Phase change temperature testing device

Abstract

The utility model provides a phase-change temperature testing device, which comprises a liquid storage tank for containing heat transfer fluid to soak a test sample; the magnetic stirring module comprises a body and a rotor, a liquid storage tank is placed on the body, and the rotor placed in the liquid storage tank rotates to stir the heat transfer fluid; a heating module for heating the heat transfer fluid; the test module comprises a gravity table, a supporting structure, a temperature sensor and a laser ranging probe; the gravity table is pressed on the test sample and ascends along with the heated rebound of the test sample; a laser ranging probe is installed on the supporting structure and located above the gravity table to monitor the ascending distance of the gravity table. The temperature sensor is arranged in the liquid storage tank to measure the temperature of the heat transfer fluid; and the clamp is arranged at the bottom of the inner side of the liquid storage tank and is used for clamping a test sample. The phase transition temperature testing device measures the phase transition temperature of the shape memory alloy product based on the BFR testing method, the detection cost can be reduced, and the detection efficiency and the detection precision can be improved.

Description

Technical Field

[0001] The utility model belongs to the field of phase change temperature detection, and in particular relates to a phase change temperature testing device for detecting the phase change point temperature of shape memory alloy products. Background Art

[0002] Since the first cardiac stent intervention surgery was performed in China in 1984, the number of cardiac stent implants has grown rapidly, especially in the past 20 years. With the great achievements of China's reform and opening up, people's living standards have been greatly improved, the medical industry has also made great progress, and the cardiac stent market has also been expanding. According to data, the scale of China's cardiac stent market in 2020 is about 20.44 billion yuan, an increase of 14.1% over 2019. There are many kinds of auxiliary stent products, among which nickel-titanium alloy stents have attracted much attention due to their excellent material properties and performance. The phase change point temperature of such stents is an important part of the stent performance. Before use, the phase change point temperature must be tested to verify whether its performance meets the standard.

[0003] Currently, the phase transition temperature of nickel-titanium shape memory alloys is measured mainly through two measurement techniques, namely differential scanning calorimetry (DSC) and bend and free recovery (BFR). Generally speaking, the BFR test is more in line with the performance of the stent in actual working conditions after implantation in the body and is used more. The BFR test method includes cooling the sample to its nominally complete martensite phase, deforming the sample, heating the sample to the complete austenite phase, measuring the movement of the sample during the heating process, and plotting it against the sample temperature to finally determine the phase transition temperature. For the determination of the phase change temperature of nickel-titanium shape memory alloy by bending and free recovery, some existing test instruments use a non-contact visual test system, which collects the boundary image of the bracket through a camera, and then obtains the movement of the sample during the heating process based on the collected boundary image. This type of equipment is expensive and has a limited detection range. It cannot measure brackets with complex structures. More importantly, the measurement results are inaccurate and detection errors often occur. Some other test instruments measure the displacement of the sample during the heating process through contact displacement sensors. This method requires larger equipment and is very expensive. It also has slow cooling and heating speeds and low efficiency. In particular, there is a discrepancy between the force and the actual working conditions. Therefore, the measurement results are inaccurate.

[0004] Therefore, a more reasonable phase change temperature testing device is needed to solve the problems of high cost, low accuracy and limited measurement range in the phase change point temperature detection of shape memory alloy products. Utility Model Content

[0005] The purpose of the utility model is to provide a phase change temperature testing device, which uses the BFR testing method to measure the phase change temperature of various shape memory alloy products, thereby reducing the testing cost and improving the testing efficiency and testing accuracy.

[0006] To achieve the above object, the utility model provides a phase change temperature testing device, which includes:

[0007] A liquid storage tank, used to contain a heat transfer fluid, and then immerse the test sample prepared by the shape memory alloy in the heat transfer fluid;

[0008] A magnetic stirring module, comprising a body and a rotor, wherein the body is used to place the liquid storage tank, and the rotor is used to be placed in the liquid storage tank and rotate to stir the heat transfer fluid;

[0009] A heating module, used for heating the heat transfer fluid in the liquid storage tank;

[0010] The test module comprises a gravity table, a support structure, a temperature sensor and a laser ranging probe; the gravity table is used to press on the test sample, and then the test sample moves upward as it rebounds due to heat; the laser ranging probe is installed on the support structure, so that the laser ranging probe is located above the gravity table; the laser ranging probe is used to monitor the distance of the gravity table when it moves upward as the test sample rebounds due to heat; the temperature sensor is used to be placed in the liquid storage tank to measure the temperature of the heat transfer fluid; and

[0011] A fixture is used to be placed on the inner bottom of the liquid storage tank and to clamp the test sample.

[0012] In some embodiments, the supporting structure includes a column, a gravity table connecting arm and a moving part; the bottom end of the column is connected to the liquid storage tank, and the laser ranging probe is installed on the top end of the column; one end of the gravity table connecting arm is fixedly connected to the gravity table, and the other end of the gravity table connecting arm is fixedly connected to the moving part; the moving part is movably connected to the column.

