A test apparatus and method for testing the crack initiation of brake discs and their fasteners.

Abstract

This invention relates to the field of brake disc technology, and more particularly to a test apparatus and method for testing crack initiation in brake discs and their fasteners. The test apparatus includes a support frame, a first drive device, a brake disc mechanism, a brake caliper mechanism, a heating mechanism, a cooling mechanism, an industrial camera, a temperature sensor, a real-time crack initiation monitoring system, and a high-frequency pulse load and thermal shock coupling loading device. This invention achieves millisecond-level synchronous coupling of load and thermal shock by heating and cooling the brake disc surface in conjunction with brake caliper braking, and by capturing the dynamic evolution process of the initial crack initiation stage using the real-time crack initiation monitoring system. The high-frequency pulse load and thermal shock coupling loading device achieves millisecond-level synchronous coupling of load and thermal shock, and the sensor and industrial camera record the complete crack initiation process and related data on the disc surface. By studying the crack initiation mechanism using this data, a reference is provided for mitigating or solving the problem of crack formation in brake discs and their fasteners.

Description

Technical Field

[0001] This invention relates to the field of brake disc testing technology, specifically to a test device and method for testing the crack initiation of brake discs and their fasteners. Background Technology

[0002] Currently, the initiation and propagation of cracks in brake discs and their fasteners is one of the main causes of braking system failure. Crack formation primarily stems from two aspects: first, uneven wear on the disc surface during service accelerates brake disc wear; second, the propagation of thermal fatigue cracks leads to disc fracture. Specifically, during braking, friction generates heat on the brake disc surface, and repeated braking creates alternating thermal stress within the brake disc and its fasteners, leading to the formation of cracks on the friction surface. Under reciprocating pulse stress, these cracks develop radially into main cracks. Cracks damage the friction surface structure of the brake disc, resulting in uneven braking force distribution and increased braking distance. During emergency braking, sudden brake force decay or brake failure may occur.

[0003] Traditional crack detection relies on manual visual inspection or offline flaw detection (such as magnetic particle and ultrasonic testing), which cannot capture the dynamic evolution process in the early stages of crack initiation and is easily affected by environmental noise. To address this issue, some researchers in the industry have conducted research, but existing devices use a single waveform (such as a sine wave) and thermal loading lags behind mechanical load, making it impossible to simulate the coupled conditions of "high-frequency impact load and transient high temperature" during sudden braking.

[0004] Therefore, there is an urgent need in the industry for a testing device and method for detecting the initiation of cracks in brake discs and their fasteners. Summary of the Invention

[0005] The purpose of this invention is to provide a test device for crack initiation of brake discs and their fasteners, which can simulate crack initiation of brake discs and their fasteners and accurately record the changes in parameters during the initiation process. It can provide the data required for the study of crack initiation mechanism of brake discs and their fasteners, and provide technical support for subsequent research on brake discs and their fasteners.

[0006] To achieve the above objectives, the present invention provides a test device for crack initiation of a brake disc and its fasteners, comprising a support frame and a first drive device, a brake disc mechanism, a brake caliper mechanism, a heating mechanism, a cooling mechanism, an industrial camera, a temperature sensor, a real-time crack initiation monitoring system, and a high-frequency pulse load and thermal shock coupling loading device mounted on the support frame; the support frame includes a frame, an upper plate, a middle plate, and a lower plate; the first drive device is mounted on the middle plate; the brake disc mechanism includes a rotating spindle for mounting the brake disc and a tensioning sleeve sleeved on the rotating spindle, the rotating spindle being connected to the first drive device via a torque and speed sensor; the brake caliper mechanism includes a clamp, a brake caliper, and a first lifting device, the brake caliper being mounted on the clamp and spanning above the brake disc, the first lifting device being connected to the clamp to carry... The clamp and brake caliper are raised and lowered; the heating mechanism includes a heater disposed on one side of the brake disc and a second lifting device for driving the heater to move up and down; the cooling mechanism includes a cooler disposed on one side of the brake disc and a cooling gas tank connected to the cooler; the industrial camera and the temperature sensor are used to acquire images of the changes on the surface of the brake disc and measure the temperature of the brake disc during the test, respectively; the crack initiation real-time monitoring system includes a fiber optic grating sensor and a high-speed fiber optic demodulator, the fiber optic grating sensor is embedded on the test surface of the brake disc, and the high-speed fiber optic demodulator is connected to the fiber optic grating sensor; the high-frequency pulse load and thermal shock coupling loading device includes an axial pulse loading module for controlling the opening and closing of the brake caliper and a radial thermal shock unit for simulating transient thermal shock in the contact area of ​​the brake disc.

