Double-target bolt pre-tightening force intelligent monitoring system based on laser rotation angle measurement

Abstract

The invention provides a double-target bolt pre-tightening force intelligent monitoring system based on laser rotation angle measurement, and the system comprises a laser transmitting module which is used for transmitting parallel laser beams to irradiate a target A and a target B, and the target A and the target B are fixed to the head of a bolt and the surface of a connected piece respectively; the photoelectric receiving module is used for receiving reflected light of the target A and the target B and outputting an angle difference analog signal; the analog-to-digital converter is used for converting the angle difference analog signal into an angle difference digital signal; the microprocessor is used for calculating the pre-tightening force according to the angle difference digital signal; the display is used for displaying the pre-tightening force; the power supply is used for supplying power to the system. The monitoring system can be used in cooperation with the target A arranged on the head of the bolt and the target B arranged on the surface of the connected piece, monitoring of the bolt pretightening force is achieved through the angle difference of reflected light of the two targets, interference of overall displacement / vibration of equipment on the measuring basis can be eliminated, and the environmental adaptability of the system can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of bolt pretightening force monitoring, in particular to a double-target bolt pretightening force intelligent monitoring system based on laser angle measurement. BACKGROUND

[0002] The bolt pretightening force is a key parameter in a mechanical connection system, and the precision thereof directly affects the reliability and safety of equipment operation.

[0003] In the prior art, a single-target laser measurement method is usually used as a monitoring method. However, the detection method is easily disturbed by the overall displacement or vibration of the equipment, the measurement reference is unstable, and the precision is limited. In addition, environmental temperature fluctuations and bolt surface differences (such as roughness and coating) will further increase the measurement error. Therefore, a high-precision, non-contact and non-destructive pretightening force monitoring scheme is urgently needed. SUMMARY

[0004] The application provides a double-target bolt pretightening force intelligent monitoring system based on laser angle measurement, which can be used in cooperation with a target A arranged on the head of a bolt and a target B arranged on the surface of a connected part, the angle difference between the reflected light of the two targets is used to monitor the bolt pretightening force, and the overall displacement / vibration of the equipment can be eliminated to disturb the measurement reference, thereby improving the environmental adaptability of the system.

[0005] The application provides a double-target bolt pretightening force intelligent monitoring system based on laser angle measurement, which comprises: A laser emission module is used to emit parallel laser beams to irradiate a target A and a target B, and the target A and the target B are fixed on the head of a bolt and the surface of a connected part, respectively. A photoelectric receiving module is used to receive the reflected light of the target A and the target B and output an angle difference analog signal. An analog-to-digital converter is electrically connected with the photoelectric receiving module and is used to convert the angle difference analog signal into an angle difference digital signal. A microprocessor is electrically connected with the analog-to-digital converter and is used to calculate the pretightening force according to the angle difference digital signal. A display is electrically connected with the microprocessor and is used to display the pretightening force. A power supply is electrically connected with the laser emission module, the photoelectric receiving module, the analog-to-digital converter, the microprocessor and the display, and is used to supply power to the system.

[0006] In an optional embodiment, the microprocessor calculates the pretightening force by the following steps: The bolt rotation angle is calculated according to the angle difference digital signal. The bolt rotation angle is converted into an elongation according to the bolt pitch. calculate the pre-tightening force of the bolt according to the elongation.

[0007] In an alternative embodiment, the step of calculating the pre-tightening force by the microprocessor comprises calibrating the pre-tightening force according to a friction calibration coefficient.

[0008] In an alternative embodiment, further comprising a temperature sensor for collecting ambient temperature data. The step of calculating the pre-tightening force by the microprocessor comprises compensating the elongation according to the ambient temperature.

[0009] In an alternative embodiment, further comprising a circuit board, the circuit board being a composite circuit board structure, the circuit board comprising a first circuit board and a second circuit board opposite to each other, the laser emitting module and the photoelectric receiving module being integrated on a surface of the first circuit board facing away from the second circuit board, the analog-digital converter being integrated on a surface of the first circuit board facing the second circuit board, the microprocessor and the display being integrated on a surface of the second circuit board facing the first circuit board, and the power supply being integrated on a surface of the second circuit board facing away from the first circuit board.

[0010] In an alternative embodiment, further comprising a housing with a light-transmitting window, the laser emitting module, the photoelectric receiving module, the analog-digital converter, the microprocessor, the display and the power supply being arranged in the housing.

[0011] In an alternative embodiment, further comprising a fixing module arranged in the housing for adsorbing and fixing the housing to a mounting surface.

