Abstract:
A nozzle removal assembly including an outlet nozzle for centrifuge rotors and cooperating hand tool. The nozzle has an improved structure for facilitating the installation within and removal from a rotor wall. The centrifuge nozzle includes a body portion having inlet and outlet ends wherein the outlet end includes a placement channel. The placement channel defines a radially inwardly facing engagement surface supported externally to the rotor wall for engagement with a hand tool. The hand tool is adapted for engaging the radially inwardly facing engagement surface of the placement channel wherein both rotational and axial forces may be applied to assist in the removal of the nozzle from the rotor wall. 5

Description:
This application is a 371 of PCT/US98/21974 filed Oct. 15, 1998 which is claims benefit of provisional Appln No. 60/062,295 filed Oct. 17, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an outlet nozzle for centrifuge rotors and, more particularly, to an outlet nozzle having an improved structure for facilitating installation within and removal from a centrifuge rotor wall. 
     2. Description of the Prior Art 
     Centrifugal machines of a nozzle type typically include a rotor defining a separating chamber containing a stack of separating discs for effecting a two-fraction separation of a feed slurry. The feed slurry is separated into a heavy discharge slurry, or underflow fraction, which is delivered outside the rotor by a plurality of nozzles supported within the outer wall of the rotor. A light fraction or separated liquid is removed from the rotor by overflow from the top end of the machine. 
     To effect proper separation of the feed slurry, it is necessary to rotate the rotor within a conventional centrifugal machine at a high angular speed, typically around 3,100 rotations per minute (RPM). The high rotational speed of the rotor creates sufficient centrifugal force to separate the heavy discharge slurry outwardly to the nozzles supported within the outer wall of the rotor. The centrifugal force also necessitates that the nozzles be adequately secured to the outer wall to ensure that the nozzles remain therein during rotation of the rotor. 
     One arrangement for securing a centrifuge nozzle to a rotor wall is disclosed in U.S. Pat. No. 2,695,748 to Millard which is incorporated by reference herein. A plurality of such nozzles are mounted at regularly spaced intervals about the periphery of the rotor wall. More particularly, the rotor wall is provided with a plurality of cylindrical bores for receiving the nozzles wherein the axis of each bore is radially disposed with respect to the axis of the rotor. Means are provided for detachably securing each nozzle within the wall wherein the means consists of a lug which is formed integral with the body of the nozzle. The rotor wall is machined to provide an arcuate groove or recess within each cylindrical bore wherein the groove is dimensioned to accommodate the lug. The groove is semi-circular, and its ends open into a cavity formed within the outer surface of the rotor wall adjacent the cylindrical bore. 
     When the nozzle is positioned within the cylindrical bore such that the lug is disposed within the groove, the nozzle is securely locked to the rotor wall. When the nozzle is turned approximately 180° from this locked position, the lug is brought into registration with the cavity such that the body may be retracted from the rotor wall. A slot is provided on the end of the nozzle for engagement by a suitable turning tool, such as a screwdriver, to facilitate rotation of the nozzle. 
     During prolonged operation of the centrifuge, the nozzles often become plugged with discharge slurry thereby requiring the cleaning of the discharge orifices in the nozzles. Additionally, it is common for the nozzles to wear or erode over time due to extended contact with the abrasive discharge slurry. In order to facilitate cleaning of the plug discharge orifices, and replacement of worn nozzles, it is well known in the prior art to detachably mount the nozzles in the outer wall of the rotor. Before the Millard nozzle, the prior art means of attachment often required access to the interior of the rotor in order to install or remove the nozzles. 
