BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid jet cutting systems, and more particularly to a fluid perforating/cutting nozzle configured for high endurance and wear resistance. 
     2. Description of the Related Art 
     In the oil and gas industry, it is often necessary to perforate or sever tubing employed during drilling operations. Fluid jet cutters are typical cutting systems utilized for such purposes due to their versatility in configuration for specific tasks and relatively low material requirements. The cutting fluid is usually a mixture of water and abrasive that is pumped to a fluid jet cutting nozzle at a very high pressure, e.g., about 3000 psi or higher. One of the difficulties arises from the design of a conventional fluid jet cutting nozzle. During a fluid jet cutting operation, the conventional nozzle experiences splashback, i.e., fluid reflecting back towards the nozzle as the cutting fluid contacts the work surface. This causes the nozzle and the tool to wear relatively quickly due to the high kinetic energy in the cutting fluid splashback and the relatively close spacing between the nozzle and the work surface in which these tools normally operate, the close spacing providing little room to avoid the angle of attack from the splashback. Worn nozzles and/or tools must be replaced or retooled, which creates significant downtime and incur undesirable additional costs. 
     Thus, a fluid perforating/cutting nozzle solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The fluid perforating/cutting nozzle is composed of a substantially cylindrical shaft having an inlet port, an outlet port and a shroud, flange or splash guard formed at the outlet port end. The splash guard is a barrier that provides a much greater surface area and material for the splashback to hit. Thus, the nozzle and the tool are significantly protected from wear. 
     Another aspect of the fluid jet cutting nozzle is the tool to which the nozzle will be mounted and the process of making the mount for the nozzle. Due to the unique features of the nozzle, the nozzle mount of the tool is configured to accommodate these unique features. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded, perspective view of a fluid perforating/cutting nozzle according to the present invention, also showing an exemplary tool on which the nozzle may be mounted. 
         FIG. 2  is a bottom perspective view of the fluid perforating/cutting nozzle according to the present invention. 
         FIG. 3  is a top perspective view of the fluid perforating/cutting nozzle according to the present invention. 
         FIG. 4  is an elevational section view of the fluid perforating/cutting nozzle according to the present invention. 
         FIG. 5  is a top plan view of the fluid perforating/cutting nozzle according to the present invention. 
         FIG. 6  is a detailed section view of the lip portion of the fluid perforating/cutting nozzle according to the present invention at the inlet end of the nozzle. 
         FIG. 7  is a detailed section view of the shoulder portion of the fluid perforating/cutting nozzle according to the present invention at the outlet end of the nozzle. 
         FIG. 8  is a partial environmental section view of the fluid perforating/cutting nozzle according to the present invention mounted on an exemplary tool, showing details of the mounting structure. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to a fluid jet perforating/cutting nozzle  100  and to a tool mount for attaching the nozzle  100  to an exemplary tool  200 . As shown in  FIGS. 2-5 , and particularly referring to  FIG. 4 , the nozzle  100  is composed of a substantially cylindrical shaft  102  having an inlet end  106  and an outlet end  110 . The inlet end defines an inlet port  108 , and the outlet end defines an outlet port  112 . The high pressure cutting fluid supplied from the tool flows into the inlet port  108  and exits through the outlet port  112 . The cylindrical shaft  102  has a threaded shank portion  104  that is used to mount the nozzle  100  onto the tool  200 . In this embodiment, the thread length is about 0.477 in. 
     Referring to  FIGS. 4 and 6 , the inlet port  108  has a machined or press-formed conical surface  114  that slightly flares out towards the bottom of the shaft  102 . The angle of the slope is about 26° with respect to the longitudinal axis of the shaft  102 . This angle can be varied, depending on the requirements for a specific task and the involved manufacturing processes for the nozzle. In a high pressure fluid jet cutting environment, it is desirable to minimize spray of the cutting fluid at the outlet end, since a coherent stream provides a better cutting characteristic. The sloping surface, as well as the smoothness thereof, directs the cutting fluid to form a coherent stream. Moreover, the smooth internal surfaces of the nozzle  100  reduce wear from abrasive particles traveling therethrough. The inlet end  106  has a lip  116  terminating at a first angled shoulder  120 . The outer portion of the lip  116  is chamfered at  118  to eliminate burrs that may have formed during manufacturing of the nozzle  100 . The first angled shoulder  120  is disposed at about 30° with respect to horizontal, and the angular disposition provides a self-centering benefit to the nozzle  100  when seating the nozzle  100  on the tool  200 . 
     In the orientation shown in  FIG. 4 , a longitudinally extending center bore  122  is disposed intermediate of the inlet and outlet ends  106 , respectively. The bore  122  forms part of the outlet port  112  and has an inner diameter of about 0.125 in. 
