Automatic chamfering method for side wall hole of large-depth-diameter-ratio pipe fitting

Abstract

The invention discloses an automatic chamfering machining method for a side wall hole of a large-depth-diameter-ratio pipe fitting. The automatic chamfering machining method comprises the following steps that axial positioning is conducted; radial positioning; selecting a processing scheme; machining a chamfer; and evaluating the chamfering quality of the side wall hole. According to the large-depth-diameter-ratio pipe fitting side wall hole measurement and machining reevaluation integrated method, the size coordinates of the pipe fitting side wall hole are recorded through the laser displacement sensor, data are processed through a signal filtering and abnormal point detection method, a proper chamfering machining track is selected according to the hole diameter, and the machining precision of the pipe fitting side wall hole is improved. And on the basis of the simulation track, through multi-axis linkage cooperation, precise machining of the hole edges is conducted, finally, the requirement is met through calculation and judgment of the relevant chamfering size, and size evaluation and quality control of the chamfering are achieved. Automatic measurement, machining and reevaluation are combined, and the side wall hole chamfering machining precision and efficiency are improved. The method comprehensively evaluates the quality of the edge and the chamfer of the hole, and solves the problem that the quality of the edge and the chamfer of the machined hole cannot be observed and evaluated.

Description

Technical Field

[0001] The present invention relates to a method for chamfering the side wall holes of pipe fittings, and more particularly to an automatic chamfering method for the side wall holes of pipe fittings with a large depth-to-diameter ratio. Background Art

[0002] Due to their excellent inner surface quality, outstanding high-temperature resistance and mechanical properties, and relatively large length dimensions, pipe fittings with a large depth-to-diameter ratio are commonly used in core areas such as engines and landing gears, and their main functions include force transmission and gas transportation. However, during operation, the side wall holes are prone to accumulating dirt due to their low surface quality, which seriously affects the working reliability of the pipe fittings and the safety of operators. Currently, the chamfering of the side wall holes of pipe fittings with a large depth-to-diameter ratio is mainly carried out manually by mechanical means, that is, a scraper is fixed at the top of a long rod for removal operations. However, this method has certain limitations during the chamfering of the side wall holes of pipe fittings with a large depth-to-diameter ratio. Chinese Patent CN201510944085.3 designed a tool for drilling through holes, and adopted a method of drilling with a stepped drill and a guide sleeve in cooperation to achieve deep hole chamfering and improve the surface quality; Chinese Patent CN201911389229.8 proposed a laser removal processing method for intersecting deep holes, and processed the hole edge through the thermal coupling effect formed by a high-temperature spherical block and a laser shock wave, but this method is prone to damaging the surface of the workpiece. Scholars from Konkuk University in South Korea designed a new structure for a hole deburring tool. The tool body and the tool tip are manufactured separately, and a spring is added inside the tool tip to avoid the generation of drilling burrs, but the surface quality of the hole after processing is poor. A certain domestic aerospace machinery company adopted an electrolytic processing method to remove the material of the metal hole edge to solve the problem of difficult deburring of the micro deep holes of aerospace valve cores; a certain aviation hydraulic machinery company adopted an abrasive flow machining technology, and removed the material of the inner wall hole edge of the pipe fitting by extruding the abrasive flow inside the pipe fitting through a hydraulic system; scholars from Shandong University adopted an abrasive water jet method to remove the material of the deep hole and the intersecting hole edge, and improved the quality of the hole edge by controlling the jet pressure, erosion time, abrasive flow rate, etc. However, the above methods are not applicable to the removal of the hole edge material in pipe fittings with a large depth-to-diameter ratio and cannot form a chamfer. Beijing University of Posts and Telecommunications developed a robotic system for intersecting deep hole grinding, including a grinding head, a linear motion module, a clamping and power module, a rotation module and a base. The entire system is fixed on the base, and the grinding head is inserted into the pipe fitting through a flexible shaft for hole edge grinding, but this system cannot accurately locate the hole position and the material removal amount is small. Therefore, there is an urgent need for a new method that is applicable to the automatic chamfering of the side wall holes of pipe fittings with a large depth-to-diameter ratio and has high precision and high efficiency. Summary of the Invention

