Pure titanium and titanium alloy seamless tube rolling method based on MPM unit

Abstract

The invention discloses a pure titanium and titanium alloy seamless tube rolling method based on an MPM unit. Comprising the steps of pipe blank fixed-length cutting, pipe blank centering and drilling, pipe blank quality and chemical component detection, antioxidant brushing on the surface of a pipe blank, pipe blank protection heating, bacterium type perforating, MPM unit continuous pipe rolling, induction reheating, tension reducing, two times of straightening with temperature, cooling bed cooling, fixed-length saw cutting and pipe body surface quality detection. Carrying out mechanical property and geometric dimension detection; carrying out nondestructive flaw detection; and related process parameters are limited. The invention aims to provide the pure titanium and titanium alloy seamless tube rolling method based on the MPM unit, which is low in production cost, high in production efficiency, high in yield, high in dimensional precision, high in toughness performance matching and good in surface quality.

Description

Technical Field

[0001] The invention belongs to the technical field of production technology of titanium and titanium alloy seamless pipes, and in particular relates to a rolling method of pure titanium and titanium alloy seamless pipes based on an MPM unit. Background Art

[0002] At present, pure titanium and titanium alloy pipes are mainly used in the fields of aerospace and military industry. With the development of the national economy, only a few research institutes and manufacturers in China have begun to conduct preliminary research in the field of oil and gas drilling. At present, most titanium and titanium alloy pipes are prepared by the method of sheet rolling + welding, which has the disadvantages of long manufacturing cycle, large number of welds, high production cost and poor reliability. The patent of this invention is based on the existing MPM continuous pipe rolling unit production line and the characteristics of plastic deformation of pure titanium and titanium alloy materials, and the key production technology for manufacturing pure titanium and titanium alloy seamless pipes, that is, the control technology of tube billet quality, the control technology of tube billet surface brushing, the control technology of annular heating furnace, the control technology of mushroom punching machine, the control technology of MPM continuous rolling unit, the control technology of induction reheating, the control technology of tension reducing unit and the control technology of continuous two-time belt temperature straightening, so as to realize the comprehensive performance of pure titanium and titanium alloy seamless pipes with low production cost, high production efficiency, high yield rate, high dimensional accuracy, high strength and toughness matching and good surface quality; the heating process and continuous rolling process that meet the requirements of titanium and titanium alloy seamless pipes are designed.

[0003] After searching, it was found that three literature patents are most relevant to the utility model technology, and the specific contents are described as follows:

[0004] Patent document CN 201610900656.8 discloses a hot rolling method for industrial pure titanium and titanium alloys. The invention is based on a hot rolling mill to produce industrial pure titanium and titanium alloy strips, adopts a steel-titanium co-linear efficient production mode, and inserts the rolling of the strip steel. The working rolls of the rolling mill adopt a negative roll profile, and the roll profile curve can automatically center the rolled piece, and can control the cross-sectional shape of the rolled piece according to the special material and special process of the rolled piece, and can achieve stable operation of the equipment, with the characteristics of low production cost and high production efficiency. However, since the invention is based on a hot rolling mill to produce industrial pure titanium and titanium alloy strips, the invention cannot be used to produce pure titanium and titanium alloy seamless pipes.

[0005] Patent document CN 201611065459.5 discloses a production process for hot-rolled large-diameter thin-walled titanium alloy seamless pipes. The invention sprays a closed isolation coating on the surface of the billet, and the coating is dropped off the billet after it is taken out of the furnace, thereby avoiding the reaction of the titanium alloy billet with oxygen, nitrogen, carbon, iron, etc. at high temperature, and the problem of hydrogen absorption. The inclined grate bars and the turning device between the punching machine and the tube rolling machine are replaced with a fast transfer device, and a fast transfer device is set between the sizing machine and the straightening machine to shorten the transfer time and reduce the cooling of the rough pipe. However, the invention does not specify the production unit of the titanium alloy seamless pipe. In addition to the temperature system, other disclosed parameters are mostly the range of the equipment. Therefore, it has no reference value.

