A non-contact on-machine shape tolerance measurement device and method for small-diameter deep holes with large aspect ratio

Abstract

A non-contact on-machine shape tolerance measurement device and method for small-diameter deep holes with a large aspect ratio, belonging to the technical field of geometric tolerance measurement of small-diameter deep hole parts. It includes a deep hole profile optical measurement unit, an optical-to-digital signal conversion unit and a shape tolerance measurement unit; the deep hole profile optical measurement unit includes a laser measurement feed assembly, a magnetic clamping unit and a laser line scanning device; the optical-to-digital signal conversion unit includes a power supply, a controller, and a data collector; the shape tolerance measurement unit is a signal processing system on the computer side, including a roundness fitting module, a straightness fitting module, and a cylindricity fitting module, which can realize high-quality point cloud data acquisition and shape tolerance calculation. The designed non-contact on-machine measurement feed assembly adopts the laser measurement principle, which greatly avoids contact damage to the surface quality of the deep hole. The present invention is suitable for the measurement of small-diameter deep holes with an inner diameter of 30mm-40mm, and is a completely non-contact measurement device with broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of geometric tolerance measurement of small-diameter deep hole parts, and specifically relates to a non-contact on-machine shape tolerance measurement device and method for small-diameter deep holes with a large aspect ratio, which is used to measure the roundness, straightness and cylindricity of small-diameter deep holes. Background Art

[0002] In the machinery manufacturing industry, inner holes with an aspect ratio greater than 10 are usually called large aspect ratio deep holes. Among them, small-diameter deep hole parts (inner hole diameter 30mm-40mm) have the advantages of light weight, less space occupation, good cooling and lubrication effects, etc., which meet the requirements of lightweight and high precision and are widely used in key technical fields. The shape tolerances such as roundness, straightness and cylindricity of small-diameter deep holes directly affect the assembly accuracy with other parts, and thus affect the performance and service life of the equipment. For example, in occasions where strict shaft-hole matching requirements are required, such as aircraft landing gear actuators, if the roundness deviation is too large, it may reduce the tightness of the shaft-hole matching and weaken the energy conversion efficiency. Therefore, after the small-diameter deep hole parts are manufactured and processed, their roundness, straightness and cylindricity errors must be precisely tested to ensure that the accuracy of the deep hole parts used meets the standards and improve the performance and service life of the equipment.

[0003] Due to the small inner diameter of the deep hole parts with large aspect ratio and small diameter, the space available for measuring shape tolerance in the hole is limited, and it is difficult to develop related measuring devices. Therefore, the shape tolerance measurement of deep holes with large aspect ratio and small diameter has always been a difficult point in the field of deep hole measurement technology. The shortcomings of the deep hole roundness, straightness and cylindricity error detection technologies commonly used in industry are mainly reflected in the following three aspects:

[0004] (1) The laser equipment used in the existing deep hole shape tolerance laser measurement device involves the comprehensive application of multiple types of optical measuring instruments. The rotation and feed motion system occupies a large space, has a complex structural design, and has poor measurement stability. It is only suitable for the inspection of large deep hole parts and cannot meet the high-precision measurement requirements of small-diameter deep hole parts with an inner diameter of 30mm-40mm.

[0005] (2) The probe length of existing contact measuring equipment such as three-dimensional coordinate measuring machines is short, the detectable hole depth is limited, and it is difficult for the measuring tool to contact the specific part of the bottom of the hole. At the same time, it is easily affected by human factors, the steps are cumbersome, and the measurement cycle is long. It is not easy to achieve efficient measurement of the shape tolerance of deep holes with large aspect ratios and small diameters. In addition, the contact between the measuring tool and the inner wall is easy to scratch the workpiece, which will inevitably damage the surface quality of the deep hole parts that have been processed.

