GB967225A - Improvements in or relating to a plunger type glass feeding apparatus - Google Patents

Abstract

<PICT:0967225/C1/1> A glass feeding apparatus of the reciprocating plunger type in which upward movement of the plunger is effected primarily by mechanical means including a rotary cam while downward movement of the plunger is caused by gravity, includes a control valve operatively connected with a fluid-actuated unit, and a slipping clutch to move a two-position control member of the control valve to one of its two positions upon initial downward movement of the plunger to energize the fluid-actuated unit in a direction to assist downward movement of the plunger. A plunger 10 is mounted by clamping means 22 to one end of an arm 12 which is adjustably supported on a bracket 14 for vertical reciprocation therewith relative to a bowl 16 containing molten glass. The bracket 14 is rigidly connected to a shaft 24 which is vertically reciprocable through bushings 26, 28 which form part of the fixed frame F of the apparatus. A cam 30 driven in an anti-clockwise direction acts on a cam follower comprising a roller 34 supported on a pivoted arm 36 and further supported by a pair of straps 38. Extensions 40 of the straps 38 journal a roller 42 engaging the upper arcuate surface 44 of a lever 46 pivotally mounted at 48 to the frame F. The lever 46 includes a portion 50 with a bifurcated end which straddles the shaft 24 and is pivotally connected to a pair of links 52 pivoted on a pin 54 secured in the shaft 24. Depression of the cam following roller 34 causes the shaft 24 and hence the plunger 10 to be raised, the stroke of the plunger being dependent on the distance between the lever pivot axis 48 and the roller axis 42 which distance is adjustable by means of a screw 56. A magnetic hysteresis brake type of slipping clutch 72 is mounted on the arm 14 and has an armature the rotation of which together with its shaft 78 and a pinion 80 is normally retarded. Upon initial downward movement of the plunger 10 and hence also the arm 14, the retarded pinion 80 causes a rack 70 with an associated two position valve within a valve housing 66 to be depressed until the valve is in its lowermost position when the clutch 72 slips and the pinion 80 rotates and rides down the rack 70. In its lowermost position the valve applies fluid pressure to the top of a piston of a fluid actuated unit 58 and exhausts from the bottom end through conduits 62, 64 respectively. The piston, thus, through a rod extension 60, applies a force to the portion 50 of the lever 46 to assist the downward movement of the shaft 24 and hence the plunger 10. Upon initial upward movement of the plunger 10 the valve is raised to its uppermost position and provides upward pressure on the piston of the unit 58 so assisting the raising of the plunger 10. The upward force applied by the unit 58 is limited to less than the weight of the plunger 10, the bracket 14 and the associated vertically movable elements by a pressure limiting valve in line 64 to ensure that positive contact between the cam follower roller 34 and the cam 30 is maintained due to the force of gravity. A tension spring 82 returns the two position valve to its uppermost position whenever the apparatus is not being operated.