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

Abstract

The invention discloses a hole-axis interference fit deformation detection method and device based on small hole diffraction. The method comprises the following steps: installing a laser at the edge of a detected mating hole; before and after interference fit is carried out on the detected matching hole, the laser point positioning assembly is used for detecting the laser emitting position. And judging the interference fit deformation of the hole and the shaft according to the change of the light-emitting coordinates. According to the invention, the laser is installed at the edge of the interference fit hole, and the positions of the laser before and after interference fit are respectively detected, so that the deformation caused by interference fit is determined, and whether the deformation of interference fit of the hole and the shaft exceeds an allowable range or not is rapidly detected. According to the method, the characteristic that small-amplitude displacement can obviously influence the clear degree and shape of a light ring with alternate brightness and darkness in a small-hole diffraction image is utilized, the camera and the laser are utilized to realize accurate detection of coordinates of a target position, and the precision of hole-shaft interference assembly deformation detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of deformation detection, and particularly relates to a method and device for detecting the deformation of an interference fit of a hole axis based on small hole diffraction. Background Art

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

[0003] In industrial production, common deformation detection methods include coordinate measuring machine arm measurement, 3D scanning measurement, and industrial photogrammetry technology. The coordinate measuring machine arm measurement automatically generates measurement data and analysis reports through a computer coordinate measurement system, and can accurately judge the quality of parts. This method is widely used in the field of mechanical manufacturing for high-precision measurement of precision mechanical components such as machine tool spindles, lead screws, and gears to ensure their dimensional accuracy, shape accuracy, and position accuracy. However, this method requires professional operation, and manual measurement and marking rely on inspection reports and experience, and cannot comprehensively feedback the deformation of the entire assembly surface. In addition, coordinate measurement is a contact measurement method, and there are limitations in measuring under certain specific conditions, such as being unable to measure the dimensions of soft materials.

[0004] The 3D scanning measurement uses a laser scanning facility to compare the scanned point cloud data with the theoretical digital model, and can comprehensively and intuitively view the dimensional quality of parts. This method is widely used in industrial inspection and quality control for dimensional measurement and defect detection of products, such as automotive parts, electronic components, etc. However, the cost of 3D scanning measurement equipment is relatively high, and it is generally used for reverse development projects and measurement of important and complex parts. Although 3D scanning technology has significant advantages, it has limitations in processing large-scale area measurements, and there are also challenges in measuring complex surfaces and obstacles, and the data post-processing process is relatively complex.

[0005] Industrial photogrammetry technology is used for automatic, intelligent, and flexible manufacturing in intelligent manufacturing. For example, for the automatic grinding of some cast blanks, it is necessary to measure the surface model of the cast blank in order to plan the path of the grinding robot and achieve automatic grinding. However, this technology still faces challenges in measurement accuracy and data processing, especially the measurement accuracy and reliability in complex environments need to be improved.

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

[0007] The object of the present invention is to provide a deformation detection device for interference fit of hole axis based on small hole diffraction, a method and device for detecting interference fit deformation of hole axis based on small hole diffraction, so as to overcome the deficiencies of the prior art and meet the requirements of modern industry for high-precision and high-efficiency measurement. The device utilizes the principle of small hole diffraction, obtains the small hole diffraction pattern through an industrial camera, and judges the position of the laser source by analyzing the formed diffraction image, thereby realizing rapid and high-precision detection of the interference fit deformation of the hole axis.

[0008] In the first aspect, the present invention provides a method for detecting interference fit deformation of hole axis based on small hole diffraction, and the method includes: Install a laser at the edge of the measured mating hole.

[0009] Before the interference fit of the measured mating hole, use the laser point positioning component to detect the laser emission position as the initial light emission coordinate.

[0010] After the interference fit of the measured mating hole, use the laser point positioning component to detect the laser emission position as the light emission coordinate after deformation.

[0011] Judge the interference fit deformation amount of the hole axis according to the change of the light emission coordinate after deformation relative to the initial light emission coordinate.

[0012] When detecting the laser emission position, the laser point positioning component takes the position of the camera when the camera is aligned with the laser emission point as the laser emission position. An imaging film with an imaging hole is arranged at intervals outside the lens of the camera. The clarity of the small hole diffraction pattern formed by the laser passing through the imaging hole is used to judge whether the camera is aligned with the laser emission point.