[0013] In some embodiments, the moving part is a slider, the column is a slide rod, the slide rod and the slider constitute a linear guide moving pair, or the moving part is a screw nut, the column is a screw, and the screw nut and the screw constitute a ball screw moving pair.

[0014] In some embodiments, the gravity table is used to be independently set up and pressed on the test sample; the phase change temperature testing device also includes: a guide ring, which is used to be placed in the liquid storage tank and arranged around the gravity table, and a gap is reserved between the guide ring and the gravity table.

[0015] In some embodiments, at least one of the guide ring and the gravity table is a hollow structure.

[0016] In some embodiments, the support structure includes a column, a probe connecting arm and a cross-shaped connecting piece; the cross-shaped connecting piece is connected to have a first mounting hole and a second mounting hole; the axis of the first mounting hole is skewed and perpendicular to the axis of the second mounting hole; the bottom end of the column is connected to the inner bottom of the liquid storage tank; one end of the probe connecting arm is connected to the first mounting hole of a corresponding one of the cross-shaped connecting pieces, and the other end of the probe connecting arm is connected to the first mounting hole of another corresponding one of the cross-shaped connecting pieces; the laser ranging probe is connected to the second mounting hole of a corresponding one of the cross-shaped connecting pieces; and the top end of the column is connected to the second mounting hole of another corresponding one of the cross-shaped connecting pieces.

[0017] In some embodiments, the density of the gravity table is greater than the density of the heat transfer fluid.

[0018] In some embodiments, the liquid storage tank is a transparent structure.

[0019] In some embodiments, the phase change temperature testing device further comprises:

[0020] The low temperature storage device is used to store the heat transfer fluid so as to maintain the heat transfer fluid at a preset temperature, wherein the preset temperature is -20°C to -10°C.

[0021] In some embodiments, the heating module and the magnetic stirring module are integrated into an integrated device, the heating module includes a heating pad, the heating pad is placed on the main body, and the liquid storage tank is placed on the heating pad; and / or the temperature sensor is a thermocouple, which is used to be inserted into the liquid storage tank and has no contact with the test sample.

[0022] In summary, the phase change temperature testing device provided by the present invention has at least the following beneficial effects:

[0023] The phase change temperature test device includes: a liquid storage tank for containing a heat transfer fluid, and then a test sample prepared by immersing the heat transfer fluid into a shape memory alloy; a magnetic stirring module, including a body and a rotor, the body is used to place the liquid storage tank, and the rotor is used to be placed in the liquid storage tank and stir the heat transfer fluid after rotating; a heating module is used to heat the heat transfer fluid in the liquid storage tank; a test module includes a gravity table, a support structure, a temperature sensor and a laser ranging probe; the gravity table is used to press on the test sample, and then the test sample rebounds due to heat and moves upward; the laser ranging probe is installed on the support structure, and then the laser ranging probe is located above the gravity table; the laser ranging probe is used to monitor the distance when the gravity table rebounds due to heat and moves upward; the temperature sensor is used to be placed in the liquid storage tank to measure the temperature of the heat transfer fluid; and a clamp is used to be placed at the inner bottom of the liquid storage tank and clamp the test sample.

[0024] With such configuration, the above-mentioned test device can measure the displacement of the gravity table during the sample's thermal rebound process through a laser ranging probe, thereby obtaining a displacement-time curve, and synchronously obtain the heating temperature of the heat transfer fluid in conjunction with a temperature sensor, thereby obtaining a temperature-time curve. Finally, based on the displacement-time curve and the temperature-time curve, the displacement-temperature curve of the sample during thermal rebound can be obtained. Based on the displacement-temperature curve, the phase change point temperature (af) of the test sample can be determined. This detection method overcomes the defects of visual measurement of phase change temperature and the defects of contact displacement sensor measurement of phase change temperature. Not only is the structure of the entire device simpler, it occupies less space, has low cost, and is easy to operate, but the test results are more accurate, and it can measure brackets of various structures with a wide measurement range.

[0025] In the above phase change temperature test device, if the gravity table is independently set and pressed on the test sample, the influence of friction on the test result can be eliminated, making the test result more accurate. At the same time, by setting a guide ring on the periphery of the gravity table, the range of movement of the gravity table in the horizontal direction can be limited, thereby ensuring that the gravity table is within the monitoring range of the laser ranging probe and will not run out of the monitoring range, thereby ensuring the accuracy of the test result. In addition, the guide ring can reduce the possibility of the gravity table tipping over during the sample rebound process, thereby improving the reliability of the test.

