One-way pipe fitting

Abstract

The invention provides a one-way pipe fitting, and belongs to the technical field of check valves. The check valve solves the problems that an existing check valve is troublesome in operation and low in assembly efficiency. The one-way pipe fitting comprises a first pipe body, a second pipe body and a one-way valve, the inner side wall of the first pipe body is provided with an annular first step face, the inner side wall of the second pipe body is provided with an annular second step face, the one-way valve comprises a cylindrical valve body, and the peripheral wall of the valve body is sleeved with a first sealing ring; the first pipe body and the second pipe body are fixedly connected in a friction welding mode, so that one end of the valve body abuts against the first step face, the other end of the valve body abuts against the second step face, and the first sealing ring is attached to the inner side wall of the first pipe body. The one-way pipe fitting has the advantages that water leakage of the one-way pipe fitting is avoided, and meanwhile the assembling efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of check valves and relates to a one-way pipe fitting. Background Art

[0002] A check valve is an automatic valve whose core function is to prevent the reverse flow of the medium, ensuring the one-way flow of the medium in the pipeline. The check valve is automatically opened and closed by the force generated by the flow of the medium itself without an external driving device, and is widely used in fields such as chemical industry, petroleum, water supply, and construction.

[0003] For existing check valves, for example, a Chinese patent document discloses a tubular one-way valve [Patent No.: 202220560499.1; Application Publication No.: CN216975894U]. The tubular one-way valve adopts a split valve seat structure, including a front valve seat, a sealing ring, a rear valve seat, a valve core, a spring, a guide rod, an anti-rotation washer, and an anti-rotation nut; the front valve seat is located on the side of the fluid medium inlet, and the side of the fluid medium inlet is machined with internal threads for connecting external connectors. The side close to the fluid medium outlet is external threads and is screwed to the rear valve seat; the rear valve seat is located on the side of the fluid medium outlet. The side close to the fluid medium inlet has internal threads that match the external threads of the front valve seat, and an installation groove for the sealing ring is provided on the end face close to the fluid medium inlet side; the inside of the rear valve seat close to the fluid medium outlet side is provided with internal threads for installing the guide rod and can also be used to connect other parts such as joints in the system.

[0004] For the tubular one-way valve with this structure, the front valve seat and the rear valve seat are fixedly connected by means of threaded connection. Although a sealing ring is provided between the front valve seat and the rear valve seat, the accuracy of threaded connection is relatively low, resulting in the problem that the sealing ring is not installed in place, and the sealing ring also has the problem of aging and failure, leading to the problem of water leakage between the front valve seat and the rear valve seat. At the same time, for the tubular one-way valve with this structure, during assembly, first connect the front valve seat and the rear valve seat by threaded connection, then put the valve core, spring, guide rod, and anti-rotation washer into the front valve seat and the rear valve seat, and finally rotate the anti-rotation nut with a tool to install the valve core, spring, guide rod, and anti-rotation washer to the appropriate position. However, the installation operation space is small, the operation is troublesome, and the assembly efficiency is low. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art and propose a one-way pipe fitting, and the technical problem to be solved is how to make the one-way pipe fitting not leak water while improving the assembly efficiency.

[0006] The object of the present invention can be achieved by the following technical solutions: A one-way pipe fitting includes a first pipe body, a second pipe body and a one-way valve. It is characterized in that an annular first step surface is provided on the inner side wall of the first pipe body, an annular second step surface is provided on the inner side wall of the second pipe body, the one-way valve includes a cylindrical valve body, a first sealing ring is sleeved on the outer peripheral wall of the valve body, and the first pipe body and the second pipe body are fixedly connected by friction welding so that one end of the valve body abuts against the first step surface and the other end abuts against the second step surface, and the first sealing ring fits with the inner side wall of the first pipe body.

