CN212837828U

CN212837828U - Mountain tunnel passes through broken device of preventing collapsing of fault

Info

Publication number: CN212837828U
Application number: CN202021946180.XU
Authority: CN
Inventors: 杨天羽; 唐解; 王翰林; 李立国; 杨涛; 李梦豪; 庞宇哲; 白云涧; 苗海涛
Original assignee: CCCC Tunnel Engineering Co Ltd
Current assignee: CCCC Tunnel Engineering Co Ltd
Priority date: 2020-09-08
Filing date: 2020-09-08
Publication date: 2021-03-30
Anticipated expiration: 2030-09-08

Abstract

The utility model discloses a mountain tunnel passes through broken device of preventing collapsing of fault, including the preliminary bracing device, the preliminary bracing device includes upper portion steel bow member, fixes at the tunnel invert support of the inboard bottom of upper portion steel bow member and fixes the well septum frame between the inboard top of upper portion steel bow member and tunnel invert support top, the both sides of well septum frame all are provided with the interim strengthening mechanism of multiunit adjustable. The utility model relates to a rationally, the cooperation setting of the interim strengthening mechanism of multiunit adjustable and intermediate frame can carry out the outrigger to the both sides and the intermediate position of upper portion steel bow member, improves its preliminary stage temporary support stability, reduces the risk that takes place to collapse in the tunnel cave body initial stage construction, and can adjust the height and the gradient of roof according to actual need for can support different inclination radians and the upper portion steel bow member of height, improve its application scope, be favorable to the use.

Description

Mountain tunnel passes through broken device of preventing collapsing of fault

Technical Field

The utility model relates to a tunnel construction technical field especially relates to a massif tunnel passes through broken anti-collapse device of fault.

Background

Along with the increase of road traffic volume and the development of capital construction engineering, mountain tunnels are more and more common, when tunnels penetrating fault fracture zones of mountain tunnels are excavated mostly by adopting a step method in the prior art, the excavation difficulty is very high, and the phenomenon of large-area subsidence and collapse of vault is easily caused in the excavation process, so that the convenience of preventing collapse on a fracture layer mainly refers to the early-stage support collapse prevention, the construction safety of personnel is ensured, the phenomenon can be avoided through reinforcement treatment in some aspects such as grouting and the like after construction, and the excavated tunnels need to be temporarily reinforced and supported in the initial stage of excavation construction.

To this end, upon retrieval, the authorization post number: CN208456616U discloses a primary support and mid-partition reinforced support system for a tunnel passing through a fault fracture zone, which comprises a full-section support system and a mid-partition temporary support structure, wherein the mid-partition temporary support structure is positioned between a left pilot tunnel and a right pilot tunnel in a tunnel body at the upper part of the tunnel; the left and right sides bottom of the tunnel upper portion hole body is provided with a lateral part underbeam respectively, the interim supporting construction of mid-board includes one mid-board underbeam, a plurality of mid-board and mid-board longitudinal connection structure, the device construction is simple and convenient and excellent in use effect, full section support system and the interim supporting construction of mid-board all support through the underbeam and connect the wholeness support system firm as an organic whole formation structure, and only set up the stability that the vault can effectively be guaranteed to the interim supporting construction of mid-board in the tunnel upper portion hole simultaneously, the construction is simple and convenient and can effectively reduce construction cost, can avoid the preliminary bracing bow member to sink and effectively guarantee the stability of preliminary bracing.

