High-performance fixed ball valve

Abstract

The utility model provides a high-performance fixed ball valve which comprises a ball valve body provided with a left valve body and a right valve body, the ball valve body is provided with a left flow channel, a valve cavity and a right flow channel which are sequentially communicated, a valve ball is arranged in the valve cavity, and the two ends of the valve cavity are respectively provided with a valve seat located on the two sides of the valve ball. A plurality of guide inserting grooves are circumferentially formed in the cavity wall, facing the valve ball, of the valve cavity, a plurality of guide inserting columns connected with the guide inserting grooves in an inserted mode are fixedly connected to the end face, facing the guide inserting grooves, of the valve seat, the guide inserting columns are in sliding fit with the guide inserting grooves, and grooves are formed in the end faces, deviating from the valve seat, of the guide inserting columns. And a push seat spring is arranged between the bottom wall of the groove and the bottom wall of the guide slot. According to the high-performance fixed ball valve, the push seat spring is arranged, so that the valve seat can be kept in the state of abutting against the valve ball, and the sealing performance between the valve seat and the valve ball can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of ball valves, in particular to a high-performance fixed ball valve. Background Art

[0002] A ball valve is a valve whose opening and closing member (ball) is driven by the valve stem and rotates around the axis of the ball valve. It can be used for fluid regulation and control. Ball valves are mainly used to cut off, distribute and change the flow direction of the medium in pipelines. It only needs to rotate 90 degrees and a very small rotational force to close or open.

[0003] The trunnion-mounted ball valve is suitable for long-distance pipelines and general industrial pipelines. Its strength, safety, and resistance to harsh environments are specially considered during design. During operation, the force generated by the fluid pressure in front of the valve on the ball is completely transmitted to the bearing, which will not cause the ball to move toward the valve seat. Therefore, the valve seat will not be subjected to excessive pressure. Therefore, the trunnion-mounted ball valve has low torque, small valve seat deformation, stable sealing performance, and long service life. It is suitable for high-pressure and large-diameter occasions.

[0004] The existing Chinese patent with authorization announcement number CN219588167U discloses a ball-stem integrated fluorine-lined fixed ball valve, including a valve body, a valve cover, a valve seat, an integrated ball valve plate and a valve stem. A drain device is provided at the bottom of the valve body, and the drain device includes a drain clip stud, a wrench clip, a push-pull wrench, a plug and a drain channel connected to the cavity; the drain clip stud connects the valve body and the drain device, and the push-pull wrench is connected to the drain device through the wrench clip; a fastening device is provided on the upper part of the ball valve plate, and the fastening device is arranged between the valve body and the valve stem. The fastening device includes a fastening stud, a fastening plate integrated with the fastening stud, a fixing sleeve, a retractable hose and a sealing ring wrapped around the fastening plate and the fixing sleeve.

[0005] The above-mentioned prior art solution has the following defects: the valve seat and the spherical valve plate of the ball-stem integrated fluorine-lined fixed ball valve cooperate to form a seal, and the sealing performance between the valve seat and the spherical valve plate is poor. Utility Model Content

[0006] The problem to be solved by the present invention is to provide a high-performance fixed ball valve in view of the above-mentioned deficiencies in the prior art, which solves the problem of poor sealing in the prior art.

[0007] The above-mentioned utility model object of the present invention is achieved through the following technical solutions: a high-performance fixed ball valve, comprising a ball valve body with a left valve body and a right valve body, the ball valve body having a left flow channel, a valve cavity, and a right flow channel connected in sequence, a valve ball is arranged in the valve cavity, and valve seats are respectively arranged on both ends of the valve cavity, and a plurality of guide slots are circumferentially opened on the cavity wall of the valve cavity facing the valve ball, and a plurality of guide plugs that are plugged into the guide slots are fixedly connected to the end surface of the valve seat facing the guide slots, the guide plugs are slidably matched with the guide slots, and a groove is arranged on the end surface of the guide plug facing away from the valve seat, and a push seat spring is arranged between the bottom wall of the groove and the bottom wall of the guide slot.

