An oil pumping polished rod

Abstract

The utility model discloses an oil pumping polished rod, including the upsetting end head and the not upsetting end head of being located two ends respectively and the rod body between the upsetting end head and the not upsetting end head, the rod body includes the alloy coating section in the middle and the no coating section at both sides, and the area of alloy coating section is equipped with the transition section close to the no coating section, in the plane of the outer circumferential surface of the rod body, the alloy coating edge of the junction of transition section and the no coating section is a uniformly distributed wavy curve. Through the targeted design of the coating edge structure of the junction between the hard alloy coating and the base body of the nickel base alloy coating oil pumping polished rod, avoid the centralized mutation of the material composition and the hardness of the alloy coating oil pumping polished rod in the position of the existing technology flush boundary both ends, make the performance of oil pumping polished rod get further improvement, thereby realize that oil pumping polished rod obtains longer life.

Description

Technical Field

[0001] This utility model belongs to the field of artificial oil extraction equipment, specifically relating to a sucker rod. Background Technology

[0002] In artificial oil recovery systems, the sucker rod is a crucial oil production component, and its wear resistance and corrosion resistance are extremely important. Existing sucker rod standards such as API 11B and SY / T 5029 employ a thermal spraying-remelting method to prepare alloy coatings, typically nickel-based self-fluxing alloy coatings, on the surface of the sucker rod substrate. The high hardness of the alloy coating improves the wear resistance of the sucker rod, while its corrosion resistance effectively enhances its corrosion resistance. The thermal spraying-remelting process involves two steps: first, molten nickel-based alloy powder is thermally sprayed onto the sucker rod substrate surface using a spray gun; second, a medium-frequency induction heating coil is used to remelt the previously sprayed alloy coating at a high temperature of over 900 degrees Celsius. This process seals the pores on the surface of the thermally sprayed coating, significantly improving the surface quality of the alloy coating and forming a metallurgical bond between the alloy coating and the sucker rod substrate. The sucker rod consists of three main parts from one end to the other: an upset end, a rod body, and an un-upset end. Both the upset end and the un-upset end are threaded. The outer diameter of the un-upset end is basically the same as that of the rod body, while the outer diameter of the upset end is significantly larger than that of the rod body.

[0003] During the alloy coating preparation process, to prevent deformation of the connecting threads after heating, and considering the size limitations and processing influence of the large diameter of the upset end on the medium-frequency induction heating coil, the preparation length of the alloy coating is limited. This means the alloy coating can only be mainly located in the middle of the sucker rod, leaving a section of the rod without alloy coating near both the upset and un-upset ends. Furthermore, considering that the rod near the un-upset end is also used for clamping and fixing the sucker rod, to prevent damage to the high-hardness alloy coating from the clamp and subsequent accelerated fatigue failure in later service, an uncoated area is also left at the un-upset end. In existing alloy-coated sucker rod processing, based on actual coating preparation costs, the end face of the alloy coating is flush. This results in the edge of the alloy coating forming a straight line perpendicular to the axis after unfolding the outer circumference of the interface between the hard alloy coating and the substrate into a plane. Compared to the substrate of the sucker rod, the alloy coating has significantly higher hardness and significantly lower toughness. Therefore, due to the significant difference in material and hardness on both sides of the interface between the cemented carbide coating and the substrate, the flush section at the junction of the cemented carbide coating and the substrate on the sucker rod becomes a new abrupt interface. This flush section further concentrates the abrupt change, making this location a dangerous point for fatigue failure and gradually becoming a new problem threatening the alloy-coated sucker rod. Therefore, there is a need to develop a sucker rod with a novel structure. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a sucker rod. Through targeted design of the coating edge structure at the interface between the hard alloy coating and the substrate, the abrupt change at the coating-substrate interface is mitigated, thereby further improving the performance of the sucker rod.

[0005] The present invention relates to a sucker rod, which adopts the following main technical solution: The sucker rod includes an upset end and an unupset end located at both ends, and a rod body located between the upset end and the unupset end. The rod body includes an alloy-coated section in the middle and uncoated sections on both sides. The alloy-coated section includes an alloy coating on the rod body substrate and surface. The uncoated sections on both sides of the alloy-coated section are close to the upset end and the unupset end, respectively. The outer diameter of the rod body substrate surface of the alloy-coated section is smaller than the outer diameter of the rod body of the uncoated section. A transition section is provided in the region of the alloy-coated section near the uncoated section. The outer diameter of the rod body substrate of the transition section gradually increases towards the uncoated section. In the plane unfolded on the outer circumferential surface of the rod body, the edge of the alloy coating at the junction of the transition section and the uncoated section is a uniformly distributed wavy curve.