[0007] The one-way valve is pre-assembled into one body, and the installation is not restricted by space and is convenient to assemble. When installing the one-way pipe fitting, the first pipe body is positioned by equipment and the second pipe body is clamped, so that the inner ends of the first pipe body and the second pipe body are arranged opposite to each other. The one-way valve is inserted into the inner end of the first pipe body. The second pipe body is moved to a set position by equipment and the second pipe body is rotated at a high speed, so that heat is generated due to friction between the inner ends of the first pipe body and the second pipe body, and the contact surface reaches the molten state, and the first pipe body and the second pipe body are hermetically fixed by friction welding, and the sealing effect is good. At the same time, when the first pipe body and the second pipe body are fixedly connected, one end of the valve body abuts against the first step surface and the other end abuts against the second step surface, and the one-way valve is naturally fixed, thereby completing the assembly of the one-way pipe fitting, making the one-way pipe fitting not leak water and improving the assembly efficiency.

[0008] In the above one-way pipe fitting, a first avoidance groove is provided on the outer side wall of the inner end of the first pipe body, a second avoidance groove is provided on the inner side wall of the inner end of the second pipe body, the groove width of the first avoidance groove along the axial direction of the one-way pipe fitting is greater than the groove width of the second avoidance groove, the inner side wall of the inner end of the first pipe body is embedded in the second avoidance groove, and the outer side wall of the inner end of the second pipe body is embedded in the first avoidance groove. This structure enables the inner ends of the first pipe body and the second pipe body to be inserted into each other, increases the contact area between the first pipe body and the second pipe body, increases the melting and sealing area, thereby improving the sealing effect of the one-way pipe fitting and making the one-way pipe fitting not leak water; the inner side wall of the inner end of the first pipe body is embedded in the second avoidance groove, and the outer side wall of the inner end of the second pipe body is embedded in the first avoidance groove. Initially, the groove width of the first avoidance groove along the axial direction of the one-way pipe fitting is greater than the groove width of the second avoidance groove, that is, the inner side wall of the inner end of the first pipe body is longer, which can provide more melting material, so as to better fill the gap between the first pipe body and the second pipe body, improve the sealing effect, and make the one-way pipe fitting not leak water.

[0009] In the above-mentioned one-way pipe fitting, a plurality of first anti-rotation strips are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the first pipe body, and a plurality of second anti-rotation strips are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the second pipe body. The first anti-rotation strips and the second anti-rotation strips are both arranged along the axial direction of the one-way pipe fitting. The arrangement of the first anti-rotation strips can improve the stability of the first pipe body during positioning, and the arrangement of the second anti-rotation strips can improve the stability of the second pipe body during rotation, thereby improving the stability of the one-way pipe fitting during friction welding connection, ensuring the sealing quality of the one-way pipe fitting, and thus improving the sealing effect of the one-way pipe fitting, so that the one-way pipe fitting does not leak water.

[0010] In the above-mentioned one-way pipe fitting, the distance from the first step surface to the inner end face of the first pipe body is greater than the distance from the second step surface to the inner end face of the second pipe body, and the first sealing ring is arranged adjacent to the first step surface. With this structure, the first sealing ring is far from the welding position, so that the first sealing ring will not be damaged when the first pipe body and the second pipe body are friction welded, ensuring the sealing performance of the first sealing ring and the one-way conduction function of the one-way pipe fitting.

[0011] In the above-mentioned one-way pipe fitting, the inner side wall of the first pipe body also has a tapered guiding surface. The inner diameter of the first pipe body between the first step surface and the guiding surface is smaller than the inner diameter of the first pipe body between the inner end face and the guiding surface. The first sealing ring is located between the first step surface and the guiding surface. The guiding surface plays a guiding role. The guiding surface is tapered, so that the first sealing ring can better cross the guiding surface and be located between the first step surface and the guiding surface. The inner diameter of the first pipe body between the first step surface and the guiding surface is smaller than the inner diameter of the first pipe body between the inner end face and the guiding surface. The reduced inner diameter can be 0.2 mm, and the reduction amount is relatively small, but it enables the first sealing ring to deform better, has a better sealing effect, ensures the one-way conduction function of the one-way pipe fitting, and at the same time, under the action of the deformation of the first sealing ring to generate sealing, the one-way valve can be better positioned, improving the stability of the one-way valve, thereby improving the stability of the one-way pipe fitting and ensuring the one-way conduction function of the one-way pipe fitting.

