A hole axis interference fit deformation detection method and device based on small hole diffraction

Abstract

The application discloses a hole shaft interference fit deformation detection method and device based on small hole diffraction, and relates to the technical field of hole shaft interference fit deformation detection. The method comprises the following steps: installing a laser at the edge of a measured fitting hole; and using a laser point positioning assembly to detect the laser emission position before and after the interference fit of the measured fitting hole. According to the change of the light emission coordinates, the hole shaft interference fit deformation amount is judged. The laser is installed at the edge of the interference fit hole, and the positions of the laser before and after the interference fit are detected, so that the deformation amount caused by the interference fit is determined, and whether the deformation amount of the hole shaft interference fit exceeds the allowed range is detected quickly. The application utilizes the characteristics that small amplitude displacement can significantly affect the clarity and shape of the light ring between light and dark in the small hole diffraction image, and realizes accurate detection of the target position coordinates by using a camera and a laser, thereby improving the accuracy of the hole shaft interference fit deformation detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deformation detection, in particular to a hole shaft interference fit deformation detection method and device based on small hole diffraction. BACKGROUND

[0002] In the industrial field, hole shaft interference assembly is a key process in mechanical manufacturing, and the degree of deformation directly affects the assembly quality and service life of parts. The deformation caused by interference assembly exceeding the expected range will lead to part failure, so the detection of hole shaft interference fit deformation is crucial.

[0003] In industrial production, commonly used deformation detection methods include three-coordinate mechanical arm measurement, three-dimensional scanning measurement and industrial photogrammetry technology. Three-coordinate mechanical arm measurement automatically generates measurement data and analysis reports through a computer three-coordinate measurement system, which can accurately judge the quality of parts. This method is widely used in the field of mechanical manufacturing for high-precision measurement of machine tool spindles, lead screws, gears and other precision mechanical parts to ensure their dimensional accuracy, shape accuracy and position accuracy. However, this method requires professional operation, and manual measurement depends on detection reports and experience, and cannot provide comprehensive feedback on the deformation of the entire assembly surface. In addition, three-coordinate measurement is a contact measurement, which has limitations for measurement under certain conditions, such as the inability to measure the size of soft materials.

[0004] Three-dimensional scanning measurement uses laser scanning facilities to compare the point cloud data obtained by scanning with the theoretical model, which can intuitively view the size quality of the parts in all directions. This method is widely used in industrial detection and quality control for size measurement and defect detection of products such as automobile parts and electronic components. However, three-dimensional scanning measurement equipment is expensive and is generally used for reverse engineering and measurement of important and complex parts. Although three-dimensional scanning technology has significant advantages, it has limitations in measuring large areas, and the measurement of complex surfaces and obstructions also faces challenges, and the data post-processing process is complex.

[0005] Industrial photogrammetry technology is used for automatic, intelligent and flexible manufacturing in intelligent manufacturing. For example, for the automatic polishing of some casting blanks, the surface model of the casting blank needs to be measured to plan the polishing robot path and achieve automatic polishing. However, this technology still faces challenges in terms of measurement accuracy and data processing, especially in complex environments.

[0006] In summary, existing deformation detection methods have certain limitations in terms of operation complexity, cost, accuracy and scope of application. Therefore, it is of great practical significance to develop a hole shaft interference fit deformation detection device that is simple in structure, easy to operate, low in cost and high in accuracy. SUMMARY

[0007] The present application aims to provide a hole shaft interference fit deformation detection device based on small aperture diffraction and a hole shaft interference fit deformation detection method and device based on small aperture diffraction to overcome the shortcomings of the prior art and meet the needs of modern industry for high-precision and high-efficiency measurement. The device uses the principle of small aperture diffraction to obtain a small aperture diffraction pattern through an industrial camera and analyzes the formed diffraction image to determine the position of the laser source, thereby achieving rapid and high-precision detection of hole shaft interference fit deformation.

[0008] In the first aspect, the present application provides a hole shaft interference fit deformation detection method based on small aperture diffraction, which comprises:

[0009] A laser is installed at the edge of the measured fitting hole.

[0010] Before the measured fitting hole is subjected to interference fit, the laser point positioning assembly is used to detect the laser exit position as the initial light emission coordinates.

