Abstract:
A new and improved rollerhead for packerhead assemblies employed in concrete pipe making machines utilizing the packerhead method of pipe formation wherein the rollerhead includes a roller shaft having an upper end and a lower end, a hollow cylindrical roller body rotatably disposed around the roller shaft, a first bearing coaxially mounted about the upper end of the roller shaft and contacting an inside surface of the roller body, a second bearing coaxially mounted about the lower end of the roller shaft and contacting an inside surface of the roller body. The improvement comprises a roller body including a radially inwardly directed flange, an annular body mounted coaxially about the roller shaft, and an annular seal coaxially disposed about the annular body. The inwardly directed flange, annular body, and annular seal create a sealing system designed to prevent the infiltration of concrete contaminate matter into the rollerhead housing thus reducing wear on interior roller parts and lengthening the operative lifespan of the rollerhead assemblies.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to an apparatus for the production of concrete pipe. More particularly, the present invention relates to an improved rollerhead assembly for use in conventional packerhead assemblies that incorporates a roller seal system for the prevention of contaminate infiltration into the concrete roller.  
         BACKGROUND  
         [0002]    Concrete pipe has been used for infrastructure development for thousands of years and has a well-established reputation for serviceability and long-lasting characteristics. Concrete pipe comes in a variety of shapes and sizes and particular pipe specifications are based on hydraulic and structural needs, cost requirements, and project site specifics such as topography and soil conditions.  
           [0003]    The basic materials used in the production of concrete pipe are aggregate, portland cement, and water and various types of machines have been developed over the years for the casting of pipe using these materials. Different manufacturers of tubular concrete pipe have in recent years used machines which employ apparatus known as “packerheads” or “packerhead assemblies”. In such machines, a large, inverted “U” shaped mainframe is used in connection with the driveshaft to which the packerhead is connected. The packerhead typically includes a troweling cylinder, also known in the art as a longbottom, which is rotated in one direction by the driveshaft, and a plurality of distributing rollers or rollerhead assemblies which are frictionally driven by engagement with the concrete in a direction opposite to that of the driveshaft on the troweling cylinder. The axis of the plurality of rollers and the troweling cylinder extend parallel to the axis of the pipe.  
           [0004]    The packerhead assembly is lowered into a form, and the packerhead is placed at the bottom of the form. As concrete is placed around the inside periphery of the form, the packerhead is raised. As the packerhead is 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 packerhead reaches an upper pallet, the pipe is completed. The packerhead is then withdrawn from the finished pipe and the form thus provided with a molded pipe is replaced by an empty form and the pipe molding process repeated. The self-supporting formed pipe is then de-molded and stored to reach a sufficient strength after an initial curing to enable handling of the pipe and removal from the pallet.  
           [0005]    The use of packerhead machines and methods in the production of concrete pipe is generally disclosed in numerous references including: U.S. Pat. No. 4,041,118 to Ottmann et al.; U.S. Pat. No. 4,042,315 to Ottmann et al.; U.S. Pat. No. 4,253,814 to Christian; U.S. Pat. No. 4,334,848 to Gross et al.; U.S. Pat. No. 4,340,553 to Fosse; U.S. Pat. No. 4,407,648 to Fosse; U.S. Pat. No. 4,540,539 to Crawford et al.; U.S. Pat. No. 4,600,548 to Nenna; U.S. Pat. No. 4,639,342 to Adly; U.S. Pat. No. 4,756,861 to Schultz; U.S. Pat. No. 4,957,424 to Mitchell et al.; U.S. Pat. No. 5,147,196 to Adly; U.S. Pat. No. 5,167,967 to Adly; U.S. Pat. No. 5,236,322 to Willert; U.S. Pat. No. 5,248,248 to Adly; and U.S. Pat. No. 6,106,749 to Adly.  
