Single-Edge Deep-Hole Drill With External Coolant Flow Path
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Solution Overview
Problem
Conventional deep hole-forming drills face challenges in efficiently supplying coolant liquid and effectively discharging chips when using an external oil supply method, leading to poor coolant circulation and chip removal performance, especially when forming deep holes in metal workpieces without step feed.
Innovation Solution
A single-edge drill design featuring a large-diameter portion with coolant delivery grooves and a small-diameter portion that creates a supply path for coolant liquid between the drill's outer surface and the hole, ensuring efficient coolant delivery and chip discharge through a chip discharge groove with a crescent-shaped cross-section and a core-tapered groove bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coolant liquid is supplied externally to the drill, then the drill can form deep holes without internal oil supply systems, but coolant circulation becomes poor and chip discharge efficiency deteriorates
Solution Approach 1:
The drill body is segmented into a large-diameter portion and a small-diameter portion, creating distinct functional zones. The large-diameter portion houses coolant delivery grooves for coolant supply, while the small-diameter portion provides a clearance space for coolant circulation and chip discharge, resolving the contradiction between simplified external supply and effective coolant circulation.
Solution Approach 2:
The clearance space between the drill's small-diameter portion and the hole wall acts as an intermediary channel, facilitating coolant circulation from the supply grooves to the cutting edge and enabling effective chip discharge, thus maintaining reliability without complex internal systems.
2Device complexity
If a single chip discharge groove is used in the large-diameter portion, then chip discharge path is simplified, but chip discharge efficiency is insufficient for deep holes
Solution Approach 1:
The chip discharge function is enhanced by utilizing the radial dimension - the clearance space between the small-diameter portion and hole wall creates an additional discharge pathway dimension, allowing chips to be efficiently removed from deep holes without complicating the groove structure itself.
3Reliability
If coolant delivery grooves are added to the large-diameter portion, then coolant supply to cutting edge is improved, but device complexity increases
Solution Approach 1:
Coolant delivery grooves are localized to the large-diameter portion of the drill body, concentrating the coolant supply function where it is most needed while keeping the small-diameter portion simple, thus improving reliability without excessive complexity.
4Productivity
If the drill forms deep holes without step feed, then productivity is improved, but chip discharge becomes difficult and coolant circulation is insufficient
Solution Approach 1:
The combination of coolant delivery grooves in the large-diameter portion and the clearance space in the small-diameter portion creates a continuous coolant circulation path and chip discharge channel throughout the deep hole, enabling uninterrupted machining without step feed while maintaining effective chip removal and coolant delivery.
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
The drill achieves stable deep hole formation exceeding 20D without step feed, with improved coolant circulation and chip discharge efficiency, preventing chip damage to the hole surface and eliminating the need for internal oil supply systems.
Implementation Method 1
The margin includes a sub-groove twisted around the rotational axis of the drill in the direction opposite the direction in which the chip discharge groove is twisted, to extend from the shank toward the distal end of the cutting part, such that the sub-groove generates pumping action to supply coolant liquid to the cutting part
Implementation Method 2
the drill is configured such that a supply path for coolant liquid is defined between the outer peripheral surface of the small-diameter portion and the radially inner surface of a hole being formed by the drill
Data Source
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AI summary
A single-edge drill for forming a deep hole is provided which includes a body (2) and a shank (3). The body (2) has a single chip discharge groove (5) in the outer periphery thereof, and includes a small-diameter portion (2b), and a large-diameter portion (2a) having coolant delivery grooves (8) in the outer periphery thereof. The body (2) has a core thickness at the distal end portion of the large-diameter portion (2a). At the other portion of the body (2), the groove bottom (5a) of the chip discharge groove (5) is located beyond the rotation center (O) of the drill such that the body (2) has no core thickness, and when taken perpendicularly to the axial direction of the drill, the cross section of the body (2) has a crescent shape. When a hole is formed with the drill using an external oil supply method, a supply path for coolant liquid is defined between the outer peripheral surface of the small-diameter portion (2b) and the radially inner surface of the hole.