Crosshead Braking Configuration to Prevent Backdrive in Material Testing

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Solution Overview

Problem

Material testing machines face challenges in safely moving and securing a crosshead with increased mass due to the application of larger forces, leading to potential backdrive and uncontrolled motion.

Innovation Solution

The implementation of an electric machine with a driving and braking configuration, controlled by a switching device, which connects the winding in a low resistance configuration to prevent backdrive, and an electric clamping mechanism to secure the crosshead to the guide, reducing the risk of uncontrolled motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the mass supported by the crosshead is increased to apply larger forces, then the testing capability is improved, but the risk of backdrive and uncontrolled motion increases

Engineering Contradiction:

Improvetesting forceVSAvoidcontrol stability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The electric machine is configured into a braking configuration immediately after the crosshead completes its movement. This preliminary anti-action prevents backdrive by creating a counter-torque that opposes any potential reverse motion caused by the increased mass, thereby maintaining control stability while enabling larger testing forces

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful effect of gravitational force causing backdrive into a beneficial braking force. By configuring the electric machine's winding with a low resistance connection, the system generates electromagnetic braking that utilizes the potential backdrive energy to slow and secure the crosshead, transforming a reliability risk into a control mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Force

If the crosshead mass is increased to support larger forces, then the testing capability is improved, but the safety of moving and securing the crosshead deteriorates

Engineering Contradiction:

Improvetesting forceVSAvoiduncontrolled motion

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The controller configures the electric machine into braking configuration as soon as the crosshead completes its movement. This preliminary anti-action counteracts the gravitational force on the increased mass before uncontrolled motion can occur, preventing harmful effects while maintaining the capability to support larger testing forces

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system converts the potentially harmful gravitational force acting on the increased crosshead mass into a beneficial braking mechanism. The electromagnetic braking generated by the low resistance winding configuration utilizes the downward motion energy to create a securing effect, transforming the harm of increased mass into a safety feature

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This solution effectively prevents backdrive and ensures safe operation by immediately configuring the electric machine into a braking state after movement completion and applying a releasable clamping force, thereby securing the crosshead and maintaining control during testing.

Implementation Method 1

the crosshead drive means is driven by an electric machine in a driving configuration

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

configure the electric machine into a braking configuration, wherein in the braking configuration a winding of the electric machine is connected together with a low resistance connection

Methodology Applied

Scientific EffectElectromagnetic braking: Electromagnetic Induction

Data Source

PatentUS11788940B2Apparatus and method for material testing including configuring an electrical machine in a braking configuration

Publication Date: 2023.10.17 ILLINOIS TOOL WORKS INC

AI summary

An example material testing apparatus includes: guide means; sample test means for holding a sample and applying a test force to the sample; a crosshead arranged to support at least a portion the sample test means, wherein the crosshead is moveable about the guide means; crosshead drive means for moving the crosshead generally vertically about the guide means, wherein the crosshead drive means is driven by an electric machine in a driving configuration; and a controller arranged to: configure the electric machine into the driving configuration; control the crosshead drive means to move the crosshead generally vertically about the guide means; and configure the electric machine into a braking configuration, wherein in the braking configuration a winding of the electric machine is connected together with a low resistance connection.