Processing method of high-strength direct connection type petroleum casing joint

Abstract

This invention discloses a processing method for high-strength direct-connection oil casing joints, relating to the fields of iron and steel metallurgy and machining technology. The method includes: S1, machining the external threads and metal sealing surface of an oil casing blank after smelting, continuous casting, rolling, upsetting, and full-length heat treatment; S2, machining the internal threads and metal sealing surface of the oil casing blank that has undergone external thread and metal sealing surface machining; S3, performing surface treatment on the threads and metal sealing surface of the oil casing blank that has undergone internal thread and metal sealing surface machining. The processing method of this invention has been tested in terms of cutting parameters (cutting speed, depth of cut and number of passes, feed rate), cooling method, and clamping method. It effectively overcomes the shortcomings of high tool wear and low joint qualification rate in the machining of high-strength direct-connection casing joints, meeting the production requirements of high-strength direct-connection oil and gas casing joints, reducing production costs, and improving processing efficiency.

Description

Technical Field

[0001] This invention relates to the fields of iron and steel metallurgy and machining technology, and in particular to a processing method for a high-strength direct-connection type oil casing joint. Background Technology

[0002] In oil and gas exploration and extraction, most oil casing joints utilize couplings for threaded connections. With the development of drilling technology, windowed sidetracking drilling technology, developed based on directional, horizontal, and small-diameter drilling techniques, is a comprehensive drilling technology that, to a certain extent, represents the level of drilling technology development. This technology can revitalize wells with damaged casing, shut-in wells, abandoned wells, and low-production wells, improving reservoir extraction efficiency, effectively developing various reservoirs, increasing recovery rates and well production, and reducing overall development costs. Furthermore, it can fully utilize the structure of old wells to further tap into reservoir potential, making full use of existing well sites and surface transportation equipment, reducing drilling operation costs, saving on casing usage costs and surface construction costs, lowering construction costs, shortening construction cycles, and improving overall economic benefits.

[0003] In a certain oilfield, the reservoir is buried at a depth of over 5500 m. Due to the need for stable production, secondary sidetracking is required based on the existing well casing string. Sidetracking with a window opened in the Φ177.8 mm casing is difficult to select from the existing suitable casings that both meet the required entry clearance and the requirement that the secondary drilling diameter be greater than 121 mm. Summary of the Invention

[0004] The purpose of this invention is to provide a processing method for a high-strength direct-connection type oil casing joint. This method can develop and produce a upset and thickened casing specially designed for the unconventional well structure of an ultra-deep well in an oilfield, according to its personalized requirements. It adopts a high-strength direct-connection type (without coupling connection) casing joint (material yield strength ≥140 Ksi, joint outer diameter Φ143.6±0.2 mm, joint inner diameter Φ122.6±0.1 mm, and joint length after connection 145±2 mm), and the pipe body size is Φ139.7×7.72 mm.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for processing a high-strength direct-connection oil casing joint, the method comprising the following steps:

[0007] Step S1: The oil casing billet, after undergoing smelting, continuous casting, rolling, upsetting and thickening and full-length heat treatment processes, is processed to produce external threads and metal sealing surfaces.

[0008] Step S2: Machining the internal threads and metal sealing surface of the oil casing blank that has already undergone external thread and metal sealing surface machining;

[0009] Step S3: Perform surface treatment on the threads and metal sealing surfaces of the oil casing blank that has already been machined for internal threads and metal sealing surfaces, thus completing the machining of the high-strength direct-connection oil casing joint.

[0010] Furthermore, the chemical composition of the oil casing blank comprises the following components by mass percentage: C: 0.10–0.35%, Mn: 0.20–1.20%, Cr: 0.4–1.50%, Mo: 0.40–1.0%, Si≤0.45%, Ni≤1.5%, P≤0.015%, S≤0.005%, with the balance being Fe and unavoidable impurities.

[0011] Further, step S1 specifically includes:

[0012] Step S11: Place the sleeve blanks side by side on the material table and send them to the special threading machine station via the stepping beam. The sleeve blanks are then transported in by the automatic conveyor that is matched with the threading machine, and are fixed in length or position. The blanks are clamped and centered by the front and rear hydraulic jaws of the machine tool. The height of the alloy pads of the six jaws at the front and rear is adjusted. The deviation between the center line of the sleeve blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa.

[0013] Step S12: Set the cutting parameters on the CNC program of the threading machine to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.6±0.1 mm, a length of ≥110 mm, and a surface roughness Ra of 12.5 μm; at the same time, using the tool position on another tool holder, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm.

[0014] Step S13: Change the tool position of the tool holder, set the cutting parameters on the CNC program of the threading machine, and perform cutting according to the set taper requirements to prepare for threading and machining of the sealing surface in the next station.

