Method and apparatus for measuring cutting force and cutting temperature for solid propellant shaping

Abstract

The application relates to a cutting force and cutting temperature measuring method and device for solid propellant shaping, and belongs to the field of solid rocket engine propellant shaping processing. The cutting force and cutting temperature measuring device comprises a force and temperature measuring cutter, a surface acoustic wave temperature measuring module and a surface acoustic wave force measuring module which are installed on a cutter head of the shaping cutter and are used for monitoring the cutting temperature and the cutting force of the cutter in real time; and a radio frequency reader system which is connected with a signal of the force and temperature measuring cutter, receives, transmits and processes signals transmitted by the force and temperature measuring cutter. The application adopts the surface acoustic wave sensing technology, realizes wireless and passive measurement of the cutting force and the cutting temperature in the solid propellant shaping processing, has good explosion-proof performance and convenient use; the radio frequency reader of the application adopts the software radio technology, has a short equipment development cycle, low cost and is convenient for system maintenance and upgrading; the application can perform coherent averaging on echo signals, improves the signal signal-to-noise ratio, has higher frequency estimation resolution and stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solid rocket engine propellant shaping processing, and particularly relates to a cutting force and cutting temperature measuring method and device for solid propellant shaping. BACKGROUND

[0002] In the field of aerospace, solid rocket engine, as the power device of various launch vehicles and missile weapons, provides strong power support for their safe flight, and is often referred to as the heart of launch vehicles and missiles. Solid propellant shaping process is an important link in its preparation process. At present, the propellant shaping work in China is generally artificial, but solid propellant is a flammable and explosive dangerous goods. The accumulated heat generated by friction and cutting force in the shaping process can easily cause safety accidents once it reaches the ignition point. Therefore, it is necessary to monitor the cutting temperature and cutting force of the shaping process in real time.

[0003] In recent years, in order to realize real-time monitoring of cutting temperature and cutting force in the shaping process, there have been many technical innovations. For example, Chinese patent application CN201420795203.X introduces a solid propellant shaping tool assembly, which uses platinum resistance to realize accurate temperature measurement and real-time monitoring of tool temperature; Chinese patent application CN201810705611.4 introduces an ultrasonic auxiliary shaping tool for solid fuel, which uses ultrasonic vibration to change the traditional cutting mode and reduce the temperature during processing; Chinese patent application CN202311831392.1 introduces a man-machine collaborative remote operation system and method for solid propellant shaping processing and deviation compensation, which uses a miniature infrared temperature measurement sensor to monitor the temperature of the shaping cutting area. The above temperature measurement methods all use traditional temperature measurement sensors. Platinum resistance temperature sensor is a wired active sensor, which needs to use connecting wires. The existence of connecting wires limits the flexibility of shaping processing, and active sensors can produce electric spark discharge due to static electricity, short circuit and other factors, which has great safety hazards. Infrared temperature measurement sensor is easily blocked by cutting chips, affecting the temperature measurement effect.

[0004] The surface acoustic wave temperature sensor is made by using the characteristic that the surface acoustic wave propagation speed changes with the physicochemical properties of the piezoelectric substrate. The surface acoustic wave temperature sensor has the characteristics of wireless passive, high sensitivity and excellent explosion-proof performance, and is very suitable for solid propellant cutting temperature measurement occasions. In recent years, the surface acoustic wave sensor has been applied in the field of mechanical processing. For example, Chinese patent application CN201310078061.5 introduces an intelligent cutter based on a surface acoustic wave sensing system, which is applied to a turning tool blade to realize cutting force and cutting temperature measurement; Chinese patent application 202410799129.7 cutter with surface acoustic wave sensor, cutter stress monitoring method and system; the above method does not consider the cutting force and cutting temperature change characteristics, and simultaneous measurement of cutting force and cutting temperature is prone to signal crosstalk.

