Self-centering plunger connecting structure and tightening tool thereof

Abstract

The utility model discloses a self-centering plunger connecting structure and a tightening tool thereof. The self-centering plunger connecting structure at least comprises but not limited to a limiting screw, a clamping nut and a crosshead. A first threaded hole matched with the clamping nut is formed in the crosshead, an external thread matched with the first threaded hole is arranged on the outer side wall of the clamping nut, a limiting groove for axially limiting the limiting screw is formed in one end of the clamping nut, and the end of the limiting screw is matched with the structure of the limiting groove. A tightening groove is formed in the end, away from the limiting groove, of the clamping nut. According to the scheme, the adjusting assembly capable of dynamically adjusting the relative position of the plunger and the cylinder body is arranged, the plunger is allowed to automatically adapt and keep the optimal concentricity in the assembling process, and friction and impact damage are reduced.

Description

Technical Field

[0001] The utility model relates to the field of fluid mechanical reciprocating pumps, in particular to a self-centering plunger connection structure and a tightening tool thereof. Background Art

[0002] In traditional plunger pumps, the connection between the plunger and the crosshead usually adopts a rigid connection or a simple floating design. However, under long-term high-pressure working environment, affected by factors such as temperature changes and mechanical vibrations, this type of connection can easily lead to increased wear between the plunger and the cylinder body, as well as stress concentration at the connection point, thereby affecting the working efficiency and service life of the equipment.

[0003] The plunger pump of the prior art, such as Figure 1 As shown, it is divided into a power end 4 and a hydraulic end 2. It is mainly driven by a motor / internal combustion engine 7 through a belt, gear or direct 6 to rotate the crankshaft, and then the connecting rod mechanism in the plunger bin 3 causes the plunger to reciprocate in the cylinder body, converting mechanical energy into hydraulic energy, thereby realizing the pressure test of the system under test. The power end 4 and the hydraulic end 2 are assembled and fixed on the base 5 through the connecting stud 1, and can be used for all kinds of pressure vessels, boilers, pipelines, valves and other places where pressure bursting tests and strength tests are required, for bursting and pressure testing; it can also be used for oil field wellheads and water injection.

[0004] There are several traditional plunger connection methods: one is a rigid direct connection, in which the crosshead 2 is located in the hole of the frame 1, and the plunger 3 is connected to the crosshead 2 through threads, and the shaft at the rear of the threads is positioned by matching with the hole in the crosshead. The rear end of the plunger 3 is tightly matched with the seal 5 in the cylinder body 4, and when the crosshead 2 drives the plunger 3 to reciprocate, work is done on the liquid medium to increase the pressure. The plunger 3 also reciprocates in the seal 5.

[0005] Figure 2 The plunger connection shown is a rigid direct connection, which is connected by threads and positioned by the shaft neck at the front end of the plunger. To ensure the reliability and life of the seal 5 during the long-term reciprocating motion of the plunger, it is necessary to ensure that the movement accuracy of the plunger 5 and the seal 5 is high enough. This requires ensuring the coaxiality of the connection between the crosshead and the plunger, the matching accuracy of the crosshead and the frame, and the connection and assembly accuracy of the frame 1 and the cylinder body 4. This is difficult to ensure in processing and assembly. Under this connection method, after the front end thread of the plunger is tightened, the freedom of the plunger is limited (when the pump is not working, the freedom of the plunger is zero), which may cause uneven force, increase eccentric wear, and affect the life of the sealing pair;

