Unknown

Abstract

Grinding a surface of a workpieces is accomplished with a grinding machine having at least two grinding units. First, a target structure of the surface to be achieved is provided. Then, using predetermined grinding parameters, a first of the two grinding units is used to grind the surface of the structure. Then, the surface of the actual structure is captured and compared to the target structure. Based on the comparison, the grinding parameters are adjusted and the surface is then ground, using the adjusted parameters, with the second of the two grinding units.

Claims

1. A method for grinding a surface of a workpiece with a grinding machine comprising at least two grinding units, comprising: providing a description of a target structure of the surface to be achieved; grinding the surface of the workpiece with a first of the at least two grinding units using a predetermined set of grinding parameters so as to produce a ground surface; capturing an actual structure of the ground surface; comparing the captured actual structure with the target structure; adjusting a set of grinding parameters of a second of said at least two grinding units depending on said comparison; and grinding the surface of the workpiece with the second of the at least two grinding units using the adjusted set of grinding parameters.

2. The method according to claim 1, wherein the grinding machine has more than two grinding units and the surface of the workpiece is ground by more than two grinding units.

3. The method according to claim 2, wherein before each grinding step the actual structure of the surface is captured by one of the grinding units and compared with the target structure, and the set of grinding parameters to be used during grinding is adjusted depending on the result of the comparison.

4. The method according to claim 1 further comprising determining a wear condition of at least one abrasive of at least one of the grinding units, and wherein the set of grinding parameters is adapted in dependence on the determined wear condition.

5. The method of claim 1 wherein the description of the target structure is an image of a reference surface or the reference surface.

6. The method of claim 1 wherein the target structure is 2-dimensional or 3-dimensional.

7. The method of claim 1 wherein the set of grinding parameters comprises one or more of a feed rate, an abrasive speed, a pressure or its spatial and/or temporal distribution with which the abrasive is pressed against the workpiece, and a path of at least one pressure shoe and/or pressure beam from a rest position to the grinding position.

8. The method of claim 1 wherein one or more sets of grinding parameters are adjusted in dependence on sensor measurement data obtained from one or more of at least one sound, vibration and/or force measurement on a pressure shoe and/or pressure beam of at least one grinding unit, at least one displacement measurement on at least one pressure shoe and/or one pressure beam, at least one surface and/or at least one thickness measurement of the workpiece, a roughness, temperature and/or slip measurement of at least one abrasive material, and a color, capacitive and/or geometric measurement of the surface of at least one abrasive.

9. The method according to claim 2 wherein the surface is not ground by all grinding units of the grinding machine and the grinding units used for grinding are selected taking into account a state of wear of abrasives of all the grinding units.

10. The method of claim 1 further comprising adjusting a position of the workpiece relative to at least one abrasive of at least one grinding unit taking into account a state of wear of the abrasive.

11. The method of claim 1 further comprising rejecting the workpiece is rejected as scrap if, when comparing the captured actual structure with the target structure, it is detected that the target structure cannot be achieved or if at least one parameter of the adapted set of grinding parameters is outside a predetermined value range.

12. A grinding machine for performing a method according to claim 1.

Description

[0039] With the aid of the accompanying figures, some embodiments of the present invention are explained in more detail below. They show:

[0040] FIG. 1 schematic representation of a grinding machine according to an embodiment of the present invention, and

[0041] FIG. 2 a flow diagram of a method according to a further embodiment of the present invention.

[0042] FIG. 1 schematically shows a grinding machine according to an embodiment of the present invention. It has three grinding units 2, each of which has an abrasive 4, in the example shown an abrasive belt. A conveyor belt 6 conveys the work-pieces to be ground, which are not shown in FIG. 1, through the grinding machine along the direction indicated by the arrow 8. Each of the abrasives 4 is pressed against a workpiece to be ground by means of a separate pressure element 10, which in FIG. 1 is designed as a pressure beam. Various sensors are provided to pick up different readings and measure different parameters.

[0043] The grinding machine shown in FIG. 1 has three surface sensors 12 that are adapted to capture an actual structure of the surface of the workpiece. The surface sensors 12 can be designed as cameras in the visible or non-visible wavelength range, 3D scanners or other sensors. A closing sensor 14, which is also designed as a surface sensor and which captures the finished grinding result, i.e. the actual structure after the last grinding process, is arranged behind the last grinding unit in the feed direction.

