Precise manufacturing method of petroleum lifting ring
By adopting a precision manufacturing method using low-alloy high-strength steel plates, the problems of complex processes, high costs, and poor environmental performance in the manufacturing of oil lifting rings have been solved. This has enabled the production of high-precision, low-cost, and reliable lifting rings that meet API 8C standards and are adaptable to different temperature environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RG PETRO MACHINERY GROUP
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-28
AI Technical Summary
Existing oil lifting ring manufacturing methods suffer from problems such as cumbersome processes, high costs, long production periods, poor environmental performance, low connection dimensional accuracy, and insufficient pairing success rate, especially the complexity and instability caused by forging and heat treatment.
Low-alloy high-strength steel plates are used, and the material is cut by laser cutting or CNC plasma cutting, combined with precision machining on CNC boring and milling machines to avoid forging and heat treatment. The small end is formed using a special cold bending die, shot blasting is performed to increase surface compressive stress, load tests are conducted to ensure no plastic deformation, and then it is painted and packaged.
It simplifies the manufacturing process, reduces production costs, improves dimensional accuracy and mating success rate, enhances fatigue resistance, meets API 8C specification requirements, adapts to different temperature environments, and ensures product reliability and safety.
Smart Images
Figure CN121928313A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil and gas drilling technology, specifically to a precision manufacturing method for oil lifting rings, which is applied to oil drilling and oil production lifting equipment (workover rigs). The aim is to improve the precision, performance, and production efficiency of oil lifting rings by changing the traditional manufacturing process and process parameters, and to ensure that the products meet the core industry specifications. Background Technology
[0002] Oil lifting rings are key connecting components on the main load path of oil drilling rigs. They are used in conjunction with other components of the traveling block system to complete the drilling string tripping operations and bear the weight of the entire drill string. The main load is tensile stress, and their quality and reliability are directly related to the safety of drilling rig operators and the entire equipment. Therefore, the design and manufacture of these products must strictly comply with API 8C "Drilling and Lifting Equipment Specification".
[0003] The existing manufacturing method for oil lifting rings has many drawbacks: Using 20SiMn2MoVA bar stock as raw material and forging it, the large geometric dimensions of the lifting ring necessitate a large heating furnace and forging equipment. The forging process is extremely complex, requiring multiple steps for both the large and small ends, including flattening, pre-forming, trimming, and final forming, each requiring three sets of specialized molds. After more than eight heat treatments, the forged blank is slowly cooled. The forged blank then undergoes a normalizing-quenching-low-temperature tempering heat treatment process to meet the mechanical property requirements of API 8C standards, as shown in Table 1. As 20SiMn2MoVA is a low-carbon martensitic steel, its low-temperature impact energy is insufficient and its stability is poor. It often needs to be reworked because its impact energy index does not meet the requirements of Table 1. At the same time, as a slender part, the lifting ring is prone to deformation after heat treatment, and additional hydraulic press straightening and stress-relieving tempering are required.
[0004] Oil lifting rings are connecting parts used in drilling and oil production hoisting equipment on oil drilling rigs. To ensure a smooth connection, the industry standard API 8C specifies the arc dimensions of both the large and small ends. Conventional oil lifting ring blanks are hot-formed by die forging, resulting in significant errors (±20mm) in the arc dimensions and ring length. These errors require manual grinding to meet drawings and specifications. Furthermore, API 8C stipulates that the error should not exceed 4mm when the design length of a pair of lifting rings is ≤4.25m, and should not exceed 7mm when the design length is >4.25m. This results in approximately 10% of lifting rings in a production batch failing to pair successfully, necessitating additional production for subsequent batches and increasing production costs. With increasingly stringent environmental requirements, the number of forging and heat treatment companies has decreased, leading to rising manufacturing costs and extended production cycles, making it difficult to meet customer delivery deadlines. Summary of the Invention
