Method of realizing cutter path parameter arc length based on three times of PH curve interpolations

Abstract

The invention discloses a method of realizing a cutter path parameter arc length based on three times of PH curve interpolations. The method comprises the following steps of (1) using three times of PH curves to carry out local interpolation on two adjacent data points, acquiring several three-times PH curves and using a set of PH curves between the adjacent data points to form an interpolation curve; (2) converting the interpolation curve into one integral B spline curve, and carrying out isoparametric sampling on the integral B spline curve; (3) calculating an arc length parameter of a sampling point and establishing a target function taking the arc length parameter as a variable; (4) using an ELSPIA algorithm to solve the target function, and acquiring a B spline of an approximation parameter arc length. By using the parameter arc length method, the isoparametric sampling is performed on the integral B spline curve, cutter path B spline fitting algorithm efficiency is increased, the parameter arc length is realized, a speed fluctuation during processing is reduced and phenomena of a shape defect of a cutter path and error dissatisfaction are effectively improved.

Description

technical field [0001] The invention belongs to the technical field of material mechanics, and more specifically relates to a method for realizing the arc length of tool trajectory parameters based on cubic PH curve interpolation. Background technique [0002] At present, the tool trajectory of NC machining is usually expressed by small line segments, and the small line segments are obtained by discretizing the original surface according to the machining error by CAM software. The small line segment indicates that the tool path has the following disadvantages: (1) The number of small line segments is huge, and the amount of data storage and transmission is large; (2) The tool path only has G0 continuity, G1 and G2 are discontinuous, and the system frequently accelerates and decelerates, which is easy to cause machine tool failure. Vibration reduces the machining accuracy and surface quality of the parts; (3) The smoothness of the tool path is poor, and the machining accuracy...

AI Technical Summary

Problems solved by technology

The small line segment indicates that the tool path has the following disadvantages: (1) The number of small line segments is huge, and the amount of data storage and transmission is large; (2) The tool path only has G0 continuity, G1 and G2 are discontinuous, and the system frequently accelerates and decelerates, which is easy to cause machine tool failure. Vibration reduces the machining accuracy and surface quality of the parts; (3) The smoothness of the tool path is poor, and the machining accuracy and surface quality of the parts contour are poor

First, a non-parametric arc-length B-spline tool trajectory is decomposed into several Bezier line segments, and then these Bezier line segments are sampled to calculate the arc length of the sampling points, and finally the least squares method is used to fit these sampling points to obtain a parametric arc Lengthened B-spline curve; however, there is no analytical solution when calculating the arc length of the cubic Bezier curve, and the arc length can only be calculated by numerical integration method, which cannot be accurately calculated

[0007] The article "Arc-length parameterized spline curves for real-time simulation" discloses the calculation of the segmented arc length of the input cubic B-spline, and then finds several uniformly distributed sampling points on the spline according to the arc length, and uses the dichotomy method Calculate the parameters of the sampling points, and finally construct an interpolation curve to pass through these sampling points; but the arc length of the cubic B-spline curve can only be calculated by the numerical integration method, and cannot be accurately calculated

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