Manufacturing method of TA2 pure titanium concentric reducer, flaring tool and sizing system

Abstract

The application belongs to the field of metal material processing manufacturing, and particularly relates to a TA2 pure titanium concentric reducing pipe manufacturing method, a flaring tool and a sizing system. The TA2 pure titanium concentric reducing pipe manufacturing method comprises the following steps: S1. blanking; S2. blank heat treatment; S3. medium-frequency hot spinning and flaring forming; S4. cold shrinking and sizing forming; S5. beveling and dimension inspection; S6. stress relief heat treatment; S7. surface treatment; and S8. hydrogen removal treatment. The TA2 pure titanium concentric reducing pipe manufacturing method can ensure the TA2 reducing pipe forming while effectively avoiding the wrinkle phenomenon of the inner wall of the TA2 reducing pipe, and the performance, quality and yield of the TA2 reducing pipe can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology and manufacturing, specifically relating to a method for manufacturing TA2 pure titanium concentric reducers, flaring tooling, and sizing system. Background Technology

[0002] TA2 is an industrially pure titanium material with advantages such as low density, high tensile strength, high specific strength (tensile strength / density), non-magnetic properties, low coefficient of linear expansion, and corrosion resistance. It is widely used in aerospace, shipbuilding, petrochemical, and biomedical fields. However, both cold and hot working of TA2 are relatively difficult. During cold deformation, TA2 does not have a distinct yield point; its yield strength is close to its ultimate tensile strength, and its yield strength ratio (Rp0.2 / Rm) is relatively high. Compared to high-purity titanium, TA2 has significantly improved strength but significantly reduced plasticity, with a room temperature elongation of approximately 20%. Simultaneously, TA2 is very sensitive to hot working temperatures, with a narrow hot forging temperature range, making hot working more challenging. Because titanium is a chemically highly reactive metal, at higher temperatures, it can undergo titanium absorption reactions with elements and compounds such as C, H, O, and N, causing embrittlement, reducing thermoplasticity, and further increasing the difficulty of hot working.

[0003] TA2 pure titanium reducers are used to connect pipes of two different diameters and are an important pipe fitting commonly used in shipbuilding, marine engineering, and chemical industries. Traditional forming processes for TA2 reducers mainly include cold-pressing or hot-pressing. The cold-pressing process involves placing a tube blank with the same diameter as the reducer's large end into a forming mold, and then pressing it "from the outside in" along the tube blank's axial direction, causing the metal to move along the mold cavity and shrink to form the shape. Due to the low elongation of TA2, when cold-pressing TA2 reducers are used, the large deformation of the tube blank can easily lead to cracks at the small end and the diameter-changing section of the reducer due to work hardening and metal accumulation, reducing the yield. Furthermore, because TA2 has a very high work hardening effect, there will be greater stress during cold forming, placing higher demands on the strength, rigidity, and processing capabilities of the equipment and molds. On the other hand, when TA2 reducers are formed using hot pressing, a significant amount of metal accumulates at the smaller end, increasing the wall thickness and making forming difficult. This also increases the risk of cracks and wrinkles on the inner wall of the reducer. Furthermore, TA2 is difficult to grind and cut, and tends to "stick" to the cutting tool. These internal wrinkles are not only difficult to remove but also lead to a sharp increase in manufacturing processes and costs. Therefore, this issue urgently needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing TA2 pure titanium concentric reducers. This method can effectively avoid wrinkles on the inner wall of TA2 reducers while ensuring the processing and forming of the TA2 reducers. The performance, quality and yield of TA2 reducers can also be effectively improved.

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

[0006] The manufacturing method of TA2 pure titanium concentric reducer is characterized by including the following steps:

[0007] S1. Material feeding

[0008] The blank is obtained by cutting seamless steel pipes, then the burrs are removed, and foreign matter on the surface of the blank is thoroughly removed with acetone;

[0009] S2. Heat treatment of billet

[0010] A vacuum furnace was selected for heat treatment of the billet; the heat treatment temperature of the billet was 680℃; the holding time was 5 min / mm depending on the billet wall thickness; cooling was carried out inside the furnace.

[0011] S3. Medium-frequency hot spinning flaring molding

[0012] The billet is clamped onto a rotating device, and the medium-frequency induction coil and rotating device are started to induction heat the billet. The heating area is the part that needs to be flared, and a flaring fixture is used for medium-frequency hot-spinning flaring. The initial hot-spinning temperature of the TA2 billet is 900℃, and the hot-spinning is stopped when the temperature drops below 700℃. At the same time, argon gas protection is used throughout the hot-spinning process, with an argon purity of not less than 99.99% and an argon flow rate of 30L / min. The billet rotation speed during medium-frequency induction heating is 3m / s-5m / s.

