CN-120461184-B - Digital twinning-based complex blade type cutter machining process chatter prediction method

CN120461184BCN 120461184 BCN120461184 BCN 120461184BCN-120461184-B

Abstract

The invention discloses a method for predicting flutter of a complex blade type cutter in a machining process based on digital twinning, which comprises the following steps of S1, simulating the milling process of the complex blade type cutter based on a digital twinning model, obtaining a meshing area CWE of the cutter and a workpiece in the machining process, S2, dispersing the rotation period of the cutter and the cutting edge participated in cutting, extracting meshing information of the cutter and the workpiece in the machining process, combining the property of a machined material and the dynamic characteristic of the cutter, calculating and obtaining a flutter stability lobe diagram of the complex blade type cutter under a given working condition, S3, comparing the stability lobe diagrams of different blade type cutters, and selecting an optimal blade type cutter under the given working condition. According to the method for predicting the flutter of the complex blade type cutter machining process based on digital twin, the stability lobe diagram is drawn through calculation and analysis of the rotation period of the discrete cutter and the cutter edge and combination of materials and cutter characteristics based on the digital twin model.

Inventors

SHEN BIN
AI DI
WANG CHENGHAN
YUE TING
CHEN SULIN
JIN SUN

Assignees

上海交通大学

Dates

Publication Date: 20260508
Application Date: 20250418

Claims (5)

