Abstract:
The invention relates to a material conveying assembly ( 10 ) of the kind comprising an outer tubular casing ( 11 ) and a rotary feed screw ( 12 ) mounted within the casing ( 11 ) on a tubular drive shaft ( 13 ), wherein the intake end of the auger is provided with a replacement intake auger sub-assembly ( 14 ) comprising flexible helical flighting ( 15 ) freely rotatably mounted on a drive shaft extension ( 17 ) which is connected to the main drive shaft ( 13 ) and a clutch device ( 30 ) which drivingly connects the intake flighting shaft portion ( 25 ) to the drive shaft extension ( 17 ). The clutch device is arranged so that it will automatically disengage drive to the shaft portion ( 25 ) in the event of an overload occurring. A soft pliable extension sleeve ( 19 ) is co-axially fitted over the open leading end of the outer casing ( 11 ) and is arranged to encircle a portion of the intake flighting ( 15 ). The extension sleeve ( 19 ) being easily deformable, in combination with the resilient flexible flighting ( 15 ) significantly reduces the likelihood of any injury being suffered by an operator in the event of one of his or her limbs being caught in the intake flighting.

Description:
This invention relates to new and useful improvements to augers, in particular an auger used for conveying grain and other particulate material. More specifically the invention relates to a material conveying auger having an improved intake designed for increased safety of persons working in the near vicinity thereof. 
     Conventional grain augers comprise a tubular or cylindrical rigid outer casing or housing in which is housed a rotary feed screw having a constant diameter rigid metal helical flight which extends from an intake at one end of the casing to a discharge end at the opposite end of the casing. In many instances, the intake end of the auger, ie where the grain is fed into the auger, a portion of the auger flighting is exposed and projects outwardly from the outer casing, with the outer end of the main auger shaft being journalled in an end bearing assembly which itself is supported by a plurality of circumferentially spaced longitudinal support rods which are fixed to the casing and project beyond the open intake end of the casing. The projecting support rods provide partial shielding around the intake end of the auger for preventing a limb, eg a hand or leg, being accidentally caught in the auger intake end flighting. However, it is not uncommon for an operator of a grain auger to lose a finger, or even part of an arm, as a result of insufficient safety guards at the auger intake end during operation of the auger. It will be appreciated that the intake flighting where it enters the open end of the rigid metal outer casing and the end edge of the rigid casing effectively function as a slicer and will readily slice an obstruction, eg a finger, which becomes trapped therebetween, especially when the edges of the metal casing and metal flighting become sharpened through wear from use. 
     It is also known for manufacturers of grain augers to fit protective guards or shields over the auger intake end in order to minimise the likelihood of injury to the operator; however, it has been found that the use of such guards around the intake end of the auger interferes with the pick-up and conveyance of the material which reduces the working capacity of the auger. As a result, operators quite often remove the shields or guards, and of course, once removed, there is the potential for a serious injury. 
     A further problem with existing farm augers is that there is no safeguard for stopping the rotation of the flighting in the event of an obstruction engaging within the intake end or the intake end becoming choked with material, eg fertiliser. In cases where the obstruction is a foreign object such as a fertiliser bag, the object can be conveyed into the section of the auger casing where it can be difficult to remove should jamming of the auger occur. It would be advantageous if the auger was designed so that its intake end flighting stopped rotating in an overload situation, while still permitting the downstream portion of the auger to continue rotating so as to help clear the overload before the intake flighting resumed its rotation. In the situation where the obstruction is a person&#39;s limb, eg leg or arm, it is vital that drive to the intake end flighting cease virtually instantaneously. 
     It is an object of the present invention to provide an improved auger assembly which is designed so that the likelihood of any serious injury being suffered by an operator (or any other person in the vicinity of the auger intake end) in the event of his or her leg or arm (or a part thereof) accidentally being caught in the auger intake end, is drastically reduced. 
     It is another object of the present invention to provide an improved auger assembly which incorporates a safety overload prevention device which will operate to disengage drive to the intake flighting should an overload occur, eg as a result of an obstruction, such as a leg or arm, becoming trapped in the auger intake. 
