Drive mechanism for lifting units of workpiece handling systems

摘要

In a workpiece handling system with lifting units which are arranged in pairs and which are moved alternatingly from a first end position into a second end position and back, the driving of the lifting units is achieved by means of a reversible drive motor which drives the input shaft of a differential gear, the output shafts of which are in communication with the lifting units. Each output shaft can be stopped by a stop brake, so that upon activation of one brake the entire drive power is transmitted to the other lifting unit. The lifting units are provided with grip heads for gripping the workpieces, and in order to obtain an exact positioning of the grip heads a fixed stop is provided for each lifting unit in the lower end position. In order to avoid a mechanical overloading in this case, the stop brake of the lifting unit located in the upper end position is released when the other lifting unit reaches its lower end position. The remaining rotational energy of the drive motor can then slightly move the lifting unit located in the upper end position, without it being possible for excessive mechanical loads to occur.