BACKGROUND OF THE INVENTION 
     1. Technical Field 
     Generally, the invention relates to high pressure fluid cutting systems. Particularly, the invention relates to high velocity cutting nozzles for connection to the fluid supply tube of high pressure fluid cutting systems. Specifically, the invention relates to cutting nozzles comprising a housing which threadably connects to the fluid supply tube for receiving pressurized liquid therefrom, with a bushing disposed in the housing that sandwiches a removable sleeved orifice disk therebetween at a spray outlet bore of the housing. 
     2. Background Information 
     High pressure liquid cutting devices are commonly used for cutting various sheet materials such as plastics, and masonry materials such as brick and concrete slabs. Such cutting devices are also used for drilling and abrading materials. Such devices are also often used to clean materials such as masonary and steel. Such cutting devices usually include an electric motor which drives a hydraulic pump supplying a working fluid to a high pressure intensifier unit. The intensifier draws a cutting liquid in the form of water from a reservoir, and discharges the water at a very high pressure (e.g. 20,000 to 70,000 psi or more) through the fluid supply tube to the cutting nozzle to produce a fluid jet to cut through the desired material. The fluid jet may range in diameter from about a thousandth of an inch up to about fifteen thousandths of an inch or more, at a velocity of about 1,000 to 3,000 feet per second. 
     Many prior art cutting nozzles are prone to prematurely wearing out due to abrasion caused by the high pressure and velocity of the water traveling through the nozzles upstream of the orifice. Turbulence upstream of the orifice also causes lack of cohesiveness of the fluid jet. That is, convergence of the various velocity vectors of the fluid within the fluid jet at the orifice only extends for a short distance upon exiting the orifice. This results in a more dispersed fluid jet having less cutting force so only shallower cuts may be made, a wider width of cut or kerf, and more overspraying or wetting of the material adjacent the cut. Conversely, a more cohesive fluid jet provides a finer fluid jet, more precise cutting, and deeper cuts. 
     One attempt to reduce such turbulence is a liquid jet cutting device and method disclosed in U.S. Pat. No. 3,997,111 issued to Thomas et al. on Dec. 14, 1976. The disclosed device includes a source of high pressure fluid, a jet nozzle, and a high pressure conduit connecting the fluid source to the nozzle. A liquid collimating device is disposed directly upstream of the nozzle comprising a housing interconnected between the conduit and the nozzle. The housing defines a flow collimating chamber directly upstream of the nozzle through which the high pressure liquid is delivered to the nozzle. The cross-sectional area of the flow collimating chamber must be at least greater than one hundred times the cross-sectional area of the nozzle opening. The liquid jet produced is claimed to have relatively little dispersion and a relatively narrow kerf. 
     An orifice assembly and method providing highly cohesive fluid jet is disclosed in U.S. Pat. No. 5,226,597 issued to Ursic on Jul. 13, 1993. The orifice assembly includes a housing that receives pressurized fluid from a supply tube. The housing has a passageway therein through which the fluid flows. The passageway has an orifice element therein having an orifice for producing the fluid jet, and a converging section disposed upstream of the orifice that extends toward the orifice element. The converging section is designed to reduce turbulence upstream of the orifice and thus produce a more cohesive fluid jet emitted from the orifice. A section having a rounded surface is disposed between the converging section and the orifice element which joins the converging section and an upstream portion of the orifice element. The section is designed to further improve the cohesiveness of the fluid jet by further reducing turbulence upstream of the orifice. 
     Although these devices are adequate for the purpose for which they were intended, the first device has additional length and adds weight to the cutting assembly. Additionally, neither device directly addresses the problem of nozzle wear. 
     Another problem with prior art nozzles is the inability to easily change orifice sizes when the particular material requires such. The sapphire orifice disk is typically affixed to the nozzle housing requiring changing out of the entire nozzle, or the use of a press to remove the orifice disk from the housing. Furthermore, the same must be done to replace a worn out orifice disk. If the orifice disk cannot be removed, the entire nozzle must be scrapped. 
     Therefore, the need exists for an improved high velocity cutting nozzle that reduces turbulence upstream of the orifice to produce a narrow kerf, that has a significantly longer service life prior to wearing out, and having easily replaceable orifice disks. 
     SUMMARY OF THE INVENTION 
     Objectives of the invention include providing a high pressure cutting nozzle which has reduced turbulence. 
     Another objective is to provide a high pressure cutting nozzle with significantly reduced internal wear due to abrasion of the water flow providing a longer service life. 
