Abstract:
A water cutting assembly with an increased stream cohesiveness to improve the efficiency of water cutting operations. The water cutting assembly includes a nozzle, a nozzle nut, and an orifice assembly that defines a collimating chamber to reduce turbulence of the water before it exits an orifice passage in the orifice assembly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This present invention is directed to a water cutting assembly and nozzle nut that allows a more cohesive high velocity water stream for cutting of materials. 
         [0002]    High pressure water assemblies  100  typically include a nozzle  120  and a retainer  102  secured to the nozzle by a nut  108  ( FIG. 1 ). The retainer  102  forms a water tight seal with the nozzle  120  and includes an orifice member  106  sealed to the retainer by an O-ring  104 . The orifice member  106  is typically formed from a sapphire or ruby material. The retainer  102  also includes an elongated passage extending away from the orifice  106 . The retainer  102  and orifice member  106  are designed to be replaceable so that when the orifice member  106  wears out and the stream loses efficiency or cohesiveness or the seals  104  around the orifice member  106  wear out, the retainer  102  including orifice member  106  may be discarded and replaced. However, replacement of the retainer  102  with a new retainer including a new orifice member is difficult and reduces valuable operational time. More specifically, when the orifice member is replaced valuable time is spent aligning and realigning the position of the retainer as well as recalibrating the apparatus so that the water stream will contact the work piece precisely. 
         [0003]    Manufacturers continue to strive to create more cohesive water streams and therefore faster and more accurate and precise cuts. Therefore, with any water cutting assembly, a cohesive and narrow water stream is desired to create a water cutting apparatus that is more efficient, precise and accurate. Most improvements to the water stream cohesiveness relate to the orifice passage. 
       SUMMARY OF THE INVENTION 
       [0004]    In view of the above, the present invention is directed to an assembly for a water cutting apparatus that includes an improved nozzle assembly that improves the cohesiveness of the exiting water stream. A more cohesive water stream at high pressure allows for more efficient operation and faster cutting times. 
         [0005]    The present invention includes an end assembly for a water cutting apparatus comprising a nozzle, a nut coupled to the nozzle, and a collimating chamber defined between the nozzle and the nut. The collimating chamber has a volume and a portion of the volume is formed by each of the nut and the nozzle. 
         [0006]    The nozzle may include a first end and an opposing second end, with an elongated passageway extending between the first and second ends. The elongated passageway includes an expanded area portion. The nut may include an orifice assembly, so that the nut, nozzle and the orifice assembly define a collimating chamber. The orifice assembly includes a retainer having an inner profiled surface extending from the nut to the orifice member with a decreasing diameter. The expanded area portion, in combination with an inner profiled surface cooperate to create an enlarged collimating chamber. 
         [0007]    A nut having an orifice member for use with a water cutting apparatus. The nut includes a cavity having a threaded area, a sealing surface, a profiled surface and orifice cavity. The sealing surface is located between said threaded area and said profiled surface. An orifice assembly is retained within the orifice cavity. The orifice assembly includes an orifice and a retainer having an inner retainer profile. 
         [0008]    Further scope of applicability of the present invention will become apparent from the following detailed description, claims, and drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which: 
           [0010]      FIG. 1  is a partial sectional view of a prior art water cutting assembly; 
           [0011]      FIG. 2  is a partial sectional view of a first exemplary water cutting assembly; 
           [0012]      FIG. 3  is a partial sectional view of a second exemplary water cutting assembly; 
           [0013]      FIG. 4  is a partial sectional view of a third exemplary water cutting assembly; 
           [0014]      FIG. 5  is a partial sectional view of a fourth exemplary water cutting assembly; 
           [0015]      FIG. 6  is a partial sectional view of a fifth exemplary water cutting assembly; 
           [0016]      FIG. 7  is a partial sectional view of a sixth exemplary water cutting assembly; 
           [0017]      FIG. 8  is a partial sectional view of a seventh exemplary water cutting assembly; 
           [0018]      FIG. 9  is a partial sectional view of a eighth exemplary water cutting assembly; and 
           [0019]      FIG. 10  is a partial sectional view of a ninth exemplary water cutting assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    As illustrated in  FIG. 2  the present invention is directed to a water cutting assembly  10  having a nozzle body  20 , a nozzle nut  22 , and an orifice assembly  70 . The nozzle  20  generally includes threads  26  to which the nozzle nut  30  is secured with a threaded portion  39 . To perform water cutting operations, high pressure water is provided through an inlet passage  24  on the nozzle  20  to an expanded region portion, generally referred to in this application as a collimating chamber  80 . The water then passes through a restriction such as the illustrated orifice passage  52  in the orifice member  50 . By releasing the water through an opening the size of the orifice passage  52  a very high velocity water stream is created that is capable of cutting materials such as steel or aluminum. 
         [0021]    The nozzle  20  generally includes an elongated body  21  which defines the inlet passage  24 . At a first end, not illustrated, the nozzle  20  is connected to an apparatus that provides high pressure water to the inlet passage  24 . Many prior art nozzles have a collimating chamber at the first end, and the present invention may also have a variety of configurations at the first end, including a collimating chamber. The apparatus or assembly to which the nozzle  20  is coupled may be a robotic arm capable of movement. At the second end  23 , the nozzle  20  includes threads  26  or other coupling means and an inner wall or a first profiled surface  28  that defines an expanded region  29  which forms at least a portion of the collimating chamber  80 . The nozzle  20  also includes a seal surface or a first engagement surface  22  which allows the nozzle nut  30  to be coupled to the nozzle  20  with a water tight seal. The first engagement surface  22  meets the first profiled surface  28  at an inner nozzle edge  29 . While the first engagement surface  22  is illustrated as being in a plane perpendicular to the axis of the inlet passage  24 , other geometric configurations may be used such as a beveled surface, so long as the nozzle nut  30  is capable of being sealed to the nozzle  20  to withstand the high pressures within the inlet passage  24  and collimating chamber  80 . 