[0007] Furthermore, a spiral groove is formed on the test surface of the brake disc, and the fiber Brake grating sensor is spirally installed in the spiral groove. The surface of the fiber Brake grating sensor is coated with a high-temperature resistant polyimide, and a thermoplastic polyester elastomer for covering the fiber Brake grating sensor is also provided in the spiral groove. The axial pulse loading module is an electro-hydraulic servo exciter, and the radial thermal shock unit includes an infrared laser array disposed on both sides of the test surface of the brake disc and a scanning galvanometer for controlling the movement of the spot of the infrared laser array projected onto the test surface of the brake disc. The radial thermal shock unit can locally heat the brake disc to 500~800℃ within 0.1s to simulate the transient thermal shock of the brake pad contact area.

[0008] Furthermore, the first lifting device includes a second driving device and a screw jack. The second driving device is disposed on the upper plate, and the screw jack passes through the upper plate. The upper end of the screw jack is connected to the output shaft of the second driving device through a coupling, and the lower end of the screw jack is fixedly connected to the clamp. The brake caliper is a pneumatic brake caliper.

[0009] Furthermore, the second lifting device includes a guide rail, a lead screw, and a third driving device. The third driving device is disposed on the upper plate. The guide rail and the lead screw are disposed parallel to each other on one side of the axial direction of the brake disc. The upper and lower ends of the guide rail are fixedly connected to the upper plate and the lower plate, respectively. The upper end of the lead screw is connected to the output shaft of the third driving device through a coupling, and the lower end of the lead screw is rotatably connected to the lower plate.

[0010] Furthermore, a first opening is provided on the intermediate plate, and the brake disc is disposed in the first opening; the guide rail and the lead screw are arranged through the first opening so that the heater can move up and down through the first opening.

[0011] Furthermore, the heater is a far-infrared heater, which includes a heating plate, a far-infrared heating wire, and a slide. The heating plate is arranged parallel to the brake disc, and the far-infrared heating wire is located on the side of the heating plate facing the brake disc. The slide is connected to the heating plate, and both ends of the slide are respectively provided with guide rail sliding holes and lead screw screw holes that match the guide rail and the lead screw. A second opening is provided on the lower plate, which allows the heating disc to be partially placed below the lower plate.

[0012] Furthermore, both the industrial camera and the temperature sensor are disposed on the intermediate plate. The industrial camera is located on the radial side of the brake disc, and the lens of the industrial camera is arranged coaxially with the rotating spindle. There are multiple temperature sensors, distributed on both radial sides of the brake disc.

[0013] Furthermore, a cooler is provided on each of the radial sides of the brake disc, and the side of the cooler facing the brake disc has an arc-shaped structure; each cooler is connected to a cooling air tank.

[0014] Furthermore, it includes a control system and a data acquisition card. The control system is connected to the first drive device, the brake caliper mechanism, the heating mechanism, the cooling mechanism, the industrial camera, the real-time crack initiation monitoring system, the high-frequency pulse load and thermal shock coupling loading device, and the data acquisition card. The data acquisition card is connected to the temperature sensor and the torque and speed sensor.

[0015] The present invention also provides a method for testing the crack initiation of brake discs and their fasteners, using the above-mentioned testing apparatus, and the testing method includes the following steps:

[0016] S1. Install the brake disc to be tested and its fasteners onto the tensioning sleeve, start the industrial camera and temperature sensor, take pictures of the initial state of the brake disc surface, and record the initial temperature T0.

