Abstract:
An auger mixer for mixing a concrete mix includes an elongated mixer housing having a mixing chamber for mixing the concrete mix therein. A mixing auger is rotatably mounted within the mixing chamber. A bearing assembly mounts one end of the auger shaft to the mixer housing. A seal assembly comprising a stationary seal remains stationary relative to the mixer housing and a rotating seal rotates with the auger. The stationary seal and the rotating seal contact one another to create a seal preventing the concrete mix from exiting the mixing chamber and moving toward the bearing assembly.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a bearing seal assembly for a concrete auger mixer.  
         [0002]     Concrete auger mixers have been utilized to mix concrete in a continuous process. They include an elongated housing having a rotating auger therein. The housing usually has a flexible bottom and a rigid top and is arcuate at least in the bottom portion to conform to the flightings on the auger.  
         [0003]     The auger housing is usually elevated at the discharge end and is lowered at the input end so that the concrete ingredients are placed within the housing at the lower end and is raised by the auger and mixed as it approaches the discharge opening at the upper end of the auger.  
         [0004]     Problems have been encountered in providing a satisfactory seal of the lower end of the auger to the lower end of the auger housing. The auger rotates within the lower end wall of the auger housing and the cementations materials and water directed downwardly by gravity seep into the bearing and ultimately damage the bearing because of the abrasive nature of the cementatious material.  
         [0005]     It is therefore desirable to provide an improved seal preventing the cementatious material from entering the bearing from within the auger housing.  
         [0006]     Therefore a primary object of the present invention is the provision of an improved bearing seal for concrete auger mixers.  
         [0007]     A further object of the present invention is the provision of a bearing seal for a concrete auger mixer that utilizes a stationary seal and a rotating seal which engage one another and provide a seal therebetween.  
         [0008]     A further object of the present invention is the provision of a stationary seal that remains stationary relative to the end wall of the housing mixer and a rotating seal that rotates with the auger, the two seals engaging one another and providing a seal to prevent cementations material from exiting the mixing housing chamber.  
         [0009]     A further object of the present invention is the provision of a seal comprising a fixed sealing member and a fixed flexible member, and providing a rotating sealing member and a rotating flexible member. The fixed sealing member and the rotating sealing member include sealing surfaces that engage one another and prevent cementatious material from exiting the auger housing.  
         [0010]     A further object of the present invention is the provision of a flexible plate outside the lower housing wall which permits a slight movement of the angle of the auger relative to the mixer housing wall so as to permit slight flexing thereof.  
         [0011]     A further object of the present invention is the provision of a bearing for permitting the rotation of the auger relative of the end wall of the mixer, the seal being provided between the bearing and the cementatious material.  
         [0012]     A further object of the present invention is the provision of a seal and bearing for a concrete auger mixer which is economical to manufacture, durable in use, and efficient in operation.  
         [0013]     A further object of the present invention is the provision of a method for sealing the cementatious material within the mixer housing during rotation of the auger.  
         [0014]     A further object of the present invention is the provision of a bearing which utilizes lapped surfaces for engaging one another to cause the seal.  
       SUMMARY OF THE INVENTION  
       [0015]     The foregoing objects may be achieved with an auger mixer for mixing a concrete mix comprising an elongated mixer housing having a first end and a second end. The mixer housing has a mixing chamber for mixing the concrete mix therein. A mixing auger is disposed within the mixing chamber and has an auger shaft. The auger shaft has a longitudinal shaft axis extending from the first end to the second end of the mixer housing. A power source is connected to the mixing auger for rotating the mixing auger about the longitudinal shaft axis of the shaft. The mixer housing has a first end wall adjacent the first end of the housing. A bearing assembly mounts one end of the auger shaft to the first end wall of the housing for rotation relative to the first end wall about the shaft axis. A seal assembly comprises a stationary seal remaining stationary relative to the first end wall and a rotating seal rotating about the auger shaft axis. The stationary seal and the rotating seal contact one another to create a seal preventing the concrete mix from exiting the mixing chamber and moving toward the bearing assembly.  
         [0016]     According to another feature of the present invention the fixed seal comprises a first fixed seal member and a second fixed seal member. The rotating seal comprises a first rotating seal member and a second rotating seal member.  
         [0017]     According to another feature of the present invention the first fixed seal member and the first rotating seal member are made of a resilient material deformed to engage and urge the second fixed member and the second rotating member respectively into frictional engagement with one another to create the seal.  
         [0018]     According to another feature of the present invention the first fixed and rotating seal members are made of rubber and the second fixed and rotating seal members are made of steel.  
         [0019]     According to another feature of the present invention the stationary seal comprises a sealing surface and the rotating seal comprises a sealing surface frictionally engaging and sealing against the sealing surface of the stationary seal.  
         [0020]     According to another feature of the present invention the sealing surfaces of the stationary seal and the rotating seal are comprised of steel.  
