Vehicle drum brake hub fatigue life test device

Abstract

The application comprises hydraulic station, servo electric cylinder, programmable controller, industrial control touch screen, sensor detection technology and various technologies.The hydraulic station provides tension for the test bench and dynamically adjusts according to the feedback of the tension sensor.The servo electric cylinder controls the lifting through the input of the laser displacement sensor height, so as to control the horizontal of the steel wire rope.The PLC is used for sending instructions and collecting data.The touch screen is used for writing instructions, monitoring the equipment state and data processing.The bending fatigue testing machine is used for detecting whether the hub can not produce cracks under the action of the specified bending moment and the rotating number.The application provides a bending fatigue testing device which integrates the functions of non-pole speed regulation, automatic loading, automatic detection and recording, and has higher competitiveness in the intelligent degree, manufacturing cost and accuracy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of test devices, in particular to a kind of vehicle drum brake wheel hub fatigue life experimental device. BACKGROUND

[0002] Vehicle wheel hub plays the role of bearing, braking and transmission etc.. The fatigue life of wheel hub is one of the key factors affecting the safety of vehicle operation. Due to the complexity of production technology and the influence of dynamic random load, two typical failure modes of wheel hub appear in service: fatigue failure and strength failure, which accounts for 80% of the proportion in wheel hub service. Bending fatigue is an important indicator of wheel hub design pass or fail, and has an important influence on the driving safety of vehicle.

[0003] At present, the method for predicting the fatigue life of wheel hub mainly includes finite element analysis and bending fatigue test. Finite element analysis is essentially a simulation method based on numerical calculation, which calculates the behavior and response of each element through mathematical model, and finally obtains the behavior and response of the whole system. By using finite element method, the wheel hub can be simulated in the design stage, which saves a lot of manpower and material resources. To some extent, finite element analysis is only a method used to reduce test, but real test is essential. Therefore, it is particularly important to design a bending fatigue test machine capable of efficiently detecting the bending fatigue of wheel hub.

[0004] Commonly used bending fatigue test machines mostly test by fixing wheel and applying rotary bending moment. This design scheme needs to install a hollow shaft motor at one end of the loading shaft, and design a loading arm to place eccentric block. Before test, the required bending moment needs to be calculated, then eccentric block is added on the loading arm, and centrifugal force is generated by rotating eccentric block driven by motor to provide bending moment.

[0005] There are the following problems by using centrifugal force to simulate instead of loading bending moment:

[0006] 1) The loading system is not sensitive enough and difficult to control;

[0007] 2) In test, the size of bending moment M can only be changed by adjusting the speed of motor;

[0008] 3) The required bending moment of vehicle is large, and the loading arm is easy to break, which has safety hazard;

[0009] 4) The degree of intelligence is low, real-time display and monitoring cannot be realized, and bending moment is difficult to adjust. SUMMARY

[0010] An object of the present application is to provide a kind of vehicle drum brake wheel hub fatigue life experimental device, and provide at least the advantages to be explained later.

[0011] Another object of the present application is to provide a vehicle drum brake wheel hub fatigue life test device, which can make the transmission more accurate by rotating the wheel under a fixed bending moment, and can select a motor with smaller torque and power, thereby effectively reducing the manufacturing cost.

[0012] The technical scheme of the present application is as follows:

[0013] The vehicle drum brake wheel hub fatigue life test device comprises:

[0014] A rack, which is provided with a clamp table mounting hole on the top;

[0015] A clamp table, which is mounted in the clamp table mounting hole through a bearing on the bottom and is fixed with a wheel hub to be detected on the top, and the center of the clamp table is provided with a through hole;

[0016] A servo motor, which is arranged on one side below the rack, and the output end of the servo motor is arranged horizontally;

[0017] A spur gear transmission set and a bevel gear transmission set, which are connected to the output end of the servo motor, and one bevel gear in the bevel gear transmission set is fixed on the clamp table;

[0018] A loading shaft, which passes through the through hole and extends above the wheel hub to be detected, and the top of the loading shaft is provided with a plurality of threaded holes, and the bottom of the loading shaft is provided with a steel wire rope fixing position;

[0019] An end cover, which is provided with an inner ring bolt hole and an outer ring bolt hole on the top and is connected with the top of the loading shaft and the wheel hub to be detected through bolts, respectively;

[0020] A steel wire rope, which is connected horizontally on the steel wire rope fixing position;

[0021] A loading system, which is connected to the steel wire rope and loads the loading shaft with a pulling force;

[0022] Wherein;

[0023] The outer ring bolt hole on the end cover and its distribution circle are the same as the bolt hole on the wheel hub to be detected and its distribution circle;

[0024] The inner ring bolt hole on the end cover and its distribution circle are the same as the threaded hole on the top of the loading shaft and its distribution circle.