[0005] To address the aforementioned technical deficiencies, the present invention aims to provide a precision manufacturing method for oil lifting rings. This method eliminates the need for forging, heat treatment, and other heat processing steps during the manufacturing process, effectively solving problems such as cumbersome procedures, high costs, long lead times, poor environmental performance, low connection dimensional accuracy, and insufficient matching success rate in existing manufacturing processes. In particular, it avoids the manufacturing difficulties caused by forging, such as process complexity, unstable heat treatment performance indicators, and product deformation.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A precision manufacturing method for oil lifting rings, comprising the following steps: 1) Structural design: The connection dimensions of the large and small ends of the lifting ring are designed according to API 8C "Drilling and Oil Production Lifting Equipment Specification", and the corresponding dimensional parameters are determined according to the lifting ring specifications; the middle rod of the lifting ring is designed with a rectangular cross section, and the corners of the rectangular cross section are chamfered to form a polygon; 2) Material selection: Low alloy high strength steel plates conforming to GB / T1591 or GB / T16270 standards are selected. The strength level and plate thickness are selected according to the lifting ring model, and the material quality grade is selected according to the service environment temperature. 3) Blanking and blanking: The low alloy high strength steel plate in step 2) is blanked using laser cutting or CNC plasma cutting. The surface roughness of the blank after cutting is ≤12.5μm. The length direction of the lifting ring is consistent with the rolling direction of the plate. A machining allowance of 0.5-3mm is reserved in each part. 4) Machining: Select a CNC boring and milling machine with a stroke >1600mm, and process the large end, rod and small end in sequence according to the program compiled in the drawings, with the key mating dimensions accurate to ±0.03mm; 5) Small end bending: Using a special cold bending die on a press with a capacity of not less than 500 tons, the small end is pressed into an upward-curving shape. 6) Shot blasting: Use cast steel shot with a diameter of 0.8-2.5mm and a hardness of HRC40-55, and blast at a shot speed of 60-90m / s and a shot angle of 90±20° for 20-40 minutes to make the surface compressive stress of the lifting ring ≥340Mpa. 7) Load test: Perform the rated load functional test, 1.5 times rated load verification test, and 2.4 times rated load type test in sequence according to API 8C standard. After the test, perform dimensional measurement and non-destructive testing. 8) Painting and packaging: After printing the markings, paint the product and package it in pairs.
[0007] Furthermore, the blank formed in step 3) after precision machining has a length error of no more than 1mm.
[0008] In step 6), the diameter of the cast steel shot used for shot blasting is 0.8-1.2 mm, the blasting speed is 80-90 m / s, the blasting angle is 90±10°, the blasting time is 25 minutes, and the surface compressive stress after treatment is ≥410 MPa.
[0009] The low-alloy high-strength steel plate selected in step 2) is Q690E, with a plate thickness of 60mm, and is suitable for a minimum service environment temperature of -45℃.
[0010] Step 4) The machining process is divided into two parts: rough milling and finish milling. After machining, the accuracy of the key dimensions reaches ±0.03mm.
[0011] The special cold bending die used in step 5) includes a lower die base, and an upper die base is connected to the inner side of the lower die base by a guide plate, so that a bending cavity is formed between the upper die base, the lower die base and the guide plate. The bending cavity is provided with a positioning pin for positioning the small end, and a limiting plate for restricting the movement of the small end is also provided inside the bending cavity. There is also a positioning plate for positioning the lifting ring rod outside the bending cavity. The small end of the lifting ring is fixed by the above-mentioned special cold bending die, and the small end of the lifting ring is pressed and formed on a 500-ton press.
[0012] The present invention can ensure that the lifting ring is free from plastic deformation and crack defects through the load test in step 7).
[0013] The lifting ring rod of this invention adopts a rectangular cross-section chamfered structure, with a key dimension accuracy of ±0.03mm, a 100% matching success rate, and a surface compressive stress ≥340Mpa after shot blasting. It has excellent fatigue resistance and meets the requirements of API 8C specifications. It is suitable for oil drilling and oil production hoisting equipment.
[0014] The low-alloy high-strength steel plate in the quenched and tempered state described in step 2) of this invention has good low-temperature toughness and machinability compared to traditional oil lifting ring materials, and is easy to procure and mass-produce, while simplifying the process and improving production efficiency.
[0015] The blank formed by blanking in step 3) of this invention has a smaller machining allowance and a length error of no more than 1mm after final precision machining compared to a forging blank. It has a higher material utilization rate, a 100% success rate in matching lifting rings, and lower process costs.
[0016] In step 4), the precision machining achieved by CNC boring and milling machine and programming ensures that the fitting dimensions of the lifting ring meet the requirements of API 8C specifications and have higher accuracy, further guaranteeing a 100% success rate in fitting the lifting ring and improving production efficiency.
[0017] In step 5), the cold bending of the small end serves two purposes: first, to ensure that the small end of the lifting ring meets the dimensional requirements of the drawing; and second, to strengthen the small end through cold bending deformation, thereby improving the structural strength of the small end.
[0018] The shot blasting process in step 6) of this invention serves three purposes: first, it subjects the surface of the lifting ring to a compressive stress state, thereby improving its fatigue resistance; second, it removes surface rust and oxide scale, increasing surface roughness; and third, it enhances the adhesion of subsequent coatings by increasing surface roughness, thus improving the corrosion resistance of the lifting ring.
