Interactive precise force control electric tightening tool

Abstract

The invention relates to the technical field of electric torque wrenches, in particular to an interactive precise force control electric tightening tool which comprises a preload indication gasket and an interactive electric torque wrench. The preload indication gasket detects the deformation quantity of the belleville spring gasket through the micro-displacement sensor and converts the deformation quantity into a pressure value, and the interactive electric torque wrench adjusts the output rotating speed by receiving the pressure value so as to accurately control the pretightening force of the bolt. According to the tool, efficient communication between the preload indication gasket and the torque wrench is achieved through roll-call communication logic and a Modbus protocol, the problem that pretightening force is too large or too small can be effectively solved, and the safety and reliability of bolt connection are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial production, and specifically relates to an interactive precision force-controlled electric tightening tool Background Art

[0002] In industrial production, with the continuous improvement of the requirements for precision manufacturing, bolt pre-tightening technology has become one of the key links. Currently, the electric torque wrenches on the market mainly achieve bolt pre-tightening work by a fixed torque method. However, the relationship between torque and bolt pre-tightening force is complex and requires detailed calculations to determine. In addition, the relationship between the tightening torque of the bolt and the pre-tightening force is affected by various factors, such as the surface machining accuracy of the connecting parts, the tightening speed, the lubrication conditions, and the ambient temperature. Changes in these factors will cause changes in the relationship between torque and pre-tightening force, thus affecting the pre-tightening effect

[0003] In order to ensure sufficient pre-tightening force between the connecting parts while avoiding the situation that the bolt cracks or even breaks due to excessive pre-tightening force, the prior art usually leaves a margin in the design stage and selects bolts with a larger diameter for connection. This method not only increases the assembly difficulty but also increases the structural weight. In addition, due to the inability to precisely control the bolt pre-tightening force, "over-tightening" phenomena caused by excessive pre-tightening force and "under-tightening" phenomena caused by insufficient pre-tightening force may occur during the assembly process. Over-tightening will cause the pre-tightening force to exceed the tolerable range of the bolt, leading to accidents; under-tightening will cause the bolt connection to become loose and lose its fastening function

[0004] To solve the above problems, the present invention provides an interactive precision force-controlled electric tightening tool, which includes a preload indicating washer and an interactive electric torque wrench. By introducing the preload indicating washer and the interactive electric torque wrench into the bolt pre-tightening system, relevant software and hardware and an interactive thread connection pre-tightening force control method are designed. The preload indicating washer can detect the pressure change during the bolt pre-tightening process in real time through the internal micro-displacement sensor and transmit this data to the interactive electric torque wrench. The interactive electric torque wrench then makes dynamic adjustments based on this data to achieve precise control of the bolt pre-tightening force. This method can be applied to high-strength bolt pre-tightening occasions with high control requirements for bolt pre-tightening force, effectively solving the deficiencies in the prior art and improving the accuracy and reliability of bolt pre-tightening Summary of the Invention

[0005] Aiming at the problems existing in the prior electric torque wrench during the bolt pre-tightening process, such as complex pre-tightening force calculation, unstable pre-tightening force, and insufficient safety and reliability, the present invention adopts the following technical solutions

[0006] The present invention provides an interactive precision force-controlled electric tightening tool, which includes a preload indicating washer and an interactive electric torque wrench, wherein

[0007] The preload indicating washer is used to detect the deformation amount in the bolt pre-tightening process in real time and convert it into a pressure value. The interactive electric torque wrench adjusts the output speed by receiving the pressure value to achieve precise control of the bolt pre-tightening force.

[0008] Further, the preload indicating washer includes a disc spring washer, a bottom gasket, a retaining ring and a micro-displacement sensor. The disc spring washer deforms during the bolt pre-tightening process. The bottom gasket supports the disc spring washer. The retaining ring fixes the micro-displacement sensor. The micro-displacement sensor is used to detect the deformation amount of the disc spring washer and convert the deformation amount into an electrical signal.

