Fatigue life test device for drum brake hub of vehicle

Abstract

The system comprises a hydraulic station, a servo electric cylinder, a programmable controller, an industrial control touch screen, a sensor detection technology and other technologies. The hydraulic station provides tension for the test bench and dynamically adjusts according to feedback of the tension sensor. The servo electric cylinder inputs height through the laser displacement sensor to control lifting, and therefore the purpose of controlling the steel wire rope to be horizontal is achieved. The PLC is used for sending instructions and collecting data. And the touch screen is used for writing instructions, monitoring equipment states and processing data. All the modules of the bending fatigue testing machine are matched to detect whether the hub can not generate cracks under the action of the specified bending moment and within the number of rotation turns or not. The bending fatigue test device provided by the invention integrates the functions of stepless speed regulation, automatic loading, automatic detection, recording and the like, and has relatively high competitiveness in the aspects of intelligent degree, manufacturing cost, accuracy and the like.

Description

Technical Field

[0001] The invention belongs to the field of testing devices, and in particular relates to a vehicle drum brake hub fatigue life testing device. Background Art

[0002] The wheel hub of a vehicle plays the role of load bearing, braking and transmission. The fatigue life of the 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 loads, two typical failure modes occur in the wheel hub during service: fatigue failure and strength failure, which account for 80% of the wheel hub service. Bending fatigue is an important indicator of whether the wheel hub design is qualified or not, and has a significant impact on the driving safety of the vehicle.

[0003] At present, the main methods for predicting wheel fatigue life are finite element analysis and bending fatigue test. Finite element analysis is essentially a simulation method based on numerical calculation. It calculates the behavior and response of each element through mathematical models, and finally obtains the behavior and response of the entire system. Using the finite element method, it can be simulated in the design stage, saving a lot of manpower and material resources. To a certain extent, finite element analysis is just a method used to reduce tests, but real test links are indispensable. Therefore, it is particularly important to design a bending fatigue testing machine that can efficiently detect wheels.

[0004] Most commonly used bending fatigue testing machines are tested by fixing the wheel and applying a rotational bending moment. This design requires a hollow shaft motor to be installed at one end of the loading shaft and a loading arm to hold the eccentric weight. Before the test, the required bending moment needs to be calculated, and then the eccentric weight is added to the loading arm, and the motor drives the rotation of the eccentric weight to generate centrifugal force to provide the bending moment.

[0005] Using centrifugal force to simulate the loading moment has the following problems:

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

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

[0008] 3) The bending moment required by the vehicle is large, and the loading arm is easy to break, posing a safety hazard;

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

[0010] An object of the present invention is to provide a vehicle drum brake hub fatigue life test device and to provide at least the advantages to be described below.

[0011] Another object of the present invention is to provide a vehicle drum brake hub fatigue life test device, which allows the wheel to rotate under a fixed bending moment, making the transmission more precise. In addition, a motor with smaller torque and power can be selected to effectively reduce manufacturing costs.

[0012] The technical solution of the present invention is as follows:

[0013] Vehicle drum brake hub fatigue life test device, which includes:

[0014] A frame having a fixture table mounting hole on the upper portion thereof;

[0015] A fixture table, the lower part of which is mounted in the fixture table mounting hole through 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;

[0016] A servo motor is arranged at one side below the frame, and an output end of the servo motor is arranged horizontally;

[0017] 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 on the fixture table;

[0018] A loading shaft, which 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;

[0019] An end cover, which has an inner circle bolt hole and an outer circle bolt hole, and is respectively connected to the top of the loading shaft and the wheel hub to be tested by bolts;

[0020] A steel wire rope horizontally connected to the steel wire rope fixing position;

[0021] a loading system connected to the steel wire rope and applying tension to the loading shaft;

[0022] in;

[0023] 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;

[0024] The inner circle bolt holes on the end cover and their distribution circle are the same as the threaded holes at the top of the loading shaft and their distribution circle.

[0025] Preferably, in the vehicle drum brake hub fatigue life test device, an air floating shock-absorbing foot is respectively provided at the four corners of the lower end surface of the frame.

