Method and system for inspecting grooved surface of cylinder bore of crankcase of motor vehicle

Abstract

The invention relates to a method for inspecting a surface of a cylinder bore (14) of a crankcase (12) of a motor vehicle provided with a groove (28), in which method an image (44) reflecting the entire surface of the cylinder bore (14) is detected by means of a detection device, the image (44) is divided into a plurality of sub-images (46) reflecting respective segments of the surface, and the sub-images (46) of the respective segments of the cylinder bore (14) are detected by means of a detection device. A contour feature value (60) characterizing the cross-sectional shape of the groove (28) in the corresponding segment is determined from the pixels of each sub-image (46), a check is made as to whether the contour feature value (60) lies within a predetermined tolerance limit of the contour feature value (60), if the contour feature value (60) lies within the tolerance limit, the checked segment is determined to be qualified, and if the contour feature value (60) lies within the tolerance limit, the checked segment is determined to be qualified. And if the contour characteristic value (60) lies outside the tolerance limit, determining that the inspected segment is unqualified.

Description

Technical Field

[0001] The present invention relates to a method and system for inspecting the grooved surface of the crankcase cylinder bore of a motor vehicle. Background Technology

[0002] DE 102019111947 A1 discloses a method for determining characteristic values ​​of the surface roughness of at least one surface of a component. In this method, a detection dataset is generated based on measurements relating to the surface structure of the component detected by means of a detection device. A modified detection dataset is generated using filtering rules. A summation value is generated from the absolute measurements (especially absolute height values) of the modified detection dataset using summation rules. In this method, a mean rule (especially involving the arithmetic mean) is further applied to the summation value to calculate characteristic values ​​characterizing the surface roughness of the at least one surface of the component. Summary of the Invention

[0003] The objective of this invention is to provide a solution that can reliably identify defects on the machined surfaces of crankcase cylinder bores.

[0004] This task is solved by the technical solution of the independent claim. Other possible designs of the invention are disclosed in the dependent claims, the specification, and the drawings. The features, advantages, and possible designs set forth within the scope of the specification for one of the technical solutions of the independent claim can be at least similarly regarded as the features, advantages, and possible designs of the corresponding technical solutions of other independent claims and any possible combinations of the technical solutions of the independent claims, and, if necessary, combined with one or more dependent claims.

[0005] This invention relates to a method for inspecting the grooved surface of a crankcase cylinder bore in a motor vehicle. The grooved surface of the cylinder bore enables particularly good adhesion of a coating applied to the surface in a later method step. The coated surface of the crankcase cylinder bore provides a cylinder operating surface for the corresponding piston of the internal combustion engine during crankcase operation. Therefore, within the scope of inspection, it is determined whether the surface has a predetermined profile for achieving particularly good coating adhesion or whether the surface profile is within predetermined tolerance limits.

[0006] This method specifies that an image reflecting the entire surface of the cylinder bore is detected by means of a detection device, particularly a camera device. This image can show the surface of the cylinder bore in an unfolded and therefore planar shape. The cylinder bore surface is thus reflected as a two-dimensional image. To record the image, the camera device can, for example, be moved into the cylinder bore along the axial direction, oriented radially outward within its visible range, and rotated 360° around the axial direction of the cylinder bore to record the entire surface of the cylinder bore. The method also specifies that the image is divided into multiple sub-images reflecting corresponding segments of the surface. These corresponding sub-images can, in particular, be of equal size. Each sub-image thus reflects a segment of the cylinder bore surface.

[0007] The method also specifies that contour feature values ​​characterizing the cross-sectional shape of the grooves in the corresponding segment are determined based on the pixels of each sub-image. This means that the pixels of each sub-image are evaluated and contour feature values ​​are generated based on the evaluation. These contour feature values ​​may, for example, characterize the width of the corresponding groove and / or the spacing of the corresponding grooves and / or whether the corresponding grooves are concave and / or the degree of concavity of the corresponding grooves. Furthermore, it is checked whether the contour feature values ​​are within predetermined tolerance limits. Upper and lower tolerance limits can be predetermined. If the contour feature values ​​are within the tolerance limits and therefore lie between or equal to the lower and upper tolerance limits, the segment being inspected is deemed acceptable. If the contour feature values ​​are determined to be outside the tolerance limits and therefore greater than the upper tolerance limit or less than the lower tolerance limit, the segment being inspected is deemed unacceptable. Therefore, within the scope of this method, contour feature values ​​are determined based on pixels, and segment acceptance is determined by comparing these contour feature values ​​with a tolerance range predetermined by tolerance limits. This ensures adequate coating adhesion to the surface, while segment acceptance does not guarantee adequate coating adhesion. Thus, this method allows for seamless inspection of the entire surface of the cylinder bore, i.e., checking whether the corresponding contour of the groove is within a predetermined tolerance range. Furthermore, the described method enables particularly simple and rapid surface inspection.

