Boots – shoes – and leggings
Patent
1987-03-17
1988-08-16
Smith, Jerry
Boots, shoes, and leggings
364170, 318572, G05B 1900
Patent
active
047648783
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a surface cutting method and, more particularly, to a surface cutting method for cutting a surface within an area bounded by a closed curve by moving a tool along a cutting path in a predetermined direction to cut the surface within the area, thenceforth moving the tool along an adjacent cutting path, obtained by a shift of a predetermined amount, in a direction opposite the predetermined direction to cut the surface, and repeating such two-way cutting.
BACKGROUND ART
A form of numerically controlled machining is one in which there is an area bounded by a closed curve, wherein surface cutting is applied to a portion (convex portion) projecting from an area on the outer side of the closed curve.
Such an area cutting (surface cutting) method includes the following steps:
(a) inputting data specifying a closed curve CCL of an area AR shown in FIG. 7, cutting direction (direction of arrow A) along cutting path PT.sub.i (i=1, 2, . . . ), shift direction (direction of arrow B) in which a tool TL is shifted by a predetermined amount of cut-in whenever surface cutting along the cutting path PT.sub.i ends, and cut-in amount P;
(b) generating the cutting path PT.sub.i on the basis of the inputted data;
(c) performing cutting by moving the tool along the cutting path PT.sub.i from a cutting starting point P.sub.i to a cutting end point Q.sub.i on the generated cutting path PT.sub.i ;
(d) obtaining the next cutting path PT.sub.i+1, which results when the tool is shifted by the amount of cut-in P following the end of cutting along the preceding cutting path;
(e) thereafter performing cutting (unidirectional cutting) by moving the tool from point P.sub.i+1 to point Q.sub.i+1, in which point P.sub.i+1 is taken as the cutting starting point of cutting path PT.sub.i+1 and point Q.sub.i+1 is taken as the cutting end point of cutting path PT.sub.i+1, or performing cutting (back-and-forth cutting) by moving the tool from point Q.sub.i+1 to point P.sub.i+1, in which point Q.sub.i+1 is taken as the cutting starting point of cutting path PT.sub.i+1 and point P.sub.i+1 is taken as the cutting end point of cutting path PT.sub.i+1 ; and
(f) repeating the unidirectional or back-and-forth cutting operation from this point onward to surface-cut the area AR. When cutting must be carried out by an up-cut or down-cut method, which depends upon the workpiece, surface cutting is performed unidirectionally. If the up-cut/down-cut method need be taken into consideration, surface cutting is performed by back-and-forth cutting.
In the conventional surface cutting method, the cutting starting point and end point of each cutting path PTi (i=1, 2, . . . ) are set fairly remote from the area boundary line so as not to leave any portions uncut. This results in a long tool pass along each cutting path, namely in a lengthy period of time during which surface cutting is not carried out. Consequently, machining efficiency is poor.
Accordingly, an object of the present invention is to provide a surface cutting method through which tool pass can be shortened without leaving portions uncut.
Another object of the present invention is to provide a surface cutting method through which a portion projecting from an area can be cut away in a reliable manner.
DISCLOSURE OF THE INVENTION
The present invention provides a surface cutting method for back-and-forth surface cutting of the interior of an area bounded by a closed curve.
The surface cutting method includes repeating the following steps:
a step of obtaining points of intersection P.sub.i, Q.sub.i between an i-th cutting path and an offset curve offset by (T+C+R) to the outer side of the closed curve, as well as points of intersection P.sub.i+1, Q.sub.i+1 between the offset curve and an (i+1)th cutting path, where T, C and R represent excess thickness, amount of clearance and tool radius, respectively;
a step of obtaining a coordinate value, in the cutting path direction, of an outermost point R.sub.i on the offset curve between the points of intersection Q.
REFERENCES:
patent: 4621959 (1986-11-01), Kishi et al.
patent: 4706200 (1987-11-01), Kishi et al.
patent: 4706201 (1987-11-01), Kishi et al.
Onishi Yasushi
Tanaka Kunio
Fanuc Ltd
MacDonald Allen
Smith Jerry
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