A welding fixture and method for TiNi shape memory alloy wire and stainless steel wire

Abstract

The application relates to a welding clamp and method for TiNi shape memory alloy wire and stainless steel wire, belonging to the technical field of dissimilar material connection. In order to solve the problem of poor mechanical performance of the welding joint of the TiNi shape memory alloy wire and the stainless steel wire, the clamp comprises a chuck and a sliding seat, two chucks are coaxially arranged on the base in a facing rotation mode, a lifting platform is arranged between the two chucks, a front clamping plate and a rear clamping plate are slidably arranged on the lifting platform, a connecting piece is fixed during welding, and the shape memory alloy wire and the stainless steel wire are fixed through the chucks on the same side. The connecting piece is welded and fused by laser welding, so as to be welded with the shape memory alloy wire and the stainless steel wire. The application solves the problem of limited welding area of the shape memory alloy wire and the stainless steel wire, greatly improves the bearable tension, and the tensile strength of the welding joint is much higher than that of the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of dissimilar material connection, and particularly relates to a welding clamp and method for TiNi shape memory alloy wire and stainless steel wire. BACKGROUND

[0002] In recent years, due to the continuous development of medical technology, higher and higher requirements are put forward for micro medical devices. Due to the consideration of product cost and performance, the performance of a single metal wire material cannot meet the actual use demand. For example, the central venous guide wire needs to use stainless steel wire to provide support, and needs to use the super-elasticity of TiNi shape memory alloy wire to prevent it from being folded during use. In addition, the product reduces the use of TiNi shape memory alloy wire, greatly reducing the production cost.

[0003] At present, the welding of TiNi shape memory alloy wire and stainless steel wire generally uses the method of adding alloy elements (intermediate layer or alloy powder) between the two and changing the position of the laser heat source to improve the mechanical properties of the welded joint. However, due to the differences in physical and chemical properties between dissimilar materials, it is still difficult to obtain a joint with high strength. For example, the patent with publication number CN102152017A discloses a connection method for dissimilar materials of TiNi shape memory alloy wire and austenitic stainless steel wire, which provides a technical solution of adding a pure copper intermediate layer between the TiNi shape memory alloy and the austenitic stainless steel. The addition of the copper intermediate layer reduces the generation of iron-titanium brittle intermetallic compounds, but at the same time, copper-titanium intermetallic compounds are also generated, making it difficult for the joint to achieve high strength.

[0004] When welding dissimilar metal wires, the differences in physical and chemical properties between different materials are the main reason for the sharp decline in the mechanical properties of the joint. The difference in melting point will cause the burning loss of alloy elements during welding, and the difference in thermal conductivity and linear expansion coefficient will cause large residual stress at the interface. The small solid solubility between dissimilar metals and the generation of brittle intermetallic compounds will lead to a sharp decline in the performance of the joint. In addition, due to the limitations of metal wires in welding (limited maximum welding area), these are the reasons for the small joint tension. SUMMARY

[0005] The purpose of the present application is to provide a welding clamp and method for TiNi shape memory alloy wire and stainless steel wire to solve the problem of poor mechanical properties of the welded joint of TiNi shape memory alloy wire and stainless steel wire. The technical solution adopted by the present application is as follows:

[0006] A welding clamp for TiNi shape memory alloy wire and stainless steel wire, comprising a base, a chuck, a sliding seat, a front clamp plate and a rear clamp plate.

[0007] Two supports are arranged on the base in left and right directions, a pipe shaft is rotatably arranged on each support, the two pipe shafts are coaxial, the inner end of the pipe shaft protrudes from the inner side of the corresponding support, and the inner end of the pipe shaft is provided with a chuck;

[0008] The base is provided with a lifting platform, the lifting platform is located between the two supports, the top end of the lifting platform is provided with a sliding seat, the front clamping plate and the rear clamping plate are respectively in front and rear sliding cooperation with the sliding seat, the bottom of the front clamping plate and the rear clamping plate are respectively provided with a plurality of strip blocks extending in opposite directions, the strip blocks of the front clamping plate and the strip blocks of the rear clamping plate are arranged in a staggered manner, and the upper ends can be combined into a working plane, a drive screw is rotatably arranged on the sliding seat, the screw threads of the front part and the rear part of the drive screw are opposite in rotation direction, a driving block is arranged on the front clamping plate and the rear clamping plate, a screw hole is arranged on the driving block, the two driving blocks are respectively in corresponding screw thread cooperation with the front part and the rear part of the drive screw, and a quick clamp is arranged on the front clamping plate and the rear clamping plate.

