Abstract:
The extruder head assembly comprises of a drive shaft connected to a troweling cylinder. A plurality of rollers are spaced around the drive shaft and above the troweling cylinder and intermittently contact an inside surface as the troweling cylinder is rotated and pulled upward. The rollers are either elliptically shaped or round positioned on an eccentric axis for intermittent contact against an inside surface of the concrete pipe. The rollers compact the concrete mixture to form the outer surface and the troweling cylinder follows the compaction by smoothing the surface. The troweling cylinder comprises a plurality of removable sections. Each section is composed of a plurality of removable and replaceable tile segments. When a tile segment breaks, the section containing the broken tile segment can be removed so that the broken tile segment can be replaced.

Description:
This non-provisional application claims priority to U.S. Provisional Application No. 61/646,592 filed May 14, 2012, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     This invention relates generally to the field of concrete pipe manufacturing machinery, and more specifically to the packerhead system of manufacturing concrete pipe. 
     It is conventional practice in dry casting of concrete pipe products to dispose a mold on the base of a concrete pipe machine that is provided with a vertically movable crosshead having a vertically driven shaft on the lower end of which a packer head is attached. The packer head typically includes a troweling cylinder that is rotated in one direction by the driven shaft, and a plurality of distributing rollers that are frictionally driven by engagement with the concrete in a direction opposite to that of the driven shaft on the troweling cylinder. With the packer head moved to its lowermost position so the top is at or below the level of a lower pallet, cement or concrete is fed to the interior of the mold. Then, as the crosshead is raised causing the packer head to be raised, the friction driven rollers pack the cement or concrete against the inner surface of the mold and the troweling cylinder is counter-rotated to finish the inner surface thereby forming the pipe. When the packer head reaches an upper pallet, the pipe is completed. The packer head is then withdrawn from the finished pipe and the form thus provided a molded pipe is replaced by an empty form and the pipe molding process repeated. 
     SUMMARY 
     An extruder head assembly for a concrete pipe manufacturing machine is disclosed. The head assembly comprises of a drive shaft connected to a troweling cylinder. A plurality of rollers are spaced around the drive shaft and above the troweling cylinder and intermittently contact an inside surface as the troweling cylinder is rotated and pulled upward. The rollers are either elliptically shaped or round positioned on an eccentric axis for intermittent contact against an inside surface of the concrete pipe. The rollers compact the concrete mixture to form the outer surface and the troweling cylinder follows the compaction by smoothing the surface. 
     In another embodiment, the troweling cylinder comprises a plurality of removable sections. Each section is composed of a plurality of removable and replaceable tile segments. When a tile segment breaks, the section containing the broken tile segment can be removed so that the broken tile segment can be replaced. 
    
    
     
       BRIEF DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
         FIG. 1  is a perspective view an extruder head assembly embodying the present invention. 
         FIG. 2  is a cross sectional view of the extruder head assembly of  FIG. 1  taken on the lines A-A. 
         FIG. 3  is a vertical bi-sectional view of the extruder head assembly of  FIG. 1 . 
         FIG. 4  is a cross sectional view of the extruder head assembly of  FIG. 1  taken on the lines B-B in  FIG. 3   
         FIG. 5  is a perspective view looking from the top of the troweling cylinder assembly of  FIG. 1 . 
         FIG. 6  is a perspective view of a section of the surface of the troweling cylinder assembly of  FIG. 1 . 
         FIG. 7A  is an illustration showing the orientation of the rollers with respect to each other. 
         FIG. 7B  is an illustration showing an alternative orientation of the rollers with respect to each other. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As best seen in  FIG. 1 , the lower portion of a concrete pipe manufacturing apparatus is provided with an extruder head assembly  12  embodying the present invention. Typically, a pipe manufacturing apparatus includes a turntable adapted to support a pallet and a cylindrical jacket or mold having a cylindrical reinforcing cage used in the formation of a tubular concrete pipe. An upper portion of the pipe manufacturing apparatus supports a downwardly directed drive shaft  24  to which the extruder head assembly  12  is mounted for simultaneous movement therewith vertically inside the mold. Drive shaft  24  is conventionally driven by a motor drive system mounted on the upper portion of the pipe manufacturing apparatus to provide rotational movement as well as vertical movement to the drive shaft  24  and the extruder head assembly  12 . As is well known, a pipe making apparatus has a top table with a funneling mouth located above the upper end of the jacket for receiving a stream or flow of concrete as delivered from a feeding device such as a conveyor, which directs the concrete through the funneling mouth and into the jacket above the extruder head assembly  12 . 
