A leading Midwestern steel bar producer had a problem - one of their roughing mills, reducing billets to steel bars, was experiencing continual breakdown problems resulting from the design of its 45-degree bevel gear sets. The line consisted of six sets of mill rolls, each driven by an AC-motor through reduction gears; the motor and primary gear reducer were horizontal, while the mill pinions were at an angle of 45 degrees above horizontal; and the spiral bevel gear set used to produce the necessary angle was designed with a long bearing span on the bevel pinion shaft. This arrangement had resulted in numerous shaft and gear failures in the years since its installation.
One of Philadelphia Gear's Regional Service
and Manufacturing Facilities had been servicing the plant
for over 10 years, providing consistently responsive maintenance
in getting these units back online, despite that the original
drives were not manufactured by Philadelphia Gear. Given the
opportunity to replace two of the finish-end drives, Philadelphia
Gear provided the steel producer with the necessary drives within the existing configuration, performing without problems.
As the shaft continued to break on the bevel gears, Philadelphia
Gear Regional engineer Bob Johnson, and Technical
Center engineers Bill Clifton and Steve Luchetta were
turned to for a solution. This dynamic - teaming local personnel
who were very familiar with the drives in question as well
as the demands of the plant, with world-class engineers -
afforded Philadelphia Gear a unique opportunity to solve the
Philadelphia Gear recommended the customer replace the first
three stands (which were also the most heavily loaded) with
specially engineered drives aligned to the angle of the mill
rolls, eliminating the need for the bevel gear set.
The technical team designed an extremely unique drive to fit a very tight envelope, at
the same time upgrading the mill's power level by 60%. The
new design incorporated primary and secondary gear reductions
and mill pinions in a single housing, while still fitting
in the space of the previous drive. Each of the three stands
had a unique gear ratio. Thus, the capacity had been designed
into the smallest primary gear reduction to maintain the maximum
number of common components between the drives.
Philadelphia Gear was able to design and manufacture
these custom gear drives in less than half the industry average
time in order to install and start up the line during a two-week
shut down window.