The above patent still has some disadvantages, the supporting effect is unstable only by the way of supporting the tunnel upper portion cavity body through the intermediate wall and the upper portion steel arch, the middle portion of the upper portion steel arch can be stably supported through the intermediate wall, but the space on both sides of the upper portion steel arch is large and lacks a supporting structure, and the risk that the upper portion steel arch collapses from both sides still occurs at the initial construction stage; although some constructors can arrange temporary support frames on two sides of an upper steel arch for supporting, the constructors have the defects that the support height and the support inclination of the support frames cannot be adjusted conveniently according to actual needs, the application range is limited, and the device is improved by combining the situations, so that the mountain tunnel crossing fault breaking anti-collapse device is provided for solving the problems.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the defects existing in the prior art and providing a mountain tunnel crossing fault breakage anti-collapse device.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a mountain tunnel crossing fault crushing collapse prevention device comprises a primary support device, wherein the primary support device comprises an upper steel arch, a tunnel inverted arch support fixed at the inner bottom of the upper steel arch and a middle support fixed between the inner top of the upper steel arch and the top of the tunnel inverted arch support, a plurality of groups of adjustable temporary reinforcing mechanisms are arranged on two sides of the middle support, each adjustable temporary reinforcing mechanism comprises a base fixed at the top of the tunnel inverted arch support through a bolt, a rectangular branch pipe is fixedly connected to the top of the base, a rectangular support rod is sleeved in the rectangular branch pipe in a sliding mode, the top end of the rectangular support rod extends to the upper side of the rectangular branch pipe and is hinged with a support top plate in an inclined mode, the top of the support top plate is in contact with the inner top of the upper steel arch, and a first screw rod rotatably mounted at the top of the corresponding base is arranged in the rectangular branch, the rectangular supporting rod is sleeved on the first screw rod in a threaded manner, a first bevel gear is fixedly sleeved on the first screw rod, the left side of the first bevel gear is meshed with a second bevel gear, the left side of the second bevel gear is fixedly connected with a rotating shaft, and the left end of the rotating shaft extends out of the rectangular supporting rod and is fixedly connected with a rocking disc;

the utility model discloses a support structure, including rectangle branch, rectangle support, slider, supporting roof, rectangle pole, rectangle branch pipe, and the top fixedly connected with L shape pole of well spacer, and the bottom of L shape pole has seted up the rectangular hole, and sliding sleeve is equipped with the rectangle pole in the rectangular hole, and the top of rectangle pole extends to the top of the L shape pole that corresponds and articulates there is the slider, and slider slidable mounting is in bottom one side of the supporting roof that corresponds, the second screw rod is installed to the rectangular hole internal rotation, and rectangle pole thread bush is established on the second screw rod, one side rotation that well spacer was kept away from to the rectangle branch pipe is installed the square pole, and in the top of square pole extends to the rectangular hole that corresponds, the second screw rod slip cap is established on the square pole that.

Preferably, the top of the base is fixedly connected with a first bearing, a second bearing is fixedly connected between the inner walls of the two sides of the rectangular branch pipe, and the inner ring of the second bearing and the inner ring of the first bearing are welded and sleeved with the outer side of the corresponding first screw rod.

Preferably, the bottom end of the rectangular supporting rod is provided with a first thread groove, and the first thread groove is in threaded connection with the corresponding first screw rod.

Preferably, a first round hole is formed in the inner wall of one side, away from the middle partition frame, of the rectangular branch pipe, a third bearing is fixedly sleeved in the first round hole, and the inner ring of the third bearing is welded and sleeved with the outer side of the corresponding rotating shaft.

Preferably, the bottom end of the rectangular rod is provided with a second thread groove, and the second thread groove is in threaded connection with the corresponding second screw rod.

Preferably, a square hole is formed in the top end of the second screw, and the inner wall of the square hole is in sliding connection with the outer side of the square rod.

Preferably, two T-shaped sliding rails are fixedly connected to one side of the bottom of the supporting top plate, two T-shaped sliding grooves with two sides being opened are formed in the top of the sliding block, and the T-shaped sliding grooves are connected with the corresponding T-shaped sliding rails in a sliding mode.

Preferably, one side of the rectangular branch pipe, which is far away from the middle partition frame, is welded with a fixed seat, one side of the fixed seat, which is far away from the corresponding rectangular branch pipe, is welded with a fourth bearing, and the inner ring of the fourth bearing is welded and fixed with the outer side of the corresponding square rod.

Preferably, a fifth bearing is fixedly connected between the inner walls of the two sides of the rectangular hole, and an inner ring of the fifth bearing is welded and sleeved with the outer side of the corresponding second screw rod.