     While the above mentioned Millard nozzle has addressed the task of installing new nozzles, there remains a need for improved means of removing nozzles from a rotor wall. While the Millard nozzle facilitates use of a screwdriver to impart torque and rotational movement to the nozzle, no means are provided for applying a force acting radially outwardly from the rotor along the axis of the nozzle to remove the nozzle from its receiving bore. During operation, the nozzles usually become bonded to the rotor wall by solid or liquid materials passing through the centrifuge, such that the nozzles are essentially welded in place. Additionally, sealing means, such as O-rings, provided between the nozzle and the rotor wall resist forces applied in attempts to remove the nozzles from the cylindrical bores within the rotor wall. Attempts to remove the nozzles often leads to the use of screwdrivers or other tools to pry the nozzle out of the rotor wall. The use of these tools against the rotor wall in attempt to gain leverage can result in considerable damage to the rotor wall. In extreme cases, the nozzles are bonded to the rotor wall to such an extent that metal must be welded to the top end of the nozzle so it may be pulled out by applying radially outwardly acting force. 
     Accordingly, there is a need for a centrifuge nozzle having an improved structure to facilitate installation within and removal from a rotor wall. There is a further need for a hand tool adapted for engaging the centrifuge nozzle to assist a user in installing and removing the nozzle from the rotor wall. 
     SUMMARY OF THE INVENTION 
     The present invention provides for an improvement over the prior art centrifuge nozzles by providing a nozzle removal assembly for facilitating application of both rotational and radial forces to a nozzle whereby the nozzle may be easily removed from a rotor wall. In the preferred embodiment, the nozzle of U.S. Pat. No. 2,695,748 is improved by adding a diametrically disposed placement channel within the outlet end thereof. 
     The nozzle of the present invention includes a body portion having opposing inlet and outlet ends. The body portion is adapted to be received within a cylindrical bore formed within an outer wall of a rotor wherein the longitudinal axis of the body portion is disposed radially with respect to the axis of rotation of the rotor. The outlet end of the body portion is positioned radially outwardly from the inlet end of the body portion. 
     The body portion defines an inlet bore extending radially outwardly from the inlet end and coaxial with the longitudinal axis of the body portion. An outlet bore intersects the inlet bore wherein the longitudinal axis of the outlet bore is angularly offset from the longitudinal axis of the inlet bore. The outlet bore is provided with an insert which preferably comprises an erosion and corrosion resistant material. 
     A locking mechanism, preferably a lug, is formed integral with the body portion and is diametrically opposed to the outlet bore. The lug extends outwardly from the body portion away from the longitudinal axis. The lug is adapted to be received within an arcuate groove or recess formed within the cylindrical bore of the outer wall of the rotor to prevent radial movement of the nozzle. 
     A placement channel formed within the outlet end of the body portion defines a radially inwardly facing engagement surface supported externally to the outer wall of the rotor for engagement with a hand tool. The placement channel includes a diametrically disposed slot and a bore positioned radially inwardly from the slot. The bore extends parallel to the slot wherein the lower portion of the slot intersects the bore. 
     The hand tool is adapted for engaging the nozzle of the present invention and includes a cylindrical shaft having opposing first and second ends. The first end of the shaft supports a nozzle engaging device comprising a turning member connected to a pulling member. The turning member is adapted to be slidingly received within the slot of the nozzle while the pulling member is adapted to be slidingly received within the placement bore of the nozzle. When positioned within the placement bore, the pulling member engages the radially inwardly facing engagement surface of the placement channel upon application of a radially outwardly acting force to the hand tool, resulting in a radially outwardly acting force being applied to the nozzle. The hand tool further comprises an impact mechanism including a cooperating impact disc and weight member wherein the impact disc is fixed to the shaft and the weight member is slidably received on the shaft and supported for engagement with the impact disc. 
     To remove the nozzle from the outer wall of the rotor, the pulling member of the hand tool is placed within a cavity formed within the outer surface of the outer rotor wall adjacent the nozzle. The turning and pulling members are next aligned and slid into the slot and placement bore, respectively. A rotational force, or torque, is applied to the tool to rotate the lug until it aligns with the cavity in the cylindrical bore of the rotor wall. A radially outwardly acting force is then applied to the hand tool such that the pulling member transfers the force to the radially inwardly facing surface of the placement bore thereby transmitting the radially outwardly acting force to the nozzle in a direction along its longitudinal axis. The weight member may be moved along the shaft into contact with the impact disc successively to apply successive forces of increased magnitude and short duration radially outwardly against the nozzle. Once the hand tool applies sufficient radially outwardly acting force, the nozzle is released from the rotor wall for easy removal. 