[0009] Particularly, the preload indicating washer further includes a main control chip, an ADC sampling chip and a data level conversion module. The main control chip uses an STM32F030 processing chip, and the internal 8MHz high-speed RC oscillation clock source is used as the system clock. The ADC sampling chip uses an ADS1115 high-precision analog-to-digital converter, which has a 16-bit resolution, supports 4 IIC slave addresses, the single power supply operating range is 2.0V to 5.5V, and the maximum sampling rate is 860 samples / second. The data level conversion module uses an SP3485EEN chip and its external circuit to convert the TTL signal output by the main control chip into an RS485 signal for long-distance transmission.

[0010] Further, the preload indicating washer establishes a displacement-pressure correspondence relationship through a calibration method. The calibration method detects the correspondence relationship between the washer displacement and the pressure through an MTS machine and stores the measured data in the main control chip. When calculating the bolt pre-tightening force, the main control chip converts the electrical signal read by the washer into a pressure value through the Lagrange interpolation method, where:

[0011] The Lagrange interpolation method performs interpolation calculation based on four parameters read by the main control chip from the ADC sampling chip and their corresponding pressure values. The pressure value calculation formula is:

[0012]

[0013] where x represents the axial deformation amount of the disc spring, y n is the corresponding pressure value in the calibration data, and Ln(x) is the interpolation basis function.

[0014] Particularly, the preload indicating washer adopts an average value filtering technique during the AD sampling process. After 16 voltage samplings of the sensor, the sampling values are converted into binary form and added together, and then window-shifted by 4 bits. The processed result is used for subsequent pressure calculation to suppress the voltage fluctuation phenomenon and ensure the response speed.

[0015] Furthermore, a roll-call communication logic is adopted between the preload indicating washer and the interactive electric torque wrench. When pre-tightening a bolt, the interactive electric torque wrench first matches the washer used for the bolt and obtains the virtual address of the washer, and then sends a pre-tightening force query request signal with address information. After receiving the signal, the pre-load indicating washer performs AD sampling and pre-tightening force calculation and outputs the calculation result to the interactive electric torque wrench.

[0016] In particular, the communication protocol adopts the Modbus communication protocol, which is configured with a baud rate of 9600, 8 data bits, 1 stop bit, and no check bit. The communication level standard adopts the RS485 standard, and transmits differential signals to improve anti-interference ability and achieve long-distance transmission.

[0017] Furthermore, the interactive electric torque wrench includes a control circuit module and a motor drive circuit module. The control circuit module collects real-time speed information of the motor through a Hall sensor, and outputs a PWM wave to the drive circuit module after calculation by a controller. The drive circuit module controls the three-phase bridge arm voltage through MOSFET to achieve control of the motor.

[0018] In particular, the main control unit of the control circuit module adopts the STM32G431 chip and its peripheral circuits, the DC voltage regulator module adopts LMR14052SDDA and BL855CC3BTR33 to provide 5V and 3.3V regulated power supplies for the circuit, and the MOSFET adopts Infineon BSC0702LS.

[0019] Furthermore, the motor of the interactive electric torque wrench adopts a synchronous motor with an operating voltage of 48V and a torque of 1.6Nm. The output shaft of the synchronous motor is connected to an 8-tooth helical gear, and the output is from a 35-tooth helical gear shaft, and is connected to a planetary reducer through a reversing mechanism. The reduction ratio of the planetary reducer is 840. After the torque is amplified by the reducer, the maximum output torque is not less than 3000Nm, and high-strength bolts of size M36 and below can be pre-tightened.

[0020] In particular, the controller of the interactive electric torque wrench adopts an upper and lower layer design. The upper layer controller designs a model predictive control method based on the mechanical model of the bolt pretightening process, characterizes the dynamic characteristics of the system and performs online optimization of the target performance indicators during the working process to determine the control effect at future moments. The lower layer controller designs a dual closed-loop motor vector control to achieve rapid tracking of the motor speed.

[0021] Furthermore, the model predictive control method divides the bolt pre-tightening process into a non-pre-tightening stage and a pre-tightening stage, selects the motor speed as the system input, and the bolt pre-tightening force as the system output to establish a one-dimensional model predictive control model. A target function is established based on the input value, predicted value, and expected pre-tightening force, and the system input that minimizes the target function value is selected as the motor speed to achieve the dynamic optimal output speed.

[0022] Specifically, the double closed-loop motor vector control takes the optimal speed output by the upper controller as the target speed, outputs the corresponding PWM wave to the motor drive circuit to drive the motor to rotate, thereby realizing the precise pre-tightening function of the bolt.