[0015] Step S14: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting parameters on the CNC program of the threading machine to perform cutting, ensuring that the surface roughness Ra of the thread reaches 3.2 μm and the thread diameter tolerance is controlled within ±0.05 mm. Then, set the cutting parameters on the CNC program of the threading machine to perform cutting on the sealing surface, so that the diameter tolerance of the outer metal sealing surface is controlled within ±0.05 mm and the surface roughness Ra is controlled at 1.6 μm. Using a special measuring tool, the diameter of the outer thread is controlled within ±0.05 mm and the diameter of the sealing surface is controlled within ±0.05 mm.

[0016] Further, in step S12, the cutting parameters include: a cutting speed of 100-120 m / min, a cutting depth of 0.5-0.8 mm / cut, a feed rate of 0.45-0.6 mm / revolution, 2-3 passes, and a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90°; the tool position on the other tool holder uses a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°.

[0017] Further, in step S13, the cutting parameters include: a cutting speed of 80-100 m / min, a cutting depth of 0.35-0.45 mm / cut, a feed rate of 0.25-0.35 mm / revolution, 1-2 passes, using a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, and a taper of 1:16 in diameter and length.

[0018] Further, in step S14, the cutting parameters include: a cutting speed of 78–85 m / min, a cutting depth of 0.20–0.25 mm / cut, a feed rate of 4 mm / revolution, constant pitch cutting, 8–10 passes, and the use of a specially designed thread profiler; wherein, the parameters of the specially designed thread profiler include: a single tooth, a tooth height of 1.206±0.05 mm, a pitch of 4±0.05 mm, a bearing angle of 15°, a tooth tip and root radius of 0.15±0.05 mm at the bearing surface, a guide angle of 45°, and tooth tip and root radii of 0.38±0.05 mm and 0.56±0.05 mm, respectively, at the guide surface;

[0019] The cutting parameters at the sealing surface include: cutting speed of 70-78 m / min, depth of cut of 0.18-0.20 mm / cut, feed rate of 0.08 mm / revolution, and 2-3 passes.

[0020] Further, step S2 specifically includes:

[0021] Step S21: The sleeve blank with the machined external thread and sealing surface of the straight-connect type threaded joint is sent to the dedicated threading machine station at the other end through the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length or position. It is clamped and centered by the front and rear hydraulic jaws of the machine tool. The height of the alloy pads of the six jaws at the front and rear is adjusted. The deviation between the center line of the tube blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa.

[0022] Step S22: Set the cutting parameters on the CNC program of the threading machine to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.35±0.1 mm, a length of ≥120 mm, and a surface roughness Ra of 12.5 μm; at the same time, using the tool position on another tool holder, also using a YB435 carbide tool with an arc radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm.

[0023] Step S23: Change the tool position of the tool holder, use a special internal boring tapered tool holder, set the cutting parameters on the CNC program of the thread turning machine, and perform cutting according to the set taper requirements to prepare for the next station to turn the internal thread and process the internal sealing surface;

[0024] Step S24: Rotate the tool holder to the threading and sealing surface machining station, set the cutting parameters on the CNC program of the threading machine to perform cutting, ensuring that the surface roughness Ra of the thread reaches 3.2 μm; the thread diameter tolerance is controlled within ±0.05 mm; then set the cutting parameters on the CNC program of the threading machine to perform cutting on the sealing surface, so that the diameter tolerance of the outer metal sealing surface is controlled within ±0.05 mm, and the surface roughness Ra is controlled within 1.6 μm; using a special measuring tool, the internal thread diameter is controlled within ±0.05 mm, and the sealing surface diameter is controlled within ±0.05 mm.

[0025] Further, in step S22, the cutting parameters include: a cutting speed of 100-120 m / min, a cutting depth of 0.5-0.8 mm / cut, a feed rate of 0.45-0.6 mm / revolution, 2-3 passes, and a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90°.

[0026] Further, in step S23, the cutting parameters include: a cutting speed of 70-90 m / min, a cutting depth of 0.30-0.40 mm / cut, a feed rate of 0.25-0.35 mm / revolution, 1-2 passes, using a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, and a taper of 1:16 in diameter and length.

[0027] Further, in step S24, the cutting parameters include: a cutting speed of 72–80 m / min, a cutting depth of 0.18–0.22 mm / cut, a feed rate of 4 mm / revolution, constant pitch cutting, 10–12 passes, and the use of a specially designed profile threading tool; wherein, the parameters of the specially designed profile threading tool include: a single tooth with a tooth height of 1.306±0.05 mm, a pitch of 4±0.05 mm, a bearing angle of 15°, and a radius of curvature of the tooth tip and root at the bearing surface of 0.15±0.05 m; a guide angle of 45°, and radii of curvature of the tooth tip and root at the guide surface of 0.38±0.05 mm and 0.56±0.05 mm, respectively;

[0028] The cutting parameters at the sealing surface include: cutting speed of 68-72 m / min, depth of cut of 0.16-0.18 mm / cut, feed rate of 0.08 mm / revolution, and 2-3 passes.