[0003] Aiming at the problems of low machining accuracy, low efficiency and difficult machining of the chamfers at the edges of the holes in the inner cavity of deep-hole pipe fittings, the present invention proposes an automatic machining method for chamfering the side-wall holes of pipe fittings with a large depth-to-diameter ratio, which has the advantages of high automation, high machining accuracy and high machining efficiency for chamfering the side-wall holes of pipe fittings with a large depth-to-diameter ratio.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] An automatic machining method for chamfering the side-wall holes of pipe fittings with a large depth-to-diameter ratio is carried out by using an automatic machining device for chamfering the side-wall holes of pipe fittings with a large depth-to-diameter ratio. The automatic machining device for chamfering the side-wall holes of pipe fittings with a large depth-to-diameter ratio is hereinafter referred to as the device, and the pipe fittings with a large depth-to-diameter ratio are hereinafter referred to as pipe fittings. The device includes a walking unit, a machining unit, a positioning unit, a tensioning mechanism, a driving wheel, a driven wheel, a linear module, a indexing motor and a driving motor; the machining unit is an X-feed unit, and the positioning unit is a C-indexing unit;

[0006] Let the longitudinal central axis of the device be the Y-axis, and the direction towards the machining unit be the positive direction of the Y-axis; the straight line perpendicular to the Y-axis and located in the horizontal plane is the Z-axis, and the direction towards the front is the positive direction of the Z-axis; the straight line perpendicular to the Y-axis and located in the vertical plane is the X-axis, and the direction towards the lower side is the positive direction of the X-axis; the rotation axis of the indexing plate in the device is the C-axis, and the clockwise rotation of the C-axis is the positive direction.

[0007] The method includes the following steps:

[0008] A. Axial positioning

[0009] On the side wall of the pipe fitting, multiple circles of side-wall holes are distributed along the axial direction of the pipe fitting. Each circle of side-wall holes is evenly distributed along the circumferential direction of the pipe fitting. Let the total number of side-wall holes be N, and i be used to represent the serial number of the side-wall holes. First, a positioning pin is inserted into one of the side-wall holes in the first circle of side-wall holes on the upper side of the pipe fitting, and then two tensioning mechanisms are manually adjusted so that the driving wheel and the driven wheel extend a certain distance along the positive direction of the X-axis. When the distance from the upper end point of the upper driving wheel to the lower end point of the lower driving wheel is greater than the inner diameter of the pipe fitting, stop adjusting the tensioning mechanism. Then, manually compress the driving wheel and the driven wheel so that the springs in the connected tensioning mechanisms are compressed, and the driving wheel and the driven wheel retract, so that the device can smoothly enter the pipe fitting. After releasing the manually applied pressures on the driven wheel and the driving wheel respectively, the springs in the tensioning mechanisms rebound, and the driven wheel and the driving wheel respectively return to the extended state and contact the inner wall of the pipe fitting, so as to support and position in the pipe fitting. Then, the device is powered on through the socket, and the linear module, the X-feed unit and the C-indexing unit are controlled to reset. The driving motor is controlled to rotate forward, so that the device feeds along the positive direction of the Y-axis in the pipe fitting until the inner end of the positioning pin contacts the stepped surface on the right side of the head cover, and the driving motor stops. The device stops walking along the positive direction of the Y-axis.

[0010] B. Radial positioning

[0011] Control the indexing motor to rotate forward 180°. Through the cooperation of the linear module and the C indexing unit, the laser emitted by the laser displacement sensor travels along an S-shaped reciprocating trajectory on the inner wall of the pipe fitting, and signal filtering and detection and removal of abnormal points are carried out. Record the coordinates of the maximum position points at both ends of the circumferential side wall holes of the pipe fitting, and record the coordinates of the left end point, right end point, front end point and back end point of the side wall hole. After controlling the indexing motor to reverse 180° back to the origin, then control the indexing motor to reverse 180°, and record the coordinates of the left end point, right end point, front end point and back end point of the circumferential side wall hole of the pipe fitting. The left end point of the side wall hole is the starting point of the Y-direction feeding and machining of the side wall hole.

[0012] C. Select the machining plan

[0013] After the measurement is completed, obtain the coordinates x i 、y i 、z i of the front end point of the side wall hole and the coordinates x i+1 、y i+1 、z i+1 of the back end point. According to the Euclidean distance formula in three-dimensional space, calculate the distance value L between the two end points. The formula is as follows:

[0014]

[0015] And judge the size relationship between the distance value L and the diameter D of the spherical grinding rod. When the distance value L is less than the diameter D, select the chamfering machining trajectory of Plan 1 for the side wall hole machining, and go to Step C1; when the distance value L is greater than the diameter D, select the chamfering machining trajectory of Plan 2 for the side wall hole machining, and go to Step C2.