     Referring to  FIG. 4 , a stepped, second angled shoulder  124  is formed between the shroud  130  and the threaded shank portion. The second angled shoulder forms a shank  127 , and an O-ring  128  is mounted in the space between the shank  127  and the underside of the shroud  130 . The O-ring  128  provides a seal between the tool  200  and the nozzle  100  when the nozzle  100  is mounted onto the tool  200 . The angle of the second angled shoulder is preferably about 30° with respect to horizontal. The outlet end  110  has an outwardly extending flange that forms the shroud  130 . As shown in  FIG. 5 , the shroud  130  is disk-shaped, providing a large protective surface area to catch any splashback. The shroud  130  is preferably about 0.085-0.125 in. thick, with an outside diameter of about 0.875-1.5 in. With the shank diameter being approximately 0.477 in. it can be seen that the outside diameter of the shroud is at least 1.75 times the shank diameter (0.875/0.477). The larger diameter shroud thus forms an effective barrier that provides a much greater surface area and material for the splashback to hit. Thus, the nozzle and the tool are significantly protected from wear. 
     Referring to  FIGS. 4 ,  5  and  7 , a hexagonal aperture  140  is formed at the outlet end  110  of the nozzle  100 . The aperture  140  extends toward the central bore  122  at a slight taper or angle, designated by reference number  126 . The shape of the aperture  140  accommodates an Allen wrench, which is used to thread the nozzle  100  onto the tool  200 . The slight angle  126  provides necessary clearance for insertion of the Allen wrench. 
     Referring to  FIGS. 1 and 8 , the tool  200  may be composed of a substantially cylindrical housing  202  having an outer surface  204 . A portion of the outer surface  204  is machined to form a flat surface  206 . A nozzle mount pocket  220  is centrally located on the flat surface  206 . The pocket  220  contains, among other things, various stepped recesses that conform and correspond to features of the nozzle  100 . As shown in  FIG. 8 , and viewing these features from the surface  206  to the inner surface of the cylindrical housing  202 , the first recess  222  is a depression extending to a depth corresponding to the thickness of the shroud  130 . The second recess  224  is another depression forming a seat for the O-ring  128 . A chamfer  226  of about 60° with respect to horizontal is formed to conform to the shape of the second shoulder  124  of the nozzle. Threads  228  are tapped and extend downwardly to the formed chamfered surface  230  and a bore  232 . 
     Due to the specific features of the nozzle  100 , the following process has been developed to form the pocket in the tool. First, a blank cylindrical housing is provided. Second, the surface of the housing is machined to form the longitudinally flat surface  206 , the dimensions of which are about 3″×1.5″. Third, the center of the flat surface  206  is located and drilled. The drill bit is about 0.453 in. diameter. Fourth, the first recess  222  is formed by boring to a predetermined depth, the depth being about 0.125 in. The diameter is about 1.01 in. Fifth, the second recess  224  is formed by boring to a predetermined total depth from the flat surface  206 . The total depth is about 0.21 in., and the diameter of the second recess  224  is about 0.812 in. Sixth, the chamfer  226  is formed by a chamfering tool. The major diameter of the chamfer  226  is about 0.60 in. on drilled area. Seventh, a tap forms the threads to a minimum of 0.5 in. full thread. The dimensions of the tap are 2 in., 20 TPI (threads per inch). Eighth, sharp edges or burrs are removed to a maximum of about 0.015 in. chamfer. Finally, the seal area is polished to 32 Ra maximum finish. 
     As shown above, the protective benefits of the shroud  130  results in a longer lasting fluid jet cutting nozzle. Compared to conventional nozzles, the longer life of the nozzle  100  equates to substantial savings for the user. The size of the shroud  130  also protects the tool body because the shroud  130  covers the majority of the areas that may be hit by splashback. 
     It is noted that the present invention may encompass a variety of alternatives to the various features thereof. For example, the nozzle  100  is preferably made from tungsten carbide, but other hard, durable materials may be employed. The nozzle  100  may also be provided with a protective coating, which would further increase the erosion resistance and life of the nozzle  100 . It is noted that the dimensions mentioned above are exemplary and other dimensions are within the scope of the invention as claimed, such as that the outer diameter of the shrouded nozzle  100  may range from 0.875-2.000 in. and the tool may range from 1.5-15 in. diameter. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.
The fluid perforating/cutting nozzle is configured to provide long life to the nozzle. The nozzle is composed of a cylindrical shaft defining a bore for the passage of cutting fluid and having inlet and outlet ends, a shank portion and a relatively large diameter shroud disposed on the outlet end. The shroud protects both the nozzle and the tool from the high pressure cutting fluid reflecting off the surface of a workpiece.