         [0021]     According to another feature of the present invention the sealing surfaces of the stationary seal and the rotating seal are circular.  
         [0022]     According to another feature of the present invention the sealing surfaces of the stationary seal and the rotating seal are cone shaped and have outer circular cone ends. The cone shaped sealing surfaces of the stationary and rotating seals are oppositely opposed to one another so that only the outer circular cone ends contact one another.  
         [0023]     According to another feature of the present invention a flexible stationary seal member and a flexible rotating seal member engage the stationary sealing surface and the rotating sealing surface respectively and bias the stationary sealing surface and the rotating sealing surface toward one another.  
         [0024]     According to another feature of the present invention a steel plate attaches the bearing assembly to the first end wall of the housing. A compressible plate is between the steel plate and the first end wall. A securing member secures the steel plate and the compressible plate to the first end wall whereby the compressible plate permits flexing of the steel plate and the first end wall relative to one another so as to permit slight movement of the angular disposition of the shaft axis relative to the end wall.  
         [0025]     According to the method of the present invention a seal assembly is placed between the first end wall and the rotating shaft. The seal assembly comprises a stationary seal and a rotating seal. The method includes maintaining the stationary seal stationary with respect to the first end wall and rotating the rotating seal about the rotating axis of the rotating auger shaft. The stationary seal and the rotating seal are frictionally contacted to provide a sealing engagement therebetween for preventing concrete mix from exiting the mixing chamber through the first end wall.  
         [0026]     According to another feature of the method of the present invention a stationary seal having a circular stationary sealing surface and a rotating seal having a circular rotating sealing surface contact one another.  
         [0027]     According to another feature of the present invention the circular rotating surface and the circular stationary surface are biased in frictional engagement with one another. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  is a sectional view of an auger mixer of the present invention.  
         [0029]      FIG. 2  is a sectional view of the bearing assembly of the present invention.  
         [0030]      FIG. 3  is an exploded perspective view of the lapped seal members used in the present application.  
         [0031]      FIG. 4  is an enlarged detailed sectional view taken along line  4 - 4  of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]     Referring to  FIG. 1 , a concrete auger mixer  10  embodying the present invention is shown. Mixer  10  includes a mixer housing  12  having a rigid upper member  14  and a flexible lower member  16 . A first end wall  18  and a second end wall  20  together with the upper member  14  and the flexible lower member  16  form a mixing chamber  22  in which concrete is to be mixed. The mixing chamber  22  includes an inlet opening  24  adjacent the lower end wall  18  and a discharge opening  26  adjacent the upper end wall  20 . A hopper  28  is provided for dropping the concrete mix into the lower end of the auger mixer  10 . The concrete mix may vary, but usually includes cement, aggregate, water, and possibly other ingredients such as pigments.  
         [0033]     Rotatably mounted within the mixing chamber  22  is an auger  30  having an auger shaft  32  and auger flightings  34 . The auger shaft  32  is adapted to rotate about its longitudinal axis  32 . A motor  36  is attached to the upper end of the auger shaft  32 . A motor bearing  38  (not shown) provides the rotation of shaft  32  in the end wall  20  as it is rotated by motor  36 . The bearing  38  does not encounter substantial pressure from the cementatious material within the housing  22  because it is located at the upper end of the mixing auger  10 .  
         [0034]     However, a bearing assembly  40  is used to mount the lower end of the auger shaft  32  to the lower end wall  18 .  
         [0035]     Referring to  FIG. 2 , a wear plate  42  is in facing engagement with the interior of lower end wall  18 . Wear plate  42  includes an annular flange  44 . On the opposite side of end wall  18  is a flexible plate  46  preferably made from rubber, but possibly made from other flexible material. A bearing housing  48  includes a housing plate  50  which is in facing engagement with the flexible plate  46  and holds the flexible plate  46  against the end wall  18 . Bearing housing  48  also includes a housing cylinder  52  which includes a grease zerk  54  therein. Bolts  56  bolt the flexible plate  46  between the housing plate  50  and the end wall  18 , and also bolt the wear plate  42  against the end wall  18 . The end wall  18 , the flexible plate  46 , the housing plate  50 , and the internal wearing plate  42  all include a circular opening therein which together form a clearance opening  58 .  
         [0036]     Mounted telescopically within the lower end of shaft  32  is a tail shaft  60  which is held in attachment to the auger shaft  32  by means of a connecting bolt  62 . Thus tail shaft  60  rotates in unison with auger shaft  32 .  
