RU2790124C1 - Method for coordination of identification and processing workpiece defect and device for implementation of this method - Google Patents

Abstract

FIELD: material processing.

SUBSTANCE: group of inventions relates to processing of defects by grinding or polishing. A method for coordination of identification of defect (1) of a workpiece coating surface and its processing by grinding and/or polishing, using at least one grinding or polishing tool capable of moving above defect (1) automatically and under computer control based on a stored program, is described. Stages of implementation of a method are given, and a device for implementation of a method is disclosed.

EFFECT: increase in the accuracy of a defect localization process and accuracy of its processing.

18 cl, 5 dwg

Description

The invention relates to a method for coordinating the identification and grinding and/or polishing of at least one defect with at least one grinding or polishing tool capable of moving automatically and under computer control, based on a stored program, over a coating defect on a workpiece surface according to the restrictive part of paragraph 1 of the claims , to the device for implementing this method.

In particular, in the case of defects in painted surfaces, such as those found on car bodies, especially in the form of dust inclusions, dirt particles, paint noses and craters, which cannot be avoided despite many efforts, these defects must be eliminated by grinding and polishing.

In particular, identifying and classifying the identified deficiencies is very time-consuming even for specially trained and experienced employees.

Then, based on the classification of defects, the appropriate abrasive is selected, and the defect is removed by manual grinding and subsequent polishing.
For sanding, abrasive materials based on micro-grit have proven to be the best choice. They can be used as abrasive sheets by hand or on manual rotary, eccentric, planetary or vibrating machines.

According to the size of the defect, the task is to keep the grinding area as small as possible and prepare it for subsequent polishing with a minimum depth of roughness.

For the grinding process, two different methods are generally known, with respective advantages and disadvantages.

In the case of so-called dry grinding, for example, the grinding dust generated during the grinding process is collected on the abrasive sheet, which means that only a few defects can be treated with one abrasive sheet.

If grinding is carried out using the so-called wet grinding process, in which the defect and/or the abrasive sheet is wetted with grinding water, significantly more defects can be treated. However, the defect to be processed must be cleaned after the sanding process before polishing due to adhering sanding dust or dirt, which can take a very long time, especially on vertical surfaces.

For polishing, an appropriate amount of polishing paste is applied to the grinding area and/or polishing wheel, and the grinding area is processed by the polishing machine.

Handling defects is very time and effort intensive, especially when the defect is on transitions, curved surfaces, smeared edges, or near cracks.

When processing a defective area, a worker may experience significant losses in quality and the need for additional work if hand-held grinders and polishers are set at an angle, if, for example, grinding must be carried out in ergonomically unfavorable places, improper micro-grit is used, the abrasive sheet is not positioned correctly on the backing pad , the abrasive sheet is not replaced in time, the grinding time is exceeded and, as a result, the grinding is carried out too deep, the amount of polishing paste for the grinding area is selected too large, as a result of which unnecessary splashes of polishing paste remain on the workpiece, for example, on a car body, or too little polishing paste is selected paste and therefore the optimum polishing effect is not achieved, and the polishing area is too hot due to too much contact pressure and too long polishing time, polishing paste flocculates and polishing curls form.

During independent reviews of the product and process by the quality management team, the process is regularly evaluated, improvements and employee training are initiated.

Partial automation of the localization and processing of flaws is known from the prior art.

When eliminating deficiencies, localization procedures help to determine the position of the defect and use it for a further process, while the localization procedure can be semi-automatic or fully automatic.

In accordance with the prior art, a distinction is made between stationary localization methods, in which a workpiece, for example, the surface of a car body with finish painting, is examined by a system, and a modular localization method, in which the workpiece is examined along the outer contour by a detection unit using a detector attached to a robot arm.

Using stationary localization methods, it is possible to examine workpieces of various sizes and characteristics along the contour, however, the method does not allow one to examine inside shaded areas and undercuts of the workpiece. In addition, the recorded scanned data of the position and classification of defects using such methods is less accurate than is possible with modular localization methods.

