Laser welding device for roll forming system and control method thereof

Abstract

A roll forming system which roll-forms a shaped beam by a roll forming unit including a plurality of roll formers is disclosed. A laser welding device for the roll forming system may include: front and rear guide means disposed apart from each other at the rear of the roll forming unit, and guiding movement of the shaped beam; laser welding means mounted above and between the front and rear guide means, reciprocatedly rotating a mirror by controlling a mirror motor so as to irradiate a laser beam to a welding position of the shaped beam, and thereby forming a welding bead having a predetermined welding pattern; forming speed detecting means detecting a forming speed of the shaped beam and transmitting a signal corresponding thereto to a controller; a camera disposed at the rear of the laser welding means, photographing a welding portion of the shaped beam, and transmitting an image signal corresponding thereto to the controller.

What is claimed is: 
     
         1 . A control method of a laser welding device for a roll forming system, comprising:
 (a) detecting a forming speed of a shaped beam;   (b) laser welding each welding position of the shaped beam by controlling an output and a moving speed of a focus of a laser beam to be reference values;   (c) determining whether the forming speed is within a predetermined error range;   (d) receiving and analyzing image information of the welding position of the shaped beam in a case that the forming speed is within the predetermined error range;   (e) determining whether an analyzed welding pattern analyzed from the image information maintains a predetermined welding pattern; and   (f) maintaining the output and the moving speed of the focus of the laser beam in a case that the analyzed welding pattern maintains the predetermined welding pattern.   
     
     
         2 . The control method of  claim 1 , wherein the output and the moving speed of the focus of the laser beam are controlled according to the forming speed detected in real time before performing the step (d) in a case that the forming speed is out of the predetermined error range at the step (c). 
     
     
         3 . The control method of  claim 1 , wherein a malfunction signal is output and the control method of the laser welding device is finished in a case that the analyzed welding pattern does not maintain the predetermined welding pattern at the step (e). 
     
     
         4 . The control method of  claim 1 , wherein the predetermined welding pattern is set as a contour of a welding bead formed along a predetermined zigzag line. 
     
     
         5 . The control method of  claim 4 , wherein information about the contour of the welding bead is stored as the predetermined welding pattern. 
     
     
         6 . The control method of  claim 1 , wherein the analyzed welding pattern is a contour of the welding bead recognized from shading difference between a basic material and the welding bead at each welding position of the shaped beam.