[0008] In one possible extension of the invention, the opening width of a corresponding groove is determined based on pixels in a sub-image, and the tooth width of the tooth tip surface of a tooth disposed between adjacent grooves is also determined. The contour feature value is determined as the average ratio of the opening width to the tooth width. Therefore, the opening width of a groove is the gap width of the groove in the surface at the tooth tip height. The surface alternately has teeth and grooves along the axial direction. This means that a groove is defined by a corresponding tooth. The tooth tip surface of a corresponding tooth is the surface that projects radially toward the cylinder bore central axis and thus defines the corresponding tooth radially toward the cylinder bore central axis. The tooth width is therefore also measured at the tooth tip height. Therefore, the height of the examined cylinder bore surface along the axial direction and thus along the longitudinal extension direction of the cylinder bore central axis is obtained from the sum of the opening widths of all grooves and the tooth widths of all teeth. Therefore, the opening width of a groove is simultaneously equal to the spacing between the tooth tip surfaces of adjacent teeth defining the groove along the axial direction. The contour feature value thus describes the average ratio of the corresponding opening width of the groove to the corresponding tooth width of the tooth in the observed segment. Contour feature values ​​thus characterize the surface structure in the corresponding segments with particular precision.

[0009] In this context, one extended approach specifies that corresponding pixels in a sub-image are examined row by row, and the row's grayscale value is used to determine whether it represents a groove or a tooth. The corresponding rows extend, in particular, along the circumferential direction of the cylinder bore. Specifically, the corresponding rows extend at least substantially parallel to the longitudinal direction of the tooth or groove. To determine the opening width of a corresponding groove or the tooth width of a corresponding tooth based on the pixels in the sub-image, it is crucial to understand which pixels are assigned to the corresponding tooth and which are assigned to the corresponding groove. To obtain this assignment, pixels in the sub-image are observed row by row. Each observed row is one pixel wide along the axial direction of the cylinder bore. Thus, for each row of pixels, it can be precisely determined whether the pixels in that row are assigned to the tooth tip or the opening of a groove. To perform this assignment, all pixels in the observed row are examined in terms of their grayscale values. Therefore, the grayscale values ​​of all pixels in a row are evaluated to determine whether the row represents the tooth tip or the opening of a groove. Based on the grayscale values ​​of the corresponding pixels in a row, it is possible to determine with particular reliability and precision whether the pixels in that row should be assigned to the opening of a tooth or a groove. By understanding which rows represent the corresponding teeth and which rows represent the openings of the corresponding grooves, the tooth width and opening width can be determined with particular precision.

[0010] In this context, one extended approach specifies that multiple feature values ​​are determined by the grayscale values ​​of a row of pixels, and for each row, a row point representing these feature values ​​is input into a multidimensional coordinate system. The coordinate system has the same number of dimensions as the number of feature values ​​determined for that row. The row point representing the observed row (which is input into the multidimensional coordinate system) thus simultaneously represents all the feature values ​​of that row. The row points of all rows in the observed sub-image are input into this multidimensional coordinate system and subjected to cluster analysis. In this cluster analysis, tooth clusters representing corresponding teeth and groove clusters representing corresponding grooves are identified. The determination is made that all rows whose row points are assigned to tooth clusters represent corresponding teeth, and all rows whose row points are assigned to groove clusters represent corresponding grooves, especially the openings of the corresponding grooves. In this method, each segment is observed separately in terms of whether the corresponding row is assigned to a tooth or a groove. By performing cluster analysis separately on each segment, it is possible to avoid, for example, misclassifying corresponding pixel rows as teeth or grooves due to brightness differences between the different segments being examined. Therefore, the corresponding pixel rows are classified as representing teeth or groove openings with particularly high precision.

