Abstract:
Apparatus is provided for facilitating the loading of a hollow cylindrical drum, for example, an image-recording drum in an electrostatographic printer or the like, onto a rotatably driven drum axle having a free end extending outwardly in a cantilever manner from a support frame and having a longitudinally-extending axis of rotation. According to a preferred embodiment, such apparatus generally comprises a plurality of slide mechanisms disposed at equal distances from each other and from the intended axis of drum rotation. Each of the slide mechanisms comprises a pair of elongated slide members extending parallel to said axis of rotation, one of the slide members of each of each pair being rigidly supported by said drum axle, and the other slide members of each pair being slidably mounted on the rigidly supported slide members for movement parallel to the drum axis. The slidably mounted slide members are operable to collectively support the drum from within for axial movement between a drum-loading position axially spaced from the drum axle and a loaded position atop the drum axle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Reference is made to the commonly assigned U.S. patent application Ser. No. 09/574,425, filed on May 19, 2000, and entitled “Document Printer/Copier with Decoupleable Drum-Support Member” (now U.S. Pat. No. 6,263,177, issued on Jul. 17, 2001), and U.S. application Ser. No. 09/877,777, filed on Jun. 8, 2001, now U.S. Pat. No. 6,484,002 a Continuation-in-Part thereof, the disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to improvements in apparatus for loading (and unloading) a hollow drum onto (and from) a cantilever-mounted axle adapted to support the drum for rotation. The apparatus of the invention is particularly useful for loading and unloading an image-recording or image-transfer drum in an electrostatographic printer/copier in which minimal clearance is provided between the drum surface and the various processing stations associated with the electrostatographic imaging process. 
     BACKGROUND OF THE INVENTION 
     Referring to FIGS. 1-3, the above-referenced U.S. application Ser. No. 09/574,425 discloses an electrostatographic document printer  10  that comprises a pair of confronting, cantilever-mounted drums  12  and  16 . Drum  12  typically comprises a hollow metal cylinder having a photoconductive outer layer  14  and serves to record images, in a conventional manner, via the well-known electrostatographic process. Briefly, as drum  12  rotates counter-clockwise, layer  14  is uniformly charged at a primary charging station  20 , imagewise exposed with actinic radiation at an exposure station  22  to produce a charge image on layer  14 , and subjected to toner particles that selectively adhere to the charge image to render such image visible. Continued rotation of drum  12  results in the intermediate transfer of the previously formed toner image to a non-stick outer surface  18  of drum  16 . Thereafter, the image-recording surface of drum  12  is cleansed at cleaning stations  25  and  26 , readying the drum for subsequent image recording. Meanwhile, the toner image on drum  14  is transferred to an image-receiver sheet (not shown), and the drum surface  18  is cleaned at a cleaning station  28 . As will be appreciated, all of the aforementioned processing stations are precisely positioned in close proximity to the outer surfaces of the drums  12  and  16 , and great care must be taken in removing the drums for servicing lest the drum surfaces be damaged by the hardware of the processing stations. 
     In the printer described above, drums  12  and  16  are rotatably supported by a pair of axles A 2  and A 3 , respectively, that extend outwardly, in a cantilever fashion, from the rear mech plate RP of the printer support frame. Referring to FIG. 2, a solenoid-operated drum-support mechanism  32  serves to provide support for the free ends of axles A 2  and A 3  during drum rotation. Such support mechanism is movably mounted on a pivot mount  50  for movement between an operable position in which it supports both drum axles A 1  and A 3 , and a stand-by position (shown in FIG. 2) in which it is sufficiently spaced from the drums to enable axial movement of the drums for removal and servicing. In use, the image-recording drum  12  is supported at its opposite ends  12 A and  12 B by a pair of gudgeons  40  and  42  that are releasably press fit into the respective ends of the drum. The rear gudgeon  40  is rotatably mounted directly on axle A 2 , whereas the front gudgeon  42  is rotatably mounted on a stub axle assembly A 1  that, in use, is releasably connected to the free end of axle A 2 . When so connected, beveled edges on each gudgeon cooperate with beveled edges at each drum end to center the drum on the longitudinal axis of axle A 2 . As disclosed in the aforementioned application, when axle assembly A 1  is disconnected from axle A 2 , drum  12  will slide off its supporting gudgeons and will be free to move axially, through an opening in the printer&#39;s front mech plate FP for servicing. 
     As best shown in FIG. 3, careful axial movement of drum  12  from the printer frame is facilitated by a drum-loading/unloading structure  100  that is supported by axle A 2  within the drum interior. The drum loading/unloading structure comprises a pair of discs  102 ,  103  and a plurality of interconnecting rods  104 . Discs  102 ,  103  are provided with concentrically arranged central apertures  102 A,  103 A, each being adapted to receive and slide upon axle A 2 . Rods  104  are mutually parallel with each other and with the longitudinal axis of axle A 2 . The most radially outward surface of each rod extends slightly outside the perimeter of each of the supporting discs and lies on a circle having a diameter slightly less than the inside diameter of drum  12 . The respective lengths of the rods, including their extensions  104 A that extend beyond disc  103 , are slightly less than the length of drum  12 . Thus, upon removing gudgeon  42  from the end  12 B of the drum  12 , it will be appreciated that the drum will slide off the beveled edge of gudgeon  40  and thereby be collectively supported by several of the underlying rods  104  of the drum-loading/unloading structure. To remove the drum from axle A 2 , the operator grasps handles  106  mounted on disc  103  and exerts an axially outward force. 