[0013] Preferably, 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 scales.

[0014] Preferably, the process of the laser point positioning component detecting the laser emission position is divided into a preliminary positioning stage and a precise positioning stage.

[0015] In the preliminary positioning stage, move the position of the camera so that the laser emitted by the laser can partially or completely pass through the imaging hole on the imaging film, and the camera collects the small hole diffraction image. Continue to move the position of the camera until a circular diffraction ring with light and dark intervals appears in the small hole diffraction image.

[0016] In the precise positioning stage, a laser positioning recognition model is used to determine whether the precise positioning of the laser emission position is completed; 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 again to determine whether the precise positioning of the laser emission position is completed 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.

[0017] Preferably, the laser positioning recognition model performs binarization processing on the input diffraction image with different thresholds to obtain a multi-channel original feature map; compresses the multi-channel original feature map into multiple global features; uses two fully connected layers to reduce the dimension and restore the initial dimension of the global features respectively, and the obtained features are used as weights to multiply with the multi-channel original feature map; the obtained enhanced features are input into a series of convolutional blocks for feature extraction and then input into a fully connected layer; the fully connected layer outputs the position information of the imaging hole.

[0018] Preferably, a plurality of lasers are installed at different positions on the edge of the measured mating hole. Before and after the interference fit of the measured mating hole, the laser point positioning component is used to detect the laser emission position of each laser respectively.

[0019] In a second aspect, the present invention provides a device for detecting the deformation of interference fit between a hole and a shaft, which is used to execute the method for detecting the deformation of interference fit between a hole and a shaft described above. The device for detecting the deformation of interference fit between a hole and a shaft includes a base, a two-axis moving module installed on the base and capable of detecting the moving position, and a laser point positioning component installed on the two-axis moving module. The laser point positioning component includes a camera, an imaging film and a light-shielding sleeve. The imaging film is arranged at intervals outside the lens of the camera. An imaging hole aligned with the center position of the lens of the camera is opened on the imaging film. The light-shielding sleeve is sleeved at the position between the camera lens and the imaging film to avoid the influence of ambient light on the detection result.

[0020] Preferably, the laser point positioning component further includes a camera support plate and a support plate. The support plate includes a horizontal plate and a vertical plate that are fixed together and perpendicular to each other. The horizontal plate of the support plate is fixed on the Y-axis electric slide table. The camera support plate is provided with a waist-shaped adjustment hole. The camera support plate and the vertical plate of the support plate are fixed and the height of the camera support plate is adjusted through bolts and the waist-shaped adjustment hole. The camera with a vertically arranged axis is fixed on the camera support plate.

[0021] Preferably, the laser spot positioning assembly further includes an adapter threaded sleeve, a small hole height adjustment sleeve, a mounting plate and a pressing plate. The lens of the camera is threadedly connected to the adapter threaded sleeve. The adapter threaded sleeve and the small hole height adjustment sleeve are threadedly connected and axially adjusted relative to each other. The small hole height adjustment sleeve and the adapter threaded sleeve are locked by bolts. The mounting plate is installed at the outer end of the small hole height adjustment sleeve. The imaging film is arranged inside the mounting plate and fixed by the pressing plate. The light-shielding sleeve is sleeved outside the adapter threaded sleeve.

[0022] Preferably, the two-axis moving module includes an X-axis electric slide and a Y-axis electric slide. The X-axis electric slide is installed on the base. The Y-axis electric slide is installed on the X-axis electric slide. The laser spot positioning assembly is installed on the Y-axis electric slide.

[0023] Preferably, the X-axis electric slide includes an X-axis guide rail, an X-axis grating scale and an X-axis slider. The X-axis slider is slidably connected to the X-axis guide rail and driven by an X-axis sliding drive assembly. The X-axis grating scale is installed on the X-axis guide rail and matches with an X-axis grating detection head fixed on the X-axis slider. The Y-axis electric slide includes a Y-axis guide rail, a Y-axis grating scale and a Y-axis slider. The Y-axis slider is slidably connected to the Y-axis guide rail and driven by a Y-axis sliding drive assembly. The Y-axis grating scale is installed on the Y-axis guide rail and matches with a Y-axis grating detection head fixed on the Y-axis slider.

[0024] The present invention has the following beneficial effects.

