Force temperature signal real-time synchronous measuring device in ultra-precision cutting process

Abstract

The invention belongs to the technical field of ultra-precision cutting machining, and particularly relates to a force temperature signal real-time synchronous measuring device in the ultra-precision cutting process. A real-time synchronous measuring device for force and temperature signals in the ultra-precise cutting process comprises a diamond self-temperature-sensing tool, the diamond self-temperature-sensing tool is fixed to a tool rest through a piezoelectric flexible force measuring hinge, and the piezoelectric flexible force measuring hinge is used for decoupling three-axis cutting force and projecting the cutting force to the X axis, the Y axis and the Z axis of a space coordinate system; the weak charge signals are converted into weak charge signals by the detection sensor and are output to the pre-processing module; original weak charge signals and voltage signals are output through the piezoelectric flexible force measuring hinge and the diamond self-temperature-sensing cutter, and after being processed by the signal preprocessing module, the original weak charge signals and the voltage signals are synchronously collected and output in real time by the signal collecting module, so that synchronous and accurate measurement of the cutting temperature and the three-axis cutting force in the ultra-precise process is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-precision cutting, and in particular relates to a real-time synchronous measurement device for force and temperature signals in an ultra-precision cutting process. Background Art

[0002] In order to evaluate the quality of ultra-precision cutting surface and optimize the cutting process, online monitoring of cutting state is indispensable. The cutting process is accompanied by complex thermal-mechanical coupling interactions. Cutting force and cutting temperature are important indicators for measuring cutting state such as machining surface size, shape accuracy, cutting chatter, tool wear, etc. Therefore, by sensing the size of cutting force and cutting temperature in real time, online monitoring of cutting state can be effectively achieved, thereby ensuring and optimizing the machining process. Especially for a class of materials with strong thermal sensitivity and poor stability, such as energetic materials that are used as power sources and power sources for long-range efficient destruction and precise strikes of weapons and equipment, online and accurate monitoring of cutting area temperature and force during their ultra-precision machining is crucial to ensuring machining surface quality and improving process safety. In addition, for difficult-to-machine materials with extremely low thermal conductivity, such as carbon fiber composites, online measurement of cutting temperature and cutting force can effectively avoid carbonization of the machining surface and excessive tool wear, reduce scrap rate, and improve machining efficiency. Therefore, it is of great significance to achieve real-time synchronous measurement of cutting temperature and cutting force in ultra-precision cutting. Summary of the invention

[0003] The purpose of the present invention is to provide a real-time synchronous measurement device for force-temperature signals in an ultra-precision cutting process, which is advantageous for high sensitivity, high precision, high response speed and can accurately detect cutting temperature and three-axis cutting force.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a real-time synchronous measurement device for force and temperature signals in an ultra-precision cutting process, comprising a diamond self-sensing temperature-sensing tool, which is fixed to a tool holder through a piezoelectric flexible force measuring hinge, the piezoelectric flexible force measuring hinge and the tool holder are insulated, and a signal pre-processing module, a signal acquisition module, and a power supply module are also provided on the tool holder; the power supply module is used to supply power and provide an accurate reference voltage for the signal pre-processing module and the signal acquisition module; the piezoelectric flexible force measuring hinge is used to decouple the three-axis cutting force, project the cutting force onto the three axes of the spatial coordinate system X, Y and Z, and is converted into a weak charge signal by the detection sensor and output to the signal pre-processing module; the original weak charge signal and voltage signal are output by the piezoelectric flexible force measuring hinge and the diamond self-sensing temperature-sensing tool, and after being processed by the signal pre-processing module, they are synchronously acquired and output in real time by the signal acquisition module, thereby realizing the synchronous and accurate measurement of the ultra-precision process cutting temperature and the three-axis cutting force.

[0005] The piezoelectric flexible force measuring hinge of the present invention can adopt the piezoelectric three-axis cutting force measuring flexible hinge disclosed in the patent publication number CN118493077A, and the diamond self-sensing temperature tool can adopt the diamond temperature sensing tool sensor disclosed in the patent publication number CN115847637A to realize high-resolution signal acquisition. The present invention can realize the synchronous real-time acquisition of force and temperature signals in the ultra-precision cutting process, achieve high sensitivity, high precision, and high response speed, realize the synchronous real-time acquisition of force and temperature signals in the ultra-precision cutting process, and realize the integration of processing and detection.