     A further objective is to provide a high pressure cutting nozzle in which orifice disks are easily changed to ones having a different orifice size or replaced when worn out. 
     A still further objective of the invention is to provide such a high pressure cutting nozzle which includes a separate housing and bushing between which the orifice disk is sandwiched, and which solves problems and satisfies needs existing in the art. 
     These objectives and advantages are obtained by the improved high velocity cutting nozzle for connection to a fluid supply tube of a high pressure fluid cutting system of the present invention, the general nature of which may be stated as including: a housing adapted for connection to the fluid supply tube, a bushing receiving bore extending from the fluid supply tube partially through the housing, and a spray outlet bore extending inwardly from a front surface of the housing which joins with the bushing receiving bore through which the liquid is directed as a high velocity liquid cutting jet; a bushing that closely fits within the bushing receiving bore, having an end surface adapted to closely sealingly engage a mating surface of the housing within the bushing receiving bore, the bushing having a flow-directing bore for receiving the liquid from the fluid supply tube and extending at least partially through the bushing, the flow directing bore including a convergent inlet portion having an annular inner surface for reducing turbulence in the flow-directing bore, and an outlet portion having an annular inner surface and a convergent end surface; and an orifice plate in co-axial fluid communication with the flow-directing bore and the spray outlet bore, the orifice plate fitting within a sleeve receiving bore in one of the bushing and the housing immediately downstream of the flow-directing bore and abutting a shoulder of the bushing, the orifice plate having an orifice of a diameter that is smaller than a minimum diameter of the flow-directing bore for producing a high velocity fluid jet, with the orifice plate being sandwiched between the bushing and the housing. 
     According to another aspect, the objectives and advantages are obtained by the improved method for extending the service life of a high velocity cutting nozzle, the general nature of which may be stated as including the steps of: producing a flow of high pressure fluid; passing the flow through a flow-directing bore including a convergent inlet portion having an annular inner surface, and through an outlet portion having an annular inner surface and a convergent end surface to remove turbulence; and passing the flow through an orifice closely adjacent the flow-directing bore having an orifice of a diameter that is smaller than a minimum diameter of the flow-directing bore for producing a high velocity fluid jet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
     FIG. 1 is a schematic view of a high pressure water cutting system of the type that may utilize the cutting nozzles of the present invention; 
     FIG. 2 is a fragmentary longitudinal sectional view of a first embodiment of the cutting nozzle of the present invention having a flow directing bore that includes a straight outlet portion having an annular straight surface and an annular curved convergent surface; 
     FIG. 3 is a fragmentary longitudinal sectional view of a second embodiment of the cutting nozzle of the present invention having a flow directing bore that includes a straight outlet portion having an annular straight surface and an annular angled convergent surface; 
     FIG. 4 is a fragmentary longitudinal sectional view of a third embodiment of the cutting nozzle of the present invention having a flow directing bore that includes a flared outlet portion having an annular flared surface and an annular curved convergent surface; 
     FIG. 5 is a fragmentary longitudinal sectional view of a fourth embodiment of the cutting nozzle of the present invention having a flow directing bore that includes a flared outlet portion having an annular flared surface and an annular curved convergent surface; 
     FIG. 6 is a partially exploded perspective view of the housing and bushing, with the sleeve, and orifice disk installed within the bushing of the cutting nozzles; 
     FIG. 7 is an exploded perspective view of the housing, bushing, sleeve, and orifice disk of the cutting nozzle; 
     FIG. 8 is an exploded perspective view of the housing, bushing, sleeve, orifice disk, and an alternate orifice disk having a larger orifice of the cutting nozzle; and 
     FIG. 9 is a partially exploded perspective view of the housing, bushing, and orifice disk, with the sleeve, and alternate orifice disk installed within the bushing of the cutting nozzle. 
     Similar numerals refer to similar parts throughout the drawings. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The high velocity cutting nozzle of the present invention is shown in FIGS. 1 and 2, and is indicated generally at  20 . Cutting nozzle  20  is shown in FIG. 1 positioned as part of a high pressure water cutting system  23 . Cutting system  23  includes a cutting gun  26  having a fluid supply tube  29  to which the cutting nozzle  20  is engaged as explained subsequently. Gun  26  receives high pressure water produced by an electric powered hydraulic pump  32  that supplies a working fluid such as hydraulic fluid through a pipe  35  to a high pressure intensifier unit  38 . The intensifier unit  38  draws a suitable cutting fluid (i.e. water) through a pipe  41  from a reservoir  44 , and discharges the water at a very high pressure through a pipe  47  to an ultra-fine filter  50  to remove any small particulates that might plug up the cutting nozzle  20 . The water passes from filter  50  through a pipe  53  to the fluid supply tube  29  of gun  26 . 
