CN-116661372-B - Milling cutter track generation method

CN116661372BCN 116661372 BCN116661372 BCN 116661372BCN-116661372-B

Abstract

The invention relates to a milling cutter track generation method, which comprises the following steps of S1, encoding a cutter motion path of a non-expandable straight line surface of five-axis side milling machining according to a five-axis side milling kinematics principle to determine a cutter pose at any moment in a non-expandable straight line curved surface machining tool position track, S2, obtaining an initial cutter path according to differential geometry and related mathematical knowledge, S3, carrying out self-adaptive interpolation on a cutter center point track curve, a course angle parameter curve and an inclination angle curve in the initial cutter path by using a de Casteljau interpolation algorithm to continuously update three curves, S4, continuously iterating the number and the position of relevant curve control points of the cutter track by using an electromagnetic-like mechanism random optimization method until the iteration is finished to the maximum iteration times, and S5, taking the track curve of the last iteration as a final cutter track curve. The high-order continuity along the path track of the straight-line curved-surface tool is realized, and the overall processing quality and the processing efficiency are improved.

Inventors

LIU GANG
LI ZHONGPENG
ZHANG LIQIANG
YANG QINGPING
Dai Shifei

Assignees

成都永峰科技有限公司
上海工程技术大学
上海交通大学四川研究院

Dates

Publication Date: 20260512
Application Date: 20230526

Claims (5)

1. A method for generating a five-axis side milling continuous tool path track of a non-expandable straight grain surface is characterized by comprising the following steps: Step S1, coding a cutter motion path of a non-expandable straight grain surface machined by five-axis side milling according to a five-axis side milling kinematics principle to obtain a cutter point coordinate and a cutter axis vector course angle under a single cutter position And inclination angle ; The coding steps are as follows: step 1.1 representing the center point of the tool, wherein the track of the center point of the tool is recorded as ; Step 1.2 representing the cutter shaft vector, namely, the course angle for the posture of the cutter shaft And inclination angle Representing the course angle and the inclination angle along with the parameters of the lead Is changed continuously, the course angle is changed And inclination angle Expressed as a function of curve parameters, respectively noted as And ; Step S2, under the condition that an upper lead equation and a lower lead equation of a non-expandable straight line surface are known, calculating expressions of quasi-lines, which are connected with corresponding two points, of parameters such as the upper lead and the lower lead of the straight line surface, and calculating an initial cutter path; the generation of the initial tool path includes the steps of: step 2.1, spline equations of the upper and lower guidelines of the non-expandable straight line surface are respectively And In the process that the cylindrical cutter sweeps along the non-expandable straight line surface, the cutter and the non-expandable straight line surface are aligned Generating a series of contact points, and recording the contact point set formed by the contact points as (PiA, i), wherein the corresponding curved normal vector set and the corresponding standard line vector set of the non-expandable vein surface at the contact points are respectively recorded as And ; Step 2.2, a series of contact point sets (PiA, i) of the tool on the lower alignment in contact with the non-expandable ruled surface are offset by a tool radius along the normal to the non-expandable ruled surface at the corresponding contact point Obtaining a series of discrete tool path track center points ; Step 2.3, fitting the discrete tool center points obtained after the contact point offset by adopting a cubic spline function to obtain a complete tool center point track curve equation The method comprises the following steps: ; Wherein, the The least square method is adopted in the solving process for the control points of the fitted cubic spline function; Step 2.4, solving the control points of the fit cubic spline function by adopting a least square method so as to minimize the square sum of the distances between the fit spline parameter curve and the center points of the discrete tool, wherein the error function can be expressed as The optimal objective function of the cubic spline function fitting is ; Step 2.5 solving the coordinate system of the machine tool Course angle of middle cutter shaft vector And inclination angle Since the CLS file is in the object coordinate system The tool axis vector in the workpiece coordinate system is required to be converted into the machine tool coordinate system through the inverse kinematics transformation; Step S3, performing self-adaptive interpolation on a tool center point track curve, a course angle parameter curve and an inclination angle curve in an initial tool path by using a de Casteljau interpolation algorithm, and continuously updating three curves; The curve control points are adaptively added by using the de Casteljau algorithm, and the continuous iteration tool path comprises the following steps: step 3.1 by equation The Bezier curve is obtained and the method comprises the steps of, Wherein, the Is a control point of the curve; Step 3.2, subdividing the Bezier curve into two sections by using a de Casteljau interpolation algorithm, and passing through an equation Obtaining a specific segmentation method; step 3.3, dividing the third-order Bezier curve into two sections by the dividing method, wherein the control points are the control points of the first section respectively And a second control point : Step 3.4, maintaining the segmented two-segment Bezier curve at the break point The constraint of continuity is that ; Wherein a is a proportional coefficient; step S4, continuously iterating the number and the positions of the control points of the tool path related curve by using a similar electromagnetic mechanism random optimization method until the iteration is carried out to the maximum iteration times, and ending the search; The electromagnetic mechanism-like random optimization method continuously searches the number of optimal control points, and continuously iterates the cutter path to comprise the following steps: initializing, namely randomly generating m sample points in an N-dimensional space by using a quasi-electromagnetic mechanism random optimization method, wherein each sample point corresponds to one particle in the quasi-electromagnetic mechanism random optimization method, and the dimension of the particle is 3N; Wherein N is the number of discrete tool positions in the tool path track; step 4.2 local search of optimal solution given two local random search parameters LSITER and Representing the local search iteration number and the multiplier respectively; Step 4.3 calculating the total force applied to each charged particle and the total charge of particle i Is that The total force applied to the particles i is : Wherein, the For the optimal solution in the iterative process, At the objective function The value at which the expression of the objective function is : Wherein, the Is the geometric error between two adjacent tool positions; step 4.4 displacement of particles in force The charged particles will generate displacement by the formula of ; Step 4.5, obtaining a final optimal solution; And S5, taking the track curve of the last iteration as a final tool path track curve.
2. The method for generating a five-axis side milling continuous tool path trace of a non-expandable straight line surface according to claim 1, wherein in the step S5, the optimal solution in the step 4 is taken as the tool path trace of the optimized non-expandable straight line surface.
3. The method for generating the five-axis side milling continuous tool path track of the non-expandable straight line surface according to claim 2, wherein curve parameters corresponding to contact points in the contact point set (PiA, i) are uniformly distributed.
4. The method for generating a five-axis side milling continuity tool path trace of a non-expandable ruled surface as set forth in claim 3, wherein said arbor vector is converted into a conversion formula for no loss of generality , : Wherein, the A six-cell array coordinate in a workbench coordinate system for a workpiece coordinate system; representing the position of the tool nose point coordinate and the tool shaft vector in the workpiece coordinate system respectively; Representing the representation of the tool pose in the machine tool coordinate system; Represents a rotation matrix of Angle of rotation about Axis, The expressions representing the translation matrix, the rotation matrix and the translation matrix are Rot (X, a), trans (X0 y0 z 0), respectively: , And obtaining an initial tool position path representation under a machine tool coordinate system through the rotation matrix and the translation matrix.
5. The method for generating the five-axis side milling continuous tool path track of the non-expandable straight line surface according to claim 3, wherein the sample points in the step 4.1 are uniformly distributed, and the sample points are equal to the parameter intervals corresponding to the upper and lower wires.