[0044] FIG. 1 also shows further measuring sensors 16 which are arranged within the individual grinding units 2. They exemplify different types of sensors which can be used to capture measured values on the basis of which an adapted set of grinding parameters can be determined or adjusted. In the embodiment example shown in FIG. 1, the measuring sensors 16 are adapted to determine the path of the pressure element 10 from the rest position shown in FIG. 1 to a grinding position.

[0045] Via signal lines 18, the signals captured by the sensors 12, 14, 16 are transmitted to an electronic data processing device 20. The signal lines 18 of the sensors 12, 14, 16 of the last grinding unit 2 are shown dashed to illustrate that these sensors 12, 14, 16 are optional and are not used for determining a customized set of grinding parameters. The electronic data processing device 20 has an input module 22 by means of which a user of the grinding machine can intervene in the control system, enter new parameters or otherwise operate the machine.

[0046] FIG. 2 shows schematically a sequence of a method according to an embodiment of the present invention. After the start 24 of the method, parameters of the workpiece to be ground, in particular its width and/or thickness, are recognized by means of a workpiece recognition device 26 and initially stored. These parameters and data relating to the workpieces are used to achieve uniform stressing of the abrasive means 4 in the electronic data processing device 20. This is done in the stressing module 28 of the electronic data processing device, to which the data and parameters are passed. This module may also be in the form of a computer program product, for example software. In the next method step, surface data describing the target structure are provided from a data memory 30. This data can be available 2-dimensional or 3-dimensional and is transferred to a target structure module 32, which provides a machine-readable description of the target structure.

[0047] In the next step, the actual structure is captured 34, which is then compared to the target structure in a comparison module 36 of the electronic data processing device 20. If this comparison indicates that an adjusted set of grinding parameters needs to be determined, this information is passed to an adjustment module 38 in which the new adjusted set of grinding parameters is determined. Using this adjusted set of grinding parameters, the surface of the workpiece is ground in the next method step, referred to as grinding 40.

[0048] If the comparison indicates that an adjusted set of grinding parameters does not need to be determined, the comparison module 36 preferably passes this information directly to the next grinding unit or electronic data processing device 20 and grinding 40 takes place immediately after the comparison.

[0049] The surface ground in this way is again subjected to an actual structure detection 34, the result of which is again compared in the comparison module 36 with the target structure, whereupon, if necessary, an adapted set of grinding parameters is determined in the adjustment module 38. Alternatively, grinding 40 is performed again without adjusted grinding parameters. The same module can be used several times as comparison module 36. Alternatively, different modules can be used as comparison module 36. This is particularly advantageous if different measured values and/or different parameters are used in order to use the actual structure and/or the respective target structure. The same applies to the adjustment module 38.

[0050] In the method sequence shown in FIG. 2, after the last grinding 40, the actual structure is again captured 34 and compared with the target structure in a comparison module 36. In this way, the grinding quality can be assessed and, for example, scrap can be detected. In a display step 42, the user of the grinding machine is shown how heavily the respective abrasive 4 is stressed and/or worn. This is preferably indicated as location-dependent information, preferably depending on the grinding width and/or depending on the position relative to the width of the abrasive.

[0051] In a final quality control 44, the last comparison of the actual structure with the target structure is used to assess whether the workpiece is a scrap. If this is not the case, the workpiece is sent for further processing 46, for example packaging. The method then ends 48.

[0052] All modules described are preferably part of the electronic data processing device 20 and are designed as software, i.e. computer program product.

LIST OF REFERENCE NUMBERS

[0053] 2 Grinding unit

[0054] 4 Abrasive

[0055] 6 Conveyor belt

[0056] 8 Arrow

[0057] 10 Pressure element

[0058] 12 Surface sensor

[0059] 14 Closing sensor

[0060] 16 Measuring sensor

[0061] 18 Signal line

[0062] 20 Electronic data processing device

[0063] 22 Input module

[0064] 24 Start

[0065] 26 Workpiece recognition

[0066] 28 Stress module

[0067] 30 Data memory

[0068] 32 Target structure module

[0069] 34 Actual structure detection

[0070] 36 Comparison module

[0071] 38 Adjustment module

[0072] 40 Grinding

[0073] 42 Display step

[0074] 44 Quality control

[0075] 46 Further processing

[0076] 48 End