Clamping device with mechanical servo mechanism

In a clamping device for a machine vise having a movable clamping slide member and a mechanical servo mechanism, comprising:

• a stationary housing means on said machine vise having an internally threaded opening therein;
• an axially movable plunger acting in particular on said movable clamping slide;
• a clamping sleeve encircling said servo mechanism, said clamping sleeve being coaxial with said plunger and having an external thread threadedly engaged in said internally threaded opening;
• a clamping member axially slidable in said clamping sleeve and non-rotatably connected thereto, one end of said clamping member being supported on said plunger;
• an abutment member axially movably supported and rotatably supported to a limited extent in said clamping sleeve, said movement of said abutment member being between a first end position defining an open position of the clamping slide member and a second end position defining a clamping position of the clamping slide member;
• an operating lever connected to and projecting from said clamping sleeve;
• plural studs disposed between said clamping member and said abutment member, said studs, when in said first end position of said abutment member, being inclined at an acute angle to an axis of said clamping sleeve and, when in said second end position of said abutment member, being arranged approximately parallel to said axis of said clamping sleeve;
• the improvement wherein
• (a) a compression spring abuts at one end against said plunger and at the other end against said housing means to effectively bias said clamping member toward said abutment member to clamp said studs therebetween;
• (b) an adjusting sleeve disposed adjacent an end of said clamping sleeve abutting said abutment member;
• (c) said external thread is provided directly on an outer circumference of said clamping sleeve, concentrically adjacent said clamping member and said studs;
• (d) said adjusting sleeve is axially displaceable relative to said clamping sleeve by means of a fine thread, and plural cup springs are disposed between a side of said abutment member remote from said studs and said adjusting sleeve;
• and
• (e) stop means is provided between said clamping sleeve and said housing for limiting a rotational movement of said clamping sleeve relative to said housing in said open position whereby a rotation of said plunger will effect an axial movement of said plunger and said clamping slide member, and cause said clamping slide member to eventually engage a workpiece, thereafter, movement of said operating lever and said clamping sleeve connected thereto will cause rotative movement of said abutment member from said first end position to said second end position to re-orient said studs and to effect an amplification of the force applied by said clamping sleeve member to said workpiece, the relative positional relation between said adjusting sleeve and said clamping sleeve controlling the magnitude of the amplification of the force applied by said clamping sleeve member to said workpiece.