Seam welders are driven by a motor and a gear-reducing unit imparting rotary motion to the welding wheels in one of three forms: knurl drive, gear drive or friction drive.
The knurl drive is commonly used on coated metals because the knurling breaks up coatings on the metal surface and minimizes “pickup” on the welding wheel. The knurl drive has a great advantage over the gear drive if appearance of weld is not paramount. The knurl drive is the most positive of the three in avoiding “slippage” between driving wheels and the parts being welded.
The gear-drive mechanism is important in many types of work. If the surface of the welding wheel must be flat and free from markings of any kind for such particular work as the seam welding of propeller blades, then there is no alternative but to use a gear-drive mechanism. This is for the reason that knurl- or friction-drive mechanism might cause slippage between the drive wheel and the welding wheel resulting in burned welds.
Advantages of the friction-typedrive are that the peripheral speed of the seam-welding wheels – or the surface speed of the work passing through the wheels – is constant at all times regardless of the wear on the wheel.