[0006] (3) Most of the existing small-diameter deep hole shape tolerance measurement equipment belongs to offline measurement, which requires the workpiece to be removed from the production equipment and the coordinates of all spatial points in the hole to be calibrated. It cannot meet the needs of calculating the shape tolerance of the cross-sectional profile of the small-diameter deep hole part by fitting it on the machine, which seriously affects the measurement efficiency. In addition, the existing technology cannot provide online feedback of measurement results and timely adjust and control the processing process, which affects the processing quality of small-diameter deep holes.

[0007] In view of the above problems, the present invention has developed a non-contact on-machine measuring device for the roundness, straightness and cylindricity of small-diameter deep holes with a large aspect ratio. The device optimizes the design of the measuring tooling for the measurement requirements of an inner diameter of 30mm-40mm, reduces the size restrictions, and adapts to the laser measurement of the shape tolerance of small-diameter deep holes. Based on the non-contact laser displacement sensor, under the premise of completely not contacting the inner surface of the small-diameter deep hole part, the tool holder drives the magnetic clamping unit and the laser measurement feed assembly, and the measurement of the shape tolerance of the small-diameter deep hole part can be completed in one feed. This design reduces manual intervention, improves the measurement efficiency, and ensures that the surface quality of the processed inner hole is not damaged. After the small-diameter deep hole part is processed, it can be directly measured on the machine. It has the ability to simulate the contour change trend and fit the center of the cross section online, and can feedback the measurement results online, thereby realizing the subsequent compensation of the cutting parameters and the correction of the measurement results, thereby improving the processing quality of small-diameter deep holes. Summary of the invention

[0008] The present invention aims to solve the problems existing in the current measurement technology of roundness, straightness and cylindricity of small-diameter deep holes with large aspect ratio, such as the measuring device is easy to come into direct contact with the inner hole, cannot meet the measurement size requirements of small-diameter deep holes with inner diameters of 30mm-40mm, and the measurement technology or detection equipment is complicated. To this end, a non-contact on-machine shape tolerance measurement device and method for small-diameter deep holes with large aspect ratio are provided.

[0009] The technical solution of the present invention:

[0010] A non-contact on-machine shape tolerance measuring device for small-diameter deep holes with a large aspect ratio, suitable for measuring small-diameter deep holes with an inner diameter of 30mm-40mm; comprising a deep hole profile optical measuring unit, an optical-to-digital signal conversion unit and a shape tolerance measuring unit;

[0011] The deep hole profile optical measurement unit includes a laser measurement feed assembly 3, a magnetic clamping unit and a laser line scanning device;

[0012] The optical-to-digital signal conversion unit includes a power supply, a controller and a data collector; the controller is respectively connected to the laser displacement sensor 9, the computer end and the data collector, the laser displacement sensor 9 is connected to the data collector, and the data collector is connected to the computer end. The controller is used to control the position signal data obtained by the data collector from the laser displacement sensor 9 to be transmitted to the computer end after optical-to-digital conversion.

[0013] The shape tolerance measurement unit is a signal processing system on a computer, including a roundness fitting module, a straightness fitting module and a cylindricity fitting module, which are used to realize point cloud data acquisition and shape tolerance calculation.

[0014] The laser measurement feed assembly 3 includes a clamp body 10, a sensor positioning seat 6, a laser displacement sensor 9 and a reflective prism 7; the clamp body 10 has three grooves evenly distributed around the circumference for fixing the sensor positioning seat 6 and the reflective prism 7, and for routing the optical transmission cable; three laser displacement sensors 9 are fixed on the sensor positioning seat 6, and each laser displacement sensor 9 emits laser in a direction parallel to the axial direction of the clamp body 10; the reflective prism 7 faces the laser emission direction of the laser displacement sensor 9 and is at an angle of 45° to the axial direction of the clamp body 10. The laser displacement sensor 9 is used to measure the vertical distance D between the laser emission point and the inner surface of the small-diameter deep hole.