[0013] When the billet temperature is heated to 900℃, a flaring fixture is used for medium-frequency hot rotary flaring forming. The flaring fixture is pushed along the billet axis at a speed of 2mm / s-6mm / s until the reducer is formed. Then, before the reducer temperature exceeds 250℃, argon gas is continuously introduced for protection. When the reducer temperature drops below 250℃, the argon gas is stopped, the rotation is stopped, and the reducer is removed from the rotating equipment.

[0014] S4. Cold shrink sizing forming

[0015] Through cold shrinking sizing forming, a straight pipe section with a set length and a set diameter is formed at the large end of the reducer. At the same time, the large end and the straight pipe section are sizing to a set size.

[0016] S5. Beveling and dimensional inspection

[0017] On a lathe, the two ends of the reducer are beveled one by one: first, the two ends of the reducer are flattened, and then beveled, leaving a blunt edge. During machining, a W18Cr4V tool is used on the lathe, with a cutting speed of 30-34 m / min, a depth of cut of 0.6-1.5 mm, and a feed rate of 0.38-0.13 mm / revolution; then the dimensions are inspected.

[0018] S6. Stress-relieving heat treatment

[0019] Stress relief treatment of the reducer is performed using a vacuum furnace or an inert gas protected furnace. The annealing temperature in the furnace is 500℃, and the holding time is 5min / mm based on the maximum wall thickness of the reducer, followed by cooling in the furnace. When using an inert gas protected furnace, the inert gas is high-purity argon with a purity of not less than 99.99%.

[0020] S7. Surface Treatment

[0021] Pickling is used to remove the oxide scale from the surface of the reducer. The pickling time is 3-5 minutes and the pickling temperature is 15-30℃. After pickling, the reducer is rinsed with water and then dried with clean, oil-free, dry compressed air.

[0022] S8. Hydrogen removal treatment

[0023] A vacuum furnace was selected for hydrogen removal treatment. The hydrogen removal treatment temperature was 560℃, the holding time was 2 hours, and the furnace was cooled inside or cooled to below 150℃ before being taken out of the furnace.

[0024] Preferably, in step S7, the pickling solution formula is as follows:

[0025] Nitric acid (HNO3, 65%-68%) 200-400 ml / L;

[0026] Hydrofluoric acid (HF, 40%) 50-80 ml / L;

[0027] Water and the remainder.

[0028] Preferably, the ultimate vacuum pressure of each vacuum furnace is no greater than 6.7 × 10⁻⁶. 3 Pa.

[0029] Preferably, in step S1, a horizontal band saw is used for cutting.

[0030] Preferably, in step S1, the cutting length of the seamless steel pipe is calculated using the following formula:

[0031]

[0032] in:

[0033] D1 is the diameter of the smaller end of the reducer, in mm;

[0034] 'a' represents the wall thickness of the smaller end of the reducer, in mm.

[0035] D2 is the diameter of the larger end of the reducer, in mm;

[0036] b represents the wall thickness of the larger end of the reducer, in mm;

[0037] H represents the axial length of the reducer, in mm.

[0038] Preferably, a flaring fixture is used in the aforementioned method for manufacturing TA2 pure titanium concentric reducers. The fixture is characterized by: a hollow screw with a through cavity forming an argon gas inlet channel; an adjusting nut threaded onto the hollow screw, a rotating ring coaxially arranged at the adjusting nut, and a connecting disc with a diameter smaller than the inner diameter of the blank at the front end of the hollow screw; the tail end of a rear connecting rod hinged to the rotating ring, the head end of the rear connecting rod hinged to the tail end of the front connecting rod, and the head end of the front connecting rod hinged to the connecting disc, with the axes of each hinge parallel to each other and perpendicular to the axis of the hollow screw; a working unit consisting of one rear connecting rod and one front connecting rod that cooperate with each other, and three or more working units arranged sequentially around the axis of the hollow screw; bearings coaxially mounted on the front connecting rods are fitted with rolling sleeves for directly pressing against the inner wall of the blank, and the rolling sleeves together form a conical working part for flaring the blank.

[0039] Preferably, the sizing system, applied to the aforementioned TA2 pure titanium concentric reducer manufacturing method, is characterized by: a frame, on which a main shaft driven by a power source is arranged, the main shaft passing through the table surface of the frame from bottom to top and a main mold roller coaxially mounted on the table surface; a swing plate with one end vertically hinged to the table surface, two sets of auxiliary mold rollers vertically mounted on the swing plate along its axis, the three sets of mold rollers cooperating to radially extrude and shape the large end of the reducer; with the side of the swing plate on which the auxiliary mold rollers are mounted as the inner side, a force-applying part is also provided on the outer side of the swing plate for applying force along the swing direction of the swing plate, thereby causing the auxiliary mold rollers to extrude the reducer.