[0011] In this context, it can be specifically specified that the gray values ​​used to determine the common row are the average and / or variance of the gray values ​​and / or the skewness and / or the kurtosis and / or the minimum and / or maximum gray values ​​and / or the decimal places of the gray values. For example, a total of 15 feature values ​​can be determined for each row. The more feature values ​​used to evaluate the gray values ​​of a row of pixels, the more accurately the corresponding row points are defined in terms of tooth and groove clusters in the coordinate system. This means that the more feature values ​​used to evaluate the pixels of the corresponding row, the more clearly the tooth and groove clusters are separated from each other in the coordinate system.

[0012] In another embodiment of the invention, the sharpness and / or contrast of a corresponding sub-image are adjusted before evaluating its pixels. Adjusting the sharpness or contrast of the corresponding sub-image allows for sub-image standardization. This, for example, can compensate for lighting differences between different sub-images. Therefore, particularly similar preconditions can be provided for evaluating the corresponding pixels of the sub-images. Consequently, the evaluations of the corresponding sub-images can be compared and thus correlated particularly well.

[0013] In another possible design of the invention, the groove has a laterally concave shape, particularly a dovetail shape, in the profile of a longitudinal section of the cylinder bore wall. This longitudinal section extends in both the axial and radial directions. The groove is created by machining a groove in the cylinder bore surface and shaping the groove. For example, the groove can be milled in the surface of the cylinder bore. The groove can then be shaped, for example, by means of a rolling roller, within the range of a rolling process. The laterally concave shape of the groove is created by shaping the groove. The opening of the corresponding groove therefore has a narrower width than the bottom of the corresponding groove. In other words, the corresponding tooth has a larger axial width at its tooth tip than at its tooth root. Whether the shaping in the corresponding segment is adequate is determined based on the corresponding profile feature value. If the profile feature value is within a predetermined tolerance limit, the shaping is acceptable; if the profile feature value is outside the predetermined tolerance limit, the shaping is unacceptable. When shaping the groove, the axial width of the bottom of the corresponding groove remains unchanged, only the opening width of the corresponding groove is narrowed to form the laterally concave shape. This means that during forming, the corresponding tooth widens axially on its top surface facing the cylinder bore center axis, while the width of the tooth root extending axially remains constant. Therefore, if the axial width of the corresponding groove bottom or the corresponding tooth bottom is known, and the opening width of the corresponding groove or the tooth width is determined by the corresponding pixel according to the sub-pattern, it can be determined whether the tooth is sufficiently formed or whether the groove has a sufficient lateral concavity shape. If the profile feature value is within a predetermined tolerance limit, it is determined that the tooth forming or the lateral concavity shape of the groove is sufficient. The lateral concavity shape of the groove allows the coating subsequently applied to the cylinder bore surface to hook into the groove on the surface, thereby holding the coating particularly firmly on the cylinder bore surface. In particular, the coating fills the lateral concavity shape of the groove and thus acts on the tooth from behind the cylinder bore surface.

[0014] In another possible design of the invention, the segment whose profile feature value is furthest outside the tolerance range from all the inspected segments is selected, and the grooves on the cylinder bore surface are scanned with a laser beam using a laser device, at least in that segment. Here, the cylinder bore surface can be scanned axially with the laser beam, which travels through the selected segment. Therefore, the segment on the cylinder bore surface determined to be most severely deviating from the predetermined tolerance range is subsequently inspected using the laser beam. The profile of the cylinder bore surface can be determined with particularly high precision using a laser beam. However, completely scanning the entire surface of the cylinder bore with a laser beam would take a particularly long time, as the laser beam needs to be guided across the entire surface of the cylinder bore. The described method thus enables a rough pre-inspection of the cylinder bore surface based on the recorded images, and if at least one of the segments is determined to deviate from, especially severely deviating from, the predetermined tolerance range in its profile feature value, then that segment is inspected more precisely, at least by means of a laser device. Therefore, the method enables particularly rapid inspection of the cylinder bore surface and particularly precise re-inspection of potential defects on the cylinder bore surface using a laser device. Therefore, only the surface areas of the cylinder bore surface that are identified as potentially defective or have defects based on images within the pre-inspection range are subject to particularly precise inspection.

