Tensile testing device

Abstract

The utility model aims to provide the tensile testing device, so that the fracture times of an object to be tested under different stress amplitudes can be quickly tested; in order to achieve the purpose, the tensile testing device comprises a frame, a fixed pulley is rotatably mounted at the top of the frame, a rope matched with the fixed pulley is arranged on the fixed pulley, and the rope bypasses the top of the fixed pulley; the two ends of the rope extend downwards along the two sides of the fixed pulley respectively, so that one end of the rope is connected with a sliding block, a driving device controls the sliding block to reciprocate in the sliding rail in the direction of the rope, and the other end of the rope is connected with an object to be detected through a clamp. The rope is provided with an elastic section and a force measuring device, the frame-shaped frame is provided with a distance measuring device and a counter, the distance measuring device is used for monitoring the deformation quantity of the object to be measured, and the counter is used for recording the repeated movement times of the sliding block.

Description

Technical Field

[0001] The utility model relates to the technical field of fatigue testing, and particularly relates to a simple plastic tensile testing device, which can meet the comparative evaluation of the fatigue performance of materials in product development. Background Art

[0002] Fatigue testing is based on the phenomenon that within a certain stress and strain range, a material shows cracks or fractures after a certain number of cycles under repeated loading conditions. According to the stress-life curve or strain-life curve, the fatigue limit of the material can be evaluated, that is, the maximum stress or strain value at which the number of cycles does not cause fatigue failure.

[0003] Plastic fatigue testing is a method for testing the fatigue life of plastic materials and is important in the reliability evaluation of plastic materials. By evaluating aspects such as the fatigue strength, fatigue life, and fatigue fracture toughness of the material, the reliability and durability of plastic products can be better improved, the limitations and defects of the material can be discovered in a timely manner, and it provides a basis for the improvement and optimization of the material.

[0004] The fatigue behavior of thermoplastic materials, especially crystalline and semi-crystalline plastics, under dynamic tensile loads leads to changes in their long-term use stability and reliability. A convenient and reliable evaluation of the fatigue behavior of polymers can provide reliable basic data for material development and design and accelerate the product development speed. Currently, the fatigue behavior of materials can be measured by tensile testing machines, special fatigue equipment, etc. However, most fatigue testing devices are large in volume and expensive, especially the fatigue testing cycle is long, and testing devices such as tensile testing machines can only test one spline, seriously lengthening the entire fatigue testing time. Therefore, designing and developing a simple and reliable device can greatly accelerate the material development progress and reduce the testing costs.

[0005] Therefore, it is an urgent technical problem to provide a tensile testing device for the fatigue testing technology field, which can greatly accelerate the material development progress and reduce the testing costs. Summary of the Invention

[0006] The purpose of the utility model is to provide a tensile testing device to achieve rapid testing of the number of fractures of a test object under different stress amplitudes.

[0007] To achieve the above object, the solution of the present utility model is to provide a tensile testing device, comprising: a frame-shaped structure, a fixed pulley is rotatably installed on the top of the frame-shaped structure, a rope matching with the fixed pulley is arranged on the fixed pulley, and the rope bypasses the top of the fixed pulley; both ends of the rope extend downward along both sides of the fixed pulley respectively, so that one end of the rope is connected with a slider, and a driving device controls the slider to reciprocate along the direction of the rope in a slide rail, and the other end of the rope is connected with a test object through a fixture; the rope has an elastic section and a stress measuring device, when the slider reciprocates up and down, the stress on the rope is changed by the flexion and extension of the elastic section, and the stress measuring device is used to measure the stress on the rope; a distance measuring device and a counter are arranged on the frame-shaped structure, the distance measuring device is used to monitor the deformation amount of the test object, and the counter is used to record the number of times the slider moves repeatedly; preferably, the elastic section is a spring, and as a force value change buffer device, the spring reduces the change of the force value during the fatigue test.