[0040] Preferably, the hinge end of the swing plate is mounted on the support plate, and the support plate and the bolt groove fixed on the table form a bolt fixing fit; the force application part includes a threaded seat mounted on the table, the adjusting screw and the threaded seat form a threaded fit, and the front end of the adjusting screw forms a pressing end against the outside of the swing plate, and the rear end of the adjusting screw is coaxially arranged with a handwheel.

[0041] Preferably, the length direction of the bolt groove is parallel to the axis direction of the adjusting screw, and the bolt groove has two or more sets of bolt fixing points arranged along the length direction, so as to adjust the installation position of the support plate relative to the bolt groove.

[0042] Preferably, the power source includes a motor, a gear reducer, and a worm gear reducer arranged sequentially along the power path; the output gear of the worm gear reducer meshes with the power input gear at the main shaft, thereby achieving the power transmission effect.

[0043] The beneficial effects of this invention are as follows:

[0044] 1) Through the above scheme, the present invention relies on the sequential arrangement of blanking, billet heat treatment, medium frequency hot spinning flaring forming, cold shrinking sizing forming, beveling and dimensional inspection, stress relief heat treatment, surface treatment and final hydrogen removal treatment, which can ensure the processing and forming of TA2 reducers while effectively avoiding wrinkles on the inner wall of TA2 reducers. The performance, quality and yield of TA2 reducers can also be effectively improved.

[0045] More specifically, the TA2 billet heat treatment process stabilizes the billet's microstructure and improves its plasticity while simultaneously dehydrogenating the raw materials, facilitating subsequent molding. The medium-frequency hot-spinning flaring process eliminates the need for an external mold, reducing mold investment costs. Furthermore, unlike traditional outside-to-inside flaring, this invention's inside-to-outside flaring process allows for real-time observation of the expanded seamless steel pipe's inner wall, enabling real-time monitoring of the metal's plastic deformation process, timely detection of molding defects or cracks, and rapid process adjustments, thus improving yield. The hot-spinning flaring process utilizes argon gas protection throughout, preventing TA2 from absorbing gas at high temperatures and thus preventing embrittlement—a multi-benefit approach. Additionally, because TA2 is difficult to machine and prone to "tool sticking," resulting in shortened tool life and significant surface scratches and roughness, this invention also includes beveling for TA2 reducers. To ensure product quality, this invention provides corresponding machining process parameters and defines parameters for stress-relieving heat treatment and surface treatment. Considering the characteristics of TA2 material, a dehydrogenation process was subsequently added to improve the performance and quality of TA2 material.

[0046] 2) Based on the above solution, the present invention further provides a cutting formula for reducers, which further avoids material waste or product scrapping due to cutting problems.

[0047] 3) It is worth noting that this invention differs from the traditional “outside-in” narrowing process. Instead, it breaks away from rigid thinking and adopts an “inside-out” widening method. Many quality control problems caused by the widening process that cannot be solved by existing technologies are solved through the series of processes of this invention, so as to ensure the quality of finished products and achieve remarkable results.

[0048] Thus, this invention employs a novel flaring tooling for medium-frequency hot rotary flaring molding, which makes the operation simpler and more flexible, while also providing more viewing angles. In addition, thanks to the hollow screw design, the introduction of argon gas will not be affected, and it has the advantages of early formation of molding defects or cracks and high argon gas protection efficiency.

[0049] 4) Furthermore, traditional cold shrink sizing molding requires different molds for different specifications of reducers, resulting in high mold investment costs. Therefore, this invention also developed a sizing system for TA2 reducers. By reducing the diameter of the large end of the reducer, it is sizing to a standard outer diameter size, which is more applicable to concentric reducers of different specifications and sizes, reduces mold investment costs, and makes demolding extremely convenient, improving production efficiency and facilitating mass production. Attached Figure Description

[0050] Figure 1 This is a flowchart of the method of the present invention;

[0051] Figure 2 This is a front view of the flaring fixture;

[0052] Figure 3 for Figure 2 The left view;

[0053] Figure 4 and Figure 5 A schematic diagram showing the working state of the flaring tool at different flaring angles;

[0054] Figure 6 This is a top view of the sizing system;

[0055] Figure 7 for Figure 6 Schematic diagram of sectional view along direction AA;

[0056] Figure 8 This is a schematic diagram showing the assembly location of the power source.

