Welding tool and valve cover welding part

Abstract

The utility model relates to the technical field of welding processing, and discloses a welding tool and a valve cover welding piece. A valve cover, a sleeve and a bracket of the valve cover welding piece are sequentially propped against and sleeved on the periphery of the core rod; the first positioning sleeve corresponds to the abutting position of the valve cover and the sleeve; the ventilation sleeve is clamped between the core rod and the valve cover; the ventilation sleeve is provided with a gap channel; the filler sleeve is clamped in the bracket filler hole; the gland sleeve is clamped in the rear opening of the bracket; the pre-tightening assembly is connected with the core rod in an assembled mode and presses and abuts against the gland sleeve; according to the welding tool and the valve cover welding piece, the welding tool matched with the valve cover welding piece is arranged, the purposes of guaranteeing the coaxiality of parts, effectively reducing welding deformation and improving production efficiency are achieved, the yield of machining every shift in a traditional design is two or three pieces, and after the welding tool and automatic argon arc welding matched with the welding tool are adopted, the production efficiency is greatly improved. And the average yield of machining of each shift can reach more than ten pieces, the production efficiency is high, and the practicability is high.

Description

Technical Field

[0001] The utility model relates to the technical field of welding processing, in particular to a welding tool and a valve cover welding piece. Background Art

[0002] The valve cover weldment is an integral part composed of multiple components. It is long and cannot be directly processed. It must be formed by welding multiple sections.

[0003] In the prior art, when valve cover weldments are machined, the traditional socket welding method of two parts is often adopted, that is, the two parts are plugged together, positioned and manually welded. This welding method has large welding deformation and poor weld formation, resulting in post-processing operations such as grinding and sandblasting after welding, and the overall production efficiency is low. Utility Model Content

[0004] In view of this, the utility model provides a welding tool and a valve cover welding piece to solve the problems of large deformation and low production efficiency in the insertion and positioning welding of the valve cover welding piece.

[0005] In the first aspect, the utility model provides a welding tool, including: a core rod, a positioning end plate is provided on its periphery; a valve cover, a sleeve, and a bracket of a valve cover welding part are sequentially abutted and sleeved on the outer periphery of the core rod, and the end of the valve cover abuts against the positioning end plate; a first positioning sleeve is sleeved between the core rod and the valve cover welding part, and corresponds to the abutment position of the valve cover and the sleeve; the valve cover and the sleeve are at least partially sleeved on the periphery of the first positioning sleeve; a ventilation sleeve is sleeved on the core rod and clamped between the core rod and the valve cover; the ventilation sleeve has a gap; a stuffing sleeve is sleeved on the core rod and clamped at the stuffing hole of the bracket; a pressure cover sleeve is sleeved on the core rod and clamped at the rear opening of the bracket; a pre-tightening component is assembled with the core rod, and the pre-tightening component is suitable for pressing and abutting against the pressure cover sleeve.

[0006] Beneficial effects: By setting up a welding tool that matches the valve cover welding parts, the coaxiality of the parts is ensured while effectively reducing welding deformation and improving production efficiency; the maximum output that can be processed per shift by the traditional process is 2 to 3 pieces. With the help of welding tools and corresponding automatic argon arc welding, the average output that can be welded per shift is 12 pieces, which greatly improves production efficiency, is highly practical, and saves labor; the welding tool has pre-tightening parts and multiple positioning parts, which can effectively improve the welding quality, make the shape beautiful, and do not require grinding and sandblasting, reducing subsequent turnover processes, further improving efficiency and reducing costs; the welding tool is suitable for multi-section welding, and can ensure coaxiality without affecting the assembly and use of parts.

[0007] In an optional embodiment, it also includes a second positioning sleeve, which is sleeved between the core rod and the valve cover welding part and corresponds to the abutment position of the sleeve and the bracket; the sleeve and the bracket are at least partially sleeved on the periphery of the second positioning sleeve.

