End upsetting oil well pump pull rod and machining method thereof
By designing an upsetting section and a transition arc structure in the oil pump tie rod, combined with heat treatment and surface anti-corrosion treatment, the problem of oil pump tie rod fracture due to increased stress was solved, thus improving the stability and efficiency of the oil pump system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-11-07
- Publication Date
- 2026-05-08
AI Technical Summary
As the stroke, number of strokes, and pump diameter increase, the rod of the existing oil pump is prone to frequent breakage due to increased stress, which affects the stable operation and efficiency of the rod pump oil pumping system.
A tip-upped oil pump tie rod is designed. By setting upped sections and transition arcs on both sides of the rod body, the stress condition at the thread end is improved. The toughness and fatigue strength of the tie rod are improved by overall heat treatment and shot blasting. Combined with surface anti-corrosion treatment, the seismic performance is enhanced.
It improves the stress condition at the thread end, enhances the toughness and fatigue strength of the tie rod, reduces the frequency of tie rod breakage, and ensures the stable operation of the oil pump system.
Smart Images
Figure CN121993393A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of oil pumps for rod-type oil production systems, and specifically relates to an end-upped oil pump tie rod and its processing method. Background Technology
[0002] In the oil extraction process, the sucker pump plays a crucial role and is a key piece of equipment in rod pump mechanical oil production. As a critical component connecting the pump body and the drive unit, the sucker pump rod continuously transmits and bears the alternating stress between the sucker rod and the pump piston, and its performance directly affects the stable operation and efficiency of the entire rod pump oil extraction system.
[0003] Currently, the connecting rod of an oil pump has the same diameter at both ends, with metric threads machined at both ends. One end connects to the sucker rod via a reducing coupling, and the other end connects to the oil pump plunger outlet valve cover and is locked with a nut. Alternatively, one end has a sucker rod thread, connected to the sucker rod via a coupling, and the other end has a metric thread, connecting to the oil pump plunger outlet valve cover and being locked with a nut. Currently, most oilfields are in the later stages of development, with pump runs becoming increasingly deeper and facing ever-increasing demands for fluid discharge. Strokes, strokes, and pump diameters are gradually increasing, leading to increased alternating loads on the connecting rod during operation. This increases the likelihood of frequent connecting rod breakage, often occurring at the point where the metric thread disappears. Summary of the Invention
[0004] To address the problem that existing oil pump tie rods are prone to breakage when the stroke, number of strokes, and pump diameter increase, leading to increased stress, the present invention aims to provide an end-upped oil pump tie rod and its processing method. By using an end-upped structure, the stress condition at the thread end is improved, enhancing the tie rod's toughness and fatigue resistance, and reducing the frequency of tie rod breakage.
[0005] The technical solution of the present invention is as follows: an end-upset oil pump connecting rod, comprising a rod body, an oil pump connecting end and a sucker rod connecting end connected to both sides of the rod body, the oil pump connecting end comprising an upset section, the diameter of the upset section being larger than the diameter of the rod body, a first transition arc being provided at the connection between the upset section and the rod body, and a metric thread section being provided at the end of the upset section, the metric thread section having a metric thread for connecting the oil pump, the sucker rod connecting end comprising a sucker rod connecting section, the diameter of the sucker rod connecting section being larger than the diameter of the rod body, a second transition arc being provided at the connection between the sucker rod connecting section and the rod body, and a sucker rod thread being provided at the end of the sucker rod connecting section for connecting the sucker rod coupling.
[0006] The sucker rod connecting section is provided with a wrench square on the side near the second transition arc, and the sucker rod connecting section is provided with a sucker rod head push bearing surface on the side near the sucker rod thread.
[0007] The connection between the metric thread section and the upsetting section is provided with a stepped surface.
[0008] The major diameter of the metric thread is smaller than the diameter of the upset section. The radius R of the first transition arc and the second transition arc is R57.15±3.175mm. The ratio of the upset section length to the metric thread end length is 1:1. The ratio of the upset section diameter to the rod diameter is 17.06% to 20.26%.
