Pneumatic Grip Pressure Control for Safe Materials Testing

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Solution Overview

Problem

Materials testing systems face safety concerns due to rapid grip closure, potential specimen damage, and lack of reliable pressure control, which affects result repeatability and accuracy, with manual pressure settings being time-consuming and unreliable.

Innovation Solution

An electronic control system for hydraulic or pneumatic components that allows adjustable low gripping pressure for safety, slow grip closure, and automatic pressure ramp-up to full pressure, with firmware logging and checking pressure settings to ensure test initiation only when target pressure is achieved.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual pressure setting is used for each specimen type, then pressure control is simple, but it is time-consuming and impacts repeatability of results

Engineering Contradiction:
Improvepressure setting simplicityVSAvoidtime for pressure setting
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The system automatically determines and sets the gripping pressure based on the specimen type selected in the test parameters, eliminating the need for manual pressure setting by the operator. The control unit retrieves the appropriate pressure value from stored data associated with the specimen type and automatically configures the pneumatic system.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The manual mechanical adjustment of pressure is replaced by an automated electronic control system that reads specimen type information and automatically sets the pressure parameters, substituting operator action with automated computational and control processes.

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

2Force

If full test pressure is applied during grip closure, then gripping force is sufficient, but it creates safety hazards and may damage the specimen

Engineering Contradiction:
Improvegrip forceVSAvoidsafety hazard and specimen damage
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The grip closure process is divided into two distinct phases: a first phase at reduced pressure for safe initial closure and positioning, and a second phase at full test pressure for achieving the required gripping force. This segmentation allows the system to avoid applying full pressure during the potentially hazardous initial closure while still achieving sufficient grip strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs a preliminary grip closure at reduced pressure before applying full test pressure. This preliminary action positions the grips safely on the specimen without the full force that would cause damage or safety hazards, and only after this preliminary positioning does the system proceed to apply the full required pressure.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If pressure feedback is implemented, then pressure control is improved, but it may impact the accuracy of the results

Engineering Contradiction:
Improvepressure control reliabilityVSAvoidtest result accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The pressure feedback signal is extracted and used solely for control purposes to maintain the desired gripping pressure, while the actual test measurements are taken through separate, independent sensing channels. This separation ensures that the feedback control system does not interfere with or contaminate the test result measurements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses an intermediary control mechanism that regulates pressure based on feedback signals, acting as a mediator between the pressure source and the specimen. This intermediary control ensures stable pressure application without directly interfering with the measurement process, maintaining both pressure reliability and measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Productivity

If fast closing rate is used, then test setup time is reduced, but it may pinch user fingers or damage the specimen

Engineering Contradiction:
Improvetest setup speedVSAvoidpinch injury and specimen damage
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The grip closure speed is made dynamic rather than fixed: the system initially closes at a reduced speed for safety during positioning, then automatically transitions to a faster closing rate once the grips are properly positioned on the specimen. This dynamic adjustment maintains safety during the critical positioning phase while achieving productivity gains during the subsequent rapid closure phase.

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

Enhances user safety, improves result repeatability, and ensures accurate pressure control, preventing tests from proceeding unless proper pressure is reached, thereby increasing the reliability and safety of materials testing.

Implementation Method 1

a pneumatic control system to open and close the grips and to regulate the pressure

Methodology Applied
Scientific EffectPneumatic pressure: Pressure Increase

Implementation Method 2

receive pressurized air through pressurized air supply

Methodology Applied
Scientific EffectGas compression: Compression

Data Source

PatentEP3440364B1Materials testing system and method
Publication Date: 2021.12.08 ILLINOIS TOOL WORKS INC
  • EP3440364B1 patent drawingFigure 1
  • EP3440364B1 patent drawingFigure 2
  • EP3440364B1 patent drawingFigure 3

AI summary

The present disclosure relates to an electronic control system for pneumatic grips, using proportional air pressure control, as employed in the field of materials testing. The disclosed embodiments allow for variable gripping pressure thereby increasing the safety for the user/operator. Additionally, materials testing will not commence until the proper pressure for testing has been achieved.