[0006] Patent document CN 202210991837.1 discloses a production process for hot-rolled large-diameter thin-walled titanium alloy seamless pipes, including a conveyor belt, a fusion casting machine, a forging machine, a quenching machine, a round tube casting machine and a low-temperature cold air cooling machine. The titanium metal billet is screened and fed into the casting furnace of the fusion casting machine → the titanium alloy liquid is poured onto the forging table → the semi-solidified titanium alloy liquid is forged and purified → the round tube casting machine produces a titanium alloy seamless pipe → the low-temperature cold air cooling machine cools the titanium alloy pipe. The invention produces titanium alloy seamless pipes based on centrifugal casting. Since no recrystallization has occurred, the pure titanium and titanium alloy seamless pipes produced have coarse structure and cast defects. Summary of the invention

[0007] The purpose of the present invention is to provide a pure titanium and titanium alloy seamless pipe rolling method based on an MPM unit with low production cost, high production efficiency, high yield rate, high dimensional accuracy, high strength and toughness matching and good surface quality.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention discloses a pure titanium and titanium alloy seamless pipe rolling method based on an MPM unit, comprising tube blank cutting to a fixed length → tube blank centering drilling → tube blank quality and chemical composition detection → tube blank surface brushing with an antioxidant → tube blank protective heating → mushroom punching → MPM unit continuous tube rolling → induction reheating → tension reduction → two-time belt temperature straightening → cooling on a cooling bed → fixed length sawing → tube body surface quality, mechanical properties and geometric dimension detection → non-destructive flaw detection, and is characterized in that:

[0010] Preparation of tube blank: Drill a centering hole at one end of the tube blank. The diameter of the centering hole is The depth is 80mm; the tube blank is chamfered to form an angle of 40° to 45° perpendicular to the axial direction of the tube blank; at the same time, a roller brush is used to evenly apply water-based boron nitride coating to the surface of the tube blank after drilling to prevent oxygen absorption;

[0011] The prepared round tube blanks are heated in a rotary hearth furnace. A plurality of grooves with a depth of 8 mm and arranged radially are evenly opened on the hearth of the rotary hearth furnace. During the process of the tube blank rotating from the feeding end to the discharging end, it successively passes through preheating section 1, preheating section 2, heating section 1, heating section 2, heating section 3, and heating section 4. The heating temperature of the tube blank with the grade of TA1 is controlled at 960°C - 980°C, and the heating temperature of the tube blank with the grade of TC4 is controlled at 1020°C - 1040°C. The tube blank moving with the hearth is heated through the burners arranged at the furnace wall, furnace top, etc.

[0012] The heated tube blank is pierced. An anti-sticking agent is evenly smeared on the surface of the hot rolling guide plate, and glass powder is evenly smeared on the surface of the ground plug. The cooling water control system is closed. The starting rolling temperature is 950°C - 1050°C, the temperature after piercing is 1000°C - 1050°C, the feeding angle of the piercing mill is 10.0°, and the biting speed: the percentage of the main machine speed is 25%.

[0013] The pierced mandrel tube is continuously rolled by an MPM mill. After piercing, borax and nitrogen are blown into the mandrel tube. Before rolling, the mandrel coated with lubricant is preheated to 100 ± 10°C. The rolling parameters of the MPM mill are set according to the density and expansion coefficient of metallic titanium to ensure the geometric dimensions of the finished tube after rolling.

[0014] The pierced mandrel tube is subjected to induction reheating. Ten sets of series-connected induction heating coils are arranged on the transfer roller table between the MPM mill and the stretch reducing mill. The temperature of the pierced mandrel tube is increased by 60°C - 100°C online. The inlet temperature of the pierced mandrel tube entering the stretch reducing mill is controlled at 880°C - 900°C.

[0015] The pierced mandrel tube after induction heating is subjected to stretch reducing to achieve the purpose of reducing the diameter and wall thickness, so that the steel tube reaches the required finished tube size.

