A high-speed friction device with constant temperature and pressure and its usage method

Abstract

The present invention proposes a constant temperature and constant pressure high-speed friction device and a method for using the same, comprising a friction pair and a heating component for heating the friction pair, a PLC, a dynamometer (2) for measuring the friction force of the friction pair, and a thermal infrared imager (15) for measuring the temperature of the friction interface of the friction pair; the friction pair comprises a pin (11) fixed by a pin fixture (8), and a friction disk (12) driven to rotate by an external mechanism; the movement of the pin fixture is driven by a cylinder (4) with a servo valve (17); the PLC is connected to the heating component and controls the heating of the pin according to the temperature measurement result to keep the temperature of the friction surface of the friction pair constant; the PLC is connected to the servo valve and controls the output pressure of the cylinder to the pin by controlling the cylinder air intake according to the friction force measurement result to keep the pressure between the pin and the friction disk constant; the present invention can realize accurate control of the friction interface temperature and contact pressure in the experiment, and can quickly heat and replace the sample, thereby effectively improving the reliability and efficiency of the experiment.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental equipment, in particular to a constant temperature and constant pressure high-speed friction device and a use method thereof. Background Art

[0002] The metal cutting process involves both passive and active heating of the workpiece material. During conventional cutting, the workpiece material undergoes rapid and intense plastic deformation. Due to the rapid deformation rate, heat accumulates within the workpiece within a short period of time, causing a strong adiabatic temperature rise. In specialized cutting conditions, such as laser-assisted cutting, lasers are used to actively heat the workpiece material, thereby modifying the mechanical properties of difficult-to-cut materials and enabling high-speed and efficient machining. In both cases, the increased temperature causes thermal softening of the workpiece material, affecting the cutting mechanism. Furthermore, the bond-slip relationship between the tool and chip changes under different process parameter combinations, affecting the contact pressure and, in turn, the friction and wear characteristics of the tool. Since most currently used tribology testing machines cannot simultaneously maintain a constant temperature and pressure environment, designing a tribology testing apparatus under constant temperature and pressure to analyze the tribological behavior between the workpiece and tool substrate under different temperature and contact pressure conditions will help us gain a deeper understanding of the tool-workpiece interaction mechanism during cutting, improve tool friction and wear, and optimize cutting process parameters.

[0003] At the same time, current friction test equipment lacks precise temperature control devices and does not take into account the effects of surface roughness and unevenness on the interaction force between the friction pair. Since the temperature rise at the tool-chip interface during metal cutting is caused by the large deformation of the material in the shear band and the friction between the tool and chip, increasing the temperature of the friction interface by using a heating device can more closely resemble the friction environment during the cutting process. During the experiment, the friction disc and the pin rub against each other, and a certain amount of material plastic flow will occur on the surfaces of the two specimens, which may cause microscopic ups and downs on the surface of the friction disc, changing the original surface roughness and unevenness of the friction disc, and thus affecting the interaction force between the pin and the friction disc. In order to accurately control the interaction force between the pin and the friction disc, it is necessary to constantly adjust the extension of the cylinder piston rod.

[0004] The current experimental equipment is not easy to achieve the above requirements and needs to be improved. Summary of the Invention

[0005] The present invention proposes a constant-temperature and constant-pressure high-speed friction device and a method for using the same. Through PID control, precise control of the friction interface temperature and contact pressure can be achieved in the experiment, and rapid heating and sample replacement are possible, effectively improving the reliability and efficiency of the experiment.

[0006] The present invention adopts the following technical solutions.

[0007] A constant temperature and constant pressure high-speed friction device is used for tool-chip contact friction experiments in metal cutting. The friction device comprises a friction pair and a heating component for heating the friction pair, a PLC, a dynamometer (2) for measuring the friction force of the friction pair, and a thermal infrared imager (15) for measuring the temperature of the friction interface of the friction pair. The friction pair comprises a pin (11) fixed by a pin fixture (8) and a friction disk (12) driven to rotate by an external mechanism. The movement of the pin fixture is driven by a cylinder (4) with a servo valve (17).

