This invention relates to a stroke enlarging mechanism of an arm and the like, and more particularly to a type thereof adapted to be used in a work removing device for a die-casting machine or a press.
In a technical field of, for instance, industrial robots and manipulators, it is frequently required that a chuck-hand thereof grasps and transports products or works from one position to another along a linear path, and such functions have been accomplished by an arm coupled to a piston operated by a hydraulic or pneumatic cylinder.
In the above described case, although there is no problem when the distance of the required movement of the arm is equal to or less than the stroke of the piston, a mechanism for enlarging or multiplying the stroke of the piston is required when the distance of the required movement is larger than the stroke of the piston.
A typical construction of a conventional stroke enlarging mechanism is shown in FIG. 1. In this mechanism, a pinion 14 is mounted to be freely rotatable at an end of a piston rod 12 movable in a cylinder 10, and a pair of movable racks 16 and 18 are disposed so that the pinion 14 engages with the racks 16 and 18 at an upper end and a lower end thereof, respectively. When the piston-rod 12 moves outwardly from the cylinder 10, the rack 16 is driven upward while the rack 18 is driven downward as viewed in FIG. 1. Although an enlargement of the stroke of the piston can be realized by the above described stroke enlarging mechanism, this mechanism requires a space substantially equal to the enlarged stroke, and therefore it has been difficult to use the mechanism in a narrow space such as a factory of a low ceiling height or where the vertical space therein is limited because of the presence of a hoist or a crane, where the mechanism is disposed vertically, and in a narrow space horizontally where the mechanism is disposed horizontally.