A high-frequency induction seamless special-shaped titanium welded pipe and production method

Abstract

The present invention relates to the field of seamless special-shaped titanium welded pipes, and in particular to a high-frequency induction seamless special-shaped titanium welded pipe and a production method thereof, wherein the mother pipe undergoes a first straight-drawn cold-drawn diameter reduction, a second straight-drawn cold-drawn special-shaped pipe preforming and heat treatment, and then undergoes a third straight-drawn cold-drawn special-shaped pipe fine forming, and finally is formed by hydraulic shaping of an inner core. The seamless special-shaped titanium welded pipe produced by the present invention has very uniform wall thickness and outer diameter, and a dimensional accuracy of ±0.03-0.05mm, realizing a process route in which a thin-walled seamless special-shaped titanium pipe is directly prepared from a raw material strip coil by welding and cold drawing, thereby greatly reducing production costs.

Description

Technical Field

[0001] The invention relates to the field of seamless special-shaped titanium welded pipes, and in particular to a high-frequency induction seamless special-shaped titanium welded pipe and a production method thereof. Background Art

[0002] Currently, titanium tubes can generally only produce round tubes (seamless tubes and fusion welded tubes). Due to the characteristics of the seamless rolling process, it is impossible to produce special-shaped titanium tubes by rolling. Due to the low precision of the fusion welding process, there is still a minimum wall thickness limit when welding titanium tubes. The high temperature causes the weld zone and heat-affected zone to be too wide, and there is a large difference between the metallographic microstructure and the parent material, so it is impossible to directly make seamless special-shaped titanium welded tubes by welding. The cost of producing special-shaped tubes through the cold drawing process is too high to choose thin-walled seamless titanium tubes. The fusion welded titanium tubes also need to be annealed and cold rolled to make the weld and heat-affected zone consistent with the metallographic structure of the parent material. The cost is also not low. In addition, the production of special-shaped titanium tubes is currently subject to many restrictions such as deformation, symmetry, tube drawing medium, and mold opening accuracy, and there are few successful cases.

[0003] High-frequency induction straight-seam titanium welded pipe uses high-frequency current and extrusion rollers to implement solid-phase metal connection. The thinnest wall thickness that can be welded is 0.15mm, the maximum welding speed is 150m / min, the weld and heat-affected zone are extremely narrow, the weld strength is close to or equal to the parent material, and only polishing is required to complete the seam elimination treatment. The 1st-2nd cold drawing does not require annealing. High-frequency induction straight-seam titanium welded pipe is seamlessly cold drawn, reduced in diameter, reduced in wall and deformed into special shapes. The reduction rate and deformation are large, the precision and efficiency are high, and the manufacturing cost is low. Summary of the invention

[0004] Aiming at the problems existing in the background technology, a high-frequency induction seamless special-shaped titanium welded pipe and a production method are proposed. The wall thickness and outer diameter of the seamless special-shaped titanium welded pipe produced by the present invention are very uniform, and the dimensional accuracy is ±

[0005] 0.03-0.05mm, realizing the process route of thin-walled seamless special-shaped titanium tubes directly prepared from raw material strips through welding and cold drawing, which greatly reduces the production cost.

[0006] The present invention provides a high-frequency induction seamless special-shaped titanium welded pipe, which is made by a mother pipe undergoing a first pass of straight drawing and cold drawing to reduce the diameter, a second pass of special-shaped pipe preforming straight drawing and cold drawing and heat treatment, and then a third pass of special-shaped pipe fine forming straight drawing and cold drawing, and finally being hydraulically formed by an inner core.

[0007] The mother tube is a high-frequency induction straight seam welded titanium tube with internal and external scraping scars; the original weld on the surface of the prepared seamless special-shaped titanium welded tube is invisible after polishing, the wall thickness and outer diameter are uniform, and the original weld and heat-affected zone have the same structure and properties as the parent material in the length and circumferential directions, which are polygonal equiaxial structures of uniform size.

