A self-powered force measuring intelligent tool handle based on electromagnetic induction

Abstract

The present invention relates to the field of mechanical processing and manufacturing, and specifically to an intelligent tool handle that realizes online monitoring of forces during cutting processing through electromagnetic induction self-powering. The present invention adopts electromagnetic induction self-powering to make it possible for the intelligent tool handle to be used continuously for a long time, thereby improving the convenience of use; a four-dimensional force measurement decoupling method of the tool tip point is realized by building a Wheatstone bridge using a resistance strain gauge, providing high-precision four-dimensional force measurement results, which helps to accurately grasp the force conditions of the tool during the cutting process; it provides rich data support for tool status monitoring, real-time control and adjustment during the processing process; the integration of the intelligent tool handle is greatly improved by embedding a rotor at the taper handle and a compact printed circuit board, while optimizing the cutting scheme to reduce the stiffness loss of the tool handle; the intelligent tool handle of the present invention has great potential for integrating more sensors to obtain more processing parameters, and has broad application prospects in related fields such as cutting processing, tool design and process optimization.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing and manufacturing, and in particular to an intelligent tool handle that realizes online monitoring of forces in a cutting process through electromagnetic induction self-power supply. Background Art

[0002] In the cutting process, due to the lack of real-time monitoring of the interaction force between the tool and the workpiece, it is often difficult to accurately control the machining process. In order to solve these problems, a type of force measuring tool holder that can realize online monitoring of the machining process has gradually emerged. The four-dimensional force information of this type of tool holder is used to determine whether the machining process is proceeding normally, adjust the tool processing parameters in real time, evaluate and predict the tool status, and optimize and improve the machining process. It plays a key role in achieving efficient, accurate and reliable machining operations. However, due to the high price of the product, it is often used in experimental research rather than in actual product processing. Usually, the signal processing circuit of the force measuring tool holder has a low integration level, which makes the tool holder bulky and easy to cause interference during the machining process. In addition, most tool holders rely on battery power, which limits long-term continuous monitoring during the machining process. Some force measuring tool holders also have insufficient stiffness due to the need for sensor unit structure; therefore, real-time monitoring of cutting force during cutting has always been a difficult problem, which brings inconvenience to the cutting process. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a highly integrated intelligent tool handle based on electromagnetic induction self-power supply technology and capable of realizing four-dimensional force measurement during cutting processing.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] It includes a tool handle body arranged on the main shaft, a magnet bracket, a magnet, a copper coil, a tapered handle annular hole, a rectifier and voltage-stabilizing circuit, a tool handle strain gauge pasting surface, a uniaxial temperature compensation strain gauge, a uniaxial working strain gauge, a torque strain gauge, and a bridge signal processing circuit; the magnet bracket is provided with a wedge-shaped groove, and the magnet is connected to the magnet bracket through the wedge-shaped groove; the magnet bracket is arranged on the side of the interface between the main shaft and the tool handle body, and the magnet bracket is arranged on the main shaft end face mounting cover through the bracket fastening screw; the copper coil is arranged in the tapered handle annular hole; the rectifier and voltage-stabilizing circuit is arranged on the tool handle body; the uniaxial temperature compensation strain gauge, the uniaxial working strain gauge, and the torque strain gauge are arranged on the tool handle strain gauge pasting surface for building a Wheatstone bridge sensing circuit; the bridge signal processing circuit is arranged on the tool handle body.

[0006] The rectifier and voltage stabilizing circuit includes 6 circuit board lead interfaces P15, capacitors C94-C97, C99-C100, C103-C105, resistors R116-R123, temperature measuring resistor RT1, LED lamp D6 and wireless power receiver U13; the circuit board lead interface P15 includes 6 interfaces; the wireless power receiver U13 includes interfaces CLAMP1, COMM1, AC1, AC2, BOOT1, BOOT2, CLAMP2, COMM2, OUT, CHG, ILIM, FOD, RECT, TS, EN1, EN2; one end of the capacitor C96 is connected in parallel with the capacitors C99 and C103 and connected to the AC1 interface of U13, and the other end of C96 is connected to the BOOT1 of U13; the other end of the capacitor C99 is connected to the interface CLAMP1 of U13; the other end of the capacitor C103 is connected to the interface COMM1 of U13; one end of the capacitor C97 is connected in parallel with the capacitors C100 and C104 and connected to the AC2 interface of U13, and the other end of C97 is connected to the BOOT2 of U13; the other end of the capacitor C100 is connected to the interface CLAMP2 of U13; The other end of capacitor C104 is connected to the interface COMM2 of U13; the positive pole of the LED lamp D6 is connected to the interface OUT of U13, and the negative pole is connected to the interface CHG of U13; one end of the resistor R116 is connected to the interface ILIM of U13, and the other end is connected to the resistors R117 and R121, and the interface FOD of U13; one end of the resistor R117 is connected to the interface FOD of U13, and the other end is connected to the interface RECT of U13 and the filter capacitor C105; one end of the resistor R121 is connected to the interface FOD of U13, and the other end is connected to GND; one end of the capacitor C105 is connected to RECT of U13, and the other end is connected to GND; one end of the resistor R119 is connected to VOUT, and the other end is connected to resistor R122 and interface 5 of P15, and the other end of resistor R122 is connected to GND; one end of the resistor R120 is connected to VOUT, and the other end is connected to resistor R123 and interface 6 of P15, and the other end of resistor R123 is connected to GND; the temperature measuring resistor RT1 is connected to interface TS of U13; interfaces 1 and 2 of P15 are connected to GND, interfaces 3 and 4 are connected to voltage source VOUT, interface 5 is connected to interface EN1 of U13, and interface 6 is connected to interface EN2 of U13.