[0017] S2. Start the second lifting device to raise the heater to the working position and start it. At the same time, start the radial thermal shock unit. After the brake disc is heated to the predetermined temperature T1, the heater will descend back to its initial position.

[0018] S3. Start the first drive device, set its predetermined speed and record the torque of the rotating spindle at the current moment;

[0019] S4. Start the first lifting device, move the brake caliper to the working position, start the brake caliper to perform a braking test on the brake disc, and record the torque during the test; after a certain period of time, the brake caliper returns to the initial position.

[0020] S5. Turn off the first drive device. At this time, the information recorded by the industrial camera, the temperature sensor and the torque speed sensor is the brake disc surface status information of the first stage.

[0021] S6. Activate the cooling mechanism to rapidly cool the brake disc, then repeat steps S2 to S5. During this process, when the real-time crack initiation monitoring system detects that the local strain gradient on the surface of the brake disc is greater than 50 με / mm and the temperature rise rate is greater than 10℃ / s, it triggers an audible and visual alarm and controls the system to mark suspicious areas. Until failure cracks appear on the surface of the brake disc, remove the brake disc and photograph its fasteners, then stop the test.

[0022] S7. The images of several sets of brake disc cracks from initiation to failure obtained from the test, as well as the torque, speed, temperature and test duration of each test stage, are processed to finally obtain the mechanism of brake disc surface crack initiation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The test device for crack initiation of brake discs and their fasteners of the present invention includes a support frame, a first drive device, a brake disc mechanism, a brake caliper mechanism, a heating mechanism, a cooling mechanism, an industrial camera, a temperature sensor, and a torque-speed sensor. The first drive device drives the rotating spindle and the brake disc assembly mounted thereon to rotate via the torque-speed sensor and a coupling. The torque-speed sensor is used to measure the rotational speed and torque of the simulated rotating spindle. The first lifting device drives the clamp and brake caliper to move up and down via the coupling. The second lifting device drives the heating mechanism to move up and down along the guide rail via the coupling. The heating mechanism is used to simulate extreme high temperature conditions on the surface of the brake disc. The cooling mechanism is used to cool the brake disc, which can reduce the temperature of the brake disc in a short time. The industrial camera and the temperature sensor are used to capture images of the front of the brake disc and measure the temperature of the brake disc during the experiment, respectively. The test device of the present invention can simulate the crack initiation of brake discs and their fasteners and accurately record the changes in parameters during the initiation process, and can provide the data required for the study of the crack initiation mechanism of brake discs and their fasteners.

[0025] (2) The crack initiation test device for brake discs and their fasteners of the present invention can capture the dynamic evolution process of the initial stage of crack initiation (micron-level defects) by setting a real-time crack initiation monitoring system, and is not easily affected by environmental noise; by setting a high-frequency pulse load and thermal shock coupling loading device, it breaks through the traditional step-by-step mode of "loading first and then heating", and realizes millisecond-level synchronous coupling of load and thermal shock; it can reproduce the crack initiation conditions of "contact stress concentration + thermal stress gradient" in real braking, and greatly shorten the test cycle.

[0026] (3) The method for testing the crack initiation of brake discs and their fasteners of the present invention applies severe alternating thermal stress to the surface of the brake disc and can use the sample device to arbitrarily set temperature gradients such as heating and cooling according to the needs of the test design to accelerate the simulation of alternating thermal stress changes of the brake disc, and then combines it with brake calipers for braking; the image of the crack change on the disc surface, other relevant data and the failure results of its fasteners are recorded by sensors and industrial cameras throughout the entire process from the crack initiation to the failure of the brake disc. Finally, the crack initiation mechanism is studied by image recognition, deep learning and data processing, which provides a reference for mitigating or solving the problem of crack generation in brake discs and their fasteners.