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

[0027] A servo electric cylinder, which is arranged at the lower part of the frame and has an output end pointing vertically upward;

[0028] A fixed pulley 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 fixing position of the steel wire rope.

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

[0030] 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, and fixing holes are provided on the fixture plate corresponding to the positioning holes, and bolts and nuts cooperate to fix the fixture plate and the fixture table;

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

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

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

[0034] PLC controller;

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

[0036] A servo electric cylinder controller, which is electrically connected to the servo electric cylinder;

[0037] A hydraulic station servo controller, which is electrically connected to the hydraulic station;

[0038] A distance-measuring laser displacement sensor that detects the offset of the loading axis and transmits it to the PLC controller;

[0039] 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;

[0040] A tension sensor, which detects the loading tension value and transmits it to the PLC controller;

[0041] in,

[0042] The PLC controller pre-stores threshold values ​​for loading axis offset, wire rope fixing position height from the ground, and loading tension value. When the received loading axis offset, wire rope fixing position height from the ground, and loading tension value deviate, an adjustment command is issued to the servo motor controller, the servo electric cylinder controller, and the hydraulic station servo controller.

[0043] The present invention has the following beneficial effects:

[0044] 1. It has very high precision;

[0045] 2. It is more in line with the actual working conditions of the wheel than the method of applying rotational bending moment;

[0046] 3. The wheels are easy to install;

[0047] 4. It does not need to simulate the bending moment by the centrifugal force generated by the rotation of the counterweight, making the test safer;

[0048] 5. The cost is lower, 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, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic structural diagram of an embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

[0051] Figure 2 A schematic structural diagram of a combination of a loading shaft and an end cover in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

[0052] Figure 3 A schematic diagram of the structure of a fixture table in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

[0053] Figure 4 A schematic cross-sectional structure diagram of a fixture table in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

[0054] Figure 5 A working principle diagram of a hydraulic station in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

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

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

[0057] Figure 8 A servo electric cylinder control diagram in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention;

[0058] Fig. 9 A control diagram of a hydraulic station in one embodiment of a vehicle drum brake hub fatigue life test device provided by the present invention. DETAILED DESCRIPTION

[0059] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0060] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0061] The present invention clamps the wheel on the fixture table, applies a constant force to the other end of the loading shaft, and the platform and the loading shaft rotate together. The servo motor directly drives the fixture table to rotate through gear transmission. A bearing is installed at the force application point of the loading shaft, and then connected through a hydraulic system to generate a constant bending moment. On this basis, the present invention is a new wheel testing equipment designed 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 equipment is suitable for most vehicle wheel hub detection, including engineering vehicles, large buses, cars, etc.

[0062] like Figure 1 As shown, the vehicle drum brake hub fatigue life test device provided by the present invention adopts a loading method in which the wheel, the fixture table and the loading shaft rotate together and the load remains stationary. Specifically, it includes:

[0063] The frame 1 has a fixture table mounting hole on the top;

[0064] A fixture table 2, the lower part of which is mounted in the fixture table mounting hole through a bearing, and the wheel hub to be tested is fixed on the upper part, and the center of the fixture table 2 has a through hole;

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

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

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

[0068] An end cover 7, which has an inner circle bolt hole and an outer circle bolt hole, and is connected to the top of the loading shaft 5 and the wheel hub 6 to be tested by bolts respectively;

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

[0070] a loading system 9 connected to the steel wire rope 8 and applying tension to the loading shaft 5;

[0071] in;

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

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

[0074] A pair of spur gears and a pair of bevel gears form a two-stage transmission, which transmits the power of the motor to the fixture table, and also amplifies the torque of the servo motor and reduces the speed. Before the test, the tested wheel hub is replaced first. The mounting hole in the middle of the wheel hub is connected to the end cover on the upper part of the loading arm by bolts. The motor transmits power to the vertical loading shaft through two-stage gear transmission, driving the wheel hub, fixture table, and loading shaft to rotate together. The lower end of the loading shaft is connected to the hydraulic system through a wire rope for loading. The hydraulic system can be adjusted in real time according to the pre-set value and feedback the data to the PLC. The servo electric cylinder is controlled by the PLC to adjust the horizontal height of the wire rope to ensure the level of force loaded on the loading shaft. This is a key step to ensure the accuracy of the test. Imagine if the wire rope is not horizontal, then the force in the horizontal direction is actually a component force. This component force will be smaller than the theoretical loading force, resulting in a smaller bending moment of the actual loading and inaccurate test results. The air floating vibration reduction foot not only supports the weight of the equipment, but also can reduce the vibration of the equipment, which can save the isolation foundation and simplify the equipment installation process.