[0006] Among them, the insulation treatment between the piezoelectric flexible force measuring hinge and the tool holder can avoid the introduction of power frequency noise, reduce the error of electrical signal output, ensure the detection accuracy, and realize ultra-precision detection. Among them, the detection sensor can use a piezoelectric ceramic sensor to further improve the detection resolution and ensure ultra-precision detection.

[0007] Preferably, the diamond self-sensing temperature tool is used for cutting temperature measurement, by measuring its resistance value and then converting it into a temperature signal through the temperature-resistance function relationship. The resistance measurement can be performed by volt-ampere method.

[0008] Preferably, the piezoelectric flexible force measuring hinge is fixed to the tool holder through a connecting piece, an insulating layer is provided between the piezoelectric flexible force measuring hinge and the tool holder, and the insulating layer is provided with a through hole for making way for the connecting piece. By providing the insulating layer, physical insulation isolation between the piezoelectric flexible force measuring hinge and the tool holder is achieved to prevent signal interference. The insulating layer can be made of insulating materials such as ceramic sheets.

[0009] Preferably, the connector is provided with an insulating film, the tool holder is provided with a fixing hole for matching the connector, the insulating film is located between the connector and the wall of the fixing hole, the end of the connector is located outside the fixing hole, and an insulating gasket is provided between the end of the connector and the tool holder. The use of a bolt-style connector facilitates the connection and fixation of the piezoelectric flexible force measuring hinge and the tool holder, making assembly more convenient and easy to maintain and replace.

[0010] Preferably, the signal pre-processing module includes a charge amplifier unit, a voltage amplifier unit and a microampere constant excitation current output unit, and the charge amplifier unit corresponds one-to-one to the detection sensor and is used to measure the weak charge signal output by the detection sensor.

[0011] Preferably, the voltage amplifier unit is a differential amplifier circuit with the AD8421 instrument amplifier chip as the core, and the microampere constant excitation current output unit is a constant current source circuit with the LM334 power chip as the core, and a negative temperature coefficient silicon diode 1N457 is used to compensate for the temperature drift of the LM334 power chip during operation.

[0012] Preferably, the charge amplifier unit includes an LM7721 precision operational amplifier chip, and is designed with an input stage protection loop and a shielding cover to shield environmental electromagnetic interference. The charge signal is amplified and converted into a voltage signal in the range of -2.5V to +2.5V and output to the signal acquisition module; the charge amplifier unit uses a 10nF polypropylene film feedback capacitor to ensure system stability.

[0013] A cover-shaped piece made of materials such as nickel silver is used as a shielding cover to perform electromagnetic shielding, thereby improving the stability of use and the precision effect; nickel silver has good weldability, machinability, electromagnetic shielding and corrosion resistance.

[0014] Preferably, the signal acquisition module includes an AD7606 eight-channel bipolar analog-to-digital conversion chip and an STM32F103C8T6 microprocessor. The AD7606 converts the six-channel voltage signal into a digital signal and sends it to the STM32 via SPI. The STM32 sends the received data to the data output terminal via UART.

[0015] The invention has the advantages of being easy to achieve high sensitivity, high precision, high response speed and being able to accurately detect the cutting temperature and the size of the three-axis cutting force. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the device according to an embodiment of the present invention.

[0017] Figure 2 It is a schematic structural diagram of the connection between the piezoelectric flexible force measuring hinge and the tool holder in an embodiment of the present invention.

[0018] Figure 3 It is a schematic diagram of the implementation principle of the charge amplification unit in the signal pre-processing module in an embodiment of the present invention.

[0019] Figure 4 It is a schematic diagram of the principle of realizing electromagnetic shielding of the charge amplification unit in the signal pre-processing module in an embodiment of the present invention.

[0020] Figure 5 It is a wiring diagram of AD7606 and STM32 of the signal acquisition module in an embodiment of the present invention.

[0021] Figure 6 It is a schematic diagram of the output voltage configuration principle of the power supply module in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below based on the accompanying drawings and specific embodiments.

