NC Toolpath Smoothing After Kinematic Conversion
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Solution Overview
Problem
Existing numerical control devices smooth paths specified by a tool center point, leading to deceleration and deterioration of machined surface quality due to coordinate conversion issues, which affect cycle time and machining precision.
Innovation Solution
A numerical control device that generates a tool center point sequence, performs interpolation and kinematic conversion to obtain a control point sequence, applies smoothing processing with a predetermined parameter, and controls machining tool driving based on the smoothed control point sequence to ensure smooth motion and adherence to tolerance limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If smoothing is performed on the tool center point sequence before coordinate conversion, then the tool center point path becomes smooth, but the control point path becomes non-smooth after coordinate conversion, causing deceleration and lowering cycle time
Solution Approach 1:
Instead of smoothing the tool center point sequence before coordinate conversion (conventional approach), the patent inverts the sequence: first perform coordinate conversion to obtain the control point sequence, then apply smoothing to the control point sequence. This reversal eliminates the need for subsequent re-smoothing and prevents deceleration, thereby improving cycle time while maintaining path smoothness.
Solution Approach 2:
The patent performs coordinate conversion as a preliminary action before smoothing. By converting the tool center point sequence to control point sequence first, the smoothing operation is applied to the correct coordinate system, preventing later deceleration events and ensuring continuous smooth motion throughout the machining process.
Data Source
AI summary
Provided is a numerical control device for improving cycle time and machined surface quality. The numerical control device (1) comprises: a machining program reading unit (10) that generates, on the basis of a read machining program, a tool center point sequence indicating a path of a center point of a tool of a machining tool; an interpolation control unit (11) that interpolates the tool center point sequence generated by the machining program reading unit (10); a kinematic conversion unit (12) that performs coordinate-conversion on the tool center point sequence interpolated by the interpolation control unit (11) to obtain a control point sequence indicating a path of a control point by which the position of the tool is determined; a smoothing application unit (13) that performs smoothing by performing smoothing processing on the control point sequence, obtained by the kinematic conversion unit (12), with predetermined parameters; and a drive control unit (14) that controls driving of a machining tool A on the basis of the control point sequence smoothed by the smoothing application unit (13).