[0016] The steel tube after stretch reducing is straightened. Using the residual temperature of the tube body coming out of the stretch reducing mill, it is continuously straightened twice while still warm. For the first time, the seamless tube with the temperature reduced to between 520°C - 550°C is sent into the roller straightening machine for the first rough straightening. For the second time, the seamless tube with the temperature reduced to between 400°C - 430°C is sent into the roller straightening machine for the second fine straightening.

[0017] The steel tube after two straightenings is cooled on a cooling bed, cut to length by a saw, and then subjected to inspection of the surface quality, mechanical properties, geometric dimensions, and non-destructive flaw detection of the tube body, and then packed and stored in the warehouse.

[0018] Furthermore, the chemical composition mass percentage of the tube with the brand TA1 is: C: 0.02-0.05%; P≤0.010; S≤0.003; H≤1.2PPM; O≤0.0012%; N≤0.003%; the remainder is matrix Ti≥99.5%; and undetectable trace impurity elements.

[0019] Furthermore, the chemical composition mass percentage of the tube with the grade TC4 is: C: 0.05-0.08%; Fe: 0.20-0.30%; P≤0.010; S≤0.003; Al: 5.50%-6.75%; V: 3.50%-4.50%; H≤1.5PPM; O≤0.002%; N≤0.005%; the remainder is matrix Ti≥90%.

[0020] Furthermore, the performance of the finished product with the grade TA1 meets the following requirements: yield strength: 237MPa~252MPa; tensile strength: 321MPa~343MPa; yield strength ratio: ≤0.74; elongation: ≥45%; transverse impact value at 0℃: ≥100J / cm 2 .

[0021] Furthermore, the performance of the finished product with the grade TC4 meets the following requirements: 785MPa~843MPa; tensile strength: 912MPa~958MPa; yield strength ratio: ≤0.88; elongation: ≥14%; transverse impact value at 0℃: ≥40-50J / cm 2 .

[0022] Furthermore, the specifications of seamless pipes produced by the two grades are

[0023] Furthermore, the perforated tube is fed into the The unit performs continuous rolling.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are:

[0025] ① Due to the continuous tube rolling process of the MPM unit, the production efficiency of seamless pipes is relatively high;

[0026] ② Due to the use of multiple-length continuous tube rolling process for cutting, the yield rate of seamless tubes is relatively high;

[0027] ③Since the production efficiency and yield rate of seamless pipes are relatively high, the production cost of seamless pipes is relatively low;

[0028] ④Due to a series of technical measures such as precise centering + mushroom piercing + continuous tube rolling by MPM mill + induction re-heating + stretch reducing + two-stage hot straightening + on-line detection throughout the process, the dimensional accuracy of seamless tubes is relatively high, with wall thickness unevenness ≤ 15% and ovality ≤ 0.8%.

[0029] ⑤Due to the continuous tube rolling process by MPM mill, the structure of the tube body is fully compressed and refined. Therefore, the seamless tubes have excellent performance, and the specific performance indicators are as follows:

[0030] TA1: Yield strength: 237 MPa - 252 MPa; Tensile strength: 321 MPa - 343 MPa; Yield ratio: ≤ 0.74; Elongation: ≥ 45%; Transverse impact value at 0 °C: ≥ 100 J / cm²;

[0031] TA1: Yield strength: 785 MPa - 843 MPa; Tensile strength: 912 MPa - 958 MPa; Yield ratio: ≤ 0.88; Elongation: ≥ 14%; Transverse impact value at 0 °C: ≥ 40 - 50 J / cm²;

[0032] ⑥Due to a series of technical measures such as raw material preparation + precise centering + surface coating with antioxidant + pre-treatment with hot tools + on-line monitoring throughout the process, the surface quality of seamless tubes is relatively good, and there are no visually visible cracks, folds, rolled folds, delaminations, and scabs on the inner and outer surfaces. Description of the Drawings

[0033] Figure 1 It is a front view structural schematic diagram of the position selected longitudinally for geometric dimension detection of a seamless tube sample;

[0034] Figure 2 It is a left view structural schematic diagram of the position selected circumferentially at the Y1 position of a seamless tube sample for geometric dimension detection;

[0035] Figure 3 It is a left view structural schematic diagram of the position selected circumferentially at the Y8 position of a seamless tube sample for geometric dimension detection.