[0009] Further, two axially front and rear extending light rods are arranged on the sliding seat, two sliding blocks are arranged on the front clamping plate and the rear clamping plate, the two sliding blocks of the front clamping plate are respectively in one-to-one corresponding sleeve sliding cooperation with the two light rods, and the two sliding blocks of the rear clamping plate are respectively in one-to-one corresponding sleeve sliding cooperation with the two light rods.

[0010] Further, the chuck is a double-claw chuck.

[0011] Further, the pipe shaft is connected with the support through a bearing.

[0012] Further, the outer periphery of the pipe shaft is provided with two axisymmetric top pockets, a positioning sleeve is sleeved on the pipe shaft, the positioning sleeve is connected with the support, a spring pin is arranged on the positioning sleeve, and the spring pin is in pin cooperation with any top pocket.

[0013] The application also provides a welding method for TiNi shape memory alloy wires and stainless steel wires, which is realized by relying on the above-mentioned welding clamp for TiNi shape memory alloy wires and stainless steel wires and comprises the following steps.

[0014] Step one: separately place the TiNi shape memory alloy wire, the stainless steel wire and the connecting piece into a polishing liquid to remove the oxide film;

[0015] Step two: separately place the TiNi shape memory alloy wire, the stainless steel wire and the connecting piece into an acetone solution to remove surface oil stains;

[0016] Step three: adjust the height of the lifting platform, and fix the TiNi shape memory alloy wire, the stainless steel wire and the connecting piece on the welding clamp respectively;

[0017] Step four: adopt a laser welding mode to heat melt the connecting piece, so that the connecting piece is connected with the TiNi shape memory alloy wire and the stainless steel wire respectively;

[0018] The connecting piece is a plurality of stacked metal sheets or metal tubes, when the connecting piece is a metal tube, the front and rear clamping plates are clamped on the outer periphery of the connecting piece, and the TiNi shape memory alloy wires and the stainless steel wires are respectively and one-to-one correspondingly inserted into two tube shafts and respectively inserted into two ends of the connecting piece, and the TiNi shape memory alloy wires and the stainless steel wires are respectively fixed by corresponding chucks;

[0019] When the connecting piece is a plurality of stacked metal sheets, the TiNi shape memory alloy wires and the stainless steel wires are respectively and one-to-one correspondingly inserted into two tube shafts and are placed close to each other on the working plane, and the TiNi shape memory alloy wires and the stainless steel wires are respectively fixed by corresponding chucks, and the connecting piece is placed on the TiNi shape memory alloy wires and the stainless steel wires, and the front and rear ends of the connecting piece are respectively pressed by corresponding quick clamps on the same side.

[0020] Step five: loosen the connecting piece, rotate the two chucks in the same direction by 180 degrees, and repeat step four.

[0021] Further, the process parameters of the laser welding are as follows: pulse width 0.1-50 ms, frequency 0.1-1 Hz, protective gas flow 5-20 L / min, welding current 10-800 A, and the welding current on one side of the stainless steel wire is 1-100 A higher than that on one side of the TiNi shape memory alloy wire, and the welding current on any one side after rotation by 180 degrees is 1-100 A lower than the welding current on the side before rotation.

[0022] Further, the material of the connecting piece is copper, nickel or tantalum.

[0023] Further, when the connecting piece is a metal tube, the wall thickness of the connecting piece is 0.1-16 mm; when the connecting piece is a plurality of stacked metal sheets, the total thickness of the connecting piece is 0.1-16 mm, and the thickness of a single layer is 0.1-1 mm.

[0024] Further, the distance between the TiNi shape memory alloy wires and the stainless steel wires is 0.1-1 mm.

[0025] Compared with the prior art, the beneficial effects of the present application are as follows:

[0026] 1. The present application proposes a welding method for TiNi shape memory alloy wires and stainless steel wires, by changing the welding structure, a connecting tube is added at the butt joint of the TiNi shape memory alloy wires and the stainless steel wires, which solves the problem of limited welding area when welding metal wires, greatly improves the bearing tension, and as the lap length of the connecting tube on the dissimilar metal wires increases, the bearing tension of the joint approximately linearly increases.