[0029] Furthermore, step S3 specifically includes:

[0030] The casing, with both ends machined and inspected, is conveyed to the phosphate-dedicated station by a walking beam. The end joints are immersed in a phosphate bath and slowly rotated at a rate of 1-2 revolutions per minute to ensure uniform phosphate treatment. After 30-35 minutes, the joints are removed, dried, and the phosphate film thickness is checked. If the thickness is 10-12 μm and the film is uniform and dense, the processing of the high-strength direct-connection oil casing joint is complete.

[0031] The technical effects and advantages of this invention are as follows:

[0032] The processing method of this invention is applicable to the machining of straight-connection casing joints (internal thread at one end, external thread at the other end, and metal sealing surface) used in oil and gas extraction. It involves external boring, internal boring, threading, and sealing surface machining from the upset and thickened portion of the pipe end. Experiments were conducted on cutting parameters (cutting speed, depth of cut and number of passes, feed rate), cooling methods, and clamping methods. This effectively overcomes the shortcomings of high tool wear and low joint qualification rate in the machining of high-strength straight-connection casing joints, meeting the production requirements of high-strength straight-connection casing joints for oil and gas, reducing production costs, and improving processing efficiency.

[0033] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a processing method for a high-strength direct-connection oil casing joint according to the present invention.

[0035] Figure 2 This is a schematic diagram of the structure of a high-strength direct-connection oil casing according to the present invention;

[0036] Figure 3 This is a physical image of a high-strength direct-connection oil casing and connector according to the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The core innovation of this invention lies in the fact that it requires machining the internal and external threads and sealing surfaces of both pipe ends. Specifically, the machining of this high-strength direct-connection casing joint is divided into two parts: first, machining the external thread and metal sealing surface of the joint: one end of the casing (pipe end) undergoes external pulling, internal boring, external thread turning, and external sealing surface machining; second, machining the internal thread and metal sealing surface of the joint: the other end of the casing (pipe end) undergoes roughing, internal boring, internal thread turning, and internal sealing surface machining. The total length of the casing is 10-11 m. However, using traditional machining processes (cutting parameters, cold cutting methods, and clamping methods) often results in high tool wear and low joint machining pass rates because the material properties of high-strength oil pipe joints differ significantly from ordinary steel pipes, and the requirements for thread dimensional tolerances and metal sealing surfaces are very strict.

[0039] To address the shortcomings of existing technologies, this invention discloses a processing method for a high-strength direct-connection type oil casing joint. Figure 1 This is a flowchart illustrating a processing method for a high-strength direct-connection oil casing joint according to the present invention. Figure 1 As shown, the method includes the following steps:

[0040] Step S1: The oil casing billet, after undergoing smelting, continuous casting, rolling, upsetting and thickening and full-length heat treatment processes, is processed to produce external threads and metal sealing surfaces.

[0041] Step S2: Machining the internal threads and metal sealing surface of the oil casing blank that has already undergone external thread and metal sealing surface machining;

[0042] Step S3: Perform surface treatment on the threads and metal sealing surfaces of the oil casing blank that has already been machined for internal threads and metal sealing surfaces, thus completing the machining of the high-strength direct-connection oil casing joint.

[0043] The processing method of this invention is applicable to a high-strength direct-connection type oil casing, whose chemical composition, by mass percentage, includes the following components: C: 0.10–0.35%, Mn: 0.20–1.20%, Cr: 0.4–1.50%, Mo: 0.40–1.0%, Si≤0.45%, Ni≤1.5%, P≤0.015%, S≤0.005%, with the balance being Fe and unavoidable impurities. After preliminary smelting, continuous casting, and rolling processes, as well as proprietary upsetting and thickening, and full-length heat treatment processes, an upsetting and thickened casing is formed. Due to its material characteristics, it has high strength and alloy composition, with a yield strength exceeding 140 Ksi, exhibiting excellent mechanical properties and corrosion resistance, making it suitable for the special well conditions of a certain oilfield in the oil and gas industry. Figure 2 This is a schematic diagram of the structure of a high-strength direct-connection oil casing according to the present invention, as shown below. Figure 2 As shown, the entire casing length is controlled at 10–11 m. After upsetting and thickening at both ends, the outer diameter is Φ146–148 mm, and the upsetting length is not less than 120 mm. After upsetting and thickening at both ends, the inner diameter is Φ118–118.5 mm, and the inner thickening length is not less than 130 mm. The inner and outer surfaces are free of defects such as protruding ridges, grooves, flash, pits, and scale. After upsetting and thickening, the steel pipe undergoes full-length heat treatment to ensure consistent mechanical properties between the upset end and the pipe body. The room temperature mechanical tensile properties requirements are: yield strength minimum 965 MPa, maximum 1172 MPa, and tensile strength minimum 1034 MPa. The oil casing, processed using the invented method, has a direct-connection joint with the following dimensions: outer diameter of the joint is Φ143.6±0.2 mm, inner diameter of the joint is Φ122.6±0.1 mm, joint length after connection is 145±2 mm, and pipe body dimensions are Φ139.7×7.72 mm.