           [0006]    One long-standing problem in the manufacture of tubular concrete pipe by the packerhead method is the foreign material or particles in the incoming concrete flow that can affect the manufacture of the pipe or damage internal moving parts. The coarseness of the concrete flow can cause wear damage to the external surfaces of the packerhead assembly. Also, such particulate matter can become lodged between the troweling cylinder and one or more of the distributing rollers, thereby causing the rollers to stick or jam. When jamming of this nature occurs and one or more of the rollers does not rotate, the compaction of the concrete becomes uneven and the quality of the pipe formation suffers accordingly. Additionally, contaminates in the concrete flow can infiltrate the packerhead assembly and the individual rotating rollers. Such infiltration of concrete material causes increased wear on moving components of the rollerhead assembly and more specifically can cause the interior bearings of the individual rollers to be damaged within a short period of time. This contamination of the interior bearings of the concrete rollers causes the entire packerhead machine to have to be shut down for cleaning of the individual rollers. Several patents disclose prior efforts to address these long-standing problems associated with the concrete flow in a variety of different ways.  
           [0007]    U.S. Pat. No. 3,276,091 to Pausch discloses a rollerhead for cement pipe forming including a rollerhead and smoothing or troweling mechanism having a downwardly depending cylindrical skirt. A head plate is bolted across the upper end of the troweling cylinder. An annular array of symmetrically and circumferentially spaced, eccentrically adjustable roller packer units is disposed to extend upwardly from the head plate. An aggregate spreader plate is disposed above the roller packer units. A plurality of aggregate slingers disposed on the spreader plate are adapted to propel aggregate into the paths of the roller packer units. To guard against wear of the troweling or smoothing casing, Pausch discloses wearguards that are provided on the top of the troweling cylinder in the spaces between the roller packer units. Pausch further discloses the use of an O-ring seal between the stud and the cylinder in the roller packer units to protect the bearings. However, the use of an O-ring seal in such a manner would expose the seal to high frictional stresses, resulting in failure of the O-ring within a relatively short time. It is believe that because of the shortcomings resulting from the seal arrangement as described in Pausch, this type of rollerhead sealing system has not been adopted by the concrete pipe making industry.  
           [0008]    U.S. Pat. No. 3,733,163 to Hermann discloses an improved wear surface for the longbottom section employed in packerhead concrete pipe making machines. The longbottom of the packerhead includes a plurality of wear segments disposed about the upper circumferential outer surface thereof.  
           [0009]    U.S. Pat. No. 4,690,631 to Haddy discloses a packerhead concrete pipe making machine having a rotatable packerhead operable to form a concrete pipe in an upright cylindrical mold. The packerhead has a plurality of rollers rotatably mounted on a circular plate operable to pack concrete into a cylindrical shape in the mold. Each roller has an outer sleeve of elastic rubber material for greater traction on the abrasive concrete in the mold and ensuring continuous rotation of the roller during the rotation of the packerhead in the mold.  
           [0010]    U.S. Pat. No. 5,080,571 to Crawford discloses a packerhead assembly for use in concrete pipe making machines that incorporates a longbottom assembly that utilizes a removable wearband to limit the ingress of concrete material to the interior area of the longbottom assembly around the individual rollerheads. This wearband extends upwardly from the uppermost level of the longbottom assembly to a position approximately ⅛″ from the lowermost portion of the rollers of the roller assembly.  
           [0011]    U.S. Pat. No. 5,215,604 to Crawford discloses a packerhead assembly that incorporates a longbottom or troweling cylinder wear segment that has increased wear resistance through the use of a specific alloy.  
           [0012]    U.S. Pat. No. 6,017,208 to Schultz discloses a concrete pipe manufacturing machine including a troweling cylinder having a head plate, a vertically movable and rotatable drive shaft fixed to the head plate for moving the troweling cylinder in a vertical direction and in one rotational direction, and a series of roller assemblies rotatably mounted on the head plate and adapted to be rotated by frictional contact with the concrete mixture in a direction counter to the one rotational direction of the drive shaft. Schultz further discloses a drive arrangement interconnecting and collectively driving the roller assemblies together for preventing jamming of the roller assemblies due to material in the concrete mixture lodging between the bottom of the rollers and the top of the head plate.  