[0025] Preferably, in the vehicle drum brake wheel hub fatigue life test device, the lower end surface of the rack is provided with a gas floating damping foot at each of the four corners.

[0026] Preferably, the vehicle drum brake wheel hub fatigue life test device further comprises a steel wire rope horizontal adjustment mechanism, which comprises:

[0027] a servo cylinder arranged at the lower part of the frame and having an output end vertically upward;

[0028] a fixed pulley fixed to the output end of the servo cylinder by a fixed frame, and the upper surface of the fixed pulley is flush with the steel wire fixing position.

[0029] Preferably, in the vehicle drum brake wheel hub fatigue life experiment device,

[0030] The upper surface of the clamp table is provided with a T-shaped groove in a radial manner, a T-shaped sliding block is installed in the T-shaped groove, and positioning holes are arranged on the T-shaped groove and the T-shaped sliding block. A fixing hole is arranged on the clamp plate corresponding to the positioning hole, and the clamp plate and the clamp table are fixed by cooperation of a bolt and a nut.

[0031] The diameter of the through hole is much larger than the diameter of the loading shaft.

[0032] Preferably, in the vehicle drum brake wheel hub fatigue life experiment device, the loading system is composed of a hydraulic station and a single-piston rod hydraulic cylinder.

[0033] Preferably, the vehicle drum brake wheel hub fatigue life experiment device further comprises:

[0034] a PLC controller;

[0035] a servo motor controller electrically connected to the servo motor;

[0036] a servo cylinder controller electrically connected to the servo cylinder;

[0037] a hydraulic station servo controller electrically connected to the hydraulic station;

[0038] a distance measuring laser displacement sensor for detecting the loading shaft offset and transmitting it to the PLC controller;

[0039] a height measuring laser displacement sensor for detecting the steel wire fixing position ground clearance value and transmitting it to the PLC controller;

[0040] a tension sensor for detecting the loading tension value and transmitting it to the PLC controller;

[0041] wherein,

[0042] The PLC controller has pre-stored threshold values of the loading shaft offset, the steel wire fixing position ground clearance value and the loading tension value. When the received loading shaft offset, the steel wire fixing position ground clearance value and the loading tension value deviate, the servo motor controller, the servo cylinder controller and the hydraulic station servo controller are sent adjustment commands.

[0043] The present application has the following advantages:

[0044] 1. Very high precision;

[0045] 2. More in line with the actual working conditions of the wheel than the method of applying a rotating bending moment;

[0046] 3. Easy to install the wheel;

[0047] 4. No need to simulate the bending moment by the centrifugal force generated by the counterweight rotation, thus making the test safer;

[0048] 5. Lower cost, mainly reflected in the simpler processing technology of the loading shaft and the elimination of the rotating arm and its supporting parts.

[0049] Other advantages, objects and features of the present application will be partly embodied in the following description, and partly understood by those skilled in the art through research and practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 Structure schematic view of an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0051] Figure 2 Structure schematic view of the combination of the loading shaft and the end cover in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0052] Figure 3 Structure schematic view of the clamp table in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0053] Figure 4 Structure schematic view of the cross section of the clamp table in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0054] Figure 5 Working principle diagram of the hydraulic station in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0055] Figure 6 PLC control structure diagram in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0056] Figure 7 PLC control flow chart in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0057] Figure 8 Servo cylinder control diagram in an embodiment of the vehicle drum brake wheel hub fatigue life test device provided by the present application;

[0058] Figure 9 The hydraulic station control chart in one embodiment of the vehicle drum brake wheel hub fatigue life experiment device provided by the application. DETAILED DESCRIPTION

[0059] The application will be further described in detail below with reference to the drawings, so that those skilled in the art can implement the application according to the description and the drawings.

[0060] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0061] The application clamps the wheel on the fixture table, applies a constant force at the other end of the loading shaft, and rotates the platform and the loading shaft together. The servo motor directly drives the fixture table to rotate through gear transmission. A bearing is installed at the force application position of the loading shaft, and then connected through a hydraulic system to generate a constant bending moment. On this basis, the application designs a brand new wheel testing device with servo motor drive technology, laser displacement detection technology, programmable logic controller (PLC) technology, servo hydraulic pump station technology, and servo electric cylinder technology as the core. The device is suitable for most vehicle hub detection, including engineering vehicles, large passenger cars, and passenger cars.