[0005] The surface acoustic wave temperature sensor needs a radio frequency reader for identification, and the traditional radio frequency reader hardware circuit is complex and difficult to upgrade and maintain. Therefore, a software radio platform is used to develop a surface acoustic wave radio frequency reader. SUMMARY

[0006] The purpose of the present application is to provide a cutting force and cutting temperature measurement method and device for solid propellant shaping, to realize wireless and passive real-time monitoring of cutting temperature and cutting force in solid propellant shaping processing, and to solve the problems of poor processing convenience and safety hazards of existing force and temperature measuring cutters.

[0007] The technical solution adopted by the present application is:

[0008] A cutting force and cutting temperature measurement device for solid propellant shaping, comprising

[0009] The force and temperature measuring cutter comprises a surface acoustic wave temperature measuring module and a surface acoustic wave force measuring module installed on the shaping cutter head, and is used for real-time monitoring of the cutting temperature and cutting force of the cutter;

[0010] The radio frequency reader system is connected with the force and temperature measuring cutter signal, and transmits, receives and processes the signals transmitted by the force and temperature measuring cutter.

[0011] A method for measuring cutting force and cutting temperature of solid propellant shaping device, the surface acoustic wave temperature sensor radio frequency reading steps are as follows:

[0012] Step 1: The host computer generates a digital baseband signal;

[0013] Step 2: The software radio platform converts the digital baseband signal to digital-analog;

[0014] Step 3: The software radio platform generates a carrier signal and mixes it with the baseband signal to obtain an excitation signal;

[0015] Step 4: the software radio platform transmits an excitation signal through the copper rod antenna;

[0016] Step 5: the acoustic surface wave temperature sensor or the acoustic surface wave strain gauge of the shaping cutter head is excited to emit a return signal;

[0017] Step 6: the software radio platform receives the return signal through the copper rod antenna;

[0018] Step 7: the software radio platform down-converts the return signal to obtain a return baseband signal;

[0019] Step 8: the software radio platform analog-to-digital converts the analog baseband signal and uploads to the host computer storage;

[0020] Step 9: steps 1 to 8 are repeated until 50 return signals are collected;

[0021] Step 10: the host computer performs coherent averaging and frequency estimation on the 50 return signals;

[0022] Step 11: steps 1 to 10 are repeated until all acoustic surface wave temperature sensors or acoustic surface wave strain gauges are read;

[0023] Step 12: the host computer analyzes and demodulates the data to realize force and temperature measurement.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application uses acoustic surface wave sensing technology to realize wireless and passive measurement of solid propellant shaping machining cutting force and cutting temperature, and has good explosion-proof property and use convenience;

[0026] 2. The radio frequency reader of the present application uses software radio technology, has short equipment development cycle, low cost, and is convenient for system maintenance and upgrading;

[0027] 3. The present application can perform coherent averaging on the return signal, improve the signal-to-noise ratio, and has higher frequency estimation resolution and stability.

[0028] 4. The software radio platform of the present application continuously transmits excitation signals and receives sensor return signals, and a single-pole double-throw radio frequency switch controls the transmission and reception time sequence to realize time-sharing use of one antenna. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is an exploded view of the force and temperature measuring cutter of the present application;

[0030] Figure 2 is a schematic diagram of the radio frequency reader system of the present application;

[0031] Figure 3is the surface acoustic wave sensor array diagram of the present application;

[0032] Figure 4 is Figure 3 the A-A sectional view of

[0033] Figure 5 is the temperature measuring impedance matching and power distribution circuit of the present application;

[0034] Figure 6 is the schematic diagram of the force measuring sensitive unit of the present application;

[0035] Figure 7 is the B-B sectional view of Figure 6

[0036] Figure 8 is the force measuring impedance matching and power distribution circuit of the present application;

[0037] Figure 9 is the radio frequency reading flow chart of the surface acoustic wave temperature sensor of the present application;