[0057] The actual correspondence between the reference numerals and component names in this invention is as follows:

[0058] a-Reducer;

[0059] 10 - Hollow screw; 11 - Through cavity;

[0060] 20 - Adjusting nut; 21 - Rotary ring;

[0061] 30-Connecting disk;

[0062] 41 - Rear link; 42 - Front link;

[0063] 50-Rolling sleeve;

[0064] 60-rack;

[0065] 70 - Main spindle; 71 - Power input gear;

[0066] 81-Main mold roller; 82-Secondary mold roller;

[0067] 91-Swing plate; 92-Panel; 93-Bolt groove;

[0068] 100 - Power source; 101 - Motor; 102 - Gear reducer; 103 - Worm gear reducer;

[0069] 110 - Force application part; 111 - Threaded seat; 112 - Adjusting screw; 113 - Handwheel. Detailed Implementation

[0070] For ease of understanding, this section combines... Figure 1-8 The specific structure and operation of the present invention are further described below:

[0071] Specifically, such as Figure 1 As shown, the actual manufacturing process of this invention includes the following steps:

[0072] I. Material feeding

[0073] Seamless steel pipe of material TA is selected as the blank for reducer a. The outer diameter and wall thickness of the seamless steel pipe are the same as those of the smaller end of reducer a. A horizontal band saw is used for blanking. After blanking, burrs are removed, and acetone is used to thoroughly remove lubricating grease, cutting fluid, and other harmful foreign matter from the surface of the blank.

[0074] Given the current lack of a formula for calculating the blanking length of reducer A, the blanking length is often too long or too short, easily leading to the structural dimensions of reducer A not meeting standard requirements, thus causing product scrap or material waste. This invention, considering the material forming characteristics, provides the following formula for calculating the blanking length:

[0075]

[0076] in:

[0077] D1 is the diameter of the smaller end of reducer a, in mm;

[0078] 'a' represents the wall thickness of the smaller end of the reducer, in mm.

[0079] D2 is the diameter of the larger end of reducer a, in mm;

[0080] b represents the wall thickness of the larger end of the reducer (a), in mm.

[0081] H represents the axial length of reducer a, in mm.

[0082] Taking a reducer a with diameters of Φ88.9×5.49-Φ141.3×2.77 and H=127mm as an example, according to the above formula, the calculated cutting length is 206.45mm. After rounding the cutting length, a Φ88.9×5.49 titanium steel pipe with a length of 207mm is taken, which meets the cutting size requirements of common reducers a in GB / T27684-2011 "Seamless and Welded Pipe Fittings of Titanium and Titanium Alloys", thus verifying its practicality and the accuracy of the calculation results.

[0083] II. Heat Treatment

[0084] Seamless steel pipes made of TA2 material are heat-treated at a temperature of 680℃. The holding time is selected according to the wall thickness of the billet, and is generally controlled at 5min / mm. That is, for every 1mm increase in the wall thickness of the billet, the holding time is increased by 5min. Cooling is then performed in the furnace.

[0085] The purpose of heat treatment is twofold: first, to restore recrystallization, obtaining a stable and ductile microstructure, improving the plasticity of the billet, and facilitating subsequent hot expansion and plasticizing processes; second, to remove hydrogen. Seamless steel pipes are prone to hydrogen accumulation before and during blanking, leading to a decrease in the material's mechanical properties. Heat treatment can remove hydrogen and reduce the hydrogen content in the material. To avoid unnecessary oxidation and TA2 gas absorption reactions during heat treatment, a vacuum furnace is selected for heat treatment. The ultimate vacuum pressure of the vacuum furnace should not exceed 6.7 × 10⁻⁶. 3 Pa.

[0086] Traditional TA2 reducer manufacturing processes lack this step, directly molding the material after blanking without considering the characteristics of TA2 material, failing to remove hydrogen from the TA2 billet, and not improving the material's plasticity, often resulting in a low yield. Unlike traditional methods, the heat treatment process in this invention uses appropriately selected holding temperature and time, achieving a stable microstructure and improving material plasticity while simultaneously dehydrogenating the material, facilitating subsequent molding. Furthermore, the use of a vacuum furnace reduces titanium oxidation and gas absorption reactions.

[0087] III. Medium-frequency hot spinning flaring molding

[0088] After annealing, the billet is clamped on a rotating device, preferably using a four-jaw chuck, ensuring that the billet's centerline coincides with the rotation centerline. The intermediate-frequency induction coil and rotating device are started to induction heat the billet, specifically the area requiring flaring. The flaring fixture of this invention is used for intermediate-frequency hot-spinning flaring. The initial flaring temperature is 900°C, and flaring is stopped when the temperature drops below 700°C. Because oxygen significantly affects the plasticity of titanium, argon gas protection is used throughout the hot-spinning flaring process. The argon purity is not less than 99.99% to prevent TA2 from absorbing gas at high temperatures, ensuring that the TA2 material does not oxidize or become embrittled.