[0023] The beneficial effects of the present invention achieve precise control of the bolt pre-tightening force through the cooperation of the preload indicating washer and the interactive electric torque wrench, avoiding over-tightening and under-tightening phenomena, improving the safety and reliability of bolt connections, reducing the time for multiple adjustments and re-assembly caused by inaccurate pre-tightening force, improving the assembly efficiency, and at the same time being able to maintain stable pre-tightening force control under different conditions and environments, meeting the pre-tightening requirements of various high-strength bolts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the overall schematic diagram of the present invention;

[0025] Figure 2 is the structural schematic diagram of the preload indicating washer of the present invention;

[0026] Figure 3 is the circuit diagram of the DC voltage stabilization module of the present invention;

[0027] Figure 4 is the circuit diagram of the drive module of the present invention;

[0028] Figure 5 is the partial diagram of the chip peripheral circuit of the present invention;

[0029] Figure 6 is the circuit diagram of the main control module of the present invention.

[0030] The reference numerals are as follows:

[0031] 1. Preload indicating washer; 2. Interactive electric torque wrench; 3. Disc spring washer; 4. Bottom gasket; 5. Retaining ring; 6. Micro-displacement sensor; 7. Main control chip; 8. ADC sampling chip; 9. Data level conversion module; 10. Hall sensor; 11. Control circuit module; 12. Motor drive circuit module; 13. MOSFET. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention relates to an interactive precision force-controlled electric tightening tool, which includes a preload indicating washer and an interactive electric torque wrench. The following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0033] As Figures 1 to 6 shown, the preload indicating washer 1 is composed of a disc spring washer 3, a bottom gasket 4, a retaining ring 5 and a micro displacement sensor 6. The disc spring washer 3 is subjected to pressure during the bolt preloading process and undergoes axial deformation. The bottom gasket 4 is used to support the disc spring washer 3 to ensure its stable deformation during the preloading process. The retaining ring 5 fixes the position of the micro displacement sensor 6 so that it can accurately detect the deformation amount of the disc spring washer 3. The micro displacement sensor 6 is installed between the disc spring washer 3 and the bottom gasket 4, and calculates the current preloading force by detecting the deformation amount of the disc spring washer 3.

[0034] The main control chip 7 of the preload indicating washer 1 uses an STM32F030 processing chip, which integrates an 8MHz high-speed RC oscillator clock source as the system clock. The ADC sampling chip 8 selects an ADS1115 high-precision analog-to-digital converter, which has a 16-bit resolution, supports four IIC slave addresses, has a single power supply operating range of 2.0V to 5.5V, and a maximum sampling rate of 860 samples / second. In the present invention, two ADS1115 chips are used, which can simultaneously perform high-speed AD sampling on 8 washers, ensuring the real-time and accuracy of the data.

[0035] The data level conversion module 9 uses an SP3485EEN chip and its external circuit to convert the TTL signal output by the main control chip 7 into an RS485 signal for long-distance transmission. The RS485 signal transmission mode represents 0 and 1 through the voltage difference between two wires. A voltage difference of -2 to -6V between the two wires represents 0, and a voltage difference of +2 to +6V between the two wires represents 1. This signal transmission mode improves the anti-interference ability of the signal and ensures the stable transmission of the data.

[0036] Before actual use, the preload indicating washer 1 needs to be calibrated to establish the corresponding relationship between the washer displacement and pressure. The specific calibration operation is as follows:

[0037] Calibration steps:

[0038] S1: Install the preload indicating washer 1 on the MTS machine, and use the MTS machine to detect the displacement-pressure of the washer.

[0039] S2: Apply different pressures through the MTS machine and record the corresponding displacement values.

[0040] S3: Input and store the measured displacement-pressure data in the Flash of the main control chip 7.

[0041] Pressure value calculation:

[0042] During the bolt preloading process, the main control chip 7 reads the electrical signal output by the micro-displacement sensor 6 from the ADC sampling chip 8 through the IIC interface.

[0043] The main control chip 7 uses the Lagrange interpolation method to convert the read electrical signal into a pressure value. The specific calculation formula is as follows:

[0044]

[0045] where x represents the axial deformation of the disc spring, y n is the corresponding pressure value in the calibration data, and Ln(x) is the interpolation basis function.

