Conveyor system opens new opportunities

Bosch Rexroth has completed the first major UK application for its innovative new VarioFlow single strand conveyor system.

Bosch Rexroth has completed the first major UK application for its innovative new VarioFlow single strand conveyor system, in partnership with the world's leading supplier of CNC lathes and machining centres, Mazak.

The project centres on the development of a purpose-built conveyor system integrated with Mazak's best-selling IVS 200 vertical spindle lathes, creating an automated production cell around one CNC lathe or linking two separate machines, including an optional 180-degree turnover unit between work processes.

In addition to designing and commissioning the conveyor and associated pallet system, drive and control company Rexroth has provided aluminium structural framing, pneumatic control valves and automation components, a PLC unit for controlling material flow and workpiece rotation, and global after-sales support, through its synergistic technology and servicing operations in St Neots and Cirencester.

The new IVS 200 production cells will enable Mazak Europe to open up fresh business opportunities internationally, with world-class spares and maintenance backing from Rexroth.

VarioFlow, the latest chain-driven conveyor system from Rexroth, is designed for the transport of machined and automotive parts, electrical components, packaged goods, plastic mouldings, pharmaceuticals and other materials handling applications.

Offered in two chain widths, 65 and 90mm, its extremely stable chain design enables VarioFlow to achieve pulling strengths up to 1250N, these superior tensile forces providing for a high degree of system performance and facilitating longer conveyor sections with fewer drives; while the relatively closed chain surface allows even small components to be transported smoothly, in both horizontal and vertical planes.

The modular design of the system consists of a choice of standard and special-purpose chains, including ESD versions, aluminium conveyor profiles and side rails, multifunction product guide system, gearmotor end and curve-wheel drive units and returns, variable frequency converters, horizontal and vertical curve sections and wheels, leg sets and accessories.

VarioFlow offers the only conveyor profile with a centre bore and stiffeners, so it requires less leg and ceiling supports, and it is fully compatible with Rexroth's renowned aluminium framing support system.

The dedicated AutoCAD-based FMSsoft suite of software programs, which contains CAD drawings in industry-standard formats, provides structural layout guidance, load and driving power calculations, detailed dimensional designs and a complete bill of materials.

Headquartered in Nagoya, Japan, Mazak is an international company manufacturing advanced machine tools in the Far East, Europe and America.

Its European base and production facility is located in Worcester, where it handles all manufacturing operations from raw materials to finished product.

Its IVS 200 inverted vertical spindle CNC lathe is already a best seller across Europe, notable for a high spindle speed of 7000rev/min, fast 1.8s acceleration from 0-5000rev/min, extremely accurate positioning performance and workpiece loading/unloading that does not require an additional gantry robot, resulting in a compact installation footprint of just 3288 x 1235mm.

Multiple machines can be connected together for line production or two machines can be linked together for first and second work processes.

Recognising growing market potential across Europe, Mazak recently took the decision to develop fully integrated production cells at Worcester, built around its IVS 200 lathes and an automated material flow system, then invited tenders for the conveyor content.

Rexroth's Linear Motion and Assembly Technologies business unit, which operates out of Cirencester, has supplied Mazak with modular rail systems and guides over a number of years and put forward a cost-effective solution based on the new VarioFlow conveyor.

It gained the contract on the basis of highly competitive pricing, very short lead and development times, and the capacity to provide a complete conveyor solution, including PLC controls, together with service support and warranty across Europe.

Rexroth was also able to demonstrate VarioFlow working in a machine tool environment, at the Robert Bosch motor assembly line in Germany.

The Mazak conveyor solution is designed and assembled entirely with Rexroth products, including VarioFlow system, purpose-built workpiece pallets, pneumatic control valves, cylinders and automation components, self-contained PLC and extrusion frame build elements.

Configured using FMSsoft, the flexible VarioFlow conveyor has been readily adapted to the single and twin machine layouts, with provision for storage buffers, and retained the brand's characteristically small installation footprint.

There are two production cell layouts: IVS-GA1 with a single loop conveyor and six pallets for the one machine system and IVS-GA2 with a double loop, 12 pallet configuration for linking two machines, plus the option of a 180-degree turnover unit for rotating workpieces.

The purpose-made pallets, which cater for both new billet dimensions and the completed component, include tooling to allow the workpiece to be accurately located at the machine pick-up point and are spring-loaded so that it can be pushed accurately against the machine chuck, which performs the pick and place operations.

Used for the delivery of steel billets to an IVS 200 CNC lathe and return of the machined parts, the L-shaped single conveyor system, with 90m wide chain, is controlled by a PLC that interfaces with the Mazak machine controller and powered by a 180-degree curve wheel drive with geared motor, at speeds up to 60m/min.

The system is fitted with four pneumatically operated stops at the operator load/unload, premachine load and machine load and unload positions, which have optical sensors that detect whether parts are present and interface with the machining centre, via the PLC.

With empty pallets held downstream by a pneumatic stop, one pallet at a time is loaded, which is then released by operator pushbutton and passes through a pre-stop position to a stop-and-locate device, ready to be picked up by the machine.

During machining, the empty pallet is released and continues to the unload position, where the machine deposits the finished component, and proceeds thence to the operator unload point.

In the case of the two machine cell, which features a VarioFlow system configured in a T-shaped double loop and nine pneumatic stops, once the pallet is released from the first machine unload position, it moves to the next IVS200 machine, where it follows a similar path, before continuing to the final operator unload point.

Where there is optional component rotation, a turnover unit stops and locates the part-machined component between processes, lifts it off the pallet and rotates it 180 degrees, before returning it to the pallet for the second machining operation.

The turnover unit and control valves are contributed by Rexroth's Pneumatics business unit, which also has its sales and service centre in Cirencester.

The turnover unit comprises three pneumatic modules that are assembled together in a three-axis handling device for reorientation of components: a Rexroth GPC high precision lift cylinder, which provides movement in the z-axis, a two-finger parallel action gripper, which secures the workpiece, and a side-mounted turntable, which fully rotates it for secondary machining.

A five-port Type V15 valve unit, with BUSdirect connectivity to the PLC, is used for controlling the turnover function, while Type 579 solenoid valves control the various stop positions, which are bespoke VarioFlow components incorporating pneumatic cylinders.

Overall system control and interfacing with the Mazak machining centres is performed by a compact 16-input/8-output CL151 programmable logic controller (PLC), which was supplied by Rexroth's Electric Drives and Controls business unit, also based in Cirencester.

Finally, service support and warranty coverage for all components is provided Europe-wide by Rexroth's Service operation, headquartered in St Neots.

Working cross-divisionally and with the main VarioFlow factory in Germany, Rexroth UK designed and produced the Mazak conveyor systems within just five weeks, to full customer specification.

The first production cells are working seamlessly, helping to build Mazak's presence in a new market sector, and Rexroth is already discussing further refinements, including the use of a conveyor "spring bed", to obviate the need for spring-loaded pallets, and the integration of a turboscara SR8 swivel arm robot, for automatically loading the pallets from stillage.

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