Brazed Tube Joint Assembly With Helical Protrusions for Centering
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Solution Overview
Problem
Conventional joining techniques face challenges in centering and retaining tube members, particularly in thin-walled structures, where knurling can lead to localized thinning and thickening issues and requires careful parameter control, and radiographic inspection may be necessary to ensure joint coverage.
Innovation Solution
A tube joint design featuring a second member with helical protrusions and bottom land surfaces that define a larger outer diameter, allowing for centering and retention within a first member's bore, using braze alloy, solder, or welding to create a secure joint without the need for knurling, with the helical protrusions and land surfaces facilitating the flow and solidification of braze or solder for a reliable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If knurling is used to center and retain tube members, then joining is accomplished, but localized thinning and thickening occurs particularly on thin-walled structures
Solution Approach 1:
The patent applies local quality by creating localized deformations in the form of helical protrusions and bottom land surfaces on specific portions of the tube member outer surface. These localized features provide centering and retention functions without requiring global knurling of the entire tube surface, thereby avoiding widespread wall thickness variations while achieving the necessary mechanical interlocking for reliable joint formation.
Solution Approach 2:
The patent segments the continuous knurling pattern into discrete helical protrusions separated by bottom land surfaces. This segmentation allows the centering and retention features to be distributed around the tube circumference in a controlled manner, preventing the localized thinning and thickening problems associated with conventional continuous knurling while maintaining effective mechanical interlocking.
2Manufacturing precision
If knurling parameters are controlled to limit localized thinning and thickening, then wall thickness is preserved, but radiographic inspection becomes necessary to ensure joint coverage
Solution Approach 1:
The patent applies self-service by designing the helical protrusions and bottom land surfaces to inherently provide visible and measurable centering features that eliminate the need for additional radiographic inspection. The geometric features create observable gaps and contact points that allow operators to verify proper centering and joint coverage through simple visual or dimensional inspection methods, making the system self-verifying without requiring complex inspection equipment.
3Reliability
If helical protrusions with larger outer diameter are used, then centering and retention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies curvature by forming helical (curved) protrusions instead of straight radial features. The helical geometry provides smooth transitions and continuous contact surfaces that improve centering performance while being amenable to standard forming processes such as roller forming or extrusion. The curved helical paths distribute manufacturing stresses more evenly compared to sharp angular features, making the features easier to produce with conventional tube forming equipment.
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 design enhances the reliability of tube joints by eliminating the need for knurling, reducing the risk of braze voids and potentially eliminating the need for radiographic inspection, while ensuring consistent and secure fixation of the second member within the first member.
Implementation Method 1
brazing typically involve flowing solder or braze between adjacent surfaces of the parts which, once solidified, forms a joint between the parts
Implementation Method 2
flowing solder or braze between adjacent surfaces
Implementation Method 3
the thickened portions channelizing the solder or braze through the thinned sections to form the joint once solidified
Data Source
Figure 1
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AI summary
A tube joint (100) includes a first member (104) and a second member (102). The first member (104) has a bore defining an inner diameter (118). The second member (102) has a first outer surface defining a first outer diameter with two or more helical protrusions (132) extending radially from the first outer diameter. The two or more helical protrusions collectively define a second outer diameter. The second outer diameter of the second member is larger than the inner diameter of the first member (104) by an amount sufficient to center and retain the second member (102) within the bore of the first member. Brazed tube joint assemblies and methods of making brazed tube joints (100) are also described.