Gun Drill Body Structure With Bent Discharge Groove for Accuracy

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Solution Overview

Problem

Gun drills experience bending during machining due to uneven force distribution, leading to reduced machining accuracy as the central body attempts to displace in a direction that aligns with the formation of the coolant discharge groove, causing potential contact with the machined hole.

Innovation Solution

A gun drill body design featuring a partially bent coolant discharge groove that diverges from the bending direction of the cross-sectional secondary moment, with the groove oriented opposite to the rotating direction towards the base end side, and a guide pad positioned differently along the circumferential direction to counteract bending forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a linear discharging groove is formed on the body, then the structure is simple and easy to manufacture, but the body bends during machining due to bending moment causing reduced machining accuracy

Engineering Contradiction:
Improveease of manufactureVSAvoidmachining accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The discharging groove is designed with a bent configuration instead of a straight linear path. The groove bends in the circumferential direction at a specific position along the body, creating a curved layout that counteracts the bending moment applied to the body during machining, thereby suppressing body deformation and maintaining machining accuracy.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Manufacturing precision

If the discharging groove is bent to suppress body bending, then machining accuracy is improved, but the groove structure becomes more complex

Engineering Contradiction:
Improvemachining accuracyVSAvoidgroove structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The discharging groove is segmented into multiple sections: a first groove section extending from the leading end, a second groove section that bends in the circumferential direction, and a third groove section continuing to the base end. This segmentation allows the groove to follow a bent path that counteracts bending moment while maintaining manufacturability through standardized forming processes.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If guide pad is positioned at the same circumferential position as cutting edge, then the structure is simple, but bending moment causes body displacement and contact with machined hole

Engineering Contradiction:
Improvestructural simplicityVSAvoidmachining accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The guide pad is positioned at a different circumferential position than the cutting edge, creating an asymmetric configuration. This asymmetric placement, combined with the bent discharging groove, generates counteracting moments that balance the bending forces during machining, preventing body displacement and maintaining machining accuracy without requiring complex additional components.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP4272889A1Body for gun drill
Publication Date: 2023.11.08 TUNGALOY CORP
  • EP4272889A1 patent drawingFigure 1
  • EP4272889A1 patent drawingFigure 2
  • EP4272889A1 patent drawingFigure 3

AI summary

Provided is a body capable of suppressing the bending of the body during machining. A body includes: a first mounting part serving as a portion that is provided on a leading end side and has a cutting edge mounted thereon; and a second attachment part serving as a portion that is provided at a position different from a position of the first mounting part along a circumferential direction and has a guide pad attached thereto on the leading end side. One discharging groove that extends from the leading end side to a base end side and is used to guide and discharge a fluid to the base end side is formed on an outer peripheral surface of the body, and at least a part of the discharging groove is bent.