[0026] In the above phase change temperature testing device, if a low-temperature storage device is added, the heat transfer fluid can be cooled in advance, and then the cooled heat transfer fluid can be used immediately during the test, thereby reducing the test time, improving the test efficiency, and making the operation more convenient and quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Those skilled in the art will appreciate that the drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0028] Figure 1 This is a schematic diagram of the overall structure of a phase change temperature testing device provided by one embodiment of the utility model; wherein a rotor and a fixture are placed at the inner bottom of the liquid storage tank;

[0029] Figure 2 A front view of a phase change temperature testing device provided by one embodiment of the utility model;

[0030] Figure 3 A top view of a phase change temperature testing device provided in one embodiment of the utility model;

[0031] Figure 4 A schematic diagram of the structure of a test module provided by an embodiment of the utility model; wherein the moving part is a slider, the column is a slide bar, and the slider and the slide bar form a linear guide moving pair;

[0032] Figure 5 A schematic diagram of the structure of a test module provided by another embodiment of the utility model; wherein the moving part is a lead screw nut, the column is a lead screw, and the lead screw nut and the lead screw form a ball screw moving pair;

[0033] Figure 6 This is a schematic diagram of the overall structure of a phase change temperature test device provided by another embodiment of the utility model; wherein the liquid storage tank is omitted, the gravity table is not connected to the support structure but is independently arranged on the test sample, and a guide ring is arranged on the periphery of the gravity table;

[0034] Figure 7 for Figure 6 An enlarged view of the structure in FIG. 1 ; wherein a gap d is reserved between the gravity table and the guide ring;

[0035] Figure 8 A schematic diagram of a method of pressing a gravity table onto a test sample and tracking the movement of the test sample when it rebounds after being heated, provided by an embodiment of the utility model;

[0036] Fig. 9 A displacement-temperature curve diagram for determining phase change temperature using the tangent method provided in one embodiment of the present invention; wherein the abscissa is temperature (unit: °C) and the ordinate is displacement (unit: Mm).

[0037] In the attached figure:

[0038] 100-magnetic stirring module; 101-main body; 102-rotor; 200-heating module; 201-heating pad; 300-test module; 301-gravity table; 3011-through hole; 302-support structure; 3021-column; 3022-fixed block; 3023-gravity table connecting arm; 3024-moving part; 3025-probe connecting arm; 3026-cross-shaped connector; 303-laser ranging probe; 304-guide ring; 400-liquid storage tank; 500-clamp; 10-test sample. DETAILED DESCRIPTION

[0039] In order to make the purpose, advantages and features of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model. The same or similar reference numerals in the drawings represent the same or similar components.

[0040] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner, so the diagram only shows the components related to the present invention rather than drawing according to the number, shape and size of the components in the actual implementation. The type, quantity and proportion of each component in the actual implementation can be a random change, and the component layout type may also be more complicated.

[0041] In addition, each embodiment of the following description has one or more technical features, but this does not mean that the user of the present invention must implement all the technical features in any embodiment at the same time, or can only implement part or all of the technical features in different embodiments separately. In other words, under the premise of being possible to implement, those skilled in the art can selectively implement part or all of the technical features in any embodiment according to the disclosure of the present invention and according to the design specifications or implementation requirements, or selectively implement a combination of part or all of the technical features in multiple embodiments, thereby increasing the flexibility of the implementation of the present invention.

[0042] As used in this specification, the singular forms "one", "an", and "the" include plural objects, and the plural form "a plurality" includes more than two objects, unless the content clearly indicates otherwise. As used in this specification, the term "or" is generally used in a sense that includes "and / or", unless the content clearly indicates otherwise, and the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium, and it can be a connection between two elements or an interactive relationship between two elements. Relational terms such as the terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor do they indicate or imply relative importance or implicitly indicate the number of technical features indicated. It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The core idea of ​​the utility model is to provide a phase change temperature testing device for measuring the phase change point temperature of shape memory alloy products. The shape memory alloy products involved in this article are specifically interventional stent products in the medical field, which can be heart stents, various vascular stents or stents for other purposes, without limitation. The materials of shape memory alloy products include but are not limited to nickel-titanium-based shape memory alloys.

[0044] In order to enable those skilled in the art to better understand the technical solution provided by the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0045] Please refer to Figures 1 to 8 The utility model provides a phase change temperature testing device, which includes: a magnetic stirring module 100, a heating module 200, a testing module 300, a liquid storage tank 400 and a fixture 500.

[0046] First, the liquid storage tank 400 is described. The liquid storage tank 400 can be a transparent structure (such as transparent plastic) or an opaque structure. Preferably, the liquid storage tank 400 adopts a transparent structure so that the tester can observe the test state and make the test more convenient. The shape and size of the liquid storage tank 400 are not limited. In addition to the cylindrical liquid storage tank 400 described in the figure, a liquid storage tank 400 such as a rectangular, oval or other arbitrary shape can also be used. The function of the liquid storage tank 400 is to hold a heat transfer fluid, which is a heat transfer fluid bath for soaking the test sample 10. The test sample 10 is a shape memory alloy bracket product. After the test sample 10 is immersed in the heat transfer fluid of the liquid storage tank 400, the heat transfer fluid can be heated to make the test sample 10 rebound and expand, and then the phase change point temperature of the test sample 10 can be determined.

[0047] Specifically, the heat transfer fluid in the liquid storage tank 400 is heated by the heating module 200. Since the structure of the heating module 200 is not limited, its position and connection relationship are also not limited, as long as the heating module 200 can heat the heat transfer fluid in the liquid storage tank 400.