[0025] In the present invention, 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 respectively detected, thereby determining the deformation amount caused by the interference fit, so as to quickly detect whether the deformation amount of the hole-shaft interference assembly exceeds the allowable range.

[0026] The present invention utilizes the characteristic that a small displacement can significantly affect the clarity and shape of the bright and dark fringes in the small hole diffraction image, and uses a camera and a laser to accurately detect the target position coordinates, improving the detection accuracy of the deformation amount of the hole-shaft interference assembly.

[0027] The detection device provided by the present invention has a simple structure and can be manually transferred to different structures for testing, with extremely high flexibility. Description of the Drawings

[0028] Figure 1 It is a schematic side view structure diagram of the hole-shaft interference fit deformation detection device provided in Embodiment 1 of the present invention; Figure 2 It is a combined schematic diagram of the mounting plate, the imaging film and the pressing plate in Embodiment 1 of the present invention.

[0029] Figure 3The top view schematic diagram of the hole-shaft interference fit deformation detection device provided in Embodiment 1 of the present invention; Figure 4 The flowchart of Embodiment 2 of the present invention.

[0030] Figure 5 The schematic diagram of the installation position of the laser in Embodiment 2 of the present invention.

[0031] Figure 6 The principle diagram of small hole diffraction in Embodiment 2 of the present invention.

[0032] Figure 7 The schematic diagram of the diffraction image collected in Embodiment 2 of the present invention.

[0033] Reference numerals: 1, adapter threaded sleeve; 2, small hole height adjustment sleeve; 3, camera support plate; 4, base plate; 5, side support feet; 6, U-shaped handle; 7, support plate; 8, mounting plate; 9, imaging film; 10, pressing plate; 11, light-shielding sleeve; 12, X-axis electric slide; 13, Y-axis electric slide; 121, X-axis grating scale; 122, X-axis slider; 131, Y-axis grating scale; 132, Y-axis slider; 14, camera; 15, measured mating hole; 16, laser. Detailed implementation manners

[0034] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0035] Embodiment 1 As Figure 1 and Figure 3 shown, a hole-shaft interference fit deformation detection device based on small hole diffraction includes a base, a two-axis movement module, a laser point positioning component, and a laser. During the working process, the laser is installed at a 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.

[0036] The base includes a base plate 4, side support feet 5, and a U-shaped handle 6. The base plate 4 and the side support feet 5 are positioned by conical pins and fixed by bolts. The side support feet 5 serve as the support structure of the entire device to avoid unnecessary collision damage caused by direct contact between the upper electric slide and the measured object. Corresponding mounting holes are provided on the side support feet 5 for installing the U-shaped handle 6, and the operator can move the device conveniently and quickly through the U-shaped handle 6.

[0037] The two-axis movement module includes an X-axis electric slide 12 and a Y-axis electric slide 13. The X-axis electric slide 12 is installed on the base and includes an X-axis guide rail, an X-axis grating scale 121, and an X-axis slider 122. Corresponding threaded holes are provided on the substrate 4. The substrate 4 is fixed to the X-axis guide rail by bolts. The X-axis slider 122 is slidably connected to the X-axis guide rail and is driven by an X-axis sliding drive assembly. The X-axis grating scale 121 is installed on the X-axis guide rail and matches an X-axis grating detection head fixed on the X-axis slider 122.

[0038] The Y-axis electric slide 13 is installed on the X-axis slider 122 of the X-axis electric slide and includes a Y-axis guide rail, a Y-axis grating scale 131, and a Y-axis slider 132. The threaded hole on the X-axis slider 122 is fixed to the Y-axis guide rail of the Y-axis electric slide 13 by bolts. The Y-axis slider 132 is slidably connected to the Y-axis guide rail and is driven by a Y-axis sliding drive assembly. The Y-axis grating scale 131 is installed on the Y-axis guide rail and matches a Y-axis grating detection head fixed on the Y-axis slider 132.

[0039] The laser point positioning component is installed on the Y-axis slider 132 of the Y-axis electric slide 13. During the measurement process, the X-axis electric slide 12 and the Y-axis electric slide 13 control the movement of the laser point positioning component in the X-axis and Y-axis directions respectively through the movement of the X-axis slider 122 and the Y-axis slider 132 above them, so that the laser point positioning component performs precise movement at the sub-micron level on the entire measured plane.

