Pulse fatigue testing device and method

Abstract

The present invention discloses a pulse fatigue testing device and method in the field of wire material testing instrument technology, aiming to solve the problems of existing experimental devices and methods, which are not only complex in steps, long in cycle, low in efficiency, but also high in cost. The device comprises a driving mechanism, a bending roller mechanism, and a lever mechanism; the bending roller mechanism is arranged between the driving mechanism and the lever mechanism; the lever scale and the counterweight scale in the lever mechanism are pre-adjusted, and the bending roller assembly of the sample to be tested is passed around the bending roller mechanism, the left end of the sample to be tested is fixed to the first bracket in the lever mechanism, and the right end is fixed to the fixing member on the right side of the bending roller mechanism; the driving mechanism drives the bending roller mechanism to perform horizontal reciprocating motion, and drives the connecting rod and the counterweight wheel in the lever mechanism to reciprocate relative to the lever, so as to perform pulse fatigue testing on the sample to be tested; the present invention is suitable for pulse fatigue testing of steel wires and cords, and can simplify experimental steps, shorten experimental cycles, and reduce the overall experimental cost.

Description

Technical Field

[0001] The invention relates to a pulse fatigue testing device and method, belonging to the technical field of wire material testing instruments. Background Art

[0002] A hose is a tubular rubber product used to transport gases, liquids, slurries, or granular materials, such as hydraulic hoses and high-pressure hoses. The hose's structure primarily consists of rubber and a skewer. The steel wire used in the hose skewer is called hose wire. A hose in which the single layers of steel wire are woven into a web in an interlaced pattern is called a braided hose; a hose in which the single layers of steel wire are wound in the same direction into a tube is called a spiral hose.

[0003] During use, hoses are primarily subjected to periodic, fluctuating hydraulic loads, known as pulse pressure. Therefore, the pulse fatigue performance of the hose wire is crucial for the hose's skeleton material. The current method for testing hose wire pulse fatigue involves fabricating the tested wire into a finished hose, placing it in a pulse fatigue testing machine, filling it with hydraulic oil, and then applying the pulsed hydraulic pressure. This testing method, using a pulse fatigue testing machine, is not only complex, time-consuming, inefficient, and costly.

[0004] The information disclosed in this background section is only intended to enhance understanding of the overall background of the invention and should not be considered as an admission or any form of suggestion that the information constitutes the prior art already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a pulse fatigue testing device, which uses a driving mechanism to drive the roller mechanism to reciprocate, so that the connecting rod drives the counterweight wheel to move synchronously on the lever groove. As the counterweight wheel moves, the relative distance between the counterweight and the second bracket changes periodically, and the counterweight applies a periodic force, i.e., a pulse pressure, to the sample to be tested through the lever; the bending roller group can cause the sample to be tested to produce bending deformation, simulating the bending stress of the hose steel wire (sample to be tested), so as to apply the lever theorem and realize the pulse fatigue performance testing of the hose steel wire based on the wire material through a simple mechanical structure.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0007] In one aspect, the present invention provides a pulse fatigue testing device, comprising a lever mechanism, a bending roller mechanism, and a driving mechanism, which are sequentially arranged on a machine tool from left to right; the bending roller mechanism comprises a roller bracket and a bending roller assembly arranged on the roller bracket; the lever mechanism comprises a lever, a connecting rod, an adjustment seat, a first bracket, and a second bracket; the adjustment seat is provided with a lever scale; the connecting rod is provided with a counterweight scale;

[0008] The first bracket is fixed to the machine tool and is used to limit the lever to move up and down within a set range; the top of the second bracket serves as the fulcrum of the lever, enabling the lever to rotate around the second bracket; the bottom end of the second bracket is adjustably connected to the adjustment seat, so that the second bracket can be moved and adjusted with reference to the lever scale; the counterweight end of the connecting rod is provided with a counterweight wheel, and the counterweight wheel rolls in the lever groove of the lever; the connecting end of the connecting rod is adjustably connected to the roller bracket, so that the roller bracket can be moved and adjusted with reference to the counterweight scale;

[0009] The left end of the sample to be tested is fixed in the fixing hole of the lever, and the right end is fixed to the fixing piece on the right side of the bending roller mechanism; the driving mechanism drives the bending roller mechanism to perform horizontal reciprocating motion, and drives the connecting rod and the counterweight wheel to perform horizontal reciprocating motion relative to the lever.

