Shrink-Fit Tool Holder Heating Control Using Coil Inductance
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Solution Overview
Problem
Shrink-fit devices for tool shafts in tool holders face issues with overheating due to excessive inductive heating, leading to structural changes or cracking, and existing temperature measurement methods are inaccurate due to surface color, quality, and contamination.
Innovation Solution
A method using the present inductance of the induction coil as a measure for the sleeve part's temperature, with power supply adjustment to prevent overheating, and a compact shrink-fit device design with advanced shielding and cooling features for mobile use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inductive heating is used to heat the sleeve part of the tool holder, then the shrink-fitting process is accelerated and becomes more efficient, but the sleeve part may be overheated leading to structural changes or cracking
Solution Approach 1:
The patent implements feedback control by continuously monitoring the inductance of the induction coil during heating. Since inductance changes with temperature, the system uses this real-time feedback to adjust or terminate heating before the sleeve part reaches dangerous temperatures, thus preventing overheating while maintaining efficient heating speeds
Solution Approach 2:
The patent monitors changes in electrical parameters (inductance) of the induction coil system as the sleeve part heats up. By detecting parameter changes that correlate with temperature increase, the system can control the heating process precisely without direct temperature measurement, preventing structural damage while maintaining productivity
2Measurement precision
If infrared detector or contact sensor is used to measure temperature, then temperature monitoring is attempted, but measurement accuracy is distorted by surface color, quality, and contamination
Solution Approach 1:
The patent uses the induction coil's inductance as an intermediary parameter to indirectly measure temperature. Instead of directly measuring the sleeve part's surface temperature (which is affected by color and contamination), the system measures the electrical property of the coil that changes predictably with temperature, eliminating surface-related measurement errors
Solution Approach 2:
The patent replaces mechanical/contact-based temperature sensors with an electrical measurement approach. By measuring the inductance of the induction coil (an electrical parameter) rather than physically contacting or optically sensing the sleeve part surface, the system avoids all surface-related interference while achieving accurate temperature monitoring
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
Precise temperature control prevents damage to the shrink-fit chuck, accelerates cooling, and enables safe, efficient shrink-fitting and removal of tool shafts, while the compact design allows for mobile operation and reduced risk of overheating.
Implementation Method 1
an induction coil embodied as an annular or cylindrical coil that encompasses the sleeve part of the tool socket and is acted on by an alternating current, which preferably has a high frequency (and ideally, a frequency of greater than 1 kHz), in order to heat the sleeve part
Implementation Method 2
the induction coil has a first casing composed of magnetically conductive and electrically nonconductive material on its outer circumference, for example made of ferrite or of a powdered metal material
Implementation Method 3
the induction coil and its first casing are enclosed on the outer circumference by a second casing. This second casing is composed of magnetically nonconductive and electrically conductive material
Data Source
AI summary
The invention relates to a method for monitoring the temperature of the sleeve part of a tool holder, which sleeve part is inserted into the induction coil of a contraction device, wherein the instantaneous inductance of the induction coil is measured during the inductive heating and the current supply to the induction coil is influenced if the instantaneous inductance approaches, reaches, or exceeds a specified value.