[0011] After the measured fitting hole is subjected to interference fit, the laser point positioning assembly is used to detect the laser exit position as the deformed light emission coordinates.

[0012] According to the change of the deformed light emission coordinates relative to the initial light emission coordinates, the hole shaft interference fit deformation is determined.

[0013] When detecting the laser exit position, the laser point positioning assembly aligns the camera with the laser light emission point, and the position of the camera at this time is taken as the laser exit position. An imaging sheet with an imaging aperture is arranged outside the lens of the camera. By judging the clarity of the small aperture diffraction pattern formed by the laser passing through the imaging aperture, it is determined whether the camera is aligned with the laser light emission point.

[0014] As a preferred embodiment, the camera moves in two degrees of freedom through a two-axis movement module, and the position of the camera is detected by two sets of grating rulers.

[0015] As a preferred embodiment, the process of detecting the laser exit position by the laser point positioning assembly is divided into a preliminary positioning stage and a precise positioning stage.

[0016] In the preliminary positioning stage, the position of the camera is moved so that the laser emitted by the laser can partially or completely pass through the imaging aperture on the imaging sheet, and the camera captures a small aperture diffraction image. Continue to move the position of the camera until a circular diffraction ring with light and dark alternating appears in the small aperture diffraction image.

[0017] In the precise positioning stage, a laser positioning recognition model is used to determine whether the precise positioning of the laser exit position is completed or not. If the precise positioning is not completed, the movement amplitude is reduced and the camera position is moved step by step. After each step of movement, the laser positioning recognition model is used to determine whether the precise positioning of the laser exit position is completed or not until the precise positioning of the laser exit position is completed. The laser positioning recognition model has a mapping relationship between the diffraction pattern and the position information of the laser emitting point relative to the imaging hole.

[0018] As a preferred, the laser positioning recognition model performs threshold different binaryzation processing on the input diffraction image to obtain a multi-channel original feature map; compresses the multi-channel original feature map into a plurality of global features; uses two fully connected layers to respectively reduce the dimension and restore the initial dimension of the global features, and the obtained features are used as weights and multiplied by the multi-channel original feature map; the obtained enhanced features are input into a plurality of convolution blocks in series for feature extraction and then input into a fully connected layer; and the fully connected layer outputs the imaging hole position information.

[0019] As a preferred, a plurality of lasers are installed at different positions of the edge of the measured mating hole. Before and after the measured mating hole is subjected to interference fit, a laser point positioning assembly is used to detect the laser exit position of each laser.

[0020] In a second aspect, the present application provides a hole shaft interference fit deformation detection device for performing the hole shaft interference fit deformation detection method described above. The hole shaft interference fit deformation detection device comprises a base, a two-axis movement module capable of detecting the movement position installed on the base, and a laser point positioning assembly installed on the two-axis movement module. The laser point positioning assembly comprises a camera, an imaging sheet and a light shielding sleeve. The imaging sheet is arranged at the outside of the lens of the camera. An imaging hole aligned with the center position of the lens of the camera is formed on the imaging sheet. The light shielding sleeve is sleeved on the position between the camera lens and the imaging sheet to avoid the influence of ambient light on the detection result.

[0021] As a preferred, the laser point positioning assembly further comprises a camera support plate and a support plate. The support plate comprises a horizontal plate and a vertical plate fixed together and perpendicular to each other. The horizontal plate of the support plate is fixed on the Y-axis electric sliding table. The camera support plate is provided with a waist-shaped adjusting hole. The camera support plate and the vertical plate of the support plate are fixed and adjusted in height by the bolt and the waist-shaped adjusting hole. The camera fixed on the camera support plate is arranged vertically along the axis.

[0022] As preferred, the laser point positioning assembly further comprises an adapter threaded sleeve, a small hole height adjusting sleeve, a mounting plate and a pressing plate. The lens of the camera is threadedly connected with the adapter threaded sleeve. The adapter threaded sleeve is threadedly connected with the small hole height adjusting sleeve and the relative position is adjusted along the axial direction. The small hole height adjusting sleeve is locked with the adapter threaded sleeve by bolts. The mounting plate is mounted on the outer end of the small hole height adjusting sleeve. The imaging sheet is arranged on the inner side of the mounting plate and is fixed by the pressing plate. The light shielding sleeve is arranged on the outer side of the adapter threaded sleeve.