[0007] It also includes a bridge signal processing board, a power management board, a main control board, a WiFi board, a collet, a nut and a milling cutter; four circuit board mounting platforms are arranged in the middle of the handle body, and the circuit board mounting platforms are provided with an upper row of fastening threaded through holes and a lower row of fastening threaded blind holes; the signal processing board, the power management board, the main control board and the WiFi board are arranged on the four circuit board mounting platforms respectively through an upper row of fastening screws and a lower row of fastening screws, and the upper row of fastening screws and the lower row of fastening screws are matched with the upper row of fastening threaded through holes and the lower row of fastening threaded blind holes respectively; the tapered handle A coil lead hole is provided on the circular hole, a circuit board lead groove is provided between adjacent circuit board mounting platforms, and a circuit board lead hole is provided on the circuit board mounting platform that matches the power management board; the induced current in the copper coil is transmitted to the power management board, the bridge signal processing board, the main control board, and the WiFi board through the coil lead hole, the circuit board lead hole, and the circuit board lead groove; the collet, the nut, and the milling cutter are arranged in sequence at the lower end of the handle body, the rectifier and voltage stabilizing circuit is arranged on the power management board, and the bridge signal processing circuit is arranged on the bridge signal processing board.

[0008] The Wheatstone bridge is used to measure the four-dimensional force at the tool tip, and the steps are as follows:

[0009] ① Determine the structure of the elastic element of the handle;

[0010] 101. Four or more evenly distributed planes are arranged in the circumferential direction of the middle part of the shank, with the axial direction being the length direction of the plane and the other vertical direction being the width direction of the plane;

[0011] 102. With the bottom end of the cone handle as a reference, the distances between the first and last ends of the plane in the length direction and the plane of the bottom end of the cone handle are taken as two parameters; the width of the plane is taken as the third parameter;

[0012] ② Carry out multi-parameter and multi-objective optimization;

[0013] 201. Taking the three parameters as optimization parameters and the axial and radial stiffness of the tool holder as optimization targets, UG&ANSYS joint simulation optimization is performed;

[0014] ③ Create a four-dimensional force measurement decoupling model based on resistance strain gauges and fixed resistors;

[0015] 301. Establish a Wheatstone bridge sensing circuit, including a resistance strain gauge (uniaxial strain gauge, torque strain gauge) and a fixed value resistor, denoted by R a , R b , R c , R d Where R a , R b and R c , R d Two bridge circuits are formed respectively, and the resistance change of each strain gauge is recorded as ΔRa , ΔR b , ΔR c , ΔR d , bridge output voltage V O With the bridge input voltage V S The relationship between them is:

[0016]

[0017] 302. Strain ε, resistance change rate Strain gauge sensitivity K S The relationship is:

[0018]

[0019] 303. Replace the resistance change rate in (a) with strain and sensitivity:

[0020]

[0021] where ε a , ε b , ε c , ε d Represent the strain of each strain gauge respectively;

[0022] 304. Two uniaxial strain gauges are respectively arranged on each cutting surface, wherein the first strain gauge is used as a uniaxial working strain gauge, the sensitive grid direction of the working strain gauge is parallel to the axis direction of the tool handle, and is arranged above the center of the plane; the second strain gauge is used as a uniaxial temperature compensation strain gauge, the sensitive grid direction is perpendicular to the axis direction, and is arranged above the working strain gauge, and the strain gauge on each cutting surface and two fixed resistors form a Wheatstone bridge; 305. The sum of the bridge output values ​​between the two cutting surfaces of the tool handle elastic element relative to each other is the change value caused by the single load of the axial force, and the subtraction of the bridge values ​​is the change value caused by the single load of the radial force along the direction of the line connecting the two surfaces; 306. Two torque strain gauges are arranged on two opposite cutting surfaces to form a Wheatstone bridge circuit, and the torque strain gauge is arranged below the center of the plane;

[0023] ④Determine the bridge signal processing circuit;

[0024] 401. Setting amplification gain for half bridge and full bridge based on bridge output voltage;

[0025] The bridge signal processing circuit includes strain gauge interfaces P10, P11 and P13, lead interface P12 between the bridge board and the main control board, resistors R45-R99, R102, R105-R115, capacitors C42-C43, C46-C56, C61-C66, C69-C80, C83-C91, triodes TVS5-TVS10, amplifiers U8, U10 and U12, analog-to-digital conversion chip U9, and reference voltage chip U11; the strain gauge interfaces P10, P11 and P13 each include 6 interfaces; the lead interface P12 between the bridge board and the main control board includes 10 interfaces; the amplifiers U8, U10 and U12 each include 16 interfaces; the analog The digital conversion chip U9 includes 33 interfaces; the strain gauge interface P11 is connected, and one end of the strain gauge resistor R85 is connected to resistors R84 and R86, and the other end is connected to resistor R82; both ends of resistor R82 are respectively connected to capacitors C73 and C74 and then grounded AGND, the other end of resistor R82 is connected to resistor R83, and the output signal is connected to interface 1IN1+ of U10; one end of strain gauge resistor R97 is connected to resistors R92 and R102 and the other end is connected to resistor R98, both ends of resistor R98 are respectively connected to capacitors C79 and C80 and then grounded AGND, the other end of resistor R98 is connected to resistor R99, and the output signal is connected to interface 10IN3+ of U10; interface 1 of P11 is input by voltage Vs+, and interface 2 Connect TVS7 tube, and connect it in series with resistors R78 and R79, and the other end of R79 is connected to interface 3IN2+ of U10; interface 4 of P11 is input by voltage Vs+, interface 5 is connected to TVS8 tube, and connects it in series with resistors R93 and R94, and the other end of R94 is connected to interface 12IN4+ of U10; interfaces 3 and 6 of P11 are connected to Vs-; the other ends of TVS7 tube and TVS8 tube are connected to AGND; the connection method of P10 and P13 is the same as that of P11; the amplifier U10 is connected, and the left end of resistor R80 is connected to Vref, and the other end is connected to interface 16IN1- of U10; one end of resistor R76 is connected to interface 16IN1- of U10, and the other end is connected to interface 15OUT1 of U10; One end of resistor R75 is connected to interface 16IN1- of U10, and the other end is connected to interface 4IN2- of U10; one end of resistor R77 is connected to interface 4IN2- of U10, and the other end is connected to interface 5OUT2 of U10; one end of resistor R81 is connected to interface 15OUT1 of U10, and the other end is connected to interface 4IN2- of U10; after the signals are amplified by amplifiers U8, U10 and U12, the outputs are OUT2, OUT4, OUT6, OUT8 and OUT10, which are respectively connected to 29, 28, 26, 25 and 27 of U9; interfaces 3 to 10 of P12 are connected corresponding to interfaces 7 to 14 of U9; the connection method of amplifiers U8 and U12 is the same as that of U10.