1. A method for predicting chatter in a machining process of a complex blade type cutter based on digital twinning is characterized by comprising the following steps: s1, simulating a milling process of a complex blade type cutter based on a digital twin model, and obtaining a meshing area CWE of the cutter and a workpiece in the machining process; s2, dispersing the rotation period of the cutter and the cutting edge which participates in cutting, extracting meshing information of the cutter and a workpiece in the machining process, and calculating to obtain a flutter stability lobe diagram of the complex-edge cutter under a given working condition by combining the property of the machined material and the dynamic characteristic of the cutter; S3, comparing the stability lobe diagrams of the different blade type cutters, and selecting an optimal blade type cutter under a given working condition; S2, calculating a flutter stability vane diagram of the complex blade type cutter, wherein the calculating process comprises the following steps: extracting discrete steps in any single period by using the obtained CWE information of the meshing area in the machining process, and calculating the time rotation angle, the helix angle and the cutter shaft included angle of all cutting edge infinitesimal under each discrete step; calculating a cutting force coefficient matrix under each discrete step, carrying out zero-order processing on the cutting force coefficient matrix in a period, and counting the cutting times and time lag angles of all cutting edge microelements in the period; setting the range of the vibration frequency according to the natural frequency of the cutter, dispersing, and calculating cutter response functions, cutter rotating speeds and critical stable cutting widths under all the vibration frequencies by combining with CWE information; and (5) drawing images of critical stable cutting width relative to the rotating speed of the cutter at all the chatter frequencies, namely a stable lobe diagram.
2. The method for predicting the chatter of the machining process of the complex blade type cutter based on digital twin according to claim 1, wherein in S1, the milling process of the complex blade type cutter is simulated based on a digital twin model, and an engagement area CWE of the cutter and a workpiece in the machining process is obtained, and the method comprises the following specific steps: firstly, representing the space information of a workpiece by using tri-dexel, namely, using dense lines to penetrate the workpiece from xyz three directions in space, and representing the line segment formed by each line and two points of the workpiece penetrating and penetrating; Secondly, inputting a numerical control nc code into a digital twin system, namely inputting the motion pose of the cutter and the space information of the workpiece into the digital twin system together to obtain a meshing area CWE of the cutter and the workpiece in the machining process.
3. The method for predicting the chatter of the machining process of the complex blade type cutter based on the digital twin according to claim 1, wherein the step S2 comprises the following steps of performing stability analysis based on a stability analysis model of a standard milling cutter: the milling stability analysis is carried out by selecting a four-edge standard milling cutter, and in the milling process of a non-thin-wall workpiece, the vibration amplitude of the workpiece is smaller than that of a cutter, so that the cutter has vibration degrees of freedom in the x and y directions respectively when the workpiece is regarded as a rigid body; let the cutting thickness of the j-th edge along the normal direction of the edge in the milling process be , wherein, For the rotation angle of the j-th edge at this moment, this rotation angle is resolved into x and y directions And , And The expression of (2) is as follows: (1); (2); Wherein, the Representing the vibration component of the j-th blade in the x-direction, Representing the vibration component of the j-1 th blade, i.e., the last blade, in the x direction; According to the stability analysis theory, the relation between the cutting force and the cutting thickness of the cutter along the x and y directions is expressed as follows: (3); Wherein, the For the axial depth of cut, The dynamic cutting force coefficient matrix is responsible for projecting the force born by the cutter in the cutting process to the x and y directions; for dynamic cutting force coefficient matrix And (3) expanding the Fourier series and taking a zeroth order term to obtain: ; assuming that there is no coupling in the degrees of freedom of the tool in the x and y directions, the vibration displacement in the x-direction frequency domain is related to the cutting force as: (4); Wherein, the For the frequency of the vibration to be high, As a frequency response function in the x direction of the cutter, the formula (4) is replaced by the formula (3), and zero order processing is carried out to obtain: (5); solving the formula (5) to obtain: (6); Wherein, the Represents the critical stable cutting width of the cutting tool, Representation of Is used for the real part of (c), Representation of Is used to determine the imaginary part of (c), For standard milling cutters, at selected chatter frequencies The critical stable cutting width was then calculated.
4. The method for predicting the chatter of a complex blade type cutter machining process based on digital twinning according to claim 3, wherein the step S2 comprises discretizing all blades of the milling cutter based on a digital twinning model of the generalized milling cutter, and comprises the following specific steps: extracting relevant information of a blade micro element meshed with a workpiece at any moment, wherein the relevant information comprises tangential direction, normal direction, cutting thickness and cutter rotating speed information of the blade micro element under a workpiece coordinate system; And analyzing the stability of the current milling working condition by extracting the related information of all blade infinitesimal in one cutter rotation period, and predicting the stability of the five-axis milling process of the ball end milling cutter with unequal helix angles or the cylindrical milling cutter with unequal pitches.
5. The method for predicting the flutter of the machining process of the complex blade type cutter based on digital twinning according to claim 4, wherein the step S2 is further characterized by further comprising the step of carrying out flutter stability analysis of the ball-end cutter based on a stability analysis model of a generalized milling cutter, and comprises the following specific steps: In the digital twin model, one rotation period T is discretized into n parts, The cutting width of each blade element along the cutter shaft direction is Each one by Calculating the information of all the cutting edge infinitesimal once, then calculating the information of the formula (5) After zero-order matrix processing, formula (5) is rewritten as: (7); Wherein: (8); Wherein, the Indicating the number of blade infinitesimal currently participating in cutting, Is the helix angle of the blade, For the rotation angle on the ith blade element, Is the included angle between the ith blade infinitesimal and the xy plane; Assuming that the frequency response functions in the x and y directions of the tool are identical and not coupled to each other, equation (6) is substituted back into equation (7) and aligned in one tool rotation period And (5) calculating an average value of the matrix to obtain: (9); taking into account the resulting multiple time delays of unequal pitch cylindrical mills or unequal helix angle cylindrical mills, according to the Floquet stability theory, equation (9) satisfies the following equation in the critical stability case: (10); Assume that , wherein, Representing the tooth passing period of the ith blade element, namely the time delay from the current blade to the last blade; Selecting the frequency of vibration to be scanned For each of the ranges of (a) Respectively calculating corresponding rotating speeds The specific calculation process comprises the following steps: (11); Wherein, the The number of edge elements involved in cutting during the rotation period of the tool is indicated, Representation of Is used to determine the imaginary part of (c), Representation of In determining the real part of (2) Then obtaining the rotating speed through a formula (11); each is then obtained by calculation of (10) Lower critical cutting depth Thereby obtaining a series of% , ) A point pair; and connecting all the point pairs to obtain a stable lobe diagram of the arbitrary blade milling cutter in the five-axis or three-axis milling process, and completing stability analysis of cutters with different blade types under specific working conditions.