[0006] Another plunger connection method is the front ball head type, such as Figure 3As shown, the concave block 3 is located in the crosshead 2, the convex block 4 spherical surface cooperates with the concave block 3, the right plane of the convex block 4 contacts the front end surface of the plunger 5, a split spherical pad 8 is placed in the front end axial diameter of the plunger 5, and the nut 6 wraps the spherical pad 8 and the front end of the plunger and is tightened on the crosshead 2 through threads. Under this connection method, the plunger's degree of freedom is also limited (when the pump is not working, the plunger's degree of freedom is that it can rotate around the sphere in a small range). After the plunger neck nut is tightened, the plunger and the sealing sub-axis centerline may deviate. Although this connection method plays a more advantageous role in eliminating the error of the crosshead and the plunger being out of alignment during assembly than the rigid plunger connection method, under the multiple influences of processing and assembly errors, this connection method has no degree of freedom in the radial direction and still cannot eliminate the influence of errors well. At the same time, this method has a complex structure and it is difficult to assemble the convex block 4 and the spherical pad 8. Utility Model Content

[0007] The purpose of the utility model is to provide a self-centering plunger connection structure and a tightening tool thereof in view of the above-mentioned deficiencies, so as to solve the problems in the prior art that, under the multiple influences of processing and assembly errors, the front end ball head connection method has no freedom in the radial direction and cannot well eliminate the influence of errors. At the same time, the method has a complex structure and it is difficult to assemble the convex block and the spherical pad.

[0008] The utility model is realized by the following scheme:

[0009] A self-centering plunger connection structure includes at least but not limited to a limit screw, a retaining nut and a crosshead; the crosshead is provided with a first threaded hole matching the retaining nut, the outer wall of the retaining nut is provided with an external thread matching the first threaded hole, one end of the retaining nut is provided with a limit groove for axially limiting the limit screw, the end of the limit screw is matched with the structure of the limit groove, and the end of the retaining nut away from the limit groove is provided with a tightening groove.

[0010] Based on the above-mentioned self-centering plunger connection structure, a centering hole is also provided on the crosshead. The centering hole is provided on the end of the first threaded hole away from the crosshead, and the centering hole is coaxially arranged with the central axis of the first threaded hole. The diameter of the centering hole is not less than the diameter of the first threaded hole.

[0011] Based on the above-mentioned self-centering plunger connection structure, a self-centering component is further arranged behind the locking nut. The self-centering component is sleeved on the outer side of the limit screw, and the size of the self-centering component matches the size of the centering hole.

[0012] Based on the above-mentioned self-centering plunger connection structure, the self-centering component includes a concave pad and a spherical pad, both of which are sleeved on the screw rod of the limit screw, and the end of the screw rod of the limit screw is connected to the plunger.

[0013] Based on the above-mentioned self-centering plunger connection structure, one end of the concave pad is set as a plane structure, and the other end is set as an arc-shaped concave structure. The plane structure side of the concave pad contacts the inner wall of the centering hole, and the arc-shaped concave structure contacts the spherical pad; the concave pad as a whole is a cylindrical structure with one side concave.

[0014] Based on the above-mentioned self-centering plunger connection structure, one side of the spherical pad is a spherical structure, the curvature of the spherical structure is matched with the curvature of the arc-shaped concave structure, and the other end surface of the spherical pad is a plane structure; the spherical structure side of the spherical pad contacts the arc-shaped concave structure side of the concave pad, and the plane structure side of the spherical pad contacts the plunger.

[0015] Based on the above-mentioned self-centering plunger connection structure, the limit screw includes a threaded rod, a smooth rod and a screw head; the threaded rod and the smooth rod are integrally formed, the outer side of the threaded rod is evenly distributed with external threads, and the smooth rod is connected to the center position of the screw head; an arc chamfer is arranged on the end face of the screw head away from the smooth rod.

[0016] Based on the above-mentioned self-centering plunger connection structure, the limit groove is composed of a combination of arc-shaped support columns, and the gap between adjacent arc-shaped support columns is the limit groove. The arc-shaped support column is arranged on the end face of the locking thread that is moved away from the tightening groove. The outer wall of the arc-shaped support column is smoothly arranged, and the height of the arc-shaped support column is not less than the overall thickness of the thread head, so that when the arc-shaped support column contacts the first threaded hole, a gap is left between the threaded head and the inner end face of the first threaded hole.