[0089] The actual structure of the flaring tool of the present invention is as follows: Figure 2-5 As shown, it includes a hollow screw 10 with a fixed end. After the hollow screw 10 is fixed, its centerline coincides with the centerline of the blank. The adjusting nut 20 can adjust the included angle between the rolling sleeve 50 and the hollow screw 10, so that it can be referenced as shown in the figure. Figure 4-5 The diagram illustrates the hot expansion forming of reducers (a) with different diameter ratios. In practical design, H13 heat-resistant mold steel can be considered for the rolling sleeve 50. A limiting block is installed on the front connecting rod 42, and a plane bearing is placed between the rolling sleeve 50 and the limiting block to form a bearing fit. During the billet rotation, the rolling sleeve 50 can rotate around the centerline of the front connecting rod 42, thereby reducing the friction between the inner wall of the seamless steel pipe and the rolling sleeve 50. When the billet temperature is heated to 900℃, the fixed end of the flaring fixture is pushed horizontally to hot expand the billet. The hollow screw 10, front connecting rod 42, and rear connecting rod 41 form a stable triangle, ensuring reliable and balanced force distribution. In the design, hinged connections can also be formed with the connecting disc 30 and the rotating ring 21 via pins to achieve adjustment of the flaring angle. The center of the hollow screw 10 is an argon gas vent, or through cavity 11, which can be protected by introducing argon gas during the hot expansion forming process.

[0090] The rotation speed of the billet during medium-frequency induction heating should be controlled between 3 m / s and 5 m / s. Argon gas should be injected through the argon vent for inert gas protection, with a purity of not less than 99.99% and a flow rate of 30 L / min. When the billet temperature reaches 900℃, the flaring fixture should be horizontally pushed into the billet at a speed of 2 mm / s to 6 mm / s. After the reducer a is flared, the outer wall temperature should be measured using an infrared thermometer. Argon gas should be continuously supplied for protection until the temperature drops below 250℃. Once the temperature has dropped below 250℃, the argon supply should be stopped, rotation should be stopped, and reducer a can be removed.

[0091] This invention employs special tooling for medium-frequency hot rotary flaring forming, which has the following innovations compared to traditional diameter reduction cold pressing or diameter reduction hot pressing forming processes:

[0092] First, traditional diameter reduction processes require different molds for different specifications of reducer tubes a, resulting in extremely high mold investment costs. This invention eliminates the need for external molds, significantly reducing mold investment costs. It can produce reducer tubes a with different diameter ratios by adjusting the tooling, achieving the effect of "one mold for multiple uses".

[0093] Secondly, in traditional diameter reduction processes, a large amount of metal material accumulates at the smaller end of the reducer (a), increasing its wall thickness and making forming difficult. This also increases the risk of cracks and wrinkles on the inner wall of the reducer (a). Furthermore, the TA2 material is difficult to grind and cut, and tends to "stick" to the tool, making internal wrinkles difficult to remove. In contrast, this invention takes a different approach, breaking with conventional thinking by adopting an "inside-out" flaring method. This makes the easily deformable inner wall structure of the special TA2 material blank easier to observe during the flaring process. This allows for real-time monitoring of the metal's plastic deformation throughout the flaring process; if abnormalities occur, forming can be quickly stopped and the process adjusted, thereby improving the yield. Many quality control problems caused by the flaring process that cannot be solved by existing technologies are addressed through the series of processes in this invention, ensuring the quality of the finished product. The flaring method also prevents the material at the small end of the reducer a from thickening, making it less prone to cracking. Furthermore, the inner wall of the reducer a is formed by rollers, which reduces friction and machining operations. It can even drastically reduce or eliminate wrinkles on the inner wall of the reducer a, achieving multiple benefits in one fell swoop.

[0094] Finally, traditional diameter reduction processes rely on external mold control for forming. A design flaw in this process makes inert gas protection during hot diameter reduction difficult. For materials like TA2, which are highly susceptible to oxidation and gas absorption reactions, traditional processes often rely on increasing the blank machining allowance and then removing it through grinding and cutting after forming, thus increasing both blank and machining costs. This invention, using a through cavity 11 and flaring fixtures, employs argon gas protection throughout the hot flaring process, reducing titanium oxidation and preventing TA2 from absorbing gas at high temperatures, thus preventing TA2 material from becoming embrittled. This indirectly reduces blank and machining costs while maintaining material properties.

