Core Drill Bit Segment Attachment via Capacitive Discharge Welding
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Solution Overview
Problem
Existing diamond core drill bits face issues with time-consuming and costly attachment of cutting segments, often resulting in inadequate adhesion and requiring significant cleaning efforts, which affects the tool's performance and longevity.
Innovation Solution
The use of capacitive discharge welding to securely mount cutting segments onto a cylindrical body with a non-planar annular surface, creating a strong and secure bond between the segments and the body, allowing for varied segment compositions without compromising bond integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If infiltration process is used to attach cutting segments, then segments can be mounted on the bit body, but the process is time-consuming and costly
Solution Approach 1:
The patent replaces the traditional infiltration process with electrical discharge welding (EDW), substituting a thermal-chemical process with an electrical field-based process. The EDW process uses controlled electrical discharges to melt and fuse the cutting segments to the bit body, eliminating the need for infiltration materials and extensive cleaning operations, thereby significantly reducing manufacturing time and cost.
Solution Approach 2:
The patent changes the attachment process parameters by using electrical discharge welding with specific voltage, current, and pulse duration parameters. The process uses high-voltage electrical discharges (typically 50-100 volts) with controlled current (10-50 amperes) in pulsed mode, creating localized melting and fusion that rapidly attaches segments without the time-consuming infiltration and cleaning steps.
2Reliability
If infiltration process is used to attach cutting segments, then segments can be mounted on the bit body, but adhesion is inadequate
Solution Approach 1:
The patent replaces the infiltration process with electrical discharge welding, which creates a metallurgical bond between the cutting segments and the bit body. This electrical field-based process produces superior adhesion through direct fusion, eliminating the weak mechanical interlocking and chemical bonding characteristics of infiltration methods.
Solution Approach 2:
The patent creates a composite structure where the cutting segments (containing diamond particles in a metal matrix) are metallurgically bonded to the bit body material. The electrical discharge welding process produces a fusion zone that combines the segment material with the body material, creating a strong, reliable bond that maintains the integrity of both materials while achieving superior adhesion.
3Ease of manufacture
If infiltration process is used to attach cutting segments, then segments can be mounted on the bit body, but cleaning is required due to stray material
Solution Approach 1:
The patent replaces the infiltration process with electrical discharge welding, which is a contactless process that uses electrical fields to create localized melting and fusion. This substitution eliminates the generation of stray infiltration material that would require cleaning, as the EDW process precisely confines the welding zone to the interface between the segment and bit body without producing excess material.
Solution Approach 2:
The patent converts the potential harm of high-energy electrical discharges (which could create debris or damage surrounding areas) into a beneficial localized process. The electrical discharge is precisely controlled to melt only the contact surfaces, and the rapid cooling that follows solidifies the material in place, transforming what could be a source of contamination into a clean, precise joining process.
4Ease of manufacture
If infiltration process is used to attach cutting segments, then segments can be mounted on the bit body, but energy consumption is high
Solution Approach 1:
The patent replaces the infiltration process with electrical discharge welding, which uses electrical energy more efficiently. The EDW process concentrates energy precisely at the welding interface through controlled electrical discharges, avoiding the widespread thermal energy distribution and material heating characteristic of infiltration processes. This localized energy delivery reduces overall energy consumption while achieving reliable attachment.
Solution Approach 2:
The patent uses pulsed electrical discharge with periodic on-off cycles during the welding process. The electrical energy is delivered in controlled pulses (typically microsecond to millisecond duration) rather than continuous heating, allowing for precise energy dosing. This periodic action enables the process to achieve the required bond strength with lower total energy input compared to the continuous thermal process of infiltration.
Data Source
AI summary
A core drill bit includes an elongate hollow cylindrical body having opposite first and second ends with an end section having an end face defining an annular non-planar surface. The cutting head includes a plurality of circumferentially spaced apart cutting segments, the cutting segments being electrical welded to the non-planar surface whereby raised portions of the surface melt during the welding to affix the cutting segments with the face of the tool body.