Search

CN-121977559-A - Method for measuring and planning deformation of metal cavity part by alternately mixing materials

CN121977559ACN 121977559 ACN121977559 ACN 121977559ACN-121977559-A

Abstract

The invention discloses a method for measuring and planning deformation of a metal cavity part by alternately mixing materials. The additive and subtractive hybrid manufacturing technology can effectively process complex cavity parts by combining the design freedom degree of additive manufacturing and the high-precision advantage of subtractive manufacturing, but repeated thermodynamic actions and alternating procedures can cause accumulated step-shaped deformation, and the traditional optical measurement method is difficult to completely capture measurement data due to the problems of internal shielding and surface reflection of the cavity, and has point cloud registration errors. The method provided by the invention has the advantages that the multi-axis on-machine measurement is embedded into the alternating working procedure sequence of increasing and decreasing materials, the measuring points are directly from the cutter contact points of the cutting path, the measurement accuracy of the multi-axis on-machine measurement and the measurement accessibility of the deep cavity structure are ensured, the measuring path is optimized by combining probe gesture planning and customized travelling business algorithm, and the point cloud registration link required by optical measurement is eliminated by the method because the probe and the cutter share the same coordinate system, and the data accuracy is obviously improved.

Inventors

  • HE DONG
  • YANG HAI
  • LIU XIAOJUN
  • WU WENYU
  • MO JINGWEN

Assignees

  • 东南大学

Dates

Publication Date
20260505
Application Date
20260113

Claims (6)

  1. 1. The method for measuring and planning the deformation of the metal cavity part by alternately mixing the materials is characterized by comprising the following steps of: Dividing the geometry of a cavity part to be processed into a plurality of sections to obtain a sequence of alternate manufacturing of increasing and decreasing materials, and sequentially planning a multi-axis additive manufacturing path and a multi-axis cutting processing path in each additive-subtractive manufacturing section; Step 2, downsampling the intensive cutting tool contacts according to the multi-axis cutting path obtained in the step 1 and the corresponding cutter shaft vector direction, so as to ensure that the tool contacts are scattered and uniformly distributed in Euclidean space; step 3, aiming at each additive-subtractive manufacturing section, taking the discrete knife contact point in the step 2 as an on-machine measuring probe contact point and the knife shaft direction corresponding to the knife contact point as a probe direction; step 4, calculating interference conditions of the probe assembly and the rest of the material increasing and decreasing sections at each measuring path point and in the direction corresponding to the probe obtained in the step 3 aiming at each material increasing and decreasing manufacturing section to obtain a measuring accessibility index of the material increasing and decreasing section to be analyzed; And 5, inserting all the segmented measuring procedures which are already machined under the condition of meeting the requirement of measuring accessibility after each material adding or subtracting procedure according to the measuring accessibility index of each material adding-subtracting manufacturing segment, and carrying out on-machine measurement according to the measuring path planned in the step 3 to acquire the probe position point cloud.
  2. 2. The method for measuring and planning the deformation of the metal cavity part manufactured by alternately mixing materials according to claim 1, wherein the specific implementation process of the step 1 is as follows: Slicing the geometric three-dimensional model of the part to be processed by using a group of cross-section planes at preset positions to obtain a series of plane slice contours, grouping different plane slice contours so as to divide the geometric body of the cavity part to be processed into a plurality of orderly sections And planning a multi-axis material adding path and a nozzle axis vector thereof, and a multi-axis processing path and an axis vector thereof in each layer, wherein the multi-axis material adding path and the nozzle axis vector thereof meet the non-interference constraint.
  3. 3. The method for measuring and planning the deformation of the metal cavity part manufactured by alternately mixing materials according to claim 1, wherein the specific implementation process of the step 2 is as follows: downsampling the dense cutter contacts according to the ith segmented multiaxial cutting path obtained in the step 1 and the corresponding cutter shaft vector direction, and reducing the point set scale to a preset number through the furthest point sampling strategy so as to realize sparse and uniformly distributed measurement point sets in Euclidean space The down-sampled point cloud presents discrete and uniform spatial distribution characteristics on the processing surface, and meanwhile, the consistency with the original cutter shaft direction is maintained.
  4. 4. The method for measuring and planning the deformation of the metal cavity part manufactured by alternately mixing materials according to claim 1, wherein the specific implementation process of the step 3 is as follows: manufacturing segments for each additive-subtractive process Taking the knife contact point in the cutting processing path after the downsampling in the step 2 as the contact point of an on-machine measuring probe Simultaneously, the vector direction of the cutter shaft corresponding to the cutter contact point is directly used as the detection direction of the probe Adding a relay point of a safe position for each contact point in the measurement path planning And converting the relay point connection problem of the measurement point set into a travel business problem, designing a comprehensive cost function to optimize the traversing sequence, and calculating an optimal measurement traversing path by adopting an efficient solver.
  5. 5. The method for measuring and planning the deformation of the metal cavity part manufactured by alternately mixing materials according to claim 1, wherein the specific implementation process of the step 4 is as follows: Additive-subtractive manufacturing segments for each of the additive-subtractive manufacturing segments to be analyzed Each measurement probe contact point obtained in step 3 The posture of the probe is set to be the cutter shaft direction of the cutter at the position corresponding to the cutter contact point Simplifying the probe assembly of the probe into a geometric envelope, and verifying the probe from Extending along the normal direction of the surface of the part to be measured to a relay point In the complete motion trail of the probe assembly and the segments Is defined by the following segments of (a) (K > i) a segment to be collided with the probe assembly first Is taken as the contact point Reachability index of (a) last traverse of the segment All of the lower measuring contacts Selecting the smallest index k as the segment Is a comprehensive measure of reachability index.
  6. 6. The method for measuring and planning the deformation of the metal cavity part manufactured by alternately mixing materials according to claim 1, wherein the specific implementation process of the step 5 is as follows: according to the measurement accessibility index of each additive-subtractive manufacturing segment obtained in step 4, after each segment is completed After the additive or subtractive process, evaluating the segment and all segments preceding it (I≤k) measurement reachability index, when segments to be measured If the measure accessibility index of (1) verifies as collision-free, then immediately insert the segment And (3) performing on-machine measurement according to the planned measurement path in the step (3), wherein the measurement probe and the cutting tool share the same coordinate system, coordinate data of measurement points are directly read through a numerical control system, the posture of the probe strictly follows the direction of a cutter shaft vector corresponding to a cutter contact, and a safety return point is arranged along the surface normal translation extension preset distance, so that the movement track of the probe in the whole approaching and retracting processes is ensured to pass the reachability verification.

