Method and device for testing frictional wear of cable

Abstract

The invention discloses a cable friction wear experiment method and device, and relates to the technical field of friction wear experiments. The method comprises the steps of working condition parameter calculation, pulley matching machining, experimental system construction, dynamic parameter adjustment, traction force loading, friction force monitoring and abrasion performance evaluation, friction force is calculated by accurately reproducing actual working condition parameters and combining pressure and torque sensor data, and the performance is evaluated from the abrasion area and the abrasion rate. The device comprises an experiment table, a hydraulic loading assembly, a sliding assembly, a fixed assembly and a replaceable pulley block module, and parameters such as pulley spacing and rotating speed can be dynamically adjusted. The problems that the difference between simulation and reality is large, and friction force is difficult to obtain are solved, the experiment reliability is improved, and support is provided for cable abrasion mechanism research.

Description

Technical Field

[0001] This invention relates to the field of friction and wear testing technology, specifically to an experimental method and special apparatus for simulating the friction and wear process between cables and pulleys / winches, applicable to the study of cable wear performance in fields such as construction hoisting, vehicle traction, marine mooring, and aircraft carrier arresting cables. Background Technology

[0002] As a critical load-bearing component in industrial and military fields, cables are widely used in construction hoisting, vehicle towing, marine mooring, and aircraft carrier arresting gear. Their working environment is open and complex, making them susceptible to factors such as temperature and humidity changes, salt spray corrosion, and sunlight exposure, leading to material aging, structural deformation, and performance degradation. More importantly, during cable retrieval / release, continuous friction and wear between the cable and pulleys / winches can cause localized breakage and even alter the overall structural strength. Because cables bear immense traction during operation, if performance failure due to wear is not detected in time, it can easily lead to major safety accidents.

[0003] Currently, cable maintenance in China is still limited to periodic inspections and visual and detail checks, with little in-depth research into the influencing factors and mechanisms of aging and wear leading to performance failure. Experimental simulation is an important method to reveal the wear patterns of cables, but field experiments have inherent drawbacks such as poor controllability, high cost, and long cycles. Therefore, laboratory simulation has become the mainstream technical approach.

[0004] However, cable friction and wear have unique characteristics: the wear mainly occurs between the cable and pulleys / winches, and the two pairs of pulleys around which the cable is wound do not directly contact each other. This means that the clamping force output by the hydraulic cylinder / motor cannot directly act on the cable, making it difficult to directly measure the frictional force between the cable and the pulleys. Existing research mostly relies on simulation analysis of cable stress, but the simulation results deviate somewhat from the actual field conditions. Therefore, there is an urgent need to propose an experimental method that can accurately simulate the cable friction and wear process, and to design a dedicated experimental device based on this method. This is a key problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for testing cable friction and wear, so as to study the influence and law of various working parameters on the friction and wear performance of cables, and solve the problems of large gap between existing simulation results and actual results and difficulty in obtaining friction force.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows: On one hand, this invention discloses a method for testing cable friction and wear, which mainly includes the following steps: (1) Calculation of working parameters: Obtain the weight of the dragged object, the traction speed and the actual working condition pulley block model, and calculate the traction force, wrap angle and slack coefficient when the cable is wound and released. (2) Pulley matching and machining: Select multiple sets of pulleys with the same diameter ratio as the actual working condition pulley set, and the diameter of the large pulley in different pulley sets is different; machine the selected pulleys into a cylindrical structure with groove width and groove depth consistent with the actual working condition pulley; (3) Experimental system construction: Install the pulley group of selected diameter on the two rotating shafts, so that the two pulley shafts are coplanar and the distance between them is adjustable; wrap the cable around the pulleys to form surface contact; (4) Dynamic parameter adjustment: Adjust the cable slack coefficient by adjusting the rotation speed of the two shafts and the center distance of the two pulleys to achieve the calculated value in step (1); adjust the wrap angle by adjusting the center distance of the two pulleys by moving the slide rail platform to achieve the calculated value in step (1); adjust the pulley rotation speed according to the traction speed of the dragged object; (5) Traction loading: The cable is tensioned by pushing the slide rail platform with a hydraulic cylinder, and the traction force calculated in step (1) is applied. (6) Friction detection: Data is collected by pressure and torque sensors, and the friction between the cable and pulley is calculated by combining the wrap angle.