[0046] Average value filtering technology:

[0047] To ensure the stability of the sampled voltage, the main control chip 7 performs 16 voltage samplings on the sensor in each process of reading the pressure value.

[0048] The sampled values are added after being converted into binary form and then processed by window shifting 4 bits. This processing method can effectively suppress the voltage fluctuation phenomenon, maintain the smoothness of the output value of the preloading indicating washer 1 during the bolt preloading process, save the computing power resources for filtering, and ensure the response speed of the washer.

[0049] As Figure 1 shown, the interactive electric torque wrench 2 includes a control circuit module 11 and a motor drive circuit module 12. The control circuit module 11 collects the real-time rotational speed information of the motor through the Hall sensor 10, and outputs a PWM wave to the motor drive circuit module 12 after calculation by the controller. The motor drive circuit module 12 controls the three-phase bridge arm voltage through the MOSFET 13, thereby achieving precise control of the motor.

[0050] The controller of the interactive electric torque wrench 2 adopts an upper and lower layer design. The upper layer controller designs a model predictive control method according to the mechanical model of the bolt preloading process, characterizes the dynamic characteristics of the system and online optimizes the target performance index during the working process to determine the control action at the future moment. The lower layer controller designs a double closed-loop motor vector control to achieve fast tracking of the motor speed.

[0051] The upper layer controller first establishes a mechanical model of the bolt preloading process according to the mechanical principle. This model divides the bolt preloading process into a non-preloading stage and a preloading stage, and is specifically expressed as:

[0052] T=K 1 θ+K 2

[0053] where T is the bolt tightening torque; K 1 and K 2is the tightening coefficient; θ is the bolt torsional angle.

[0054] Select the motor speed ω as the system input and the bolt pre-tightening force F as the system output to establish a one-dimensional model predictive control model. Establish an objective function based on the input value, predicted value, and expected pre-tightening force, and select the system input that minimizes the objective function value as the motor speed to achieve the dynamic optimal output speed.

[0055] The lower-level controller designs a double-closed-loop motor vector control, including a speed loop and a current loop. The speed loop is used to quickly track the optimal speed output by the upper-level controller, and the current loop is used to control the current of the motor to ensure the stable operation of the motor.

[0056] The lower-level controller takes the optimal speed output by the upper-level controller as the target speed and outputs the corresponding PWM wave to the motor drive circuit module 12, thereby driving the motor to rotate and realizing the precise pre-tightening function of the bolt.

[0057] The main control unit of the control circuit module 11 uses the STM32G431 chip and its peripheral circuits. The DC voltage stabilization module circuit uses LMR14052SDDA and BL855CC3BTR33 to provide 5V and 3.3V regulated power supplies for the circuit. MOSFET13 uses Infineon BSC0702LS, and its specific circuit design is as Figure 3 、 Figure 4 、 Figure 5 and Figure 6 shown.

[0058] As Figures 1 to 6 shown, the DC voltage stabilization module includes LMR14052SDDA and BL855CC3BTR33 voltage stabilization chips. LMR14052SDDA provides a 5V regulated power supply for the circuit, and BL855CC3BTR33 provides a 3.3V regulated power supply for the circuit. Capacitors and diodes are used for filtering and protecting the circuit, resistors are used for current limiting and voltage division, and crystal oscillators are used to provide a stable clock signal.

[0059] The input voltage of the power supply module is 48V. Through the conversion of the voltage stabilization chip, it outputs 5V and 3.3V regulated power supplies to provide stable power support for the entire system.

[0060] As Figures 1 to 6 shown, the main control chip 7 of the main control module 11 uses the STM32G431 processing chip. The main control chip 7 communicates with the ADC sampling chip 8 through the IIC interface, communicates with the Hall sensor 10 through the SPI interface, and communicates with the 485 communication module 9 through the UART interface.

[0061] The peripheral circuit of the main control chip 7 includes a crystal oscillator, a capacitor, a resistor and a diode, which are used to provide a stable clock signal, filtering and protection circuits. The buttons are used for manual control and debugging, which is convenient for users to operate during actual use.

