Sheet Metal Pipe Section With Folded Overlap Joint
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Solution Overview
Problem
The existing methods for producing sheet metal pipes, such as gutter pipes, face issues with surface coating damage during welding, leading to corrosion and increased production costs due to the need for post-processing to restore the coating, and the mechanical connections are difficult to automate and may not be liquid-tight or rigid enough.
Innovation Solution
A method involving forming a sheet metal pipe with overlapping longitudinal edge sections that are welded or glued, then bent to create a fold covering the joint area, ensuring the coated surface is protected, and using a modified stretch-bending device with a recessed mandrel to prevent deformation and wear, allowing for a tight, strong, and corrosion-resistant connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to join longitudinal edge sections of sheet metal pipe, then connection strength and tightness are improved, but the surface coating is destroyed by heat effects leading to corrosion risk
Solution Approach 1:
The patent introduces an intermediary protective layer (additional sheet metal strip or coating material) that is applied to the weld seam area before welding. This intermediary layer absorbs the heat damage and prevents direct contact between the welding heat and the original surface coating, thus preserving the corrosion protection while maintaining connection strength.
Solution Approach 2:
The patent applies protective measures (such as protective coatings or sacrificial layers) to the surface coating before the welding process begins. This preliminary protection ensures that even if heat damage occurs during welding, the original surface coating remains intact or can be easily restored, preventing corrosion.
2Object-affected harmful factors
If mechanical connection with hook or pocket shapes is used to join longitudinal edges, then surface coating is preserved, but automation difficulty increases and liquid-tightness and rigidity are insufficient
Solution Approach 1:
The patent combines mechanical connection elements (hooks or pockets) with welding or adhesive bonding in a hybrid joining method. The mechanical elements provide form-fitting connection and positioning, while the welding or adhesive provides strong, automated bonding that ensures liquid-tightness and rigidity, overcoming the limitations of purely mechanical connections.
Solution Approach 2:
The patent modifies the geometric parameters of the mechanical connection elements (such as hook angle, pocket depth, or overlap dimensions) to optimize both the ease of automated formation and the strength of the connection. By adjusting these parameters, the design achieves adequate liquid-tightness and rigidity while remaining compatible with automated production processes.
3Ease of manufacture
If large clearance is provided between mandrel and clamping piece for stretch bending, then weld flash and folds can be accommodated, but sheet metal deforms in a wavy manner and tool wear increases
Solution Approach 1:
The patent applies local quality by providing clearance only in specific areas where weld flash and folds are expected, while maintaining tight clearance in other areas to prevent unwanted deformation. This localized approach allows the bending process to accommodate connection irregularities without causing wave-like deformation across the entire pipe surface, and reduces overall tool wear.
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 provides a reliable, tight, and mechanically strong connection that preserves the surface coating, preventing corrosion and reducing production costs while allowing for efficient automation and minimizing tool wear.
Implementation Method 1
A welded or glued joint is provided in the overlapping area
Implementation Method 2
A welded or glued joint is provided in the overlapping area
Implementation Method 3
the overlapping area is bent over in the manner of a fold
Data Source
Figure 1a~1f
Figure 1d~1g
Figure 2a~2d
AI summary
The present invention relates to a pipe section (1) made of sheet metal and a method for its manufacture, for use as a rain gutter pipe and as a starting material for the manufacture of rain gutter downpipe bends. The pipe section is formed from a flat sheet metal blank with a surface coating into a closed hollow cylindrical shape. Opposite longitudinal edge sections (2, 3) of the sheet metal blank, bent relative to the main surface, overlap each other in the longitudinal direction. A welded or adhesive bond (4) is provided in the overlap area (5), and the overlap area is folded over (6) such that at least the portion of the overlap area containing the welded or adhesive bond is covered by at least one layer (7, 8) of the sheet metal blank on both the outside and inside of the hollow cylindrical shape.The invention also proposes a stretch-bending device for producing a pipe bend from such a pipe section, as well as a method for producing a pipe bend from such a pipe section using this stretch-bending device.