Multi-station welding systems in contemporary automated welding production lines demand quite high indexing precision. While cam indexers have become a cheap and effective alternative with their special mechanical advantages, traditional servo indexing devices are highly expensive but extremely accurate. The creative use of cam indexers in multi-station welding together with their exact control technology will be discussed in this paper.
Cam indexers' technical benefits
By means of exact meshing of the cam curve and the roller, the cam indexer achieves indexing positions using a simply mechanical construction. Its main notable benefits are:
High repeatability: sufficient for precision welding up to ±15 arc seconds
Instant dynamic response: indexing action is finished without any electrical delay.
Strong anti-interference: fit for the welding environment; unaffected by electromagnetic interference
Design free of maintenance: one lubrication will operate hundreds of hours.
Innovative control strategy
We have developed the following creative technologies to reach better-precision indexing control:
1. Method of temperature adjustment
Real-time monitoring of ambient temperature changes allows the driving angle to be automatically changed to offset the little mistake resulting from metal thermal expansion, hence maintaining steady indexing accuracy within ±5 arc seconds.
2. Dynamic preload adjustment
The clever hydraulic system guarantees the indexing rigidity and not only lowers wear by automatically adjusting the preload between the cam and the roller depending on the load change.
3. Technology for suppressing vibrations
Introduced at the beginning and conclusion of the indexing step, the S-shaped acceleration and deceleration curve helps to greatly reduce mechanical vibration and raise welding quality.
Actual application case
Following the upgraded cam indexer in a certain automotive parts welding line:
From 1.2 seconds to 0.8 seconds, the indexing cycle runs in half.
From 98.5% to 99.9% the welding qualifying rate rises.
The interval of equipment maintenance is from three months to six months.
More than thirty percent of energy use is cut off.