[0008] The PLC is connected to the heating component and controls the heating of the pin according to the temperature measurement results to keep the temperature of the friction surface of the friction pair constant; the PLC is connected to the servo valve and controls the output pressure of the cylinder to the pin by controlling the cylinder air intake according to the friction force measurement results to keep the pressure between the pin and the friction plate constant.

[0009] The dynamometer is mounted on a slide (14) of an external mechanism via a base plate (1), and a heating assembly heats the pins with a heating coil (9); a clamping plate (3) with a guide rail (7) is mounted above the dynamometer; a slide (6) is mounted on the guide rail; and a heating coil and a voltage controller (10) connected thereto are provided on the slide.

[0010] The external mechanism is a machine tool.

[0011] The heat output surface of the heating coil is directed toward the area between the end and the midpoint of the pin to avoid interfering with the thermal imaging of the thermal infrared imager; the heating coil heats the upper half of the pin, and the heat conduction through the pin body causes the entire pin to heat up; the distance between the heating coil and the pin is adjusted by moving a slider.

[0012] The pin fixture is installed at the piston rod (5) of the cylinder; the pin fixture fixes the pin with a fastener so that the front end of the pin contacts the friction disk, and the machine tool fixes the friction disk with a three-jaw chuck (13) and drives it to rotate.

[0013] A method for precisely controlling the temperature of the friction interface of a friction pair using a constant temperature and constant pressure high-speed friction device, employing the high-speed friction device described above, specifically comprising the following steps:

[0014] Step A1: The PLC measures the temperature of the pin using an infrared thermal imager to obtain the temperature T1 of the friction interface. The temperature command signal Ts is compared with the pin measured temperature signal T1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3.

[0015] Step A2, sending the error information e1, e2, and e3 to the PLC temperature controller (16), and the PLC temperature controller performs PID calculation on the error information;

[0016] In step A3, after the PID operation, the PLC controller inputs the signal that changes with the error information into the voltage controller. By controlling the voltage of the heating coil, different heating degrees of the pin are achieved. Combined with the heat dissipation process of the pin, the temperature of the pin reaches the set value.

[0017] A method for precisely controlling the interaction force of a friction pair by a constant temperature and constant pressure high-speed friction device, using the high-speed friction device described above, the method comprising the following steps:

[0018] Step B1: The pin and friction disk interact during the experiment. The PLC obtains the force along the machine tool axis through the dynamometer. The positive pressure P1 is obtained by converting the force and pressure. The pressure command signal Ps is compared with the positive pressure P1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3.

[0019] Step B2: input the error information e1, e2, and e3 into the PLC pressure controller (18), and the PLC pressure controller performs PID calculation on the error information;

[0020] Step B3: After the PID operation, the pressure controller of the PLC outputs a voltage or current analog value that changes with the error information, controls the opening degree of the servo valve to adjust the gas output of the air pump (19) of the cylinder gas source, and adjusts the extension of the cylinder piston rod, thereby adjusting the interaction force between the pin and the friction disk to achieve the purpose of the set pressure control instruction.

[0021] The force measuring instrument includes a Kistler force sensor.

[0022] A method for using a constant temperature and constant pressure high-speed friction device in a tool-chip contact friction experiment in metal cutting, using the high-speed friction device described above, wherein the hangar is a lathe, and comprising the following steps:

[0023] Step C1, move the slide of the lathe and adjust the position of the slider to ensure that the heating coil is located at the position required for the experiment;

[0024] Step C2: The machine tool spindle rotates, and the temperature command signal Ts and pressure command signal Ps are input. The heating coil and cylinder start working, and the PLC controls the feed amount of the piston rod through the servo valve to make the pin contact with the friction plate;

[0025] Step C3: Under the control of the PLC temperature controller and the PLC pressure controller, the measured temperature T1 and pressure P1 of the friction interface quickly reach the command temperature Ts and pressure Ps and remain stable, and the experimental data is recorded at this time;

[0026] At the end of the experiment, step C4, the servo valve controls the piston rod to retract, separating the pin from the friction disc. Simultaneously, the voltage controller gradually reduces the voltage in the heating coil to zero, shutting it down. The lathe's slide and slider are moved to ensure the pin is clear of the heating coil and friction disc, facilitating pin replacement.