[0009] A method for machining an end-upped oil pump tie rod, comprising the following steps: S1: Pole straightening; The pole was straightened using a straightening machine to improve its straightness. After straightening, the straightness of the pole reached 304.8mm:1.65mm. S2: Forging upsetting; The rod end is upsetting and forging using a horizontal parting die and a punch. The specific process is as follows: S21: Perform visual inspection on the straightened rod body to eliminate surface cracks and inclusion defects. Based on the design drawings of the tie rod, determine the shape, size and tolerance of the die. Install the die in the designated position of the flat forging machine and perform multiple pressure tests and adjustments to ensure that the die is tightly closed and without misalignment. At the same time, adjust the punching force and speed parameters. S22: The rod body is heated in a medium-frequency heating furnace with a medium-frequency voltage of 660±20V, a medium-frequency power of 750±20KW, a medium-frequency frequency of 6.0±0.2KHZ, and a cooling water temperature of ≤38℃ inside the medium-frequency heating furnace. Then, it is sent into the working area of the flat forging machine by the robotic arm and gradually forged into a tie rod shape that meets the design requirements. S3: Overall heat treatment; The overall heat treatment is carried out by quenching and tempering, and the specific process is as follows: S31: Before the heat treatment begins, the rod body is thoroughly cleaned and degreased to remove surface impurities and oil stains. At the same time, the sucker rod is preliminarily inspected to confirm that there are no obvious cracks, deformations or damages. S32: Heating process: The pre-treated rods are loaded one by one into the box-type through-type electric furnace. The rods are evenly distributed in the furnace chamber. The heating temperature of the box-type through-type electric furnace is 800-850℃, and the heating and holding time is 40-50 minutes, so that the internal structure of the rods undergoes sufficient phase transformation and recrystallization. S33: Quenching process: After heating, the rod body is quickly placed into the quenching medium for cooling. Water is selected as the cooling medium during the quenching process. A dense martensitic structure will be formed on the surface of the quenched rod. S34: Tempering process: The rod is put back into the box-type through-type electric furnace for high-temperature tempering treatment. The tempering temperature range is 500-550℃ and the tempering time is 30-50min. S35: Performance Testing: After tempering, the rod body needs to undergo performance testing, including: tensile strength ≥ 800 MPa, elongation ≥ 10%, reduction of area ≥ 45%, and fatigue performance σ. 0.1 540MPa≥10 6 Second, impact toughness (U-shaped) ≥60J; S4: Shot blasting The surface of the rod is cold-worked by shot blasting. The shot blasting machine is started, and the shot is accelerated to an extremely high speed in the shot blaster. After being directionally projected by the shot blasting wheel, it impacts the surface of the rod at high speed. The impeller speed of the shot blaster is 2250 rpm, the axial scattering angle is 0-55°, the radial scattering angle is 0-12°, the shot blasting rate is 150-200 kg / min, the steel shot size is 1.0-1.8 mm, and the working speed is 0.50-2.00 m / min. S5: Thread machining; Machining sucker rod threads and metric threads at both ends of the tie rod; S6: Surface anti-corrosion, processing completed.
[0010] In step S2, the forging upsetting process, the initial forging temperature of the flat forging machine is in the range of 1100℃-1250℃, and the final forging temperature is not lower than 750℃.
[0011] In step S6, the surface corrosion protection is achieved by one of spraying, brushing, or electroplating. The specific process is as follows: S61: Preliminary preparation: Inspect the dipping tank, agitator, dehydration equipment, and operating area, keep it dry and well-ventilated, and control the room temperature between -10℃ and 20℃ and the humidity above 20%. S62: Pre-treatment before dipping: Use a high-pressure water gun or chemical cleaner to thoroughly remove oil, rust, old coating impurities from the surface of the pole to ensure that the surface is clean and free of residue. The pole must be dried after cleaning. S63: Dipping Operation: Mix the water-based paint base agent, hardener, and thinner evenly according to the manufacturer's provided ratio to prepare a paint solution suitable for dipping. Slowly immerse the treated rod into the prepared paint solution for 5 minutes. S64: Leveling and Removing Excess Paint: After dipping the rod in paint, it should be left to stand for a period of time to allow the paint to level naturally under gravity, reducing surface bubbles and unevenness. Use a scraper or cloth strip to gently scrape away any excess paint that may have accumulated at both ends of the rod. S65: Drying treatment: After leveling, the rod body is dried to remove moisture and volatile substances from the paint film, thereby improving the hardness and wear resistance of the coating.
