Abstract:
Apparatuses for attenuating a body of hot glass moving over a body of molten metal are each provided with a nip sensing device, a linear movement monitoring device and an angular movement monitoring device. The nip sensing device includes a plurality of discrete phototransistors positioned over the glass and molten metal in a direction generally transverse to the direction of glass movement. When the selected ones of the phototransistors are not conducting, the circuit operates to appropriately energize a motor to move the attenuating apparatus with respect to the edge of the ribbon to provide a nip width within a predetermined range. The linear movement monitoring device includes a potentiometer on each opposed attenuating apparatuses giving an output which is monitored to determine the width of the ribbon. The angular movement monitoring device includes a potentiometer which yields an output which varies with the movement of the apparatus along an arcuate path relative to the edge of the ribbon. In the preferred embodiment the output of the nip sensing device, and the potentiometers of the angular and linear movement monitoring devices, are forwarded to a computer which maintains the ribbon width within a predetermined range.