[0075] The load deviation of the loading system does not exceed the calculated value of the test load, and there are requirements for the number of test cycles, so it is more appropriate to use 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 maximum speed, and at any time, the torque of the motor cannot exceed its rated torque. Therefore, when selecting a servo motor, we must consider the use of the motor in many aspects to ensure that the motor can work safely for a long time. Select the MS1H3-44C15CD servo motor of Inovance Technology. It is necessary to install the bracket during installation. The bracket is first connected to the 4 holes on the end face of the motor with bolts, and then the bracket is fixed to the equipment.

[0076] The servo motor needs to be matched with the servo driver to operate normally, so it is necessary to select a servo driver. After consulting the technical documents of Inovance's MS1H3-44C15CD servo motor, it was found that this servo motor should use the SV680*T017S driver.

[0077] When selecting the material for the loading shaft, we must fully consider factors such as strength and stiffness while taking into account economy. The loading shaft in this test is subject to a large bending moment, so the alloy structural steel 40CrNiMoA is selected for tempering. One end of the loading shaft is connected to the end cover by bolts, and the end cover is connected to the wheel hub by bolts. 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, and the inner ring bolt holes and their distribution circle are the same as the threaded holes and their distribution circle on the top of the loading shaft. This design is mainly based on the fact that the bolt hole sizes and distribution circles of different types of wheel hubs are different. Each time you test a different type of wheel hub, you only need to replace the end cover, and the loading shaft does not need to be replaced, which can effectively reduce costs and bring convenience to operation. The other end of the loading shaft is designed with a shaft shoulder and a bearing ring groove to prevent the bearing from moving up and down. The combined structure diagram of the loading shaft and the end cover is shown in the figure. Figure 2 shown.

[0078] Gear transmission is one of the most commonly used mechanical transmissions. It has obvious transmission advantages, very high transmission efficiency, compact structure, good reliability, long service life, stable and accurate transmission ratio. Therefore, it is more appropriate to choose gear transmission for bending fatigue testing machine. Because the size of gear module mainly depends on the bending fatigue strength of tooth root, and the size of gear diameter mainly depends on the contact fatigue strength of tooth surface. Take the bending fatigue strength to obtain the module and round it to the pitch circle diameter calculated according to the contact fatigue strength. The gear of this equipment is most suitable as a solid structure. The speed of each axis of this machine tool is low, so a single key connection is used.

[0079] The fixture table is one of the core components of the bending fatigue testing machine. It mainly plays the role of clamping the wheel hub and driving the wheel hub to rotate. The quality of the fixture table directly affects the accuracy of the wheel hub fatigue test, the service life of the equipment and the safety and reliability. Therefore, the design of the fixture table is very important. The fixture table is processed with T-slots, which are used to install T-sliders. The slides are used with fixture plates and nuts to clamp the wheel hub. At the same time, in order to prevent the T-block from being thrown out when the fixture table rotates, positioning holes are designed on the T-slots and T-sliders. Before clamping the wheel hub, the slider can be positioned with a cylindrical pin, such as Figure 3 and Figure 4As shown. The design of the T-slider and T-slot is mainly based on the national standard. The through hole inside the fixture is mainly reserved for installing the loading shaft, and the inner diameter of this through hole is much larger than the diameter of the loading shaft. This design is to prevent the two from interfering with each other during the working process and greatly save space. This design makes the volume and weight of this test machine much smaller than the previous hub rotation type bending fatigue test machine. A bevel gear is installed at the lower end of the fixture, and its main function is to transmit the motor power to the fixture. After the tapered roller bearing is installed on the fixture, it can be installed on the test bench.