[0044] The tube blank (both ends have been upset and thickened, and the entire length has been heat-treated) provided to the machining (threaded joint machining) process in the previous steps is processed in two parts: one end is machined for external threads and sealing surfaces, and the other end is machined for internal threads and sealing surfaces. If the machining of one end is not up to standard, the threaded joint of the entire sleeve will be defective.

[0045] Furthermore, the processing method of a high-strength direct-connection oil casing joint disclosed in this invention specifically includes the following steps:

[0046] Step S1: Machining of the external thread and metal sealing surface of the straight-connection sleeve:

[0047] Step S11: Place the sleeve blank (i.e., the tube body size is Φ139.7×7.72 mm, both ends of the tube have been upset and thickened, and the entire length has been heat treated. After the upset and thickened tube ends, the outer diameter is Φ146~148 mm, and the upset length is not less than 120 mm; after the upset and thickened tube ends, the inner diameter is Φ118~118.5 mm, and the inner thickening length is not less than 130 mm, with a total length of 10~11 m) side by side on the material table, and send it to the special threading machine station through the walking beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are used to clamp and center it. The height of the alloy pads of the front and rear six jaws is adjusted. The deviation between the center line of the tube blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10~12 MPa.

[0048] Step S12: Set the cutting speed to 100-120 m / min on the CNC program of the thread cutting machine, the cutting depth per pass to 0.5-0.8 mm / pass, the feed rate to 0.45-0.6 mm / revolution, and the cutting in 2-3 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.6±0.1 mm, a length of ≥110 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm.

[0049] Step S13: Change the tool position of the tool holder, set the cutting speed to 80-100 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.35-0.45 mm / pass, the feed rate to 0.25-0.35 mm / revolution, and perform 1-2 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, and perform cutting according to the requirement of a 1:16 taper in diameter and length to prepare for threading and machining of the sealing surface in the next station.

[0050] Step S14: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 78–85 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.20–0.25 mm, the feed rate to 4 mm / revolution, and constant pitch cutting. Perform cutting in 8–10 passes using a specially designed thread profiler (single tooth, tooth height 1.206±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 mm, guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively). Ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within ±0.05 mm. Machining is performed on the sealing surface: The CNC program of the threading machine is set to a cutting speed of 70–78 m / min, a depth of cut of 0.18–0.20 mm per pass, a feed rate of 0.08 mm / revolution, and 2–3 passes. This ensures the diameter tolerance of the external metal sealing surface is controlled within ±0.05 mm, and the surface roughness Ra is controlled at 1.6 μm. Using specialized measuring tools, the external thread diameter and the sealing surface diameter are controlled within ±0.05 mm.

[0051] The cutting cooling method has been improved by using a special cutting fluid instead of the original tool tip coolant channel. This allows the coolant to be sprayed directly onto the tool cutting edge and cutting area, increasing pressure and flow rate for effective machining cooling.

[0052] Cover the machined straight-connection threaded joint's external thread and sealing surface with a special plastic steel protective sleeve to prevent collision damage during subsequent processes.

[0053] Step S2: Machining of the internal thread and metal sealing surface of the straight-connection sleeve:

[0054] Step S21: The sleeve blank with the machined external thread and sealing surface of the straight-connect type threaded joint is sent to the dedicated threading machine station at the other end via the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are used to clamp and center it. The height of the alloy pads of the six jaws at the front and rear is adjusted. The deviation between the center line of the sleeve blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa.

[0055] Step S22: Set the cutting speed to 100-120 m / min on the CNC program of the thread cutting machine, the cutting depth per pass to 0.5-0.8 mm / pass, the feed rate to 0.45-0.6 mm / revolution, and the cutting in 2-3 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.35±0.1 mm, a length of ≥120 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm.

[0056] Step S23: Change the tool position of the tool holder, use a dedicated internal boring tapered tool holder, set the cutting speed to 70-90 m / min on the CNC program of the threading machine, the depth of cut per pass is 0.30-0.40 mm / pass, the feed rate is 0.25-0.35 mm / revolution, and the tool passes in 1-2 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, and perform cutting according to the requirement of a 1:16 taper in diameter and length, to prepare for the internal threading and machining of the internal sealing surface in the next station.

[0057] Step S24: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 72–80 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.18–0.22 mm, the feed rate to 4 mm / revolution, and constant pitch cutting in 10–12 passes. Use a specially designed profile thread cutter (single tooth, tooth height 1.306±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 m; guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively) to ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within ±0.05 mm. Machining is employed at the sealing surface: The CNC program of the threading machine is set to a cutting speed of 68–72 m / min, a depth of cut of 0.16–0.18 mm per pass, a feed rate of 0.08 mm / revolution, and 2–3 passes. This ensures the diameter tolerance of the external metal sealing surface is controlled within ±0.05 mm, and the surface roughness Ra is controlled at 1.6 μm. Using specialized measuring tools, the internal thread diameter and the sealing surface diameter are controlled within ±0.05 mm.