[0015] In another possible design of the invention, a display diagram is generated and output by means of an output device, showing the defined contour feature values ​​of all segments and the positions of all segments relative to each other. Thus, in the display diagram, the corresponding contour feature values ​​can be set relative to each other according to the relative positions of the corresponding segments on the cylinder bore surface. This makes it particularly easy to identify which contour feature value is assigned to which segment on the cylinder bore surface. Here, the corresponding contour feature values ​​can be output, for example, in numerical form. Alternatively or additionally, the corresponding contour feature values ​​can be marked with colors, thereby generating a heat map as the display diagram. In this heat map, different colors can be assigned to contour feature values ​​that are different from each other, and the same color can be assigned to contour feature values ​​that are the same. For example, progressively increasing colors can be assigned to correspondingly increasing contour feature values. Therefore, through the color features of the display diagram, a person can particularly easily and quickly view the contour feature values ​​of the corresponding segments, especially the contour feature values ​​of the corresponding areas on the cylinder bore surface. In the display diagram, segments whose defined contour feature values ​​are outside a predetermined tolerance range can be additionally marked with color (e.g., by color selection or the intensity of the corresponding color display). Therefore, through color design, personnel can easily identify which segments within the inspection area are deemed non-conforming and which are deemed conforming in the display diagram. Consequently, personnel can easily determine which area of ​​the cylinder bore surface might contain or has defects. Thus, personnel can, for example, perform additional visual inspection of that area of ​​the cylinder bore surface themselves and thus confirm or deny the actual presence of defects in that area. Therefore, the display diagram assists personnel in re-inspecting the cylinder bore surface, enabling them to complete the re-inspection particularly quickly.

[0016] If a cylinder bore has at least one segment marked as non-conforming or a defect has been identified on the cylinder bore surface by personnel or a laser device, the cylinder bore surface can be reworked or the crankcase with the cylinder bore can be rejected in order to keep the risk of delivering a defective crankcase to the customer particularly low.

[0017] The present invention also relates to a system for inspecting the grooved surface of a cylinder bore in a motor vehicle crankcase. The crankcase is, in particular, part of an internal combustion engine in a motor vehicle. The internal combustion engine of a motor vehicle is configured to drive the motor vehicle by burning fuel. The system includes a detection device configured to detect an image reflecting the entire surface of the cylinder bore. Furthermore, the system includes an electronic computing device configured to divide the image into multiple sub-images reflecting corresponding segments of the surface, determine contour feature values ​​characterizing the cross-sectional shape of the grooves in the corresponding segment based on the pixels of each sub-image, check whether the contour feature values ​​are within predetermined tolerance limits, and if the contour feature values ​​are within the tolerance range, the inspected segment is deemed acceptable; if the contour feature values ​​are outside the tolerance range, the inspected segment is deemed unacceptable. Therefore, the system is configured to perform the method described in conjunction with the method for inspecting the grooved surface of a cylinder bore in a motor vehicle crankcase according to the present invention. The system may additionally include a laser device if necessary.

[0018] Other features of the invention can be derived from the claims, drawings, and description of the drawings. The features and combinations thereof mentioned above in the specification, as well as the features and combinations thereof shown separately in the description of the drawings and / or in the drawings, may be used not only in the given combinations, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0019] The attached image is as follows:

[0020] Figure 1 A schematic diagram of a method for machining grooves in the surface of a crankcase cylinder bore in a motor vehicle is shown.

[0021] Figure 2 A schematic diagram illustrating a method for inspecting defects on the grooved surface of a cylinder bore; and

[0022] Figure 3 A schematic diagram showing the results of inspecting the grooves on the cylinder bore surface.

[0023] In the accompanying drawings, identical and functionally identical elements are given the same reference numerals. Detailed Implementation

[0024] Figure 1A schematic diagram of a method for machining grooves 28 in the surface of a cylinder bore 14 of a motor vehicle crankcase 10 is shown. Within this method, the cylinder bore 14 is machined in the crankcase 10 using a cutting tool 12. Subsequently, a corresponding groove 18 is machined in the wall defining the cylinder bore 14 of the crankcase 10 using a milling tool 16. This corresponding groove 18 extends circumferentially around the central axis 20 of the cylinder bore 14. The groove 18 thus extends in its longitudinal direction in the circumferential direction of the cylinder bore 14. Adjacent corresponding grooves 18 are separated from each other by tooth root bodies 22 disposed therebetween in the axial direction.