[0048] The magnetic stirring module 100 is used to stir the heat transfer fluid so that the heat transfer fluid is evenly mixed and heated more evenly, thereby improving the accuracy of the test results. The magnetic stirring module 100 can be implemented by a commonly used magnetic stirrer. The magnetic stirring module 100 specifically includes a body 101 and a rotor 102; the body 101 is the main control part of the magnetic stirrer, which uses a magnetic field to drive the magnetic rotor 102 placed in the liquid storage tank 400 to rotate, and the rotor 102 rotates to stir the heat transfer fluid. Optionally, the rotation speed of the rotor 102 is 100r / min-150r / min.

[0049] In some optional embodiments, the magnetic stirring module 100 cooperates with the heating temperature control to heat and control the temperature of the heat transfer fluid according to the test requirements, thereby controlling the temperature of the test sample 10. Therefore, preferably, the magnetic stirring module 100 and the heating module 200 are integrated into an integrated device. Preferably, the heating module 200 includes a heating pad 201, and the heating pad 201 is integrated with the magnetic stirrer and cannot be separated physically. If the heating module 200 is integrated with the magnetic stirring module 100, the heating pad 201 is directly placed on the body 101, and then the liquid storage tank 400 is placed on the heating pad 201. In specific implementation, the heating module 200 and the magnetic stirring module 100 can be integrated, or they can be physically separated and independently set.

[0050] It should also be noted that the heating method includes but is not limited to the heating pad 201. For example, in some other embodiments, a heating wire (such as a glass fiber electric heating wire) is directly installed on the side wall of the liquid storage tank 400 for heating, or a heating rod is directly placed in the liquid storage tank 400 to heat the heat transfer fluid. In short, the present application does not specifically limit the method in which the heating module 200 heats the heat transfer fluid in the liquid storage tank 400.

[0051] Since commonly used magnetic stirrers have their own heating temperature control system, the simplest way is to integrate the heating module 200 and the magnetic stirring module 100 into an integrated device, and then the temperature of the test sample 10 can be accurately controlled by only setting the heating temperature through the main body 101 of the magnetic stirring module 100. In this way, the structure of the entire device is simpler, the size is smaller, and the operation is easier.

[0052] To increase the heating rate, a low-power heating module 200 is preferably selected, such as a silicone rubber heating plate, a temperature-adjustable silicone heating sheet, etc. Preferably, the heating rate of the heating module 200 is less than or equal to 4° C. / min.

[0053] Specifically, the test module 300 includes a gravity table 301 , a support structure 302 , a temperature sensor, and a laser ranging probe 303 .

[0054] refer to Figure 8 , the gravity table 301 is used to press on the test sample 10 and contact with the test sample 10, so that the gravity table 301 can move upward following the test sample 10's thermal rebound. It should be noted that during the test, the gravity table 301 always provides downward pressure on the test sample 10 to ensure that the gravity table 301 and the test sample 10 are not separated. For interventional stent products, during the thermal rebound of the test sample 10, the pressure to ensure that the gravity table 301 and the test sample 10 are not separated should not exceed 1N in theory, and the heating rate of the test sample 10 is less than or equal to 4°C / min.

[0055] It should be further explained that when the gravity table 301 is set, the weight of the gravity table 301 should be able to eliminate or reduce the influence of buoyancy on the test results, so that the test is as consistent as possible with the working conditions after the stent is implanted in the body. In other words, while the gravity table 301 contacts the test sample 10, it is also used to balance the buoyancy it is subjected to when placed below the liquid surface, and a small part of the gravity is reserved to apply pressure to the test sample 10 to prevent the two from separating. It can be understood that part of the gravity of the gravity table 301 balances the buoyancy, and the other part of the gravity is used to provide downward pressure to ensure that the gravity table 301 and the test sample 10 do not separate. The way to balance the buoyancy can be: simply set up the gravity table 301, balance the buoyancy through the gravity of the gravity table 301 itself, or add a balance block to the gravity table 301. If there is no balancing block, the gravity table 301 should be made of a material with a density greater than that of the heat transfer fluid. By increasing the material density of the gravity table 301, after the gravity table 301 balances the buoyancy, some downward residual force remains, ensuring that the gravity table 301 is always in contact with the test sample 10 and does not separate during the liquid flow or sample rebound process. Schematically, when the heat transfer fluid is anhydrous ethanol, the gravity table 301 can use plastics with a density greater than that of anhydrous ethanol, such as ABS, PA12 and other materials that are insoluble in the heat transfer fluid. If a balancing block is selected, balancing blocks of various weights can be prepared in advance, and the balancing block of the corresponding weight can be selected according to the needs to balance the buoyancy. Of course, the balancing block can also be of only one specification or multiple identical specifications, which can be set according to actual needs.

[0056] In actual operation, the counterweight required to balance the buoyancy can be determined in a manner that can be understood by those skilled in the art. For example, one determination method is: turn on the laser rangefinder, and by continuously adding counterweights, observe the curve of the falling distance and time when the gravity table 301 is lowered from the liquid surface and slowly and uniformly descends below the liquid surface. If the distance and time curve is almost a straight line, the counterweight obtained at this time is determined as the weight required to balance the buoyancy.

