Multi-Tubular Reinforcement Beam With Zinc-Free Forge Weld Seam
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Solution Overview
Problem
Galvanized sheet metal is difficult to form and weld, especially in roll forming operations due to the presence of a zinc coating, which interferes with laser welding and affects the quality of the welds.
Innovation Solution
A high-frequency electric resistance welding process is used to heat the surfaces of the galvanized metal sheet to a temperature that burns off the zinc coating, forming a solid state forge weld without zinc inclusions, using electrical contacts to deliver the current and a closing pressure roll to press the heated surfaces together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanized sheet metal is used to form reinforcement beams, then corrosion resistance is improved, but welding quality deteriorates due to zinc coating interference
Solution Approach 1:
The patent applies preliminary action by heating the galvanized sheet metal surfaces to burn off the zinc coating immediately before welding occurs. The electrical resistance heating contacts pre-treat the surfaces by removing the harmful zinc layer, creating a zinc-free zone at the weld interface. This preliminary removal of the galvanized coating enables subsequent high-quality welding while maintaining the corrosion-resistant galvanized coating on the non-welded portions of the beam.
2Productivity
If laser welding is used on galvanized sheet metal, then welding speed is improved, but weld integrity deteriorates due to zinc oxide gas formation
Solution Approach 1:
The patent converts the harmful zinc coating into a beneficial process by using electrical resistance heating to deliberately burn off the zinc coating before welding. The zinc coating, which normally causes welding defects, is transformed into a controlled pre-treatment step that eliminates the source of problems. The heating process converts the zinc-rich surface into a zinc-free surface, turning the previously harmful galvanized coating into a useful preparatory action that ensures weld integrity.
3Productivity
If roll forming is used to form the beam, then manufacturing efficiency is improved, but forming difficulty increases due to galvanized coating
Solution Approach 1:
The patent applies local quality by selectively removing the galvanized coating only at the specific locations where welding will occur, while preserving the galvanized coating on all other portions of the beam. The electrical resistance heating contacts create localized zinc-free zones at the weld interfaces without affecting the corrosion-resistant coating elsewhere. This localized approach maintains the overall benefits of galvanized steel while eliminating forming difficulties only where necessary for welding operations.
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 process achieves high-quality welds with a narrow heat-affected zone, eliminating zinc oxide gases and ensuring consistent weld integrity, suitable for forming multi-tubular reinforcement beams for vehicles.
Implementation Method 1
The resistance of the high frequency current delivered by the electrical contacts heats the outside surface of the two opposing portions of the weld seam to a suitable welding temperature
Implementation Method 2
the galvanized coating at least partially burns off and forms zinc oxide gas
Implementation Method 3
the two heated opposing portions are then pressed together by the closing pressure roller to from a solid state forge weld
Data Source
AI summary
A reinforcement beam for an automotive component is continuously formed with a metal sheet that is roll formed to have at least one tubular portion that extends along a length of the reinforcement beam. A solid state forge weld is formed between an edge of the metal sheet and an intermediate portion of the metal sheet to close a seam that extends along the tubular portion of the reinforcement beam. Prior to forming the solid state forge weld, select portions of the metal sheet are heated to a desirable welding temperature with a high frequency current delivered by electrical contacts to opposing sides of the weld seam. The desired welding temperature may burn off a galvanized coating on the metal sheet at the select portions prior to forming the solid state forge weld that is generally void of zinc inclusions.