Vibration-reduction mechanism for gear cutting machine
A vibration-reduction mechanism for a gear cutting machine is provided with a vibration-reduction mechanism that includes balancer shafts arranged in parallel to a crank shaft. The balancer shafts rotate synchronously with the crank shaft at the same speed as the speed of the crank shaft. One balancer shaft rotates in the opposite direction to the rotational direction of the crank shaft while the other balancer shaft rotates in the same direction as the rotational direction of the crank shaft. The vibration-reduction mechanism also includes: main balancer weights detachably attached onto the crank shaft; and sub balancer weights detachably attached onto the balancer shafts. The balancer weights are selected on the basis of a stroke width of the main shaft and on the basis of a lead corresponding to the helical angle to be formed in the workpiece W.
1. A vibration-reduction mechanism for a gear cutting machine that performs gear cutting on a gear blank with a rotary tool attached to a main shaft made to move reciprocally by a crank mechanism, by imparting to the main shaft a twisting motion corresponding to a helical angle to be formed in the gear blank, the vibration-reduction mechanism comprising:
a first balancer shaft and a second balancer shaft which are arranged in parallel to a crank shaft of the crank mechanism, and which rotate synchronously with the crank shaft at a same speed as a speed of the crank shaft, the first balancer shaft rotating in an opposite direction to a rotational direction of the crank shaft and the second balancer shaft rotating in a same direction as the rotational direction of the crank shaft;
main balancer weights detachably attached onto the crank shaft so as to reduce vibrations in an axial direction of the main shaft; and
sub balancer weights detachably attached onto the first and the second balancer shafts so as to reduce vibrations caused by translational unbalance between the main balancer weights in directions that are orthogonal to the axial direction of the main shaft, wherein
the main balancer weights and the sub balancer weights are selected on the basis of a stroke width of the main shaft and on the basis of the helical angle to be formed in the gear blank.
2. The vibration-reduction mechanism for a gear cutting machine according to claim 1 , wherein
the main balancer weights include:
a front-side balancer weight having a phase being offset by 180° from a phase of the main shaft eccentrically supported with respect to a center of the crank shaft; and
a rear-side balancer weight having a phase being offset by 180° from the phase of the front-side balancer weight so as to solve an imbalance caused by the offset, in an axial direction of the crank shaft, between the position of a mass center of the main shaft and the position of a mass center of the front-side balancer weight.
3. The vibration-reduction mechanism for a gear cutting machine according to claim 1 , wherein
the sub balancer weights are disposed, in the axial direction of the crank shaft, at same positions as the position of the mass center of the main shaft in the axial direction of the crank shaft.