«Improving the Reliability and Performance of Bar Mill Rolling Stand Spindles»

Parthiv R. Amin, Richard J. Maguire, Michael T. D’Angelo.

http://rollway-bearing.be/EPTroot/public/Kopflex_tech_papers/PRA1.PDF

1 Introduction of Laclede Steel & Kop-Flex

1.1 Laclede Steel 14 inches Bar Mill

        Laclede Steel is located in Alton, Illinois, and has been in operation for 88 years producing steel bar, pipe and strip. The 14 inches bar mill is comprised of 19 horizontal and vertical stands; split into 9 roughing, 4 intermediate, and 6 finishing stands.

        Laclede incorporates stand changes in their production, as contrasted to roll changes. This means rather than changing the rolls and mounting new ones, the entire stand is unfastened from the base and replaced with another. For a horizontal stand change, assembly and disassembly is not much different from a standard roll change, but the vertical stands require a blind assembly, since the motor, gearbox and spindle are located under the floor as shown in the figure 2. This blind assembly is a complicated procedure since the clutch faces of the drive spindles must be lined up properly at installation to permit engagement when the stand is brought in at an angle to clear the housing.

        These drive spindles are designed to telescope to accommodate stand changes for various roll configurations, depending on the product being rolled. This roll shifting takes place by grabbing the spindle center shaft and sliding it relative to the stand to accommodate the shift. The roll end of the spindle is held to the roll end pod through a fixed connection and Item 6 in figure 1.

1.2 Kop-Flex

        Kop-Flex, formerly the power transmission division of Koppers Company, was started in 1920 with the invention of the first gear coupling - known as the Fast’s^® coupling. Kop-Flex is presently a division of Emerson Power Transmission Corporation, a division of Emerson Electric Company. Kop-Flex’ headquarters is located in Baltimore, Maryland with a second plant in Rexdale, Ontario, Canada. Kop-Flex designs and manufactures all types of couplings, ranging from gear type, grid, elastomer (resilient), and disc type - to gear spindles and, since 1991, universal joints known as Maxxus. Primary consumers are steel mills, aluminum mills, the paper industry, and the petrochemical and refinery industries.

2 Universal Joint Design

        To better understand the mill’s requirements, Laclede Steel and Kop-Flex had several meetings between Engineering and Maintenance staff to study the existing technology and see what could be done. This allowed for the drawings to be brought up to date, as well as to see how the spindles operated under normal conditions. The conditions were studied jointly with the mill staff, to optimize the design that fit the mill’s operation and performance requirements. The universal joints (shown in the figure 3 and 4) were designed with the overall requirements of:

1. Reduce the unscheduled downtime - need reliable solution.

2. Easy roll end assembly with the least amount of man-hours for roll/stand change.

3. Easy to maintain and operate.

Figure 3: Universal Driveshaft Design

Figure 4: Universal Driveshaft

        The driveshaft (universal joint) design for Laclede Steel was completed in 1995, and the universals were installed in the beginning of 1996 on stand 7. The proposed universal joint met all the requirements set forth by Laclede steel:

1. All parts were common between the horizontal and vertical stands, with a special seal configuration and plate to prevent water damage at the gearbox end. See figure 5.

2. To minimize spare requirements and reduce inventory costs, all parts were common between intermediate and finishing stands except the center shaft and pinion end pod.

3. To maintain interchangeability between stands and reduce inventory requirements, the universal joints were designed to be interchangeable between Intermediate and Finishing stands and for both horizontal and vertical configuration.

Figure 5 – Construction of plate and deflector

3 Summary

        The success of a pro-active working partnership has resulted in:

1.a reduction in unscheduled downtime - 800% reduction in mechanical delays due to universal joints and 200% due to improved gear spindle design;

2. reduced costs - about $110,000 savings per year on spindle parts cos;

3. increased productivity;

4. reduced much of the maintenance associated with drive spindles;

5. reduced noise.

        Due to these successful results, both Kop-Flex and Laclede Steel plan to extend the cooperative partnership to continually improve the throughput and quality of steel at Laclede Steel. In the future, more universal joints will replace the existing gear spindles to improve yield, save costs, and improve the quality.