[0008] The present invention provides a method for producing a high-frequency induction seamless special-shaped titanium welded pipe, comprising the following steps:

[0009] S1. Selection and treatment of mother tube: High-frequency induction straight seam welded titanium tube with internal and external scratches is selected as the mother tube, and non-destructive testing is performed on the mother tube to ensure that the mother tube has no defects, and the surface is polished;

[0010] S2, straight drawing and cold drawing to reduce diameter: the mother tube selected in S1 is straight drawn in one pass using a special titanium tube cold drawing die and cold drawing medium to make a reduced diameter titanium welded tube; the titanium tube cold drawing die is a fixed external die, and its tube diameter needs to be determined according to the circumference of the special-shaped titanium welded tube;

[0011] S3, straight drawing cold drawing preforming: the reduced diameter titanium welded pipe is subjected to the second pass of special-shaped pipe preforming straight drawing cold drawing, the preforming outer mold is designed according to 50%-70% of the deformation of the special-shaped pipe, and the diameter is not reduced during the straight drawing cold drawing to prepare a preformed special-shaped titanium welded pipe;

[0012] S4, heat treatment: annealing the preformed special-shaped titanium welded tube 7 obtained in S3 in a vacuum annealing furnace;

[0013] S5, straight drawing cold drawing finishing forming: the preformed special-shaped titanium welded pipe obtained in S4 is subjected to the third special-shaped pipe finishing forming, the finishing forming outer die is designed according to 95%-98% of the deformation of the special-shaped pipe, and the straight drawing cold drawing is performed without reducing the diameter to form a finishing special-shaped titanium welded pipe;

[0014] S6, hydraulic inner core shaping: the finely formed special-shaped titanium welded pipe obtained in S5 is hydraulically shaped to the inner diameter by hydraulically pushing the push rod and the shaping inner core; the shaping inner core is accurately designed according to 100% of the deformation amount of the special-shaped pipe, with a tolerance of ±0.03-0.05mm, and finally a seamless special-shaped titanium welded pipe is made;

[0015] S7, cleaning and cutting: The seamless special-shaped titanium welded pipe obtained in S6 is ultrasonically cleaned and dried, and then cut according to the finished product length specifications to complete the production.

[0016] Preferably, in S1, the mother tube is a round tube with an outer diameter of 10 mm-80 mm and a wall thickness of 0.3 mm-1.5 mm.

[0017] Preferably, in S2, the diameter reduction ratio of each cold drawing pass is controlled between 20% and 36.5%.

[0018] Preferably, a straight drawing machine is used with a cold drawing speed of 15m-20m / min. The external molding die used is specially designed according to the low density and ductility of titanium metal. The cold drawing medium used must ensure viscosity, lubricity and the formation of a surface protective oil film.

[0019] Preferably, the first pass of the mother tube shrinkage does not require annealing, and when the deformation amount of each subsequent pass is greater than 20%, an intermediate annealing is added between every 1-2 passes of cold drawing.

[0020] Preferably, in S4, the heat treatment is annealing in an argon atmosphere, the temperature is controlled at 600° C.-650° C., and the insulation time is 20 minutes-30 minutes.

[0021] Preferably, the prepared seamless special-shaped titanium welded pipe has an outer diameter of 5 mm to 78 mm and a wall thickness of 0.3 mm to 1.5 mm, calculated based on the circumference.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] The wall thickness and outer diameter of the seamless special-shaped titanium welded pipe produced by the present invention are very uniform, and the dimensional accuracy is ±

[0024] 0.03-0.05mm, realizing the process route of thin-walled seamless special-shaped titanium tubes directly prepared from raw material strips through welding and cold drawing, which greatly reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a mother tube in an embodiment of the present invention;

[0026] Figure 2 This is a diagram showing the operation of straight drawing and cold drawing in one embodiment of the present invention;

[0027] Figure 3 This is a diagram showing the operation of straight-draw cold-drawn preforming in one embodiment of the present invention;

[0028] Figure 4 This is an operation diagram showing the straight drawing cold drawing finishing forming in one embodiment of the present invention;

[0029] Figure 5 This is a diagram showing the operation of hydraulic core shaping in one embodiment of the present invention;

[0030] Figure 6 is a cross-sectional view of the finished product of Example 2;

[0031] Figure 7 This is a cross-sectional view of the finished product of Example 3.

