There are various processes to join two panels like folding/tab joint , Welding, self piercing rivet, pulling rivet, Self clinching, screw joints, bolting etc. Here are some of the processes which are used in BIW panel joining:
1. Spot Welding
Spot welding is a thermal process in which metals are joined by heat generated by resistance of electric current. In this work pieces(panels)are placed together under high pressure exerted by electrodes. When a large amount of current is passed through the panels , current melts the panelon that specific spot where electrodes are touching the panel and forms weld.
There are various guns to do spot welding but most commonly used guns are X – TYPE and C – TYPE gun. X guns are also known as scissors or pinch gun. These guns are selected on the basis of location of gun mount,tooling access and the geometry of the panel. X-Gun or C-Guns can different shapes of die post as per the requirement.
Mentioned area is known as die post of the gun.
X GUN :
In this gun actuator is parallel to the weld plane and and actuates about a pivot.
X type guns are used where accessibility is constraint.
C GUN :
C-type or straight action gun actuates perpendicular to the plane and in line with the weld.
GUN STROKES :
Working Condition: That condition when both electrodes on gun are touching the panel while doing spot welding is called as Working Condition.
Semi opening condition or intermediate stroke: After completing one stroke, gun moves to next spot without opening completely is knownas intermediate stroke or semi opening. This opening may differ as per the requirement.
Full Stroke or Full opening : it is the maximum open condition of moving electrodes of the gun.
Basics while considering a gun :
- Preferably Fixed electrode should be visible to the operator.
- Gun should have good reach-ability to all spots.
- As much as possible same gun should be used for maximum no. of spots.
- Tip wear out condition (preferably 5 mm) should be considered while designing the tool.
Self piercing Rivet(SPR) :
SPR- Self-piercing riveting is a cold mechanical fastening technique for joining of two or sheet metals or panels. For joining , the rivet is driven into the matel at a controlled force, piercing the panels, Then rivet radially expands into the bottom layer,due ti the shape of die, forming a mechanical interlock.
This process is quite helpful in joining of aluminium panels.
MIG WELDING(Metal Inert Gas) :
Metal inert gas welding or MIG Welding is based on the electric arc welding process where completion of an electric circuit between positive and negative poles creates an electric arc , which generates tremendous heat permitting the fusion welding of metals.
GLUE GUN :
Glue guns are used for metering of sealentso or adhesive bonds.
adhesive bonding and sealing are used for various applications in the modern automotive induastry.