Interlocking Pie-Cut Tubing for Precise Exhaust Elbow Alignment
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Solution Overview
Problem
Current methods for fabricating tubular elbows with tight-radius bends face challenges in repeatability and tolerance issues due to imperfect alignment of pie-cut sections, which are often joined visually and lack precise fixtures, leading to gaps and manufacturing inconsistencies.
Innovation Solution
The use of keyed and faceted profile features on the interface of angular cut tubular profiles, where evenly spaced keys on one pie cut engage with evenly spaced facets on another, ensuring precise alignment and connection through welding or tacking, with reference lines for consistent orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pie-cut sections are joined visually without precise fixtures, then the manufacturing process is simple and quick, but alignment precision and repeatability deteriorate
Solution Approach 1:
The pie-cut sections incorporate self-aligning features (keys and facets) that automatically guide proper alignment during joining, eliminating the need for external fixtures or visual alignment by operators. The geometry of the keys and facets ensures that when engaged, they inherently position the sections correctly, making the joining process both simple and precise.
Solution Approach 2:
The keyed interface acts as an intermediary mechanism between pie-cut sections. Rather than directly joining smooth surfaces which require precise visual alignment, the keys and facets serve as mediating elements that enforce proper positioning, transferring alignment accuracy from the keyed interface to the overall joint.
2Device complexity
If pie-cut sections are aligned visually, then no additional alignment features are needed, but repeatability and tolerance control worsen
Solution Approach 1:
The alignment features are self-contained within the pie-cut sections themselves. The keys and facets are integral parts of the tube sections, providing automatic alignment without requiring external fixtures, jigs, or complex alignment procedures. This self-service approach ensures consistent repeatability across multiple joining operations.
Solution Approach 2:
The keys and facets are pre-formed during the pie-cut manufacturing process, before the actual joining operation. This preliminary creation of alignment features ensures that when joining occurs, the alignment geometry is already established, eliminating variability in the alignment process and improving repeatability.
3Adaptability or versatility
If base stock pie cuts are not perfectly round, then material variability exists, but alignment precision deteriorates due to gaps
Solution Approach 1:
The alignment features (keys and facets) are localized at the joining interface of each pie-cut section. Even if the overall tube section has slight non-circularity or dimensional variations, the local geometry of the keys and facets maintains precise engagement, ensuring proper alignment at the critical joining location regardless of global material variability.
Solution Approach 2:
The keyed interface design anticipates and compensates for material variability and manufacturing tolerances. The geometry of the keys and facets is designed to accommodate slight variations in tube roundness and dimensions, providing a cushioning effect that maintains alignment precision despite base stock imperfections.
Data Source
AI summary
A tube arrangement as described herein can include a first and a second wedge shaped circular tube, or pie cut, that are each defined by a front face and a back face, a minimum face-to-face distance between the front face and the back face that is smaller than a maximum face-to-face distance between the front face and the back face. A plurality of evenly spaced keys is dispersed along the front face of the first pie cut. The keys are engaged with a plurality of evenly spaced facets dispersed along the back face of the second pie cut. A weld seals a joint located between the front face of the first pie cut to the back face of the second pie cut. This arrangement is beneficial for constructing custom shaped exhaust tubes by welding the offset pie cuts as needed.