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CN-122018428-A - Five-axis machining center and shared-axis geometric error level compensation system and method thereof

CN122018428ACN 122018428 ACN122018428 ACN 122018428ACN-122018428-A

Abstract

The invention belongs to the technical field of precision control of numerical control machine tools, and particularly relates to a five-axis machining center and a geometric error level compensation system and method thereof, which solve the problem of interference compensation during concurrent cutting of multiple spindles. The system comprises a physical architecture module, a hierarchy error modeling module and a virtual compensation controller, wherein a virtual axis control unit of the virtual compensation controller executes a hierarchy compensation strategy comprising a public hierarchy, calculating a reference public error based on a shared X axis, injecting the reference public error into the virtual axis control unit for pre-compensation, acquiring feedback of each real-time cutting force when compensation demands conflict, dynamically adjusting a weight coefficient of each processing head according to the cutting force, calculating an optimal public compensation quantity by using a WLS algorithm, and a differential hierarchy, calculating the difference value between the demands of each processing head and the optimal public compensation quantity, decomposing residual error mapping into independent additional motion instructions of each processing head, and executing compensation by each independent axis servo system. The effect of improving the overall machining precision of the large die is achieved.

Inventors

  • ZHANG JINQIAO
  • HU HANXI

Assignees

  • 汉霸智能科技(台州)有限公司

Dates

Publication Date
20260512
Application Date
20251231

Claims (10)

  1. 1. The system is characterized by comprising a physical architecture module, a hierarchical error modeling module and a virtual compensation controller, wherein the virtual compensation controller is configured with a virtual axis control unit and executes the following hierarchical compensation strategy: The common level calculates a reference common error based on the shared X axis, and the reference common error is injected into the virtual axis control unit to pre-compensate the X axis; when the compensation demands of a plurality of processing heads on the X axis are in conflict, collecting real-time cutting force feedback of each processing head, dynamically adjusting the weight coefficient of each processing head according to the cutting force, and calculating the optimal public compensation quantity of the X axis by using a weighted least square algorithm; and the differential level is used for calculating the difference between the requirements of each processing head and the optimal common compensation quantity, and decomposing the residual error map into additional motion instructions of an independent Y axis, an independent Z axis or an independent rotation axis of each processing head through kinematic inversion and conversion, and executing compensation by each independent shaft servo system.
  2. 2. The geometric error level compensation system of claim 1, wherein the level error modeling module employs mathematical logic that: , Wherein, P i is the point position of the tool tip of i processing heads, and X shard is the real-time feedback coordinate of the shared axis.
  3. 3. The geometrical error hierarchical compensation system according to claim 1, wherein the hierarchical error modeling module establishes a full error vector equation of the processing head i through homogeneous coordinate transformation, and defines a rigid body displacement component which does not change with the Y/Z coordinates of the processing head in 21 geometrical errors generated by the shared axis as a reference common error E base by using a spatial decoupling operator, and maps an abbe error component generated by interference of the rotational error item epsilon xx 、ε yx 、ε zx of the shared axis with the instantaneous offset of the processing head to a fine tuning axis independent of each channel for local differential compensation.
  4. 4. The geometric error level compensation system according to claim 1, wherein the virtual compensation controller calculates the error trend in a future preset time window in advance in the virtual axis control unit after receiving the multi-channel interpolation command stream, and when detecting that the compensation requirement change rate dδ req /dt of each channel to the shared axis exceeds the acceleration limit of the physical axis, the controller automatically reduces the common compensation quantity of each channel according to the weight proportion, and feeds back undigested residual errors to the residual error prediction model of each channel, and the feedforward compensation is performed by each independent axis.
  5. 5. A method for compensating a geometric error level of a shared axis of a five-axis machining center, which is applicable to the geometric error level compensation system of any one of claims 1 to 4, and is characterized by comprising the following steps: S1, initializing error mapping, namely acquiring 6 items of geometric error data of a shared shaft in a full stroke through external measuring equipment, and generating a reference common error mapping table; s2, synchronously analyzing space coordinates, namely, a numerical control system reads interpolation positions in multiple channels in real time and identifies the relative position distribution of each processing head on a cross beam; S3, executing a hierarchical compensation strategy: (1) Extracting a reference common error component, and directly feeding back to an X-axis servo driver to perform global precompensation; (2) Residual offset of each processing head at each tool point due to yaw and rolling is solved, and differential fine adjustment is carried out through an independent Y axis or Z axis of each processing head; and S4, conflict collaborative optimization, namely when the compensation requirement directions of the plurality of processing heads on the shared shaft are opposite or the magnitudes are inconsistent, invoking a weighted least square algorithm to calculate the optimal median compensation displacement.
  6. 6. The geometrical error level compensation method according to claim 5, wherein in the step S4, the formula of the weighted least squares algorithm of the optimal median compensation displacement is specifically: , Wherein, the For a common compensation amount to be eventually sent to the X-axis drive, The X-axis requirement for the ith channel.
  7. 7. The geometrical error level compensation method according to claim 6, wherein the weighted least squares optimization process in step S4 gives different weight coefficients according to the accuracy level of the currently processed workpiece surface To ensure preferential compensation of the high-precision task area.
  8. 8. The geometrical error level compensation method according to claim 7, wherein the steps of For dynamic evolution functions, the following formula is satisfied: wherein Rank i is task priority, For real-time cutting force feedback, smooths is a position dependent smoothing function.
  9. 9. The geometrical error level compensation method according to claim 5, wherein in the step S1, the obtaining of the geometrical error data specifically comprises: A. The whole course measurement is carried out, and 6 basic geometric errors sharing an X axis are identified through a laser interferometer; B. space grid scanning, namely identifying the point displacement errors of the machining head at different positions of the cross beam through a laser tracker; C. differential error identification, namely extracting local errors of the self-linked chains Y/Z/A/C of each processing head through a double-club instrument.
  10. 10. Five machining centers, characterized in that, the geometric error level compensation system or the method of any one of the applicable claims 1-8, including gantry beam (1) and set up two at least machining head mount pad (2) on gantry beam (1), machining head mount pad (2) on be provided with through elevation structure (3) machining head (4), gantry beam (1) both ends set up on Y axle floorplan (5), gantry beam (1) and Y axle floorplan (5) between be equipped with X axle feed system (6), machining head mount pad (2) and gantry beam (1) between be equipped with Y axle feed system (7), gantry beam (1) and Y axle floorplan (5) between be equipped with processing fixed station (8) that are located machining head (4) below.