[0008] The utility model is further configured as follows: an upper slot is provided on the top surface of the valve ball, and the upper slot is a rectangular slot; a stuffing slot and an upper through-rod hole are provided downward in sequence on the top surface of the right valve body; an upper valve stem rotatably matched with the upper valve stem is passed through the upper through-rod hole; a connecting block that is plugged into the upper slot is provided at the bottom of the upper valve stem, and the connecting block is a rectangular block.

[0009] The utility model is further configured as follows: a sealing packing sleeved on the upper valve stem is embedded in the bottom of the packing groove, a packing gland screwed to the right valve body is embedded in the top of the packing groove, and the bottom surface of the packing gland is against the top surface of the sealing packing.

[0010] The utility model is further configured as follows: a plurality of spokes are equidistantly arranged on the circumference of the outer side wall of the upper valve stem, a rim is arranged on the top of the plurality of spokes, and a handle is arranged on the rim.

[0011] The utility model is further configured as follows: a lower slot is provided on the bottom surface of the valve ball, a lower through-rod hole is provided through the bottom surface of the right valve body, a lower valve stem is passed through the lower through-rod hole, an oil-free lubricating bearing is sleeved on the top of the lower valve stem, and the top of the lower valve stem equipped with the oil-free lubricating bearing is plugged into the lower slot.

[0012] The utility model is further configured as follows: a lock cover slot is provided on the bottom surface of the right valve body, a limit ring groove is provided on the groove wall of the lock cover slot, a bottom cover is provided on the bottom of the lower valve stem, a lock cover through-hole aligned with the lock cover slot is provided on the bottom surface of the bottom cover, a lock cover device is inserted in the lock cover slot and the lock cover through-hole, the lock cover device includes a lock cover column with an inner column groove inside, the lock cover column passes through the lock cover through-hole and is plugged into the lock cover slot, a positioning convex plate whose top surface abuts against the bottom surface of the bottom cover is provided on the outer side wall of the lock cover column, a lock cover guide hole is provided through the outer side wall of the lock cover column, a lock cover slide is slidably provided in the lock cover guide hole, and a control piece assembly is provided in the inner column groove.

[0013] The present invention is further configured as follows: a through-rod hole is provided on the bottom surface of the lock cover column, a hinged platform is provided on the end surface of the lock cover slide close to the inner column groove, and external hinged nails are provided on both end surfaces of the hinged platform; the control plate assembly includes a rotary vertical rod, a rod convex plate, and a hinged rod; the rotary vertical rod is rotatably arranged at the center of the inner column groove and the end portion extends out of the inner column groove through the through-rod hole; the rod convex plate is coaxially arranged on the rotary vertical rod, and a plurality of middle hinged nails are provided on both end surfaces of the rod convex plate; one end of the hinged rod is hinged to the hinged platform through the external hinged nail, and the other end is hinged to the rod convex plate through the middle hinged nail.

[0014] The utility model is further configured as follows: a cross hand wheel is coaxially arranged after the rotary vertical rod passes through the through rod hole.

[0015] The utility model is further configured as follows: an upper limit turntable and a lower limit turntable are coaxially arranged on the rotary vertical rod, and the upper limit turntable and the lower limit turntable are both rotatably matched with the inner column groove, the upper limit turntable is abutted against the top wall of the inner column groove, and the lower limit turntable is abutted against the bottom wall of the inner column groove.

[0016] The utility model is further configured as follows: a lock disk insertion hole is opened on the side wall of the lower limit turntable, a lock disk through hole aligned with the lock disk insertion hole is opened through the outer wall of the lock cover column, and a lock disk pin connected to the lock disk insertion hole is passed through the lock disk through hole.

[0017] In summary, the beneficial technical effects of the present invention are as follows: the high-performance fixed ball valve is provided with a seat push spring so that the valve seat can maintain a state of pressing against the valve ball, which is beneficial to improving the sealing between the valve seat and the valve ball. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic cross-sectional view of the high-performance fixed ball valve in the utility model;

[0019] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0020] Figure 3 yes Figure 1 Enlarged view of point B in the middle;

[0021] Figure 4 This is a structural diagram of the cover locking device in the utility model;

[0022] Figure 5 It is a structural schematic diagram of the cover locking device of the utility model without the cover locking column.

