Harmonic Drive
Machining Centre Pallet Changer
Hollow-shaft
Integrated output bearing
In order to allow machining centres to operate unattended for longer periods, there is a trend to increasing automation of workpiece handling. One example of this trend is the pallet changer shown in the drawing. This changer is used in a horizontal-spindle machining centre and transfers pallets carrying the workpiece from a loading station to the NC rotary table of the machining centre.
It consists of a cast-iron cube carrying 4 pallets, each of which carries a cubic fixture holding a number of individual workpieces. When fully loaded the pallet changer carries enough workpieces to allow the machining centre to operate unattended for several hours. The design shown is driven by an HFUC-2UH Unit combined with an AC servo motor. An interesting feature of this design is the orientation of the input shaft relative to the gear. The Wave Generator is mounted on an input shaft, which passes through the hollow centre of the output flange.
The input shaft is connected to the motor via a shaft coupling. This arrangement allows the output-side cross-roller bearing of the Unit to be mounted close to the line of the centre-of-gravity of the cast-iron cube. As a result, the tilting moment acting on the output bearing is minimised, ensuring a long, maintenance-free, operating life. This design solution is particularly compact and offers a high dynamic performance, so minimising idle time for the machining centre.