[0008] Further, the driving device includes a crank-slider mechanism and a driving machine, the driving machine drives the crank-slider mechanism to move, and the crank-slider mechanism drives the slider to reciprocate up and down; by adjusting the rotation speed of the driving machine and the size of the crank-slider mechanism, the moving speed and stroke of the slider can be conveniently controlled, which enables the tensile testing device to adapt to different test requirements and realize tensile testing under various test conditions.

[0009] Further, the crank-slider mechanism includes a driving rod and a driven rod, one end of the driving rod is connected with the driving machine, the other end is connected with the driven rod, the circumferential movement of the driving rod drives the driven rod to move, one end of the driven rod is connected with the driving rod, and the other end is connected with the slider, driving the slider to move up and down in the guide rail; by adjusting parameters such as the lengths of the driving rod and the driven rod and the rotation frequency of the driving rod, the moving distance and speed of the slider can be accurately controlled.

[0010] Preferably, the moving distance of the slider is determined by the distance between the driving rod and the driven rod, and the moving distance of the slider is the sum of the distance between the driving rod and the driven rod minus the difference between the distance between the driving rod and the driven rod.

[0011] Further, the fixture includes an upper fixture and a lower fixture, the top of the upper fixture is connected with the rope, the bottom of the lower fixture is connected with the bottom of the frame-shaped structure, the upper end of the test object is fixed by the upper fixture, and the lower end of the test object is fixed by the lower fixture; the upper fixture fixes the upper end of the test object, while the lower fixture fixes the lower end of the test object. Such a fixing method can prevent the test object from moving or slipping during the test, thereby ensuring the accuracy and reliability of the test results, and can adapt to test objects of different sizes and shapes.

[0012] Preferably, a pull ring for fixing the rope is provided at the top of the upper clamp, and the rope is fixed by the pull ring, so that a stable connection structure can be formed between the upper clamp and the rope. This helps to resist the influence of external forces during the working process, prevent the upper clamp from loosening or shifting, and thus ensure the stability and safety of the entire structure.

[0013] Furthermore, an upper slot is provided on the bottom section of the upper fixture, and the upper end of the object to be tested is inserted into the upper slot and fixed in the upper slot. The design of the upper slot makes the installation and disassembly process of the object to be tested simple and quick, and can be designed and adjusted according to actual needs to adapt to objects to be tested of different specifications and sizes.

[0014] Furthermore, a lower slot is provided on the top section of the lower fixture, and the lower end of the object to be tested is inserted into the lower slot and fixed in the lower slot. The design of the lower slot makes the installation and disassembly process of the object to be tested simple and quick, and can be designed and adjusted according to actual needs to adapt to objects to be tested of different specifications and sizes.

[0015] Furthermore, a recess is provided through the side wall of the upper slot, and a screw is provided in the recess for fixing the object to be tested. An internal thread is provided in the recess, and the upper end of the object to be tested can be clamped and fixed by rotating the screw. The cooperation between the screw and the internal thread makes the fixation more firm and reliable, and can effectively prevent the object to be tested from shifting or shaking during testing or processing, thereby ensuring the accuracy of the test and the processing quality.

[0016] Furthermore, a hole is provided through the side wall of the lower slot, and a screw is provided in the hole to fix the object to be tested. The hole is provided with an internal thread, and the lower end of the object to be tested is clamped and fixed by rotating the screw. Since the screw can be rotated, it can be flexibly adjusted according to the size and shape of the object to be tested. This design enables the fixture to adapt to objects to be tested of different specifications, improving the versatility and flexibility of the fixture.

[0017] Furthermore, an adjustment screw is provided at the bottom of the lower clamp, and the frame is provided with a threaded sleeve at a position below the adjustment screw. The adjustment screw is cooperatively connected with the threaded sleeve, and a knob is provided at the bottom of the adjustment screw. The adjustment screw is controlled to rotate in the threaded sleeve by rotating the knob, thereby realizing the up and down movement of the lower clamp. This design allows the height of the lower clamp to be flexibly adjusted to accommodate objects of different sizes. The design of the knob makes the adjustment process simpler and more intuitive. The operator only needs to rotate the knob to realize the up and down movement of the lower clamp, without the need to use complicated tools or perform tedious disassembly and installation operations.

