A light rod righting device

Abstract

This utility model belongs to the technical field of straightening devices, specifically relating to a polished rod straightening device. The device includes an upper connector for connection to a packing box and a lower connector for connection to a wellhead Christmas tree. The center of the upper and lower connectors forms a through-hole in the polished rod. It also includes a straightening body composed of a ball bearing sleeve and several balls evenly distributed on the ball bearing sleeve for rolling contact with the polished rod. The straightening body is detachably and fixedly installed inside the polished rod hole. During assembly, the straightening body only needs to be embedded into the polished rod hole, and then synchronously fixed by connecting the upper and lower connectors, improving detachability, reducing assembly difficulty, increasing assembly efficiency, and easily ensuring assembly quality. When replacing damaged balls, the connection of the upper and lower connectors is disassembled, the straightening body is removed, and the balls are replaced individually or the entire straightening body is replaced, simplifying the maintenance process and reducing maintenance costs. Through the directional docking of the upper and lower connectors, combined with the straightening body and its fixing structure, the three work together to ensure the coaxiality of the polished rod movement.

Description

Technical Field

[0001] This utility model belongs to the technical field of straightening devices, specifically relating to a straightening device for a smooth pole. Background Technology

[0002] In oilfield production, the polished rod is a crucial component connecting the sucker rod and the suspension cable. During the reciprocating motion of the pumping unit, the suspension cable is prone to irregular oscillations, causing the polished rod's trajectory to deviate. Under the combined influence of well conditions, loads, and assembly factors, the suspension point of the pumping unit experiences angular and horizontal displacements relative to the wellhead center, causing the polished rod axis to deviate from the wellhead axis. This easily leads to uneven wear of the polished rod and packing, resulting in accelerated packing wear, shortened service life, and in severe cases, wellhead leaks and other accidents, increasing the frequency of wellhead maintenance and packing replacement. Simultaneously, the polished rod is subjected to alternating loads over long periods, and uneven wear can easily cause fatigue failure and breakage, leading to well-running accidents.

[0003] To address these issues, a centralizing device is typically installed at the wellhead. One type, the sliding sleeve centralizing device, involves installing a sliding sleeve within the polished rod channel of the wellhead equipment. This sleeve provides rigid support and centralizes the polished rod, but it exhibits significant friction with the rod, leading to wear. Another type, the rolling centralizing device, usually includes a centralizing body fitted onto the sucker rod. The outer circumference of the centralizing body is equipped with rollers or balls for rolling contact with the inner wall of the tubing or the wellhead tree channel. The centralizing body reciprocates up and down with the sucker rod, and prolonged use can cause wear on the tubing or wellhead equipment.

[0004] As an improvement, Chinese utility model patent CN202689990U, authorized on January 23, 2013, discloses a rolling polished rod centering and alignment wellhead packing box for pumping unit wells. The box includes a packing box, a rolling polished rod centering device, and a short connector assembly. The packing box includes a packing cap, packing, and a packing gland seat. The rolling polished rod centering device includes an upper plate, a lower plate, and ball bearings. The upper and lower plates are circular, with a polished rod hole at their center for the polished rod to pass through. Holes for installing ball bearings are evenly distributed along their concentric circumferences. The upper and lower plates are connected by screws, allowing a portion of the ball bearing's volume to extend from the holes into the polished rod hole. The short connector assembly includes a connecting cap, a welded short connector, and a lower eccentric short connector. During assembly, the welded short connector is fitted into the connecting cap and welded to the lower cavity of the lower plate. The connecting cap is threadedly connected to the lower eccentric short connector. The lower plate is threadedly connected to the packing gland seat. In use, the packing box and the rolling polished rod centralizing device assembly are connected to the wellhead tubing threaded through the lower eccentric short joint. The polished rod passes through the center of the short joint assembly, the centralizing device and the packing box in sequence.