[0040] The X-axis grating scale 121 and the Y-axis grating scale 131 on the two electric slides can read the current X-axis position and Y-axis coordinate position of the deformation detection module, and feed the readings back to the control drive module to achieve the micro-movement of the electric slide, with the minimum single displacement reaching 0.5 μm.

[0041] The X-axis electric slide 12 uses a linear module with the model number OC05-CXN60300-F2PN-G42-MH; the Y-axis electric slide 13 uses a linear module with the model number CXN6050-S. The accuracy of the X-axis grating scale 121 and the Y-axis grating scale 131 is 50 nm, so that the two-axis movement module realizes sub-micron-level displacement control.

[0042] As Figure 2 shown, the laser point positioning component includes a camera support plate 3, a camera 14, an adapter threaded sleeve 1, a small hole height adjustment sleeve 2, a support plate 7, a mounting plate 8, an imaging film 9, a pressing plate 10, and a light-shielding sleeve 11. The support plate 7 includes a horizontal plate and a vertical plate that are fixed together and perpendicular to each other. The horizontal plate of the support plate 7 is connected to the Y-axis slider 132 by threaded screws. The support plate 7 plays a transitional role in the electric slide 13 to ensure that the axis of the camera 14 in the laser point positioning component is perpendicular to the measured surface.

[0043] The vertical plate of the support plate 7 is provided with threaded holes. The camera support plate 3 is provided with waist-shaped adjustment holes. The waist-shaped adjustment holes on the camera support plate 3 are connected to the threaded holes on the vertical plate of the support plate 7 through bolts. The side part of the camera support plate 3 is fixed to the camera 14 by countersunk head screws.

[0044] By using the waist-shaped adjustment holes on the camera support plate 3, the height of the camera support plate 3 can be adjusted, and then the distance between the camera 14 and the measured surface can be adjusted. Before specific detection, first find the best imaging position by adjusting the height of the camera 14, and then fix the height of the camera 14, and ensure that the distance between the camera 14 and the measured surface does not change before and after the interference fit of the measured workpiece.

[0045] The lens at the bottom of the camera 14 is threadedly connected to the adapter threaded sleeve 1. The adapter threaded sleeve 1 is machined with external threads for threadedly connecting with the small hole height adjustment sleeve 2 to achieve an adjustable spacing. By rotating the small hole height adjustment sleeve 2, the height position of the small hole height adjustment sleeve 2 can be adjusted.

[0046] A plurality of threaded holes matching the small hole height adjustment sleeve 2 are provided in the circumferential direction of the adapter threaded sleeve 1. The upper part of the small hole height adjustment sleeve 2 is provided with waist-shaped adjustment holes. After the small hole height adjustment sleeve 2 is adjusted to the required height, the small hole height adjustment sleeve 2 can be locked and fixed to the adapter threaded sleeve 1 through bolts and the waist-shaped adjustment holes to prevent the small hole height adjustment sleeve 2 from shaking caused by the existence of the thread spacing.

[0047] The mounting plate 8 is threadedly connected to the internal thread of the small hole height adjustment sleeve 2 with an adjustable spacing, so as to facilitate the adjustment of the distance between the mounting plate 8 and the camera 14, thereby changing the ring spacing of the small hole diffraction imaging and the size of the small hole. However, it should be noted that the distance between the mounting plate 8 and the camera 14 should be adjusted on the premise of meeting the Fresnel approximation condition.

[0048] An imaging film 9 is fixed to the upper surface of the mounting plate 8 by bolts. An imaging hole for realizing the small hole diffraction phenomenon is opened at the center position of the imaging film 9. A pressing plate 10 is provided above the imaging film 9 for fixing the imaging film to prevent the relative slip and damage between the imaging film and the mounting plate 8. A light-shielding sleeve 11 is provided outside the small hole height adjustment sleeve 2, and the light-shielding sleeve 11 is used to prevent external light from entering the inside of the small hole height adjustment sleeve 2 through the long holes on the small hole height adjustment sleeve 2 and affecting the imaging effect.

[0049] The small hole height adjustment 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 film 9 from undergoing diffuse reflection inside the small hole height adjustment sleeve 2 and thus affecting the imaging effect.

[0050] Embodiment 2 A method for detecting the deformation of interference fit of hole axis based on small hole diffraction, using the device for detecting the deformation of interference fit of hole axis provided in Embodiment 1.