[0010] Furthermore, the bending roller group includes at least three bending rollers; the bending rollers are distributed on the roller bracket at intervals above and below; and the sample to be tested is fixed after passing around each bending roller in turn.

[0011] Furthermore, a fixed pulley is rotatably connected to the first bracket; the center of the fixed pulley is on the same horizontal line as the center of the curved roller distributed below the roller bracket; the left end of the sample to be tested passes around the fixed pulley and is fixed in the fixing hole.

[0012] Furthermore, the first bracket has an open displacement slot and two limit holes; one end of the lever is placed in the displacement slot, and the limit pin passes through the limit hole and is connected to the lever, so that the lever moves up and down relative to the displacement slot; a spring is installed between the lever and the displacement slot.

[0013] Furthermore, it also includes a first limiting bolt; a first sliding groove is provided at the bottom end of the second bracket; the adjustment seat is adapted to the first sliding groove, so that the second bracket is displacement-adjusted relative to the adjustment seat with reference to the lever scale, and the first limiting bolt passes through the second bracket and rests against the adjustment seat to limit the displacement.

[0014] Furthermore, a guide wheel is installed at the top end of the second bracket; an open assembly groove is provided on the outer periphery of the guide wheel, and the lever part is placed in the assembly groove and rotates relative to the assembly groove during the experiment.

[0015] Furthermore, it also includes a second limiting bolt and an assembly block; the assembly block is rotatably connected to the roller bracket and can rotate freely around the roller bracket; the connecting rod passes through the second slide groove on the assembly block, so that the roller bracket is adjusted in displacement relative to the connecting rod with reference to the counterweight scale, and the second limiting bolt passes through the assembly block and abuts against the connecting rod to limit the displacement.

[0016] Furthermore, the driving mechanism includes a motor, a transmission gear and a gear transmission rod; the motor is connected to the transmission gear for driving the transmission gear to rotate; the rack on the gear transmission rod is engaged with the transmission gear, and one end of the gear transmission rod is fixedly connected to the roller bracket; when the motor drives the transmission gear to rotate forward and reverse, the gear transmission rod causes the roller bracket to move back and forth in a straight line.

[0017] In another aspect, the present invention provides a pulse fatigue testing method, wherein the testing method using any of the above-described pulse fatigue testing devices comprises:

[0018] Select and record the appropriate motor speed, gear transmission rod movement range, lever and counterweight;

[0019] According to the pulse force required by the experiment, the range of the pulse force applied to the sample is:

[0020]

[0021] Adjust the first limit bolt and the second limit bolt to set the corresponding lever scale and counterweight scale;

[0022] Apply oil to the sample to be tested, or cover the surface of the bending roller with a layer of rubber sheet;

[0023] Fix one end of the sample to be tested on the fixing piece, and pass the other end around the bending roller set and fixed pulley, and fix it on the fixing hole;

[0024] Start the motor and record the number of cycles until the sample to be tested breaks.

[0025] Furthermore, calculating the pulse force of the sample to be tested specifically includes:

[0026] The relationship between the pulse force and time of the sample to be tested is:

[0027]

[0028] Where P is the movable range of the gear transmission rod; a is the adjusted lever scale value; b is the adjusted counterweight scale value; M is the weight of the counterweight; F is the pulse force exerted on the sample to be tested; T is the time it takes for the motor to rotate forward / reverse once, and t is the pause time during the motor switching process.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a pulse fatigue testing device, which can drive the roller mechanism to reciprocate by operating the driving mechanism, so that the connecting rod drives the counterweight wheel to move synchronously on the lever groove. As the counterweight wheel moves, the relative distance between the counterweight and the second bracket changes periodically, and the counterweight applies a periodic force, i.e., a pulse pressure, to the sample to be tested through the lever; the bending roller group can cause the sample to be tested to produce bending deformation, simulating the bending stress of the hose steel wire (sample to be tested), so as to apply the lever theorem and realize the pulse fatigue performance testing of the hose steel wire based on the wire material through a simple mechanical structure; the device uses a lever to provide a pulse force, and by adjusting the two scales of the lever scale and the counterweight scale, the pulse force in any range can be achieved, which can meet the experimental requirements under any conditions.

