ing planetary gear carriers for wind turbines, brake disks for commercial vehicles, or railway wheels, the demands made on the different production planners are very similar. Component quality must pass the severest tests, as all these parts will be exposed to extreme stresses when in service. Take a wind turbine, for example. It
is in service for an average of 120,000 hours and exposed to varying wind and weather conditions for 20 years or more. But its production must be highly flex- ible, despite relatively small numbers; and the production tools used ought to be adaptable for the machining of other components, without involving complex conversion work.
Machining Workpieces of up to 1.5 t Meeting the requirements of heavy-
duty machining with the help of a compact production system concept is no matter of course. Many companies use complex, interlinked, multistage processes to machine large work- pieces. Te VLC production centers from EMAG, however, rely on a totally different approach. Not only do the machines load themselves with the help of a pick-up spindle, but the machin- ing area accommodates all necessary machining processes—turning, drilling, milling, grinding, gear hobbing—on the same machine, and in a single setup. To achieve this, the production center is equipped with an automatic turn- ing tool receptor, milling spindle and toolchanger. Te single setup ensures a high degree of dimensional accuracy and a constantly maintained, excellent surface finish. At the top of the range of heavy-duty
machining centers is the VLC 1200, presently the world’s largest pick-up machine. It handles workpieces of up to 1200-mm diameter and 1500 kg. “De- spite having to handle these enormous components, the production center dis- plays the same qualities as all the verti- cal pick-up machines from EMAG,” said
Markus Woitsch, business unit manager, Application Engineering. To be able to explain the success the
VLC machines are enjoying in heavy- duty machining circles it is important to take a closer look at the basic construc- tion of this machine series. Te spindle carrying the workpiece is positioned vertically above the tool, which allows the chips to fall unhindered into a con- veyor located below, from where they are transported out of the machining area. Tis prevents the hot chips from heating up the workpieces and contami- nating the spindle.
Workpieces of up to 1200-mm diameter and 1500 kg can be machined on a VLC vertically, in a single setup.
“Tis is a great advantage, especially
in a lightly-manned, fully automated, heavy-duty machining environment,” said Woitsch. Another benefit derived from this
kind of heavy-duty machining is the quality control. Te raw materials used for this type of workpiece represent a heavy investment. Mistakes made during the production process result in high, avoidable costs. Te VLC series’ designers came up with a very sophisti- cated response to this challenge: a probe with an accuracy of 2 μm measures and checks the workpieces between machin- ing operations.
Application Examples Some of the advantages of the VLC as
used in various areas of manufacturing can be seen in these two applications: • One manufacturer uses a VLC 500 to produce components for the nacelle of a wind turbine. Batch sizes are approximately 120 per week. Production of the six different components calls for up to 12 different tools. “Tese numbers already show the flex- ibility of the machine. Without time-consuming modifications,
the VLC 500 is capable of ma- chining a number of totally dif- ferent constituent components,” said Woitsch. “Furthermore, the wind turbine specification calls for a particularly high degree of component quality, which we can guarantee with the VLC.”
• A VLC 1200 that complete- machines railway wheels and brake disks has to carry a weight of 3 t—including the chuck—at the spindle nose. Te production center also incorporates a chain magazine for 36 tools. High feed rates in the X and Z axes of the workspindle and a maximum torque of 13,000 N•m make for short throughput times. “Tis enormous amount of power, the integral pick-up automation and the intelligent combination of diverse machining applications in a single setup have enabled us to reduce throughput times by up to 80%, compared to previously used processes,” said Woitsch.
Setting Effort and Process Control Te advantages of a multifunction
concept also have a positive effect on the production of components for construc- tion machinery, HGVs and agricultural machines. Compared to the classical shop floor production of such compo- nents on three or four machines, the work load is greatly reduced when one has only the VLC to set up. “It makes a great difference whether I have to set up three or four machines for the produc- tion of 10 components, or just one,” explained Woitsch. Another telling feature of the VLC
series is their modular design. Every machine is configured to suit the user’s particular production requirements. Te possibilities are many: one or two turrets, the integration of grinding and hard-machining processes and the dif- ferent workpiece capacities of the VLC 500, VLC 800 and VLC 1200.
Energy Manufacturing 2013 35
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