[0062] As shown in Figure 1 The application provides a vehicle drum brake wheel hub fatigue life experiment device, which adopts a loading mode in which the wheel, the fixture table and the loading shaft rotate together and the load remains unchanged. Specifically, the device comprises:

[0063] A rack 1, which has a fixture table mounting hole at the top;

[0064] A fixture table 2, which is installed at the bottom of the fixture table mounting hole through a bearing, and has a to-be-detected wheel hub fixed at the top, and the fixture table 2 is provided with a through hole at the center;

[0065] A servo motor 3, which is arranged at one side below the rack 1, and the output end of the servo motor 3 is arranged horizontally;

[0066] A straight gear transmission set and a bevel gear transmission set 4, which are connected to the output end of the servo motor 3, and one bevel gear in the bevel gear transmission set is fixed on the fixture table 2;

[0067] A loading shaft 5, which passes through the through hole and extends above the to-be-detected wheel hub 6, and the top of the loading shaft 5 is provided with a plurality of threaded holes, and the bottom of the loading shaft 5 is provided with a steel wire rope fixing position;

[0068] End cover 7, which has inner circle bolt hole and outer circle bolt hole on it, and is connected with the top of the loading shaft 5 and the hub 6 to be tested respectively through bolt;

[0069] Steel wire rope 8, which is horizontally connected on the steel wire rope fixing position;

[0070] Loading system 9, which is connected to the steel wire rope 8 and loads the loading shaft 5 with tension;

[0071] Among them;

[0072] The outer circle bolt hole on the end cover 7 and its distribution circle are the same as the bolt hole on the hub 6 to be tested and its distribution circle;

[0073] The inner circle bolt hole on the end cover 7 and its distribution circle are the same as the threaded hole on the top of the loading shaft 5 and its distribution circle.

[0074] A pair of straight gears and a pair of bevel gears constitute a two-stage transmission, which transmits the power of the motor to the clamp table, and also amplifies the torque of the servo motor and reduces the speed. Before the test, first replace the test hub, the mounting hole in the middle of the hub is connected with the end cover on the upper part of the loading arm through the bolt, the motor transmits power to the vertical loading shaft through two-stage gear transmission, drives the hub, clamp table and loading shaft to rotate together. The lower end of the loading shaft is connected with the hydraulic system through the steel wire rope for loading, which can be adjusted in real time according to the preset value, and the data is fed back to PLC. The servo cylinder is controlled by PLC to adjust the horizontal height of the steel wire rope and ensure the horizontal force on the loading shaft. This is a key step to ensure the test accuracy. If the steel wire rope is not horizontal, the horizontal force will actually be a component force. This component force will be smaller than the theoretical load, resulting in a smaller actual bending moment and inaccurate test results. The air floating damping foot not only supports the weight of the equipment, but also can reduce the vibration of the equipment, so the isolation foundation can be omitted to simplify the equipment installation process.

[0075] The load deviation of the loading system should not exceed the calculated value of the test load, and the test cycle number is required, so it is more appropriate to select a servo motor with higher precision and controllable speed as the power source. In order to correctly select the motor, it is necessary to ensure that the maximum speed of the motor output does not exceed its highest speed, and at any time, the torque of the motor cannot exceed its rated torque. Therefore, when selecting a servo motor, we should consider the use of the motor from multiple aspects to ensure that the motor can work safely for a long time. Select the MS1H3-44C15CD type servo motor of Huichuan Technology. When installing, the installation support is needed. First, connect the support with the 4 holes on the end face of the motor with bolts, and then fix the support on the equipment.

[0076] Servo motor needs to cooperate with servo driver to run normally, so it is necessary to select a servo driver. According to the query of the technical document of the MS1H3-44C15CD type servo motor of Huichuan Technology, it is found that this servo motor should use the SV680*T017S type driver.

[0077] When selecting the material of the loading shaft, the strength, stiffness and other factors must be fully considered, and the economy must be considered. In this test, the loading shaft bears a large bending moment, so the alloy structural steel 40CrNiMoA is selected for quenching and tempering treatment. One end of the loading shaft is connected to the end cover through bolts, and the end cover is connected to the hub through bolts. The outer circle bolt hole and its distribution circle on the end cover are the same as the bolt hole and its distribution circle on the hub, and the inner circle bolt hole and its distribution circle are the same as the top thread hole and its distribution circle of the loading shaft. This design mainly considers that the bolt hole size and its distribution circle of different types of hubs are different. When testing different types of hubs each time, only the end cover needs to be replaced, and the loading shaft does not need to be replaced, which can effectively reduce the cost and bring convenience to the operation. The other end of the loading shaft is designed with a shoulder and a bearing ring clamping slot to prevent the bearing from moving up and down. The combined structure of the loading shaft and the end cover is shown in Figure 2 .