[0027] Step C5: When conducting the next set of experimental parameters, after replacing the pin, proceed to Step C1. Simultaneously, the distance between the pin and the friction disc's rotational center must be adjusted by moving the lathe slide. By adjusting the distance between the pin and the friction disc's rotational center and the lathe spindle speed, friction experiments can be performed at different linear speeds without replacing the friction disc.

[0028] In the tool-chip contact friction experiment, the material of the pin corresponds to the workpiece material during the cutting process, and the material of the friction disc corresponds to the tool material during the cutting process;

[0029] The heating coil heats the pin based on the induction principle. The temperature rise caused by it corresponds to the temperature rise caused by large material deformation during the cutting process. The pin-disc friction temperature rise corresponds to the temperature rise caused by the tool-chip processing process during the cutting process.

[0030] In step C5, multiple sets of experiments can be performed on one friction disc without changing the material of the pin or the friction disc.

[0031] The device of the present invention has the following beneficial effects:

[0032] 1. The structure is simple and the test platform can be quickly built. Compared with the general friction tester, the device of the present invention is built on a lathe and has higher stability.

[0033] 2. The induction heating device has a simple structure and can achieve rapid heating of the pin through the induction principle (infrared thermal radiation or electromagnetic eddy current effect), saving experimental time; one friction disc can be used to conduct experiments with multiple sets of experimental parameters, improving experimental efficiency;

[0034] 3. Precise control of temperature and contact pressure through PID control ensures the reliability of experimental results.

[0035] The present invention only heats the pin during the experiment, so a large-diameter friction disc and a large-diameter heating coil are unnecessary, thereby avoiding an increase in the risk factor due to a bulky device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0037] Attachment Figure 1 is a schematic diagram of the device of the present invention;

[0038] Attachment Figure 2This is a schematic diagram of the installation of the dynamometer;

[0039] Attachment Figure 3 This is a schematic diagram of the installation of the heating component;

[0040] Attachment Figure 4 This is the installation diagram of the friction pair;

[0041] Attachment Figure 5 It is a schematic diagram of temperature control;

[0042] Attachment Figure 6 is a schematic diagram of pressure regulation;

[0043] Attachment Figure 7 It is a schematic diagram of the temperature measurement process;

[0044] In the figure: 1-base plate, 2-dynamometer, 3-clamp, 4-cylinder, 5-piston rod, 6-slider, 7-guide rail, 8-pin fixture, 9-induction coil, 10-voltage controller, 11-pin, 12-friction disk, 13-three-jaw chuck, 14-lathe slide, 15-thermal infrared imager, 16-PLC temperature controller, 17-servo valve, 18-PLC pressure controller, 19-air pump. DETAILED DESCRIPTION

[0045] As shown in the figure, a high-speed friction device with constant temperature and constant pressure is used for tool-chip contact friction experiments in metal cutting. The friction device includes a friction pair and a heating assembly for heating the friction pair, as well as a PLC, a dynamometer 2 for measuring the friction force of the friction pair, and a thermal infrared imager 15 for measuring the temperature of the friction interface of the friction pair. The friction pair includes a pin 11 fixed by a pin fixture 8 and a friction disk 12 driven to rotate by an external mechanism. The movement of the pin fixture is driven by a cylinder 4 with a servo valve 17.

[0046] The PLC is connected to the heating component and controls the heating of the pin according to the temperature measurement results to keep the temperature of the friction surface of the friction pair constant; the PLC is connected to the servo valve and controls the output pressure of the cylinder to the pin by controlling the cylinder air intake according to the friction force measurement results to keep the pressure between the pin and the friction plate constant.

