Deformable Surface Finish Stylus Contact Element
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Solution Overview
Problem
Machine tool scanning probes apply high contact forces during surface finish measurements, leading to potential damage and inaccuracy due to excessive pressure on the surface being measured.
Innovation Solution
A surface finish stylus with a deformable contact element clamped to an elongate stylus shaft, featuring a low stiffness material with high hardness, allowing for precise measurement of surface roughness and waviness while minimizing surface damage, and enabling easy replacement of the contact element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a machine tool scanning probe is used for surface finish measurements, then the measurement can be performed on-machine, but the high spring forces applied by the probe cause excessive contact force that can damage the surface being measured
Solution Approach 1:
The patent changes the mechanical parameters of the contact element by using a deformable material with specific stiffness characteristics. The contact element is designed to deform under load, automatically reducing the contact force to a safe level that prevents surface damage while maintaining measurement capability. This parameter change allows the system to operate safely with machine tool scanning probes that inherently apply high forces.
Solution Approach 2:
The deformable contact element acts as a cushioning element that absorbs excess force before it reaches the workpiece surface. The compliant material prevents direct transmission of high spring forces from the probe to the measured surface, thereby protecting the surface from damage while enabling on-machine measurement.
2Stability of the object's composition
If a stiff contact element is used to maintain probe position, then measurement stability is improved, but surface damage increases due to high contact pressure
Solution Approach 1:
The patent changes the stiffness parameter of the contact element to an intermediate value that provides both stability and compliance. The contact element has sufficient stiffness to maintain probe position and resist lateral forces, but enough compliance to deform under axial load and reduce contact pressure to safe levels. This optimized parameter balance resolves the contradiction between stability and surface protection.
Solution Approach 2:
The contact element transitions from a static rigid structure to a dynamic compliant structure that adapts its stiffness based on loading conditions. Under light loads, it maintains position stability; under heavy loads, it deforms to reduce contact pressure. This dynamic behavior allows the system to maintain stability while protecting the surface.
3Measurement precision
If a deformable contact element is used to reduce surface damage, then measurement accuracy is improved, but the contact element may wear or deform permanently
Solution Approach 1:
The patent employs a contact element made from inexpensive, replaceable material that can withstand a limited number of measurement cycles. The contact element is designed as a consumable component that is replaced when worn or permanently deformed, ensuring measurement accuracy is maintained throughout its service life. This approach prioritizes measurement precision while accepting periodic replacement of the contact element.
Solution Approach 2:
The patent selects materials with specific mechanical parameters that optimize the balance between compliance for accurate measurement and durability for reliability. The material parameters are chosen to provide sufficient elasticity for following surface features while maintaining resistance to wear and permanent deformation over the intended service life.
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 deformable contact element reduces surface damage and enhances measurement accuracy by minimizing contact pressure, allowing for precise surface finish measurements with improved durability and ease of maintenance.
Implementation Method 1
The contact element is deformable and the stylus shaft comprises a clamp for retaining the contact element, the contact element being deformed by the clamp
Data Source
AI summary
A surface finish stylus is described that includes an elongate stylus shaft and a contact element protruding from the elongate shaft for contacting a surface to be measured. The contact element is deformable and the stylus shaft includes a clamp for retaining the contact element, the contact element being deformed by the clamp. The contact element may comprise a metal, such as chromium steel or nitinol. The contact element includes one or more regions of weakness to cause a required deformation when retained by the clamp. The surface finish stylus may be used with a surface finish measurement probe or the like.