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Off-line analysis method of machining allowance for free-form surface parts

A technology of curved surface parts and machining allowance, applied in image analysis, image data processing, instruments, etc., can solve the problem of low precision, reduce the number of tool passes and optimize the distribution of machining allowance

Active Publication Date: 2018-12-18
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the shortcomings of the existing registration method with low accuracy, and propose an off-line analysis method of machining allowance for free-form surface parts

Method used

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  • Off-line analysis method of machining allowance for free-form surface parts
  • Off-line analysis method of machining allowance for free-form surface parts
  • Off-line analysis method of machining allowance for free-form surface parts

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specific Embodiment approach 1

[0016] Specific implementation mode 1: The off-line analysis method of machining allowance for free-form surface parts in this implementation mode, such as figure 1 shown, including:

[0017] Step 1: Obtain a translation vector that can translate the center of mass of the blank and the center of mass of the design model to coincide.

[0018] This step is the process of obtaining the rough registration translation vector. The process of calculating the rough center of mass can be as follows: first, through the high-precision scanning and 3D reconstruction of the 3D scanner, and remove the outliers through filtering, to obtain the rough point cloud to be analyzed, and then Each point in the point cloud is regarded as a mass point, and the centroid of the entire point cloud is calculated as the centroid of the blank. The calculation process of the design model is similar. The design model can be used for point cloud sampling to obtain a model point cloud with the same volume as...

specific Embodiment approach 2

[0034] Specific embodiment two: the difference between this embodiment and specific embodiment one is that step one includes:

[0035] The blank is scanned and 3D reconstructed, and filtered to remove outliers to obtain the blank point cloud.

[0036] Sampling the point cloud of the design model to obtain a model point cloud with the same volume as the blank point cloud.

[0037]Treat each point in the rough point cloud and model point cloud as a mass point, calculate the space position of the center of mass of the rough point cloud and the model point cloud, and make a difference between the rough point cloud and the centroid of the model point cloud to obtain the The centroid and design model's centroid are translated to coincident translation vectors.

[0038] Other steps and parameters are the same as those in Embodiment 1.

specific Embodiment approach 3

[0039] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is that step two is specifically:

[0040] Calculate all surface normals for blank and design model separately; generate extended Gaussian image sphere; map all surface normals for blank and design model to extended Gaussian image sphere, blank and design model on each face of the extended Gaussian image sphere The number of normals contained represents the characteristic strength of the blank and the characteristic strength of the design model, and the degree of correlation between the characteristic strength of the blank and the characteristic strength of the design model is calculated. The calculation formula is:

[0041]

[0042] Where Corr is the degree of correlation, is a vector consisting of the number of normals that the blank contains on each face of the extended Gaussian image sphere, A vector of the number of normals that the ...

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Abstract

The invention relates to an off-line analysis method for machining allowance of a free-form surface part, which is proposed to solve the disadvantage of low precision of the existing registration method. The method comprises the following steps: obtaining a translation vector capable of making the center of mass of a blank and the center of mass of a design model translate to coincidence; obtaining a translation vector capable of making the center of mass of the blank translate to coincidence; all surface normals of the blank and the design model being mapped to the extended Gaussian image spheres, respectively, and 3D attitude angle combinations capable of making the extended Gaussian image of the blank and the extended Gaussian image of the design model reach the preset correlation conditions being obtained by mapping the blank and the surface normals of the design model to the spheres. The rotation matrix and translation of the blank and the design model can satisfy the full envelope condition, the datum alignment condition and the margin uniformity condition. The invention is applicable to the registration method in the process of machining curved surface parts.

Description

technical field [0001] The invention relates to the technical fields of computer graphics and mechanical processing, in particular to an off-line analysis method of machining allowance for free-form surface parts. Background technique [0002] For thin-walled blade curved surface parts that require high machining accuracy, investment casting technology is often used to manufacture blanks, and then the final process of removing allowances and surface polishing is completed by grinding, but the degree of consistency of casting produces inconsistent machining allowances. phenomenon, which has a serious impact on the degree of automation of subsequent processing, and manual operation has higher requirements for the operator's skills; in addition, the traditional manual grinding environment is harsh, and dust has a great impact on the health of the operator, so the digitalization of complex surfaces processing is important. In order to realize the digital processing of free-form...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/00G06T7/30
CPCG06T7/0004G06T7/30
Inventor 杜志江高永卓董为徐威李明洋王勇智
Owner HARBIN INST OF TECH
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