[0032] Figure numerals: 1. Mother tube; 2. Original weld; 3. Heat affected zone; 4. Titanium tube cold drawing die; 5. Reduced diameter titanium welded tube; 6. Preformed outer die; 7. Preformed special-shaped titanium welded tube; 8. Fine forming outer die; 9. Fine forming special-shaped titanium welded tube; 10. Hydraulic push rod; 11. Shaping inner core; 12. Seamless special-shaped titanium welded tube; 13. Seamless symmetrical special-shaped titanium welded tube; 14. Seamless asymmetric special-shaped titanium welded tube. DETAILED DESCRIPTION

[0033] Embodiment 1

[0034] The present invention provides a high-frequency induction seamless special-shaped titanium welded pipe, which is made by a mother pipe 1 that undergoes a first pass of straight drawing and cold drawing to reduce the diameter, a second pass of special-shaped pipe preforming straight drawing and cold drawing, and heat treatment, and then a third pass of special-shaped pipe fine forming straight drawing and cold drawing, and finally is formed by hydraulic shaping of an inner core.

[0035] like Figure 1 As shown, the mother tube 1 is a high-frequency induction straight seam welded titanium tube with internal and external scrapes; the prepared seamless special-shaped titanium welded tube 12 has an original weld 2 on the surface that is not visible after polishing, and has uniform wall thickness and outer diameter. The original weld 2 and the heat-affected zone 3 have the same structure and properties as the parent material in the length and circumferential directions, and are polygonal equiaxed structures of uniform size.

[0036] like Figure 2-5 As shown, the present invention provides a method for producing a high-frequency induction seamless special-shaped titanium welded pipe, comprising the following steps:

[0037] S1. Selection and treatment of mother tube 1: A high-frequency induction straight seam welded titanium tube with internal and external scratches is selected as mother tube 1, and non-destructive testing is performed on mother tube 1 to ensure that mother tube 1 has no defects, and the surface is polished;

[0038] S2, straight drawing and cold drawing to reduce diameter: the mother tube 1 selected in S1 is straight drawn in one pass using a special titanium tube cold drawing die 4 and a cold drawing medium to form a reduced diameter titanium welded tube 5; the titanium tube cold drawing die 4 is a fixed external die, and its tube diameter needs to be determined according to the circumference of the special-shaped titanium welded tube;

[0039] S3, straight drawing cold drawing preforming: the reduced diameter titanium welded tube 5 is subjected to the second pass of special-shaped tube preforming straight drawing cold drawing, the preforming outer die 6 is designed according to 50%-70% of the deformation of the special-shaped tube, and the diameter is not reduced during the straight drawing cold drawing to prepare a preformed special-shaped titanium welded tube 7;

[0040] S4, heat treatment: annealing the preformed special-shaped titanium welded tube 7 obtained in S3 in a vacuum annealing furnace to eliminate stress, so as to ensure that the structure and performance of the original weld zone and heat-affected zone of the prepared preformed special-shaped titanium welded tube 7 are completely consistent with those of the parent material, and are polygonal equiaxed structures of uniform size;

[0041] S5, straight drawing cold drawing finishing forming: the preformed special-shaped titanium welded tube 7 obtained in S4 is subjected to the third special-shaped tube finishing forming, the finishing forming outer die 8 is designed according to 95%-98% of the deformation of the special-shaped tube, and the diameter is not reduced during straight drawing cold drawing to form a finishing special-shaped titanium welded tube 9; the finishing forming outer die 8 is more fully deformed than the preformed outer die 6;

[0042] S6, hydraulic inner core shaping: the finely formed special-shaped titanium welded pipe 9 obtained in S5 is hydraulically shaped to the inner diameter by hydraulically pushing the push rod 10 and the shaping inner core 11; the shaping inner core 11 is precisely designed according to 100% of the deformation amount of the special-shaped pipe, with a tolerance of ±0.03-0.05mm, and finally a seamless special-shaped titanium welded pipe 12 is made;

[0043] S7, cleaning and cutting: the seamless special-shaped titanium welded pipe 12 obtained in S6 is ultrasonically cleaned and dried, and then cut according to the finished product length specification to complete the production.

