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FIELD OF THE INVENTION 
       [0001]    This invention relates to a water spray assembly and to a pick box provided with such a spray assembly. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pick boxes of rotary cutting heads or drums of mineral winning machines or tunnel driving machines are frequently fitted with screw-in water spray nozzles, particularly if coal mining is involved, for a variety of well established reasons. The propensity for damage to the nozzles has led to the adoption of so-called rear-entry spray nozzles, whereby the nozzle is screwed into, and out of its receiving bore, from the rear of the pick box. 
         [0003]    Inevitably, in service conditions nozzle blockage and/or damage occurs, and whilst blockage of a few nozzles e.g. on a cutting head carrying 50-100 pick boxes and associated nozzles might be tolerated, modern mining machines monitor both water flow and pressure so that keeping the nozzles operational is critical to avoid automatic machine shut-down, and consequently nozzle removal, inspection, cleaning and/or replacement followed by replacement of a cleaned or new nozzle, in mine conditions is involved. 
         [0004]    In addition, to achieve a desired spray pattern—usually a hollow or solid cone—the spray nozzle is a precision component and hence relatively expensive if replacement, and in particular multiple replacement, is required. 
         [0005]    A basic object of the invention is the provision of an improved water spray assembly and a pick box incorporating such an assembly. 
       SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect of the invention there is provided a water spray assembly, for replaceable location in a receiving bore of a pick box, which pick box is also adapted to receive a replaceable mineral cutter pick, characterized in that the spray assembly is constructed from two components, one component being a spray body and the other component being a co-axial spray nozzle, with the two components being releasably connected together by means of screw threads, whereby the spray assembly may either be removed from, or inserted into, its receiving bore as a whole, or alternatively as individual components. 
         [0007]    According to a second aspect of the invention there is provided a pick box adapted to be secured to a rotary cutting head or shearer drum and provided with a bore in which is located a water spray assembly in accordance with the first aspect. 
         [0008]    The two-component spray nozzle assembly in accordance with the invention provides the option of removal of the entire spray assembly, as a unit, from the rear of its receiving bore in the pick box, or alternatively removal of the spray nozzle only from the front of its receiving bore, with the spray body remaining in situ. It would of course be possible to remove the spray body only from the rear end of the bore but normally this component requires no maintenance or inspection and lasts the life of the associated pick box. Thus, when the spray nozzle becomes worn or damaged, only this component requires replacement and the spray body remains in situ, available for re-use. 
         [0009]    In a first embodiment, the spray body is provided with an external thread adapted to be screwed into a portion of an internally tapped receiving bore of a pick box. 
         [0010]    To permit the spray body to be screwed into, or out of, the receiving bore in the pick box, its outer end is provided with a hexagonal socket for engagement by an Allen key, although a diametrical slot might be provided for engagement by an ordinary screwdriver blade, or a Philips or Torx recess might be provided for engagement by a Philips or Torx screwdriver. Yet again, flats might be provided for engagement by a suitable tool, or a coaxial spigot e.g. of hexagonal profile might be provided, for engagement by a hexagonal drive socket. 
         [0011]    The spray body terminates, at its outer end, in an enlarged head or collar adapted, in use, to abut a portion of the pick box and thereby limit penetration of the water spray assembly into its receiving bore. 
         [0012]    The spray body is provided, intermediate its ends, with a circumferential groove adapted to be in water flow communication with a water supply bore of the pick box, which bore is adapted to convey pressurized water from a supply source. 
         [0013]    The spray body is provided with two resilient water sealing rings, one located each side of the circumferential groove, in a sealing ring receiving groove. 
         [0014]    The spray body is provided with a gauze filter sleeve surrounding the circumferential groove. 
         [0015]    The spray body is provided with an internal, water-receiving chamber to which water is conveyed by at least one inlet bore, from the circumferential groove. 
         [0016]    The water receiving chamber is a bore, preferably a coaxial bore. 
         [0017]    The at least one inlet bore is located at such an angle as to produce a swirl in the water supply. 
         [0018]    The spray body terminates, at its inner end, in a sleeve, which is internally threaded, to receive a nose portion of the water spray nozzle, which is correspondingly externally threaded, whereby the two components may be attached to one another to form the water spray assembly, or separated from one another for removal, inspection, cleaning, re-fitting or replacement. 
         [0019]    The water spray nozzle is also provided with a water receiving chamber in fluid flow communication with that of the water spray body. 
         [0020]    The water receiving chamber of the spray nozzle is a bore, preferably a coaxial bore. 
         [0021]    The water receiving chambers of both the spray body and the spray nozzle are of the same diameter. 
         [0022]    The water receiving chamber of the water spray nozzle is provided with a discharge orifice appropriate to the water spray pattern required. 