[0047] The dynamometer is installed on the slide 14 of the external mechanism through the base plate 1, and the heating component heats the pin with a heating coil 9; a clamping plate 3 with a guide rail 7 is installed above the dynamometer; a slider 6 is installed on the guide rail; a heating coil and a voltage controller 10 connected to it are provided on the slider.

[0048] The external mechanism is a machine tool.

[0049] The heat output surface of the heating coil is directed toward the area between the end and the midpoint of the pin to avoid interfering with the thermal imaging of the thermal infrared imager; the heating coil heats the upper half of the pin, and the heat conduction through the pin body causes the entire pin to heat up; the distance between the heating coil and the pin is adjusted by moving a slider.

[0050] The pin fixture is installed at the piston rod 5 of the cylinder; the pin fixture fixes the pin with a fastener so that the front end of the pin contacts the friction disk, and the machine tool fixes the friction disk with a three-jaw chuck 13 and drives it to rotate.

[0051] A method for precisely controlling the temperature of the friction interface of a friction pair using a constant temperature and constant pressure high-speed friction device, employing the high-speed friction device described above, specifically comprising the following steps:

[0052] Step A1: The PLC measures the temperature of the pin using an infrared thermal imager to obtain the temperature T1 of the friction interface. The temperature command signal Ts is compared with the pin measured temperature signal T1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3.

[0053] Step A2: sending the error information e1, e2, and e3 to the PLC temperature controller 16, and performing PID calculation on the error information;

[0054] In step A3, after the PID operation, the PLC controller inputs the signal that changes with the error information into the voltage controller. By controlling the voltage of the heating coil, different heating degrees of the pin are achieved. Combined with the heat dissipation process of the pin, the temperature of the pin reaches the set value.

[0055] A method for precisely controlling the interaction force of a friction pair by a constant temperature and constant pressure high-speed friction device, using the high-speed friction device described above, the method comprising the following steps:

[0056] Step B1: The pin and friction disk interact during the experiment. The PLC obtains the force along the machine tool axis through the dynamometer. The positive pressure P1 is obtained by converting the force and pressure. The pressure command signal Ps is compared with the positive pressure P1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3.

[0057] Step B2: input the error information e1, e2, and e3 into the PLC pressure controller 18, and the PLC pressure controller performs PID calculation on the error information;

[0058] In step B3, after the PID operation, the PLC pressure controller outputs a voltage or current analog value that changes with the error information, controls the opening degree of the servo valve to adjust the air output of the air pump 19 of the cylinder air source, and adjusts the extension of the cylinder piston rod, thereby adjusting the interaction force between the pin and the friction plate to achieve the purpose of the set pressure control instruction.

[0059] The force measuring instrument includes a Kistler force sensor.

[0060] A method for using a constant temperature and constant pressure high-speed friction device in a tool-chip contact friction experiment in metal cutting, using the high-speed friction device described above, wherein the hangar is a lathe, and comprising the following steps:

[0061] Step C1, move the slide of the lathe and adjust the position of the slider to ensure that the heating coil is located at the position required for the experiment;

[0062] Step C2: The machine tool spindle rotates, and the temperature command signal Ts and pressure command signal Ps are input. The heating coil and cylinder start working, and the PLC controls the feed amount of the piston rod through the servo valve to make the pin contact with the friction plate;

[0063] Step C3: Under the control of the PLC temperature controller and the PLC pressure controller, the measured temperature T1 and pressure P1 of the friction interface quickly reach the command temperature Ts and pressure Ps and remain stable, and the experimental data is recorded at this time;

[0064] At the end of the experiment, step C4, the servo valve controls the piston rod to retract, separating the pin from the friction disc. Simultaneously, the voltage controller gradually reduces the voltage in the heating coil to zero, shutting it down. The lathe's slide and slider are moved to ensure the pin is clear of the heating coil and friction disc, facilitating pin replacement.

[0065] Step C5: When conducting the next set of experimental parameters, after replacing the pin, proceed to Step C1. Simultaneously, the distance between the pin and the friction disc's rotational center must be adjusted by moving the lathe slide. By adjusting the distance between the pin and the friction disc's rotational center and the lathe spindle speed, friction experiments can be performed at different linear speeds without replacing the friction disc.

