Engineers, works managers - and accountants even - have been focussing firmly on the role of ac drive systems and energy efficient motors as the means of reducing energy costs. This focus is entirely justified by the undeniable contribution to energy saving that inverter/motor combinations can make in most applications. However, it does not take into account cases where energy saving drives and high efficiency motors are routinely fitted as part of a larger power transmission train.
In these instances there are other components, which, if not optimised for energy use, can cancel out the potential for achieving savings. Alternatively if they are considered and specified they can substantially enhance the savings made by motors and drives.
One product area, in particular, that has been overlooked by industrial consumers is power transmission roller chain. Despite this lack of awareness, the potential for achieving savings is indeed real, and is proven by two products from Tsubaki UK. Both aimed at conveyor applications, Bearing Roller Conveyor Chain (BRCC) and Double Plus chain, can help to optimise the energy savings of any power transmission system, protecting the gains made further up the transmission chain via energy efficient motors and drives.
The novel BRCC design integrates cylindrical roller bearings inside the chain, providing increased strength and reduced friction. This allows a decrease in driving power, enabling users to downsize by selecting a chain up to two sizes smaller, and to reduce costs by using smaller drive motors. Driven conveyors thus require less energy to operate, making them more economical. Tsubaki’s BRCC reduces chain running resistance to around a third that of conventional conveyor chain. The chain configuration also ensures that any irregular movement of the conveyor caused by stick slip is completely eliminated, and this is so right down to chain speeds as low as two metres per minute.
Packing and sealing grease into the bearing area of the chain rollers further enhances the BRCC’s low friction operation. This also reduces lubrication maintenance by up to ten times, depending upon the application, and increases the energy efficiency characteristics of the chain. In addition, the combination of sealed lubricant and inherent low friction coefficient solves the problem of early wear between bushing and roller as a result of dust ingress. This simple expediency can extend chain wear life far beyond that experienced with standard conveyor chains.
Faster conveying - reduced motor speed
The term ‘free flow’ is aptly applied to describing the energy saving characteristics of Tsubaki’s Double Plus conveyor chain, as it conveys at more than twice the speed of ordinary free flow chain. The design incorporates a large centre roller, and a smaller outer roller, which supports the chain on a guide rail. When engaged, the large centre rollers (upon which conveyed objects travel) rotate the same number of revolutions per minute as the small rollers. However, since the diameter of the large rollers is approximately 2.5 times that of the smaller ones, conveyed objects move along approximately 2.5 times faster than the chain.
The benefits are that chain speeds of up to 60% slower can be used without affecting the object conveying speed. Motor drive speeds can thus be reduced, leading to substantial energy savings, and noise levels some 15db lower than those of plastic side roller chains.