Internal gear grinding machine
An internal gear grinding machine achieves space savings and reduction in size of a machine, as well as prevents the tools from being damaged even when an abnormal situation such as a blackout occurs, by a simplifying dressing operation. The internal gear grinding machine for grinding a workpiece (W) by synchronously rotating the workpiece (W) and a barrel-shaped threaded grinding wheel ( 17 ) in mesh with each other includes a dressing device ( 20 ) for dressing the threaded tool ( 17 ) by meshing the threaded grinding wheel ( 17 ) with a disk dresser ( 56 ). When dressing, the threaded grinding wheel ( 17 ) and the disc dresser ( 56 ) are operated in accordance with the helix angle and barrel shape of the threaded grinding wheel ( 17 ), and the brake mechanism ( 58 ) applies a braking force to a dresser turn drive motor ( 53 ) to enable the disc dresser ( 56 ) to be maintained at a turned position thereof.
1. An internal gear grinding machine for use in grinding a to-be-machined internal gear by synchronously rotating the to-be-machined internal gear and a barrel-shaped threaded tool in mesh with each other, the to-be-machined internal gear being rotatable about a work rotation axis, the barrel-shaped threaded tool being rotatable about a tool rotation axis having a predetermined crossed axes angle with respect to the work rotation axis, the internal gear grinding machine comprising:
dressing means for dressing the threaded tool with a disk-shaped dresser rotatable about a dresser rotation axis in accordance with a shape of the threaded tool,
the dressing means including:
dresser turning means for turning the dresser about a dresser pivot perpendicular to the dresser rotation axis; and
braking and maintaining means for applying a braking force to the dresser turning means, and maintaining the dresser at a turned position thereof,
the braking and maintaining means including:
a rotary shaft disposed coaxially with the dresser pivot and rotatably supported in a casing;
a disk-shaped rotary disk provided on the rotary shaft;
a fixing member provided in the casing and opposing the rotary disk;
an armature disposed between the rotary disk and the fixing member and supported to be slidable along the rotary shaft;
a brake disk disposed at a side opposite to the armature with respect to the rotary disk;
a spring member provided in the fixing member to bias the armature toward the rotary disk; and
a coil member provided in the fixing member to generate a magnetic force when being supplied with power and thereby attract the armature against a biasing force of the spring member.
2. The internal gear grinding machine according to claim 1 , wherein
the dresser turning means is a direct-drive motor comprising:
a rotor provided on the rotary shaft; and
a stator provided on the casing.
3. The internal gear grinding machine according to claim 1 , wherein the braking and maintaining means applies a braking force to the dresser turning means when power to the internal gear grinding machine is shut off.