         [0023]    The water spray nozzle is provided at its outer end with an enlarged head or collar which is externally grooved, between its ends, to receive a water sealing ring, the head or collar being adapted to enter the receiving bore, with the sealing ring resiliently engaging the receiving bore. 
         [0024]    The enlarged head or collar of the water spray nozzle is of smaller diameter than the head or collar of the spray body, such that it may penetrate a portion, such as a counter-bored portion, of the receiving bore, and hence be protected within the receiving bore. 
         [0025]    The enlarged head or collar of the water spray nozzle is provided with a hexagonal recess to be engaged by an Allen key, to enable the water spray nozzle to make screwed connection with, or disconnection from, the water spray body. Again, as with the spray body, various alternatives are possible such as flats or a Torx recess. 
         [0026]    In the connected position, a terminal inner end of the spray nozzle abuts an annular, radial face of the spray body. 
         [0027]    In a second embodiment, the water spray assembly is adapted to be retained in its receiving bore in a screwless manner, for which purpose the enlarged head or collar of the water spray nozzle, together with the enlarged head or collar of the water spray body, define abutment surfaces for location against or near to corresponding surfaces of the pick box. 
         [0028]    This embodiment avoids the need to tap the receiving bore, and simplifies fitting and removal. 
         [0029]    Although the arrangement could be such that both enlarged heads engage, and can be tightened against, surfaces of the pick box, the arrangement is such that the spray assembly can float, within limits, in the receiving bore. 
         [0030]    The enlarged head or collar of the water spray nozzle is the same diameter as that of the water spray body, so that the spray assembly is balanced and the water pressure has a neutral effect on the assembly. 
         [0031]    The receiving bore, adjacent its forward end is counter-bored to define an annular shoulder for engagement by the enlarged head of the spray nozzle. 
         [0032]    Otherwise, save for the absent external thread on the spray body, all the preferred or optional features of the first embodiment are present in the second embodiment. 
         [0033]    Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying five drawing sheets illustrating multiple embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a longitudinal sectional view through the first embodiment of water spray assembly in accordance with the first aspect; 
           [0035]      FIG. 2  is a perspective of  FIG. 1 ; 
           [0036]      FIG. 3  is a sectional side elevation through a pick box fitted with the water spray assembly of  FIGS. 1 and 2 , in accordance with the second aspect of the invention; 
           [0037]      FIG. 4  is an enlargement of the circled portion of  FIG. 3 ; 
           [0038]      FIGS. 5 and 6  correspond to  FIGS. 1 and 2 , but show the second embodiment of water spray assembly; 
           [0039]      FIGS. 7 and 8  correspond to  FIGS. 3 and 4 , but show the pick box fitted with the second embodiment of water spray assembly; 
           [0040]      FIGS. 9 ,  10 ,  11  and  12  are respectively side and end elevations of the spray body and spray nozzle, respectively, of a disassembled, fourth embodiment of water spray assembly, with sealing rings and gauze filter sleeve omitted for clarity; and 
           [0041]      FIGS. 13 and 14  are a side elevation and end elevation respectively of a spray body of a third embodiment of water spray assembly with sealing rings and gauze filter sleeve omitted for clarity. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    As shown in  FIGS. 3 ,  4 ,  7  &amp;  8  of the drawings a water spray assembly  1  located in a multi-diameter receiving bore  2  of a pick box  3  (also known as a tool holder or, in U.S. terminology, a block). 
         [0043]    In turn the pick box  3  is provided with a multi-diameter bore  4  to replaceable sleeve  5  with an enlarged collar  6  at one end adapted to make annular seating contact with a portion of the pick box  3 , and to limit the penetration of the sleeve  5  into the pick box  3 . Releasably received in the sleeve  5  by a shank  7  is a point attack, numeral cutter pick  8  having, at approximately its mid length, an enlarged collar  9  to make annular seating contact with a portion of the collar  6  of the sleeve  5 . A head  10  of the pick  8  is provided with a carbide tip  11 . Recess  12  is provided in the pick box  3  for the insertion of a drift to engage end  13  of the pick  8 , for manually levering the picks out of the sleeve  5  when pick changing is required. The pick box  3  is also provided with a bore  14  leading to the bore  2  housing the water spray assembly for the supply of pressurized water to the water spray assembly  1  to emit a conical spray  15  to a zone slightly behind the pick head  10  and tip  11 , for well understood reasons. 
         [0044]    The above is a widely used, industry standard arrangement. 
         [0045]    In accordance with the invention, and as best seen as the first embodiment of  FIGS. 1 and 2 , the second embodiment in  FIGS. 5 and 6 , the third embodiment of  FIGS. 9 to 12 , and the fourth embodiment of  FIGS. 13 and 14 . 
         [0046]    In all embodiments, like components are accorded like reference numerals. 