[0023] Depend on Figure 1 and Figure 2As shown, this embodiment discloses a real-time synchronous measurement device for force and temperature signals in an ultra-precision cutting process, including a diamond self-sensing temperature tool 5, which is fixed to a tool holder through a piezoelectric flexible force measuring hinge 3, and the piezoelectric flexible force measuring hinge 3 is insulated from the tool holder. A signal pre-processing module 6, a signal acquisition module 7, and a power supply module 9 are also provided on the tool holder. Among them, the tool holder includes a base 10 and a top cover 1, and the base 10 and the top cover 1 are installed by M2 screws. The tool holder is a 65Mn alloy tool holder, which ensures the high rigidity performance of the entire device; the base 10 has an installation space for accommodating the signal pre-processing module 6, the signal acquisition module 7, and the power supply module 9, forming a modular design, which is convenient for the later debugging, fault diagnosis and repair of the device of this embodiment.

[0024] The power supply module 9 is used to supply power and provide accurate reference voltage for the signal pre-processing module 6 and the signal acquisition module 7; the diamond self-temperature sensing tool 5 is used to measure the cutting temperature, by measuring its resistance value and then converting it into a temperature signal through the temperature-resistance function relationship; the piezoelectric flexible force measuring hinge 3 is used to decouple the three-axis cutting force, projecting the cutting force onto the three axes of the spatial coordinate system X, Y and Z, and converted into a weak charge signal by five detection sensors and output to the signal pre-processing module; the detection sensor of this embodiment is a piezoelectric ceramic sensor. The piezoelectric flexible force measuring hinge of this embodiment adopts the piezoelectric three-axis cutting force measurement flexible hinge disclosed in the patent publication number CN118493077A, and the diamond self-temperature sensing tool adopts the diamond temperature sensing tool sensor disclosed in the patent publication number CN115847637A.

[0025] In this embodiment, the original weak charge signal and voltage signal are output by the piezoelectric flexible force measuring hinge 3 and the diamond self-temperature sensing tool 5. After being processed by the signal pre-processing module 6, the signal acquisition module 7 synchronously collects and outputs them in real time, thereby realizing the synchronous and accurate measurement of ultra-precision process cutting temperature and three-axis cutting force.

[0026] Depend on Figure 1 As shown, the diamond self-sensing temperature tool 5 is installed on the piezoelectric flexible force measuring hinge 3 through the M4 hexagon socket screw and nut, and the piezoelectric flexible force measuring hinge 3 is installed on the front half of the base 10 through the insulating structure 4. The signal pre-processing module includes a first signal pre-processing module 6 and a second signal pre-processing module 8. The first signal pre-processing module 6, the second signal pre-processing module 8, the signal acquisition module 7 and the power supply module 9 are stacked and installed on the rear half of the base 10, and the shielding cover made of white copper is installed on the signal pre-processing module.

[0027] like Figure 2As shown, the insulating structure between the piezoelectric flexible force measuring hinge 3 and the tool holder includes a sheet-like insulating layer 13 made of ceramic, a connector 4 and an insulating gasket 14 made of ceramic. The connector 4 is in the shape of a bolt, and both the piezoelectric flexible force measuring hinge 3 and the tool holder have a fixing hole for matching the connector 4. The insulating layer 13 is provided with a through hole for giving way to the connector 4. The connector 4 is provided with an insulating film 16 made of insulating plastic. The piezoelectric flexible force measuring hinge 3 is fixed to the tool holder through the connector 4, and the insulating film 16 is located between the wall of the fixing hole and the connector 4, and the insulating gasket 14 is located between the bolt head of the connector 4 (the end of the connector 4) and the tool holder. The base 10 of the tool holder of this embodiment has a fixing portion 11, and the fixing portion 11 has the through hole. The fixing portion 11 is penetrated by the hexagon socket screw and the connector. The fixing portion 11 is provided with a window for the diamond self-temperature sensing tool 5 to pass through, and the bolt head of the connector 4 (the end of the connector 4) is located outside the fixing portion 11.

[0028] The first signal pre-processing module 6 integrates a charge amplifier unit, a voltage amplifier unit and a microampere constant excitation current output unit, and the second signal pre-processing module 8 integrates four stability charge amplifier units. A total of five charge amplifier units correspond to five detection sensors one by one and are used to measure weak charge signals. Among them, the charge amplifier unit uses a 10nF polypropylene film feedback capacitor to ensure system stability.