[0036] Definition rule for the measurement positions of the seamless tube sample of the present invention longitudinally:

[0037] Observed from the front view direction, the seamless tube sample is divided into seven equal parts longitudinally, avoiding the head and tail. One cross-section can be used as a measurement position. In this way, eight measurement positions can be obtained. For the convenience of description, the eight measurement positions are respectively defined as X1, X2, X3, X4, X5, X6, X7, and X8 from left to right; to further calibrate the measurement positions of the diameter and wall thickness;

[0038] Definition rule for the measurement positions of the diameter of the seamless tube sample of the present invention circumferentially:

[0039] Observed from the left view direction, the seamless tube sample is equally divided into eight parts along the circumferential direction. Two opposite points are used as a measurement position to measure a diameter of the seamless tube sample. In this way, four measurement positions of the diameter can be obtained. For the convenience of description, the four measurement positions are respectively defined as Y1Y1, Y2Y2, Y3Y3, and Y4Y4 in the clockwise direction; in this way, a seamless tube sample has a total of thirty-two measurement positions for measuring the diameter;

[0040] Definition rule for the measurement positions of the wall thickness of the seamless tube sample of the present invention along the circumferential direction:

[0041] Observed from the left view direction, the seamless tube sample is equally divided into eight parts along the circumferential direction. A single point is used as a measurement position to measure a wall thickness of the seamless tube sample. In this way, eight measurement positions of the wall thickness can be obtained. For the convenience of description, the eight measurement positions are respectively defined as Z1, Z2, Z3, Z4, Z5, Z6, Z7, and Z8 in the clockwise direction; in this way, a seamless tube sample has a total of sixty-four measurement positions for measuring the wall thickness. Detailed implementation mode

[0042] The following further elaborates on the present invention patent in conjunction with embodiments.

[0043] The process flow is briefly described as: billet sizing and cutting → billet centering and drilling → billet quality and chemical composition inspection → brushing anti-oxidant on the billet surface → billet protective heating → mushroom piercing → continuous tube rolling by MPM mill → induction re-heating → tension reducing → two times of straightening with temperature → cooling on cooling bed → sizing sawing → inspection of tube body surface quality, mechanical properties and geometric dimensions → non-destructive flaw detection.

[0044] The specific production process flow is as follows:

[0045] Key technology of billet preparation: First, billets of TA1 and TC4 with a diameter of are sized and cut into billets with a length of 2230 mm each. Then, the quality and geometric dimensions of the billets are inspected. Then, a centering hole with a diameter of and a depth of 80 mm is drilled at one end of the billet. The purpose of drilling the centering hole is to more smoothly bite during the piercing process of the piercing mill to prevent the billet from slipping during piercing and causing rolling jam. Then, an anti-oxidant for preventing oxygen absorption is applied to the surface of the billet after drilling with a roller brush to prevent the titanium tube from oxidizing at high temperature. Three coats are evenly brushed until furnace charging. Then, the chemical composition of the billet is analyzed. The chemical composition inspection results are shown in Table 1;

[0046] Table 1 Chemical composition inspection results of billets (weight percentage%)

[0047]