[0038] 1, the surface acoustic wave temperature sensor array; 2, the shaping cutter head; 3, the impedance matching and power distribution circuit board; 4, the force measuring sensitive unit; 5, the handle; 6, the fastening screw; 7, the cover plate; 8, the FPC antenna; 9, the copper bar antenna; 10, the single-pole double-throw radio frequency switch; 11, the software radio platform; 12, the host computer; 13, the trapezoidal hole; 14, the force measuring sensitive unit support beam; 15, the force measuring sensitive unit sensitive beam; 16, the surface acoustic wave strain gauge. DETAILED DESCRIPTION

[0039] In order to better understand the purpose, structure and function of the present application, the present application will be further described in detail below in combination with the drawings.

[0040] As Figure 1 , Figure 2 shown, the present application provides a cutting force and cutting temperature measuring device for solid propellant shaping, comprising

[0041] The force and temperature measuring cutter comprises a surface acoustic wave temperature measuring module and a surface acoustic wave force measuring module installed on the shaping cutter head 2, for real-time monitoring of the cutter cutting temperature and cutting force.

[0042] The radio frequency reader system is connected with the force and temperature measuring cutter signal, receives, transmits and processes the signal transmitted by the force and temperature measuring cutter.

[0043] As Figure 1 ​As shown, the surface acoustic wave temperature measurement module comprises a surface acoustic wave temperature sensor array 1, a shaped tool bit 2, and a temperature measurement impedance matching and power distribution circuit; the shaped tool bit 2 is close to the position of the cutting edge and is deposited with the surface acoustic wave temperature sensor array 1, the surface acoustic wave temperature sensor array 1 is connected to the temperature measurement impedance matching and power distribution circuit through an extremely thin signal line covered with an insulating film, and the temperature measurement impedance matching and power distribution circuit is connected to the FPC antenna 8.

[0044] The temperature measurement impedance matching and power distribution circuit is as shown in Figure 5 .

[0045] The temperature measurement impedance matching and power distribution circuit and the force measurement impedance matching and power distribution circuit are integrated on the impedance matching and power distribution circuit board 3.

[0046] The impedance matching and power distribution circuit board 3 is installed on the shaped tool bit 2.

[0047] The FPC antenna 8 is installed on the handle 5 through the cover plate 7 and the fastening screw 6.

[0048] The surface acoustic wave temperature sensor array 1 is five surface acoustic wave temperature sensors with a piezoelectric film as a substrate,

[0049] As shown in Figure 3 , Figure 4 , the surface acoustic wave temperature sensor comprises a piezoelectric film, an interdigital electrode, and a protective layer, a 2um thick piezoelectric film is deposited at the temperature measurement array of the cutting area of the shaped tool bit 2, the interdigital electrode is arranged between the piezoelectric film and the protective layer, and the interdigital electrode is connected to the temperature measurement impedance matching and power distribution circuit through a signal line.

[0050] Further, the piezoelectric substrate is a metal substrate;

[0051] Further, the piezoelectric film is an AlN or ZnO film;

[0052] Further, the interdigital electrode material is Pt or Al;

[0053] Further, the protective layer is diamond, SiO2, or Al2O3;

[0054] Further, the surface acoustic wave temperature sensor array 1 is a 1x5 array parallel to the cutting edge line of the shaped tool bit 2 and 5mm away.

[0055] As shown in Figure 1 , the shaped tool bit 2 is a shovel-shaped, and the 1x5 surface acoustic wave temperature sensor array 1 is deposited along the cutting edge of the shaped tool bit 2 through micro-nano processing.

[0056] As shown in Figure 1 , Figure 2As shown, the surface acoustic wave force measuring module includes a force measuring sensitive unit 4 arranged between the shaping tool bit 2 and the handle 5; the force measuring sensitive unit 4 is a metal tube as a whole, and the two ends of the force measuring sensitive unit 4 are connecting parts, which are external threads and internal threads respectively, for connecting the shaping tool bit 2 and the handle 5, and the middle of the force measuring sensitive unit 4 is a sensitive part, which is a thin-walled beam structure. The material of the force measuring sensitive unit 4 is 40Cr.

