With their ease of installation, removal and replacement, our industrial Gear Couplings, Shrink Discs and Locking Assemblies are ideal power transmission components for steel production equipment, which have some of the most demanding operating conditions around. One specific application within the steel industry involves the bridle roll systems in cold steel mills.
Bridle roll systems, which are located near the melting furnaces, roll blazing hot sheets of metal to the next step in the milling process. Due to the size and weight of the rolled materials, these roller assemblies are very large, with diameters typically ranging from 4 to 5 feet.
The Challenges of Shrink-Fit Connections
To withstand the high torques involved in steel mills, we often see bridle roll assemblies with shrink-fit connections. Installing these couplings on the machine shaft is a time-consuming and labor-intensive process that involves first quenching the coupling in hot oil for several hours, causing it to expand, and then centering the component on the shaft. Because it’s a keyed connection, installers must take the time to properly line up the key.
To remove or replace these couplings, at a minimum the manufacturers must cut through the coupling components or — worst case — the entire roller shaft. This process poses several challenges:
- Due to the size of the bridle rolls, workers must operate saws and other heavy machinery several feet in the air, creating a potential safety hazard.
- The cutting process is very labor-intensive. Many workers report sore backs from handling the heavy equipment for extended periods of time.
- In the case where it’s necessary to cut through the shaft, which can exceed 10 inches, workers tend to wear through several saw wheels, increasing material costs.
- While workers replace the coupling or shaft, all other mill processes are put on hold, creating time-consuming and costly downtime.
Friction-Locked Connections Offer High Torque
Our power transmission components facilitate installation and avoid the challenges associated with removing and replacing bridle roll shafts — all while keeping your workers out of harm’s way, minimizing your material costs and avoiding extended downtime. They include the following components:
Locking Assemblies, which are internal clamping connections rated up to 1,760,000 Nm (Rfn 7005). These friction-locked shaft-hub connections can precisely fasten all types of hubs while bridging relatively large fit clearances.
Compared to shrink-fit connections, these components are easy to install, adjust and remove. They join shaft components by making 360-degree contact with the shaft and its mating component. As you tighten the assembly, it expands radially, creating a robust compression fit between the two parts. Within the device, compression forces are generated through the interaction of tapered surfaces on the Locking Assembly’s inner and outer thrust rings.
A second solution for bridle roll systems includes our ZIAUU Gear Couplings and Shrink Discs — a combination that also avoids the challenges associated with removing and replacing shrink-fit connections on roller shafts. Ideal for steel mills and other industrial sectors, our torsionally rigid Gear Couplings can transmit high torques up to 195,000 Nm from shaft to shaft.
The ZIAUU series, in particular, includes two long hubs, enabling you to combine them with our Shrink Disc external locking devices. A modern method for creating a mechanical shrink fit, these components offer an even distribution of locking forces and eliminate fatigue-prone keyed connections in heavy-duty applications. Each Shrink Disc consists of one or two thrust rings with tapered bores or a mating tapered inner ring. After placing the device over the hub and shaft, simply tighten the locking screws, drawing the disc’s outer and inner thrust rings together and compressing the hub tightly around the shaft.
To learn more about our products for the steel industry, please visit our industry page.