[0012] In an alternative embodiment, the fixing module is a magnetic seat.

[0013] In an alternative embodiment, further comprising an alarm module electrically connected to the microprocessor for triggering an alarm when the pre-tightening force is lower than a pre-tightening force threshold.

[0014] In an alternative embodiment, further comprising a communication module electrically connected to the microprocessor for transmitting monitoring information to an external device or a cloud.

[0015] The above technical solutions of the present application have the following beneficial technical effects: The double-target bolt pre-tightening force intelligent monitoring system based on laser angle measurement of the present application can be used in cooperation with the target A arranged on the bolt head and the target B arranged on the surface of the connected member, the angle difference of the reflected light of the two targets is used to monitor the bolt pre-tightening force, and in the monitoring process, the system can eliminate the interference of the overall displacement / vibration of the equipment on the measurement reference, which helps to improve the environmental adaptability of the system.

[0016] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are referred to, and specifically described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. The drawings herein are incorporated into the description and form a part of the description, which show the embodiments consistent with the present application, and are used to explain the technical solutions of the present application together with the description. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0018] Figure 1 The structure schematic diagram of a double-target bolt pretightening force intelligent monitoring system based on laser angle measurement provided by the embodiments of the present application is shown; Figure 2 The internal structure schematic diagram of a double-target bolt pretightening force intelligent monitoring system based on laser angle measurement provided by the embodiments of the present application is shown; In the drawings: 1, laser emitting module; 2, photoelectric receiving module; 3, analog-to-digital converter; 4, microprocessor; 5, display; 6, power supply; 7, temperature sensor; 8, first circuit board; 9, second circuit board; 10, housing; 11, light-transmitting window. DETAILED DESCRIPTION

[0019] Now various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement, numerical expression and numerical value of the components and steps set forth in these embodiments do not limit the scope of the present application, unless otherwise specifically stated.

[0020] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, and are only used to explain the present application, and cannot be understood as a limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] The terms "first", "second" in the description and claims of the present application can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in an "or" relationship.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0023] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] Reference Figure 1 And Figure 2 , the embodiment of the present application provides a kind of based on laser corner measurement double target bolt pre-tightening force intelligent monitoring system, including laser emission module 1, photoelectric receiving module 2, analog-digital converter 3 (ADC), microprocessor 4, display 5 and power 6.Laser emission module 1 is used to emit parallel laser beam to irradiate target A and target B, and target A and target B are fixed on bolt head and the surface of connected piece (such as flange or mounting plate etc. fixed by bolt) respectively.Photoelectric receiving module 2 is used to receive the reflected light of target A and target B and output angle difference analog signal.Analog-digital converter 3 is electrically connected with photoelectric receiving module 2, for converting angle difference analog signal into angle difference digital signal.Microprocessor 4 is electrically connected with analog-digital converter 3, for calculating pre-tightening force according to angle difference digital signal.Display 5 is electrically connected with microprocessor 4, for displaying pre-tightening force.Power 6 is electrically connected with laser emission module 1, photoelectric receiving module 2, analog-digital converter 3, microprocessor 4 and display 5, for system power supply.

[0025] The working process of the double-target bolt pretightening force intelligent monitoring system based on laser angle measurement includes four stages: signal acquisition stage, signal conversion stage, data operation stage and result output stage. In the signal acquisition stage, the laser emission module 1 outputs parallel red light, which vertically irradiates target A located on the bolt head (moving with the bolt) and target B located on the surface of the connected part (fixed), so as to realize non-contact angle measurement and provide a light signal basis for subsequent angle difference calculation. The photoelectric receiving module 2 is responsible for receiving the reflected light of the two targets and converting the "reflected light angle difference" into an analog signal, which is collected regularly. The core function is to convert the light signal into an electrical signal for subsequent processing. In the signal conversion stage, the ADC receives the angle difference analog signal of the photoelectric receiving module 2, converts it into a digital signal after conditioning, and realizes high-precision signal conversion to provide accurate digital data for the microprocessor 4 operation. In the data operation stage, the microprocessor 4, as the signal processing core, calculates the bolt pretightening force according to the angle difference digital signal. In the result output stage, the display screen displays the bolt pretightening force in real time.

[0026] The double-target bolt pretightening force intelligent monitoring system based on laser angle measurement of the embodiments of the present application can be used with target A arranged on the bolt head and target B arranged on the surface of the connected part. The angle difference of the reflected light of the two targets is used to monitor the bolt pretightening force. During the monitoring process, the overall displacement of the system has the same effect on the two targets, so that the interference of the overall displacement / vibration of the device on the measurement reference can be eliminated, which helps to improve the environmental adaptability of the system.

