Insert Holder With Measurement Cavities for Cutting Force Detection

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Solution Overview

Problem

Existing insert holders for machine tools struggle to accurately measure cutting forces during finishing or semi-finishing operations due to low machining forces, which conventional sensors like wattmeters and piezoelectric dynamometers cannot reliably detect without being expensive and impractical for all machine tools.

Innovation Solution

An insert holder with symmetrically arranged measurement cavities and strain gauges on its body, designed to amplify shear deformations caused by tangential cutting forces, allowing precise measurement of cutting forces while using standard cutting inserts without modifications, and featuring a Wheatstone bridge configuration to minimize the influence of other forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sensors like wattmeters are used to measure cutting forces, then the measurement can be carried out with simple equipment, but the measurement precision is insufficient for finishing or semi-finishing operations with low machining forces

Engineering Contradiction:
Improvecutting force measurement precisionVSAvoidsensor complexity and cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The insert holder body is segmented by forming measurement cavities that create localized measurement zones. This segmentation allows the strain gauges to focus on measuring deformations in specific regions, improving measurement precision for low cutting forces while keeping the overall device structure relatively simple

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The insert holder body acts as an intermediary element that translates cutting forces into measurable deformations. By incorporating measurement cavities and strain gauges, the holder mediates between the cutting insert and the measurement system, enabling precise force measurement without requiring complex external sensors

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If piezoelectric dynamometers are used to measure cutting forces with high precision, then the measurement precision is satisfactory even for low machining forces, but the device becomes very expensive and installation becomes impossible in certain machine tools

Engineering Contradiction:
Improvecutting force measurement precisionVSAvoidmanufacturing cost and installation feasibility
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The insert holder serves itself as the measurement platform by integrating measurement cavities and strain gauges directly into its structure. This self-service approach eliminates the need for expensive external piezoelectric dynamometers, making the system cost-effective and easier to manufacture and install in various machine tools

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The measurement function is merged with the insert holder structure itself. The holder body, measurement cavities, and strain gauges form an integrated system that combines the mechanical support function with the measurement function, reducing the need for separate expensive measurement devices

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If measurement cavities are formed in the insert holder body, then the deformation amplification improves measurement precision, but the structural strength of the holder may be compromised

Engineering Contradiction:
Improvedeformation measurement precisionVSAvoidinsert holder structural strength
Core Design Contradiction:
Measurement precisionVSStrength

Solution Approach 1:

The measurement cavities create local quality changes in the insert holder body, concentrating the measurement function in specific regions while maintaining the overall structural integrity. The cavities are positioned and sized to amplify deformations locally without compromising the global strength of the holder

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The geometry parameters of the insert holder body are changed by forming measurement cavities with specific dimensions and positions. These parameter changes are optimized to provide sufficient deformation amplification for precise measurement while maintaining adequate structural strength for withstanding cutting forces

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

Enables accurate and cost-effective measurement of cutting forces in various turning operations, improving machining precision and productivity without damaging the insert holder's resistance or requiring expensive sensors.

Implementation Method 1

at least a first strain gauge configured to measure the deformation of the flat bottom of at least one of the two measurement cavities

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP2978565B1Insert holder for a machine tool
Publication Date: 2017.11.01 CENT TECHN DE LIND DU DECOLLETAGE
  • EP2978565B1 patent drawingFigure 1~3
  • EP2978565B1 patent drawingFigure 4~5
  • EP2978565B1 patent drawingFigure 6a~6b

AI summary

The invention relates to an insert holder for a tool for turning a machine tool, comprising an insert holder body (2), the head (22) of which is intended to receive a cutting insert (3), characterized in that at least two measurement recesses (4, 5) are provided in the insert holder body (2) on the side of the head (22), said measurement recesses (4, 5) being arranged symmetrically relative to the neutral fiber (6) of the insert holder body (2) and centered on the neutral fiber (6). The measurement recesses (4, 5) have, respectively, a planar bottom (41, 51) that is parallel to the direction (Y) of the component of the tangential cutting force of the insert holder to be measured, and parallel to the longitudinal direction (X, Z) of the insert holder body (2). The insert holder also comprises at least one first strain gauge (71, 72, 73, 74) configured such as to measure the change in shape of the planar bottom (41, 51) of at least one of the measurement recesses (4, 5).