Method for determining the accuracy of processing machines

#The present application hereby claims priority under 35 U.S.C. §119 on German patent application number DE 10206183.1 filed Feb. 14, 2002, the entire contents of which are hereby incorporated herein by reference.

#The invention generally relates to a method for determining the accuracy of processing machines, in particular of laser processing machines.

#Precision machining or processing of objects using laser processing machines requires regular checking of the accuracy with which the laser beams used for the processing are directed onto the object to be processed. When verifying accuracy in such a way, it is customary within a test program for a test object to be processed in such a way that what are known as test markings are provided at predetermined points. Since a certain amount of material is removed each time from the test object during material processing by use of laser beams, the provision of test marks is also referred to as structuring the test object with test marks. Once the test marks have been structured, the test object is removed from the laser processing machine and measured by what is known as a measuring machine. In it, the exact spatial positions of the test markings provided are recorded, and consequently the accuracy of the laser processing machine is determined. In this case, the deviation of the actual position from the set-point position of a test marking is a direct measure of the accuracy of the laser processing machine. Usually used as a test object is what is known as a test plate, which is produced either from glass or from printed circuit board material. A test plate made of printed circuit board material is used in particular whenever the laser processing machine of which the accuracy is to be determined is intended for structuring, drilling or otherwise processing printed circuit boards.

#Further advantages and features of the present invention emerge from the following description by way of example of a currently preferred embodiment.

#FIG. 1 shows the arrangement of reference marks and test marks in the entire working area of a laser processing machine and

#FIG. 2 shows a detail of the working area represented in FIG. 1.

#FIG. 1 shows a plan view of a complete processing area of a laser processing machine for which accuracy verification is carried out according to an exemplary embodiment of the invention. On a vacuum table 100 lies a reference plate 110, which is sucked firmly onto the vacuum table 100 by a negative pressure, which is generated by a multiplicity of suction channels (not represented) formed on the vacuum table 100. Above the reference plate 110 lies a test plate 120. The fixing of the test plate 120 in relation to the reference plate 110 and in relation to the vacuum table 100 is ensured by the reference plate 110 having a multiplicity of vacuum through-holes 111, through which the negative pressure transferred by the suction channels of the vacuum table 100 can be applied to the underside of the test plate 120. The fixing of the test plate 120 and of the reference plate 110 on the vacuum table 100 by means of negative pressure has the advantage that the negative pressure can be quickly applied and also quickly switched off again by switching corresponding pressure valves, with the result that the reference plate 110 and the test plate 120 can be fixed on the vacuum table quickly and reliably and removed again from the vacuum table 100 similarly quickly.

#It is pointed out that other temporary fastening methods, such as for example clamping, screwing, adhesive bonding or magnetic fixing, may also be used for the spatial fixing of the reference plate 110 and the test plate 120. Similarly, it is conceivable for the reference plate 110 and the test plate 120 simply to be placed one on top of the other, in which case, to avoid an unwanted change in position, attention should be paid not only to a mounting that has as little vibration as possible but also to a certain minimum weight of the plate lying on top and a high coefficient of static friction between the two plate surfaces facing each other.

#According to the exemplary embodiment represented in FIG. 1, on the reference plate 110 along with the vacuum through-holes 111 there are a plurality of reference marks 112, which are arranged on a square grid. It is pointed out in this connection that the reference marks 12 can of course be provided on the reference plate 110 in any other desired arrangement. The test plate 120, which is produced from an opaque material, has a multiplicity of bores 121, which are arranged in such a way that, given a corresponding relative position between the reference plate 110 and the test plate 120, the reference marks 112 provided on the reference plate 110 can be seen.