Tapping Motion Planning Without Staging Waypoints
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Solution Overview
Problem
Current machine tool control methods for hole tapping are inefficient due to the inclusion of staging location waypoints, which increase cycle time and reduce machine tool efficiency.
Innovation Solution
A time-optimal motion planning method that determines a motion plan for a hole tapping operation by computing air cut steps to ensure the tapping tool arrives at the top of the hole with proper axial and rotational velocities, minimizing cycle time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If staging location waypoints are included in the motion plan, then the machine tool can prepare spindle speed before tapping, but the cycle time increases and efficiency decreases
Solution Approach 1:
The patent applies preliminary action by computing the air cut step duration based on maximum-effort spindle acceleration to determine the optimal duration for lateral and axial transit motions. This allows the spindle to be brought to proper rotational velocity during the air cut step itself, eliminating the need for separate staging location waypoints while ensuring the spindle is ready for tapping.
Solution Approach 2:
The patent merges the spindle speed preparation function into the air cut step by coordinating the spindle acceleration profile with the lateral and axial transit motions. The air cut step simultaneously accomplishes tool repositioning and spindle speed preparation, combining multiple functions into a single motion segment rather than requiring separate staging movements.
2Reliability
If the tool is moved to a staging location before tapping, then spindle speed can be synchronized, but the overall cycle time increases
Solution Approach 1:
The patent maintains continuity of useful action by ensuring the spindle is brought to proper rotational velocity continuously during the air cut step without interrupting the lateral and axial transit motions. The motion plan computes coordinated acceleration profiles that maintain continuous progress toward both repositioning and speed synchronization goals simultaneously.
Solution Approach 2:
The patent applies dynamics by computing time durations for air cut steps based on maximum-effort spindle acceleration conditions and coordinating these with the transit motion profiles. The system dynamically adjusts the timing and acceleration of different motion components to achieve synchronization at the optimal moment without requiring static staging locations.
3Productivity
If maximum-effort spindle acceleration is used during air cut, then the cycle time is reduced, but the coordination with axial and lateral transit motions becomes more complex
Solution Approach 1:
The patent segments the air cut step into computable components by separately determining time durations for lateral transit, axial transit, and spindle acceleration under maximum-effort conditions. Each component is calculated independently based on its own constraints, then the maximum of these durations determines the overall air cut step duration, simplifying the coordination complexity.
Solution Approach 2:
The patent changes parameters by computing motion profiles based on maximum-effort acceleration conditions and using these computed parameters to coordinate all motion components. The system uses the computed time durations from maximum-acceleration spindle ramp-up as the governing parameter to synchronize lateral and axial transit motions, transforming a complex coordination problem into a parameter-matching problem.
Data Source
AI summary
A method for machine tool motion control which determines a time-optimal motion plan for a hole tapping step preceded by an air cut step. The motion plan for the air cut step is computed so that the tapping tool arrives at the top of the hole to be tapped with the proper axial tapping feed speed and the proper tapping rotational velocity. First, time durations for the air cut step are computed for lateral and axial transit motions and for spindle acceleration under maximum-effort conditions. The longest of the time durations is then used to plan the air cut step, where the time-limiting axis motion is performed at maximum machine effort, and other axes have their motions planned to complete at the same time as the longest-duration axis. The technique is applicable to an air cut step before a tapping step or in between two tapping steps.