Research Of Tangent Interpolation In CNC Leather-cutting

Leather is cut by impulse of punch at present, which demands the worker's proficiency and has adverse working environment. Leather-cutting machine abroad is advanced, but it isn't accepted by most corporations in China because of high price and technical privacy protection. In order to research CNC leather-cutting machine owning intellectual property right, tangent interpolation as its core technology is researched in this thesis.Work principle of leather-cutting machine, technics flow of leather-cutting are introduced and its motion is analysed, then tangent motion is advanced. Overall scheme of the control system are designed.Tangent interpolation algorithms on line, arc and ellipse are researched and simulated. The result shows that these algorithms meet demand of tangent motion, and interpolation error meets demand of leather-cutting. Tangent interpolation on arc based on equal step angle and on ellipse based on equal centrifugal step angle can use the same formula for different quadrants.Self-adaptive tangent interpolation algorithm on NURBS curve is proposed and researched. It is realized by controlling increment of C axis and normal acceleration. The simulation result shows increment of C axis can be controlled and distortion of the cutter is decreased.As the cutter is strip shape, cutter offsetting is researched in the thesis. In order to solve the overcut problem when cutting inner concave curve, cutting strategy based on overcut error control is advanced and researched, and the flow of this algorithm is given.Cutting control software is researched in the thesis. In order to identify common curve in DXF file such as line, arc, ellipse and NURBS curve, DXF file interface module is designed, which is realized by programming with VC++.