[0029] Among them, the voltage amplifier unit is a differential amplifier circuit with the AD8421 instrument amplifier chip as the core. A 100-ohm variable resistor and a 10-ohm resistor are used in series to configure the amplification factor of the AD8421. The voltage signal is amplified to the range of 0V~5V and output to the signal acquisition module 7. The microampere-level constant excitation current output unit is a constant current source circuit with the LM334 power chip as the core. The negative temperature coefficient silicon diode 1N457 is used to compensate for the temperature drift of the chip during operation. The LM334 chip peripheral feedback network is configured using two resistors of 13.7kΩ and 137kΩ to obtain a constant current source output size of 10μA. For the specific implementation method of the AD8421 instrument amplifier amplification configuration, refer to the AD8421 data sheet provided by ANALOG DEVICES, and for the specific implementation scheme of the LM334 output current configuration, refer to the LM334 data sheet provided by Texas Instruments. The resistor configuration scheme principle disclosed in the patent application number 202411120880.6 is used to configure the resistors to obtain a suitable current size to compensate for the temperature drift.

[0030] like Figure 3 As shown, the charge amplifier unit is a charge amplifier circuit with the LMP7721 operational amplifier chip as the core. Ignoring the parasitic capacitance and resistance of the transmission line, the ideal result of the calculation - the amplification gain A is approximately: .

[0031] in, is the unit of gain (F is the unit of capacitance, Farad), which means that the input charge signal is converted into a voltage signal and amplified by 10 8 times. The charge from Input stage input, R2 is the input stage protection resistor, R1 is 20 The large feedback resistor is used to unload the charge stabilization system. The voltage signal obtained by charge conversion is output after passing through R3. , The non-inverting input stage is grounded and connected to the The voltage follower is connected to the circuit, R6 and C10 are the feedback resistor and capacitor of the voltage follower, and the output signal is output to the circuit after passing through R42. To realize electromagnetic shielding of the charge amplifier unit, the input stage protection loop GUARD1 is connected to the shielding cover, such as Figure 4 As shown, the shielding cover 17 tightly covers the charge amplifying unit 18, and the shielding covers outside the charge amplifying unit 19 and the charge amplifying unit 21 are not drawn.

[0032] The signal acquisition module 7 is based on the AD7606 eight-channel analog-to-digital conversion chip and the microprocessor STM32F103C8T6. The AD7606 converts the six-channel voltage signal into a digital signal and sends it to the STM32 via SPI. The STM32 sends the received data to the data output terminal via UART, including wireless Bluetooth, USB interface and RS485 interface. The voltage signal interface receives the sensor signal from the signal pre-processing module. After passing through the AD7606, the signal is quantized into a 16-bit digital signal and transmitted to the STM32 via SPI. The wiring diagram of AD7606 and STM32 is shown in Figure 5Given, where +5V is the power supply line of AD7606, +2.5V is the external reference voltage, and GND is the common ground level of AD7606 and STM32. CS is the chip select signal of the SPI line, connected to the PC3 pin of STM32. RD / SCLK is the clock signal of SPI, connected to the PA5 pin of STM32. DB7 / DOUT is the data signal of SPI, connected to the PA6 pin of STM32. RAGE is the range configuration of AD7606, and the range is configured to ±5V when grounded. RST is the reset signal, connected to the PB13 pin of STM32. CVA is connected in parallel with CVB and is the start analog-to-digital conversion signal, connected to the PB12 pin. OS0, OS1, and OS2 are oversampling configuration signals, and all grounding cancels the oversampling function of AD7606. STM32F103C8T6 is the control core of the signal acquisition module, and its program running cycle is 1ms. After the data is packaged, it is sent to the module data output terminal through the serial port. The 8MHz passive crystal oscillator ensures the time accuracy of the program running cycle. The data output end includes three parts: 485 interface, USB interface and wireless Bluetooth. Among them, the 485 interface uses the Max485 chip to convert the serial port TTL level into a 5V 485 signal, the USB interface uses the CP2102 chip to convert the serial port signal into a USB signal, and the wireless Bluetooth module uses the CH9140-SER low-power Bluetooth module produced by Qinheng Company, which uses the Bluetooth V4.2 Bluetooth protocol. The power interface is connected to the power supply module to power the signal acquisition module.