[0044] Embodiment 2

[0045] The present invention provides a high-frequency induction seamless special-shaped titanium welded pipe, which is made by a mother pipe 1 that undergoes a first pass of straight drawing and cold drawing to reduce the diameter, a second pass of special-shaped pipe preforming straight drawing and cold drawing, and heat treatment, and then a third pass of special-shaped pipe fine forming straight drawing and cold drawing, and finally is formed by hydraulic shaping of an inner core.

[0046] like Figure 1 As shown, the mother tube 1 is a high-frequency induction straight seam welded titanium tube with internal and external scrapes; the prepared seamless special-shaped titanium welded tube 12 has an original weld 2 on the surface that is not visible after polishing, and has uniform wall thickness and outer diameter. The original weld 2 and the heat-affected zone 3 have the same structure and properties as the parent material in the length and circumferential directions, and are polygonal equiaxed structures of uniform size.

[0047] Furthermore, the mother tube 1 is a round tube with an outer diameter of 10mm-80mm and a wall thickness of 0.3mm-1.5mm.

[0048] Furthermore, the seamless special-shaped titanium welded pipe 12 is calculated based on the circumference, and the outer diameter is 5mm-78mm and the wall thickness is 0.3mm-1.5mm.

[0049] like Figure 6 As shown, this embodiment takes the production of a seamless symmetrical special-shaped titanium welded tube 13 with an outer diameter of 22.8 mm, a wall thickness of 0.6 mm, and a length of 300 mm as an example. The mother tube 1 is a TA1 grade high-frequency induction straight seam welded titanium tube with an outer diameter of 25 mm, a wall thickness of 0.6 mm, and a length of 1500 mm.

[0050] like Figure 2-5 As shown, the present invention provides a method for producing a high-frequency induction seamless special-shaped titanium welded pipe, comprising the following steps:

[0051] S1. Selection and treatment of mother tube 1: A high-frequency induction straight seam welded titanium tube with internal and external scratches is selected as mother tube 1, and non-destructive testing is performed on mother tube 1 to ensure that mother tube 1 has no defects, and the surface is polished;

[0052] S2, straight drawing and cold drawing to reduce diameter: the mother tube 1 selected in S1 is straight drawn in one pass using a special titanium tube cold drawing die 4 and a cold drawing medium to form a reduced diameter titanium welded tube 5; the titanium tube cold drawing die 4 is a fixed external die, and its tube diameter needs to be determined according to the circumference of the special-shaped titanium welded tube;

[0053] S3, straight drawing cold drawing preforming: the reduced diameter titanium welded tube 5 is subjected to the second pass of special-shaped tube preforming straight drawing cold drawing, the preforming outer die 6 is designed according to 50%-70% of the deformation of the special-shaped tube, and the diameter is not reduced during the straight drawing cold drawing to prepare a preformed special-shaped titanium welded tube 7;

[0054] S4, heat treatment: annealing the preformed special-shaped titanium welded tube 7 obtained in S3 in a vacuum annealing furnace to eliminate stress, so as to ensure that the structure and performance of the original weld zone and heat-affected zone of the prepared preformed special-shaped titanium welded tube 7 are completely consistent with those of the parent material, and are polygonal equiaxed structures of uniform size;

[0055] S5, straight drawing cold drawing finishing forming: the preformed special-shaped titanium welded tube 7 obtained in S4 is subjected to the third special-shaped tube finishing forming, the finishing forming outer die 8 is designed according to 95%-98% of the deformation of the special-shaped tube, and the diameter is not reduced during straight drawing cold drawing to form a finishing special-shaped titanium welded tube 9; the finishing forming outer die 8 is more fully deformed than the preformed outer die 6;

[0056] S6, hydraulic inner core shaping: the finely formed special-shaped titanium welded pipe 9 obtained in S5 is hydraulically shaped to the inner diameter by hydraulically pushing the push rod 10 and the shaping inner core 11; the shaping inner core 11 is precisely designed according to 100% of the deformation amount of the special-shaped pipe, with a tolerance of ±0.03-0.05mm, and finally a seamless special-shaped titanium welded pipe 12 is made;

[0057] S7, cleaning and cutting: the seamless special-shaped titanium welded pipe 12 obtained in S6 is ultrasonically cleaned and dried, and then cut according to the finished product length specification to complete the production.

[0058] Furthermore, in S2, the diameter reduction rate of each cold drawing pass is controlled between 20% and 36.5%.