[0078] Gear transmission is one of the most commonly used mechanical transmissions, which has obvious transmission advantages, very high transmission efficiency, compact structure, good reliability, long service life and stable and accurate transmission ratio. Therefore, it is appropriate to choose gear transmission for the bending fatigue testing machine. Because the size of the gear modulus mainly depends on the tooth root bending fatigue strength, and the size of the gear diameter mainly depends on the tooth surface contact fatigue strength. The modulus is obtained by taking the bending fatigue strength and rounding it to, and the dividing circle diameter is calculated according to the contact fatigue strength. The gear of this equipment is most suitable as a solid structure. The rotational speed of each shaft of the machine tool is relatively low, so single key connection is adopted.

[0079] The fixture table is one of the core components of the bending fatigue testing machine, which mainly serves to clamp and rotate the hub. The quality of the fixture table directly affects the precision of the hub fatigue test, the service life and safety reliability of the equipment. Therefore, the design of the fixture table is very important. The T-shaped groove is machined on the fixture table, which is used to install the T-shaped slider. The slider cooperates with the clamp plate and the nut to clamp the hub. At the same time, in order to prevent the T-shaped block from being thrown out when the fixture table rotates, the T-shaped groove and the T-shaped slider are designed with positioning holes. Before clamping the hub, the slider can be positioned with a cylindrical pin, as shown in Figure 3 and Figure 4The T-shaped slider and T-shaped groove design are mainly based on the literature national standard. The through hole in the fixture table is mainly reserved for installing the loading shaft, and the inner diameter of the through hole is much larger than the diameter of the loading shaft. Such design is to avoid interference between the two during operation and greatly save space. This design makes the volume and mass of the test machine much smaller than the previous hub rotation type bending fatigue test machine. The bevel gear is installed at the lower end of the fixture table, and the main function is to transmit the power of the motor to the fixture table. The fixture table is installed with tapered roller bearings, and then it is installed on the test table.

[0080] The following aspects need to be considered in the design of the rack:

[0081] Load requirement: The rack of the test bench needs to bear the maximum load and dynamic load of the test bench. Therefore, the strength and stiffness of the rack are important considerations in the design. When determining the size and shape of the rack, the load distribution of the test bench and the movement mode of the test bench need to be considered to ensure that the strength and stiffness of the rack can meet the test requirements.

[0082] Space limitation: The design of the test bench rack needs to consider the space occupied by the test bench and the layout of the surrounding equipment. The size and shape of the rack should be designed according to the actual needs to ensure that the rack is coordinated with the layout of the surrounding equipment.

[0083] Material selection: The material of the test bench rack should be selected according to the use environment and load requirement of the test bench. Generally, the material of the rack can be selected from steel, aluminum alloy, carbon fiber, etc. The material of the rack should have sufficient stiffness and strength, and good corrosion resistance and wear resistance.

[0084] Connection method: The connection method of the test bench rack should be selected according to the use environment and load requirement of the test bench. Common connection methods include bolt connection, welding connection, etc. The selection of the connection method should consider the strength and stiffness, as well as the convenience of maintenance and maintenance.

[0085] Processing technology: The processing technology of the test bench rack should be selected according to the characteristics of the material and the design requirements. Common processing technologies include cutting, bending, drilling, riveting, etc. The selection of the processing technology should consider the strength and stiffness requirements of the rack, as well as the precision and efficiency of the processing.

[0086] Maintenance: The design of the test bench rack should be convenient for maintenance and maintenance. The design of the rack should consider the convenience of maintenance and maintenance to prolong the service life of the rack and ensure the accuracy of the test. The design of the rack should consider the replacement and maintenance of the vulnerable parts, as well as the cleaning and lubrication.

[0087] The working principle diagram of the hydraulic station matched by the present application is as follows: Figure 5The hydraulic cylinder left half cylinder flows in hydraulic oil, the right half cylinder flows out hydraulic oil, the left side pressure is greater than the right side pressure, the piston rod extends, at this time, a pushing force can be provided. When the electromagnetic reversing valve is in the right position, the hydraulic cylinder right half cylinder flows in hydraulic oil, the left half cylinder flows out hydraulic oil, the left side pressure is less than the right side pressure, the piston rod retracts, at this time, a pulling force can be provided. When the electromagnetic reversing valve is in the middle position, the system is unloaded, the hydraulic oil directly flows back to the oil tank, so that energy can be saved, and the oil liquid can be prevented from heating. At the same time, the hydraulic oil cylinder can stably maintain the pressure.

