Device for surface inspection and plant for the production of machine elements

Abstract

The invention relates to a device (100) for surface testing of machine elements (1), comprising: - at least one lighting device (10) for illuminating a surface (2) of at least one machine element (1), wherein the at least one lighting device (10) is configured to illuminate the surface (2) of the at least one machine element (1) simultaneously with light from at least three separate wavelength ranges, - at least one detection device (20) for detecting the surface (2) of the at least one machine element (1), wherein the at least one detection device (20) is configured to detect at least one image of the surface (2) of the at least one machine element (1), wherein the at least one image depicts a separate reflection from the surface (2) of the at least one machine element (1) in each of the at least three separate wavelength ranges, - at least one evaluation device (60) for evaluating the at least one image, wherein the at least one evaluation device (60) is configured to determine at least one test information of the captured surface (2) from the at least one image, and a plant (200) for the manufacture of machine elements (1).

Description

[0001] The invention relates to a device for surface testing and a system for the manufacture of machine elements.

[0002] Machine elements, such as ball hubs for vehicles, are routinely inspected for surface defects in industrial manufacturing to meet high surface quality requirements. Optical surface inspection can be performed, for example, using cameras.

[0003] A method for bearing quality detection based on machine image processing is known from CN 1 12 308 832 B.

[0004] However, the known methods are slow, as they require, for example, multiple scans. Furthermore, surface inspection cannot distinguish between surface defects and superficial contamination, leading to unnecessary scrapping of machine components. The known methods are therefore inefficient.

[0005] The technical problem is to create a device for surface inspection and a system for manufacturing machine elements that can improve the efficiency of surface inspection and shorten inspection time.

[0006] The solution to the technical problem is provided by the articles with the features of the independent claims. Further advantageous embodiments of the invention are described in the dependent claims.

[0007] A device for surface testing of machine elements is proposed, comprising: - at least one lighting device for illuminating a surface of at least one machine element, wherein the at least one lighting device is designed to illuminate the surface of the at least one machine element simultaneously with light from at least three separate wavelength ranges, - at least one detection device for detecting the surface of the at least one machine element, wherein the at least one detection device is configured to detect at least one image of the surface of the at least one machine element, wherein the at least one image depicts a separate reflection from the surface of the at least one machine element in each of the at least three separate wavelength ranges, - at least one evaluation device for evaluating the at least one image, wherein the at least one evaluation device is designed to determine at least one test information of the captured surface from the at least one image.

[0008] A further proposal is a plant for the production of machine elements, comprising at least one device according to an embodiment described in this disclosure. The plant is particularly designed to produce at least 50,000 machine elements per day using the at least one device.

[0009] The technical effects and advantages mentioned in this disclosure for the device naturally also extend to the plant and vice versa.

[0010] The device has the technical advantage that the test information can be determined from a single image. This is achieved by simultaneously illuminating the surface of the machine element to be tested with light from at least three separate wavelength ranges, so that at least three different reflections of the surface are available for evaluation in the captured image. This increases the quality of the test information. At the same time, the device reduces the time required for surface testing, as multiple images do not need to be captured. The device thus improves the efficiency of surface testing.

[0011] The machine element to be tested could be, for example, a ball hub. Alternatively, the machine element could be, for example, a shaft, a ball bearing, a gear, or a piston. The machine element is, in particular, a component that must meet high surface quality requirements.

[0012] The surface of the machine element to be inspected can be, for example, part of a cylindrical surface or the cylindrical surface of the machine element itself. Alternatively, or in combination, the surface to be inspected can be part of a cover surface or the cover surface of the machine element.

