Boots – shoes – and leggings
Patent
1987-03-16
1988-12-13
Lastova, John R.
Boots, shoes, and leggings
G05B 19403
Patent
active
047915765
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to U.S. patent application Ser. No. 37,678, filed concurrently with this application on Mar. 16, 1987.
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to an area cutting method and, more particularly, to an area cutting method for cutting the interior of an area bounded by a closed curve.
2. Description of the Related Art
Forms of numerically controlled machining include cutting in which the interior of an area bounded by a closed curve is hollowed out down to a predetermined depth, and die milling in which the interior of an area is die milled. In such machining, as shown in FIG. 9(A), an area cutting method is conventionally carried out by performing cutting along an (i-1)th cutting path PTi-1 in one direction (the direction of the solid line arrow), raising the tool a predetermined amount at the completion of cutting, then positioning the tool directly above a cutting starting point Ps on the next, or i-th, cutting path PTi, thereafter lowering the tool to the cutting starting point Ps, moving the tool along the i-th cutting path PTi in the direction of the solid line arrow, and subsequently repeating the above unidirectional cutting.
Another area cutting method shown in FIG. 9(B) includes, following completion of cutting along the cutting path PTi-1 of the (i-1)th cutting path, moving the tool from a cutting end point Pe to the cutting starting point Ps on the next, or i-th, cutting path, and thereafter performing cutting along the i-th cutting path PTi. Thus, cutting is performed back and forth in the direction of the arrows.
Still another area cutting method shown in FIG. 9(C) includes obtaining offset paths OFC1, OFC2, . . . OFCn offset by predetermined amounts with respect to a curve OLC of an external shape, and moving the tool successively along the offset paths.
However, with the first area cutting method based on unidirectional cutting, the tool must be positioned at the cutting starting point Ps on the i-th cutting path PTi after the completion of cutting along the (i-1)th cutting path PTi-1. This method is disadvantageous in that it results in a long tool traveling distance.
With the second cutting method based on reciprocative cutting, portions are left uncut. In order to cut the uncut portions, the tool must be moved along the external shape curve OLC at completion of the back-and-forth cutting, thereby necessitating both back-and-forth cutting control and cutting control along the shape of the external curve. Accordingly, this method is disadvantageous in that control is complicated. Further, if an area AR has concavities and convexities, as shown in FIG. 9(D), the second method requires movement for achieving positioning indicated by the dashed lines. This is disadvantageous in that tool travelling distance and cutting time are prolonged. In addition, since the cutting process for the outward trip is different from the cutting process for the return trip, cutting cannot be performed efficiently overall. It should be noted that the cutting processes referred to here indicate up cutting and down cutting processes. FIGS. 10(A), (B) show examples of the down cutting process, and FIGS. 10(C), (D) depict examples of the up cutting process. If the workpiece material has been decided, then a cutting method capable of cutting the workpiece efficiently is selected from the up cutting and down cutting processes. However, with the second method, the up cutting process [e.g. FIG. 10(A)] and the down cutting process [e.g. FIG. 10(C)] are always mixed, so that cutting cannot be performed efficiently.
With the third method of cutting along the offset paths, portions are left uncut at, e.g., the central portion of the area, depending upon the contour of the external shape curve. This method is disadvantageous in that dealing with these uncut portions is a complicated task.
Accordingly, in order to eliminate the aforementioned drawbacks of the conventional method, the applicant has proposed a method in which a tool
REFERENCES:
patent: 3766369 (1973-10-01), Watanabe et al.
patent: 4503493 (1985-03-01), Burkhart et al.
patent: 4621959 (1986-11-01), Kishi et al.
patent: 4689750 (1987-08-01), Kishi et al.
Onishi Yasushi
Tanaka Kunio
Fanuc Ltd
Lastova John R.
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