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

[0081] Load requirements: The test bench frame needs to withstand the maximum load and dynamic loads that the test bench is subjected to. Therefore, the strength and rigidity of the frame are important design considerations. When determining the size and shape of the frame, it is necessary to consider the load distribution of the test bench and the movement of the test bench to ensure that the strength and rigidity of the frame can meet the test requirements.

[0082] Space constraints: 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 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 frame should be selected according to the use environment and load requirements of the test bench. Generally, the material of the frame can be steel, aluminum alloy, carbon fiber, etc. The material of the frame should have sufficient rigidity and strength, and good corrosion resistance and wear resistance.

[0084] Connection method: The connection method of the test bench frame should be selected according to the use environment and load requirements of the test bench. Common connection methods include bolt connection, welding connection, etc. The connection method should be selected considering strength and rigidity, as well as the convenience of maintenance and maintenance.

[0085] Processing technology: The processing technology of the test bench frame should be selected according to the characteristics of the material and design requirements. Common processing technologies include cutting, bending, drilling, riveting, etc. The selection of processing technology should take into account the strength and rigidity requirements of the frame, as well as the accuracy and efficiency of processing.

[0086] Maintenance: The design of the test bench frame should be easy to maintain and maintain. The design of the frame should take into account the convenience of maintenance and maintenance to extend the service life of the frame and ensure the accuracy of the test. The design of the frame should consider the replacement and maintenance of wearing parts, as well as cleaning and lubrication.

[0087] The working principle diagram of the hydraulic station provided by the present invention is as follows: Figure 5As shown. When the electromagnetic reversing valve is in the left position, hydraulic oil flows into the left half of the hydraulic cylinder, and hydraulic oil flows out of the right half of the cylinder. The pressure on the left is greater than the pressure on the right, and the piston rod extends, which can provide a thrust. When the electromagnetic reversing valve is in the right position, hydraulic oil flows into the right half of the hydraulic cylinder, and hydraulic oil flows out of the left half of the cylinder. The pressure on the left is less than the pressure on the right, and the piston rod retracts, which can provide a pulling force. When the electromagnetic reversing valve is in the middle position, the system is unloaded, and the hydraulic oil flows directly back to the tank, which can save energy and prevent the oil from heating. At the same time, the hydraulic cylinder can maintain pressure stably.

[0088] Air flotation shock absorption is a technology that applies air flotation technology to the field of machine tool vibration reduction. During the machining process of machine tools, due to the high-speed rotation of the hub, the equipment will generate large vibration and noise, which seriously affects the accuracy of equipment detection and testing. The working principle of air flotation shock absorption is to use the air pressure control system to control the air pressure in the shock absorption unit, so that the shock absorption unit produces a reaction force, thereby producing a supporting effect to achieve the effect of vibration reduction. The air flotation shock absorption system has the advantages of good shock absorption effect, high stability, and automatic adjustment. It can effectively reduce equipment vibration and noise and improve the test accuracy of this equipment. After comprehensive consideration, Hengfan HFD-700B is selected for the air flotation shock absorption of the present invention.

[0089] The loading shaft and fixture are the most important load-bearing parts in this design, so it is necessary to perform finite element analysis. This finite element analysis uses the relevant plug-in in SolidWorks. The plug-in has an intuitive user interface, can be simulated during the design process, and provides a wealth of predefined materials, boundary conditions, and analysis types. The stress that the loading shaft can withstand is within the safety range, and the maximum displacement is also within the allowable range, so the design of the loading shaft meets the actual needs. After the fixture receives the torque from the gear, the stress and displacement are bent within the allowable range, so the design of the fixture meets the requirements.