Description

Five-axis machining center and shared-axis geometric error level compensation system and method thereof Technical Field The invention belongs to the technical field of precision control of numerical control machine tools, and particularly relates to a five-axis machining center and a shared-axis geometric error level compensation system and method thereof. Background In the field of modern ultra-precise manufacturing, particularly in the processing process of large aerospace components, automobile panel molds and thin-wall parts, a Multi-spindle concurrent cutting (Multi-Spindle Concurrent Cutting, MSSC) technology has become a key means for improving production efficiency and reducing equipment floor area. Such machine tools typically employ a large gantry architecture in which multiple independent five-axis linkage machining heads are commonly mounted on the same gantry beam and share an X-axis feed system. However, the integration of such a physical architecture also brings about a difficulty in precision control, for example, geometric errors such as nonlinear straightness, pitch, roll, yaw and the like, which inevitably exist in the ultra-long stroke of the gantry beam, can act on all the processing heads at the same time, and generate complex coupling and amplifying effects along with the spatial position change of the processing heads on the beam, so as to affect the processing precision and quality. Disclosure of Invention The invention aims to solve the problems in the prior art and provides a shared-axis geometric error level compensation system of a five-axis machining center. The aim of the invention can be achieved by the following technical scheme: The system comprises a physical architecture module, a hierarchical error modeling module and a virtual compensation controller, wherein the virtual compensation controller is configured with a virtual axis control unit and executes the following hierarchical compensation strategy: The common level calculates a reference common error based on the shared X axis, and the reference common error is injected into the virtual axis control unit to pre-compensate the X axis; when the compensation demands of a plurality of processing heads on the X axis are in conflict, collecting real-time cutting force feedback of each processing head, dynamically adjusting the weight coefficient of each processing head according to the cutting force, and calculating the optimal public compensation quantity of the X axis by using a weighted least square algorithm; and the differential level is used for calculating the difference between the requirements of each processing head and the optimal common compensation quantity, and decomposing the residual error map into additional motion instructions of an independent Y axis, an independent Z axis or an independent rotation axis of each processing head through kinematic inversion and conversion, and executing compensation by each independent shaft servo system. The invention provides a hierarchical compensation mechanism based on common component and local difference, which is characterized in that an error source is spatially decoupled. In the shared axis error of the five-axis machining center, the positioning error belongs to a common term, and the influence of the rotation error (such as pitching and rolling) on the tool tip point linearly or nonlinearly changes along with the offset of the machining head on the cross beam. The invention constructs a virtual axis model through a software algorithm, separates the common displacement of the X axis from the fine adjustment displacement of each head, and utilizes the five-axis motion chain carried by each head (such as the rotating shaft or the vertical shaft of the main shaft head) to digest the error amount of the conflict, thereby realizing that all the processing heads are in the optimal precision state at the same time. In addition, on the cooperative level, the residual error of the weighted least square algorithm is directly converted into a physical axis instruction, so that the precision dead angle can be solved, physical quantity, namely cutting force, is introduced to interfere with the calculation of the geometric quantity of error compensation, and the method is a cross-level control strategy, so that a machine tool can sense the machining state, and rough machining and finish machining can be conveniently distinguished, and precision resources can be intelligently distributed. In the above-mentioned geometrical error level compensation system, the level error modeling module adopts the following mathematical logic: , Wherein, P i is the point position of the tool tip of i processing heads, and X shard is the real-time feedback coordinate of the shared axis. In the above-mentioned geometric error hierarchical compensation system, the hierarchical error modeling module establishes a full error vector equation of the processing head i through homogeneous coordinate t