[0027] 2. Compared with the welding method of the prior TiNi shape memory alloy wire and stainless steel wire, the present application completely avoids the generation of the mixed molten pool of the TiNi shape memory alloy and stainless steel with poor weldability, and forms the molten pool of the material (copper, nickel, tantalum, etc.) with better weldability, which is mixed with the molten pool of the TiNi shape memory alloy and the third material and the stainless steel, and weakens the influence of the poor weldability of the dissimilar metal wire on the load bearing of the joint. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the axonometric view of the present application;

[0029] Figure 2 is the front view of the present application;

[0030] Figure 3 is the top view of the present application;

[0031] Figure 4 is the structural schematic view of the slide;

[0032] Figure 5 is the structural schematic view of the front clamp plate;

[0033] Figure 6 is the structural schematic view of the rear clamp plate;

[0034] Figure 7 is the metal wire tensile strength column chart obtained by the prior welding technology and the test 1 and test 2 of the present application;

[0035] Figure 8 is the metal wire tensile strength curve chart.

[0036] 1 - base, 11 - support, 2 - pipe shaft, 21 - spring pin, 22 - positioning sleeve, 23 - chuck, 31 - TiNi shape memory alloy wire, 32 - stainless steel wire, 33 - connecting piece, 4 - lifting platform, 5 - slide, 51 - light rod, 52 - drive screw, 6 - front clamp plate, 61 - long block, 62 - drive block, 63 - sliding block, 7 - rear clamp plate, 8 - quick clamp. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application will be described below through the specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0038] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as bolted connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can be found to achieve this function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a bolted connection can be chosen for detachable connections.

[0039] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0040] Example 1: As Figures 1-6 As shown, a welding fixture for TiNi shape memory alloy wire and stainless steel wire includes a base 1, a chuck 23, a slide 9, a front clamping plate 6 and a rear clamping plate 7.

[0041] Two supports 11 are set on the base 1 from left to right. A tube shaft 2 is rotatably mounted on the support 11. The two tube shafts 2 are coaxial. The inner end of the tube shaft 2 protrudes from the inner side of the corresponding support 11. A chuck 23 is provided at the inner end of the tube shaft 2.

[0042] A lifting platform 4 is provided on the base 1, which is located between two supports 11. A slide 9 is provided at the top of the lifting platform 4. A front clamping plate 6 and a rear clamping plate 7 are arranged front and rear, respectively, and slide in cooperation with the slide 9. Several opposing long strips 61 are provided at the bottom of the front clamping plate 6 and the rear clamping plate 7. The long strips 61 of the front clamping plate 6 and the long strips 61 of the rear clamping plate 7 are arranged alternately, and their upper ends can be assembled into a working plane. A drive screw 92 is rotatably provided on the slide 9. The drive screw 92 is arranged axially front and rear, and the threads of the front and rear parts of the drive screw 92 are opposite. A drive block 62 is provided on both the front clamping plate 6 and the rear clamping plate 7. The drive block 62 is provided with a screw hole, and the two drive blocks 62 are respectively threaded in cooperation with the front and rear parts of the drive screw 92. A quick clamp 8 is provided on both the front clamping plate 6 and the rear clamping plate 7.

[0043] The slide block 9 is provided with two axially extending light rods 91. The front clamping plate 6 and the rear clamping plate 7 are each provided with two sliders 63. The two sliders 63 of the front clamping plate 6 are respectively sleeved and slidably engaged with the two light rods 91. The two sliders 63 of the rear clamping plate 7 are respectively sleeved and slidably engaged with the two light rods 91.

[0044] Chuck 23 is a double-jaw chuck 23.

[0045] The tube shaft 2 is connected to the bracket 11 via a bearing.

[0046] The outer periphery of the pipe shaft 2 is provided with two axisymmetric top pockets, a positioning sleeve 22 is sleeved on the pipe shaft 2, the positioning sleeve 22 is connected with the support 11, the positioning sleeve 22 is provided with a spring pin 21, and the spring pin 21 is inserted into any top pocket.

