Hot Crimping High-Strength Steel Hollow Profiles
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Solution Overview
Problem
High-strength steels, such as AHSS and UHSS, are difficult to join without weakening the material, as conventional crimping methods often result in material cracks and fractures due to the high tensile strength of these materials.
Innovation Solution
A method involving a soft connection zone in at least one end of the hollow profiles allows for hot crimping, which minimizes material stress and cracking, enabling the joining of high-strength steel components without welding, using a process where the connection zone can be locally rehardened or using an adapter that is heated and quenched during pinching to achieve comparable mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional crimping methods are used to join high-strength steel components, then the joining process is simple and efficient, but material cracks and fractures occur due to high tensile strength
Solution Approach 1:
The patent applies parameter changes by heating the connection zone to austenitizing temperature, transforming the material's microstructure and mechanical properties. This temporary parameter change allows the high-strength steel to become more ductile and formable during crimping, preventing cracks and fractures while maintaining joining efficiency
Solution Approach 2:
The patent employs preliminary action by pre-heating the connection zone before crimping occurs. This preliminary thermal treatment prepares the material by creating a soft, formable connection zone that can accommodate the crimping deformation without cracking, thereby ensuring material integrity during the subsequent joining operation
2Strength
If high-strength steel is heat treated to achieve high tensile strength, then the steel meets crash test requirements, but subsequent heating during processing causes considerable strength loss
Solution Approach 1:
The patent applies local quality by heating only the connection zone locally rather than the entire component. This localized heating creates a soft, formable region specifically where joining is needed, while the rest of the high-strength steel component retains its full strength and hardening, thus avoiding overall strength loss
Solution Approach 2:
The patent segments the heating process to affect only the connection zone rather than the entire component. This segmentation allows differential treatment: the connection zone becomes soft and formable for easy manufacturing, while the bulk material maintains its high-strength properties for structural integrity
3Strength
If high-strength steel components are joined without a soft connection zone, then material strength is maintained, but crimping causes material cracks and fractures
Solution Approach 1:
The patent changes the thermal parameter of the connection zone to austenitizing temperature, which fundamentally alters the material's mechanical properties. This parameter change creates a temporary soft state that is easy to crimp, while the surrounding material maintains its high strength, resolving the contradiction between strength and crimpability
Solution Approach 2:
The patent introduces dynamics by creating a time-dependent state change in the connection zone. The zone transitions from a hard, strong state to a soft, formable state during heating, then returns to a strong state after cooling and hardening. This dynamic property change enables easy crimping operation while maintaining final material strength
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 joins high-strength steel components without material weakening, allowing for the formation of robust hollow frame structures for motor vehicle bodies with reduced risk of fractures and improved connection strength through hot forming and potential adhesive bonding.
Implementation Method 1
at least during pinching, has a soft connection zone in which the high-strength steel is unhardened for pinching
Implementation Method 2
the connection zone can be locally rehardened or using an adapter that is heated and quenched during pinching
Data Source
AI summary
A method for the joining of hollow profiles made from high-strength steel, in particular to form a motor vehicle frame, the hollow profiles being connected to one another, nonpositively and positively against being pulled out, by pinching (crimping) in a connection zone, one end of at least one of the hollow profiles having a connection zone for pinching which is soft at least during forming. This soft connection zone may be hardened during pinching if at least one of the profiles to be joined is made from hardenable steel and is brought to austenizing temperature before pinching.