Downtime Elimination, Adopted Suggestion

Pulley Press Suggestion, Murata Pulley Cell
Pulley Press Suggestion. Four machines were updated with this modification at Delphi Thermal and Interior.

PROBLEM
The use of a 12mm proximity switch to detect proper pulley positioning on the bearing press arbor results in frequent downtime due to damaged prox, misadjustment, and machine malfunction. Furthermore, unnecessary prox replacement results long before the life expectancy of this switch would require it, due to interference damage.

The current situation usually results in a call for an electrician and tinner even for a simple model change. This problem repeats itself several times each week, across all shifts.

Currently, a metal bracket attached to the underside of the arbor positions the TurckBi2-M12-AD4X-H1141 prox next to the arbor, to detect that the pulley is present, and not misloaded by the placement robot.

Due to the 19.5mm mounting nut, the center of the prox's sensing range is not aligned with the target pulley on small diameter pulleys. On large diameter pulleys, the target area is angled in a different plane, and adjusting the prox to read properly places it in a position susceptible to damage. This also usually necessitates an electrician/tinner call at each change of models.

In either case, increasing the sensing range from the current 2 millimeters would not be an acceptable solution, as pulleys could still be placed in cocked positions, and wrecked onto the arbor during a bearing press, resulting in tinner/millwright/machine-repair call, easily a multi-hour downtime event.

For either diameter pulley, the sensing range of the prox is at the outer limits of its design capability, and this often necessitates the electrician/tinner combo to tinker with the adjustment at random times of the week. Also, the indicating light on the prox is not visible to the operator or maintenance technician.



SOLUTION
Fabricate a new bracket to mount to the underside of the arbor, as in the current situation. Attached to this, with button-head screws, would be a plastic block, drilled for a 5mm prox, held in place by a set-screw.

Omron E2EC-C1R5D is a 2-wire DC prox that is electrically similar to the current Bi2-M12-AD4X-H1141, so that no panel wiring or logic changes would be required. This prox has a remote amplifier that could be mounted anywhere visible on the machine, unlike the current, un-indicated situation. It could be pre-assembled with a connector that simply plugs into the existing Turck cable (Connector: Setech 0107-4453).

Although this prox has a shorter sensing range (1.5mm), it can be positioned precisely to detect the flat backside of any pulley currently in use (Figures 5,6), without model-change adjustment.

Additionally, the prox adjusting screw is accessible to the electrician through the part load door, so it will no longer be necessary to call a tinner to remove the side safety guard when adjustments are called for.

A tinner and electrician within a two-hour downtime window, per machine, could easily achieve this modification. This is likely less than the downtime caused by the current situation each shift, each week!

The payback of this modification will be almost immediate.