[0047] Embodiment two: a welding method of TiNi shape memory alloy wire and stainless steel wire, relying on the welding clamp of TiNi shape memory alloy wire and stainless steel wire in embodiment one, comprising the following steps:

[0048] Step one: separately put the TiNi shape memory alloy wire 31, the stainless steel wire 32 and the connecting piece 33 into the polishing liquid to remove the oxidation film;

[0049] Step two: separately put the TiNi shape memory alloy wire 31, the stainless steel wire 32 and the connecting piece 33 into the acetone solution to remove the surface oil stains;

[0050] Step three: adjust the height of the lifting platform 4, and fix the TiNi shape memory alloy wire 31, the stainless steel wire 32 and the connecting piece 33 on the welding clamp respectively;

[0051] Step four: heat melt the connecting piece 33 by laser welding, so that it is connected with the TiNi shape memory alloy wire 31 and the stainless steel wire 32 respectively;

[0052] The connecting piece 33 is a plurality of stacked metal foils or metal pipes, when the connecting piece 33 is a metal pipe, the front clamp plate 6 and the rear clamp plate 7 are clamped on the outer periphery of the connecting piece 33, the TiNi shape memory alloy wire 31 and the stainless steel wire 32 are respectively and one by one inserted into the two pipe shafts 2, and respectively inserted into the two ends of the connecting piece 33, and the TiNi shape memory alloy wire 31 and the stainless steel wire 32 are respectively clamped and fixed by the corresponding chucks 23;

[0053] When the connecting piece 33 is a plurality of stacked metal foils, the TiNi shape memory alloy wire 31 and the stainless steel wire 32 are respectively and one by one inserted into the two pipe shafts 2, and are placed close to each other on the working plane, the TiNi shape memory alloy wire 31 and the stainless steel wire 32 are respectively clamped and fixed by the corresponding chucks 23, and the connecting piece 33 is placed on the TiNi shape memory alloy wire 31 and the stainless steel wire 32, and the front and rear ends of the connecting piece 33 are respectively pressed by the corresponding quick clamps 8 on the same side;

[0054] Step five: loosen the connecting piece 33, rotate the two chucks 23 in the same direction by 180°, and repeat step four.

[0055] The process parameters of the laser welding are as follows: pulse width 0.1-50 ms, frequency 0.1-1 Hz, protective gas flow 5-20 L / min, welding current 10-800 A, and the welding current of one side of the stainless steel wire 32 is 1-100 A higher than that of the TiNi shape memory alloy wire 31, the welding current of any one side after rotating 180° is 1-100 A lower than that of the side before rotating.

[0056] The material of the connecting piece 33 is copper, nickel or tantalum.

[0057] When the connecting piece 33 is a metal pipe, the wall thickness of the connecting piece 33 is 0.1-16 mm; when the connecting piece 33 is a plurality of stacked metal sheets, the total thickness of the connecting piece 33 is 0.1-16 mm, and the thickness of a single layer is 0.1-1 mm.

[0058] The distance between the TiNi shape memory alloy wire 31 and the stainless steel wire 32 is 0.1-1 mm.

[0059] The present application provides a welding method for TiNi shape memory alloy wire and stainless steel wire, by changing the welding structure, a connecting pipe is added at the butt joint of the TiNi shape memory alloy wire and the stainless steel wire, solving the problem of limited welding area when welding metal wires, greatly improving the bearing tension, and as the lap length of the connecting pipe on the dissimilar metal wires increases, the bearing tension of the joint approximately linearly increases.

[0060] Compared with the existing welding method of TiNi shape memory alloy wire and stainless steel wire, the present application completely avoids the formation of a mixed molten pool of TiNi shape memory alloy and stainless steel which has poor weldability, and forms a material (copper, nickel, tantalum, etc.) with better weldability, which forms a eutectic pool with the TiNi shape memory alloy and the third material and the stainless steel, weakening the influence of poor weldability on the bearing force of the joint when welding dissimilar metal wires.

[0061] Test verification shows that the connection strength at the welded joint by the welding method of the present application is much greater than the welding strength in the prior art, and the following examples are given:

[0062] Test one: the diameter of the TiNi shape memory alloy wire is 0.4 mm; the stainless steel wire is a 304 stainless steel wire with a diameter of 0.4 mm; the connecting pipe is a copper hollow pipe with a length of 1.7 mm and a wall thickness of 0.1 mm, and the TiNi shape memory alloy wire and the stainless steel wire have a distance of 0.1 mm, and the lap length of the connecting pipe and the metal wires on both sides is 0.8 mm.