     Referring to  FIG. 1 , the extruder head assembly  12  has a troweling cylinder assembly  34  and a plurality of roller assemblies  36 . Troweling cylinder assembly  34  includes a circular head plate  38 . Connected centrally to the head plate  38  is an upstanding cylindrical hub  48  having a lower circular flange  50 , which is secured by bolts  52  to a mating second circular flange  54  joined to the bottom end of drive shaft  24 . The hub  48  and flanges  50 ,  54  are suitably dimensioned to allow the extruder head assembly  12  to adequately handle the rotational and vertical forces applied through the drive shaft  24 . 
     Four upright fins or vanes  92  that extend upwardly from a horizontal base plate  94  fixed to the top of each roller  56  that forms a part of roller assemblies  36 . Another pair of fins or vanes  93  extend upwardly from a horizontal base plate  95  that is fixed to hub  48  the base plate  95  extending between adjacent rollers  56  to prevent the concrete from falling downwardly around hub  48 . Posts  97  that are fixed to circular head plate  38 , support base plate  95 . Vanes  92  and  93  function to centrifugally sling the wet concrete mixture being delivered into the jacket against the jacket. 
     Roller assemblies  36  include a plurality of elliptical or non-round rollers  56  for rotation relative to the head plate  38  of troweling cylinder assembly  34 . As the extruder head assembly  12  is raised and rotated by drive shaft  24 , rollers  56  are rotated by frictional contact with the wet concrete mixture in a direction counter to the direction of rotation of drive shaft  24  and troweling cylinder assembly  34  connected thereto. In the illustrated embodiment, a set of four rollers  56  are spaced about the periphery of head plate  38  to compact the concrete mixture delivered into the jacket. The outermost surface of rollers  56  is preferably in intermittent vertical alignment with an outer troweling surface  44  of the troweling cylinder, as seen in  FIG. 2 . One skilled in the art would recognize any number of rollers  56  could be used, but an even number of rollers  56  evenly spaced around the periphery balances the weight and equalizes the lateral forces on the drive shaft to minimize vibration. 
       FIG. 2  shows a cross-section of extruder head assembly  12  looking down on roller assemblies  36 . As shown, each roller  56  is oblong or somewhat oval in configuration. The non-round rollers  56  rotate against the inside surface of the wet concrete mixture to compact the concrete mixture in the jacket. The rotation of non-round rollers  56  causes an oscillating impacting force against the inside surface of the concrete pipe to increase compaction of the concrete similar to a repeated paddling by rollers  56  against the wet concrete mixture. Compaction of the concrete mixture expels entrapped air and packs the aggregate particles together to increase the density of the concrete mixture and decrease its permeability. Compaction also greatly increases the ultimate strength and general durability of the concrete pipe that is produced. 
     The timing of the oscillating impacting force by rollers  56  against the inside surface of the concrete pipe can be changed by adjusting the orientation of rollers  56  with respect to each other.  FIGS. 7A and 7B  show alternative orientations of rollers  56 .  FIG. 7A  shows rollers  56  in three positions with rollers  56  oriented in the same direction throughout their rotation. At the first position, rollers  56   a  have their outermost edge in vertical alignment with outer troweling surface  44  of the troweling cylinder and rollers  56   b  are spaced apart from outer troweling surface  44 . As rollers  56  rotate, shown in the second position, the outermost edges of rollers  56   a  rotate away from the outer troweling surface  44 . In the third position, rollers  56   b  have their outermost edge in vertical alignment with the outer troweling surface  44  of troweling cylinder side all  42  and rollers  56   a  are spaced apart from outer troweling surface  44 . 
       FIG. 7B  shows rollers  56  in three positions with opposing rollers  56   a  and opposing rollers  56   b  ninety degrees out of phase with respect to each other throughout their rotation. At the first position, rollers  56   a  and  56   b  have their outermost edge in vertical alignment with the outer troweling surface  44  of troweling cylinder side all  42 . As the rollers  56  rotate, shown in the second position, the outermost edges of rollers  56   a  and  56   b  rotate away from the outer troweling surface  44 . 
       FIG. 3  shows each roller  56  with a downwardly extending support shaft  64  that is rotatably mounted in a bore formed in a cylindrical bearing unit  68  fixed to and depending from the head plate  38 . The bearing unit  68  has an annular collar  70  that is received in head plate  38 . Each collar  70  has a height which will keep the bottom of roller  56  slightly spaced from the top of the head plate  38  so that there is adequate clearance for the rollers  56  to rotate. Also included in the bearing unit  68  is a set of conventional ball bearings, which surround the support shaft  64  and allow each roller  56  to freely rotate relative to the head plate  38 . 
