Digital proportional cartridges for die-casting (Mar 09)
Die casting is an efficient and competitive process offering a broad range of light alloy products for automotive and toys industries. High dynamic digital proportional cartridge valves and advanced controllers allow die casting machines to perform high pressure injection of molten alloy, permitting complex shapes and accurate tolerances. The injection is the ‘core process’ of the die-casting press as it defines the final product quality. It is operated in speed/position and pressure closed loop by the digital proportional cartridge valves described in the following.
Digital proportional cartridges
Available from size 16 to 100 (conforming to ISO 7368) with high flow up to 10.000 l/min, the cartridge’s main poppet slides into a sleeve and it is piloted in closed loop by a servoproportional valve assembled on the cover. The integral digital electronics operates a double position closed loop control of the poppet and of the pilot spool through the integral LVDT transducers and perform high dynamics and low response times (15-30 ms from 0 to 100 per cent). Digital cartridges are available in two different executions:
- Two-way version – leak-free poppet type, normally closed to perform accurate flow metering controls in both directions.
- Three-way version – spool type for flow or pressure controls thanks to their 3 way configuration P-A or A-T.
The proportional cartridges are equipped with a digital driver designed with DSP technology, advanced algorithms and firmware. Atos’ PC software, window based, provides an user friendly intuitive approach. CANOpen or Profibus DP interfacing allows to program valves parameters, to check diagnostics and to manage the valve in real-time during the machine operation.
Rugged construction
High accelerations of inertial masses cause high mechanical shocks (up to 50 g) affecting proportional valves during the injection phase. The ‘rugged’ execution of proportional valves withstand the above mechanical stresses thanks to the structural enforcement of the most critical parts. In addition a shock absorber plate, fitted between driver shell and transducer housing, reduces of about 10 times the vibrations to electronics.
New digital proportional cartridges has been developed in cooperation with the main die-casting OEMs to improve the performances and reliability of the die-casting presses. Thousands of valves operating in the field witness the success of the digital cartridges in heavy-duty applications.
www.atos.com
High dynamic digital proportional cartridge valves.
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