[0063] The welding process parameters of step four are as follows: the TiNi shape memory alloy wire side, the laser welding process parameters are as follows: welding current 200 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min; and the stainless steel wire side, the laser welding process parameters are as follows: welding current 210 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min.

[0064] The welding process parameters of step five are as follows: the TiNi shape memory alloy wire side, the laser welding process parameters are as follows: welding current 190 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min; and the stainless steel wire side, the laser welding process parameters are as follows: welding current 200 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min.

[0065] Through the tensile strength test, the tensile strength of the TiNi shape memory alloy wire and the stainless steel wire welded by the application can reach 525 MPa (joint tension 67 N), and the joint strength is increased by 1.5 times compared with the welding method with an intermediate layer (350 MPa).

[0066] Test two: the diameter of the TiNi shape memory alloy wire is 0.4 mm; the stainless steel wire is a 304 stainless steel wire with a diameter of 0.4 mm, the connecting pipe is a copper hollow pipe with a length of 2.3 mm and a wall thickness of 0.1 mm, there is a space of 0.1 mm between the TiNi shape memory alloy wire and the stainless steel wire, and the overlap length of the connecting pipe and the two metal wires is 1.2 mm.

[0067] The welding process parameters of step four are as follows: welding current 200 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min; and the stainless steel wire side, the laser welding process parameters are as follows: welding current 210 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min.

[0068] The welding process parameters of step five are as follows: welding current 190 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min; and the stainless steel wire side, the laser welding process parameters are as follows: welding current 200 A, pulse width 8 ms, frequency 0.7 Hz, and protective gas flow 10 L / min.

[0069] Through the tensile strength test, the tensile strength of the TiNi shape memory alloy wire and the stainless steel wire welded by the application can reach 708 MPa (joint tension 89 N), and the joint strength is increased by more than twice compared with the welding method with an intermediate layer (350 MPa).

[0070] The above examples are only illustrative of the present application and do not limit the protection scope thereof, and the person skilled in the art can also make partial changes thereto, as long as the changes do not exceed the spirit and essence of the present application and are within the protection scope of the present application.

Claims

1. A welding jig for a TiNi shape memory alloy wire and a stainless steel wire, characterized by: Includes a base (1), a chuck (23), a slide (5), a front clamp (6), and a rear clamp (7); Two supports (11) are set on the base (1) from left to right. A tube shaft (2) is rotatably set on the support (11). The two tube shafts (2) are coaxial. The inner end of the tube shaft (2) protrudes from the inner side of the corresponding support (11). A chuck (23) is provided at the inner end of the tube shaft (2). A lifting platform (4) is provided on the base (1). The lifting platform (4) is located between two supports (11). A slide (5) is provided at the top of the lifting platform (4). The front clamp (6) and the rear clamp (7) slide in conjunction with the slide (5) respectively. The bottom of the front clamp (6) and the rear clamp (7) are provided with several opposing long strips (61). The long strips (61) of the front clamp (6) and the long strips (61) of the rear clamp (7) are interleaved. The slide (5) is equipped with a drive screw (52) that can be assembled into a working plane. The drive screw (52) has opposite threads at the front and rear. The front clamping plate (6) and the rear clamping plate (7) are equipped with drive blocks (62). The drive blocks (62) have screw holes. The two drive blocks (62) are respectively threaded to the front and rear of the drive screw (52). The front clamping plate (6) and the rear clamping plate (7) are equipped with quick clamps (8). The connector (33) is heat-melted by laser welding so that it is connected to the TiNi shape memory alloy wire (31) and the stainless steel wire (32) respectively; The connector (33) is a number of stacked metal sheets or metal tubes. When the connector (33) is a metal tube, the front clamp (6) and the rear clamp (7) are clamped on the outer periphery of the connector (33). The TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively inserted into the two tube shafts (2) and respectively protruded into both ends of the connector (33). The TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively clamped and fixed by the corresponding chuck (23). When the connector (33) is a number of stacked metal sheets, the TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively inserted into the two tube shafts (2) and placed close to each other on the working plane. The TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively clamped and fixed by the corresponding chuck (23). The connector (33) is placed on the TiNi shape memory alloy wire (31) and the stainless steel wire (32). The front and rear ends of the connector (33) are respectively pressed by the corresponding quick clamps (8) on the same side.

