Water turbine spray needle abrasion amount measuring device and method based on laser displacement sensor

Abstract

The invention provides a water turbine spray needle abrasion amount measuring device and method based on a laser displacement sensor, and belongs to the technical field of impact type water turbine spray needle abrasion amount measurement. Comprising a spray needle and a water distribution ring pipe, a fixing box is fixedly installed below the water distribution ring pipe, a laser displacement sensor is installed in the fixing box, the position of the laser displacement sensor is right opposite to the spray needle, and the laser displacement sensor is connected with a water turbine spray needle abrasion amount online monitoring system. The laser displacement sensor can determine the surface displacement amount by monitoring the laser reflection intensity change of the surface of an object, and the monitored displacement amount is calculated through the water turbine spray needle abrasion amount on-line monitoring system, so that the non-contact and high-precision measurement of the spray needle surface abrasion amount is realized. The detachable inspection of the spray needle during the unit maintenance period is avoided, the monitoring precision of the abrasion loss of the spray needle is improved, and meanwhile, the normal operation of the water turbine is prevented from being influenced by excessive abrasion of the spray needle.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring the abrasion amount of a jet needle of an impulse turbine, and in particular relates to a device and a method for measuring the abrasion amount of a jet needle of a turbine based on a laser displacement sensor. Background Art

[0002] The impulse turbine uses a DC nozzle as a water guide mechanism. After the water flows through the DC nozzle, it is ejected from the nozzle to form a powerful jet. The jet rushes to the runner bucket to drive the runner to rotate and do work. The nozzle needle is located in the nozzle part of the impulse turbine and is responsible for converting the pressure energy of the water flow in the nozzle into the kinetic energy of the jet. The design of the nozzle needle directly affects the velocity distribution of the water flow and the stability of the jet. Since the impulse turbine is usually arranged in areas with high head and high sediment content, the fine sand particles carried by the high-speed water flow entering the injection mechanism will cause wear on the nozzle needle and nozzle part. Wear will not only cause deformation of the nozzle needle surface, but also change the hydraulic characteristics and flow conditions of the high-speed jet, which will lead to a decrease in turbine efficiency and reduced operating stability, and even bring safety hazards to the operation of the impulse unit. Therefore, understanding the abrasion of the nozzle needle is of great significance for preventing deformation of the surface of the injection mechanism, stabilizing the flow state of high-speed water flow, and preventing unit accidents.

[0003] Studies have shown that the wear of the needle is positively correlated with the sediment concentration of the water flow, and when the sediment concentration is constant, the wear of the needle is related to the sediment particle size. Usually, sand particles with smaller particle sizes are more destructive to the surface structure of the needle. Through the analysis of the flow of the needle channel at different openings, it is found that when the needle opening is small, its surface pressure will decrease along the flow direction until negative pressure occurs, and then cavitation will occur. This phenomenon will aggravate the damage of the needle head together with the sediment wear.

[0004] At present, the research on needle wear mainly adopts two methods: numerical calculation and experimental research, and the numerical calculation method is more common. The existing numerical calculation mainly relies on the selected empirical or semi-empirical wear formula, which cannot accurately calculate the actual wear of the needle on site; while the experimental research requires accurate analysis of the needle surface wear under laboratory conditions, and cannot realize online monitoring of the needle wear, which has certain limitations. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem that the existing calculation method for the needle erosion amount cannot achieve accurate calculation and online monitoring of the needle erosion amount, and to provide a turbine needle erosion amount measurement device and method based on a laser displacement sensor.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: In the first aspect, the present invention provides a device for measuring the abrasion of a turbine needle based on a laser displacement sensor, comprising a nozzle needle and a water distribution ring pipe, a fixed box being fixedly installed below the water distribution ring pipe, a laser displacement sensor being installed inside the fixed box, the laser displacement sensor being installed opposite to the nozzle needle, and the laser displacement sensor being connected to an online monitoring system for the abrasion of a turbine needle.

[0007] The laser displacement sensor includes a beam emitting mirror, a beam receiving mirror, a semiconductor laser and a beam receiving element, wherein the semiconductor laser is used to emit laser light, the beam emitting mirror is installed at the output end of the semiconductor laser, the beam emitting mirror and the beam receiving mirror are used to collimate and focus the laser beam, the beam receiving mirror is located inside the laser displacement sensor, the beam receiving element is located at the output end of the beam receiving mirror, and the beam receiving element is used to convert the received laser beam into an electrical signal.