[0031] The present invention provides a pulse fatigue testing method, which can be combined with the pulse fatigue testing device provided by the present application to measure the pulse fatigue of a sample to be tested. Compared with the existing implementation method, the test cost is reduced and the test efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a pulse fatigue testing device provided in Example 1;

[0033] Figure 2 for Figure 1 A front view of the connection between the middle lever and the first support structure;

[0034] Figure 3 for Figure 1 A top view of the connection between the middle lever and the first support structure;

[0035] Figure 4 for Figure 1 Schematic diagram of parameter selection for the force on the middle lever;

[0036] Figure 5 for Figure 1 Schematic diagram of the connection between the middle counterweight wheel and the lever;

[0037] Figure 6 Schematic diagram of the adjustment of the second bracket and the adjustment seat;

[0038] Figure 7 Schematic diagram of the adjustment of the connecting rod and the roller bracket;

[0039] Figure 8 It is a pulse wave schematic diagram;

[0040] Figure 9 A schematic flow chart of a pulse fatigue testing method provided in Example 2;

[0041] In the figure: 1. Motor; 2. Transmission gear; 3. Gear transmission rod; 4. Rack; 5. Rack guide; 6. Bending roller assembly; 7. Roller bracket; 8. Roller guide; 9. Fixing piece; 10. Connecting rod; 11. Adjusting seat; 12. Fixed pulley; 13. Lever; 14. First bracket; 15. Counterweight wheel; 16. Counterweight; 17. Sample to be tested; 18. Second bracket; 19. Guide wheel; 20. Lever scale; 21. Counterweight scale; 22. Fixing hole; 23. Spring; 24. Counterweight rod; 25. Base; 26. Support rod; 27. Limit pin; 28. Displacement slot; 29. ​​Limit hole; 30. First limiting bolt; 31. First slide slot; 32. Second limiting bolt; 33. Assembly block; 34. Second slide slot; 35. Lever groove; 36. Channel. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying 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 limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0044] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] Example 1:

[0046] See Figures 1 to 7As shown, the present invention provides a pulse fatigue testing device comprising a drive mechanism, a bending roller mechanism, and a lever mechanism. The bending roller mechanism is mounted between the drive mechanism and the lever mechanism, and can be installed on the same machine tool according to this assembly position relationship. The bending roller mechanism includes an alarm roller bracket 7 and a bending roller assembly 6, which is mounted on the roller bracket 7.

[0047] like Figure 1 As shown, the lever mechanism includes a lever 13, a connecting rod 10, an adjustment seat 11, a first bracket 14, and a second bracket 18. A lever groove 35 is defined in the lever 13, and a passage 36 for the movement of the counterweight rod 24 is defined between the lever groove 35 and the lever 13. A counterweight wheel 15 is provided on the counterweight end of the connecting rod 10. This counterweight wheel 15 is positioned within the lever groove 35 provided on the upper end surface of the lever 13. One end of the counterweight rod 24 is fixed to the crossbeam of the counterweight wheel, and the other end passes through the passage 36 to be mounted on the counterweight 16.

[0048] like Figure 6 and Figure 7 As shown, a lever scale 20 is provided on the adjustment seat 11, and a counterweight scale 21 is provided on the connecting rod 10. The first bracket 14 is vertically mounted on the machine tool, and the first bracket 14 is used to limit the lever 13 from moving up and down within a set range. The top end of the second bracket 18 serves as the fulcrum of the lever 13, allowing the lever 13 to rotate around the second bracket 18. The bottom end of the second bracket 18 is adjustably connected to the adjustment seat 11, allowing the second bracket 18 to be moved and adjusted with reference to the lever scale 20 on the adjustment seat 11. The connecting end of the connecting rod 10 is adjustably connected to the roller bracket 7, allowing the roller bracket 7 to be moved and adjusted with reference to the counterweight scale 21 on the connecting rod 10.

