Rock Drill Bolt With Flat Collar Surface for Rotational Fixation
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Solution Overview
Problem
Bolts in rock drills experience wear damage and fatigue fractures due to normal forces at contact points when the eccentric collar locks the bolt in rotational direction, leading to potential bolt failure during operation.
Innovation Solution
A bolt design featuring an elongated body with a central axis, a collar with flat surfaces parallel to the axis for rotational fixation, and threaded ends, which eliminates the need for the bolt to abut the housing, thereby reducing normal forces and distributing forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the eccentric collar locks the bolt in rotational direction together with the cylindrical surface of the bolt, then the bolt is fixed against rotation in the housing part, but large normal forces occur in contact points causing wear damages and fatigue cracks
Solution Approach 1:
The invention extracts the rotational fixation function from the cylindrical surface of the bolt to a dedicated flat surface on the collar. By providing a flat surface on the collar that abuts against a corresponding flat surface in the housing part, the bolt achieves rotational fixation without relying on friction between the cylindrical surface and housing, thereby eliminating the harmful normal forces that caused wear and fatigue cracks.
Solution Approach 2:
The flat surface on the collar acts as an intermediary element between the bolt and the housing part for rotational fixation. Instead of the cylindrical surface directly contacting the housing, the flat surface mediates the rotational constraint, distributing forces more evenly and avoiding concentrated normal forces that led to wear damages.
2Object-affected harmful factors
If the collar is provided with a flat surface extending parallel to the central axis, then the bolt achieves rotational fixation without abutting the housing, but the collar structure becomes more complex
Solution Approach 1:
The invention applies local quality by providing a flat surface only on the collar where it is needed for rotational fixation, rather than changing the entire bolt structure. This localized modification maintains the cylindrical shape of the collar body while adding a specific functional feature (the flat surface) that eliminates wear damages without significantly increasing overall structural complexity.
Data Source
AI summary
Herein a bolt (2) comprising an elongated body (4) with a central axis (C) is described. The elongated body (4) is in a first end (6) provided with a first thread (8) and in a second end (10) with a second thread (12). An intermediate part (14) of the elongated body (4) is provided with a collar (16). The collar (16) is provided with at least one first flat surface (18), which first flat surface (18) extends substantially in parallel with the central axis (C). Further, a rock drill comprising housing parts held together by at least one bolt (2) is described.