[0016] C1. Execute Plan 1

[0017] By controlling the X feeding unit, make the spherical grinding rod descend along the positive X-axis direction, make the top of the grinding rod contact the left end point of the side wall hole, and reach the target grinding depth of the grinding rod. While the spindle motor drives the grinding rod to rotate, control the grinding unit to feed along the negative Y-axis direction through the linear module. After reaching the right end point of the side wall hole, control the X feeding unit to make the spherical grinding rod rise along the negative X-axis direction, and control the grinding rod to stop rotating and the linear movement of the X feeding unit. Go to Step D.

[0018] C2. Execute Plan 2

[0019] After collecting the side wall holes to be processed through an endoscope and obtaining the side wall hole profiles, the machining program of the grinding rod is obtained through simulation software. Then, the X feed unit is controlled to make the spherical grinding rod descend along the positive X-axis direction, so that the top end of the grinding rod contacts the left end point of the side wall hole. After obtaining the tool setting point, according to the machining program, the target grinding depth of the grinding rod is reached through the X feed unit. While the spindle motor drives the grinding rod to rotate, it cooperates with the linear module and the C indexing unit to complete the machining of the side wall hole chamfer. After the machining is completed, the spherical grinding rod is controlled to rise along the negative X-axis direction, and then the rotation of the grinding rod and the linear motion of the X feed unit are stopped. Go to step D.

[0020] D. Chamfer machining

[0021] According to the selected execution plan 1 or execution plan 2, the spherical grinding rod moves out of the corresponding trajectory under the combined action of the linear module and the C indexing unit, and the grinding depth of the spherical grinding rod is controlled by controlling the displacement of the X feed unit. After the spherical grinding rod rotates forward and processes once, it rotates backward and processes once. The machining times of the grinding rod are judged. When the set number threshold is met, the grinding rod stops machining, and the X feed unit, the linear module and the C indexing unit stop moving, and the reset of the three units is completed.

[0022] E. Evaluate the quality of the side wall hole chamfer

[0023] E1. Calculate the elliptical dimensions of the side wall hole

[0024] Take pictures of the surface topography of the side wall hole after machining through an endoscope, identify the side wall hole profile through image processing technology and obtain the complete side wall hole profile after machining. Then, use the ellipse fitting method to obtain the elliptical characteristics of the side wall hole. The ellipse formula is:

[0025] Ax 2 +Bxy+Cy 2 +Dx+Ey+F = 0

[0026] Among them, A, B, C, D, E, and F are the parameters of the ellipse equation. Assuming the ellipse rotation angle is α, then:

[0027] A = b 2 cos 2 α+a 2 sin 2 α

[0028] B = 2(b 2 -a 2 )cosαsinα

[0029] C = b 2 sin 2 α+a 2 cos 2 α

[0030] D = -2b 2 x a cosα - 2a 2 y a sinα

[0031] E = 2b 2 x a sinα - 2a 2 y a cosα

[0032] F = b 2 x a +a 2 y a 2 -a 2 b 2

[0033] Wherein, x a and y a are the coordinates of the center of the ellipse on the X-axis and Y-axis respectively. Therefore, the relational expressions of the ellipse parameters, the ellipse rotation angle α, and the coordinate values x a and y a , the major axis a and the minor axis b are calculated as follows:

[0034]

[0035] After obtaining the ellipse equation, the function f(A, B, C, D, E, F) is obtained as follows:

[0036]

[0037] Solve the extreme values of the parameter values through the following system of equations, and substitute the obtained extreme points into the second-order partial derivative equation to determine whether it is a minimum value:

[0038]

[0039] Through the above system of equations, the specific values of the six parameters A, B, C, D, E, and F are solved; furthermore, the major axis a and the minor axis b of the ellipse are solved, and then compared with the dimensions of the major axis and minor axis of the target ellipse to determine whether the dimension error meets the requirements.