[0008] In an optional embodiment, the preload assembly includes an elastic member and a fastener, one side of the elastic member abuts against the gland sleeve, and the fastener is pressed against the other side of the elastic member to shrink the elastic member, thereby providing a preload force.

[0009] In an optional embodiment, the ventilation sleeve is formed by correspondingly buckling at least two first ring sleeves; wherein a gap is provided at the buckling position of the at least two first ring sleeves, and the gap forms the gap channel.

[0010] In an optional embodiment, a vent hole is formed through the positioning end plate, and is suitable for introducing protective gas through the vent hole.

[0011] In an optional embodiment, the second positioning sleeve is formed by a plurality of second ring sleeves that are correspondingly fastened together; and the filling sleeve is formed by a plurality of third ring sleeves that are correspondingly fastened together.

[0012] In an optional embodiment, a raised layer is provided on the periphery of the core rod, and the raised layer and the periphery of the core rod form a stepped limit stop, and the vent sleeve is suitable for being clamped at the limit stop.

[0013] In an optional embodiment, the gland sleeve has a barrel portion and a flange, the barrel portion is located in the rear opening, and the flange abuts against an open end of the rear opening.

[0014] In an optional embodiment, the positioning end plate is perpendicular to the axis of the core rod.

[0015] In the second aspect, the utility model also provides a valve cover welding part, which is suitable for being welded with the assistance of the welding tool as described in any one of the above items, and the valve cover welding part comprises: a valve cover, a sleeve and a bracket coaxially arranged in sequence along the axial direction, and the valve cover abuts the sleeve, and the sleeve abuts the bracket; the valve cover is provided with a first groove at the abutting position with the sleeve, and the sleeve is provided with a second groove at the abutting position with the valve cover, and the first groove and the second groove are arranged oppositely; the sleeve is provided with a third groove at the abutting position with the bracket, and the bracket is provided with a fourth groove at the abutting position with the sleeve, and the third groove and the fourth groove are arranged oppositely. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a schematic diagram of the cooperation between the welding tool and the valve cover welding part of the utility model;

[0018] Figure 2 It is a schematic diagram of the cooperation between the core rod and the positioning end plate of the utility model;

[0019] Figure 3 It is an enlarged schematic diagram of the A part of the utility model;

[0020] Figure 4 It is a schematic diagram of the bracket of the utility model;

[0021] Figure 5 It is a cross-sectional view of the ventilation sleeve of the utility model;

[0022] Figure 6 It is a side view schematic diagram of the ventilation sleeve of the utility model;

[0023] Figure 7 It is a cross-sectional view of the first positioning sleeve of the utility model;

[0024] Figure 8 It is a cross-sectional view of the second positioning sleeve of the utility model;

[0025] Fig. 9 It is a side view schematic diagram of the second positioning sleeve of the utility model;

[0026] Fig.10 It is a cross-sectional view of the packing sleeve of the utility model;

[0027] Fig.11 It is a side view schematic diagram of the packing sleeve of the utility model;

[0028] Fig.12 It is a cross-sectional view of the gland sleeve of the utility model.

[0029] Description of reference numerals:

[0030] 1. Mandrel; 11. Raised layer; 12. Limit stop; 2. Positioning end plate; 21. Vent hole; 3. First positioning sleeve; 4. Vent sleeve; 41. Gap; 42. First ring sleeve; 5. Stuffing sleeve; 51. Third ring sleeve; 6. Gland sleeve; 61. Cylinder; 62. Flange; 7. Preload assembly; 71. Elastic member; 72. Fastener; 8. Second positioning sleeve; 81. Second ring sleeve; 9. Valve cover; 91. Sleeve; 92. Bracket; 93. Rear opening; 94. First groove; 95. Second groove; 96. Third groove; 97. Fourth groove; 98. Stuffing hole. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Combine the following Figures 1 to 12 , describing an embodiment of the utility model.

