Flexible Pallet Handling and Storage for
5-Axis Machining

The German machine tool manufacturer, Hermle, which specialises in supplying 5-axis vertical machining centres, has introduced an automatic handling and storage system for up to seven pallets of 500 mm diameter or 400 x 400 mm. Designated PW 160, it can be factory-fitted or retrofitted to the company's C 30 U and C 40 U machines and is available in the UK through sole agent, Geo Kingsbury Machine Tools, Gosport.

The system brings automation to the mould shop and complex component manufacturing environment, as pallets may be exchanged to and from a trunnion-mounted rotary table that provides fourth and fifth CNC axes in Hermle C-Series machines.

In its simplest form, the PW 160 handles three pallets using a rotating 2APC (twin automatic pallet changer) fitted with double grippers at each end. It travels in the Y-axis direction, sharing its time between the machining area and a fixturing station at the front of the machine. The design allows a component fixtured on a pallet to be introduced to the working area and production to start while the next component is still being set up, minimising idle time. Maximum permissible weight of the pallet, fixture and component combined is 160 kg per side.

Additional flexibility can be obtained by increasing storage within the system to seven pallets. An optional, 4-pallet storage carousel is positioned to the side of the 2APC unit, exchange being effected by 180 degree rotation parallel to the X-axis. Pallets with finished components and/or those awaiting machining may be parked in the carousel. Pallet management software is built into the machine control, either a Heidenhain iTNC 530 or a Siemens S 840D, both of which are Ethernet enabled for networking.

Constructed on a mineral casting that provides stability for rapid, accurate pallet exchange, the PW 160 is easy to install as it is a single-lift unit that does not need special foundations. The footprint of the pallet changer is compact at 2.5 m2 while that of the additional 4-pallet store is only 1.0 m2, so a full 7-pallet storage and handling system consumes only 3.5 m2 of factory space in front of a machine. Although the PW 160 is intended to facilitate automated running of a machining centre, the operator can nevertheless gain access to the working area from the side for manual intervention if necessary.

Hermle C 30 U and C 40 U machining centres are available in two variants, one with linear acceleration of 6 m/s2 to 45 m/min axis traverse and a chip-to-chip time of around 5.5 seconds, and a 'dynamic' version with uprated specifications of 10 m/s2, 60 m/min and 4.5 seconds respectively. Production capability is enhanced by 656 rpm rotational speed of the 360-degree rotary table (B-axis) and up to 25 rpm rotation of the trunnion (A-axis).

A 7-pallet PW 160 pallet storage and handling system fitted to a Hermle 5-axis vertical machining centre.

Although the PW 160 is intended for full automation, the operator can access the working area from the side if necessary.