[0040] E2. Calculate the fillet size of the chamfer of the side wall hole

[0041] The processed side wall hole point cloud data collected by the laser displacement sensor is filtered to obtain smooth and continuous point cloud data. According to the target chamfer value, the point cloud data of the side wall hole edge is retained. At this time, it is observed that there are obvious slope changes in the remaining side wall hole edge point cloud, and inflection points start to appear from the side wall hole edge until the middle mutation fracture position, where the inflection points reach the maximum value. The inflection points are identified by calculating the second derivative of the function, and it is judged whether the second derivative is 0. When the second derivative is not 0, it is an inflection point; when it is 0, it is a straight line segment. For continuous two-dimensional point cloud data, the central difference method of the finite difference method is used to calculate the first and second derivatives, and the formulas are as follows:

[0042] First derivative:

[0043]

[0044] Second derivative:

[0045]

[0046] where x i represents the data points of the two-dimensional point cloud, and f(x i ) represents the function value at this point.

[0047] The position of the side wall hole edge is obtained at the maximum value of the second derivative. Then, combined with the target chamfer R value, the retention range of the side wall hole edge point cloud data is set, and the least squares method is used to perform circular fitting on the point cloud in the retained side wall hole edge area. The circular fitting formula is:

[0048] (x - c) 2 +(y - d) 2 =R 2

[0049] where the coordinate of the center of the circle on the X-axis is c, and the coordinate on the Y-axis is d. The radius R of the chamfer of the side wall hole edge is obtained. For the multiple fitted circles obtained from the side wall hole edge, the average radius of the rounded corners is taken as r. Furthermore, by comparing the rounded corner size of the side wall hole edge with the target rounded corner size, it is judged whether the rounded corner size of the chamfer meets the requirements.

[0050] E3. Calculate the inclination angle size and chamfer width of the side wall hole chamfer

[0051] After taking the Z-direction cross-section of the point cloud data obtained by filtering the laser displacement sensor, and taking the Z-direction cross-section of the point cloud area on the chamfer after taking the approximate horizontal area of the inner wall horizontal point cloud area of the pipe fitting, that is, the area near the edge of the hole. The data points of the straight lines measured in these two areas under this cross-section are obtained. The data in the plane is a binary function. At this time, the least squares method is used to fit the data points to obtain the angle J between the fitted straight line and the horizontal axis and the intercept. Calculate all the fitted straight lines to obtain the average angle J 1 of the plane and the horizontal axis, and the average angle J of the chamfer and the horizontal axis2 , at this time, the inclination angle dimension β = |J 2 - J 1 |, and the maximum intercept is the chamfer width.

[0052] Furthermore, the method for identifying the side wall hole profile in step E1 includes gray clustering segmentation and binarization methods, boundary extraction method or threshold segmentation method.

[0053] Furthermore, the filtering method in step E2 includes Kalman filtering method, radius outlier filtering method or statistical filtering method.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] 1. The present invention proposes an integrated method for measuring and re - evaluating the side wall holes of large depth - to - diameter ratio pipe fittings. The size coordinates of the side wall holes of the pipe fittings are recorded by a laser displacement sensor, and the data is processed by signal filtering and outlier detection methods. The appropriate chamfering processing trajectory is selected according to the hole diameter, and the precise machining of the hole edge is carried out through multi - axis linkage cooperation based on the simulation trajectory. Finally, it is judged whether the requirements are met through the calculation of relevant chamfer dimensions, realizing the size evaluation and quality control of the chamfer. This method combines automatic measurement, processing and re - evaluation, improving the precision and efficiency of the chamfer processing of the side wall holes.

[0056] 2. The present invention proposes a method for evaluating the chamfer quality of the side wall holes of large depth - to - diameter ratio pipe fittings. First, the surface image of the side wall holes after processing is taken by an endoscope, and the complete side wall hole profile, that is, the elliptical feature, is obtained by using image processing technology. Secondly, the point cloud data after processing is collected by a laser displacement sensor, and after being processed by methods such as filtering, smooth point cloud data is obtained. The inflection points are identified through algorithms and fitted to obtain the fillet size. Finally, a straight line with a certain slope is obtained by fitting the point cloud data in the cross - section, and the inclination angle dimension and chamfer width of the side wall hole chamfer are calculated, thus comprehensively evaluating the quality of the hole edge and the chamfer, and solving the problem that the quality of the hole edge chamfer after processing cannot be observed and evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a schematic structural diagram (axonometric drawing) of the device of the present invention;

[0058] Figure 2 is a schematic diagram of the device of the present invention located inside the pipe fitting (non - working state);

[0059] Figure 3 is a schematic diagram of the device of the present invention located inside the pipe fitting (working state);