[0005] However, in the above scheme, the upper and lower buckle plates are connected by screws. After the ball bearings wear out, the entire buckle plate needs to be disassembled for replacement, which is cumbersome. The lower buckle plate and the welded short joint are non-removable welded connections. If the ball bearing holes of the lower buckle plate wear out, the entire assembly needs to be replaced, resulting in high maintenance costs. The assembly of the rolling smooth rod straightening device and the short joint assembly requires four levels of connection: "lower buckle plate - welded short joint - connecting buckle cap - lower eccentric short joint". The assembly steps are numerous, and the cumulative processing errors at each level of connection will lead to an increase in the coaxiality deviation of the smooth rod channel, weakening the straightening effect. Utility Model Content

[0006] The purpose of this invention is to provide a smooth rod straightening device to solve the problems of complex structure of existing ball bearing straightening devices, which makes it difficult to control assembly accuracy and has poor assembly and maintenance convenience.

[0007] To achieve the above objectives, the smooth rod straightening device of this utility model adopts the following technical solution: A polished rod straightening device includes an upper connector for connecting to a packing box and a lower connector for connecting to a wellhead tree. The center of the upper and lower connectors after connection forms a through polished rod hole. The device also includes a straightening body composed of a ball sleeve and a plurality of balls evenly distributed on the ball sleeve for rolling contact with the polished rod. The straightening body is detachably and fixedly installed in the polished rod hole.

[0008] Furthermore, the straightening device also includes a pressure cap, the inner cavity of which has a stepped structure. One end of the upper connector and the lower connector is provided with a radially outward protruding flange. The pressure cap and the lower connector are threaded together so that the flange mates with the stepped surface of the inner cavity of the pressure cap, so that the end faces of the upper connector and the lower connector abut against each other.

[0009] Furthermore, a limiting protrusion is provided in either the upper or lower connector's optical rod hole, and the straightening body is clamped in the optical rod hole through the limiting protrusion and another end face opposite to the limiting protrusion.

[0010] Furthermore, there is a gap e between the outer wall of the upper connector and the inner wall of the pressure cap, and e satisfies the condition: 2mm≤e≤10mm.

[0011] Furthermore, the straightening body also includes a straightening sleeve that seals with the inner wall of the upper or lower connector. The two ends of the straightening sleeve are respectively provided with stop structures, and the ball sleeve is disposed inside the straightening sleeve through the stop structures.

[0012] Furthermore, the stop structure includes a stop protrusion ring at one end of the straightening sleeve and a retaining spring at the other end.

[0013] Furthermore, the ball sleeve is provided with a plurality of ball holes that penetrate the ball sleeve wall for accommodating the ball, and each ball hole is evenly distributed along the circumference of the ball sleeve, linearly arranged in the axial direction, and the circumferentially adjacent ball holes are arranged in an axially staggered manner.

[0014] Furthermore, the diameter of the ball bearing hole gradually decreases from the outside to the inside along the radial direction of the ball bearing sleeve.

[0015] Furthermore, a sealing structure is provided between the abutting end faces of the upper and lower connectors.

[0016] Furthermore, the pressure cap includes a screw-on end and a threaded connection end, the inner diameter of the screw-on end is smaller than the inner diameter of the threaded connection end, and the transition between the two forms the stepped surface; the screw-on end has a prismatic structure.

[0017] The beneficial effects of this utility model are as follows: The polished rod straightening device provided by this utility model is an improvement on the existing technology. The upper and lower connectors are respectively oriented to the existing packing box and wellhead Christmas tree components at the wellhead, forming a two-point positioning installation structure, which can quickly realize the assembly with the wellhead components; the polished rod hole formed after the upper and lower connectors are connected is coaxial with the original polished rod movement path at the wellhead, limiting the radial offset range of the polished rod and avoiding the skew problem caused by the offset of the device itself; the straightening body is fixedly installed in the polished rod hole, avoiding displacement or shaking of the straightening body itself during operation, ensuring the stable contact position between the ball and the polished rod, and making the straightening effect continuous and reliable; the straightening body, through the structure of the roller sleeve and multiple balls, ensures that the balls are evenly distributed along the circumference of the polished rod, realizing radial constraint on the polished rod, improving the uniformity of force on the polished rod and the straightening stability, and reducing the friction and wear between the straightening body and the polished rod. During assembly, the straightener is simply inserted into the hole of the smooth rod, and then synchronous fixation is achieved by connecting the upper and lower connectors. This simplifies the structure, reduces assembly difficulty, simplifies the assembly process, improves assembly efficiency, and makes it easy to ensure assembly quality. When replacing damaged balls, the connection between the upper and lower connectors is disassembled, the straightener is removed, and the damaged balls are replaced individually or the straightener is replaced as a whole. This improves disassembly, simplifies the maintenance process, and reduces maintenance costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the optical rod straightening device in this utility model; Figure 2 This is a partial enlarged view of the structure of the optical rod straightening device in this utility model.