[0088] Air float shock absorption is a technology that applies air float technology to the field of machine tool shock absorption. During machine tool processing, due to high-speed rotation of the hub, the equipment will generate large vibration and noise, which seriously affects the accuracy of equipment detection and test. The working principle of air float shock absorption is to control the air pressure in the shock absorption unit by using an air pressure control system, so that the shock absorption unit generates a reaction force, thereby generating a supporting effect, to achieve the effect of shock absorption. The air float shock absorption system has the advantages of good shock absorption effect, high stability and automatic adjustment, can effectively reduce the vibration and noise of the equipment, and improve the test precision of the equipment. After comprehensive consideration, the air float shock absorption of the present application selects HFD-700B.

[0089] The loading shaft and the fixture table are the most important force components in this design, so it is necessary to carry out finite element analysis. The finite element analysis adopts the related plug-in of solidworks. The plug-in has an intuitive user interface, can simulate during the design process, and provides rich predefined materials, boundary conditions and analysis types. The stress that the loading shaft can withstand is within the safe range, and the maximum displacement is also within the allowable range, so the design of the loading shaft meets the actual requirements. After receiving the torque from the gear, the stress and displacement of the fixture table are within the allowable range, so the design of the fixture table meets the requirements.

[0090] As Figure 6 and Figure 7As shown, the PLC cooperates with the laser displacement sensor, the tension sensor, the servo motor, the servo cylinder and the hydraulic station, and fully plays the maximum advantage. The control of the application is not complex, and therefore a small PLC can meet the demand, and the Huichuan Easy521-0808TN is selected. The PLC is suitable for small volume, multi-axis operation and control, communication networking and the like. The PLC adopts a modular design, has strong expandability, and can add expansion modules according to the interface needs. The completely autonomous programming software continuously iterates the ease-of-use function, conforms to the application habit of engineers, and is more easy to use. According to the function realized by the PLC, when the PLC main program is designed, the system initialization, motor stop, hydraulic station stop, data acquisition, system reset and the like are mainly realized. When the testing machine is started, the data of each register is initialized, the motor speed is set in the test parameters, is input into the PLC and the static data value of each sensor is recorded. After the motor reaches the set speed, the electromagnet power is turned on, the current is adjusted according to the system parameters of the measured wheel, and the testing machine starts to work normally. In the test process, the PLC feeds back the data of each sensor to the touch screen in real time.

[0091] In the monitoring system of the test equipment, in order to realize the information exchange between the test equipment and the person, a complete test equipment is designed. The bending fatigue testing machine is controlled on site by adopting the PLC control technology, the PLC control system is the core equipment in the control of the testing machine, and the man-machine interaction system needs to be compatible with the PLC control system, so as to improve the reliability of the whole control system. The compatibility of the industrial control touch screen and the PLC is very good, and only a bus is needed to complete the communication needs between multiple devices. The Huichuan IT7000 is a new type of touch screen, and its display capacity realizes a qualitative leap, and compared with the previous touch screen, its communication capacity is more powerful, and the communication interface types are more. It has the following characteristics.

[0092] 1. High-precision touch: adopting the capacitive touch technology, the touch precision is up to ±2mm, and the response speed is fast;

[0093] 2. Multi-point touch: supporting 10-point touch, multi-point operation can be realized, and the operation efficiency is improved;

[0094] 3. High-definition display: adopting a 7-inch TFT liquid crystal screen, the resolution is 800*480, the display effect is clear and the color is bright;

[0095] 4. Multiple communication interfaces: supporting multiple communication interfaces such as serial port, Ethernet and USB, which is convenient for communication with other devices;

[0096] 5. Multiple programming languages are supported: supporting C, C++, VB,.NET and the like, which is convenient for users to carry out secondary development;

[0097] 6. Multiple control support: support buttons, text boxes, progress bars, charts and other controls, easy for users to interface design;

[0098] 7. Multiple protection functions: support password protection, screen lock, data backup and other protection functions, convenient for technical protection.

[0099] In the test bench control system, the HuiChuan Easy521-0808TN type PLC is used as a field device, and the HuiChuan IT7100E type working condition touch screen with bending compatibility is used with the HuiChuan Easy521-0808TN type PLC. The HuiChuan touch screen and the HuiChuan PLC can communicate through TCP.