[0062] like Figures 1 to 6 As shown, the driving module 12 includes MOSFET 13 and a three-phase bridge arm circuit. MOSFET 13 adopts Infineon BSC0702LS, and the voltage of the three-phase bridge arm is controlled by the PWM wave output by the main control chip 7, so as to achieve precise control of the motor.

[0063] The three-phase bridge arm circuit includes three MOSFETs 13, which respectively control the three-phase voltages of the motor. Capacitors and diodes are used for filtering and protecting the circuit to ensure that the motor runs stably at high speed and high torque.

[0064] The motor of the interactive electric torque wrench 2 uses a synchronous motor with a working voltage of 48V and a torque of 1.6Nm. The output shaft of the synchronous motor is connected to the helical gear, and the output from the helical gear shaft is connected to the planetary reducer through the reversing mechanism. The reduction ratio of the planetary reducer is 840. After the torque is amplified by the reducer, the maximum output torque of the wrench is not less than 3000Nm, which can pre-tighten high-strength bolts of size M36 and below.

[0065] The preload indicator washer 1 and the interactive electric torque wrench 2 use a roll call communication logic, that is, when the wrench preloads a bolt, it will first match the washer used for the bolt, obtain the virtual address of the washer, and then send a preload query request signal with address information in the communication bus of the washer. After receiving the signal, the washer with the corresponding address performs an AD sampling and preload calculation, and outputs the calculation result to the interactive electric torque wrench 2.

[0066] Communication Protocol:

[0067] The Modbus communication protocol is used to realize the one-master-multiple-slave communication mode. The serial port is configured with a baud rate of 9600, 8 data bits, 1 stop bit, and no parity bit.

[0068] The communication level standard adopts the RS485 standard, and transmits differential signals to improve anti-interference ability and achieve long-distance transmission. The specific signal conversion form is: the TTL signal generated by the gasket main control chip 7 is converted into an RS485 signal through the SP3485EEN chip, and the RS485 signal completes the long-distance transmission task on the data bus. The interactive electric torque wrench 2 receives the RS485 signal through the 485 module on it and realizes the conversion from RS485 to TTL signal.

[0069] Communication process:

[0070] Taking the reading of register 00 00 as an example, the request signal sent by the host (Interactive Electric Torque Wrench 2) is: 01 03 00 00 00 02 C4 0B (HEX).

[0071] The signal replied by the slave (Preload Indicator Washer 1) is: 01 03 04 00 00 0D 74 FE 84 (HEX). Among them, 00 00 0D 74 is the AD sampling value, with the high-order bits in front and the low-order bits at the back, representing 3444, integer type.

[0072] Taking the reading of register 00 06 as an example, the request signal sent by the host is: 01 03 00 06 00 02 24 0A (HEX).

[0073] The signal replied by the slave is: 01 03 04 41 CD D7 0A A0 07 (HEX). Among them, 41 CD D7 0A is the pressure value, with the high-order bits in front and the low-order bits at the back, representing 25.73, floating-point type.

[0074] Operating principle and process of the Interactive Precision Force Control Electric Tightening Tool

[0075] Operating principle of the preload indicator washer:

[0076] When the bolt is pre-tightened, the disc spring washer 3 is under pressure and undergoes axial deformation. The micro-displacement sensor 6 detects the deformation of the disc spring washer 3 and converts the deformation into an electrical signal.

[0077] The main control chip 7 reads the electrical signal output by the ADC sampling chip 8 through the IIC interface, processes the signal using the average value filtering technique, and then converts the processed electrical signal into a pressure value through the Lagrange interpolation method.

[0078] The pressure value is transmitted to the Interactive Electric Torque Wrench 2 through the 485 communication module 9 to achieve real-time monitoring of the bolt pre-tightening force.

[0079] Operating principle of the interactive electric torque wrench:

[0080] The Interactive Electric Torque Wrench 2 receives the bolt pre-tightening force value transmitted by the preload indicator washer 1 through the 485 communication module 9.

[0081] The controller calculates the optimal speed of the motor through the model predictive control method according to the received pre-tightening force value.

[0082] The optimal speed is achieved through the double closed-loop motor vector control method to ensure that the motor quickly and accurately reaches the required speed.

[0083] The motor outputs torque through the synchronous motor and the planetary reducer to achieve precise pre-tightening of the bolt.

