ERW Metal Tube Edge Profile to Prevent Bend Cracking
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Solution Overview
Problem
Electric resistance welded pipes experience cracking during severe processing like 90° bending due to the decreased toughness of discharged metal, which propagates to the base material despite removal of penetrators from welded portions.
Innovation Solution
A method for manufacturing electric resistance welded metal pipes involves forming an inclined surface on the inner corner portion of metal strips before welding, ensuring the inclined surface remains on excess metal post-welding, preventing the discharged metal from being welded to the excess metal, thus avoiding cracking propagation to the base material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electric resistance welding is performed after providing tapered shapes to side ends of metal strip, then penetrators can be removed from welded portions, but cracking occurs in discharged metal during severe processing such as 90° bending and propagates to base material
Solution Approach 1:
The welded portion is segmented into distinct zones: excess metal containing the inclined surface, discharged metal, and base material. This segmentation creates a physical barrier where the inclined surface on the excess metal prevents crack propagation from the discharged metal to the base material, thus resolving the contradiction between ease of manufacture and cracking resistance
Solution Approach 2:
The inclined surface is formed on the inner surface side corner portion of the metal strip before welding takes place. This preliminary action ensures that when welding occurs, the inclined surface remains on the excess metal and prevents the discharged metal from welding to the excess metal, thereby preventing future cracking propagation
2Ease of manufacture
If discharged metal is removed from welded portion, then penetrator removal is facilitated, but toughness of discharged metal decreases due to heat influence making it prone to cracking
Solution Approach 1:
The harmful discharged metal is extracted or isolated from the welded portion by ensuring it does not weld to the excess metal through the inclined surface configuration. This extraction prevents the discharged metal from becoming a crack propagation path to the base material, while still allowing for its removal if needed
3Adaptability or versatility
If severe processing such as 90° bending is applied to electric resistance welded pipe, then pipe flexibility is achieved, but cracking propagates from discharged metal to base material
Solution Approach 1:
The inclined surface on the excess metal serves as a beforehand cushioning measure that prevents crack propagation before severe processing is applied. This structural feature is in place before bending operations, ensuring that even when flexibility is required through severe processing, the crack propagation path is blocked
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 effectively prevents cracking propagation to the base material even during severe processing, such as 90° bending, by maintaining the inclined surface on excess metal and avoiding welding of discharged metal to it, enhancing the pipe's durability and bendability.
Implementation Method 1
welding the side ends by high frequency heating
Data Source
AI summary
A method for manufacturing an electric resistance welded metal pipe by butting side ends of a metal strip against each other and then welding the side ends by high frequency heating to manufacture an electric resistance welded metal pipe, each side end being provided with an inner surface side corner portion located on an inner surface side of the electric resistance welded metal pipe, the method includes a step of forming an inclined surface at the inner surface side corner portion before butting the side ends of the metal strip, and wherein the side ends are butted and welded to each other such that the inclined surface remains on an excess metal of the metal pipe after electric resistance welding and a discharged metal is not welded to the excess metal.