DE102022118558A1 - Method and computer program for determining the properties of a structured surface of a component and methods for quality assurance when processing such a surface - Google Patents

Abstract

The invention relates to a method for determining the properties of a structured surface (12) of a component (10), wherein the method can be carried out using a component that has already been processed or to design a planned processing. According to the invention, an evaluation unit (20) receives an image (18) of the surface (12) and searches it according to a predetermined search rule, the predetermined search rule comprising searching the image (18) for at least one predetermined structural feature (24). For each structural feature (24) found, the evaluation unit (20) determines an actual value of at least one parameter describing the structural feature (24) and compares the actual value with a predetermined target value for the parameter, whereby a deviation between the actual value and the target value is determined. The evaluation unit (20) determines the condition of the surface (12) based on the deviation.

Description

The invention relates to a method, in particular a computer-implemented method, for determining a condition of a structured surface of a component, in particular a cast component. The invention also relates to a computer program which causes an evaluation unit to carry out the steps of the method according to the invention. Another aspect of the invention relates to a method for quality assurance when processing a structured surface of a component.

Providing a structure or relief along a surface of a component may have technical and/or aesthetic reasons. For example, in order to achieve sufficient tightness or tightness of a unit or engine block in the combination of several housing components, a liquid sealant can be applied to flange surfaces of the housing components. In order to ensure a desired adhesion of the sealant along the flange surfaces, the surfaces of the flange surfaces can be provided or structured with a processing structure or structure. By way of example, a cross-cut structure or geometry can be created which has diamonds or meshes lined up next to one another. Depending on the tightness requirement and/or properties of the sealant used, different geometries have proven to be useful in terms of the structure created. A cross-cut geometry can be described by parameters such as cross-cut angle and/or mesh size of the mesh.

There are various methods known for checking the condition of structured surfaces for the purposes of quality control. In the simplest case, this can be done randomly by hand. However, this type of review is time-consuming, not objective and prone to errors.

The CN 205 404 440 U describes a system for checking a cross-cut product. A high-speed camera is used, which takes an image of the product to be tested. This image can be contrasted with a known standard image, and an instruction can be issued to a cross-cutting tool based on a result of the comparison. However, the image analysis and the image comparison described here are very computationally intensive and therefore very complex both in terms of the computing capacity to be made available and in terms of the analysis time required.

From the DE 10 2004 038 761 A1 A camera-based object inspection using “Shape from shading” is known. As is well known, with the “Shape from shading” process, the object or component to be tested must be illuminated precisely and with great effort. The check is therefore particularly time-consuming and prone to errors.

From the EP 3 002 071 A1 a device and a method for checking a die-cast component are known. However, a surface analysis is not discussed here, but rather the integrity, geometry and temperature distribution within the component are checked.

An object of the present invention is to provide an efficient and objective way to determine a condition of a structured surface of a component. In other words, objective and effective quality control of a structured surface of a component should be made possible.

The task is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are described in the dependent claims, the following description and the figures.

The invention provides a method for determining a condition of a structured surface of a component. The method is in particular a computer-implemented method. The component can be a cast component, wherein the component can in particular be a housing component with a flange, with the structured surface extending along the flange surface. The structure can in particular serve to improve the adhesion of a sealant to the flange surface. The sealant can be, for example, a hardening elastomer.

The method according to the invention provides that an evaluation unit, for example a device for data processing, receives an image of the surface. The image may have been previously generated by a sensor device. For this purpose, for example, a scanning process may have been carried out along the surface. Alternatively or additionally, the surface may have been optically recorded at least in sections by a camera of the sensor device. Receiving the image according to the invention by the evaluation unit can also include the evaluation unit creating the image from raw data transmitted by the sensor device.

The evaluation unit can also receive the image in the form of CAD data from a known processing plan for the component. In other words, the component does not have to be in a processed form, but the method according to the invention can also run in advance of the processing using the known processing plan. The procedure can also be carried out in advance of the processing to design a planned processing. For example, different machining parameters, such as a diameter of the milling head, a planned path and/or a feed, can be compared in advance.

The structured surface can have a cross-cut structure as a structure. The structure can, for example, have been created using a milling cutter or milling head. Depending on the milling cutter diameter, different optimal structure widths can result, whereby a selection of a respective structure width can be based on a component geometry of the component.

According to the invention, the evaluation unit searches the image of the surface according to a predetermined search rule. This can be done by optically scanning the image. According to the invention, the predetermined search rule includes searching or scanning the image for at least one predetermined structural feature. A structural feature in the sense of the invention is a geometric feature that is characteristic of the structure created. In the above example of the cross-cut structure, the predetermined structural feature may be a closed shape. In this case, one of the stitches of the cross-cut structure is considered a closed shape.

The method according to the invention is preferably only continued in areas in which there is a minimum number of structural features found.