     Therefore, it is an object of the present invention to provide a centrifuge nozzle which permits the installation and removal of the nozzle from the exterior of the rotor without requiring access to the rotor interior. 
     It is another object of the invention to provide a centrifuge nozzle which greatly reduces the labor and time required for the installation and removal of the nozzle. 
     It is a further object of the present invention to provide a centrifuge nozzle which prevents damage to the nozzle and rotor upon removal. 
     It is still yet another object of the present invention to provide a nozzle removal assembly including a centrifuge nozzle and cooperating hand tool which provide for a radially outwardly acting force along the longitudinal axis of the nozzle for facilitating removal of the nozzle. 
     It is a further object of the present invention to provide a relatively simple centrifuge nozzle structure which can be readily and inexpensively manufactured. 
     It is another object of the present invention to provide a hand tool for facilitating manipulation of centrifuge nozzles. 
     Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a nozzle of the present invention; 
     FIG. 1A is an enlarged detail view of the placement channel of the nozzle of FIG. 1; 
     FIG. 2 is an end view of the nozzle of FIG. 1; 
     FIG. 3 is an end view of the nozzle of FIG. 1 disposed in an outer wall of a rotor; 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a perspective view of a hand tool of the present invention aligned with the nozzle of FIG. 1; 
     FIG. 6 is a side elevational view of the hand tool of FIG. 5; 
     FIG. 7 is a side elevational view of the hand tool of FIG. 5 engaging the nozzle of FIG. 1; and 
     FIG. 7A is an enlarged detail view of FIG. 7 illustrating the hand tool engaging the placement channel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIGS. 1-4, the nozzle  10  of the present invention includes a body portion  12  having an outer cylindrical surface  14 . The body portion  12  includes an inlet end  16  and an outlet end  18  wherein the body portion defines a longitudinal axis  20 . The nozzle  10  is adapted to be received within a cylindrical bore  22  formed within an outer rotor wall  24 . The rotor wall  24  has an outer cylindrical surface  25  and defines a portion of a rotor  26  which, in turn, forms a centrifuge of the type well known in the art. 
     With further reference to FIGS. 3 and 4, the cylindrical bore  22  within the rotor wall  24  is dimensioned to sealingly engage the body portion  12  wherein the longitudinal axis  20  of the nozzle  10  is radially disposed with respect to the axis of rotation of the rotor  26 . In the following description, unless otherwise noted, references to radial direction are with respect to the axis of rotation of the rotor  26 , in other words, along the longitudinal axis  20  of the nozzle  10 . 
     A resilient sealing member  30 , preferably an o-ring, is received within an annular groove  32  formed circumferentially around the outer surface  14  of the nozzle  10 . The resilient member  30  is dimensioned whereby it is compressed in a radial direction with respect to the longitudinal axis  20  when the nozzle  10  is received within the bore  22  whereby sealing contact is maintained between the body  12  and the surface of the bore  22 . 
     The inlet end  16  of the body portion  12  is provided with a cylindrical inlet bore  34  which is coaxially aligned with the longitudinal axis  20 . A cylindrical outlet bore  36  is provided in the outlet end  18  of the body portion  12  wherein the outlet bore  36  intersects the inlet bore  34  to provide fluid communication therebetween. A longitudinal axis  38  of the outlet bore is angularly offset from the longitudinal axis  20  of the inlet bore. The outlet bore  36  is preferably fitted with an insert  40  which comprises an erosion and corrosion resistant material, such as tungsten carbide or ceramic. It may be held in place by suitable means such as soldering, brazing or cementing. 
