Clamping assembly for a toolholder assembly
A clamping assembly includes a base member having an internal bore, a lock rod within the internal bore of the base member and moveable between an unlocked position and a locked position, the lock rod including a lock rod cam surface and a first bearing, a crank wheel having an axis of rotation and a third bearing, and a linkage including a second bearing comprising an elongated cavity formed in an outer surface, a fourth bearing and a cam surface at one end thereof.
1 . A clamping assembly, comprising:
a base member having an internal bore;
a lock rod within the internal bore of the base member and moveable between an unlocked position and a locked position, the lock rod including a lock rod cam surface and a first bearing, the lock rod cam surface formed with a radius;
a crank wheel having an axis of rotation and a third bearing; and
a linkage including a second bearing comprising an elongated cavity formed in an outer wall facing the lock rod, a fourth bearing, and a cam surface at one end thereof, the cam surface formed with a radius that is substantially identical to the radius of the lock rod cam surface to reduce Hertzian contact stress,
wherein the linkage is rotationally and translationally coupled to the lock rod by a first pin joint comprising a first pin received within the first bearing of the lock rod and at least partially received within the second bearing of the linkage,
wherein the linkage is rotationally coupled to the crank wheel by a second pin joint comprising a second pin received with the third bearing of the crank wheel and within the fourth bearing of the linkage,
wherein rotation of the crank wheel in a first direction causes the cam surface of the linkage to engage the lock rod cam surface to place the lock rod in the unlocked position, and
wherein rotation of the crank wheel in a second direction opposite to the first direction causes the first pin to engage the second bearing of the linkage to place the lock rod in the locked position.
2 . The clamping assembly of claim 1 , wherein the cam surface of the linkage does not engage the lock rod cam surface when the lock rod is in the locked position.
3 . The clamping assembly of claim 1 , wherein a gap exists between the first pin and the linkage when the lock rod is in the unlocked position.
4 . The clamping assembly of claim 1 , wherein the lock rod comprises a forward end and a rearward end.
5 . The clamping assembly of claim 4 , wherein an outer surface of the rearward end of the lock rod includes a substantially planar recess including a radial support wall for preventing the linkage from twisting and tipping during operation.
6 . The clamping assembly of claim 5 , wherein the lock rod includes an undercut formed between the cam surface and the radial support wall for providing clearance and stress relief.
7 . The clamping assembly of claim 1 , wherein the lock rod cam surface comprises a groove formed on an outer surface of the lock rod.
8 . The clamping assembly of claim 1 , wherein the linkage comprises a plurality of cam surfaces, and wherein each of the plurality of cam surfaces have different radii.
9 . The clamping assembly of claim 1 , wherein the elongated cavity comprises a blind hole.
10 . The clamping assembly of claim 1 , wherein the elongated cavity comprises a through hole.
11 . The clamping assembly of claim 1 , wherein the third bearing of the crank wheel is located at a position radially offset from the axis of rotation of the crank wheel.
12 . The clamping assembly of claim 1 , wherein the linkage includes a tapered or conical hole for cooperating with the second pin.
13 . The clamping assembly of claim 1 , wherein the lock rod cam surface comprises a curved surface formed by a groove.
14 . The clamping assembly of claim 1 , wherein rotation of the crank wheel in the second direction also causes a gap between the cam surface of the linkage and the lock rod cam surface.
15 . A method of changing a toolholder in a clamping assembly as recited in claim 1 , the method comprising:
rotationally and translationally coupling the linkage to the lock rod by a first pin joint comprising a first pin received within the first bearing of the lock rod and at least partially received within the second bearing of the linkage;
rotationally coupling the linkage to the crank wheel by a second pin joint comprising a second pin received with the third bearing of the crank wheel and within the fourth bearing of the linkage;
rotating the crank wheel in a first direction to cause the cam surface of the linkage to engage the lock rod cam surface to place the lock rod in the unlocked position to unclamp a first toolholder from the clamping assembly;
removing the first toolholder from the clamping assembly;
inserting a second toolholder into the clamping assembly; and
rotating the crank wheel in a second direction opposite to the first direction to cause the first pin to engage the second bearing of the linkage to place the lock rod in the locked position.
16 . A clamping assembly, comprising:
a base member having an internal bore;
a lock rod within the internal bore of the base member and moveable between an unlocked position and a locked position, the lock rod including a lock rod cam surface and a first bearing, the lock rod cam surface formed with a radius;
a crank wheel having an axis of rotation and a third bearing; and
a linkage including a second bearing comprising an elongated cavity formed in an outer wall facing the lock rod, a fourth bearing, and a cam surface at one end thereof, the cam surface formed with a radius that is substantially identical to the radius of the lock rod cam surface to reduce Hertzian contact stress,
wherein the linkage is rotationally and translationally coupled to the lock rod by a first pin joint comprising a first pin received within the first bearing of the lock rod and at least partially received within the second bearing of the linkage,
wherein the linkage is rotationally coupled to the crank wheel by a second pin joint comprising a second pin received with the third bearing of the crank wheel and within the fourth bearing of the linkage,
wherein rotation of the crank wheel in a first direction causes the linkage to move away from the first pin such that the first pin travels freely in the elongated cavity of the linkage, thereby allowing the linkage to move without pulling the lock rod until the linkage eventually contacts the lock rod cam surface and pushes the lock rod in the forward direction to place the lock rod in the unlocked position.
17 . The clamping assembly of claim 16 , wherein rotation of the crank wheel in a second direction opposite to the first direction causes the first pin to engage the second bearing of the linkage to place the lock rod in the locked position.