[0057] As shown in Figure 6 , Figure 7 , the force measuring sensitive unit 4, two mutually parallel planes are milled on the symmetric positions of the metal tube side wall, two trapezoidal holes 13 are opened on the two planes, and the metal tube is rotated by 90° along the axis to open two trapezoidal holes 13 on the side wall, forming six support beams 14 and two sensitive beams 15. The beams between the trapezoidal holes and milled by the plane are sensitive beams 15, and the remaining beams are support beams 14. Two mutually perpendicular surface acoustic wave strain gauges 16 are pasted on each sensitive beam 15. Four surface acoustic wave strain gauges 16 are connected to the force impedance matching and power distribution circuit, and further connected to the FPC antenna 8.

[0058] Further, the piezoelectric material of the surface acoustic wave strain gauge 16 is ST tangential quartz sheet;

[0059] Further, the interdigital electrode material of the surface acoustic wave strain gauge 16 is Al;

[0060] Further, the surface acoustic wave strain gauge 16 adopts full quartz packaging;

[0061] Further, the force impedance matching and power distribution circuit, as shown in Figure 8 ;

[0062] Further, in order to avoid crosstalk, based on the cutting temperature and cutting force variation characteristics, the frequency band of the surface acoustic wave temperature sensor is 2.4GHz, and the frequency band of the surface acoustic wave strain gauge 16 is 433MHz.

[0063] As shown in Figure 2 , the radio frequency reader system includes a copper rod antenna 9, a single-pole double-throw radio frequency switch 10, a software radio platform 11 and an upper computer 12;

[0064] The upper computer 12 is signal connected with the software radio platform 11, the software radio platform 11 adopts a double-transmitting and double-receiving full-duplex platform, and each pair of receiving end and transmitting end of the software radio platform 11 is isolated by the single-pole double-throw radio frequency switch 10. The software radio platform 11 is signal connected with the copper rod antenna 9.

[0065] The software radio platform 11 selects USRP B210, and the single-pole double-throw radio frequency switch 10 selects QM-SW-2ST. The USRP B210 is developed by GNURadio.

[0066] To realize isolation of the transmitting end and the receiving end and reduce the transceiver crosstalk, the USRP B210 is closed for receiving, continuously transmits a signal, then is closed for transmitting, and continuously receives a signal. However, the transceiver switching of the USRP B210 needs about 10 microseconds, and the echo signal of the surface wave temperature sensor or the surface acoustic wave strain gauge 16 usually lasts about 15 microseconds. If the USRP B210 is used for transceiver switching, the signal quality of the first 10 microseconds of the echo signal will be lost. Therefore, the USRP B210 is continuously used for transmitting and receiving, the transmitting end and the receiving end are isolated by the QM-SW-2ST radio frequency switch, the transceiver switching is realized at the nanosecond level, and the loss of the echo signal is reduced as much as possible. Meanwhile, the USRP B210 is a double-transmitting and double-receiving full-duplex platform, and can simultaneously access the force measuring module and the temperature measuring module.

[0067] As shown in Figure 9 The software radio platform 11 includes

[0068] The transmitting module generates a baseband signal through a signal source, the USRP signal transmitting module mixes the carrier signal and the baseband signal to obtain an excitation signal and transmits the excitation signal;

[0069] The receiving module receives the echo signal through the USRP signal receiving module, down-converts the echo signal to a baseband signal, and transmits the baseband signal to the host computer after digital-analog conversion. The host computer performs coherent averaging, frequency estimation, and temperature demodulation on the echo signal, and realizes temperature measurement.