[0019] Figure 3 This is a schematic diagram illustrating the application of the optical pole straightening device in this utility model.

[0020] In the diagram: 1. Upper connector; 11. Flange; 2. Pressure cap; 3. Lower connector; 31. Protrusion; 4. Straightening sleeve; 41. Convex ring; 5. Ball sleeve; 6. Ball; 7. Snap ring; 8. Sealing gasket; 9. Wellhead Christmas tree; 10. Packing box; 11. Polished rod. Detailed Implementation

[0021] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0022] To address the problems of complex structures in existing ball bearing straightening devices, which lead to difficulties in controlling assembly accuracy and poor ease of assembly and maintenance, the present invention provides a smooth rod straightening device with a modular structure consisting of an upper connector, a straightening body, and a lower connector. During assembly, the straightening body only needs to be embedded into the smooth rod hole of the upper and lower connectors, and then synchronously fixed by directional connection between the upper and lower connectors and the packing box and the wellhead tree. This reduces assembly complexity, improves assembly efficiency, and makes it easier to ensure assembly accuracy. At the same time, it improves disassembly, simplifies the maintenance process, and reduces maintenance costs.

[0023] An embodiment of the optical rod straightening device in this utility model: like Figure 1 As shown, and refer to Figure 3 The polished rod straightening device provided by this utility model includes an upper connector 1 for connecting to the packing box 10 and a lower connector 3 for connecting to the wellhead tree 9. The center of the upper connector 1 and the lower connector 3 after connection forms a polished rod 11 hole that runs through the device along its axial direction, allowing the polished rod 11 to pass through. The upper connector 1 and the lower connector 3 are respectively oriented to the existing wellhead components, the packing box 10 and the wellhead tree 9, forming a two-point positioning installation structure, which can quickly achieve assembly with the wellhead components. The polished rod 11 hole formed after the upper connector 1 and the lower connector 3 are connected is coaxial with the original polished rod 11 movement path at the wellhead, limiting the radial offset range of the polished rod 11, avoiding the skew problem caused by the device's own offset, and simplifying the assembly process.

[0024] The lower connector 3 is a hollow tubular structure. One end of the lower connector 3 is provided with an internal thread for threaded connection with the wellhead tree 9, and the other end is provided with an external thread. The inner wall of the lower connector 3 is provided with an annular protrusion 31 near the end of the internal thread extension. The axial end face of the annular protrusion 31 is a plane.

[0025] The upper connector 1 is a hollow tubular structure. One end of it is provided with an external thread for threaded connection with the packing box 10, and the other end is provided with a flange 11 protruding outward in a radial direction. The inner diameter of the upper connector 1 is not greater than the inner diameter of the annular protrusion 31.