[0095] IV. Cold Shrink Sizing Forming

[0096] After the TA2 reducer is formed by medium-frequency hot expansion, the large end is flared, which is not conducive to subsequent assembly and welding. A certain length of straight pipe section needs to be left at the large end, and the large end needs to be reduced in diameter and sized to the standard outer diameter size.

[0097] This invention provides a cold shrink sizing forming process and develops corresponding equipment and molds, as detailed below:

[0098] Construction reference for sizing system Figure 6-8As shown, the system includes a power motor 101, which drives a small pulley located on its output shaft to rotate. The power is then transmitted to a large pulley via a V-belt. The large pulley is connected to a gear reducer 102, which reduces speed while increasing torque. The gear reducer 102 is then connected to a worm gear reducer 103 via a coupling, further reducing speed and increasing torque. A small gear-shaped output gear is mounted on the upper end of the worm gear reducer 103. This output gear meshes with the power input gear 71 on the main shaft 70, reducing speed and further increasing torque. A main mold roller 81 is mounted on the main shaft 70, providing power for the reduction of the diameter of the reducing tube a.

[0099] In the design, the forming mold is mainly formed by the cooperation of a main mold roller 81 and a secondary mold roller 82. There is one main mold roller and two secondary mold rollers 82. Each mold roller is cylindrical, forming a shape like... Figure 6 The distribution is shown as equilateral or isosceles triangles. During assembly, the secondary mold roller 82 is mounted on the inner side of the swing plate 91 via the secondary mold shaft, thereby causing at least a portion of the roller surface of the secondary mold roller 82 to be as shown... Figure 6 The inner side is protruding as shown, thereby achieving a radial pressure effect on the large end of the reducer a. One end of the swing plate 91 can rotate around the support plate 92. The support plate 92 is fastened to the bolt groove 93 on the table by bolts, so that the support plate 92 can move back and forth to accommodate the reduction forming of reducers a of different diameters.

[0100] In actual cold shrink forming, the steps are as follows:

[0101] Take the reducer a as an example Figure 6-7 The reducer a is positioned between the main mold roller 81 and the auxiliary mold roller 82, tangent to their outer circumferences. Once the reducer a is in close contact with the mold rollers, the power source 100 is activated, and the power motor 101 transmits power to the main mold roller 81. The main mold roller 81 drives the reducer a and the auxiliary mold roller 82 to rotate accordingly. Manually rotating the handwheel 113, by adjusting the screw 112 and the threaded seat 111, transmits force to the inner side of the swing plate 91. As the inner side of the swing plate 91 rotates around the support plate 92, it forces the auxiliary mold roller 82 to press forward against the larger end of the reducer a. While rotating, the reducer a achieves diameter reduction at its larger end, ultimately setting the outer diameter of the larger end of the reducer a to a standard outer diameter size.

[0102] Thus, this invention abandons the problem of traditional cold shrink sizing forming, where different molds are required for different specifications of reducers a, resulting in high mold investment costs. The above-mentioned cold shrink sizing forming equipment and process of this invention are applicable to reducers a of different specifications and sizes, reducing mold investment costs, and demolding is also extremely convenient, improving production efficiency and facilitating mass production.

[0103] V. Beveling and Dimensional Inspection

[0104] On a lathe, beveling is performed on both ends of reducer a. First, both ends of reducer a are flattened, ensuring that the height of reducer a meets the requirements of the process flow chart or drawings. After flattening, beveling is performed, with the beveling angle conforming to the process flow chart or drawings. A blunt edge is required after beveling, and its dimensions must meet the dimensional tolerances of the process flow chart or drawings. After machining, the geometric dimensions of reducer a, its beveling angle and deviation, height and deviation, end plane deviation, blunt edge and deviation, etc., are inspected and must all meet the requirements of the process flow chart and drawings.

[0105] Because titanium has a low thermal conductivity, the heat generated during beveling is difficult to dissipate through the material being cut. Furthermore, titanium has a low specific heat per unit volume, leading to a tendency for localized temperature rise and tool sticking. This shortens tool life and results in larger scratches and roughness on the machined surface. Therefore, for beveling TA2 reducers, to ensure product quality, this invention preferably uses a W18Cr4V tool with a cutting speed of 30-34 m / min, a depth of cut of 0.6-1.5 mm, and a feed rate of 0.38-0.13 mm / revolution. Practical experience shows significant effectiveness.