[0007] Furthermore, in step (4), the slack cable coefficient k is calculated using the following formula: In the formula, n1 is the rotational speed of the small pulley when releasing the cable and the rotational speed of the large pulley when retracting the cable; n2 is the rotational speed of the large pulley when releasing the cable and the rotational speed of the small pulley when retracting the cable; d d1 Let d be the diameter of the smaller pulley. d2 Let θ be the diameter of the large pulley, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

[0008] Furthermore, in step (4), the wrap angle is calculated using the following formula: In the formula: d d1 Let d be the diameter of the smaller pulley. d2 Let θ be the diameter of the large pulley, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

[0009] Furthermore, in step (6), the frictional force f between the cable and the pulley is calculated as follows: In the formula, α represents the wrap angle of the cable, F0 is the cable traction force, and F is the cable tension force.

[0010] Furthermore, in step (7), the cross-sectional area and mass of the cable are measured before and after the experiment. The cable wear area is the ratio of the area removed from the cross section to the cross-sectional area before the experiment, and the cable wear rate is the ratio of the cable mass loss after the experiment to the unit distance traveled.

[0011] On the other hand, the present invention discloses a cable friction and wear test apparatus, comprising: Experimental platform; A hydraulic loading assembly, mounted on an experimental platform, includes a hydraulic cylinder and a pressure sensor, wherein the pressure sensor is fixed to the end of the piston rod of the hydraulic cylinder. A sliding assembly, mounted on a slide rail of the experimental platform and linked with a hydraulic loading assembly, includes a slide rail platform and a first drive unit and a first axle box mounted thereon. The first drive unit includes a first motor, a coupling, and a torque sensor. The first motor is sequentially driven and connected to the first axle box via the coupling and the torque sensor. The end of the first axle box is provided with a first detachable pulley interface. A fixed assembly, fixed to the experimental platform and disposed opposite to the sliding assembly, includes a second motor and a second axle box. The second motor is driven and connected to the second axle box via a belt. The end of the second axle box is provided with a second detachable pulley interface. A replaceable pulley block module includes at least one set of pulley blocks; each set of pulley blocks includes matching small pulleys and large pulleys, wherein the small pulleys or large pulleys are installed in a first detachable pulley interface, and the large pulleys or small pulleys are installed in a second detachable pulley interface; the small pulleys and large pulleys form a cable friction path, and the distance between them is dynamically adjusted by the displacement of the sliding component.

[0012] Furthermore, a top column is fixed to the top of the piston rod of the hydraulic cylinder.

[0013] Furthermore, the bottom of the slide rail platform is slidably connected to the slide rail on the experimental platform via a slider, and the bottom end of the slide rail platform is provided with a base that cooperates with the top column. The hydraulic cylinder pushes the slide rail platform to move in order to adjust the distance between the two pulleys.

[0014] Furthermore, an electromagnetic stop valve is provided on the slide rail platform, and the electromagnetic stop valve is installed near the slide rail to lock the position of the slider.

[0015] Beneficial effects: (1) Accurately reproduce actual friction and wear scenarios and improve experimental reliability. The pulley machining strictly follows the principle of "diameter ratio consistent with actual working conditions, groove width and groove depth the same as the pulley on site" to ensure that the contact area, contact stress distribution and actual working conditions of the cable and pulley are completely matched. By adjusting the center distance and rotation speed of the two pulleys, the error between the wrap angle and the cable slack coefficient and the calculated value of the actual working conditions is controlled within a very small range, accurately reproducing the dynamic friction state during cable winding / unwinding, and avoiding the experimental results deviating from reality due to parameter distortion.