[0026] The tapered handle annular holes are arranged on the tapered handle of the handle body. The number of the tapered handle annular holes is 3 or more and they are evenly arranged along the circumference of the tapered handle.

[0027] The magnet has a longitudinal section in the shape of an arc.

[0028] The three optimized parameters result in a cutting plane size of 50 mm×30 mm, and a distance of 20 mm between the plane near the cone handle and the plane at the lower end of the cone handle.

[0029] The uniaxial working strain gauge is arranged 5 mm above the center of the plane and away from the bisector of the length direction, and the uniaxial temperature compensation strain gauge is arranged 5 mm above the working strain gauge; the torque strain gauge is arranged 5 mm below the center of the plane and away from the bisector of the length direction.

[0030] The positive effects of the present invention are as follows: the present invention proposes an implementation method of electromagnetic induction self-powering of an intelligent tool handle, so that the tool handle no longer needs an external power supply or battery to power the circuit, and the scheme of embedding the copper coil inside the tapered handle reduces the expansion of the external size of the tool handle, improves the integration of the tool handle, and reduces the possibility of processing interference of the intelligent tool handle; self-powering makes it possible for the intelligent tool handle to be used continuously for a long time, improving the convenience of use; it reduces energy consumption, which is in line with the development trend of energy conservation and environmental protection; the present invention discloses a method for realizing the decoupling of four-dimensional force measurement of the tool tip point by building a Wheatstone bridge with a resistance strain gauge for an intelligent tool handle, provides high-precision four-dimensional force measurement results, and helps to accurately grasp the force conditions of the tool during the cutting process; the present invention discloses a highly integrated intelligent tool handle force signal processing circuit, which integrates multiple modules into a small printed circuit board, reduces the volume and weight of the intelligent tool handle system, and improves the stability and reliability of the system; the present invention helps to simplify the tool handle structure and improve the work efficiency and performance of the system; the circuit of the present invention can simultaneously process force signals and transmit them wirelessly, can obtain information about the cutting process and tool status, and is convenient for tool use and cutting parameter optimization. The invention provides a more accurate data basis; the modular circuit design of the invention provides convenience for integrating more signals for the intelligent tool handle, and reduces the workload for circuit maintenance and updating; the invention is based on electromagnetic induction self-power supply and has the function of online monitoring of cutting force parameters during cutting processing, and has a compact structure and high integration; the invention breaks the shackles of limited use time caused by battery power supply of the intelligent tool handle; the invention provides rich data support for tool status monitoring, real-time control and adjustment during processing; the physical data-driven process optimization of the invention helps to reduce production costs and improve competitiveness; the invention helps to promote the development of intelligent and automated industrial production, and improve the production efficiency and product quality of the manufacturing industry; the rotor embedded in the tapered handle of the invention and the compact printed circuit board greatly improve the integration of the intelligent tool handle, and at the same time, the optimized cutting scheme of the tool handle reduces the stiffness loss of the tool handle, so that the external contour of the intelligent tool handle does not exceed the contour of the prototype tool handle, reducing the possibility of processing interference; the intelligent tool handle of the invention has great potential to integrate more sensors to obtain more processing parameters, and has broad application prospects in related fields such as cutting processing, tool design and process optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 An exploded view of the overall structure of the intelligent knife handle of the present invention;

[0033] Figure 2 It is the assembly diagram of the knife handle of the present invention;

[0034] Figure 3 This is a main structural diagram of the knife handle of the present invention;

[0035] Figure 4 It is a schematic diagram of the electromagnetic induction structure of the present invention;

[0036] Figure 5 This is a schematic diagram of pasting strain gauges for measuring four-dimensional forces on a tool handle of the present invention;

[0037] Figure 6 This is the circuit schematic diagram of the power management board;

[0038] Figure 7 This is the circuit schematic diagram of the bridge signal processing board.

[0039] In the figure: 1 tool handle body, 101 upper row of fastening screws, 102 lower row of fastening screws, 103 tapered handle ring hole, 104 coil lead hole, 105 circuit board lead groove, 106 circuit board lead hole, 107 strain gauge pasting surface, 108 vibration plate lead square hole, 109 circuit board mounting platform, 110 upper row of fastening threaded through holes, 111 lower row of fastening threaded blind holes, 112 uniaxial temperature compensation strain gauge, 113 uniaxial working strain gauge, 114 torque strain gauge, 2 collet, 3 nut, 4 milling cutter, 5 magnet bracket, 501 bracket fastening screw, 6 magnet, 7 copper coil, 11 bridge signal processing board, 12 power management board, 13 main control board, 14 WiFi board, 15 spindle. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Establish the intelligent tool handle device that characterizes the present invention:

[0042] like Figure 1-4 As shown, the intelligent tool handle device is composed of a tool handle body 1, an upper row of fastening screws 101, a lower row of fastening screws 102, a uniaxial temperature compensation strain gauge 112, a uniaxial working strain gauge 113, a torque strain gauge 114, a collet 2, a nut 3, a milling cutter 4, a magnet bracket 5, a bracket fastening screw 501, a magnet 6, a copper coil 7, a bridge signal processing board 11, a power management board 12, a main control board 13, and a WiFi board 14. The prototype structure model of the tool handle body 1 is HSK63A-ER40-160L.

[0043] The handle body 1 has undergone a lot of structural changes on the basis of the prototype handle. The conical handle circular ring hole 103 is provided for embedding the copper coil 7; the coil lead hole in the conical handle circular ring hole 103 is provided for the copper coil 7 to be led to the center of the handle for collection; the circuit board lead groove 105 is provided for the transmission of energy and signals between the bridge signal processing board 11, the power management board 12, the main control board 13 and the WiFi board 14; the circuit board lead hole 106 is provided for connecting the collected copper coil 7 leads to the power management board 12 for rectification and voltage stabilization; The uniaxial temperature compensation strain gauge 112, the uniaxial working strain gauge 113 and the torque strain gauge 114 are attached by setting the strain gauge attachment surface 107; the installation of the bridge signal processing board 11, the power management board 12, the main control board 13 and the WiFi board 14 with the tool handle body 1 is realized by setting the circuit board mounting platform 109, the upper row of fastening threaded through holes 110 and the lower row of fastening threaded blind holes 111 in combination with the upper row of fastening screws 101 and the lower row of fastening screws 102; the milling cutter 4 is installed with the tool handle body 1 through the collet 2 and the nut 3.