[0049] When testing, if Figure 1 , the sample to be tested 17 is passed around the bending roller set 6 of the bending roller mechanism, and the left end of the sample to be tested 17 is fixed in the fixing hole 22 provided on the lever 13, and the right end of the sample to be tested 17 is fixed on the fixing part 9 on the right side of the bending roller mechanism. The operating driving mechanism drives the bending roller mechanism to perform reciprocating motion, and the roller bracket 7 drives the connecting rod 10 to make the counterweight wheel 15 synchronously reciprocate in the lever groove 35. As the counterweight wheel 15 moves, the relative distance between the counterweight 16 on the counterweight wheel and the first bracket 14 changes periodically, and the counterweight 16 applies a periodic force, i.e., a pulse pressure, to the sample to be tested 17 through the lever 13. At the same time, the bending roller set 6 can cause the sample to be tested 17 to produce bending deformation, simulating the bending stress of the hose steel wire, so as to apply the lever 13 theorem and realize the pulse fatigue performance test of the hose steel wire based on the wire material through a simple mechanical structure. Specifically, the roller mechanism is connected to the machine tool via the roller guide rail 8 . When the driving mechanism drives the roller bracket 7 to move, the entire roller mechanism can reciprocate along the roller guide rail 8 .

[0050] Optionally, the bending roller assembly 6 includes at least three bending rollers. The bending rollers are spaced apart on the roller bracket 7. A fixed pulley 12 is provided on the first bracket 14 for rotation; the center of the fixed pulley 12 is on the same horizontal line as the center of the bending roller distributed relatively below the roller bracket 7. The fixing hole 22 is specifically provided on the lever 13 at the intersection of the axis of the lever 13 in a horizontal state and the perpendicular line passing through the center of the fixed pulley 12. During the experiment, the left end of the sample to be tested passes around the fixed pulley 12 and is fixed in the fixing hole 22 of the lever 13.

[0051] Specifically, such as Figure 1 The roller bracket 7 includes a support rod 26 connected to a base 25. The bending roller assembly 6 utilizes three bending rollers. One bending roller is mounted on the support rod 26 via a roller shaft, while the other two bending rollers are symmetrically mounted on the base 25. In other words, the three roller shafts are distributed in a triangular shape on the roller bracket 7. The center of the fixed pulley 12 is aligned with the center of the bending rollers on the base 25. During testing, the sample is passed around the three roller shafts in sequence, and then secured at both ends in the fixing holes 22 and the fixing member 9.

[0052] Optional, such as Figure 2 and Figure 3 As shown, the first bracket 14 is provided with an open displacement slot 28 and two limiting holes 29. Limiting holes 29 are provided on the first bracket 14 to enable the limiting pin 27 to move vertically. One end of the spring 23 is screwed into the displacement slot 28, and the other end is also screwed into the portion of the lever 13 mounted in the displacement slot 28. To ensure that the lever 13 floats only in the vertical direction relative to the first bracket 14 after being subjected to left and right forces, two limiting pins 27 are connected to the lever 13 through two limiting blocks, allowing the lever 13 to float up and down along the direction of the limiting holes 29.

[0053] Optional, combined Figure 1 and Figure 6 The lever mechanism also includes a first limiting bolt 30. An open first slide groove 31 is provided at the bottom end of the first bracket 14, so that the adjustment seat 11 is adapted to the first slide groove 31. The second bracket 18 refers to the lever scale 20 on the adjustment seat 11 and performs displacement adjustment relative to the adjustment seat 11. After adjustment, the first limiting bolt 30 is screwed through the second bracket 18 and rests on the adjustment seat 11 for limited displacement to prevent the second bracket 18 from moving relative to the adjustment seat 11 and affecting the subsequent detection accuracy. Before the experiment begins, adjust the distance between the second bracket 18 and the first bracket 14, and the lever scale 20 increases in the left direction. The zero scale is the intersection of the adjustment seat 11 and the vertical extension line of the fixing hole 22.