[0012] The technical effects of this invention are as follows: 1. This invention connects the sucker rod thread with the sucker rod coupling. The end face of the coupling is in close contact with the push-bearing surface of the sucker rod head, forming a compressive load and creating stable tensile stress at the unloading groove. This improves the stress condition at the end of the thread, enhances the toughness and fatigue strength of the rod, and reduces the frequency of rod breakage. 2. This invention provides a wrench handle at the rear of the push-bearing surface of the sucker rod head for easy tightening or disassembly of the sucker rod thread. 3. This invention uses an upset section for thread processing, with the major diameter of the thread being smaller than the diameter of the upset section. A stepped surface is provided at the thread section and the upset section, which fits tightly with the end face of the pump plunger outlet valve cover. The tight fit between the upset section stepped surface and the end face of the pump injection / production outlet valve cover enhances the seismic performance and has an anti-loosening effect. At the same time, tensile stress is formed at the root of the thread, thereby improving the stress condition at the end of the thread, enhancing the toughness and fatigue strength of the rod, and reducing the frequency of rod breakage.
[0013] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of an end-upped oil pump tie rod according to an embodiment of the present invention.
[0015] Reference numerals: 1-Metric thread; 2-Stepped surface; 3-Upsetting section; 4-First transition arc; 5-Rod body; 6-Wrench square; 7-Sucker rod head push bearing surface; 8-Sucker rod thread; 9-Second transition arc. Detailed Implementation Example 1
[0016] like Figure 1 As shown, an end-upped oil pump pull rod includes a rod body 5, an oil pump connecting end and a sucker rod connecting end connected to both sides of the rod body 5. The oil pump connecting end includes an upsetting section 3, the diameter of which is larger than the diameter of the rod body 5. A first transition arc 4 is provided at the connection between the upsetting section 3 and the rod body 5. A metric thread section is provided at the end of the upsetting section 3, and a metric thread 1 is provided on the metric thread section for connecting the oil pump. The end of the sucker rod connecting end is provided with a sucker rod connecting section, the diameter of which is larger than the diameter of the rod body 5. A second transition arc 9 is provided at the connection between the sucker rod connecting section and the rod body 5. A sucker rod thread 8 is provided at the end of the sucker rod connecting section for connecting the sucker rod coupling.
[0017] In actual use, the oil pump connection end of the present invention includes an upsetting section 3, the diameter of which is larger than the diameter of the rod body 5. Through the end upsetting structure, the stress condition at the end of the thread is improved, the toughness and fatigue strength of the tie rod are enhanced, and the frequency of tie rod breakage is reduced. Example 2
[0018] Preferably, based on Embodiment 1, in this embodiment, the sucker rod connecting section is provided with a wrench square 6 on the side near the second transition arc 9, and the sucker rod connecting section is provided with a sucker rod head push bearing surface 7 on the side near the sucker rod thread 8.
[0019] In practical use, the present invention connects the sucker rod thread with the sucker rod coupling. The end face of the coupling is in close contact with the push-bearing surface of the sucker rod head, forming a compressive load and a stable tensile stress at the unloading groove. This improves the stress condition at the end of the thread, enhances the toughness and fatigue strength of the rod, and reduces the frequency of rod breakage. A wrench is provided at the rear of the push-bearing surface of the sucker rod head for easy tightening or disassembly of the sucker rod thread. Example 3
[0020] Preferably, based on Embodiment 1 or Embodiment 2, in this embodiment, a stepped surface 2 is provided at the connection between the metric thread section and the upsetting section 3.
