A machine tool for implementing machining with rotation, the machine tool includes a first rotor, an enclosure, a first rail, a second rail, and a coupler. The first rotor rotates about a rotational axis. The first rotor is surrounded with the enclosure. The first rail is disposed on the first rotor. The second rail is disposed on the enclosure so as to be brought into alignment with the first rail at a rotational position. The coupler moves along the first rail and the second rail. The coupler is to engage with the first rail and the second rail in a first state and to engage with the second rail without engaging with the first rail in a second state.

A double rotation indexing device includes two sets of rotation indexing units. Each of the rotation indexing units includes a main shaft and a drive transmission mechanism which includes a drive shaft, a disk-shaped driven member and a drive member. The drive shaft is supported on one end side via a bearing holder and is supported on an other end side via a radial bearing. The drive shafts of both rotation indexing units are connected by a connecting member. A drive motor is connected to an end portion of the drive shaft. The other end of the drive shaft in one rotation indexing unit is connected to the other end of the drive shaft in the other rotation indexing unit.

Improvements in a rotary screen printer that operates with a stepper motor for indexing the screen printer. The stepper motor provides a positive rotation and locating of the printing arms. The stepper motor can also have a controlled acceleration and deceleration speed while it indexes. The stepper motor further drives a spur gear to improve the drive ratio from the stepper motor to the indexing arms. The rotary screen printer uses pneumatic cylinders to operate the screening arms. Pneumatic cylinders are controllable for the downward force by adjusting pressure regulator(s) and the stroke by adjusting either limit switches or mechanical stops. Each station is interchangeable to accommodate the printing requirements of each job. Each station can be operated as a screen printing station, a drying station, a pad printer, and the number of stations can be changed by reprogramming the number of steps between each station stop.

A cam mechanism includes a base, a roller gear, and a camshaft. The roller gear and the camshaft are rotatably supported by the base. The roller gear has a turret and a plurality of cam followers mounted on the circumference of the turret. The camshaft has a shaft portion and a tapered rib having a first tapered rib and a second tapered rib. The first and second tapered ribs are each engaged with the cam followers. The first and second tapered ribs are configured to rotate relative to each other around a rotation axis of the shaft portion during adjustment of preload at which the first and second tapered ribs are pressed against the cam followers. After the adjustment of the preload, the second tapered rib is fixed to the shaft portion, and the first and second tapered ribs are prevented from rotating relatively.