[0013] The lighting device can have one or more lighting elements. The lighting element can, for example, be an LED. The light produced by the lighting device is, in particular, visible light. The lighting device can, for example, be designed to produce monochromatic light in each of the three wavelength ranges, e.g., red, green, and blue light. The fact that the wavelength ranges are separate means, in particular, that the wavelength ranges of the light are disjoint from one another. Specifically, the wavelength ranges do not border each other. A first wavelength range can, for example, comprise wavelengths in the range of 650 nm to 750 nm. The first wavelength range can therefore be referred to as the red wavelength range. A second wavelength range can, for example, comprise wavelengths in the range of 490 nm to 575 nm.The second wavelength range can therefore be called the green wavelength range. A third wavelength range can, for example, include wavelengths in the range of 420 nm to 480 nm. The third wavelength range can therefore be called the blue wavelength range.

[0014] The detection device can have one or more image sensors. The light detected by the detection device is, in particular, visible light. Conventional image sensors, such as CCD sensors and / or active pixel sensors, can be used in this way. Pixels of the image sensor can, for example, be arranged in a Bayer matrix. The detection device can therefore also be referred to as a matrix camera. The detection device is specifically designed to simultaneously detect the separate reflections of the surface in each of the at least three wavelength ranges. The detection device can have at least one separate sensor channel for detection in each of the at least three separate wavelength ranges. Alternatively, the detection device can have a separate image sensor for each of the at least three wavelength ranges, with the respective reflections being, for example,The light can be deflected onto the respective image sensor using a dichroic prism and / or the respective reflections can be filtered using a filter. In this way, for example, the image resolution can be increased, since a separate image sensor is available for each wavelength range. Naturally, the detection device can incorporate such a dichroic prism and / or filter.

[0015] The image is, in particular, a two-dimensional image of the surface of the machine element to be inspected. The image is, for example, an RGB image. Each imaged reflection is, in particular, assigned to one of the detected wavelength ranges of light. The image can include at least one intensity value in each of the at least three imaged reflections. Each intensity value is, in particular, assigned to one of the detected wavelength ranges of light. The image comprises, in particular, a plurality of pixels. In particular, at least three separate intensity values ​​are assigned to each pixel of the image. Each pixel can, for example, represent a point on the surface of the machine element. The resolution of the image can, for example, have a value in the range of 1 megapixel to 50 megapixels. With the aid of the device, surface defects with a size of, for example, 10 µm and larger can be detected. The image comprises, in particular, at least three parts.For example, a first part depicts the reflection in the first wavelength range. This first part can be referred to as the red part. A second part depicts the reflection in the second wavelength range. This second part can be referred to as the green part. A third part depicts the reflection in the third wavelength range. This third part can be referred to as the blue part. The reflections depicted in the image all relate to a common point in time.

[0016] The evaluation unit can be designed as a microcontroller or incorporate one. The at least three reflections, in particular the previously mentioned intensity values, can be evaluated using the evaluation unit. The evaluation unit is specifically designed to perform a so-called shape-from-shading method. Using the shape-from-shading method, the reflections depicted in the image, especially the intensity values, can be evaluated to determine the test information. This is because the reflections depicted in the image can represent a shading of the machine element's surface under the influence of the illumination, from which a shape of the surface can be determined as test information.

[0017] The specific test information can include one or more surface inclination vectors. The inclination vector can, for example, be a normal vector orthogonal to the surface with three directional components at a point on the surface of the machine element.

[0018] The inclination vector can represent the shape of the surface at a given point. To determine the inspection information, a system of differential equations can be evaluated according to the Lambert-Beer law. For example, the at least three intensity values ​​for a point on the surface can be an input (shading), and the three directional components of the inclination vector can be an output (shading) for that point. In particular, starting from the at least three reflections, an orthogonal inclination vector can be determined for each point on the surface of the at least one machine element. The inspection information can therefore also be referred to as an inclination map. The inspection information can be visualized as a so-called P-image, Q-image, and / or albedo image. In this way, for example,a person can gain a visual overview of the specific test information and thus visually assess the surface quality of the machine element.

