RGB ENGINEERING

INSTALLATION EXAMPLES: NORTON TRAVELING CARRIAGE ROLL GRINDER

COMPUTERIZED CROWNER RETROFIT SYSTEM

The photos immediately below show a 36" Norton roll grinder that was purchased from government surplus, still crated, in near "mint" condition.  The machine had been originally manufactured for grinding cylindrical gun barrels, and therefore was not equipped with a crowning mechanism.  However, as can be seen from the pictures, the trunnion tilt axis was included, probably because it was the most cost effective and expeditious alternative at the time.  This grinder has over 50 feet of wheel travel, making it a perfect candidate for paper mill roll grinding.  However, since Norton is no longer in the roll grinder business, and due to the scarcity of the parts, retrofitting the original mechanical crowning mechanism would have been very expensive and time consuming.  This customer elected to purchase the RGB Engineering FFG/FFP/SLA computerized crowning system.  Not only does this provide the means for grinding any type of crown profile, mathematical or empirical, but there are a number of side benefits that helped justify the project.  First of all, it is very difficult to maintain straightness accuracy on a 50' single wheel grinder.  The crowner "bed correction" feature makes it possible to hold paper mill class tolerances using the computer to compensate for mechanical misalignments.  Also, with the original Norton design, even with the crowning attachment, the operator did not have any means for fine feeding the wheel using the trunnion "tilt" axis.  All infeeding had to be done using the grease lubricated slide ways, and acme screw.  With the RGB crowning system, a precision handwheel is included that operates the "tilt" system by moving the axis of the crown curve in and out.  Essentially, this superimposes the tilt infeed with the crowning motion.  Continuous and end infeeds can also be programmed using the tilt axis, which has no backlash because it is gravity preloaded.  The wheel infeed can be controlled much more accurately than with the subbase slide ways. 

The photos below left show the same machine after the RGB crowner retrofit.  The SLA consists of a special design ball screw, uniquely constructed for minimal backlash, driven by a DC servo motor through a zero backlash harmonic drive reducer and timing belt connection.  The LVDT measures the tilt motion of the wheelhead directly, and provides the linear feedback for the servo drive.  As can be seen, the actuator assembly interfaces very nicely with the Norton wheelhead and subbase.  Minimal machining was required (mostly drilling and tapping) to mount the new parts.  The carriage position encoder assembly, not shown in these pictures, is located on the front side of the carriage drive case.  The photo on the right shows the remote FFG monitor and keyboard.  This satellite work station allows the operator to make keyboard entries and observe the computer screen from the normal work station on the carriage.  The precision infeed handwheel is conveniently located on the control panel.  One full turn = .001" of tilt infeed.  With this resolution, movements of 50 micro inches can be easily controlled, which would not be possible using the subbase slide ways.