Drill Tool Hard Material Head Cutting Edge Geometry
Solution Overview
Problem
Existing drilling tools for rock and reinforced concrete face challenges in enhancing drilling performance and robustness against reinforcement iron hits, particularly in effectively managing contact pressure and guiding behavior.
Innovation Solution
A drilling tool with a one-piece hard material head featuring cross-shaped, radially extending legs with main and secondary cutting edges, where the secondary cutting edges' envelope surface lies within the main cutting edges', concentrating axial contact pressure and providing protection against reinforcement iron hits, and optimized roof edge angles for improved performance and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the envelope surface of secondary cutting edges lies within the envelope surface of main cutting edges, then axial contact pressure is concentrated on main cutting edges improving drilling performance, but the secondary cutting edges need to provide protection against reinforcement iron hits
Solution Approach 1:
The patent applies local quality by differentiating the functions of main and secondary cutting edges through their geometric arrangement. The main cutting edges have a larger envelope surface extending radially outward to concentrate axial contact pressure for effective rock drilling. The secondary cutting edges have a smaller envelope surface that lies within the main cutting edges' envelope, positioning them to provide protective function against reinforcement iron hits while maintaining optimal drilling performance.
2Productivity
If the roof edge angle of secondary cutting edges is smaller than main cutting edges, then axial contact pressure is concentrated on main cutting edges, but the angle difference must be optimized for both drilling performance and robustness
Solution Approach 1:
The patent applies parameter changes by optimizing the roof edge angles of both main and secondary cutting edges. The main cutting edges have a larger roof edge angle optimized for concentrating axial contact pressure and achieving effective drilling performance. The secondary cutting edges have a smaller roof edge angle that provides robustness against reinforcement iron hits. The specific angle parameters are carefully selected and optimized to balance drilling efficiency with durability against unexpected impacts.
3Productivity
If secondary cutting edges are convexly curved in axial projection, then drill cuttings are better conveyed into the helical shaft, but uniform curvature is needed to avoid local points of strong curvature where cuttings can be deposited
Solution Approach 1:
The patent applies spheroidality by designing the secondary cutting edges with a convex curvature in axial projection. This convex shape facilitates the conveyance of drill cuttings into the helical shaft by creating a smooth flow path. However, the curvature is carefully controlled to be uniform, avoiding local points of strong curvature that could create accumulation zones for cuttings. The uniform convex curvature optimizes both cutting conveyance and prevents clogging.
Data Source
Figure 1a~1c
AI summary
The drilling tool (1) has a helical shaft (2), where a one-piece hard material head (4) is fixed on an axial shaft end (3). The hard material head has four cross-shaped radially extending shanks with two diametrically opposite major cutting edges (6). Auxiliary cutting edges (7) are also provided, which run from an outgoing drill bit (8) axially monotonous up to a radial external edge. A cladding surface (9) of another cutting edge lies completely within the cladding surface of the major cutting edges and affect only at the drill bit.