[0054] Combine Figure 1 and Figure 4As shown, a guide wheel 19 is rotatably mounted on the top of the second bracket 18. A circle of open mounting grooves is defined around the outer circumference of the guide wheel 19. Lever 13 is partially positioned within the mounting grooves on the guide wheel 19, using the guide wheel 19 as a fulcrum. During the experiment, the lever was subjected to a force that caused it to rotate slightly around the mounting grooves in the guide wheel 19.

[0055] Optional, combined Figure 1 and Figure 7 The lever mechanism also includes a second limiting bolt 32 and an assembly block 33. The assembly block 33 is mounted on the roller bracket 7 and can rotate freely around the roller bracket 7. A second sliding groove 34 is provided on the assembly block 33, and the connecting rod 10 passes through the second sliding groove 34, so that the roller bracket 7 can be displaced relative to the connecting rod 10 with reference to the counterweight scale 21 on the connecting rod 10. After adjustment, the second limiting bolt 32 is screwed into the assembly block 33 and abuts against the connecting rod 10 for limited displacement, preventing the connecting rod 10 from moving relative to the roller bracket 7 and affecting the subsequent detection accuracy. The counterweight scale 21 increases in the rightward direction. The counterweight scale 21 is defined as when the rack drive rod 3 moves to the far right and the counterweight wheel 15 is moved to the top of the second bracket 18, the counterweight scale 21 is equal to the lever scale 20. That is, the counterweight scale 21 is the distance between the rightmost side that the center line of the counterweight wheel 15 can reach and the vertical extension line of the fixing hole 22.

[0056] Specifically, the fixing member 9 on the right side of the roller mechanism is an inverted T-shaped fixing block, around which the right end of the sample 17 to be tested is wrapped and secured. A fixed pulley 12 is mounted on the first bracket 14 via an axle, such that the center of the fixed pulley 12 is aligned with the centers of the two curved rollers symmetrically mounted on the base 25 of the roller bracket 7. A fixing hole 22 is provided on the first bracket 14 above the fixed pulley 12 for securing the left end of the sample 17 to be tested.

[0057] Optional, such as Figure 1 The driving mechanism includes a motor 1, a transmission gear 2 and a gear transmission rod 3. The gear transmission rod 3 is slidably connected to the machine tool through a rack guide 5. The motor 1 is connected to the transmission gear 2 and is used to drive the transmission gear 2 to rotate. A gear transmission rod 3 is provided under the transmission gear 2. A rack 4 is installed on the gear transmission rod 3 to engage with the transmission gear 2, and one end of the gear transmission rod 3 is fixed to the roller bracket 7. The motor 1 drives the transmission gear 2 to rotate forward and backward, so that the gear transmission rod 3 moves telescopically and drives the roller bracket 7 to move back and forth in a straight line. The moving range of the gear transmission rod 3 is controlled by the number of rotations of the motor 1. The rotation direction of the motor 1 changes twice within one pulse cycle, namely forward and reverse. The number of rotations of the motor 1 can be adjusted, and the number of forward and reverse rotations remains consistent. This device uses a transmission gear 2 as a transmission system, refer to Figure 8As shown in the pulse wave diagram, one pulse cycle is divided into pressurization section, high pressure section, pressure relief section, and low pressure section. The pressure of the high pressure section and the low pressure section remains unchanged. This waveform conforms to the working pressure state of the hose and can effectively and accurately verify the performance of the steel wire in the finished product state.

[0058] Example 2:

[0059] See Figure 8 and Figure 9 As shown, this embodiment provides a pulse fatigue test method, which includes using the pulse fatigue test device described in any one of the above-mentioned embodiments. The test method specifically includes:

[0060] Step 1: Select the appropriate motor 1 speed, gear transmission rod 3 movement range, lever 13 and counterweight 16, and record them.

