Rotating Cone Drill Bit Thermal Assembly With Localized Leg Bore Heating
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Solution Overview
Problem
The thermal assembly of leg-cone assemblies in rotating cone drill bits poses a challenge due to the close proximity of heat-sensitive components like grease and seals to the heated drill bit body, leading to potential damage during the high-temperature fitting process.
Innovation Solution
The method involves localized leg bore heating using an induction heating coil, temporary installation of insulative cords in pressure equalization grooves, application of thermal gaskets or heat-blocking pastes, use of heat sinks, pre-chilling assemblies, and circulation of fluids to mitigate heat transfer, and forming pockets for thermal symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal assembly is used to assemble leg-cone assemblies into the drill bit body, then assembly strength and fit precision are improved, but the seals and grease within the leg-cone assemblies are damaged due to excessive heat exposure
Solution Approach 1:
The heating process is segmented into localized zones using induction heating coils positioned at specific locations around the drill bit body, allowing only the leg bore regions to be heated to assembly temperature while keeping other areas including the leg-cone assemblies at lower temperatures
Solution Approach 2:
The drill bit body is pre-heated to the required assembly temperature (800°F to 900°F) before the leg-cone assemblies are inserted, so that the thermal differential is established in advance and the assemblies experience minimal heat exposure during the actual fitting process
Solution Approach 3:
Heat-resistant coatings or insulating materials are applied as intermediary layers between the heated drill bit body and the heat-sensitive seals and grease within the leg-cone assemblies, protecting these components from thermal damage while allowing the metal-to-metal interface to achieve proper fit
2Device complexity
If the entire drill bit body is heated uniformly for thermal assembly, then assembly process simplicity is maintained, but thermal symmetry of leg bores is compromised leading to misalignment
Solution Approach 1:
Different thermal conditions are applied to different regions of the drill bit body - localized induction heating coils heat only the specific leg bore areas to the required temperature, creating non-uniform temperature distribution that ensures thermal symmetry of individual leg bores without requiring uniform heating of the entire body
Solution Approach 2:
The heating approach transitions from uniform three-dimensional heating of the entire body to targeted one-dimensional localized heating at each leg bore position, achieving better thermal symmetry by addressing each bore independently
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 approach effectively reduces the adverse thermal effects on seals and grease, ensuring the integrity and longevity of the leg-cone assemblies during assembly.
Implementation Method 1
localized leg bore heating using an induction heating coil
Implementation Method 2
temporarily installing an insulative cord in the pressure equalization groove of the leg body to provide a heat barrier
Implementation Method 3
installing a heat sink on the body pin end or about all or a portion of the body
Implementation Method 4
providing circulation through the mud paths for heat removal
Data Source
AI summary
A method of thermal assembly of multiple leg-cone assemblies within multiple respective distally-opening leg bores of a drill bit body of a rotating cone drill bit, each leg-cone assembly having a leg body with a proximal leg shank for selective receipt within the respective leg bore, the method including the steps of (a) forming a pocket in the drill bit body symmetrically about the leg bores, (b) heating a single leg bore, (c) inserting the leg shank of the leg-cone assembly into the heated leg bore, (d) cooling the drill bit, and (e) repeating steps (b)-(d) in separately assembling each leg-cone assembly within the respective leg bore, thereby mitigating against adverse thermal effects on seals or grease within the leg-cone assemblies.