Patent GB-738246-A (GB)
Title: Improvements in or relating to method of and apparatus for striping glass
IPC: C03B23/24
Filed: 1953-10-22
Abstract: <PICT:0738246/III/1> <PICT:0738246/III/2> <PICT:0738246/III/3> <PICT:0738246/III/4> In the making of double-glazed units by welding together the edges of single glass sheets the heating of the sheets at the zones of junction being effected by passing a current through a stripe or stripes of conducting material applied to one of the sheets, the stripe is applied to the underside of the upper sheet by a rotating wheel the periphery of which is coated with the conducting material.  The underside of the lower sheet is similarly striped with a material which prevents adhesion between the sheet and its support during the welding operation.  The sheet 11, intended to be the top sheet, is brought under a vacuum chuck 37 by the roller conveyer 15, and is preceded on the conveyer by the bottom sheet 10 which is positioned under a vacuum chuck 38. The rollers are driven by a reversible motor 26 and an electromagnetic clutch 27 which is energized by control circuits as described below.  The leading edges of the sheets 10, 11 actuate switches 50, 51 which, in co-operation with a switch 52, initiate a circuit which disengages clutch 27 and also starts side-centring means 53 moving towards the sheets.  The clutch disengagement is timed to allow about 5 degrees of movement of the rollers 15 after the sheets have abutted against stops 40, 41 to ensure that good contact therewith is made.  The stop 40 is fixed, but the stop 41 is mounted on an arm pivoted on a rod 49 and is operated by a pneumatic cylinder 46 so that the stop is beneath the conveyer when the sheet 10 is passing over it, and is then projected up between the sheets.  The stop 41 is swung into position when switches 42, 43, 44 are in proper sequence, a solenoid valve 45 then being operated to admit air to the cylinder 46.  The side-centring means 53 comprise rubber buffers 54 on piston rods 56, and when the inward travel of the buffers, initiated by switches 50, 51, 52, has progressed to the predetermined extent, limit switches 61 are actuated to energize solenoid valve 45 to swing the stop 41 to inoperative position, the stop arm operating another switch to energize the solenoid valve 58 to admit air to the cylinders 57 to return the side-centring means to their original positions.  The sheets are now in correct position for engagement by the vacuum chucks 37, 38 which raise them for striping.  The chucks are carried on piston rods in pneumatic cylinders 66, 67 and, when inoperative, are kept in raised position by air pressure beneath the pistons.  The completion of the side-centring operation closes a circuit which opens solenoid valves to vent both the tops and bottoms of the cylinders 66, 67 to atmosphere, so that the pistons and chucks descend until the sheets are reached and stops, movable with the chucks, contact limit switches to initiate a circuit to close the solenoid valves and end the venting to atmosphere.  The limit switches also set up a circuit which energizes a solenoid valve for the application of vacuum through pipes 110 to the chucks. When a vacuum of about 24 to 26 inches of water is applied to the chucks, a vacuum-operated switch actuates the thermostatic valves to admit air pressure beneath the pistons and to vent the cylinders at the tops of the pistons, whereby the chucks rise with the sheets attached thereto.  The sheets are now in position for application of the stripes by means mounted on a carriage 140 which is reciprocable horizontally and transversely to and above the conveyer 15.  The stripe-applying means each consists of a wheel 155 driven by an independent motor 156 which is carried by a platform 157 pivotally and slidably connected by lugs 158 to a rod 146 rigid with the carriage.  The pivoting movement is limited and sliding along the rod 146 is prevented, when adjustment of the spacing of the wheels has been effected, by a split collar member 160 having a screw stop which engages one side of the platform 157 and a spring-urged member 170 which engeges the other side, to apply the wheel 155 to the glass sheet with a slight pressure. The wheel dips into a striping solution container 180.  The carriage is reciprocated by a chain driven through an electromagnetic clutch by a reversible motor 212.  The direction of rotation of the striping wheels is such that the peripheries, at the points of contact with the sheets, move against the direction of linear movement, the peripheral speed of the wheels being greater than the linear speed.  The traverse of the carriage is effected by the clutch becoming energized by limit switches actuated by the chucks as they reach their top positions, and when a complete inward movement of the carriage is ending, two limit switches are contacted, one of which disengages the clutch and energizes a solenoid valve to effect a 90-degree rotation of the chucks and the other is effective to control selected motors 156 according to whether square or rectangular sheets are being striped.  The carriage carries two pairs of stripe-applying rollers 155 for each sheet of glass, the roller units 125, 135 being used if square sheets are being striped and the roller units 120, 130 being used additionally if the sheets are rectangular. The indexing of the chucks is effected pneumatically by a cylinder 224 and a piston rod 225 connected to the vacuum heads at 226, p  236.  Alternatively a separate cylinder 224 may be used for each chuck.  A lug on the piston rod 225 actuates limit switches, when the chucks have been indexed to cause the motors 156 to start in the reverse direction and to actuate the electromagnetic clutch to cause the carriage 140 to move back to its original position, stripes being applied to the sheets during the movement.  Limit switches are then contacted to cause the chucks to return to their original positions.  The charging car 270 is then moved under the chucks to receive therefrom the sheets 10, 11 on graphite knobs 284, the descent of the chucks to the car and the release of the vacuum being controlled by limit switches actuated by the movements of the car.