[0058] The cutting cooling method has been improved by using a special cutting fluid instead of the original tool tip coolant channel. This allows the coolant to be sprayed directly onto the tool cutting edge and cutting area, increasing pressure and flow rate for effective machining cooling.

[0059] Step S3, Surface Treatment:

[0060] Because the casing string needs to be repeatedly tightened and loosened during construction and use to ensure the integrity of the threads and sealing surfaces, according to relevant standards, it needs to be tightened three times and loosened twice to prevent sticking. Therefore, the threads and metal sealing surfaces need to be surface treated.

[0061] The sleeves, machined and inspected at both ends, are conveyed to the dedicated phosphate treatment station via a walking beam. The end joints are immersed in a phosphate bath and slowly rotated at a rate of 1–2 rpm to ensure uniform phosphate treatment. After 30–35 minutes, they are removed and dried. The phosphate film thickness is measured to be 10–12 μm, and the film layer is uniform and dense.

[0062] Figure 3 This is a physical image of a high-strength direct-connection oil casing and connector according to the present invention, as shown below. Figure 3 As shown, the relevant performance of the oil casing joint processed by the present invention was finally tested. The actual performance test was carried out in the third laboratory according to ISO 13679 standard: three-on, two-off, non-stick. The results are shown in Table 1 below. Through tensile, external pressure and internal pressure tests, the measured results all exceeded the design values ​​in the table below.

[0063] Table 1. Measured performance results and standard requirements of oil casing joints processed using the method of this invention.

[0064]

[0065] This processing method increases the pass rate of high-strength direct-connection sleeve joints of this specification from 53% to 88%.

[0066] Example 1:

[0067] Step S1: Machining of the external thread and metal sealing surface of the straight-connection sleeve:

[0068] Step S11: Place the sleeve blank (i.e., the tube body size is Φ139.7×7.72 mm, both ends of the tube have been upset and thickened, and the entire length has been heat treated. After the tube ends are upset and thickened, the outer diameter is Φ147.5 mm and the upset length is 122 mm; after the tube ends are upset and thickened, the inner diameter is Φ118.4 mm and the inner thickening length is 132 mm) on the material table and send it to the special threading machine station through the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are clamped and centered. The height of the alloy pads of the six jaws at the front and rear is adjusted. The center line of the tube blank is adjusted with 11 MPa hydraulic pressure, and the deviation from the center line of the threading machine is 0.02 mm.

[0069] Step S12: Set the cutting speed to 110 m / min on the CNC program of the threading machine, the cutting depth per pass to 0.6 mm / pass, the feed rate to 0.5 mm / revolution, and perform 3 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.58 mm, a length of 116 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.56 mm, a length of 98 mm, and a surface roughness Ra of 6.4 μm.

[0070] Step S13: Change the tool position of the tool holder, set the cutting speed to 90 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.38 mm / pass, the feed rate to 0.30 mm / revolution, and perform two passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45° to perform cutting according to the requirement of a 1:16 taper in diameter and length, in order to prepare for threading and machining of the sealing surface in the next station.

[0071] Step S14: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 80 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.22 mm, the feed rate to 4 mm / revolution, and constant pitch cutting. Perform cutting in 8 passes using a specially designed thread profiler (single tooth, tooth height 1.206±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 mm, guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively). Ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within +0.04 mm. Machining was performed on the sealing surface: The CNC program on the threading machine was set to a cutting speed of 72 m / min, a depth of cut of 0.18 mm per pass, a feed rate of 0.08 mm / revolution, and 3 passes. This ensured that the diameter tolerance of the outer metal sealing surface was controlled within ±0.03 mm, and the surface quality was controlled within Ra1.6 μm. Using specialized measuring tools, the external thread diameter was controlled within +0.03 mm, and the sealing surface diameter within +0.02 mm.

[0072] The cutting cooling method has been improved by using a special cutting fluid instead of the original tool tip coolant channel. This allows the coolant to be sprayed directly onto the tool cutting edge and cutting area, increasing pressure and flow rate for effective machining cooling.

[0073] Cover the machined straight-connection threaded joint's external thread and sealing surface with a special plastic steel protective sleeve to prevent collision damage during subsequent processes.

[0074] Step S2: Machining of the internal thread and metal sealing surface of the straight-connection sleeve.

[0075] Step S21: The sleeve blank with the machined external thread and sealing surface of the straight-connect type threaded joint is sent to the dedicated threading machine station at the other end via the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are used to clamp and center it. The height of the alloy pads of the six jaws at the front and rear is adjusted. The deviation between the center line of the sleeve blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using 11MPa hydraulic pressure.

[0076] Step S22: Set the cutting speed to 110 m / min on the CNC program of the thread cutting machine, the cutting depth per pass to 0.6 mm / pass, the feed rate to 0.5 mm / revolution, and the cutting process to 3 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.42 mm, a length of 124 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.58 mm, a length of 98 mm, and a surface roughness Ra of 6.4 μm.