[0057] Furthermore, the support structure 302 is at least used to install the laser ranging probe 303, so that the laser ranging probe 303 can be located above the gravity table 301 and aligned with the gravity table 301 to achieve ranging. It is understandable that the laser ranging probe 303 monitors the distance (i.e., displacement) of the gravity table 301 when the test sample 10 rebounds due to heat and moves upward, and then obtains the displacement-time curve. The support structure 302 can be used for lifting or not, and the support structure 302 can slide or not slide in the horizontal direction. The horizontal position and the upper and lower positions of the laser ranging probe 303 are adjusted by the support structure 302 to ensure that the laser ranging probe 303 is aligned with the gravity table 301. The accuracy of the laser ranging probe 303 is preferably above 0.1mm.

[0058] In addition, the temperature sensor is any temperature measuring device with a temperature measuring function. In practice, the temperature sensor is used to be placed in the liquid storage tank 400 to directly measure the temperature of the heat transfer fluid. More specifically, the temperature sensor is used to measure the temperature near the test sample 10, and the temperature of the test sample 10 is determined based on the temperature of the heat transfer fluid. The temperature sensor feeds back a temperature-time curve, and the displacement-time curve can be combined to obtain a displacement-temperature curve (see Fig. 9 ). Preferably, the temperature sensor is a thermocouple (not shown), which is inserted into the liquid storage tank 400 and does not contact the test sample 10. This non-contact measurement can avoid obstruction to the test sample 10, and can ensure that the temperature measurement point relative to the test sample 10 remains unchanged, thereby ensuring the stability and accuracy of the temperature measurement. For the thermocouple, the thermocouple measures the temperature of the solution around the test sample 10 as the sample temperature in a non-contact manner. Since the thermocouple does not contact the test sample 10, the thermocouple does not obstruct the test sample 10 during the sample's thermal rebound process, and at the same time, the temperature measurement point does not change.

[0059] In some optional embodiments, the position of the thermocouple is constrained by the gravity table 301, so that the thermocouple can pass through the gravity table 301 and be inserted into the liquid storage tank 400. The specific method is as follows: Figure 4 and Figure 5 As shown, a through hole 3011 is provided on the gravity table 301, and the thermocouple is provided through the through hole 3011, and then the thermocouple is fixed by glue. In order to ensure the measurement accuracy, the temperature sensor used in this application is a high-precision sensor, and the measurement accuracy is not less than (ie greater than or equal to) 0.1°C.

[0060] In addition, the present application has no particular restrictions on the type of heat transfer fluid, and a suitable heat transfer fluid can be selected according to the characteristics of the tested sample 10. In more detail, if the austenite phase transformation completion temperature of the tested sample 10 is lower than room temperature, a heat transfer fluid with a freezing point lower than -55°C (-67°F) is selected, such as anhydrous ethanol; if the austenite phase transformation completion temperature of the tested sample 10 is higher than room temperature, a heat transfer fluid with a freezing point not higher than 10°C (50°F) is selected, such as anhydrous ethanol, ethylene glycol, water, sodium chloride solution of appropriate concentration, etc. It should be recognized that the heat transfer fluid has a non-heating state (i.e., a low temperature state) and a heating state. The temperature of the heat transfer fluid in the unheated state is used to achieve phase change testing of most interventional stent products; the end temperature of the austenite phase change of interventional stent products is generally around room temperature, 37°C lower than body temperature, and the start temperature of the austenite phase change is around 0-20°C, so the test start point temperature is lower than the start temperature of the austenite phase change. Specifically: in the unheated state, the temperature of the heat transfer fluid is -20°C to -10°C, and the heat transfer fluid is preferably anhydrous ethanol, which can reach this temperature. The heating temperature of the heat transfer fluid in the heated state should exceed the stent phase change point temperature (i.e., af temperature) by at least 10°C.

[0061] During the test, the test sample 10 is clamped by the fixture 500. Specifically, the fixture 500 is placed at the bottom of the inner side of the liquid storage tank 400. Figure 8 As shown, the fixture 500 only clamps a corner or one side of the test sample 10, and clamps it until the test sample 10 does not shake at will, but does not limit the test sample 10's rebound action when heated, so that the test sample 10 can recover freely and unconstrainedly during the heating process. The fixture 500 is placed at the bottom of the liquid storage tank 400 in a detachable or non-detachable manner. The fixture 500 can adopt any structure with a clamping function, such as various fixtures such as clamps and splints. Preferably, the fixture 500 is composed of two upper and lower metal plates, and a corner or one side of the test sample 100 is clamped by the two metal plates. The metal plates can be fixed together by screw connection or rubber band tightening or other connection methods. More appropriately, the fixture 500 is configured to be able to clamp test samples 10 of various structures, making the test more convenient, the measurement range wider, and the cost lower. Of course, the fixture 500 can also be a special fixture suitable for clamping test samples 10 of corresponding structures.