     Cutting nozzle  20  includes a housing  56  preferably made of high strength steel, a bushing  59  preferably made of steel, an orifice disk  62  preferably made of sapphire, and a sleeve  65  preferably made of plastic or rubber. The housing  56  is generally cylindrical in shape, having an externally threaded portion  68  configured to engage an internally threaded portion  71  of a bore  74  of fluid supply tube  26  of standard guns  26 , and a wrench engaging external hexagonal portion  77  adapted to be engaged by standard hex wrenches (not shown). A bushing receiving bore  80  extends through the threaded portion  68  and partially into the hexagonal portion  77 . A spray outlet bore  83  extends from a convex front surface  86  of housing  56  into the hexagonal portion  77  and joins with the bushing receiving bore  80 . The bushing  59  includes a cylindrical body  89  terminating at a head  92 , the body  89  being of a diameter to closely fit within the bushing receiving bore  80 , with head  92  being of a larger diameter. Head  92  includes a frustoconical or annular tapered surface  95  adapted to engage a mating frustoconical or annular tapered surface  98  of fluid supply tube  29  when cutting nozzle  20  is assembled to gun  26 . A flat end surface  101  of bushing  59  closely engages a mating circular surface  104  of housing  56  within bushing receiving bore  80  when bushing  59  is assembled within housing  56 , with an annular space  107  remaining between head  92  and threaded portion  68 . The bushing  59  further includes a flow directing bore  110  coaxially disposed with a water outlet bore  111  of fluid supply tube  29  of gun  26 , the flow directing bore  110  having a longitudinally tapered inlet portion  113  having an angular funnel-shaped surface  116  and a straight outlet portion  119  having a cylindrical straight surface  122  and a cylindrical curved convergent surface  125 . Surface  116  could also be slightly convex without departing from the spirit of the present invention. A sleeve receiving bore  128  extends inwardly from flat surface  101  of bushing  59  joining with the outlet portion  119  of flow directing bore  110  at a shoulder  131 . The orifice disk  62  includes an orifice  134  of a desired cutting diameter, and pressfits into an inner bore  137  of sleeve  65 . Sleeve  65  closely, but removably fits into the sleeve receiving bore  128  of bushing  59 . 
     A second embodiment of the cutting nozzle of the present invention is indicated at  140  in FIG.  3 . Cutting nozzle  140  includes the housing  56 , a bushing  59 A, the orifice disk  62 , and the sleeve  65 . The bushing  59 A includes a cylindrical body  89 A terminating at a head  92 A, the body  89 A being of a diameter to closely fit within the bushing receiving bore  80 , with head  92 A being of a larger diameter. Head  92 A includes an annular tapered surface  95 A adapted to engage the annular or cylindrical tapered surface  98  of fluid supply tube  29  when cutting nozzle  140  is assembled to gun  26 . A flat end surface  101 A of bushing  59 A closely engages the circular surface  104  of housing  56  within bushing receiving bore  80  when bushing  59 A is assembled within housing  56 , with the annular space  107  remaining between head  92 A and threaded portion  68 . The bushing  59 A further includes a flow directing bore  10 A coaxially disposed with the water outlet bore  111  of fluid supply tube  29  of gun  26 , the flow directing bore  110 A having the longitudinally tapered inlet portion  113 A having the funnel-shaped surface  116 A and a straight outlet portion  119 A having a cylindrical straight surface  122 A and an annular angled convergent surface  125 A. A sleeve receiving bore  128 A extends inwardly from flat surface  101 A of bushing  59 A joining with the outlet portion  119 A of flow directing bore  110 A at a shoulder  131 A. The orifice disk  62  includes the orifice  134  of a desired cutting diameter, and pressfits into the inner bore  137  of sleeve  65 . Sleeve  65  closely, but removably fits into the sleeve receiving bore  128 A of bushing  59 A. 