During the processing of defects, the worker is given time for partially automated grinding and polishing, or they are performed automatically.

The invention aims to further develop a general method so as to optimize the grinding or polishing result, in particular to better coordinate defect detection and automatic grinding and polishing.

This problem is solved by a method having the features of paragraph 1 of the claims, as well as a device having the features of paragraph 15 of the claims.

The method according to the invention for coordinating the identification and grinding and/or polishing of at least one defect with at least one grinding or polishing tool capable of moving automatically and under computer control, based on a stored program, over a defect in the coating of a surface of a workpiece, comprises the following steps:

a) automatic, in particular optical, scanning of the surface coating of the workpiece (5) at the detection station (2) and storing the scanned position data in a database;

b) identifying the defect (1) by comparing the detected position data with the stored target workpiece data (5);

c) simulation of possible movements of the grinding or polishing tool (7, 8) to process the defect (1);

d) transferring the setting data for the grinding or polishing tool (7, 8) determined during the simulation to the main computer;

e) transferring certain processing data for processing a defect (1) to a grinding or polishing tool (7, 8);

f) processing the defect (1) with a grinding or polishing tool (7, 8).

The method according to the invention significantly improves the precise coordination of the individual process steps, in particular through the interaction of automatic defect detection and automatic grinding and polishing.

This is accompanied by significant time savings, since, in particular, automatic defect detection takes less time than manual or visual defect detection by trained personnel.

In addition, automatic storage of the coordinates of detected defects allows you to directly transfer these coordinates for the adjustment of the grinding or polishing tool.

Preliminary simulation of the grinding or polishing process before grinding or polishing ensures that the corresponding defects can be automatically processed with available grinding or polishing tools.

The subsequent processing of the defect with the grinding or polishing tool can be optimized, in particular in terms of speed, on the basis of the processing data transmitted to the control unit of the grinding or polishing tool.

Preferred embodiments of the invention are the subject of dependent claims.

According to a preferred embodiment of the method according to the invention, the optical scanning of the surface coating of the workpiece is carried out at the detection station using a moving detection unit.

This improves the accuracy of the localization process in terms of location data, defect size, and defect type. This in turn allows machining with the smallest possible grinding points.

According to a preferred embodiment of the method according to the invention, when the impossibility of automated processing of the defect area is detected by the grinding or polishing tool in step c), the defect area is marked and marked.

The advantage is that such defects are bypassed directly by the grinding or polishing tool, resulting in additional time savings. The unmachinable defect is displayed to the operator on the screen, and the coordinates of this defect are stored, which allows trained special personnel to deal with these defects after automatic processing of machine-machinable defects.

According to another preferred embodiment, the workpiece is divided into processing areas before step e), in particular in the case of several detected defects.

The advantage is that with the path planning software it is possible to optimize the processing of defects in terms of speed.

Machining areas are preferably calculated based on the geometric shape of the workpiece and the availability of an appropriate grinding or polishing tool.

This can greatly improve coordination, especially in the case of multiple grinding or polishing tools available. It also avoids tool collisions.

According to another preferred embodiment, in the case of several defects to be processed, at least one grinding or polishing tool is controlled so as to optimize the processing of defects in time and distance. In particular, several grinding or polishing tools located next to each other are controlled simultaneously to process the corresponding defect.

This allows multiple defects to be processed at the same time, which means that the processing time of the workpiece can be further reduced.

According to another preferred embodiment, in the case of parts of the workpiece that can move a predetermined distance in the holder, the opening angle is calculated on-line by means of a distance sensor using the stored target data, such as CAD data, of the workpiece and is taken into account in the processing of defects, so that the grinding and polishing the tool can perform a correct surface finish.

Such situations arise in particular with car bodies with doors, bonnets or guards, which, after pre-painting and drying, are not in the closed position, but only pre-fixed in the respective frames.