     While the drum-loading/unloading apparatus described above is useful in reducing any damage to the drum surface as the drum is removed from the printer frame, it is problematic in certain respects. For example, it will be appreciated that axial movement of the drum will be supported by axle A 2  only so long as the central aperture  103 A of disc  103  maintains contact with the axle A 2 . Once contact is lost as the drum continues to move axially outward, it is up to the operator to assure that the drum axis remains substantially co-linear with the axis of axle A 2 ; otherwise, the relatively delicate outer surface of the drum may physically contact the hardware of the various processing stations of the printer and cause damage. Ideally, the drum should be mechanically supported until the drum clears all potentially harmful surfaces as it moves axially from the printer frame. A further problem associated with the drum loading/unloading apparatus of the type described is that, being incapable of providing support for the drum at all times during of its axial movement, relatively slight defects in the drum surface cannot be addressed without totally removing the drum from the printer frame. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing discussion, an object of the present invention is to provide an improved drum-loading/unloading apparatus of the type described, one that is substantially more robust than the prior art apparatus, and one that overcomes the aforementioned problems of the prior art apparatus. 
     According to the invention, an improved apparatus is provided for facilitating the loading and unloading of a hollow cylindrical drum, for example, an image-recording drum in an electrostatographic printer or the like, onto a drum axle having a free end extending outwardly in a cantilever manner from a support frame and having a longitudinally-extending axis about which the drum is adapted to rotate. According to a preferred embodiment, the apparatus of the invention comprises a plurality of telescoping slider mechanisms disposed at equal distances from each other and from the axis of the drum axle. Each of the slider mechanisms comprises a pair of elongated slide members extending substantially parallel to the drum axle. One of the slide members of each pair is rigidly supported by the drum axle, and the other slide member of each pair is slidably mounted on the rigidly supported slide member for movement parallel to the drum axle axis. The slidably mounted slide members of each pair cooperate to support the drum from within for axial movement between a drum-loading position axially spaced from the drum axle, and a loaded position atop the drum axle. Preferably, a total of three slider mechanisms are used to slidably support the drum, and each the slide mechanisms comprises a common drawer slider mechanism of the type commonly used to support a drawer in a cabinet for movement between a closed and open position. Preferably, a latching mechanism is provided to selectively latch the slidably mounted slide members in their respective drum-loading positions to facilitate loading of a drum onto the slide members. 
     The drum-loading/unloading apparatus of the invention is substantially more robust in construction than the aforementioned prior art structure, and it provides full support for the drum during axial movement of the drum between its operating position and a service position substantially spaced from the drum&#39;s operating position, such as outside the support frame of the drum-utilization device. Thus, the drum may be handled and worked on, e.g., for cleaning purposes, without physically removing the drum from the loading/unloading apparatus. Further, the loading aid is significantly less costly to assemble and install in the supporting instrument. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention and its advantages will be better understood from the ensuing detailed description of preferred embodiments, reference being made to the accompanying drawings in which like reference characters denote like parts. 
     FIG. 1 is a side elevation illustration of an electrostatographic printer of the type in which the invention is particularly useful; 
     FIG. 2 is an exploded view of a portion of the FIG. 1 apparatus; 
     FIG. 3 is an exploded perspective view of a drum-loading/unloading apparatus structured in accordance with the prior art and discussed above; 
     FIG. 4 is a side elevation of a drum-supporting assembly incorporating the present invention; 
     FIG. 5 is a cross sectional view of the FIG. 4 apparatus taken along the section line  5 — 5 ; 
     FIG. 6 is an exploded view illustrating the FIG. 4 drum-supporting assembly; 
     FIG. 7 is a perspective view of the drum loading/unloading apparatus of the invention with the drum-supporting sliders in a retracted state; 
     FIG. 8 is an end view of the FIG. 7 apparatus; 
     FIG. 9 illustrates the FIG. 7 apparatus in its extended position, ready to receive a drum for loading; 