[0044] Implementation method of the electromagnetic induction self-powered device of the present invention:

[0045] The intelligent tool handle self-powering device of the present invention is as follows Figure 3-4 As shown. The method is based on Faraday's law of electromagnetic induction. The specific implementation method is to use a magnet bracket 5 to carry a magnet 6 to generate a constant magnetic field near the lower end of the spindle 15. The magnet bracket 5 is connected to the spindle 15 through the screw hole on the spindle cover by screws 501. The magnet bracket 5 is manufactured by 3D printing of white resin material, and the magnet 6 is a customized NdFeB strong magnet with a circular arc shape in the longitudinal section. At the same time, a tapered handle annular hole 103 distributed at 120° is set on the handle body 1 for embedding three copper coils 7 placed at 120°. When the machine tool is cutting, the copper coil 7 rotates with the handle body 1. At this time, the magnetic flux in the copper coil 7 changes with the rotation, and the changing magnetic flux will generate an induced potential. The copper coil 7 passes through the coil lead hole 104 and then through the circuit board lead hole 106 to the power management board 12 for rectification and voltage stabilization to supply power to various circuits and components; the cone handle annular hole 103 is set on the cone handle of the handle body 1, the number of the cone handle annular holes 103 is 3 or more, and they are evenly arranged along the circumference of the cone handle; the longitudinal section of the magnet 6 is arc-shaped; the circuit schematic diagram of the power management board 12 is as shown in the attached figure Figure 6As shown, the rectifier and voltage stabilizing circuit includes 6 circuit board lead interfaces P15, capacitors C94-C97, C99-C100, C103-C105, resistors R116-R123, temperature measuring resistor RT1, LED lamp D6 and wireless power receiver U13; the circuit board lead interface P15 includes 6 interfaces; the wireless power receiver U13 includes interfaces CLAMP1, COMM1, AC1, AC2, BOOT1, BOOT2, CLAMP2, COMM2, OUT, CHG, ILIM, FOD, REC T, TS, EN1, EN2; one end of the capacitor C96 is connected in parallel with the capacitors C99 and C103 and connected to the AC1 interface of U13, and the other end of C96 is connected to the BOOT1 of U13; the other end of the capacitor C99 is connected to the interface CLAMP1 of U13; the other end of the capacitor C103 is connected to the interface COMM1 of U13; one end of the capacitor C97 is connected in parallel with the capacitors C100 and C104 and connected to the AC2 interface of U13, and the other end of C97 is connected to the BOOT2 of U13; the other end of the capacitor C100 is connected to the interface CLAMP2 of U13; The other end of the capacitor C104 is connected to the interface COMM2 of U13; the positive pole of the LED lamp D6 is connected to the interface OUT of U13, and the negative pole is connected to the interface CHG of U13; one end of the resistor R116 is connected to the interface ILIM of U13, and the other end is connected to the resistors R117 and R121, and the interface FOD of U13; one end of the resistor R117 is connected to the interface FOD of U13, and the other end is connected to the interface RECT of U13 and the filter capacitor C105; one end of the resistor R121 is connected to the interface FOD of U13, and the other end is connected to GND; one end of the capacitor C105 is connected to the interface FOD of U13, and the other end is connected to GND; RECT of U13, and the other end is connected to GND; one end of the resistor R119 is connected to VOUT, and the other end is connected to resistor R122 and interface 5 of P15, and the other end of resistor R122 is connected to GND; one end of the resistor R120 is connected to VOUT, and the other end is connected to resistor R123 and interface 6 of P15, and the other end of resistor R123 is connected to GND; the temperature measuring resistor RT1 is connected to interface TS of U13; interfaces 1 and 2 of P15 are connected to GND, interfaces 3 and 4 are connected to voltage source VOUT, interface 5 is connected to interface EN1 of U13, and interface 6 is connected to interface EN2 of U13.

[0046] When the generated induced voltage is delivered to the circuit through the copper coil 7, the internal synchronous rectifier feeds this voltage to the RECT pin with filter capacitor C105; the BQ51013 identifies and authenticates itself by switching the COM FET on and off, and by switching CCOMM on and off. If the authentication is successful, the transmitter will remain powered on;

[0047] The EN1 and EN2 pins include internal 200kΩ pull-down resistors, so if these pins are not connected, the wireless power receiver BQ51013 will default to AD-EN control mode;

[0048] However, these pins can be pulled high, as shown by resistors R119 and R120;

[0049] The BQ51013 provides two identical integrated communication FETs connected to pins COMM1 and COMM2. These FETs are used to modulate the secondary load current, enabling the BQ51013 to communicate error control and configuration information to the transmitter.

[0050] In addition to resistive load modulation, the BQ51013 is also capable of capacitive load modulation, as shown in the circuit on the left;

[0051] In this case, the capacitor is connected from COMM1 to AC1 and from COMM2 to AC2;

[0052] When the COMM switch is closed, a 22nF capacitor is actually connected between AC1 and AC2;

[0053] Connecting a capacitor between AC1 and AC2 modulates the impedance seen by the coil, which will be reflected in the primary resistance as a change in current.

