Methods of laser welding zinc coated galvalized steel are disclosed. In a method that relates to forming hem joints for motor vehicle body components a sheet of steel is provided with a plurality of V-shaped tabs. When a hem joint is formed the V-shaped tabs together with a surface of another sheet of steel form gas venting channels that provide an escape passage for gas vapors that are developed when the zinc coating is vaporized by laser welding. In another method of laser welding, one of the steel sheets has an axially extending wall that is V-shaped to provide a V-shaped groove and the wall has spaced gas vent holes.

Method of making hemmed joints utilizing laser welding

A method for welding galvanized material including a low vapor pressure mild steel core and a high vapor pressure rich zinc coating includes the steps of arranging components of such galvanized material in juxtaposed relationship at a lapped joint; and applying a high density laser energy beam along the lapped joint as a weave pattern in which the weave pattern has a width great enough to bridge the lapped joint and a weave pattern frequency which forms a predetermined weld pool between the components and wherein the lapped joint and weave pattern combine to define a vapor pressure relief path so that the weld pool will not be disrupted during the application of the high density laser energy beam to the galvanized components.

Method for welding galvanized material

An apparatus comprises a fixture for positioning a first sheet metal part in proximity of a second sheet metal part so that each sheet metal part has one surface facing the other sheet metal part across a gap and one surface facing away from the other sheet metal part, wherein at least one of the sheet metal parts comprises galvanized steel. A laser beam delivery device applies a laser beam to one of the facing away surfaces. A feed wire source provides a feed wire comprising a supplemental wire and a reactive agent at an intersection of the laser beam and the one facing away surface. The apparatus affects relative movement between the one facing away surface and the laser beam to provide a laser weld between the two sheet metal parts.

Welding process and apparatus

This work investigates the use of a trifocal laser intensity distribution to control the applied heat profile for laser brazing of hot-dip galvanized steel. Process analysis of conventional monofocal brazing processes showed that spatter and other process disruptions mainly originate from zinc dissolution and evaporation at the wetting line. In order to increase process stability and seam quality, a trifocal brazing method was developed and applied for brazing experiments. A transient three-dimensional model of the brazing processes shows a shift of the achieved temperature distribution and thus a separated evaporation of the zinc coating prior to the wetting with molten CuSi3 brass. The influence of the adjusted intensity distribution in the process area was analyzed with high-speed video imaging, thermal imaging, and metallographic analysis of the seam properties. The experimental analysis confirms that during trifocal brazing, a local zinc evaporation takes place prior to the spreading of the molten filler metal. As a result, a less turbulent processing zone and a superior seam quality are attained.

Three-beam laser brazing of zinc-coated steel

A laser welding apparatus comprises a mount attached to a laser beam delivery system and a cylinder attached to the mount. A piston having first and second piston ends and a piston body sealingly and slidably engages with the cylinder dividing the cylinder into first and second piston chambers. The piston is slidable between an extended position and a retracted position and has a central axial bore through which a supplemental wire is fed. A wire supply provides supplemental wire to the first piston end and a delivery head attached to the second piston end delivers the supplemental wire proximate to a laser beam and a work-piece.

Welding apparatus and process

A laser welding method and apparatus for welding stacked coated members (1. 2 1 in which voids in the welds are positively eliminated. A spacer (14) is disposed between the two members (1, 2) to be welded. This provides a path (16) for discharging gas formed by heating the coating matenal. The method and apparatus of the invention are useful for the laser welding of base members coated with metals having a lower melting point than the metal of the base, paints and oils. Preferably, the width of the gap is in a range of 0.1 mm to 0.5 mm.

Laser welding method and apparatus

PURPOSE:To obtain a good weld zone having no defect such as blowhole by superposing materials to be joined which are coated with coating materials on each other to provide a prescribed gap between each other thereby constituting a discharge passage for the gas of the coating materials gasified by laser welding. CONSTITUTION:A spacer 14 and a clamper 15 which are connected to cylinders 17, 18 and are movable upward and downward are provided and the materials 1, 2 to be joined which are superposed via the spacer 14 are fixed onto a working table 13 by the clamper 15 in the stage of superposing the materials to be joined which are coated by the coating materials and subjecting said materials to laser welding. A laser beam 3 is irradiated on the superposed part of the materials 1, 2 while the prescribed gap 16 is formed in said part. The gas of the coating materials 4-7 gasified by laser welding is discharged from the gap 16. The good weld zone having no weld defect such as blowhole is thus obtd.

Junichi Gotoh

Papers

Laser welding method and apparatus

Method and device for laser welding