Cutting Bit Recess Geometry for Contaminant Exclusion
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Solution Overview
Problem
Cutting bits in rock cutting machines often experience hindered rotation and premature wear due to dust and contaminant particles entering the recess region, leading to decreased operational lifetime and potential damage to the bit holder.
Innovation Solution
A cutting bit with a recess having a stepped internal surface profile, featuring a convex and/or radially outward tapered surface, and a matching projection with a concave and/or radially outward tapered surface, which inhibits axial advancement of contaminants and optimizes load transfer, ensuring self-centering and effective contaminant exclusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional recess mounting is used, then the cutting bit can be mounted and rotated, but dust particles and contaminants enter the recess causing hindered rotation and premature wear
Solution Approach 1:
The recess internal surface is segmented into multiple zones with different geometric profiles: a mouth region, a transition region with convex/tapered profile, and an innermost region. This segmentation creates a stepped configuration that segments the contaminant flow path, preventing particles from reaching the critical mounting interface while maintaining functional clearance.
Solution Approach 2:
The convex and/or tapered transition surface acts as an intermediary barrier between the contaminant-laden external environment and the protected mounting interface. This intermediate geometric feature redirects contaminant flow away from the recess interior while maintaining the rotational functionality of the cutting bit.
2Object-affected harmful factors
If the recess profile is modified to prevent contaminant entry, then contaminant exclusion improves, but load transfer and stress distribution may be affected
Solution Approach 1:
Different regions of the recess internal surface are given different geometric qualities optimized for their specific functions: the mouth region has a configuration optimized for contaminant exclusion, the transition region has convex/tapered profiles for both contaminant redirection and stress distribution, and the innermost region maintains geometry optimized for load transfer and mounting stability.
Solution Approach 2:
The recess geometry parameters are optimized across different axial positions: the convex and/or tapered transition surface is designed with specific curvature radii and angles that simultaneously achieve contaminant flow redirection and stress distribution. The step profile dimensions are carefully selected to provide adequate contaminant barrier height while maintaining sufficient load-bearing contact area.
Data Source
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AI summary
A cutting bit and bit assembly (100) for mounting at a cutting machine. The bit comprises an axially tapered bit body (101) having a recess (201) extending axially within the body, the recess (201) having an innermost region (217) and a mouth region (218) that is generally convex and/or tapered radially outward to abut a corresponding concave or tapered surface of a projection (207) to secure the cutting bit (101) at a holder body (103). An annular step (203) is positioned within the recess at the mouth region (218) to prevent dust and contaminant fluid or particles from passing axially into the recess.