[0106] VI. Stress-relieving heat treatment

[0107] The reducer a undergoes stress-relief treatment to eliminate internal stress generated during the forming process. The stress-relief annealing temperature is 500℃, and the holding time is selected based on the maximum wall thickness of reducer a, generally controlled at 5 min / mm, followed by furnace cooling. Similarly, to avoid unnecessary oxidation and TA2 gas absorption reaction during heat treatment, a vacuum furnace or inert gas protected furnace is preferred for heat treatment; the ultimate vacuum pressure of the vacuum furnace should not exceed 6.7 × 10⁻⁶. 3 Pa, the inert gas is high-purity argon, and the purity of argon is not less than 99.99%.

[0108] VII. Surface Treatment

[0109] The oxide scale on the surface of the reducer (a) is removed by pickling. The pickling solution formula is: 200-400 ml / L nitric acid (HNO3, 65%-68%), 50-80 ml / L hydrofluoric acid (HF, 40%), with the remainder being water and the balance. During pickling, the pickling time is 3-5 minutes, and the pickling temperature is 15-30℃. The surface after pickling should be smooth, with a metallic luster or silvery-white color, and free of any remaining oxide scale. After pickling, the surface is rinsed with water and dried with clean, oil-free, dry compressed air.

[0110] VIII. Hydrogen Removal Treatment

[0111] During surface treatment, the mixed acid solution can cause hydrogen enrichment in the TA2 material. Therefore, the reducer (a) needs to undergo hydrogen removal treatment. The hydrogen removal temperature is 560℃, and the holding time is 2 hours. A vacuum furnace is used for hydrogen removal. The ultimate vacuum pressure of the vacuum furnace should not exceed 6.7 × 10⁻⁶. 3 Pa, cooled inside the furnace or cooled to below 150°C before being removed from the furnace.

[0112] It is worth noting that the traditional TA2 reducer production process lacks this step, and is basically completed after surface treatment without taking into account the characteristics of TA2 material. Since the mixed acid solution will increase the hydrogen content of TA2 material during the surface treatment process, this step can be used to further improve the material performance and ensure the high quality of the finished product.

[0113] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar methods that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description.

[0114] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0115] All technical parts not described in detail in this invention are publicly known technologies.

Claims

1. A method of manufacturing a TA2 pure titanium concentric reducer, characterized by Includes the following steps: S1. Material feeding The blank is obtained by cutting seamless steel pipes, then the burrs are removed, and foreign matter on the surface of the blank is thoroughly removed with acetone; S2. Heat treatment of billet A vacuum furnace was selected for heat treatment of the billet; the heat treatment temperature of the billet was 680℃; the holding time was 5 min / mm depending on the billet wall thickness; cooling was carried out inside the furnace. S3. Medium-frequency hot spinning flaring molding The billet is clamped onto a rotating device, and the medium-frequency induction coil and rotating device are started to induction heat the billet. The heating area is the part that needs to be flared, and a flaring fixture is used for medium-frequency hot-spinning flaring. The initial hot-spinning temperature of the TA2 billet is 900℃, and the hot-spinning is stopped when the temperature drops below 700℃. At the same time, argon gas protection is used throughout the hot-spinning process, with an argon purity of not less than 99.99% and an argon flow rate of 30L / min. The billet rotation speed during medium-frequency induction heating is 3m / s-5m / s. When the billet temperature is heated to 900℃, a flaring fixture is used for medium-frequency hot rotary flaring forming. The flaring fixture is pushed along the billet axis at a speed of 2mm / s-6mm / s until the reducer is formed. Then, before the reducer temperature exceeds 250℃, argon gas is continuously introduced for protection. When the reducer temperature drops below 250℃, the argon gas is stopped, the rotation is stopped, and the reducer is removed from the rotating equipment. S4. Cold shrink sizing forming Through cold shrinking sizing forming, a straight pipe section with a set length and a set diameter is formed at the large end of the reducer. At the same time, the large end and the straight pipe section are sizing to a set size. S5. Beveling and dimensional inspection On a lathe, the two ends of the reducer are beveled one by one: first, the two ends of the reducer are flattened, and then beveled, leaving a blunt edge. During machining, a W18Cr4V tool is used on the lathe, with a cutting speed of 30-34m / min, a depth of cut of 0.6-1.5mm, and a feed rate of 0.38-0.13mm / revolution. Then, dimensional inspection is performed; S6. Stress-relieving heat treatment Stress relief treatment of the reducer is performed using a vacuum furnace or an inert gas protected furnace. The annealing temperature in the furnace is 500℃, and the holding time is 5min / mm based on the maximum wall thickness of the reducer, followed by cooling in the furnace. When using an inert gas protected furnace, the inert gas is high-purity argon with a purity of not less than 99.99%. S7. Surface Treatment Pickling is used to remove the oxide scale from the surface of the reducer. The pickling time is 3-5 minutes and the pickling temperature is 15-30℃. After pickling, the reducer is rinsed with water and then dried with clean, oil-free, dry compressed air. S8. Hydrogen removal treatment A vacuum furnace was selected for hydrogen removal treatment. The hydrogen removal treatment temperature was 560℃, the holding time was 2 hours, and the furnace was cooled inside or cooled to below 150℃ before being taken out of the furnace.