[0027] In some embodiments, the laser emission module 1 adopts OSRAM SFH4550 model, the output power is 5mW, and the wavelength is 650nm.

[0028] In some embodiments, the photoelectric receiving module 2 selects Hamamatsu S5991.

[0029] In some embodiments, the analog-to-digital converter 3 selects the ADC of ADS1255 model, the ADC is 24 bits, and the sampling rate is 30kHz.

[0030] In some embodiments, the microprocessor 4 selects STM32F407 model, the microprocessor 4 has a main frequency of 168MHz and a FPU floating point unit. The microprocessor 4 processes the data transmitted by the ADC in real time by means of an interrupt service program, and the response time can be controlled within 50μs.

[0031] In some embodiments, the display 5 selects ST7735 model, and the display 5 is provided with a touch screen. The touch screen is used to input related parameters, such as bolt specifications, material, effective length, calibration coefficient and pretightening force threshold value, etc.

[0032] In some embodiments, the power supply 6 provides power through two paths: one path, after being regulated by a voltage regulator, supplies 3.3V to the ADC, microprocessor 4, and display 5; the other path, after being boosted by a voltage booster, supplies 3.3V to the laser emitting module 1 and photoelectric receiving module 25V. In this embodiment, the power supply 6 is equipped with a charging interface for replenishing power.

[0033] In some embodiments, the microprocessor 4 calculates the preload force through the following steps: The bolt rotation angle is calculated based on the digital signal of the angle difference. The formula for calculating the rotation angle is: X = Y × 180 / π In the above formula, X is the turning angle and Y is the angle difference; Based on the bolt pitch, the bolt angle is converted into elongation. The formula for calculating elongation is: ΔL = (X / 360°) × d In the above formula, X is the rotation angle and d is the pitch; The preload of the bolt is calculated based on the elongation. The formula for calculating the preload is: F = E × A × ΔL / L In the above formula, E is the elastic modulus of the bolt, A is the cross-sectional area of ​​the bolt, ΔL is the elongation, and L is the effective length of the bolt (i.e., the length of the bolt clamping section).

[0034] In other words, the microprocessor 4, as the signal processing core, first converts the angle difference digital signal into the relative rotation angle of the bolt, then calculates the elongation by combining the pre-stored or pre-input bolt pitch, and finally calculates the final preload based on the elongation.

[0035] In some embodiments, the step of the microprocessor 4 calculating the preload includes calibrating the preload according to a friction calibration coefficient to improve measurement accuracy.

[0036] After improvements, microprocessor 4 calculates the preload force through the following steps: The bolt rotation angle is calculated based on the digital signal of the angle difference. The formula for calculating the rotation angle is: X = Y × 180 / π Based on the bolt pitch, the bolt angle is converted into elongation. The formula for calculating elongation is: ΔL = (X / 360°) × d The preload of the bolt is calculated based on the corrected elongation. The formula for calculating the preload is as follows: F = E × A × ΔL / L × k In the above formula, k is the friction calibration coefficient.

[0037] It should be noted that the friction calibration coefficient refers to the calibration coefficient corresponding to the actual friction coefficient, which can be calculated from the theoretical formula of thread preload.

[0038] In some embodiments, the step of calculating the pretightening force by the microprocessor 4 comprises compensating the elongation according to the ambient temperature to improve the measurement accuracy.

[0039] With the above improvement, the microprocessor 4 calculates the pretightening force by the following steps: The bolt rotation angle is calculated according to the angle difference digital signal, and the calculation formula of the rotation angle is: X=Yx180 / π The bolt rotation angle is converted into the elongation according to the bolt pitch, and the calculation formula of the elongation is: ΔL=(X / 360°)xd The thermal expansion compensation is performed according to the temperature digital signal to correct the elongation, and the correction formula of the elongation is: ΔL'=ΔL-αxLxΔT In the above formula, α is the thermal expansion coefficient of the bolt, and ΔT is the difference between the current ambient temperature and the standard temperature.

[0040] The pretightening force of the bolt is calculated according to the corrected elongation, and the calculation formula of the pretightening force is: F=ExAxΔL' / L Or, F=ExAxΔL' / Lxk In the above formula, k is the friction calibration coefficient.

