Automation with multiple chaining

Four MILLTURN machines are linked with the help of a central automation system. By automatically changing the clamping jaws, tailstock centers and prism tools, the machines and the automation can be operated without setup.

A unique automation project revolves around central automation of four MILLTURN machines. This turnkey system has a whole range of special features. Automatic changeover of jaws, tailstock tips and prismatic tools in conjunction with a servomotor gripper for covering an extremely large product range allows for set-up-free operation of the machines and automation  solution. The system features a fully automatic gripper quick-change system and gripper warehouse. Servo grippers for workpieces up to max. 250 kg are used. Grippers for prismatic tools, tailstock tips as well as inner and outer jaws are also used. The 6-axis robot with 480 kg payload is mounted on a 7th axis. A range of grippers can be added to and removed from the  production process fully automatically. An integrated drip tray collects coolant and chips.

Set-up stations and workpiece measurement
By using two set-up stations for workpieces and tools, tools can be set up and new workpieces can be loaded and unloaded parallel to machining time. The two diameters at which the grippers hold the workpiece are determined via the two servo parallel grippers with an absolute position measuring system. These two values are compared with the nominal diameters stored  in the recipe. Two stationary laser light barriers determine the length of the workpieces and compare them with the recipe‘s nominal values. The workpieces‘ offset value from the robot zero point is also calculated.

Automatic tool change incl. cleaning and lubrication
A special chuck allows for fully automatic jaw change over (simultaneous replacement of the 3-part sets). The tailstock  tips can be changed automatically using a special gripper. Another special gripper is able to automatically change the long prismatic tools (up to 2,500 mm long and 250 kg in weight).
Before the new tool is inserted into the machine, the robot moves with the exposed guide to a special station in which the guide is blown off to clean it and then coated with oil. This creates the optimum conditions for a reliable handover process

Control technology
The system has three control levels:

  • KUKA KRC robot controller
  • Siemens PLC sequence control, safety technology
  • Host computer cell logic & recipe management

A cell host computer manages the CNC programs centrally and makes them available to the machine. Additional information, such as tool management and material flow planning, can optimise machine utilisation times as well as minimise downtimes and also enable autonomous production.

  • Set-up-free operation: Use of flexible servo gripper for the workpieces, 5-position gripper station
  • Warehouse serves as a „lung“: For 20 different sets of jaws, 12 different prismatic tools, 6 different tailstock tips and 8 different shafts (unfinished part, semi-finished part, finished part)
  • Host computer as the „brain“: The host computer compiles an optimised production program based on the available tools and workpieces so that the system can be operated autonomously overnight or at weekends.
  • Lower unit costs: Unmanned shifts or unmanned production at the weekend, faster changeover of tools and workpieces and thus greater machine utilisation
  • Flexibility: On the automation side, through the universal gripper for workpieces, on the machine-side through the 20-position jaw store for different shaft parts, 6 different tailstock tips and 12 special tools in the tool storage housing
  • Lower machine & tool costs: Central tool store (expensive tools can be used for all four machines), special tool changer for heavy/long tools is only needed once as the automation solution means it covers all machines.
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