[0027] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a schematic diagram of the structure of a test device for crack initiation of a brake disc and its fasteners according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of a test device for crack initiation of a brake disc and its fasteners according to the present invention from another angle;

[0031] Figure 3 This is a schematic diagram of the heater in this invention;

[0032] Figure 4 This is a schematic diagram of the brake disc structure in this invention;

[0033] Wherein: 1-Support frame; 1.1-Frame; 1.2-Upper plate; 1.3-Middle plate; 1.4-Lower plate; 2-First drive device; 3-Brake disc mechanism; 3.1-Rotating spindle; 4-Brake caliper mechanism; 4.1-Clamp; 4.2-Brake caliper; 4.3-Second drive device; 4.4-Screw jack; 5-Heating mechanism; 5.1-Heater; 5.1a-Heating plate; 5.1b-Far-infrared heating wire; 5.1c-Slide carriage; 5.1d-Guide rail sliding hole; 5.1e-Screw screw hole; 5.2-Guide rail; 5.3-Screw; 5.4-Third drive device; 6-Cooling mechanism; 6.1-Cooler; 6.2-Cooling gas tank; 7-Industrial camera; 8-Temperature sensor; 9-Torque and speed sensor; 10-Data acquisition card; A-Brake disc; A.1-Spiral groove. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0035] Please see Figure 1 and Figure 2This invention provides a test device for crack initiation of a brake disc and its fasteners, comprising a support frame 1, a first drive device 2, a brake disc mechanism 3, a brake caliper mechanism 4, a heating mechanism 5, a cooling mechanism 6, an industrial camera 7, a temperature sensor 8, a torque and speed sensor 9, a data acquisition card 10, a real-time crack initiation monitoring system, a high-frequency pulse load and thermal shock coupling loading device, and a control system; wherein, the first drive device 2, the brake disc mechanism 3, the brake caliper mechanism 4, the heating mechanism 5, the cooling mechanism 6, the industrial camera 7, and the temperature sensor 8 are respectively mounted on the support frame 1; the specific structure is as follows:

[0036] Combination Figure 3 As shown, the support frame 1 includes a frame 1.1, an upper plate 1.2, a middle plate 1.3, and a lower plate 1.4. The upper plate 1.2 is located at the top of the frame 1.1. The middle plate 1.3 has a first opening, allowing the heater 5.1 to move up and down through the first opening to heat the test brake disc A mounted on the brake disc mechanism 3. The lower plate 1.4 is located below the middle plate 1.3, but not at the bottom of the frame 1.1. The lower plate 1.4 has a second opening. When not heating, the heating disc 5.1a can be partially placed below the lower plate 1.4. This structural design not only facilitates the installation of the first drive device 2, brake disc mechanism 3, brake caliper mechanism 4, heating mechanism 5, and cooling mechanism 6, but also makes the test device compact and space-saving. The brake disc mechanism 3 includes a rotating spindle 3.1 for mounting the brake disc A and a tensioning sleeve fitted on the rotating spindle 3.1. The first drive device 2 is an AC motor mounted on the intermediate plate 1.3. The output shaft of the AC motor is connected to the torque and speed sensor 9 via a coupling. The torque and speed sensor 9 is connected to the rotating spindle 3.1 via a coupling. The tensioning sleeve is connected to the brake disc A and its fixing parts. The first drive device drives the rotating spindle 3.1 to rotate via the coupling and the torque and speed sensor 9. The torque and speed sensor 9 is used to measure the speed and torque of the rotating spindle 3.1.

[0037] Combination Figure 4 As shown, the brake caliper mechanism 4 includes a clamp 4.1, a brake caliper 4.2, and a first lifting device. The first lifting device includes a second drive device 4.3 and a screw jack 4.4. The second drive device 4.3 is a servo motor mounted on the upper plate 1.2. The screw jack 4.4 passes through the upper plate 1.2. The upper end of the screw jack 4.4 is connected to the output shaft of the second drive device 4.3 via a coupling, and the lower end of the screw jack 4.4 is connected to the clamp 4.1 via a flange. The brake caliper 4.2 is mounted on the clamp 4.1 and spans above the brake disc A. The second drive device 4.3 drives the screw jack 4.4 and the clamp 4.1 to move up and down via the coupling, thereby realizing the downward movement of the brake caliper 4.2. The brake caliper 4.2 is a pneumatic brake caliper.

