A Method Study On Generating 3D Printing Gcode From Industrial CT Slices

In recent years,3D printing technology has made great progress.3D printing is flexible and versatile.It is very good at processing complex shaped workpieces.Industrial computed tomography(ICT)has unique advantages in detecting workpiece with inner cavity structure by X-ray penetration.In order to realize reverse manufacturing of workpiece with inner cavity structure,it is a good choice to combine industrial CT and 3D printing.The result of industrial CT detection is a series of CT slices,and the 3D printer needs G code to drive directly.How to convert industrial CT slices into 3D printing G code is the key to combine the two technologies.The existing method of converting industrial CT slices into 3D printing G codes is indirect conversion through STL and CLI.There is no intermediate interpolation in STL conversion,and the result of 3D printing has obvious "ladder effect",and the conversion efficiency is not high,which is prone to defects.However,CLI and other two-dimensional slice data are seldom used in today's 3D printing process,which is not supported by the mainstream 3D printing software and has low practicability.And through the indirect transformation of CLI format,there still exists a redundant CLI intermediate format,which is inefficient.In order to integrate industrial CT with 3D printing directly and avoid the disadvantage of indirect conversion through STL and CLI formats,a method of generating 3D printing G code directly from industrial CT slice images is proposed.This method bypasses the intermediate formats such as STL and CLI,and the generated G code can be directly transmitted to 3D printer for processing and printing.At the same time,this paper also designs and implements supporting software for this method,which can easily complete the conversion process.The main research contents are as follows:(1)The contour image of industrial CT slice was obtained by preprocessing the image of industrial CT slice.Canny and other classical edge detection operators are used to detect the edges of industrial CT slices,and the performance of each operator is compared.Canny operator is selected to complete the edge detection work,and the edge information of slices is effectively obtained.Eight neighborhood contour tracking algorithm and broken edge connection are used to obtain complete and closed edge contour curves.Left and right vector method is used to simplify the contour data and reduce it.The amount of computation for subsequent problem processing.(2)According to the characteristics of industrial CT image,the geometric elements of industrial CT slice image are divided into workpiece entity,background,outer contour,inner contour,fragment,outline point,feature point and so on.The ray method is used to determine the inner and outer contours;the position of the inner and outer contours is used to determine the entity and background area;the value of the symbolic curvature of the contour points is obtained,and then the extreme points of the symbolic curvature and point coordinate function are obtained,and the points that do not meet the requirements are excluded,thus the feature points are extracted.(3)Inserting a new contour image into the contour image of adjacent industrial CT slices reduces the interlayer thickness of industrial CT slices to that of 3D printing.For contour matching between adjacent layers,when the contour matching branches,the contours are split and merged reasonably,so that all contours in the contour image of industrial CT slices can find one-to-one corresponding contours in the contour image of adjacent industrial CT slices;the matching of feature points and contour points is completed so that each contour point can find the corresponding contour points;and in the middle of the corresponding contour points.Insert new points and connect new points to get new industrial CT slice contour images.(4)format conversion is carried out for each layer of industrial CT slices.Substances in industrial CT slices are divided into outer wall,inner wall,upper and lower surface,filling and supporting;print areas are filled with reciprocating parallel scanning filling;motion paths are converted into G code instructions.The industrial CT slice image processing of automobile hub and carburetor was used to get the 3D printing G code,which was read and displayed by Cura simulation software,and the actual model was processed by 3D printer.Compared with STL and CLI intermediate format conversion,it has better printing quality and efficiency.The validity and correctness of the transformation method are verified.