[0048] Key technologies of the rotary hearth furnace: The prepared tube blanks are put into the rotary hearth furnace for heating. To prevent the tube blanks from rolling in the furnace, a plurality of grooves with a depth of 8 mm and arranged radially are evenly opened on the furnace bottom of the rotary hearth furnace; during the process of the tube blanks rotating from the feeding end to the discharging end, they successively pass through preheating section 1, preheating section 2, heating section 1, heating section 2, heating section 3 and heating section 4. The heating temperature of the tube blanks of grade TA1 is controlled at 960°C to 980°C, and the heating temperature of the tube blanks of grade TC4 is controlled at 1020°C to 1040°C. The tube blanks moving with the furnace bottom are heated through the burners arranged on the furnace wall and furnace top, etc. If the heating temperature of the tube blanks is too low, the deformation resistance generated during the piercing process of the tube blanks will be too large, thus easily leading to difficult piercing or rolling jam; on the contrary, if the heating temperature of the tube blanks is too high, the plasticity of the tube blanks will decrease, thus easily generating rolling defects on the inner surface of the tube body; therefore, comprehensively considering, continuously check and control process parameters such as the heating temperature and heating time of each section of the rotary hearth furnace to ensure thorough and uniform heating without overheating, and use a computer to automatically control and record the temperature and heating time of each section of the rotary hearth furnace. The setting of the heating temperature and heating time parameters of each section is shown in Table 2:

[0049] Table 2 Setting of heating temperature and heating time parameters of each section of the rotary hearth furnace

[0050]

[0051] Key technologies of the piercing mill: The heated titanium tube blanks are taken out of the furnace for piercing. Measure the hot tools before use, check and process the roller table before rolling to avoid scratching the tube wall, evenly apply an anti-sticking agent on the surface of the guide plate to prevent the accident of sticking blanks on the guide plate; evenly apply glass powder on the surface of the plug to prevent the accident of sticking blanks on the plug; turn off the cooling water control system to prevent the temperature of the tube blanks from decreasing, and then perform mushroom piercing on the heated tube blanks; reasonably set process parameters such as the roll distance, guide plate distance, plug forward extension, biting speed, feed angle and rolling speed of the mushroom piercing mill. The setting of the process parameters of the mushroom piercing mill is shown in Table 3 and Table 4.

[0052] Table 3 Setting of process parameters of the MPM mill for rolling TA1

[0053]

[0054]

[0055] Table 4 Setting of process parameters of the MPM mill for rolling TC4

[0056]

[0057]

[0058] Key technologies of the MPM continuous rolling mill: The pierced mandrel tube is continuously rolled by the MPM mill. Before rolling, the mandrel is preheated to 100 °C, and then colloidal graphite is sprayed on the surface of the mandrel to ensure uniform spraying, coating thickness and reduce scratching; the automatic borax spraying system is turned off, and opposed nozzles are used to spray an antioxidant on the inner surface of the tube body from the head and tail of the tube body respectively to prevent oxidation of the inner surface of the mandrel tube; then the pierced mandrel tube is sent into the mill for continuous rolling; the process parameters for rolling TA1 and TC4 of the MPM mill are set according to the density and expansion coefficient of titanium metal to ensure the geometric dimensions of the finished tube after rolling.

[0059] Key technologies of induction reheating: The rough tube after continuous rolling is subjected to induction reheating. Since the heating temperature of the ring furnace is low, there is also a certain temperature loss when the rough tube coming out of the MPM mill runs on the roller table. In order to meet the temperature requirements of the stretch reducing mill for the rough tube, five sets of series-connected induction heating coils are arranged on the transport roller table between the MPM mill and the stretch reducing mill, so that the temperature of the rough tube can be increased by 60 °C - 100 °C online during the running process of the rough tube, and the inlet temperature of the rough tube entering the stretch reducing mill is controlled between 880 °C - 900 °C.

[0060] Key technologies of the stretch reducing mill: The rough tube after induction heating is sent into the 24-stand stretch reducing mill for stretch reducing, and finally seamless tubes with a specification of are produced. During rolling, hot sampling is carried out at least once per batch to check the geometric dimensions and ensure the precise forming of the seamless tubes.

[0061] In the example of grade TA1, three small batches of seamless tubes were produced, and the specifications of the produced seamless tubes were all The outer diameter and wall thickness of the tube bodies of these three small batches of seamless tubes were comprehensively detected, and the specific detection results are shown in Table 5.