[0060] Figure 4 is a schematic flow diagram of the present invention;

[0061] Figure 5It is a working schematic diagram of the tensioning mechanism for small-diameter pipe fittings;

[0062] Figure 6 It is a working schematic diagram of the tensioning mechanism for large-diameter pipe fittings;

[0063] Figure 7 It is a schematic diagram of the circumferential hole positioning of the pipe fitting;

[0064] Figure 8 It is a schematic diagram of the first chamfering machining trajectory plan;

[0065] Figure 9 It is a schematic diagram of the second chamfering machining trajectory plan;

[0066] Figure 10 It is a schematic diagram of the elliptical geometry in the two-dimensional plane;

[0067] Figure 11 It is a schematic diagram of the fitting straight line of a certain Z-value cross-section in the horizontal area;

[0068] Figure 12 It is a schematic diagram of the fitting straight line of a certain Z-value cross-section in the chamfering area.

[0069] In the figure: 1. Pipe fitting, 2. Spindle motor, 3. Endoscope, 4. Laser displacement sensor, 5. Indexing motor, 6. Tensioning mechanism, 7. Pulling ring, 8. Plug, 9. Driving wheel, 10. Linear module, 11. Driven wheel, 12. C indexing unit, 13. X feed unit, 14. Ball-shaped grinding rod, 15. Side wall hole, 16. Positioning pin, 17. Head cover, 18. Driving motor. Specific implementation mode

[0070] The present invention will be further described below with reference to the accompanying drawings.

[0071] As Figures 1-3 shown, a device for automatically chamfering the side wall holes of large deep-diameter ratio pipe fittings includes a fuselage main body, a walking unit, a machining unit, and a positioning unit. The fuselage main body includes an upper shell, a lower shell, a connecting strip, a plug 8, and a pulling ring 7. The upper shell and the lower shell are respectively straddled on the upper side and the lower side of the connecting strip. The walking unit includes a driving motor 18, a pressing plate, a tensioning mechanism 6, a swinging bracket, a driving wheel 9, and a driven wheel 11. There are two pairs of driving wheels 9 and driven wheels 11, which are distributed on the front and rear sides of the upper shell and the lower shell. The machining unit includes a spindle motor 2, a ball-shaped grinding rod 14, an endoscope 3, a dividing plate, an indexing motor 5, a linear module 10, and an electric push rod. The machining unit is fixed to the lower shell through the dividing plate and the linear module 10. The positioning unit includes a positioning pin 16, a head cover 17, and a laser displacement sensor 4.

[0072] As Figures 1-12 shown, a method for automatically chamfering the side wall holes of large deep-diameter ratio pipe fittings includes the following steps:

[0073] A. Insert a positioning pin 16 into one of the side wall holes 15 in the first circle of side wall holes 15 on the upper side of the pipe fitting. Adjust the protruding distance between the driving wheel 9 and the driven wheel 11 through the tensioning mechanism 6. Then, manually apply force to the driving wheel 9 and the driven wheel 11, so that the connected spring is compressed. Place the device into the pipe fitting 1 until the driving wheel 9 completely enters the pipe fitting 1, and the driving wheel 9 and the driven wheel 11 are in close contact with the inner wall of the pipe fitting 1.

[0074] B. Connect the power supply of the device through the plug 8, and after pressing the power-on button, control the C indexing unit 12, the X feed unit 13 and the linear module 10 to reset.

[0075] C. Control the driving motor 18 to rotate forward, so that the device feeds along the negative Y-axis direction in the pipe fitting 1 until the inner end of the positioning pin 16 contacts the stepped surface on the right side of the head cover 17, and the driving motor 18 stops, and the device walking ends.

[0076] D. Control the indexing motor 5 to rotate forward / backward by 180°, and combine the linear module 10 and the indexing unit to determine the endpoints of the major axis and minor axis of the side wall hole 15.

[0077] F. Judge the absolute value of the circumferential dimension of the side wall hole 15 and the diameter of the grinding rod. When the absolute value is less than the diameter, the chamfering processing trajectory of Option 1 is selected for the processing of the side wall hole 15; when the absolute value is greater than the diameter, the chamfering processing trajectory of Option 2 is selected for the processing of the side wall hole 15. For pipe fittings 1 made of the same material and having the same type of side wall holes 15, single-factor experiments or orthogonal experiments on the rotational speed of the grinding rod, the diameter D of the grinding rod, the particle size of the grinding rod abrasive, the X feed speed, the feed speed of the linear module 10 and the processing time, etc. can be carried out to obtain the influence degree of the main factors and the optimal parameter combination.

