Area cutting method

• US 4,706,200 A
• Filed: 08/13/1985
• Issued: 11/10/1987
• Est. Priority Date: 12/14/1983
• Status: Expired due to Fees

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Seki, Masaki, Takegahara, Takashi, Kishi, Hajimu
• Primary Examiner(s): Ruggiero, Joseph
• Application Number:
  US06/768,118
• Time in Patent Office: 819 Days
• Field of Search: 364/474, 364/475, 364/167-171, 318/572
• US Class Current: 700/187
• CPC Class Codes: G05B 19/41 characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/49157 Limitation, collision, interference, forbidden zones, avoid obstacles
• CPC Class Codes: G05B 2219/49381 Raster, line servo, area machining, cutting, facing

Abstract

The present invention relates to an area cutting method for cutting an area (AR) delimited by a curve (OLC) of an external shape and at least two closed curves (INC₁, INC₂) which lie within the curve of the external shape. The area cutting method has a step of calculating first and second offset curves (INF₁, INF₂) offset outwardly from the respective closed curves (INC₁, INC₂) by an amount dependent upon tool diameter, a step of checking whether the offset curves intersect each other, a step of ascertaining that an overlap portion (CSA) incapable of being area-cut exists when the offset curves intersect each other, and a step of cutting only an area from which the portion (CSA) incapable of being area-cut is omitted when the overlap portion exists.

Claims

1. An area cutting determining method for determining an area for cutting delimited by a curve of an external shape and at least two closed curves which lie within said curve of the external shape, comprising the steps of:

producing offset curves outwardly from respective ones of said closed curves by an amount dependent upon tool diameter;

checking whether the offset curves intersect one another;

ascertaining that an overlap portion incapable of being area-cut exists when the offset curves intersect one another;

entering area cutting data necessary for performing area cutting based on unidirectional cutting or back-and-forth cutting including a cutting path shift direction and a shift amount;

producing a straight line, which specifies an i-th cutting path PTi, from the cutting path shift direction and the shift amount contained in said area cutting data;

obtaining points Pi, Qi at which said straight line intersects an offset curve obtained by inwardly offsetting the curve of the external shape, and point Ri, Si;

Ti, Ui at which said straight line intersects each of said offset curves, respectively; and

cutting an area from which said overlap position incapable of being area cut is omitted by;

moving the tool in a cutting-feed mode along the i-th cutting path from the machining starting point Pi to the intersection point Ri;

moving the tool in the cutting-feed mode along an offset curve containing said intersection point Ri;

moving the tool in the cutting-feed mode along the i-th cutting path after arrival thereat when the tool arrives at the i-th cutting path before arriving at a different offset curve;

moving the tool along the other offset curve after arrival thereat when the tool arrives at a different

moving the tool along the i-th cutting path to the machining end point Qi.