           [0013]    Applicant believes that all of the aforesaid efforts have suffered from various shortcomings and none have proven to be a solution to the contaminate problem.  
           [0014]    The present invention is provided to solve these and other problems associated with the prevention of contaminates entering into the individual concrete rollers, and specifically with the prevention of contaminate damage through the use of a new and novel seal system built into each individual roller housing.  
         DISCLOSURE OF THE INVENTION  
         [0015]    In accordance with the present invention, an improved rollerhead assembly is provided for use in a machine for making a concrete product, such as concrete pipe, in an upright generally cylindrical mold. The machine has a frame, 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 system supports a downwardly directed driveshaft and a packerhead assembly movably mounted thereon. The packerhead is adapted to be located in a mold chamber of the generally upright mold. The driveshaft is conventionally driven by a lifting means and a drive arrangement to selectively raise and lower the packerhead assembly as well as provide rotational movement such that the packerhead is concurrently rotated and elevated during the forming of the concrete pipe. The packerhead has a base plate that is connected to the drive means. A plurality of rollers are rotatably mounted on top of the base plate for rotation about separate generally upright axes. The rollers function to move and pack concrete in a generally cylindrical shape and form with the mold the cylindrical concrete pipe. Each of the rollers has an upright roller shaft secured to the plate and projected upwardly therefrom. A roller body surrounds the roller shaft and includes a radially inwardly directed flange that defines an aperture for receiving the lower end of the roller shaft. Bearings rotatably mount the body and the roller shaft. An outer wear band may be provided in a press fit relationship on the outside surface of the roller body for protection of the roller body.  
           [0016]    A novel sealing system is provided in the present invention to prevent contaminates from entering the inside of the roller housing through the channel located between the roller shaft and the roller body. The sealing system comprises an annular body mounted coaxially about the roller shaft and disposed adjacent to the flange defined by the roller body and an annular seal coaxially disposed about the annular body. The inwardly directed flange of the roller body, the annular body, and the annular seal cooperate to provide a sealing system on the lower end of the rollerhead assembly for the prevention of concrete and other particulate matter infiltration into the roller housing. A generally cylindrical trowel is secured to the plate and extends downwardly therefrom. The trowel has an annular surface for troweling in the inside surface of a pipe during movement of the packerhead relative to the mold. The trowel may have replaceable segments of abrasion-resistant material.  
           [0017]    Therefore, it is an object of the present invention to provide an improved rollerhead assembly for a packerhead assembly used in forming concrete pipes.  
           [0018]    It is another object of the present invention to provide an improved rollerhead assembly that is designed for use with concrete mixes having relatively high fluidity.  
           [0019]    Yet another object of the present invention is to provide an improved rollerhead assembly in which wear on rotating internal parts is reduced.  
           [0020]    It is a further object of the present invention to provide an improved rollerhead assembly having a sealing system resistant to particulate matter infiltration.  
           [0021]    Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a vertical cross-sectional view of a concrete pipe manufacturing system equipped with a packerhead assembly embodying rollerheads of the present invention;  
         [0023]    [0023]FIG. 2 is an enlarged sectional view taken along the line  2 - 2  of FIG. 1;  
         [0024]    [0024]FIG. 3 is an enlarged vertical cross-sectional view of a prior art packerhead assembly which does not employ the rollerheads of the present invention;  
         [0025]    [0025]FIG. 4 is an enlarged fragmentary vertical cross-sectional view of the packerhead assembly employing rollerheads of the present invention.  