[0019] In particular, the evaluation unit can be configured to execute a machine learning process. The machine learning process serves, for example, to determine the inspection information. The machine learning process can, for example, include training an artificial neural network. The machine learning process can be trained, for example, using a large number of pre-existing images—i.e., images of machine elements as defined in this disclosure, which are provided for training—as well as pre-existing inspection information assigned to each image. In particular, between 1,000 and 1,000,000 pre-existing images of machine elements can be provided as training data, with corresponding inspection information serving as the underlying truths. After training, inspection information can be determined for an image acquired by the acquisition device using the machine learning process.The determination of the test information is thus accelerated by the machine learning process.

[0020] In particular, the evaluation unit can be configured to evaluate a release criterion for the at least one machine element based on at least one specific test piece of information. For example, the release criterion can be met if, based on the test information, a surface finish value exceeds a known threshold. Methods for determining the surface finish value based on the test information, e.g., based on the surface's slope vectors, are known to those skilled in the art. The evaluation unit can, in particular, generate at least one control command when the release criterion is met, wherein the at least one control command releases the at least one machine element for further production. Release can, for example, be effected by controlling a release actuator of a production line using the at least one control command. The device can, of course, include such a release actuator.If, however, the specific test information does not meet the release criterion, the machine element cannot be released and at least one machine element can be further processed as scrap, for example.

[0021] In one embodiment, the inspection information includes whether the surface has one or more depressions and / or one or more protrusions. This allows the inspection information to differentiate between harmful surface defects and surface contamination, thus reducing defective scrap (also known as pseudo-rejects) in production. A depression can represent a surface defect, and a protrusion can represent contamination. In particular, the evaluation device can be configured to determine depressions and / or protrusions of the surface using the previously described shape-from-shading method. A depression or protrusion of the surface can be determined as a function of a plurality of inclination vectors, for example, using the evaluation device.In particular, a surface can have a depression if adjacent inclination vectors are inclined towards each other, e.g., because the surface appears convex at the point of the depression. Furthermore, in particular, a surface can have a protrusion if adjacent inclination vectors are inclined away from each other, e.g., because the surface appears convex at the point of the depression.

[0022] In one embodiment, the at least one lighting device has at least one ring-shaped lighting element to illuminate the surface of the at least one machine element over an angular range of 0° to 360°. In this way, the surface of the machine element can be illuminated all around, for example. This allows, for instance, the illumination of the entire lateral surface of the machine element. In other words, the angular range forms a circle in which the machine element can be positioned to be illuminated. The angular range can therefore also be referred to as the illumination area. The angular range can, for example, be oriented in a horizontal plane of the device. Alternatively, the angular range can also be oriented in a plane rotated relative to the horizontal plane. The at least one ring-shaped lighting element can, for example, be configured as an LED ring or LED strip.Of course, the lighting element does not necessarily have to be a circular ring to illuminate the machine element over the angular range of 0° to 360°, but can, for example, have straight segments.

[0023] In one embodiment, the at least one illumination device is configured to illuminate the surface of the at least one machine element from a separate direction in each of the at least three separate wavelength ranges. This results in more diverse surface reflections, which in turn simplifies image evaluation and thus improves the quality of the test information. In other words, the at least one illumination device is configured to illuminate the surface of the at least one machine element from a different angle in each of the at least three wavelength ranges. A first illumination element can emit light at a first angle – for example, in a horizontal direction. A second illumination element can emit light at a second angle – for example, at an angle inclined at +45° to the horizontal direction.A third lighting element can emit light at a third lighting angle - e.g. in a direction inclined at -45° to the horizontal direction.

[0024] In one embodiment, the device further comprises at least one mirror assembly, wherein the at least one mirror assembly is configured to reflect reflections from the surface of the at least one machine element over an angular range of 0° to 360° onto the at least one detection device. In this way, the surface of the machine element can be reflected all around. This makes it possible, for example, to depict the reflections of the entire lateral surface of the machine element in the image. The angular range of the mirror assembly can be oriented in a plane that is parallel to the horizontal plane of the previously described angular range of the illumination device. The at least one mirror assembly is, for example, arranged between the at least one illumination device and the at least one detection device.The at least one mirror arrangement comprises, in particular, a first part and at least one further part. With the aid of the first part, reflections from the surface of the machine element can be deflected onto the second part and reflected from the second part onto the detection device. In this way, the detection device can, for example, be arranged concentrically to the lighting device. The mirror arrangement, in particular the first part of the mirror arrangement, can, for example, be ring-shaped. The mirror arrangement, in particular the second part of the mirror arrangement, can, for example, be conical or spherical.