         [0047]    In all embodiments, the water spray assembly is constructed from two basic components being a spray body  16  and a co-axial spray nozzle  17 , with the body  16  being internally threaded at  18  and the nozzle  17  externally threaded at  19 , so that the two components may be readily screwed together, or screwed apart e.g. when it is required to remove the nozzle  17  for cleaning, usually for the removal of debris entrained in the mine water supply, whereas the body  16  would normally remain in situ for the life of the pick box  3 . 
         [0048]    In the embodiments of  FIGS. 1 to 4 , and  9  to  12  the body  16  is provided with an external thread  20  with a portion of the receiving bore  3  being internally tapped at  21 . In the embodiments of  FIGS. 1-8  and  9 - 12  the body  16  is provided with a hexagonal socket  22  for engagement by an Allen key, and in the embodiment of  FIGS. 13 and 14  with a hexagonal spigot  22 A for engagement by a suitable socket. 
         [0049]    The spray body  16  terminates, as an outer end  23 , in an enlarged head or collar  24  adapted, in use, to abut a portion of the pick box and thereby limit penetration of the water spray assembly  1  into its receiving bore  2 . 
         [0050]    The spray body  16  is provided, intermediate its ends, with a circumferential groove  25  adapted to be in water flow communication with the water supply bore  14  of the pick box  3 , and is also provided with two resilient water sealing rings  26 ,  27 , one located each side of the circumferential groove, in appropriate receiving grooves, whilst a gauze filter sleeve  28  surrounds the circumferential groove  25 . The spray body  16  is additionally provided with an internal, water-receiving chamber  29  in the form of a coaxial bore to which water is conveyed by at least one inlet bore  30  from the circumferential groove  25  which inlet bore  30  is located at such an angle as to produce a swirl in the water supply. 
         [0051]    The spray body  16  terminates, at its inner end  31 , in a sleeve  32 , which is internally threaded at  18 , to receive a nose portion  33  of the water spray nozzle  17 , which is correspondingly externally threaded at  19 . 
         [0052]    The water spray nozzle  17  is also provided with a water receiving chamber  34  in the form of a coaxial bore in fluid flow communication with the chamber  29  of the water spray body  16 , the chambers  29  and  34  being of the same diameter, whilst water receiving chamber  34  is provided with a discharge orifice  35  appropriate to the conical spray  15 , or other water spray pattern required. 
         [0053]    The water spray nozzle  17  is also provided at its outer end with an enlarged head or collar  36  which is externally grooved, between its ends, to receive a water sealing ring  37 , the head or collar being adapted to enter a portion of the receiving bore  2 , with the sealing ring resiliently engaging that portion. 
         [0054]    The enlarged head or collar  36  is of smaller diameter than the head or collar  24  of the spray body  16 , such that the head or collar may penetrate an end portion, of the receiving bore  2 , and hence be protected, as shown in  FIGS. 3 ,  4 ,  7  and  8 . 
         [0055]    The enlarged head or collar  36  is also provided with a hexagonal recess  38  to be engaged by an Allen key, to enable the water spray nozzle  17  to make screwed connection with, or disconnection from, the water spray body  16 . 
         [0056]    In the connected position of the components  16  and  17 , a terminal inner end  39  of the spray nozzle  17  abuts an annular, radial face  40  of the spray body  16 . 
         [0057]    In the embodiment of water spray assembly  1  is shown in  FIGS. 5 and 6 , adapted to be retained in its receiving bore  2  in a screwless manner, for which purpose the enlarged head or collar  24  of the water spray nozzle  16 , together with the enlarged head or collar  36  of the water spray body  17 , define abutment surfaces  41  and  42  respectively for location against corresponding surfaces of the pick box  3 . 
         [0058]    This embodiment avoids the need to tap the receiving bore  2 , and simplifies fitting and removal of the water spray assembly  1 . 
         [0059]    Although the arrangement could be such that both enlarged heads  24  and  36  engage, and can be tightened against, surfaces of the pick box  3 , the arrangement is such that the spray assembly  1  can float, within limits, in the receiving bore  2 . 
         [0060]    The embodiments of  FIGS. 9-12  also indicate the possibility of providing diametrical slots  22 B to receive an ordinary screwdriver blade. The slots  22 B may be in addition to a hexagon socket  22 , or an alternative to a hexagon socket  22 . 
         [0061]    While I have illustrated and described preferred embodiments of my invention, it is understood that these are capable of modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

Summary:
A water spray assembly for replaceable location in a receiving bore of a pick box, which pick box is also adapted to receive a replaceable mineral cutter pick, is constructed from two components. One component is a spray body and the other component is a co-axial spray nozzle. The two components are releasably connected together by screw threads, whereby the spray assembly may either be removed from or inserted into, its receiving bore as a whole, or alternatively as individual components.