[0062] The following is a further description of the testing process of the phase change temperature testing device provided by the present application in conjunction with an exemplary embodiment. As can be understood by those skilled in the art, the phase change temperature testing standard of the test sample 10 can adopt ASTM F2082 (Test method for determining the phase change temperature of nickel-titanium shape memory alloy by bending and free recovery) or other known testing standards.

[0063] In this demonstration, a nickel-titanium alloy heart stent is used as an example, wherein the rotor 102 rotates at a speed of 100 r / min-150 r / min, the test time is within 1 hour, the heating temperature is 40°C, and the heating rate is less than 4°C / min. The specific test process is as follows:

[0064] (a) For alloys that are superelastic at room temperature, cool the bracket to -55°C or below using anhydrous ethanol or other suitable heat transfer fluid;

[0065] (b) Fixing the heart stent to the bottom of the fluid storage tank 400 by means of a clamp 500;

[0066] (c) injecting anhydrous ethanol that has been cooled in advance by a cold trap into the liquid storage tank 400;

[0067] (d) The gravity table 301 is moved to the top of the heart stent and lightly touches the heart stent, then the heart stent is slowly pressed downward to apply pressure to the heart stent, so that the heart stent is deformed (basically axially stretched and radially compressed) after being compressed. The force applied to compress and deform the heart stent is basically very small, because the heart stent will become soft at low temperatures, and the pressure may not exceed 1 kg, and the compression amount of the stent is generally about 50% of the outer diameter of the stent;

[0068] (e) After the heart stent is deformed by pressure, the liquid storage tank 400 is slowly heated by the heating pad 201, and the magnetic stirrer is turned on and rotated. At this time, the laser rangefinder probe 303 starts to measure the distance of the measurement point above the gravity table 301 (any point on the surface of the gravity table facing the laser rangefinder probe can be selected) as the stent rebounds, and the thermocouple records the real-time temperature near the heart stent; when the heating temperature exceeds the stent phase transition point temperature by at least 10°C, the test is stopped; note that when the displacement and temperature curves become flat, turn off the heating pad 201 and the magnetic stirrer, and stop recording;

[0069] (f) Finally, according to the test standard, the phase transition temperature (A f ); The phase transition temperature can be determined by the tangent method or the 95% recovery deformation method, and the tangent method is more commonly used.

[0070] In this embodiment, according to Fig. 9 The tangent method shown is used to determine the phase transition temperature. This is a commonly used method for determining the phase transition temperature that can be understood in the art and will not be described in detail.

[0071] It can be seen that the phase change temperature testing device provided in the present application can realize the phase change temperature detection of interventional stent products through the combined use of the laser ranging probe 303 and the temperature sensor. The structure of the entire device is simple, the space occupied is small, the cost is low, the operation is easy, and the detection range is not limited. It can measure both simple and complex stents. The most important thing is that the stress conditions can be closer to the actual conditions, the measurement results are more accurate, and the reliability is good.

[0072] There are many ways to set up the gravity table 301, which are described below by way of example.

[0073] In an exemplary embodiment, if Figures 1 to 5 As shown, the gravity table 301 is movably connected to the support structure 302 , and the gravity table 301 can move up and down on the support structure 302 .

[0074] Specifically, the support structure 302 includes a column 3021. The bottom end of the column 3021 is connected to the liquid storage tank 400, which can be a fixed connection, a rotational connection, or a movably connection. In practice, the column 3021 can be connected to the liquid storage tank 400, or the column 3021 can be connected to a position outside the test device. Preferably, the bottom end of the column 3021 is connected to the inner bottom of the liquid storage tank 400. Optionally, the bottom end of the column 3021 is connected to the inner bottom of the liquid storage tank 400 through a fixed block 3022. The fixed block 3022 can be connected to the bottom end of the column 3021 by threads or other commonly used fixing methods. The laser ranging probe 303 is installed at the top of the column 3021.

[0075] In some optional embodiments, the support structure 302 also includes a gravity table connecting arm 3023 and a moving part 3024; one end of the gravity table connecting arm 3023 is fixedly connected to the gravity table 301, and the other end of the gravity table connecting arm 3023 is fixedly connected to the moving part 3024; the moving part 3024 is movably connected to the column 3021, so that the moving part 3024 can move up and down on the column 3021. In this way, the support structure 302 is also used to support the gravity table 301, to prevent the gravity table 301 from shifting in the horizontal direction during the sample rebound process, and to prevent the gravity table 301 from tipping over during the sample rebound process. Because the moving part 3024 is movably connected to the column 3021, the gravity table 301 will be subjected to friction. Reduce friction as much as possible to make the test condition closer to the actual condition. Ways to reduce friction include: increasing lubrication at the sliding contact part, changing the form of friction movement, increasing the gap, etc.

[0076] In a specific embodiment, Figures 1 to 4 As shown, the moving part 3024 and the column 3021 are in sliding contact, and the two form a linear guide moving pair, that is, the moving part 3024 is a slider, and the column 3021 is a slide rod.

