Nickel-titanium memory alloy two-way training device and training method thereof

Abstract

The invention discloses a nickel-titanium memory alloy two-way training device which sequentially comprises a cover plate, a device body and a bottom plate from top to bottom. The cover plate is separably placed above the device main body; a cap is arranged on the lower surface of the cover plate; the cap is used for applying downward pressure to the nickel-titanium alloy sample training; a through hole for a nickel-titanium alloy sample to penetrate through is formed in the device main body; the bottom plate is detachably connected to the lower portion of the device body. After the bottom plate is fixedly connected with the device body, upward bearing force is applied to nickel-titanium alloy sample training. The training device is low in price and convenient to machine and obtain, the test cost can be greatly reduced, and the feasibility of carrying out two-way training on the nickel-titanium shape memory alloy through a thermal mechanical circulation method is improved. And through the designed water bath heating cabin, the training device can be quickly heated and cooled, so that the temperature transformation of the nickel-titanium alloy sample is quicker and more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment process of memory alloys, in particular to a nickel-titanium memory alloy two-way training device and a training method thereof. Background Art

[0002] In recent years, the two-way shape memory effect (TWSME) of shape memory alloys (SMA) has become a hot topic of research because of its ability to produce spontaneous reversible shape changes during thermal cycling. The two-way shape memory effect refers to the phenomenon that shape memory alloys can reversibly restore the shapes of the high-temperature phase (austenite phase) and the low-temperature phase (martensite phase) as the temperature changes. It has a wide range of application scenarios in the development of intelligent actuators and systems with simple and compact structures, easy assembly, and small size. Unlike other deformation phenomena based on thermoelastic martensitic phase transformation, TWSME is not an inherent characteristic of shape memory alloys, but requires special deformation treatment (usually called training) to obtain. Thermomechanical cycling is a commonly used two-way training method for nickel-titanium alloys. It is generally due to the application of different deformations at high and low temperatures to produce a directional dislocation structure inside the alloy, thereby realizing the TWSME of shape memory alloys.

[0003] At present, the training method of thermomechanical cycle is often achieved by applying stretching and recovery to the shape memory alloy material at a specific temperature through a universal mechanical testing machine. However, this method is difficult to control the temperature in actual operation. On the one hand, this is because the testing machine needs to be equipped with a special heating box and high and low temperature extensometers on the equipment, which is expensive; on the other hand, the heating and cooling process of the heating box is slow, which can easily cause unstable deformation of the material, and the entire training process requires multiple heating and cooling, which makes the process cumbersome and complicated to operate. Therefore, in order to enable the widespread application of nickel-titanium shape memory alloys and promote their practical application and industrialization, a thermomechanical cycle training method with low cost, simple operation, rapid response and stable deformation is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to provide a nickel-titanium memory alloy two-way training device to address the technical defects of the existing thermomechanical cycle training method, such as complicated operation, high cost and unstable deformation.

[0005] Another object of the present invention is to provide a training method for the above-mentioned nickel-titanium memory alloy two-way training device.

[0006] The technical solution adopted to achieve the purpose of the present invention is:

[0007] A nickel-titanium memory alloy two-way training device, comprising a cover plate, a device body and a bottom plate from top to bottom;

[0008] The cover plate can be detachably placed on the top of the device body; a cap is provided on the lower surface of the cover plate; the cap applies downward pressure to the nickel-titanium alloy sample training;

[0009] The device body is provided with a through hole for the nickel-titanium alloy sample to pass through;

[0010] The bottom plate is detachably connected to the bottom of the device body; after the bottom plate is fixedly connected to the device body, it applies an upward supporting force to the nickel-titanium alloy sample training.

[0011] In the above technical solution, the outer dimensions of the cover plate are a×a×b; the outer dimensions of the bottom plate are a×a×c; the thickness of the device body is d, and the outer dimensions are a×a×dmm, where a=15-50mm, b=2-5mm, c=4-10mm, and d=11-45mm.

[0012] In the above technical solution, the cap is arranged at the center of the lower surface of the cover plate; the cap is a rectangular protrusion.

[0013] In the above technical solution, the size of the cap is (2.1-5.1 mm)×(2.1-5.1 mm)×(1.8-6.5 mm).

[0014] In the above technical solution, the cross-section of the through hole is square.

[0015] In the above technical solution, the cross-sectional dimensions of the through hole are (2.2-5.2 mm)×(2.2-5.2 mm); the side length of the cross-sectional dimension of the through hole is 0.1-0.2 mm greater than the side length of the cap.

[0016] In the above technical solution, the base plate is detachably connected to the device body by bolts; a sink bolt hole is provided on the base plate; and a threaded hole is provided at a corresponding position below the device body.

[0017] In the above technical solution, the size of the sinker in the sinker bolt hole is φ5-10mm, the inner hole size is φ3-6mm, and the center is 4-10mm away from the boundary; the size of the threaded hole is φ2.5-5mm, and the depth is 5-10mm.

[0018] Another aspect of the present invention is the application of the above nickel-titanium memory alloy two-way training device in nickel-titanium memory alloy two-way training.