[0054] Implementation method of the tool tip four-dimensional force measurement of the present invention:

[0055] The Wheatstone bridge is used to measure the four-dimensional force at the tool tip, and the steps are as follows:

[0056] ① Determine the structure of the elastic element of the handle;

[0057] 101. Four or more evenly distributed planes are arranged in the circumferential direction of the middle part of the shank, with the axial direction being the length direction of the plane and the other vertical direction being the width direction of the plane;

[0058] 102. With the bottom end of the cone handle as a reference, the distances between the first and last ends of the plane in the length direction and the plane of the bottom end of the cone handle are taken as two parameters; the width of the plane is taken as the third parameter;

[0059] ② Carry out multi-parameter and multi-objective optimization;

[0060] 201. Taking the three parameters as optimization parameters and the axial and radial stiffness of the tool holder as optimization targets, UG&ANSYS joint simulation optimization is performed;

[0061] ③ Create a four-dimensional force measurement decoupling model based on resistance strain gauges and fixed resistors;

[0062] 301. Establish a Wheatstone bridge sensing circuit, including a resistance strain gauge (uniaxial strain gauge, torque strain gauge) and a fixed value resistor, denoted by R a , R b , R c , R d Where R a , R b and R c , R d Two bridge circuits are formed respectively, and the resistance change of each strain gauge is recorded as ΔR a , ΔR b , ΔR c , ΔR d , bridge output voltage V O With the bridge input voltage V S The relationship between them is:

[0063]

[0064] 302. Strain ε, resistance change rate Strain gauge sensitivity K S The relationship is:

[0065]

[0066] 303. Replace the resistance change rate in (a) with strain and sensitivity:

[0067]

[0068] where ε a , ε b , ε c , ε d Represent the strain of each strain gauge respectively;

[0069] 304. Two uniaxial strain gauges are respectively arranged on each cutting surface, wherein the first strain gauge is used as a uniaxial working strain gauge 113, the sensitive grid direction of the working strain gauge is parallel to the axis direction of the tool handle, and is arranged above the center of the plane; the second strain gauge is used as a uniaxial temperature compensation strain gauge 112, the sensitive grid direction is perpendicular to the axis direction, and is arranged above the working strain gauge, and the strain gauge of each cutting surface and two fixed resistors form a Wheatstone bridge; 305. The sum of the bridge output values ​​between the two cutting surfaces of the tool handle elastic element relative to each other is the change value caused by the single load of the axial force, and the subtraction of the bridge values ​​is the change value caused by the single load of the radial force along the direction of the line connecting the two surfaces; 306. Two torque strain gauges 114 are arranged on two opposite cutting surfaces to form a Wheatstone bridge circuit, and the torque strain gauge 114 is arranged below the center of the plane;

[0070] 307. The uniaxial working strain gauge 113 is arranged 5 mm above the center of the plane and away from the bisector of the length direction; the uniaxial temperature compensation strain gauge 112 is arranged 5 mm above the working strain gauge; the torque strain gauge 114 is arranged 5 mm below the center of the plane and away from the bisector of the length direction.

[0071] ④Determine the bridge signal processing circuit;

[0072] 401. Setting amplification gain for half bridge and full bridge based on bridge output voltage;

[0073] 402. The half-bridge and full-bridge amplification gains are 10,000 times and 1,000 times respectively; a differential amplifier is used to achieve signal gain, and the differential amplifier circuit is composed of TLV9004 or TLV9002;

[0074] 403. The cutting force signal frequency is obtained according to the cutting frequency of the cutter teeth, and the sampling frequency is designed according to the sampling theorem; the signal frequency is 1.2kHz (four-tooth milling cutter, HSK tool holder maximum operating speed is 18000rpm), and the sampling frequency is set to 6kHz according to the sampling theorem, and the analog conversion circuit is composed of ADS1235.

[0075] The method for measuring the four-dimensional force of the tip of the intelligent tool handle of the present invention is as follows: Figure 5 This method uses a Wheatstone bridge circuit based on a resistance strain gauge to measure force. The specific implementation method is: four half-bridge circuits are used to measure axial force and radial force. Each half-bridge consists of a uniaxial temperature compensation sheet 112, a uniaxial working strain gauge 113 and two fixed value resistors arranged in the bridge signal processing board 11. The uniaxial temperature compensation sheet 112 is used to offset the influence of temperature on the strain of the uniaxial working strain gauge 113, as shown in the attached figure. Figure 5 The wire grid of the uniaxial temperature compensation sheet 112 is perpendicular to the axis of the tool handle, and the uniaxial working strain gauge 113 is placed parallel to the axis. A full bridge circuit is used to measure the torque, and each full bridge is composed of two torque strain gauges 114, as shown in the attached figure. Figure 5 Each torque strain gauge 114 shown contains two groups of wire grids, which are arranged at 45° or 135° to the axis. The half-bridge circuit signals with a difference of 180° are added to obtain the signal change caused by the single load of axial force, and the signal change caused by the single load of radial force is subtracted. The full-bridge signal is caused by the single load of torque. The static calibration of the four-dimensional force is carried out through a calibration device with a higher level of accuracy (torsion testing machine, universal testing machine) to realize the corresponding relationship between the load and the signal voltage value, thereby realizing the measurement of the four-dimensional force of the tip of the intelligent tool handle;

[0076] The bridge circuit consists of a bridge arm balance resistor, a front differential amplifier circuit, an input filter circuit, and an analog conversion circuit. The signal input part differentially amplifies the strain gauge input signal and the balance resistor input signal, and sends them to the analog conversion circuit after filtering. The schematic diagram of this circuit is shown in the attached figure. Figure 7 shown.

[0077] The bridge signal processing circuit includes strain gauge interfaces P10, P11 and P13, a lead interface P12 between the bridge board and the main control board, resistors R45-R99, R102, R105-R115, capacitors C42-C43, C46-C56, C61-C66, C69-C80, C83-C91, three-stage tubes TVS5-TVS10, amplifiers U8, U10 and U12, analog-to-digital conversion chip U9, and reference voltage chip U11; the strain gauge interfaces P10, P11 and P13 each include 6 interfaces; the lead interface P12 between the bridge board and the main control board includes 10 interfaces; the amplifiers U8, U10 and U12 each include 16 interfaces; the analog-to-digital conversion chip U9 includes 33 interfaces;

[0078] P10, P11 and P13 on the left side of the figure are the strain gauge interface and bridge arm resistance circuit part, which are responsible for converting the resistance change caused by the strain gauge into a voltage signal;

[0079] For P10, one end of the strain gauge resistor R61 is connected to the resistors R60 and R60, and the other end is connected to the resistor R58. The two ends of the resistor R58 are connected to the capacitors C52 and C53 and then to the ground AGND. The other end of the resistor R58 is connected to the resistor R59, and the output signal is connected to the interface 1IN1+ of U8. Similarly, one end of the strain gauge resistor R71 is connected to the resistors R66 and R74, and the other end is connected to the resistor R72. The two ends of the resistor R72 are connected to the capacitors C65 and C66 and then to the ground AGND. The other end of the resistor R72 is connected to the resistor R73, and the output signal is connected to the interface 10IN3+ of U8.