[0041] As can be seen, the system can further comprise a temperature sensor 7 for collecting ambient temperature data. In the present embodiment, the temperature sensor 7 is electrically connected with the analog-to-digital converter 3, the analog-to-digital converter 3 is further used to convert the temperature analog signal into a temperature digital signal, and the microprocessor 4 receives the temperature digital signal and compensates the elongation according to the temperature data of the received temperature digital signal.

[0042] In some embodiments, the system further comprises a circuit board, and the laser emitting module 1, the photoelectric receiving module 2, the analog-to-digital converter 3, the microprocessor 4, the display 5 and the power supply 6 are all integrated on the circuit board. In the present embodiment, the circuit board is a composite circuit board structure, and the circuit board comprises opposite first and second circuit boards 8 and 9. The laser emitting module 1 and the photoelectric receiving module 2 are integrated on the surface of the first circuit board 8 away from the second circuit board 9, the analog-to-digital converter 3 is integrated on the surface of the first circuit board 8 facing the second circuit board 9, the microprocessor 4 and the display 5 are integrated on the surface of the second circuit board 9 facing the first circuit board 8, and the power supply 6 is integrated on the surface of the second circuit board 9 away from the first circuit board 8. In this way, the layered arrangement of the various devices can be achieved, which helps to reduce electromagnetic interference between the devices and ensure the reliability of the system.

[0043] In a specific arrangement, the laser emitting module 1 is connected to the microprocessor 4 through the via signal line by the GPIO control pin, and receives the emission control instruction sent by the microprocessor 4; the photoelectric receiving module 2 transmits the collected reflected light angle difference analog signal to the ADC through the via signal line to convert it into a digital signal; the ADC is connected to the microprocessor 4 through the SPI interface and the via signal line, transmits the processed digital signal to the microprocessor 4, and at the same time, the analog signal collected by the temperature sensor 7 is also transmitted to the ADC through the via signal line to complete the temperature data transmission; the microprocessor 4 is connected to the display 5 through the SPI interface and the FPC flat cable, and outputs real-time data such as pre-tightening force and temperature, and the microprocessor 4 also outputs an alarm signal through the via signal line to realize timely prompting of the device state.

[0044] In some embodiments, the system further comprises a shell 10 with a light-transmitting window 11, and the laser emitting module 1, the photoelectric receiving module 2, the analog-to-digital converter 3, the microprocessor 4, the display 5 and the power supply 6 are all arranged in the shell 10. In this embodiment, the shell 10 can be made of ABS engineering plastic, with a size of 120mm x 80mm x 50mm, a window of 45mm x 35mm reserved on the front, and a 0.3mm thick tempered glass with a light transmittance of not less than 92% embedded. In use, the laser emitting module 1 and the photoelectric receiving module 2 can transmit and receive laser through the tempered glass. In addition, the side of the shell 10 can also be provided with a mounting port for mounting the display 5, so that the user can observe or operate the display 5 from the side of the shell 10. In this way, the integration and protection of the device can be realized, preventing the device from being affected by the external environment and ensuring the reliability of the system.

[0045] In some embodiments, the system further comprises a fixing module arranged in the shell 10 for adsorbing and fixing the shell 10 to a mounting surface. In this embodiment, the fixing module is a magnetic seat arranged on the side of the shell 10 away from the light-transmitting window 11, and the suction force of the magnetic seat is not less than 50N. In this way, the installation efficiency can be improved, which is especially suitable for the rapid maintenance scene of industrial equipment.

[0046] In some embodiments, the system further comprises an alarm module electrically connected to the microprocessor 4 for triggering an alarm when the pre-tightening force is lower than the pre-tightening force threshold. In this embodiment, the alarm module includes a buzzer and an LED. When the pre-tightening force is lower than the threshold, the buzzer sounds and the LED flashes intermittently. Of course, in actual application, the display 5 can also participate in the alarm. For example, when the pre-tightening force is not lower than the threshold, the display 5 displays the green character "pre-tightening force meets the standard", and when the pre-tightening force is lower than the threshold, the display 5 flashes the red character "insufficient pre-tightening force".

[0047] In some embodiments, the system further comprises a communication module electrically connected with the microprocessor 4, for transmitting the monitoring information to an external device or cloud. In the present embodiment, the communication module can comprise a wired communication device and a wireless communication device.

[0048] For the convenience of understanding, the use method of the double-target bolt pretightening force intelligent monitoring system based on laser rotation angle measurement according to the embodiment of the present application is illustrated below.

[0049] 1. Install target A and target B.