[0051] As Figure 4 shown, the method for detecting the deformation of interference fit of hole axis includes the following steps: S1. Device installation and movement Lift the device above the measured mating hole 15 by a small distance through 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 central axis of the measured mating hole 15, release the U-shaped handle 6, and make the side support feet 5 below the device contact the upper surface of the structure where the measured mating hole 15 is located.

[0052] S2. Setting of the single-mode laser 16, small hole diffraction positioning principle and preliminary positioning.

[0053] Before using the device, first adjust the positions 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 film 9 reaches a preset value, meeting the Fresnel approximation condition, so that the small hole diffraction image is clear and of appropriate size after the laser 16 is positioned. As Figure 5 shown, set the laser 16 on the left side of the measured mating hole 15 and keep it perpendicular to the upper surface of the structure where the measured mating hole 15 is located.

[0054] As Figure 6 shown, since the distance between the imaging film 9 and the camera 14 meets the Fresnel approximation condition. If the laser emitted by the laser is accurately incident vertically into the imaging hole, Fresnel diffraction will occur to form a circular diffraction ring with bright and dark intervals; if the laser fails to be incident into the imaging hole or deviates from the imaging hole within a large range (sub-millimeter level), the diffraction pattern will change significantly (become blurred or even disappear). Through this method, the preliminary positioning of the laser can be achieved.

[0055] Before the interference fit of the hole axis, first adjust the lens position of the camera 14 by a large step with the X-axis electric slide 12 and the Y-axis electric slide 13 until the laser generated by the laser 16 is vertically incident into the imaging hole on the imaging film 9 below the camera 14 to form a small hole diffraction image. At this time, adjust the single-displacement accuracy of the two electric slides to the sub-millimeter level, and move the positions of the camera 14 and the imaging hole to find the position where the small hole imaging is clear until the circular ring spacing of the small hole diffraction imaging image of the laser is appropriate and clearly visible, indicating that the laser generally completely passes through the small hole, and the preliminary positioning is completed, as Figure 7 shown.

[0056] S3. Based on neural network analysis, judge the alignment state between the imaging hole and the laser to complete the precise positioning.

[0057] On the basis of completing the preliminary positioning, control the two electric sliding tables to move 0.5 μm each time in the plane to achieve precise position adjustment, and record the obtained diffraction images after each adjustment. Since the diffraction pattern obtained after the laser source passes through the small hole (as Figure 6 shown) conforms to the Fresnel-Kirchhoff diffraction integral formula, its diffraction result can be calculated by the following formula (1): where, is the light field (intensity and phase) at the observation point P; is the light field at any point Q within 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, with the direction 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; i is the imaginary unit.

[0058] Therefore, when the relative position between the laser source and the small hole changes, the light field , cosine value will change, resulting in corresponding changes in the diffraction pattern. Since it is relatively complex to solve the diffraction result using formula (1), in the case of meeting the Fresnel approximation condition (formula 2), the Fresnel approximation formula (formula 3) is generally used for calculation, as shown below: where, is the distance from the observation plane to the aperture plane; , are the coordinates on the aperture plane; , are the coordinates of the observation plane.

[0059] Therefore, it can be seen from the Fresnel approximation formula that there is a positive 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 position of the laser is a non-linear mapping relationship, a convolutional neural network (CNN) can be used to perform non-linear recognition on the image, and the relationship between the position of the laser and the diffraction pattern can be reflected by the theoretical model shown in formula (4): where is the 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.

[0060] In this embodiment, the laser positioning and recognition model for non-linear recognition adopts the SENet structure. First, the obtained diffraction image is subjected to binarization processing with different thresholds to extract corresponding features, so as to expand the original image into a multi-channel original feature map. Further, the obtained original feature map is compressed into N global features as shown in Equation (5) (in this embodiment, the size of the obtained original feature image is N×H×W, N is the number of channels, and H and W are the number of pixel points in the height and width directions of the image).

[0061] Then, the obtained global features are operated through two fully connected layers. The previous fully connected layer plays a role in dimensionality reduction and adopts the Relu activation function; the second fully connected layer restores the global feature quantity to the initial dimension and adopts the Sigmoid activation function, specifically as shown in Equation (6): where is the global feature obtained by compression; is the output feature of the second fully connected layer; is the original feature map; is the Sigmoid function; is the Relu function.

