Rotatable Tool Body Non-Planar Flange Friction Reduction
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Solution Overview
Problem
Rotatable tools used in cutting machines, such as those in the trenching and mining industries, experience premature wear and reduced useful life due to uneven wear of the hardened cutting tip caused by inadequate rotation within the tool holder, primarily due to excessive frictional resistance between the non-rotatable wear ring and the annular flange.
Innovation Solution
The tool design features an annular flange with a non-planar configuration, comprising a first annular portion contiguous with the shank and a second portion contiguous with the outer diameter of the cutting head, with a frustoconical midportion that reduces the contact area and frictional resistance, allowing only the outer perimeter of the flange to contact the wear ring, thereby minimizing rotational resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a planar annular flange contacts the wear ring over a large area, then the contact stability is improved, but the frictional resistance increases causing inadequate tool rotation
Solution Approach 1:
The annular flange is segmented into two distinct portions: a first annular portion that contacts the wear ring and a second annular portion that is axially offset. This segmentation reduces the contact area between the flange and wear ring, thereby reducing frictional resistance while maintaining stable contact through the strategically positioned first annular portion.
Solution Approach 2:
The solution transitions from a two-dimensional planar contact surface to a three-dimensional configuration with axial offset. The second annular portion is positioned at a different axial level than the first annular portion, creating a stepped or offset geometry that reduces contact area while preserving contact stability through the elevated first annular portion.
2Reliability
If the wear ring is prevented from rotating with respect to the tool holder, then wear protection is improved, but the tool rotation is inhibited due to friction
Solution Approach 1:
The annular flange is divided into two portions where only the first annular portion contacts the wear ring. This segmentation minimizes the frictional interface while maintaining the wear ring's non-rotational function, allowing the tool to rotate efficiently without compromising wear protection.
Solution Approach 2:
The contact surface is localized to only the first annular portion of the flange, which is specifically positioned to engage the wear ring. The second annular portion is excluded from contact, creating a localized friction interface that preserves wear protection while enabling free tool rotation.
3Reliability
If a compressible retainer sleeve is added to retain the wear ring, then the wear ring retention is improved, but the device complexity increases
Solution Approach 1:
A compressible retainer sleeve made of flexible material is used to retain the wear ring. The compressible nature of the sleeve allows it to conform to the cylindrical surface and provide reliable retention through friction and elastic deformation, while its thin-film structure minimizes added complexity compared to rigid mechanical retention systems.
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 design significantly reduces frictional resistance, enhancing the tool's rotational efficiency and extending its useful life by minimizing wear and maintaining the tool's sharpness, allowing for daily reuse without significant wear on the contacting surfaces.
Implementation Method 1
The frictional force generated between the forward surface of the non-rotatable wear ring and the rearward surface of the rotating annular flange of the tool inhibits rotation of the tool. It is therefore desirable to minimize the resistance forces between the wear ring and the annular flange.
Data Source
AI summary
A rotatable tool has a tool body that is generally symmetrical about a longitudinal axis, an enlarged cutting head, and a rearwardly extending shank. The shank joins the enlarged cutting head at an annular flange having an annular inner portion contiguous with the forward end of the shank and an annular outer portion contiguous with the outer circumference of the enlarged cutting head. The annular flange is not planar. Instead, the annular inner portion of the flange is positioned axially forward of the annular outer portion.