     It is a still further object of the present invention to provide a safety clutch mechanism for the intake end of an auger assembly which is easy to assemble and maintain and which an be easily disengaged for servicing purposes. 
     It is a still further object of the present invention to provide a replacement auger intake section which can be readily fitted to an existing auger for improving its operating safety by minimising the risk of injury being suffered by an operator should one of his limbs, or a part thereof, become caught in the auger intake end, and one which allows an operator to readily change the intake flighting where a different pitch is required. 
     It is yet a still further object of the present invention to provide an improved auger intake unit which is simple in construction, economical to manufacture and .which does not materially affect the capacity of the auger to convey material therealong. 
     According to one aspect of this invention therefore, there is provided an improved material conveying auger assembly of the type which includes an elongate tubular casing having an intake end and a discharge end, a drive shaft extending coaxially through the casing and journalled for rotation therein, and helical flighting on said drive shaft, the improvements comprising (i) a replacement auger intake section adapted for connection to the drive shaft so as to rotate therewith, said intake section having helical flighting formed of resilient flexible wear resistant material and (ii) a soft, pliable tubular extension sleeve attachable to the intake end of said casing so as to project axially outwards therefrom, said extension sleeve being arranged to encircle at least a portion of said intake section and its flighting. 
     Preferably the intake end flighting is formed of polymeric material, eg polyurethane, having a Shore “A” hardness value in the range 60-100, most desirably a value of around 90. 
     Desirably the extension sleeve is formed of a rubber or rubber-like material having a Shore “A” hardness value in the range 35-60, most desirably a value of 45. Generally, the extension sleeve will be formed of a durable material which is quite softer and more pliable than the material of the intake flighting but at the same time possess sufficient radial stiffness to support itself under operating conditions. 
     Preferably the extension sleeve is slidably fitted over the open intake end of the casing and is clamped thereto by releasable clamping means. 
     The resiliently deflectable intake end flighting and the soft rubber extension sleeve at the intake end of the auger casing eliminate the sharp metal edges normally present in a conventional auger and thereby greatly minimise the likelihood of a serious injury being suffered should a person&#39;s limb or limbs become caught in the intake end of the auger. With the arrangement of the present invention, it has been shown that even with the auger rotating at speeds in the order of 400-500 rpm, a person&#39;s fingers can be trapped in the intake end flighting and subsequently withdrawn therefrom without serious injury or damage. The soft rubber sleeve portion of the auger casing at the intake end thereof, being easily deformable, will allow the fingers, caught by the intake flighting to be pulled out without serious consequences. 
     Preferably the extension sleeve has associated therewith a feed tray portion which projects axially away from the outer end of the sleeve and extends along the underside of the intake section. The tray may be a separately formed member and have its own attachment means for attaching it to the auger casing, or the tray can be integrally formed with the extension sleeve. 
     According to another aspect of the invention, there is provided a safety clutch mechanism arranged to drivingly connect the auger intake flighting section to the main auger shaft so that the intake flighting, under normal operating conditions, will rotate simultaneously with the main auger shaft or, in the event of an obstruction becoming caught in the intake end of the auger, drive to the intake flighting will be disengaged and the intake flighting will be stationary relative to the main auger shaft. 
     Preferably the clutch mechanism is of the dog clutch type and comprises a clutch driver element which is adjustable to allow axial alignment of the flightings and then locked in position by a securing bolt so that it is fast with the main drive shaft, and a driven clutch plate element axially movable with respect to the driver element for engaging and disengaging the drive. 
     Preferably, the clutch mechanism is constructed and arranged so that when an overload occurs, the driven clutch plate element will disengage from its driver element and drive to the auger intake flighting will cease and will not re-engage until the overload is cleared. 
     Preferably, drive is transmitted to the intake flighting shaft portion via a bodily rotatable coil spring mounted on the drive shaft between the driven clutch plate element and a drive coupling member on the intake flighting shaft portion. 
     The clutch assembly is arranged so that it will only disengage with a shock overload, and will not disengage under normal constant loading conditions. 