[0016] (2) Innovative methods for calculating friction force To address the unique characteristics of cable winding pulleys not contacting each other and the inability of clamping force to directly act on the cable, a friction force calculation formula combining a pressure sensor (to collect tension force), a torque sensor (to collect shaft torque), and the wrap angle is proposed. This enables real-time detection of friction force between the cable and pulleys, solving the core problem of difficulty in directly obtaining friction force in existing technologies and providing direct data support for analyzing the correlation between friction and wear.

[0017] (3) Multi-parameter coordinated adjustment to cover the simulation requirements of complex working conditions Traction force adjustment: By pushing the slide rail platform with a hydraulic cylinder to tension the cable, different traction forces can be accurately simulated to adapt to different scenarios from light traction to heavy lifting. Motion parameter adjustment: The speed of the two motors is independently adjustable. Combined with the pulley diameter ratio, the motion state under different traction speeds can be reproduced. Cable slack coefficient adjustment: By coordinating the speed difference between the two shafts, the pulley diameter and the center distance, the cable slack coefficient can be adjusted to accurately simulate the speed mismatch phenomenon when the cable is being wound up (negative coefficient) and when the cable is being released (positive coefficient), thus meeting the wear simulation requirements of different cable winding and releasing conditions.

[0018] (4) The device structure design ensures the stability and safety of the experiment. The slide rail platform achieves smooth movement through the cooperation of the slider and the slide rail. The electromagnetic stop valve can lock the center distance of the pulley during the experiment to avoid parameter deviation due to vibration or traction force fluctuation. The hydraulic cylinder loading process adopts the "slow pressurization + zero value calibration" mode. The electromagnetic stop valve is opened before the second pressurization to effectively buffer the instantaneous impact caused by the possible breakage of the cable, protect the experimental platform from damage, and ensure the stability and safety of long-term experiments.

[0019] (5) The experimental system is flexible in construction and adaptable to testing different specifications of cables, meeting the wear test requirements of cables with different diameters and lengths; it supports the replacement of multiple sets of pulleys with different diameters. By adjusting the pulley diameter ratio, the friction and wear process between different pulley sets and cables can be simulated, improving the versatility of the device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cable friction and wear experimental device in this invention.

[0021] Figure 2 This is a schematic diagram of the slide rail platform in this invention.

[0022] In the diagram, 1. First motor, 2. Coupling, 3. Torque sensor, 4. First shaft box, 5. Small pulley, 6. Second motor, 7. Slide rail platform, 8. Top column, 9. Pressure sensor, 10. Hydraulic cylinder, 11. Large pulley, 12. Second shaft box, 13. Slider, 14. Slide rail, 15. Electromagnetic stop valve, 16. Base. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0024] In the description of this invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0025] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0026] This invention provides a method for testing cable friction and wear, such as... Figure 1 As shown, this method reproduces the friction and wear process of cables against pulleys / winches in actual operation through physical simulation and parameter matching. Its underlying logic is based on the "similarity principle," which means that by restoring key parameters in actual working conditions (such as traction force, wrap angle, cable slack coefficient, and movement speed), the friction and wear patterns in the experiment are consistent with those in the field, thereby accurately studying the cable wear mechanism. Specifically, it includes the following steps:

[0027] (1) Calculation of operating parameters

[0028] By obtaining the weight of the dragged object, the traction speed, and the actual working condition pulley block model, the traction force, wrap angle, and slack coefficient during cable winding and unwinding can be accurately calculated.

[0029] This step provides "benchmark parameters" for the entire experiment, ensuring that the experimental simulation does not deviate from the actual scenario. Among them, the traction force corresponds to the actual traction force borne by the cable, the wrap angle reflects the contact range between the cable and the pulley, and the slack coefficient reflects the speed mismatch characteristics during cable winding / unwinding. These three factors together determine the intensity and pattern of cable friction and wear, and serve as the direct basis for subsequent experimental parameter adjustments.

