Continuous hot-drawing forming method for nickel-titanium alloy pipe

[0033] Example 1

[0034] Such as figure 1 with figure 2 As shown, the continuous hot drawing forming device used in this embodiment includes a quartz tube 1, a graphite tube 3 arranged in the quartz tube 1, and an induction coil 2 wound outside the quartz tube 1, and used for supplying power to the induction coil 2. The high-frequency induction heating power supply 8; the quartz tube 1 includes an inlet pipe 1-1, an equal diameter section 1-3 connected to the inlet pipe 1-1 through a diverging section 1-2, and a tapered section 1-4 The outlet pipe 1-5 connected with the equal diameter section 1-3; the left end of the graphite pipe 3 is attached to the inner wall of the right end of the inlet pipe 1-1, and the right end of the graphite pipe 3 is attached to the inner wall of the left end of the outlet pipe 1-5 The graphite tube 3 and the divergent section 1-2, the equal diameter section 1-3 and the tapered section 1-4 of the quartz tube 1 form a cavity 4; the graphite tube 3 is provided with one end and a graphite tube The other end of the 3-phase communication passes through the pipe wall of the equal-diameter section 1-3 and is used to pass the protective gas into the graphite tube 3 through the first gas pipe 5; the equal-diameter section 1-3 of the quartz tube 1 is provided with The second gas pipe 6 through which the protective gas is introduced into the cavity 4; the equal diameter section 1-3 of the quartz tube 1 is provided with a temperature measuring tube 7 for measuring the temperature of the outer wall of the graphite tube 3; the outlet of the quartz tube 1 A drawing machine 12 is provided at the tube 1-5.

[0035] Such as figure 1 with figure 2 As shown, in this embodiment, the induction coil 2 is a hollow copper tube, and the nozzles at both ends of the induction coil 2 are respectively connected with the water inlet and the water outlet of the cooling circulating water machine 9 for cooling the induction coil 2; The winding position of the induction coil 2 corresponds to the position of the graphite tube 3; the frequency of the high-frequency induction heating power supply 8 is 50KHz-100KHz; the wall thickness of the quartz tube 1 is 3mm-5mm (preferably 3mm, 4mm, 5mm), the wall thickness of the graphite tube 3 is 4mm-8mm (preferably 4mm, 5mm, 6mm, 7mm, 8mm); the number of the temperature measuring tube 7 is two, one of which is located at the end of the equal diameter section 1-3, The other is located in the middle of the equal diameter section 1-3, which is convenient for monitoring the axial temperature uniformity of the graphite tube 3; the left and right ends of the graphite tube 3 are provided with two oblique holes 10, One end is located on the end surface of the graphite tube 3, and the other end is located on the wall of the graphite tube 3 and communicates with the cavity 4, which is convenient for quickly purging the air in the quartz tube 1; the square of the inner diameter of the first gas pipe 5 is larger than that of the graphite tube 3 The sum of the squares of the inner diameters of the left and right ends, the sum of the squares of the inner diameters of the first gas pipe 5 and the second gas pipe 6 is greater than the square sum of the inner diameters of the inlet of the inlet pipe 1-1 and the outlet of the outlet pipe 1-5 Therefore, it is structurally ensured that the amount of gas introduced from the first gas pipe 5 and the second gas pipe 6 is greater than the amount of gas discharged from the inlet pipe 1-1 and the outlet pipe 1-5, thereby ensuring the quartz tube 1 and the graphite tube 3 The inside is completely in a protective atmosphere; the inlet pipe 1-1 and the outlet pipe 1-5 are both concentric reducing pipes, and the inner diameter of the inlet of the inlet pipe 1-1 is smaller than the inlet pipe 1-1 and the diverging section 1- 2 The inner diameter of the nozzle at the junction, the inner diameter of the outlet of the outlet pipe 1-5 is smaller than the inner diameter of the nozzle at the junction of the outlet pipe 1-5 and the tapered section 1-4.

[0036] Such as figure 1 with figure 2 As shown, in this embodiment, the continuous hot drawing forming device further includes a bracket 13 for supporting the quartz tube 1 and a discharging rack 14 arranged at the inlet tube 1-1 of the quartz tube 1.