     Preferably the drive coupling member on the shaft portion of the intake flighting comprises a quick release cammed bush selectively rotatable and axially movable between a normally locked clutch engaging position and an unlocked position which disengages the clutch mechanism and thereby enables the intake flighting to be freely rotated about the drive shaft. This is desirable for maintenance reasons where an operator may wish to check that the intake flighting is freely rotating on the drive shaft. It is not unusual for some clogging to occur between the intake flighting shaft portion and the drive shaft on which it rotates—particularly where the auger is being used for conveying fertiliser materials and moisture penetrates into this region. 
     Desirably, the clutch mechanism is designed so that it will only engage when the intake flighting is properly aligned with the flighting on the main drive shaft, and in the event of the clutch temporarily slipping due to an overload, it will only reengage with the flightings properly re-aligned. 
     In order to more fully explain the present invention, two preferred embodiments thereof are described hereunder in some further detail with reference to and as illustrated in the accompanying drawings wherein: 
     FIG. 1 is a fragmentary perspective view of an auger intake assembly fitted to the intake end of a conventional auger (which has had a portion of its shaft and flighting at the intake end thereof cut-off), according to a first embodiment; 
     FIG. 2 is an exploded perspective view of the assembly shown in FIG. 1; 
     FIG. 3 ( a ) is a fragmentary elevational view of the outer end of the auger intake section showing only the clutch mechanism in its normally engaged position; 
     FIG. 3 ( b ) is a view similar to FIG. 3 ( a ) showing the clutch in a disengaged state (by virtue of a shock overload); 
     FIG. 3 ( c ) is a view similar to FIG. 3 ( a ) showing the manner in which the clutch is disengaged by operation of the drive coupling member on the intake flighting shaft; 
     FIG. 4 is a transverse sectional view taken through the section of the intake flighting shown in FIG. 1; while 
     FIG. 5 is a fragmentary view of the auger intake end showing the intake flighting and an extension sleeve fitted to the end of the main auger casing, according to a second embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2 of the drawings, there is shown a material conveying auger assembly  10  which comprises an elongate tubular metal outer casing  11 , a rotary feed metal screw  12  coaxially and rotatably mounted within the casing  11  on a main longitudinal tubular drive shaft  13  which is journalled in end bearings at opposite ends of the casing  11 —all of which is conventional design. A portion of the screw  12  has been cut off from its intake or upstream end so as to permit the fitment of a replacement intake section  14 . 
     The replacement auger intake section  14  includes flexible helical flighting  15  formed preferably of resilient pliable wear resistant polymeric material, eg polyurethane, having a Shore “A” hardness of 90, and which is rotatably and slidably mounted on a solid drive shaft extension portion  17  which is fitted to the main drive shaft  13  and forms a co-axial extension thereof. The shafts  13 ,  17  are joined to one another by means of a locating sleeve  18  welded to the end of the shaft portion  17  and which is inserted into the upstream end of the hollow main shaft  13  and fixed thereto by any suitable means, eg welding, so that the two shafts rotate as one. 
     In this embodiment the intake flighting  15  has a length approximating to two helical turns, with approximately 1½ turns being exposed (refer FIG.  1 ). 
     The open leading end of the main casing  11  has coaxially fitted thereto a soft rubber extension sleeve or collar  19  which encircles a portion, ie approximately one half turn, of the intake flighting  15 . The extension sleeve  19  slidably fits over the open intake end of the casing  11  and is clamped thereto by means of wormdrive ring clamps  20 . In this embodiment, the rubber for the sleeve  19  has a Shore “A” hardness of  45 . 
     A metal supporting bar assembly  22  extends beneath the intake section  14  and is attached at its inner end by means of clamps  23  to the leading end of the casing  11 , the outer end of the bar assembly  22  providing support for the outer end of the shaft extension piece  17 . The support bar  22 , in this embodiment has a draw-bar attachment  24  pivotally connected thereto and which can attach to a towing vehicle for transporting the auger  10 . 