[0025] In one embodiment, the at least one mirror assembly has several planar segments, each planar segment being oriented such that it reflects a geometric segment of the surface of the at least one machine element. In this way, the detection device can be aligned with the geometric segments of the machine element using the planar segments of the mirror assembly. Furthermore, because the segments of the mirror assembly are planar, distortions of the reflection due to, for example, curved reflection do not need to be taken into account in the evaluation of the image. Moreover, the planar segments can be manufactured particularly easily. For example, the machine element can be a ball hub with six grooves and six teeth along a circumference, the six grooves and the six teeth forming the geometric segments of the surface.The reflections of these twelve geometric segments can each be reflected onto the detection device by a flat segment of the mirror device.

[0026] In one embodiment, the at least one detection device has at least one lens with a variable focal length. This allows the focal length of the detection device to be readjusted during operation. In particular, the focal length can be varied during surface inspection, enabling the surface to be inspected, for example, at varying depths, especially along a bore of the machine element. The lens can, for example, be a liquid lens. Liquid lenses are characterized by a particularly short reaction time, for example, between 0.1 milliseconds and 1.0 milliseconds, for varying the focal length.

[0027] In one embodiment, the device further comprises at least one positioning device, wherein the device is configured to inspect the surface of the at least one machine element, and simultaneously, at least one further machine element is positioned for surface inspection using the at least one positioning device. In this way, the time required for illuminating the surface and capturing and evaluating the image can be used to move another machine element into an inspection position for surface inspection. If the machine element has, for example, the geometric segments described above, the machine element can be positioned relative to the planar segments of the mirror device using the positioning device. This position of the machine element can also be referred to as the inspection position. The positioning device can, for example, include an electric motor to move the machine element.to rotate and position in the test position.

[0028] In one embodiment, the at least one lighting device has at least one diffuser. This allows the light generated by the lighting device to be converted into diffuse illumination, thus illuminating the surface evenly. If the lighting device has, for example, several LEDs, the light from the multiple LEDs can be diffused by means of the diffuser. This prevents the multiple LEDs from appearing as point-like spots of light in the image. The at least one diffuser can, in particular, be arranged in front of the at least one ring-shaped lighting element.

[0029] The device is specifically designed to inspect the surface of at least 50,000 machine elements per day. In other words, the device is specifically designed to perform the surface inspection in a time of no more than 1.728 seconds. The device is specifically designed to perform the surface inspection in a time of no more than 500 milliseconds. The remaining time can then be used, for example, to position the machine element in the device. These short surface inspection times can be achieved by the features of the device described in this disclosure.

[0030] The invention is explained in more detail using exemplary embodiments. The figures show: Fig. 1 a schematic cross-sectional representation of an embodiment of a device for surface testing, Fig. 2 a schematic representation of a depression on the surface of a machine element, Fig. 3 a schematic representation of a raised surface of a machine element and Fig. 4 a schematic representation of an embodiment of a plant for the manufacture of machine elements.

[0031] In the following, identical reference symbols denote elements with the same technical characteristics.

[0032] Fig. Figure 1 shows a schematic cross-sectional representation of an embodiment of a device 100 for surface inspection of a machine element 1. The machine element 1 is, for example, a ball hub. A surface 2 of the machine element 1 to be inspected can, for example, be a cylindrical surface of the ball hub.

[0033] The illustrated embodiment of the device 100 is rotationally symmetrical about a vertical axis 101, so that the device 100 can inspect the surface of the machine element 1 from all sides of its cylindrical surface. For this purpose, the device 100 comprises several components, which are explained below.