[0008] A stepper motor is arranged on the top of the fixed box, the stepper motor is connected to an electric slider, and the stepper motor controls the electric slider to slide on the staggered slide rails, and the staggered slide rails are installed parallel to the top of the fixed box.

[0009] The electric slider is detachable, and threads matching with fixing bolts are arranged inside the electric slider and above the laser displacement sensor. The laser displacement sensor is fixed on the staggered slide rail through the fixing bolts and the electric slider.

[0010] Waterproof sand baffles are arranged at both ends of the fixed box, and the height of the water-proof sand baffles can be adjusted.

[0011] The bottom of the fixed box is provided with an opening structure to ensure that the laser displacement sensor is not obstructed in transmitting and receiving light beams.

[0012] It includes a deflector, which is located between the spray needle and the rotating wheel. The opening position of the deflector is located at the overlapping part of the top of the deflector and the protrusion of the spray needle. The measurement position of the laser displacement sensor is the spray needle part exposed at the deflector opening.

[0013] The water turbine needle abrasion amount online monitoring system includes a computer system, a PLC controller, and a motor power supplier; The laser displacement sensor is used to collect the displacement data of the spray needle; The computer system is used to process and display the data collected by the laser displacement sensor; The PLC controller is used to control the position of the electric slider driven by the stepper motor; The motor power supplier is used to supply power to the stepper motor.

[0014] In the second aspect, the present invention provides a method for measuring the abrasion of a turbine needle based on a laser displacement sensor, which is characterized in that the turbine is stopped, the equipment is adjusted to an initial state, the online monitoring system for the abrasion of the turbine needle is started and the laser displacement sensor is calibrated, the surface of the impulse turbine needle is precisely measured by the laser displacement sensor, the measurement data is collected and analyzed, and the measurement data is compared with a set abrasion warning value. When the measurement data exceeds the warning value, the system automatically sends a warning signal to prompt maintenance personnel to check or replace the needle.

[0015] The method for calibrating the laser displacement sensor is: The stepper motor is controlled by the PLC controller to operate the electric slide to the top of the spray needle, ensuring that the beam emitting mirror and the beam receiving mirror surface of the laser displacement sensor are parallel to the surface of the spray needle, and the laser displacement sensor is fixed on the staggered slide rail.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a device and method for measuring the abrasion of a water turbine needle based on a laser displacement sensor, comprising a nozzle needle and a water distribution ring pipe, a fixed box fixedly installed below the water distribution ring pipe, a laser displacement sensor installed inside the fixed box, the laser displacement sensor is installed opposite to the nozzle needle, and the laser displacement sensor is connected to an online monitoring system for the abrasion of a water turbine needle. During measurement, the operation of the water turbine is stopped, the equipment is adjusted to an initial state, the online monitoring system for the abrasion of a water turbine needle is started, and the laser displacement sensor is calibrated. The surface of the impulse turbine needle is precisely measured by the laser displacement sensor, the measurement data is collected and analyzed, and the measurement data is compared with the set abrasion warning value. When the measurement data exceeds the warning value, the system automatically sends a warning signal to prompt the maintenance personnel to check or replace the needle. The laser displacement sensor can determine the surface displacement by monitoring the change in the laser reflection intensity on the surface of the object, and the monitored displacement is calculated by the online monitoring system for the abrasion of a water turbine needle, thereby realizing non-contact and high-precision measurement of the wear on the needle surface. The disassembly inspection of the nozzle needle during the unit maintenance is avoided and the monitoring accuracy of the nozzle needle wear is improved, while the normal operation of the turbine is prevented from being affected by excessive abrasion of the nozzle needle.

[0017] Furthermore, the fixing box is fixed below the top of the water distribution ring pipe by bolts, which can ensure that the interference to the measuring system is minimal when the impulse turbine is working. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic diagram of the device of the present invention; Figure 2 It is a schematic diagram of the laser displacement sensor of the present invention; Figure 3 This is a schematic diagram of the triangulation principle of the laser displacement sensor of the present invention; Figure 4 This is a schematic diagram of a fixing box for a laser displacement sensor of the present invention; Figure 5 This is a schematic diagram of the opening structure of the laser displacement sensor fixing box of the present invention; Figure 6 A schematic diagram of the staggered slide rails of the present invention; Figure 7 It is a schematic diagram of the control system of the present invention; Figure 8 It is a schematic diagram of the opening structure of the deflector of the present invention.