[0023] As preferred, the two-axis moving module comprises an X-axis electric sliding table and a Y-axis electric sliding table. The X-axis electric sliding table is mounted on the base. The Y-axis electric sliding table is mounted on the X-axis electric sliding table. The laser point positioning assembly is mounted on the Y-axis electric sliding table.

[0024] As preferred, the X-axis electric sliding table comprises an X-axis guide rail, an X-axis grating ruler and an X-axis sliding block. The X-axis sliding block is slidingly connected on the X-axis guide rail and is driven by an X-axis sliding driving assembly. The X-axis grating ruler is mounted on the X-axis guide rail and is matched with an X-axis grating detection head fixed on the X-axis sliding block. The Y-axis electric sliding table comprises a Y-axis guide rail, a Y-axis grating ruler and a Y-axis sliding block. The Y-axis sliding block is slidingly connected on the Y-axis guide rail and is driven by a Y-axis sliding driving assembly. The Y-axis grating ruler is mounted on the Y-axis guide rail and is matched with a Y-axis grating detection head fixed on the Y-axis sliding block.

[0025] The present application has the following beneficial effects.

[0026] The present application installs the laser on the edge of the interference fit hole, and detects the position of the laser before and after the interference fit respectively, so as to determine the deformation caused by the interference fit, and to detect whether the deformation of the interference fit of the hole shaft exceeds the allowable range.

[0027] The present application utilizes the characteristics that small displacement can significantly affect the clarity and shape of the light ring between light and dark in the diffraction image of the small hole, and utilizes the camera and the laser to realize accurate detection of the target position coordinates, thereby improving the accuracy of the deformation detection of the interference fit of the hole shaft.

[0028] The detection device provided by the present application has simple structure and high flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The side structure schematic view of the hole shaft interference fit deformation detection device provided for the embodiment 1 of the present application is shown in the figure.

[0030] Figure 2 The combination schematic view of the mounting plate, the imaging sheet and the pressing plate in the embodiment 1 of the present application is shown in the figure.

[0031] Figure 3 A top view schematic diagram of the hole axis interference fit deformation detection device provided for embodiment 1 of the present application;

[0032] Figure 4 A flowchart for embodiment 2 of the present application.

[0033] Figure 5 A schematic diagram of the installation position of the laser in embodiment 2 of the present application.

[0034] Figure 6 A small hole diffraction principle diagram in embodiment 2 of the present application.

[0035] Figure 7 A schematic diagram of the diffraction image collected in embodiment 2 of the present application.

[0036] The reference numerals: 1, adapter threaded sleeve; 2, small hole height adjusting sleeve; 3, camera support plate; 4, base plate; 5, side support leg; 6, U-shaped handle; 7, support plate; 8, mounting plate; 9, imaging sheet; 10, pressing plate; 11, light shielding sleeve; 12, X-axis electric sliding table; 13, Y-axis electric sliding table; 121, X-axis grating ruler; 122, X-axis sliding block; 131, Y-axis grating ruler; 132, Y-axis sliding block; 14, camera; 15, measured mating hole; 16, laser. DETAILED DESCRIPTION

[0037] The following specific embodiments illustrate the embodiments of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosed content.

[0038] Embodiment 1

[0039] As shown in Figure 1 and Figure 3 , a hole axis interference fit deformation detection device based on small hole diffraction includes a base, a two-axis moving module, a laser point positioning assembly, and a laser. During operation, the laser is installed at the position near the edge of the assembly hole on the top surface of the workpiece, and the laser emission direction is perpendicular to the top surface of the workpiece.

[0040] The base includes a base plate 4, a side support leg 5, and a U-shaped handle 6. The base plate 4 and the side support leg 5 are positioned by a conical pin and fixed by a bolt. The side support leg 5 serves as a support structure for the entire device, avoiding unnecessary collision damage caused by direct contact between the upper electric sliding table and the measured object. The side support leg 5 is provided with a corresponding mounting hole for mounting the U-shaped handle 6, and the operator can move the device conveniently and quickly through the U-shaped handle 6.