[0034] The device 100 comprises a lighting device 10 for 360° illumination of the surface 2 of the machine element 1. The lighting device 10 is designed to illuminate the surface 2 of the machine element 1 simultaneously with light from three separate wavelength ranges. The light of a first wavelength range is red, the light of a second wavelength range is green, and the light of a third wavelength range is blue.

[0035] The lighting device 10 has three ring-shaped lighting elements 11, 12, 13 for 360° illumination. The lighting elements 11, 12, 13 illuminate the surface 2 of the machine element 1 over an angular range of 0° to 360°. The lighting elements 11, 12, 13 can, for example, be designed as LED rings. The first lighting element 11 illuminates the surface 2 with the previously described red light. The second lighting element 12 illuminates the surface 2 with the previously described green light. The third lighting element 13 illuminates the surface 2 with the previously described blue light. The first lighting element 11, which emits the red light and thus the warmest light, is positioned above the second and third lighting elements 12, 13 in order to protect the second and third lighting elements 12, 13 from heat emitted by the first lighting element 11.

[0036] A diffuser 16 is arranged in front of each of the lighting elements 11, 12, 13, which diffuses the respective light. This allows each lighting element 11, 12, 13 to have several LEDs without them being perceived as point light sources.

[0037] The lighting elements 11, 12, 13 are arranged such that the surface 2 of the machine element 1 is illuminated from a different direction in each of the at least three separate wavelength ranges. For this purpose, the lighting elements 11, 12, 13 illuminate the surface of the machine element 1 from a separate angle. The light emitted from different directions by the lighting elements 11, 12, 13 and the associated reflections are shown in Fig. Figure 1 schematically represents the left side of the device 100 by lines. Due to the illumination in separate directions, depressions or protrusions on the surface 2 of the machine element 1 are illuminated at the three different illumination angles and cast, for example, a different shadow in each of the three wavelength ranges.

[0038] To position the machine element 1 in an illumination area 15 of the lighting device 10, the device 100 can include, for example, a pneumatically designed actuator 50. A pneumatic actuator 50 acts particularly quickly. The actuator 50 can, for example, be designed as a plunger that lifts the machine element 1 from a production conveyor belt (not shown) into the illumination area 15 and lowers it again after surface inspection. Fig. 1 indicated by a double arrow).

[0039] The lighting device 10 can also be designed to be removable. This allows the lighting elements 11, 12, 13 to be replaced in a disassembled state. In this way, for example, the calibration of the non-disassembled components of the device 100 is not jeopardized by the replacement of the lighting elements 11, 12, 13.

[0040] The device 100 further comprises a mirror assembly 30. The mirror assembly 30 is designed to reflect reflections from the surface 2 of the machine element 1, resulting from illumination, over an angular range of 0° to 360° onto a detection device 20. For this purpose, the mirror assembly 30 has a first annular part 31 and a second conical part 32. The first part 31 directs the reflections onto the second part 32, from which the reflections are reflected onto an image sensor 21 of the detection device 20. The second part 32 of the mirror assembly 30 can, for example, be placed on a glass plate (not shown).

[0041] In particular, the first part 31 and the second part 32 of the mirror device 30 can have several planar segments, each planar segment being oriented such that it reflects a geometric segment of the surface 2 of the machine element 1. A geometric segment of the surface 2 can, for example, be a tooth or a groove (not shown) of the machine element 1. In this way, the detection device 20 can, for example, more easily focus the geometric segments of the machine element 1.

[0042] The device 100 comprises the aforementioned detection device 20. The detection device 20 is configured to detect at least one image (not shown) of the surface 2 of the machine element 1. The image represents the reflections from the surface 2 of the machine element 1 in each of the at least three separate wavelength ranges. For this purpose, pixels of the image sensor 21, designed as a CCD sensor, are arranged in a Bayer matrix, wherein a first proportion of the pixels detects the reflection of red light, a second proportion of the pixels the reflection of green light, and a third proportion of the pixels the reflection of blue light.