[0077] Step S23: Change the tool position of the tool holder, use a dedicated internal boring tapered tool holder, set the cutting speed to 78 m / min on the CNC program of the threading machine, the depth of cut per pass is 0.32 mm / pass, the feed rate is 0.28 mm / revolution, and the tool passes in 2 passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45° to perform cutting according to the requirement of a 1:16 taper in diameter and length, in order to prepare for the internal threading and machining of the internal sealing surface in the next station.

[0078] Step S24: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 76 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.20 mm, the feed rate to 4 mm / revolution, and constant pitch cutting. Perform 12 passes using a specially designed profile thread cutter (single tooth, tooth height 1.306±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 m; guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively). Ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within ±0.03 mm. Machining was performed on the sealing surface: The CNC program of the threading machine was set to a cutting speed of 70 m / min, a depth of cut of 0.16 mm per pass, a feed rate of 0.08 mm / revolution, and 3 passes. This ensured that the diameter tolerance of the outer metal sealing surface was controlled within ±0.03 mm, and the surface roughness was controlled within Ra 1.6 μm. Using specialized measuring tools, the internal thread diameter and the sealing surface diameter were controlled within ±0.04 mm.

[0079] Using the method of this invention, 10 straight-connection sleeve threaded joints were processed continuously, and 8 of them passed the inspection, with a pass rate of 80%.

[0080] Example 2:

[0081] Step S1: Machining of the external thread and metal sealing surface of the straight-connection sleeve:

[0082] Step S11: Place the sleeve blank (i.e., the tube body size is Φ139.7×7.72 mm, both ends of the tube have been upset and thickened, and the entire length has been heat treated. After the upset and thickened tube ends, the outer diameter is Φ147.8 mm and the upset length is 126 mm; after the upset and thickened tube ends, the inner diameter is Φ118.4 mm and the inner thickening length is 132 mm) side by side on the material table, and send it to the special threading machine station through the walking beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are used to clamp and center it. Adjust the height of the alloy pads of the six jaws at the front and rear. Use 12 MPa hydraulic pressure to adjust the deviation between the center line of the tube blank and the center line of the threading machine tool to not exceed 0.02 mm.

[0083] Step S12: Set the cutting speed to 118 m / min on the CNC program of the thread cutting machine, the cutting depth per pass to 0.78 mm / pass, the feed rate to 0.55 mm / revolution, and perform two passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.52 mm, a length of 116 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.62 mm, a length of 98 mm, and a surface roughness Ra of 6.4 μm.

[0084] Step S13: Change the tool position of the tool holder, set the cutting speed to 95 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.42 mm / pass, the feed rate to 0.32 mm / revolution, and one pass. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45° to perform cutting according to the requirement of a 1:16 taper in diameter and length, in order to prepare for threading and machining of the sealing surface in the next station.

[0085] Step S14: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 84 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.24 mm / pass, the feed rate to 4 mm / revolution, and constant pitch cutting. Perform cutting in 8 passes using a specially designed thread profiler (single tooth, tooth height 1.206±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 mm, guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively). Ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within ±0.03 mm. Machining was performed on the sealing surface: The CNC program of the threading machine was set to a cutting speed of 76 m / min, a depth of cut of 0.20 mm per pass, a feed rate of 0.08 mm / revolution, and two passes. This ensured that the diameter tolerance of the outer metal sealing surface was controlled within ±0.04 mm, and the surface roughness Ra was controlled at 1.6 μm. Using specialized measuring tools, the external thread diameter was controlled within ±0.04 mm, and the sealing surface diameter within ±0.03 mm.

[0086] Step S2: Machining of the internal thread and metal sealing surface of the straight-connection sleeve.

[0087] Step S21: The sleeve blank with the machined external thread and sealing surface of the straight-connect type threaded joint is sent to the dedicated threading machine station at the other end via the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length (position). The front and rear hydraulic jaws of the machine tool are used to clamp and center it. The height of the alloy pads of the front and rear six jaws is adjusted. The deviation between the center line of the sleeve blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa.

[0088] Step S22: Set the cutting speed to 118 m / min on the CNC program of the threading machine, the cutting depth per pass to 0.78 mm / pass, the feed rate to 0.55 mm / revolution, and perform two passes. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90° to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.28 mm, a length of 124 mm, and a surface roughness Ra of 12.5 μm. At the same time, using a tool position on another tool holder, also using a YB435 carbide tool with a radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.58 mm, a length of 96 mm, and a surface roughness Ra of 6.4 μm.

[0089] Step S23: Change the tool position of the tool holder, use a dedicated internal boring tapered tool holder, set the cutting speed to 88 m / min on the CNC program of the threading machine, the depth of cut per pass is 0.38 mm / pass, the feed rate is 0.32 mm / revolution, and the tool passes once. Use a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, and perform cutting according to the requirement of a 1:16 taper in diameter and length to prepare for the internal threading and machining of the internal sealing surface in the next station.

