Designing Rolling Mills with Reliable Motion Systems

In the steel industry, the malfunction or failure of a single component can lead to the shutdown of the entire steelworks. That is why reliability is a fundamental requirement that has to be taken in due consideration also for the drives of the rolling rollers. The Sumitomo Cyclo Drive is highly reliable. Thanks to its design, it offers high shock load capabilities and lends itself to a variety of configurations for demanding customizing requirements.

by Alberto Lionello

The conveying system that links one process to another is the lifeblood of any rolling mill. In the steel industry a single component can shut down production of the steel mill; this is why this part is strictly important and needs to be designed considering, first of all, its reliability.
Many older designed mills utilize single drive systems (motor, coupling and speed reducer) to power several conveyor rolls. This design uses the primary roll to drive four to five other rolls slaved to the prime mover by means of a secondary transmission (typically a chain).
Technology has improved many processes of the rolling operation, including the design of the roll drive. While the concept of the single drive system is cost-efficient up-front, it is costly in lost production if a problem develops with one of the drives. The failure of aby drive would lead to the shutdown of an important part of the line, preventing steel to be transferred fast enough to keep up with production.
With the multi-drive system, each rolling roller uses a direct drive, so in the event of a stop of a slave, there is no stopping of the line and production is always guaranteed. Ultimately the overall cost of the individual roll drive approach is considerably lower because it increases productivity and savings by significantly reducing downtime.
Preventative maintenance procedures, spare parts procurement, system monitoring and rapid change out procedures are some design considerations for components critical to production. Rolling operations consider the electro-mechanical system that delivers power to the roll drives are “critical to production” component.
Several solutions are available on the market for this application. Among these, one solution that is worth considering is the Sumitomo Cyclo drive. This technology can offer important benefits in this kind of industry, as described below.

Reliability: a major requirement
Sumitomo Cyclo’s unique internal configuration makes it more performing compared with speed reducers using common involute tooth gears. Cyclo components operate in compression, not in shear. All rotating components are fully hardened, vacuum degassed, bearing grade steel, manufactured to strict tolerances and finishes. Along with the ductile iron housing, this unique design enables the Cyclo speed reducer to provide consistent, reliable performance for years in hostile environments such as steel mills. All Cyclo products are warranted for a full two years of service.

High Shock Load Capabilities
Unlike gear teeth with limited contact points, a Cyclo has two-thirds of its reduction components in contact at all times. The Sumitomo internal parts are comprised of fully hardened, 52100 bearing steel, produced with stringent tolerances and finishes, which guarantees perfect load sharing among the load-carrying elements. Housings are made of ductile iron, which provides superior vibration dampening capacities when compared to grey iron.

Superior Sealing Capabilities
Cyclo offers dual double-lip seals that provide a protection barrier against the penetration of contaminants or lubricants. The outer dual lip seal is the first barrier against external contamination. The inboard seal is a double lip seal that serves as an additional protection barrier and lubrication retention.
These seals are also available in Polyacrylate, Silicon, and Viton material that will provide protection in high or low temperature applications or where chemical resistance is required.

Maximum versatility in design and mounting configurations
Sumitomo Cyclo offers numerous design configurations regarding mounting configuration, motor mounting, lubrication, and ratio range. Figure 5 illustrates some of the many motor mounting options available.
Sumitomo Cyclo also offers many reducer mounting options. The reducers can be mounted in any orientation (horizontal, vertical or inclined).
Mounting options also include foot mounting, wall mounting, and flange mounting. Units are available in both oil or grease lubrication. Grease lubricated reducers offer the advantage of low maintenance, and allow for universal mounting configurations. They can be installed in any direction and at any angle without consideration for lubrication flow.
The Cyclo reducer has the distinct advantage of a very wide range of ratios. Due to its unique cycloidal design, ratios of 87:1 (and in some cases 119:1) are attainable with a single reduction stage. Multiple reductions allow Cyclos to operate at very high ratios, while maintaining relatively high efficiency.
Sumitomo Cyclo speed reducers have a proven track record of solving difficult applications within the steel industry. Figures 5-8 are a few examples of Cyclo reducers’ solution capabilities.

Customization Capability
Customization is common when dealing with the many design parameters of diverse applications. Over the years, Sumitomo has partnered with our customers to provide unique solutions for demanding applications. In many cases, we are requested to provide “drop-in” reducers for obsolete equipment. Because the Cyclo is compact and power dense, we can offer many design modifications to fulfill these special requirements.
The Sumitomo solution to “drop-in” for various speed reducer manufacturers is made possible by the Cyclo’s unique “F” flange design.