[0077] In another specific embodiment, Figure 5 As shown, the moving part 3024 and the column 3021 are in rolling contact, and the two form a ball screw moving pair, that is, the moving part 3024 is a screw nut, and the column 302 is a screw. The ball screw moving pair has less friction than the linear guide moving pair, making the running track of the gravity table 301 more stable, as shown in FIG. Fig. 9 The temperature-displacement curve shown is smoother and the test results are more accurate.

[0078] Optionally, both ends of the gravity table connecting arm 3023 are fixed to the moving part 3024 and the gravity table 301 respectively by means of set screws, but the method is not limited to screw fixation.

[0079] As a variation, Figure 6 As shown, the gravity table 301 is not connected to the support structure 302. In this case, the gravity table 301 is not affected by friction, eliminating the influence of friction on the test results. This arrangement is more in line with the performance of the stent in actual working conditions after implantation in the body, thereby making the measurement results more accurate. Furthermore, the gravity table connecting arm 3023 and the moving part 3024 can be eliminated, and only the column 3021 can be retained. The column 3021 is only used to support the installation of the laser ranging probe 303.

[0080] Preferably, the phase change temperature test device of the present application also includes a guide ring 304, which is used to be placed in the liquid storage tank 400 and arranged around the gravity table 301. A gap d is reserved between the guide ring 304 and the gravity table 301, and the gap should not be too large or too small, so as not to expand the range of motion of the gravity table 301 in the horizontal direction, and not to increase the friction between the gravity table 301 and the guide ring 301. Here, the range of motion of the gravity table 301 in the horizontal direction is limited by the guide ring 304, so as to prevent the gravity table 301 from having a large horizontal deviation during the sample rebound process, thereby ensuring that the gravity table 301 is within the monitoring range of the laser ranging probe 303 and will not run out of the monitoring range, while reducing the possibility of the gravity table 301 tipping over during the sample rebound process. The advantage of doing this is to eliminate the friction during the test process and make the measurement more accurate.

[0081] In order to reduce fluid resistance and make the temperature of the heat transfer fluid more uniform, at least one of the guide ring 304 and the gravity table 301 is a hollow structure. It should be understood that the fixture 500 and the test sample 10 are both covered in the guide ring 304. The bottom end of the guide ring 304 is detachably or non-detachably arranged on the inner bottom of the liquid storage tank 400.

[0082] Gravity table 301 can fully cover test sample 10 or partially cover test sample 10. Gravity table 301 can have any suitable shape, including but not limited to the circular structure shown in the figure. The diameter of gravity table 301 can be greater than or equal to or less than the diameter (i.e. outer diameter) of object 10 or. For non-circular structure, the diameter of gravity table 301 refers to the diameter of the circumscribed circle. Preferably, remove the connection between gravity table 301 and support structure 302, also cancel the balance block, and then select a larger gravity table 301, and simultaneously add a guide ring 304 at the periphery (surrounding the periphery of the central object) of gravity table 301, in this case, require the material density of gravity table 301 to be close to or slightly larger than the density of the selected heat transfer fluid, as in the present embodiment, the heat transfer fluid selects anhydrous ethanol as the bath heat fluid, then gravity table 301 selects PP material (i.e. polypropylene material) close to its density.

[0083] It should also be noted that the support structure 302 can be connected to the liquid storage tank 400, or it can be disconnected from the liquid storage tank 400. In order to reduce the volume of the entire device, preferably, the support structure 302 is fixed on the liquid storage tank 400 so that the two are physically inseparable, which is convenient for transportation, storage and use. Of course, the support structure 302 can also be separated from the liquid storage tank 400. Further, the support structure 302 can be fixed inside or outside the liquid storage tank 400. Preferably, the support structure 302 is fixed to the inner bottom of the liquid storage tank 400, but it should be recognized that in some other embodiments, the support structure 302 is fixed to the inner side wall or outer side wall or top of the liquid storage tank 400. It can be seen that the utility model does not limit the installation position of the support structure 302. Moreover, the shape and size of the support structure 302 are not particularly required, as long as the laser ranging probe 303 can be installed or the gravity table 301 can be further installed. Preferably, a support structure 302 with a simple structure, convenient processing and manufacturing and easy use is adopted.

[0084] In some optional embodiments, the support structure 302 further includes a probe connecting arm 3025 and a cross-shaped connecting piece 3026; the cross-shaped connecting piece 3026 is connected to a first mounting hole and a second mounting hole; the axis of the first mounting hole is perpendicular to the axis of the second mounting hole; the bottom end of the column 3021 is connected to the inner bottom of the liquid storage tank 400; one end of the probe connecting arm 3025 is connected to the first mounting hole of a corresponding cross-shaped connecting piece 3026, and the other end of the probe connecting arm 3025 is connected to the first mounting hole of another corresponding cross-shaped connecting piece 3026; the laser ranging probe 303 is connected to the second mounting hole of a corresponding cross-shaped connecting piece 3026; the top end of the column 3021 is connected to the second mounting hole of another corresponding cross-shaped connecting piece 3026. In specific use, the axis of the first mounting hole is in the horizontal direction, and the axis of the second mounting hole is in the up-down direction, so that the top end of the column 3021 is inserted into the second mounting hole and fixed, and the other end of the probe connecting arm 3025 is inserted into the first mounting hole and fixed. In this way, the column 3021 and the probe connecting arm 3025 can be installed more conveniently and their respective directions can be positioned.