[0041] The two-axis moving module includes an X-axis electric sliding table 12 and a Y-axis electric sliding table 13. The X-axis electric sliding table 12 is mounted on a base and includes an X-axis guide rail, an X-axis grating ruler 121 and an X-axis sliding block 122. The base plate 4 is provided with corresponding threaded holes. The base plate 4 is fixed to the X-axis guide rail by bolts. The X-axis sliding block 122 is slidingly connected to the X-axis guide rail and is driven by an X-axis sliding drive assembly. The X-axis grating ruler 121 is mounted on the X-axis guide rail and is matched with an X-axis grating detection head fixed to the X-axis sliding block 122.

[0042] The Y-axis electric sliding table 13 is mounted on the X-axis sliding block 122 of the X-axis electric sliding table and includes a Y-axis guide rail, a Y-axis grating ruler 131 and a Y-axis sliding block 132. The threaded holes on the X-axis sliding block 122 are fixed to the Y-axis guide rail of the Y-axis electric sliding table 13 by bolts. The Y-axis sliding block 132 is slidingly connected to the Y-axis guide rail and is driven by a Y-axis sliding drive assembly. The Y-axis grating ruler 131 is mounted on the Y-axis guide rail and is matched with a Y-axis grating detection head fixed to the Y-axis sliding block 132.

[0043] The laser point positioning assembly is mounted on the Y-axis sliding block 132 of the Y-axis electric sliding table 13. During measurement, the X-axis electric sliding table 12 and the Y-axis electric sliding table 13 control the movement of the laser point positioning assembly in the X-axis and Y-axis directions through the movement of the X-axis sliding block 122 and the Y-axis sliding block 132 above, so that the laser point positioning assembly performs sub-micron precision movement on the entire measured plane.

[0044] The X-axis grating ruler 121 and the Y-axis grating ruler 131 on the two electric sliding tables can read the current X-axis position and Y-axis coordinate position of the deformation detection module and feed back the readings to the control drive module to realize the micro movement of the electric sliding table, and the minimum single displacement can reach 0.5 μm.

[0045] The X-axis electric sliding table 12 adopts a linear module with a model number of OC05-CXN60300-F2PN-G42-MH, and the Y-axis electric sliding table 13 adopts a linear module with a model number of CXN6050-S. The X-axis grating ruler 121 and the Y-axis grating ruler 131 have a precision of 50 nm, so that the two-axis moving module realizes sub-micron displacement control.

[0046] As shown in Figure 2 The laser point positioning assembly includes a camera support plate 3, a camera 14, an adapter threaded sleeve 1, a small hole height adjusting sleeve 2, a support plate 7, a mounting plate 8, an imaging sheet 9, a pressing plate 10 and a light shielding sleeve 11. The support plate 7 includes a horizontal plate and a vertical plate which are fixed together and perpendicular to each other. The horizontal plate of the support plate 7 is connected to the Y-axis sliding block 132 through threaded screws. The support plate 7 plays a transitional role in the electric sliding table 13 and is used to ensure that the axis of the camera 14 in the laser point positioning assembly is perpendicular to the measured surface.

[0047] The vertical plate of the support plate 7 is provided with a threaded hole. The camera support plate 3 is provided with a waist-shaped adjusting hole. The waist-shaped adjusting hole of the camera support plate 3 is connected with the threaded hole on the vertical plate of the support plate 7 through a bolt. The side of the camera support plate 3 is fixed with the camera 14 through a countersunk screw.

[0048] The height of the camera support plate 3 can be adjusted through the waist-shaped adjusting hole on the camera support plate 3, and then the distance between the camera 14 and the measured surface can be adjusted. Before the specific detection, the height of the camera 14 is fixed after the optimal imaging position is found by adjusting the height of the camera 14, and the distance between the camera 14 and the measured surface is not changed before and after the interference assembly of the measured workpiece.

[0049] The lens at the bottom of the camera 14 is threadedly connected with the adapter threaded sleeve 1. The adapter threaded sleeve 1 is processed with external threads, which is used for threadedly connecting with the small-hole height adjusting sleeve 2 to achieve an adjustable distance. By rotating the small-hole height adjusting sleeve 2, the height position of the small-hole height adjusting sleeve 2 can be adjusted.