According to the invention, the evaluation unit determines an actual value of at least one parameter describing the structural feature for each structural feature found and compares the actual value with a predetermined target value for the parameter. The actual value can be measured and/or calculated from the image by the evaluation unit. For the example of the cross-cut structure described above, the structural feature may be a stitch. The mesh width and/or the cross-cut angle can be considered as parameters describing the mesh. For example, the mesh size in millimeters and/or the cross-section angle in degrees can be determined as actual values.

The determined actual value is then compared with a predetermined target value for the parameter, with a deviation between the actual value and the target value being determined. The comparison can result in a deviation if the actual value and target value do not match. The deviation can be within a predetermined tolerance limit or exceed it.

Finally, the evaluation unit determines the condition of the surface based on the deviation. In other words, the evaluation unit assigns a quality level to the structured surface based on the deviation. The quality level can be based on the predetermined tolerance limits with regard to a tolerated deviation between the actual and target value.

By searching the image according to the invention for the predetermined structural feature and by the described analysis limited to the structural features found, the method according to the invention is advantageously designed to be less computationally intensive, efficient and therefore resource-saving.

The invention also includes embodiments that result in additional advantages.

One embodiment provides that each structural feature found is approximated or mapped by a geometric comparison form to determine the actual value and the actual value is calculated from known values of the comparison form. The embodiment is explained in more detail below using the example of the cross-cut structure described above.

In the case of the cross-cut structure under consideration, the structural feature can be a closed geometric shape, in particular a diamond or mesh. First, the approximation of the mesh using an ellipse should be examined in more detail as a geometric comparison form.

A diamond or mesh has a long and a short axis (major axis vs. minor axis). The mesh can be approximated using an ellipse as a comparison shape, which also has a long and a short axis. The axes of the ellipse can be transferred to the axes of the rhombus by transferring the center of the ellipse (i.e. the intersection of the ellipse axes) to the center of the rhombus (i.e. the intersection of the diamond axes). Then the long axis of the ellipse can be transferred to the long axis of the rhombus and the short axis of the ellipse can be transferred to the short axis of the rhombus. The axis lengths of the ellipse are known. Thus, after success With greater approximation the axis lengths of the rhombus are also known. This also results in the values for the interior angles of the rhombus.

The parameters describing the diamond include mesh width and cross-section angle. Since the axis lengths of the rhombus are known after successful approximation through the ellipse, the actual values of the cross-section angle and mesh size can be calculated using trigonometric functions. The cross-section angle can be calculated from the ratio of the angles of the rhombus, where “α” denotes the interior angle of the rhombus that is halved by the short axis: $$v=\frac{minOraxislenGtH}{majOraxislenGtH}=\frac{\text{cos}\left(\frac{\alpha }{2}\right)}{\text{sin}\left(\frac{\alpha }{2}\right)}$$

$$\text{sin}\left(\frac{\alpha }{2}\right)=\frac{\frac{majoraxislength}{2}}{Maschenweite}$$

$$Maschenweite=\sqrt{majoraxislengt{h}^2+minoraxislengt{h}^2}$$

The mesh size, i.e. the side length of the diamond, can be calculated as follows: $$\text{cos}\left(\frac{\alpha }{2}\right)=\frac{\frac{minOraxislenGtH}{2}}{MascHenweite}$$

$$\text{sin}\left(\frac{\alpha }{2}\right)=\frac{\frac{majOraxislenGtH}{2}}{MascHenweite}$$

$$MascHenweite=\sqrt{majOraxislenGt{H}^2+minOraxislenGt{H}^2}$$

Preferably, the evaluation unit is provided with a scale, wherein an identifier of the component, for example a hole, is marked in the image of the structured surface and its real dimension, for example in millimeters, can be made available to the evaluation unit. Using the scale, the evaluation unit can then convert the pixels of the image into millimeters. The embodiment described here has the advantage that the geometries of the structure to be checked can be determined precisely with as few calculation steps as possible.

The predetermined structural feature is preferably a closed shape, in particular a closed polygon, preferably a closed quadrilateral. In other words, a closed shape is preferably selected as the predetermined structural feature, which has the advantage that such a shape can be easily recognized by the evaluation unit due to its characteristics.

