Thin-Walled Tube Machining for Leak-Free Labyrinth Joints
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Solution Overview
Problem
Non-rigid thin-walled tubular elements with geometric deficiencies, such as ellipticity, skewing, and non-uniform wall thickness, pose challenges in machining and assembly, leading to potential gas leaks and weak joints, which can prevent them from being used effectively as rocket motor cartridges.
Innovation Solution
A method involving heat-treating and machining using a conformal lathe steady-rest with rollers to achieve precise cylindricity and uniformity, followed by forming labyrinth-joints with circular planar closure elements to ensure leak-free assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polymeric materials are used to make beakers, then weight is reduced, but manufacturing precision deteriorates due to distortions from extrusion and internal stresses
Solution Approach 1:
The patent applies preliminary action by performing heat treatment and machining operations before the beaker is fully assembled and sealed. The heat treatment process is applied to the extruded polymeric tube to relieve internal stresses and reduce distortions before machining operations. This preliminary treatment allows the polymeric material to achieve better geometric stability, enabling precision machining of sealing surfaces and geometric features while maintaining the weight advantages of polymeric materials.
2Ease of manufacture
If geometric deficiencies are present in tubular elements, then ease of manufacture is improved, but reliability deteriorates due to gas leaks and weak joints
Solution Approach 1:
The patent converts the harmful effect of geometric deficiencies into a benefit by using the heat treatment process to intentionally induce controlled distortions that can then be precisely corrected through machining. The heat treatment causes predictable distortions in the polymeric tube, which are then compensated for during the machining of sealing surfaces. This approach allows the manufacturing process to account for and correct geometric deficiencies, transforming what would be harmful irregularities into opportunities for achieving precise, leak-free joints through controlled machining operations.
3Manufacturing precision
If precision machining is applied to correct geometric deficiencies, then manufacturing precision is improved, but device complexity increases due to specialized equipment requirements
Solution Approach 1:
The patent introduces an intermediary substance, specifically a support wax or similar sacrificial material, that is placed inside the polymeric tube during machining operations. This intermediary provides internal support to the thin-walled tubular element, preventing distortion and vibration during precision machining. The support wax acts as a mediator between the machining tool and the workpiece, enabling high-precision machining of sealing surfaces and geometric features without requiring overly complex specialized equipment. After machining, the intermediary material is removed, leaving the precisely machined polymeric beaker.
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 method corrects geometric deficiencies, enabling the creation of leak-free, reliable, and hot-gas-resistant rocket motor cartridges that can be interchangeably assembled and used with precision, ensuring proper fit and performance.
Implementation Method 1
heat-treating and machining using a conformal lathe steady-rest
Data Source
AI summary
A method for correcting non-rigid thin-walled tubular elements having geometric deficiencies, wherein, following correction, the tubular elements may perform over a wide range of pressure and temperatures, for example as a rocket motor beaker, from about −70 C to about 1000 C. Correction is required to remove asperities, maximize cylindricity, squaring a forward end wall and a rearward end wall, so that the forward end wall of the tube product may be fitted, bonded and sealed to a circular planar element using a labyrinth-joint closure. The method provides uniformity so that both the tubular elements and the circular planar elements are interchangeably uniform in size, shape and performance, and may be readily assembled into non-rigid thin-walled tube products.