         [0026]    [0026]FIG. 5 is a vertical cross-sectional view of the rollerhead of the present invention;  
         [0027]    [0027]FIG. 6 is a top plan view of the rollerhead of the present invention;  
         [0028]    [0028]FIG. 7 is an exploded view of a rollerhead of the present invention;  
         [0029]    [0029]FIG. 8 is an enlarged vertical cross-sectional side view of the lower portion of the rollerhead of the present invention; and  
         [0030]    [0030]FIG. 9 is an enlarged vertical cross-sectional view of the seal system portion of the rollerhead of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    Referring to FIG. 1, there is shown a lower portion of a concrete pipe manufacturing system  10  provided with a packerhead assembly  12  embodying the rollerhead of the present invention. Typically, system  10  comprises a turntable  14  adapted to support a pallet  16  and a cylindrical jacket or mold  18  having a cylindrical reinforcing cage  20  used in the formation of a tubular concrete pipe  22 . An upper portion of the system  10  supports a downwardly directed driveshaft  24  to which the packerhead assembly  12  is mounted for simultaneous movement therewith, as found in a uni-directional packerhead assembly. It is also envisioned that the improved rollerhead of the present invention can be used in a bi-directional packerhead assembly system, as is known to those skilled in the art. Driveshaft  24  is conventionally driven by a drive arrangement (not shown) mounted on the upper portion of the system  10  so as to provide rotational movement as well as vertical movement to the driveshaft  24  and the packerhead assembly  12  in a manner well known in the art. A top table  26  having a funneling mouth  28  is located above the upper end of jacket  18  for receiving a stream or flow of concrete C as delivered from a feeding device such as a conveyor  32  which directs concrete C through funneling mouth  28  and into the jacket  18  above the packerhead assembly  12 . The packerhead  12  is rotated at a desired speed as it is raised relative to mold.  
         [0032]    Referring to FIG. 2, there is shown the top of packerhead  12  with the concrete removed therefrom. Packerhead  12  has four circumferentially spaced rollers indicated generally at  40 . Each roller rotates about a generally upright axis. Adjacent axes of the rollers are circumferentially spaced 90 degrees from each other. The axes of rollers  40  extend upwardly from roller mounting plate  48  generally parallel to the axes of rotation of driveshaft  24 . Each of the rollers  40  rotate independently about their axis during the rotation of the packerhead to pack and compress the concrete in an annular configuration around the inside of mold  18  and around wire cage  20 . Rollers  40  have the same diameters and vertical dimensions or height. The height of each roller is substantially the same as the height of troweling sleeve  50 . As shown in FIG. 2, on rotation of packerhead  12  in the direction of the arrow  52 , rollers  40  are rotated in the direction of the arrows, such as arrow  54 .  
         [0033]    Referring back to FIG. 1, as the packerhead  12  is rotated, some of the concrete is effectively forced into the annular spaces in the cylindrical reinforcing cage  20  in the gap between the outer wall of the packerhead and the inner wall of the cylindrical mold  18 . As the concrete begins to cure, the packerhead  12  is raised upwardly throughout the cylindrical mold  18 . The entire lining process typically occurs in less than five minutes. Once the lining is applied inside the cylindrical mold  18  and has sufficiently cured, the tubular concrete pipe  22  can be removed and another form and reinforcing cage to be lined can be positioned in the apparatus. The tubular concrete pipe  22  may then be allowed to naturally cure or be placed in a kiln to effect an accelerated final curing.  
         [0034]    [0034]FIG. 3 is an example of a packerhead assembly using prior art rollers. As shown in FIG. 3, concrete C can enter into the interior of the packerhead and rollers. As the packerhead assembly is rotated, concrete C will be flung against the inside surface of the concrete pipes being formed. In addition, concrete C which flows radially inwardly between roller  40  and the longbottom assembly  60  can easily enter the rollerhead housing (see arrow) and contribute significantly to contamination and excess wear of the bearings which support the rollers. The extent to which concrete will enter the interior of the packerhead assembly and the rollers themselves will depend upon the fluidity of the mix and the size of the aggregate used in the mix. The novel seal system of the present invention is designed to eliminate this infiltration of concrete mix C.  