[0017] Based on the above-mentioned self-centering plunger connection structure, the structure of the limiting groove is a non-circular structure, the tightening groove is an embedded slot arranged at a circumferential position of the locking nut, and the number of the tightening grooves along the circumferential position of the locking thread is at least one.

[0018] The present solution also provides a tightening tool for a self-centering plunger connection structure, which at least includes but is not limited to a sleeve cavity and a rotating armrest, wherein one side of the sleeve cavity is open, the interior of the sleeve cavity is hollow, the rotating armrest is arranged on the side wall of the sleeve cavity away from the opening side, and the opening side of the sleeve cavity is provided with a number of locking columns that is the same as the tightening groove, and the locking columns can be snapped into the tightening groove; the size of the locking columns is not larger than the size of the tightening groove, the length of the hollow cavity of the sleeve cavity is not smaller than the length of the threaded rod of the limit screw, and the overall size of the sleeve cavity is not smaller than the size of the locking thread, so that the sleeve cavity can be snapped into the first threaded hole to clamp the locking nut.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0020] 1. The structure of this solution is provided with an adjustment component that can dynamically adjust the relative position of the plunger and the cylinder body, allowing the plunger to automatically adapt and maintain the optimal concentricity during the assembly process, thereby reducing friction and impact losses.

[0021] 2. The unique floating connection structure of the plunger and the crosshead in this solution can keep the plunger in good concentricity relative to the cylinder body even if it is slightly offset or vibrated in the axial and radial directions when the pump is working, thereby reducing the uneven wear on both sides of the seal pair and the risk of seal failure. At the same time, it can also absorb the impact load from the transmission system and the vibration during the working process, avoiding the strong impact caused by the rigid connection directly acting on the plunger sealing part, and extending the service life of the seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 to Figure 3 All of them are structural schematic diagrams of the prior art;

[0023] Figure 4 It is a schematic diagram of the cross-sectional structure of the utility model as a whole;

[0024] Figure 5 It is a schematic diagram of the three-dimensional cross-sectional structure of the utility model as a whole;

[0025] Figure 6 It is a schematic diagram of the assembly three-dimensional structure of the limit screw and the retaining nut in the utility model;

[0026] Figure 7 This is a schematic diagram of the structure of the limit screw in the utility model;

[0027] Figure 8 This is a schematic diagram of the structure of the locking nut in the utility model;

[0028] Fig. 9 This is a schematic diagram of the structure of the concave pad in the utility model;

[0029] Fig.10 This is a schematic diagram of the structure of the spherical pad in the utility model;

[0030] Fig.11 It is a structural schematic diagram of the special tool in the utility model;

[0031] Description of the drawings: 11. Limit screw; 12. Locating nut; 13. Cross head; 14. First threaded hole; 15. Limiting groove; 16. Tightening groove; 17. Centering hole; 18. Concave pad; 19. Spherical pad; 111. Threaded rod; 112. Smooth rod; 113. Screw head; 114. Arc chamfer; 115. Arc support column; 21. Sleeve cavity; 22. Rotating armrest; 23. Locating column; 24. Plunger. DETAILED DESCRIPTION

[0032] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0033] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0034] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0035] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0036] Example 1

[0037] like Figures 3 to 10 As shown, the utility model provides a technical solution:

[0038] A self-centering plunger connection structure, which at least includes but is not limited to a limit screw 11, a retaining nut 12 and a cross head 13, the cross head 13 is provided with a first threaded hole 14 matching the retaining nut 12, the outer wall of the retaining nut 12 is provided with an external thread matching the first threaded hole 14, one end of the retaining nut 12 is provided with a limit groove 15 for axially limiting the limit screw 11, the end of the limit screw 11 is matched with the structure of the limit groove 15, and the end of the retaining nut 12 away from the limit groove 15 is provided with a tightening groove 16.