     The helical intake flighting  15  is attached to an elongate rigid tubular sleeve or shaft portion  25  which slidably locates on shaft portion  17 , with the inner end of flighting  15  aligned with and abutting the leading end of flighting  12  on the main shaft  13 . The shaft portion  25 , in this embodiment, comprises an inner elongate rigid metal tube  25 ′ around which is moulded an outer cylindrical layer  26  of polymeric material which is integrally formed with the flighting  15 . The layer  26  and flighting  15  can be moulded simultaneously onto the steel tube  25 ′. 
     A dog clutch mechanism  30  is provided at the outer end of the drive shaft extension  17  to drivingly couple the intake flighting shaft portion  25  to the drive shaft  17 . The clutch  30  is constructed so that it will automatically disengage drive to the shaft portion  25  in the event of an overload occurring (refer FIG. 3 ( b )) whereupon the intake flighting  15  will stop rotating almost immediately while the main auger  12  will continue rotating. 
     In this embodiment the clutch mechanism  30  includes an outer driver clutch element  27 , a driven clutch plate  28  engagable with the driver element  27 , the driver  27  being fastened to the outer end of the shaft extension  17  by a securing bolt  29  so as to be fast therewith. The driver  27  has a single wedge-shaped radial drive lug  31  which, when the clutch is engaged, snugly engages in a complementary shaped radial slot  32  formed in the clutch plate  28 . The clutch plate  28  is urged against the flange of driver  27  by means of a heavy duty compression spring  33  which is rotatably mounted on the shaft  17  between a quick release drive coupling member  35  on the shaft portion  25  of the intake flighting  15  and the clutch plate  28 , with the opposite ends of the spring  33  abutting against axially projecting lugs  37 ,  38  fixedly secured to opposing inner faces of the member  35  and clutch plate  28  respectively. With the clutch  30  engaged, the ends of the spring  33  are held fixed relative to one another, and drive from the clutch driver  27  is transmitted through the spring  33 , to the drive coupling  35  which is held fast with the shaft portion  25  of the flighting  15 , to thereby rotate the flighting  15 . 
     The amount of pre-tension or pre-load on the clutch mechanism  30  will depend on the degree to which the coil spring  33  is compressed when tightening the securing bolt  29 . This can be reduced by means of spring metal shim washers  38  located on the securing bolt  29  against the end of shaft  17 . The use of shim washers makes it difficult for the clutch to be over tensioned to a degree where it will not disengage. 
     The drive coupling member  35  slidably fits over the outer end of the shaft portion  25  of the flighting  15  and has an axial skirt  40  which has a pair of diametrically opposite cam edge surfaces  41  which are inclined with respect to the central axis of the tubular shaft portion  25 . The tubular shaft portion  25  is provided with two fixed radially projecting diametrically opposed projections  42  which make camming engagement with the cam surfaces  41  when the member  35  is rotated relative to the shaft portion  25 . The arrangement is such that the member  35  can be selectively rotated by hand or by a spanner, between a locked clutch engaging position wherein the projections  42  locate in notches  44  formed in the end circular edge of the skirt  40  and the member  35  and shaft portion  25  rotate together, and a clutch release position wherein the projections  42  are disengaged from their notches  44  and the clutch is released to permit the shaft portion  25  and its flighting  15  to rotate freely about the shaft  17 . The camming engagement between projections  42  and cam surfaces  41  when the member  35  is rotated, causes the member  35  to slide axially inwards along the shaft portion  25 , such axial shift causing the tension on spring  33  to be removed to in turn release the clutch and permit the flighting  15  to freely rotate about the shaft  17 . This facility is useful for checking the free rotational movement of the flighting  15  on shaft  17  without the need to loosen the driver element  27 —it being appreciated that there are instances where the shaft portion  25  may become “stuck” to shaft  17 . 
     In the clutch engaging position, the flexible flighting  15  is exactly aligned with the metal flighting of the main auger screw  12 , so that the flightings form a smooth continuous path for the material being fed through the auger. 
     The clutch element  27 , in this embodiment, also serves as an end bearing for the outer end of shaft  17 . The hollow cylindrical body portion of clutch element  27 , is journalled within end bearing  47  which is fixed to a mounting plate  39  which is detachably fastened to a mounting ring  48  which in turn is secured to the support bar  22  adjacent its outer end by means of fasteners  49 . The ring  48  provides protection for the flighting  15  when the intake end is inserted into a bin or hopper. 