[0090] like Figure 6 and Figure 7As shown, PLC cooperates with laser displacement sensor, tension sensor, servo motor, servo electric cylinder and hydraulic station to give full play to the greatest advantages. The control of the present invention is not complicated, so a small PLC can meet the needs, and Huichuan Easy521-0808TN is selected. This type of PLC is suitable for small volume, multi-axis operation and control, communication networking and other occasions. The PLC adopts modular design, has strong scalability, and can add expansion modules according to the interface needs. The fully autonomous programming software, continuously iterates the usability function, conforms to the application habits of engineers, and is easier to use. According to the functions realized by PLC, the present invention mainly realizes the functions of system initialization, motor stop, hydraulic station stop, data acquisition, system reset, etc. when designing the PLC main program. When starting the test machine, first initialize the data of each register, set the motor speed in the test parameters, input PLC and record the static data value of each sensor. After the motor reaches the set speed, turn on the electromagnet power supply, adjust the current according to the system parameters of the wheel under test, and the test machine starts to work normally. During the test, 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, a complete set of test equipment is designed to realize the information exchange between the test equipment and people. The bending fatigue testing machine uses PLC control technology for on-site control. The PLC control system is the core equipment for the control of the test machine. The human-computer interaction system needs to be compatible with the PLC control system to improve the reliability of the entire control system. The compatibility between industrial control touch screens and PLCs is very good, and only the bus is needed to meet the communication needs between multiple devices. Huichuan IT7000 is a new type of touch screen, and its display capability has achieved a qualitative leap. Compared with previous touch screens, its communication capability is more powerful and there are more types of communication interfaces. It has the following characteristics.

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

[0093] 2. Multi-touch: Support 10-point touch, which can realize multi-point operation and improve operation efficiency;

[0094] 3. High-definition display: 7-inch TFT LCD screen with a resolution of 800×480, clear display and bright colors;

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

[0096] 5. Support for multiple programming languages: Supports multiple programming languages ​​such as C, C++, VB, .NET, etc., which is convenient for users to carry out secondary development;

[0097] 6. Support for multiple controls: supports buttons, text boxes, progress bars, charts and other controls to facilitate user interface design;

[0098] 7. Multiple protection functions: supports password protection, screen lock, data backup and other protection functions to facilitate technical protection.

[0099] In the test bench control system, Inovance Easy521-0808TN PLC is used as the field device, and the touch screen uses the Inovance IT7100E working touch screen which is bend-compatible with the Inovance Easy521-0808TN PLC. The Inovance touch screen and Inovance PLC can communicate via TCP.

[0100] The present invention has three parts that require the use of sensors. The first is to determine whether the wheel hub has failed by detecting the offset of the loading shaft; the second is to control the servo electric cylinder by detecting the height of the loading position from the ground; the third is to control the hydraulic station by detecting the size of the loading tension. These three sensor detection points have a great impact on the test accuracy. If the failure of the wheel hub is not detected correctly or in time, failure data will be included, and even a safety accident may occur. Detecting the height of the loading position from the ground is directly related to the control accuracy of the servo electric cylinder, which causes the loading bending moment to be less than the theoretical bending moment, seriously affecting the test accuracy of the equipment. The sensor that detects the size of the loading tension is the feedback part of the hydraulic station, and its accuracy directly affects the size of the output tension of the hydraulic cylinder.

[0101] After multiple cycles of stress, the wheel's stiffness will inevitably decrease, which will cause the wheel to deform more and more during rotation, specifically manifested as a larger offset of the loading axis. Therefore, the offset of the loading axis can be used to determine whether the wheel has failed.

[0102] When the experiment is carried out, the static position of the loading axis on any side of the ranging laser motion sensor should be set in the experimental environment, and its actual static position should be recorded. During the formal measurement process of the equipment, the actual movement value measured by the sensor and the static value are subtracted to obtain the actual displacement rate of the measured point. In this way, it is more reasonable to determine whether the wheel is damaged. In this way, it is effective to judge whether the wheel is invalid. When the offset of the loading axis exceeds the set value, the PLC will issue a command to stop the test. Of course, if the bolts connecting the wheel hub are cracked or broken, it will also cause the offset of the loading axis to increase. In this case, you only need to replace all the bolts and continue the test. The probability of this happening is not high, and it cannot be regarded as a misjudgment of the equipment. Because stopping the rotation in this case can protect the safety of the test personnel, it is very necessary. Since the loading axis rotates during the test, it is more appropriate to use a non-contact sensor. For this test, it is decided to use a laser displacement sensor.

[0103] The laser distance measuring sensor of the present invention is Panasonic HG-C1200, and its measuring range is 120-280 mm to meet the detection requirements of the equipment.

[0104] The servo electric cylinder of the present invention adopts Chuangtuo YDA80-TL-BR-P: folded rear flange type, with a stroke of 150mm. The height measuring laser displacement sensor selects Panasonic HG-C1400 type, with a measuring range of 200-600mm.