     A transmission arrangement interconnects each roller  56  in a manner that will synchronize the rotation and speed of the rollers  56  and equalize frictional forces should any of the friction driven rollers  56  become stuck or jammed because of concrete or other particles becoming lodged between the bottom of the roller  56  and the top of the head plate  38 . 
       FIG. 4  shows fourtooth-engaging drive sprockets  82 , each keyed to the bottom end of each support shaft  64 , such that rotation of the drive sprocket  82  will turn the support shaft  64  and the roller  56  relative to its bearing unit  68 . Drive sprockets  82  are positioned on support shafts  64  such that they all lie in the same horizontal plane. Four spaced idler sprockets  84  having depending cylindrical sleeves  85  are rotatably supported on shafts  86  that are fixed to and extend downwardly from the bottom of head plate  38 . Each idler sprocket  34  lies in the same horizontal plane as the drive sprockets  82 . A linkage arrangement  90  interconnects each drive sprocket  82  along an outer peripheral portion and idler sprockets  84  along an inner peripheral portion and over a winding path. In the preferred embodiment, the linkage arrangement  90  takes the form of a chain, although it should be understood that a belt, gears or another suitable transmission arrangement could likewise be employed. Drive sprockets  82 , idler sprockets  84 , and linkage arrangement  90  define a synchronous friction drive for collectively driving the rollers  56  without sticking. 
       FIG. 3  shows troweling cylinder assembly  34 , which is mounted underneath circular plate  38  and connected to drive shaft  24  by a collar  72 .  FIG. 5  shows troweling cylinder assembly  34  removed from extruder head assembly  12 . Collar  72  is connected to an inner circular flange  80  by several bolts  81 , so that rotation of drive shaft  24  causes rotation of troweling cylinder assembly  34  in the same direction. 
     The outer troweling surface  44  of the troweling cylinder assembly  34  has a segmented smooth outer surface comprised of a plurality of tiles  82  combined to segments of a steel plate  88  and positioned in grooves  88  in plate  89 , as shown in  FIG. 6 . The troweling cylinder assembly  34  is composed of a plurality of individual sections  83 , each of which is contoured, when assembled, to form a circular outer periphery. 
     Tiles  87  are made from an alumina, such as AL2O3, a tungsten carbide, or a similar ceramic or carbide material. Tiles  87  are less expensive that using a steel outer surface and they can be easily replaced once they begin to show signs of wear. Tiles  87  have may be brittle, so they are held in place with an elastic polymer, which provides elasticity for tiles  87  to prevent cracking. Grooves  89  in steel plate  88  provide a high strength structure that can absorb the shearing force on tiles  87  as trowel  34  is rotated against the concrete, which also prevents tiles  87  from cracking. If, however, tiles  87  crack, an entire outer section  83  can be removed and placed in a kiln to melt the polymer so the broken tiles  87  can be removed and replaced. 
     In use, extruder head assembly  12  is first positioned in the bottom of the jacket adjacent to the pallet. Concrete  30  is then moved by a conveyor into the funneling mouth on the top table and dropped onto extruder head assembly  12 . Drive shaft  24  is then operated to rotate head plate  38  and troweling cylinder assembly  34  in one direction. As troweling cylinder assembly  34  rotates, the friction driven rollers  56  are rotated in an opposite direction by engagement with the concrete to form the concrete pipe as the extruder head assembly  12  moves up the mold. Concrete that is deposited on top of extruder head assembly  12  is slung by vanes  92  and  93  to the outside walls of the jacket. Thereafter, the concrete is acted upon by rollers  56  in an oscillatory motion to compact the concrete. As the extruder head assembly  12  is further rotated and lifted, the concrete is engaged by the smooth outer surface  44  formed from all of the individually spaced tiles  87  of the troweling cylinder assembly to provide a smooth finish to the inside surface of the finished concrete pipe. 
     In an alternative embodiment, roller assemblies  36  include a plurality of round rollers eccentric from an axis defined by downwardly extending support shaft  64 . In that regard, round rollers spinning about eccentric axes have a similar affect as use of non-round rollers. The rotation causes an oscillating impacting force against the inside surface of the concrete pipe to increase compaction of the concrete similar to a repeated paddling by the rollers against the wet concrete mixture. 
     Reference has been made throughout this disclosure to “one embodiment,” “an embodiment,” or “embodiments” meaning that a particular described feature, structure, or characteristic is included in at least one embodiment of the present invention. Thus, usage of such phrases may refer to more than just one embodiment. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood by those of ordinary skill in the art that various changes, substitutions and alterations could be made herein without departing from the spirit and scope of the invention as embodied by the appended claims and their equivalents.