[0020] Explanation of the reference numerals in the figure: 1. Pipeline system; 2. Fixing groove; 3. Fixing box; 4. Laser displacement sensor; 41. Beam emitting mirror; 42. Beam receiving mirror; 43. Semiconductor laser; 44. Beam receiving element; 5. Stepper motor; 6. Waterproof sand baffle; 7. Staggered slide rail; 8. Electric slider; 9. Fixing bolt; 10. Opening structure; 11. Deflector; 12. Deflector opening; 13. Spray needle. DETAILED DESCRIPTION

[0021] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] Embodiment 1: like Figure 1 As shown, a device for measuring the abrasion amount of a water turbine needle based on a laser displacement sensor comprises a pipeline system 1 and a fixing groove 2. The fixing groove 2 is arranged above a water distribution ring pipe and is used to fix the pipeline system 1. A fixing box 3 is fixed below the top of the water distribution ring pipe. A laser displacement sensor 4 is installed inside the fixing box 3. The laser displacement sensor 4 is installed opposite to the needle 13. Preferably, the fixed box 3 is fixed below the top of the water distribution ring pipe by bolts. Since the water flow rarely flows to the top of the water distribution ring pipe after impacting the runner, installing the fixed box 3 here can ensure that the interference to the measurement system is minimized when the impulse turbine is working. The interior of the pipeline system 1 can be partially retracted to match different sensor positions. The laser displacement sensor 4 and the stepper motor 5 are connected internally. After passing above the water distribution ring pipe outside the fixed box 3, they are buried in concrete and connected to the outside. The fixed groove 2 is set above the water distribution ring pipe to fix the pipeline system 1 to prevent the pipeline from deviating from its position or even breaking due to excessive vibration of the unit. The power line of the stepper motor 5, the power line of the laser displacement sensor and the optical fiber cable are all connected to the outside through the pipeline system 1.

[0026] like Figure 2 and Figure 3As shown, the laser displacement sensor 4 is composed of a beam emitting mirror 41, a beam receiving mirror 42, a semiconductor laser 43 and a beam receiving element 44. The semiconductor laser 43 is located on the side of the laser displacement sensor 4 and is used to emit laser light. The beam emitting mirror 41 is installed at the output end of the semiconductor laser 43. The beam emitting mirror 41 is used to collimate and focus the laser beam. The beam receiving mirror 42 is located inside the laser displacement sensor 4. The beam receiving mirror 42 is used to collimate and focus the laser beam. The beam receiving element 44 is located at the output end of the beam receiving mirror 42. The beam receiving element 44 is used to convert the received laser beam into an electrical signal. The laser displacement sensor 4 uses the principle of triangulation. First, a certain point on the surface of the object is selected as a reference point. The laser emitted by the semiconductor laser 43 passes through the beam emitting mirror 41 and hits the reference point. The reflected laser passes through the beam receiving mirror 42 and hits the center of the beam receiving element 44 inside the sensor. Through the one-to-one correspondence between the light receiving point and the measured distance, the position of the measuring point can be calculated with the help of the position of the light receiving point, thereby completing the calibration.

[0027] like Figure 4 and Figure 5 As shown, the fixed box 3 contains a laser displacement sensor 4, a stepper motor 5, a waterproof sand baffle 6, a staggered slide rail 7, an electric slider 8 and a fixing bolt 9. Figure 6 The figure shows a schematic diagram of the staggered slide rail 7, which is parallel to the bottom and top surfaces of the fixed box 3 and fixed to the box wall by means of the edge of the short rail. The stepper motor 5 is placed on the top of the fixed box 3, and the motor power supply is controlled by the PLC controller. The stepper motor 5 controls the electric slider 8 to move on the staggered slide rail 7. The electric slider 8 is a detachable slider, and has threads matching the fixing bolts 9 inside and in the middle above the laser displacement sensor 4. The laser displacement sensor 4 can be directly fixed on the staggered slide rail 7 with the help of the electric slider 8 and the fixing bolts 9. An opening structure 10 matching the position of the laser displacement sensor 4 is installed at the bottom of the fixed box 3, which can ensure that the emission and reception of the laser displacement sensor 4 after the fixed position is not hindered. In order to prevent a small amount of splashing water and mud from entering the fixed box through the pores, there is a fixed transparent rotating waterproof sand baffle 6 at both ends of the fixed box 3, and the waterproof sand baffle 6 can be adjusted in height. Before the turbine is started, the waterproof sand baffle 6 is adjusted to the bottom of the fixed box opening structure 10 to prevent water and sand from entering the box.

