (9), the rotating mechanism (9) is provided with a first connecting rod (10), the end part of the first connecting rod (10) is provided with a limiting sleeve (11), a second connecting rod (12) is arranged in the limiting sleeve (11) in a transverse sliding mode, and the upper end and the lower end of the limiting sleeve (11) are provided with limiting switch assemblies for fixing the second connecting rod (12);

a rotating shaft (124) is arranged at one end, away from the limiting sleeve (11), of the second connecting rod (12), a fixing ring (122) is fixedly connected to the end portion of the rotating shaft (124), a polishing rod (14) is slidably connected to the inside of the fixing ring (122), a handle (141) is arranged at the outer side end of the polishing rod (14), and a fixing mechanism for fixing a maintenance device is arranged at the inner side end of the polishing rod (14);

fixed establishment includes fixed disk (142), fixed disk (142) one side fixed connection is at the tip of pole (14) of polishing, the another side of fixed disk (142) is equipped with fixed slot (145), be equipped with a plurality of threaded rod (144) on the lateral wall of fixed slot (145), threaded rod (144) threaded connection is on the lateral wall of fixed slot (145), the medial extremity of threaded rod (144) rotates through the bearing and is connected with splint (143), the outside end of threaded rod (144) is equipped with fixed button (146).

2. A mechanical service sharpening device according to claim 1, characterized in that the turning mechanism (9) comprises a knob (91), a screw (92), a shutter (93) and a connecting shaft (94);

one end fixed connection of connecting axle (94) is on the lateral wall of platform (3) of polishing, the other end of connecting axle (94) is equipped with the screw hole, baffle (93) set up on the lateral surface of connecting axle (94), the one end that stop collar (11) were kept away from in head rod (10) is equipped with connecting hole (101), head rod (10) cup joint the tip at connecting axle (94) through connecting hole (101), a side of knob (91) is equipped with outstanding screw rod (92), knob (91) pass through screw rod (92) threaded connection in the screw hole of connecting axle (94) to press from both sides head rod (10) and fix it between knob (91) and baffle (93).

3. A mechanical service sharpening device according to claim 2, characterized in that the baffle (93) and the knob (91) are provided with teeth on opposite sides, the teeth on the baffle (93) and the knob (91) being in opposite directions.

4. The mechanical maintenance equipment of polishing of claim 3, characterized in that, the limit switch subassembly includes limiting plate (111), the up end and the lower terminal surface of stop collar (11) all are equipped with logical groove (112), it is equipped with pivot (114) in logical groove (112), the lower terminal surface fixedly connected with adapter sleeve (115) of limiting plate (111), adapter sleeve (115) rotate to be connected on limiting plate (111), the up end and the lower terminal surface of second connecting rod (12) all are equipped with spacing groove (121), the one end joint of limiting plate (111) is in spacing groove (121) of second connecting rod (12), the other end of limiting plate (111) extends to the outside of stop collar (11), connect through spring (113) between the extension end of limiting plate (111) and the lateral surface of stop collar (11).

5. A mechanical service grinding apparatus according to claim 4, characterized in that the limiting plate (111) is a flat obtuse angle bending plate, and the width of the limiting plate (111) is smaller than the width of the through groove (112).

6. A mechanical maintenance grinding device according to claim 5, characterized in that the lower end surface of the grinding table (3) is provided with a collecting hopper (13) below the grinding disc (8), the lower end of the collecting hopper (13) is provided with a discharge pipe, and the discharge pipe is provided with a discharge valve.

7. A mechanical service grinding apparatus according to any of claims 1-6, characterized in that the clamping ball (62) consists of two hemispherical spring segments, the outer maximum distance between the two hemispherical spring segments being larger than the width of the clamping groove (63), and the outer minimum distance between the two hemispherical spring segments being smaller than the width of the clamping groove (63).

8. A mechanical maintenance grinding device according to claim 7, characterized in that the support frame comprises a bottom plate (1) and a support column (2), the support column (2) is fixedly connected to the upper end face of the bottom plate (1), and the bottom plate (1) is fixed on the ground through fixing screws.

9. A mechanical service sanding device according to claim 8, wherein the sanding rod (14) has a diameter smaller than the inner diameter of the stationary ring (122), the stationary ring (122) is provided on its outside with fastening bolts (123), the fastening bolts (123) are screwed to the outer wall of the stationary ring (122), and the lower ends of the fastening bolts (123) penetrate the outer wall of the stationary ring (122).