[0036] According to an embodiment of the utility model, on the one hand, a welding tool is provided, including: a core rod 1, a positioning end plate 2 is provided on its periphery, the positioning end plate 2 is perpendicular to the axis of the core rod 1, and is used to position the valve cover 9 to the core rod 1; the valve cover 9, the sleeve 91, and the bracket 92 of the valve cover welding part are sequentially abutted and sleeved on the outer periphery of the core rod 1, and the end of the valve cover 9 abuts against the positioning end plate 2, so that the valve cover 9 and the core rod 1 are concentrically arranged; a first positioning sleeve 3 is sleeved between the core rod 1 and the valve cover welding part, and corresponds to the abutment position of the valve cover 9 and the sleeve 91; the valve cover 9 and the sleeve 91 are at least partially sleeved on the periphery of the first positioning sleeve 3; ventilation A sleeve 4 is sleeved on the core rod 1 and clamped between the core rod 1 and the valve cover 9; the ventilation sleeve 4 has a gap 41; a stuffing sleeve 5 is sleeved on the core rod 1 and clamped in the stuffing hole 98 of the bracket 92; a pressure cover sleeve 6 is sleeved on the core rod 1 and clamped in the rear opening 93 of the bracket 92; a pre-tightening component 7 is assembled and connected to the core rod 1, and the pre-tightening component 7 is suitable for pressing and abutting against the pressure cover sleeve 6; a second positioning sleeve 8 is sleeved between the core rod 1 and the valve cover welding part, and corresponds to the abutment position of the sleeve 91 and the bracket 92; the sleeve 91 and the bracket 92 are at least partially sleeved on the periphery of the second positioning sleeve 8.

[0037] Furthermore, the valve cover 9 abuts against the sleeve 91, and the sleeve 91 abuts against the bracket 92; the valve cover 9 is provided with a first groove 94 at the abutting position with the sleeve 91, and the sleeve 91 is provided with a second groove 95 at the abutting position with the valve cover 9, and the first groove 94 is docked with the second groove 95; the sleeve 91 is provided with a third groove 96 at the abutting position with the bracket 92, and the bracket 92 is provided with a fourth groove 97 at the abutting position with the sleeve 91, and the third groove 96 is docked with the fourth groove 97; the first positioning sleeve 3 is located at the docking position of the first groove 94 and the second groove 95, and is used to ensure that the first groove 94 is concentric with the second groove 95 to avoid misalignment; the second positioning sleeve 8 is located at the docking position of the third groove 96 and the fourth groove 97, and is used to ensure that the third groove 96 is concentric with the fourth groove 97 to avoid misalignment.

[0038] Furthermore, a raised layer 11 is provided on the periphery of the core rod 1, and the raised layer 11 and the periphery of the core rod 1 form a stepped limit stop 12, and the ventilation sleeve 4 is clamped at the limit stop 12; a ventilation hole 21 is passed through the positioning end plate 2, and a protective gas is introduced through the ventilation hole 21, and the protective gas can be argon.

[0039] Furthermore, the preload assembly 7 includes an elastic member 71 and a fastener 72, one side of the elastic member 71 abuts against the pressure cover sleeve 6, and the fastener 72 is pressed against the other side of the elastic member 71 to shrink the elastic member 71, which is suitable for providing a preload force; the elastic member 71 can be a disc spring, the fastener 72 can be a fastening nut, and an external thread matching with it is provided around the corresponding position of the core rod 1.

[0040] The welding process includes, on the one hand, the welding process adopts automatic argon arc welding, that is, an automated welding process using argon as a shielding gas, which can effectively prevent oxidation of the welding area and improve welding efficiency; on the other hand, the welding method adopts butt welding, that is, the groove surfaces of the weldment are aligned and welded, the gap between the roots of the butt joints is 3mm, single-sided welding and double-sided forming are performed during welding, that is, welding on the outside, the weld on the inner cavity side can also be well formed, and the weld on the inner cavity side can be polished after welding, which saves time and effort; on the other hand, welding tooling is designed, and the welding tooling and the parts of the valve cover weldment are simulated and assembled and fixed, wherein argon arc spot welding brings the parts into contact, and automatic welding welds the parts together, ensuring the coaxiality of the parts while having high welding quality, without the need for turnover and polishing post-processing procedures, thereby improving production efficiency and greatly increasing the number of finished products processed in the same time period.