[0085] In some optional embodiments, the phase change temperature testing device of the present application further includes a low temperature storage device for storing the heat transfer fluid so as to maintain the heat transfer fluid at a preset temperature of -20°C to -10°C. When testing is required, the heat transfer fluid in the low temperature storage device can be directly transferred to the liquid storage tank 400 for use. The low temperature storage device can be a low temperature cold trap, a constant temperature low temperature water tank, a refrigerator, a freezer or other.

[0086] It should be noted that the above description is only a description of the preferred embodiment of the utility model, and is not any limitation on the scope of the utility model. Any changes and modifications made by ordinary technicians in the field of the utility model based on the above disclosure content belong to the protection scope of the utility model. Obviously, technicians in this field can make various changes and modifications to the utility model without departing from the spirit and scope of the utility model. In this way, if these modifications and variations fall within the scope of the utility model and its equivalent technology, the utility model is also intended to include these modifications and variations.

Claims

1. A phase change temperature testing device, characterized in that: include: A liquid storage tank, used to contain a heat transfer fluid, and then immerse the test sample prepared by the shape memory alloy in the heat transfer fluid; A magnetic stirring module, comprising a body and a rotor, wherein the body is used to place the liquid storage tank, and the rotor is used to be placed in the liquid storage tank and rotate to stir the heat transfer fluid; A heating module, used for heating the heat transfer fluid in the liquid storage tank; The test module comprises a gravity table, a support structure, a temperature sensor and a laser ranging probe; the gravity table is used to press on the test sample, and then the test sample moves upward as it rebounds due to heat; the laser ranging probe is installed on the support structure, so that the laser ranging probe is located above the gravity table; the laser ranging probe is used to monitor the distance when the gravity table moves upward as the test sample rebounds due to heat; the temperature sensor is used to be placed in the liquid storage tank to measure the temperature of the heat transfer fluid; as well as A fixture is used to be placed on the inner bottom of the liquid storage tank and to clamp the test sample.

2. The phase change temperature testing device according to claim 1, characterized in that: The supporting structure includes a column, a gravity table connecting arm and a moving part; the bottom end of the column is connected to the liquid storage tank, and the laser ranging probe is installed on the top end of the column; one end of the gravity table connecting arm is fixedly connected to the gravity table, and the other end of the gravity table connecting arm is fixedly connected to the moving part; the moving part is movably connected to the column.

3. The phase change temperature testing device according to claim 2, characterized in that: The moving part is a slider, the column is a slide rod, the slide rod and the slider form a linear guide moving pair, or the moving part is a screw nut, the column is a screw, the screw nut and the screw form a ball screw moving pair.

4. The phase change temperature testing device according to claim 1, characterized in that: The gravity table is used to be independently arranged and pressed on the test sample; the phase change temperature testing device also includes: a guide ring, which is used to be placed in the liquid storage tank and arranged around the gravity table, and a gap is reserved between the guide ring and the gravity table.

5. The phase change temperature testing device according to claim 4, characterized in that: At least one of the guide ring and the gravity platform is a hollow structure.

6. The phase change temperature testing device according to claim 1, characterized in that: The supporting structure includes a column, a probe connecting arm and a cross-shaped connecting piece; the cross-shaped connecting piece is connected with a first mounting hole and a second mounting hole; the axis of the first mounting hole is perpendicular to the axis of the second mounting hole; the bottom end of the column is connected to the inner bottom of the liquid storage tank; one end of the probe connecting arm is connected to the first mounting hole of a corresponding one of the cross-shaped connecting pieces, and the other end of the probe connecting arm is connected to the first mounting hole of another corresponding one of the cross-shaped connecting pieces; the laser ranging probe is connected to the second mounting hole of a corresponding one of the cross-shaped connecting pieces; the top end of the column is connected to the second mounting hole of another corresponding one of the cross-shaped connecting pieces.

7. The phase change temperature testing device according to claim 1, characterized in that: The density of the gravity table is greater than the density of the heat transfer fluid.

8. The phase change temperature testing device according to claim 1, characterized in that: The liquid storage tank is a transparent structure.

9. The phase change temperature testing device according to claim 1, characterized in that: Also includes: The low temperature storage device is used to store the heat transfer fluid so as to maintain the heat transfer fluid at a preset temperature, wherein the preset temperature is -20°C to -10°C.

10. The phase change temperature testing device according to claim 1, characterized in that: The heating module and the magnetic stirring module are integrated into an integrated device, the heating module includes a heating pad, the heating pad is placed on the main body, and the liquid storage tank is placed on the heating pad; and / or the temperature sensor is a thermocouple, the thermocouple is used to be inserted into the liquid storage tank and has no contact with the test sample.

Images