[0012] In the above-mentioned one-way pipe fitting, the inner diameter of the inner end of the first pipe body is greater than the inner diameter of the outer end of the first pipe body, the inner diameter of the inner end of the second pipe body is greater than the inner diameter of the outer end of the second pipe body, and the outer peripheral wall of the valve body is in clearance fit with the inner peripheral wall of the inner end of the first pipe body, and the outer peripheral wall of the valve body is in clearance fit with the inner peripheral wall of the inner end of the second pipe body. With this structure, the one-way valve can be embedded and installed in the first pipe body and the second pipe body. One end of the one-way valve realizes radial positioning with the first pipe body through the first sealing ring, and the other end of the one-way valve realizes radial positioning due to the molten material flowing into the gap during the relative rotation and friction welding of the first pipe body and the second pipe body.

[0013] In the above-mentioned one-way pipe fitting, the one-way valve further includes a core rod, a pressing plate, a second sealing ring and a spring. There is a guiding cylinder in the valve body. The core rod passes through the guiding cylinder. One end of the core rod is fixedly connected with the pressing plate, and the other end is sleeved and fixedly connected with the second sealing ring. The spring is sleeved on the core rod. The two ends of the spring respectively act on the valve body and the pressing plate, so that the second sealing ring always has a tendency to be hermetically abutted against the valve body to close the one-way valve. Under the action of the spring force, the second sealing ring is hermetically abutted against the valve body to close the one-way valve. When the water flow overcomes the spring force and pushes the core rod open, the one-way valve is opened to achieve one-way conduction.

[0014] In the above-mentioned one-way pipe fitting, a plurality of first guiding strips are protruded on the inner side wall of the guiding cylinder at equal intervals, and a plurality of second guiding strips are protruded on the outer side wall of the core rod at equal intervals. The first guiding strips and the second guiding strips are both arranged along the axial direction of the one-way pipe fitting. The first guiding strips are located between two adjacent second guiding strips, and the second guiding strips are located between two adjacent first guiding strips. There are gaps between the first guiding strips and the two adjacent second guiding strips. Both the first guiding strips and the second guiding strips play a guiding role to make the core rod move in a set direction. At the same time, there are gaps between the first guiding strips and the two adjacent second guiding strips, so that the core rod has a certain circumferential degree of freedom, which can reduce contact friction, reduce wear, and improve the sensitivity of guiding and conduction.

[0015] In the above-mentioned one-way pipe fitting, an annular abutting ring is protruded inward on the inner side wall of the valve body. The abutting ring and the guiding cylinder are fixedly connected by a plurality of connecting rods arranged at intervals. There are water passing holes for water to pass through between two adjacent connecting rods. Under the action of the spring force, the second sealing ring can be abutted against the abutting ring to block the water passing holes to close the one-way valve. This kind of structure makes the design of the one-way valve reasonable and enables the one-way valve to have a better one-way conduction function.

[0016] In the above-mentioned one-way pipe fitting, the spring is sleeved outside the guiding cylinder, and the spring abuts against the connecting rod. The outer diameter of the spring matches the outer diameter of the guiding cylinder, which improves the stability of the spring.

[0017] In the above-mentioned one-way pipe fitting, the pressing plate is fixedly connected with one end of the core rod by bolts, and the bolts are arranged along the axial direction of the core rod. The pressing plate is detachable, which makes the installation of the spring more convenient.

[0018] Compared with the prior art, a one-way pipe fitting provided by the present invention has the following advantages:

[0019] 1. The first pipe body and the second pipe body of this one-way pipe fitting are hermetically connected by friction welding, which has a good sealing effect. At the same time, when the first pipe body and the second pipe body are connected, the one-way valve is naturally fixed, thus completing the assembly of the one-way pipe fitting, making the one-way pipe fitting leak-proof and improving the assembly efficiency.

[0020] 2. The inner ends of the first pipe body and the second pipe body of this one-way pipe fitting are inserted into each other, increasing the contact area between the first pipe body and the second pipe body, increasing the melting and sealing area, thereby improving the sealing effect of the one-way pipe fitting and making the one-way pipe fitting leak-proof.