[0062] Table 5 Comprehensive detection results of the outer diameter and wall thickness of the tube body of seamless tubes of grade TA1 (mm)

[0063]

[0064]

[0065] In the example of grade TC4, three small batches of seamless tubes were produced, and the specifications of the produced seamless tubes were all The outer diameter and wall thickness of the tube bodies of these three small batches of seamless tubes were comprehensively detected, and the specific detection results are shown in Table 6.

[0066] Table 6 All-round test results of outer diameter and wall thickness of seamless pipe body with grade TC4 (mm)

[0067]

[0068] Key technology of the straightening unit: straighten the steel pipe after tension reduction twice, send the seamless pipe with the temperature reduced to 520℃~550℃ into the roller straightening machine for the first warm straightening, and then send the seamless pipe with the temperature reduced to 400℃~430℃ into the roller straightening machine for the second warm straightening;

[0069] Then the seamless pipe after two consecutive temperature straightenings is sent to a step-type cooling bed for natural cooling, and then the seamless pipe after natural cooling is sent to a gang saw for cut to length, and finally the geometric dimensions and surface quality of the pipe body after cut to length are checked one by one, and then the qualified pipe body is subjected to non-destructive testing one by one. After the above-mentioned process production and inspection process, the qualified ones become the finished products of the pure titanium and titanium alloy seamless pipes of the present invention, and the samples are prepared from them for mechanical property inspection.

[0070] The embodiment with the brand TA1 produced three small batches of seamless pipes, and the embodiment with the brand TC4 produced three small batches of seamless pipes. The specifications of the seamless pipes produced by the two brands are Mechanical property specimens were taken from the six small batches of seamless pipes and tested respectively. The specific test results are shown in Table 7.

[0071] Table 7 Mechanical properties test results of seamless pipes (the following values ​​are all average values)

[0072]

[0073] In summary, the pure titanium and titanium alloy seamless pipe rolling technology based on the MPM unit provided by the present invention can produce pure titanium and titanium alloy seamless pipes with low production cost, high production efficiency, high yield rate, high dimensional accuracy, high strength and toughness matching and good surface quality.

[0074] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A rolling method for seamless tubes of pure titanium and titanium alloys based on an MPM mill, including sizing and cutting of tube blanks → centering and drilling of tube blanks → inspection of the quality and chemical composition of tube blanks → brushing of antioxidant on the surface of tube blanks → protective heating of tube blanks → mushroom piercing → continuous rolling of tube blanks by an MPM mill → induction re-heating → tension reducing → two times of straightening while still warm → cooling on a cooling bed → sizing and sawing → inspection of the surface quality, mechanical properties and geometric dimensions of the tube body → non-destructive flaw detection, characterized in that: Tube blank preparation, a centering hole is drilled at one end of the tube blank, and the diameter of the centering hole is with a depth of 80 mm; the tube blank is chamfered at an oblique angle of 40° - 45° perpendicular to the axial direction of the tube blank; at the same time, a water-based boron nitride coating antioxidant for preventing oxygen absorption is evenly brushed on the surface of the tube blank after drilling using a roller brush; The prepared round tube blanks are heated in a rotary hearth furnace. A plurality of grooves with a depth of 8 mm and arranged radially are evenly opened on the hearth of the rotary hearth furnace. During the process of the tube blank rotating from the feeding end to the discharging end, it successively passes through preheating section 1, preheating section 2, heating section 1, heating section 2, heating section 3 and heating section 4. The heating temperature of the tube blank of grade TA1 is controlled at 960 °C - 980 °C, and the heating temperature of the tube blank of grade TC4 is controlled at 1020 °C - 1040 °C. The tube blank moving with the hearth is heated by burners arranged at the furnace wall, furnace top, etc. The heated tube blanks are pierced. Anti-sticking agent is evenly smeared on the surface of the hot rolling guide plate, and glass powder is evenly smeared on the surface of the well-ground plug. The cooling water control system is turned off. The starting rolling temperature is 950 °C - 1050 °C, the temperature after piercing is 1000 °C - 1050 °C, the feeding angle of the piercing mill is 10.0 °, and the biting speed: the percentage of the main machine speed is 25%. The pierced mandrel tubes are continuously rolled by an MPM mill. After piercing, borax and nitrogen are blown into the mandrel tubes. Before rolling, the mandrel coated with lubricant is preheated to 100 ± 10 °C. The rolling parameters of the MPM mill are set according to the density and expansion coefficient of metallic titanium to ensure the geometric dimensions of the finished tube after rolling. The rough tubes coming out of the MPM mill are subjected to induction re-heating. Ten sets of series-connected induction heating coils are arranged on the transfer roller table between the MPM mill and the tension reducing mill. The temperature of the rough tubes is increased by 60 °C - 100 °C online. The inlet temperature of the rough tubes entering the tension reducing mill is controlled at 880 °C - 900 °C. The induction-heated rough tubes are subjected to tension reducing to achieve the purpose of reducing diameter and wall thickness, so that the steel tubes reach the required finished tube dimensions. The tension-reduced steel tubes are straightened. The remaining temperature of the tube body coming out of the tension reducing mill is used for two times of straightening while still warm. For the first time, the seamless tubes with the temperature reduced to between 520 °C and 550 °C are sent into a roller straightening machine for the first rough straightening. For the second time, the seamless tubes with the temperature reduced to between 400 °C and 430 °C are sent into a roller straightening machine for the second fine straightening. The steel tubes after two times of straightening are cooled on a cooling bed, sized and sawed, and then inspected for the surface quality, mechanical properties, geometric dimensions and non-destructive flaw detection of the tube body, and then packed and stored in the warehouse.

