摘要:
Method and device (10) for mixing polyurethane—forming reactive chemical components; at least first and second chemical components (A, B) are introduced into a common pressure and feeding chamber, from where the chemical components are made to flow and co-injected through one or more narrow orifices (31) into a mixing chamber. During co-injection of the chemical components (A, B) a first mixing takes place into the jet strim, while a final intimate mixing is performed by impingement and collision into the mixing chamber (24) of the device; selectively actuable cleaning members (12, 29) eject the residual chemical material remaining into the common pressure and feeding chamber (15), and the mixing chamber (24) of the mixing device (10).
摘要:
A method and device (10) for mixing polyurethane-forming liquid chemical components for the production of polyurethane foams, in which positive use is made of the turbulency and swirling action caused by the injection of pressurized jets of chemical components, in order to provide a methodology tending to improve the mixing processes by impingement and by the turbulency induced by a pressure drop in conventional self-cleaning apparatuses.
摘要:
A high-pressure mixing apparatus for producing and discharging a composite material resulting from a reactive mixture of at least a first and a second chemical components and from a filler material. The apparatus includes a main body, provided with a discharge duct for the composite material, at least one high-pressure mixing chamber for the chemical components and a first cleaning member axially displaceable between a forward and a rearward position within the discharge duct. The apparatus also comprises a second cleaning member with a control device selectively actuable to sequentially move the first and the second cleaning member between the rearward position, in which the first cleaning member opens the discharge duct, and the forward position in which the facing annular surfaces of the discharge duct and the second cleaning member are mutually abutting to eject the residual reactive mixture and close the exit port of the mixing chamber.
摘要:
A method and apparatus for feeding a polyurethane mixture suitable to form a thermally insulating layer inside hollow bodies, such as hollow walls of a refrigerator cabinet, freezer, display counter or insulating panel. A polyurethane mixture resulting from chemically reactive components, supplied by a high-pressure mixing device, is injected into a cavity of a hollow body extending in a horizontal plain. The mixture is injected at a first flow-rate and a first injection speed, to be poured into a first deposition zone farthest from the injection point. Subsequently, the flow-rate and the injection speed of the polyurethane mixture are gradually reduced in a controlled manner, to be poured in successive deposition zones towards the injection point of the polyurethane mixture, along a distribution strip, allowing the injected mixture to spread out throughout the cavity of the hollow body along isometric expansion lines.
摘要:
A high-pressure mixing apparatus suitable for producing a composite material from a reactive mixture of at least a first and a second chemical components and from a filler material, including a main body conformed with a discharge duct for the composite material, a high-pressure mixing chamber for the chemical components, and a first cleaning member axially displaceable between a forward position and a rearward position within the discharge duct.
摘要:
The high-pressure mixing apparatus, for reactive chemical components, comprises a device for self-lubricating and scraping the outlet duct of the chemical mixture, and flushing out the scraped residues. The self-lubricating and scraping device comprises a delivery chamber for the lubricant material axially aligned and in fluid communication with the outlet duct; the lubricant delivery chamber is connected to a storage tank by a feeding and re-circulation circuit. The lubricant is sucked into the outlet duct and subsequently returned into the delivery chamber by a cleaning member in the form of a pumping piston sliding into the outlet duct, the pumping piston being provided with scraping rings for removing the reacted mixture adhered to the inner surface of the outlet duct.
摘要:
A high-pressure self-cleaning mixing apparatus adapted to mix at least first and second reactive polyurethane-forming components and feed the mixed components to a mold is disclosed. The apparatus includes at least a mixing chamber, first and second feed passages, first and second recycle passages, and a cleaning member having at least first and second longitudinally-extending recycle grooves spaced from each other. The cleaning member is movable between an open position in which the first feed passage radially feeds the first polyurethane-forming component to the mixing chamber and a closed position in which the first longitudinally-extending recycle groove communicates the first feed passage with the first recycle passage to recycle the first polyurethane-forming component instead of feeding the first polyurethane-forming component to the mixing chamber. The second feed passage may be communicated with a longitudinally-extending passage of the cleaning member to permit the second polyurethane-forming component to be fed into the mixing chamber along an axial direction of the mixing chamber. A valve member may be provided to prevent the flow of the second polyurethane-forming component to the mixing chamber by recycling the second polyurethane-forming component to the second recycle passage. Spacing between the first and second grooves seals the first feed and recycle passages from the second feed and recycle passages.
摘要:
A metering device for feeding liquids, in particular chemical components for the production of polyurethane mixtures in a high-pressure mixing head.The device comprises at least a first and a second metering unit of the type having a cylindrical chamber in which a plunger slides to displace a pre-established volume of liquid during its stroke and to feed it to the mixing head. The plunger is connected to a worm screw control device, in which the worm screw control devices of the metering units are interconnected by a mechanical drive actuated by a driving motor; one or more revolution variators can be disposed in the mechanical interconnecting transmission in order to vary the ratios between the speeds of the plungers and, therefore, the quantities metered in relation to the stochiometric ratios between the liquids to be mixed.
摘要:
An apparatus for mixing and ejecting fluid materials interacting with one another; said apparatus comprises at least a head having a mixing chamber with an outlet opening for the mixture at one end thereof, and having inlet ports, each of which connected to a supply line for a component. Each inlet port is connectable, through a distributing valve, with an orifice opening into the mixing chamber and respectively with an outlet port connected to a return line for a recycle at a first pressure rate of each component to a reservoir. A pin is reciprocable by a first double-acting cylinder to and away from the outlet opening of the mixing chamber; the distributing valves are operated by a second double-acting cylinder parallel connected to said first cylinder, one side of said second cylinder being directly connected to a pressure fluid source, and the other side being connected to pressure source by means of a shut off valve operable by the piston of the first cylinder at the end of its backward stroke. The return line for each of the components is further provided with a branched conduit having a valve defining a narrow orifice for a recycle at a higher pressure rate than the former.
摘要:
A process and a system for the continuous manufacture of polymeric foams. Reactive chemical components and additives comprising a low boiling blowing agent are mixed under pressure; the mixture is then frothed before chemical reaction takes place by feeding the mixture through a pressure equalizing and frothing device having a pressure-drop zone opening into a frothing cavity having an output aperture to discharge the froth onto a moving substrate.