[0070] The control program of the software radio platform 11 includes a receiving program and a transmitting program. The transmitting program controls the software radio platform 11 to transmit the excitation signal, and the receiving program controls the software radio platform 11 to receive the sensor echo signal and demodulate the temperature / strain. In addition, the control program has a feedback link, that is, the resonant frequency is fed back to the transmitting flow chart as the next sensor identification excitation frequency after the resonant frequency is obtained.

[0071] The echo signal of the surface wave temperature sensor or the surface acoustic wave strain gauge 16 is mixed with random noise, which will affect the accuracy of subsequent frequency estimation. To reduce the influence of random noise, 50 segments of echo signals are subjected to coherent averaging.

[0072] The receiving program of the receiving module processes the echo signal and demodulates the temperature / strain, including coherent averaging of multiple segments of echo signals to reduce random noise interference, and preferably coherent averaging of 50 segments of echo signals. The calculation formula is as follows:

[0073]

[0074] where is the coherent average echo signal, y i (t) is the original echo signal, u(t) is the useful signal, n i (t) is the random noise signal.

[0075] As Figure 9 shown, the radio frequency reading steps of the surface acoustic wave temperature sensor are as follows:

[0076] Step 1: the host computer 12 generates a digital baseband signal;

[0077] Step 2: the software radio platform 11 converts the digital baseband signal to an analog signal;

[0078] Step 3: the software radio platform 11 generates a carrier signal and mixes it with the baseband signal to obtain an excitation signal;

[0079] Step 4: the software radio platform 11 transmits the excitation signal through the copper rod antenna 9;

[0080] Step 5: the surface acoustic wave temperature sensor or surface acoustic wave strain gauge 16 of the shaped tool cutter head 2 is excited to emit an echo signal;

[0081] Step 6: the software radio platform 11 receives the echo signal through the copper rod antenna 9;

[0082] Step 7: the software radio platform 11 down-converts the echo signal to obtain an echo baseband signal;

[0083] Step 8: the software radio platform 11 converts the analog baseband signal to a digital signal and uploads it to the host computer 12 for storage;

[0084] Step 9: repeat steps 1 to 8 until 50 echo signals are collected;

[0085] Step 10: the host computer 12 performs coherent averaging and frequency estimation on the 50 echo signals;

[0086] Step 11: repeat steps 1 to 10 until all surface acoustic wave temperature sensors or surface acoustic wave strain gauges 16 are read;

[0087] Step 12: the host computer 12 analyzes and demodulates the data to realize force measurement and temperature measurement.

[0088] It is to be understood that the present application is described by way of example only, and that modifications or alterations can be made to the features and embodiments described without departing from the spirit and scope of the application. In addition, modifications can be made to the features and embodiments described to accommodate specific situations and materials without departing from the spirit and scope of the application. Accordingly, the application is not limited to the specific embodiments disclosed herein, but rather, the scope of the application includes all embodiments falling within the scope of the claims.

Claims

1. A device for measuring cutting force and cutting temperature for solid propellant shaping, characterized in that: include The force and temperature measuring tool includes a surface acoustic wave temperature measuring module and a surface acoustic wave force measuring module installed on the cutting tool head (2) for real-time monitoring of the tool cutting temperature and cutting force; The surface acoustic wave force measurement module includes a force-sensing unit (4) disposed between the shaping tool head (2) and the handle (5); the force-sensing unit (4) is a metal tube, with connecting parts at both ends for connecting the shaping tool head (2) and the handle (5), and the sensing part in the middle of the force-sensing unit (4). The force-sensing unit (4) has two parallel planes milled out at symmetrical positions on the side wall of the metal tube, and two trapezoidal holes (13) are opened on the two planes. The metal tube is rotated 90° along the axis and two more trapezoidal holes (13) are opened on the side wall to form six support beams (14) and two sensitive beams (15). Two mutually perpendicular surface acoustic wave strain gauges (16) are attached to each sensitive beam (15). The four surface acoustic wave strain gauges (16) are connected to the force-sensing impedance matching and power distribution circuit, and then connected to the FPC antenna (8). The radio frequency reader system is connected to the force and temperature measuring tool signal, and receives, transmits and processes the signals transmitted by the force and temperature measuring tool.