[0026] The pressure cap 2 has a screw-on end and a threaded connection end. The threaded connection end is used to connect with the external thread of the lower connector 3. The inner cavity of the pressure cap 2 has a stepped structure, with the inner diameter of the screw-on end being smaller than the inner diameter of the threaded connection end. A stepped surface is formed at the transition between the threaded connection end and the screw-on end in the inner cavity of the pressure cap 2. When the pressure cap 2 is threadedly connected to the lower connector 3, its stepped surface mates with the flange 11 of the upper connector 1. After the pressure cap 2 is tightened, the end faces of the upper connector 1 and the lower connector 3 abut against each other, thus compressing the upper connector 1. The mating of the flange 11 of the upper connector 1 with the stepped surface of the pressure cap 2, combined with the threaded connection between the pressure cap 2 and the lower connector 3, forms a dual constraint of axial compression and radial limiting, ensuring that the end faces of the upper and lower connectors 3 are tightly abutted. During disassembly, loosening the nut in the reverse direction releases the compression constraint on the upper connector 1, thereby directly separating the upper connector 1 from the lower connector 3. The one-piece molded stepped surface structure has high strength, ensuring continuous compression of the flange 11 of the upper connector 1.

[0027] To facilitate the tightening of the cap 2, the outer periphery of the tightening end of the cap 2 has a prismatic structure. Specifically, it can be a quadrilateral, hexagonal, or octagonal structure. Of course, it can also be other structures that are compatible with wrenches commonly used in wellhead operations.

[0028] There is a gap e between the outer wall of the upper connector 1 and the inner wall of the pressure cap 2. Specifically, there is a gap e between the inner surface of the screw end of the pressure cap 2 and the outer surface of the upper connector 1, and the gap range satisfies: 2mm≤e≤10mm. If the force direction of the suspension device is not coaxial with the wellhead, and the polished rod 11 still deviates after passing through the straightening area, the pressure cap 2 can be loosened, and the upper connector 1 and packing box 10 can be radially fine-tuned within the gap range to compensate for the deviance of the polished rod 11 and keep the polished rod 11 coaxial with the wellhead; after the fine-tuning is completed, the pressure cap is tightened to fix the fine-tuned position.

[0029] After the lower connector 3 and the pressure cap 2 are threaded together, an axial gap is formed between the annular protrusion 31 and the lower end face of the upper connector 1. This axial gap constitutes the installation space for the straightener. One end of the straightener abuts against the upper end face of the annular protrusion 31, and the other end abuts against the lower end face of the upper connector 1. The upper surface of the annular protrusion 31 and the lower end face of the upper connector 1 form an axial limit on the straightener. It should be understood that the height of the limiting protrusion 31 (i.e., the distance between the limiting protrusion 31 and the end face of the lower connector 3) should match the axial thickness of the straightener to ensure that when the limiting protrusion 31 mates with the end face of the upper connector 1, it can form a clamping space that fits snugly against the straightener, thereby preventing the straightener from shifting.

[0030] The centralizing body is fixedly installed in the hole of the polished rod 11 by axial clamping of the limiting protrusion 31 with the corresponding end face. The axial preload after the upper and lower connectors 3 are connected is used to limit the centralizing body to a preset position in the hole of the polished rod 11. Combined with the radial constraint of the hole of the polished rod 11, the position of the centralizing body is prevented from being unstable during operation, so that the centralizing effect is continuous and reliable. At the same time, since the centralizing body is fixed, wear on the wellhead is avoided when the polished rod 11 moves up and down. During assembly, the centralizing body only needs to be inserted into the hole of the polished rod 11, and then the upper and lower connectors 3 are connected to achieve synchronous clamping and fixing of the centralizing body, which reduces the assembly difficulty, simplifies the assembly process, improves the assembly efficiency, and makes it easy to ensure the assembly quality. During maintenance, only the pressure cap 2 needs to be loosened and the upper and lower connectors 3 need to be separated to release the clamping and fixing of the centralizing body, and the centralizing body can be directly removed to replace the damaged ball bearing 6. The operation is convenient and the disassembly is improved.

[0031] In other embodiments, the flange is provided on the lower connector and the limiting protrusion is provided on the upper connector; or, the inner walls of both the upper and lower connectors are provided with radially protruding protrusions, and after the upper and lower connectors are threadedly connected, the centering body is limited by the opposite end faces of the protrusions of the two.

