Apparatus for clamping workpieces on machine tools

Apparatus for clamping workpieces on machine tools, comprising:

• at least one basic frame attachable to a machine tool for the machining of at least one workpiece;
• at least a first clamping assembly and at least a second clamping assembly associated with said basic frame in a movable manner from a release position to a clamping position of said workpiece, along a clamping stroke, and from said clamping position to said release position, along a release stroke;
• at least one fluid actuator, provided with a fixed portion associated with said basic frame and with a movable portion associated with said fixed portion in a sliding manner along a direction of sliding and connected to a drive assembly associated with said clamping assemblies, said fluid actuator comprising at least one chamber which can be fed with at least one pressurized fluid to simultaneously displace said clamping assemblies between said release position and said clamping position;
• wherein said drive assembly comprises at least one rocker element hinged to said first clamping assembly and to said second clamping assembly and associated in a rotatable manner with said movable portion, which comprises at least one curved thrust surface arranged in thrust contact against said rocker element during said clamping stroke, wherein said rocker element is rotatable on said curved thrust surface.