According to another preferred embodiment, the grinding process is carried out exclusively as so-called dry grinding.

This makes it possible to shorten the cycle time for defects, since the grinding dust generated during the grinding process remains bound in the abrasive material, and thus intermediate cleaning of the grinding area before polishing can be eliminated.

According to another preferred embodiment, during the polishing of a defect, the area of the pre-abrased surface is treated repeatedly, which in particular has the advantage of less heat generation in the region of the polishing point and thus prevents flocculation of the polishing agent used or other similar effects.

The device according to the invention for carrying out the method described above comprises a detection station, a grinding station and a polishing station. At least one grinding tool is made in the form of a robot that is connected to a computer and has a support device that is attached to the arm of the robot, can move with rotation and / or vibration and / or planetary, and is designed to hold the abrasive belt, and the polishing tool, which is made in the form of a robot that is connected to a computer and has a support plate that is attached to the arm of the robot, can move with rotation and / or vibration and / or planetary and is designed to hold the polishing sponge, while the arm is adapted to move under the control of the computer.

The use of an abrasive belt is particularly suitable for dry grinding, since such an abrasive belt can be cyclically adjusted after each defect treatment so as to adapt the unused area of the abrasive belt surface for each defect to be processed, thereby ensuring a consistent quality of grinding for each defect.

According to a preferred embodiment, the at least one grinding or polishing tool is movable along a linear axis, which allows a greater reach of the grinding or polishing tool.

According to a preferred embodiment, the polishing tool comprises a wiping and/or blowing device and, optionally, a detection unit. Thus, the wiping device allows you to automatically wipe the polishing point. The blower device makes it possible to additionally cool the polishing point by blowing compressed air, in particular into the polishing sponge. The detection block makes it possible to check the results.

In particular, getting rid of the light tunnels required in the prior art for manual processing of defects by grinding, polishing and wiping the polishing area, as well as control of the results, significantly less effort for cleaning, which is the result of dry grinding, waste-optimized form of abrasive in the form of a tape instead of an abrasive sheet, no additional necessary finishing steps for fixing the abrasive due to the vacuum bonding used, less consumption of polishing pastes due to precisely coordinated dosing with a polishing sponge, significantly less space requirement, environmental balance and sustainability, all this applies to significant improvements achieved thanks to the method and device in accordance with the invention.

Preferred examples of embodiments of the invention are described in more detail below with reference to the accompanying drawings, in which:

1 is a schematic plan view of an embodiment of a device according to the invention for carrying out the method according to the invention,

figure 2 is a side view of the device shown in figure 1, and

Figures 3, 4 and 5 are respective perspective views of a detail of the device shown in Figures 1 and 2.

In the following description of the figures, terms such as "top", "bottom", "left", "right", "front", "rear", etc., refer exclusively to the examples of the location of the detection station, polishing station, grinding station, grinding tool, polishing tool, workpiece, etc. selected for the respective figures. These terms are not to be understood as restrictive and these guidelines may change for other operating positions, mirror-symmetrical design, etc.

In figures 1 and 2, reference numeral 1 generally denotes an embodiment of a device according to the invention for carrying out a method for detecting and processing by grinding and/or polishing at least one defect 1 with at least one grinding or polishing tool 7, 8 in coating the surface of the workpiece 5, while the grinding or polishing tool 7, 8 is able to move automatically and under computer control over the defect 1 based on the stored program.

As can be seen in figures 1 and 2, the device comprises a detection station 2, a grinding station 3 and a polishing station 4. The individual stations are interconnected by a rail system 9, along which the workpieces 5 to be processed, for example, in the form of car body parts, can move from station to station and timely delivered to individual stations.

As shown in figures 1, 2 and 3, the detection station 2 comprises two robots with respective robot arms, to the end of which an optical scanning device is attached. Preferably, the optical sensing device includes a source of electromagnetic radiation directed at the workpiece 5, and a detector unit 61 for detecting and then evaluating the rays reflected from the workpiece 5.