[0019] Another aspect of the present invention is a training method of the above nickel-titanium memory alloy two-way training device, characterized in that it comprises the following steps:

[0020] Step 1: fix the bottom plate to the lower surface of the device body; insert the nickel-titanium alloy sample into the through hole of the device body; cover the cover plate on the device body;

[0021] Step 2: Place the nickel-titanium memory alloy two-way training device assembled in step 1 in an electronic universal testing machine equipped with a water bath heating chamber, and inject boiling water into the water bath chamber to make the nickel-titanium alloy sample at the reverse martensitic transformation end temperature A. f above;

[0022] Step 3: Start the compression function of the electronic universal testing machine, so that the cover plate is pressed down to match the main body of the training device, and the pressure is maintained at this value without unloading;

[0023] Step 4: Open the water bath valve to drain the boiling water and add ice water to completely immerse the nickel-titanium memory alloy two-way training device. At this time, the nickel-titanium alloy sample is completely at the austenite transformation temperature M f the following;

[0024] Step 5: After the pressure is maintained for 5-10 minutes, unload and drain the ice water in the water bath;

[0025] Repeat steps 2-5 20-100 times;

[0026] Step 6: Disassemble the bottom plate from the device body, take out the trained nickel-titanium alloy sample, measure its length at high and low temperatures, and calculate its change rate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The nickel-titanium shape memory alloy two-way training device provided by the present invention is low-priced, easy to process and obtain, can greatly reduce the test cost, and improve the feasibility of two-way training of nickel-titanium shape memory alloy by the thermomechanical cycle method.

[0029] 2. The nickel-titanium memory alloy two-way training method provided by the present invention can quickly heat up and cool down the training device through the designed water bath heating chamber, so that the temperature change of the nickel-titanium alloy sample is faster and more accurate. The designed training device can constrain the deformation of the nickel-titanium alloy sample during the training process and keep it constant during multiple cycles of the training process, greatly improving the accuracy and stability of the two-way training.

[0030] 3. The nickel-titanium memory alloy two-way training method provided by the present invention can achieve a change rate of 12%, which is significantly better than the 5-8% that can be obtained by similar methods at present. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1The figure shows the assembly structure diagram of the nickel-titanium memory alloy two-way training device;

[0032] Figure 2 Shown is a schematic diagram of the structure of the cover plate;

[0033] Figure 3 Shown is a schematic structural diagram of the device body;

[0034] Figure 4 Shown is a schematic diagram of the structure of the base plate;

[0035] Figure 5 Shown are caps of different sizes used in Example 3;

[0036] Figure 6 Shown is a flow chart of the training method described in Example 2.

[0037] In the figure: 1-cover plate, 2-device body, 3-base plate, 4-cap, 5-through hole, 6-sunk platform bolt hole, 7-threaded hole. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Example 1

[0040] A nickel-titanium memory alloy two-way training device, such as Figure 1 As shown, it includes a cover plate 1, a device body 2 and a bottom plate 3 from top to bottom;

[0041] The cover plate 1 can be detachably placed on top of the device body 2; the outer contour dimensions of the cover plate are 20×20×2mm; a cap 4 is provided at the center of the lower surface of the cover plate 1; the cap is a rectangular protrusion of 2.1×2.1×(1.8-2.4)mm; during training, the cap 4 applies downward pressure to the nickel-titanium alloy sample training.

[0042] The device body 2 is 11 mm thick and has an outer dimension of 20×20 mm. The device body 2 is a hollow structure, and is provided with a through hole 5 for the nickel-titanium alloy sample to pass through; the cross section of the through hole is a square of 2.2×2.2 mm.

[0043] The bottom plate 3 is detachably connected to the bottom of the device body 2 by bolts; the outer contour size of the bottom plate 3 is 20×20×2mm; a sink bolt hole 6 is provided on the bottom plate 3; a threaded hole 7 is provided at a corresponding position below the device body 2; the sink size of the sink bolt hole 6 is φ5mm, the inner hole size is φ3mm, and the center distance from the boundary is 4mm; the threaded hole 7 has a size of φ2.5mm and a depth of 3mm. After the bottom plate 3 is fixedly connected to the device body 2, an upward supporting force is applied to the nickel-titanium alloy sample training.

[0044] Example 2

[0045] The training method of the nickel-titanium memory alloy two-way training device is characterized by comprising the following steps:

[0046] Step 1: fix the bottom plate 3 to the lower surface of the device body 2; put the nickel-titanium alloy sample into the through hole 5 of the device body; cover the cover plate 1 on the device body 2;

[0047] Step 2: Place the nickel-titanium memory alloy two-way training device assembled in step 1 in an electronic universal testing machine equipped with a water bath heating chamber, and inject boiling water into the water bath chamber to make the nickel-titanium alloy sample at the reverse martensitic transformation end temperature A. f above;

[0048] Step 3: Start the compression function of the electronic universal testing machine, so that the cover plate 1 is pressed down to match the training device body 2, and the pressure is maintained at this value without unloading;

[0049] Step 4: Open the water bath valve to drain the boiling water and add ice water to completely immerse the nickel-titanium memory alloy two-way training device. At this time, the nickel-titanium alloy sample is completely at the austenite transformation temperature M f the following;

[0050] Step 5: After the pressure is maintained for 5 minutes, unload and then drain the ice water in the water bath chamber;

[0051] Repeat steps 2-5;

[0052] Step 6: Disassemble the bottom plate from the device body, take out the trained nickel-titanium alloy sample, measure its length at high and low temperatures, and calculate its change rate.