2. A welded clamp of a TiNi shape memory alloy wire and a stainless steel wire according to claim 1, characterized in that: The slide block (5) is provided with two axially extending light rods (51), and the front clamping plate (6) and the rear clamping plate (7) are each provided with two sliders (63). The two sliders (63) of the front clamping plate (6) are respectively fitted and slidably engaged with the two light rods (51), and the two sliders (63) of the rear clamping plate (7) are respectively fitted and slidably engaged with the two light rods (51).

3. The welded clamp of a TiNi shape memory alloy wire and a stainless steel wire according to claim 1, characterized by: The chuck (23) is a double-jaw chuck (23).

4. The welding fixture for TiNi shape memory alloy wire and stainless steel wire according to claim 1, characterized in that: The tube shaft (2) is connected to the bracket (11) via a bearing.

5. A welding fixture for TiNi shape memory alloy wire and stainless steel wire according to any one of claims 1-4, characterized in that: The outer periphery of the tube shaft (2) is provided with two axially symmetrical top recesses. A positioning sleeve (22) is sleeved on the tube shaft (2). The positioning sleeve (22) is connected to the bracket (11). A spring pin (21) is provided on the positioning sleeve (22). The spring pin (21) cooperates with any of the top recess pins.

6. A method for welding TiNi shape memory alloy wire and stainless steel wire, implemented using a welding fixture for TiNi shape memory alloy wire and stainless steel wire as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Place the TiNi shape memory alloy wire (31), stainless steel wire (32), and connector (33) into the polishing solution separately to remove the oxide film; Step 2: Place the TiNi shape memory alloy wire (31), stainless steel wire (32), and connector (33) into an acetone solution to remove surface oil stains; Step 3: Adjust the height of the lifting platform (4) and fix the TiNi shape memory alloy wire (31), stainless steel wire (32) and connector (33) onto the welding fixture respectively; Step 4: The connector (33) is heat-melted by laser welding so that it is connected to the TiNi shape memory alloy wire (31) and the stainless steel wire (32) respectively; The connector (33) is a number of stacked metal sheets or metal tubes. When the connector (33) is a metal tube, the front clamp (6) and the rear clamp (7) are clamped on the outer periphery of the connector (33). The TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively inserted into the two tube shafts (2) and respectively protruded into both ends of the connector (33). The TiNi shape memory alloy wire (31) and the stainless steel wire (32) are respectively clamped and fixed by the corresponding chuck (23). When the connector (33) is a number of stacked metal sheets, the TiNi shape memory alloy wire (31) and stainless steel wire (32) are respectively inserted into the two tube shafts (2) and placed close to each other on the working plane. The TiNi shape memory alloy wire (31) and stainless steel wire (32) are respectively clamped and fixed by the corresponding chuck (23). The connector (33) is placed on the TiNi shape memory alloy wire (31) and stainless steel wire (32). The front and rear ends of the connector (33) are respectively pressed by the corresponding quick clamps (8) on the same side. Step 5: Loosen the connector (33), rotate the two chucks (23) 180° in the same direction, and repeat step 4.

7. The welding method for TiNi shape memory alloy wire and stainless steel wire according to claim 6, characterized in that: The laser welding process parameters are: pulse width 0.1-50ms, frequency 0.1-1Hz, shielding gas flow rate 5-20L / min, welding current 10-800A, and the welding current on the stainless steel wire (32) side is 1-100A higher than the welding current on the TiNi shape memory alloy wire (31) side, and the welding current on any side after rotating 180° is 1-100A lower than the welding current on that side before rotation.

8. The welding method for TiNi shape memory alloy wire and stainless steel wire according to claim 6, characterized in that: The connector (33) is made of copper, nickel or tantalum.

9. The welding method for TiNi shape memory alloy wire and stainless steel wire according to claim 6, characterized in that: When the connector (33) is a metal tube, the wall thickness of the connector (33) is 0.1 to 16 mm; when the connector (33) is a number of stacked metal sheets, the total thickness of the connector (33) is 0.1 to 16 mm, and the thickness of a single layer is 0.1 to 1 mm.

10. A welding method for TiNi shape memory alloy wire and stainless steel wire according to claim 6, characterized in that: The spacing between the TiNi shape memory alloy wire (31) and the stainless steel wire (32) is 0.1 to 1 mm.

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