Description

Method for measuring and planning deformation of metal cavity part by alternately mixing materials Technical Field The invention belongs to the field of computer-aided manufacturing, and particularly relates to a method for measuring and planning deformation of a metal cavity part by alternately mixing materials. Background In the fields of aerospace, energy equipment and the like, parts with deep cavity structures have strict requirements on geometric precision and surface quality, the traditional pure material reduction manufacturing faces the problems of large material waste, poor accessibility of cutters and the like, and the laser Directional Energy Deposition (DED) additive manufacturing is limited by defects of insufficient dimensional precision and surface roughness. The material adding and reducing mixed manufacturing adopts a mode of alternately carrying out material adding and material reducing processes, realizes material layer-by-layer deposition and multi-axis machining of metal parts on a multi-axis numerical control platform, and meets the requirements of complex geometric forming capability and machining surface quality. However, the metallic material undergoes repeated melt-solidification cycles during the DED process, overlapping the mechanical effects of subsequent cutting processes, resulting in complex thermo-mechanical coupling effects inside the workpiece. This effect is further amplified in the additive-subtractive alternating process, ultimately resulting in geometric distortion with stepped features. More critical is that the inside of the deep cavity structure is difficult to completely capture deformation data by an optical measurement method (such as structure light scanning) due to geometric shielding and high reflection characteristics of the milled surface, so that point cloud is lost, and coordinate alignment errors introduced by a point cloud registration link are even equivalent to deformation magnitude, so that measurement reliability is further reduced. Aiming at the problem of stepped accumulated deformation of metal cavity parts caused by repeated thermodynamic actions in alternate manufacturing of increasing and decreasing materials, the prior measuring technology has triple limitations that 1, deformation data are difficult to capture completely by an optical measuring method due to shielding in a cavity and high reflection characteristics of the surface, 2, the deep cavity area data are not fully acquired due to the fact that a contact measuring scheme is not integrated with the depth of a manufacturing process, and 3, geometrical constraints of a manufactured workpiece which are not considered to be dynamically changed are planned at an on-machine measuring point, and the verification of the probe posture and path accessibility is insufficient. Disclosure of Invention In order to solve the problems, the invention discloses a metal cavity part material increasing and decreasing alternate mixing manufacturing deformation measurement planning method, wherein a multi-axis on-machine measurement procedure is organically embedded into a multi-axis material increasing and decreasing alternate mixing manufacturing sequence, probe gestures are reasonably planned according to material increasing and decreasing segments and corresponding processing paths so as to ensure probe measurement precision and measurement accessibility, and a measurement path traversing sequence is optimized based on an algorithm, so that collision-free high-precision data acquisition of a deep cavity structure is realized. In order to achieve the above purpose, the technical scheme of the invention is as follows: a metal cavity part material increasing and decreasing alternate mixing manufacturing deformation measurement planning method comprises the following steps: Dividing the geometry of a cavity part to be processed into a plurality of sections to obtain a sequence of alternate manufacturing of increasing and decreasing materials, and sequentially planning a multi-axis additive manufacturing path and a multi-axis cutting processing path in each additive-subtractive manufacturing section; Step 2, downsampling the intensive cutting tool contacts according to the multi-axis cutting path obtained in the step 1 and the corresponding cutter shaft vector direction, so as to ensure that the tool contacts are scattered and uniformly distributed in Euclidean space; step 3, aiming at each additive-subtractive manufacturing section, taking the discrete knife contact point in the step 2 as an on-machine measuring probe contact point and the knife shaft direction corresponding to the knife contact point as a probe direction; step 4, calculating interference conditions of the probe assembly and the rest of the material increasing and decreasing sections at each measuring path point and in the direction corresponding to the probe obtained in the step 3 aiming at each material increasing and decreasing manufact