     FIG. 10 is a cross-sectional view of a drum assembly having a latching mechanism for selectively latching the slidably mounted slide members of the drum loading/unloading apparatus in a drum-loading position; and 
     FIGS. 11 and 12 are end views of the drum-loading apparatus showing the latching mechanism in latching and unlatched positions, respectively. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 4-9, a drum-supporting assembly  110  embodying the drum-loading/unloading apparatus of the present invention is shown to comprise a compound axle assembly  111  composed of a pair of axle sub-assemblies A 1  and A 2  that are releasably joined together at opposing ends. Axle sub assembly A 2  comprises an axle member  112  that supports a pair of bearing assemblies B 1  and B 2 , by which the axle member is supported for rotation, and a disk-shaped rear gudgeon  40  that serves, as discussed above, to support one end of a hollow drum D (shown in FIG. 9) so that the drum&#39;s longitudinal axis is substantially co-linear with the longitudinal axis A′ of axle member A 2 . As shown, gudgeon  40  has a beveled inside rim edge  40 A adapted to mate with a similarly shaped edge on a drum to be supported. In use, the outer races of bearings B 1 ,B 2  are rigidly clamped to a support plate (not shown) from which axle  112  extends in a cantilever fashion. The forward axle sub-assembly A 1  comprises the front drum-supporting gudgeon  42  and an internal releasable coupling assembly  43  that enables the axle subs-assemblies A 1  and A 2  to be either rigidly connected together or separated. The front gudgeon  42  is a one-piece structure comprising a front axle portion  114 , a sleeve portion  115  having a central bore adapted to receive the forward portion of axle member  112 , and a flange portion  116  having a beveled rim  116 A adapted to engage, support and center with respect to axis A′ one end of a drum D. Activation of the coupling  43  is achieved by rotation of a threaded rod  117  that engages a threaded bore formed in the most forward end of axle member  112 . Axle portion  114  of gudgeon  42  supports a bearing assembly B 3  by which the axle member is rotatably supported on a movably-mounted front drum support (shown in FIG. 2 as member  32 ). As described in the above-referenced U.S. application Ser. No. 09/574,475, such movably-mounted front drum support is, in use, releasably engaged with the outer race of the bearing assembly B 3  to provide support for the drum as it rotates within the bearing assembly. Upon de-coupling the front drum support  32  from the bearing assembly, the front drum support can be moved to a location sufficiently remote from the drum to enable the front axle assembly A 1  to be de-coupled and removed from the rear axle assembly A 2 , thereby allowing the drum to be moved axially forward and, eventually, be removed from the rear axle assembly A 2  for servicing and/or replacement. 
     Now in accordance with the present invention, the compound axle assembly  111  supports a drum-loading/unloading apparatus  120  that greatly facilitates the loading and unloading of a drum onto the axle assembly. Apparatus  120  is rigidly connected to, and is thereby supported by, axle member  112 , and, preferably, such apparatus extends fully between the gudgeons  40  and  42  when a drum is supported by such gudgeons. Apparatus  120  comprises a plurality (preferably three) of elongated slide mechanisms  122 , each extending parallel to the axle axis A′ and being equally spaced from each other, as well as from the axle axis. The slide mechanisms  122  are supported by a pair of spider-shaped brackets  124 , each bracket having a central circular opening  124 A adapted to slide onto the major cylindrical portion  112 A of axle member  112 , and be fixed thereto (to prevent axial movement) by a set screw  126  or the like, shown in FIG.  7 . Each of the spider brackets  124  has a plurality of outwardly-extending legs  128 , equal in number to the number of slide mechanisms  122 , and each leg is rigidly connected to a non-moving portion of the slide mechanism, as explained below. A third spider bracket  130  having a central circular opening  130 A and a plurality of outwardly-extending legs  132  is also connected to the slide mechanisms and provides forward support. Unlike brackets  124 , however, bracket  130  is slidably supported by the sleeve portion  115  of gudgeon  42  so that the latter may be de-coupled from axle assembly A 2  without disturbing the drum-loading/unloading apparatus. 
     Referring to FIGS. 7-9 which best illustrate the details of the apparatus of the invention, each slide mechanism  122  preferably comprises a conventional “drawer slide” mechanism of the type commonly used to support a drawer as it moves between open and closed positions in a cabinet or the like. Such a mechanism comprises an elongated channel-defining member  122 A and an elongated slider member  122 B that is captured by and is free only to slide within the channel defined by member  122 A. The channel-defining member  122 A of each slide mechanism is rigidly connected to one of the legs  128  of the spider brackets  124  by a flange  128 A extending at a right angle from the end portion of such legs. Thus, in the embodiment shown, each slide mechanism  122  is rigidly supported at two locations along its length atop, and at a fixed location on, axle portion  112 A by virtue of the rigid connection of at least one of the spider brackets  124  to the axle via set screw(s)  126  that passes through a circular flange on at least one of the brackets and engages the underlying axle. One end of each of the slider members  122 B is rigidly connected to the third spider bracket  130  via a suitable flange and screw connection  132 A at the respective ends of the spider legs  132 . As noted above, the circular central opening  130 A of spider bracket  130  is adapted to receive the sleeve portion  115  of the forward gudgeon  42  when the latter is positioned on the drive shaft  112 . Thus, the parallel and physical relationship of the slider members relative to their respective support channels is maintained throughout the linear movement as the slider members from their “home” or retracted positions (shown in FIGS. 4-7) and their fully extended positions, as shown in FIG.  9 . 