2. The method of manufacturing a TA2 pure titanium concentric reducer according to claim 1, characterized by: In step S7, the pickling solution formula is as follows: 200-400 ml / L of nitric acid with a mass fraction of 65%–68%; 50-80 ml / L of hydrofluoric acid with a mass fraction of 40%; Water and the remainder.

3. The method for manufacturing TA2 pure titanium concentric reducers according to claim 1, characterized in that: The limit vacuum pressure of each vacuum furnace is not more than 6.7x10 3 Pa.

4. The method for manufacturing TA2 pure titanium concentric reducers according to claim 1, characterized in that: In step S1, a horizontal band saw is used for cutting.

5. The method for manufacturing TA2 pure titanium concentric reducers according to claim 1, 2, 3, or 4, characterized in that: In step S1, the cutting length of the seamless steel pipe is calculated using the following formula: in: D 1 The smaller end diameter of the reducer is in mm. a The wall thickness of the smaller end of the reducer is in mm. D 2 The larger end diameter of the reducer is in mm. b The wall thickness of the larger end of the reducer is in mm. H This refers to the axial length of the reducer, in mm.

6. A flaring fixture, applied to the manufacturing method of TA2 pure titanium concentric reducer as described in claim 1, characterized in that: The device includes a hollow screw (10) with a through cavity (11), which forms an argon gas inlet channel; an adjusting nut (20) is threaded onto the hollow screw (10), and a rotating ring (21) is coaxially arranged at the adjusting nut (20); a connecting disc (30) with a diameter smaller than the inner diameter of the blank is arranged at the front end of the hollow screw (10); the tail end of the rear connecting rod (41) is hinged to the rotating ring (21), and the head end of the rear connecting rod (41) is hinged to the tail end of the front connecting rod (42); the head end of the front connecting rod (42) is hinged to the tail end of the front connecting rod (42). Hinged at the connecting plate (30), the axes of each hinge are parallel to each other and perpendicular to the axis of the hollow screw (10); a set of working units is formed by a rear connecting rod (41) and a front connecting rod (42) that cooperate with each other, and there are three or more working units that are evenly distributed around the axis of the hollow screw (10); the front connecting rod (42) is equipped with bearings that are coaxial and have rolling sleeves (50) for directly pressing against the inner wall of the billet, and the rolling sleeves (50) are combined to form a conical working part for flaring the billet.

7. A sizing system, wherein the sizing system is applied to the manufacturing method of TA2 pure titanium concentric reducer as described in claim 1, characterized in that: The machine includes a frame (60), on which a main shaft (70) driven by a power source (100) is arranged. The main shaft (70) passes through the table of the frame (60) from bottom to top and a main mold roller (81) is coaxially mounted on the table. The machine also includes a swing plate (91) with one end vertically hinged to the table. Two sets of auxiliary mold rollers (82) are vertically mounted on the axis of the swing plate (91). The three sets of mold rollers cooperate to radially extrude and shape the large end of the reducer. With the side on the swing plate (91) on which the auxiliary mold rollers (82) are mounted as the inner side, a force-applying part (110) is also provided on the outer side of the swing plate (91) for applying force along the swing direction of the swing plate (91), so that the auxiliary mold rollers (82) extrude the reducer.

8. The sizing system according to claim 7, characterized in that: The hinge end of the swing plate (91) is installed on the support plate (92), and the support plate (92) and the bolt groove (93) fixed on the table form a bolt fixing fit; the force application part (110) includes a threaded seat (111) installed on the table, the adjusting screw (112) and the threaded seat (111) form a threaded fit, and the front end of the adjusting screw (112) forms a pressing end against the outside of the swing plate (91), and the rear end of the adjusting screw (112) is coaxially arranged with a handwheel (113).

9. The sizing system according to claim 8, characterized in that: The length of the bolt groove (93) is parallel to the axis of the adjusting screw (112), and the bolt groove (93) has two or more sets of bolt fixing points arranged along the length of the groove, which are used to adjust the installation position of the support plate (92) relative to the bolt groove (93).

10. The sizing system according to claim 7, characterized in that: The power source (100) includes a power motor (101), a gear reducer (102) and a worm gear reducer (103) arranged sequentially along the power path; the output gear of the worm gear reducer (103) meshes with the power input gear (71) at the main shaft (70) to achieve the power transmission effect.

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