         [0022]    The nozzle nut  30  defines a cavity  31  having a threaded portion  39 , a second engagement or seal surface  32 , an inner wall or second profiled surface  36 , an orifice cavity  38 , and an outlet passage  34 . The threaded portion  39  allows the nozzle nut  30  to be threaded onto the nozzle  20  although other means of connection may be used. The second engagement surface  32  creates a water tight seal with the first engagement surface when the nozzle nut  30  is coupled to the nozzle  20 . The orifice cavity  38  is designed to receive the orifice assembly  70 . The second profiled surface  36  is located between the orifice cavity  38  and the second engagement surface  32 . While in the first example in  FIG. 2  the second profiled surface  36  may be a bevel, as shown in  FIGS. 4-7 , it may instead be approximately parallel to the inlet passage  24 . Of course, other geometric shapes may be used for the second profiled surface  36  such as oval or elliptical shapes, so long as the second profiled surface allows the collimating chamber  80  to have an expanded diameter beyond the diameter of the inlet passage  24  and a gradual reduction in diameter to the orifice member  50 . Of course, as illustrated in  FIG. 3 , the nozzle nut  30  may be formed without the second profiled surface  36  with the collimating chamber  80  being formed primarily from the expanded region  29  of the nozzle  20  with a small portion of the collimating chamber  80  being formed by the orifice assembly  70 . The second profiled surface  36  meets the second sealing surface  32  at an inner nut edge  35 . Therefore, the inner nut edge  35  meets the inner nozzle edge  29  to make a smooth transition between the nozzle  20  and nozzle nut  30  to prevent turbulence within the collimating chamber  80 . 
         [0023]    The orifice assembly  70  which fits within the orifice cavity  38  on the nozzle nut  30  includes an orifice member  50  and a retainer  40 . The orifice member  50  is typically formed out of a hard material such as sapphire, ruby, or diamond and has an orifice passage  52  which restricts the flow of the high pressure water within the collimating chamber  80  to a very small outlet to create the high velocity water stream. The retainer  40  is formed from titanium, however alternate materials such as delrin, acetal, peek or other materials with similar properties may be used. The retainer  40  includes tabs or fingers  44  which hold the orifice member  50  in place. The tabs or fingers  44  create a spring-like effect to hold the orifice member  50  in place. While being illustrated as planar in  FIG. 2 , the orifice member  50  may have a chamber surface  51  that is not planer but is instead profiled to a beveled, oval, elliptical, or other shape. The retainer  40  includes an inner retainer surface  42  which has a geometric profile and forms part of the surface of the collimating chamber  80 . The inner retainer surface  42  is illustrated in  FIGS. 2-5  and  7 - 10  as being a beveled shape. Of course, as illustrated in  FIG. 6 , an elliptical shape, conical or other geometric shape may be used as the inner retainer surface  42 . Generally, it has been found helpful to have the retainer  40  to slope with a reducing diameter from the second profiled surface  36  to the orifice member  50 . More particularly, as the inner retainer surface  42  gets closer to the orifice, the retainer extends in thickness between the inner retainer surface  42  and the inside wall  71  of the nut  30  causing the diameter formed by a plane passing through the retainer  40  to be reduced. Therefore, when viewed in cross-section as illustrated in the figures, the retainer has a beveled surface and when viewed in whole or in perspective (not illustrated) it has a frusto-conical shape. 
         [0024]    The inventors have found that a high velocity stream exiting through the orifice passage  52  may be improved to have tighter more cohesive stream characteristics and thereby provide improved cutting performance by having the water pass through an inlet passage  24  into a collimating chamber  80  wherein the collimating chamber  80  expands in diameter over the inlet passage  24 . It is believed that the expanded diameter allows better flow movement before entering the orifice passage  52 , which helps create the improved high velocity stream exiting the orifice passage. The expanded collimating chamber allows an area for the turbulence, which is believed to be primarily caused by the velocity of the water, to subside or calm as the water is being directed to the orifice passage. The reduction in turbulence is believed to result in an improved, more cohesive water stream exiting the orifice passage. Of course, the collimating chamber  80  is formed primary without sharp edges that may cause turbulence. The collimating chamber  80  may take on almost any shape so long as it expands in diameter. More specifically, it has been found that a smooth expansion in diameter from the inlet passage with a smooth reduction in diameter to the orifice member  50  is helpful in improving the stream characteristics of the exiting high velocity water stream. Therefore, the retainer  40  has been formed with a somewhat frusto-conical or in cross-section a beveled shape to help transition the reduction in diameter as the water approaches the orifice passage  52 . The nozzle nut  30  may also facilitate this reduction in diameter. The collimating chamber  80  in the illustrated embodiment is defined by both the nozzle  20 , the retainer, and typically at least a portion of the nozzle nut  30 . 
         [0025]    The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.