[0078] G. After the processing is completed, control the main shaft motor 2 to stop the self-rotation of the grinding rod and reset it with the X feed unit 13.

[0079] H. Open the endoscope 3, take a surface image of the processed side wall hole 15, and execute the edge contour recognition program of the side wall hole 15.

[0080] H. Based on the point cloud data collected by the laser displacement sensor 4, execute the edge chamfer contour recognition program of the side wall hole 15.

[0081] I. After completing the quality evaluation of the edge chamfer of the side wall hole 15, control the linear module 10 and the C indexing unit 12 to reset.

[0082] J. Control the driving motor 18 to rotate backward, and the device walks until the pull ring 7 is exposed.

[0083] K. Pull out the power plug 8 of the device.

[0084] L. Remove the device from the pipe fitting 1 by pulling the pull ring 7.

[0085] The up, down, left, right, front and rear directions in the present invention are only relative to Figure 1 , and do not constitute any limitation to the present invention.

[0086] The present invention is not limited to this embodiment, and any equivalent conceptions or changes within the technical scope disclosed by the present invention are included in the protection scope of the present invention.

Claims

1. A method for automatically processing chamfering of a side wall hole of a pipe fitting with a large depth-to-diameter ratio, using an automatic processing device for chamfering of a side wall hole of a pipe fitting with a large depth-to-diameter ratio for processing, the automatic processing device for chamfering of a side wall hole of a pipe fitting with a large depth-to-diameter ratio hereinafter referred to as the device, the pipe fitting with a large depth-to-diameter ratio hereinafter referred to as the pipe fitting (1), the device comprising a walking unit, a processing unit, a positioning unit, a tensioning mechanism (6), a driving wheel (9), a driven wheel (11), a linear module (10), a dividing motor (5) and a driving motor (18); the processing unit is an X feeding unit (13), and the positioning unit is a C dividing unit (12); The longitudinal center axis of the device is assumed to be the Y axis, and the direction toward the processing unit is the positive direction of the Y axis; the straight line perpendicular to the Y axis and located in the horizontal plane is the Z axis, and the direction toward the front is the positive direction of the Z axis; the straight line perpendicular to the Y axis and located in the vertical plane is the X axis, and the direction toward the bottom is the positive direction of the X axis; the rotation axis of the indexing plate in the device is the C axis, and the clockwise rotation of the C axis is the positive direction; Features: The method comprises the following steps: A. Axial positioning On the side wall of the pipe (1), a plurality of circles of side wall holes (15) are distributed along the axial direction of the pipe (1), and each circle of side wall holes (15) is evenly distributed along the circumference of the pipe (1). The total number of the side wall holes (15) is assumed to be N, and i is used to represent the serial number of the side wall holes (15); firstly, a positioning pin (16) is inserted into a side wall hole (15) of the first circle of side wall holes (15) on the upper side of the pipe (1), and then the two tensioning mechanisms (6) are manually adjusted so that the driving wheel (9) and the driven wheel (11) extend a certain distance along the positive direction of the X axis, so that the distance from the upper end point of the upper driving wheel (9) to the lower end point of the lower driving wheel (9) is greater than the inner diameter of the pipe (1), and then the tensioning mechanism (6) connected to the driving wheel (9) is stopped. Then, the driving wheel (9) and the driven wheel (11) are manually compressed to make the tensioning mechanism (11) connected to the driving wheel (9) extend a certain distance along the positive direction of the X axis. The spring in the tensioning mechanism (6) is compressed, and the driving wheel (9) and the driven wheel (11) are retracted, so that the device can smoothly enter the pipe (1); after the pressure manually applied by the driven wheel (11) and the driving wheel (9) is released respectively, the spring in the tensioning mechanism (6) rebounds, and the driven wheel (11) and the driving wheel (9) respectively resume the extended state and contact the inner wall of the pipe (1), thereby supporting and positioning the device in the pipe (1); then the device is powered on through the socket, the linear module (10), the X feeding unit (13) and the C indexing unit (12) are controlled to reset, and the driving motor (18) is controlled to rotate forward, so that the device feeds in the pipe (1) along the positive direction of the Y axis until the inner end of the positioning pin (16) contacts the right step surface of the head cover (17), the driving motor (18) stops, and the device ends its movement along the positive direction of the Y axis; B. Radial