[0015] The magnetic clamping unit includes a magnetic clamp 4 and a tool holder 5 . One end of the magnetic clamp 4 is adsorbed on the tool holder 5 of the processing machine by magnetic force, and the other end of the magnetic clamp 4 is used to clamp the clamp body 10 of the laser measurement feed assembly 3 .

[0016] The laser line scanning device is used to measure the distance d from the laser emission point of the laser displacement sensor 9 to the center of the laser measurement feeding assembly 3.

[0017] A non-contact on-machine shape tolerance measurement method for a small-diameter deep hole with a large aspect ratio, the steps are as follows:

[0018] Before measurement, a laser line scanning device is used to measure the distance from the laser emission point of the laser displacement sensor 9 to the center of the laser measurement feed assembly 3;

[0019] Then, the three optical transmission cables of the laser displacement sensor 9 are respectively connected to the three interfaces of the data collector, and then the data collector is connected to the computer; the sampling frequency, sampling channel, and scale are set in the signal processing system of the computer to ensure the accurate online display of the measurement data; the small-diameter deep hole part 2 to be measured is clamped on the main shaft of the machine tool, and the laser measurement feed assembly 3 is clamped on the magnetic clamp 4, and the magnetic clamp 4 is adsorbed on the tool holder 5 of the machine tool. By continuously adjusting the position of the laser measurement feed assembly 3, ensure that its center coincides with the axis of the small-diameter deep hole to reduce the eccentricity error, and ensure that the laser measurement feed assembly 3 is completely non-contact with the inner wall of the small-diameter deep hole during feeding to avoid scratches during the measurement process.

[0020] During measurement, the machine tool is started, and the tool holder 5 drives the laser measurement feed assembly 3 to realize linear feeding along the axial direction of the small-diameter deep hole until it passes through the entire inner hole; during the measurement process, after the laser is reflected by the 45° reflective prism 7, the direction of the light is changed to propagate in the radial direction to the inner surface of the small-diameter deep hole, and the refracted light on the inner surface of the small-diameter deep hole returns to the laser displacement sensor 9 along the original path, and then the laser displacement sensor 9 measures the vertical distance D between the laser emission point and the inner surface of the small-diameter deep hole. During the measurement process, the change trend of the inner hole profile displayed on the computer should be observed in real time. If the value of the measured vertical distance D exceeds the range, it means that the centering adjustment before measurement is not in place, and the measurement should be stopped quickly, and the centering should be adjusted before measurement.

[0021] After measurement, the signal processing system is used to improve the quality of the position signal data based on the measured data. The circular contours of each section of the small-diameter deep hole are fitted based on the three-point circle method, and the center point cloud diagram is drawn; the roundness fitting module, straightness fitting module and cylindricity fitting module calculate the roundness, straightness and cylindricity values ​​of the small-diameter deep hole based on the minimum envelope algorithm and the least squares method.

[0022] Beneficial effects of the present invention:

[0023] (1) The designed deep hole profile optical measurement unit of the non-contact form tolerance on-machine measurement device for small-diameter deep holes with large aspect ratio adopts the laser measurement principle, which greatly avoids contact damage to the surface quality of small-diameter deep holes. The front end of the laser measurement feed component is evenly distributed with three slots for the integration of the deep hole profile optical measurement unit. It is light in weight, small in size, and easy to assemble. It is especially suitable for the form tolerance detection of small-diameter deep hole parts with an inner diameter of 30mm-40mm under harsh measurement conditions.

[0024] (2) Compared with the existing laser measurement equipment, the non-contact on-machine shape tolerance measurement device for small-diameter deep holes with a large aspect ratio has a simple structure, compact layout, and convenient measurement method. It can effectively reduce manual intervention. The machine tool tool holder drives the feed to complete the efficient measurement of deep hole roundness, straightness, and cylindricity at one time.