[0053] Example 3

[0054] This embodiment uses caps 4 of different sizes to perform the training described in Embodiment 2, and the training results are as follows:

[0055] The NiTi alloy change rate was 8% after 30 tests using a cap with a center protrusion height of 1.8 mm;

[0056] The change rate was 12% after 30 tests using a cap with a 2.0 mm protrusion height;

[0057] The change rate was 10% when 30 tests were conducted using a cap with a 2.2 mm protrusion height;

[0058] 50 tests were conducted using a cap with a 2.0 mm protrusion height, and the resulting change rate was 12%;

[0059] The test was carried out 100 times using a cap with a protrusion height of 2.0 mm, and the change rate was 11%.

[0060] Too many repetitions will cause the rate of change to decrease, so you need to experiment to find the right number of cycles. The most suitable parameters for this example are a cap of 2.0 mm and 30 tests.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A nickel-titanium memory alloy two-way training device, characterized in that: From top to bottom, it includes a cover plate, a device body and a bottom plate; The cover plate can be detachably placed on the top of the device body; a cap is provided on the lower surface of the cover plate; the cap applies downward pressure to the nickel-titanium alloy sample training; The device body is provided with a through hole for the nickel-titanium alloy sample to pass through; The bottom plate is detachably connected to the bottom of the device body; after the bottom plate is fixedly connected to the device body, it applies an upward supporting force to the nickel-titanium alloy sample training.

2. The nickel-titanium memory alloy two-way training device according to claim 1, characterized in that: The outer dimensions of the cover plate are a×a×b; the outer dimensions of the bottom plate are a×a×c; the thickness of the device body is d, and the outer dimensions are a×a×dmm, wherein a=15-50mm, b=2-5mm, c=4-10mm, and d=11-45mm.

3. The nickel-titanium memory alloy two-way training device as claimed in claim 2, characterized in that: The cover cap is arranged at the center of the lower surface of the cover plate; the cover cap is a rectangular protrusion.

4. The nickel-titanium memory alloy two-way training device as claimed in claim 3, characterized in that: The size of the cap is (2.1-5.1 mm)×(2.1-5.1 mm)×(1.8-6.5 mm).

5. The nickel-titanium memory alloy two-way training device as claimed in claim 2, characterized in that: The cross section of the through hole is square.

6. The nickel-titanium memory alloy two-way training device according to claim 5, characterized in that: The cross-sectional dimensions of the through hole are (2.2-5.2 mm)×(2.2-5.2 mm); the side length of the cross-sectional dimensions of the through hole is 0.1-0.2 mm greater than the side length of the cap.

7. The nickel-titanium memory alloy two-way training device according to claim 1, characterized in that: The bottom plate is detachably connected to the device body by bolts; a sink bolt hole is arranged on the bottom plate; and a threaded hole is arranged at a corresponding position below the device body.

8. The nickel-titanium memory alloy two-way training device according to claim 1, characterized in that: The size of the sinker in the sinker bolt hole is φ5-10mm, the inner hole size is φ3-6mm, and the center distance from the boundary is 4-10mm; the size of the threaded hole is φ2.5-5mm, and the depth is 5-10mm.

9. Application of the nickel-titanium memory alloy two-way training device as claimed in any one of claims 1 to 8 in nickel-titanium memory alloy two-way training.

10. The training method of the nickel-titanium memory alloy two-way training device according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: fix the bottom plate to the lower surface of the device body; insert the nickel-titanium alloy sample into the through hole of the device body; cover the cover plate on the device body; Step 2: Place the nickel-titanium memory alloy two-way training device assembled in step 1 in an electronic universal testing machine equipped with a water bath heating chamber, and inject boiling water into the water bath chamber to make the nickel-titanium alloy sample at the reverse martensitic transformation end temperature A. f above; Step 3: Start the compression function of the electronic universal testing machine, so that the cover plate is pressed down to match the main body of the training device, and the pressure is maintained at this value without unloading; Step 4: Open the water bath valve to drain the boiling water and add ice water to completely immerse the nickel-titanium memory alloy two-way training device. At this time, the nickel-titanium alloy sample is completely at the austenite transformation temperature M f the following; Step 5: After the pressure is maintained for 5-10 minutes, unload and drain the ice water in the water bath; Repeat steps 2-5 20-100 times; Step 6: Disassemble the bottom plate from the device body, take out the trained nickel-titanium alloy sample, measure its length at high and low temperatures, and calculate its change rate.

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