     As best shown in FIG. 8, each of the slider members  122 B has a portion P that extends radially outward relative to axle axis A by a distance slightly greater than the most radially outward portion P′ of the channel-defining members  122 A. Each of the portions P lie on a circle having a diameter slightly smaller than the inside diameter of drum D. Thus, as the axle assembly A 1  is de-coupled from axle assembly A 2  and the front gudgeon  42  is removed from its engagement with the front edge of the drum, the drum will slide (incrementally) forward, off the beveled edge  40 A of rear gudgeon  40 ; having done so, the drum will be totally supported by at least two of the slider members  122 B. To remove the drum from its position atop the axle assembly A 2 , the operator need only lightly grasp the forward edge of the drum and pull it forward. As a result, the drum will slide axially forward, being supported all the way by the underlying slider members that are traveling within their associated channel-defining members  122 A. Thus, in contrast with the afore-described drum-loading apparatus of the prior art, there is no need for the operator to physically support the drum during a major portion of its axial travel, and any potential damage to the drum surface is minimized. 
     To facilitate the loading or re-loading of a drum onto the loading/unloading apparatus  120  while the slider members  122 B are in their respective extended positions (shown in FIG.  9 ), it is preferred that a latching mechanism be provided to selectively prevent axial movement of the slider members (toward their home positions) while the drum is being manually positioned on the ends of the slider members and urged axially towards a position in which the drum is fully supported by the slider members. According to a preferred embodiment, such latching mechanism (shown in FIG. 10) comprises an elongated, latch-actuating rod  140  that is supported in a position generally parallel to axis A′ by one of the slider members  122 B and by the spider bracket  130 . More specifically, rod  140  is supported for rotation about its longitudinal axis by a mounting bracket  142  attached near the rearward end of one of the fixed slider members  122 B, and by a hole  130 B formed in an arm of the movable spider bracket  130 . Optionally, the rod  140  may be further supported by a disk  141  positioned at the front end of the drum, the outer circular edge such disk serving to facilitate the initial loading of a drum onto the front edges of the extended slider members  122 B. The rotational position of rod  140  within suitable apertures formed in the support brackets is controlled by an integral handle  140 A extending perpendicular to the rod axis. An latching member  144  extends radially outward from the distal end (opposite the handle end) of the rod, and a torsion spring  146  wrapped about rod  140  serves to bias the rod for rotation in a direction such that the latching member is normally positioned behind the innermost edge (closest to rear gudgeon  40 ) of the stationary channel-defining member  122 A associated with the slider member  122 B that supports the latch-actuating rod. 
     Thus, when the slider member  122 A that supports rod  140  is in its home position, i.e., totally within its associated channel-defining member  122 B, the drum-loading/unloading apparatus is latched in place. Upon manually rotating the rod via handle  140 A in a counter-clockwise direction, as viewed from the front end of the drum assembly, the latch member  144  will move against the opposing force of the torsion spring until clears the edge of the fixed slider member  122 A. In this position, the movable slider members  122 B of the drum-loading/unloading aid are free to be withdrawn to their fully extended positions. As the movable slider members  122 B are withdrawn, latch  144  rides on the longitudinal edge surface of one of the fixed slider members  122 A until the movable members  122 B reach their fully extended positions, whereupon the latch member moves off such edge, under the force of the torsion spring, and falls to a latching position behind the outermost end edge of the fixed slider member. During loading a drum onto the extended slider members, the movable slider members will, due to the latching mechanism, remain stationary until the drum is fully loaded onto the loading/unloading aid. To reposition the drum onto the rear axle assembly A 2 , the operator again rotates the rod  140  counter-clockwise, thereby moving the latching member away from its latching position, and then slides the drum and its underlying loading/unloading aid toward the home position. By virtue of the latching mechanism, there is no need to manually hold the slide members in their extended position while attempting to load the drum onto the loading/unloading aid. 
     The invention has been described with reference to a particularly preferred embodiment. It will be apparent, however, that certain modifications can be made without departing from the spirit of the invention, and such modifications are intended to be protected by the following claims. 
     PARTS LIST 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 10 
                 printer 
               
