Core Bit Cutting Section With Plug-Turn Torque Transfer

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Solution Overview

Problem

The existing methods for producing cutting sections for drill bits, such as the 'Hilti DD X-CM', require high manufacturing effort due to turning and milling processes, and have limited material selection, which affects force and torque transmission, as well as tensile loads during drilling and jammed bit removal.

Innovation Solution

A method involving a cutting section composed of a first open tubular element and a second closed tubular element, connected via a releasable plug-and-turn connection, where the second element is formed from a sheet metal part and features slot-shaped recesses for torque transmission and a transverse groove for enhanced stability, allowing for separate material selection and reduced manufacturing effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If cutting sections are manufactured from a closed tubular element using turning and milling processes, then the annular stop shoulder and slot-shaped recesses can be produced, but the manufacturing effort and complexity increase significantly

Engineering Contradiction:
Improveproduction of annular stop shoulder and slot-shaped recessesVSAvoidmanufacturing effort
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The cutting section is divided into multiple separate components: a first tubular element, a second tubular element, and drilling segments. These components are manufactured separately and then assembled together, eliminating the need for complex turning and milling operations on a single closed tubular element. The segmentation allows each component to be produced using simpler manufacturing processes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of starting with a closed tubular element and removing material through turning and milling to create the annular stop shoulder and slot-shaped recesses, the invention inverts the approach by assembling open tubular elements and adding features through joining processes. This reverse methodology simplifies manufacturing by avoiding subtractive machining of complex geometries.

Inventive Principle:
Principle #13The other way round (Inversion)

2Strength

If cutting sections are manufactured from a closed tubular element, then structural integrity is maintained, but material selection is limited and compromises must be made regarding force transmission, torque transmission, and tensile loads

Engineering Contradiction:
Improveforce transmission, torque transmission, and tensile loadsVSAvoidmaterial selection
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The cutting section is segmented into multiple components that can be manufactured from different materials optimized for specific functions. The first tubular element can be selected for force transmission, the second tubular element for torque transmission, and drilling segments for cutting performance. This segmentation enables tailored material selection without compromising overall structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutting section employs a composite structure consisting of multiple tubular elements and drilling segments made from different materials. Each material is selected to optimize specific performance characteristics such as strength, toughness, or wear resistance. The composite construction allows the cutting section to simultaneously achieve high force transmission, torque transmission, and tensile load capacity through appropriate material pairing.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If a single closed tubular element is used for the cutting section, then manufacturing is simplified, but the ability to handle tensile loads during jammed bit removal is compromised

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidtensile loads during jammed bit removal
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The cutting section is segmented into a first tubular element and a second tubular element connected by a connection element. This segmentation creates a dedicated load path for tensile forces during jammed bit removal, with the connection element specifically designed to handle these loads. The segmented structure maintains manufacturing simplicity while significantly improving tensile load capacity.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If detachable connection devices are used for plug-and-rotate connection, then the cutting section can be released from the drill shaft, but the connection complexity increases

Engineering Contradiction:
Improverelease of jammed bitsVSAvoidconnection device structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The connection device incorporates dynamic features including a spring element that enables automatic engagement and disengagement. The spring-loaded mechanism allows the cutting section to be easily released from the drill shaft by overcoming the spring force, providing a simple operational interface despite the internal mechanical complexity. This dynamic design facilitates quick release of jammed bits while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3727729B1Method for producing a cutting section for a core bit
Publication Date: 2024.07.31 HILTI AG
  • EP3727729B1 patent drawingFigure 1A
  • EP3727729B1 patent drawingFigure 1B
  • EP3727729B1 patent drawingFigure 2A

AI summary

The invention relates to a method for producing a cutting section consisting of a first, open tube element (14) embodied as a first hollow cylinder, a second, closed tube element (15) embodied as a second hollow cylinder, and at least one boring segment (16) which is connected to the first, open tube element (14) and the second, closed tube element (15).