A further embodiment provides that the condition is visualized as an image, in particular as a two- or multi-dimensional image, of the surface, with different areas of the surface being colored differently based on the deviation determined in the respective area. In other words, the evaluation unit can be designed to display the determined deviations graphically or visually. For this purpose, for example, a screen of a corresponding display device can be controlled by the evaluation unit. For example, the deviations determined along the surface of the component can be classified or assigned to different quality levels. This can be done, for example, by specifying certain tolerance ranges for the deviations, compliance with which is checked. If a narrow tolerance range is maintained, a corresponding area along the image of the surface can be colored green. If a medium tolerance range is maintained, the area can be colored yellow, and if a wide tolerance range is maintained, the area can be colored orange. If the actual values determined are outside of every tolerance range, the area can be colored red. For example, the narrow tolerance range can be half as large as the medium tolerance range and the wide tolerance range can be twice as large as the medium tolerance range. The coloring described above can also be used if, in the case of the diamond pattern, for example, both axes (long and short axes) lie within a predetermined axis length (green), only one axis adheres to the predetermined axis length (yellow), and both axes lie within a predetermined tolerance range (orange) or none of the axes are within the specified tolerance range (red). This has the advantage that a user can detect a distribution of the determined deviations along the surface of the component at first glance. This makes quality control easier and increases the efficiency of component processing.

Alternatively or additionally, a percentage distribution of the determined deviations along the surface can preferably be determined and, in particular on the display device mentioned, visualized as a bar diagram. In other words, the evaluation unit can provide an output of an image file with structural areas marked in color and/or an output of the percentage distribution of the colored markings as a bar chart.

The invention also relates to a computer program which can be loaded directly into a memory of an evaluation unit, with program means to carry out the steps of the method as described above. to be executed when the program is executed in the evaluation unit.

As a further solution, the invention also includes a computer-readable storage medium, comprising commands which, when executed by a computer or a computer network, in particular an evaluation unit, cause it to carry out an embodiment of the method according to the invention. The storage medium can, for example, be used at least partially as a non-volatile data storage (for example as a flash memory and/or as an SSD - solid state drive) and/or at least partially as a volatile data storage (for example as a RAM - random access memory ) must be designed. The computer or computer network can provide a processor circuit with at least one microprocessor. The instructions may be provided as binary code or assembler and/or as source code of a programming language (e.g. C).

The computer program preferably also includes a graphic user interface (GUI), which guides a user through individual steps of the method according to the invention and also enables users who cannot deal with programming languages to use the method described here.

The invention further relates to a method for quality assurance when processing a structured surface of a component, which comprises determining a condition of the structured surface according to the method according to the invention.

According to the quality assurance method, a processing device for producing the structured surface first removes material from the surface using a tool head in accordance with a predetermined pattern. The processing device can be, for example, a milling device with a milling head. After the structured surface has been created, a sensor device creates an image of the structured surface. As described above, the sensor device can have a scanning device and/or an optical camera, which are set up to detect at least sections of the structured surface. The image is then transmitted to an evaluation unit, which determines the nature of the structured surface.

To determine the nature of the structured surface, the method for determining the quality described here is carried out. In other words, this process forms a sub-step of the quality assurance process. Accordingly, further developments of the method for quality assurance described here, which have features such as those already described in connection with the further developments of the method for determining quality, are also part of the invention. For this reason, the corresponding further developments in the quality assurance process are not described again here.

According to the quality assurance method, at least one processing parameter for the processing device is adapted depending on the specific condition. The processing parameter can also be adjusted, for example, by the evaluation unit.

The quality assurance method can preferably contain a loop. In other words, after the step of adjusting the processing parameter, the surface can be processed again. The surface can then be recorded again and the condition of the surface can be determined again. In this way, the quality assurance procedure can be further improved in an iterative process.

A further development provides that the processing device for producing the structured surface processes it along a path, the path being described by at least one path parameter, the at least one path parameter being adapted depending on the specific condition.

Alternatively or additionally, a feed and/or a pressing force of the tool head of the processing device can be adapted to the surface.

A further embodiment provides that, depending on the specific condition, the tool head of the processing device is replaced in whole or in part.

For use cases or application situations that may arise with the method and that are not explicitly described here, it can be provided that an error message and/or a request to enter user feedback and/or a standard setting and/or a predetermined one can be issued according to the method Initial state is set.

The invention also includes the combinations of the features of the described embodiments. The invention therefore also includes implementations that each have a combination of the features of several of the described embodiments unless the embodiments have been described as mutually exclusive.

• 1 eine schematische Darstellung eines Bearbeitungsprozesses zur Bearbeitung einer Oberfläche eines Bauteils;
• 2 eine schematische Darstellung einer Ausführungsform des erfindungsgemäßen Verfahrens.

Examples of embodiments of the invention are described below. This shows:

• 1 a schematic representation of a machining process for machining a surface of a component;
• 2 a schematic representation of an embodiment of the method according to the invention.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another and which also further develop the invention independently of one another. Therefore, the disclosure is intended to include combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.

In the figures, the same reference numerals designate functionally identical elements.

