Machining Program Optimization for Constant Tool Tip Feedrate
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Solution Overview
Problem
Current CAD/CAM systems fail to maintain a constant feedrate at the end of the tool during machining of complex surfaces due to dynamic performance limitations, leading to speed discontinuities and undesirable marks on the part, especially when dealing with high variations in tool-part orientation and geometric discontinuities.
Innovation Solution
A method for optimizing the tool path by modifying the alignment and distribution of orientation vectors, reconstructing the speed profile of rotary axes, and synchronizing kinematic movements to eliminate discontinuities and maintain constant tool tip speed, applied upstream of numerical control, independent of the machining machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the feedrate at the end of the tool is maintained constant as programmed, then the tool path accuracy is improved, but the machine dynamic performance is exceeded causing speed reduction
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-positioning the rotary axes before the tool reaches zones with high orientation variations. The system anticipates the geometric discontinuities and prepares the machine configuration in advance, allowing the linear axes to maintain their programmed constant speed without sudden reductions, thus resolving the contradiction between path accuracy and speed maintenance.
2Manufacturing precision
If the machine reduces feedrate to respect the programmed path and orientation, then the tool path accuracy is maintained, but productivity decreases
Solution Approach 1:
By pre-positioning the rotary axes in advance before the tool reaches critical zones, the system eliminates the need for speed reduction during machining. The preliminary configuration allows the machine to maintain the programmed constant feedrate throughout, preserving both path accuracy and productivity without trade-offs.
3Productivity
If the CAD/CAM generates tool path with constant feedrate, then the cutting parameters are optimized, but discontinuities in axis speed occur at geometric transitions
Solution Approach 1:
The system performs preliminary positioning of rotary axes before the tool approaches geometric transition zones. This advance preparation ensures that when the tool reaches these zones, all axes are already in their correct positions and can move smoothly together, eliminating speed discontinuities and maintaining both cutting efficiency and speed profile continuity.
Solution Approach 2:
The patent applies preliminary anti-action by counteracting the potential speed discontinuities before they occur. The system pre-calculates the required rotary axis positions and movements in advance, preparing the machine to smoothly transition through geometric discontinuities without generating acceleration peaks or speed jumps that would disrupt the constant feedrate.
4Manufacturing precision
If the rotary axes are activated to handle high orientation variations, then the tool-part orientation accuracy is improved, but acceleration peaks and inertial forces increase
Solution Approach 1:
The patent applies preliminary action by activating and pre-positioning the rotary axes before the tool reaches zones requiring high orientation accuracy. This gradual, pre-coordinated activation allows the rotary axes to reach their required positions smoothly without sudden movements, thereby maintaining orientation accuracy while minimizing acceleration peaks and the resulting inertial forces on the machine structure.
Data Source
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AI summary
The present invention pertains to a method for generating a machining program defining a trajectory of a tool (1) with respect to a workpiece (2) to be machined, said method including: - the generation of a base code defining the trajectory of the tool (1) with a first traversal where the relative motion is performed solely according to linear axes followed by a second traversal where the relative motion is performed according to linear axes and one or two rotary axes, characterized in that it furthermore includes: - the optimization of the base code so as to modify the previously defined trajectory, with the aid of the following steps: - modification of the first traversal with a relative motion being performed along the linear axes and the rotary axis or axes before embarking on the second traversal; - reconstruction of the profile of a kinematic quantity of the said or of one of said rotary axes on the first traversal so as to remove the discontinuities on the profile.