[0066] In the tool-chip contact friction experiment, the material of the pin corresponds to the workpiece material during the cutting process, and the material of the friction disc corresponds to the tool material during the cutting process;

[0067] The heating coil heats the pin based on the induction principle. The temperature rise caused by it corresponds to the temperature rise caused by large material deformation during the cutting process. The pin-disc friction temperature rise corresponds to the temperature rise caused by the tool-chip processing process during the cutting process.

[0068] In step C5, multiple sets of experiments can be performed on one friction disc without changing the material of the pin or the friction disc.

[0069] In this example, the temperature of the friction interface is measured by an infrared thermal imager 15. The thermal infrared imager 15, the temperature PLC controller 16, the voltage controller 10, and the heating coil 9 form a closed-loop control circuit to regulate the temperature of the friction interface.

[0070] In this example, the pressure of the friction interface is measured by the dynamometer 2 , and the friction assembly, the dynamometer 2 , the pressure PLC controller 18 and the servo valve 17 form a closed-loop control circuit to regulate the pressure of the friction interface.

[0071] In this example, the dynamometer model is Kistler 9257B, which is connected to the base plate and the lathe slide through T-bolts; the clamping plate has a countersunk hole and is connected to the lathe slide through hexagon socket bolts.

[0072] In this example, the pin fixture has a pin hole with threads, and the pin is placed in the pin hole and clamped by a bolt in the threaded hole.

[0073] In this example, the guide rail-slider is installed on the splint by means of hexagon socket bolts, and a voltage controller is installed above the slider; the front end of the voltage controller is connected to the two poles of the heating coil, and the rear end is connected to the temperature PLC controller; the temperature of the friction interface is measured by a thermal infrared imager, and the thermal infrared imager, temperature PLC controller, voltage controller, and heating coil form a closed-loop control to adjust the temperature of the friction interface.

[0074] In this example, the cylinder is connected to a servo valve, which is connected to a pressure PLC controller and an air pump. The friction assembly, dynamometer, pressure PLC controller, and servo valve form a closed-loop control to adjust the contact pressure of the friction interface.

[0075] In this example, a heating coil is wrapped around the pin.

Claims

1. A high-speed friction device with constant temperature and constant pressure, used for tool-chip friction experiments in metal cutting, characterized by: The friction device includes a friction pair and a heating assembly for heating the friction pair, a PLC, a dynamometer (2) for measuring the friction force of the friction pair, and a thermal infrared imager (15) for measuring the temperature of the friction interface of the friction pair; the friction pair includes a pin (11) fixed by a pin fixture (8), and a friction disk (12) driven to rotate by an external mechanism; the movement of the pin fixture is driven by a cylinder (4) with a servo valve (17); The PLC is connected to the heating assembly and controls the heating of the pin according to the temperature measurement results to keep the temperature of the friction surface of the friction pair constant. The PLC is connected to the servo valve and controls the cylinder air intake to control the cylinder output pressure to the pin according to the friction force measurement results to keep the pressure between the pin and the friction plate constant. The dynamometer is mounted on a slide seat (14) of an external mechanism via a base plate (1), and a heating assembly heats the pins with a heating coil (9); a clamping plate (3) with a guide rail (7) is mounted above the dynamometer; a slide block (6) is mounted on the guide rail; a heating coil and a voltage controller (10) connected thereto are provided on the slide block; The external mechanism is a machine tool; The heat output surface of the heating coil faces the area between the end and the midpoint of the pin to avoid interfering with the thermal imaging of the thermal infrared imager. The heating coil heats the upper half of the pin, and heat conduction through the pin body causes the entire pin to heat up. The distance between the heating coil and the pin is adjusted by moving a slider. The pin fixture is installed at the piston rod (5) of the cylinder; the pin fixture fixes the pin with a fastener so that the front end of the pin contacts the friction disk, and the machine tool fixes the friction disk with a three-jaw chuck (13) and drives it to rotate.