positioning The indexing motor (5) is controlled to rotate forward 180°, and the linear module (10) cooperates with the C indexing unit (12) to make the laser emitted by the laser displacement sensor (4) follow an S-shaped reciprocating trajectory on the inner wall of the pipe (1), and signal filtering and abnormal point detection and removal are performed to record the coordinates of the maximum position points of the two ends of the circumferential side wall hole (15) of the pipe (1), and the coordinates of the left end point, the right end point, the front end point and the rear end point of the side wall hole (15) are recorded; after the indexing motor (5) is controlled to rotate reversely 180° to return to the origin, the indexing motor (5) is controlled to rotate reversely 180° again, and the coordinates of the left end point, the right end point, the front end point and the rear end point of the circumferential side wall hole (15) of the pipe (1) are recorded; wherein the left end point of the side wall hole (15) is the starting point of the Y-direction feeding processing of the side wall hole (15); C. Select processing plan After the measurement is completed, the coordinates x of the front end point of the side wall hole (15) are obtained. i ,y i 、z i and the coordinate x of the rear endpoint i+1 ,y i+1 、z i+1 , calculate the distance value L between the two endpoints according to the Euclidean distance formula in three-dimensional space, the formula is as follows: and determining the relationship between the distance value L and the diameter D of the ball-shaped grinding rod (14); when the distance value L is smaller than the diameter D, the chamfering processing trajectory of the side wall hole (15) is selected in the first processing scheme, and the process goes to step C1; when the distance value L is larger than the diameter D, the chamfering processing trajectory of the second processing scheme is selected in the side wall hole (15), and the process goes to step C2; C1. Implementation Plan 1 By controlling the X-feed unit (13), the ball-shaped grinding rod (14) is lowered along the positive direction of the X-axis, so that the top end of the grinding rod contacts the left end point of the side wall hole (15) and reaches the target grinding depth of the grinding rod. The spindle motor (2) drives the grinding rod to rotate while controlling the grinding unit to feed along the negative direction of the Y-axis through the linear module (10). After reaching the right end point of the side wall hole (15), the X-feed unit (13) is controlled to make the ball-shaped grinding rod (14) rise along the negative direction of the X-axis, and the grinding rod is controlled to stop rotating and the linear motion of the X-feed unit (13); go to step D; C2. Implementation Plan 2 The endoscope (3) is used to take an image of the surface morphology of the side wall hole (15) to be processed. After obtaining the contour of the side wall hole (15), the processing program of the grinding rod is obtained through the simulation software; then the X-feed unit (13) is controlled to make the ball-shaped grinding rod (14) descend along the positive direction of the X-axis so that the top end of the grinding rod contacts the left end point of the side wall hole (15). After obtaining the tool setting point, according to the processing program, the X-feed unit (13) is used to reach the target grinding depth of the grinding rod. The spindle motor (2) drives the grinding rod to rotate while cooperating with the linear module (10) and the C indexing unit (12) to complete the chamfering of the side wall hole (15); after the processing is completed, the ball-shaped grinding rod (14) is controlled to rise along the negative direction of the X-axis, and then the rotation of the grinding rod and the linear motion of the X-feed unit (13) are stopped; and the process goes to step D; D. Processing chamfering According to the selected execution scheme 1 or execution scheme 2, the ball-shaped grinding rod (14) moves out of the corresponding track under the cooperation of the linear module (10) and the C indexing unit (12), and the grinding depth of the ball-shaped grinding rod (14) is controlled by controlling the displacement of the X-feeding unit (13); after the ball-shaped grinding rod (14) is processed once in the forward direction, it is processed once in the reverse direction, and the number of times the grinding rod is processed is determined. When a set number threshold is met, the grinding rod stops processing, and the X-feeding unit (13), the linear module (10) and the C indexing unit (12) stop moving, and reset is completed; E. Evaluation of the chamfer quality of the side wall hole (15) E1. Calculate the ellipse size of the side wall hole (15) An image of the surface morphology of the side wall hole (15) after processing is taken through an endoscope (3), and the contour of the side wall hole (15) is identified through image processing technology to obtain the complete contour of the side wall hole (15) after processing, and then an ellipse fitting method is used to obtain the