High Torque Servomotors for the Multi-spindle Lathe

AKM servomotors from Kollmorgen have been selected for the MS40C-8 CNC multi-spindle lathe from INDEX-Werke used both in the production of high quantities of precision parts and – due to their shorter set-up times – for smaller batches. The DRIVE-CLiQ connection allows servo motors to be adapted to the machine automation technology without time-consuming adjustments.

di Sandra Becker

MS40C-8 is the name given to an eight-spindle metal processing machine from German manufacturer INDEX-Werke for fully-automated production of complex components. Yet with double 4-spindle machining, the same machine is also available for cost-effective production of simple parts with double the output quantity.
The CNC multi-spindle machine produced in INDEX Deizisau facilities, near Esslingen, and driven by Kollmorgen servo technology, is seen as a true all-around solution in machining technology. The solution from INDEX is used both in the production of high quantities of precision parts and – due to their shorter set-up times – for smaller batches.

Eight motors spindles allow highly complex components to be machined
Multi-spindle machines are mostly used for parts such as injection pump components, valve needles, small gears or injector nozzles, all featuring accuracy levels within tolerance grade IT5. The centerpiece of the INDEX MS40C-8 multi-spindle automatic lathe is the compact spindle drum with eight fluid-cooled motor spindles using synchronized technology. These can reach speeds of up to 7,000 rpm with 24 kW of power and torques of up to 57 Nm. They feature infinitely variable speed control, high torques, and a compact design; and they require no maintenance. As a result of the increased number of main spindles and tool carriers, the MS40C-8 is also completely capable of in a single operation. There are also two pivoting synchronous spindles available, each able to work on up to seven rear-end machining tools, with four of these capable of being powered. The capacity for two rear-end machining tools to work on the workpiece at the same time is a new feature.

Continuous programming of spindle parameters
In all cases, the optimum speed and feed rate can be programmed for each spindle location and each cutting edge, and these can even be modified during the cutting process. The eight fluid-cooled motor spindles integrated in the spindle drum are infinitely variable, require no maintenance, and are driven with synchronous motors. The Kollmorgen AKM permanent magnet servomotors are installed in the cross slides. The synchronous machines in the INDEX systems also include the added benefit of high-quality control mechanisms and high torque density. The optimum power-to-volume ratio allows INDEX to work with smaller drives during the design process. Careful use of space is a particular benefit in confined work areas.

The high torque density enables compact designs
INDEX uses the Kollmorgen motors in part as positioning axes for the tools. The high-power density enables compact designs that take up less space when installed in the work area. The very good torque density of the AKM synchronous servomotors allows INDEX to convert the rotation movement of the motors into a linear motion without gears. The ball bearing spindles are connected directly to the motor shaft for this. The lack of gears means there are fewer moving parts, and improves the zero backlash and the overall stiffness of the drive.

Servomotors can be installed directly into the machining process
INDEX uses these features without having to clad the AKM synchronous servomotors in the work area beforehand – a time-consuming process. The AKM servomotors are specially designed to meet the requirements provided by INDEX and undergo extensive IP67 testing in the aim of keeping the work area as orderly as possible. The motors can be installed directly with the cross slides thanks to their special washdown exterior paint. This allows the units to be introduced directly into the machining process without impairing their service life. In order to protect the connecting cables from constant bombardment from metal chips Kollmorgen placed these in a metal cable duct specifically designed to meet INDEX’s needs. Today, this co-engineering initiative securely protects the servo drive, together with its wiring, from the metal chips that fly around and from the cutting oil that gets into the work area at pressures up to 80 bar. Integration standards are maintained even though the AKM synchronous servo motors from Kollmorgen are perfectly aligned towards the usage conditions in the INDEX CNC multi-spindle machines as a result of the co-engineering project. The motors need to fit seamlessly into the machine’s overall automation mechanism without time-consuming adjustments. The connection via DRIVE-CLiQ is an example of this. This allows the performance benefits of the AKM synchronous servo motors to be used for CNC applications directly with Sinumerik control units in metal machining, without needing to compromise on the connection technology.

In conclusion
Fitting with DRIVE-CLiQ is an example of how the synchronous servo motors from KOLLMORGEN can adapt to the diversity of CNC and automation technology – particularly for metal machining. This lets machine constructors use drives outside of closed systems, without losing any of the convenience or performance benefits. Very simple adjustments can also be carried out outside of mass production, opening up whole new avenues for INDEX – from gearless use of the AKM servo motors to protection for the connecting cable using a specially developed cable duct. l