Licensing a patented design from R.F. Dray, Van Dorn Demag is now offering a nonreturn valve with a highly specialized design that it claims will help improve molding efficiency and produce more consistent parts. The CloserNRV?s uniqueness lies in its closing mechanism. Pullback is reportedly minimized, creating more consistent closure. Once the valve?s ring slides past the circumference groove, closure begins, with further sealing occurring when the ring contacts the rear seat. Van Dorn says this allows total closure and permits the valve to withstand injection pressures of up to 30,000 psi. Pressure drop during recovery is also reportedly reduced by the design since the valve closes in one-third the distance of standard nonreturn valves. This shortening of closing distance is said to equate to less variation in part weight. Van Dorn says the valve?s design lends itself to use with high-performance parts and engineering resins.
The CloserNRV is designed to meet a variety of customer applications and requirements: It comes in 32 sizes with standard and high-performance models that can work for standard, short-stroke, and high-flow environments. The valves can be ordered for existing presses through Van Dorn?s Molder Action Network or delivered with new Van Dorn machines.
Van Dorn Demag Corp., Strongsville, OH