[0021] 3. By providing a tapered guiding surface on the inner side wall of the first pipe body of this one-way pipe fitting, the first sealing ring can deform better, making the first sealing ring have a better sealing effect, ensuring the one-way conduction function of the one-way pipe fitting. At the same time, under the action of the deformation of the first sealing ring to generate sealing, the one-way valve can be better positioned, improving the stability of the one-way valve, thereby improving the stability of the one-way pipe fitting and ensuring the one-way conduction function of the one-way pipe fitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the overall structural sectional view of this one-way pipe fitting.

[0023] Figure 2 is this one-way pipe fitting Figure 1 the enlarged view of area A in.

[0024] Figure 3 is this one-way pipe fitting Figure 1 the enlarged view of area B in.

[0025] Figure 4 is the exploded view of this one-way pipe fitting.

[0026] Figure 5 is the exploded view of the one-way valve of this one-way pipe fitting.

[0027] In the figure, 1. First pipe body; 11. First step surface; 12. First avoidance groove; 13. First anti-rotation strip; 14. Guiding surface; 2. Second pipe body; 21. Second step surface; 22. Second avoidance groove; 23. Second anti-rotation strip; 3. One-way valve; 31. Valve body; 311. Guiding cylinder; 312. First guiding strip; 313. Abutting ring; 314. Connecting rod; 315. Water passing hole; 32. First sealing ring; 33. Core rod; 331. Second guiding strip; 34. Pressing plate; 35. Second sealing ring; 36. Spring; 37. Bolt. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following are specific embodiments of the present invention in combination with the drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0029] As Figure 1 、 Figure 4 shown, this one-way pipe fitting includes a first pipe body 1, a second pipe body 2, and a one-way valve 3 with a one-way conduction function.

[0030] In this embodiment, eight first anti-rotation strips 13 are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the first pipe body 1, and eight second anti-rotation strips 23 are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the second pipe body 2. Both the first anti-rotation strips 13 and the second anti-rotation strips 23 are arranged along the axial direction of the one-way pipe fitting. In actual production, the number of the first anti-rotation strips 13 and the second anti-rotation strips 23 can both be six or twelve.

[0031] On the outer side wall of the inner end of the first pipe body 1, there is a first avoidance groove 12, and on the inner side wall of the inner end of the second pipe body 2, there is a second avoidance groove 22. The groove width of the first avoidance groove 12 along the axial direction of the one-way pipe fitting is greater than the groove width of the second avoidance groove 22. The inner side wall of the inner end of the first pipe body 1 is embedded into the second avoidance groove 22, and the outer side wall of the inner end of the second pipe body 2 is embedded into the first avoidance groove 12.

[0032] As Figure 2 shown, on the inner side wall of the first pipe body 1, there is an annular first step surface 11 and a conical guiding surface 14. As Figure 3 shown, on the inner side wall of the second pipe body 2, there is an annular second step surface 21. The distance from the first step surface 11 to the end face of the inner end of the first pipe body 1 is greater than the distance from the second step surface 21 to the end face of the inner end of the second pipe body 2. The inner diameter of the first pipe body 1 between the first step surface 11 and the guiding surface 14 is smaller than the inner diameter between the end face of the inner end of the first pipe body 1 and the guiding surface 14.

[0033] As Figure 5 shown, the one-way valve 3 includes a valve body 31, a first sealing ring 32, a core rod 33, a pressing plate 34, a second sealing ring 35, a spring 36, and a bolt 37.

[0034] The valve body 31 is in a cylindrical shape. The first sealing ring 32 is sleeved on the outer peripheral wall of the valve body 31. The first pipe body 1 and the second pipe body 2 are fixedly connected by friction welding, so that one end of the valve body 31 abuts against the first step surface 11 and the other end abuts against the second step surface 21. The first sealing ring 32 is in contact with the inner side wall of the first pipe body 1. The first sealing ring 32 is adjacent to the first step surface 11, and the first sealing ring 32 is located between the first step surface 11 and the guiding surface 14. The inner diameter of the inner end of the first pipe body 1 is greater than the inner diameter of the outer end of the first pipe body 1, and the inner diameter of the inner end of the second pipe body 2 is greater than the inner diameter of the outer end of the second pipe body 2. The outer peripheral wall of the valve body 31 has a clearance fit with the inner peripheral wall of the inner end of the first pipe body 1, and the outer peripheral wall of the valve body 31 has a clearance fit with the inner peripheral wall of the inner end of the second pipe body 2.