     In operation, centrifugal force imparted on a feed slurry within the rotor  26  causes a heavy discharge slurry, or underflow fraction, to be delivered to the inlet bore  34 . The heavy discharge slurry continues through the inlet bore  34  and through a passageway  42  defined by the insert  40  to a position outside of the rotor  26 . 
     In the preferred embodiment of the nozzle  10 , an outlet end face  44  of the body portion  12  is positioned flush with the outer cylindrical surface  25  of the rotor wall  24 . A cavity  46 , having a surface  47 , is provided within the outer surface  14  of the rotor wall  24  to enable free discharge of the heavy discharge slurry from the insert  40  of the nozzle  10 . As is well known in the art, the discharge slurry is directed backwardly with respect to the direction of rotation of the rotor  26 . 
     A locking mechanism, preferably a lug  48 , extends radially outwardly with respect to the longitudinal axis  20  from the body portion  12  and is integral therewith. The lug  48  is preferably diametrically opposed to the outlet bore  36  (FIG.  4 ). The rotor wall  24  is machined to provide an arcuate groove or recessed portion  50  for accommodating the lug  48 . The groove  50  defines a semicircle of approximately 270° wherein its ends are open to the cavity  46 . As shown in FIG. 3, when the lug  48  is positioned within the groove  29 , the nozzle  10  is securely locked within the rotor wall  26  wherein radial movement along the longitudinal axis  20  is prevented. However, when the body  12  is rotated approximately 180°, as indicated by arrow  51 , from the position shown in FIG. 3, the lug  48  no longer locks the nozzle  10  in place. 
     Returning to FIGS. 1 and 2, a diametrically disposed placement channel  52  is provided within the end face  44  of the body portion  12 . The placement channel  52  is preferably defined by a slot  54  and a bore  56  positioned radially inwardly along the longitudinal axis  20  of the nozzle  10  relative to the slot  54 , such that the bore  56  is positioned closer than the slot  54  to the inlet end  16 . The slot  54  opens toward the outlet  18  and has a width w. In the preferred embodiment, the slot  54  perpendicularly intersects the longitudinal axis  20 , i.e., extends transversely to the body portion  12 . 
     The placement bore  56  extends parallel to the slot  54  wherein the slot  54  and placement bore  56  intersect to thereby define the placement channel  52 . The placement bore  56  is preferably cylindrical in nature and has a diameter of d 1  which is greater than width w of the slot  54 . It will be appreciated that while the placement bore  56  preferably has a substantially circular cross-section, other cross-sections may be substituted therefor. More particularly, the placement bore  56  may have a rectangular or triangular cross-section. 
     The placement bore  56  includes reentrant edges defining a pair of substantially radially inwardly facing engagement surfaces  58  supported for engaging a hand tool  100 , as will be described in detail hereinafter. The engagement surfaces  58  face inwardly toward the inlet end  16  of the body portion  12 . Turning to FIGS. 3 and 4, the radially inwardly facing engagement surfaces  58  have at least one end located radially outside of an adjacent portion of the outer surface  47  of the cavity  46 . The placement channel  52  has one end open to, or in communication with, the cavity  46  wherein clearance is provided adjacent the engagement surfaces  58  for access by the hand tool  100 . More particularly, both the slot  54  and placement bore  56  each have at least one end opening to the outer surface  14  of the body portion  12 . 
     FIG. 5 illustrates a hand tool  100  which together with the nozzle  10  of the present invention defines a nozzle removal assembly. The hand tool  100  is adapted to provide both torque, or rotational force, and radial force acting along the longitudinal axis  20  of the nozzle  10  for assisting in the assembly and disassembly of the body portion  12  with the cylindrical bore  22 . The hand tool  100  includes a cylindrical shaft  102  having first and second ends  104  and  106 . The first end  104  of the shaft supports a nozzle engaging device  108  including a turning member  110  and a pulling member  112 . The second end  106  of the shaft is connected to a handle  114  adapted to be gripped by the user. 
