Patent Publication Number: US-2011068201-A1

Title: Build-up minimizing spray gun tip

Description:
TECHNICAL FIELD 
     This application claims the benefit of U.S. Application Ser. No. 61/052,833, filed May 13, 2008, the contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND ART 
     Spray guns, particularly for the application of fast setting materials such as polyurethanes and polyureas have traditionally been prone to the build-up of sprayed material on the front of the gun which requires laborious cleaning by the operator. 
     DISCLOSURE OF THE INVENTION 
     The purpose of this invention is to prevent build-up of sprayed material on the frontal surface of spray guns. 
     The instant invention utilizes high pressure air forced through thin openings that surround the spray tip, to eliminate the eddies in the air flow around the frontal area of the spray gun. Without this technology the eddies spin towards the frontal area of the gun, bringing small particulates back to the frontal area of the gun where they can build-up and eventually effect the spray pattern. One concentric thin opening surrounds the spray tip similar to the current spray applicators on the market today and is directed parallel to the direction of spray. With a second concentric thin opening, the air is directed at an angle of about 55 degrees relative to the axis or direction of spray. The eddies are forced to develop further away from the frontal area of the gun, where the eddies can not deposit the particulates on the frontal area of the spray gun. 
     The advantage of this construction is that the time between manual cleanings of the frontal area of the gun can be lengthened or eliminated. This allows operator to be more efficient. 
     These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-section of the front end of a spray gun embodying the instant invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In spray tip assembly of the instant invention, generally  10 , is comprised of a housing  12 , a retaining ring  14  threadedly attached to housing  12 , and an air cap  16  having a conical face and surrounding a spray tip  18  having a fluid passage  20  therein which runs longitudinally along the axis of the tip  18 . A passage  26  supplies pressurized air to the tip assembly  10  where it can exit through two openings which are concentric about tip  18 . The first concentric opening  22  is formed between tip  18  and the central opening in air cap  16 . The width of the opening  22  in the preferred embodiment is about 0.005 inches. A second concentric opening  24  is formed between retaining ring  14  and air cap  16  and in the preferred embodiment has a width of about 0.015 inches. Also in the preferred embodiment, the conical face  16   a  of air cap  16  has an angle (designated by A in  FIG. 1 ) of about 55 degrees relative to the axis formed by passage  20  and the center  16  of air cap  16  is spaced backwards a distance (designated by B in  FIG. 1 ) of about 0.302 inches from the tip of spray tip  18 . 
     The instant invention utilizes high pressure air forced through thin openings that surround the spray tip, to eliminate the eddies in the air flow around the frontal area of the spray gun. Without this technology the eddies spin towards the frontal area of the gun, bringing small particulates back to the frontal area of the gun where they can build-up and eventually effect the spray pattern. One concentric thin opening surrounds the spray tip similar to the current spray applicators on the market today and is directed parallel to the direction of spray. With a second concentric thin opening, the air is directed at an angle of about 55 degrees relative to the axis or direction of spray. The eddies are forced to develop further away from the frontal area of the gun, where the eddies can not deposit the particulates on the frontal area of the spray gun. 
     It is contemplated that various changes and modifications may be made to the spray gun tip without departing from the spirit and scope of the invention as defined by the following claims.