[0037] The continuous hot drawing forming method of this embodiment is:

[0038] Step 1. Insert a Φ7.5mm 316L stainless steel mandrel into a Ni-44Ti alloy tube with an outer diameter of 10.5mm and an inner diameter of 8.5mm to obtain the assembly 11; in the assembly, the head of the mandrel is exposed from the tube by 200mm, and the core The tail of the rod exposed the tube blank 400mm; the roughness of the inner surface of the Ni-44Ti alloy tube blank Ra<3.2, the roughness of the outer surface of the core rod Ra<3.2; the surface of the core rod is electroplated with a copper lubricating coating with a thickness of 5μm ;

[0039] Step 2: Insert the core rod head of the assembly 11 from the inlet pipe 1-1, pass through the graphite pipe 3 and then pass through the outlet pipe 1-5, and then pass through the drawing die of the drawing machine 12 and clamp it On the clamp of the drawing machine 12, the core rod tail of the assembly 11 is supported on the discharge rack 14; the protective gas argon is introduced into the quartz tube 1 and the graphite tube 3, and the quartz tube 1 and the graphite tube 3 After the air is exhausted, the high-frequency induction heating power supply 8 is turned on, and the graphite tube 3 and the assembly 11 are heated through the induction coil 2. When the temperature of the outer wall of the graphite tube 3 reaches 740°C, the drawing machine 12 is turned on and clamped with refractory tongs The combination body 11, the drawing trolley of the drawing machine 12 drives the combination body 11 to run at a constant speed and sends the combination body 11 into the drawing die for drawing; the running speed of the combination body 11 is to control the nickel-titanium alloy tube blank from the graphite tube 3 The time for one end to reach the other end of the graphite tube 3 is 20s; the specification of the drawing die is Φ10mm;

[0040] Step 3. Repeat Step 2 19 times for the assembly after drawing in Step 2. The drawing die specifications are: Φ9.6mm, Φ9.3mm, Φ9.0mm, Φ8.6mm, Φ8.2mm, Φ7.8mm, Φ7.4mm, Φ7.0mm, Φ6.6mm, Φ6.0mm, Φ5.8mm, Φ5.6mm, Φ5.4mm, Φ5.2mm, Φ5.0mm, Φ4.8mm, Φ4.7mm, Φ4.6mm, Φ4. 5mm;

[0041] Step 4. Heat the assembly after repeated drawing in step 3 to 780℃, then plastically stretch the core rod in the assembly to reduce the diameter of the core rod, and finally take out the reduced core rod to obtain the outer diameter Ni-44Ti alloy pipe with 4.5mm, wall thickness of 0.8mm, dimensional tolerance of ±0.03mm, outer surface roughness Ra<3.0, and inner surface roughness Ra<3.4.

[0042] Example 2

[0043] The continuous hot drawing forming device used in this embodiment is the same as that of the first embodiment.

[0044] The continuous hot drawing forming method of this embodiment is:

[0045] Step 1. Insert a 316L stainless steel mandrel with Φ6.5mm into a Ni-44Ti alloy tube with an outer diameter of 10mm and an inner diameter of 7mm to obtain assembly 11; the head of the mandrel in the assembly exposes 300mm of the tube, and the tail of the mandrel The exposed tube blank is 500mm; the roughness of the inner surface of the Ni-44Ti alloy tube blank is Ra<3.2, and the roughness of the outer surface of the core rod is Ra<3.2; the surface of the core rod is electroplated with a copper lubricating coating with a thickness of 10 μm;

[0046] Step 2: Insert the core rod head of the assembly 11 from the inlet pipe 1-1, pass through the graphite pipe 3 and then pass through the outlet pipe 1-5, and then pass through the drawing die of the drawing machine 12 and clamp it On the clamp of the drawing machine 12, the core rod tail of the assembly 11 is supported on the discharge rack 14; the protective gas argon is introduced into the quartz tube 1 and the graphite tube 3, and the quartz tube 1 and the graphite tube 3 After the air is exhausted, the high-frequency induction heating power supply 8 is turned on, and the graphite tube 3 and the assembly 11 are heated by the induction coil 2. When the temperature of the outer wall of the graphite tube 3 reaches 720°C, the drawing machine 12 is turned on and clamped with refractory tongs The combination body 11, the drawing trolley of the drawing machine 12 drives the combination body 11 to run at a constant speed and sends the combination body 11 into the drawing die for drawing; the running speed of the combination body 11 is to control the nickel-titanium alloy tube blank from the graphite tube 3 The time for one end to reach the other end of the graphite tube 3 is 30s; the specification of the drawing die is Φ9.8mm;

