A high-pressure mixing device adapted to form a polymeric mixture from the reaction of two or more reactive liquid components or resins, comprises a head-body provided with a mixing chamber having an inner cylindrical surface with inlet and outlet openings for injecting and recirculating reactive components; a duct for delivering the mixture, communicating with the mixing chamber; a valve body with recirculation longitudinal slots, sliding into the mixing chamber between a backward position in which it clears the inlet openings and enables to mix components, and an advanced position, in which the slots put inlet openings in communication with outlet openings for recirculating the reactive components; the delivery duct, of the self-cleaning type, is a single-piece tubular element, removably fastenedby means of fixing membersand can be inserted into a hole transversal to the mixing chamber passing through the head-body; the tubular element has an intermediate transversal hole aligned with the mixing chamber with a diameter greater than a diameter of the mixing chamber for compensating, while assembling, for possible inevitable errors of alignment and mutual positioning due to processing tolerances of the parts to be coupled and for avoiding protrusions of the walls of the transversal hole from forming inwardly of the mixing chamber of the head-body, protrusions that might interfere with the end the walls of the valve member during the movement in the hole passing through the thickness of the tubular element until the end of said hole leading into the delivery chamber and that extends the mixing chamber to the wall of the self-cleaning delivery duct. Between the tubular element and the pass-through hole in the head-body a gap is defined, i.e. a certain coupling tolerance with a clearance between the tubular element and the hole, enabling to insert and remove the tubular element into/from the pass-through hole. Sealing elements prevent the leakage of polymeric mixture and lubricant liquid in the aforesaid gap; analogously, between the surface of the cap and the second holeobtained in a opposite position with respect to the holea respective gap with clearance is defined where an elastic or elasto-plastic sealing is interposed; the valve member, in the advanced and penetrating position into the hole of the tubular element, is separated therefrom by a gap, with a sealing member interposed therebetween; the gap prevents the metal-on-metal contact on the front part of the valve element when it enters into the intermediate hole; generally, thanks to gaps, the assembly and coupling of respective components is eased, facilitating the centering and mutual angular posit

A method for obtaining and applying a sealing gasket element on a slide-valve sliding in a cavity of an apparatus for the recirculation and mixing of chemically reactive polymeric components, comprises the steps of: obtaining from an elastic-plastic material a precursor element of the seal element, with a grid structure having a reticular shape; positioning the precursor element around the slide-valve; exerting on the precursor element, through temporary clamping elements, a radial compression and contraction action to insert it and couple it to one or more housing seats provided on the slide-valve so as to obtain the seal element well coupled to the latter; progressively removing the clamping elements to sequentially release successive parts of the gasket element and gradually free the slide-valve to gradually introduce the parts of the slide-valvefreed in successionin the housing cavity allowing the sealing gasket element to gradually expand radially due to the elastic return by adhering tightly to the inner surface of the same housing cavity. The special equipment for fitting the sealing gasket element on the slide-valve and the so obtained recirculation and mixing apparatus is also described.

A nozzle unit for a reaction molding machine, comprising an inlet channel prepared for connection to a mixing head outlet and comprising a first dispensing nozzle, which is prepared for applying a reactive mixture and which is connected to the inlet channel in a first operating state, a second dispensing nozzle being present, which is connected to the inlet channel in a second operating state and which is likewise prepared for applying a reactive mixture. Further disclosed is a mixing head device for a reaction molding machine having the nozzle unit, to a reaction molding machine having the mixing head device, and to a method for producing a plastic part.

A device for mixing at high-pressure two or more reactive liquid components or resins includes a head-body provided with a mixing chamber with inlet and outlet openings for the injecting and recirculating reactive components; a single-piece tubular element, for delivering the mixture; a valve member with longitudinal recirculation slots; the tubular element is removably inserted into a pass-through hole of the head-body, having annular shoulder zone, separated and distant from the transversal hole; fixing elements removably lock the annular shoulder zone at the head-body for holding the tubular element in the aforesaid hole; a clearance gap between the tubular element and the pass-through hole of the head-body is provided such that the forces are exchanged through the annular shoulder zone; sealing and centering elements avoid leakages of polymeric mixture. Deformation-detecting elements detect the deformation conditions which the tubular element is subjected.

A melting device includes a container capable of melting a material supplied in a free-flowing state and storing the material in a liquid state. The container includes a first storage section for storing the material in the free-flowing state, a second storage section for storing the material in the liquid state, and a dividing section provided between the first storage section and the second storage section and configured to hold back the material, when the material is in a non-molten or free-flowing state and to allow passage of the material from the first storage section into the second storage section, when the material is in a molten or liquid state.

A cleaning piston for a mixing head of a reaction moulding machine includes a main part which has a cylindrical casing region, and a clearing part. The material and geometry of the clearing part are designed to remove residual material adhering to a channel of the mixing head. The clearing part is at least partly made of non-polar material.

A system for generating and dispensing plural component materials includes a controller operatively connected to dispense valves and return valves. The return valves are in respective open states to allow constituent materials to circulate back to a source and are in respective closed states to block circulation. The dispense valves are in respective open states to allow mixing of the constituent materials to form the plural component material and in respective closed states to prevent generation and dispense. The controller implements a delay between closing the return valves and opening the dispense valves to build pressure in the system prior to generating and dispensing the plural component material.

A mixing device includes a first feed opening for a first liquidpreferably gas-ladenplastics component, a second feed opening for a second liquid plastics component, and a discharge opening for discharging a mixture of the first and the second liquid plastics component. The mixing device has a rotating agitator for mixing the first and second liquid plastics components, and a gap remains between the agitator and the discharge opening. An adjustment device is provided which either varies the gap by way of a relative movement between discharge opening and agitator or varies the size of the discharge opening. A regulating device is connected in signal-transmitting fashion to a sensor for determining a pressure prevailing in the mixing device. The regulating device sets the gap, or the size of the discharge opening, by the adjustment device such that the pressure prevailing in the mixing device has a predetermined value.

A melting device includes a container capable of melting a material supplied in a free-flowing state and storing the material in a liquid state. The container includes a first storage section for storing the material in the free-flowing state, a second storage section for storing the material in the liquid state, and a dividing section provided between the first storage section and the second storage section and configured to hold back the material, when the material is in a non-molten or free-flowing state and to allow passage of the material from the first storage section into the second storage section, when the material is in a molten or liquid state.

A method for a system having a plurality of primary fluid sources and a fluid output with a common pump includes halting pumping of a first fluid, isolating the common pump from the fluid output and the primary fluid sources, connecting an inlet of the common pump to a solvent source and an outlet of the common pump to a waste fluid dump, actuating the common pump first in a pumping mode, then in a recirculation mode, and then in a flush mode, connecting an inlet of the common pump to a second primary fluid source, and an outlet of the common pump to the output line, and starting pumping mode pumping of a second fluid from the second primary fluid source through the output line.