[0039] Based on the above structure, a movable kit is formed by inserting the end of the limit screw 11 into the limit groove 15, and then the retaining nut 12 of the movable kit is screwed into the first threaded hole 14, and the tightening groove 16 is inserted into a special tool to lock the limit nut. When the retaining thread is locked, the end of the limit groove 15 conflicts with the inner end of the first threaded hole 14. At this time, there is a gap between the limit screw 11 and the inner end of the first threaded hole 14. At the same time, the limit screw 11 is stuck by the limit groove 15 to prevent it from rotating, thereby finally realizing a floating connection structure for the limit screw 11 in a specified direction.

[0040] As an example, a centering hole 17 is also provided on the crosshead 13. The centering hole 17 is provided on the end of the first threaded hole 14 away from the crosshead 13, and the centering hole 17 is coaxially arranged with the central axis of the first threaded hole 14. The diameter of the centering hole 17 is not less than the diameter of the first threaded hole 14.

[0041] A self-centering component is further provided behind the locking nut 12 . The self-centering component is sleeved on the outer side of the limiting screw 11 , and the size of the self-centering component matches the size of the centering hole 17 .

[0042] Based on the above structure, the self-centering component can be accommodated by providing the centering hole 17, so that the self-centering component can work stably, and the overall structure can also be made more compact.

[0043] As an example, the self-centering assembly may include a concave pad 18 and a spherical pad 19 , both of which are sleeved on the screw rod of the limit screw 11 , and the end of the screw rod of the limit screw 11 is connected to the plunger 24 .

[0044] Based on the above structure, during assembly, the plunger 24 is in a floating state before being connected to the limit screw 11. After the plunger 24 is connected to the limit screw 11 as a whole, since the front end of the plunger 24 is a floating structure, the plunger 24 is in a free state during the tightening process of the plunger 24. The tightening is automatic centering due to the combined action of the concave pad 18 and the spherical pad 19; therefore, even if there are processing and assembly errors between the crosshead 13 and the sealing pair in the cylinder body, this connection method can also eliminate the errors well.

[0045] As an example, one end of the concave pad 18 is set as a plane structure, and the other end is set as an arc-shaped concave structure. The plane structure side of the concave pad 18 contacts the inner wall of the centering hole 17, and the arc-shaped concave structure contacts the spherical pad 19; the concave pad 18 is a cylindrical structure with one side concave.

[0046] One side of the spherical pad 19 is a spherical structure, the curvature of the spherical structure is matched with the curvature of the arc-shaped concave structure, and the other end face of the spherical pad 19 is a planar structure; the spherical structure side of the spherical pad 19 contacts the arc-shaped concave structure side of the concave pad 18, and the planar structure side of the spherical pad 19 contacts the plunger 24.

[0047] Based on the above structure, since the plane structure side of the concave pad 18 is embedded in the centering hole 17, the concave pad 18 can rotate freely in the centering hole 17, the concave pad 18 and the spherical pad 19 are in arc contact, and the center of the concave pad 18 and the center of the spherical pad 19 are connected by a screw. At this time, since the top of the limit screw 11 is restricted by the limit cavity, it will not rotate. In the process of gradually tightening the plunger 24, the end of the plunger 24 gradually contacts the plane structure of the spherical pad 19. Before the plunger 24 is connected to the limit screw 11, it is in a floating state. After the plunger 24 is connected to the limit screw 11 as a whole, since the front end of the plunger 24 is a floating structure, the plunger 24 is in a free state during the tightening process of the plunger 24, and it is automatically centered after tightening.

[0048] As an example, the limit screw 11 may include a threaded rod 111, a smooth rod 112 and a screw head 113; the threaded rod 111 and the smooth rod 112 are integrally formed, the outer side of the threaded rod 111 is evenly distributed with external threads, and the smooth rod 112 is connected to the center position of the screw head 113.

[0049] An arc chamfer 114 is provided on the end surface of the screw head 113 away from the smooth rod 112;

[0050] Based on the above structure, the threaded head is inserted into the limiting cavity, and at the same time, an arc chamfer is formed on the end face of the threaded head to prevent its end face from protruding from the limiting cavity. On the one hand, it avoids interference with the side wall of the first threaded hole 14 during the process of the movable kit being inserted into the first threaded hole 14, thereby damaging the internal thread of the first threaded hole 14. On the other hand, a gap is reserved between the threaded head and the first threaded hole 14, so that after the locking nut 12 is locked, a gap structure is formed between the circumferential position and the first threaded hole 14.