[0018] Further, a baffle is provided at the top of the upper fixture, and the distance measuring device is disposed above the baffle. The distance measuring device detects the distance between the distance measuring device and the baffle in real time. Since the baffle can reflect signals in a larger range, the accuracy and reliability of the distance detection are ensured.

[0019] Preferably, the distance measuring device is an infrared distance sensor. The strain of the object to be measured after each fatigue test is represented by the change in the distance between the infrared distance sensor and the baffle after each fatigue test.

[0020] Preferably, the counter is disposed above the slider. The counter emits a signal to the upper surface of the slider and receives the reflected signal from the upper surface of the slider. The number of reciprocating movements of the slider is monitored by the change in the strength of the reflected signal. This non-contact monitoring method does not require additional sensors or mechanical devices to be installed on the slider. The non-contact monitoring method reduces the system instability factors caused by mechanical wear or contact sensor failures, thus simplifying the structure and maintenance cost of the system.

[0021] Advantages of the present utility model:

[0022] This device is simple to manufacture and can be quickly replicated. The device is small in size and can be placed in different constant temperature and humidity devices to meet the fatigue test requirements under different temperatures and humidities. Thus, the number of fractures of the object to be measured under different stress amplitudes can be quickly tested at different temperatures and humidities. This device uses a spring as a force value change buffer device, reducing the change in the force value during the fatigue test. Description of the Drawings

[0023] Figure 1 is a schematic diagram of a tensile test device provided by the present utility model;

[0024] Figure 2 is provided by the present utility model

[0025] As shown in the figure, 1 - driving device, 2 - slider, 3 - force measuring device, 4 - elastic section, 5 - upper fixture, 6 - object to be measured, 7 - lower fixture, 8 - distance measuring device, 9 - counter, 10 - void, 11 - screw. Detailed Embodiment

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model.

[0027] Embodiment 1

[0028] A tensile testing device, comprising: a frame-shaped rack, a fixed pulley is rotatably installed on the top of the frame-shaped rack, a rope matched with the fixed pulley is arranged on the fixed pulley, and the rope bypasses the top of the fixed pulley; both ends of the rope extend downward along both sides of the fixed pulley respectively, so that one end of the rope is connected with a slider 2, and a driving device 1 controls the slider 2 to reciprocate in the slide rail along the direction of the rope, and the other end of the rope is connected with a test object 6 through a clamp; the rope has an elastic section 4 and a force measuring device 3, when the slider 2 reciprocates up and down, the stress on the rope is changed by the flexion and extension of the elastic section 4, and the force measuring device 3 is used to measure the stress on the rope; a distance measuring device 8 and a counter 9 are arranged on the frame-shaped rack, the distance measuring device 8 is used to monitor the deformation amount of the test object 6, and the counter 9 is used to record the number of times the slider 2 moves repeatedly; preferably, the elastic section 4 is a spring, and as a force value change buffer device, the spring reduces the change of the force value during the fatigue test. The elastic coefficient of the spring is between 1-100 N / mm, and the length is between 50-300 mm. Springs with different elastic coefficients are selected according to the size and strength requirements of the test object 6. It is required that the spring cannot undergo permanent deformation under the specified force value, and the elongation rate is between 100-200 mm.

[0029] The driving device 1 includes a crank-slider mechanism and a driving machine, the driving machine drives the crank-slider mechanism to move, and the crank-slider mechanism drives the slider 2 to reciprocate up and down; by adjusting the rotation speed of the driving machine and the size of the crank-slider mechanism, the moving speed and stroke of the slider 2 can be conveniently controlled, which enables the tensile testing device to adapt to different test requirements and realize tensile testing under various test conditions; the crank-slider mechanism includes a driving rod and a driven rod, one end of the driving rod is connected with the driving machine, and the other end is connected with the driven rod. The circumferential movement of the driving rod drives the driven rod to move. One end of the driven rod is connected with the driving rod, and the other end is connected with the slider 2, driving the slider 2 to move up and down in the guide rail; by adjusting parameters such as the lengths of the driving rod and the driven rod and the rotation frequency of the driving rod, the moving distance and speed of the slider 2 can be precisely controlled; the moving distance of the slider 2 is determined by the distance between the driving rod and the driven rod. The moving distance of the slider 2 is the sum of the distances between the driving rod and the driven rod minus the difference between the distances between the driving rod and the driven rod.

