Sink Butt Welding for 120 Degree Door Frame Design

This paper deals with vehicle door 120-degree joint rust issue and water leak faced in most of SUV cars. Generally based on vehicle segment its styling curves and exterior design are defined. A Sedan or Hatchback is provided with curves to show its fluidic design but a SUV is provided with Straight lines to show its aggressive look. In existing condition door frame Joint has sharp joints where weld bead is added to prevent rust in joint area, but still improper seating of weather strip on weld bead cause water leak. Door’s A Pillar Frame and Horizontal Frame match at 120 degree joint edges are chamfered straight to match perfectly. Weld bead runs over the matching profile to join it. But weld bead project over the Frame surface and affects weather strip seating & results in poor sealing. Adhesive added for better sealing also follows the same path on bead and create a path way for water entry. Thus in long run this water stagnates and cause chronic rust issues in frame. This in turn results in high claim cost within warranty period. It is serious issue which should be addressed.

This paper investigates deeply the process of eradicating the rust issue and water leak issue simultaneously. Edges of frame are provided with forming at 120 Joint matching areas. So that weld bead gets sink into shallow depth without projecting out from the surface. This flattened profile of weld bead on frame surface results in perfect sealing of weather strip. This is how sink weld prevents rust and arrest water entry.