Tool Path Generation for Curved Surface Error Correction
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Solution Overview
Problem
Existing methods for correcting shape errors in curved surface machining are sensitive to measurement noise, making it difficult to generate an appropriate tool path that accurately conforms to the shape characteristics.
Innovation Solution
A tool path generation method that involves inputting a polynomial function defining a curved surface, measuring the machined workpiece at multiple points, calculating symmetrical correction points, and generating a new tool path based on a modified function that best fits the correction points, allowing for precise correction of shape errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shape error correction is performed by inverting the sign of calculated shape error and superimposing it on the design shape, then correction can be made to a certain extent, but the correction is sensitive to measurement noise and appropriate tool path cannot be generated
Solution Approach 1:
The patent changes the parameter representation from direct shape error values to symmetrical position coordinates. By calculating symmetrical positions with respect to the first curved surface and using these as correction points, the method transforms the correction parameters into a form that is less sensitive to measurement noise while maintaining the ability to correct shape errors effectively.
Solution Approach 2:
The patent creates a virtual model (second function representing second curved surface) based on the measured data and calculated symmetrical positions. This virtual model serves as a corrected copy of the original design, allowing the system to generate an appropriate tool path without directly using the noisy measurement data, thus reducing sensitivity to measurement noise.
2Manufacturing precision
If correction is made by inverting sign of calculated shape error and superimposing on prior design shape, then correction can be made to certain extent, but it is difficult to correct according to shape characteristics
Solution Approach 1:
The patent transforms the correction approach by changing from direct shape error values to symmetrical position coordinates relative to the curved surface. This parameter transformation enables the correction method to adapt to different curved surface characteristics while maintaining effective shape error correction, as the symmetrical positions inherently reflect the local geometry of the surface.
Solution Approach 2:
The patent applies local quality by calculating symmetrical positions for each measurement point individually with respect to the local curved surface geometry. This allows the correction to adapt to local shape characteristics at each point rather than applying a global correction, thereby improving the ability to correct according to specific shape characteristics.
Data Source
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AI summary
Disclosed is a tool path generating method which generates a tool path on the basis of functions which define curved surfaces in a three-dimensional space, wherein: a first function which defines a first curved surface is inputted, said first function being formed from a polynomial formula which comprises a plurality of coefficients; a first tool path is generated on the basis of the first function; the first tool path is inputted into a numerical controller (NC) device of a machine tool, and a tool is made to move relative to a workpiece along the first tool path, machining the workpiece; the shape of the machined workpiece is measured at a plurality of measuring points upon the surface of the workpiece; for each of the measuring points, a position is computed in a perpendicular direction to the first curved surface as a correction point which is symmetric with respect to the first curved surface; a second function is derived which represents a second curved surface which best fits a position data series of the correction points; and a second tool path is generated on the basis of the second function.