Description

Milling cutter track generation method Technical Field The invention relates to the technical field of machining, in particular to a method for generating a milling cutter track. Background Nowadays, with the development of various fields such as aerospace and carrying, the demand for excellent high-end equipment is more and more urgent, and precise complex curved surface parts widely applied to the fields are more and more required in terms of indexes such as processing efficiency, forming precision and yield. The non-expandable straight line curved surface is a typical characteristic of the complex part, and is generally processed by a multi-axis linkage numerical control machine tool, the multi-axis linkage numerical control processing needs the support of an automatic programming technology, and the cutter path planning method is used as a core technology of automatic programming, so that the processing quality and the processing efficiency of the curved surface are determined by the advantages and disadvantages of the cutter path planning method. The non-expandable striation surface is formed by sweeping a bus bar along a conducting wire, and is non-expandable. Because the non-expandable straight grain surface has a torsion angle, namely, each normal vector on the straight bus has an included angle, a principle error can be inevitably generated in the side milling process, and how to reasonably plan the tool path track becomes important. In order to solve the problems, the invention provides a milling cutter track generation method. Disclosure of Invention The invention aims to provide a milling cutter tool path track generation method, which realizes high-order continuity along the straight-line curved surface tool path track and improves the overall processing quality and the processing efficiency. In order to achieve the above purpose, the present invention provides the following technical solutions: A method for generating a five-axis side milling continuous tool path track of a non-expandable straight grain surface comprises the following steps: Step S1, coding a cutter motion path of a non-expandable straight grain surface of five-axis side milling according to a five-axis side milling kinematics principle to obtain a cutter point coordinate, a course angle of a cutter axis vector and an inclination angle of a single cutter position; Step S2, under the condition that an upper lead equation and a lower lead equation of a non-expandable straight line surface are known, solving an expression of a quasi-line connected with two points corresponding to parameters such as the upper lead and the lower lead of the straight line surface, and solving an initial cutter path according to differential geometry and related mathematical knowledge; Step S3, performing self-adaptive interpolation on a tool center point track curve, a course angle parameter curve and an inclination angle curve in an initial tool path by using a de Casteljau interpolation algorithm, and continuously updating three curves; Step S4, continuously iterating the number and the positions of the control points of the tool path related curve by using a similar electromagnetic mechanism random optimization method until the iteration is completed to the maximum iteration times; And S5, taking the track curve of the last iteration as a final tool path track curve. Further, in the step S1, the tool motion path is encoded according to the principle of five-axis side milling kinematics, so as to determine the tool pose at any moment in the tool position track of the non-expandable straight line curved surface processing, and the method is characterized by comprising the following steps: step 1.1 representing the center point of the tool, wherein the track of the center point of the tool is recorded as ; Step 1.2 representing the cutter shaft vector, namely, the course angle for the posture of the cutter shaftAnd inclination angleRepresenting the course angle and the inclination angle along with the parameters of the leadIs changed continuously, the course angle is changedAnd inclination angleExpressed as a function of curve parameters, respectively noted asAnd。 Further, in the step S2, the generating of the initial tool path includes the following steps: step 2.1, spline equations of the upper and lower guidelines of the non-expandable straight line surface are respectively AndIn the process that the cylindrical cutter sweeps along the non-expandable straight line surface, the cutter and the non-expandable straight line surface are alignedGenerating a series of contact points, and recording the contact point set formed by the contact points as (PiA, i), wherein the corresponding curved normal vector set and the corresponding standard line vector set of the non-expandable vein surface at the contact points are respectively recorded asAnd; Step 2.2, a series of contact point sets (PiA, i) of the tool on the lower alignment in contact with the non-e