Patent GB-884182-A (GB)
Title: Improvements relating to window envelope machines
Inventor: FORBES HUGH MACLACHLAN
IPC: B31B19/00
Filed: 1957-04-17
Abstract: 884,182. Envelope making machines. CARLAW (ENGINEERS) Ltd., DAVAID. April 17, 1958 [April 17, 1957], No. 12543/57. Class 94(2). A machine for making window envelopes with transparent patches comprises feed rollers 31, 32, a cutter 30, 38 to which the patch material 36 is fed by the rollers 31, 32, a suction roller 39 which is connected through a valve 22 with a suction system and is arranged to seize the leading end of the material beyond the cutting station and carry a cut-off patch to a windowed envelope blank, and means for rotating the feed and suction rollers in such timed relationship that the ratio of the linear speed of the feed rollers to that of the suction roller is equal to the ratio of the patch size to the distance between corresponding points of successive blanks. The blanks are fed from a stack 10 by a known suction device to the first pairs of feed rollers 18, 19 and are gummed by a rotary gum roller 20 before being fed to the patch applying mechanisms 39, 23. The roller 23 rotates once for each machine cycle and the peripheral speed of the suction roller 39 is the same as that of the roller 20. The size of roller 39 is such that it makes two revolutions for each cycle. The cutter comprises a fixed knife 38 and a rotary knife 30 driven in timed relation to the roller 39. The knife 30 is fitted to a shaft 45 connected by a clutch 60, 61 and gearing 62, 63 to the suction roller 39. The feed rollers 31, 32 are geared to the knife shaft 45, the gear ratio being chosen to provide the required ratio between the linear speeds of the rollers and the suction roller 39 having regard to the size of patch required. The roller 39 has suction holes 40 connected by an axial conduit 41 to piping 42 and via valve 22 to a source of suction 43. The valve is mounted on the shaft 44 of the gumming roller 20 and includes parts 52, 51 connected to conduits 42, 43 respectively and the parts are connected by a rotary disc 50 having an arcuate slot 54 at the appropriate time in each cycle. The disc 50 rotates once to each machine cycle. A device for stopping the machine if no patch is present for sticking to a blank comprises a cylinder 70 having a piston 72 normally spring biased into a position where an electrical contact 74 on the piston makes contact with a fixed contact 76. These contacts are connected in series with a relay 80 and contacts 79 which are bridged once per cycle by a contact strip 77 on an insulated ring 78 rotating with the knife shaft 45. The cylinder 70 communicates with the conduit 42 so that when suction is applied to the latter the piston is drawn upwardly and contacts 74, 76 broken. It is during this time that the contacts 79 are bridged. If no patch is present the conduit 42 remains open to the atmosphere through the holes 40 so that no suction is applied to the piston 72 and the contacts 74, 76 remain closed. When contacts 79 are bridged the relay 80 is energised to stop the driving motor. Means, as described in Specification 884,183 may be provided for stopping the machine in the event of a failure of envelope blank feed.