Single-Lip Gun Drill Layout for Larger Coolant Channels

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Solution Overview

Problem

Single-lip drills with small diameters face challenges in providing an efficient supply of cooling lubricant due to limited space, leading to reduced drilling depth, increased flow resistance, and potential tool breakage from chip sticking, while also being costly and prone to production errors.

Innovation Solution

The design features a drill head with recesses for guide strips that have non-rectangular cross sections, allowing for a larger diameter cooling lubricant channel, reducing notch effects, and optimizing the placement of the cooling lubricant channel to increase volume flow and stability, thereby enhancing cooling and lubrication of the cutting edge and guide strips.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If two parallel coolant channels with small diameter are provided in the drill head, then the coolant flow cross-section is increased, but the manufacturing cost increases and the drilling process becomes slower and more error-prone

Engineering Contradiction:
Improvecoolant flow cross-sectionVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The drill head cross-section is divided into functional zones: two recesses for guide strips positioned at opposite sides, and a central coolant channel. This segmentation allows the coolant channel to be positioned optimally in the center, maximizing its diameter while the recesses are arranged peripherally to avoid interfering with the channel.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The recesses are designed with non-rectangular cross-sections (specifically, rounded or curved shapes) rather than simple rectangular forms. This dimensional optimization reduces the space occupied by each recess, thereby increasing the available space for the central coolant channel and allowing for a larger channel diameter.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the coolant channel diameter is increased, then the coolant supply efficiency is improved, but the space for recesses and the remaining tool body stability is reduced

Engineering Contradiction:
Improvecoolant supply efficiencyVSAvoidtool body stability
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The recesses are positioned asymmetrically at opposite sides of the drill head, flanking the central coolant channel. This asymmetric arrangement allows the coolant channel to occupy the central position with maximum possible diameter, while the recesses are pushed to the periphery, minimizing their interference with the channel size.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The recesses are designed with curved or rounded cross-sections rather than sharp rectangular corners. This curvature reduces the notch effect at the recess boundaries, distributing stress more evenly and maintaining tool body stability even with a larger central coolant channel.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If recesses with rectangular cross-section are used, then the positioning of guide strips is simplified, but the space for coolant channel is reduced

Engineering Contradiction:
Improveguide strip positioningVSAvoidcoolant channel volume
Core Design Contradiction:
Ease of operationVSVolume of stationary object

Solution Approach 1:

The recesses are designed with rounded or curved cross-sections instead of rectangular shapes. This curvature optimizes the space utilization within the drill head, allowing larger coolant channel diameter while the recesses occupy less peripheral space. The curved surfaces also reduce stress concentration.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Manufacturing precision

If smaller drill diameter is used, then the drilling precision for small bores is improved, but the space for coolant channel and groove is reduced

Engineering Contradiction:
Improvesmall bore drilling precisionVSAvoidcoolant channel and groove space
Core Design Contradiction:
Manufacturing precisionVSVolume of stationary object

Solution Approach 1:

The drill head is segmented into distinct functional regions: central coolant channel and peripheral recesses. This segmentation allows the coolant channel to be positioned centrally with maximum possible diameter, while recesses are pushed to the edges, optimizing space utilization in small-diameter drills.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The recesses are designed with non-rectangular, curved cross-sections that more efficiently utilize the available peripheral space. This dimensional optimization reduces the space consumed by recesses, thereby maximizing the coolant channel diameter within the constraints of small drill overall diameter.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 solution increases the drilling depth, improves chip removal, extends tool life, and enhances process reliability, making it suitable for small diameters and reducing production costs by simplifying the manufacturing process.

Implementation Method 1

Pressurized coolant is conveyed through this channel from the chuck end to the tip of the single-flute drill

Methodology Applied
Scientific EffectFluid flow through pressurized channel: Pressure Gradient

Implementation Method 2

It cools the drill cutting edge and lubricates the guide lips

Methodology Applied
Scientific EffectThermal cooling: Cooling

Implementation Method 3

It cools the drill cutting edge and lubricates the guide lips

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 4

As it does so, the coolant carries the chips produced by the cutting edge out of the bore

Methodology Applied
Scientific EffectChip removal through fluid flow: Entrainment

Data Source

PatentEP4417348A1Single lip gun drill with interchangeable guide pads
Publication Date: 2024.08.21 BOTEK PRAEZISIONSBOHRTECHNIK GMBH
  • EP4417348A1 patent drawingFigure 1
  • EP4417348A1 patent drawingFigure 2
  • EP4417348A1 patent drawingFigure 3

AI summary

A single-lip drill is presented, which has replaceable guide strips 27 and is particularly suitable for producing small bores. Compared to conventional single-lip drills, it has a coolant channel 43 with an increased diameter.