[0038] Combination Figures 1-3 As shown, the heating mechanism 5 is used to simulate extreme high temperature conditions on the surface of the brake disc. It includes a heater 5.1 and a second lifting device. The heater 5.1 is movably mounted on one radial side of the brake disc A. Specifically, the second lifting device includes a guide rail 5.2, a lead screw 5.3, and a third drive device 5.4. The third drive device 5.4 is a servo motor mounted on the upper plate 1.2. The guide rail 5.2 and the lead screw 5.3 are parallel and spaced apart on one axial side of the brake disc A. The upper and lower ends of the guide rail 5.2 are fixedly connected to the upper plate 1.2 and the lower plate 1.4, respectively. The upper end of the lead screw 5.3 is connected to the output shaft of the third drive device 5.4 through a coupling, and the lower end of the lead screw 5.3 is rotatably connected to the lower plate 1.4 through a bearing seat. The heater 5.1 is preferably a far-infrared heater, which includes a heating plate 5.1a, a far-infrared heating wire 5.1b, and a slide 5.1c. The heating plate 5.1a is arranged parallel to the brake disc A, and the far-infrared heating wire 5.1b is located on the side of the heating plate 5.1a facing the brake disc A. The slide 5.1c is fixedly connected to the heating plate 5.1a, and both ends of the slide 5.1c are respectively provided with guide rail sliding holes 5.1d and lead screw screw holes 5.1e that match the guide rail 5.2 and the lead screw 5.3. The third drive device 5.4 drives the lead screw 5.3 to rotate, thereby driving the heater 5.1 to move up and down along the guide rail 5.2. The cooling mechanism 6 includes a cooler 6.1 and a cooling gas tank 6.2 connected to the cooler 6.1. Both the cooler 6.1 and the cooling gas tank 6.2 are mounted on the intermediate plate 1.3. Preferably, a cooler 6.1 is provided on each radial side of the brake disc A, and each cooler 6.1 is connected to a cooling air tank 6.2; the side of the cooler 6.1 facing the brake disc A is configured with an arc shape. The cooling mechanism 6 is used to cool the brake disc, which can reduce the temperature of the brake disc in a short time. In this structural configuration, the heating mechanism 5 and the cooling mechanism 6 work together to apply severe alternating thermal stress to the surface of the brake disc, and the temperature gradients such as heating and cooling can be arbitrarily set according to the needs of the device test design to accelerate the simulation of alternating thermal stress changes of the brake disc.

[0039] In one specific embodiment of the present invention, both the industrial camera 7 and the temperature sensor 8 are disposed on the intermediate plate 1.3. The industrial camera 7 is located on the radial side of the brake disc A, and the lens of the industrial camera 7 is coaxially arranged with the rotating spindle 3.1, used to acquire images of surface changes of the brake disc A during the test. Multiple temperature sensors 8 are distributed on both radial sides of the brake disc A, used to measure the temperature of the brake disc A during the test. The distance between the temperature probe of the temperature sensor 8 and the brake disc A is 28 to 35 times the radius of the brake disc A being tested; preferably, the distance between the temperature probe and the brake disc A is 30 times the radius of the brake disc A, to ensure accurate data collection, thereby providing a reference for subsequent research and actual production.

[0040] In this embodiment of the invention, the real-time crack initiation monitoring system includes a fiber Bragg grating sensor and a high-speed fiber optic demodulator. For example... Figure 4 As shown, a spiral groove A.1 is formed on the test surface of brake disc A (the contact area of ​​the brake disc used for friction with brake caliper 4.2). A fiber optic grating sensor (not shown) is spirally mounted in this groove, with its receiving end and transmitting end mounted on the wheel hub. The depth of the spiral groove is 0.5-1mm, and the spiral arrangement of the fiber optic grating sensor forms a full-coverage monitoring network. The surface of the fiber optic grating sensor is coated with a high-temperature resistant polyimide coating, and a thermoplastic polyester elastomer is also provided in the spiral groove to cover the fiber optic grating sensor, so that the fiber optic grating sensor can fit snugly with the spiral groove, thereby ensuring that the fiber optic grating can deform synchronously with the brake disc; and the use of the thermoplastic polyester elastomer ensures that the test surface of the brake disc remains a flat surface. A high-speed fiber optic demodulator is connected to the fiber optic grating sensor to analyze strain and temperature signals in real time and transmit them to the control system via the PCIe bus. During the test, when the real-time crack initiation monitoring system detects a local strain gradient of >50με / mm on the brake disc and an abnormal temperature rise (ΔT>10℃ / s), it triggers an audible and visual alarm, and the control system marks the suspicious area.