[0030] Such as Figure 2As shown, the fixture includes an upper fixture 5 and a lower fixture 7. The top of the upper fixture 5 is connected to a rope, and the bottom of the lower fixture 7 is connected to the bottom of the frame-shaped structure. The upper end of the object to be tested 6 is fixed by the upper fixture 5, and the lower end of the object to be tested 6 is fixed by the lower fixture 7. The upper fixture 5 fixes the upper end of the object to be tested 6, while the lower fixture 7 fixes the lower end of the object to be tested 6. This fixing method can prevent the object to be tested 6 from moving or slipping during the test, thus ensuring the accuracy and reliability of the test results, and can adapt to objects to be tested 6 of different sizes and shapes. The top end of the upper fixture 5 is provided with a pull ring for fixing the rope. Fixing the rope through the pull ring can form a stable connection structure between the upper fixture 5 and the rope. This helps to resist the influence of external forces during operation, prevent the loosening or displacement of the upper fixture 5, and thus ensure the stability and safety of the entire structure. The bottom section of the upper fixture 5 is provided with an upper slot, and the upper end of the object to be tested 6 is inserted into the upper slot and fixed therein. The design of the upper slot makes the installation and disassembly process of the object to be tested 6 simple and fast, and can be designed and adjusted according to actual needs to adapt to objects to be tested 6 of different specifications and sizes.

[0031] A lower slot is provided on the top cross-section of the lower fixture 7. The lower end of the object under test 6 is inserted into the lower slot and fixed therein. The design of the lower slot makes the installation and removal process of the object under test 6 simple and fast, and can be designed and adjusted according to actual needs to adapt to objects under test 6 of different specifications and sizes; a clearance 10 is provided through the side wall of the upper slot. A screw 11 is fitted in the clearance 10 for fixing the object under test 6. The clearance 10 is provided with internal threads. By rotating the screw 11, the upper end of the object under test 6 can be clamped and fixed, so that the upper end of the object under test 6 can be clamped and fixed. The cooperation between the screw 11 and the internal threads makes the fixation more firm and reliable, and can effectively prevent the object under test 6 from shifting or shaking during testing or processing, thus ensuring the accuracy of testing and the processing quality; a clearance 10 is provided through the side wall of the lower slot. A screw 11 is fitted in the clearance 10 for fixing the object under test 6. The clearance 10 is provided with internal threads. By rotating the screw 11, the lower end of the object under test 6 can be clamped and fixed. Since the screw 11 can rotate, it can be flexibly adjusted according to the size and shape of the object under test 6. This design enables the fixture to adapt to objects under test 6 of different specifications, improving the versatility and flexibility of the fixture; an adjustment screw is provided at the bottom of the lower fixture 7. A screw sleeve is provided at the position of the frame below the adjustment screw. The adjustment screw is connected to the screw sleeve in a mating manner. A knob is provided at the bottom of the adjustment screw. By rotating the knob, the adjustment screw is controlled to rotate in the screw sleeve, thereby realizing the up and down movement of the lower fixture 7. This design enables the height of the lower fixture 7 to be flexibly adjusted to adapt to objects under test 6 of different sizes. The design of the knob makes the adjustment process simpler and more intuitive. The operator only needs to rotate the knob to realize the up and down movement of the lower fixture 7 without using complex tools or performing cumbersome disassembly and installation operations.

[0032] A baffle is provided at the top of the upper fixture 5. The distance measuring device 8 is provided above the baffle. The distance measuring device 8 continuously detects the distance between the distance measuring device 8 and the baffle. Since the baffle can reflect signals in a larger range, the accuracy and reliability of the distance detection are ensured; the baffle is annular, and the distance measuring device 8 is an infrared distance sensor. The change in the distance between the infrared distance sensor and the baffle after each fatigue test represents the strain of the object under test 6 after each fatigue test.