The optical scanner 6 can optically detect all portions of the surface of the workpiece 5 using the movable arm of the robot.

The robot arm is preferably controlled by a higher level host computer with a database connected to it, in which the relative coordinates of the surface of the workpiece 5 to be scanned are stored.

Based on the relative coordinates of the surface of the workpiece 5, blocking areas related to the workpiece 5 are permanently stored or automatically determined in advance, for example, along the edges of the workpiece 5, along the lubricated edges of the workpiece 5, made in the form of housing modules, and in the narrow radii of the workpiece 5. All necessary parameter variables are stored to process the movement of the robots and adjusted to the appropriate defect size. Limit values are stored for variable parameters that can be changed for a continuous improvement process.

The optical scanning device 6 scans the surface of the workpiece 5, preferably using a light beam. The reflected radiation is detected by the detector and any defects found on the surface of the part 5 are stored digitally in a second database.

When saving, the position data and, optionally, defect weighting are saved. Together with the aforementioned host computer database in which the relative surface coordinates of the workpiece 5 are stored, the data of the detected defect is compared with the stored relative coordinates of the workpiece 5 and coordinated with the forthcoming further automatic processing, i.e. grinding and subsequent polishing.

Depending on the workpiece to be processed, it is also possible to use only one robot with a defect detection device attached to it at the detection station 2, or even more than two such robots.

It is also provided, depending on the size of the workpiece or to improve the accuracy of the localization process in terms of position data, defect size and type of defect, to install this or an additional detection unit on the grinding tool itself.

Since the optical scanner 6 of the detection station 2 can move, it is also possible to scan areas of the workpiece that cannot be checked by stationary localization systems, such as shadow areas or undercuts of the workpiece.

Detection of only the position of the defect is also provided, which eliminates the need for extensive and expensive detection of the position of the vehicle and the workpiece.

In this case, the data acquisition unit will optically scan the area of the defect in advance, and more accurate data will be used for further processing in step b).

As shown in figures 1, 2 and 4, two robots are also located on the grinding station 3 next to the detection station 2. In the exemplary embodiment shown here, the robots can move along the linear axis 32. Also on such linear axes 32, the robots of the detection station 2 and/or the polishing station 4 are provided. 3.

Before the grinding tools 7 of the grinding station 3 are controlled by the host computer, a simulation of the possible movements of the grinding tool 7 for processing the corresponding defect is performed beforehand.

If during such a simulation it is determined that automatic processing of a defect by the grinding tool 7 is not possible, for example due to an unfavorable position of the defect for automatic processing, the coordinates of this defect are transmitted to the host computer and reported to the employee, preferably in the form of an image on the screen.

If the simulation shows that the defect can be machined automatically, the position data of this defect is transmitted to the main computer for further grinding. During this process, the grinding tool 7 and the robot arm to which the grinding tool 7 is attached are brought to a predetermined position for grinding a defect.

As shown in figures 1 and 2, several robots with respective grinding tools 7 are placed in the grinding station 3, the workpiece 5 is preferably divided into several processing sections before the processing data determined to process the defect is transmitted to the grinding tool 7.

The machining areas are preferably calculated on the basis of the geometric shape of the workpiece and the availability of an appropriate grinding or polishing tool. Then, the grinding tool 7 with the shortest time and distance is controlled so as to optimize the processing of the defect in terms of time and distance.

When grinding, the preferred method is grinding with concentric grinding paths around the defect.

In particular, the calculation of the control of the grinding tools 7 and, in the subsequent polishing process, also of the polishing tools 8 is performed by the software so that the defective area of the workpiece 5 is machined at an optimized speed.

When processing defects, it is also taken into account that in the case of simultaneous operation of several grinding or polishing tools, defects can be processed in parallel without collisions between grinding or polishing tools or between robots and robot arms, each of which has such a grinding or polishing tool.

