Drill Stem Sheath Threaded Liner Fixation
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Solution Overview
Problem
Existing solutions for securing communications cables within rotary drill pipes are prone to vibration and displacement, leading to premature rupture and are complex and expensive to maintain, especially when requiring axial tensile pre-stressing and compatibility with thin-walled tubular components.
Innovation Solution
A drill stem component with a tubular body featuring a sheath and liner system, where the sheath is threaded to securely hold the cable, allowing for axial retention without adhesives and enabling easy installation and removal, with self-locking thread profiles for tensile pre-stressing, and designed to fit a variety of existing tubular components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communications line is housed in drill pipe bore, then data transfer is enabled, but line vibrates and displaces causing premature rupture
Solution Approach 1:
The drill pipe is divided into functional zones: end zones with shoulders for cable fixation and intermediate portions with thinner walls. The communications line is segmented into portions housed in different zones, with end portions fixed in end zones and intermediate portions in the bore, reducing vibration and displacement hazards.
Solution Approach 2:
A communications line with protective sheath acts as an intermediary element between the drill pipe structure and the cable. The sheath houses the cable and provides mechanical protection, while the liner in the end zone provides additional support and fixation, mediating the interaction between moving and stationary components.
2Reliability
If holding devices are added to secure cabling elements, then cable retention is improved, but device complexity and cost increase
Solution Approach 1:
The end zones with shoulders serve multiple functions: they provide structural support for the drill pipe, enable cable fixation through the liner and sheath assembly, and allow for maintenance operations. This multi-functionality reduces the need for separate dedicated holding devices, simplifying the overall structure.
Solution Approach 2:
The sheath and liner assembly is designed to be self-retaining through the threading mechanism. The sheath threads onto the liner which is supported by the shoulder, creating a self-locking arrangement that maintains cable retention without requiring additional active holding devices or complex mechanisms.
3Reliability
If adhesive is used to retain liner, then liner retention is improved, but maintenance and removal become difficult
Solution Approach 1:
The chemical bonding method (adhesive) is replaced with a mechanical retention system. The liner is retained by the shoulder through direct mechanical contact and support, allowing the sheath to be threaded onto the liner and secured. This mechanical system enables easy installation and removal during maintenance without chemical bonds.
4Reliability
If sheath is fixed rigidly in end zone, then axial retention is improved, but integrity of end zone and adaptability to thin-walled components deteriorates
Solution Approach 1:
The drill pipe structure is differentiated into end zones with thicker walls and shoulders for rigid cable fixation, and intermediate portions with thinner walls. This local quality variation allows the end zones to provide strong axial retention while the intermediate portions maintain adaptability to thin-walled component requirements.
Solution Approach 2:
The sheath is nested within the liner which is in turn supported by the end zone structure. This nested arrangement allows the sheath to be securely fixed in the end zone while the liner and end zone structure can be designed to accommodate thin-walled intermediate portions, achieving both rigid fixation and adaptability.
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
The solution provides reliable and cost-effective cable retention, reducing the risk of rupture and facilitating maintenance, while maintaining mechanical integrity and compatibility with existing components under various drilling conditions.
Implementation Method 1
At least one first end portion of the sheath is provided with a first threading. The liner supports a second threading. The first and the second threadings are screwed together.
Implementation Method 2
self-locking thread profiles for tensile pre-stressing
Implementation Method 3
self-locking thread profiles for tensile pre-stressing
Data Source
Figure 1~2
Figure 3~16
Figure 4~5
AI summary
The invention concerns a component (100) for a drill stem comprising a tubular body (1) with at least one first end zone (2) and a second end zone (3). The component (100) comprises a sheath (4) for the passage of a cable extending inside the tubular body (1) between the first end (zone 2) and the second end zone (3). The component further comprises at least one liner (70) which lines at least a portion of the inside of the tubular body (1) in the first end zone (2). At least a first end portion (4a) of the sheath (4) is provided with a first threading (43). The liner (70) supports a second threading (80a). The first (43) and second (80a) threading are screwed together.