[0019] The beneficial effects of this invention are reflected in the following aspects: This invention uses low-alloy high-strength steel plates as raw materials, eliminating the need for forging and heat treatment processes, simplifying the manufacturing process, shortening the production cycle, avoiding environmental problems caused by hot processing, and reducing production energy consumption and costs.
[0020] This invention uses laser cutting or CNC plasma cutting for blanking, combined with precision machining on a CNC boring and milling machine, to achieve a critical fit dimension accuracy of ±0.03mm for the lifting ring, which is far higher than the ±1 to 2mm accuracy of the traditional forging and grinding process. The length dimension accuracy of ±1mm ensures 100% successful pairing of the lifting ring, eliminating the need for additional production reserves and significantly reducing production costs.
[0021] The shot blasting process in this invention not only achieves surface cleaning and coating pretreatment, but also improves the fatigue resistance of the lifting ring by introducing surface compressive stress, thus extending the product's service life; the small end is formed by cold bending mold, which has high forming accuracy and requires no subsequent correction.
[0022] The material selection in this invention can be adapted to the quality grade according to the service environment temperature, ensuring that the lifting ring can meet the low-temperature impact toughness requirements of API 8C specifications under different temperature conditions, thereby improving the environmental adaptability and reliability of the product. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the DH100A type lifting ring in this invention.
[0024] Figure 2 This is a schematic diagram of the special bending mold for bending the small end of the lifting ring in this invention.
[0025] Figure 3 This is a schematic diagram showing the arrangement of strain gauges during the load test of this invention.
[0026] Appendix Figure 1-3 In the middle, 1. Upper mold base; 2. Lower mold base; 3. Positioning pin; 4. Guide plate; 5. Positioning plate; 6. Nut; 8. Bolt; 9. Limiting plate; 10. Rod; 11. Small end; 12. Large end; 13-16. Critical section. Detailed Implementation
[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0028] Taking the DH100A type lifting eyelet as an example, the manufacturing method of this invention includes the following specific steps: The structural design follows API 8C, "Drilling and Oil Production Lifting Equipment Specification," in designing the connection dimensions of the large and small ends. The rod section adopts a rectangular cross-section, which is chamfered to form a polygon. The geometric dimensions are as follows: Figure 1 As shown.
[0029] exist Figure 1 For the small end of the eye, the radius parameters of the inner ring of the small end are R52, R52, and R36, and the radius parameters of the outer ring of the small end are R105, R183, and R125. The length of the inner ring of the small end is 154±2. The radius parameters of the inner ring of the large end of the eye are R120, R40, R50, and R110, and the radius parameters of the outer ring of the large end are R195, R220, and R175. The length of the inner ring of the small end is 195±2. The length of the inner rings of both the large and small ends is 1500.
[0030] In terms of material selection, 60mm thick Q690E steel plate was chosen. Its technical specifications comply with GB / T16270 "High-strength structural quenched and tempered steel plate". Its mechanical properties, safety factor and connection dimensions all meet the requirements of API 8C specifications, and it is suitable for service environments with a minimum operating temperature of -45℃. The mechanical property parameters of Q690E steel plate are shown in the table below:
[0031] In terms of blanking and billet preparation, a CNC laser cutting machine is used to cut Q690E steel plates. The surface roughness after cutting is ≤12.5μm. The length direction of the lifting ring is consistent with the rolling direction of the plate. A machining allowance of 1-1.5mm is reserved in each part. The dimensions are precisely controlled, and the machining allowance is left as small as possible to ensure the success rate of matching.
[0032] In terms of machining, a CNC boring and milling machine with a worktable size of 8000x2000mm and a stroke of 6000mm was selected. The machining program was compiled according to the drawings, and the large end, rod and small end were machined in two processes: rough milling and finish milling. After machining, the accuracy of key mating dimensions reached ±0.03mm, and the accuracy of length dimensions was ≤±1mm.
[0033] Special cold bending dies (such as those used for bending the small end) are employed for bending the small end. Figure 2 As shown in the figure, the small end of the lifting ring is pressed and formed on a 500-ton press, so that the upward tilt of the small end reaches 20.2mm, which meets the design requirements of the drawing.
[0034] The special cold bending die includes a lower die base 2, and an upper die base 1 is connected to the inner side of the lower die base 2 by a guide plate 4, so that a bending cavity is formed between the upper die base 1, the lower die base 2 and the guide plate 4. The bending cavity is provided with a positioning pin 3 for positioning the small end 11, and a limiting plate 9 for restricting the movement of the small end 11 is also provided inside the bending cavity. There is also a positioning plate 5 for positioning the lifting ring rod 10 outside the bending cavity. The small end of the lifting ring is fixed by the above-mentioned special cold bending die, and the small end of the lifting ring is pressed and formed by a 500-ton press.