[0059] Furthermore, a straight drawing machine is used with a cold drawing speed of 15m-20m / minute. The external molding die used is specially designed according to the characteristics of titanium metal's low density and ductility. The cold drawing medium used must ensure viscosity, lubricity and the formation of a surface protective oil film to avoid surface wire drawing and tube breakage.

[0060] Furthermore, the mother tube 1 does not need annealing for the first pass of diameter reduction, and when the deformation amount of each subsequent pass is greater than 20%, an intermediate annealing is added between every 1-2 passes of cold drawing.

[0061] Furthermore, in S4, the heat treatment is annealing in an argon atmosphere, the temperature is controlled at 600° C.-650° C., and the insulation time is 20 minutes-30 minutes.

[0062] The present embodiment comprises three straight-drawing cold drawing passes and one inner diameter hydraulic forming pass. The first cold drawing pass is for diameter reduction, and a diameter reduction outer die with an outer diameter of 22.8 mm is used. The second special-shaped tube preforming cold drawing pass performs outer diameter deformation according to 50%-70% of the deformation amount of the special-shaped tube. The third special-shaped tube fine forming cold drawing pass performs outer diameter deformation according to 95%-98% of the deformation amount of the special-shaped tube. The first inner diameter hydraulic forming pass performs inner diameter deformation according to 100% of the deformation amount of the special-shaped tube. Finally, a seamless symmetrical special-shaped titanium welded tube 13 with an outer diameter of 22.8 mm, a wall thickness of 0.6 mm, and a length of 300 mm calculated according to the circumference is obtained.

[0063] The original weld 2 of the seamless symmetrical special-shaped titanium welded tube 13 prepared through the above steps is invisible on the surface, the wall thickness and outer diameter are uniform, and the original weld 2 and the heat-affected zone 3 have the same organization and performance as the mother tube 1 in the length direction and circumferential direction, which is a polygonal equiaxed organization of uniform size. Its wall thickness and outer diameter are very uniform, with a dimensional accuracy of ±0.03, realizing the process route of preparing thin-walled seamless special-shaped titanium tubes directly from raw material strip coils through welding and cold drawing, which greatly reduces the production cost.

[0064] Embodiment 3

[0065] The present invention provides a high-frequency induction seamless special-shaped titanium welded pipe, which is made by a mother pipe 1 that undergoes a first pass of straight drawing and cold drawing to reduce the diameter, a second pass of special-shaped pipe preforming straight drawing and cold drawing, and heat treatment, and then a third pass of special-shaped pipe fine forming straight drawing and cold drawing, and finally is formed by hydraulic shaping of an inner core.

[0066] like Figure 1 As shown, the mother tube 1 is a high-frequency induction straight seam welded titanium tube with internal and external scrapes; the prepared seamless special-shaped titanium welded tube 12 has an original weld 2 on the surface that is not visible after polishing, and has uniform wall thickness and outer diameter. The original weld 2 and the heat-affected zone 3 have the same structure and properties as the parent material in the length and circumferential directions, and are polygonal equiaxed structures of uniform size.

[0067] Furthermore, the mother tube 1 is a round tube with an outer diameter of 10mm-80mm and a wall thickness of 0.3mm-1.5mm.

[0068] Furthermore, the seamless special-shaped titanium welded pipe 12 is calculated based on the circumference, and the outer diameter is 5mm-78mm and the wall thickness is 0.3mm-1.5mm.

[0069] like Figure 7 As shown, in this embodiment, the production of a seamless asymmetric special-shaped titanium welded tube 14 with an outer diameter of 14.2 mm, a wall thickness of 0.6 mm, and a length of 62.2 mm is taken as an example. The mother tube 1 uses a TA1 grade high-frequency induction straight seam welded titanium tube with an outer diameter of 19 mm, a wall thickness of 0.6 mm, and a length of 1500 mm.