[0021] In practical use, the present invention provides stepped surfaces at the threaded section and the upset section, which fit tightly with the end face of the oil pump plunger outlet valve cover. The tight fit between the stepped surface of the upset section and the end face of the oil pump injection / production outlet valve cover enhances the anti-vibration performance and has an anti-loosening effect. At the same time, tensile stress is formed at the root of the thread, thereby improving the stress condition at the end of the thread, increasing the toughness and fatigue strength of the tie rod, and reducing the frequency of tie rod breakage. Example 4
[0022] Preferably, based on Embodiment 1 or Embodiment 3, in this embodiment, the major diameter of the metric thread 1 is smaller than the diameter of the upsetting section 3, the radius R of the first transition arc 4 and the second transition arc 9 is R57.15±3.175mm, the ratio of the length of the upsetting section 3 to the end length of the metric thread 1 is 1:1, and the ratio of the diameter of the upsetting section 3 to the diameter of the rod body 5 is 17.06% to 20.26%. In actual use, the major diameter of the metric thread 1 described in this invention is smaller than the diameter of the upset section 3. When the major diameter of the thread is smaller than the diameter of the upset section, after the sucker rod coupling is tightened, it can ensure that the end face of the coupling is in close contact with the push bearing surface of the sucker rod head, forming a compressive load and forming a stable tensile stress at the unloading groove, thereby improving the stress condition at the end of the thread, enhancing the toughness and fatigue strength of the rod, and reducing the frequency of rod breakage. Example 5
[0023] A method for machining an end-upped oil pump tie rod, comprising the following steps: S1: Pole straightening; A straightening machine was used to straighten rod 5, improving its straightness. After straightening, the straightness of the rod reached 304.8mm:1.65mm. S2: Forging upsetting; The rod end is upsetting and forging using a horizontal parting die and a punch. The specific process is as follows: S21: Perform visual inspection on the straightened rod 5 to eliminate surface cracks and inclusion defects. Based on the design drawings of the tie rod, determine the shape, size, and tolerance of the die. Install the die in the designated position of the flat forging machine and perform multiple pressure tests to ensure that the die is tightly closed and without misalignment. At the same time, adjust the punching force and speed parameters. S22: The rod 5 is heated in a medium-frequency heating furnace with a medium-frequency voltage of 660±20V, a medium-frequency power of 750±20KW, a medium-frequency frequency of 6.0±0.2KHZ, and a cooling water temperature of ≤38℃ inside the medium-frequency heating furnace. Then, it is sent into the working area of the flat forging machine by the robotic arm and gradually forged into a tie rod shape that meets the design requirements. S3: Overall heat treatment; The overall heat treatment is carried out by quenching and tempering, and the specific process is as follows: S31: Before the heat treatment begins, the rod body 5 is thoroughly cleaned and degreased to remove impurities and oil stains from the surface. At the same time, the sucker rod is preliminarily inspected to confirm that there are no obvious cracks, deformations or damages. S32: Heating process: The pre-treated rods 5 are loaded one by one into the box-type through-type electric furnace. The rods 5 are evenly distributed in the furnace chamber. The heating temperature of the box-type through-type electric furnace is 800-850℃, and the heating and holding time is 40-50 minutes, so that the internal structure of the rods 5 undergoes sufficient phase transformation and recrystallization. S33: Quenching process: After heating, the rod 5 is quickly placed into the quenching medium for cooling. Water is selected as the cooling medium during the quenching process. A dense martensitic structure will be formed on the surface of the quenched rod. S34: Tempering process: The rod 5 is put back into the box-type through-type electric furnace for high-temperature tempering treatment. The tempering temperature range is 500-550℃ and the tempering time is 30-50min. S35: Performance Testing: After tempering, the rod 5 needs to undergo performance testing, including: tensile strength ≥ 800 MPa, elongation ≥ 10%, reduction of area ≥ 45%, and fatigue performance σ. 0.1 540MPa≥10 6 Second, impact toughness (U-shaped) ≥60J; S4: Shot blasting The surface of the rod body 5 is cold-worked by shot blasting. The shot blasting machine is started, and the shot is accelerated to an extremely high speed in the shot blaster. After being directionally projected by the shot blasting wheel, it impacts the surface of the rod body at high speed. The impeller speed of the shot blaster is 2250 rpm, the axial scattering angle is 0-55°, the radial scattering angle is 0-12°, the shot blasting rate is 150-200 kg / min, the steel shot size is 1.0-1.8 mm, and the working speed is 0.50-2.00 m / min. S5: Thread machining; Machining sucker rod threads 8 and metric threads 1 at both ends of rod body 5; S6: Surface anti-corrosion, processing completed.