[0032] like Figure 1 and Figure 2 As shown, the centering body includes a ball sleeve 5 and a plurality of balls 6 evenly distributed on the ball sleeve 5 for rolling contact with the guide rod 11. Specifically, the ball sleeve 5 is a cylindrical structure with a plurality of ball holes penetrating the wall of the ball sleeve 5 for accommodating the balls 6. The ball holes are evenly distributed circumferentially along the ball sleeve 5, linearly arranged axially, and adjacent circumferential ball holes are axially staggered. The diameter of the ball holes gradually decreases radially from the outside to the inside of the ball sleeve 5, thereby ensuring that the balls 6 are inserted radially from the outside of the ball sleeve 5. A portion of the balls 6 protrudes from the inner surface of the ball sleeve 5, and all balls 6 protrude from the inner surface of the ball sleeve 5 at the same height. It should be understood that the diameter of the ball holes matches the size of the balls to ensure that the balls can only rotate around their own center, avoiding slippage or jamming, and ensuring the stability of the rolling contact. In other embodiments, the ball holes are evenly distributed circumferentially along the ball sleeve and arranged in a continuous spiral in the axial direction.

[0033] The rolling balls 6 and the smooth rod 11 form rolling friction, reducing the frictional resistance between the straightener and the smooth rod 11 and reducing the wear on the surface of the smooth rod 11. The axially linearly arranged rolling balls 6 can effectively increase the straightening contact range with the smooth rod 11 and improve the straightening stability. The structure of the straightener with the rolling sleeve and multiple rolling balls 6 ensures that the rolling balls 6 are evenly distributed along the circumference of the smooth rod 11, realizing radial constraint on the smooth rod 11 and improving the uniformity of force on the smooth rod 11. The circumferentially adjacent staggered arrangement makes the contact points of the rolling balls 6 evenly staggered along the axial direction of the smooth rod 11, avoiding excessive local force on the smooth rod 11 and causing surface wear. When replacing the damaged rolling balls 6, the connection of the upper and lower joints 3 is disassembled, the straightener is taken out, and the damaged rolling balls 6 are replaced individually or the entire straightener is replaced. The maintenance process is simple and the maintenance cost is reduced.

[0034] As a further embodiment, the straightening body also includes a straightening sleeve 4 that seals against the inner wall of the lower connector 3. The straightening sleeve 4 has stop structures at both ends, and the ball sleeve 5 is disposed within the straightening sleeve 4 via the stop structures. Specifically, the straightening sleeve 4 has a tubular hollow structure, with a protruding ring 41 at one end and an annular groove at the other end for engaging with the retaining spring 7. One end of the ball sleeve 5 abuts against the upper surface of the protruding ring 41, and the other end is limited by the engagement of the retaining spring 7 with the annular groove. In this embodiment, the retaining spring 7 and the protruding ring 41 constitute the stop structure of the ball sleeve 5. It should be understood that the spacing of the stop structures matches the axial dimension of the ball sleeve 5. When the straightening body is installed in the installation space between the protrusion 31 of the lower connector 3 and the lower end face of the upper connector 1, one end of the straightening sleeve 4 abuts against the upper end face of the protrusion 31 of the lower connector 3, and the other end abuts against the lower end face of the upper connector 1. The stop structure fixes the position of the ball sleeve 5 to prevent it from moving axially during the reciprocating motion of the guide rod 11, ensuring that the ball 6 always maintains uniform contact with the guide rod 11. During assembly, the ball sleeve 5 can be pre-installed in the straightening sleeve 4 through the stop structure and then installed into the hole of the guide rod 11 as a whole, which improves the assembly efficiency.

[0035] In this embodiment, the straightening sleeve 4, the ball sleeve 5, and the ball 6 are all made of high carbon steel, thus having high hardness and wear resistance.

[0036] To ensure a tight seal after the upper connector 1 and lower connector 3 abut against each other, a sealing structure is provided on the abutting end faces of the lower connector 3 and the upper connector 1. In this embodiment, a groove is provided on the abutting end face of the lower connector 3, and a sealing element is embedded in the groove. Specifically, the sealing element is a sealing gasket 8 or a sealing ring. In other embodiments, the sealing gasket 8 can be directly provided on the abutting end face without the need for a groove. The thread preload of the pressure cap 2 provides continuous contact pressure for the sealing element, making the fit between the upper connector 1 and the lower connector 3 tighter, reducing relative displacement caused by vibration, further ensuring the coaxiality of the smooth rod hole, and avoiding the skewing of the smooth rod caused by slight displacement of the connector.