[0023] In the above drawings: 1, ball valve body; 2, right valve body; 3, left valve body; 4, left flow channel; 5, valve chamber; 6, right flow channel; 7, valve ball; 8, upper slot; 9, lower slot; 10, guide slot; 11, valve seat; 12, guide pin; 13, groove; 14, push seat spring; 15, stuffing groove; 16, upper rod hole; 17, upper valve stem; 18, connecting block; 19, spoke; 20, wheel rim; 21, handle; 22, sealing packing; 23, stuffing gland; 24, lower rod hole; 25, lower valve stem; 26, oil-free lubricated bearing; 2 7. Lock cover slot; 28. Limit ring groove; 29. ​​Bottom cover; 30. Lock cover through hole; 31. Lock cover device; 32. Lock cover column; 321. Semi-cylinder; 33. Inner column groove; 34. Through rod hole; 35. Positioning convex plate; 36. Lock cover guide hole; 37. Lock cover slide; 38. Articulated table; 39. External hinge pin; 40. Rotating vertical rod; 41. Cross handwheel; 42. Rod convex plate; 43. Middle hinge pin; 44. Articulated rod; 45. Upper limit turntable; 46. Lower limit turntable; 47. Lock disk jack; 48. Lock disk through hole; 49. Lock disk pin. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below with reference to the accompanying drawings and specific implementation methods.

[0025] like Figure 1 As shown, the utility model proposes a high-performance fixed ball valve, including a ball valve body 1, the ball valve body 1 includes a right valve body 2, a left valve body 3 screwed to the side of the right valve body 2, the ball valve body 1 has a left flow channel 4, a valve cavity 5, and a right flow channel 6 connected in sequence, the left flow channel 4 is located in the left valve body 3, the valve cavity 5 is partially located in the left valve body 3, and the other part is located in the right valve body 2, and the right flow channel 6 is located in the right valve body 2.

[0026] like Figure 1 As shown, a valve ball 7 is provided in the valve cavity 5, an upper slot 8 is provided on the top surface of the valve ball 7, and the upper slot 8 is a rectangular slot, and a lower slot 9 is provided on the bottom surface of the valve ball 7, and the lower slot 9 is a circular slot.

[0027] like Figure 1 and 2As shown, the valve chamber 5 has a plurality of circular guide slots 10 formed on the circumferential surface of the cavity wall facing the valve ball 7. Valve seats 11 are provided at both ends of the valve chamber 5, one on each side of the valve ball 7. The valve seats 11 and the valve ball 7 form a dynamic seal. A plurality of guide pins 12 are fixedly connected to the end surface of the valve seat 11 facing the guide slots 10. The guide pins 12 are equidistantly distributed around the circumference and are cylindrical in shape. The guide pins 12 slide in engagement with the guide slots 10. A groove 13 is formed on the end surface of the guide pin 12 facing away from the valve seat 11. A seat push spring 14 is provided between the bottom wall of the groove 13 and the bottom wall of the guide slot 10. The seat push spring 14 is used to push the valve seat 11 toward the valve ball 7, allowing the valve seat 11 to remain in contact with the valve ball 7, thereby improving the sealing between the valve seat 11 and the valve ball 7.

[0028] The high-performance fixed ball valve is provided with a seat push spring 14 so that the valve seat 11 can maintain a state of being pressed against the valve ball 7 , which is beneficial to improving the sealing between the valve seat 11 and the valve ball 7 .

[0029] like Figure 1 As shown, the top surface of the right valve body 2 is provided with a packing groove 15 and an upper rod hole 16 in a downward direction. The packing groove 15 is T-shaped, and the upper rod hole 16 is a circular hole. An upper valve stem 17 is inserted into the upper rod hole 16. The upper rod hole 16 and the upper valve stem 17 are rotatably engaged. The top of the upper valve stem 17 passes through the packing groove 15. The bottom of the upper valve stem 17 is integrally connected to a connecting block 18 that plugs into the upper slot 8. The connecting block 18 is a rectangular block. When the upper valve stem 17 rotates, it can drive the valve ball 7 to rotate. A plurality of spokes 19 are equidistantly arranged on the outer wall of the upper valve stem 17. A rim 20 is fixedly connected to the top of the spokes 19. A handle 21 is fixedly connected to the rim 20.