Compared with the prior art, the beneficial effects of the utility model are that:

by matching the upper steel arch, the middle spacer, the base, the rectangular branch pipe, the rectangular support rod, the supporting top plate, the first screw rod, the first bevel gear, the second bevel gear, the rotating shaft, the rocking disc, the L-shaped rod, the rectangular hole, the rectangular rod, the sliding block, the second screw rod, the square rod and the rotating disc with the square hole, stable support can be carried out on the two sides and the middle position of the upper steel arch through the matching of a plurality of groups of adjustable temporary reinforcing mechanisms and the spacer, when the inclination of the supporting top plate is required to be adjusted according to actual requirements, the forward rotating rotary disc drives the second screw rod to rotate through the corresponding square rod and the square hole on the square rod, the corresponding rectangular rod is driven to move upwards while the second screw rod rotates, the corresponding sliding block is driven to move upwards by the rectangular rod, the sliding block extrudes the supporting top plate to rotate at the top of the rectangular support rod through the corresponding two T-shaped sliding rails, the supporting top plate drives the, the T-shaped slide rails slide in the corresponding T-shaped slide grooves, when the supporting top plate rotates to the inclination degree parallel to the upper steel arch, the rotation of the rotary table is stopped, then the rocking disc is rotated in the forward direction to drive the second bevel gear to rotate through the corresponding rotating shaft, the second bevel gear drives the corresponding first screw rod to rotate through the first bevel gear meshed with the second bevel gear, the first screw rod drives the corresponding rectangular supporting rod to move upwards while rotating, the rectangular supporting rod drives the second screw rod to slide upwards on the square rod through the corresponding L-shaped rod and the fifth bearing, the second screw rod drives the sliding block to move upwards through the corresponding rectangular rod, the rectangular supporting rod drives the supporting top plate hinged with the rectangular supporting rod to move upwards, so that the sliding block and the supporting top plate synchronously move upwards, when the top of the supporting top plate is in close contact with the inner wall of the top of the upper steel arch, the rocking disc is stopped to rotate, so that the supporting top plate, thereby completing the adjustment of the height and inclination of the supporting top plate.

The utility model relates to a rationally, the cooperation setting of the interim strengthening mechanism of multiunit adjustable and intermediate frame can carry out the outrigger to the both sides and the intermediate position of upper portion steel bow member, improves its preliminary stage temporary support stability, reduces the risk that takes place to collapse in the tunnel cave body initial stage construction, and can adjust the height and the gradient of roof according to actual need for can support different inclination radians and the upper portion steel bow member of height, improve its application scope, be favorable to the use.

Drawings

Fig. 1 is a schematic structural view of a mountain tunnel crossing fault crushing collapse prevention device provided by the present invention;

fig. 2 is a schematic view of a sectional structure of an adjustable temporary reinforcing mechanism of the mountain tunnel crossing fault crushing anti-collapse device provided by the utility model;

fig. 3 is an enlarged schematic view of a portion a in fig. 2.

In the figure: 100 upper steel arch frames, 101 middle shelves, 1 base, 2 rectangular branch pipes, 3 rectangular support rods, 4 supporting top plates, 5 first screw rods, 6 first bevel gears, 7 second bevel gears, 8 rotating shafts, 9 rocking discs, 10L-shaped rods, 11 rectangular holes, 12 rectangular rods, 13 sliding blocks, 14 second screw rods, 15 square rods, 16 rotating discs and 17 square holes.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments.

Referring to fig. 1-3, a mountain tunnel crossing fault crushing collapse prevention device comprises a primary support device, the primary support device comprises an upper steel arch 100, a tunnel inverted arch support fixed at the bottom of the inner side of the upper steel arch 100, and an intermediate support 101 fixed between the top of the inner side of the upper steel arch 100 and the top of the tunnel inverted arch support, two sides of the intermediate support 101 are respectively provided with a plurality of groups of adjustable temporary reinforcing mechanisms, each adjustable temporary reinforcing mechanism comprises a base 1 fixed at the top of the tunnel inverted arch support through bolts, the top of the base 1 is fixedly connected with a rectangular branch pipe 2, a rectangular support rod 3 is slidably sleeved in the rectangular branch pipe 2, the top end of the rectangular support rod 3 extends to the upper side of the rectangular branch pipe 2 and is hinged with a support top plate 4 which is obliquely arranged, the top of the support top plate 4 is in contact with the top of the inner side of the upper steel arch 100, a first screw 5 rotatably installed at the, the rectangular supporting rod 3 is sleeved on the first screw rod 5 in a threaded manner, the first screw rod 5 is fixedly sleeved with a first bevel gear 6, the left side of the first bevel gear 6 is meshed with a second bevel gear 7, the left side of the second bevel gear 7 is fixedly connected with a rotating shaft 8, and the left end of the rotating shaft 8 extends out of the rectangular branch pipe 2 and is fixedly connected with a rocking disc 9;