[0006] Furthermore, the wavy curve of the alloy coating edge at the junction of the transition section and the uncoated section is continuous and without sharp corners.

[0007] Furthermore, on the wavy curve of the alloy coating edge at the junction of the transition section and the uncoated section, the positional difference between any two protruding end points in the direction of the sucker rod axis shall not exceed 5 mm, and the positional difference between any two concave end points in the direction of the sucker rod axis shall not exceed 5 mm.

[0008] Furthermore, the distance between any protruding end point and any recessed end point on the wavy curve in the direction of the axial direction of the sucker rod body shall not exceed 20 mm.

[0009] Furthermore, the distance between any two adjacent protruding and concave endpoints on the wavy curve in the direction of the rod axis does not exceed 1 / 2 of its distance in the direction of the circumference.

[0010] Furthermore, the surface roughness of both the alloy-coated section and the uncoated section is 0.2-0.8 micrometers.

[0011] Furthermore, the outer diameters of the alloy-coated section and the uncoated section are the same.

[0012] Furthermore, the coating thickness of the alloy coating section of the rod is 0.2-0.5 mm.

[0013] Compared with the prior art, the oil extraction rod of this utility model application has the following advantages: First, this invention optimizes the interface between the alloy coating edge and the sucker rod substrate on both sides of the sucker rod from a flush circumference to a wider, undulating strip-like region, effectively mitigating the abrupt change between the coating and the substrate. Within the plane unfolded on the outer circumference surface of the rod, the alloy coating edge at the junction of the transition section and the uncoated section forms a uniformly distributed wavy curve, continuous and without sharp corners. This structural optimization transforms the abrupt change between the coating and the substrate from a flush interface to a transitional interface with a certain gradient, undulating along the axial direction. This effectively mitigates the difference in material and hardness on both sides of the interface, transforming the abrupt change from a flush cross-section into a transitional region of a certain width, thereby improving the mechanical properties at this location.

[0014] Secondly, this invention defines the wavy curve of the alloy coating edge at the junction of the transition section and the uncoated section, taking into account both the processing difficulty of the alloy coating and its impact on mechanical properties. By defining the positional differences of any two protruding endpoints, any two concave endpoints, and any protruding endpoint and any concave endpoint along the axis of the sucker rod on the wavy curve, the wavy curve of the alloy coating edge can avoid the risk of fatigue failure caused by abrupt interface changes, while also taking into account the processing difficulty, and preventing new performance problems caused by large local protrusions or depressions in the alloy coating.

[0015] Third, this invention adapts the outer diameter of the sucker rod substrate at different locations by limiting the outer diameter of the alloy-coated section to be smaller than that of the uncoated section, ensuring that the outer diameter of the final sucker rod product remains consistent across different locations. Furthermore, the outer diameter of the substrate in the transition section gradually increases towards the uncoated section, thus providing a certain transitional effect in the radial direction of the alloy coating edge at the junction of the transition and uncoated sections, further improving the abrupt change between the alloy coating and the substrate. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the oil sucker rod of this utility model.

[0017] Figure 2 This is a schematic diagram of the alloy coating edge at the junction of the transition section and the uncoated section on the side of the un-upset end of the sucker rod of this utility model.

[0018] Figure 3 This is a schematic diagram of the unfolded plane of the alloy coating edge at the junction of the transition section and the uncoated section on the side of the un-upset end of the sucker rod of this utility model. Detailed Implementation

