Method for manufacturing strain wave gear device and strain wave gear device

A method for manufacturing a strain wave gear device, the method comprising steps of:

• measuring a dimension of an internal gear;
• measuring a dimension of an external gear, the external gear to be placed inside the internal gear in a radial direction, the external gear being configured to mesh with the internal gear, the external gear being flexible;
• measuring a dimension of a bearing, the bearing to be placed inside the external gear in the radial direction, the bearing being flexible;
• and
• machining an elliptical cam, the elliptical cam to be placed inside the bearing in the radial direction, the elliptical cam being configured to flex the external gear in a non-circular manner,
• wherein the elliptical cam is made based on the measured dimensions of the internal gear, external gear and bearing such that the internal and external gears mesh with each other at a constant position,
• wherein, in the step of machining the elliptical cam, one of a plurality of ellipse cutting programs is selected and used,
• wherein a between pin diameter of the internal gear is measured,
• wherein an over pin diameter of the external gear is measured, and
• wherein, in the step of machining the elliptical cam, a major axis dimension of the elliptical cam is determined based on the measured dimensions, and a machining dimension of the elliptical cam is determined such that a length of a circumference of the elliptical cam remains unchanged.

A strain wave gear device comprising:

• an internal gear;
• an external gear placed inside the internal gear in a radial direction, the external gear meshing with the internal gear, the external gear being flexible;
• a bearing placed inside the external gear in the radial direction, the bearing being flexible;
• and
• an elliptical cam placed inside the bearing in the radial direction, the elliptical cam being configured to flex the external gear in a non-circular manner,
• wherein the elliptical cam is made based on measured dimensions of the internal gear, external gear and bearing such that the internal and external gears mesh with each other at a constant position.