[0051] As an example, the limit groove 15 is composed of an arc support column 115, and the gap between adjacent arc support columns 115 is the limit groove 15. The arc support column 115 is arranged on the end face of the locking thread away from the tightening groove 16. The outer wall of the arc support column 115 is smoothly arranged, and the height of the arc support column 115 is not less than the overall thickness of the thread head, so that when the arc support column 115 contacts the first threaded hole 14, a gap is left between the thread head and the inner end face of the first threaded hole 14.

[0052] Based on the above structure, after the special tool is used to fix and lock the locking nut 12, the arc-shaped support column 115 contacts the inner side wall of the first threaded hole 14. At this time, there is a gap between the thread head and the inner side wall of the first threaded hole 14, so the thread head is in a floating state.

[0053] As an example, the structure of the limiting groove 15 is a non-circular structure, and specifically can be a cross-shaped structure, a straight-line structure, etc. Of course, for the convenience of processing, the limiting groove 15 is usually set to a straight-line structure.

[0054] As an example, the tightening groove 16 is an embedded slot arranged in the circumferential position of the locking nut 12. There is at least one tightening groove 16 arranged along the circumferential position of the locking thread. The locking nut 12 can be rotated by inserting it into the tightening groove 16 through a special tool.

[0055] In this embodiment, four tightening grooves 16 are arranged along the circumferential position of the locking nut 12 , and the four tightening grooves 16 form a cross-shaped structure on two opposite sides.

[0056] Based on the above structure, in order to improve the efficiency of tightening and avoid damage to the special tooling, four-point contact is used for rotation. When the locking thread is rotated, the connecting column of the special tool is inserted into the tightening groove 16. The special tool is rotated to realize the rotation of the locking thread. The torque can be evenly distributed through the four-point locking, which can improve the rotation efficiency and avoid damage to the special tool.

[0057] In this solution, an adjustment component is provided that can dynamically adjust the relative position of the plunger 24 and the cylinder body, allowing the plunger 24 to automatically adapt and maintain optimal concentricity during the assembly process, thereby reducing friction and impact losses.

[0058] At the same time, the unique floating connection structure of the plunger 24 and the crosshead 13 in this solution can maintain good concentricity relative to the cylinder body even if it is slightly offset or vibrated in the axial and radial directions when the pump is working, thereby reducing the uneven wear on both sides of the sealing pair and reducing the risk of seal failure. At the same time, it can also absorb the impact load from the transmission system and the vibration during the working process, avoid the strong impact caused by the rigid connection directly acting on the sealing part of the plunger 24, and extend the service life of the seal.

[0059] Example 2

[0060] like Fig.11 As shown, the utility model provides a technical solution:

[0061] A tightening tool for a self-centering plunger connection structure, which at least includes but is not limited to a sleeve cavity 21 and a rotating armrest 22. One side of the sleeve cavity 21 is open, the interior of the sleeve cavity 21 is hollow, the rotating armrest 22 is arranged on the side wall of the sleeve cavity 21 away from the open side, and the open side of the sleeve cavity 21 is provided with a number of locking columns 23 that is the same as the tightening groove 16, and the locking columns 23 can be inserted into the tightening groove 16.

[0062] As an example, the size of the locking column 23 is not larger than the size of the tightening groove 16, the length of the hollow cavity of the sleeve cavity 21 is not less than the length of the threaded rod 111 of the limit screw 11, and the overall size of the sleeve cavity 21 is not smaller than the size of the locking thread, so that the sleeve cavity 21 can be inserted into the first threaded hole 14 to lock the locking nut 12, and the locking nut 12 can be tightened by rotating the handrail 22.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-centering plunger connection structure, characterized in that: At least includes but is not limited to a limit screw, a retaining nut and a cross head; the cross head is provided with a first threaded hole matching the retaining nut, the outer wall of the retaining nut is provided with an external thread matching the first threaded hole, one end of the retaining nut is provided with a limit groove for axially limiting the limit screw, the end of the limit screw is matched with the structure of the limit groove, and the end of the retaining nut away from the limit groove is provided with a tightening groove.