[0033] The counter 9 is arranged above the slider 2. The counter 9 emits signals to the upper surface of the slider 2 and receives the reflected signals from the upper surface of the slider 2. The number of reciprocating motions of the slider 2 is monitored by the change in the intensity of the reflected signals. This non-contact monitoring method eliminates the need to install additional sensors or mechanical devices on the slider 2. The non-contact monitoring method reduces the system instability factors caused by mechanical wear or contact sensor failures, thereby simplifying the system structure and maintenance costs.

[0034] When this device is used in experiments, the tester fixes the test object 6 through the upper fixture 5 and the lower fixture 7. The stress value is read by a digital display force sensor. The rotational speed of the driving machine is set, the driving machine is started, which drives the slider 2 to move up and down. The strain of each fatigue experiment is obtained through the distance measuring device 8, the number of experiments is read through the counter 9, and the stress value, the state of the test object 6, and the number of fatigue experiments are observed regularly.

[0035] Embodiment 2

[0036] The difference between this embodiment and Embodiment 1 is that the driving device 1 includes a cylinder and a push rod. The cylinder is fixed to the frame-shaped rack by screws. The cylinder drives the push rod to drive the slider 2 to move up and down. The cylinder is equipped with a magnetic switch to control the movement frequency of the slider 2. The cylinder is connected to an air pipe joint, and the displacement of the slider 2 is controlled by the air intake.

[0037] Embodiment 3 applies the simple plastic tensile test device of Embodiment 1 for fatigue test settings

[0038] Comparative example: Through a fatigue testing machine, a force of 600 N is applied to test the fatigue S-N curve of ASTM D638 Type I PP30GF splines.

[0039] Test group 1: Clamp an ASTM D638 Type I PP30GF spline with a fixture, select a spring with a spring elastic coefficient of 3, adjust the lengths of the driving rod and the driven rod to make the force measuring device 3 display 600 N, read the data of the counter 9 and the infrared distance sensor, and record the number of fatigue experiments when the spline breaks.

[0040] Test group 2: Clamp an ISO 527B type PP / GF30 spline with a fixture, select a spring with a spring elastic coefficient of 15, place the device in a high-temperature box, adjust the lengths of the driving rod and the driven rod to make the force measuring device 3 display 3000 N, adjust the temperature of the high-temperature box to 40 °C, read the data of the counter 9 and the infrared distance sensor, and record the number of fatigue experiments when the spline breaks.

[0041] Test group 3: Use a fixture to clamp the ASTM D Type I PA / GF20 specimen, select a spring with a spring coefficient of 25, put the device into a constant temperature and humidity chamber, adjust the length of the active rod and the driven rod, make the force measuring device 3 display 4000N, adjust the temperature of the constant temperature and humidity chamber to 80℃, and the humidity to 80%, read the data of the counter 9 and the infrared distance sensor, and record the number of fatigue tests when the specimen breaks.

[0042] Test group 4: Use a fixture to clamp the ASTM D Type I ABS spline, select a spring with a spring coefficient of 12, adjust the length of the active rod and the driven rod, make the force measuring device 3 display 1500N, read the data of the counter 9 and the infrared distance sensor, and record the number of fatigue tests when the spline breaks.

[0043] Test group 5: Use a fixture to clamp the ASTM D Type I PS spline, select a spring with a spring coefficient of 20, adjust the length of the active rod and the driven rod, make the force measuring device 3 display 2000N, read the data of the counter 9 and the infrared distance sensor, and record the number of fatigue tests when the spline breaks.