[0062] Finally, taking the feature as the weight of each channel, multiply it with all elements of the multi-channel original feature map respectively, so as to enhance the key channels and weaken the unimportant channels to obtain the processed result, specifically as shown in Equation (7): where is the new feature graph after processing.

[0063] Input the enhanced feature into multiple cascaded convolutional blocks to extract corresponding image information. Each convolutional block contains a convolutional layer, a batch normalization layer, and a pooling layer. The output feature of the last convolutional block is input to 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.

[0064] Therefore, after obtaining the diffraction pattern at each position and constructing the relationship between the imaging and the laser position through the neural network, the specific position of the laser is reflected through the obtained diffraction pattern, so as to realize the precise positioning of the laser.

[0065] S4. Hole deformation detection Before the interference fit of the hole and the shaft, the positioning of the laser is completed according to steps S2 and S3, and the readings of the X-axis grating scale 121 and the Y-axis grating scale 131 are recorded respectively as the initial light-emitting coordinates (x1, y1); keeping the hole-shaft interference fit deformation detection device stationary, the hole-shaft interference fit is carried out; Due to the deformation caused by the hole-shaft interference after assembly, the position of the laser 16 is offset. Steps S2 and S3 are re-executed to complete the positioning of the laser again, and the position information of the two grating scales at this time is recorded again as the light-emitting coordinates (x'1, y'1) after deformation, and the interference fit deformation amount Δ 总 and its x-axis deformation component Δx and y-axis deformation component Δy are shown in formulas (8) to (10): In some other embodiments, multiple lasers 16 are used. Each laser 16 is respectively installed at different positions on the edge of the measured mating hole 15. During the two rounds of execution of steps S2 and S3, the initial light-emitting coordinates (x i , y i ) corresponding to each laser 16 are detected and recorded, and the light-emitting coordinates (x' i , y' i ) after deformation, i = 1, 2,..., n ; n is the number of lasers 16; for each laser 16, the initial light-emitting coordinates (x i , y i ) and the light-emitting coordinates (x' i , y' i ) after deformation are measured, and the corresponding x-axis deformation component Δx i and y-axis deformation component Δy i are calculated respectively.

[0066] Combining the x-axis deformation components Δx i and the y-axis deformation components Δy i , the interference fit deformation amount is obtained. In this embodiment, the mean value of the x-axis deformation components Δx i is taken as the final x-axis deformation component. The mean value of the y-axis deformation components Δy i is taken as the final y-axis deformation component. According to the final x-axis deformation component and y-axis deformation component, the final interference fit deformation amount is calculated using formula (10).

[0067] This embodiment can effectively detect the deformation of the hole-shaft interference fit, and the detection process is simple. The specific situation after the deformation of the measured mating hole 15 can be quickly obtained, and it can be judged whether the parts obtained by the interference fit are qualified. In some embodiments, when the measured interference fit deformation amount is greater than the error threshold, it is determined that the parts obtained by the interference fit are unqualified.

Claims

1. A method for detecting the deformation of interference fit on the hole axis based on small hole diffraction, characterized in that The method includes: Installing a laser at the edge of the mating hole to be measured; Before the interference fit of the mating hole to be measured, using a laser point positioning component to detect the laser emission position as the initial emission coordinate; After the interference fit of the mating hole to be measured, using a laser point positioning component to detect the laser emission position as the deformed emission coordinate; Judging the deformation amount of the interference fit between the hole and the shaft according to the change of the deformed emission coordinate relative to the initial emission coordinate; When detecting the laser emission position, the laser point positioning component takes the position of the camera when the camera is aligned with the laser emission point as the laser emission position; an imaging sheet with an imaging hole is arranged at an interval outside the lens of the camera; the clarity of the small hole diffraction pattern formed by the laser passing through the imaging hole is used to judge whether the camera is aligned with the laser emission point.

2. The interference fit deformation detection method for hole and shaft according to claim 1, characterized in that: 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.

3. The interference fit deformation detection method for hole and shaft according to claim 1, characterized in that: The process of the laser point positioning component detecting the laser emission position is divided into a preliminary positioning stage and a precise positioning stage; In the preliminary positioning stage, move the position of the camera 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 the small hole diffraction image; continue to move the position of the camera until a circular diffraction ring with bright and dark intervals appears in the small hole diffraction image; In the precise positioning stage, use a laser positioning recognition model to judge whether the precise positioning of the laser emission position is completed currently; if the precise positioning is not completed, reduce the movement amplitude and move the position of the camera step by step; after each step of movement, re-judge whether the precise positioning of the laser emission position is completed currently through 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.