         [0037]     Tail shaft  60  includes an internally facing shoulder  64 . The term internally refers to facing in the direction of the mixing chamber  22 . Tail shaft  60  and bearing housing  48  together create an annular seal cavity  66  which contains a stationary seal  68  and a rotating seal  70 . Stationary seal  68  includes a stationary steel ring  72  ( FIG. 4 ) and a stationary flexible ring  74 . The rotating seal  70  includes a rotating steel ring  76  and a rotating flexible ring  78 . Together the stationary seal  68  and the rotating seal  70  comprise a heavy duty seal manufactured by CR Services, 735 Tollgat Road, Elgin, Ill. 60123-9332 under the service kit number 16904. These seals are also referred to as “lapped seals”. They are shown in greater detail in  FIGS. 3 and 4 . Stationary steel ring  72  includes a horizontal ring  80  and a vertical ring  82 . The vertical ring  82  has a cone shaped surface  84  thereon. Cone shaped surface  84  has an outer cone edge  86  which forms the outer peripheral edge of a tapered seal surface  88 .  
         [0038]     The rotating steel ring  76  is similarly constructed and includes a horizontal ring  80 , a vertical ring  82 , a cone shaped surface  84 , an outer cone edge  86 , and a tapered seal surface  88 . It should be noted that only the outer peripheral edges  86  of the two steel members  72 ,  76  engage one another around the entire periphery of the rings  72 ,  76 . As the friction between the two causes wear of the tapered seal surface  88 , the wear merely results in a flatter surface being formed between the steel members  72 ,  76 . Flexible members  76 ,  78  are enclosed within seal cavity  66  and are distorted so that they are loaded and are angularly presented so that they force or bias the two steel members  72 ,  76  into engagement with one another as shown in  FIG. 4 . The lapped surface  86  provides a seal that prevents the cementatious material from entering between the two seal members  72 ,  76 .  
         [0039]     The tail shaft  60  also includes an outwardly facing shoulder  90  that faces away from the end wall  18 . A bearing comprising an outer race  92 , an inner race  94  and a tapered bearing  96  engages this outwardly facing shoulder  90 . Similarly, a second bearing comprising an outer race  98 , an inner race  100 , and oppositely tapered bearings  102  is spaced outwardly from the first bearing member described. The bearing housing  48  includes an outwardly presented housing shoulder  104  and an inwardly presented housing shoulder  106  which engaged the bearings and hold them in place. The two bearings are spaced apart from one another by a bearing cavity  108 . A spacer washer  110  surrounds the outwardly presented end of the tail shaft  60 . A slotted nut  112  is threaded over the outer threaded end of tail shaft  60  and is further held in place by means of a cotter pin  116 . In addition the slotted nut  112  includes slots  114  for receiving cotter pin  116  and has a hexagonal configuration for use of a wrench. A dust cap  118  is in covering relation over the nut  112  and is held in place by a securing ring  120  that includes bolts  122 . Tail shaft  60  includes a shank portion  124  that forms an internal margin of a donut shaped cavity  108  that extends between the two bearings.  
         [0040]     Grease is inserted through zerk  54  into the cavity  108  and then forced through bearing  96  into a donut shaped cavity  126 , then between seal  68  and seal  70  into cavity  66  and continuing into cavity  130 .  
         [0041]     In operation, the motor  36  rotates the auger shaft  32  so as to cause the concrete mix to be moved upwardly from the inlet opening  24  towards the discharge opening  26 . The rotation of the auger  32  and flightings  34  causes the concrete mix to be thoroughly mixed together before it is discharged from the discharge opening  26 .  
         [0042]     The concrete mix includes a slurry formed by the water in the mix, and this slurry drops by gravity toward the bearing assembly  40 . It can enter between a lower end flange  128  through an L-shaped limited cavity  130 . While the slurry can enter this cavity  130 , larger particles such as aggregate are too large to enter the cavity  130 . However, when the slurry reaches the sealed cavity  66  ( FIG. 4 ), it is prevented from further infiltration into the bearing assembly  40  by the contact between the stationary seal  68  and the rotating seal  70 . It should be noted that auger shaft  32 , lower end flange  128 , and rotating seal  70  rotate in unison together with the tail shaft  60  and the slotted nut  124 .  
         [0043]     The end wall  18 , the plates  42 ,  46 ,  50 , and the entire bearing housing  48  remain stationary as well as the stationary seal  68 .  
         [0044]     An important feature of the present invention is the frictional engagement between the rotating steel ring  76  and the stationary steel ring  72 . These two rings engage one another at the outer cone edge  86 . Through extended use, these surfaces will wear, but the angled nature of the sealing surfaces  84  take up the wear and prevent the seal from losing its sealing capability. Thus the cementatious slurry that enters through limited cavity  130  never progresses beyond the seal cavity  66 . This cementatious material is also trapped between the two flexible sealing members  74 ,  78 .  
         [0045]     The bearings  96 ,  102  also are protected from the cementatious slurry material, and therefore their wear in response to the abrasive cementatious slurry is minimized.  
         [0046]     The flexible plate  46  permits slight flexing of the auger shaft  32  with respect to the angle at which the tail shaft  60  passes through the wall opening  58 . This provides tolerance for rotational movement of the shaft  32 .  
         [0047]     The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.