the top of one side of the rectangular support rod 3, which is far away from the middle spacer 101, is fixedly connected with an L-shaped rod 10, the bottom end of the L-shaped rod 10 is provided with a rectangular hole 11, a rectangular rod 12 is sleeved in the rectangular hole 11 in a sliding manner, the top end of the rectangular rod 12 extends to the upper side of the corresponding L-shaped rod 10 and is hinged with a slider 13, the slider 13 is slidably mounted at one side of the bottom of the corresponding supporting top plate 4, a second screw 14 is rotatably mounted in the rectangular hole 11, the rectangular rod 12 is sleeved on the second screw 14 in a threaded manner, a square rod 15 is rotatably mounted at one side of the rectangular branch pipe 2, which is far away from the middle spacer 101, the top end of the square rod 15 extends into the corresponding rectangular hole 11, the second screw 14 is sleeved on the corresponding square rod 15 in a sliding manner, the bottom end of the square rod 15 is fixedly connected with a rotary plate 16, and the outer side of the rotary plate 16 is fixedly connected, can carry out the outrigger to the both sides and the intermediate position of upper portion steel bow member 100, improve its preliminary stage temporary support stability, reduce the risk that takes place to collapse in the tunnel cave body initial stage construction, and can adjust the height and the gradient of roof 4 according to actual need for can support different inclination radians and the upper portion steel bow member 100 of height, improve its application scope, be favorable to using.

In the utility model, a first bearing is fixedly connected on the top of a base 1, a second bearing is fixedly connected between the inner walls of the two sides of a rectangular branch pipe 2, the inner ring of the second bearing and the inner ring of the first bearing are welded and sleeved with the outer side of a corresponding first screw 5, a first thread groove is arranged at the bottom end of a rectangular support rod 3 and is in threaded connection with a corresponding first screw 5, a first round hole is arranged on the inner wall of one side of the rectangular branch pipe 2 away from a middle partition frame 101, a third bearing is fixedly sleeved in the first round hole, the inner ring of the third bearing is welded and sleeved with the outer side of a corresponding rotating shaft 8, a second thread groove is arranged at the bottom end of a rectangular rod 12 and is in threaded connection with a corresponding second screw 14, a square hole 17 is arranged at the top end of the second screw 14, the inner wall of the square hole 17 is in sliding connection with the outer side of the square rod 15, two T-shaped slide rails are fixedly connected on one side, the top of the sliding block 13 is provided with two T-shaped sliding grooves with two sides opened, the T-shaped sliding grooves are connected with corresponding T-shaped sliding rails in a sliding manner, one side of the rectangular branch pipe 2 far away from the middle spacer 101 is welded with a fixed seat, one side of the fixed seat far away from the corresponding rectangular branch pipe 2 is welded with a fourth bearing, the inner ring of the fourth bearing is welded and fixed with the outer side of the corresponding square rod 15, a fifth bearing is fixedly connected between the inner walls of the two sides of the rectangular hole 11, and the inner ring of the fifth bearing is welded and sleeved with the outer side of the corresponding second screw 14, the utility model has reasonable design, the matching arrangement of the multiple groups of adjustable temporary reinforcing mechanisms and the middle spacer 101 can stably support the two sides and the middle position of the upper steel arch 100, improve the initial temporary supporting stability, reduce the collapse risk in the initial construction of the tunnel cave body, and adjust the height and inclination of the supporting top plate 4, the upper steel arch 100 with different inclination radians and heights can be supported, the application range of the steel arch is widened, and the use is facilitated.