[0025] Next, the rolling tool 24 is inserted into the cylinder bore 14 and, with the aid of the rolling tool 24, the tooth root 22 is shaped into the corresponding tooth 26. By shaping the tooth root 22 into the tooth 26, the groove 18 is shaped into a groove 28 with side recesses. The groove 28 can have a dovetail profile in particular in the cross-section extending in the axial direction of the cylinder bore 14. Here, the groove bottom 30 of the corresponding groove 28 corresponds in its axial direction width to the axial direction width of the corresponding groove 18 shaped into the groove 28. The axial direction is consistent with the extension direction of the central axis 20 of the cylinder bore 14. The width 32 of the corresponding groove 18 corresponds to the spacing between the corresponding tooth root 22s that are adjacent to each other and define the groove 18 on opposite sides in the axial direction. The width of the tooth root 34 of the corresponding tooth 26 in the axial direction corresponds to the width 36 of the tooth root 22 in the axial direction. By shaping the corresponding tooth root 22 into corresponding teeth 26, these teeth 26 have a tooth width 40 on their tooth tip surface 38 that is larger than the axial width 36 of the corresponding tooth root 22. Therefore, in the tooth tip surface 38 region, the corresponding teeth 26 become wider axially compared to the corresponding tooth root 22 through shaping, especially rolling. Consequently, the axial opening width 42 of the corresponding groove 28 is narrower than the width 32 of the groove 18. If the corresponding widths 32 and 36 of the groove 18 and the tooth root 22 are known, the degree of shaping of the corresponding tooth root 22 into teeth 26 can be determined based on the corresponding, defined tooth width 40 and opening width 42. Therefore, the shaping strength can be determined.

[0026] The groove 28 with side recesses is formed so that the coating subsequently applied to the surface of the cylinder bore 14 can adhere particularly well to the surface of the cylinder bore 14, especially by embedding in the corresponding side recesses of the groove 28. If the side recesses of the groove 28 are not adequately formed, the coating may peel off. Therefore, it is desirable to identify and screen out the corresponding cylinder bores with areas where the tooth root body 22 is not adequately formed into the tooth 26 before coating, or to re-machine them.

[0027] Figure 2 A schematic diagram illustrating a method for inspecting the grooved surface of the cylinder bore 14 of a motor vehicle crankcase 10.

[0028] This method specifies that image 44, reflecting the entire surface of cylinder bore 14, is detected by means of a detection device, particularly a camera device. Figure 2 The surface of the cylinder bore 14, unfolded around the central axis 20, is shown in two dimensions. Image 44 is divided into multiple sub-images 46 reflecting corresponding segments of the surface. For clarity, in Figure 2 Only some sub-images 46 are provided with their respective reference numerals. Each sub-image 46 reflects multiple grooves 28 and teeth 26. Within the scope of this method, it is now specified that contour feature values ​​60 characterizing the cross-sectional shape of the grooves 28 in the corresponding segment are determined based on the pixels of each sub-image 46.

[0029] To determine the contour feature value 60 of the corresponding segment based on the pixels of the corresponding sub-image 46, the following operations are performed. In each sub-image 46, pixels are examined row by row, with the corresponding row extending along the circumferential direction of the cylinder bore 14. Each row examined is currently one pixel wide, with the width of the corresponding row extending along the axial direction of the cylinder bore 14. Based on the corresponding grayscale value of a row of pixels, it is determined whether the row represents the opening of the groove 28 or the tooth tip surface 38 of the tooth 26. Multiple statistical feature values ​​are determined from the grayscale values ​​of the corresponding pixels in a row. Currently, in particular, 15 statistical feature values ​​are determined for the grayscale values ​​of each row of pixels. Subsequently, for each row, a row point 50 representing all statistical feature values ​​is input into a multidimensional coordinate system 48. The multidimensional coordinate system 48 currently includes 15 dimensions and therefore has one dimension for each calculated feature value. The row point 50 of each examined row of the examined sub-image 46 is input into the common coordinate system 48. Cluster analysis of the row points 50 is then performed. Therefore, based on the corresponding positions of row points 50 in coordinate system 48, two clusters are determined: tooth cluster 52 and groove cluster 54. It is determined that all rows of tooth cluster 52 with row points 50 assigned to it represent the corresponding teeth 26 (especially the corresponding tooth tip surface 38 of teeth 26), and all rows of groove cluster 54 with row points 50 assigned to it represent the corresponding grooves 28, especially the corresponding openings of grooves 28.

