Biomedical Engineering Reference
In-Depth Information
Fig. 8.16 Stepping motor
Guides
Carriage
Lead Screw
Springs
Fig. 8.17 Design of carriage
diameter. For milling and drilling, the special gripper for the workpiece should be
installed on the carriage (7).
The design of the stepping motor is presented in Fig.
8.16
. It contains four coils
with cores made from soft steel, a brass plate, and a steel plate supporting the cores
of the coils and the shaft of the rotor. The rotor is made from permanent magnetic
material and is magnetized in the radial direction. The coil pairs are connected
crosswise about the center point, so the motor has four input contacts. The motor
makes four steps per revolution and can be forced to make eight half-steps. In our
experiments, the stepping motor was used in the mode of high-speed rotation. We
used gearboxes to decrease the rotation speed. The main advantage of this motor is
the simplicity of manufacture and assembly. In addition, this motor does not contain
details much smaller than the motor, which is very important for scaling down.
The guides for the carriages were made as round bars, which simplifies the
production, assembly, and scaling down of micromachine tools. The carriages
(Fig.
8.17
) were made as simple as possible, each containing a spring to eliminate
the spaces between the carriage and the guides. Such spaces could appear due to
variations of guide diameter and thermal expansion of the carriage.
