Spring Arrangement for Tensioning Device with Articulated Flexural Rods

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Solution Overview

Problem

Existing spring arrangements in clamping devices for machine tools suffer from reduced stability and service life due to end stress on buckling rods, leading to potential damage and failure.

Innovation Solution

A spring arrangement featuring flexural rods made of fiber composite materials connected to support devices via pivotable intermediate pieces, allowing for free tilting and reduced stress, with a pendulum-like bearing mechanism that distributes load and ensures defined bending with minimal pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the ends of the buckling rods are clamped in the slots of the receiving devices, then the spring arrangement can generate the required pull-in force, but the ends of the buckling rods are pressed against the edges at the exit of the slots which leads to notches or other damage and reduced service life

Engineering Contradiction:
Improvepull-in forceVSAvoidservice life
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent introduces an intermediate piece (Gelenkstück) as a mediator between the buckling rod end and the support device. This intermediate piece is pivotably mounted on the support device and allows the buckling rod end to articulate freely during compression, preventing direct contact with the slot edges that would cause notching and damage. The intermediate piece absorbs the stress concentration that would otherwise occur at the rod ends.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the ends of the bending rods are pressed against a fixed lateral abutment of a receptacle, then the spring arrangement provides structural support, but the stress on the bending bars in the area of the ends increases considerably reducing stability

Engineering Contradiction:
Improvestructural stabilityVSAvoidrod end strength
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The patent transforms the static connection between the buckling rod and support device into a dynamic articulated connection. The intermediate piece can pivot freely, allowing the rod end to tilt in the bending direction without being constrained by a fixed lateral abutment. This dynamic capability reduces stress concentration at the rod ends while maintaining structural stability through the pivotable connection.

Inventive Principle:
Principle #15Dynamics

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 enhances the stability and service life of the spring arrangement by reducing end stress on the flexural rods, enabling high stability and adaptability through a combination of spring units, while ensuring efficient clamping and release operations.

Implementation Method 1

The intermediate pieces and the joint supports thus form a type of pendulum or pivot bearing for the ends of the bending bars, which ensures a defined bending of the bending bars with the lowest possible load.

Methodology Applied
Scientific EffectPendulum: Pendulum

Implementation Method 2

a spring arrangement (17) for generating the pull-in force of a tensioning device (2), comprising a plurality of support devices (22, 23, 24) spaced apart from one another in the axial direction, between which a plurality of flexural rods (25) spaced apart from one another in the circumferential direction are arranged

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3292932B1Spring arrangement for generating the draw-in force of a tensioning device and tensioning device with such a spring arrangement
Publication Date: 2019.05.15 OTT JAKOB & SPANNTECHN
  • EP3292932B1 patent drawingFigure 1
  • EP3292932B1 patent drawingFigure 2
  • EP3292932B1 patent drawingFigure 3

AI summary

The invention relates to a spring arrangement (17) for generating the clamping force of a clamping device with several axially spaced support devices (22, 23, 24), between which several circumferentially spaced bending bars (25) made of a fiber composite material are arranged. The ends of the bending bars (25) are pivotally connected to the support devices (22, 23, 24) via an intermediate piece (33) pivotally mounted on each of the support devices (22, 23, 24).