Two-Piece Drill Bit Bonded Interface for Stronger Tip-Shaft Joining

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Solution Overview

Problem

Existing two-piece drill bits face challenges in achieving a strong and reliable bond between the tip segment and the shaft, particularly due to misalignment and varying material properties, which can lead to weld or braze failures.

Innovation Solution

The drill bit design incorporates an interface feature with protrusions and/or recesses between the tip segment and the shaft, along with an intermediary inner layer made of materials like copper-nickel alloy or metal mesh, to increase the bonding surface area and enhance the joining process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional two-piece drill bit design is used with direct welding or brazing between tip segment and shaft, then the manufacturing process is simple, but the bond strength is insufficient and weld failures occur due to misalignment and varying material properties

Engineering Contradiction:

Improvebond strengthVSAvoidinterface structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The interface between tip segment and shaft is segmented into multiple bonding zones through protrusions and recesses, creating distributed bond locations that reduce stress concentration and improve overall bond strength despite the increased interface complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bonding interface is extended from a simple planar surface to a three-dimensional structure with protrusions and recesses, increasing the effective bonding surface area and creating multiple bonding planes that enhance bond strength while accommodating misalignment

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If direct welding or brazing is performed between tip segment and shaft, then the joining process is fast, but misalignment between components causes weld or braze failures

Engineering Contradiction:

Improveweld reliabilityVSAvoidalignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Protrusions and recesses are designed into the interface beforehand to accommodate and cushion misalignment between tip segment and shaft, preventing weld failures by providing built-in alignment tolerance before the welding or brazing process occurs

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The protrusion-recess interface features act as intermediaries that facilitate alignment between the tip segment and shaft, mediating the connection and enabling reliable welding or brazing even when perfect alignment is not achieved

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If different materials are used for tip segment and shaft, then the drill bit performance is optimized for specific applications, but varying material properties make bonding difficult and prone to failure

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidbond strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The interface features are designed with specific local geometries (protrusions and recesses) that create favorable bonding conditions at the interface between different materials, allowing each material to contribute its optimal properties while achieving strong bonding despite material property differences

Inventive Principle:

Principle #3Local quality

4Strength

If the bonding surface area between tip segment and shaft is increased, then bond strength improves, but the manufacturing complexity and processing time increase

Engineering Contradiction:

Improvebond strengthVSAvoidmanufacturing ease

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The increased bonding surface area is achieved through segmentation into discrete protrusions and recesses rather than a continuous complex surface, making the manufacturing process more manageable while still achieving the desired bond strength through distributed bonding zones

Inventive Principle:

Principle #1Segmentation

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 creates a stronger bond between the tip segment and the shaft, reduces the risk of weld or braze failures, and allows for the use of thicker tip segments, while also reducing misalignment issues and lowering the melting point required for joining.

Implementation Method 1

heating the tip segment, the shaft, and the inner layer to a specific temperature to join the tip segment, the shaft, and the inner layer together

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS20250187084A1Two-Piece Drill Bit with Bonded Interface

Publication Date: 2025.06.12 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A drill bit is provided having a tip segment, a shaft, and an interface feature. The tip segment includes a cutting end, an attachment end, and a body. The attachment end defines an attachment surface facing in a direction away from the cutting end. A cross-sectional area perpendicular to the central axis is defined by an outer perimeter of the body. The shaft includes a first end coupled to the attachment end. The interface feature is located on the attachment surface and positioned between the attachment end and the first end. An outer surface of the interface feature and the attachment surface define an interface surface. The interface surface has a surface area greater than the cross-sectional area of the tip segment. In various embodiments, the interface feature includes at least one protrusion and/or at least one recess.