[0030] (2) Pulley matching machining

[0031] Select multiple sets of pulleys, ensuring their diameter ratio is the same as the actual working pulley set (the diameter of the largest pulley in different pulley sets is different), and process the pulleys into a cylindrical structure to ensure that the groove width and groove depth are consistent with the actual working pulley.

[0032] The dimensions of the pulley directly affect the contact state between the cable and the pulley. This step ensures that the wrap angle ratio of the cable during winding is the same as that under actual working conditions by maintaining a consistent diameter ratio; and by machining it into a cylindrical shape with groove width and depth consistent with the actual dimensions, the contact area and stress distribution between the cable and the pulley can be accurately reproduced, avoiding distortion of the friction and wear pattern due to pulley size deviations.

[0033] (3) Experimental system construction

[0034] Install the pulley block of the selected diameter on the two rotating shafts, ensuring that the two pulley shafts are coplanar and the spacing is adjustable; wrap the cable around the pulleys to form surface contact.

[0035] The "coplanar axis of the two pulleys" can avoid uneven force on the cable due to axis misalignment and ensure uniform friction and wear; the "adjustable spacing" provides a structural basis for subsequent dynamic adjustment of the wrap angle and slack coefficient; the "cable winding to form surface contact" completely replicates the contact form between the cable and pulley in actual work (not point / line contact), ensuring that the physical process of friction and wear is consistent with reality.

[0036] (4) Dynamic parameter adjustment

[0037] Cable slack coefficient adjustment: By changing the rotational speed of the two shafts and the center distance between the two pulleys, the cable slack coefficient is adjusted to the value calculated in step (1). The cable slack coefficient reflects the degree of mismatch between the cable and the dragging speed during cable winding / unwinding, and its calculation formula is as follows: In the formula, n1 is the rotational speed of the small pulley 5 when releasing the cable and the rotational speed of the large pulley 11 when retracting the cable; n2 is the rotational speed of the large pulley 11 when releasing the cable and the rotational speed of the small pulley 5 when retracting the cable; d d1 The small pulley has a diameter of 5, d d2 Let θ be the diameter of the large pulley 11, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

[0038] It should be noted that the "slack cable coefficient" referred to in this invention is mainly caused by the mismatch between the speed of the cable and the speed of the towed object during the cable winding / unwinding process (when winding the cable, the winding speed is less than the speed of the towed object; when unwinding the cable, the unwinding speed is greater than the speed of the towed object). Therefore, in order to simulate the "slack cable phenomenon" during the winding / unwinding process, this invention uses different speed matching between the small pulley and the large pulley to make the slack cable coefficient adjustable. Specifically, when the slack cable coefficient is less than zero, it simulates the slack cable phenomenon during the winding process, in which case the rotation speed of the small pulley is less than that of the large pulley; when the slack cable coefficient is greater than zero, it simulates the slack cable phenomenon during the unwinding process, in which case the rotation speed of the large pulley is less than that of the small pulley.

[0039] Wrap angle adjustment: Change the center distance between the two pulleys by moving the slide rail platform to make the wrap angle reach the calculated value in step (1); the wrap angle reflects the contact range between the cable and the pulley, and the calculation formula is: In the formula: d d1 Let d be the diameter of the smaller pulley. d2 Let θ be the diameter of the large pulley, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

[0040] The wrap angle determines the contact range between the cable and the pulley (the larger the wrap angle, the larger the contact area and the more sufficient the friction). The center distance is precisely adjusted by moving the slide rail platform to ensure that the contact range is consistent with the actual working conditions and to avoid distortion of the wear degree due to the wrap angle deviation.

[0041] Speed ​​adjustment: Adjust the pulley speed according to the traction speed of the towed object to ensure that the relative motion rate between the cable and the pulley is consistent with the actual situation, and to ensure that the number of frictions and friction energy per unit time are the same as the actual situation.