[0100] The present application has three parts that need to use sensors, the first place is to detect the loading shaft offset and then judge whether the hub is invalid; the second place is to detect the loading position height from the ground and then control the servo cylinder; the third place is to detect the loading tension and then control the hydraulic station. The three sensor detection points have a great influence on the test accuracy. If the detection of hub invalidity is incorrect and not timely, it will cause invalid data to be counted, and even safety accidents may occur. The detection of the loading position height from the ground is directly related to the control accuracy of the servo cylinder, thereby causing the loading moment to be less than the theoretical moment, which seriously affects the equipment test accuracy. The sensor for detecting the loading tension is the feedback part of the hydraulic station, and its accuracy directly affects the output tension of the hydraulic cylinder.

[0101] After the wheel is subjected to force for many cycles, the stiffness will certainly decrease, which will make the deformation of the wheel in the rotating process become larger and larger, and the specific performance is that the offset of the loading shaft becomes larger. Therefore, the size of the loading shaft offset can be used to judge whether the wheel is invalid.

[0102] During the experiment, the static position of the loading shaft on one side of the distance laser movement sensor should be set in the experimental environment first, and the actual static position thereof is recorded. During the formal measurement process of the equipment, the actual movement value measured by the sensor is subtracted from the static value, so that the actual displacement rate of the measured point can be obtained. In this way, it can be more reasonably determined whether the wheel is damaged. In this way, it can effectively judge whether the wheel is invalid. When the loading shaft offset exceeds the set value, the PLC will issue a command to stop the test. Of course, if the bolts connected to the hub crack or break, it will also cause the loading shaft offset to become larger. In this case, the test can be continued after replacing all the bolts. The probability of this situation is not high, and it cannot be counted as a wrong judgment of the equipment. Because stopping rotation in this case can play a protective role for the test personnel, it is therefore very necessary. Since the loading shaft is rotating during the test, it is more appropriate to use a non-contact sensor, and a laser displacement sensor is determined to be used for the test.

[0103] The laser ranging sensor of the application selects Panasonic HG-C1200 type, and the range thereof is 120-280mm, which satisfies the detection requirement of the equipment.

[0104] The servo cylinder of the application adopts Zhejiang Chuangda YDA80-T-L-BR-P: flange type after folding, and the stroke is 150mm.

[0105] The loading system directly affects the accuracy of the test, especially whether the loading force is horizontal, which is directly related to the reliability of the test, so the servo cylinder should be accurately controlled. The servo cylinder is used to lift the fixed pulley, so as to ensure that the applied force is in the horizontal direction. The servo cylinder is controlled by PLC, and the horizontal height of the steel wire rope is adjusted to ensure that the force on the loading shaft is horizontal. This is a key step to ensure the test accuracy. If the steel wire rope is not horizontal, the force in the horizontal direction is actually a component force. This component force will be smaller than the theoretical loading force, so the actual bending moment is smaller, and the test result is inaccurate. The control of the servo cylinder should be closed-loop control. The vertical height of the force point on the loading shaft is determined by the laser displacement sensor, and the feedback data of the position sensor in the servo motor is sent to the input end to adjust the lifting height of the servo cylinder until the force along the steel wire rope is horizontal. The control block diagram is shown in Figure 8 .

[0106] The application adopts PLC to control the hydraulic station, and the control mainly includes the following aspects:

[0107] 1. Hydraulic system pressure control: the pressure of the hydraulic system is controlled by adjusting the working capacity of the hydraulic pump through the opening and closing of the electromagnetic valve. The PLC can monitor the pressure change in real time and respond according to the set pressure range, so as to ensure that the system always works in the safe range;

[0108] 2. Direction control of the hydraulic cylinder: the extension and contraction of the hydraulic cylinder can be realized by controlling the inflow of hydraulic oil. The PLC can calculate the required flow and pressure of the hydraulic cylinder according to the set motion trajectory, and realize accurate control;

[0109] 3. Temperature control of the hydraulic system: too high or too low temperature of the hydraulic oil will cause damage to the system. The PLC can adjust the temperature of the hydraulic oil by controlling the working of the heat dissipation device and the heat exchanger, so as to keep it within the working range;

[0110] 4. Data recording and tracking: the PLC can realize data recording and tracking, so as to ensure that the data during the operation of the equipment is controllable and visible, and provide guidance for subsequent maintenance.

[0111] By using PLC, human-machine interface and other technologies, automatic control and monitoring of the hydraulic system can be realized, and the stability and reliability of the system can be improved.

