Resistance Welding Force Sensor for Continuous Clamping Monitoring

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Solution Overview

Problem

Traditional resistance welding devices used in automated systems face challenges in continuous monitoring of welding parameters, particularly the closing force, which is influenced by external factors, leading to unreliable torque measurements and decreased productivity.

Innovation Solution

A resistance welding device equipped with a force sensor and a unique bearing assembly that allows direct detection of the constraining reaction during clamping, independent of external parameters, using a gear system and a strain gauge or load cell to measure the axial displacements caused by the clamping force, ensuring continuous monitoring and high reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If calibration stations are used for periodic checking of closing force, then measurement reliability is improved, but productivity deteriorates due to interruptions and time loss

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidproductivity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the mechanical calibration station system with an electronic sensing system. A force sensor (load cell) integrated into the welding device's mechanism electronically measures closing force in real-time, eliminating the need for periodic mechanical calibration stations and the interruptions they cause, thereby maintaining measurement reliability while preserving productivity

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

Solution Approach 2:

The patent introduces a force sensor as an intermediary element between the welding mechanism and the control system. This sensor continuously provides feedback on closing force, enabling real-time monitoring without requiring external calibration stations or interrupting the welding process, thus resolving the contradiction between reliable measurement and continuous production

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If torque constant control is used to control nominal current, then ease of operation is improved, but measurement precision deteriorates due to oscillations from external parameters

Engineering Contradiction:
Improveease of operationVSAvoidtorque measurement precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements direct feedback from a force sensor that measures closing force independently of torque constant variations. The sensor provides real-time feedback on actual closing force, allowing the control system to compensate for external parameter changes (temperature, humidity) that affect torque constant, thereby maintaining measurement precision while preserving ease of operation through electronic control

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The force sensor performs self-measurement of closing force directly at the point of application, independent of motor torque calculations. This self-service measurement approach eliminates reliance on torque constant parameters and their susceptibility to environmental variations, ensuring precise measurement while maintaining simple electronic control operation

Inventive Principle:
Principle #25Self-service

3Measurement precision

If frequent recalibration is performed to maintain measurement accuracy, then measurement precision is improved, but productivity deteriorates due to increased interruptions

Engineering Contradiction:
Improvemeasurement precisionVSAvoidproductivity
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent enables continuous measurement of closing force through an integrated force sensor that operates throughout the welding process without interruption. The sensor provides continuous feedback on closing force, eliminating the need for periodic recalibration stops, thereby maintaining measurement precision while ensuring uninterrupted welding operations and maximum productivity

Inventive Principle:
Principle #20Continuity of useful action

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 device provides continuous and reliable monitoring of welding parameters, unaffected by external factors, enhancing productivity and ensuring consistent weld quality without the need for frequent recalibration or interruption of the welding process.

Implementation Method 1

using a gear system and a strain gauge or load cell to measure the axial displacements caused by the clamping force

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP3231546B1Resistance welding device with a load sensor
Publication Date: 2019.05.15 TECNA
  • EP3231546B1 patent drawingFigure 1
  • EP3231546B1 patent drawingFigure 2
  • EP3231546B1 patent drawingFigure 3

AI summary

A resistance welding device (1) comprises movement means for mutually moving a pair of jaws (4, 5), which support respective electrodes (4a, 5a) that can be crossed by an electric current, for transition from an inactive configuration, in which the electrodes (4a, 5a) are mutually spaced, to an active configuration, in which the electrodes (4a, 5a) are mutually closer and crossed by current, for the clamping and welding of elements of various types, and vice versa. The movement means comprise a drive unit of a mechanism (6) associated with a jaw (4). The device (1) further comprises a force sensor (7), associated with an element of the mechanism (6), for detecting the constraining reaction generated by the element in the clamping configuration, which is linked directly to the clamping force of the electrodes (4a, 5a).