[0035] The valve body 31 is provided with a guide cylinder 311. The core rod 33 passes through the guide cylinder 311. One end of the core rod 33 is fixedly connected with a pressing plate 34 by a bolt 37, and the other end is sleeved and fixedly connected with a second sealing ring 35. The bolt 37 is arranged along the axial direction of the core rod 33. In this embodiment, four first guide strips 312 are convexly arranged at equal intervals on the inner side wall of the guide cylinder 311, and four second guide strips 331 are convexly arranged at equal intervals on the outer side wall of the core rod 33. Both the first guide strips 312 and the second guide strips 331 are arranged along the axial direction of the one-way pipe fitting. The first guide strips 312 are located between two adjacent second guide strips 331, and the second guide strips 331 are located between two adjacent first guide strips 312. There are gaps between the first guide strips 312 and the two adjacent second guide strips 331. In actual production, the number of the first guide strips 312 and the second guide strips 331 can both be six or eight.

[0036] An annular abutting ring 313 is formed by inward protrusion on the inner side wall of the valve body 31. The abutting ring 313 and the guide cylinder 311 are fixedly connected by four spaced connecting rods 314. There are water passing holes 315 for water to pass through between two adjacent connecting rods 314. The spring 36 is sleeved on the core rod 33 and outside the guide cylinder 311. The two ends of the spring 36 respectively act on the connecting rod 314 and the pressing plate 34, so that the second sealing ring 35 always has a tendency to abut against the abutting ring 313 to block the water passing hole 315 and close the one-way valve 3.

[0037] The one-way valve 3 is pre-assembled into one body. During installation, the first pipe body 1 is positioned by the equipment and the second pipe body 2 is clamped, so that the inner ends of the first pipe body 1 and the second pipe body 2 are arranged opposite to each other. The one-way valve 3 is inserted into the inner end of the first pipe body 1. The equipment moves the second pipe body 2 to a set position and makes the second pipe body 2 rotate at a high speed, so that heat is generated due to friction between the inner ends of the first pipe body 1 and the second pipe body 2, and the contact surface reaches the molten state, and the first pipe body 1 and the second pipe body 2 are hermetically fixed by friction welding, and the one-way valve 3 is installed between the inner ends of the first pipe body 1 and the second pipe body 2.

[0038] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0039] Although terms such as the first tube body 1, the first step surface 11, the first avoidance groove 12, the first anti-rotation bar 13, the guiding surface 14, the second tube body 2, the second step surface 21, the second avoidance groove 22, the second anti-rotation bar 23, the one-way valve 3, the valve body 31, the guiding cylinder 311, the first guiding bar 312, the abutting ring 313, the connecting rod 314, the water passing hole 315, the first sealing ring 32, the core rod 33, the second guiding bar 331, the pressing plate 34, the second sealing ring 35, the spring 36, and the bolt 37 are used more frequently in this text, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A one-way pipe fitting, comprising a first pipe body (1), a second pipe body (2) and a one-way valve (3), characterized in that, The inner wall of the first pipe body (1) has an annular first step surface (11), the inner wall of the second pipe body (2) has an annular second step surface (21), the one-way valve (3) includes a cylindrical valve body (31), a first sealing ring (32) is sleeved on the outer peripheral wall of the valve body (31), and the first pipe body (1) and the second pipe body (2) are fixedly connected by friction welding so that one end of the valve body (31) abuts against the first step surface (11) and the other end abuts against the second step surface (21), and the first sealing ring (32) is in contact with the inner wall of the first pipe body (1).