[0070] like Figure 2-5 As shown, the present invention provides a method for producing a high-frequency induction seamless special-shaped titanium welded pipe, comprising the following steps:

[0071] S1. Selection and treatment of mother tube 1: A high-frequency induction straight seam welded titanium tube with internal and external scratches is selected as mother tube 1, and non-destructive testing is performed on mother tube 1 to ensure that mother tube 1 has no defects, and the surface is polished;

[0072] S2, straight drawing and cold drawing to reduce diameter: the mother tube 1 selected in S1 is straight drawn in one pass using a special titanium tube cold drawing die 4 and a cold drawing medium to form a reduced diameter titanium welded tube 5; the titanium tube cold drawing die 4 is a fixed external die, and its tube diameter needs to be determined according to the circumference of the special-shaped titanium welded tube;

[0073] S3, straight drawing cold drawing preforming: the reduced diameter titanium welded tube 5 is subjected to the second pass of special-shaped tube preforming straight drawing cold drawing, the preforming outer die 6 is designed according to 50%-70% of the deformation of the special-shaped tube, and the diameter is not reduced during the straight drawing cold drawing to prepare a preformed special-shaped titanium welded tube 7;

[0074] S4, heat treatment: annealing the preformed special-shaped titanium welded tube 7 obtained in S3 in a vacuum annealing furnace to eliminate stress, so as to ensure that the structure and performance of the original weld zone and heat-affected zone of the prepared preformed special-shaped titanium welded tube 7 are completely consistent with those of the parent material, and are polygonal equiaxed structures of uniform size;

[0075] S5, straight drawing cold drawing finishing forming: the preformed special-shaped titanium welded tube 7 obtained in S4 is subjected to the third special-shaped tube finishing forming, the finishing forming outer die 8 is designed according to 95%-98% of the deformation of the special-shaped tube, and the diameter is not reduced during straight drawing cold drawing to form a finishing special-shaped titanium welded tube 9; the finishing forming outer die 8 is more fully deformed than the preformed outer die 6;

[0076] S6, hydraulic inner core shaping: the finely formed special-shaped titanium welded pipe 9 obtained in S5 is hydraulically shaped to the inner diameter by hydraulically pushing the push rod 10 and the shaping inner core 11; the shaping inner core 11 is precisely designed according to 100% of the deformation amount of the special-shaped pipe, with a tolerance of ±0.03-0.05mm, and finally a seamless special-shaped titanium welded pipe 12 is made;

[0077] S7, cleaning and cutting: the seamless special-shaped titanium welded pipe 12 obtained in S6 is ultrasonically cleaned and dried, and then cut according to the finished product length specification to complete the production.

[0078] Furthermore, in S2, the diameter reduction rate of each cold drawing pass is controlled between 20% and 36.5%.

[0079] Furthermore, a straight drawing machine is used with a cold drawing speed of 15m-20m / minute. The external molding die used is specially designed according to the characteristics of titanium metal's low density and ductility. The cold drawing medium used must ensure viscosity, lubricity and the formation of a surface protective oil film to avoid surface wire drawing and tube breakage.

[0080] Furthermore, the mother tube 1 does not need annealing for the first pass of diameter reduction, and when the deformation amount of each subsequent pass is greater than 20%, an intermediate annealing is added between every 1-2 passes of cold drawing.

[0081] Furthermore, in S4, the heat treatment is annealing in an argon atmosphere, the temperature is controlled at 600° C.-650° C., and the insulation time is 20 minutes-30 minutes.

[0082] The present embodiment comprises three straight-drawing cold drawing passes and one inner diameter hydraulic forming pass. The first cold drawing pass is for diameter reduction, and a diameter reduction outer die with an outer diameter of 14.2 mm is used. The second special-shaped tube preforming cold drawing pass is for outer diameter deformation according to 50%-60% of the deformation amount of the special-shaped tube. The third special-shaped tube finishing cold drawing pass is for outer diameter deformation according to 95%-98% of the deformation amount of the special-shaped tube. The last inner diameter hydraulic forming pass is for inner diameter deformation according to 100% of the deformation amount of the special-shaped tube. Finally, a seamless asymmetric special-shaped titanium welded tube 14 with an outer diameter of 14.2 mm, a wall thickness of 0.6 mm, and a length of 62.2 mm calculated according to the circumference is obtained.