[0041] The specific welding production process includes a spot welding process, in which a tool is used to fix the valve cover welding piece to perform spot welding at an electric welding machine; a vent sleeve 4 is welded at the limit stop 12 of the core rod 1, and a gap 41 for ventilation is provided at the vent sleeve 4; a center line is drawn at the valve cover 9, the sleeve 91 and the bracket 92, and the first positioning sleeve 3 is sleeved to the periphery of the core rod 1, and the first positioning sleeve 3 is abutted against the vent sleeve 4; the valve cover 9, the sleeve 91, the second positioning sleeve 8, the bracket 92, the packing sleeve 5, the gland sleeve 6, the elastic member 71 are sequentially assembled. , the fasteners 72 are aligned and assembled to the periphery of the core rod 1, wherein the valve cover 9 is in contact with one end of the sleeve 91, the first groove 94 is opposite to the second groove 95, the bracket 92 is in contact with the other end of the sleeve 91, and the third groove 96 is opposite to the fourth groove 97; the first positioning sleeve 3 is sleeved between the core rod 1 and the valve cover welding part, and corresponds to the abutting position of the valve cover 9 and the sleeve 91, and the valve cover 9 and the sleeve 91 are at least partially sleeved on the periphery of the first positioning sleeve 3, and the first positioning sleeve 3 makes the first groove 94 and the second groove 95 concentric to ensure The second positioning sleeve 8 is similar to the first positioning sleeve 3. The second positioning sleeve 8 is sleeved between the core rod 1 and the valve cover welding part, and corresponds to the abutment position of the sleeve 91 and the bracket 92, and the sleeve 91 and the bracket 92 are at least partially sleeved on the periphery of the second positioning sleeve 8. The second positioning sleeve 8 makes the third groove 96 and the fourth groove 97 concentric to ensure the coaxiality of the parts; the packing sleeve 5 is sleeved on the core rod 1 and clamped on the packing hole 98 of the bracket 92 to locate the position of the packing hole 98 at the core rod 1; the gland sleeve 6 is sleeved on Mandrel 1, and clamped to the rear opening 93 of the bracket 92, positioning the rear opening 93 at the mandrel 1; the elastic member 71 cooperates with the fastener 72, one side of the elastic member 71 abuts against the gland sleeve 6, and the other side is pressed by the fastener 72, so that the elastic member 71 contracts and presses the gland sleeve 6, providing preload force for the welding assembly to reduce deformation; first fix it with argon arc spot welding at the groove to make the brackets 92 of each part contact, ensure the height of the welding parts between adjacent parts to ensure the coaxiality of the parts, and remove the valve cover welding parts.

[0042] The specific welding production process also includes the assembly welding process, which is to use a tool to fix the valve cover welding parts to perform assembly welding at the assembly welding machine; assemble the valve cover welding parts and the stuffing sleeve 5, the gland sleeve 6, and the pre-tightening assembly 7 to the core rod 1, take the fastening screws through the valve cover 9 and the positioning end plate 2 and fix them, then clamp and fix the core rod 1, and start welding; start the welding gun to start the arc welding of the first layer of the weld seam 1, and the weld seam 1 is the weld seam at the third groove 96 and the fourth groove 97; rotate the welding gun 180 degrees to start the arc, and weld The first layer of weld seam 2, wherein weld seam 2 is the weld seam at the first groove 94 and the second groove 95; tighten fastener 72 and continuously weld weld seam 2; after rotating the welding gun 180 degrees, start an arc near weld seam 1 and continuously weld weld seam 1; after cooling for ten minutes, remove the valve cover welding part and complete the welding; during the welding process, an air pipe is provided at the air hole 21, and argon gas is introduced through the air pipe to protect the weld seam; after welding is completed, the weld seam expands first and then contracts, and fastener 72 needs to be tightened in time to reduce deformation.