[0042] (5) Traction loading

[0043] The cable is tensioned by pushing the slide rail platform with a hydraulic cylinder, simulating the traction force the cable experiences in actual operation, according to the required traction force in a real-world scenario. The output pressure of the hydraulic press is adjusted according to the required traction force; this output pressure is the cable traction force.

[0044] Traction force is a direct influencing factor of the friction between the cable and the pulley (friction force is positively correlated with normal force). This step applies a traction force consistent with the actual working conditions through a hydraulic cylinder to simulate the traction force that the cable bears during operation, ensuring that the friction stress level in the experiment is the same as that in reality.

[0045] (6) Friction force detection

[0046] The cable tension is collected using a pressure sensor, and the shaft torque is collected using a torque sensor. Combined with the wrap angle determined in step (4), the frictional force between the cable and the pulley is calculated using the following formula: In the formula, α represents the wrap angle of the cable, F0 is the cable traction force, and F is the cable tension force.

[0047] Traditional methods struggle to directly measure friction due to the unique characteristics of cable winding pulleys that do not contact each other and where clamping force cannot be directly applied to the cable. This step uses sensors to collect indirect parameters such as tension and torque, and combines this with the wrap angle calculation formula to achieve real-time friction detection, providing crucial data for analyzing the correlation between friction magnitude and wear degree.

[0048] To implement the above experimental method, this invention provides a dedicated experimental apparatus. This apparatus, through modular design, can accurately simulate the friction and wear process between cables and pulleys. Its core components include an experimental platform, a hydraulic loading assembly, a sliding assembly, a fixing assembly, and a replaceable pulley block module. These components work together to reproduce the friction and wear conditions in actual working conditions. The specific structure of each component is described in detail below.

[0049] The experimental platform serves as the fundamental load-bearing component of the device. Constructed from high-strength steel, its surface is precision-machined to ensure flatness. Its function is to provide a stable mounting reference for the hydraulic loading, sliding, and fixed components, ensuring that each component maintains relative positional accuracy during the experiment and preventing parameter measurement errors caused by foundation deformation.

[0050] The hydraulic loading assembly, mounted on the test bench, simulates the traction force experienced by the cable during actual operation. It includes a hydraulic cylinder 10, a pressure sensor 9, and a top column 8. The hydraulic cylinder 10 serves as the power source, providing linear thrust through the extension and retraction of its piston rod. The output pressure can be precisely adjusted via the hydraulic control system, simulating different traction forces and covering various working conditions from light traction to heavy lifting. A top column 8 is fixed to the top of its piston rod to transmit the thrust. The pressure sensor 9, fixed to the end of the piston rod of the hydraulic cylinder 10, moves synchronously with the piston rod, collecting the output pressure of the hydraulic cylinder 10 in real time. This directly reflects the tension force on the cable, providing crucial data for subsequent friction force calculations. The top column 8 is made of wear-resistant alloy material with an arc-shaped end face, matching the base 16 of the sliding assembly. This ensures the thrust from the hydraulic cylinder is evenly transmitted to the sliding assembly, guaranteeing stable force distribution on the sliding platform.

[0051] The sliding assembly is mounted on the slide rail 14 of the experimental platform and is linked with the hydraulic loading assembly. It is used to install one of the pulleys in the pulley group (for ease of description, the small pulley 5 will be used as an example below) and adjust the distance between the two pulleys. Specifically, it includes the slide rail platform 7 and the first drive unit and the first axle box 4 mounted on it. The first drive unit includes the first motor 1, the coupling 2, and the torque sensor 3. The first motor 1 is a servo motor, and its speed can be continuously adjusted in the range of 0-150 r / min through the frequency conversion system. It drives the first axle box 4 through the coupling 2 and the torque sensor 3 in sequence to provide rotational power to the small pulley 5. The coupling 2 is an elastic coupling, which absorbs installation deviations and vibrations through elastic elements to achieve flexible torque transmission and avoid the motor's movement affecting the measurement accuracy of the torque sensor. The torque sensor 3 is installed between the coupling 2 and the first axle box 4. It measures the torsional deformation of the shaft (sensed by strain gauges) and converts it into a torque signal. It collects the rotational torque of the small pulley 5 in real time and calculates the friction force by combining it with the pressure sensor data. One end of the first axle box 4 is connected to the torque sensor 3, and the other end is equipped with a first detachable pulley interface. An internal precision bearing is installed to fix the axial position of the small pulley 5, ensuring it is coplanar with the axis of the large pulley 11, and simultaneously transmitting torque to the pulley. The slide rail platform 7 is a rectangular steel structure. The top is used to install the first drive unit and the first axle box 4; the bottom is slidably connected to the slide rail 14 on the experimental platform via a slider 13, allowing it to move along the slide rail to change the center distance with the pulley in the fixed assembly, providing a structural basis for adjusting the wrap angle and cable slack coefficient; its bottom end is equipped with a base 16 that cooperates with the top column 8, receiving the thrust of the hydraulic cylinder to move the entire slide rail platform, achieving cable tensioning and traction loading.