[0019] See Figures 1-3This utility model discloses a sucker rod 1, comprising an upset end 10 and an unupset end 11 located at both ends, and a rod body 12 located between the upset end 10 and the unupset end 11. The rod body 12 includes an alloy-coated section 120 located in the middle and uncoated sections 121 located on both sides. The alloy-coated section 120 includes an alloy coating on the rod body substrate and surface. The uncoated sections 121 on both sides of the alloy-coated section 120 are located close to the upset end 10 and the unupset end 11, respectively. The outer diameter of the rod body substrate surface of the alloy-coated section 120 is smaller than that of the uncoated section 121. Both sides of the uncoated section 121 have transition sections 1201. The surface of the transition section 1201 is coated with an alloy coating, forming part of the alloy-coated section 120. The length of the transition section 1201 ranges from 0.1 to 0.2 meters. The outer diameter of the rod base of the transition section 1201 gradually increases towards the uncoated section 121, reaching the same size as the uncoated section 121 at the junction. The alloy coating edge 1202 at the junction of the transition section 1201 and the uncoated section 121 has a wavy curve. The wavy curve structure of the alloy coating edge 1202 at both ends of the smooth rod is consistent. Figure 2 The structure of the alloy coating edge at the junction of the transition section and the uncoated section on the side of the un-upset end of the sucker rod is illustrated as an example. In the plane unfolded on the outer circumferential surface of the rod, the alloy coating edge 1202 at the junction of the transition section 1201 and the uncoated section 121 is a uniformly distributed wavy curve, which transforms the change between the coating and the substrate from a flat interface with a sudden change to a transition interface with a certain gradient that fluctuates back and forth in the axial direction.

[0020] Furthermore, the wavy curve of the alloy coating edge 1202 at the junction of the transition section 1201 and the uncoated section 121 is continuous and without sharp corners, which further effectively reduces stress concentration.

[0021] Furthermore, on the wavy curve of the alloy coating edge 1202 at the junction of the transition section 1201 and the uncoated section 121, the wavy curve includes multiple protruding ends protruding towards the uncoated section and multiple recessed ends protruding away from the uncoated section. The positional difference between any two protruding end endpoints in the direction of the sucker rod axis does not exceed 5 mm, and the positional difference between any two recessed end endpoints in the direction of the sucker rod axis does not exceed 5 mm.

[0022] Furthermore, the distance between any protruding end point and any recessed end point on the wavy curve in the direction of the axial direction of the sucker rod body shall not exceed 20 mm.

[0023] The aforementioned limitations on the size and position of the wavy curve ensure that the wavy curve at the edge of the alloy coating can avoid the risk of fatigue failure caused by abrupt interface changes, while also taking into account the processing difficulty, and preventing new performance problems caused by large protrusions or depressions in the alloy coating in certain areas.

[0024] Furthermore, the distance between any two adjacent protruding and concave endpoints on the wavy curve in the direction of the rod axis does not exceed 1 / 2 of its distance in the direction of the circumference.

[0025] Furthermore, the surface roughness of both the alloy-coated section 120 and the uncoated section 121 is 0.2-0.8 micrometers.

[0026] Furthermore, the outer diameters of the alloy-coated section 120 and the uncoated section 121 are the same.

[0027] Furthermore, the coating thickness of the alloy coating section 120 of the rod body is 0.2-0.5 mm.

[0028] To better illustrate the technical solution of this utility model, the following description uses a 28.6 mm diameter nickel-based alloy coated sucker rod commonly found in oilfields as an example. This sucker rod uses a 20CrMo steel substrate, and the alloy powder composition of the nickel-based alloy coating is NiCrBSi self-fluxing alloy powder. The specific composition by mass percentage is: C: 0%~0.80%, Si: 2.0%~4.0%, B: 1.5%~4.5%, Cr: 5.0~14.0%, Cu: 5.0%~15.0%, Fe≤5.0%, with the balance being nickel. It is produced using a mature existing sucker rod alloy coating thermal spraying-remelting production line.