4. The method for detecting the deformation of the interference fit between a hole and a shaft according to claim 3, characterized in that: The laser positioning recognition model performs binaryzation processing on the input diffraction image with different thresholds to obtain a multi-channel original feature map; compresses the multi-channel original feature map into multiple global features; uses two fully connected layers to reduce the dimension and restore the initial dimension of the global features respectively, 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 series of convolutional blocks for feature extraction and then input into the fully connected layer; the fully connected layer outputs the position information of the imaging hole.

5. The method for detecting the deformation of the interference fit between a hole and a shaft according to claim 1, characterized in that: Install multiple lasers at different positions at the edge of the mating hole to be measured; before and after the interference fit of the mating hole to be measured, use a laser point positioning component to detect the laser emission position of each laser respectively.

6. A deformation detection device for interference fit of hole and shaft, characterized in that: For performing the method for detecting the deformation of the interference fit between the hole and the shaft as described in claim 1; the device for detecting the deformation of the interference fit between the hole and the shaft includes a base, a two-axis movement module capable of detecting the moving position installed on the base, and a laser point positioning component installed on the two-axis movement module; the laser point positioning component includes a camera (14), an imaging sheet (9) and a light-shielding sleeve (11); the imaging sheet (9) is arranged at an interval outside the lens of the camera (14); the imaging sheet (9) is provided with an imaging hole aligned with the center position of the lens of the camera (14); the light-shielding sleeve (11) is sleeved at the position between the lens of the camera (14) and the imaging sheet (9).

7. The interference fit deformation detection device for hole and shaft according to claim 6, wherein: The laser point positioning assembly further includes a camera support plate (3) and a support plate (7); the support plate (7) includes a horizontal plate and a vertical plate that are fixed together and perpendicular to each other; the horizontal plate of the support plate (7) is fixed on the Y-axis electric slide table (13); the camera support plate (3) is provided with a waist-shaped adjustment hole; the camera support plate (3) and the vertical plate of the support plate (7) are fixed and the height of the camera support plate (3) is adjusted through bolts and the waist-shaped adjustment hole; the camera with a vertically arranged axis is fixed on the camera support plate (3).

8. The interference fit deformation detection device for hole and shaft according to claim 6, characterized in that: The laser point positioning assembly further includes an adapter threaded sleeve (1), a small hole height adjustment sleeve (2), a mounting plate (8) and a pressing plate (10); the lens of the camera (14) is threadedly connected to the adapter threaded sleeve (1); the adapter threaded sleeve (1) and the small hole height adjustment sleeve (2) are threadedly connected and the relative position is adjusted along the axis; the small hole height adjustment sleeve (2) and the adapter threaded sleeve (1) are locked by bolts; the mounting plate (8) is installed at the outer end of the small hole height adjustment sleeve (2); the imaging film (9) is arranged inside the mounting plate (8) and fixed by the pressing plate (10); the light-shielding sleeve (11) is sleeved outside the adapter threaded sleeve (1).

9. The interference fit deformation detection device for hole and shaft according to claim 6, wherein: The two-axis movement module includes an X-axis electric slide table (12) and a Y-axis electric slide table (13); the X-axis electric slide table (12) is installed on the base; the Y-axis electric slide table (13) is installed on the X-axis electric slide table (12); the laser point positioning assembly is installed on the Y-axis electric slide table (13).

10. The interference fit deformation detection device for hole and shaft according to claim 9, wherein: The X-axis electric slide table (12) includes an X-axis guide rail, an X-axis grating scale (121) and an X-axis slider (122); the X-axis slider (122) is slidably connected to the X-axis guide rail and driven by an X-axis sliding drive assembly; the X-axis grating scale (121) is installed on the X-axis guide rail and matches an X-axis grating detection head fixed on the X-axis slider (122); the Y-axis electric slide table (13) includes a Y-axis guide rail, a Y-axis grating scale (131) and a Y-axis slider (132); the Y-axis slider (132) is slidably connected to the Y-axis guide rail and driven by a Y-axis sliding drive assembly; the Y-axis grating scale (131) is installed on the Y-axis guide rail and matches a Y-axis grating detection head fixed on the Y-axis slider (132).

Images