[0030] As feature values, in particular, the mean and / or variance and / or skewness and / or kurtosis and / or minimum and / or maximum and / or decimal places of the pixel grayscale values ​​of the observed row can be determined. To achieve reproducible conditions for evaluating all sub-images 46, it can be specified that sharpness and / or contrast adjustments are made to the respective examined sub-image 46 before evaluating the pixels of that sub-image 46. Here, sharpness and / or contrast adjustments can be made to the entire image 44 or to the respective sub-images 46 independently of each other.

[0031] Based on the information that the corresponding row represents either the tooth tip surface 38 of tooth 26 or the opening of groove 28, the opening width 42 of the corresponding groove 28 and the corresponding tooth width 40 of the corresponding tooth tip surface 38 of tooth 26 can be determined from the pixels. The average ratio of the corresponding opening width 42 to the corresponding tooth width 40 can determine the contour feature value 60, and thus infer the contour 56 and, in particular, the degree of deformation in the corresponding segment represented by the observed sub-image 46. The contour feature value 60 thus describes the average degree of deformation in the corresponding segment observed with the aid of the corresponding sub-image 46. Based on the corresponding contour feature value 60 of the segment, it can be determined whether the forming in the corresponding segment is sufficient. If the contour feature value 60 is within a predetermined tolerance limit, the forming is deemed acceptable; and if the contour feature value 60 is outside the predetermined tolerance limit, the forming is deemed unacceptable. Therefore, if the contour feature value 60 is within the predetermined tolerance limit, the inspected segment is deemed acceptable; and if the contour feature value 60 is outside the predetermined tolerance limit, the inspected segment is deemed unacceptable. As a lower tolerance limit, it can be specified that the ratio of the opening width 42 to the tooth width 40 should be 52:48. As an upper tolerance limit, it can be specified that the ratio of the opening width 42 to the tooth width 40 should be 28:72. When the tooth root body 22 is not deformed, the ratio of the opening width 42 to the tooth width 40 is currently 60:40.

[0032] exist Figure 3 Display Figure 58 is shown, created based on contour feature values ​​60 determined for corresponding segments, and output by means of an output device. The contour feature values ​​60 corresponding to the corresponding segments are arranged relative to each other in Display Figure 58 according to the relative arrangement of the segments on the surface of the cylinder bore 14. Therefore, it is particularly easy to identify which segment on the surface of the cylinder bore 14 has which contour feature value 60 by means of Display Figure 58. Furthermore, in Display Figure 58, corresponding contour feature values ​​60 outside a predetermined tolerance range can be highlighted by selecting the brightness of the area representing the corresponding segment and / or the color of these areas relative to the corresponding areas whose corresponding contour feature values ​​are within the predetermined tolerance range. Figure 3 In Figure 58, the regions corresponding to segments whose defined profile feature value 60 is outside the predetermined tolerance limit are shown in a darker color than the regions corresponding to segments whose defined profile feature value 60 is within the predetermined tolerance limit. Therefore, in Figure 3 As shown in Figure 58, the corresponding segment can be identified as qualified or unqualified very quickly based on the coloring or brightness of the area.

[0033] If at least one segment of the cylinder bore 14 surface is determined to be non-conforming, the segment can be scanned using a laser beam provided by a laser device, thereby allowing for a more precise inspection. If multiple segments are determined to be non-conforming because the corresponding determined profile feature value 60 is outside a predetermined tolerance range, the segment with the furthest profile feature value 60 outside the tolerance range can be selected from all segments, and the groove 28 on the cylinder bore 14 surface can be scanned using a laser beam at least in that segment. Thus, re-evaluation is performed at the most critical locations on the cylinder bore 14 surface using a laser device.

[0034] The evaluation of sub-image 46 and the determination of contour feature values ​​60 for each segment represented by the corresponding sub-image 46 can be performed, in particular, by means of artificial intelligence, especially artificial neural networks.

[0035] The described method for inspecting the surface of cylinder bore 14 enables complete inspection and evaluation of the surface of cylinder bore 14 and visual display of corresponding deviations in the surface profile of cylinder bore 14.

[0036] The described method relates to an auxiliary function for visualizing key surface areas on the rolled cylinder bore 14.