[0029] The main processing flow of the sucker rod of this utility model is as follows. Throughout the entire process, the sucker rod is always rotating at a constant speed around the axis of the rod body, thereby making each step of the processing more uniform and stable: (1) The oil sucker rod substrate blank is subjected to surface chemical degreasing treatment, and is then thoroughly brushed and degreased multiple times with a high-temperature alkaline solution at about 70°C before drying. (2) The oil extraction rod substrate is sanded at different locations as needed to make its outer diameter reach the required size. The outer diameter of the rod substrate surface corresponding to the alloy coating section is smaller than that of the uncoated section. A 0.1-meter-long transition section is provided in the area near the uncoated section within the alloy coating section. The outer diameter of the rod substrate in the transition section gradually increases towards the uncoated section. In the plane unfolded on the outer circumference surface of the rod, the edge of the junction between the transition section substrate and the uncoated section is a uniformly distributed wavy curve. The specific value of the outer diameter of the rod substrate at different locations is determined according to the coating thickness, so that after the coating of the required thickness is prepared in the subsequent steps, the outer diameter of the rod at the coating location reaches the requirement of 28.6 mm for the outer diameter of the polished rod. The wavy curve at the junction of the transition section substrate and the uncoated section can be achieved by periodically controlling the tilt angle and loading force of the sanding belt during the processing. (3) After the surface of the sucker rod substrate is preheated with a medium frequency induction heating coil at 200℃~300℃, the oxygen, acetylene, compressed air and argon gases are adjusted, and the alloy powder is melted at high temperature to complete the hot spraying treatment of the NiCrBSi nickel-based alloy coating on the surface of the sucker rod, so that the thickness of the alloy coating exceeds the thickness required for the finished product, leaving the allowance required for subsequent grinding and polishing of the alloy coating. (4) The hot-sprayed alloy coating on the surface of the sucker rod obtained in the previous step is remelted using a medium-frequency induction heating coil at a remelting temperature of 930℃~980℃, so that the surface of the hot-sprayed nickel-based alloy coating obtained in the previous step is completely melted and close to a mirror finish. In this embodiment, a nickel-based alloy coating with a thickness of 0.4 mm is obtained. In the plane unfolded on the outer circumferential surface of the sucker rod, the edge 1202 of the alloy coating at the junction of the transition section and the uncoated section is a uniformly distributed wavy curve. See Figure 3 In this embodiment, the maximum positional difference between any two protruding end points in the direction of the axial axis of the sucker rod is 3.5 mm, the maximum positional difference between any two concave end points in the direction of the axial axis of the sucker rod is 3 mm, the maximum distance between any protruding end point and any concave end point on the wavy curve in the direction of the axial axis of the sucker rod is 17 mm, and the maximum distance between any two adjacent protruding end points and concave end points on the wavy curve in the direction of the rod axis is approximately 1 / 3 of their distance in the direction of the corresponding circumference. (5) The cooled nickel-based alloy coated sucker rod is ground and polished to finally obtain the finished sucker rod with a nickel-based alloy coating of 0.3 mm thickness and a surface roughness of 0.5 micrometers in this embodiment.

[0030] This invention relates to a sucker rod that, through targeted design of the coating edge structure at the interface between the hard alloy coating and the substrate of a nickel-based alloy coated sucker rod, avoids the concentrated abrupt changes in material composition and hardness at the flush boundary ends of existing alloy coated sucker rods. By limiting the wavy curve of the alloy coating edge, the abrupt change between the alloy coating and the substrate is improved through a wider strip-shaped area, thereby further improving the performance of the sucker rod and achieving a longer service life.

Claims

1. A sucker rod, characterized by The sucker rod includes upset ends and unupset ends located at both ends, and a rod body located between the upset ends and the unupset ends. The rod body includes an alloy-coated section in the middle and uncoated sections on both sides. The outer diameter of the rod body substrate surface of the alloy-coated section is smaller than the outer diameter of the rod body of the uncoated section. A transition section is provided in the region of the alloy-coated section near the uncoated section. The outer diameter of the rod body substrate of the transition section gradually increases towards the uncoated section. In the plane unfolded on the outer circumference surface of the rod body, the edge of the alloy coating at the junction of the transition section and the uncoated section is a uniformly distributed wavy curve.

2. The sucker rod as claimed in claim 1, characterized in that The wavy curve of the alloy coating edge at the junction of the transition section and the uncoated section is continuous and without sharp corners.

3. The polished rod of claim 1, wherein, On the wavy curve at the junction of the transition section and the uncoated section, the positional difference between any two protruding end points in the direction of the sucker rod axis shall not exceed 5 mm, and the positional difference between any two concave end points in the direction of the sucker rod axis shall not exceed 5 mm.

4. The polished rod of claim 3, wherein, The distance between any protruding end and any recessed end on the wavy curve in the direction of the axial direction of the sucker rod body shall not exceed 20 mm.

5. The polished rod of claim 3, wherein, On a wavy curve, the distance between any two adjacent protruding and concave endpoints in the direction of the rod axis does not exceed 1 / 2 of their distance in the direction of the circumference.

6. The polished rod of claim 1, wherein, The surface roughness of both the alloy-coated and uncoated sections is 0.2-0.8 micrometers.

7. The polished rod of claim 1, wherein, The outer diameters of the alloy-coated section and the uncoated section are the same.

8. The polished rod of claim 1, wherein, The coating thickness of the alloy coating section of the rod is 0.2-0.5 mm.

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