[0025] (3) The non-contact shape tolerance on-machine measuring device for small-diameter deep holes with large aspect ratio is strengthened and integrated with the computer. The measurement data of each cross-sectional profile of the small-diameter deep hole can be displayed and processed on-machine, and the machining error of the small-diameter deep hole can be subsequently compensated based on the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the measurement principle of the non-contact on-machine shape tolerance measuring device for small-diameter deep holes with large aspect ratio;

[0027] Figure 2 This is a schematic diagram of the installation and operation of the deep hole profile optical measurement unit;

[0028] Figure 3 This is the front end structure distribution diagram and left view of the laser measurement feed assembly;

[0029] Figure 4 This is the optical path diagram for measuring the contour circle of the laser measuring feed component;

[0030] Figure 5 It is the schematic diagram of the signal processing system of the shape tolerance measurement unit;

[0031] Figure 6 It is a flow chart of the fitting principles of the roundness fitting module, the straightness fitting module and the cylindricity fitting module.

[0032] Numbers in the figure: 1-three-jaw chuck, 2-small-diameter deep-hole parts to be measured, 3-laser measurement feed assembly, 4-magnetic clamp, 5-tool holder, 6-sensor positioning seat, 7-reflection prism, 8-bolt, 9-laser displacement sensor, 10-clamp body, 11-cable trough, 12-outgoing light, 13-incident light. DETAILED DESCRIPTION

[0033] The measurement principle flow chart of the non-contact on-machine shape tolerance measuring device for small-diameter deep holes with large aspect ratio provided by the present invention is as follows: Figure 1 As shown, the laser measurement principle is adopted, the small-diameter deep hole part 2 to be measured is driven to rotate by the machine tool spindle, the laser measurement feed component 3 is magnetically adsorbed on the tool holder 5 by the magnetic clamp 4 to realize linear feeding, and the laser displacement sensor 9 and the laser line scanning device are used to measure the distance D from the laser emission point to the inner surface of the small-diameter deep hole and the distance d from the center of the laser measurement feed component 3 to the laser emission point respectively; the optical signal conversion unit is used to complete the three-way optical signal reception, signal temporary storage and optical signal conversion processing; the signal processing system on the computer side can realize the high-quality extraction of position signal data, and the calculation of roundness, straightness and cylindricity is completed based on the fitting modules of the shape tolerance measurement unit.

[0034] exist Figure 2In the installation and working diagram of the deep hole profile optical measurement unit of the present invention, the small-diameter deep hole part 2 to be measured is clamped on the three-jaw chuck 1 and driven to rotate by the machine tool spindle. The laser measurement feed assembly 3 is adsorbed on the square tool holder 5 by the magnetic clamp 4, and can be driven by the tool holder 5 to achieve linear feeding. When in use, the laser measurement feed assembly 3 is fixed to the tool holder 5 by the magnetic clamp 4, and the optical transmission cable at the rear end is connected to the computer terminal through the data acquisition device. The small-diameter deep hole part 2 to be measured is clamped to the lathe spindle. At the same time, in order to avoid the tool holder 5 driving the laser measurement feed assembly 3 to feed and scratch the inside of the small-diameter deep hole, it is necessary to ensure that the center of the laser measurement feed assembly 3 is highly coincident with the axial direction of the small-diameter deep hole. After installation, turn on the laser displacement sensor 9, start the machine tool, and when measuring roundness, feed the laser measurement feed assembly 3 to the predetermined measurement section in advance and keep it stable. The machine tool spindle drives the small-diameter deep hole part 2 to be measured to rotate. At the same time, the computer uses the signal processing system to start collecting and storing position signal data. In this process, the roundness data of the remaining sections are measured. When measuring straightness, keep the machine tool spindle from rotating, and directly start the tool holder 5 to drive the laser measurement feed assembly 3 to feed straightly through the entire small-diameter deep hole to obtain the straightness data. When measuring cylindricity, keep the machine tool spindle rotating, and start the tool holder 5 to drive the laser measurement feed assembly 3 to feed straightly through the entire small-diameter deep hole. It should be further explained that the deep hole profile optical measurement unit uses a laser measurement feed assembly 3 to measure each section of the small-diameter deep hole, thereby obtaining optical signal data; in order to avoid introducing secondary clamping errors, the small-diameter deep hole part 2 to be measured is still clamped on the machine tool spindle after processing and is not removed; the laser measurement feed assembly 3 is clamped by a magnetic clamp 4 adsorbed on the tool holder 5, so that the laser measurement feed assembly 3 is driven by the tool holder 5 to achieve linear feeding in the small-diameter deep hole and complete the measurement of each section data of the small-diameter deep hole. The use of the magnetic clamp 4 can ensure that the laser measurement feed assembly 3 is accurately and stably centered while realizing the quick installation and disassembly of the non-contact shape tolerance on-machine measurement device of small-diameter deep holes with large aspect ratio, thereby improving the clamping efficiency.