ellipse feature of the side wall hole (15). The ellipse formula is: Ax 2 +Bxy+Cy 2 +Dx+Ey+F=0 Among them, A, B, C, D, E, F are the parameters of the ellipse equation. Assuming the ellipse rotation angle is α, then: A=b 2 cos 2 a+a 2 sin 2 a B6(b 2 -a 2 )cosαsinα C=b 2 sin 2 a+a 2 cos 2 a D=-2b 2 x a cosα-2a 2 y a sinα E=2b 2 x a sinα-2a 2 y a cosα F=b 2 x a +a 2 y a 2 -a 2 b 2 In the formula, x a and a are the coordinates of the ellipse center on the X-axis and Y-axis respectively; therefore, we get the relationship between the ellipse parameters, the ellipse rotation angle α, and the coordinate value x a With y a , the calculation formulas for the major axis a and the minor axis b are as follows: After obtaining the ellipse equation, we get the f(A, B, C, D, E, F) function as follows: The extreme value of the parameter value is solved by the following set of equations, and the obtained extreme value point is substituted into the second-order partial derivative equation to determine whether it is a minimum value: Through the above equations, the specific values ​​of the six parameters A, B, C, D, E, and F are solved; then the major axis a and minor axis b of the ellipse are solved, and then compared with the major axis and minor axis sizes of the target ellipse to determine whether the size error meets the requirements; E2. Calculate the fillet size of the chamfer of the side wall hole (15) The point cloud data of the processed side wall hole (15) collected by the laser displacement sensor (4) is filtered to obtain smooth and continuous point cloud data, and the point cloud data of the edge of the side wall hole (15) is retained according to the target chamfer value; at this time, it is observed that the residual point cloud of the edge of the side wall hole (15) shows an obvious slope change, and an inflection point begins to appear from the edge of the side wall hole (15), until the middle sudden break position, the inflection point reaches the maximum value; the inflection point is identified by calculating the second-order derivative of the function, and judging whether the second-order derivative is 0; when the second-order derivative is not 0, it is an inflection point, and when it is 0, it is a straight line segment; for continuous two-dimensional point cloud data, the central difference method of the finite difference method is used to calculate the first-order and second-order derivatives, and the formula is as follows: First-order derivative: Second order derivative: where x i Represents the data points of a two-dimensional point cloud, f(x i ) represents the function value at that point; The position where the second-order derivative has the maximum value is the edge position of the side wall hole (15). Combined with the target chamfer R value, the retention range of the hole edge point cloud data is set, and the least squares method is used to perform circle fitting on the retained hole edge area point cloud. The circle fitting formula is: (x-c) 2 +(y-d) 2 =R 2 The coordinate of the center of the circle on the X-axis is c, and the coordinate on the Y-axis is d, and the radius R of the chamfer of the hole edge is obtained. For the multiple fitting circles obtained on the hole edge, the average radius of the fillet is taken as r; and then, by comparing the fillet size of the edge of the side wall hole (15) with the target fillet size, it is determined whether the fillet size of the chamfer meets the requirements; E3. Calculate the chamfer angle and chamfer width of the side wall hole (15) The point cloud data obtained by filtering the laser displacement sensor (4) is used to obtain a Z-direction cross section of the horizontal point cloud area of ​​the inner wall of the pipe (1), that is, the area near the edge of the hole, which is approximately a horizontal area. The point cloud area on the chamfer is taken in the Z-direction cross section, and the data points of the straight lines measured in the two areas under the cross sections are obtained respectively. The data is a binary function under the plane. At this time, the data points are fitted by the least squares method to obtain the angle J between the fitted straight line and the horizontal axis and the intercept; all the fitted straight lines are calculated to obtain the average angle J1 between the plane and the horizontal axis, and the average angle J2 between the chamfer and the horizontal axis. At this time, the inclination angle size β=|J2-J1|, and the maximum intercept is the chamfer width.

2. According to claim 1, a method for automatically chamfering a side wall hole of a pipe with a large aspect ratio, characterized in that: The method for identifying the contour of the side wall hole (15) in step E1 includes a grayscale clustering segmentation and binarization method, a boundary extraction method or a threshold segmentation method.

3. According to claim 1, a method for automatically chamfering a side wall hole of a pipe with a large aspect ratio, characterized in that: The filtering method in step E2 includes Kalman filtering, radius outlier filtering or statistical filtering.

Images