[0044] Through the above test, the test results are as follows:

[0045] Through verification, the device has the following advantages: 1. It is simple to make and can be quickly replicated to test multiple groups of fatigue experiments at the same time; 2. The device is small in size and can be placed in different constant temperature and humidity equipment to meet the fatigue test requirements under different temperatures and humidities, so that the fatigue times of plastics under different stress amplitudes can be quickly tested under different temperatures and humidities; 3. The device uses a spring as a force change buffer device to reduce the change of force during the creep process. The device is simple and the force is stable. It can be applied to test objects of different strengths through spring matching6.

[0046] Obviously, the described embodiments are only some embodiments of the utility model, not all embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

Claims

1. A tensile testing device, characterized in that, Comprising: A frame-shaped structure, on the top of which a fixed pulley is rotatably installed. A rope is provided on the fixed pulley and is matched with it. The rope bypasses the top of the fixed pulley. The two ends of the rope extend downward along both sides of the fixed pulley respectively, so that one end of the rope is connected to a slider (2). A driving device (1) controls the slider (2) to reciprocate in the slide rail along the direction of the rope. The other end of the rope is connected to a test object (6) through a clamp. The rope has an elastic section (4) and a force measuring device (3). When the slider (2) reciprocates up and down, the stress on the rope is changed by the flexion and extension of the elastic section (4). The force measuring device (3) is used to measure the stress on the rope. A distance measuring device (8) and a counter (9) are provided on the frame-shaped structure. The distance measuring device (8) is used to monitor the deformation of the test object (6), and the counter (9) is used to record the number of times the slider (2) moves repeatedly.

2. The tensile testing device according to claim 1, characterized in that, The driving device (1) includes a crank-slider mechanism and a driving machine. The driving machine drives the crank-slider mechanism to move, and the crank-slider mechanism drives the slider (2) to reciprocate up and down.

3. A tensile testing device according to claim 2, characterized in that, The crank-slider mechanism includes a driving rod and a driven rod. One end of the driving rod is connected to the driving machine, and the other end is connected to the driven rod. The circumferential movement of the driving rod drives the driven rod to move. One end of the driven rod is connected to the driving rod, and the other end is connected to the slider (2), driving the slider (2) to move up and down in the guide rail.

4. A tensile testing device according to claim 3, characterized in that, The clamp includes an upper clamp (5) and a lower clamp (7). The top of the upper clamp (5) is connected to the rope, and the bottom of the lower clamp (7) is connected to the bottom of the frame-shaped structure. The upper end of the test object (6) is fixed by the upper clamp (5), and the lower end of the test object (6) is fixed by the lower clamp (7).

5. A tensile testing device according to claim 4, characterized in that, An upper slot is provided on the bottom cross-section of the upper clamp (5). The upper end of the test object (6) is inserted into the upper slot and is fixed in the upper slot.

6. The tensile testing device according to claim 5, characterized in that, A lower slot is provided on the top cross-section of the lower clamp (7). The lower end of the test object (6) is inserted into the lower slot and is fixed in the lower slot.

7. The tensile testing device according to claim 6, characterized in that, A void (10) is provided through the side wall of the upper slot. A screw (11) is fitted in the void (10) for fixing the test object (6). The void (10) is provided with internal threads, and the upper end of the test object (6) is clamped and fixed by rotating the screw (11).

8. A tensile testing device according to claim 7, wherein, A void (10) is provided through the side wall of the lower slot. A screw (11) is fitted in the void (10) for fixing the test object (6). The void (10) is provided with internal threads, and the lower end of the test object (6) is clamped and fixed by rotating the screw (11).

9. The tensile testing device according to claim 8, characterized in that, An adjusting screw is provided at the bottom of the lower clamp (7). A screw sleeve is provided on the frame-shaped structure at the position below the adjusting screw. The adjusting screw is connected to the screw sleeve in a matching manner. A knob is provided at the bottom of the adjusting screw. By rotating the knob, the adjusting screw is controlled to rotate in the screw sleeve, thereby realizing the up and down movement of the lower clamp (7).

10. A tensile testing device according to claim 9, wherein, A baffle is provided at the top of the upper fixture (5), and the distance measuring device (8) is provided above the baffle. The distance measuring device (8) continuously detects the distance between the distance measuring device (8) and the baffle.

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