[0090] Step S24: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting speed to 78 m / min on the CNC program of the threading machine, the depth of cut per pass to 0.20 mm, the feed rate to 4 mm / revolution, and constant pitch cutting. Perform 10 passes using a specially designed profile thread cutter (single tooth, tooth height 1.306±0.05 mm, pitch 4±0.05 mm, bearing angle 15°, tooth tip and root radius at the bearing surface 0.15±0.05 m; guide angle 45°, tooth tip and root radius at the guide surface 0.38±0.05 mm and 0.56±0.05 mm respectively). Ensure the thread surface quality reaches a roughness Ra of 3.2 μm. The thread diameter tolerance is controlled within ±0.04 mm. Machining was performed on the sealing surface: a cutting speed of 70 m / min was set on the CNC program, with a depth of cut of 0.18 mm per pass, a feed rate of 0.08 mm / revolution, and two passes. This ensured that the diameter tolerance of the outer metal sealing surface was controlled within ±0.04 mm, and the surface roughness Ra was controlled at 1.6 μm. Using specialized measuring tools, the internal thread diameter was controlled within ±0.04 mm, and the sealing surface diameter was controlled within ±0.03 mm.

[0091] Using the method of this invention, 10 straight-connection sleeve threaded joints were continuously processed, and 9 of them passed the inspection, with a pass rate of 90%.

[0092] Through the above implementation cases, the processing qualification rate of this specification of high-strength direct-connection threaded sleeve was increased from 53% to 88%.

[0093] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention 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 or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of processing a high strength straight through petroleum casing joint, characterized by, The method includes the following steps: Step S1: The oil casing billet, after undergoing smelting, continuous casting, rolling, upsetting and thickening and full-length heat treatment processes, is processed to produce external threads and metal sealing surfaces. Step S2: Machining the internal threads and metal sealing surface of the oil casing blank that has already undergone external thread and metal sealing surface machining; Step S3: Perform surface treatment on the threads and metal sealing surfaces of the oil casing blank that has already been machined for internal threads and metal sealing surfaces, thus completing the machining of the high-strength direct-connection oil casing joint. Step S1 specifically includes: Step S11: Place the sleeve blanks side by side on the material table and send them to the special threading machine station via the stepping beam. The sleeve blanks are then transported in by the automatic conveyor that is matched with the threading machine, and are fixed in length or position. The blanks are clamped and centered by the front and rear hydraulic jaws of the machine tool. The height of the alloy pads of the six jaws at the front and rear is adjusted. The deviation between the center line of the sleeve blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa. Step S12: Set the cutting parameters on the CNC program of the thread cutting machine to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.6±0.1 mm, a length of ≥110 mm, and a surface roughness Ra of 12.5 μm; at the same time, using the tool position on another tool holder, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm. Step S13: Change the tool position of the tool holder, set the cutting parameters on the CNC program of the threading machine, and perform cutting according to the set taper requirements to prepare for threading and machining of the sealing surface in the next station. Step S14: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting parameters on the CNC program of the threading machine to perform cutting, ensuring that the surface roughness Ra of the thread reaches 3.2 μm and the thread diameter tolerance is controlled within ±0.05 mm. Then, set the cutting parameters on the CNC program of the threading machine to perform cutting on the sealing surface, so that the diameter tolerance of the outer metal sealing surface is controlled within ±0.05 mm and the surface roughness Ra is controlled at 1.6 μm. Using a special measuring tool, the diameter of the outer thread is controlled within ±0.05 mm and the diameter of the sealing surface is controlled within ±0.05 mm. In step S12, the cutting parameters include: a cutting speed of 100-120 m / min, a cutting depth of 0.5-0.8 mm / cut, a feed rate of 0.45-0.6 mm / revolution, 2-3 passes, and a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90°; the tool position on the other tool holder uses a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°.

2. The processing method of a high-strength direct-connection oil casing joint according to claim 1, characterized in that, The chemical composition of the oil casing blank, by mass percentage, includes the following components: C: 0.10–0.35%, Mn: 0.20–1.20%, Cr: 0.4–1.50%, Mo: 0.40–1.0%, Si≤0.45%, Ni≤1.5%, P≤0.015%, S≤0.005%, with the balance being Fe and unavoidable impurities.

3. The processing method of a high-strength direct-connection oil casing joint according to claim 1, characterized in that... The sign lies in, The step S13, cutting parameters include: The cutting speed is 80-100 m / min, the depth of cut is 0.35-0.45 mm / cut, the feed rate is 0.25-0.35 mm / revolution, the cutting is done in 1-2 passes, and a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45° is used, with a taper of 1:16 in diameter and length.