The working principle is as follows: when the temporary supporting device is used, the two sides and the middle position of the upper steel arch frame 100 can be stably supported through the matching of the multiple groups of adjustable temporary reinforcing mechanisms and the partition frame 101, the initial temporary supporting stability of the temporary supporting device is improved, and the risk of collapse in the initial construction of the tunnel cave body is reduced;

when the inclination of the supporting top plate 4 needs to be adjusted according to actual needs, the rotating disc 16 is rotated in the forward direction, the rotating disc 16 drives the corresponding square rod 15 to rotate, the square rod 15 drives the second screw rod 14 to rotate through the corresponding square hole 17, under the action of the second thread groove formed on the rectangular rod 12, the second screw rod 14 drives the corresponding rectangular rod 12 to move upwards while rotating, the rectangular rod 12 drives the corresponding sliding block 13 to move upwards while moving upwards, the sliding block 13 extrudes the supporting top plate 4 through the corresponding T-shaped sliding rail, the extrusion force enables the supporting top plate 4 to rotate at the top of the corresponding rectangular supporting rod 3, the supporting top plate 4 drives the corresponding two T-shaped sliding rails to rotate, the T-shaped sliding rails slide in the corresponding T-shaped sliding grooves, the inclination angle of the supporting top plate 4 changes along with the rotation of the supporting top plate 4, when the inclination of the supporting top plate 4 is adjusted to be suitable for the inclination of the upper steel arch 100, stopping rotating the rotary table 16, and fixing the inclination angle of the top supporting plate 4 under the action of the self-thread locking damping force of the second thread groove and the second screw 14;

then the rocking disc 9 is rotated in the positive direction, the rocking disc 9 drives the corresponding rotating shaft 8 to rotate, the rotating shaft 8 drives the corresponding second bevel gear 7 to rotate, the second bevel gear 7 drives the first bevel gear 6 engaged with the second bevel gear to rotate, the first bevel gear 6 drives the corresponding first screw 5 to rotate, under the action of a first thread groove formed on the rectangular supporting rod 3, the first screw 5 drives the corresponding rectangular supporting rod 3 to move upwards while rotating, the rectangular supporting rod 3 drives the corresponding L-shaped rod 10 to move upwards, the L-shaped rod 10 drives the second screw 14 to slide upwards on the square rod 15 through the corresponding fifth bearing, under the action of thread locking damping force, the second screw 14 drives the corresponding rectangular rod 12 to move upwards while moving upwards, the rectangular rod 12 drives the corresponding slide block 13 to move upwards, the rectangular supporting rod 3 drives the supporting top plate 4 hinged with the rectangular supporting rod 3 to move upwards, make slider 13 and roof support 4 synchronous upward movement, when roof support 4's top and upper portion steel bow member 100's top inner wall in close contact with, roof support 4 carries out the outrigger to upper portion steel bow member 100, the swivelling of stall rocking disc 9, under first screw rod 5 and the first thread groove self screw thread locking damping force effect that corresponds, make roof support 4 fixed, and then accomplished the regulation of the height and the gradient of roof support 4, make it can support different inclination radians and upper portion steel bow member 100 of height, improve its application scope.

In the description of the present application, it should be further noted that, unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may include, for example, a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, a connection through an intermediate medium, and a connection between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to specific circumstances.

The above, only be the concrete implementation of the preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art is in the technical scope of the present invention, according to the technical solution of the present invention and the utility model, the concept of which is equivalent to replace or change, should be covered within the protection scope of the present invention.

Claims

1. A mountain tunnel crossing fault crushing collapse prevention device comprises a primary support device, wherein the primary support device comprises an upper steel arch (100), a tunnel inverted arch support fixed at the inner bottom of the upper steel arch (100), and a middle partition (101) fixed between the inner top of the upper steel arch (100) and the top of the tunnel inverted arch support, and is characterized in that a plurality of groups of adjustable temporary reinforcing mechanisms are arranged on two sides of the middle partition (101), each adjustable temporary reinforcing mechanism comprises a base (1) fixed at the top of the tunnel inverted arch support through bolts, a rectangular branch pipe (2) is fixedly connected to the top of the base (1), a rectangular support rod (3) is sleeved in the rectangular branch pipe (2) in a sliding mode, the top end of the rectangular support rod (3) extends to the upper side of the rectangular branch pipe (2) and is hinged with a support top plate (4) in an inclined mode, the top of the supporting top plate (4) is in contact with the top of the inner side of the upper steel arch frame (100), a first screw (5) rotatably mounted at the top of the corresponding base (1) is arranged in the rectangular branch pipe (2), the rectangular support rod (3) is sleeved on the first screw (5) in a threaded manner, a first bevel gear (6) is fixedly sleeved on the first screw (5), a second bevel gear (7) is meshed on the left side of the first bevel gear (6), a rotating shaft (8) is fixedly connected on the left side of the second bevel gear (7), and the left end of the rotating shaft (8) extends out of the rectangular branch pipe (2) and is fixedly connected with a rocking disc (9);