2. A constant temperature and constant pressure high-speed friction device according to claim 1, characterized in that: A method for precisely controlling the temperature of the friction interface of a friction pair using a constant temperature and constant pressure high-speed friction device specifically comprises the following steps: Step A1: The PLC measures the temperature of the pin using an infrared thermal imager to obtain the temperature T1 of the friction interface. The temperature command signal Ts is compared with the pin measured temperature signal T1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3. Step A2: sending e1, e2, and e3 to the PLC temperature controller, and performing PID calculation on the error value; In step A3, after the PID operation, the PLC controller inputs the signal that changes with the error value into the voltage controller. By controlling the voltage of the heating coil, different heating degrees of the pin are achieved. Combined with the heat dissipation process of the pin, the temperature of the pin reaches the set value.

3. The constant temperature and constant pressure high-speed friction device according to claim 1, characterized in that: A method for precisely controlling the interaction force of friction pairs using a high-speed friction device with constant temperature and pressure. The following steps are included: Step B1: The pin and the friction disk interact during the experiment. The PLC obtains the force along the machine tool axis through the dynamometer. The pressure P1 is obtained by using the force-pressure conversion formula. The pressure command signal Ps is compared with the pressure P1 to obtain the error value e1, the first-order derivative of the error value e2, and the historical integral of the error value e3. Step B2: input the above e1, e2, and e3 into the PLC pressure controller, and the PLC pressure controller performs PID calculation on the error information; In step B3, after PID calculation, the PLC pressure controller outputs a voltage or current analog value that changes with the error information, controls the opening degree of the servo valve to adjust the air output of the air pump of the cylinder air source, and adjusts the extension of the cylinder piston rod, thereby adjusting the interaction force between the pin and the friction plate to achieve the purpose of the set pressure control instruction.

4. The constant temperature and constant pressure high-speed friction device according to claim 3, characterized in that: The force measuring instrument includes a Kistler force sensor.

5. The constant temperature and constant pressure high-speed friction device according to claim 1, characterized in that: In a method for using a constant temperature and constant pressure high-speed friction device in a tool-chip contact friction experiment for metal cutting, the machine tool is a lathe, and the method includes the following steps: Step C1, move the slide of the lathe and adjust the position of the slider to ensure that the heating coil is located at the position required for the experiment; Step C2: The machine tool spindle rotates, and the temperature command signal Ts and pressure command signal Ps are input. The heating coil and cylinder start working, and the PLC controls the feed amount of the piston rod through the servo valve to make the pin contact with the friction plate; Step C3: Under the control of the PLC temperature controller and the PLC pressure controller, the measured temperature T1 and pressure P1 of the friction interface quickly reach the command temperature Ts and pressure Ps and remain stable, and the experimental data is recorded at this time; Step C4: At the end of the experiment, the servo valve controls the piston rod to retract, separating the pin from the friction disc. Simultaneously, the voltage controller gradually reduces the voltage in the heating coil to zero, stopping the heating coil. Move the lathe's slide and slider to ensure that the pin is away from the heating coil and friction disc to facilitate pin replacement. Step C5. When conducting the next set of experimental parameters, after replacing the pin, you can follow step C1; at the same time, you need to move the lathe slide to adjust the distance between the pin and the rotation center of the friction disk. By adjusting the distance between the pin and the rotation center of the friction disk and adjusting the lathe spindle speed, friction experiments under different linear speeds can be obtained without replacing the friction disk.

6. The constant temperature and constant pressure high-speed friction device according to claim 5, characterized in that: In the tool-chip contact friction experiment, the material of the pin corresponds to the workpiece material during the cutting process, and the material of the friction disc corresponds to the tool material during the cutting process; The heating coil heats the pin based on the induction principle. The temperature rise caused by it corresponds to the temperature rise caused by large material deformation during the cutting process. The pin-disc friction temperature rise corresponds to the temperature rise caused by the tool-chip processing process during the cutting process. In step C5, multiple sets of experiments can be performed on one friction disc without changing the material of the pin or the friction disc.

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