Dynamic Clamping Force Control for Gear Cutting Machine Tables

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Solution Overview

Problem

Secondary processes in machine tools, such as loading and unloading, can negatively impact the machining result due to mechanical coupling of clamping devices, leading to undesirable deformations and inaccuracies.

Innovation Solution

A method for operating a machine tool with multiple tables and counterholder arms, where clamping forces are dynamically controlled and regulated based on the current process and required forces to minimize deformation influences during secondary processes, ensuring the clamping force is sufficient for workpiece positioning but reduced during machining to prevent negative impacts on the machining result.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If clamping forces are increased to hold the workpiece firmly during positioning, then the workpiece positioning stability is improved, but the workpiece deformation increases during secondary processes

Engineering Contradiction:
Improveworkpiece positioning stabilityVSAvoidworkpiece deformation
Core Design Contradiction:
Stability of the object's compositionVSShape

Solution Approach 1:

The clamping force is made dynamically adjustable rather than static. The control unit varies the clamping force magnitude based on the process phase: higher forces during positioning to ensure stability, and reduced forces during machining to prevent deformation. This dynamic adaptation resolves the contradiction between needing firm holding and avoiding deformation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The clamping force parameter is changed according to the process requirements. The system transitions between different clamping force levels (first magnitude for positioning, second magnitude for machining) based on the current operation phase. This parameter variation allows the system to optimize both positioning stability and workpiece integrity at different stages.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If secondary processes are performed with high clamping forces, then the workpiece positioning is more secure, but the machining result is negatively affected due to workpiece deformation

Engineering Contradiction:
Improveworkpiece positioning reliabilityVSAvoidmachining result quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The clamping force is dynamically adjusted based on the process phase. During secondary processes, the force is sufficient for positioning reliability but controlled to avoid excessive deformation. During machining, the force is optimized to maintain precision while still providing adequate holding. This dynamic control resolves the contradiction between positioning reliability and machining quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system performs preliminary positioning with appropriate clamping forces during secondary processes, then transitions to machining-optimized clamping forces before the actual machining operation. This preliminary action ensures the workpiece is properly positioned and centered before the critical machining phase, resolving the contradiction by sequencing the force applications appropriately.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If multiple machine tables are used for parallel secondary processes, then the productivity is improved, but the mechanical coupling of clamping devices causes unfavorable effects on machining results

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidmachining result quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The control system segments the clamping force control for each machine table and counterholder arm independently. Each clamping device can be controlled at its own optimal force level based on its specific process requirements. This segmentation allows parallel operations on multiple tables without the clamping forces from one table negatively affecting the machining precision on another table.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system independently adjusts clamping force parameters for each machine table and process stage. By varying the clamping force magnitude and timing for each table separately, the system maintains high productivity through parallel processing while preventing the mechanical coupling effects from degrading machining quality. Each table's clamping parameters are optimized for its specific operation phase.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2623244B1Method for operating a machine tool and machine tool
Publication Date: 2020.10.28 LIEBHER VERZAHNTECHNIK GMBH
  • EP2623244B1 patent drawingFigure 1
  • EP2623244B1 patent drawingFigure 2

AI summary

The present invention relates to a method for operating a machine tool, in particular a gear cutting machine, with at least two machine tables, with at least one common support, and with at least two counter-support arms, wherein the clamping forces at the respective position are controlled and/or regulated depending on the current process and depending on the process forces required according to the current process. Furthermore, the present invention relates to a machine tool, in particular a gear cutting machine.