2. The cutting force and cutting temperature measuring device for solid propellant shaping according to claim 1, characterized in that: The surface acoustic wave temperature measurement module includes a surface acoustic wave temperature sensor array (1), a shaping tool head (2), and a temperature measurement impedance matching and power distribution circuit; the surface acoustic wave temperature sensor array (1) is deposited near the tip of the shaping tool head (2), the surface acoustic wave temperature sensor array (1) is connected to the temperature measurement impedance matching and power distribution circuit, and the temperature measurement impedance matching and power distribution circuit is connected to the FPC antenna (8).

3. The cutting force and cutting temperature measuring device for solid propellant shaping according to claim 2, characterized in that: The shaping tool head (2) is shovel-shaped, and a surface acoustic wave temperature sensor array (1) is deposited along the tip of the shaping tool head (2) through micro-nano processing.

4. The cutting force and cutting temperature measuring device for solid propellant shaping according to claim 1, characterized in that: The radio frequency reader system includes a copper rod antenna (9), a single-pole double-throw radio frequency switch (10), a software radio platform (11), and a host computer (12). The host computer (12) is connected to the software radio platform (11) via signal. The software radio platform (11) is a dual-transmit and dual-receive full-duplex platform. Each pair of receivers and transmitters of the software radio platform (11) is isolated by a single-pole double-throw radio frequency switch (10). The software radio platform (11) is connected to the copper rod antenna (9) via signal.

5. The cutting force and cutting temperature measuring device for solid propellant shaping according to claim 4, characterized in that: The software radio platform (11) includes The transmitting module generates a baseband signal through a signal source, and then mixes the carrier signal with the baseband signal to obtain an excitation signal and transmits it. The receiving module receives the echo signal, down-converts it to a baseband signal, performs digital-to-analog conversion on the baseband signal, and transmits it to the host computer for processing. The host computer performs coherent averaging, frequency estimation, and temperature demodulation on the echo signal to achieve temperature measurement.

6. The cutting force and cutting temperature measuring device for solid propellant shaping according to claim 5, characterized in that: The receiving module's receiving program performs coherent averaging on 50 echo signals, calculated using the following formula: in The echo signal after coherent averaging The original echo signal, Useful signal It is a random noise signal.

7. A method for measuring cutting force and cutting temperature using the cutting force and cutting temperature measuring device for solid propellant shaping according to any one of claims 1 to 6, characterized in that: The steps for RF reading of a surface acoustic wave (SAW) temperature sensor are as follows: Step 1: The host computer (12) generates a digital baseband signal; Step 2: The software radio platform (11) converts the digital baseband signal from digital to analog; Step 3: The software radio platform (11) generates a carrier signal and mixes it with the baseband signal to obtain the excitation signal; Step 4: The software radio platform (11) transmits an excitation signal via the copper rod antenna (9); Step 5: The surface acoustic wave temperature sensor or surface acoustic wave strain gauge (16) of the shaping tool head (2) is excited and emits an echo signal; Step 6: The software radio platform (11) receives the echo signal through the copper rod antenna (9); Step 7: The software radio platform (11) down-converts the echo signal to obtain the echo baseband signal; Step 8: The software radio platform (11) converts the analog baseband signal to digital and uploads it to the host computer (12) for storage; Step 9: Repeat steps 1 to 8 until 50 echo signals are acquired; Step 10: The host computer (12) performs coherent averaging and frequency estimation on the 50 echo signals; Step 11: Repeat steps 1 to 10 until all surface acoustic wave temperature sensors and surface acoustic wave strain gauges (16) have been read; Step 12: The host computer (12) analyzes and demodulates the data to realize force and temperature measurement.

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