               
                 12 
                 image-recording drum 
               
               
                 12A and 12B 
                 beveled drum edges 
               
               
                 14 
                 photoconductive surface 
               
               
                 16 
                 image-transfer drum 
               
               
                 18 
                 non-stick sleeve 
               
               
                 20 
                 corona charging station 
               
               
                 22 
                 exposure station 
               
               
                 24 
                 development station 
               
               
                 25 
                 cleaning station 
               
               
                 26 
                 cleaning station 
               
               
                 28 
                 image-transfer drum cleaner 
               
               
                 32 
                 movable drum support 
               
               
                 40 
                 rear drum gudgeon 
               
               
                 42 
                 front drum gudgeon 
               
               
                 50 
                 pivot mount 
               
               
                 RP 
                 rear mech plate 
               
               
                 FP 
                 front mech plate 
               
               
                 A1, A2, A3 
                 axle assemblies 
               
               
                 A 
                 drum axis 
               
               
                 A′ 
                 axle axis 
               
               
                 100 
                 drum-loading aid (prior art) 
               
               
                 102, 103 
                 disks 
               
               
                 104 
                 rods 
               
               
                 104A 
                 rod extensions 
               
               
                 106 
                 handles 
               
               
                 110 
                 drum supporting apparatus 
               
               
                 111 
                 axle member of A2 
               
               
                 112 
                 major portion of axle member 111 
               
               
                 112A 
                 surface of 112 
               
               
                 114 
                 axle member of A1 
               
               
                 115 
                 collar portion of A1 
               
               
                 122 
                 slide mechanisms 
               
               
                 122A 
                 channel-defining slide member 
               
               
                 122B 
                 slider member 
               
               
                 P 
                 outermost portion of 122B 
               
               
                 P′ 
                 outermost portion of 122A 
               
               
                 124 
                 spider brackets 
               
               
                 124A 
                 central opening in brackets 124 
               
               
                 126 
                 set screw 
               
               
                 128 
                 bracket legs 
               
               
                 128A 
                 flange on bracket legs 
               
               
                 130 
                 third bracket member 
               
               
                 130A 
                 central opening in bracket 130 
               
               
                 130B 
                 hole in bracket leg 
               
               
                 132 
                 leg portions of bracket 130 
               
               
                 140 
                 latch rod 
               
               
                 141 
                 disk 
               
               
                 140A 
                 handle 
               
               
                 142 
                 bracket 
               
               
                 144 
                 latching member 
               
               
                 146 
                 torsion spring 
               
               
                 D 
                 drum