Composite-Reinforced Pressure Cylinder Neck for Weld Torque Loads
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Solution Overview
Problem
Existing pressure cylinders made of all-metal or thin-walled welded stainless steel with composite shells face issues with mechanical integrity under torque, particularly at the weld junctions, and existing composite designs do not effectively transfer axial loads, leading to potential weld damage.
Innovation Solution
A pressure cylinder design featuring a neck with tapered grooves and locking teeth on a flange, combined with a composite fiber reinforcement, ensures a hermetic seal and optimal load transfer, using a circular welded seam and phased fiber winding to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the neck is welded to the thin-walled vessel with a simple circular seam, then the manufacturing process is simple and the hermetic seal is achieved, but the weld is vulnerable to torque damage and mechanical destruction
Solution Approach 1:
The patent applies composite materials by combining metal (neck and vessel) with composite fibers (carbon, glass, or basalt) wrapped around the neck weld junction. This composite reinforcement protects the weld from torque damage while maintaining manufacturing simplicity. The fibers are impregnated with polymer matrix and wrapped in specific patterns to distribute and absorb torque loads, preventing weld destruction during operation.
Solution Approach 2:
The patent uses spiral and circumferential wrapping patterns of composite fibers around the cylindrical neck junction. The spiral wrapping angle (30-60 degrees) creates a geometric configuration that optimally distributes torque loads along the weld seam, while the circumferential wrapping provides additional reinforcement. This curved geometric arrangement enhances weld reliability without complicating the manufacturing process.
2Ease of manufacture
If composite fibers are placed only in the polymer matrix without longitudinal load transfer, then the manufacturing is simpler, but the mechanical properties are significantly reduced and axial loads are not effectively transferred
Solution Approach 1:
The patent employs spiral wrapping of composite fibers at specific angles (30-60 degrees) around the neck, creating a geometric configuration that enables effective axial load transfer. The spiral geometry converts axial forces into both tensile and shear components that the composite fibers can withstand, allowing the fibers to actively participate in load bearing rather than merely serving as a matrix filler.
Solution Approach 2:
The patent optimizes the wrapping angle parameter (30-60 degrees) to maximize the mechanical properties of the composite reinforcement. By adjusting this geometric parameter, the fiber bundle achieves optimal orientation for transferring axial loads while maintaining ease of manufacture. The nominal stress value and number of wrapping cycles are also controlled to ensure fibers work at optimal stress levels.
3Strength
If high stress is applied during fiber winding from the beginning, then the mechanical strength is maximized, but the weld seam of the neck may be damaged or destroyed
Solution Approach 1:
The patent implements a two-phase fiber winding process with periodic application of different stress levels. In the first phase, fibers are wrapped at low stress (below the threshold that would damage the weld) to establish the reinforcement structure. In the second phase, after the composite shell gains sufficient strength, fibers are wrapped at high nominal stress to maximize mechanical properties. This periodic stress application ensures both weld protection and optimal strength development.
Solution Approach 2:
The patent applies low-stress fiber wrapping beforehand to cushion and protect the weld seam during the manufacturing process. This initial low-stress reinforcement acts as a protective layer that prevents weld damage during subsequent high-stress operations. Only after this protective layer is in place and the structure is sufficiently strong does the process transition to high-stress wrapping for maximum strength.
4Ease of manufacture
If a circular groove is used for fiber placement, then the manufacturing is simpler, but torque transfer is not optimal and axial loads are not transferred effectively
Solution Approach 1:
The patent replaces simple circular grooves with spiral grooves that follow a helical path around the neck at specific angles (30-60 degrees). This spiral geometric configuration optimizes torque transfer by distributing loads along the spiral path, engaging both circumferential and axial components of the fiber reinforcement. The spiral groove geometry enables the composite fibers to effectively transfer torque while maintaining manufacturing feasibility through standardized machining processes.
Data Source
Figure 1~2a
Figure 2b~3a
Figure 3b~4a
AI summary
A pressure cylinder made of thin-walled welded stainless steel vessel (1) fitted with a composite shell and a neck (2) with an external and/or internal thread, where the neck (2) is attached to the thin-walled vessel (1) by a circular welded seam with a hermetic seal and containing a flange which is fitted circumferentially with a pair of tapered grooves (3) on its outer surface whose adjacent sides meet on an annular ridge on which there are locking teeth in the direction of the longitudinal axis of the neck (2) and composite fibers are placed in inter-tooth spaces (4, 5). The method of producing a pressure cylinder comprises the welding of a neck to the thin-walled vessel with a hermetic seal, whereupon composite fibers with stress less than the total force acting on the fiber bundle are wound into additional grooves between the teeth and further winding of the fiber around the neck is carried out while simultaneously moving bilaterally along the axis of the shell to position the fiber between the teeth, whereupon fibers with a nominal stress value are wound and final winding of the reinforced composite shell is carried out.