Patent Application
20070187434
I. Field of the Invention
The present invention relates generally to an applicator system which combines a proportioning cartridge or valve with a static mixer nozzle to produce a dispensing applicator for the mixture which generally consists of a combination of viscous liquids which cure upon mixing such as found in epoxy or polyurethane materials. More particularly, the invention relates to such a system in which the components of the two-part mixture are maintained in a separate condition in a proportioning valve prior to mixing thereof in a disposable static mixing nozzle. The disposable mixing nozzle is attached as part of an applicator system.
II. Related Art
It is known to provide mixing nozzles for use with dispenser systems to mix components and dispense two-part reactive adhesive or coating materials using a proportioning valve system in conjunction with a static mixing nozzle which also may serve as a dispensing nozzle. In prior systems, a combination of both components is fed into a static mixing nozzle by the proportioning cartridge or valve which combines the components in the valve. Thereafter, the material is more thoroughly mixed as it progresses through the static mixing nozzle and applied as desired from the nozzle.
The components are generally viscous fluids which begin to react upon contact with each other and set up permanently a short time after contact or mixing. One serious drawback to such prior systems is that during and after use both the static mixing nozzle and the proportioning cartridge or valve contain residual amounts of combinations of the two-part reactants so that, depending on available open time, they must be immediately cleaned or they will become permanently clogged with reacted, hardened material. The proportioning devices themselves are typically machined from metal blanks and are relatively expensive to replace and difficult to clean, but they must be thoroughly cleaned immediately after use to be used again.
Thus, there remains a definite need to provide a relatively simple, re-usable proportioning cartridge or valve that does not become clogged with hardened or reacted material after use and does not require immediate cleaning after each use.
By means of the present invention, there is provided an applicator system which includes a proportioning cartridge or valve for separately receiving components of a multi-part reactive mixture and transmitting them in desired proportions in a separate condition into an attached static mixing nozzle. The mixing nozzle includes an internal structure that produces component intermixing as the material progresses along in the nozzle. That structure generally includes a baffle arrangement that causes side-to-side deflection and produces a thorough mixing of the components as they are forced along the length of the nozzle. The proportioning cartridge or valve includes a body having separate inlet openings and recesses designed to connect to separate sources of the components to be combined and applied. The inlet recesses also connect with separate, generally parallel, internal passages which lead to separate, spaced, side-by-side discharge outlets which are received in (and discharge into) the receiving end of the connected static mixing nozzle. The mixed material may be applied from the discharge end of the static mixing nozzle as a continuous bead or another desired form.
The illustrated embodiment includes a proportioning cartridge or valve that is machined from a metal blank which may be made from steel or brass, for example, but should be a material that does not react with or affect any component. The inlet openings and recesses and/or internal passages and outlet openings may be the same or of different sizes to accommodate various input lines from separate sources and having different flow rates, if desired, of component materials. The relative amounts of the components to be mixed can be controlled by line size and/or line pressure so that any desired ratio of components may be fed into the static mixing nozzle. Suitable flow control and metering devices are provided for the component sources in a well known manner.
In an illustrative embodiment, the proportioning valve is attached to the plurality of supply lines using threaded fittings which attach flexible supply lines connected to sources of supply of each component to the valves. Oppositely disposed inlet openings lead into recesses which lead to separate parallel internal passages that terminate in separate side-by-side output openings contained in a common reduced diameter nose section. The nose section is provided with external threads and a stepped-down design to be received in a corresponding input end of a static mixing nozzle. The static mixing nozzle is provided with a step-down shoulder at its receiving end and is retained against the nose of the mixing valve by a threaded nut which slips over the nozzle, and abuts the shoulder.
The static mixing nozzle is preferably of an inexpensive construction made of a polymeric material such that after each use the static mixing nozzle part of the system may be simply discarded rather than subjected to a cleaning process. The material of each component contained in the portioning cartridge or valve remains in a separated condition and so no reaction or setting up takes place. Thus, use of the valve itself may be stopped and started as necessary and the inexpensive mixing nozzle replaced as needed or the unreacted components cleaned out of the proportioning valve as desired between uses. Cleaning, of course, is necessary when switching components.
In the drawings wherein like reference numerals designate like parts throughout the same:
The detailed description found herein is directed to an example embodiment which discloses the principles of the present invention but is not intended to limit the scope of the inventive concept. Thus, an important aspect of the present invention resides in a proportioning cartridge or valve which can be used to continuously feed separate components for a multi-part curable system. Well known examples include a system for dispensing continuous beads of epoxy resins produced from epichlorohydrin and bisphenol A; and polyurethanes, usually produced by the reaction of a polyfunctional isocyanate combined with a hydroxyl-containing component. The mixing cartridge or valve is combined with and feeds a static mixing applicator nozzle in a manner such that combining of the components and mixing takes place only in the static mixing nozzle and not in the proportioning cartridge or valve. The combination of the mixing valve and a static mixing nozzle provides an applicator for dispensing mixed material as a continuous bead of a desired size.
In the exploded perspective view of
The proportioning valve of the illustrative embodiment is designed to receive feed or component material from two sources (not shown) and supply them in separated, parallel relation to connected static mixing and dispensing nozzle 38 which includes an enlarged attachment shoulder 40 designed to accommodate nose 28 of proportioning valve 10. Mixing nozzle 38 is designed to be retained by an externally threaded retaining nut 42 which fits against the shoulder 40 and threads onto section 24 at 26. Internal mixing baffles shown in the cutaway at 44 mix the components as they are forced along inside the nozzle 38. The baffles are arranged in the passage in a manner that blocks a direct line of flow through the mixing nozzle and are preferably connected to cause flow to alternating sides of the nozzle 38 to produce thorough mixing. A stepped-down cut-off outlet is shown at 46 which enables the user to select the output bead size to use for the mixed material.
It should be noted that the relative sizes of the supply lines 34 and 36, the inlet passages and the internal component feed passages 16 and 18 may be tailored to accommodate any ingredient viscosity and proportion ratio desired in a final mix. In addition, the discharge pressure in the lines 34 and 36 may be modulated in a well-known manner to adjust proportional feed rates to the mixing nozzle. In the illustrative example of the detailed description, the inlet opening and recess 12 is shown larger than the passage 14, for example. The internal passages and outlets also may be sized to control the output flow of the valve 10.
The proportioning valve 10 is preferably machined from steel, brass or other metallic material which does not react with the materials of the curable system. The valve is designed to be reused many times to supply components to various mixes without fear of reaction and hardening taking place within the valve.
The static mixing nozzle 38 of the combination is preferably an inexpensive plastic part which can be discarded and replaced after each use rather than requiring a user to clean and remove reacted or reacting materials. Such types of static baffled mixing nozzles are known and available commercially from several sources. Any suitable material may be used for the mixing nozzle that does not react or affect the materials being mixed or combined.
As indicated, an important aspect of the present invention relates to maintaining separation of the components prior to final mixing in the static mixing nozzle 38. In this manner, as indicated, only unreacted fluid ingredients are present in the valve 10 at any time making the valve 10 easy to clean after use or even allowing it to be stored in the presence of components between uses given the continued use of the same materials. Thus, reacted or combined materials are confined to the inexpensive, “throw-away” component of the system while the machine proportioning valve remains to be used many times.
The proportioning, mixing and dispensing system of the present invention may be manifested as part of a continuously fed system for applying or layering down a continuous bead of polyurethane epoxy or other plastic material to a structure or delivering other materials as part of a manual or mechanized coating or seaming operation in which the applicator is used in conjunction with a multi-step manufacturing process.
This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.