[0041] In this embodiment of the invention, the high-frequency pulse load and thermal shock coupling loading device includes an axial pulse loading module and a radial thermal shock unit. The axial pulse loading module is an electro-hydraulic servo exciter for controlling the opening and closing of the brake caliper; using an electro-hydraulic servo exciter (maximum load 50kN, frequency 0-500Hz), ±20% load fluctuation is achieved through a fast reversing valve, which can effectively simulate the high-frequency braking pressure (typical frequency 10-50Hz) during ABS intervention. The radial thermal shock unit includes an infrared laser array (wavelength 808nm, single beam power 500W) disposed on both sides of the test surface of the brake disc and a scanning galvanometer for controlling the movement of the light spot projected by the infrared laser array onto the test surface of the brake disc (e.g., speed 10m / s). The radial thermal shock unit can locally heat the brake disc to 500~800℃ (preferably to 600℃) within 0.1s, simulating the transient thermal shock in the brake pad contact area. In this structural setup, based on a working condition database, the control system synchronously triggers mechanical loads and thermal loading to achieve a cyclic loading process of "load pulse-thermal shock-intermittent cooling" (adjustable cycle from 1 to 5 seconds), with a loading accuracy of ≤±3%. This structural setup breaks through the traditional step-by-step mode of "loading first and then heating," achieving millisecond-level synchronous coupling of load and thermal shock; it can reproduce the crack initiation conditions of "contact stress concentration + thermal stress gradient" in real braking, shortening the test cycle.

[0042] The control system is connected to the first drive device 2, brake caliper mechanism 4, heating mechanism 5, cooling mechanism 6, industrial camera 7, the real-time crack initiation monitoring system, the high-frequency pulse load and thermal shock coupling loading device, and data acquisition card 10, respectively, to control the test device to perform relevant actions, which is understandable to those skilled in the art. The data acquisition card 10 is connected to the temperature sensor 8 and the torque-speed sensor 9, respectively. In this configuration, sensor information is acquired using the data acquisition card; the industrial camera is used to acquire information about changes in the brake disc surface under corresponding parameters; and the control system is used to control the motor speed, brake pad movement, temperature changes in the heating and cooling mechanisms, and sensor data recording, etc.

[0043] This invention discloses a test device for crack initiation in brake discs and their fasteners. The main motion involves an AC motor driving a torque and speed sensor, a brake disc, and its fasteners (including a wheel hub, etc.) to rotate. The brake caliper and heating disc can move vertically along their respective guide mechanisms. The test device can automatically test and record data via a control system. When the main motion reaches a predetermined speed, the control system first controls the heating and cooling mechanisms to perform alternating temperature control, subjecting the brake disc mechanism to alternating complex stress. Then, the control system controls the rotation of servo motors in the heating and brake caliper mechanisms to move the heating disc and brake caliper out of the heating working area. An industrial camera then takes pictures, and this operation is repeated at preset photo intervals. Ultimately, key data on the evolution and changes in crack initiation in the brake disc and its fasteners are obtained.

[0044] This invention also provides a method for testing the crack initiation of a brake disc and its fasteners, using the aforementioned testing apparatus. The testing method includes the following steps:

[0045] S1. Install the brake disc A to be tested and its fasteners onto the tensioning sleeve, start the industrial camera 7 and temperature sensor 8, take pictures of the initial state of the surface of the brake disc A, and record the initial temperature T0.

[0046] S2. Start the second lifting device to raise the far-infrared heater 5.1 to the working position and start it. At the same time, start the radial thermal shock unit. After the brake disc A is heated to the predetermined temperature T1, the far-infrared heater 5.1 will descend back to its initial position.