[0080] Interface 1 of P10 is input by voltage Vs+, interface 2 is connected to TVS5 tube, connected in series with resistors R51 and R52, and the other end of R52 is connected to interface 3IN2+ of U10. Similarly, interface 4 of P10 is input by voltage Vs+, interface 5 is connected to TVS6 tube, connected in series with resistors R67 and R68, and the other end of R68 is connected to interface 12IN4+ of U10. Interfaces 3 and 6 of P10 are connected to Vs-. The other ends of TVS5 tube and TVS6 tube are connected to AGND.

[0081] For P11, one end of the strain gauge resistor R85 is connected to resistors R84 and R86, and the other end is connected to resistor R82;

[0082] Both ends of the resistor R82 are connected to the capacitors C73 and C74 and then to the ground AGND. The other end of the resistor R82 is connected to the resistor R83, and the output signal is connected to the interface 1IN1+ of U10.

[0083] One end of the strain gauge resistor R97 is connected to the resistors R92 and R102, and the other end is connected to the resistor R98. Both ends of the resistor R98 are connected to the capacitors C79 and C80 respectively and then to the ground AGND. The other end of the resistor R98 is connected to the resistor R99, and the output signal is connected to the interface 10IN3+ of U10;

[0084] Interface 1 of P11 is input by voltage Vs+, interface 2 is connected to TVS7 tube, and is connected in series with resistors R78 and R79, and the other end of R79 is connected to interface 3IN2+ of U10.

[0085] Interface 4 of P11 is input by voltage Vs+, interface 5 is connected to TVS8 tube, connected in series with resistors R93 and R94, and the other end of R94 is connected to interface 12IN4+ of U10;

[0086] Interfaces 3 and 6 of P11 are connected to Vs-;

[0087] The other ends of TVS7 and TVS8 tubes are connected to AGND;

[0088] For P13, the interface 1 of P13 is input by the voltage Vs+, the interface 2 is connected to the TVS9 tube, and is connected in series with the resistors R108 and R109, the capacitors C83 and C84 are connected in parallel at both ends of R108, and the other end of R109 is connected to the interface 5IN2+ of U12. Similarly, the interface 4 of P13 is input by the voltage Vs-, the interface 3 is connected to the TVS10 tube, and is connected in series with the resistors R123 and R113, the capacitors C88 and C89 are connected in parallel at both ends of R112, and the other end of R113 is connected to the interface 3IN1+ of U12. The other ends of the TVS9 tube and TVS10 tube are connected to AGND.

[0089] To the right of the bridge arm resistance circuit is the bridge signal amplifier circuit and its schematic diagram. U8 and U10 are TLV9004 multi-stage amplifiers, and U12 is a TLV9002 multi-stage amplifier. To their left is the schematic diagram of the internal multi-stage amplifier circuit, which uses a two-stage operational amplifier instrument circuit to amplify the differential signal generated by the resistance change of the strain gauge.

[0090] For amplifier U8, the left end of resistor R53 is connected to Vref, and the other end is connected to interface 16IN1- of U8. One end of resistor R46 is connected to interface 16IN1- of U8, and the other end is connected to interface 15OUT1 of U8. One end of resistor R45 is connected to interface 16IN1- of U8, and the other end is connected to interface 4IN2- of U8. One end of resistor R47 is connected to interface 4IN2- of U8, and the other end is connected to interface 5OUT2 of U8. One end of resistor R55 is connected to interface 15OUT1 of U8, and the other end is connected to interface 4IN2- of U8. Similarly, the left end of resistor R69 is connected to Vref, and the other end is connected to interface 9IN3- of U8. One end of resistor R64 is connected to interface 9IN3- of U8, and the other end is connected to interface 8OUT3 of U8. One end of resistor R63 is connected to interface 9IN3- of U8, and the other end is connected to interface 13IN4- of U8. One end of the resistor R65 is connected to the interface 13IN4- of U8, and the other end is connected to the interface 14OUT4 of U8. One end of the resistor R70 is connected to the interface 8OUT3 of U8, and the other end is connected to the interface 13IN4- of U8.

[0091] For amplifier U10, the left end of resistor R80 is connected to Vref, and the other end is connected to interface 16IN1- of U10;

[0092] One end of the resistor R76 is connected to the interface 16IN1- of U10, and the other end is connected to the interface 15OUT1 of U10;

[0093] One end of the resistor R75 is connected to the interface 16IN1- of U10, and the other end is connected to the interface 4IN2- of U10;

[0094] One end of resistor R77 is connected to interface 4IN2- of U10, and the other end is connected to interface 5OUT2 of U10;

[0095] One end of the resistor R81 is connected to the interface 15OUT1 of U10, and the other end is connected to the interface 4IN2- of U10;

[0096] After the signal is amplified by amplifiers U8, U10 and U12, the output is OUT2, OUT4, OUT6, OUT8, OUT10, which are connected to 29, 28, 26, 25, 27 of U9 respectively;

[0097] Interfaces 3 to 10 of P12 are connected to interfaces 7 to 14 of U9.

[0098] For amplifier U12, the left end of resistor R110 is connected to Vref, and the other end is connected to interface 2IN1- of U12. One end of resistor R106 is connected to interface 2IN1- of U12, and the other end is connected to interface 1OUT1 of U12. One end of resistor R105 is connected to interface 2IN1- of U12, and the other end is connected to interface 6IN2- of U12. One end of resistor R107 is connected to interface 6IN2- of U12, and the other end is connected to interface 7OUT2 of U12. One end of resistor R111 is connected to interface 1OUT1 of U12, and the other end is connected to interface 6IN2- of U12.

[0099] After the signal is amplified by amplifiers U8, U10 and U12, the output is OUT2, OUT4, OUT6, OUT8, OUT10, which are respectively connected to 29, 28, 26, 25, 27 of the ADS chip U9.

[0100] At the same time, P12 is used to meet the signal transmission between the bridge board and the main control board. Interfaces 3 to 10 of P12 are connected to interfaces 7 to 14 of U9.