[0083] The original weld 2 of the seamless asymmetric special-shaped titanium welded tube 14 prepared through the above steps is invisible on the surface, the wall thickness and outer diameter are uniform, and the original weld 2 and the heat-affected zone 3 have the same organization and performance as the mother tube 1 in the length direction and circumferential direction, which is a polygonal equiaxed organization of uniform size. Its wall thickness and outer diameter are very uniform, with a dimensional accuracy of ±0.03, realizing the process route of preparing thin-walled seamless special-shaped titanium tubes directly from raw material coils through welding and cold drawing, which greatly reduces the production cost.

[0084] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A high-frequency induction seamless special-shaped titanium welded pipe, characterized in that: The mother tube (1) is subjected to a first straight drawing cold drawing process for reducing the diameter, a second straight drawing cold drawing process for preforming the special-shaped tube, and heat treatment, and then a third straight drawing cold drawing process for fine forming the special-shaped tube, and finally an inner core is hydraulically formed to form the tube; The mother tube (1) is a high-frequency induction straight seam welded titanium tube with internal and external scraping scars; the prepared seamless special-shaped titanium welded tube (12) has an original weld seam (2) on the surface that is invisible after polishing, has uniform wall thickness and outer diameter, and the original weld seam (2) and the heat-affected zone (3) have the same structure and properties as the mother material in the length direction and circumferential direction, and are polygonal equiaxed structures of uniform size; The production method of the high-frequency induction seamless special-shaped titanium welded pipe comprises the following steps: S1. Selection and treatment of the mother tube (1): A high-frequency induction straight seam welded titanium tube with internal and external scratches is selected as the mother tube (1). The mother tube (1) is subjected to non-destructive testing to ensure that the mother tube (1) is free of defects, and the surface is polished. The mother tube (1) is a round tube with an outer diameter of 10 mm to 80 mm and a wall thickness of 0.3 mm to 1.5 mm. S2, straight drawing and cold drawing and reducing the diameter: the mother tube (1) selected in S1 is straight drawn in one pass using a titanium tube cold drawing die (4) and a cold drawing medium to form a reduced diameter titanium welded tube (5); the titanium tube cold drawing die (4) is a fixed outer die, and its tube diameter needs to be determined according to the circumference of the special-shaped titanium welded tube; the cold drawing reduction rate of this pass is controlled between 20% and 36.5%; S3, straight drawing cold drawing preforming: the reduced diameter titanium welded tube (5) is subjected to a second pass of straight drawing cold drawing to form a special-shaped tube preforming, the preforming outer die (6) is designed according to 50%-70% of the deformation of the special-shaped tube, and no reduction is performed during the straight drawing cold drawing to prepare a preformed special-shaped titanium welded tube (7); S4, heat treatment: annealing the preformed special-shaped titanium welded pipe (7) obtained in S3 in a vacuum annealing furnace; S5, straight drawing and cold drawing finishing forming: the preformed special-shaped titanium welded tube (7) obtained in S4 is subjected to the third special-shaped tube finishing forming, the finishing forming outer die (8) is designed according to 95%-98% of the deformation amount of the special-shaped tube, and no diameter reduction is performed during straight drawing and cold drawing to form a finishing special-shaped titanium welded tube (9); S6, hydraulic inner core shaping: the inner diameter of the finely formed special-shaped titanium welded pipe (9) obtained in S5 is hydraulically shaped by hydraulically pushing the push rod (10) and the shaping inner core (11); the shaping inner core (11) is precisely designed according to 100% of the deformation amount of the special-shaped pipe, and finally a seamless special-shaped titanium welded pipe (12) is made; the prepared seamless special-shaped titanium welded pipe (12) has an outer diameter of 5mm-78mm and a wall thickness of 0.3mm-1.5mm according to the circumference. S7, cleaning and cutting: the seamless special-shaped titanium welded pipe (12) obtained in S6 is ultrasonically cleaned and dried, and then cut according to the finished product length specification to complete the production.

2. The high-frequency induction seamless special-shaped titanium welded pipe according to claim 1 is characterized in that: S2 uses a straight drawing machine with a cold drawing speed of 15m-20m / min.

3. The high-frequency induction seamless special-shaped titanium welded pipe according to claim 1 is characterized in that: In S4, the heat treatment is annealing in an argon atmosphere, the temperature is controlled at 600° C.-650° C., and the insulation time is 20 minutes-30 minutes.

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