Reciprocating Tribology Tester Layout for Rocking Error Reduction
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Solution Overview
Problem
Existing tribology testers face challenges in accurately measuring friction and wear at high-speed reciprocating motions due to parasitic frictional forces caused by rocking motions of the sample holder, leading to measurement inaccuracies and errors in normal force application.
Innovation Solution
The implementation of a universal tester with a linear vertical bearing and a horizontally-sliding element between the rod pusher and vertical force sensor, which reduces the amplitude of tilting motion and allows for precise measurement of frictional forces at high reciprocating speeds by decoupling the upper module from the beam, using piezo-electric elements for improved force sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sample holder configuration is used in tribology testers, then the device structure is simple, but parasitic frictional forces are generated due to rocking motions of the sample holder during high-speed reciprocating motion, leading to measurement inaccuracies
Solution Approach 1:
The sample holder assembly is segmented into separate functional components: a linear vertical bearing isolates the sample holder from the beam structure, while a horizontally-sliding element separates the rod pusher from the vertical force sensor. This segmentation allows each component to perform its specific function independently, reducing parasitic frictional forces and improving measurement accuracy without creating an overly complex integrated structure.
Solution Approach 2:
The linear vertical bearing acts as an intermediary element between the sample holder and the beam, eliminating rocking motions by providing a guided vertical movement path. The horizontally-sliding element serves as an intermediary between the rod pusher and the vertical force sensor, allowing horizontal compensation of frictional forces. These intermediary components resolve the contradiction by introducing controlled complexity that directly improves measurement precision.
2Productivity
If high-speed reciprocating motion is applied to test materials, then productivity and testing speed are improved, but measurement errors increase due to amplified rocking motions and parasitic frictional forces
Solution Approach 1:
The apparatus employs dynamic elements including a linear vertical bearing that allows controlled vertical movement of the sample holder during high-speed reciprocating motion, and a horizontally-sliding element that dynamically compensates for horizontal displacements. These dynamic components enable the system to maintain measurement precision at high testing speeds by adapting to the changing mechanical conditions during rapid reciprocating motion.
Solution Approach 2:
The conventional mechanical coupling between the sample holder and the measurement system is replaced with a piezo-electric force sensor that electronically measures forces with high precision. This substitution of mechanical sensing with piezo-electric sensing enables accurate friction and wear measurements at high-speed reciprocating motion where traditional mechanical sensors would be overwhelmed by parasitic forces and vibrations.
3Adaptability or versatility
If a universal tester configuration is used instead of dedicated testers, then adaptability and versatility are improved, but measurement precision deteriorates due to increased device complexity and potential sources of error
Solution Approach 1:
The apparatus is designed as a universal tester with a modular sample holder assembly that can accommodate different test configurations while maintaining high measurement precision. The linear vertical bearing and horizontally-sliding element are integral components that work across multiple test types, eliminating rocking motions and parasitic frictional forces regardless of the specific test configuration being used, thus achieving both versatility and precision.
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 configuration significantly reduces measurement errors and enhances the accuracy and repeatability of friction and wear measurements, enabling testing at high reciprocating speeds previously only attainable with dedicated machines.
Implementation Method 1
the horizontal force sensor may include a piezo-electric element
Data Source
AI summary
System for conducting measurements of friction of a chosen material with reduced errors. The system includes a sample holder, a bushing accommodating such holder while permitting reversible repositioning of the holder along a bushing axis, a horizontal force sensor, a vertical force sensor, a sample holder pusher and a subsystem including a linear vertical bearing (disposed in the bushing and separating the holder from the bushing) and/or a horizontally-sliding element between the rod pusher and the vertical force sensor. The subsystem is structured to reduce a rocking motion of the holder in the bushing caused by a relative motion between the sample and an auxiliary body brought in contact with the sample. The method for performing measurements with such system.