[0061] Step 2: Based on the pulse force required for the experiment, use formula (1) to measure the range of the pulse force applied to the sample:

[0062]

[0063] The first limiting bolt 30 and the second limiting bolt 32 are adjusted to set the corresponding lever scale 20 and counterweight scale 21 .

[0064] Step 3: Apply oil to the sample 17 to be tested, or coat the surface of the bending roller with a layer of rubber sheet.

[0065] Step 4: Fix one end of the sample 17 to be tested on the fixing member 9 , and pass the other end around the bending roller set and the fixed pulley 12 , and fix it on the fixing hole 22 .

[0066] Step 5: Start the motor 1 and record the number of cycles until the sample 17 to be tested breaks.

[0067] Calculating the pulse force of the sample to be tested 17 specifically includes:

[0068] The relationship between the pulse force and time of the sample 17 to be tested is:

[0069]

[0070] Where P is the movable range of the gear transmission rod 3; a is the adjusted lever scale value 20; b is the adjusted counterweight scale value 21; M is the weight of the counterweight 16; F is the pulse force applied to the sample 17; T is the time it takes for the motor 1 to rotate forward (or reverse) once, and t is the pause time during the motor switching process. The length of t is 0 to 0.8 seconds.

[0071] Test experiment 1:

[0072] Test sample 17 is a 0.25 mm diameter hose wire. The bending roller has a diameter of 30 mm. The range of motion of gear drive lever 3 is 100 mm. Lever scale 20 is adjusted to 10, and counterweight scale 21 is adjusted to 10. Lever 13 is 200 mm long, and counterweight 16 weighs 5 N. According to formula (1), the pulse force range is 0 to 50 N. Motor 1 operates at a switching frequency of 30 cycles / min, with a pause time of 0.5 s. The sample did not break after 10,000 cycles.

[0073] Test experiment 2:

[0074] Test sample 17 is a 0.25 mm diameter hose wire. The bending roller has a diameter of 30 mm. The range of motion of gear drive lever 3 is 100 mm. Lever scale 20 is adjusted to 10, and counterweight scale 21 is adjusted to 10. Lever 13 is 200 mm long, and counterweight 16 weighs 5 N. According to formula (1), the pulse force range is 0 to 50 N. Motor 1 operates at a switching frequency of 90 cycles / min, with a pause time of 0.2 s. The sample did not break after 10,000 cycles.

[0075] Test experiment 3:

[0076] The sample to be tested, 17, was a 0.25 mm diameter hose wire. The bending roller had a diameter of 30 mm. The range of motion of the gear transmission rod, 3, was 100 mm. The lever scale, 20, was adjusted to 10, and the counterweight scale, 21, was adjusted to 10. The length of the lever, 13, was 200 mm. The weight of the counterweight, 16, was 8 N. According to formula (1), the pulse force range was 0 to 80 N. The switching frequency of the motor, 1, was 90 cycles / min, with a pause time of 0.2 s. The sample broke after 4205 cycles, and the fracture surface was a fatigue fracture.

[0077] Test experiment 4:

[0078] The sample to be tested, 17, was a 0.25 mm diameter hose wire. The bending roller had a diameter of 30 mm. The range of motion of the gear transmission rod, 3, was 100 mm. The lever scale, 2020, was adjusted to 10, and the counterweight scale, 21, was adjusted to 40. The length of the lever, 13, was 200 mm. The weight of the counterweight, 16, was 5 N. According to formula (1), the pulse force range was 15 to 85 N. The switching frequency of the motor, 1, was 90 cycles / min, with a pause time of 0.2 s. The sample broke after 3836 cycles, and the fracture surface was a fatigue fracture.

[0079] Test experiment 5:

[0080] The sample to be tested, 17, is a 0.25 mm diameter hose wire. The bending roller has a diameter of 30 mm. The range of motion of the gear transmission rod 3 is 100 mm. The lever scale 2020 is adjusted to 10, and the counterweight scale 21 is adjusted to 40. The length of the lever 13 is 200 mm, and the weight of the counterweight 16 is 5 N. According to formula (1), the pulse force range is 15 to 85 N. The switching frequency of the motor 1 is 90 times / min, and the pause time is 0.2 s. The sample did not break after 10,000 cycles.