         [0035]    Referring now to FIG. 4, it will be seen that a rollerhead driveshaft  24  is secured, as by welds  62 , to a circular roller mounting plate  48  on which a plurality of rollers  40  may be mounted. It will be understood that any desirable number of rollers may be employed. The rollers may include any type and number of distributing blades or fins  64 A and  64 B. A longbottom assembly is indicated generally at  60 , the longbottom assembly and the rollerhead, indicated generally at  40 , together with a respective drive means, comprise collectively, in this instance a bi-directional packerhead  12 . The longbottom assembly  60  includes a circular bottom plate  68  having apertures  70  therein for ready access to the rollers  40 . A mounting flange is indicated at  72 , the mounting flange carrying a smooth, circular roller distributor blade or troweling sleeve  50  which is secured entirely around the periphery of the mounting flange  72  by any suitable fastening means  74 . Circular bottom plate  68  is welded, as at  76 , to a long bottom driveshaft indicated at  78 , thus depicting a bi-directional packerhead assembly.  
         [0036]    Referring now to FIGS.  5 - 9 , a rollerhead  40  of the present invention is provided for use with a packerhead assembly  12 . The backbone or central element of rollerhead  40  is roller shaft  84 , to which all other components attach. Roller shaft  84  has an upper end and a lower end. A cylindrical roller body  86  of metal or like rigid material surrounds roller shaft  84 . A pair of first  88  and second  90  bearings are coaxially mounted about roller shaft  84  and rotatably contact the inside surface of roller body  86 . In a preferred embodiment, sealed bearings will be used in order to further protect internal parts from additional wear. Although any form of bearing means as known to those skilled in the art may be used, it is recommended that unsealed bearings not be used as their use may significantly shorten the useful life of the rollerhead assembly. As shown in more detail in FIG. 8, in the novel seal system of the present invention, roller body  86  includes a radially inwardly directed flange  92  that defines an aperture, shown generally at  120 , therein to receive the lower end of roller shaft  84  therethrough (as shown in FIG. 7). The flange comprises a first annular shoulder SH adjacent the aperture  120  that includes an axial surface  96  and a radial surface  98 . The flange further comprises a second annular shoulder SH′ located adjacent to the first annular shoulder SH and inwardly of the roller body  86  and including an axial surface  102  and a radial surface  104 . An annular body  122  of metal or like rigid material is mounted coaxially about the lower end of the roller shaft  84  and is disposed adjacent to the axial surface  96  of the first annular shoulder SH and within the aperture  120  defined by the flange  92 . The annular body  122  may be in press fit relationship to the roller shaft  84 . An annular seal  124  of ultra high molecular weight (UHMW) polyethylene or like material is coaxially disposed about the annular body  122  and interposed between the radial surface  98  of the first annular shoulder SH and the second bearing  90  mounted about the lower end of the roller shaft  84 . The radial surface  98  of the first annular shoulder SH and the axial surface  102  of the second annular shoulder SH′ are coaxially disposed around annular seal  124  so as to provide an annular slot SL in the flange  92  for receiving the annular seal  124  therein.  
         [0037]    As shown in more detail in FIG. 9, annular body  122  further comprises an annular shoulder SH″ proximate to the upper end of the roller shaft  84  and including an axial surface  110  and a radial surface  112 . The annular seal  124  further comprises an annular slot SL′ therein including an axial surface  116  and a radial surface  118  for receiving the annular shoulder SH″ of annular body  122 .  