[0050] A plurality of threaded holes matched with the small-hole height adjusting sleeve 2 are arranged on the circumference of the adapter threaded sleeve 1. The upper part of the small-hole height adjusting sleeve 2 is provided with a waist-shaped adjusting hole. After the small-hole height adjusting sleeve 2 is adjusted to the required height, the small-hole height adjusting sleeve 2 can be locked and fixed with the adapter threaded sleeve 1 through a bolt and the waist-shaped adjusting hole to prevent the shaking of the small-hole height adjusting sleeve 2 caused by the existence of the threaded distance.

[0051] The mounting plate 8 is threadedly connected with the internal threads in the small-hole height adjusting sleeve 2 to achieve an adjustable distance, so as to adjust the distance between the mounting plate 8 and the camera 14, and then change the circular ring distance of the small-hole diffraction imaging and the size of the small hole. It should be noted that the distance between the mounting plate 8 and the camera 14 should be adjusted under the premise of meeting the Fresnel approximation condition.

[0052] The imaging sheet 9 is fixed on the upper surface of the mounting plate 8 through a bolt. The center position of the imaging sheet 9 is provided with an imaging hole for realizing the small-hole diffraction phenomenon. The pressing plate 10 arranged above the imaging sheet 9 is used for fixing the imaging sheet and preventing the relative slipping and damage of the imaging sheet and the mounting plate 8. The outer side of the small-hole height adjusting sleeve 2 is provided with a light shielding sleeve 11, which is used for preventing the external light from entering the inside of the small-hole height adjusting sleeve 2 through the long hole on the small-hole height adjusting sleeve 2 to affect the imaging effect.

[0053] The small-hole height adjusting sleeve 2, the mounting plate 8, the pressing plate 10, the adapter threaded sleeve 1 and the light shielding sleeve 11 are all blackened to prevent the laser passing through the imaging hole of the imaging sheet 9 from being diffusely reflected in the small-hole height adjusting sleeve 2, thereby affecting the imaging effect.

[0054] Example 2

[0055] A hole-shaft interference fit deformation detection method based on small hole diffraction, using the hole-shaft interference fit deformation detection device provided in Embodiment 1.

[0056] As shown in Figure 4 The hole-shaft interference fit deformation detection method includes the following steps:

[0057] S1, device installation and movement

[0058] Lift the device to a small distance above the measured fit hole 15 by the U-shaped handle 6, move the U-shaped handle 6 left and right so that the initial position of the camera 14 is directly above the center axis of the measured fit hole 15, loosen the U-shaped handle 6, and make the side feet 5 below the device contact the upper surface of the structure where the measured fit hole 15 is located.

[0059] S2, setting of the single-mode laser 16, small hole diffraction positioning principle, and preliminary positioning.

[0060] Before using the device, first adjust the position of the small hole height adjustment sleeve 2 and the mounting plate 8, so that the distance between the camera 14 lens and the imaging hole on the imaging sheet 9 reaches the preset value, meets the Fresnel approximation condition, and makes the small hole diffraction image clear and appropriate in size after the laser 16 is positioned. As shown in Figure 5 Set the laser 16 on the left side of the measured fit hole 15, and keep it perpendicular to the upper surface of the structure where the measured fit hole 15 is located.

[0061] As shown in Figure 6 Since the distance between the imaging sheet 9 and the camera 14 meets the Fresnel approximation condition, if the laser emitted by the laser 16 accurately enters the imaging hole in the vertical direction, a Fresnel diffraction will occur, forming a circular diffraction light ring with alternating bright and dark areas; if the laser does not enter the imaging hole or deviates from the imaging hole by a large range (sub-millimeter level), the diffraction pattern will change significantly (become blurred or even disappear). Preliminary positioning of the laser can be achieved through this way.