[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 electric cylinder should be precisely controlled. Use the servo electric cylinder to raise and lower the fixed pulley to ensure that the force applied is in the horizontal direction. The servo electric cylinder is controlled by the PLC to adjust the horizontal height of the wire rope to ensure that the force loaded on the loading axis is horizontal. This is a key step to ensure the accuracy of the test. Imagine if the wire rope is not horizontal, then the force in the horizontal direction is actually a component force. This component force will be smaller than the theoretical loading force, resulting in a smaller bending moment of the actual loading and inaccurate test results. The control of the servo electric cylinder should be closed-loop control. The vertical height of the force point on the loading axis is determined by a laser displacement sensor, and the feedback data from the position sensor in the servo motor is sent to the input end to adjust the lifting height of the servo electric cylinder until the force along the wire rope is horizontal. Its control block diagram is as follows Figure 8 shown.

[0106] The present invention adopts PLC to control the hydraulic station, which mainly includes the following aspects of control:

[0107] 1. Hydraulic system pressure control: By controlling the switch of the solenoid valve, the workload of the hydraulic pump is adjusted to control the pressure of the hydraulic system. The PLC can monitor the pressure changes in real time and respond according to the set pressure range to ensure that the system always works within a safe range;

[0108] 2. Direction control of hydraulic cylinder: The extension and retraction of the hydraulic cylinder can be achieved by controlling the inflow of hydraulic oil. PLC can calculate the flow and pressure required by the hydraulic cylinder according to the set motion trajectory and achieve precise control;

[0109] 3. Hydraulic system temperature control: Overheating or underheating of hydraulic oil will cause system damage. PLC can adjust the temperature of hydraulic oil by controlling the operation of heat dissipation device and heat exchanger to keep it within the working range;

[0110] 4. Data recording and tracking: PLC can record and track data, ensuring that the data during equipment operation is controllable and visible, and providing guidance for subsequent maintenance.

[0111] By adopting PLC, human-machine interface and other technologies, the hydraulic system can be automatically controlled and monitored, and the stability and reliability of the system can be improved;

[0112] Hydraulic station hydraulic cylinder control Fig. 9 As shown, 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 the field of industrial automation. Its measurement principle is to use the internal thin film strain gauge to measure the force of the object and convert the force into an electrical signal output. It is usually used to measure the weight or tension of the object. The structure of the S-type tension sensor is "S" shaped, in which two tension sensors are arranged on the S-shaped surface. The Wheatstone bridge measurement method is adopted to achieve high-precision force measurement. The sensor can measure weight or force from a few grams to a few tons. It has the advantages of high sensitivity, high reliability, and easy installation. It is widely used in weight or tension measurement in logistics, mining, construction, medical treatment, machinery, environmental protection and other fields. The present invention uses the Dayang DYLY-103S tension and pressure 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 bending moment specified in the national standard by multiplying the loading axis length (1500mm).

[0114] According to the national standard, the bending fatigue test wheel hub needs to stop when the specified number of turns is reached. You only need to set the number of turns in the PLC and then use the encoder built into the servo motor to calculate it. The output of the incremental pulse encoder of the servo motor is a set of pulse signals. One of the most commonly used methods is to calculate the speed of the servo motor through pulses. It is relatively simple to use it as a speed measurement device here, which is convenient for PLC control and data collection.

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

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

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

[0118] After completing the design, production, and assembly, the bending fatigue testing machine needs to be debugged. Finally, the test is carried out according to the test requirements to verify whether the equipment meets the expected requirements. Before installing the wheel, it is necessary to select the loading shaft end cover according to the hub model, and connect the loading shaft and end cover. Then connect the hub to the loading shaft, and use a clamp to fix the hub to the fixture table. The bottom end of the fixture is a national standard T-shaped slider, on which a pin hole for a fixed position is added. When in use, the T-shaped slider and the fixture table are fixed together by pins so that the fixture will not be thrown out during rotation. After the hub is placed in the correct position, the nut on the clamping plate must be tightened so that the hub is firmly fixed to the fixture table.