         [0038]    Referring back to FIG. 5, the upper end of the rollerhead may be closed by the use of a back plate cap or flat cap  126  secured with a plurality of bolts, screws, or other suitable fastening means  128 . The flat cap  126  covers the top of roller body  86  and retains lubricants within the roller body  86 . A wavy washer or other similar dampening element  130  may be mounted between the closed upper end of the roller body and the first bearing  88  mounted about the upper end of the roller shaft. The dampening element  130  acts as a shock absorber for the roller  40  and additionally keeps the first bearing  88  in its proper location during operations. Flat cap  126  may contain a plurality of upwardly directed generally flat distributing fins or blades  64 A,  64 B and  64 C which are operable to work and move concrete toward the inner wall of mold  18 . Referring to FIG. 6, fins  64 A- 64 C are evenly distributed upon flat cap  126 . The fins  64 A- 64 C generally have a vertical height that is substantially the same as the vertical height of roller  40 . Referring back to FIG. 5, a continuous wear band, tube or sleeve  132  of metal or elastic abrasive resistant material is located about roller body  86 . Wear band  132  is press fitted onto the outside cylindrical surface of roller body  86 . Wear band  132  has an inside cylindrical surface that is smaller than the outer cylindrical surface of roller body  86 . When wear band  132  is press fitted onto roller body  86 , it is under continuous tension whereby the band is retained on the body. In the event that wear band  132  is damaged or worn, it can be removed from roller body  86  and replaced with a new wear band. Wear band  132  has a continuous cylindrical outer surface that engages the concrete as roller  40  rolls about its upright axis thereby exerting an opposite force on the concrete C.  
         [0039]    Upon assembly of the rollerhead, each roller is mounted on the roller mounting plate  48  through the placement of the threaded cylindrical hub portion of the lower end of the roller shaft through a hole in roller mounting plate  48 , as shown in FIG. 4. The threaded end of the cylindrical hub projects downwardly from the plate roller mounting plate and accommodates a nut  80  (see FIG. 4) for rigidly fixing the roller shaft to the roller mounting plate. Nut  80  can be removed from the lower end of the roller shaft  84  to allow roller  40  to be removed from the roller mounting plate  48  for servicing or replacement.  
         [0040]    In use, as packerhead  12  is rotated, the concrete C is worked and pressed around the reinforcing wire cage  20  and against the inside of the wall of cylindrical mold  18  to form a cylindrical concrete wall. All of the rollers  40  continuously work and pack concrete during the rotation of packerhead  12 . The annular troweling sleeve  50  provides a continuous annular trowel that finishes the inside surface of pipe  22 . The packing and troweling action of packerhead  12  is continuous during its rotational and vertical movements from the bottom of the mold to the top ring of the mold. Packerhead  12  forms a smooth inside surface of the concrete pipe as illustrated in FIG. 1.  
         [0041]    As shown in FIG. 3 and described hereinabove, prior art rollers consisted of open designs that essentially brought the roller body up against the roller shaft, thereby creating an “open channel” for concrete particulates and other contaminates to enter the roller housing and damage interior parts such as bearings. One prior art reference suggested using an O-ring seal, but due to frictional wear and other limiting factors, this O-ring configuration was never in wide-spread use and is not used in the industry today. The novel sealing system of applicants&#39; invention incorporates a new and novel roller body design that works in conjunction with a separate annular body and annular seal to create a labyrinth or maze that effectively functions as a seal for preventing particulate matter infiltration into the roller housing. The roller body flange and annular body design incorporates a seating arrangement in which the annular seal rests between the two structures thus not exposing the annular seal to frictional stresses. The rollers incorporating the novel seal system of the present invention are not as susceptible to contamination by concrete particles found in varying consistencies of concrete mixes. The prevention of particulate matter infiltration allows the internal bearings and other moving parts to remain functional, leading to substantially less wear on the roller assembly and to a longer operative life for the internal components thereof. Moreover, the improved rollerhead of the present invention is designed to be as easily serviceable as prior art rollers. The design of the roller body, annular body, and annular seal are such as to allow the roller shaft drive unit to push through the roller body for inspection and servicing. The unique roller design permits ease of maintenance while limiting contaminate infiltration and associated rollerhead damage.  
         [0042]    It will be further understood that various other details or features of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation—the invention being defined by the claims.