4. The processing method of a high-strength direct-connection oil casing joint according to claim 1, characterized in that... The sign lies in, In the step S14, the cutting parameters include: The cutting speed is 78–85 m / min, the depth of cut is 0.20–0.25 mm / cut, the feed rate is 4 mm / revolution, constant pitch cutting is performed in 8–10 passes, and a specially designed thread profiler is used. The parameters of the specially designed thread profiler include: single tooth, tooth height of 1.206±0.05 mm, pitch of 4±0.05 mm, bearing angle of 15°, tooth tip and root radius at the bearing surface of 0.15±0.05 mm, guide angle of 45°, and tooth tip and root radius at the guide surface of 0.38±0.05 mm and 0.56±0.05 mm, respectively. The cutting parameters at the sealing surface include: cutting speed of 70-78 m / min, depth of cut of 0.18-0.20 mm / cut, feed rate of 0.08 mm / revolution, and 2-3 passes.

5. The processing method of a high-strength direct-connection oil casing joint according to claim 1, characterized in that, Step S2 specifically includes: Step S21: The sleeve blank with the machined external thread and sealing surface of the straight-connect type threaded joint is sent to the dedicated threading machine station at the other end through the stepping beam. The sleeve blank is transferred in by the automatic conveyor matched with the threading machine and fixed in length or position. It is clamped and centered by the front and rear hydraulic jaws of the machine tool. The height of the alloy pads of the front and rear six jaws is adjusted. The deviation between the center line of the tube blank and the center line of the threading machine is adjusted to not exceed 0.05 mm using a hydraulic pressure of 10-12 MPa. Step S22: Set the cutting parameters on the CNC program of the threading machine to machine the outer surface of the upset and thickened part of the tube end into an outer circle with a diameter of Φ143.35±0.1 mm, a length of ≥120 mm, and a surface roughness Ra of 12.5 μm; at the same time, using the tool position on another tool holder, also using a YB435 carbide tool with an arc radius of 1.6 mm and an angle of 45°, machine the inner surface of the upset part of the tube end into an inner hole with a diameter of Φ122.6±0.05 mm, a length of ≥95 mm, and a surface roughness Ra of 6.4 μm. Step S23: Change the tool position of the tool holder, use a special internal boring tapered tool holder, set the cutting parameters on the CNC program of the thread turning machine, and perform cutting according to the set taper requirements to prepare for the next station to turn the internal thread and process the internal sealing surface; Step S24: Rotate the tool holder to the threading and sealing surface machining station. Set the cutting parameters on the CNC program of the threading machine to perform cutting, ensuring that the surface roughness Ra of the thread reaches 3.2 μm; the thread diameter tolerance is controlled within ±0.05 mm. Then, set the cutting parameters on the CNC program of the threading machine to perform cutting on the sealing surface, so that the diameter tolerance of the inner metal sealing surface is controlled within ±0.05 mm, and the surface roughness Ra is controlled within 1.6 μm. Using a special measuring tool, the internal thread diameter is controlled within ±0.05 mm, and the sealing surface diameter is controlled within ±0.05 mm.

6. The method of claim 5, wherein the high strength straight through petroleum casing joint is characterized by, In step S22, the cutting parameters include: a cutting speed of 100-120 m / min, a cutting depth of 0.5-0.8 mm / cut, a feed rate of 0.45-0.6 mm / revolution, 2-3 passes, and a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 90°.

7. The method of claim 5, wherein the high strength straight through petroleum casing joint is characterized by, In step S23, the cutting parameters include: a cutting speed of 70-90 m / min, a cutting depth of 0.30-0.40 mm / cut, a feed rate of 0.25-0.35 mm / revolution, 1-2 passes, and the use of a YB435 carbide tool with a tip radius of 1.6 mm and an angle of 45°, with a diameter-to-length taper of 1:

16.

8. The method of claim 5, wherein the high strength straight through petroleum casing coupling is characterized by: In step S24, the cutting parameters include: a cutting speed of 72–80 m / min, a cutting depth of 0.18–0.22 mm / cut, a feed rate of 4 mm / revolution, constant pitch cutting, 10–12 passes, and the use of a specially designed profile threading tool; wherein, the parameters of the specially designed profile threading tool include: a single tooth with a tooth height of 1.306±0.05 mm, a pitch of 4±0.05 mm, a bearing angle of 15°, and a radius of curvature of the tooth tip and root at the bearing surface of 0.15±0.05 m; a guide angle of 45°, and radii of curvature of the tooth tip and root at the guide surface of 0.38±0.05 mm and 0.56±0.05 mm, respectively; The cutting parameters at the sealing surface include: cutting speed of 68-72 m / min, depth of cut of 0.16-0.18 mm / cut, feed rate of 0.08 mm / revolution, and 2-3 passes.

9. The processing method of a high-strength direct-connection oil casing joint according to claim 1, characterized in that, Step S3 specifically includes: The casing, with both ends machined and inspected, is conveyed to the phosphate-dedicated station by a walking beam. The end joints are immersed in a phosphate bath and slowly rotated at a rate of 1-2 revolutions per minute to ensure uniform phosphate treatment. After 30-35 minutes, the joints are removed, dried, and the phosphate film thickness is checked. If the thickness is 10-12 μm and the film is uniform and dense, the processing of the high-strength direct-connection oil casing joint is complete.

Images