2. A self-centering plunger connection structure as claimed in claim 1, characterized in that: The crosshead is also provided with a centering hole, which is arranged on the end of the first threaded hole away from the crosshead, and is coaxially arranged with the central axis of the first threaded hole, and the diameter of the centering hole is not less than the diameter of the first threaded hole.

3. A self-centering plunger connection structure as claimed in claim 2, characterized in that: A self-centering component is also arranged behind the locking nut. The self-centering component is sleeved on the outer side of the limit screw, and the size of the self-centering component matches the size of the centering hole.

4. A self-centering plunger connection structure as claimed in claim 3, characterized in that: The self-centering component comprises a concave pad and a spherical pad, both of which are sleeved on the screw rod of the limit screw, and the end of the screw rod of the limit screw is connected to the plunger.

5. A self-centering plunger connection structure as claimed in claim 4, characterized in that: One end of the concave pad is set as a plane structure, and the other end is set as an arc-shaped concave structure. The plane structure side of the concave pad contacts the inner wall of the centering hole, and the arc-shaped concave structure contacts the spherical pad; the concave pad as a whole is a cylindrical structure with one side concave.

6. A self-centering plunger connection structure as claimed in claim 5, characterized in that: One side of the spherical pad is a spherical structure, the curvature of the spherical structure is matched with the curvature of the arc-shaped concave structure, and the other end surface of the spherical pad is a plane structure; the spherical structure side of the spherical pad contacts the arc-shaped concave structure side of the concave pad, and the plane structure side of the spherical pad contacts the plunger.

7. A self-centering plunger connection structure according to any one of claims 1 to 6, characterized in that: The limit screw includes a threaded rod, a smooth rod and a screw head; the threaded rod and the smooth rod are integrally formed, the outer side of the threaded rod is evenly distributed with external threads, and the smooth rod is connected to the center position of the screw head; an arc chamfer is arranged on the end surface of the screw head away from the smooth rod.

8. A self-centering plunger connection structure as claimed in claim 7, characterized in that: The limiting groove is composed of an arc-shaped support column, and the gap between adjacent arc-shaped support columns is the limiting groove. The arc-shaped support column is arranged on the end face of the locking thread away from the tightening groove. The outer wall of the arc-shaped support column is smoothly arranged. The height of the arc-shaped support column is not less than the overall thickness of the thread head, so that when the arc-shaped support column contacts the first threaded hole, a gap is left between the thread head and the inner end face of the first threaded hole.

9. A self-centering plunger connection structure as claimed in claim 8, characterized in that: The structure of the limiting groove is a non-circular structure, and the tightening groove is an embedded slot arranged at a circumferential position of the locking nut. At least one tightening groove is arranged along the circumferential position of the locking thread.

10. A tightening tool for the self-centering plunger connection structure according to any one of claims 1 to 9, characterized in that: At least includes but is not limited to a sleeve cavity and a rotating armrest, one side of the sleeve cavity is opened, the interior of the sleeve cavity is hollow, the rotating armrest is arranged on the side wall of the sleeve cavity away from the opening side, and the opening side of the sleeve cavity is provided with a number of locking columns that is the same as the tightening groove, and the locking columns can be inserted into the tightening groove; the size of the locking columns is not larger than the size of the tightening groove, the length of the hollow cavity of the sleeve cavity is not smaller than the length of the threaded rod of the limit screw, and the overall size of the sleeve cavity is not smaller than the size of the locking thread, so that the sleeve cavity can be inserted into the first threaded hole to lock the locking nut.

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