[0035] For shot blasting, a handheld shot blasting machine is used, and cast steel shot with a diameter of 0.8-1.2mm and a hardness of HRC40-55 is selected. The workpiece surface is shot for 25 minutes at a shot speed of 80-90m / s and a shot angle of 90±10°. After treatment, the surface compressive stress reaches more than 410Mpa.
[0036] For load testing, a 500-ton vertical testing machine was used, and strain gauges were attached to the critical sections 13, 14, 15, and 16 of the lifting ring (e.g., Figure 3 As shown, the stress level was monitored; functional tests (load 50 tons, single rated load), verification tests (load 75 tons, 1.5 times rated load) and type tests (load 120 tons, 2.4 times rated load) were carried out in sequence according to API 8C specifications; after the tests, the measured dimensions showed no change, confirming no plastic deformation, and magnetic particle testing and ultrasonic testing were carried out 24 hours later, and the results met the specifications.
[0037] Final painting and packaging: The lifting rings are painted red according to specifications, and the manufacturer's mark, load mark, pairing mark and API 8C mark are printed using low-stress lettering. They are then packaged in pairs and put into storage.
Claims
1. A precision manufacturing method for oilfield lifting rings, characterized in that, Includes the following steps: 1) Structural design: The connection dimensions of the large and small ends of the lifting ring are designed according to API 8C "Drilling and Oil Production Lifting Equipment Specification", and the corresponding dimensional parameters are determined according to the lifting ring specifications; the middle rod of the lifting ring is designed with a rectangular cross section, and the corners of the rectangular cross section are chamfered to form a polygon; 2) Material selection: Low alloy high strength steel plates conforming to GB / T1591 or GB / T16270 standards are selected. The strength level and plate thickness are selected according to the lifting ring model, and the material quality grade is selected according to the service environment temperature. 3) Blanking and blanking: The low alloy high strength steel plate in step 2) is blanked using laser cutting or CNC plasma cutting. The surface roughness of the blank after cutting is ≤12.5μm. The length direction of the lifting ring is consistent with the rolling direction of the plate. A machining allowance of 0.5-3mm is reserved in each part. 4) Machining: Select a CNC boring and milling machine with a stroke >1600mm, and process the large end, rod and small end in sequence according to the program compiled in the drawings, with the key mating dimensions accurate to ±0.03mm; 5) Small end bending: Using a special cold bending die on a press with a capacity of not less than 500 tons, the small end is pressed into an upward-curving shape. 6) Shot blasting: Use cast steel shot with a diameter of 0.8-2.5mm and a hardness of HRC40-55, and blast at a shot speed of 60-90m / s and a shot angle of 90±20° for 20-40 minutes to make the surface compressive stress of the lifting ring ≥340Mpa. 7) Load test: Perform the rated load functional test, 1.5 times rated load verification test, and 2.4 times rated load type test in sequence according to API 8C standard. After the test, perform dimensional measurement and non-destructive testing. 8) Painting and packaging: After printing the markings, paint the product and package it in pairs.
2. The precision manufacturing method of the oil lifting ring according to claim 1, characterized in that: The blank formed in step 3) after precision machining has an error of no more than 1mm.
3. The precision manufacturing method of the oil lifting ring according to claim 1, characterized in that: In step 6), the diameter of the cast steel shot used for shot blasting is 0.8-1.2 mm, the blasting speed is 80-90 m / s, the blasting angle is 90±10°, the blasting time is 25 minutes, and the surface compressive stress after treatment is ≥410 MPa.
4. The precision manufacturing method of the oil lifting ring according to claim 1, characterized in that: The low-alloy high-strength steel plate selected in step 2) is Q690E, with a plate thickness of 60mm, and is suitable for a minimum service environment temperature of -45℃.
5. The precision manufacturing method of the oil lifting ring according to claim 1, characterized in that: Step 4) The machining process is divided into two parts: rough milling and finish milling. After machining, the accuracy of the key dimensions reaches ±0.03mm.
6. The precision manufacturing method of the oil lifting ring according to claim 1, characterized in that: The special cold bending die used in step 5) includes a lower die base, and an upper die base is connected to the inner side of the lower die base by a guide plate, so that a bending cavity is formed between the upper die base, the lower die base and the guide plate. The bending cavity is provided with a positioning pin for positioning the small end, and a limiting plate for restricting the movement of the small end is also provided inside the bending cavity. There is also a positioning plate for positioning the lifting ring rod outside the bending cavity. The small end of the lifting ring is fixed by the above-mentioned special cold bending die, and the small end of the lifting ring is pressed and formed on a 500-ton press.