[0050] Before installing the targets, the bolt head and the surface of the connected part need to be pretreated. Use a dust-free cloth soaked with 99.9% pure anhydrous alcohol to wipe repeatedly until no obvious stains can be seen on the cloth. This is done to remove oil stains and oxidation layers on the surface, as oil stains can reduce the adhesion of the adhesive, and oxidation layers can affect the surface flatness. After the treatment, use a roughness meter to check and ensure that the surface roughness is controlled within Ra≤1.6μm.

[0051] Install target A. Align and paste the φ10mm×0.5mm polyimide aluminum-plated target (reflectivity≥95%) with the center of the bolt head as the reference, and then press it evenly with a 500g special pressing block with a silicone pad on the bottom for 10 seconds. The silicone pad can prevent scratching the target. The purpose of pressing is to ensure that the gap between the adhesive of target A and the surface of the bolt does not exceed 0.1mm.

[0052] Install target B. First, mark the radial 80mm position on the surface of the connected part with the bolt axis as the center, and then paste target B in the same way. After pasting, use a square ruler to calibrate to ensure that the parallelism deviation between the connecting line of the two targets and the bolt axis does not exceed 0.5°. Then let the adhesive cure for 5 minutes, and after 24 hours, the adhesive strength can reach 10N / cm 2 , which can meet the use requirements in a vibrating environment.

[0053] 2. Install the double-target bolt pretightening force intelligent monitoring system based on laser rotation angle measurement.

[0054] First, use the magnetic seat to fix the system on the installation surface. Use a feeler gauge to check the fit between the bottom surface of the housing and the installation surface to ensure that the gap is ≤0.5mm, preventing relative displacement due to vibration during measurement (in a 10Hz vibrating environment, the displacement needs to be controlled within ≤0.1mm).

[0055] Subsequently short press the power button (at this time the working current < 5mA), the laser emitting module will emit two beams of red light (light spot diameter < 1mm), by adjusting the base on each circle 1mm travel fine tuning knob, let the light spot cover the cross mark in the center of target A and target B, and the offset is not more than 0.5mm. When the display screen on the side of the shell appears green text prompt "alignment success", it means that the alignment is completed.

[0056] 3. Parameter configuration and calibration process.

[0057] Parameter configuration operation is mainly completed through the touch interface of the display screen. First, input the bolt specification "M30x3.5", the system will automatically identify the pitch of 3.5mm, which will be used for the conversion of the angle and the elongation. The specific formula is that the elongation is equal to the angle divided by 360 degrees and multiplied by the pitch; then input the material "35CrMo", the system will call the corresponding 200GPa elastic modulus (E) and 11.5x10 -6 / ℃ thermal expansion coefficient (a) from the built-in material library; then input the effective length "150mm", here the effective length refers to the length (L) of the bolt clamping section, which is the key parameter in the pre-tightening force calculation formula (F=ExAxDL / L, where A is the cross-sectional area of the bolt); finally, input the target pre-tightening force "1800kN", the system will automatically calculate the warning threshold as 1530kN, which is 85% of the target value, and set the data storage interval to 1 second, in order to balance the data volume and timeliness.

[0058] Select a digital torque wrench with a range of 0-1000N•m and an accuracy of ±1%, and tighten the bolt to 500N•m according to the process requirements of bolt pre-tightening. At this time, the corresponding angle is about 6°, which meets the principle of "small torque calibration". Then collect data, the system will record the "torque-angle" data within 5 seconds at a sampling frequency of 20Hz, a total of 100 groups. The microprocessor will perform curve fitting on these data by least squares method, ensuring that the goodness of fit R 2 is not less than 0.99. Finally, calculate the coefficient based on the theoretical formula of thread pre-tightening force (T=KxFxd, where K is the torque coefficient) to inversely calculate the calibration coefficient corresponding to the actual friction coefficient. In this case, the coefficient is 0.98, which will be stored in the Flash memory and will not be lost even after power failure. The coefficient will be automatically introduced in the subsequent calculation of pre-tightening force (i.e. F=calculated value x k).

[0059] 4. The whole process of monitoring and data processing.

[0060] In use, the laser emitting module continuously emits two parallel laser beams with a distance of 20mm, while the photoelectric receiving module outputs 0-5V angle difference analog signals every 100ms, which are converted into digital signals by ADC and transmitted to the microprocessor. At the same time, the temperature sensor collects environmental temperature data every 100ms, which are processed by the signal conditioning circuit (filter bandwidth 10Hz) and input into the ADC.