[0112] The control of the hydraulic station hydraulic cylinder is as shown in Figure 9 It can be found that the S-type tension sensor plays an important role.

[0113] The S-type tension sensor is a sensor widely used in industrial automation field. Its measurement principle is to measure the force of an object by using internal film strain gauges and convert the force into an electrical signal output. It is usually used to measure the weight or tension of an object. The structure of the S-type tension sensor is in the shape of "S", with two tension sensors arranged on the S-type surface. It adopts Wheatstone bridge measurement method to achieve high-precision force measurement. This sensor can measure weights or forces from a few grams to several tons, with high sensitivity, high reliability, easy installation and other advantages. It is widely used in weight or tension measurement in logistics, mining, construction, medical, mechanical, environmental protection and other fields. The present application selects Dayang DYLY-103 S-type tension sensor with a range of 100-300mm. Although this sensor can only detect the size of the loaded tension, it can also be converted into the loading moment specified in the national standard by multiplying the loading shaft length (1500mm).

[0114] According to the national standard, the bending fatigue test hub needs to stop when the specified number of turns is reached. Only the value of the number of turns needs to be set in the PLC, and then the encoder of the servo motor can be used for calculation. The output of the incremental pulse encoder of the servo motor is a group of pulse signals. The most commonly used way is to calculate the speed of the servo motor by pulse. Here, it is used as a speed measurement device because it is simple and convenient for PLC control and data acquisition.

[0115] Wheel bending fatigue test is a method used to test the durability of vehicle tires. This test usually applies cyclic loads on the tire and detects the deformation, cracks and other damage after a certain period of time to simulate the actual stress under long-term use.

[0116] During the test, the tire is usually installed on a specially designed testing machine and subjected to cyclic loads in multiple directions. The testing machine will continuously increase the load until the tire shows visible deformation, cracks or other damage.

[0117] This test method can help tire manufacturers and vehicle manufacturers check the life and performance of tires under actual use conditions to ensure safety and reliability.

[0118] After the completion of the design, production, assembly link, the bending fatigue testing machine needs to be debugged. Finally, according to the test requirements, the test is carried out to verify whether the equipment meets the expected requirements. Before the wheel is installed, the loading shaft end cover is selected according to the hub type, and the loading shaft and the end cover are connected. Then the hub is connected with the loading shaft, and the hub is fixed with the clamp table using the clamp. The bottom of the clamp is a national standard T-shaped slider, and a pin hole for fixing position is added. When in use, the T-shaped slider and the clamp table are fixed together through the pin, so that the clamp will not be thrown out during rotation. After the hub is placed in the correct position, the nuts on the compression plate are tightened, so that the hub is firmly fixed on the clamp table.

[0119] The test hub of the present application uses a 15° deep groove 22.5x7.5 steel hub currently used in most heavy trucks to verify the performance of the device. During the test, the loading force output by the hydraulic station, the position information of the servo cylinder, the offset of the loading shaft and other key indicators are collected in real time. After checking all aspects of the device, the electric brake is closed, then the switch is opened, and the test is started after the device runs stably. At this time, the running status of the device can be observed through the touch screen, and the relevant data can be saved or recorded.

[0120] The present application needs to make cost analysis on all the parts used according to the research of Taobao, Jingdong and official website, and the prices of various parts are shown in Table 1.

[0121] Table 1 Cost table of bending fatigue testing machine

[0122]

[0123]

[0124] The total cost of the device is about 21673 yuan, which has obvious price advantage compared with the same type of equipment on the market, and meets the design requirements.

[0125] The present application has simple test operation and high intelligent degree, greatly reduces the labor cost; uses electric energy as power source, is environment-friendly and pollution-free, effectively reduces heat consumption; greatly reduces the maintenance cost; adopts advanced control system, improves the test precision of the equipment and provides convenience for the upgrading of the equipment; and the service life is also guaranteed.

[0126] The scheme of running the upper computer on the touch screen has lower cost than the scheme of using industrial computer plus display screen, keyboard and mouse, and has great cost performance. The total cost of the present application is about 21673 yuan, which is lower than the cost of the bending fatigue testing machine on the market, and has great competitive advantage.

[0127] In summary, the present application meets the relevant requirements of economy and rationality.

[0128] The vehicle wheel bending fatigue test of the present application is a test equipment integrating servo motor technology, sensor detection technology, programmable controller technology, hydraulic technology, servo cylinder technology and gear transmission technology. The equipment has relatively advanced performance index and fully meets the use requirement.