1 shows a schematic representation of a machining process for machining a component 10. The machining gives the component 10 a structured surface 12. The structured surface 12 is in 1 indicated by a diamond pattern and can contain several structural features 24 in the form of diamonds. The structured surface 12 is generated along the component 10 by a processing device 14. For this purpose, the processing device 14 can remove material from the surface 12 using a tool head (not shown) according to a predetermined pattern, for example according to the diamond pattern shown here. After processing has taken place, the structured surface 12 can be detected or scanned or photographed at least in sections by a sensor device 16. The sensor device 16 can generate an image 18 of the surface 12. The image 18 can be transmitted from the sensor device 16 to an evaluation unit 20. The evaluation unit 20 can then determine a condition of the structured surface 12 (for this purpose 2 ).

The evaluation unit 20 can generate a command 22 based on the condition determination carried out by it and transmit it to the processing device 14, wherein the command 22 can contain that at least one processing parameter for the processing device 14 is adjusted depending on the specific condition. Taking the adapted processing parameter into account, the processing device 14 can now either continue with the processing of the structured surface 12 of the already processed component 10, for example revise it, or process a component 10 that has not yet been processed in accordance with the adapted processing parameter.

2 shows with reference to the related with 1 designated and described components are a schematic representation of an embodiment of the method according to the invention. In a method step S1, an evaluation unit 20 receives an image 18 of a structured surface 12 of a component 10. The evaluation unit 20 then searches the image 18 according to a predetermined search rule, the search rule comprising searching the image 18 for at least one structural feature 24. As in 1 shown, the structural feature 24 can be a closed shape, in particular a diamond or mesh. In a method step S3, the evaluation unit 20 determines an actual value of at least one parameter describing the structural feature 24 for each structural feature 24 found and compares the actual value with a predetermined target value for the parameter. In the course of the comparison, a deviation between the actual value and the target value is determined by the evaluation unit 20.

In a step S4, the evaluation unit 20 determines the nature of the structured surface 12 based on the determined deviation. In a subsequent step S5, a measure is suggested or carried out by the evaluation unit 20, the measure being based on the determined condition of the surface 12. The measure can be, for example, the generation and transmission of the above-mentioned command 22 to the processing device 14. The measure can alternatively or additionally be a visualization of the determined condition as a two- or multi-dimensional image of the surface 12. The measure can alternatively or additionally be a representation of a percentage distribution of the determined deviations along the surface 12, for example as a bar chart.

Overall, the examples show how software-supported analysis and optimization of surface processing of components, especially cast housing components, can be provided.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 205404440 U [0004]
• DE 102004038761 A1 [0005]
• EP 3002071 A1 [0006]

Claims (10)

Method for determining a condition of a structured surface (12) of a component (10), wherein - an evaluation unit (20) receives an image (18) of the surface (12) and searches it according to a predetermined search rule, the predetermined search rule comprising searching the image (18) for at least one predetermined structural feature (24), - the evaluation unit (20) determines an actual value of at least one parameter describing the structural feature (24) for each structural feature (24) found and compares the actual value with a predetermined target value for the parameter, with a deviation between the actual Value and the target value is determined, and where - The evaluation unit (20) determines the condition of the surface (12) based on the deviation. Procedure according to Claim 1 , whereby each structural feature (24) found is approximated by a geometric comparison form to determine the actual value and the actual value is calculated from known values of the comparison form. Method according to one of the preceding claims, wherein the predetermined structural feature (24) is a closed geometric shape, in particular a closed polygon, preferably a closed quadrilateral. Method according to one of the preceding claims, wherein the condition is visualized as an image of the surface (12), different areas of the surface (12) being colored differently in the image based on the deviation determined in the respective area. Method according to one of the preceding claims, wherein a percentage distribution of the determined deviations along the surface (12) is determined and visualized as a bar diagram. Computer program, which can be loaded directly into a memory of an evaluation unit (20), with program means in order to carry out the steps of the method according to one of the preceding claims when the program is executed in the evaluation unit (20). Method for quality assurance when processing a structured surface (12) of a component (10), wherein - a processing device (14) for producing the structured surface (12) removes material from the surface (12) according to a predetermined pattern with a tool head, - a sensor device (16) detects the structured surface (12) at least in sections and creates an image (18) of the same, - the image (18) is transmitted to an evaluation unit (20), which determines the condition of the structured surface (12) according to a method according to one of the Claims 1 until 5 determined, and - at least one processing parameter for the processing device (14) is adjusted depending on the specific condition. Procedure according to Claim 7 , wherein the processing device (14) for producing the structured surface (12) processes it along a path, the path being described by at least one path parameter, the at least one path parameter being adapted depending on the specific condition. Procedure according to one of the Claims 7 or 8th , wherein the processing parameter describes a feed and / or a pressing force of the tool head of the processing device (14) on the surface (12). Procedure according to one of the Claims 7 until 9 , whereby the tool head of the processing device (14) is completely or partially replaced depending on the specific condition.

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