Method of making a nest of cuts

Details Method of making a nest of cuts Method of making a nest of cuts

1998-08-19

2001-03-20

Sheikh, Ayaz R. (Department: 2781)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Product assembly or manufacturing

C700S139000, C700S150000, C700S161000, C700S171000, C700S230000, C700S259000, C700S135000, C382S111000, C083S936000, C083S937000, C083S938000, C083S939000, C083S940000, C083S941000

Reexamination Certificate

active

06205370

ABSTRACT:

This invention relates to a method of making a nest of cuts for cutting blanks out of flat, irregular workpieces, in particular leather skins, where the contour and the flaws of the workpieces spread on a supporting surface of a receiving means together with a workpiece characteristic and workpiece-specific quality features are detected by means of a digitizing unit, and the corresponding data are read into a computer, which on the basis of these data and the data stored in the computer concerning number, shape and quality requirements of the blanks calculates and stores a nest of cuts and utilizes the detected workpiece characteristics of the workpieces as a workpiece code for allocating the nests of cuts to the respective workpieces.
When cutting out blanks from leather pieces or other irregular flat pieces on an industrial scale, there should not only be achieved an optimum utilization of material, but also an economic nesting, where nesting is understood to be a combination of various blanks to a pattern individually adjusted to the respective workpiece in consideration of workpiece flaws such as holes, surface structure and color, stretching direction or the like. For automating such nesting it is known in accordance with U.S. Pat. No. 4,725,961 to digitize the contour of the workpiece by means of a computer and optically display the same on the screen of a layout unit, so that on the screen an interactive nesting can be effected by means of stored blanks. However, there is missing any direct relation of the nester to the skin, which along with the difficulty in optically detecting flaws and the like leads to unsatisfactory results and due to the necessity of interactively nesting all blanks also involves a lengthy nesting operation.
Corresponding to the DE-C-40 12 462, the U.S. Pat. No. 4,982,437 and the U.S. Pat. No. 5,089,971 it has also already been proposed to optically detect and digitize contour and flaws of a workpiece and for the preparation of a blank by calculation enter the corresponding data in a computer additionally fed with data concerning the blanks, where flaws and other quality features can also be marked manually for a better detection, and a detected workpiece characteristic of a workpiece can serve as workpiece code for the allocation of the calculated pattern to the respective workpiece for the subsequent cutting operation. In this case, however, the nest of cuts is prepared by the computer only for that workpiece area which the computer can recognize as free from flaws due to a marking or the optical resolution, so that above all workpiece areas having hardly recognizable flaws or quality deficiencies are disregarded and either by means of an extensive marking are excluded from the nest area in an uneconomic way, or by including them in the nest area can lead to rejects of the blanks.
In accordance with a further known computer-aided nesting the blanks are projected onto the workpiece by means of a projector connected to a computer, so that in the case of an up-right contact with the workpiece nesting can be effected interactively by manually controlling the projections and reading the workpiece-related position of the projections into the computer. The contact with the workpiece enables the nester himself to detect flaws and perform the nesting operation in consideration of such flaws, but due to the necessity of an interactive nesting of all parts such nesting is again rather time-consuming. In addition, there are illumination problems, as on the one hand the optical detection of the workpiece requires a bright enough illumination, but the projection of the blanks requires some darkening, which makes the detection of flaws more difficult for the nester and constitutes a health risk for his eyes due to the frequent change between bright and dark.
It is therefore the object underlying the invention to provide a method as described above, which ensures an economic nesting of the blanks by optimizing the detection and consideration of occurring flaws of the workpieces.
This object is solved by the invention in that before the automatic nesting on the part of the computer, nesting is effected interactively for selected partial areas of the workpieces, in that images of the blanks to be nested, which were provided by the computer and can optically be superimposed on the workpieces or an image of the workpieces, are positioned by specific control operations of the nester and are combined to partial nests within the partial areas, whereupon the computer calculates residual nests for the remaining residual areas of the workpieces, combines the residual nests with the associated partial nests and stores each of these combinations of partial and residual nests as nest of cuts for the individual workpieces.
When making the nest of cuts both the human capacities in the detection of flaws and the mathematical perfection of an automatic nesting can thus be utilized, and a cooperation of these two components optimally adjusted to the respective workpieces can be effected. When the nester detects areas in a spread workpiece with flaws or deficiencies that are hard to detect for the digitizing unit, he can nest interactively for these selected partial areas, where the computer provides suitable images of the blanks and superimposes the same on the workpiece or an image of the workpiece, and the nester brings these images in the desired nest position by means of specific control measures while maintaining the direct workpiece relation, and composes a partial nest which is specific for the selected partial area. This partial nest is stored in the computer, which then makes a residual nest for the remaining residual area of the flaws defined by the contour of the workpiece, the partial areas themselves and the flaws recognized by the computer and possibly marked in addition by the nester, so that by combining partial and residual nests for each workpiece a perfect nest of cuts is obtained, which together with the required workpiece characteristics is stored as workpiece code. For a subsequent cutting operation this nest of cuts then forms the basis for preparing a cutting program for cutting the blanks out of the associated workpiece to be identified by means of the workpiece code, where the workpiece contour and/or the marked flaws may very well serve as workpiece characeristics. The deliberate cooperation of interactive nesting and automatically calculated nesting leads to a quick nesting operation that minimizes the waste of material and optimally takes into account the specific properties of the workpiece.
It is particularly advantageous when in addition to the workpiece-related features also control means (e.g. the hand of a nester or manually operated sensors) provided on and/or above the workpiece and the control movements thereof can be detected by means of the digitizing unit and the data thus obtained can be transmitted to the computer, which provides the images of the blanks in dependence on these control data, superimposes the same on the workpiece or an image of the workpiece, positions the same and fixes the same in their position relative to the respective workpiece. In accordance with the invention, the digitizing unit, which may have an optical camera or another suitable scanner, is no longer merely used for recording the workpiece-related data concerning contour, flaws and the like characteristics and features, but at the same time becomes the control member for the interactive nesting, in that control means or control movements adjusted to the respective digitizing unit are used by the nester for displaying the partial area to be nested interactively, for displaying the blanks, for selecting and positioning these images, or for other measures facilitating the interactive nesting. The nester remains in contact with the workpiece, he can move and adjust control means on the workpiece, the movements themselves can be detected as control movements and be used for control purposes, and all kinds of control measures known in conjunction with electronic

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