Rock Drill Shaft Helix Geometry for Dust Removal and Head Strength
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Solution Overview
Problem
Existing rock drill shafts face a challenge in improving drilling dust transport without compromising the mechanical robustness of the drill head, as deepening removal grooves can weaken the side parts due to the cutting outlet's position relative to the drill head.
Innovation Solution
The design incorporates two helical sections with different average core diameters, where the first section near the drill head has a larger diameter, and the removal grooves are machined with a grinding or milling wheel set at an angle, ensuring the cutting outlet's axial position is within a tolerance window close to the groove base, allowing for deeper grooves without weakening the drill head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the discharge grooves are deepened to improve drilling dust removal, then the drilling dust transport is improved, but the side sections of the drill head are weakened
Solution Approach 1:
The helix is divided into two sections with different core diameters: the first section near the drill head has a larger core diameter to maintain strength, while the second section further down has a smaller core diameter to enable deeper discharge grooves for improved dust removal. This local differentiation allows each section to optimize for its specific function.
Solution Approach 2:
The helix is segmented into a first spiral section and a second spiral section with distinct geometric properties. The first section maintains structural integrity near the drill head, while the second section provides enhanced dust removal capability further down the drill shaft.
2Productivity
If the cutting outlet is positioned deeper to improve dust transport, then the removal grooves reach closer to the receiving groove, but the side parts of the drill head are weakened
Solution Approach 1:
The helix is divided into two sections with different core diameters: the first section near the drill head has a larger core diameter to maintain strength, while the second section further down has a smaller core diameter to enable deeper discharge grooves for improved dust removal. This local differentiation allows each section to optimize for its specific function.
Data Source
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AI summary
The invention relates to a rock drill shaft which has a drill head at the upper end, an insertion section at the lower end and a helix in between, wherein the helix is at least double-threaded and accordingly has at least two discharge grooves (5, 6) and wherein the drill head has an end-face receiving groove (8) for receiving a cutting insert (1a).It is proposed that a first helical section adjoining the drill head and, further towards the insertion section, a second helical section are provided, that the mean core diameter of the second helical section is smaller than the mean core diameter of the first helical section, that the discharge grooves (5, 6) have been produced in a machining process using at least one grinding or milling wheel, and that the axial position Z of the drill head-side chip run-out (11) of this machining process is within a tolerance window T around the axial position N of the groove base (12) of less than T1=10% of the drill diameter D upwards and of less than T2=200% downwards.