[0081] Test experiment 6:

[0082] The sample to be tested, 17, is a 0.7 mm diameter hose wire. The bending roller has a diameter of 30 mm. The range of motion of the gear transmission rod 3 is 100 mm. The lever scale 2020 is adjusted to 5, and the counterweight scale 21 is adjusted to 10. The length of the lever 13 is 200 mm, and the weight of the counterweight 16 is 20 N. According to formula (1), the pulse force range is 20 to 420 N. The switching frequency of the motor 1 is 90 cycles / min, and the pause time is 0.2 s. The sample did not break after 10,000 cycles.

[0083] Test experiment 7:

[0084] The sample to be tested, 17, is a 0.7 mm diameter hose wire. The bending roller has a diameter of 30 mm. The range of motion of the gear transmission rod, 3, is 150 mm. The lever scale, 2020, is adjusted to 5, and the counterweight scale, 21, is adjusted to 10. The length of the lever, 13, is 200 mm, and the weight of the counterweight, 16, is 20 N. According to formula (1), the pulse force range is 20 to 620 N. The switching frequency of the motor, 1, is 90 cycles / min, with a pause time of 0.2 s. The sample breaks after 6029 cycles, and the fracture is a fatigue fracture.

[0085] Test experiment 8:

[0086] The sample to be tested, 17, was a 0.99 mm Φ steel cord. The bending roller had a diameter of 30 mm. The range of motion of the gear transmission lever, 3, was 300 mm. The lever scale, 2020, was adjusted to 10, and the counterweight scale, 21, was adjusted to 10. The length of lever, 13, was 500 mm, and the weight of counterweight, 16, was 20 N. According to formula (1), the pulse force range was 0 to 600 N. The switching frequency of motor, 1, was 90 cycles / min, with a pause time of 0.2 s. The sample did not break after 10,000 cycles.

[0087] Test experiment 9:

[0088] The sample to be tested, 17, was a 0.99 mm Φ steel cord. The bending roller had a diameter of 30 mm. The range of motion of the gear transmission lever, 3, was 300 mm. The lever scale, 2020, was adjusted to 5, and the counterweight scale, 21, was adjusted to 10. The length of lever, 13, was 500 mm, and the weight of counterweight, 16, was 20 N. According to formula (1), the pulse force range was 20 to 1220 N. The switching frequency of motor 1 was 90 cycles / min, with a pause time of 0.2 s. The sample broke after 5291 cycles, and the fracture surface was a fatigue fracture.

[0089] Test experiment 10:

[0090] The sample to be tested, 17, was a 0.99 mm Φ steel cord. The bending roller had a diameter of 150 mm. The range of motion of the gear transmission lever, 3, was 300 mm. The lever scale, 2020, was adjusted to 5, and the counterweight scale, 21, was adjusted to 10. The length of lever, 13, was 500 mm, and the weight of counterweight, 16, was 20 N. According to formula (1), the pulse force range was 20 to 1220 N. The switching frequency of motor 1 was 90 cycles / min, with a pause time of 0.2 s. The sample broke after 6344 cycles, and the fracture surface was a fatigue fracture.