[0052] The slide rail platform 7 is equipped with an electromagnetic stop valve 15, which is located near the slide rail 14. The electromagnetic coil is energized to generate magnetic force to attract the slider 13, thereby locking the slider position and preventing changes in the center distance between the two pulleys due to vibration or traction fluctuations during the experiment, thus ensuring the stability of the wrap angle and slack cable coefficient.

[0053] The fixing assembly is located near the first axle box 4 and is used to install one of the pulleys in the pulley block (for ease of description, the large pulley 11 will be used as an example below). Specifically, it includes the second motor 6 and the second axle box 12. The second motor 6 is a servo motor of the same model as the first motor 1, and its speed can be independently adjusted. It is connected to the second axle box 12 via a belt drive to provide rotational power to the large pulley 11, forming a speed difference with the first motor, and cooperating to adjust the cable release coefficient (simulating cable winding / unwinding state). One end of the second axle box 12 is connected to the second motor 6 via a belt, and the other end is provided with a second detachable pulley interface. Its internal structure is the same as that of the first axle box 4 (including precision bearings), which is used to fix the position of the large pulley 11, ensuring that it is coplanar with the axis of the small pulley 5, and at the same time transmit the motor power to the pulley.

[0054] The replaceable pulley block module includes at least one pulley block, each containing a matching small pulley 5 and a large pulley 11. The small pulley 5 is installed on a first detachable pulley interface, and the large pulley 11 is installed on a second detachable pulley interface. Their diameter ratio is the same as that of the actual working pulley block, and the diameter of the large pulley differs in different pulley blocks. Both are machined into a cylindrical structure, with groove width and depth consistent with the actual working pulley. The two pulleys form a cable friction path, and the distance between them is dynamically adjusted by the displacement of the sliding component. The groove surface forms a surface contact with the cable, simulating the force and friction state of the actual pulley.

[0055] During the experiment, the cable is wound between the small pulley 5 and the large pulley 11, forming surface contact. The hydraulic loading component tensions the cable by pushing the sliding component, and the pressure sensor 9 detects the traction force in real time. The motors of the sliding component and the fixed component drive the pulleys to rotate, and the cable slack coefficient and wrap angle are precisely controlled by adjusting the speed difference and center distance. The torque sensor 3 and the pressure sensor 9 work together to collect data and calculate the friction force. The electromagnetic stop valve 15 locks the position of the slide rail platform 7 to ensure parameter stability. Through mechanical connection and signal transmission, all components jointly reproduce the friction and wear conditions in actual working conditions, providing a reliable experimental platform for the study of cable wear performance.