[0030] like Figure 1 As shown, a sealing packing 22 mounted on the upper valve stem 17 is embedded in the bottom of the packing groove 15, and a packing gland 23 is embedded in the top of the packing groove 15. The packing gland 23 is T-shaped and is screwed to the right valve body 2. The bottom surface of the packing gland 23 abuts against the top surface of the sealing packing 22. The packing gland 23 presses and fixes the sealing packing 22 in the packing groove 15.

[0031] like Figure 1 As shown, a lower through-rod hole 24 is provided on the bottom surface of the right valve body 2. The lower through-rod hole 24 is a circular hole. A lower valve stem 25 is passed through the lower through-rod hole 24. An oil-free lubricated bearing 26 is sleeved on the top of the lower valve stem 25. The top of the lower valve stem 25 equipped with the oil-free lubricated bearing 26 is plugged into the lower slot 9.

[0032] like Figure 1 and 3As shown, two circular locking cover slots 27 are symmetrically formed on the bottom surface of the right valve body 2, located on either side of the lower through-rod hole 24. A limiting ring groove 28 is formed on the groove wall of the locking cover slot 27, and the cross-section of the limiting ring groove 28 is circular.

[0033] like Figure 1 and 3 As shown, the bottom of the lower valve stem 25 is integrally connected with a bottom cover 29, which closes the lower through-rod hole 24. Two locking cover through-holes 30 are symmetrically provided on the bottom surface of the bottom cover 29. The locking cover through-holes 30 are circular holes, and the two locking cover through-holes 30 are aligned with the two locking cover slots 27 respectively.

[0034] like Figure 3 and 4 As shown, a lock mechanism 31 is inserted into the lock cover slot 27 and the lock cover through-hole 30. The lock mechanism 31 includes a lock cover post 32 with an inner column slot 33 therein. The inner column slot 33 is a circular groove, and the lock cover post 32 is cylindrical. After passing through the lock cover through-hole 30, the lock cover post 32 plugs into the lock cover slot 27. The lock cover post 32 is formed by gluing a pair of semi-cylinders 321 together, with the inner column slot 33 split in half between the two semi-cylinders 321. A through rod hole 34 is formed through the bottom surface of the lock cover post 32. The through rod hole 34 is a circular hole, coaxial with the inner column slot 33, and split in half between the two semi-cylinders 321.

[0035] like Figure 3 and 4 As shown, a positioning convex plate 35 is fixedly connected to the outer wall of the locking cover column 32. The cross section of the positioning convex plate 35 is annular and is arranged in half on the two half cylinders 321. When the locking cover device 31 is installed, the top surface of the positioning convex plate 35 abuts against the bottom surface of the bottom cover 29.

[0036] like Figure 3 and 4 As shown, the outer wall of the lock cover column 32 is provided with a lock cover guide hole 36. The cross-section of the lock cover guide hole 36 is rectangular, and there are two lock cover guide holes 36, which are respectively provided in the two half-columns 321. A lock cover slide 37 is slidably disposed in each lock cover guide hole 36. The lock cover slide 37 is a rectangular piece. The end surface of the lock cover slide 37 near the inner column slot 33 is fixedly connected to a hinged plate 38. The end surfaces of the hinged plate 38 are provided with external hinge pins 39.

[0037] like Figure 3 and 5 As shown, a control piece assembly is provided in the inner column groove 33, and the control piece assembly is used to drive the lock cover slide 37 to make reciprocating linear motion along the lock cover guide hole 36. The control piece assembly includes a rotary vertical rod 40, a rod convex plate 42, and a hinged rod 44.

[0038] like Figure 3 and 5 As shown, the swivel vertical rod 40 is cylindrical and is rotatably mounted at the center of the inner column slot 33. The swivel vertical rod 40 extends out of the inner column slot 33 through the through-rod hole 34 and rotatably engages with the through-rod hole 34. After the swivel vertical rod 40 passes through the through-rod hole 34, it is coaxially fixedly connected to a cross-hand wheel 41, which is used to provide a force point for a worker to rotate the swivel vertical rod 40.

[0039] like Figure 3 and 5 As shown, the rod protrusion 42 is coaxially fixedly connected to the rotary vertical rod 40, the rod protrusion 42 is coplanar with the two lock cover guide holes 36, and two middle hinge pins 43 are equidistantly arranged on the two end surfaces of the rod protrusion 42.

