Multifunction Okuma lathes with internal robot from NCMT

4 min read

MACH 2020 (Birmingham NEC, 20-24 April) will give NCMT the opportunity to show for the first time in the UK, the Okuma Spaceturn LB3000 EX II turn-milling centre. Equipped with the Japanese manufacturer's Armroid robotic arm, the Spaceturn LB3000 EX II is said to be the first in the world with such a feature integrated inside a CNC machine tool. At MACH, the machine will be configured for the automated handling of shaft-type parts.

Three different end-of-arm effector options are available for the robot, each one capable of performing different tasks. One is for blasting the cutting zone with air to improve chip management. Another provides additional support during the cutting process to prevent chatter. In combination with a workpiece stacker, the third effector automatically loads and unloads workpieces weighing up to 5 kg. All three are stored within the machine and are changed automatically by the robot.

While most conventional robotic systems require complex integration and special training for staff, Armroid needs neither. As the robot is part of the machine tool, separate system integration is unnecessary. Using Okuma's own OSP-P300A control, an operator enters the co-ordinates for the start and finish points. The robot then moves through its motions, with the cycle being generated automatically to avoid collisions. In addition to automated running under program control, manual operation is possible via a pulse handle that micro-positions the arm.

A longer and more powerful robotic arm, Armroid Type 2, will be integrated into an Okuma Multus B250II multi-tasking lathe for high-mix, small-batch billet work. This arm is capable of handling workpieces up to 10 kg and possesses a fourth end effector with a three-jaw workpiece hand.

There will be a second Multus machine on show, a U4000 2SW with an opposed spindle. The U4000 2SW will be set up to demonstrate power skiving operations, producing gears and splines to high accuracy on a generic 5-axis multi-tasking platform. This capability is made possible by robust machine construction and high levels of accuracy and repeatability, combined with special software.

The process is intended for producing gears from solid billets in large volumes using a dedicated skiving tool to sequentially rough and finish each type and size of gear. Even with deep tooth profiles, a Class 6 spur gear can be achieved due to the accurate synchronisation of tool and workpiece rotations. Other gear production techniques are also possible, including hobbing, shaping and spiral bevel milling.

The final turning machine on the stand will be a Genos L2000 with a gantry-type workpiece load/unload system. Here, the production of a flange-type component will be demonstrated.

Moving to Okuma machining centres, the MB-5000H Series 2 twin-pallet horizontal model will make its first UK appearance. The production of an aluminium engine casing on one pallet, and machining of a solid steel block on the other, will demonstrate the high output achievable.

This thermally stable machine offers greater rigidity, higher acceleration, shorter tool change, faster table indexing times and higher power than the previous Series 1 model. The machine’s cutting capabilities and high-speed automation reduce cycle times and increase productivity by up to 25%, states NCMT, while the 20% smaller footprint maximises the utilisation of shop-floor space.

Notably, the 15,000 rpm, 26 kW, direct-drive, internally-cooled spindle is fed with cutters from a 48-position disc-type tool magazine. Integrated cutter breakage detection allows for autonomously managed sister-tool replacement. Static turning tools can also be exchanged to enable the turning and profiling of bores and ODs using special turn-cutting software in the Okuma control that synchronises circular interpolation of the X and Y axes, with spindle feed motion in Z.

Offering travels of 760 mm in the X, Y and Z axes, rapid traverse at 60 m/min and a roller cam gear-driven B axis with 0.001° resolution, the MB-5000H is assisted by flood coolant to optimise chip management. In-process quality control can be integrated using a Renishaw RMP600 probe to inspect dimensions and feed the necessary offsets back to the control.

The Genos M460V-5AX vertical machining centre, with a working volume of 762 by 460 by 460 mm, will be on the stand producing a spiral bevel gear. Featuring a rotary table and 5-axis simultaneous control, the machine can process a variety of materials, from titanium to aluminium, without compromising dimensional accuracy, finish quality or productivity, says NCMT. The BT40 spindle is rated at 15,000 rpm/22 kW. A 32-position tool magazine is provided, while control is via the proprietary OSP-P300M.

A thermally-stable, double-column construction protects the machine’s structure from deformation, resulting in high machining performance. Okuma's Thermo-Friendly Concept is nevertheless included in the specification, applied to both the machine structure (TAS-C) and the spindle (TAS-S), based on feedback from temperature sensors to deliver high accuracy machining in a normal shop-floor environment. Tests have shown thermal deviation to be less than 10 micron over a 24-hour period, despite a variation in ambient temperature of as much as 8°C.

Features such as Okuma’s 5-axis tuning system, which fine-tunes the geometry of the machine for precision, and Okuma’s Absoscale linear encoders on the X, Y and Z axes, are all part of the standard package. So also are ServoNavi AI and ServoNavi SF, which automatically detect workpiece weight and adjust the machine's feed drives to achieve higher speed production of lighter components.

Machining Navi, an optional feature that minimises chatter by finding the best cutting conditions, employs a microphone to detect the onset of vibration and feed information back to the control. A change in spindle speed is then recommended to suppress any chatter.

A major theme of NCMT's Okuma stand at MACH will be the smart factory, exemplifying how Industry 4.0 applications can improve manufacturing processes by linking every machine tool across an entire manufacturing environment to Connect Plan. The solution allows complete visualisation of the factory and provides analytics for improved machine-tool utilisation.

Connect Plan achieves traceability by tying together the individual ID of a machined workpiece with the cutting data and gauging results for each production centre. The system is said to eliminate sources of errors, improving manufacturing quality, as well as reliability. In addition, by collecting process data, maintenance intervals can be accurately predicted and scheduled. Connect Plan even integrates machines from third-party providers. Real-time data, including the operational status of the machines, is accessible on PCs and mobile devices from any location.

Okuma has collaborated with other machine-tool builders, software companies and control manufacturers to create a universal machine tool interface, Umati, which enables machines and peripherals to connect to customer-specific IT ecosystems. Umati has been developed on the initiative of VDW (German Machine Tool Builders’ Association) and is based on the international interoperability standard OPC UA, making the integration of new machine tools into existing IT environments easy, secure and seamless.

Umati is becoming an open standard for machine-tool users worldwide. Okuma customers will be able to connect their machine tools without any modification, as the machine builder has developed a Umati interface for its proprietary OSP Windows-based open architecture control.

Higher levels of automation and more complex manufacturing make it increasingly difficult to predict and avoid errors. Here, Okuma’s 3D Virtual Monitor software can provide a 3D simulation of the entire manufacturing process. To ensure high accuracy, the solution relies on the exact specification of the Okuma production platform to be resident within the CNC system. With end-to-end simulation of the machining process and transfer operations, programming errors can be detected before actual machining starts, avoiding costly collisions and increasing safety.