     A third embodiment of the cutting nozzle of the present invention is indicated at  143  in FIG.  4 . Cutting nozzle  140  includes the housing  56 , a bushing  59 B, the orifice disk  62 , and the sleeve  65 . The bushing  59 B includes a cylindrical body  89 B terminating at a head  92 B, the body  89 B being of a diameter to closely fit within the bushing receiving bore  80 , with head  92 B being of a larger diameter. Head  92 B includes tapered surface  95 B adapted to engage the tapered surface  98  of fluid supply tube  29  when cutting nozzle  140  is assembled to gun  26 . A flat end surface  101 B of bushing  59 B closely engages the circular surface  104  of housing  56  within bushing receiving bore  80  when bushing  59 B is assembled within housing  56 , with the annular space  107  remaining between head  92 B and threaded portion  68 . The bushing  59 B further includes a flow directing bore  110 B coaxially disposed with the water outlet bore  111  of fluid supply tube  29  of gun  26 , the flow directing bore  110 B having the longitudinally tapered inlet portion  113 B having a funnel-shaped surface  116 B and a flared divergent outlet portion  119 B having an annular flared surface  122 B and an annular curved convergent surface  125 B. A sleeve receiving bore  128 B extends inwardly from flat surface  101 B of bushing  59 B joining with the outlet portion  119 B of flow directing bore  110 B at a shoulder  131 B. The orifice disk  62  includes the orifice  134  of a desired cutting diameter, and pressfits into the inner bore  137  of sleeve  65 . Sleeve  65  closely, but removably fits into the sleeve receiving bore  128 B of bushing  59 B. 
     A fourth embodiment of the cutting nozzle of the present invention is indicated at  146  in FIG.  5 . Cutting nozzle  140  includes the housing  56 , a bushing  59 C, the orifice disk  62 , and the sleeve  65 . The bushing  59 C includes a cylindrical body  89 C terminating at a head  92 C, the body  89 C being of a diameter to closely fit within the bushing receiving bore  80 , with head  92 C being of a larger diameter. Head  92 C includes an annular tapered surface  95 C adapted to engage the annular tapered surface  98  of fluid supply tube  29  when cutting nozzle  140  is assembled to gun  26 . A flat end surface  101 C of bushing  59 C closely engages the circular surface  104  of housing  56  within bushing receiving bore  80  when bushing  59 C is assembled within housing  56 , with the annular space  107  remaining between head  92 C and threaded portion  68 . The bushing  59 C further includes a flow directing bore  110 C coaxially disposed with the water outlet bore  111  of fluid supply tube  29  of gun  26 , the flow directing bore  110 C having the longitudinally tapered inlet portion  113 C having a funnel-shaped surface  116 C and a flared divergent outlet portion  119 C having an annular flared surface  122 C and an annular curved convergent surface  125 C. A sleeve receiving bore  128 C extends inwardly from flat surface  101 C of bushing  59 C joining with the outlet portion  119 C of flow directing bore  110 C at a shoulder  131 C. The orifice disk  62  includes the orifice  134  of a desired cutting diameter, and pressfits into the inner bore  137  of sleeve  65 . Sleeve  65  closely, but removably fits into the sleeve receiving bore  128 C of bushing  59 C. 
     The cutting nozzle  20  (as well as cutting nozzles  140 ,  143 , and  146 ) threadably connects to the fluid supply tube  29  of gun  26  by engaging a wrench to the external hexagonal portion  77  of housing  56 . The annular tapered surface  95  of bushing  59  engages the annular tapered surface  98  of fluid supply tube  29  as cutting nozzle  20  is tightened, forcing bushing  59  further into the bushing receiving bore  80 . The flat end surface  101  of bushing  59  closely engages the mating circular surface  104  of housing  56  within bushing receiving bore  80 , sealing nozzle  20  to fluid supply tube  29 . The orifice disk  62  and sleeve  65  are retained within the sleeve receiving bore  128  by the shoulder  131  without being pressfit or otherwise affixed therein. Therefore, upon disassembly of cutting nozzle  20 , the orifice disk  62  with sleeve  65  readily slides out of the sleeve receiving bore  128  without using tools, and may be replaced by an orifice disk  149  within another sleeve  65  having a different size orifice  152  to suite a different cutting job. Likewise, when orifice disk  62  wears out, it may readily be replaced without throwing out the entire cutting nozzle  20 . The cutting nozzle  20  fastens directly to conventional fluid supply tubes  29  and requires no modification thereto. 