[0061] After receiving these digital signals, the microprocessor first calculates the relative rotation angle according to the formula "rotation angle = angle difference x 180 / π". For example, if the measured angle difference corresponds to a rotation angle of 18°, combined with the pitch of the bolt 3.5mm, the elongation ΔL = (18° / 360°) x 3.5mm = 0.175mm can be calculated. If the environmental temperature changes, such as from 25℃ to 40℃, the system will automatically perform temperature compensation, and the corrected elongation ΔL' = ΔL - α x L x ΔT, where α is the thermal expansion coefficient of 35CrMo material 11.5 x 10 -6 / ℃, L is the effective length of the bolt 150mm, and ΔT is the temperature difference 15℃. After substitution, ΔL' = 0.175 - 11.5e-6 x 150 x 15 = 0.149mm. Then substitute the pre-tightening force formula F = (E x A x ΔL' / L) x k, where E is the elastic modulus 200GPa, A is the cross-sectional area of the bolt 693mm 2 (the effective area coefficient of the thread is π x (30 / 2) 2 x 0.85), and k is the calibration coefficient 0.98. Finally, the pre-tightening force is calculated to be about 1584kN. When the pre-tightening force reaches or exceeds the target value of 1800kN, the buzzer on the side of the shell will emit a 2-second 60dB prompt sound, and the display screen will pop up a green "standard" word; if the pre-tightening force is below the warning threshold of 1530kN, the display screen will flash a "warning" prompt in red font, and all data will be stored with a timestamp in the format "YYYY-MM-DD HH:MM:SS, F(kN), T(℃)".

[0062] One or more embodiments of the present specification are intended to cover all such alternatives, modifications and variations falling within the broad scope of the appended claims. Therefore, any omission, modification, equivalent replacement, improvement, etc. made in the spirit and principle of one or more embodiments of the present specification shall be included in the scope of protection of the present application.

[0063] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A dual-target bolt preload intelligent monitoring system based on laser rotation angle measurement, characterized in that, include: A laser emitting module is used to emit a parallel laser beam to irradiate target A and target B, wherein target A and target B are respectively fixed to the bolt head and the surface of the connected parts; A photoelectric receiving module is used to receive the reflected light from the target A and the target B and output an analog signal of the angle difference; An analog-to-digital converter, electrically connected to the photoelectric receiving module, is used to convert the angle difference analog signal into an angle difference digital signal; The microprocessor, electrically connected to the analog-to-digital converter, is used to calculate the preload force based on the angle difference digital signal; A display, electrically connected to the microprocessor, is used to display the preload force; The power supply is electrically connected to the laser emitting module, the photoelectric receiving module, the analog-to-digital converter, the microprocessor, and the display, and is used to provide power to the system.

2. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 1, characterized in that, The microprocessor calculates the preload force through the following steps: Calculate the bolt rotation angle based on the digital signal of the angle difference; The bolt angle is converted into elongation based on the bolt pitch; The preload of the bolt is calculated based on the elongation.

3. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 2, characterized in that, The step of the microprocessor calculating the preload includes calibrating the preload according to the friction calibration coefficient.

4. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 2, characterized in that, It also includes a temperature sensor for collecting ambient temperature data; The step of the microprocessor calculating the preload includes: compensating for the elongation based on the ambient temperature.

5. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 1, characterized in that, It also includes a circuit board, which is a composite circuit board structure. The circuit board includes a first circuit board and a second circuit board facing each other. The laser emitting module and the photoelectric receiving module are integrated on the surface of the first circuit board away from the second circuit board. The analog-to-digital converter is integrated on the surface of the first circuit board facing the second circuit board. The microprocessor and the display are integrated on the surface of the second circuit board facing the first circuit board. The power supply is integrated on the surface of the second circuit board away from the first circuit board.

6. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 1, characterized in that, It also includes a housing with a light-transmitting window, in which the laser emitting module, the photoelectric receiving module, the analog-to-digital converter, the microprocessor, the display and the power supply are all housed.

7. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 6, characterized in that, It also includes a fixing module, which is disposed on the housing and is used to magnetically fix the housing to the mounting surface.

8. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 7, characterized in that, The fixing module is a magnetic base.

9. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 1, characterized in that, It also includes an alarm module, which is electrically connected to the microprocessor and is used to trigger an alarm when the preload is lower than the preload threshold.

10. The intelligent monitoring system for dual-target bolt preload based on laser rotation measurement according to claim 1, characterized in that, It also includes a communication module, which is electrically connected to the microprocessor, for transmitting monitoring information to external devices or the cloud.

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