[0040] like Figure 3 and 5 As shown, one end of the hinged rod 44 is hinged to the hinged platform 38 through the outer hinge pin 39, and the other end is hinged to the rod protrusion 42 through the middle hinge pin 43. There are two hinged rods 44 between the rod protrusion 42 and each hinged platform 38. The two hinged rods 44 are symmetrically arranged on both sides of the rod protrusion 42. Two hinged rods 44 are arranged between the swivel vertical rod 40 and the locking cover slide 37, which is beneficial to improve the connection stability between the swivel vertical rod 40 and the locking cover slide 37.

[0041] like Figure 3 and 5 As shown, an upper limit turntable 45 and a lower limit turntable 46 are coaxially fixedly connected to the rotary vertical rod 40. The upper limit turntable 45 and the lower limit turntable 46 are both circular plate-shaped. The upper limit turntable 45 and the lower limit turntable 46 are both rotatably matched with the inner column groove 33. The upper limit turntable 45 is against the top wall of the inner column groove 33, and the lower limit turntable 46 is against the bottom wall of the inner column groove 33.

[0042] like Figure 3 and 5 As shown, a lock disk insertion hole 47 is opened on the side wall of the lower limit turntable 46, and a lock disk through hole 48 is opened through the outer wall of the lock cover column 32. The lock disk through hole 48 is opened in half on the two half cylinders 321. The lock disk through hole 48 can be aligned with the lock disk insertion hole 47. A lock disk pin 49 is inserted into the lock disk through hole 48 and is plugged into the lock disk insertion hole 47.

[0043] The detailed installation process of the lock cover device 31 in this embodiment is as follows: the worker passes the lock cover column 32 through the lock cover through-hole 30 and inserts it into the lock cover slot 27 until the top surface of the positioning protrusion 35 abuts against the bottom surface of the bottom cover 29. At this time, the lock cover guide hole 36 is aligned with the limit ring groove 28. Then the worker rotates the rotary vertical rod 40 through the cross hand wheel 41. The rotation of the rotary vertical rod 40 drives the rod protrusion 42 to rotate. The rotation of the rod protrusion 42 drives the lock cover slide 37 through the hinge rod 44. When it moves away from the rotary vertical rod 40, the lock cover slide 37 will extend out of the lock cover guide hole 36 and insert into the limit ring groove 28. At the same time, the lock disk socket 47 is aligned with the lock disk through hole 48. The worker passes the lock disk pin 49 through the lock disk through hole 48 and inserts it into the lock disk socket 47. At this time, the lower limit turntable 46 and the rotary vertical rod 40 are restricted from rotating, and the lock cover slide 37 will remain inserted into the limit ring groove 28, and the bottom cover 29 and the right valve body 2 are restricted from separation.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and are not limiting. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A high-performance fixed ball valve, comprising a ball valve body (1) having a left valve body (3) and a right valve body (2), wherein the ball valve body (1) has a left flow channel (4), a valve cavity (5), and a right flow channel (6) that are sequentially connected, a valve ball (7) being disposed in the valve cavity (5), and valve seats (11) being disposed on both sides of the valve ball (7), respectively, at both ends of the valve cavity (5), and characterized in that: A plurality of guide slots (10) are provided on the circumferential surface of the valve cavity (5) facing the valve ball (7); a plurality of guide pins (12) are fixedly connected to the end surface of the valve seat (11) facing the guide slots (10) and plugged into the guide slots (10); the guide pins (12) are slidably engaged with the guide slots (10); a groove (13) is provided on the end surface of the guide pin (12) facing away from the valve seat (11); a seat push spring (14) is provided between the bottom wall of the groove (13) and the bottom wall of the guide slot (10).

2. A high performance fixed ball valve according to claim 1, characterized in that: An upper slot (8) is provided on the top surface of the valve ball (7), and the upper slot (8) is a rectangular slot. A packing slot (15) and an upper rod hole (16) are provided downwardly on the top surface of the right valve body (2). An upper valve stem (17) rotatably matched with the upper valve stem (17) is provided through the upper rod hole (16). A connecting block (18) plugged into the upper slot (8) is provided at the bottom of the upper valve stem (17), and the connecting block (18) is a rectangular block.

