Spray tip design and manufacture

Abstract

A spray tip for a fluid applicator includes a stem configured to be inserted into the fluid applicator. The stem includes a stem pre-orifice portion and an insert receiving portion. The spray tip includes a pre-orifice insert having an inlet and an outlet. The pre-orifice insert is disposed within the insert receiving portion and disposed against a rearward shoulder of the stem.

What is claimed is: 
     
         1 . A spray tip for a fluid applicator, the spray tip comprising:
 a stem configured to be inserted into the fluid applicator, the stem comprising a stem pre-orifice portion and an insert receiving portion;   a pre-orifice insert comprising an inlet and an outlet; and   wherein the pre-orifice insert is mounted within the insert receiving portion and disposed against a rearward shoulder of the stem.   
     
     
         2 . The spray tip of  claim 1 , wherein the pre-orifice insert is coupled to the pre-orifice receiving portion by a filler metal. 
     
     
         3 . The spray tip of  claim 2 , wherein an external surface of the pre-orifice insert is disposed in the range 0.0012″ to 0.01″ away from an internal surface of the insert receiving portion. 
     
     
         4 . The spray tip of  claim 1 , wherein the pre-orifice insert is coupled to the rearward shoulder by a filler metal. 
     
     
         5 . The spray tip of  claim 4 , wherein an external surface of the pre-orifice insert is disposed in the range 0.0012″ to 0.01″ away from a surface of the rearward shoulder. 
     
     
         6 . The spray tip of  claim 1 , wherein the stem pre-orifice portion comprises a frustum surface that widens in a downstream direction. 
     
     
         7 . The spray tip of  claim 1 , wherein the stem pre-orifice portion comprises a first cylindrical surface having a first diameter and a second cylindrical surface having a second diameter. 
     
     
         8 . The spray tip of  claim 7 , wherein the stem pre-orifice portion comprises a third cylindrical surface having a third diameter. 
     
     
         9 . The spray tip of  claim 1 , wherein the stem pre-orifice portion is machined into the stem. 
     
     
         10 . The spray tip of  claim 1 , wherein the pre-orifice insert comprises a frustum surface that narrows in a downstream direction. 
     
     
         11 . A method of manufacturing a spray tip for a fluid applicator, the method comprising:
 creating a channel through a stem of the spray tip, the channel having a downstream outlet and an upstream inlet; and   inserting a pre-orifice insert into the channel through the downstream outlet; and   securing the pre-orifice insert into the channel.   
     
     
         12 . The method of  claim 11 , wherein securing the pre-orifice insert comprises brazing the pre-orifice insert into place. 
     
     
         13 . The method of  claim 11 , wherein securing the pre-orifice insert comprises applying a bonding agent to the pre-orifice insert. 
     
     
         14 . The method of  claim 11 , wherein creating the channel through the stem comprises:
 machining a first hole in the stem;   machining a pre-orifice insert retaining portion; and   machining a stem pre-orifice portion that is upstream from the pre-orifice insert retaining portion.   
     
     
         15 . The method of  claim 11 , further comprising:
 grinding the pre-orifice insert to an insert diameter that is at least 0.001″ smaller than a channel diameter of the channel.   
     
     
         16 . The method of  claim 11 , wherein inserting the pre-orifice insert comprises disposing the pre-orifice insert against a rear shoulder of the channel. 
     
     
         17 . The method of  claim 11 , further comprising machining a counter bore from the upstream inlet side of the channel. 
     
     
         18 . A paint spray tip comprising:
 a cylindrical stem configured to be inserted and rotated within a paint spray gun;   a flag coupled to the cylindrical stem;   a channel disposed through the stem, the channel having an upstream inlet and a downstream outlet; and   wherein a fluid path in the channel is defined at least in part by a pre-orifice portion of the cylindrical stem having a plurality of geometric portions and a pre-orifice insert.   
     
     
         19 . The paint spray tip of  claim 18 , wherein the cylindrical stem comprises stainless steel and the tip insert comprises tungsten carbide. 
     
     
         20 . The paint spray tip of  claim 18 , wherein the pre-orifice insert is coupled to the cylindrical stem by a filler metal.