[0028] like Figure 7As shown, the system for controlling the operation of the laser displacement sensor 4 includes computer hardware, computer software, PLC controller, motor power supply and stepper motor 5. The computer hardware is composed of a host, a display, a power supply, etc. The software mainly includes PLC program software, sensor data acquisition software, and sensor data processing software. The PLC controller connects the computer system and the motor power supply to realize the displacement control of the laser displacement sensor 4. At the same time, the laser displacement sensor 4 is also connected to the computer system through an optical fiber cable for data transmission.

[0029] like Figure 8 As shown, the deflector 11 includes a deflector 11, which is located between the spray needle 13 and the rotating wheel. The deflector opening 12 is located at the portion where the top of the deflector 11 overlaps with the protrusion of the spray needle 13 when the stroke is fully closed. The measurement range of the laser displacement sensor 4 is the portion of the spray needle 13 exposed at the deflector opening 12. The deflector opening 12 is in the shape of a rectangle, with the long side slightly smaller than the width of the top of the deflector 11, the wide side being equal to the distance between the two sides of the top of the deflector 11, and the width of the wide side slightly smaller than the distance between the two points at the front end of the spray needle 13.

[0030] Embodiment 2: The method for measuring the abrasion amount of a water turbine nozzle based on a laser displacement sensor comprises the following steps: S1: Stop the operation of the impulse turbine, adjust the impulse turbine needle 13 to the fully closed position, fully close the deflector 11, and wait for all the water on the surface of the water distribution ring pipe and the needle 13 to evaporate; S2: Start the system and observe whether the laser displacement sensor 4, computer, PLC controller and stepper motor 5 in the system can work normally, and ensure that the laser displacement sensor 4 and computer system can normally collect and display data before the system works; S3: Open the waterproof sand baffle 6, and control the stepper motor 5 through the PLC controller to operate the electric slide 8 to the top of the calibration point of the spray needle 13, ensuring that the surface of the sensor beam transmitting mirror 41 and the beam receiving mirror 42 are parallel to the surface of the spray needle 13. After determining the measurement position of the calibration point, fix the measurement position of the laser displacement sensor 4 with the fixing bolt 9; S4: Set the parameters of laser displacement sensor 4, the sampling period is set to 1ms, the sampling frequency is set to 1000 times / s, the sampling accuracy is set to 1μm, and the maximum sampling distance is set to 20cm (which can be adjusted according to the actual position of the spray needle 13), ensuring that each point within the measurement range of the spray needle 13 is within the maximum sampling distance range. Use the data processing software to display the distance data as the average value of one measurement data every 10ms; S5: Select the measurement range of the spray needle 13 and calibrate it. For the conical surface of the spray needle 13, it is necessary to perform horizontal measurement in the direction perpendicular to the spray needle stroke. Use the laser displacement sensor 4 to calibrate the boundary points of the measurement line segment on the surface of the spray needle 13 perpendicular to the spray needle stroke (the laser displacement sensor 4 translates along the short side track of the staggered slide rail 7). The vertical distance of the boundary point is less than the vertical distance of the short side of the deflector opening 12. Use the boundary point as the reference point to calibrate the laser displacement sensor 4, and use the obtained data as the reference value of the distance between the laser displacement sensor 4 and the surface of the spray needle 13. Record 1000 sets of distance data between the laser displacement sensor 4 and the reference point, filter out the data with a standard deviation greater than 10% through the matlab program, and average the remaining data, and use the result as the calibration value of the laser displacement sensor 4; S6: Data collection is performed for points within the vertical line segment. The stepper motor 5 is controlled by the PLC controller to move above the measuring point. The distance data between the sensor and the needle 13 measuring point is collected by the laser displacement sensor 4 data collection software. The displacement data of the stepper motor 5 between each measuring point must be less than 1 mm. After the measurement is completed, the stepper motor 5 is continued to be moved to another measuring point for measurement until all points in the line segment are measured; S7: Change line segment measurement. Use the PLC controller to control the stepper motor 5 to move on the long side track of the staggered slide rail 7 to the next line segment parallel to the needle stroke, adjust the fixing bolt 9 to fine-tune the angle of the laser displacement sensor 4, repeat steps S2 to S6, and complete the data collection of all line segments. At the same time, record the displacement data of the stepper motor 5 controlled by the PLC controller to move on the staggered slide rail 7, so as to facilitate the measurement of the same point next time; S8: Use data processing software to count and display the collected distance data, calculate the data average, maximum, minimum and mean square error, and import the data into programming and drawing software such as MATLAB or Origin to obtain a three-dimensional morphology image of the nozzle surface.