[0035] Figure 3 The front end structure of the laser measurement feed assembly 3 is shown. From the left view, it can be seen that three laser displacement sensors 9 are evenly installed along the circumference. Three grooves are evenly processed at the front end of the clamp body 10, and through holes are opened in the grooves. Three sensor positioning seats 6 are fixed by bolts 8. Laser displacement sensors 9 are respectively installed in the three sensor positioning seats 6 and equipped with three reflective prisms 7. Three evenly distributed cable grooves 11 are processed in the middle. One end of the optical transmission cable is fixed in the cable groove 11 and connected to the laser displacement sensor 9, and the other end is connected to the light-to-signal conversion unit. The tailstock of the laser measurement feed assembly 3 is clamped by a magnetic clamp 4.

[0036] Figure 4In the measurement optical path diagram of the laser measurement feed assembly shown, the laser displacement sensor 9 emits an incident light 13 along the axial direction. After the laser is reflected by the 45° reflecting prism 7, the direction of the light is changed to propagate in the radial direction to the inner surface of the small-diameter deep hole. The outgoing light 12 from the inner surface of the small-diameter deep hole returns to the laser displacement sensor 9 along the original path, and then the laser displacement sensor 9 measures the vertical distance D between the laser emission point and the inner surface of the small-diameter deep hole; the laser measurement feed assembly 3 is adsorbed and fed by the magnetic clamp 4. During the moving measurement process, the three laser displacement sensors 9 can simultaneously obtain the optical signal data corresponding to the three points on each section of the small-diameter deep hole, and transmit them to the optical signal conversion unit by the optical transmission cable; the subsequent computer-side signal processing system uses the measured vertical distance D value based on the three-point circle determination algorithm, and draws the contour circle and center point cloud diagram of the small-diameter deep hole by fitting the coordinates of the three points on each section, and finally obtains the deep hole roundness, straightness and cylindricity based on the least squares method and the minimum envelope algorithm.

[0037] The optical signal conversion unit is used to receive optical signal data and convert it into position signal data, so as to obtain the vertical distance D value measured by the laser displacement sensor 9. Among them, the data collector includes three optical signal interfaces, which can respectively receive the ultra-high brightness light sources emitted by the three laser displacement sensors 9, and generate stable strong light in different bands. After the optical splitter inside the data collector is used for subsequent light splitting, the optical path measurement at different positions and directions is realized, and the signal temporary storage and optical conversion processing are completed; the specific process is: the three laser displacement sensors 9 are respectively connected to the three interfaces of the data collector through three optical transmission cables. During the measurement process, the optical signal data obtained by the laser displacement sensor 9 will be transmitted to the data collector through the optical transmission cable for temporary storage and optical conversion processing. The power supply is a dedicated 24V DC power supply, which provides power for the entire optical signal conversion unit. The controller is connected to the computer end, the laser displacement sensor 9, and the data collector at the same time, and controls the transmission of the position signal data obtained by the data collector to the computer end. The laser transmitter of the laser displacement sensor 9 emits a visible green laser to the inner hole surface through the reflective prism 7 lens, and the reflected laser is received by the photoelectric receiver of the laser displacement sensor 9 itself. The photoelectric receiver can observe the laser reflective light spot at different angles, and calculate the distance between the laser emission point of the laser displacement sensor 9 and the inner surface of the measured small-diameter deep hole according to the light spot angle, and output the vertical distance D signal data proportionally on the computer end.