[0062] Before the hole-shaft interference fit, adjust the lens position of the camera 14 by adjusting the X-axis electric sliding table 12 and the Y-axis electric sliding table 13 with a larger step, until the laser generated by the laser 16 vertically enters the imaging hole on the imaging sheet 9 below the camera 14, forming a small hole diffraction image. At this time, adjust the single displacement accuracy of the two electric sliding tables to the sub-millimeter level, and move the position of the camera 14 and the imaging hole to find the position where the small hole imaging is clear, until the small hole diffraction imaging image of the laser is appropriate and clear, which indicates that the laser is approximately completely through the small hole, and the preliminary positioning is completed, as shown in Figure 7

[0063] S3, based on neural network analysis to determine the alignment state of the imaging hole and the laser to complete precise positioning. ​

[0064] On the basis of the initial positioning, the two electric sliding platforms are controlled to move in the plane by 0.5 pm each time, so as to realize the position fine adjustment, and the obtained diffraction image is recorded after each adjustment. Since the diffraction pattern obtained after the laser source passes through the small hole (as shown in FIG. 2) conforms to the Fresnel-Kirchhoff diffraction integral formula, the diffraction result can be calculated by the following formula (1): Figure 6

[0065]

[0066] wherein, is the light field (intensity and phase) of the observation point P; is the light field of any point Q in the imaging hole; is the wavelength of the laser; is the wave number of the laser; is the surface area of the small hole; is the unit normal vector of the diffraction aperture plane, which is perpendicular to the aperture surface; is the vector from the observation point P to the point Q on the aperture plane; is the vector from the laser S to the point Q on the aperture plane; r is the distance from the observation point P to the point Q on the aperture plane; and i is the imaginary unit.

[0067] Therefore, when the relative position between the laser source and the small hole changes, the values of the light field and the cosine value change, thereby causing the diffraction pattern to change accordingly. Since it is relatively complex to solve the diffraction result by formula (1), for the case satisfying the Fresnel approximation condition (formula 2), the Fresnel approximation formula (formula 3) is generally used for calculation, as shown below:

[0068]

[0069] wherein, is the distance from the observation plane to the aperture plane; , is the coordinate on the aperture plane; , is the coordinate of the observation plane.

[0070] Therefore, it can be known from the Fresnel approximation formula that there is a forward mapping relationship between the relative position of the laser source and the small hole and the diffraction pattern, and obtaining the position information of the laser source through the diffraction pattern is a reverse mapping relationship. Since the mapping relationship between the diffraction image and the laser position is a nonlinear mapping relationship, the image can be nonlinearly recognized by a convolutional neural network (CNN), and the relationship between the laser position and the diffraction pattern can be reflected by a theoretical model such as formula (4):

[0071] ​

[0072] wherein is a matrix formed by the diffraction pattern received by the CCD camera; is a matrix formed by the displacement between the laser and the small hole; is and the mapping relationship between.

[0073] The laser positioning recognition model for nonlinear recognition in the embodiment adopts the SENet structure. The obtained diffraction image is subjected to threshold different binaryzation processing to extract corresponding features, so as to expand the original image into a plurality of channel original feature maps. Further, the obtained original feature map is compressed into N global features as shown in formula (5) (in the embodiment, the size of the obtained original feature image is N x H x W, N is the number of channels, H and W are respectively the number of pixel points in the height and width directions of the image).

[0074] Then, the obtained global features are operated through two fully connected layers. The first fully connected layer plays a role of dimension reduction and adopts a Relu activation function. The second fully connected layer restores the global feature quantity to the initial dimension and adopts a Sigmoid activation function, which is specifically shown in formula (6):

[0075]

[0076] wherein is the compressed global feature; is the output feature of the second fully connected layer; is the original feature map; is the Sigmoid function; is the Relu function.

[0077] Finally, the feature is taken as the weight of each channel and is multiplied by all elements of the multi-channel original feature map, so as to enhance the key channel and weaken the unimportant channel to obtain the processed result, which is specifically shown in formula (7):

[0078]

[0079] wherein is the new feature map after processing.

[0080] The enhanced feature is input into a plurality of convolution blocks in series to extract corresponding image information. Each convolution block contains a convolution layer, a batch normalization layer and a pooling layer. The output feature of the last convolution block is input into a fully connected layer; the fully connected layer outputs a mapping result. The mapping result is the position coordinate information of the laser relative to the imaging hole.

[0081] Therefore, after obtaining the diffraction pattern of each position and constructing the relationship between the imaging and the position of the laser by the neural network, the specific position of the laser is reflected by the obtained diffraction pattern, so as to realize the accurate positioning of the laser.