[0047] Step 3. Repeat step 2 25 times for the assembly after drawing in step 2. The drawing die specifications are: Φ9.6mm, Φ9.3mm, Φ9.0mm, Φ8.6mm, Φ8.2mm, Φ7.8mm, Φ7.4mm, Φ7.0mm, Φ6.6mm, Φ6.0mm, Φ5.6mm, Φ5.2mm, Φ5.0mm, Φ4.8mm, Φ4.7mm, Φ4.6mm, Φ4.5mm, Φ4.4mm, Φ4. 3mm, Φ4.2mm, Φ4.1mm, Φ4.0mm, Φ3.9mm, Φ3.8mm, Φ3.7mm;

[0048] Step 4. Heat the assembly after repeated drawing in step 3 to 800°C, then plastically stretch the core rod in the assembly to reduce the diameter of the core rod, and finally take out the reduced core rod to obtain the outer diameter It is a Ni-44Ti alloy pipe with a wall thickness of 0.5mm, a dimensional tolerance of ±0.02mm, an outer surface roughness Ra<3.0, and an inner surface roughness Ra<3.4.

[0049] Example 3

[0050] The continuous hot drawing forming device used in this embodiment is the same as that of the first embodiment.

[0051] The continuous hot drawing forming method of this embodiment is:

[0052] Step 1. Insert a 316L stainless steel mandrel of Φ6.5mm into a Ni-50.8Ti alloy tube with an outer diameter of 10mm and an inner diameter of 7mm to obtain a combination 11; the head of the mandrel in the combination is exposed to the tube by 100mm, and the mandrel The tail part of the exposed tube blank is 200mm; the inner surface roughness of the Ni-50.8Ti alloy tube blank is Ra<3.2, and the outer surface roughness of the core rod is Ra<3.2; the surface of the core rod is electroplated with a copper lubricating coating with a thickness of 2μm ;

[0053] Step 2: Insert the core rod head of the assembly 11 from the inlet pipe 1-1, pass through the graphite pipe 3 and then pass through the outlet pipe 1-5, and then pass through the drawing die of the drawing machine 12 and clamp it On the clamp of the drawing machine 12, the core rod tail of the assembly 11 is supported on the discharge rack 14; the protective gas argon is introduced into the quartz tube 1 and the graphite tube 3, and the quartz tube 1 and the graphite tube 3 After the air is exhausted, the high-frequency induction heating power supply 8 is turned on, and the graphite tube 3 and the assembly 11 are heated through the induction coil 2. When the temperature of the outer wall of the graphite tube 3 reaches 760℃, the drawing machine 12 is turned on and clamped with refractory tongs The combination body 11, the drawing trolley of the drawing machine 12 drives the combination body 11 to run at a constant speed and sends the combination body 11 into the drawing die for drawing; the running speed of the combination body 11 is to control the nickel-titanium alloy tube blank from the graphite tube 3 The time for one end to reach the other end of the graphite tube 3 is 30s; the specification of the drawing die is Φ9.8mm;

[0054] Step 3. Repeat step 2 17 times for the assembly after drawing in step 2. The drawing die specifications are: Φ9.6mm, Φ9.3mm, Φ9.0mm, Φ8.6mm, Φ8.2mm, Φ7.8mm, Φ7.4mm, Φ7.0mm, Φ6.6mm, Φ6.0mm, Φ5.6mm, Φ5.2mm, Φ5.0mm, Φ4.8mm, Φ4.7mm, Φ4.6mm, Φ4.5mm;

[0055] Step 4. Heat the assembly after repeated drawing in step 3 to 800°C, then plastically stretch the core rod in the assembly to reduce the diameter of the core rod, and finally take out the reduced core rod to obtain the outer diameter Ni-50.8Ti alloy pipe with 4.5mm, wall thickness of 0.8mm, dimensional tolerance of ±0.03mm, outer surface roughness Ra<3.0, and inner surface roughness Ra<3.4.