2. The one-way pipe fitting according to claim 1, characterized in that, The outer wall of the inner end of the first pipe body (1) has a first avoidance groove (12), the inner wall of the inner end of the second pipe body (2) has a second avoidance groove (22), the groove width of the first avoidance groove (12) along the axial direction of the one-way pipe fitting is greater than the groove width of the second avoidance groove (22), the inner wall of the inner end of the first pipe body (1) is embedded in the second avoidance groove (22), and the outer wall of the inner end of the second pipe body (2) is embedded in the first avoidance groove (12).

3. The one-way pipe fitting according to claim 1, characterized in that, A plurality of first anti-rotation strips (13) are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the first pipe body (1), and a plurality of second anti-rotation strips (23) are protrudingly arranged at equal intervals on the outer peripheral wall of the outer end of the second pipe body (2), and both the first anti-rotation strips (13) and the second anti-rotation strips (23) are arranged along the axial direction of the one-way pipe fitting.

4. A one-way pipe fitting according to claim 1 or 2 or 3, characterized in that, The distance from the first step surface (11) to the end face of the inner end of the first pipe body (1) is greater than the distance from the second step surface (21) to the end face of the inner end of the second pipe body (2), and the first sealing ring (32) is adjacent to the first step surface (11).

5. A one-way pipe fitting according to claim 1 or 2 or 3, characterized in that, The inner wall of the first pipe body (1) also has a conical guiding surface (14), the inner diameter of the first pipe body (1) between the first step surface (11) and the guiding surface (14) is smaller than the inner diameter of the first pipe body (1) between the end face of the inner end and the guiding surface (14), and the first sealing ring (32) is located between the first step surface (11) and the guiding surface (14).

6. A one-way pipe fitting according to claim 1 or 2 or 3, characterized in that, The inner diameter of the inner end of the first pipe body (1) is greater than the inner diameter of the outer end of the first pipe body (1), the inner diameter of the inner end of the second pipe body (2) is greater than the inner diameter of the outer end of the second pipe body (2), the outer peripheral wall of the valve body (31) is in clearance fit with the inner peripheral wall of the inner end of the first pipe body (1), and the outer peripheral wall of the valve body (31) is in clearance fit with the inner peripheral wall of the inner end of the second pipe body (2).

7. A one-way pipe fitting according to claim 1 or 2 or 3, characterized in that, The one-way valve (3) further includes a core rod (33), a pressing plate (34), a second sealing ring (35) and a spring (36). The valve body (31) has a guiding cylinder (311). The core rod (33) passes through the guiding cylinder (311). One end of the core rod (33) is fixedly connected with the pressing plate (34), and the other end is sleeved and fixedly connected with the second sealing ring (35). The spring (36) is sleeved on the core rod (33), and both ends of the spring (36) act on the valve body (31) and the pressing plate (34) respectively, so that the second sealing ring (35) always has a tendency to be sealed against the valve body (31) to close the one-way valve (3).

8. A one-way pipe fitting according to claim 7, characterized in that, A plurality of first guiding strips (312) are convexly arranged at equal intervals on the inner side wall of the guiding cylinder (311). A plurality of second guiding strips (331) are convexly arranged at equal intervals on the outer side wall of the core rod (33). The first guiding strips (312) and the second guiding strips (331) are both arranged along the axial direction of the one-way pipe fitting. The first guiding strips (312) are located between two adjacent second guiding strips (331), and the second guiding strips (331) are located between two adjacent first guiding strips (312). There is a gap between the first guiding strip (312) and two adjacent second guiding strips (331).

9. The one-way pipe fitting according to claim 7, characterized in that, An annular abutting ring (313) is formed by inward protrusion on the inner side wall of the valve body (31). The abutting ring (313) and the guiding cylinder (311) are fixedly connected by a plurality of connecting rods (314) arranged at intervals. There is a water passing hole (315) for water to pass through between two adjacent connecting rods (314). Under the action of the elastic force of the spring (36), the second sealing ring (35) can abut against the abutting ring (313) to block the water passing hole (315) to close the one-way valve (3).

10. A one-way pipe fitting according to claim 7, characterized in that, The pressing plate (34) is fixedly connected with one end of the core rod (33) through a bolt (37). The bolt (37) is arranged along the axial direction of the core rod (33).

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