Although vibration has been used in the past to minimize weld distortion, results have been inconsistent. Plus, if the vibration is produced with electric power, it poses a risk: loss of welding ground could result in the welding "signal" to be sent thru the vibrator's ground line, damaging it and the power cord and source, perhaps starting a fire.

We have found that using 2 or 3 pneumatic vibrators, mounted with different orientations, and tuned to produce a modulated waveform, is ideal for minimizing weld distortion, often by 70 to 90 percent.

Using two vibrators with similar, but not the same speed, a complex waveform is produced that is ideal for blending a freezing weld puddle. With different vibrator orientations, this unique 3D excitation reduces the distortion caused by welding dramatically.

Many fabrication shops face the most challenging and frequent form of welding distortion when they produce welded structures with most, if not all the welding on one side. Shrinkage on this welded side pulls this side smaller, causing preload / expansion of the opposite side, and the classic “banana” or curl of the structure along its length, or worse, turns a rectangular structure into a “saddle” or potato chip shape.

Example 1 : Making a flatter “egg-crate”

Example 2 : Telescoping masts for mobile drilling system

Example 3 : A tale of two flanges

Rotating weld positioner flange on left was welded without VDW. Several machining cycles were needed to obtain required flatness of 1/16” - 1.5 mm.

IMPROVED SAFETY

A safety risk exists if an electrically powered vibrator is used during VDW: In the event of a loss of the welding ground, the current from the welding arc would instead travel thru the vibrator's ground, located in its power cord. This cable very likely has at most twenty amp capacity, so the cable is likely to overheat, melting the insulation between the ground and power-carrying leads in the vibrator power cable. The vibrator's power cable can ignite.

It should be pointed out that short-circuit protection, whether fuses or circuit breakers, whether located in the vibrator control box or the power line feeding it, ARE NOT in this circuit. Grounds or neutrals, as declared by the National Electrical Code, Underwriters Laboratories, and other safety regulation setting institutions, are never to be passed thru fuses or circuit breakers, since their continuous connection to ground is absolutely required for safe and proper short-circuit protection.

This is the source of ignition of fires caused by overloaded electrical circuits, whether in cables, motors or other apparatus, and is the 2nd most common cause of fires in heavy industry, the ignition of flammable liquids or gases being the only more frequent cause. This is the source of ignition of fires caused by overloaded electrical circuits, whether in cables, motors or other apparatus, and is the 2nd most common cause of fires in heavy industry, the ignition of flammable liquids or gases being the only more frequent cause.