Preferably, after the grinding process is completed, the host computer performs evaluation using statistical methods in order to further improve the automation of defect processing, in particular by reducing the number of processing steps.

The same basically applies to the polishing of defects at the polishing station 4, which is adjacent to the grinding station 3.

In the case of workpiece parts that can move in the holder for a given distance, the grinding or polishing tool is aligned accordingly, or small deviations are compensated for by smoothly placing it on the part of the workpiece 5.

Such situations arise, for example, with car bodies with doors, bonnets or guards, which, after pre-painting and drying, are not in the closed position, but are only pre-secured in the respective frames and can be moved to the closed position by applying pressure.

Thus, preferably in the case of open positions of the part of the workpiece 5 at an angle of up to 1°, such deviations from the stored coordinates are compensated by the smooth placement of the machining tools on this part of the workpiece 5 in the normal direction.

Alternatively, it is also possible to calculate the opening angle by means of an upstream distance sensor, in particular in front of the grinding tool 7, and thus take it into account during the grinding operation.

As shown in FIG. 4, for the grinding process, it is preferable to use grinding tools 7 that can operate in a dry grinding mode. For this purpose, the grinding tool 7 preferably includes an abrasive belt 71 which is displaced after each grinding operation to such an extent that the unused portion of the abrasive belt is used for the next grinding operation. Thus, the abrasive belt 71 is preferably held by vacuum on the backing pad of the grinding tool 7.

This means that intermediate cleaning of the grinding area before polishing is no longer required, since the area around the defect is completely free of dust and the abrasive can be changed, for example, during breaks.

The micro-grain used here corresponds to the polishing paste used. The preferred micrograin size is outside the FEPA-P range with a maximum roughness depth of less than 0.5 µm.

When abrasive processing, it is preferable to use the same micrograin for all types and sizes of defects. In the case of larger defects, grinding is carried out several times, but always with unused abrasive, while the grinding movements are adapted to the size of the defect. When using unused abrasive, the surface roughness of the grinding area is in a narrow tolerance range, even when processing larger defects.

As also shown in FIG. 5, the polishing tool 8 has a polishing device attached to the arm of the robot with a polishing sponge through which a polishing agent, particularly in the form of a polishing paste, can be supplied. It is also possible to apply the polishing agent directly to the grinding point of the head or to the polishing sponge itself.

Long-term wetting of the surface of the polishing sponge can be avoided by at least tripling the dosage of the polishing paste once after changing the polishing sponge.

It also provides for the recycling of the polishing sponge after use with the polishing pad washer and its continued use. According to the technological parameter, it is preferable to replace the polishing sponge after the third cleaning.

The area of polishing on the corresponding defect is preferably several times larger than the area of the surface previously processed by grinding. Thus, especially in the second half of the polishing time, heat generation can be minimized by changing the contact pressure and cooling the polishing sponge with compressed air.

In this case, the polishing tool 8 preferably includes a wiping device, for example in the form of a microfiber cloth or a cleaning sponge, to ensure automatic wiping of the polishing area. Thus, the wiper is preferably attached to the arm of the robot together with the polisher 8, and the wiper is rotatable.

In this case, the polishing tool 8 preferably includes a blowing device, through which compressed air can be supplied to the polishing point to cool it. In particular, for a closed cycle in which the polishing medium is supplied to the polishing point in the polishing sponge itself or through the polishing sponge to the polishing point, the heat generated during polishing can be minimized, in particular by changing the contact pressure of the polishing sponge at the point to be polished and cooled with the aforementioned compressed air.

It is also envisaged that the detection unit 6 mounted on the polishing tool can optically scan the treated areas and use them to check the results.

