Micromechanical CNC Tool Layout for Low Inertia and Rigidity

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Solution Overview

Problem

The reduction in size of numerically controlled machine tools for micromechanics leads to a loss of static rigidity, which is detrimental for high precision machining applications due to increased deformation under thermal and mechanical stresses.

Innovation Solution

A numerically controlled machine tool design that optimizes the size ratio between the machine tool and the raw part by minimizing the machine tool's dimensions and maximizing the raw part's dimensions, with a workpiece holder unit kinematically connected to the frame for rotation and translation in the Z direction and a tool holder unit connected for translation in X and rotation/translation in Y, minimizing inertia and maintaining rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the dimensions of the machine tool are reduced, then the inertia of moving masses is reduced and cutting/movement speeds increase, but the static rigidity of the machine tool is lost causing deformation

Engineering Contradiction:
Improveinertia of moving massesVSAvoidstatic rigidity
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The machine tool is divided into modular functional units (workpiece holder unit with carriage, tool holder unit with carriages, frame) that can be independently optimized. This segmentation allows reducing the size of moving components while maintaining the rigidity of the overall structure through strategic placement and connection of these modules.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent reconfigures the kinematic architecture by distributing degrees of freedom across different spatial dimensions and units. The workpiece holder unit handles Z-direction movements while tool holder units handle X and Y directions, creating a multi-dimensional load distribution that reduces stress on any single component and maintains rigidity in a compact form.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of stationary object

If the machine tool dimensions are minimized, then floor space and energy consumption are reduced, but machining precision deteriorates due to deformation

Engineering Contradiction:
Improvemachine tool volumeVSAvoidmachining precision
Core Design Contradiction:
Volume of stationary objectVSManufacturing precision

Solution Approach 1:

The patent implements dynamic control through computerized numerical control that coordinates the movement of multiple carriages and holder units. This dynamic control system compensates for potential deformations by precisely managing the kinematic relationships between moving parts, maintaining machining precision despite the reduced size and increased flexibility of the structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent combines multiple functions into integrated units - the workpiece holder unit integrates clamping, positioning, and Z-axis movement functions, while tool holder units combine tool carrying, positioning, and X-Y axis movements. This merging reduces the overall machine tool volume while maintaining precision through coordinated operation of these multifunctional modules.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4442401A1Numerically controlled machine tool for machining micromechanical parts from a blank, in the form of a bar or a strip
Publication Date: 2024.10.09 ETA SA MFG HORLOGERE SUISSE
  • EP4442401A1 patent drawingFigure 1~2
  • EP4442401A1 patent drawingFigure 3~4
  • EP4442401A1 patent drawing

AI summary

The invention relates to a numerically controlled machine tool (10) for machining micromechanical parts from a raw part (100) in the form of a bar or a strip, comprising a frame (12), a workpiece holder unit (11) for holding the part (100) in position and a tool holder unit (13) for holding a cutting tool (130), the workpiece holder unit (11) being kinematically connected to the frame (12) so as to have, with respect to the frame (12), only one degree of freedom in rotation and one degree of freedom in translation along a Z direction, in an XYZ frame, and the tool holder unit (13) being kinematically connected to the frame (12) so as to have, with respect to the frame (12), only one degree of freedom in translation along an X direction, and one degree of freedom in rotation and translation along a Y direction.