[0043] The detection device 20 further comprises a lens 22 designed as a liquid lens with a variable focal length. This allows the focal length to be quickly readjusted during operation, for example, or varied depending on the properties of a geometric segment of the machine element 1. The detection device 20 also includes a lens 23, which is arranged in front of the lens 22.

[0044] The device 100 also includes an evaluation unit 60 designed as a microcontroller for evaluating the image. The evaluation unit 60 is configured to determine at least one test piece of information from the image of the captured surface 2.

[0045] Fig. Figure 2 shows a schematic representation of a depression V of a surface 2 of a machine element 1 in a cross-sectional view.

[0046] Fig. 3 shows, in contrast to Fig. 2 a schematic representation of a protrusion E of a surface 2 of a machine element 1 in a cross-sectional view.

[0047] The device 100 (see Fig. 1) Certain test information may include inclination vectors N, which represent normal vectors for various points on the surface 2 of the machine element 1. In Fig. 2 and Fig. For clarity, only one of the inclination vectors N is indicated by a reference symbol in section 3. For easier understanding, in Fig. 2 and Fig. Figure 3 also shows a Cartesian coordinate system with a horizontal axis X and a vertical axis Y. The inclination vectors N thus each have an X-direction component and a Y-direction component. Of course, the inclination vectors can also have a third directional component (e.g., a Z-direction component).

[0048] A positive x-direction component indicates that the slope vector N is inclined to the right. Conversely, a negative x-direction component indicates that the slope vector N is inclined to the left. If the slope vector N has no x-direction component, then the slope vector N is vertical. Fig. 2 and Fig. 3. All inclination vectors N have a Y-direction component.

[0049] In Fig. For example, along the x-axis, a rightward inclined vector N is followed by a vertical inclined vector N and then by a leftward inclined vector N. From this sequence, it can be concluded that the surface 2 has a depression V.

[0050] In Fig. In contrast, along the x-axis, a left-leaning inclination vector N is followed by a vertical inclination vector and then a right-leaning inclination vector N. From such a sequence, it can be concluded that the surface 2 has a protrusion E.

[0051] The test information can thus indicate whether surface 2 has one or more depressions V and / or one or more protrusions E. Using device 100, a distinction can therefore be made between a depression V and a protrusion E on surface 2. A depression V can indicate a harmful surface defect on surface 2. A protrusion E, on the other hand, can be harmless soiling on surface 2.

[0052] Fig. Figure 4 shows a schematic representation of an embodiment of a plant 200 for the manufacture of machine elements 1.

[0053] Plant 200 is used for the production of a large number of machine elements per day. Plant 200 includes a first production line 210. One production direction is in Fig. 4 is represented by arrows along the production line 210. A device 100 is arranged along the production line 210, which inspects a surface 2 of the manufactured machine elements 1 (see Figure 4). Fig. 1 to 3).

[0054] In addition to the one in Fig. The embodiment of device 100 shown in 1 comprises the following: Fig. Device 100 shown in section 4 includes a positioning device 40. The positioning device 40 comprises an electric motor (not shown) and a rotary disk (in Fig. 4 (indicated by a rotation arrow). With the aid of the positioning device 40, a further machine element 3 can be positioned for surface inspection simultaneously with the surface inspection of a first machine element 1. For example, the further machine element 3 can be positioned such that the teeth and grooves of the further machine element 3 are aligned with those of the first machine element 1. This position can also be referred to as the inspection position. The inspection position is in Fig. 4 is indicated by an outline around the further machine element 3. In this way, manufacturing time can be saved.

[0055] Machine element 1 can be released for further manufacturing after surface inspection if the specific test information fulfills, for example, a release criterion (see...). Fig.1 to 3). For release, the device 100 can, for example, generate a control command to control a release actuator 250. Release allows the machine element 1 to continue along the production line 210. If, however, the machine element 1 does not meet the release criterion, it can, for example, be diverted by the release actuator 250 to a reject conveyor 240 and stored in a reject container 230 for further processing.