[0084] Operation process:

[0085] S1: The user installs the preloading indicating washer 1 at the bolt connection and calibrates it through the MTS machine, records the displacement-pressure correspondence and stores it in the Flash of the main control chip 7.

[0086] S2: The user connects the interactive electric torque wrench 2 to the preloading indicating washer 1 to ensure normal communication.

[0087] S3: The user selects the bolt to be preloaded through the buttons on the interactive electric torque wrench 2 and sends a preloading force query request signal.

[0088] S4: After receiving the query request signal, the preloading indicating washer 1 performs an AD sampling and calculates the current preloading force through the Lagrange interpolation method.

[0089] S5: The preloading indicating washer 1 transmits the calculated preloading force value to the interactive electric torque wrench 2 through the 485 communication module 9.

[0090] S6: The upper controller of the interactive electric torque wrench 2 calculates the optimal speed of the motor through the model predictive control method according to the received preloading force value.

[0091] S7: The lower controller takes the optimal speed as the target speed and outputs the corresponding PWM wave to the motor drive circuit module 12 to drive the synchronous motor to rotate.

[0092] S8: The synchronous motor converts the speed into an appropriate torque output through the cooperation of the helical gear and the helical gear.

[0093] S9: The torque output is amplified by the planetary reducer to finally achieve precise preloading of the bolt.

[0094] S10: During the preloading process, the Hall sensor monitors the speed information of the motor in real time, and the main control chip 7 adjusts the output of the PWM wave according to the monitoring result to ensure the stability of the motor speed.

[0095] S11: After the preloading is completed, the interactive electric torque wrench 2 sends a confirmation signal to the preloading indicating washer 1 through the 485 communication module 9 to complete a preloading process.

[0096] The interactive precision force-controlled electric tightening tool of the present invention is particularly suitable for high-strength bolt pre-tightening occasions with high control requirements for bolt pre-tightening force. For example, in the fields of aerospace, automotive manufacturing, heavy machinery, etc., the safety and reliability of bolt connections are of crucial importance. Traditional electric torque wrenches may cause over-tightening or under-tightening of bolts due to the inability to accurately control the pre-tightening force, affecting the stability and safety of the connection. However, through the cooperation of the preload indicating washer and the interactive electric torque wrench of the present invention, precise control of the bolt pre-tightening force is achieved, avoiding over-tightening and under-tightening phenomena, and improving the safety and reliability of bolt connections.

[0097] In the aerospace field, extremely high requirements are imposed on the control of the pre-tightening force of bolt connectors. The interactive precision force-controlled electric tightening tool of the present invention can ensure that the pre-tightening force of bolts always remains within the optimal range under different environmental temperatures and lubrication conditions, avoiding bolt cracks or fractures caused by excessive pre-tightening force, and bolt loosening caused by insufficient pre-tightening force.

[0098] During the automotive manufacturing process, the accuracy of bolt connections directly affects the safety performance of vehicles. The interactive precision force-controlled electric tightening tool of the present invention can achieve precise control of the bolt pre-tightening force on the production line, reducing the time for multiple adjustments and re-assembly caused by inaccurate pre-tightening force, and improving production efficiency and product quality.

[0099] Bolt connections in heavy machinery are required to remain stable under high load and high vibration environments. The interactive precision force-controlled electric tightening tool of the present invention can ensure that the bolt pre-tightening force remains consistent under various working conditions, improving the operating safety and reliability of the machinery.

[0100] The present invention has the following beneficial effects: The interactive precision force-controlled electric tightening tool of the present invention achieves precise control of the bolt pre-tightening force through the cooperation of the preload indicating washer and the interactive electric torque wrench, avoiding over-tightening and under-tightening phenomena, and improving the safety and reliability of bolt connections.

[0101] The preload indicating washer and the interactive electric torque wrench of the present invention adopt a modular design and can be flexibly configured according to actual needs. The preload indicating washer can adapt to bolts of different materials and specifications through a calibration method, and the interactive electric torque wrench can adapt to different pre-tightening working conditions and environmental conditions through a model predictive control method.

[0102] The interactive precision force-controlled electric tightening tool of the present invention adopts high-speed AD sampling and average value filtering technology to ensure the real-time and accuracy of pre-tightening force detection. The combination of the model predictive control method and the double closed-loop motor vector control method makes the control of the motor speed more efficient and reliable, improving the response speed and control accuracy of the overall system.