Description

Digital twinning-based complex blade type cutter machining process chatter prediction method Technical Field The invention relates to the technical field of intelligent manufacturing, in particular to a method for predicting chatter in a machining process of a complex blade type cutter based on digital twinning. Background Chatter problems during machining are major limiting factors in improving material removal rates, productivity, surface quality, and dimensional accuracy of the machined parts. Vibration atmosphere forced vibration and self-excited vibration in the machining process, wherein chatter belongs to self-excited vibration, and the cutting thickness and the cutting force which are changed in the cutting process are mutually excited, so that the vibration is the vibration which has the greatest damage to the machine tool structure and the quality of the machined surface and is most difficult to control in the vibration problem. In machine tool processing, particularly processing of materials with high hardness, the cutter blade shape has a significant influence on the suppression effect of chatter vibration. The current chatter prediction method in the milling process mainly comprises an analytic method, a semi-discrete method, a full-discrete method and a numerical method, wherein the semi-discrete method, the full-discrete method and the numerical method have higher precision, but have high calculation cost, and the result is generally used for experimental verification and effect comparison of the analytic method. The initial analysis method is only suitable for predicting the chatter vibration of the machining process of the constant-pitch vertical milling cutter, the chatter vibration of the milling process of the non-standard edge type cutter with variable pitch or variable screw angle and the like cannot be judged, and along with the theoretical research and expansion of students for years, the chatter vibration of the machining process of the cutter with variable pitch and variable screw angle can be predicted gradually. However, the known flutter prediction method is still limited to the conventional variable helix angle and variable pitch cutters, and flutter prediction and stable leaf pattern drawing cannot be performed under the condition that the helix angle of the cutting edge can be changed along the cutter shaft at will, so that the cutting edge design cannot be performed in a wider cutting edge space. The method is characterized in that the flutter prediction in the machining process of the complex blade type cutter based on digital twinning can draw a stable lobe diagram of any blade type cutter, and the optimal blade type of the cutting cutter under a specific working condition is guided to be selected on the premise of designability. Disclosure of Invention The invention aims to provide a method for predicting the flutter of a complex blade type cutter in the machining process based on digital twinning, which can acquire a flutter stable vane map of the complex blade type cutter under a given working condition and realize the optimal blade type selection and reverse design of the cutting cutter under a specific working condition by comparing the stable vane maps of different blade type cutters. In order to achieve the above purpose, the invention provides a method for predicting the chatter of a complex blade type cutter in the machining process based on digital twinning, which comprises the following steps: s1, simulating a milling process of a complex blade type cutter based on a digital twin model, and obtaining a meshing area CWE of the cutter and a workpiece in the machining process; s2, dispersing the rotation period of the cutter and the cutting edge which participates in cutting, extracting meshing information of the cutter and a workpiece in the machining process, and calculating to obtain a flutter stability lobe diagram of the complex-edge cutter under a given working condition by combining the property of the machined material and the dynamic characteristic of the cutter; S3, comparing the stability lobe diagrams of the different blade type cutters, and selecting the optimal blade type cutter under a given working condition. Preferably, in S1, a milling process of a complex blade type cutter is simulated based on a digital twin model, and a meshing area CWE of the cutter and a workpiece in a machining process is obtained, which specifically includes: firstly, representing the space information of a workpiece by using tri-dexel, namely, using dense lines to penetrate the workpiece from xyz three directions in space, and representing the line segment formed by each line and two points of the workpiece penetrating and penetrating; Secondly, inputting a numerical control nc code into a digital twin system, namely inputting the motion pose of the cutter and the space information of the workpiece into the digital twin system together to obtain a meshing area CWE of the c