[0056] Furthermore, the production line 210 has a calibration section 220. The calibration section 220 is a return conveyor on which a calibration element 4 is held. The system 200 is specifically designed to supply the calibration element 4 to the device 100 via the production line 210, so that the device 100 can be calibrated. The device 100 can be configured to generate a control command for supplying the calibration element 4. In this way, for example, the calibration of the device 100 can be automated – i.e., without a person having to enter the system 200. In particular, the calibration can be performed during a production downtime, i.e., without production time having to be used for calibration.

[0057] Plant 200 also includes a further production line 211, which is arranged parallel to the first production line 200. The same technical effects and advantages apply to the further production line 211 as to the first production line 210. Reference symbol list 1 machine element 2 Surface 3 other machine element 4 Calibration element 10 Lighting equipment 11 Lighting element 12 additional lighting elements 13 additional lighting elements 15 Lighting area 16 Diffuser 20 Recording device 21 image sensor 22 lens 23 Lens 30 Mirror equipment 31 Mirror element 32 additional mirror elements 40 Positioning device 50 actuator 60 Evaluation unit 100 Device 101 Axis 200 plant 210 first production line 211 additional production line 220 Calibration section 230 exclusion containers 240 reject tape 250 Release actuator E survey N inclination vector V In-depth study X horizontal axis Y vertical axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 1 12 308 832 B

[0003]

Claims

[1] Device (100) for surface testing of machine elements (1), comprising: - at least one lighting device (10) for illuminating a surface (2) of at least one machine element (1), wherein the at least one lighting device (10) is configured to illuminate the surface (2) of the at least one machine element (1) simultaneously with light from at least three separate wavelength ranges, - at least one detection device (20) for detecting the surface (2) of the at least one machine element (1), wherein the at least one detection device (20) is configured to detect at least one image of the surface (2) of the at least one machine element (1), wherein the at least one image depicts a separate reflection from the surface (2) of the at least one machine element (1) in each of the at least three separate wavelength ranges, - at least one evaluation device (60) for evaluating the at least one image, wherein the at least one evaluation device (60) is designed to determine at least one test information of the captured surface (2) from the at least one image. [2] Device (100) according to claim 1, characterized by , that the test information indicates whether the surface (2) has one or more depressions (V) and / or one or more protrusions (E). [3] Device (100) according to claim 1 or 2, characterized by , that the at least one lighting device (10) has at least one ring-shaped lighting element (11, 12, 13) to illuminate the surface (2) of the at least one machine element (1) over an angular range of 0° to 360°. [4] Device (100) according to any one of the preceding claims, characterized by, that the at least one lighting device (10) is configured to illuminate the surface (2) of the at least one machine element (1) in each of the at least three separate wavelength ranges from a separate direction. [5] Device (100) according to any one of the preceding claims, characterized by , that the device (100) further comprises at least one mirror device (30), wherein the at least one mirror device (30) is configured to reflect the reflections from the surface (2) of the at least one machine element (1) over an angular range of 0° to 360° onto the at least one detection device (20). [6] Device (100) according to claim 5, characterized by , that the at least one mirror arrangement (30) has several planar segments, wherein each planar segment is oriented such that each geometric segment of the surface (2) of the at least one machine element (1) is reflected. [7] Device (100) according to any one of the preceding claims, characterized by that the at least one detection device (20) has at least one lens (22) with a variable focal length. [8] Device (100) according to any one of the preceding claims, characterized by , that the device (100) further comprises at least one positioning device (40), wherein the device (100) is configured to inspect the surface (2) of the at least one machine element (1), wherein at the same time at least one further machine element (3) is positioned for surface inspection by means of the at least one positioning device (40). [9] Device according to any of the preceding claims, characterized by , that the at least one lighting device (10) has at least one diffuser (16). [10] Plant (200) for the manufacture of machine elements (1), comprising at least one device (100) according to any one of claims 1 to 9.

Images