[0101] The first circuit on the upper right is the excitation output and feedback circuit, which provides a stable voltage for the amplifier and chip to work, and does not affect the normal use of the circuit function under unexpected circumstances;

[0102] Below the excitation output and feedback circuit is the signal filtering and protection circuit, which is responsible for removing noise signals and keeping the voltage range normal so as not to damage U9, i.e. the ADS1235 chip;

[0103] U9 on the right is a 24-bit programmable gain analog-to-digital converter ADS1235 with a gain of 128 times. It is responsible for the analog-to-digital conversion of the bridge signal and is connected to the main control board through P12 below.

[0104] Vref outputs a stable reference voltage of 2.495V through the REF chip represented by U11.

[0105] The above-described embodiments are only preferred embodiments of the present invention, and are not exhaustive of the feasible implementations of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A self-powered force measuring intelligent tool handle based on electromagnetic induction, characterized in that: The invention comprises a tool handle body (1) arranged on a main shaft (15), a magnet support (5), a magnet (6), a copper coil (7), a cone handle annular hole (103), a rectifier voltage stabilizing circuit, a tool handle strain gauge pasting surface (107), a uniaxial temperature compensation strain gauge (112), a uniaxial working strain gauge (113), a torque strain gauge (114), and a bridge signal processing circuit; the magnet support (5) is provided with a wedge-shaped groove, and the magnet (6) is connected to the magnet support (5) through the wedge-shaped groove; the magnet support (5) is arranged between the main shaft and the tool handle body (1) On the side of the interface, the magnet bracket (5) is arranged on the end surface mounting cover of the spindle (15) through the bracket fastening screw (501); the copper coil (7) is arranged in the circular ring hole (103) of the cone handle; the rectifying and voltage stabilizing circuit is arranged on the tool handle body (1); the uniaxial temperature compensation strain gauge (112), the uniaxial working strain gauge (113), and the torque strain gauge (114) are arranged on the tool handle strain gauge pasting surface (107) for building a Wheatstone bridge sensing circuit; the bridge signal processing circuit is arranged on the tool handle body (1); The invention also comprises a bridge signal processing board (11), a power management board (12), a main control board (13), a WiFi board (14), a collet (2), a nut (3) and a milling cutter (4); four circuit board mounting platforms (109) are arranged in the middle of the tool handle body (1), and the circuit board mounting platforms (109) are provided with an upper row of fastening threaded through holes (110) and a lower row of fastening threaded blind holes (111); the signal processing board (11), the power management board (12), the main control board (13) and the WiFi board (14) are arranged on the four circuit board mounting platforms (109) by means of an upper row of fastening screws (101) and a lower row of fastening screws (102), and the upper row of fastening screws (101) and the lower row of fastening screws (102) are matched with the upper row of fastening threaded through holes (110) and the lower row of fastening threaded blind holes (111) respectively. The invention relates to a method for manufacturing a rotatable electric tool for a rotatable electric tool for a rotatable electric tool. The method comprises the following steps: the cone handle circular ring hole (103) is provided with a coil lead hole (104), a circuit board lead groove (105) is provided between adjacent circuit board mounting platforms (109), and a circuit board lead hole (106) is provided on the circuit board mounting platform (109) matched with the power management board (12); the induced current in the copper coil (7) is transmitted to the power management board (12), the bridge signal processing board (11), the main control board (13), and the WiFi board (14) through the coil lead hole (104), the circuit board lead hole (106), and the circuit board lead groove (105); the collet (2), the nut (3), and the milling cutter (4) are sequentially arranged at the lower end of the handle body (1), the rectifying and voltage stabilizing circuit is arranged on the power management board (12), and the bridge signal processing circuit is arranged on the bridge signal processing board (11).

2. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 1, characterized in that: The rectifier and voltage stabilizing circuit includes 6 circuit board lead interfaces P15, capacitors C94-C97, C99-C100, C103-C105, resistors R116-R123, temperature measuring resistor RT1, LED lamp D6 and wireless power receiver U13; the circuit board lead interface P15 includes 6 interfaces; the wireless power receiver U13 includes interfaces CLAMP1, COMM1, AC1, AC2, BOOT1, BOOT2, CLAMP2, COMM2, OUT, CHG, ILIM, FOD, RECT, TS, EN1, EN2; one end of the capacitor C96 is connected in parallel with the capacitors C99 and C103 and connected to the AC1 interface of U13, and the other end of C96 is connected to the BOOT1 of U13; the other end of the capacitor C99 is connected to the interface CLAMP1 of U13; the other end of the capacitor C103 is connected to the interface COMM1 of U13; one end of the capacitor C97 is connected in parallel with the capacitors C100 and C104 and connected to the AC2 interface of U13, and the other end of C97 is connected to the BOOT2 of U13; the other end of the capacitor C100 is connected to the interface CLAMP2 of U13; The other end of capacitor C104 is connected to the interface COMM2 of U13; the positive pole of the LED lamp D6 is connected to the interface OUT of U13, and the negative pole is connected to the interface CHG of U13; one end of the resistor R116 is connected to the interface ILIM of U13, and the other end is connected to the resistors R117 and R121, and the interface FOD of U13; one end of the resistor R117 is connected to the interface FOD of U13, and the other end is connected to the interface RECT of U13 and the filter capacitor C105; one end of the resistor R121 is connected to the interface FOD of U13, and the other end is connected to GND; one end of the capacitor C105 is connected to RECT of U13, and the other end is connected to GND; one end of the resistor R119 is connected to VOUT, and the other end is connected to resistor R122 and interface 5 of P15, and the other end of resistor R122 is connected to GND; one end of the resistor R120 is connected to VOUT, and the other end is connected to resistor R123 and interface 6 of P15, and the other end of resistor R123 is connected to GND; the temperature measuring resistor RT1 is connected to interface TS of U13; interfaces 1 and 2 of P15 are connected to GND, interfaces 3 and 4 are connected to voltage source VOUT, interface 5 is connected to interface EN1 of U13, and interface 6 is connected to interface EN2 of U13.

3. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 1, characterized in that: The four-dimensional force measurement of the tool tip is realized by using the Wheatstone bridge, and the steps are as follows: ① Determine the structure of the elastic element of the handle; 101. Four or more evenly distributed planes are arranged in the circumferential direction of the middle part of the shank, with the axial direction being the length direction of the plane and the other vertical direction being the width direction of the plane; 102. With the bottom end of the cone handle as a reference, the distances between the first and last ends of the plane in the length direction and the plane of the bottom end of the cone handle are taken as two parameters; the width of the plane is taken as the third parameter; ② Carry out multi-parameter and multi-objective optimization; 201. Taking the three parameters as optimization parameters and the axial and radial stiffness of the tool holder as optimization targets, UG&ANSYS joint simulation optimization is performed; ③ Create a four-dimensional force measurement decoupling model based on resistance strain gauges and fixed resistors; 301. Establish a Wheatstone bridge sensing circuit, including a resistance strain gauge (uniaxial strain gauge, torque strain gauge) and a fixed value resistor, denoted by R a , R b , R c , R d Where R a , R b and R c , R d Two bridge circuits are formed respectively, and the resistance change of each strain gauge is recorded as ΔR a , ΔR b , ΔR c , ΔR d , bridge output voltage V O With the bridge input voltage V S The relationship between them is:

302. Strain ε, resistance change rate Strain gauge sensitivity K S The relationship is:

303. Replace the resistance change rate in (a) with strain and sensitivity: where ε a , ε b , ε c , ε d Represent the strain of each strain gauge respectively; 304. Two uniaxial strain gauges are respectively arranged on each cutting surface, wherein the first strain gauge is used as a uniaxial working strain gauge (113), the sensitive grid direction of the working strain gauge is parallel to the axis direction of the tool handle, and is arranged above the center of the plane; the second strain gauge is used as a uniaxial temperature compensation strain gauge (112), the sensitive grid direction is perpendicular to the axis direction, and is arranged above the working strain gauge, and the strain gauge on each cutting surface and two fixed value resistors form a Wheatstone bridge; 305. The sum of the bridge output values ​​between the two cutting surfaces of the tool handle elastic element is the change value caused by the single load of the axial force, and the subtraction of the bridge values ​​is the change value caused by the single load of the radial force along the direction of the line connecting the two surfaces; 306. Arrange two torque strain gauges (114) on two opposite cutting surfaces to form a Wheatstone bridge circuit, wherein the torque strain gauges (114) are arranged below the center of the plane; ④Determine the bridge signal processing circuit; 401. Set the amplification gain of the half bridge and the full bridge based on the bridge output voltage.

4. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 1, characterized in that: The bridge signal processing circuit includes strain gauge interfaces P10, P11 and P13, lead interface P12 between the bridge board and the main control board, resistors R45-R99, R102, R105-R115, capacitors C42-C43, C46-C56, C61-C66, C69-C80, C83-C91, triodes TVS5-TVS10, amplifiers U8, U10 and U12, analog-to-digital conversion chip U9, and reference voltage chip U11; the strain gauge interfaces P10, P11 and P13 each include 6 interfaces; the lead interface P12 between the bridge board and the main control board includes 10 interfaces; the amplifiers U8, U10 and U12 each include 16 interfaces; the analog The digital conversion chip U9 includes 33 interfaces; the strain gauge interface P11 is connected, and one end of the strain gauge resistor R85 is connected to resistors R84 and R86, and the other end is connected to resistor R82; both ends of resistor R82 are respectively connected to capacitors C73 and C74 and then grounded AGND, the other end of resistor R82 is connected to resistor R83, and the output signal is connected to interface 1IN1+ of U10; one end of strain gauge resistor R97 is connected to resistors R92 and R102 and the other end is connected to resistor R98, both ends of resistor R98 are respectively connected to capacitors C79 and C80 and then grounded AGND, the other end of resistor R98 is connected to resistor R99, and the output signal is connected to interface 10IN3+ of U10; interface 1 of P11 is input by voltage Vs+, and interface 2 is connected Connect TVS7 tube, and connect it in series with resistors R78 and R79, the other end of R79 is connected to interface 3IN2+ of U10; interface 4 of P11 is input by voltage Vs+, interface 5 is connected to TVS8 tube, and connects it in series with resistors R93 and R94, the other end of R94 is connected to interface 12IN4+ of U10; interfaces 3 and 6 of P11 are connected to Vs-; the other ends of TVS7 tube and TVS8 tube are connected to AGND; the connection method of P10 and P13 is the same as that of P11; the amplifier U10 is connected, and the left end of resistor R80 is connected to Vref, and the other end is connected to interface 16IN1- of U10; one end of resistor R76 is connected to interface 16IN1- of U10, and the other end is connected to interface 15OUT1 of U10; resistor One end of R75 is connected to interface 16IN1- of U10, and the other end is connected to interface 4IN2- of U10; one end of resistor R77 is connected to interface 4IN2- of U10, and the other end is connected to interface 5OUT2 of U10; one end of resistor R81 is connected to interface 15OUT1 of U10, and the other end is connected to interface 4IN2- of U10; after the signal is amplified by amplifiers U8, U10 and U12, the output is OUT2, OUT4, OUT6, OUT8, OUT10, which are respectively connected to interfaces 29, 28, 26, 25, 27 of U9; interfaces 3 to 10 of P12 are connected corresponding to interfaces 7 to 14 of U9; the connection method of amplifiers U8 and U12 is the same as that of U10.

5. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 1, characterized in that: The tapered shank annular holes (103) are arranged on the tapered shank of the tool handle body (1); the number of the tapered shank annular holes (103) is 3 or more and they are evenly arranged along the circumference of the tapered shank.

6. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 1, characterized in that: The magnet (6) has a longitudinal section in the shape of an arc.

7. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 3, characterized in that: The three optimized parameters result in a cutting plane size of 50 mm×30 mm, and a distance of 20 mm between the plane near the cone handle and the plane at the lower end of the cone handle.

8. The electromagnetic induction-based self-powered force measurement intelligent tool handle according to claim 3, characterized in that: The uniaxial working strain gauge (113) is arranged 5 mm above the center of the plane and away from the bisector in the length direction; the uniaxial temperature compensation strain gauge (112) is arranged 5 mm above the working strain gauge; and the torque strain gauge (114) is arranged 5 mm below the center of the plane and away from the bisector in the length direction.

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