[0038] like Figure 5The signal preprocessing system can display the changing trend of the inner hole profile during the measurement process based on the displacement measurement value, and can store and preliminarily analyze the measurement values ​​of multiple moving processes at the same time; perform spectrum analysis based on the original time domain signal obtained to distinguish the frequency bands corresponding to the real signal and the noise signal; test the normality of the digital signal based on the QQ graph and use the 3sigma detection method to query the signal abnormal value, use the moving smoothing substitution method to replace the abnormal value with the measured average value of its adjacent position, and extract the real value corresponding to the required frequency band through six-layer wavelet packet decomposition, so as to obtain high-quality measurement data;

[0039] Figure 6 It is a flow chart of the fitting principle of the roundness fitting module, the straightness fitting module and the cylindricity fitting module. When fitting the roundness, the roundness fitting module is based on the minimum concentric circle radius difference roundness measurement principle, and uses the measurement data to calibrate the distance from the center of the laser measurement feed component 3 to the measuring point on the inner surface of the small-diameter deep hole. The difference between the maximum and minimum distances in a measurement cycle is the section roundness; when fitting the straightness, the straightness fitting module is based on the minimum cylindrical envelope principle, and uses three laser displacement sensors 9 to calibrate the coordinates of three points on a certain section. Based on the three-point circle determination algorithm, the coordinates of the center of each section are obtained and the center point cloud diagram is drawn. Then, the minimum envelope algorithm and the least squares method are used. The minimum cylindrical diameter that completely envelops all the center of the section is the deep hole straightness; when fitting the cylindricity, the cylindricity fitting module can calibrate the distance from each measuring point on the inner surface of the small-diameter deep hole to the center of the laser measurement feed component 3 based on the measurement data, and then fit the ideal center axis. The difference between the maximum and minimum distances from each measuring point to the axis is the deep hole cylindricity.

Claims

1. A non-contact on-machine shape tolerance measurement method for small-diameter deep holes with large aspect ratio, characterized in that: Under the premise of not contacting the inner surface of the small-diameter deep hole part at all, the tool holder (5) drives the magnetic clamping unit and the laser measurement feed assembly (3), and the measurement of the shape tolerance of the small-diameter deep hole part can be completed by one feeding. The steps of the non-contact shape tolerance on-machine measurement method of a small-diameter deep hole with a large aspect ratio are as follows: Before measurement, the small-diameter deep-hole part (2) to be measured is still clamped on the main spindle of the machine tool after processing and is not removed, and a laser line scanning device is used to measure the distance from the laser emission point of the laser displacement sensor (9) to the center of the laser measurement feed assembly (3); Then, the three optical transmission cables of the laser displacement sensor (9) are respectively connected to the three interfaces of the data collector, and then the data collector is connected to the computer; the sampling frequency, sampling channel, and scale are set in the signal processing system of the computer to ensure accurate online display of the measurement data; the small-diameter deep hole part (2) to be measured is clamped on the main shaft of the machine tool, and the laser measurement feed component (3) is clamped on the magnetic clamp (4), and the magnetic clamp (4) is adsorbed on the tool holder (5) of the machine tool. By continuously adjusting the position of the laser measurement feed component (3), it is ensured that its center and the axis of the small-diameter deep hole are kept coincident, thereby reducing the eccentricity error, and ensuring that the laser measurement feed component (3) is completely non-contact with the inner wall of the small-diameter deep hole during feeding, thereby avoiding scratches during the measurement process; During measurement, the machine tool is started, and the tool holder (5) drives the laser measurement feed assembly (3) to realize linear feed along the axial direction of the small-diameter deep hole until it passes through the entire inner hole. During the measurement process, after the laser is reflected by the 45° reflection prism (7), the direction of the light is changed to propagate in the radial direction to the inner surface of the small-diameter deep hole. The refracted light on the inner surface of the small-diameter deep hole returns to the laser displacement sensor (9) along the original path, and then the laser displacement sensor (9) measures the vertical distance D between the laser emission point and the inner surface of the small-diameter deep hole. During the measurement process, the change trend of the inner hole profile displayed on the computer terminal should be observed in real time. If the value of the measured vertical distance D exceeds the range, it means that the centering adjustment before measurement is not in place, and the measurement should be stopped immediately, and the centering should be adjusted before measurement. After measurement, the signal processing system is used to improve the quality of the position signal data based on the measured data. The circular contours of each cross section of the small-diameter deep hole are fitted based on the three-point circle method, and the center point cloud diagram is drawn; the roundness fitting module, straightness fitting module and cylindricity fitting module calculate the roundness, straightness and cylindricity values ​​of the small-diameter deep hole based on the minimum envelope algorithm and the least squares method; When fitting the straightness, the straightness fitting module is based on the minimum cylindrical envelope principle. Three laser displacement sensors (9) are used to calibrate the coordinates of three points on a certain section. The coordinates of the center of each section are obtained based on the three-point circle determination algorithm and a center point cloud diagram is drawn. Then, the minimum envelope algorithm and the least squares method are used. The minimum cylindrical diameter that completely envelops the center of all sections is the deep hole straightness.