[0043] Optionally, in the welding tooling, the length of the core rod 1 is determined according to the longest length of the valve cover weldments in the same batch. When producing valve cover weldments with shorter lengths, an auxiliary connecting plate can be added between the positioning end plate 2 and the end plate of the valve cover 9. The auxiliary connecting plate is fixed at intervals at the positioning end plate 2, and a vent hole 21 is also provided at the auxiliary connecting plate, and the valve cover 9 abuts against the auxiliary connecting plate.

[0044] In this embodiment, by setting up a welding tool that matches the valve cover welding parts, the purpose of ensuring the coaxiality of the parts while effectively reducing welding deformation and improving production efficiency is achieved; the maximum output that can be processed per shift by the traditional process is 2 to 3 pieces. With the help of welding tools and corresponding automatic argon arc welding, the average output that can be welded per shift is 12 pieces, which greatly improves production efficiency, has strong practicality, and saves labor; the welding tool has pre-tightening parts and multiple positioning parts, which can effectively improve the welding quality, have beautiful forming, do not require grinding and sandblasting, reduce subsequent turnover processes, further improve efficiency, and reduce costs; the welding tool is suitable for multi-section welding, and can ensure coaxiality without affecting the assembly and use of parts.

[0045] In some embodiments, in combination Figure 5 and Figure 6 As shown, the ventilation sleeve 4 is formed by correspondingly buckling at least two first ring sleeves 42; wherein, there is a gap at the buckling position of the at least two first ring sleeves 42, and the gap forms the gap channel 41, and the gap channel 41 is arranged at the periphery of the ventilation sleeve 4, and at least two gap channels 41 are arranged oppositely; argon gas passes through the ventilation hole 21, the cavity at the valve cover 9, and the gap channel 41 and then enters the vicinity of the weld to protect the weld.

[0046] In some embodiments, in combination Figures 8 to 11As shown, the second positioning sleeve 8 is formed by a plurality of second ring sleeves 81 that are correspondingly fastened together. During spot welding assembly, at least two second ring sleeves 81 can be correspondingly installed on the core rod 1, which is convenient for disassembly of the second positioning sleeve 8; the filling sleeve 5 is formed by a plurality of third ring sleeves 51 that are correspondingly fastened together, which is convenient for loading and unloading from both sides of the filling hole 98 of the bracket 92.

[0047] In some embodiments, in combination Fig.12 As shown, the gland sleeve 6 has a barrel 61 and a flange 62, wherein the barrel 61 is located in the rear opening 93 to position the rear opening 93 of the bracket 92 to the core rod 1; the flange 62 abuts against the open end of the rear opening 93 to compress the bracket 92 under the action of the pre-tightening assembly 7.

[0048] According to an embodiment of the utility model, on the other hand, a valve cover weldment is also provided, which is suitable for being welded with the assistance of a welding tool as described in any one of the above items, and the valve cover weldment comprises: a valve cover 9, a sleeve 91 and a bracket 92 which are coaxially arranged in sequence along the axial direction, and the valve cover 9 abuts against the sleeve 91, and the sleeve 91 abuts against the bracket 92; the valve cover 9 is provided with a first groove 94 at the abutting position with the sleeve 91, and the sleeve 91 is provided with a second groove 95 at the abutting position with the valve cover 9, and the first groove 94 and the second groove 95 are arranged oppositely; the sleeve 91 is provided with a third groove 96 at the abutting position with the bracket 92, and the bracket 92 is provided with a fourth groove 97 at the abutting position with the sleeve 91, and the third groove 96 and the fourth groove 97 are arranged oppositely.

[0049] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present utility model are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present utility model, and such modifications and variations are all within the scope defined by the present utility model.