[0082] S4, hole deformation detection

[0083] Before the hole shaft interference assembly, the positioning of the laser is completed according to steps S2 and S3, and the readings of the X-axis grating ruler 121 and the Y-axis grating ruler 131 are recorded as the initial light-emitting coordinates (x1, y1) respectively; the hole shaft interference assembly is performed while the hole shaft interference assembly deformation detection device is kept stationary;

[0084] After the assembly, the position of the laser 16 is offset due to the deformation caused by the hole shaft interference. The positioning of the laser is completed again by re-executing steps S2 and S3, and the position information of the two grating rulers at this time is recorded again as the light-emitting coordinates (x'1, y'1) after deformation, and the interference assembly deformation amount Δ is calculated 总 and the x-axis deformation component Δx and the y-axis deformation component Δy thereof are shown in formulas (8)-(10):

[0085]

[0086] In some other embodiments, a plurality of lasers 16 are used. Each laser 16 is installed at different positions on the edge of the measured mating hole 15. In the process of executing steps S2 and S3 twice, the initial light-emitting coordinates (x i ,y i ) and the light-emitting coordinates (x' i ,y' i ) after deformation of each laser 16 are detected and recorded, i =1,2,..., n ; n the number of lasers 16; the initial light-emitting coordinates (x i ,y i ) and the light-emitting coordinates (x' i ,y' i ) after deformation of each laser 16 are measured, and the corresponding x-axis deformation component Δx i and the y-axis deformation component Δy i are calculated respectively.

[0087] The interference assembly deformation amount is obtained by integrating the x-axis deformation components Δx i and the y-axis deformation components Δy i . In this embodiment, the average value of the x-axis deformation components Δx i is taken as the final x-axis deformation component. The average value of the y-axis deformation components Δy iThe average of the y-axis deformation components is taken as the final y-axis deformation component. According to the final x-axis deformation component and the y-axis deformation component, the final interference fit deformation is calculated by using formula (10).

[0088] The embodiment can effectively detect the deformation of the interference fit of the hole shaft, the detection process is simple, the specific situation of the measured mating hole 15 after deformation can be quickly obtained, and whether the interference fit part is qualified is judged. In some embodiments, when the measured interference fit deformation is greater than the error threshold, it is determined that the interference fit part is unqualified.

Claims

1. A hole-axle interference fit deformation detection method based on small aperture diffraction, characterized by, The method comprises: installing a laser at the edge of the mating hole to be measured; detecting the laser emission position using the laser point positioning assembly before the mating hole to be measured is subjected to interference fit, as the initial light emission coordinates; detecting the laser emission position using the laser point positioning assembly after the mating hole to be measured is subjected to interference fit, as the deformed light emission coordinates; judging the interference fit deformation of the hole axis according to the change of the deformed light emission coordinates relative to the initial light emission coordinates; when detecting the laser emission position, the laser point positioning assembly takes the position of the camera when the camera is aligned with the laser emission point as the laser emission position; the outside of the lens of the camera is spaced apart from an imaging sheet with an imaging hole; whether the camera is aligned with the laser emission point is judged by the clarity of the pinhole diffraction pattern formed by the laser passing through the imaging hole; the process of detecting the laser emission position by the laser point positioning assembly is divided into a preliminary positioning stage and a precise positioning stage; in the preliminary positioning stage, the position of the camera is moved so that the laser emitted by the laser can partially or completely pass through the imaging hole on the imaging sheet, and the camera captures a pinhole diffraction image; the camera position is continuously moved until a circular diffraction light ring with light and dark interlaced is presented in the pinhole diffraction image; in the precise positioning stage, whether the precise positioning of the laser emission position is completed is judged using a laser positioning recognition model; if the precise positioning is not completed, the movement amplitude is reduced and the camera position is moved step by step; after each step of movement, whether the precise positioning of the laser emission position is completed is judged again using the laser positioning recognition model until the precise positioning of the laser emission position is completed; the laser positioning recognition model has a mapping relationship between the diffraction pattern and the position information of the laser emission point relative to the imaging hole; the laser positioning recognition model performs threshold different binaryzation processing on the input diffraction image to obtain a multi-channel original feature map; the multi-channel original feature map is compressed into a plurality of global features; two fully connected layers are used to reduce the dimension and restore the initial dimension of the global features respectively, and the obtained features are taken as weights and multiplied with the multi-channel original feature map; the obtained enhanced features are input into a plurality of convolution blocks in series for feature extraction and then input into a fully connected layer; the fully connected layer outputs the position information of the imaging hole.

