Roll-Formed Hollow Body Seam Heating for Hydroforming Integrity
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Solution Overview
Problem
The integrity of welds in roll-formed tubular structures is compromised due to strain hardening and grain refinement, leading to decreased formability and strength gradients across the weld, which limits their ability to maintain integrity during hydroforming.
Innovation Solution
A forming system comprising a roll forming system and a hydroforming system, where the roll forming system includes an inline heater to heat the seam region of the intermediate hollow body, providing stress relief and improving material property distribution, thereby enhancing the integrity of the weld during hydroforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If roll forming is used to form tubular structures, then productivity and manufacturing efficiency are improved, but strain hardening occurs in the material which adversely affects formability
Solution Approach 1:
The patent applies heat treatment parameter changes to alter the material's physical state. By heating the seam region to specific temperatures (e.g., 100-500°C) and controlling dwell times, the material's hardness and formability are adjusted to enable successful hydroforming while maintaining production efficiency
Solution Approach 2:
The patent performs preliminary heat treatment of the seam region before hydroforming. This preliminary action softens the strain-hardened material in advance, making it more formable during the subsequent hydroforming operation without compromising the productivity gains from roll forming
2Ease of manufacture
If seam welding is used to join longitudinal edges, then the tubular structure is formed, but grain refinement and micro-cracks occur which decrease weld integrity
Solution Approach 1:
The patent changes the thermal parameters by applying controlled heating to the weld region. This heat treatment modifies the microstructure, reduces hardness gradients, and eliminates micro-cracks, thereby improving weld integrity and reliability for hydroforming applications
Solution Approach 2:
The patent converts the harmful effects of welding (grain refinement, hardness gradients, micro-cracks) into beneficial outcomes through heat treatment. The controlled heating process transforms the brittle, hard weld metal into a more ductile state, turning the previously harmful microstructure into an asset for formability
3Ease of manufacture
If seam welding is used to join longitudinal edges, then the tubular structure is formed, but strength gradient occurs across the weld which limits hydroforming capability
Solution Approach 1:
The patent applies thermal parameter changes through controlled heating of the weld region. This heat treatment creates a more uniform temperature distribution that reduces strength gradients across the weld, enabling the material to undergo hydroforming without premature failure at the seam
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 inline heating process improves the formability and integrity of the seam region, allowing the tubular structures to withstand hydroforming forces without adverse effects on the final in-service strength, thus overcoming the limitations of traditional roll forming and welding methods.
Implementation Method 1
The inline heater is downstream from the joining station and selectively heats at least the seam region of the intermediate hollow body
Implementation Method 2
The hydroforming station is downstream from the inline heater and hydroforms the intermediate hollow body to the final hollow body
Data Source
Figure 1
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AI summary
Disclosed herein are systems and method for forming a final hollow body from a metal strip. A forming system may include a forming station, a joining station, an inline heater, and a hydroforming station. Forming the final hollow body from the metal strip may include receiving the metal strip at the forming station and bending the metal strip to a desired cross-section with the forming station and such that longitudinal edges of the metal strip are abutting. In some aspects, the forming station includes at least one roller. The method may include welding the abutting longitudinal edges together as a seam region via the joining station and to form an intermediate hollow body. The method may include heating the seam region of the intermediate hollow body with the inline heater and hydroforming the intermediate hollow body to the final hollow body with the hydroforming station.