Dual-Linear-Motor Tool Drive for Turning Near the Rotation Axis
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Solution Overview
Problem
Existing turning devices face challenges in precisely machining workpieces near the axis of rotation, leading to optical defects and surface quality issues due to tool lift errors and contact with the machined surface, especially in optical lenses and glasses, where manufacturing tolerances are difficult to maintain.
Innovation Solution
A tool drive unit with a tool holder driven by multiple linear motors, including piezo actuators or moving coils, allows for novel movement kinematics, enabling the cutting edge to oscillate transversely and maneuver around positions to avoid material removal at undesired locations, using larger tool radii and compensating for height profiles with secondary transverse movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the turning tool is moved completely up to the axis of rotation, then the machining area is expanded, but the cutting edge contacts the already machined surface causing damage
Solution Approach 1:
The patent implements dynamic control of the turning tool position by independently actuating the tool holder in the infeed direction and the cutting edge in the transverse direction through two separate linear motors. This dynamic independence allows the cutting edge to be precisely positioned relative to the workpiece surface, enabling the tool to reach the axis of rotation without contacting the already machined surface, thus resolving the contradiction between expanding machining area and maintaining surface quality
Solution Approach 2:
The patent introduces an additional degree of freedom by adding transverse direction control (perpendicular to the infeed direction) to the traditional infeed-only control system. This dimensional extension allows the cutting edge to maneuver laterally to avoid contact with the machined surface while still reaching the axis of rotation, effectively resolving the contradiction through spatial repositioning
2Manufacturing precision
If the tool radius is reduced to avoid contact with machined surface, then surface quality is maintained, but prismatic machining becomes problematic and production time increases
Solution Approach 1:
The patent uses dynamic control of the cutting edge position in the transverse direction to compensate for the larger tool radius. By independently adjusting the cutting edge position, the system can maneuver larger radius tools around the machined surface to avoid contact, thereby maintaining surface quality while enabling the use of larger tools that reduce production time
Solution Approach 2:
The patent changes the control parameters from single-axis infeed control to dual-axis control (infeed direction and transverse direction). This parameter expansion allows the system to optimize tool path and positioning dynamically, enabling the use of larger tool radii without compromising surface quality, thus improving productivity
3Manufacturing precision
If the rotational speed is reduced to maintain manufacturing tolerances, then optical defects are avoided, but production time increases
Solution Approach 1:
The patent implements dynamic positioning control that operates independently of workpiece rotational speed. By controlling the cutting edge position in the transverse direction through a second linear motor, the system can maintain precise positioning and manufacturing tolerances regardless of rotational speed, thereby enabling higher speeds and improved productivity without sacrificing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables quick and precise machining near the axis of rotation, reducing optical defects and improving surface quality by allowing larger tool radii and more efficient machining paths, thus shortening production times and maintaining manufacturing tolerances.
Implementation Method 1
the tool holder is driven in a displaceable manner, in particular in a linearly displaceable manner, along an infeed direction by a first linear motor having a first moving coil or a first piezo element
Implementation Method 2
the tool holder is driven in a displaceable manner, in particular in a linearly displaceable manner, along an infeed direction by a first linear motor having a first moving coil or a first piezo element
Implementation Method 3
the tool holder is driven in a pendular or displaceable manner in a transverse direction transversely to the infeed direction by a second linear motor having a second moving coil or a second piezo element
Implementation Method 4
the tool holder is driven in a pendular or displaceable manner in a transverse direction transversely to the infeed direction by a second linear motor having a second moving coil or a second piezo element
Data Source
AI summary
A tool drive unit for a turning device for machining workpieces has a tool holder driven in a displaceable manner along an infeed direction by a first linear motor and driven in a pendular/displaceable manner in a direction transverse to the infeed direction by a second linear motor. Both linear motors have a moving coil/piezo element. The turning device has a main infeed drive, which produces a primary infeed movement of a turning tool in an infeed direction, and has a main transverse drive which produces a primary transverse movement in a transverse direction transversely to the infeed direction. The turning device has a secondary transverse drive whose movements are oriented in the same direction as the main transverse drive, wherein the turning tool and the axis of rotation can be moved towards one another and away from one another by the superimposition of primary and secondary transverse movements.