Patent GB-1216213-A (GB)
Title: Shears for molten glass feeders
IPC: C03B7/10
Filed: 1968-03-27
Abstract: 1,216,213. Glass feeder shear mechanism. EMHART CORP. 27 March, 1968 [24 April, 1967], No. 14705/68. Heading C1M. A gob shears for a molten glass feeder comprises a pair of opposed shear carriages 12, 16 movable toward and away from each other in a straight line between open and shearing positions, an hydraulic system for operating the carriages including a pair of reversible fluid motors 20, 24, each comprising a fixed part 29 or 30 and a movable part 20 or 24, the movable part of each motor being associated with a respective carriage for movement therewith, hydraulic line connections between said fluid motors including valve means 70 which is normally positioned to effect a series connection between said fluid motors so that operation of one fluid motor to move its associated carriage in one direction will cause the other fluid motor to move its associated carriage in the opposite direction, the system further including control valve means 58 to selectively move said carriages toward and to maintain them in open position and to move said carriages toward and to maintain them in gob shearing position, and means operable in timed relationship with the feeder for actuating said control valve means. The carriage 12 carries three shear blades 10 and is fixed at one end to its cylinder 20 movable against its piston 29, its other end having a dummy cylinder 18 guided over conduit 26. The other carriage 16 carries three shear blades 14 and at one end is attached to its movable cylinder 24 its other end having a dummy cylinder 22 guided over conduit 28. In the initial open position the shear carriages 12, 16 are fully retracted. The series valve 70 is set so that the conduit 32 of cylinder 20 is series connected with conduit 44 of cylinder 24. A control valve 58 is set so that no fluid can flow around the hydraulic circuit, the open lines from the cylinders 20, 24, and a synchronizing valve 68 and cut-off valve 62 being connected to a drain line 72. On receipt of a signal from the feeder timer mechanism the cut-off solenoid valve 62 is activated to open allowing fluid from pump 66 to flow into valve 58, moving its spool 104 to connect a conduit 54 with fluid at pump pressure. This also connects conduits 44 and 32 with the pump and so the fluid is allowed to flow out of orifices 34, 42 (Fig. 3) forcing the shears into gob shearing position. For ensuring a speedy operation the return flow of fluid through conduit 56 passes through valve 58 on its way to drain. In so doing it first moves against a freely movable piston 130 in valve 60 which gives a quick initial movement of the shears. When this piston has moved its full travel the fluid is then forced through a restricted orifice 108 which decelerates the rate of travel of the carriages. At the end of the shear stroke the valve 62 is de-energized, and is connected only to drain, fluid from pump enters valve 58 from line 100 to restore valve 58 to its initial position (see Fig. 1). This connects both lines 54 to drain and line 56 to pump and consequently the shear carriages move apart to their open position. The initial opening movement is rapid, but is slowed at the end of its travel by the orifice 108. To ensure synchronization of the two cylinders 20, 24 at the next stroke, when they have returned to their open position, a timed relay opens valve 68. This allows fluid to move spool 98 of series valve 70 to the position shown in Fig. 3. Here conduits 32 and 44 are no longer connected (i.e. cylinders 20, 24 no longer slaved) but conduit 32 is linked to conduit 26, and conduit 44 to conduit 28. Thus both cylinders 20, 24 are connected to drain and both are ensured as being hard against their respective pistons. The timed relay then closes valve 68 and the cycle recommences.