LIST OF REFERENCES

1 - defect

2 - detection station

3 - grinding station

32 - tool rail / linear axis

4 - polishing station

5 - blank

6 - detection unit

61 - detector

7 - grinding tool

71- abrasive belt

8 - polishing tool

81 - polishing sponge

9 - rail system

Claims (24)

1. A method for coordinating the identification and processing of at least one defect in the coating of a workpiece by grinding and / or polishing with at least one grinding or polishing tool (7, 8) configured to move automatically and under computer control based on a stored program over the defect ( 1) in coating the surface of the workpiece (5), containing the steps: a) automatic, in particular optical, scanning of the surface coating of the workpiece (5) at the detection station (2) and storing the scanned position data in a database, b) identifying the defect (1) by comparing the detected position data with the stored target workpiece data (5), c) simulation of possible movements of the grinding or polishing tool (7, 8) to process a defect (1), d) transferring the setting data for the grinding or polishing tool (7, 8) determined during the simulation to the host computer, e) transferring certain processing data for processing a defect (1) to a grinding or polishing tool (7, 8), f) processing the defect (1) with a grinding or polishing tool (7, 8). 2. The method according to claim 1, characterized in that optical scanning of the surface coating of the workpiece (5) is carried out at the detection station (2) using a mobile detection unit (6). 3. The method according to p. 1 or 2, characterized in that when it is revealed that it is impossible to automatically process the defect with a grinding or polishing tool (7, 8) in step c), the defect is marked and marked. 4. The method according to one of paragraphs. 1-3, characterized in that before step e) the workpiece (5) is divided into processing areas. 5. The method according to claim 4, characterized in that the processing areas are calculated based on the geometric shape of the workpiece (5) and accessibility for the respective grinding or polishing tool (7, 8). 6. The method according to one of paragraphs. 1-5, characterized in that in the case of a plurality of defects to be processed, at least one grinding or polishing tool (7, 8) is controlled so as to optimize the processing of defects in time and distance. 7. The method according to claim 6, characterized in that a plurality of grinding or polishing tools (7, 8) located next to each other are controlled simultaneously to process the corresponding defect. 8. The method according to one of paragraphs. 1-7, characterized in that in the case of parts of the workpiece that can move in the holder for a given distance, the grinding or polishing tool (7, 8) is adjusted so as to align the grinding or polishing tool (7, 8) normal to the surface in according to the stored desired data, or compensate for small deviations by smooth placement on the workpiece. 9. The method according to one of paragraphs. 1-8, characterized in that the grinding operation is carried out by dry grinding. 10. The method according to one of paragraphs. 1-9, characterized in that grinding is performed during grinding along a concentric grinding path around the defect. 11. The method according to one of paragraphs. 1-10, characterized in that the number of grinding operations is regulated depending on the size of the defect. 12. The method according to one of paragraphs. 1-11, characterized in that during the polishing of the defect, the surface area that has undergone preliminary abrasive processing is repeatedly treated. 13. The method according to one of paragraphs. 1-12, characterized in that after polishing the defect, the defect is cleaned with a wiping device. 14. The method according to one of paragraphs. 1-13, characterized in that after polishing the defect, the result is checked. 15. A device for coordinating the identification and processing of at least one defect in the coating of the workpiece by the method according to claim 1, containing a detection station (2), a grinding station (3) and a polishing station (4), while at least one grinding tool (7 ) is made in the form of a robot connected to a computer and having a support device attached to the arm of the robot and capable of moving with rotation, and/or vibration, and/or planetary, to hold the abrasive belt (71), while the polishing tool (8) is made in the form of a robot connected to a computer and having a support plate attached to the arm of the robot and capable of moving with rotation and / or vibration and / or planetary, adapted to hold the polishing sponge (81), while the arm is able to move under the control of the computer, and at least the detection station (2) has an optical detection unit (6). 16. Device according to claim 15, characterized in that at least one of the grinding or polishing tools (7, 8) is mounted for movement along the linear axis (32). 17. Device according to claim 15 or 16, characterized in that at least one of the grinding or polishing tools (7, 8) contains an optical detection unit (6). 18. The device according to one of paragraphs. 15-17, characterized in that the polishing tool (8) contains a wiping device and/or a blowing device.

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