Ejector Drill Head With Interchangeable Inserts
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Solution Overview
Problem
Deep hole drilling systems, such as Single Tube and Double Tube systems, face issues like work hardening and embrittlement of materials due to excessive wear pad forces and single cutting edge limitations, leading to inefficiencies and high costs from frequent tool replacements.
Innovation Solution
A drilling head design featuring a tubular shank with interchangeable cutting inserts, including a self-centering point, cutting lips, and carbide cladding, which reduces wear and allows for efficient chip formation and evacuation, minimizing radial loads and heat generation, and enabling easy replacement of worn cutting edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single cutting edge is used in deep hole drilling, then penetration rate is improved, but the tool tends to cut on itself causing significant stresses and work hardening
Solution Approach 1:
The single cutting edge is segmented into multiple cutting edges (typically two or more) distributed around the drill bit periphery. This segmentation allows the cutting action to be distributed across multiple points, reducing the concentration of stress on any single point while maintaining effective material removal capability.
Solution Approach 2:
Multiple cutting edges are merged into a single drill bit structure, working in unison to perform the cutting operation. This combining of multiple cutting elements provides balanced cutting forces that prevent the drill from cutting on itself, reducing work hardening and material stress while maintaining high penetration rates.
2Stability of the object's composition
If a wear pad is used to support the drill, then stability is improved, but the wear pad bears on the hole sides with significant force causing work hardening and embrittlement
Solution Approach 1:
The wear pad component is completely removed from the drill structure. Instead of using a wear pad that contacts the hole walls, the drill relies on its multiple cutting edges and balanced geometry to maintain stability without exerting lateral forces on the hole sides, thereby eliminating work hardening and embrittlement caused by pad contact.
Solution Approach 2:
The multiple cutting edges serve as intermediaries that distribute the cutting and support functions. Rather than a single wear pad bearing directly on the hole walls, the cutting edges themselves provide structural support through their distributed configuration, mediating between the drill body and the workpiece without causing harmful contact forces.
3Productivity
If cutting edges are made of hardened steel or brazed inserts, then cutting performance is improved, but the cutting edges are difficult to replace or re-sharpen and must be discarded when worn
Solution Approach 1:
The cutting edges are segmented as separate, interchangeable inserts rather than being integral to the drill body. Each cutting insert can be independently removed and replaced when worn, allowing rapid maintenance without discarding the entire drill assembly. This segmentation maintains high cutting performance while dramatically improving ease of repair.
Solution Approach 2:
Instead of discarding the entire drill when cutting edges wear, only the worn cutting inserts are discarded or sent for re-sharpening. The drill body and other components are recovered and reused with new or reconditioned inserts, reducing waste and maintenance costs while preserving cutting performance.
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 enhances hole straightness, reduces work hardening, and lowers costs by allowing for efficient chip formation and evacuation, increasing penetration rates, and reducing the need for frequent tool replacements, thus improving drilling efficiency and reducing material stress.
Implementation Method 1
A portion of the cutting fluid is directed internally into the inner tube through venturi slots manufactured into the inner tube wall. The remaining cutting fluid proceeds to the cutting edge in order to cool and lubricate the tool. The cutting fluid diverted through the venturi slots creates a low pressure area in the inner tube drawing cutting fluid and chips from the cutting edge through the drilling head and into the inner tube.
Data Source
AI summary
A drilling head for a tubular shank having an inside diameter and threads may comprise an axial body comprising a duct exiting through a first end; threads adjacent the first end corresponding to the threads on the shank and aligning the duct with the shank inside diameter; a bore from an outer surface of the body to the duct; and two axially extending approximately parallel and offset surfaces adjacent a second end; and an insert affixed between the offset surfaces, the insert comprising: a first face at least partially contacting one offset surface and a second face at least partially contacting the other offset surface; one or more cutting edges adjacent the first face, the second face, or both; and a cutting lip adjacent one or more cutting edges.