the top of one side of each rectangular support rod (3) far away from the middle spacer (101) is fixedly connected with an L-shaped rod (10), the bottom end of each L-shaped rod (10) is provided with a rectangular hole (11), each rectangular hole (11) is internally provided with a rectangular rod (12) in a sliding sleeve mode, the top end of each rectangular rod (12) extends to the upper portion of the corresponding L-shaped rod (10) and is hinged with a sliding block (13), each sliding block (13) is installed on one side of the bottom of the corresponding supporting top plate (4) in a sliding mode, a second screw rod (14) is installed in each rectangular hole (11) in a rotating mode, each rectangular rod (12) is sleeved on each second screw rod (14) in a threaded mode, one side of each rectangular branch pipe (2) far away from the middle spacer (101) is rotatably provided with a square rod (15), the top end of each square rod (15) extends into the corresponding rectangular hole (11), each second screw rod (14) is sleeved on the corresponding square rod (, and a plurality of handle rods are fixedly connected with the outer side of the rotary disc (16) at equal intervals in a ring shape.

2. The mountain tunnel fault-crossing crushing anti-collapse device according to claim 1, wherein a first bearing is fixedly connected to the top of the base (1), a second bearing is fixedly connected between the inner walls of the two sides of the rectangular branch pipe (2), and the inner ring of the second bearing and the inner ring of the first bearing are welded and sleeved with the outer side of the corresponding first screw (5).

3. The mountain tunnel fault-crossing, breaking and anti-collapse device as claimed in claim 1, wherein the bottom end of the rectangular strut (3) is provided with a first thread groove, and the first thread groove is in threaded connection with the corresponding first screw (5).

4. The mountain tunnel fault-crossing crushing collapse prevention device as claimed in claim 1, wherein a first circular hole is formed in an inner wall of one side, away from the middle partition frame (101), of the rectangular branch pipe (2), a third bearing is fixedly sleeved in the first circular hole, and an inner ring of the third bearing is welded and sleeved with an outer side of the corresponding rotating shaft (8).

5. The mountain tunnel fault-crossing, breaking and anti-collapse device as claimed in claim 1, wherein the bottom end of the rectangular rod (12) is provided with a second thread groove, and the second thread groove is in threaded connection with a corresponding second screw (14).

6. The mountain tunnel fault-crossing, breaking and anti-collapse device as claimed in claim 1, wherein a square hole (17) is formed at the top end of the second screw (14), and the inner wall of the square hole (17) is slidably connected with the outer side of the square rod (15).

7. The mountain tunnel fault-crossing crushing collapse prevention device as claimed in claim 1, wherein two T-shaped sliding rails are fixedly connected to one side of the bottom of the supporting top plate (4), two T-shaped sliding grooves with openings on both sides are formed in the top of the sliding block (13), and the T-shaped sliding grooves are slidably connected with the corresponding T-shaped sliding rails.

8. The mountain tunnel fault-crossing crushing anti-collapse device according to claim 1, wherein a fixed seat is welded on one side of the rectangular branch pipe (2) far away from the middle partition frame (101), a fourth bearing is welded on one side of the fixed seat far away from the corresponding rectangular branch pipe (2), and an inner ring of the fourth bearing is welded and fixed with the outer side of the corresponding square rod (15).

9. The mountain tunnel fault-crossing, breaking and anti-collapse device according to claim 1, wherein a fifth bearing is fixedly connected between the inner walls of the two sides of the rectangular hole (11), and the inner ring of the fifth bearing is welded and sleeved with the outer side of the corresponding second screw (14).