2. The method for rolling seamless pure titanium and titanium alloy tubes based on an MPM mill set according to claim 1, characterized in that, The chemical composition mass percentage of the tube blank of grade TA1 is: C: 0.02 - 0.05%; P ≤ 0.010; S ≤ 0.003; H ≤ 1.2 PPM; O ≤ 0.0012%; N ≤ 0.003%; the balance is matrix Ti ≥ 99.5%; and trace impurity elements that cannot be detected.

3. The method for rolling seamless tubes of pure titanium and titanium alloys based on an MPM mill according to claim 1, wherein The chemical composition of the tube blank with the grade of TC4 is as follows in mass percentage: C: 0.05 - 0.08%; Fe: 0.20 - 0.30%; P ≤ 0.010; S ≤ 0.003; Al: 5.50% - 6.75%; V: 3.50% - 4.50%; H ≤ 1.5 PPM; O ≤ 0.002%; N ≤ 0.005%; the balance is the matrix Ti ≥ 90%.

4. The method for rolling seamless pure titanium and titanium alloy tubes based on an MPM mill according to claim 2, characterized in that, The finished product properties of the grade of TA1 meet the following requirements: yield strength: 237 MPa - 252 MPa; tensile strength: 321 MPa - 343 MPa; yield ratio: ≤ 0.74; Elongation: ≥45%; Transverse impact value at 0°C: ≥100 J / cm 2 .

5. The method for rolling seamless pure titanium and titanium alloy tubes based on an MPM mill according to claim 3, characterized in that, The finished product properties of the grade TC4 meet the following requirements: yield strength: 785 MPa to 843 MPa; tensile strength: 912 MPa to 958 MPa; yield ratio: ≤ 0.88; elongation: ≥ 14%; transverse impact value at 0 °C: ≥ 40 - 50 J / cm 2 .

6. The method for rolling seamless pure titanium and titanium alloy tubes based on an MPM mill according to claim 1, characterized in that, The seamless pipe specifications produced by the two grades are both 7. The method for rolling seamless tubes of pure titanium and titanium alloys based on the MPM mill unit according to claim 1, characterized in that The perforated capillary tubes are fed in by a chain conveyor The unit performs continuous rolling.

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