[0129] The present application mainly explains from the aspects of the body of the wheel rotating bending fatigue testing machine, servo motor selection, bevel gear and spur gear design, fixture table design, loading shaft design, hydraulic system design, control function design, sensor detection scheme design and the like. Many new technologies are used in the design, such as laser displacement detection technology, hydraulic station technology, servo cylinder technology, sensor control technology, touch screen control technology and the like. Meanwhile, the present application also has some innovations, such as the innovative design of the structure of the bending fatigue testing machine, the transmission design, the closed loop control design of each module and the like. The mechanical structure design of the fatigue testing machine combines the advantages of the wheel rotating type and the wheel non-rotating type. This makes the simulation of the actual working condition of the testing machine more in line with the real situation, and integrates the traditional control cabinet into the body, greatly reducing the volume of the equipment. The transmission design changes the belt transmission of the previous fatigue testing machine to gear transmission, making the transmission more stable and effectively improving the detection accuracy of the equipment. When designing the control module, closed loop control is added to each small module, such as the closed loop control of the hydraulic system and the closed loop control of the servo cylinder. The closed loop control of these small modules plays a very important role in improving the accuracy of the equipment. Finally, the use method of the equipment is clarified, and the cost is analyzed and evaluated.

[0130] Although the embodiments of the present application have been disclosed as above, it is not limited to the use listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and equivalent scope.

Claims

1. Vehicle drum brake hub fatigue life test device, characterized in that: include: The frame has a fixture table mounting hole on the upper portion; A fixture table, the lower part of which is mounted in the fixture table mounting hole via a bearing, and the wheel hub to be tested is fixed on the upper part, and the center of the fixture table has a through hole; A servo motor is arranged on one side below the frame, and an output end of the servo motor is arranged horizontally; a spur gear transmission group and a bevel gear transmission group, which are connected to the output end of the servo motor, and one bevel gear in the bevel gear transmission group is fixed to the fixture table; A loading shaft passes through the through hole and extends above the wheel hub to be tested, the top of the loading shaft has a plurality of threaded holes, and the bottom of the loading shaft has a wire rope fixing position; An end cover having an inner circle bolt hole and an outer circle bolt hole, and connected to the top of the loading shaft and the wheel hub to be tested by bolts respectively; a steel wire rope horizontally connected to the steel wire rope fixing position; A loading system connected to the steel wire rope and applying tension to the loading shaft, wherein the loading system is composed of a hydraulic station and a single-piston-rod hydraulic cylinder; The wire rope horizontal adjustment mechanism comprises: A servo electric cylinder is arranged at the lower part of the frame with its output end pointing vertically upward; A fixed pulley, which is fixed to the output end of the servo electric cylinder through a fixing frame, and the upper surface of the fixed pulley is flush with the fixed position of the wire rope; PLC controller; a servo motor controller, electrically connected to the servo motor; A servo electric cylinder controller, electrically connected to the servo electric cylinder; a hydraulic station servo controller electrically connected to the hydraulic station; A distance-measuring laser displacement sensor that detects the offset of the loading axis and transmits it to the PLC controller; Height measuring laser displacement sensor, which detects the height of the wire rope fixed position from the ground and transmits it to the PLC controller; A tension sensor detects the loading tension value and transmits it to a PLC controller; the PLC controller pre-stores threshold values ​​for the loading axis offset, the height of the wire rope fixing position from the ground, and the loading tension value. When the received loading axis offset, the height of the wire rope fixing position from the ground, and the loading tension value deviate, an adjustment command is issued to the servo motor controller, the servo cylinder controller, and the hydraulic station servo controller; in; The outer ring bolt holes and their distribution circle on the end cover are the same as the bolt holes and their distribution circle on the wheel hub to be tested; The inner circle bolt holes on the end cover and the distribution circle thereof are the same as the threaded holes on the top of the loading shaft and the distribution circle thereof.

2. The vehicle drum brake hub fatigue life test device according to claim 1, characterized in that: An air-floating shock-absorbing foot is respectively provided at the four corners of the lower end surface of the frame.

3. The vehicle drum brake hub fatigue life test device according to claim 1, characterized in that: The upper surface of the fixture table is radially provided with T-shaped grooves, in which T-shaped sliders are installed, and positioning holes are provided on the T-shaped grooves and the T-shaped sliders. Fixing holes are provided on the fixture plate corresponding to the positioning holes, and bolts and nuts are used to fix the fixture plate and the fixture table; the diameter of the through hole is much larger than the diameter of the loading shaft.

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