[0024] In step S2, the forging upsetting process, the initial forging temperature of the flat forging machine is in the range of 1100℃-1250℃, and the final forging temperature is not lower than 750℃.
[0025] In step S6, the surface corrosion protection is achieved by one of spraying, brushing, or electroplating. The specific process is as follows: S61: Preliminary preparation: Inspect the dipping tank, agitator, dehydration equipment, and operating area, keep it dry and well-ventilated, and control the room temperature between -10℃ and 20℃ and the humidity above 20%. S62: Pre-treatment before dipping: Use a high-pressure water gun or chemical cleaner to thoroughly remove oil, rust, old coating impurities from the surface of the rod 5 to ensure that the surface is clean and free of residue. The rod 5 must be dried after cleaning. S63: Dipping Operation: Mix the water-based paint base agent, hardener, and thinner evenly according to the manufacturer's provided ratio to prepare a paint solution suitable for dipping. Slowly immerse the treated rod 5 into the prepared paint solution for 5 minutes. S64: Leveling and Removing Excess Paint: After dipping the rod in paint, it should be left to stand for a period of time to allow the paint to level naturally under gravity, reducing surface bubbles and unevenness. Use a scraper or cloth to gently scrape away any excess paint that may have accumulated at both ends of the rod. S65: Drying treatment: After leveling, the rod body 5 is dried to remove moisture and volatile substances from the paint film, thereby improving the hardness and wear resistance of the coating.
[0026] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A type of end-upped oil pump tie rod, characterized in that: The device includes a rod body (5), a pump connection end connected to both sides of the rod body (5), and a sucker rod connection end. The pump connection end includes an upsetting section (3), the diameter of which is larger than the diameter of the rod body (5). The connection between the upsetting section (3) and the rod body (5) is provided with a first transition arc (4). The end of the upsetting section (3) is provided with a metric thread section, and the metric thread section is provided with a metric thread (1) for connecting the pump. The end of the sucker rod connection end is provided with a sucker rod connection section, the diameter of which is larger than the diameter of the rod body (5). The connection between the sucker rod connection section and the rod body (5) is provided with a second transition arc (9). The end of the sucker rod connection section is provided with a sucker rod thread (8) for connecting the sucker rod coupling.
2. The end-upped oil pump tie rod according to claim 1, characterized in that: The sucker rod connecting section is provided with a wrench square (6) on the side near the second transition arc (9), and the sucker rod connecting section is provided with a sucker rod head push bearing surface (7) on the side near the sucker rod thread (8).
3. The end-upped oil pump tie rod according to claim 1, characterized in that: The connection between the metric thread section and the upsetting section (3) is provided with a stepped surface (2).
4. The end-upped oil pump tie rod according to claim 1, characterized in that: The major diameter of the metric thread (1) is smaller than the diameter of the upset section (3). The radius R of the first transition arc (4) and the second transition arc (9) is R57.15±3.175mm. The ratio of the length of the upset section (3) to the length of the metric thread (1) is 1:
1. The ratio of the diameter of the upset section (3) to the diameter of the rod body (5) is 17.06% to 20.26%.
5. A method for machining an end-upped oil pump tie rod, wherein the end-upped oil pump tie rod as described in claim 1 is characterized in that: Includes the following steps: S1: Pole straightening; The rod (5) was straightened using a straightening machine to improve its straightness. After straightening, the straightness of the rod reached 304.8mm:1.65mm. S2: Forging upsetting; The rod end is upsetting and forging using a horizontal parting die and a punch. The specific process is as follows: S21: Perform visual inspection on the straightened rod (5) to eliminate surface cracks and inclusion defects. Based on the design drawings of the tie rod, determine the shape, size and tolerance of the mold. Install the mold in the designated position of the flat forging machine and perform multiple pressure tests to ensure that the mold is tightly closed and without misalignment. At the same time, adjust the punching force and speed parameters. S22: The rod (5) is heated in a medium frequency heating furnace with a medium frequency voltage of 660±20V, a medium frequency power of 750±20KW, a medium frequency of 6.0±0.2KHZ, and a cooling water temperature of ≤38℃ inside the medium frequency heating furnace. Then, it is sent into the working area of the flat forging machine by the robotic arm and gradually forged into a tie rod shape that meets the design requirements. S3: Overall heat treatment; The overall heat treatment is carried out by quenching and tempering, and the specific process is as follows: S31: Before the heat treatment begins, the rod body (5) is thoroughly cleaned and degreased to remove impurities and oil stains from the surface. At the same time, the sucker rod is preliminarily inspected to confirm that it has no obvious cracks, deformations or damage. S32: Heating process: The pre-treated rods (5) are loaded one by one into the box-type through-type electric furnace. The rods (5) are evenly distributed in the furnace chamber. The heating temperature of the box-type through-type electric furnace is 800-850℃. The heating and holding time is 40-50min, so that the internal structure of the rods (5) undergoes sufficient phase transformation and recrystallization. S33: Quenching process: After heating is completed, the rod (5) is quickly placed into the quenching medium for cooling. During the quenching process, water is selected as the cooling medium. A dense martensitic structure will be formed on the surface of the quenched rod. S34: Tempering process: The rod (5) is put back into the box-type through-type electric furnace for high-temperature tempering treatment. The tempering temperature range is 500-550℃ and the tempering time is 30-50min. S35: Performance testing: After tempering, the rod (5) needs to be tested for performance, including: tensile strength ≥800MPa, elongation ≥10%, reduction of area ≥45%, and fatigue performance σ 0.1 540MPa≥10 6 Second, impact toughness (U-shaped) ≥60J; S4: Shot blasting The surface of the rod (5) is cold-worked by shot blasting. The shot blasting machine is started. The shot is accelerated to a very high speed in the shot blaster and then blasted at high speed by the directional shot wheel. The shot blaster impeller speed is 2250 rpm, the axial scattering angle is 0-55°, the radial scattering angle is 0-12°, the shot blasting amount is 150-200 kg / min, the steel shot size is 1.0-1.8 mm, and the working speed is 0.50-2.00 m / min. S5: Thread machining; Sucker rod threads (8) and metric threads (1) are machined at both ends of the rod body (5); S6: Surface anti-corrosion, processing completed.
6. The machining method for an end-upped oil pump tie rod according to claim 5, characterized in that: In step S2, the forging upsetting process, the initial forging temperature of the flat forging machine is in the range of 1100℃-1250℃, and the final forging temperature is not lower than 750℃.
7. The machining method for an end-upped oil pump tie rod according to claim 5, characterized in that: In step S6, the surface corrosion protection is achieved by one of spraying, brushing, or electroplating. The specific process is as follows: S61: Preliminary preparation: Inspect the dipping tank, agitator, dehydration equipment, and operating area, keep it dry and well-ventilated, and control the room temperature between -10℃ and 20℃ and the humidity above 20%. S62: Pre-treatment before dipping: Use a high-pressure water gun or chemical cleaner to thoroughly remove oil, rust, old coating impurities from the surface of the rod (5) to ensure that the surface is clean and free of residue. The rod (5) after cleaning needs to be dried. S63: Dipping Operation: Mix the water-based paint base agent, hardener, and thinner evenly according to the manufacturer's ratio to prepare a paint solution suitable for dipping. Slowly immerse the treated rod (5) into the prepared paint solution for 5 minutes. S64: Leveling and Removal of Excess Paint: The rod (5) after being dipped in paint should be left to stand for a period of time to allow the paint to level naturally under gravity, reducing surface bubbles and unevenness. Use a scraper or cloth to gently scrape away the excess paint at both ends of the rod and any that may have accumulated. S65: Drying treatment: After leveling, the rod body (5) is dried to remove moisture and volatile substances from the paint film and improve the hardness and wear resistance of the coating.