Perforated Metal Fibre Sensor Tubes With Post-Weld Waveguide Insertion
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Solution Overview
Problem
Existing methods for producing optical fibre waveguide sensors with metal casings face challenges such as fibre damage during hole drilling, limitations in minimum diameter production, and issues with weld quality and material flow, leading to mechanical damage and increased weight.
Innovation Solution
A continuous method for producing perforated metal hollow profiles with fibre waveguides involves trimming and forming a metal strip into a desired shape, using laser welding to create a smooth weld seam, and subsequent drilling to introduce holes without deforming existing perforations, allowing for smaller diameters and improved mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holes are introduced into the metal shell before the fibre waveguide is introduced, then the fibre waveguide is protected from damage during drilling, but the production process becomes more complex and time-consuming
Solution Approach 1:
A protective tube is introduced as an intermediary element that guides the fibre waveguide through the drilling process. The protective tube shields the fibre from direct exposure to the drilling operation, preventing damage while allowing the drilling to proceed efficiently. This mediator resolves the contradiction by providing physical protection without requiring a complex multi-step production process.
Solution Approach 2:
The metal shell is pre-perforated with holes before the fibre waveguide is installed. This preliminary action eliminates the risk of fibre damage during drilling, as the holes already exist when the fibre is placed in the shell. The fibre waveguide is then guided through the existing holes using a simple protective tube, avoiding the need for complex protective mechanisms during the drilling process itself.
2Ease of manufacture
If arc welding methods are used to weld the metal strip, then the welding process is well-established, but wall thicknesses smaller than 0.15 mm cannot be welded reliably and pronounced weld beads project into the tube interior
Solution Approach 1:
Arc welding is replaced with laser welding technology. This substitution enables precise control of the welding process, allowing reliable welding of thin walls (smaller than 0.15 mm) and producing smooth weld seams without pronounced beads projecting into the tube interior. The laser welding process provides the necessary precision while maintaining ease of manufacture through automated control.
Solution Approach 2:
The welding parameters are fundamentally changed by transitioning from arc welding to laser welding. This parameter change includes using concentrated laser energy instead of arc discharge, controlling heat input precisely, and achieving lower weld bead profiles. These parameter changes enable welding of thinner materials with higher precision while eliminating the harmful weld bead projections.
3Weight of moving object
If the tube diameter is reduced below 4.0 mm, then smaller and lighter sensors can be produced, but the minimum diameter limitation prevents further size reduction
Solution Approach 1:
Arc welding is replaced with laser welding, which provides the precision and control necessary for producing reliable welds in tubes with diameters below 4.0 mm. This substitution removes the minimum diameter limitation, enabling the production of smaller, lighter sensors while maintaining welding quality and structural integrity.
Solution Approach 2:
The welding process parameters are changed to enable operation at smaller diameters. Laser welding allows for precise control of heat input and weld geometry, making it possible to produce reliable welds in tubes with diameters below the previous 4.0 mm minimum. This parameter change directly enables reduced sensor size and weight.
4Length of moving object
If drawing processes are used to reduce tube diameter, then smaller diameters can be achieved, but compressive stress causes plastic material flow that closes the perforations
Solution Approach 1:
The holes are pre-introduced into the metal shell before the tube diameter reduction process. By establishing the perforations in advance, the subsequent drawing or reduction process does not subject the holes to compressive stresses that would cause plastic material flow and closure. The holes already exist in the final configuration, eliminating the geometry distortion problem.
Solution Approach 2:
The conventional sequence of operations is inverted: instead of reducing the tube diameter first and then drilling holes, the holes are drilled first and then the diameter reduction is performed. This inversion prevents the compressive stresses of the reduction process from affecting the hole geometry, as the holes are already in their final positions and configurations.
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 method enables the production of high-quality, lightweight optical fibre waveguide sensors with smaller diameters and improved mechanical stability, reducing fibre damage and material waste while maintaining precise control over the welding and drilling processes.
Implementation Method 1
the edges lying flush against one another are welded to one another by means of a laser welding device (8)
Implementation Method 2
a drilling device (27), by means of which the metal hollow profile is perforated
Data Source
AI summary
A method for the continuous production of a thin-walled, perforated metal hollow profile with one or more fibre waveguides mounted therein. The method includes supplying of a flat metal strip at a first supply rate to a deforming device, which continuously deforms the metal strip into a metal hollow profile with a slot running in a longitudinal direction. Two opposite edges of the metal strip deformed into the metal hollow profile that lie flush against one another in a contact region extending in the longitudinal direction of the metal hollow profile are continuously welded to one another, drawn off from the welding region and perforated. The method further includes positioning a protective tube reaching into the welded metal hollow profile on the draw-off side to beyond the perforation point and supplying one or more fibre waveguides from one or more fibre unwinders via the protective tube, such that the fibre waveguide or waveguides are introduced into the perforated metal hollow profile from the guide or protective tube downstream of the perforation point in the drawing-off direction. The perforated metal hollow profile with the fibre waveguide or fibre waveguides mounted therein is received in a receiving unit.