[0056] The following example illustrates the specific experimental method using a V-shaped cable towing winch with pulleys of 150cm and 100cm in diameter, a towed load of 500kg, and a cable release speed of 8m / s. (1) Calculation of operating parameters Obtain the weight of the towed object (500kg), the traction speed (8m / s), and the actual pulley block model under working conditions; The traction force of the cable is the weight of the object being dragged. The traction force can be calculated to be 4903.3 N based on the weight of the dragged object. Calculate the wrap angle using the wrap angle calculation formula: In the formula, d d1 d is the diameter of the small pulley, with a value of 100cm. d2 Let θ be the diameter of the large pulley, which is 150cm; θ be half the angle between the cable and the small pulley, which is 57.3° by measuring the working angle of the cable on the pulley; and a be the center distance between the two pulleys, which is 230cm by measurement. Therefore, the wrap angle can be calculated to be 170.5°. The slack cable coefficient (k) is calculated using the following formula: In the formula, n1 is the rotational speed of the small pulley when the cable is released, which is 8 m / s; n2 is the rotational speed of the large pulley when the cable is released, which is measured to be 7.87 m / s; and the final calculated slack coefficient k is 0.0173. (2) Pulley matching machining Machining pulleys with V-shaped grooves on the sidewalls, with pulley diameters of 15cm and 10cm respectively, the diameter ratio of the two pulleys being the same as the actual working condition pulley group; machining the selected pulleys into a cylindrical structure, with the width and depth of the V-shaped pulley grooves being consistent with the actual working condition. (3) Experimental system construction Install the pulley block of the selected diameter on the two rotating shafts, making the axes of the two pulleys coplanar. Adjust the pulley spacing, which can be calculated by reverse calculation based on the wrap angle formula. The pulley spacing in the experiment should be 21.1cm. Wrap the cable around the pulleys to form surface contact. (4) Dynamic parameter adjustment Based on the calculated wrap angle, slack cable coefficient, and traction speed, the center distance between the two pulleys on the moving slide platform 7 is adjusted to 21.1cm, and the wrap angle is 170.5° (error < ±0.5°). The position is locked by the electromagnetic stop valve 15. Based on the traction speed and slack cable coefficient, the speeds of the first axis motor 1 and the second axis motor 6 are set. The motor speed of the small pulley after setting is consistent with the actual working speed, both being 8m / s. The speed of the large pulley shaft is derived in reverse according to the slack cable coefficient formula as 7.86m / s. (5) Traction loading Start the hydraulic loading assembly and slowly push the slide rail platform 7 to tension the cable; when the pressure sensor 9 first collects a reading (the cable is just tensioned), set the pressure to 0 (reference point); open the electromagnetic stop valve 15 and continue to adjust the output pressure of the hydraulic cylinder 10 until it reaches 4903.3N, completing the traction loading. (6) Friction force detection The motor is started to make the cable move according to the set working conditions. During the experiment: pressure sensor 9 collects the cable tension F in real time, torque sensor 3 collects the shaft torque, and the real-time friction force of the cable during the experiment is calculated using the cable friction force calculation formula. In the formula, α represents the wrap angle of the cable, which is 170.5°; F0 represents the cable traction force, which is 4903.3N; and F represents the cable tension, which is collected in real time by a pressure sensor. After the set experimental time is reached, stop the motor, unload the hydraulic cylinder pressure, close the electromagnetic stop valve 15, move the slide rail platform 7 to the initial position, and remove the cable after the experiment. The cable can be analyzed and characterized as needed after the experiment.

[0057] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method for testing cable friction and wear, characterized in that, The main steps include the following: (1) Calculation of working parameters: Obtain the weight of the dragged object, the traction speed and the actual working condition pulley block model, and calculate the traction force, wrap angle and slack coefficient when the cable is wound and released. (2) Pulley matching and machining: Select multiple sets of pulleys with the same diameter ratio as the actual working condition pulley set, and the diameter of the large pulley in different pulley sets is different; machine the selected pulleys into a cylindrical structure with groove width and groove depth consistent with the actual working condition pulley; (3) Experimental system construction: Install the pulley group of selected diameter on the two rotating shafts, so that the two pulley shafts are coplanar and the distance between them is adjustable; wrap the cable around the pulleys to form surface contact; (4) Dynamic parameter adjustment: Adjust the cable slack coefficient by adjusting the rotation speed of the two shafts and the center distance of the two pulleys to achieve the calculated value in step (1); adjust the wrap angle by adjusting the center distance of the two pulleys by moving the slide rail platform to achieve the calculated value in step (1); adjust the pulley rotation speed according to the traction speed of the dragged object; (5) Traction loading: The cable is tensioned by pushing the slide rail platform with a hydraulic cylinder, and the traction force calculated in step (1) is applied. (6) Friction detection: Data is collected by pressure and torque sensors, and the friction between the cable and pulley is calculated by combining the wrap angle.