[0091] 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pulse fatigue testing device, characterized in that: The machine tool comprises a lever mechanism, a bending roller mechanism and a driving mechanism, which are sequentially arranged on the machine tool from left to right; the bending roller mechanism comprises a roller bracket and a bending roller assembly arranged on the roller bracket; the lever mechanism comprises a lever, a connecting rod, an adjustment seat, a first bracket and a second bracket; the adjustment seat is provided with a lever scale; the connecting rod is provided with a counterweight scale; The first bracket is fixed to the machine tool and is used to limit the lever to move up and down within a set range; The top end of the second bracket serves as the fulcrum of the lever, enabling the lever to rotate around the second bracket; the bottom end of the second bracket is adjustably connected to the adjustment seat, so that the second bracket can be moved and adjusted with reference to the lever scale; the counterweight end of the connecting rod is provided with a counterweight wheel, and the counterweight wheel rolls in the lever groove of the lever; the connecting end of the connecting rod is adjustably connected to the roller bracket, so that the roller bracket can be moved and adjusted with reference to the counterweight scale; The left end of the sample to be tested is fixed in the fixing hole of the lever, and the right end is fixed to the fixing piece on the right side of the bending roller mechanism; the driving mechanism drives the bending roller mechanism to perform horizontal reciprocating motion, thereby driving the connecting rod and the counterweight wheel to perform horizontal reciprocating motion relative to the lever; The bending roller assembly includes at least three bending rollers; the bending rollers are spaced apart and distributed on the roller bracket; the sample to be tested passes around each bending roller in turn and is then fixed; A fixed pulley is rotatably connected to the first bracket; the center of the fixed pulley is on the same horizontal line as the center of the bending roller distributed below the roller bracket; the left end of the sample to be tested passes around the fixed pulley and is fixed in the fixing hole; The driving mechanism includes a motor, a transmission gear and a gear transmission rod; the motor is connected to the transmission gear to drive the transmission gear to rotate; the rack on the gear transmission rod is engaged with the transmission gear, and one end of the gear transmission rod is fixedly connected to the roller bracket; when the motor drives the transmission gear to rotate forward and reverse, the gear transmission rod causes the roller bracket to move back and forth in a straight line.

2. The pulse fatigue testing device according to claim 1, characterized in that: The first bracket has an open displacement slot and two limiting holes; one end of the lever is placed in the displacement slot, and a limiting pin passes through the limiting hole and is connected to the lever, so that the lever moves up and down relative to the displacement slot; a spring is installed between the lever and the displacement slot.

3. The pulse fatigue testing device according to claim 1, characterized in that: It also includes a first limiting bolt; a first sliding groove is provided at the bottom end of the second bracket; the adjustment seat is adapted to the first sliding groove, so that the second bracket is adjusted relative to the adjustment seat with reference to the lever scale, and the first limiting bolt passes through the second bracket and rests against the adjustment seat to limit the displacement.

4. The pulse fatigue testing device according to claim 2, characterized in that: A guide wheel is installed at the top end of the second bracket; an open assembly groove is provided on the outer periphery of the guide wheel, and the lever part is placed in the assembly groove and rotates relative to the assembly groove during the experiment.

5. The pulse fatigue testing device according to claim 1, characterized in that: It also includes a second limiting bolt and an assembly block; the assembly block is rotatably connected to the roller bracket and can rotate freely around the roller bracket; the connecting rod passes through the second sliding groove on the assembly block, so that the roller bracket is adjusted in displacement relative to the connecting rod with reference to the counterweight scale, and the second limiting bolt passes through the assembly block and abuts against the connecting rod to limit the displacement.

6. A pulse fatigue test method, characterized in that: A testing method using the pulse fatigue testing device according to any one of claims 1 to 5 comprises: Select and record the appropriate motor speed, gear transmission rod movement range, lever and counterweight; According to the pulse force required by the experiment, the range of the pulse force applied to the sample is: （1） Adjust the first limit bolt and the second limit bolt to set the corresponding lever scale and counterweight scale; Apply oil to the sample to be tested, or cover the surface of the bending roller with a layer of rubber sheet; Fix one end of the sample to be tested on the fixing piece, and pass the other end around the bending roller set and fixed pulley, and fix it on the fixing hole; Start the motor and record the number of cycles until the sample to be tested breaks; Where P is the movable range of the gear transmission rod; a is the adjusted lever scale value; b is the adjusted counterweight scale value; M is the weight of the counterweight; and F is the pulse force applied to the sample to be tested.

7. The pulse fatigue testing method according to claim 6, characterized in that: Calculating the pulse force of the sample to be tested specifically includes: The relationship between the pulse force and time of the sample to be tested is: （2） Where P is the movable range of the gear transmission rod; a is the adjusted lever scale value; b is the adjusted counterweight scale value; M is the weight of the counterweight; F is the pulse force exerted on the sample to be tested; T is the time it takes for the motor to rotate forward / reverse once, and t is the pause time during the motor switching process.

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