3. A high performance fixed ball valve according to claim 2, characterized in that: The bottom of the stuffing groove (15) is embedded with a sealing stuffing (22) mounted on the upper valve stem (17), and the top of the stuffing groove (15) is embedded with a stuffing gland (23) screwed to the right valve body (2), and the bottom surface of the stuffing gland (23) is against the top surface of the sealing stuffing (22).

4. A high performance fixed ball valve according to claim 3, characterized in that: A plurality of spokes (19) are equidistantly arranged on the outer side wall of the upper valve stem (17), a rim (20) is arranged on the top of the plurality of spokes (19), and a handle (21) is arranged on the rim (20).

5. The high-performance fixed ball valve according to claim 1, characterized in that: A lower slot (9) is provided on the bottom surface of the valve ball (7), a lower through-rod hole (24) is provided on the bottom surface of the right valve body (2), a lower valve stem (25) is passed through the lower through-rod hole (24), an oil-free lubricating bearing (26) is sleeved on the top of the lower valve stem (25), and the top of the lower valve stem (25) equipped with the oil-free lubricating bearing (26) is plugged into the lower slot (9).

6. A high performance fixed ball valve according to claim 5, characterized in that: A locking cover slot (27) is provided on the bottom surface of the right valve body (2), a limiting ring groove (28) is provided on the groove wall of the locking cover slot (27), a bottom cover (29) is provided on the bottom of the lower valve stem (25), a locking cover through-hole (30) aligned with the locking cover slot (27) is provided on the bottom surface of the bottom cover (29), a locking cover device (31) is inserted into the locking cover slot (27) and the locking cover through-hole (30), and the locking cover device (31) includes an inner column groove The locking cover column (32) of the lock cover column (33) is inserted into the locking cover slot (27) after passing through the locking cover through hole (30). A positioning convex plate (35) is provided on the outer wall of the locking cover column (32), the top surface of which abuts against the bottom surface of the bottom cover (29). A locking cover guide hole (36) is opened through the outer wall of the locking cover column (32), a locking cover slide (37) is slidably provided in the locking cover guide hole (36), and a control piece assembly is provided in the inner column groove (33).

7. A high performance fixed ball valve according to claim 6, characterized in that: A through-rod hole (34) is provided on the bottom surface of the locking cover column (32); a hinged platform (38) is provided on the end surface of the locking cover slide (37) close to the inner column groove (33); and external hinged nails (39) are provided on both end surfaces of the hinged platform (38); the control plate assembly comprises a rotary vertical rod (40), a rod convex plate (42), and a hinged rod (44); the rotary vertical rod (40) is rotatably arranged at the center of the inner column groove (33) and its end extends out of the inner column groove (33) through the through-rod hole (34); the rod convex plate (42) is coaxially arranged on the rotary vertical rod (40); and a plurality of middle hinged nails (43) are provided on both end surfaces of the rod convex plate (42); one end of the hinged rod (44) is hinged to the hinged platform (38) through the external hinged nail (39), and the other end is hinged to the rod convex plate (42) through the middle hinged nail (43).

8. A high performance fixed ball valve according to claim 7, characterized in that: After the rotary vertical rod (40) passes through the through rod hole (34), a cross hand wheel (41) is coaxially arranged.

9. A high performance fixed ball valve according to claim 8, characterized in that: An upper limit turntable (45) and a lower limit turntable (46) are coaxially arranged on the rotary vertical rod (40). Both the upper limit turntable (45) and the lower limit turntable (46) are rotatably matched with the inner column groove (33). The upper limit turntable (45) abuts against the top wall of the inner column groove (33), and the lower limit turntable (46) abuts against the bottom wall of the inner column groove (33).

10. A high performance fixed ball valve according to claim 9, characterized in that: A lock disk insertion hole (47) is provided on the side wall of the lower limit rotating disk (46), a lock disk through hole (48) aligned with the lock disk insertion hole (47) is provided on the outer side wall of the lock cover column (32), and a lock disk pin (49) is inserted into the lock disk insertion hole (47) through the lock disk through hole (48).

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