[0103] Traditional electric torque wrenches often need to select bolts with a larger diameter to leave a margin because they cannot precisely control the pre-tightening force, which increases the assembly difficulty and structural weight. By precisely controlling the pre-tightening force, the present invention can select appropriate bolt specifications, reduce material costs and assembly time, and improve economic efficiency.

[0104] The foregoing description has shown and described several preferred embodiments of the present invention. However, as previously mentioned, it should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and environments, and can be changed within the scope of the inventive concept described herein through the above teachings or the techniques or knowledge in related fields. Any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. An interactive precision force-controlled electric tightening tool, characterized in that: The invention comprises a preload indicating washer (1) and an interactive electric torque wrench (2), wherein: The preload indicating washer (1) is used to detect the deformation amount during the bolt pre-tightening process in real time and convert it into a pressure value; The interactive electric torque wrench (2) adjusts the output rotation speed by receiving the pressure value to achieve accurate control of the bolt pre-tightening force.

2. The interactive precision force-controlled electric tightening tool according to claim 1, characterized in that: The preload indicating washer (1) comprises: The disc spring washer (3) is deformed during the bolt pre-tightening process; A bottom gasket (4) for supporting the disc spring washer (3); A retaining ring (5) fixes the micro displacement sensor (6); The micro displacement sensor (6) is used to detect the deformation amount of the disc spring washer (3) and convert the deformation amount into an electrical signal.

3. The interactive precision force-controlled electric tightening tool according to claim 2, characterized in that: The preload indicating washer (1) further comprises: The main control chip (7) adopts an STM32F030 processing chip, which has an internal integrated 8MHz high-speed RC oscillation clock source as the system clock; ADC sampling chip (8), using ADS1115 high-precision analog-to-digital converter, with 16-bit resolution, supporting 4 IIC slave addresses, single power supply operating range of 2.0V to 5.5V, and maximum sampling rate of 860 samples / second; The data level conversion module (9) uses the SP3485EEN chip and its external circuit to convert the TTL signal output by the main control chip (7) into an RS485 signal to achieve long-distance transmission.

4. The interactive precision force-controlled electric tightening tool according to claim 1, characterized in that: The preload indicating washer (1) establishes a displacement-pressure correspondence relationship through a calibration method. The calibration method detects the correspondence between the displacement and pressure of the washer through an MTS machine and stores the measured data in a main control chip (7). When calculating the bolt preload force, the main control chip (7) converts the electrical signal read from the washer into a pressure value through a Lagrange interpolation method.

5. The interactive precision force-controlled electric tightening tool according to claim 4, characterized in that: The preload indicating gasket (1) adopts average filtering technology during the AD sampling process, samples the voltage of the sensor 16 times, converts the sampled values ​​into binary form, adds them, and performs a 4-bit window shift process. The processed results are used for subsequent pressure calculation to suppress voltage fluctuations and ensure response speed.

6. The interactive precision force-controlled electric tightening tool according to claim 1, characterized in that: The interactive electric torque wrench (2) comprises: The control circuit module (11) collects the real-time rotation speed information of the motor through the Hall sensor (10), and outputs the PWM wave to the motor drive circuit module (12) after calculation by the controller; The motor drive circuit module (12) controls the three-phase bridge arm voltage through the MOSFET (13) to achieve control of the motor.

7. The interactive precision force-controlled electric tightening tool according to claim 6, characterized in that: The main control unit of the control circuit module (11) adopts the STM32G431 chip and its peripheral circuits, the DC voltage regulator module adopts LMR14052SDDA and BL855CC3BTR33 to provide 5V and 3.3V regulated power supplies for the circuit, and the MOSFET (13) adopts Infineon BSC0702LS.

8. The interactive precision force-controlled electric tightening tool according to claim 1, characterized in that: The controller of the interactive electric torque wrench (2) adopts an upper and lower layer design. The upper layer controller designs a model predictive control method based on a mechanical model of the bolt pre-tightening process, characterizes the dynamic characteristics of the system and performs online optimization of the target performance index during the working process to determine the control effect at the future moment. The lower layer controller designs a dual closed-loop motor vector control to achieve rapid tracking of the motor speed.

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