[0031] S9: After the impulse turbine runs for a period of time, the operations of S1 to S8 are repeated to record and process the new distance data of each measuring point after the injection needle 13 is used, and compare the new distance data with the original distance data.

[0032] S10: The wear warning value is set to 100μm. When the monitored abrasion exceeds this threshold, the system automatically issues a warning signal to prompt maintenance personnel to check or replace the spray needle.

[0033] Finally, it should be noted that the above embodiments only describe the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0034] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A device for measuring the abrasion of a water turbine needle based on a laser displacement sensor, characterized in that: The invention comprises a nozzle needle (13) and a water distribution ring pipe. A fixing box (3) is fixedly installed below the water distribution ring pipe. A laser displacement sensor (4) is installed inside the fixing box (3). The laser displacement sensor (4) is installed opposite to the nozzle needle (13). The laser displacement sensor (4) is connected to an online monitoring system for the abrasion amount of the nozzle needle of the turbine.

2. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 1, characterized in that: The laser displacement sensor (4) comprises a beam emitting mirror (41), a beam receiving mirror (42), a semiconductor laser (43) and a beam receiving element (44), wherein the semiconductor laser (43) is used to emit laser light, the beam emitting mirror (41) is mounted at the output end of the semiconductor laser (43), the beam emitting mirror (41) and the beam receiving mirror (42) are used to collimate and focus the laser beam, the beam receiving mirror (42) is located inside the laser displacement sensor (4), the beam receiving element (44) is located at the output end of the beam receiving mirror (42), and the beam receiving element (44) is used to convert the received laser beam into an electrical signal.

3. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 1, characterized in that: A stepper motor (5) is arranged on the top of the fixed box (3), the stepper motor (5) is connected to an electric slider (8), the stepper motor (5) controls the electric slider (8) to slide on the staggered slide rail (7), and the staggered slide rail (7) is installed parallel to the top of the fixed box (3).

4. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 3 is characterized in that: The electric slider (8) is removable, and threads matching the fixing bolts (9) are provided inside the electric slider (8) and above the laser displacement sensor (4). The laser displacement sensor (4) is fixed to the staggered slide rail (7) via the fixing bolts (9) and the electric slider (8).

5. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 3 is characterized in that: Waterproof sand baffles (6) are provided at both ends of the fixed box (3), and the height of the water-proof sand baffles (6) can be adjusted.

6. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 3 is characterized in that: The bottom of the fixed box (3) is provided with an open hole structure (10) to ensure that the emission and reception of light beams by the laser displacement sensor (4) are not obstructed.

7. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 1, characterized in that: The deflector (11) comprises a deflector (11) which is located between a spray needle (13) and a rotating wheel. The deflector opening (12) is located at a portion where the top of the deflector (11) overlaps with a protruding portion of the spray needle (13). The measurement position of the laser displacement sensor (4) is the portion of the spray needle (13) exposed at the deflector opening (12).

8. The device for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 3 or 7, characterized in that: The water turbine needle abrasion amount online monitoring system includes a computer system, a PLC controller, and a motor power supplier; The laser displacement sensor (4) is used to collect displacement data of the spray needle (13); The computer system is used to process and display data collected by the laser displacement sensor (4); The PLC controller is used to control the stepping motor (5) to drive the electric slider (8) to move; The motor power supplier is used to supply power to the stepping motor (5).

9. The method for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claims 1 to 8, characterized in that: Stop the operation of the turbine, adjust the equipment to the initial state, start the turbine needle abrasion online monitoring system and calibrate the laser displacement sensor (4), accurately measure the surface of the impulse turbine needle (13) through the laser displacement sensor (4), collect and analyze the measurement data, compare the measurement data with the set abrasion warning value, and when the measurement data exceeds the warning value, the system automatically sends a warning signal to prompt maintenance personnel to check or replace the needle.

10. The method for measuring the abrasion of a water turbine needle based on a laser displacement sensor according to claim 9, characterized in that: The method for calibrating the laser displacement sensor (4) is: The stepper motor (5) is controlled by a PLC controller to operate the electric slide block (8) to the top of the spray needle (13), ensuring that the surface of the beam emitting mirror (41) and the beam receiving mirror (42) of the laser displacement sensor (4) are parallel to the surface of the spray needle (13), and the laser displacement sensor (4) is fixed on the staggered slide rail (7).

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