     In order to fit the replaceable intake assembly  14  to an existing grain auger, it is necessary to firstly cut off an intake end portion of the main shaft and its flighting from the existing auger and then engage the end of the drive shaft extension  17 , with the flighting  15  and clutch assembly  30  mounted thereon, within the open hollow end of the main drive shaft  13 . With the securing bolt loosened, ie the clutch  30  disengaged, the intake flighting  15  is rotated so as to precisely align with the flighting on the main drive shaft, the clutch mechanism  30  engaged, and finally the securing bolt  29  is fully tightened to secure the clutch driver  27  to the shaft  17  and compress the spring  33 . 
     In operation, drive is supplied to the main drive shaft  13  by conventional means, and this drive is transmitted to the shaft  17  and in turn to the intake section  14  by means of the clutch assembly  30 . If a small obstruction; eg a hand or finger engages the intake flighting  15 , the ability of the resilient flexible flighting  15  to bend and deform and the soft supple nature of the rubber sleeve which is fitted to the intake end of the auger will allow the hand or finger to be withdrawn without injury The use of the clutch mechanism provides an additional safety factor, in that should a large obstruction eg a leg or arm, become caught, drive to the intake flexible flighting  15  will automatically disengage (by virtue of the drive lug  31  “ramping” out of the groove  32  in the driven clutch plate) and the intake flighting will stop rotating almost immediately, whilst still permitting the remaining downstream section of flighting to continue rotating. With the intake flighting stationary, the obstruction can be removed. The two clutch elements  27 ,  28  will reengage automatically once the overload is cleared. 
     Referring to the embodiment shown in FIG. 5 of the drawings, the same item numbers are used to depict parts which correspond to those described in the first embodiment shown in FIGS. 1 to  4  of the drawings. The only variation is that the extension sleeve or collar  19  has integrally formed therewith an axially extending tray portion  21  which extends beneath the flighting  15  and is supported in position by the support bar assembly  22 . 
     The tray portion is also formed of soft rubber or rubber-like material and is designed to assist the feeding of the grain into the intake end of auger as well as provide additional protection on the underside of the intake section  14 . All other parts of the replaceable auger intake section  14  remain substantially the same as that previously described. 
     While the use of a clutch mechanism for drivingly coupling the intake end section to the main drive shaft is highly desirable, it will be realised that the requirement for a clutch mechanism is not essential. For example, the sleeve or shaft portion  25  on which the flexible flighting  15  is mounted may be formed integrally with shaft extension  17 , or the tubular sleeve portion  25  can be rotatably mounted on the intake end shaft portion  17  and secured thereto by means of an overload safety shear pin which engages through aligned holes in the walls of portions  17  and  25 . 
     It should also be realised that the clutch mechanism  30  may be designed so that the driven clutch plate  28  is keyed to the shaft portion  25  and thereby avoid having to transmit drive through the coil spring  33 . A spring would still be required to bias the clutch plate  28  against its driver. 
     The construction of the deformable intake flighting  15  can be varied in a number of ways. In this embodiment, the flighting  15  is integrally moulded onto a stainless steel tube by means of radial metal keying lugs fixed to the outer surface of the metal tube  25 ′ and which are embedded in the flighting where it connects to the shaft  25 ′, thereby providing support for the flighting  15  at the base thereof. It would also be possible for the flights to be moulded to thin resilient internal metal carrier plates which are helically welded to the shaft  25 ′ and which, after the moulding operation, are encapsulated by the resilient polymeric material used to form the flighting  15 . 
     In addition, the auger may comprise several modular sections of flexible flighting having separately clutched connections therebetween. Furthermore, the feed intake of an auger may be located midway along its length, in which case the flexible flighting intake section will be fitted between sections of the drive shaft. 
     It should be appreciated that various modifications can be made to the invention as hereinabove described, and it is intended that the description contained herein hall be interpreted as illustrative only and not in a limiting sense.