Core Bit Cutting Section With Split Tube Load Paths

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Solution Overview

Problem

The existing methods for manufacturing cutting sections for drill bits, such as the 'Hilti DD X-CM', face high production costs due to turning and milling processes, and are limited in material selection, compromising power transmission, torque transmission, and tensile loads when removing a jammed drill bit.

Innovation Solution

The method involves producing a cutting section with a closed tubular element formed from two sheet metal parts, where power transmission is handled by one tubular element and torque transmission by another, allowing for separate material selection and reducing manufacturing complexity by eliminating the need for turning and milling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cutting sections are manufactured from a closed tube element using turning and milling processes, then power transmission and torque transmission are achieved, but manufacturing costs increase and material selection is limited

Engineering Contradiction:
Improvepower transmissionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The cutting section is divided into multiple separate sheet metal parts (first sheet metal part, second sheet metal part, third sheet metal part) that are formed and joined together to create a modular structure. This segmentation allows each part to be manufactured independently using cost-effective sheet metal forming processes rather than expensive turning and milling of a single closed tube, while still achieving the required power and torque transmission functions through the assembled structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses multiple sheet metal parts that can be made from different materials optimized for their specific functions. The first sheet metal part can be optimized for power transmission, the second for torque transmission, and the third for tensile load resistance, allowing composite construction that exceeds the performance of a single-material closed tube while reducing overall manufacturing cost.

Inventive Principle:
Principle #40Composite materials

2Strength

If cutting sections are manufactured from a closed tube element, then structural integrity is maintained, but material selection is compromised for tensile loads when removing a jammed drill bit

Engineering Contradiction:
Improvestructural integrityVSAvoidmaterial selection
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

Each sheet metal part is designed with specific material properties tailored to its local function: the first sheet metal part uses materials optimized for power transmission, the second for torque transmission, and the third for withstanding tensile loads during jammed drill bit removal. This local optimization of material quality in different parts achieves superior overall performance compared to using a single material for the entire closed tube structure.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If turning and milling processes are used to produce annular stop shoulder and slotted recesses, then functional features are created, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvefunctional featuresVSAvoidmanufacturing process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts the complex turning and milling operations from the manufacturing process by forming the annular stop shoulder and slotted recesses directly into sheet metal parts using forming techniques. The annular stop shoulder is formed on the first sheet metal part and the slotted recesses are formed on the second sheet metal part during the forming process itself, eliminating the need for subsequent expensive and complex turning and milling operations while maintaining the required functional precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3727730B1Method for producing a cutting section for a core bit
Publication Date: 2021.11.17 HILTI AG
  • EP3727730B1 patent drawingFigure 1A
  • EP3727730B1 patent drawingFigure 1B
  • EP3727730B1 patent drawingFigure 2A

AI summary

The invention relates to a method for producing a cut section from a closed tubular element (14) which is designed as a hollow cylinder, and one or more drilling segments (16) which are joined to the close tubular element (14).