Chuck-Integrated Measuring Hub for Accurate Cutting Force Sensing

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Solution Overview

Problem

Existing force measurement systems for machine tools with rotating spindles face challenges in accurately measuring cutting forces due to technical difficulties in implementing sensors on workpieces or tools, leading to limited usability and accuracy in production environments.

Innovation Solution

A chuck-integrated force measurement system with a measuring hub that includes strain sensors attached to a cylindrical main body, allowing for precise measurement of cutting forces without altering machine dynamics, and utilizing simulated neural networks for quasi-real-time processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If force measurement is performed on the workpiece using force transducers on a measuring table, then the measurement can be technically simple to implement, but the workpiece mass acts as a low-pass filter attenuating high-frequency signals and the measuring table mass distorts the signal, limiting measurement reliability

Engineering Contradiction:
Improveease of implementationVSAvoidmeasurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces a measuring hub as an intermediary component between the tool and the spindle chuck. This hub contains strain sensors that directly measure forces at the cutting edge without requiring workpiece modification or heavy measuring tables. The hub acts as a mediator that captures force information at its source while avoiding the signal attenuation problems of measuring on the workpiece side.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical force transmission path through the workpiece and measuring table with a direct strain measurement system in the measuring hub. Instead of measuring forces indirectly through the workpiece mass, strain sensors in the hub directly detect the mechanical stresses at the tool-workpiece interface, eliminating the low-pass filtering effect of workpiece mass.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If force measurement is performed on the tool by installing force transducers on the cutting edge, then measurement accuracy can be improved, but sufficient installation space is not available in conventional machine tools and design modifications are required

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddesign complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measuring hub is designed as a universal adapter that can be inserted into the standard spindle chuck without modifying the machine tool. It provides force measurement functionality while maintaining compatibility with conventional tooling interfaces, making the system universally applicable to existing machine tools without custom design work.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The measuring hub is designed as a compact nested structure where the strain sensors and measurement electronics are integrated within the hub body itself. The hub contains the measurement system within its own structure, eliminating the need for external mounting space and fitting within the confined space of the spindle chuck interface.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Measurement precision

If a measuring device is used as a force-transmitting connecting element between chuck shank and chuck body, then force measurement capability is achieved, but the linear arrangement of three main components results in a relatively long design and potential impairment of overall stiffness

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidassembly length
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent merges the measuring device with the tool holder into a single integrated measuring hub component. Instead of having separate chuck shank, measuring device, and chuck body components arranged linearly, the measurement functionality is combined with the tool holding function in one compact hub that fits directly into the spindle chuck.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The measuring hub serves multiple functions simultaneously: it holds the cutting tool, transmits cutting forces, and measures those forces through integrated strain sensors. This multi-functionality eliminates the need for separate measurement components and reduces the overall assembly length compared to linear arrangements of dedicated components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Measurement precision

If a measuring device is used as a force-transmitting connecting element between chuck shank and chuck body, then force measurement capability is achieved, but the mechanical interfaces between main components may impair the overall stiffness of the assembly

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidassembly stiffness
Core Design Contradiction:
Measurement precisionVSStrength

Solution Approach 1:

The patent combines the measuring function with the force transmission path in a single integrated hub structure. The strain sensors are embedded within the hub material itself, so the measurement does not require additional mechanical interfaces that would compromise stiffness. The hub maintains a continuous, stiff load path from the cutting edge through the hub to the spindle.

Inventive Principle:
Principle #5Merging (Combining)

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 with increased usability and improved measurement accuracy, reducing computational complexity and maintaining machine rigidity.

Implementation Method 1

at least one measuring sensor in the form of a strain sensor is placed on a tool holder

Methodology Applied
Scientific EffectStrain measurement: Piezoresistive Effect

Data Source

PatentEP2103379B2Chuck-integrated force measurement system
Publication Date: 2021.01.13 PRO MICRON
  • EP2103379B2 patent drawingFigure 1
  • EP2103379B2 patent drawingFigure 2

AI summary

Chuck-integrated force measuring system has a measuring sensor and a measured value processing station, where the measuring sensor is an expansion sensor, which is placed at a tool mounting of a tool machine. A measuring hub (1) is applied as an adaptor piece into the chuck of the tool machine. The measuring hub is formed with a chuck (3) for receiving the tool.