     The method of operation includes the following steps: 1) producing a flow of high pressure fluid; 2) passing the flow through a flow-directing bore including a convergent inlet portion having an annular inner surface, and through an outlet portion having an annular inner surface and a convergent end surface to remove turbulence; and 3) passing the flow through an orifice closely adjacent the flow-directing bore having an orifice of a diameter that is smaller than a minimum diameter of the flow-directing bore for producing a high velocity fluid jet. The outlet portion has one of four configurations: a) the annular inner surface is a cylindrical surface with an annular curved convergent surface downstream thereof; b) the annular inner surface is a cylindrical surface with an annular straight convergent surface downstream thereof; c) the annular inner surface is an annular straight divergent surface with an annular curved convergent surface downstream thereof; and d) the annular inner surface is an annular straight divergent surface and an annular straight convergent surface downstream thereof. In operation, it is believed that the inwardly convex convergent inlet portion of the flow directing bore stabilizes the flow of water to reduces turbulence in the flow-directing bore, producing a more laminar and coherent flow prior to entering the orifice. The various configurations of the outlet portion augment this process by smoothly directing the flow into the orifice, with or without a slight initial expansion of the flow area prior to entering the orifice. The result is less turbulence in the flow producing less wear and a tighter kerf. 
     It is understood that various materials other than those listed may be used in the construction of the cutting nozzles and various finishes be applied. For example, the bushing might be made of brass or a sand blast finish applied to all the water contacting surfaces rather than a smooth finish to improve cohesiveness of the flow. Also, other housing and bushing configurations may be devised. For example, the sleeve receiving bore may be disposed in the housing rather than in the bushing. 
     Accordingly, the cutting nozzles provide reduced turbulence to produce a finer kerf, significantly reduced internal wear due to abrasion of the water flow providing a longer service life, orifice disks that are easily changed to ones having a different orifice size or replaced when worn out, and a separate housing and bushing between which the orifice disk is sandwiched which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior art devices, and solves problems and obtains new results in the art. 
     In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
     Having now described the features, discoveries and principles of the invention, the manner in which the improved high velocity cutting nozzle is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
     TERMS 
       20 . first embodiment cutting nozzle 
       23 . high pressure water cutting system 
       26 . [cutting system] cutting gun 
       29 . [gun] fluid supply tube 
       32 . [cutting system] electric powered hydraulic pump 
       35 . [cutting system] pipe 
       38 . [cutting system] high pressure intensifier pump 
       41 . [cutting system] pipe 
       44 . [cutting system] reservoir 
       47 . [cutting system] pipe 
       50 . [cutting system] ultra-fine filter 
       53 . [cutting system] pipe 
       56 . [cutting nozzle] housing 
       59 . [cutting nozzle] bushing 
       62 . [cutting nozzle] orifice disk 
       65 . [cutting nozzle] sleeve 
       68 . [cutting nozzle] externally threaded portion 
       71 . [fluid supply tube] internally threaded portion 
       74 . [gun] bore 
       77 . [housing] externally hexagonal portion 
       80 . [housing] bushing receiving bore 
       83 . [housing] spray outlet bore 
       86 . [housing] convex front surface 
       89 . [bushing] body 
       92 . [bushing] head 
       95 . [head] annular tapered surface 
       98 . [gun] annular tapered surface 
       101 . [bushing] flat end surface 
       104 . [housing] circular surface 
       107 . [cutting nozzle] annular surface 
       110 . [bushing] flow directing bore 
       111 . [gun] water outlet bore 
       113 . [bore] longitudinally tapered inlet portion 
       116 . [bore] annular concave surface 
     “R” radius 
       119 . [bore] bulbous outlet portion 
       122 . [outlet portion] annular straight surface 
       125 . [outlet portion] annular curved convergent surface 
       128 . [bushing] sleeve receiving bore 
       131 . [bushing] shoulder 
       134 . [orifice disk] orifice 
       137 . [sleeve] inner bore 
       140 . second embodiment cutting nozzle 
       143 . third embodiment cutting nozzle 
       146 . fourth embodiment cutting nozzle 
       149 . [cutting nozzle] alternate orifice disk 
       152 . [orifice disk] orifice
A high velocity cutting nozzle for connection to the fluid supply tube of a high pressure fluid cutting system. The nozzle includes a housing which threadably connects to the fluid supply tube for receiving pressurized liquid therefrom. A bushing disposed within the housing sandwiches a removable sleeved jeweled orifice disk therebetween at a spray outlet bore of the housing. The bushing includes a flow directing bore with a convergent inlet portion for reducing turbulence, and an outlet portion having an annular cylindrical or divergent inner surface, and an annular convergent angled or curved end surface. The sleeved orifice disk is in co-axial fluid communication with the flow-directing bore and a spray outlet bore of the housing to facilitate fluid flow. The sleeved orifice disk fits within a sleeve receiving bore in the bushing immediately downstream of the flow-directing bore abutting a shoulder of the bushing.