2. A non-contact on-machine shape tolerance measurement device for a large aspect ratio and small diameter deep hole, used in a non-contact on-machine shape tolerance measurement method for a large aspect ratio and small diameter deep hole according to claim 1, characterized in that: Suitable for measuring small-diameter deep holes with an inner diameter of 30mm-40mm; including deep hole profile optical measurement unit, optical signal conversion unit and shape tolerance measurement unit; The deep hole profile optical measurement unit comprises a laser measurement feed assembly (3), a magnetic clamping unit and a laser line scanning device; The optical-to-digital signal conversion unit comprises a power supply, a controller and a data collector; the controller is respectively connected to the laser displacement sensor (9), the computer terminal and the data collector, the laser displacement sensor (9) is connected to the data collector, and the data collector is connected to the computer terminal, and the controller is used to control the position signal data obtained by the data collector from the laser displacement sensor (9) to be transmitted to the computer terminal after optical-to-digital conversion processing; The shape tolerance measurement unit is a signal processing system on the computer side, including a roundness fitting module, a straightness fitting module and a cylindricity fitting module, which are used to realize point cloud data acquisition and shape tolerance calculation; The laser measurement feed assembly (3) comprises a clamp body (10), a sensor positioning seat (6), a laser displacement sensor (9) and a reflective prism (7); the clamp body (10) is evenly distributed with three grooves in the circumferential direction for fixing the sensor positioning seat (6) and the reflective prism (7), and for routing optical transmission cables; three laser displacement sensors (9) are fixed on the sensor positioning seat (6), and each laser displacement sensor (9) emits laser light in a direction parallel to the axial direction of the clamp body (10); the reflective prism (7) faces the laser emission direction of the laser displacement sensor (9) and forms an angle of 45° with the axial direction of the clamp body (10); the laser displacement sensor (9) is used to measure the vertical distance D between the laser emission point and the inner surface of the small-diameter deep hole; The magnetic clamping unit comprises a magnetic clamp (4) and a tool holder (5); one end of the magnetic clamp (4) is adsorbed on the tool holder (5) of the processing machine tool by magnetic force, and the other end of the magnetic clamp (4) is used to clamp a clamp body (10) of the laser measurement feed assembly (3); The laser line scanning device is used to measure the distance d from the laser emission point of the laser displacement sensor (9) to the center of the laser measurement feed component (3).

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