Unit for grasping and clamping circular objects

A unit for grasping and clamping a generally circular shaped part at three points or regions of tangential contact forming, pairwise, angles greater than 90.degree., comprising:

• a) a central body having a longitudinal axis;
• b) a central push rod, having first and second opposite ends, mounted on said central body for movement along said longitudinal axis;
• c) first and second levers positioned symmetrically with respect to said axis, each of said levers including a clamping arm and an operating arm, each arm having a distal end and joined together at a junction point spaced from said distal end to form an angle between the arms;
• d) a support shaft connected to said central body for pivotally mounting each of said levers on the central body at said junction point of the clamping and operating arms for pivoting movement between a first open position and a second clamping position, with the distal ends of the clamping arms spaced closer to said axis in said clamping position than in said open position;
• e) first, second and third grasping and clamping elements mounted on said central body,
• 1) the first of said grasping and clamping elements lying on the longitudinal axis of said central body and connected to the first end of the central push rod, and
• 2) the second and third of said grasping and clamping elements being mounted symmetrically with respect to said axis, each at said distal end of one of the clamping arms of said levers;
• f) at least one clamping spring engaging against said push rod and producing a reaction force urging said push rod away from the central body in the direction of said axis;
• g) a first piston operatively connected to the second end of said push rod;
• h) at least one lever spring connected to each of said levers for producing a reaction force urging said levers toward said second clamping position, with each lever spring engaging the operating arm of each lever at a position that is intermediate said junction point and the distal end of said operating arm;
• i) an annular sleeve at least partially surrounding said push rod for sliding movement along said axis, said sleeve member having first and second opposite ends with a groove said first end pivotally connected to the distal end of the operating arm of each lever;
• j) a second piston operatively connected to the second end of said sleeve;
• k) means for urging said first piston in a direction opposing the reaction force of said clamping spring and said second piston in a direction opposing the reaction force of said lever springs;
• and
• l) the reaction force of the two lever springs applied to the levers being higher than the reaction force of said clamping spring applied to said push rod.

A unit for grasping and clamping a generally circular shaped part at three points or regions of tangential contact forming, pairwise, angles greater than 90.degree., comprising:

• a) a central body having a longitudinal axis;
• b) a central push rod, having first and second opposite ends, mounted on said central body for movement along said longitudinal axis;
• c) first and second levers positioned symmetrically with respect to said axis, each of said levers including a clamping arm and an operating arm, each arm having a distal end and joined together at a junction point spaced from said distal end to form an angle between the arms;
• d) means for pivotally mounting each of said levers on the central body at said junction point of the clamping and operating arms for pivoting movement between a first open position and a second clamping position, with the distal ends of the clamping arms spaced closer to said axis in said clamping position than in said open position;
• e) first, second and third grasping and clamping elements mounted on said central body,
• 1) the first of said grasping and clamping elements lying on the longitudinal axis of said central body and connected to the first end of the central push rod, and
• 2) the second and third of said grasping and clamping elements being mounted symmetrically with respect to said axis, each at said distal end of one of the clamping arms of said levers;
• f) at least one clamping spring engaging against said push rod and producing a reaction force urging said push rod away from the central body in the direction of said axis;
• g) a first piston operatively connected to the second end of said push rod;
• h) at least one lever spring connected to each of said levers for producing a reaction force urging said levers toward said second clamping position;
• i) each of said second and third grasping and clamping elements include a shoe member for bearing tangentially against said part, each of said shoe members being pivotally mounted at the distal and of one of said clamping arms;
• and
• j) a connecting rod connected to each of said shoe members, each of said rod members having opposite ends with one end pivotally connected to one of said shoe members and the other end pivotally connected to said central body for controlling the pivoting of said shoe member with respect to said clamping arm for all positions of said clamping arm.