[0037] like Figure 1 and Figure 3As shown, in use, the polished rod straightening device provided by this utility model has the lower connector 3 connected to the wellhead Christmas tree 9, the upper connector 1 connected to the packing box 10, and the polished rod 11 passing through the central through hole. The straightening of the polished rod 11 by the straightening body eliminates axial misalignment in the downhole portion. If the force direction of the suspension cable is not coaxial with the wellhead, causing the polished rod 11 to still deviate after passing through the straightening area, the pressure cap 2 is loosened, and the upper connector 1 and packing box 10 are radially fine-tuned to achieve coaxiality between the polished rod 11 and the packing box 10. Through the dual effects of straightening by the straightening body and radial fine-tuning, uniform contact between the polished rod 11 and the packing box 10 is ensured, preventing uneven wear.

[0038] Finally, it should be noted that the above are merely preferred embodiments of this utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some technical features, or organically combine different specific implementation methods to create the specific implementation methods shown in the accompanying drawings. Of course, those skilled in the art can also create other specific implementation methods not shown in the accompanying drawings. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A polished rod straightening device, comprising an upper connector for connection to a packing box and a lower connector for connection to a wellhead Christmas tree, wherein the upper and lower connectors, after being connected, form a through-hole in the polished rod, characterized in that: It also includes a straightening body consisting of a ball sleeve and a plurality of balls evenly distributed on the ball sleeve for rolling contact with the guide rod, the straightening body being detachably and fixedly installed in the guide rod hole.

2. The rod straightening device according to claim 1, characterized in that: The straightening device also includes a pressure cap, the inner cavity of which has a stepped structure. One end of the upper connector and the lower connector is provided with a radially outward protruding flange. The pressure cap and the lower connector are threaded together so that the flange mates with the stepped surface of the inner cavity of the pressure cap, so that the end faces of the upper connector and the lower connector abut against each other.

3. The rod straightening device according to claim 2, characterized in that: A limiting protrusion is provided in either the upper or lower connector's optical rod hole, and the straightening body is clamped in the optical rod hole through the limiting protrusion and another end face opposite to the limiting protrusion.

4. The rod straightening device according to claim 2, characterized in that: There is a gap e between the outer wall of the upper connector and the inner wall of the pressure cap, and e satisfies the condition: 2mm≤e≤10mm.

5. The rod straightening device according to any one of claims 1 to 4, characterized in that: The straightening body also includes a straightening sleeve that seals with the inner wall of the upper or lower connector. The two ends of the straightening sleeve are respectively provided with a stop structure, and the ball sleeve is disposed inside the straightening sleeve through the stop structure.

6. The rod straightening device according to claim 5, characterized in that: The stop structure includes a stop protrusion ring at one end of the straightening sleeve and a retaining spring at the other end.

7. The rod straightening device according to any one of claims 1 to 4, characterized in that: The ball sleeve is provided with a plurality of ball holes that penetrate the ball sleeve wall for accommodating the balls. Each ball hole is evenly distributed along the circumference of the ball sleeve, linearly arranged in the axial direction, and adjacent ball holes in the circumference are arranged in an axially staggered manner.

8. The rod straightening device according to claim 7, characterized in that: The diameter of the ball bearing hole gradually decreases from the outside to the inside along the radial direction of the ball bearing sleeve.

9. The rod straightening device according to any one of claims 2 to 4, characterized in that: A sealing structure is provided between the abutting end faces of the upper and lower connectors.

10. The rod straightening device according to any one of claims 2 to 4, characterized in that: The pressure cap includes a screw-on end and a threaded connection end. The inner diameter of the screw-on end is smaller than the inner diameter of the threaded connection end, and the transition between the two forms the stepped surface. The screw-on end has a prismatic structure.

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