Transfer mechanism for sheet material

Claim 1

A sheet material linear transfer and stacking apparatus comprising an overhead guide and support track positioned at an elevation well above the heads of workers on a factory floor or the like, a carriage mounted on said track and movable in opposite directions thereon toward and away from a source of sheets requiring transfering and stacking at a new location spaced from the source, a depending substantially vertical arm structure secured to the carriage and movable therewith along said track, a sheet gripping means carried by the lower end of the arm structure at an elevation to engage sheets at said source and transfer them to said new location, said sheet gripping means comprising a relatively stationary upper jaw fixedly secured to the arm structure substantially at right angles thereto and projecting forwardly thereof, and a lower cooperating vertically swingable jaw below the fixed jaw and pivotally secured to the arm structure, a first fluid-pressure operated cylinder unit on the arm structure having a connection with said vertically swingable lower jaw to shift the latter between open and closed positions with relation to the upper fixed jaw, a second fluidpressure operated cylinder unit mounted adjacent to and lengthwise of said overhead track and having a connection with said carriage to reciprocate the carriage on the track, a pair of solenoid valves operatively connected with said first and second named cylinder units to cyclically control the operation thereof, a pair of electrical limit switches on said overhead track and spaced apart longitudinally of the track and both having actuators in the path of movement of the carriage, said limit switches electrically connected with said solenoid valves in such a way that engagement of said carriage with the actuator of one limit switch while moving in one direction causes opening movement of said lower jaw by the first-named cylinder unit followed by a reversal of the direction of movement of said carriage on said track by the second cylinder unit in response to engagement of the carriage with the actuator of the second limit switch, and another switch mounted adjacent said source of sheets and electrically coupled with said solenoid valves in such a way that successive actuations of the last-named switch by successive sheets at said source produces closing of the lower jaw by the first cylinder unit and gripping of each sheet and substantially simultaneous retraction of said carriage from said source and toward said new location by said second cylinder unit.