[0033] The power supply module is used to power the entire device. The input power of the power input interface is a 9-16V DC power supply, and the output voltages are -2.5V, +2.5V, +3.3V and +5V. After the input power supply +Vin passes through two K7809-500R3 modules, it is inverted and stepped down to ±9V voltage. Among them, the +9V voltage is converted into +5V and +2.5V voltage signals by two TPS7A4901 power chips, and is converted into a +3.3V voltage signal by an AMS1117-3.3 chip. The -9V voltage is converted into a -2.5V voltage signal by a TPS7A3001 power chip. All voltage signals are connected to the output port of the power supply module. The output voltages of TPS7A4901 and TPS7A3001 are configured using feedback resistors. The configuration scheme is as follows Figure 6 As shown, the output voltage With feedback resistor and The calculation relationship is .

[0034] Among them, take ,when hour, ;when hour, . It is a chip ceramic capacitor packaged as C0603, and its capacitance is given in the figure.

Claims

1. A real-time synchronous measurement device for force and temperature signals in ultra-precision cutting process, characterized in that: It includes a diamond self-sensing temperature-sensing tool, which is fixed to a tool holder through a piezoelectric flexible force-measuring hinge. The piezoelectric flexible force-measuring hinge and the tool holder are insulated. The tool holder is also provided with a signal pre-processing module, a signal acquisition module, and a power supply module. The power supply module is used to supply power and provide accurate reference voltage for the signal pre-processing module and the signal acquisition module; The piezoelectric flexible force measuring hinge is used for decoupling the three-axis cutting force, projecting the cutting force onto the three axes of the spatial coordinate system X, Y and Z, and is converted into a weak charge signal by the detection sensor and output to the signal pre-processing module; The original weak charge signal and voltage signal are output by the piezoelectric flexible force measuring hinge and the diamond self-sensing temperature tool. After being processed by the signal pre-processing module, they are synchronously collected and output in real time by the signal acquisition module, realizing the synchronous and accurate measurement of ultra-precision process cutting temperature and three-axis cutting force.

2. The device for real-time synchronous measurement of force and temperature signals during ultra-precision cutting process according to claim 1, characterized in that: The diamond self-sensing temperature tool is used for cutting temperature measurement, and its resistance value is measured and then converted into a temperature signal through the temperature-resistance function relationship.

3. The real-time synchronous measurement device for force and temperature signals in ultra-precision cutting process according to claim 1 is characterized in that: The piezoelectric flexible force measuring hinge is fixed to the tool holder through a connecting piece, an insulating layer is provided between the piezoelectric flexible force measuring hinge and the tool holder, and the insulating layer is provided with a through hole that makes way for the connecting piece.

4. The real-time synchronous measurement device for force and temperature signals during ultra-precision cutting process according to claim 3 is characterized in that: The connector is covered with an insulating film, the tool holder is provided with a fixing hole for matching the connector, the insulating film is located between the connector and the wall of the fixing hole, the end of the connector is located outside the fixing hole, and an insulating gasket is provided between the end of the connector and the tool holder.

5. The real-time synchronous measurement device for force and temperature signals in ultra-precision cutting process according to claim 2, characterized in that: The signal pre-processing module includes a charge amplifier unit, a voltage amplifier unit and a microampere-level constant excitation current output unit. The charge amplifier unit corresponds to the detection sensor one by one and is used to measure the weak charge signal output by the detection sensor.

6. The device for real-time synchronous measurement of force and temperature signals during ultra-precision cutting process according to claim 5, characterized in that: The voltage amplifier unit is a differential amplifier circuit with the AD8421 instrument amplifier chip as the core, and the microampere-level constant excitation current output unit is a constant current source circuit with the LM334 power chip as the core. The negative temperature coefficient silicon diode 1N457 is used to compensate for the temperature drift of the LM334 power chip when it is working.

7. The device for real-time synchronous measurement of force and temperature signals during ultra-precision cutting process according to claim 5, characterized in that: The charge amplifier unit includes an LM7721 precision operational amplifier chip and is designed with an input stage protection loop and a shielding cover to shield environmental electromagnetic interference. The charge signal is amplified and converted into a voltage signal in the range of -2.5V to +2.5V and output to the signal acquisition module; the charge amplifier unit uses a 10nF polypropylene film feedback capacitor to ensure system stability.

8. The device for real-time synchronous measurement of force and temperature signals during ultra-precision cutting process according to claim 1, characterized in that: The signal acquisition module includes an AD7606 eight-channel bipolar analog-to-digital conversion chip and an STM32F103C8T6 microprocessor. The AD7606 converts six-channel voltage signals into digital signals and sends them to the STM32 via SPI. The STM32 sends the received data to the data output terminal via UART.

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