Patent GB-1439569-A (GB)
Title: Automatically controlled instrument systems
IPC: G06K15/22
Filed: 1974-03-29
Abstract: 1439569 Handling sheet material GERBER SCIENTIFIC INSTRUMENT CO 29 March 1974 [9 April 1973] 13998/74 Heading G3N In an instrument comprising a carriage 26 movable in the X direction and supporting a carriage 28 movable relative to it in the Y direction, the latter supporting a Z carriage supporting a pen, head or tool 18, operative upon sheet material 12 on a table 16, coupling means, Fig. 4, are attached to the carriage 26, and, by engaging the sheet material 12, and/or a conveyer movable with it, (120) Figs. 7-9 (not shown), enable the sheet to be positioned in the X direction with the same accuracy as member 18 is positioned in normal use relative to the then stationary sheet, the drive for carriage 26 being used to position the sheet. The coupling means may comprise, at each side of carriage 26, clamping jaws 70, 72 Fig. 4, of which jaw 70 may be rotatable through 90 degrees to engage the sheet, jaw 72 being mounted on a solenoid 78 which, when energized, is thrust down to clamp the sheet at about the level of the table top. Alternatively, Figs. 5, 6 (not shown), each coupling means may comprise a magnetically sensitive, endless, or spooled, belt (94) of flexible rubber containing a ferromagnetic powder and located in the table bed (30), a resiliently supported electromagnet (92), when energized, being attracted to the belt (94) to clamp the sheet. The belts, at each side of the sheet, may be adjustable laterally to accommodate different sheet widths. The belt (94) may be actively located in the bed, or tensioned between rollers. Electromagnet (92) may support pins (150), Fig. 10 (not shown) which penetrate the sheet, and run in grooves (154) during sheet positioning. Alternatively, Figs. 11, 12 (not shown), the coupling means may comprise a laterally extending hollow bar (160) with slots (172), and pins (162) which penetrate the sheet when actuators (166, 168) are energized, a slight pressure in chamber (44), and vacuum within the bar (160) ensuring that the sheet is subsequently lifted with the bar to be positioned. The sheet is lowered by application of vacuum in chamber (44) and slight pressure within bar (160), possibly with the actuation of members (166, 168). Bed 30 may be made of resilient foamed plastics, or bristled mat, either entirely, or in one or more laterally extending strips, into which the pins penetrate when the sheet is picked up by the bar (160). A vacuum box (44), Fig. 3 (not shown) is provided beneath the bed 30, apertures (42) ensuring that the sheet, which may be plotting paper, or fabric to be cut is held by the vacuum as the member 18 works. During sheet positioning, slight pressure in box (44) provides air cushioning for the sheet as it moves. Members (84), Fig. 2 (not shown), laterally position the sheet. In Fig. 7 (not shown), the bed (30) has longitudinal grooves (114), the conveyer belt (120) with integral projections (126) mating with holes (128) in the sheet being perforated to communicate the vacuum to the sheet. Motors 54, 56 on take-up reels 50, 52 for the sheet may be slaved to carriage drive 38 during positioning, to aid in moving the sheet. The instrument may be a numerically controlled plotting system, lines being plotted over a length greater than that of table 16, controller 14 processing punched or magnetic tape data, in which case member 18 is a plotting pen. Alternatively member 18 may be an optical, or a tracking or a cutting, head, or a drilling or fabric cutting tool. The coupling means may be pneumatically, hydraulically, or manually operated.