Free-Form Tool Path Planning for Coupled Two-Sided Dental Machining
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Solution Overview
Problem
Existing double-spindle dental tool machines with kinematic axis coupling face limitations in generating free-form tool paths that conform to individual free-form target geometries, resulting in reduced choices of tool paths and inefficient machining times.
Innovation Solution
A computer-implemented method that determines transformations to convert the kinematic axis coupling into a common coupling parameter for both tools, allowing the generation of free-form tool paths that are identical in time for all participating spindles, enabling simultaneous two-sided machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple tool spindles are used for simultaneous machining, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent merges the control of multiple tool spindles by coupling their axes through a mathematical model. The workpiece coordinate system movements are transformed into tool coordinate system movements, allowing multiple spindles to be controlled as a unified system rather than independent units, thus improving productivity without proportionally increasing mechanical complexity
Solution Approach 2:
The patent changes the control parameters from independent spindle movements to coupled axis movements. By defining a transformation model that relates workpiece coordinate system parameters to tool coordinate system parameters, the system achieves coordinated multi-spindle control through parameter transformation rather than complex mechanical linkages
2Device complexity
If kinematic axis coupling is implemented, then device complexity is reduced, but the choice of tool paths is restricted to circular or arc-shaped paths
Solution Approach 1:
The patent introduces dynamic tool path generation that adapts to the target geometry. Instead of fixed circular or arc-shaped paths, the system dynamically calculates tool paths based on the workpiece coordinate system transformations, allowing the tool paths to flexibly conform to various target geometries while maintaining the simple kinematic coupling structure
Solution Approach 2:
The patent adds a transformation dimension by introducing coordinate system transformations between workpiece and tool references. This dimensional transformation allows the system to generate diverse tool paths (including free-form paths) from the basic kinematic coupling, effectively converting a limited mechanical movement capability into versatile machining paths through mathematical transformation
3Ease of operation
If tool paths are generated independently of target geometry, then ease of operation is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent performs preliminary transformation model establishment before tool path generation. By pre-defining the relationship between workpiece coordinate system and tool coordinate system through transformation models, the system prepares the geometric conformity requirements in advance, allowing subsequent tool path generation to automatically conform to target geometry without complex manual adjustments
Data Source
AI summary
A computer-implemented method of planning of the shapes of free-form tool paths (P) for simultaneous two-sided machining of a dental restoration (1) having an individual free-form target geometry from a workpiece (2) by using a dental tool machine (3) having at least two tool spindles each having at least one tool (4) arranged on a different side of the workpiece (2) which is simultaneously movable along an axis (y) relative to the tools (4) thereby imposing a kinematic axis coupling. The method includes a step of determining transformations (T′, T″) of the target geometry by which the kinematic axis coupling is converted into a common coupling parameter for both tools (4); and a step of generating dependent on these transformations (T′, T″) the shapes of the free-form tool paths (P) in which the common coupling parameter is identical in time for all participating tool spindles that are driven simultaneously.