Shrink-Fit Chuck Rib Positioning for Accurate Tool Shank Alignment

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Solution Overview

Problem

Existing shrink-fit chucks for clamping tools in machine tools face challenges in accurately positioning the tool shank due to the need for precise angular alignment, which is often achieved inadequately with spring-loaded positioning screws.

Innovation Solution

A shrink-fit chuck design featuring a rib transverse to the receiving bore that allows angular positioning of the tool shank by aligning with a parallel clamping surface, combined with an off-center threaded bore for the clamping screw to prevent axial withdrawal and rotation, ensuring secure clamping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a spring-loaded positioning screw is used to achieve angular positioning of the tool shank, then the tool can be positioned at the correct angle, but the positioning accuracy and reliability are insufficient

Engineering Contradiction:
Improveangular positioning accuracyVSAvoidpositioning reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the spring-loaded positioning screw mechanism with a rib-clamping surface geometric constraint system. The rib on the chuck wall engages with the clamping surface on the tool shank, creating a deterministic mechanical stop that provides both angular positioning and reliability without requiring adjustable screws or springs.

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

Solution Approach 2:

The rib is positioned asymmetrically relative to the receiving bore center, and the clamping surface on the tool shank is oriented at a specific angle. This asymmetric geometric configuration ensures that the tool shank can only be fully inserted when aligned at the correct angular position, providing precise and reliable angular positioning through geometric constraint rather than adjustable mechanical elements.

Inventive Principle:
Principle #4Asymmetry

2Stability of the object's composition

If the clamping screw is positioned off-center to prevent rotation, then rotational stability is improved, but the complexity of the threaded bore positioning increases

Engineering Contradiction:
Improverotational stabilityVSAvoidthreaded bore positioning complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the angular positioning function (performed by the rib) with the rotational stability function (performed by the off-center clamping screw). The rib ensures correct angular alignment during insertion, while the off-center clamping screw prevents rotation during operation. By combining these two functions in a coordinated system, the patent achieves both positioning accuracy and rotational stability without significantly increasing overall device complexity.

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

The solution enables precise angular positioning and secure clamping of the tool shank, preventing axial withdrawal and rotation, enhancing the chuck's functionality and reliability.

Implementation Method 1

As the object is inserted into the receiving bore, its free end eventually abuts the rib, which initially prevents further axial insertion of the object. The operator then rotates the object so that the rib in the receiving bore and the clamping surface on the outer surface of the object to be clamped are aligned parallel

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

into which a tool shank of the tool to be clamped (e.g. milling cutter) can be inserted, in order to be clamped when the previously heated shrink-fit chuck cools down

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP3448607B1Shrink-fit chuck
Publication Date: 2022.09.28 KARL SCHUSSLER
  • EP3448607B1 patent drawingFigure 1~2
  • EP3448607B1 patent drawingFigure 3~4
  • EP3448607B1 patent drawingFigure 5~7

AI summary

The invention relates to a shrink-fit chuck (1) for clamping an object, in particular for clamping a milling cutter in a milling machine, comprising a cylindrical receiving bore (3) for receiving a cylindrical shaft of the object to be clamped. The receiving bore (3) runs in the shrink-fit chuck (1) and is delimited on the outside by a wall (4). The shrink-fit chuck (1) according to the invention is characterized by a rib (12) which runs transversely to the longitudinal axis (13) of the receiving bore (3) and protrudes from the wall (4) of the receiving bore (3) into the receiving bore (3) such that the rib (12) only allows the shaft (5) to be completely inserted into the receiving bore (3) in a specific angular position of the shaft (5).