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The changing direction of integrated machines

The changing direction of integrated machines

Mori Seiki's NT Series machines combine the built-in milling motors and symmetrical structures of the company's lathes with the Driven at the Center of Gravity (DCG) technology and boxinbox constructions of its machining centers for equal performance in milling and turning without compromising one for the other.

According to Mori Seiki, its NT Series machines are the first in the industry to include lower turrets with built-in motors.

NT Series machines feature new octagonal-shaped Y-axis rams with full-travel support.

Mori Seiki U.S.A. Inc. ( unveiled Nov. 3 what it is calling the future direction of integrated machining, demonstrated by its new NT Series of integrated mill-turn centers.

Thomas Dillon, president of Mori Seiki, said the "no-compromise" NT machines combine the built-in milling motors and symmetrical structures of his company's NL Series lathes with the Driven at the Center of Gravity (DCG) technology and box-in-box constructions of its NH Series machining centers. The combination, which was developed over a two-and-ahalf-year period, rests on a rigid flat-bed structure that the company says balances the impact of cutting forces to deliver equal performance in milling and turning without compromising one or the other.

Mori Seiki takes its box-in-box structure one step further in the NT Series by adding aY-axis ram with an octagonal shape. The ram rides on a V-shaped slideway, leaving its center of gravity inside the machine even when extended to its full Y-axis stroke. For the NT-4200 machine, that is about 16.5 inches (420 mm).

The ram provides a large machining area that lets shops cut the machine's maximum part diameter with its maximum diameter tool while reaching across workpiece faces in all directions.

A direct-drive motor, packed within the ram, powers the upper tool spindle. This B axis rotates ±120 degrees, clamps in 1-degree increments, rapids at 50 mpm and provides continuous 5-axis simultaneous cutting.

The upper spindle changes tools in one second for a four-second chip-tochip time. Instead of locating the automatic toolchanger (ATC) over the machine's headstock, Mori Seiki put it toward the back of the machine, and the upper spindle travels to it. Tool changes happen outside of the enclosed machining envelope.

A portal near the ATC opens, the upper spindle moves out to the ATC, unloads and loads a tool, travels back into the work envelope and the portal closes. This setup keeps chips and coolant from between the toolholder and spindle mounting surfaces. While the upper spindle is changing tools, cutting can continue using lower-turret tools. According to Mori Seiki, the NT Series' lower turrets feature the industry's first built-in motors. The design increases machining accuracy and cutting performance while minimizing heat generation and vibration, and eliminating transmission losses.

Lower turrets rapid at 30 mpm, as do the machines' second headstocks. These second headstocks are equal in cutting power and speed to the NT main headstocks.

For thermal stability and accurate machine movements, Mori Seiki circulates oil through jackets located around the spindles and along channels in headstocks on the NT machines. It cools all machine motors, ballscrew cores and motor brackets at the ballscrew ends to isolate heat generated by servo motors. In testing, the company ran the machine spindles from 0 rpm to 4,000 rpm and back down again over a long period, during which the X axis experienced less than 1.6 microns of thermal displacement with no compensation. Mori Seiki's Mapps III operator interface controls the NT Series machines. The system's 1.6-gHz Pentium CPU packs a 64-Mbyte video RAM that handles the machine's collision-avoidance system. This system senses where the machine is and the location of obstacles to create practically crash-proof machining. Other NT control features include canned cycles and expanded conversational programming.

There are 54 NT model variations built on NT 3000, 4000 and 5000 Series platforms. The 3000 Series offers 5-, 6- and 8-in. chucks, the 4000 8-, 10- and 12-in. ones, and the 5000 Series sports 15-in. chucks.

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