It is a portal machine or moving crosshead in which the working plane is stationary and is therefore the spindle that moves freely in the three axes. This solution allows you to have on one side a very large field of work and the other to contain, with respect to the field work performed, the overall dimensions of the machine.
Since the size of the work area very large, the Y-axis has been realized according to the scheme of a “gantry axis electric”, ie there are provided two electric motors, two screws and two position transducers for the translation of such axis. This solution allows you to have a very rigid construction of the machine at the same time limiting the weight of moving parts.
Compared to the solution in classical portal made by us with our model M1015H (with which it shares the spindle), however, has the drawback of posing a production cost of such axis substantially higher.
Noteworthy is the fact that both the guides of the Y axis that the support of the two screws of translation of such axis were made directly on the work table having a considerable weight (over 3,500 Kg the only work table!). The movable cross despite being made in welded structure (steel), was constructed according to the technology that provides for the filling of such component polymer with low density and therefore both the side of the work table (made of cast iron) which from the side crosshead gets the maximum damping effect of the vibrations caused by the tool in its movement of material removal and this guarantees a long life of the tool in work.
Note that the two screws of the Y axis are not rotating, but that is the nut that rotates as directly mounted inside the rotor motor which will also have a hole for passing inside the screw axis of translation. The above in order to minimize the inertia of the rotating parts. Indeed, the inertia of any rotating screw, given the stroke of axis Y, would be particularly important.
These two screws are both pre-tensioned. The pre-tensioning allows you to have a torsional stiffness and axial four times higher compared to a pre-stressed screw.
In order not to introduce any element of thermal distortion, the two motors housed inside the Y-axis of the moving crosshead, are liquid cooled.
Concerning the construction of the X axis, to note the absence of the coupling between motor and screw. The motor axis, of our construction provides the rotor mount directly on the screw drive shaft and this guarantees a greater roundness of movement for this axis.
Ball bearing screw characteristics and translation axes guides
– X axes diameter: 40 mm
– X axes diameter: 40 mm – Two screws present
– X axes diameter: 32 mm
– Screw pitch X Y Z: 20 mm per revolution
– Material: hardened and ground steel with ceramic material nut balls
– Dimensions roller block size X Z axis: 25 mm
– Dimensions roller block size Y axis: 45 mm
Position transducer axes
For all three axes are used optical absolute scales