[0119] The test wheel hub of the present invention uses a 15° deep groove 22.5×7.5 steel wheel hub currently used by most heavy-duty trucks to verify the performance of the device. During the test, key indicators such as the loading force output by the hydraulic station, the position information of the servo electric cylinder, and the offset of the loading axis are collected in real time. After checking each link of the equipment, close the power switch, then turn on the switch, and wait until the equipment runs stably before officially starting the test. At this time, the operating status of the equipment can be observed through the touch screen, and relevant data can be saved or recorded.

[0120] The present invention needs to make a cost analysis of all the accessories used based on the survey of Taobao, JD.com, and the official website, and the quotations of various parts are shown in Table 1.

[0121] Table 1 Bending fatigue testing machine cost table

[0122]

[0123]

[0124] After calculation, the total cost of the equipment is about 21,673 yuan, which has obvious price advantages over similar equipment on the market and meets the design requirements.

[0125] The test operation of the present invention is simple and intelligent, which greatly reduces the labor cost; it uses electric energy as a power source, is environmentally friendly and pollution-free, and effectively reduces heat consumption; it greatly reduces its repair and maintenance costs; it adopts an advanced control system to improve the test accuracy of the equipment and also provides convenience for the upgrade of the equipment; at the same time, its service life is also guaranteed.

[0126] The solution of running the host computer on the touch screen in the present invention is lower in cost than the solution of using an industrial computer plus a display screen, keyboard, and mouse, and is extremely cost-effective. The total cost of the equipment is about 21,673 yuan, which is lower than the cost of the bending fatigue testing machine on the market, and has great competitive advantages.

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

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

[0129] The present invention mainly describes the wheel rotating bending fatigue testing machine body, 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 other aspects. Many new technologies are used in this design, such as laser displacement detection technology, hydraulic station technology, servo electric cylinder technology, sensor control technology, touch screen control technology and the like. At the same time, the present invention also has some innovative points, such as the innovative design of the bending fatigue testing machine structure, transmission design, closed-loop control design of each module and the like. The mechanical structure design of the fatigue testing machine combines the advantages of both the wheel rotating type and the wheel non-rotating type. In this way, the simulation of the actual working condition of the wheel by the testing machine is more in line with the actual situation, and the traditional control cabinet is integrated into the machine body, which greatly reduces the size of the equipment. The transmission design changes the belt drive of the previous fatigue testing machine to gear drive, 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 closed-loop control of the hydraulic system and closed-loop control of the servo electric cylinder. The closed-loop control of these small modules plays a very important role in improving the accuracy of the equipment. Finally, the use of the equipment is explained, and the cost is analyzed and evaluated.

[0130] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. Vehicle drum brake hub fatigue life test device, characterized in that: include: A frame having a fixture table mounting hole on the upper portion thereof; A fixture table, the lower part of which is mounted in the fixture table mounting hole through 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 at 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 on the fixture table; A loading shaft, which 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, which has an inner circle bolt hole and an outer circle bolt hole, and is respectively connected to the top of the loading shaft and the wheel hub to be tested by bolts; 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; 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 their distribution circle are the same as the threaded holes at the top of the loading shaft and their distribution circle.

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 arranged 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 2, characterized in that: Also included is a wire rope horizontal adjustment mechanism, which includes: A servo electric cylinder, which is arranged at the lower part of the frame and has an output end pointing vertically upward; A fixed pulley 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 fixing position of the steel wire rope.

4. The vehicle drum brake hub fatigue life test device according to claim 3, 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, and fixing holes are provided on the fixture plate corresponding to the positioning holes, and bolts and nuts cooperate 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.

5. The vehicle drum brake hub fatigue life test device according to claim 4, characterized in that: The loading system is composed of a hydraulic station and a single-piston-rod hydraulic cylinder.

6. The vehicle drum brake hub fatigue life test device according to claim 5, characterized in that: Also includes: PLC controller; A servo motor controller electrically connected to the servo motor; A servo electric cylinder controller, which is electrically connected to the servo electric cylinder; A hydraulic station servo controller, which is 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, which detects the loading tension value and transmits it to the PLC controller; Among them, the PLC controller pre-stores threshold values ​​of 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 electric cylinder controller and the hydraulic station servo controller.

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