Patent GB-865618-A (GB)
Title: Improvements in or relating to molten glass feeders
Inventor: WYTHE FREDERICK JOSEPH
IPC: C03B7/10
Filed: 1958-08-07
Abstract: 865,618. Automatic mechanical oscillation control systems. EMHART MANUFACTURING CO. Aug. 7, 1958, No. 25414/58. Class 38 (4). [Also in Group XXIII] Apparatus for controlling a molten glass feeder having a reciprocable plunger and a shear mechanism with co-operating blades comprises first and second electrically-responsive mechanisms operable respectively to effect reciprocation of the plunger and glass-cutting strokes of the blades and a control means arranged to provide a first electrical signal always related to a desired position of the plunger to compare the first signal with a second electrical signal proportional to the actual plunger position, to feed a control signal representing the difference between the first and second signals to the first electricallyresponsive mechanism to effect reciprocation of the plunger, and to supply to the second electrically-responsive mechanism a control impulse in predetermined phase relation with' the control signal to effect a cutting stroke of the blades. As shown, a plunger 4 is reciprocated in a flow regulating tube 5 to control the charge of molten glass issued from an orifice 3 at the bottom of a passage 2 fed by gravity and head pressure from a body 1 of molten glass G, the charge being severed by coacting blades 6-6 of a shear mechanism S for delivery to a glass-forming mechanism 11. The plunger 4 is reciprocated as required by hydraulic means including a plunger valve 7 to control an hydraulic motor 8 detachably fastened through its piston-rod 8a to a plunger chuck 4a. Power for operation of the apparatus is furnished from the electric motor 10 driving the forming mechanism 11 through an output shaft 12 driving a synchro transmitter 13 which supplies an electric voltage to a mechanism box 15. One output conductor 21 of the box 15 controls the shear mechanism S and the other output conductor 16 supplies a servo amplifier 17, with stabilizing network 18, which is used to control the plunger valve 7. Feed-back control of the plunger 4 is provided by an electro-mechanical transducer 19 controlled by the position of the plunger 4 to provide an electrical output voltage varying with that position and supplied to the mechanism box 15 by conductor 20, so that the combined voltage is supplied to the servo amplifier 17. The reciprocatory motions of the plunger 4 are converted to rotational motion of the synchro-type transducer 19 through a sleeve on the shaft of the transducer with a helically-shaped slot along its length into which projects a pin on the upper end of the piston-rod 8a. In the mechanism box 15, the receiver synchro 50 rotates, through gearing and differentials 92 and 96, the rotor of a synchrotype transducer 75 the output voltage of which is developed across a rotary potentiometer whose wiper is connected to one side of the rotor of transducer 19 so that an appropriate portion of the voltage of transducer 75 is compared with that of transducer 19 and the difference voltage supplied to the amplifier 17. A second potentiometer provides additional excitation voltage. To simulate the type of cam normally used to control the plunger 4, the speed of the rotor of transducer 75 is varied by an approximately harmonic motion device 100a, 100b, 103 ... 109, driven from differential 92, the link 109 being connected to shaft 110 which forms one input to differential 96, the other input being from synchro-receiver 50, so that the drive from differential 96 to the transducer 75 represents the sum of the two inputs. Control of the amplitude of the harmonic oscillations of shaft 110 is provided by a knob 134 on shaft 133 to vary the angle between links 100a and 100b. To provide for adjustment of the timing of the plunger movement with respect to the movement of the shears 6-6, a control knob 121 on shaft 120 controls a further differential 91 driven from synchro receiver 50 and the output of which is supplied to the transducer 75 and the shaft 89 which controls operation of the shears 6-6. A further control knob 153 adjusts the position of synchro receiver 50 with respect to its mounting 85 to control the timing of the shear operation with respect to the operation of the forming mechanism 11. Control knob 142 through worm 141 and gear 140 controls relative angular positions of stator and rotor of transducer 75 to change the phase relation between the modulating motion and fundamental function. The two potentiometers are adjustable from control knobs 155 and 160 to adjust the strokes of the plunger and the "plunger height". In a modification of the mechanism box 15, the drive from the synchro receiver 50 to the transducer 75 is effected through an actual cam instead of the differentials 92 and 96, the cam being changed to alter the pattern of motion of the plunger 4.