| CPC B29B 7/7404 (2013.01) [B29B 7/7615 (2013.01); B29B 7/7657 (2013.01); B29B 7/7668 (2013.01); B29B 7/7684 (2013.01); B29B 7/801 (2013.01); B29C 44/365 (2013.01)] | 34 Claims |
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1. High-pressure mixing device suitable for forming a polymeric mixture resulting from one first and at least one second chemically reactive liquid component, said mixing device comprising:
a head-body configured with a mixing chamber having inner cylindrical surface having inlet openings and outlet openings, respectively, for injecting and recirculating the reactive components;
a delivery duct for releasing and ejecting the resulting polymeric mixture, having an inner cylindrical surface in fluid communication with said mixing chamber and inside which a cleaning member is slidingly movable that is adapted to eject the resulting polymeric mixture at an end of delivery and adapted to clean by scraping the inner surface of said delivery duct;
a valve member provided with longitudinal slots for recirculating separately the reactive liquid components and slidingly movable in said mixing chamber between a backward position, in which said valve member clears the front of said inlet openings, and advanced position, in which each of said longitudinal recirculating slots puts in communication one respective inlet opening with a respective outlet opening for recirculating the respective reactive component;
wherein said delivery duct is composed of a tubular element made in a single, not jointed, piece, having an open upper end communicating with a spacer chamber, and an open lower end for delivering the resulting polymeric mixture and,
the cleaning member or stem reciprocable via hydraulic control along said tubular element between an upper backward position—in which the cleaning member or stem clears, at least partially, an outlet of said mixing chamber into a delivery chamber defined in said tubular element for enabling the outflow of the resulting polymeric mixture—and a lower advanced position in which the cleaning member or stem ejects the mixture still contained in said tubular element and scrapes away from the surface of said tubular element an adhered resin;
said tubular element being a piece distinct from, separated and processed separately from, said head-body and removably insertable into a pass-through hole of said head-body, transversal with respect to said mixing chamber, so as to protrude at a bottom longitudinally along the axis of said pass-through hole and transversally with respect to said mixing chamber;
wherein said tubular element is configured with an intermediate transversal hole placed, in an assembly configuration, so as to extend, with an increased diameter, said mixing chamber which thus extends up until it leads into them inner chamber of said tubular element;
on the surface that delimits said intermediate transversal hole an annular seat being formed and shaped to house an elastic or elasto-plastic sealing element, said elastic or elasto-plastic sealing element being housed with forced interference and compressed in said annular seat to exert a hydraulic function against leakages of reactive components from said longitudinal recirculating slots towards said tubular element and against leakage of lubricant liquid from the gap defined between a control stem of said cleaning member and said tubular element towards said longitudinal slots when an end front part of said valve member is in the advanced position;
said tubular element being configured with an annular shoulder zone placed at a zone distant from said intermediate transversal hole, and
fixing and orienting elements being provided and configured for removably fixing said annular shoulder zone to a side surface of said head-body for locking in a correct position said tubular element in said pass-through hole,
between said tubular element and said pass-through hole a clearance gap being defined configured both for allowing to easily interchange said tubular element and for limiting the contact area between said tubular element and said head-body, so as to reduce the exchange of forces between said tubular element and the surface of said pass-through hole in said head-body and transfer the load from said tubular element to said head-body substantially totally through the aforesaid annular shoulder zone,
sealing and centering elements configured to maintain said tubular element in axially centred position and separated with respect to said pass-through hole of said head-body, avoiding metal-on-metal contact between respective cylindrical surfaces thereof, and configured to avoid leakages the polymeric mixture of the reactive components from said mixing chamber through said clearance gap and towards said spacer chamber and to avoid any leakage of lubricant liquid from said spacer chamber towards said mixing chamber through said clearance gap,
further comprising deformation-detecting elements configured to detect deformation conditions which said tubular element is subjected to due to the friction, scraping and bonding forces exchanged between the cleaning member and the inner surface of said tubular element, so as to monitor working conditions of said mixing device.
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