2. The bore shaft interference fit deformation detection method of claim 1, wherein: The camera moves in two degrees of freedom through a two-axis movement module, and the position of the camera is detected through two groups of grating rulers.

3. The bore shaft interference fit deformation detection method of claim 1, wherein: A plurality of lasers are installed at different positions at the edge of the mating hole to be measured; the laser emission position of each laser is detected using the laser point positioning assembly before and after the mating hole to be measured is subjected to interference fit.

4. A bore shaft interference fit deformation detection apparatus, characterized by: A device for performing the interference fit deformation detection method of the hole axis according to claim 1; the device comprises a base, a two-axis movement module capable of detecting the movement position installed on the base, and a laser point positioning assembly installed on the two-axis movement module; the laser point positioning assembly comprises a camera (14), an imaging sheet (9), and a light shielding sleeve (11); the imaging sheet (9) is spaced apart from the outside of the lens of the camera (14); the imaging hole of the imaging sheet (9) is aligned with the center position of the lens of the camera (14); and the light shielding sleeve (11) is sleeved at the position between the lens of the camera (14) and the imaging sheet (9).

5. The bore shaft interference fit deformation detection apparatus of claim 4, wherein: The laser point positioning assembly further comprises a camera support plate (3) and a support plate (7); the support plate (7) comprises a horizontal plate and a vertical plate which are fixed together and perpendicular to each other; the horizontal plate of the support plate (7) is fixed on the Y-axis electric sliding table (13); the camera support plate (3) is provided with a waist-shaped adjusting hole; the camera support plate (3) and the vertical plate of the support plate (7) are fixed by bolts and the waist-shaped adjusting hole to adjust the height of the camera support plate (3); the camera with the axis vertically arranged is fixed on the camera support plate (3).

6. The bore shaft interference fit deformation detection apparatus of claim 4, wherein: The laser point positioning assembly further comprises an adapter threaded sleeve (1), a small-hole height adjusting sleeve (2), a mounting plate (8) and a pressing plate (10); the lens of the camera (14) is threadedly connected with the adapter threaded sleeve (1); the adapter threaded sleeve (1) and the small-hole height adjusting sleeve (2) are connected by threads and adjust the relative position along the axial direction; the small-hole height adjusting sleeve (2) is locked with the adapter threaded sleeve (1) by bolts; the mounting plate (8) is mounted at the outer end of the small-hole height adjusting sleeve (2); the imaging sheet (9) is arranged on the inner side of the mounting plate (8) and is fixed by the pressing plate (10); the light shielding sleeve (11) is arranged on the outer side of the adapter threaded sleeve (1).

7. The bore shaft interference fit deformation detection apparatus of claim 4, wherein: The two-axis moving module comprises an X-axis electric sliding table (12) and a Y-axis electric sliding table (13); the X-axis electric sliding table (12) is mounted on the base; the Y-axis electric sliding table (13) is mounted on the X-axis electric sliding table (12); the laser point positioning assembly is mounted on the Y-axis electric sliding table (13).

8. The bore shaft interference fit deformation detection apparatus of claim 7, wherein: The X-axis electric sliding table (12) comprises an X-axis guide rail, an X-axis grating ruler (121) and an X-axis sliding block (122); the X-axis sliding block (122) is slidingly connected to the X-axis guide rail and is driven by an X-axis sliding driving assembly; the X-axis grating ruler (121) is mounted on the X-axis guide rail and is matched with an X-axis grating detection head fixed on the X-axis sliding block (122); the Y-axis electric sliding table (13) comprises a Y-axis guide rail, a Y-axis grating ruler (131) and a Y-axis sliding block (132); the Y-axis sliding block (132) is slidingly connected to the Y-axis guide rail and is driven by a Y-axis sliding driving assembly; the Y-axis grating ruler (131) is mounted on the Y-axis guide rail and is matched with a Y-axis grating detection head fixed on the Y-axis sliding block (132).

Images