[0047] S3. Start the first drive device 2, set its predetermined speed and record the torque of the rotating spindle 3.1 at the current moment; the first drive device 2 is a variable frequency motor.

[0048] S4. Start the first lifting device, move the brake caliper 4.2 to the working position, start the brake caliper 4.2 to perform a braking test on the brake disc A, and record the torque during the test; after working for a period of time, the brake caliper 4.2 returns to the initial position.

[0049] S5. The first drive unit 2 is turned off. At this time, the industrial camera 7, temperature sensor 8 and torque speed sensor 9 record the brake disc surface status in the first stage.

[0050] S6. Start the cooling mechanism 6 to quickly cool down the brake disc A, and then repeat steps S2 to S5. During this process, when the real-time crack initiation monitoring system detects that the local strain gradient on the surface of the brake disc is greater than 50 με / mm and the temperature rise rate is greater than 10℃ / s, it triggers an audible and visual alarm and controls the control system to mark suspicious areas. Until failure cracks appear on the surface of the brake disc, remove the brake disc A and photograph its fasteners, and then stop the test.

[0051] S7. Based on the obtained images of several sets of brake disc cracks from initiation to failure, and based on the torque, speed, temperature and test duration of the corresponding stages, the mechanism of brake disc surface crack initiation is finally obtained by processing these test data.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A brake disc and its fastener crack initiation test device, characterized by, The application relates to a test device for testing a brake disc, which comprises a support frame and a first driving device, a brake disc mechanism, a brake caliper mechanism, a temperature rising mechanism, a temperature falling mechanism, an industrial camera, a temperature sensor, a crack initiation real-time monitoring system and a high-frequency pulse load and thermal shock coupling loading device; the support frame comprises a frame, an upper plate, an intermediate plate and a lower plate; the first driving device is arranged on the intermediate plate; the brake disc mechanism comprises a rotating main shaft for mounting a brake disc and a tensioning sleeve sleeved on the rotating main shaft, and the rotating main shaft is connected with the first driving device through a torque and rotating speed sensor; the brake caliper mechanism comprises a clamp, a brake caliper and a first lifting device; the brake caliper is mounted on the clamp and arranged above the brake disc; the first lifting device is connected with the clamp to drive the clamp and the brake caliper to lift; the temperature rising mechanism comprises a heater arranged on one side of the brake disc and a second lifting device for driving the heater to move up and down; the temperature falling mechanism comprises a cooler arranged on one side of the brake disc and a cooling gas tank connected with the cooler; the industrial camera and the temperature sensor are respectively used for acquiring the image of the surface change of the brake disc and measuring the temperature of the brake disc during the test; the crack initiation real-time monitoring system comprises a fiber grating sensor and a high-speed fiber demodulator; the fiber grating sensor is embedded on the measured surface of the brake disc; the high-speed fiber demodulator is connected with the fiber grating sensor; the high-frequency pulse load and thermal shock coupling loading device comprises an axial pulse loading module for controlling the opening and closing of the brake caliper and a radial thermal shock unit for simulating the transient thermal shock of the contact area of the brake disc.

2. The test device of claim 1, wherein, A spiral groove is arranged on the measured surface of the brake disc; the fiber grating sensor is spirally arranged in the spiral groove; a high-temperature-resistant polyimide coating is arranged on the surface of the fiber grating sensor; and a thermoplastic polyester elastomer is arranged in the spiral groove for covering the fiber grating sensor; the axial pulse loading module is an electro-hydraulic servo vibration exciter; the radial thermal shock unit comprises an infrared laser array arranged on both sides of the measured surface of the brake disc and a scanning galvanometer for controlling the movement of the light spot projected on the measured surface of the brake disc by the infrared laser array; the radial thermal shock unit can locally heat the brake disc to 500-800 DEG C within 0.1 s to simulate the transient thermal shock of the contact area of the brake pad.

