Chain Tensioning Assembly With Strain-Based Retensioning Control

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Solution Overview

Problem

Chain assemblies in double-end tenoners experience significant tension loss over time, leading to operational discrepancies between units and resulting in faulty machining of workpieces due to unintentional rotation, necessitating manual and infrequent tension adjustments.

Innovation Solution

A chain assembly with a drive head, deflection unit, and tensioning system equipped with a strain gauge and evaluation unit to continuously monitor and automatically adjust chain tension, ensuring synchronized operation and preventing workpiece rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual tension adjustment is used during routine maintenance, then the chain tension can be readjusted, but the chain tension drops significantly before the next maintenance causing operational discrepancies

Engineering Contradiction:
Improvechain tension stabilityVSAvoidtime between maintenance intervals
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements a feedback mechanism by installing a strain gauge on the transmission device to continuously monitor chain tension. The measured strain data is processed by an evaluation unit that compares actual tension against reference values and triggers automatic retensioning when deviations exceed a threshold, ensuring continuous tension stability without manual intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-service by automatically detecting chain tension deviations and triggering the retensioning process through an actuator. The evaluation unit autonomously determines when retensioning is needed and controls the actuator to adjust the tensioning element, eliminating the need for manual maintenance checks and adjustments.

Inventive Principle:
Principle #25Self-service

2Manufacturing precision

If chain tension is not monitored continuously, then the system operation is simple, but workpieces may rotate around vertical axis causing faulty machining

Engineering Contradiction:
Improveworkpiece machining qualityVSAvoidmonitoring system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical tension monitoring mechanisms with an electrical sensing system. A strain gauge converts mechanical chain tension into an electrical signal that is processed by an evaluation unit, providing precise tension measurement without the complexity of mechanical dial indicators or gauge systems.

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

Solution Approach 2:

The strain gauge acts as an intermediary element that indirectly measures chain tension by detecting strain in the transmission device. This indirect measurement approach allows tension monitoring without direct contact with the chain, simplifying the monitoring system while maintaining measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If multiple chain units are used to transport workpieces, then workpieces can be moved along machining path, but speed discrepancies cause workpiece rotation around vertical axis

Engineering Contradiction:
Improveworkpiece transport capabilityVSAvoidsynchronization between chain units
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements feedback control by continuously monitoring chain tension in each chain unit and comparing it against reference values. When tension deviations indicate speed discrepancies, the system automatically triggers retensioning to restore proper tension and synchronization, ensuring reliable operation of multiple chain units working in parallel.

Inventive Principle:
Principle #23Feedback

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 continuous monitoring and automatic tension adjustment, significantly reducing the risk of workpiece damage and economic losses by maintaining consistent chain tension and preventing unintended tilting during machining.

Implementation Method 1

a strain gauge (18) arranged on the transmission device (15), which is designed and set up to acquire information regarding deformation of the transmission device (15) resulting from the action of the clamping force of the clamping element (10) and the derivation of this clamping force to the two guide axes (16, 17)

Methodology Applied
Scientific EffectStrain gauge measurement: Deformation

Data Source

PatentEP4516701B1Chain assembly and method for operating same
Publication Date: 2025.12.17 G KRAFT MASCHENBAU
  • EP4516701B1 patent drawingFigure 1
  • EP4516701B1 patent drawingFigure 2
  • EP4516701B1 patent drawingFigure 3

AI summary

The present application relates to a chain assembly (1) comprising a rotatable sprocket (3), a deflection unit (5), a self-contained chain (8) and a tensioning system (9) for tensioning the chain (8).The clamping system (9) comprises a clamping element (10), an adjusting element (11) for setting a clamping force of the clamping element (10), a support (12) for supporting a first end of the clamping element (11), a transmission device (15) for supporting a second end (14) of the clamping element (10), and two guide axes (16, 17) connected to the transmission device (15), wherein a clamping force introduced into the transmission device (15) as a result of the support of the clamping element (10) can be transferred to the two guide axes (16, 17) by means of the transmission device (15), wherein the deflection unit (5) is mounted by means of the guide axes (16, 17) so that it can be pressed against the chain (8) by means of the clamping force of the clamping element (10), and thereby the chain (8) can be tensioned.In order to provide a chain assembly whose operation is possible with a lower risk of fault operation compared to the prior art, a strain measuring device (18) is proposed which is arranged on the transmission device (15) in such a way that it is designed to record information concerning a deformation of the transmission device (15) which occurs as a result of the action of the tension force and its transmission to the guide axes (16, 17).