Tool Drive Unit With Oscillating Transverse Motion Near Rotation Axis

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Solution Overview

Problem

Existing rotary machining technologies face challenges in precisely machining surfaces near the axis of rotation, leading to issues like pin formation, surface damage, and difficulty in maintaining optical quality in lenses and glasses due to compliance with manufacturing tolerances and the use of small tool radii.

Innovation Solution

The implementation of a tool drive unit with linear motors and piezo actuators or voice coils allows for oscillating movements in multiple directions, enabling the use of larger tool radii and precise adjustments, which deviate from the standard machining path to avoid unwanted material removal and accommodate complex height profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the turning tool is moved all the way to the axis of rotation, then the machining area is expanded, but the cutting edge damages the machined surface

Engineering Contradiction:
Improvemachining areaVSAvoidsurface quality
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent applies dynamic control of the turning tool's transverse position by superimposing a secondary transverse movement on the primary transverse movement. This dynamic adjustment allows the tool to approach the axis of rotation more closely without causing damage, as the secondary oscillating movement prevents the cutting edge from remaining in contact with the machined surface in the wrong direction, thereby expanding the machining area while maintaining surface quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements periodic oscillating movement of the turning tool in the transverse direction through the secondary transverse drive. This periodic action causes the tool to rhythmically approach and retract from the axis of rotation, ensuring that the cutting edge does not continuously contact the machined surface in the damaging reverse direction, thus enabling safer machining closer to the axis while preserving surface integrity.

Inventive Principle:
Principle #19Periodic action

2Manufacturing precision

If small tool radii are used to maintain manufacturing tolerances, then surface quality is improved, but production time increases

Engineering Contradiction:
Improvesurface qualityVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the motion parameters of the turning tool by introducing a secondary transverse movement component. This parameter change allows the use of larger tool radii while maintaining manufacturing tolerances, as the oscillating transverse position adjusts the effective cutting path and contact dynamics, thereby reducing production time without sacrificing surface quality.

Inventive Principle:
Principle #35Parameter changes

3Length of moving object

If the cutting edge protrudes beyond the axis of rotation, then the machining path is extended, but the blunt back of the cutting edge contacts and damages the machined surface

Engineering Contradiction:
Improvemachining pathVSAvoidsurface damage
Core Design Contradiction:
Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamic control to the transverse position of the cutting edge, superimposing a secondary oscillating movement on the primary feed movement. This dynamic adjustment ensures that even when the cutting edge protrudes beyond the axis of rotation to extend the machining path, the oscillating motion prevents the blunt back of the cutting edge from continuously contacting and damaging the machined surface.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements periodic oscillating movement in the transverse direction that causes the cutting edge to rhythmically advance and retract relative to the axis of rotation. This periodic action ensures that the blunt back of the cutting edge does not remain in contact with the machined surface, thereby allowing the machining path to be extended without causing surface damage.

Inventive Principle:
Principle #19Periodic action

4Manufacturing precision

If the rotational speed is reduced to maintain manufacturing tolerances, then surface quality is improved, but production time increases

Engineering Contradiction:
Improvesurface qualityVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the motion parameters by introducing a secondary transverse movement component that operates independently of rotational speed. This parameter change allows maintaining higher rotational speeds while still achieving manufacturing tolerances, as the oscillating transverse position compensates for speed-related inaccuracies, thereby improving productivity without sacrificing surface quality.

Inventive Principle:
Principle #35Parameter changes

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 rapid and precise machining of surfaces near the axis of rotation, reducing production time and maintaining high surface quality by allowing for larger tool radii and more efficient processing paths, even in the production of optical lenses and glasses.

Implementation Method 1

a first linear motor having a first voice coil or a first piezo element in a displaceable manner, in particular linearly displaceable, along a feed direction

Methodology Applied
Scientific EffectVoice coil:

Implementation Method 2

a first linear motor having a first voice coil or a first piezo element in a displaceable manner

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

a second linear motor having a second voice coil or a second piezo element in a oscillating or displaceable manner in a transverse direction transverse to the feed direction

Methodology Applied
Scientific EffectVoice coil:

Implementation Method 4

a second linear motor having a second voice coil or a second piezo element in a oscillating or displaceable manner

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3808499B1Tool driving unit, rotating device and rotating method
Publication Date: 2024.04.03 OPTOTECH OPTIKMASCHINEN GMBH
  • EP3808499B1 patent drawingFigure 1
  • EP3808499B1 patent drawingFigure 2
  • EP3808499B1 patent drawingFigure 3

AI summary

The invention relates to a tool drive unit (2) for a rotary device (1) for machining workpieces (100), comprising a tool holder (80) which is driven by a first linear motor (81) displaceably along a feed direction (ZR) and by a second linear motor (85) in a transverse direction (QR) perpendicular to the feed direction (ZR), wherein the linear motors (81, 85) each have a voice coil (82, 86) or a piezoelectric element. The invention also relates to a rotary device with a main feed drive (40) that effects a primary feed movement of a rotary tool (20) in a feed direction (ZR), and with a main transverse drive (50) that effects a primary transverse movement in a transverse direction (QR) perpendicular to the feed direction (ZR).Additionally, this rotary device (1) has a secondary transverse drive (55) whose secondary transverse movements are in the same direction as those of the main transverse drive (50), wherein the rotary tool (20) and the axis of rotation (A) can be moved towards and away from each other by the superposition of primary and secondary transverse movements. In a method according to the invention, such primary and secondary transverse movements are superimposed to machine the center of a rotating end face (F) of a workpiece (100).