3. The test device of claim 1, wherein, The first lifting device comprises a second driving device and a screw spiral elevator; the second driving device is arranged on the upper plate; the screw spiral elevator is arranged through the upper plate; the upper end of the screw spiral elevator is connected with the output shaft of the second driving device through a shaft coupling; and the lower end of the screw spiral elevator is fixedly connected with the clamp; the brake caliper is a pneumatic brake caliper.

4. The test device of claim 1, wherein The second lifting device comprises a guide rail, a lead screw and a third driving device, the third driving device is arranged on the upper plate, the guide rail and the lead screw are arranged in parallel and spaced apart on one side of the brake disc in the axial direction, the upper and lower ends of the guide rail are fixedly connected with the upper plate and the lower plate respectively, the upper end of the lead screw is connected with the output shaft of the third driving device through a shaft coupling, and the lower end of the lead screw is rotationally connected with the lower plate.

5. The test device of claim 4, wherein, The first opening is arranged on the intermediate plate, and the brake disc is arranged in the first opening; the guide rail and the lead screw are arranged through the first opening, so that the heater can be lifted up and down through the first opening.

6. The test device of claim 4, wherein, The heater is a far-infrared heater, which comprises a heating disc, far-infrared heating wires and a sliding frame, the heating disc is arranged in parallel with the brake disc, the far-infrared heating wires are arranged on the side of the heating disc facing the brake disc, the sliding frame is fixedly connected with the heating disc, and the two ends of the sliding frame are respectively provided with a guide rail sliding hole and a lead screw hole matched with the guide rail and the lead screw; the second opening is arranged on the lower plate, and the heating disc can be partially arranged below the lower plate through the second opening.

7. The test device of claim 1, wherein The industrial camera and the temperature sensor are arranged on the intermediate plate, the industrial camera is arranged on one side of the brake disc in the radial direction, and the lens of the industrial camera is coaxially arranged with the rotating main shaft; the temperature sensor is a plurality of temperature sensors and is distributed on both sides of the brake disc in the radial direction.

8. The test device of claim 1, wherein, One of the coolers is arranged on each side of the brake disc in the radial direction, and the side of the cooler facing the brake disc is in an arc structure; each cooler is connected with one cooling gas tank.

9. The test device of claim 1, wherein, The control system is connected with the first driving device, the brake caliper mechanism, the temperature rising mechanism, the temperature falling mechanism, the industrial camera, the crack initiation real-time monitoring system, the high-frequency pulse load and thermal shock coupling loading device and the data acquisition card; the data acquisition card is connected with the temperature sensor and the torque and speed sensor.

10. A brake disc and a fastener crack initiation test method thereof, characterized by, The test device is used in the test method, and the test method comprises the following steps: S1, the brake disc and its fastener to be tested are arranged on the tensioning sleeve, the industrial camera and the temperature sensor are started, the initial state of the brake disc surface is photographed, and the initial temperature T0 is recorded; S2, the second lifting device is started, the heater is moved to the working position and started, and the radial thermal shock unit is started at the same time, and after the brake disc is heated to the predetermined temperature T1, the heater is lowered to return to the initial position; S3, the first driving device is started, the predetermined speed is set, and the torque of the rotating main shaft at the current time is recorded; S4, the first lifting device is started, the brake caliper is moved to the working position, the brake caliper is started to brake the brake disc, and the torque during the test is recorded; after a certain period of time, the brake caliper returns to the initial position; S5, the first driving device is turned off, and the industrial camera, the temperature sensor and the torque and speed sensor record the first stage of the brake disc surface state information; S6, start the cooling mechanism, and repeat steps S2-S5 after the brake disc is rapidly cooled. In this process, when the crack initiation real-time monitoring system detects that the local strain gradient on the surface of the brake disc is greater than 50 με / mm and the temperature rise rate is greater than 10°C / s, an audible and light alarm is triggered, and the control system marks the suspicious area. Until the failure crack appears on the surface of the brake disc, the brake disc is removed and the state of the fastener is photographed, and the test is stopped; S7, the pictures of the cracks of the brake discs obtained from several groups of tests from initiation to failure, and the torque, speed, temperature and test duration of each test stage are processed to obtain the mechanism of crack initiation on the surface of the brake disc.

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