[0037] List of reference numerals

[0038] 10 crankcase

[0039] 12 Cutting Tools

[0040] 14-cylinder bore

[0041] 16 Milling Tools

[0042] 18 grooves

[0043] 20 central axis

[0044] 22 tooth root body

[0045] 24 Roller Tools

[0046] 26 teeth

[0047] 28 grooves

[0048] 30 groove bottom

[0049] 32 groove width

[0050] 34 tooth root width

[0051] 36 tooth root width

[0052] 38 tooth top surface

[0053] 40 tooth width

[0054] 42 opening width

[0055] 44 images

[0056] 46 sub-images

[0057] 48 coordinate system

[0058] 50 line points

[0059] 52-tooth cluster

[0060] 54 grooved clusters

[0061] 56 outlines

[0062] 58 Display Chart

[0063] 60 contour feature values

Claims

1. A method for inspecting the grooved (28) surface of the cylinder bore (14) of a motor vehicle crankcase (12), wherein, - An image (44) reflecting the entire surface of the cylinder bore (14) is detected by means of a detection device. - Divide the image (44) into multiple sub-images (46) that reflect the corresponding segments of the surface. - Determine the contour feature value (60) representing the cross-sectional shape of the groove (28) in the corresponding segment based on the pixels of each sub-image (46). - Check whether the profile feature value (60) is within the predetermined tolerance limit of the profile feature value (60). - If the profile feature value (60) is within the tolerance limit, the inspected segment is deemed to be qualified, and if the profile feature value (60) is outside the tolerance limit, the inspected segment is deemed to be unqualified.

2. The method according to claim 1, characterized in that, The opening width (42) of the corresponding groove (28) is determined based on the pixels in the sub-image (46), the tooth width (40) of the tooth top surface (38) of the corresponding tooth (26) set between adjacent grooves (28) is determined, and the contour feature value (60) is the average ratio of the opening width (42) to the tooth width (40).

3. The method according to claim 2, characterized in that, The corresponding pixels in the sub-image (46) are examined line by line, and it is determined whether the corresponding row reflects a groove (28) or a tooth (26) based on the corresponding gray value of the pixel in the row.

4. The method according to claim 3, characterized in that, Multiple feature values ​​are determined by the gray values ​​of the corresponding pixels in a row. For each row, a row point (50) representing these feature values ​​is input into a multidimensional coordinate system (48). The row points (50) of all rows of the sub-image (46) are clustered in the coordinate system (48) to determine the tooth cluster (52) and the groove cluster (54) and to determine that: all rows whose row points (50) are assigned to the tooth cluster (52) represent the corresponding tooth (26) and all rows whose row points (50) are assigned to the groove cluster (54) represent the corresponding groove (28).

5. The method according to claim 4, characterized in that, As an eigenvalue, it determines multiple of the following: - Average value; - Variance; - Distribution skewness; - Kurtosis; - Minimum value; - Maximum value; - Tenths place value.

6. The method according to any one of the preceding claims, characterized in that, Before evaluating the pixels of the corresponding sub-image (46), adjust the sharpness and / or contrast of the corresponding sub-image (46).

7. The method according to any one of the preceding claims, characterized in that, The groove (28) has a concave shape and is formed by machining a groove (18) in the surface and shaping the groove (18), and determining whether the shaping in the corresponding segment is sufficient according to the corresponding profile feature value (60). If the profile feature value (60) is within the tolerance limit, the shaping is qualified, and if the profile feature value (60) is outside the tolerance limit, the shaping is unqualified.

8. The method according to any one of the preceding claims, characterized in that, Select the segment whose profile feature value (60) is furthest outside the tolerance range from all segments and scan the groove (28) on the surface of the cylinder bore (14) with a laser beam using a laser device at least in that segment.

9. The method according to any one of the preceding claims, characterized in that, A display diagram (58) is generated and output by means of an output device, which shows the determined contour feature values ​​(60) of all segments and the positions of all segments relative to each other.

10. A system for inspecting the grooved (28) surface of the cylinder bore (14) of a motor vehicle crankcase (12), the system comprising: - A detection device configured to detect an image (44) reflecting the entire surface of the cylinder bore (14), and - Electronic computing devices, which are configured for - Divide the image (44) into multiple sub-images (46) that reflect the corresponding segments of the surface. - Determine the contour feature value (60) representing the cross-sectional shape of the groove (28) in the corresponding segment based on the pixels of each sub-image (46). - Check whether the profile feature value (60) is within the predetermined tolerance limit of the profile feature value (60). - If the profile feature value (60) is within the tolerance range, the inspected segment is deemed to be qualified; if the profile feature value (60) is outside the tolerance range, the inspected segment is deemed to be unqualified.

Images