Claims

1. A welding tool, characterized in that: include: A mandrel (1) is provided with a positioning end plate (2) at its periphery; a valve cover (9), a sleeve (91), and a bracket (92) of a valve cover welding member are sequentially abutted and sleeved on the outer periphery of the mandrel (1), and an end of the valve cover (9) is abutted against the positioning end plate (2); A first positioning sleeve (3) is sleeved between the core rod (1) and the valve cover welding piece and corresponds to the abutment position of the valve cover (9) and the sleeve (91); the valve cover (9) and the sleeve (91) are at least partially sleeved on the periphery of the first positioning sleeve (3); A vent sleeve (4) is sleeved on the core rod (1) and sandwiched between the core rod (1) and the valve cover (9); the vent sleeve (4) has a gap (41); A filler sleeve (5) is sleeved on the core rod (1) and is clamped at the filler hole (98) of the bracket (92); A gland sleeve (6) is sleeved on the core rod (1) and is clamped at the rear opening (93) of the bracket (92); A pre-tightening component (7) is assembled and connected to the core rod (1), and the pre-tightening component (7) is suitable for pressing and abutting against the gland sleeve (6).

2. The welding tool according to claim 1, characterized in that: It also includes a second positioning sleeve (8), which is sleeved between the core rod (1) and the valve cover welding part and corresponds to the abutment position of the sleeve (91) and the bracket (92); the sleeve (91) and the bracket (92) are at least partially sleeved on the periphery of the second positioning sleeve (8).

3. The welding tool according to claim 1, characterized in that: The pre-tightening assembly (7) comprises an elastic member (71) and a fastener (72), one side of the elastic member (71) abuts against the gland sleeve (6), and the fastener (72) presses against the other side of the elastic member (71) to cause the elastic member (71) to contract, thereby providing a pre-tightening force.

4. The welding tool according to claim 3, characterized in that: The ventilation sleeve (4) is formed by correspondingly buckling at least two first ring sleeves (42); There is a gap at the buckling position of the at least two first ring sleeves (42), and the gap forms the gap channel (41).

5. The welding tool according to claim 4, characterized in that: The positioning end plate (2) is provided with a vent hole (21) through which protective gas can be introduced.

6. The welding tool according to claim 2, characterized in that: The second positioning sleeve (8) is formed by a plurality of second ring sleeves (81) being buckled in correspondence; The packing sleeve (5) is formed by a plurality of third ring sleeves (51) being correspondingly buckled together.

7. The welding tool according to claim 6, characterized in that: The periphery of the core rod (1) is provided with a raised layer (11), the raised layer (11) and the periphery of the core rod (1) form a stepped limit stop (12), and the ventilation sleeve (4) is suitable for being clamped at the limit stop (12).

8. The welding tool according to claim 7, characterized in that: The gland sleeve (6) comprises a barrel (61) and a flange (62), wherein the barrel (61) is located in the rear opening (93), and the flange (62) abuts against the open end of the rear opening (93).

9. The welding tool according to claim 1, characterized in that: The positioning end plate (2) is perpendicular to the axis of the core rod (1).

10. A valve cover welding part, characterized in that: Suitable for being welded with the assistance of the welding tool as described in any one of claims 1 to 9 above, the valve cover welded part comprises: A valve cover (9), a sleeve (91) and a bracket (92) are coaxially arranged in sequence along the axial direction, wherein the valve cover (9) abuts against the sleeve (91), and the sleeve (91) abuts against the bracket (92); The valve cover (9) is provided with a first groove (94) at a position where it abuts against the sleeve (91), and the sleeve (91) is provided with a second groove (95) at a position where it abuts against the valve cover (9), and the first groove (94) and the second groove (95) are arranged opposite to each other; The sleeve (91) is provided with a third groove (96) at the abutting position with the bracket (92), and the bracket (92) is provided with a fourth groove (97) at the abutting position with the sleeve (91), and the third groove (96) and the fourth groove (97) are arranged opposite to each other.

Images