2. The cable friction and wear test method according to claim 1, characterized in that, In step (4), the slack cable coefficient k is calculated using the following formula: In the formula, n1 is the rotational speed of the small pulley when releasing the cable and the rotational speed of the large pulley when retracting the cable; n2 is the rotational speed of the large pulley when releasing the cable and the rotational speed of the small pulley when retracting the cable; d d1 Let d be the diameter of the smaller pulley. d2 Let θ be the diameter of the large pulley, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

3. The cable friction and wear test method according to claim 1, characterized in that, In step (4), the wrap angle is calculated using the following formula: In the formula: d d1 Let d be the diameter of the smaller pulley. d2 Let θ be the diameter of the large pulley, θ be half the angle between the cable and the small pulley, and a be the center distance between the two pulleys.

4. The cable friction and wear test method according to claim 1, characterized in that, In step (6), the frictional force f between the cable and the pulley is calculated as follows: In the formula, α represents the wrap angle of the cable, F0 is the cable traction force, and F is the cable tension force.

5. The cable friction and wear test method according to claim 1, characterized in that, In step (7), the cross-sectional area and mass of the cable are measured before and after the experiment. The cable wear area is the ratio of the area removed from the cross section to the cross-sectional area before the experiment. The cable wear rate is the ratio of the cable mass loss after the experiment to the unit distance traveled.

6. A cable friction and wear test apparatus, characterized in that, include: Experimental platform; A hydraulic loading assembly, set on an experimental platform, includes a hydraulic cylinder (10) and a pressure sensor (9), wherein the pressure sensor (9) is fixed to the end of the piston rod of the hydraulic cylinder (10); The sliding assembly, located on the slide rail of the experimental platform and linked with the hydraulic loading assembly, includes a slide rail platform (7) and a first drive unit and a first axle box (4) mounted thereon; the first drive unit includes a first motor (1), a coupling (2) and a torque sensor (3), the first motor (1) being driven to connect to the first axle box (4) in sequence through the coupling (2) and the torque sensor (3); the end of the first axle box (4) is provided with a first detachable pulley interface; A fixed assembly is located near the first axle box (4) and includes a second motor (6) and a second axle box (12); the second motor (6) is connected to the second axle box (12) via a belt drive; the end of the second axle box (12) is provided with a second detachable pulley interface; The replaceable pulley block module includes at least one set of pulley blocks; each set of pulley blocks includes a matching small pulley (5) and a large pulley (11), wherein the small pulley (5) or the large pulley (11) is installed on the first detachable pulley interface, and the large pulley (11) or the small pulley (5) is installed on the second detachable pulley interface; the small pulley (5) and the large pulley (11) form a cable friction path, and the distance between them is dynamically adjusted by the displacement of the sliding component.

7. The apparatus according to claim 6, characterized in that: The piston rod of the hydraulic cylinder (10) is fixed with a top column (8).

8. The apparatus according to claim 7, characterized in that: The bottom of the slide rail platform (7) is slidably connected to the slide rail (14) on the experimental table via a slider (13). The bottom of the slide rail platform (7) is provided with a base (16) that cooperates with the top column (8). The hydraulic cylinder (10) pushes the slide rail platform (7) to move in order to adjust the center distance between the two pulleys.

9. The apparatus according to claim 6, characterized in that: The slide rail platform (7) is equipped with an electromagnetic stop valve (15), which is installed near the slide rail (14) to lock the position of the slider.

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