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  تکنولوژی جدید در طراحی mixing head  [1387/4/8]

تکنولوژی جدید در طراحی mixing head

 


        RAMPF announces a new two-component mixing head, the MS–C dynamic mixing system featuring a patented, servo-driven ceramic valve system.  MS-C simplifies two-component meter, mix, and dispensing operations by reducing downtime for cleaning and maintenance.  This is accomplished by a new revolutionary, patented design featuring a ceramic valve disk system that has no dynamic seals.  Maintenance time is reduced because the ceramic valves do not require the frequent cleaning and rebuilding that needle valves need.  The ceramic valve and mixing sections are separate allowing the mixing chamber and mixer to drop down with a quick coupler for a rapid change.  Recirculation of the components through the mix head keeps the materials consistent from shot to shot.   Temperature control systems are available that stabilize the materials regardless of ambient conditions. 

The process begins with gear pumps precisely metering the resin and catalyst entering the mixing head assuring the correct mix ratio is held.  The MS-C servo motor rotates the valve disks to the proper position aligning the valve openings.  The servo also turns the mixer up to 6000 rpm to energize the materials and thoroughly blend them.  The shutoff valve is opened and the shot is made.  The RAMPF MS-C is capable of dispensing 2 grams per second up to 120 grams per second and mixes two to three components at viscosities from 50 to 200,000 cps.   A rinsing system of either solvent or high-pressure water automatically flushes the mixing chamber. 

RAMPF MS-C mixing system is more robust with less dynamic seals, wear items, and required spare parts.  There was a time when the carburetor was the state-of-the-art device to meter and mix air and gasoline.  It worked OK but was no fun to work on.  Multiple adjusting screws, floats and vacuum hoses kept even seasoned mechanics guessing.  Once fuel injection came along, the carburetor was no more.  Fuel injection doesn’t require all the adjustments and maintenance and it works bet-ter.  The analogy is not perfect but the landscape has definitely changed when dis-cussing two-component meter, mix and dispense systems.  Older, complex mix head designs cause a preventative maintenance schedule that if done, the systems work but increasingly, maintenance is neglected and problems result.  When the carburetor had a problem, there was immediate feedback, a missing engine, loss of power and maybe a hearty backfire.  When a resin dispensing system has a problem, it is not immediately noticed until hundreds of bad parts are produced.  

Two-component reactive materials, such as polyurethane, silicone or epoxy consist of a resin and a catalyst.  The materials must be metered to the proper mix ratio, mixed and dispensed.  Some materials, such as polyurethane and silicone foams, require dynamic mixing, blending the two components using a high speed mixer.  As the materials are continually metered and mixed, the system must be capable of maintaining an accurate mix ratio while dispensing multiple shots. 

RAMPF MS-C dynamic mixing head solves many problems associated with process-ing reactive resins:

•Internal ceramic valve system that does not require frequent inspection, maintenance or cleaning

•High output rates to 120 grams per second – also precise dispensing down to 2 g/sec.

•Accurate mix ratios, consistently held

•Precise nucleation levels monitored by RAMPF nucleation controller

•Clean, compact design

•Very few parts

•One servo motor for the mixer and valve system



What has changed? 

RAMPF MS-C replaces the needle valves used in a conventional dynamic mix head with the internal ceramic valve system. Older mix heads require one valve for the resin, another valve for the catalyst and valves for air and cleaning solvents.  These valves have to be cleaned and maintained to operate properly.  Should either material valve become restricted, the mixing ratios can become incorrect.  Preventive maintenance on the valves consists of frequent cleaning of the valve tip and valve rebuilding as dynamic seals are wear items.   When this maintenance is neglected, the mix ratio can change and scrap parts result.  Older mix head designs may be extraordinarily complex.  Some dynamic, two-component mix heads may have as many as 360 parts and one material valve alone consisting of 100 parts.  These older designs are difficult to maintain and service.  Material valves with this degree of complexity may have to be returned to the factory for rebuilding requiring back-up inventory of all valves.  Recognizing these maintenance hurdles, RAMPF designed a system for higher manufacturing efficiencies. 

 

 



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