     An impact disc  116  is rigidly fixed to the shaft  102 . A weight member  118  is slidingly received on the shaft  102  for movement there along in the direction of arrow  119  in FIG.  5 . More particularly, the shaft  102  is received within a cylindrical bore  120  formed within the weight member  118 . The impact disc  116  and weight member  118  together define an impact mechanism  122  adapted to provide additional outward pulling force to assist the user in dislodging the nozzle  10  from the rotor wall  24 . 
     Turning now to FIGS.  1 A and  6 - 7 A, the turning member  110  of the nozzle engaging device  108  is adapted to be received within the slot  54  of the nozzle  10 . The turning member  110  comprises a substantially planar plate  124  having a thickness t which is less than the width w of the slot  54  such that the plate  124  may be slidingly received within the slot  54 . A first end  126  of the plate  124  supports the pulling member  112 , while a second end  128  of the plate is fixed to the shaft  102 . 
     In the preferred embodiment, the pulling member  112  comprises a cylindrical rod  130  adapted to be slidably received within the placement bore  56 . The diameter d 2  of the cylindrical rod  130  is less than the diameter d 1  of the placement bore  56 . However, the diameter d 2  of the rod  130  is greater than the width w of the slot  54  such that the rod  130  cannot pass between opposite side edges  132  of the slot  54  and instead engages the engagement surfaces  58 . 
     Operation will now be described with respect to removing a nozzle  10  locked by the lug  48  within the rotor wall  24 . It should be appreciated that a similar operation is utilized to install the nozzle  10  within the bore  22  of the rotor wall  24 . 
     First, the user positions the tool  100  within the cavity  46  of the rotor wall  24  adjacent the outlet end  18  of the nozzle  10 . Next, the tool  100  is aligned with the placement bore  56  and slot  54  of the nozzle  10 . More particularly, the plate  124  and rod  130  are axially aligned to be received within the slot  54  and placement bore  56 . The plate  124  and rod  130  are then slidably received within the slot  54  and bore  56 , as illustrated in FIG.  7 . 
     The user next rotates the tool  100  by gripping and turning the handle  114  to apply a torque to the nozzle  10  as illustrated by arrow  136  in FIG.  7 . The plate  124  engages one of the slot edges  132  thereby transferring the applied torque and rotating the body  12  in a the direction of arrow  51  around axis  20  as shown in FIG.  3 . 
     When the lug  48  has been rotated approximately 180°, the operator applies a radially outwardly acting force to the tool  100  by pulling the handle  114  as illustrated by arrow  138  in FIG.  7 . This force is transferred along longitudinal axis  20  thereby causing the rod  130  to engage the radially inwardly facing engagement surfaces  58  of the placement bore  56 . The axial force is transferred to the body portion  12  of the nozzle  10  thereby breaking any bonds formed between the body portion  12  and the rotor wall  24  by dried slurry or other materials within the rotor  26 . The nozzle  10  may then be removed from the rotor wall  24  for repair or replacement. It should also be noted that the rod  130  by engaging the surfaces  58  provides for easy handling of the nozzle  10  once it has been removed from the rotor wall  24 . 
     Should the nozzle  10  be particularly stubborn and resist being removed because of strong bonds between the rotor wall  24  and the body portion  12 , the impact mechanism  122  may be utilized. The operator moves the weight member  118  along the shaft  102  radially inwardly towards the nozzle  10  and then quickly brings the weight member  118  back to the impact disc  116  for contact therewith. By impacting the impact disc  116  with the weight member  118  in rapid succession, successive spikes of increased force in the radially outwardly direction along the longitudinal axis  20  are applied to the body portion  12  thereby breaking the bonds securing the body portion  12  within the rotor wall  24 . 
     While the form of apparatus herein described constitutes a preferred embodiment of this invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.