Abstract:
A concrete pipe making machine having a packerhead consisting of a rollerhead and a longbottom in which the rollerhead and longbottom are quickly assembleable and disassembleable as a unit from the packerhead drive means with one connector and brought into final adjustment off the machine, said drive means providing no obstruction to the flow of wet concrete toward the compaction area, the speed ratios between the rollerhead and longbottom being infinitely variable, and easily replaceable protective wear rings for precluding erosive deformation of the permanent parts of the machine due to undesired penetration of wet concrete into the longbottom.

Description:
[0001]    This invention relates generally to the field of concrete pipe manufacturing machinery and methods. It is more specifically directed to the packerhead system of manufacturing concrete pipe of which the disclosures in U.S. Pat. Nos. 4,540,539 and 5,080,571 are exemplary.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the packerhead system of concrete pipe manufacture a packerhead which consists of a rollerhead, or roller assembly, and a trowel, more frequently referred to as a longbottom, are lowered into a circular mold and rotated as they move upwardly, all the while packing wet concrete, which is dropped onto the packerhead, against the inner wall surface of the mold. Although well functioning machines are available which produce good quality pipe, both wire reinforced and non-reinforced, as epitomized by the machine disclosed in U.S. Pat. No. 4,540,539 and further improvements thereon as represented by U.S. Pat. No. 5,080,571, market dynamics require that pipe quality be further improved.  
           [0003]    In this connection it is necessary to appreciate that industry engineering and quality standards are continually increasing, particularly with respect to reinforced pipe. As has been well known for many years, when the wire cage which constitutes the reinforcement in a concrete pipe is twisted or otherwise prevented from making a good bond with the concrete, undesirable voids form which will cause the pipe to fail post production D-load testing, which simulates fill soil loading on the pipe, and water pressure testing, or, if the tests are passed, to fail prematurely in the field. The underdesireable voids form due to twisting of the wire cage in the manufacturing process, the twisting resulting from the pressures of the rollerhead and troweling surfaces against the wet concrete, said pressures, when unbalanced, eventually exerting a twisting force on the wire cage. The cage twist phenomena can be substantially reduced by the system disclosed in U.S. Pat. No. 4,549,539 but the relationship of the speed ratios between the rollerhead and the longbottom cannot be controlled precisely enough in current machines to totally eliminate cage twist. More importantly, current systems, due to the lack of precise control of the aforesaid speed relationships, are not well suited to automatic control which, it is now known, produces the most economical and consistently high quality pipe since operator judgment, and possible misjudgment, is eliminated. Further improvements dictated by market pressures include increased production rates, component life increase, and capital investment decrease by increasing the number of sizes of pipes that can be made on a single machine.  
         SUMMARY OF THE INVENTION  
         [0004]    The invention is a concrete pipe making system capable of producing either reinforced or nonreinforced concrete pipe, though its benefits are realized to a greater extent in the production of reinforced pipe. The system includes a method of delivering wet concrete to a packerhead in a more uniform manner so that a steady state flow of wet concrete can be placed against the mold wall by the packerhead, thereby resulting in a very constant and smooth wall thickness free of slight depressions and bulges as is often encountered in current machines.  
           [0005]    The invention also includes a unique packerhead which eliminates all obstructions to the feed of wet concrete so that a steady state flow of wet concrete can be presented to the mold wall preliminarily to packing and smoothing by the rollerhead and the longbottom.  
           [0006]    A further feature of the invention is an infinitely variable drive system for both the rollerhead and the longbottom whereby optimum rollerhead-longbottom speed ratios can be attained so as to produce pipe which is always within specifications. Of equal importance, such a drive system is ideally adapted to automatic control so that ideal operating conditions (rate of feed, pressure of compaction, etc.) can be consistently maintained and operator error eliminated.  
           [0007]    The invention further includes a unitized packerhead which can be assembled and disassembled to the drive system of the machine much quicker than in prior art machines. The saving of time is further increased by the unique design of the packerhead which permits assembly and adjustment of all parts in the packerhead prior to changeover rather than after initial assembly, as is, currently the norm.  
           [0008]    Another advantage of the invention over existing machines is a marked increase in the life of those component parts of the machine which are subject to wear due to contact with the chemically and physically erosive wet concrete during the pipe manufacturing process, said advantage being achieved by the use of inexpensive, readily attachable and detachable components which are in contact with the wet concrete while at the same time protecting the customized components of the machine.  
           [0009]    A further great advantage of the invention, particularly for pipe plants of smaller size, is the expansion of the range of sizes of pipe that can be manufactured on one machine, such as enabling 12″ and 15″ pipe to be made on a 60″ machine, as contrasted to a former minimum pipe size of 18″, thereby allowing the pipe plant operator to invest in only one machine instead of two for making the full range of the highly popular 12″ to 60″ pipe sizes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]    The invention is illustrated more or less diagrammatically in the accompanying drawing in which  
         [0011]    [0011]FIG. 1 is a section view with portions omitted for clarity of a counter rotating packerhead in wide use at the time of this invention and over which the present invention constitutes an improvement;  
         [0012]    [0012]FIG. 2 is a section view with parts omitted for clarity of the packerhead of this invention, here a counter rotating packerhead;  
         [0013]    [0013]FIG. 3 is a side elevation with portions omitted and others broken away for clarity of the outer packer tube which drives the roller assembly of the present invention; and  
         [0014]    [0014]FIG. 4 is a side elevation with portions broken away for clarity of the infinitely variable dual drive system of the present invention.  
         [0015]    In the following description of the invention like reference numerals will refer to the same or similar parts from Figure to Figure. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0016]    Referring first to FIG. 1, a counter rotating packerhead assembly (hereafter referred to as the packerhead) of the prior art is indicated generally at  10 . The packerhead includes a rollerhead assembly, or simply a rollerhead, indicated generally at  11 , and a troweling assembly, usually referred to as a longbottom, indicated generally at  12 .  
         [0017]    The rollerhead  11  includes a roller assembly, indicated generally at  13 , which comprises a plurality of smoothing rollers, usually four, one of which is indicated at  14 . The rollers  14  are carried by a roller mounting plate  15  which is fast with lower drive tube  16 . A roller hood which occupies the spaces between the rollers  14  is indicated at  17 , the function of the roller hood being to intercept wet concrete fed from above before it drops below the tops of rollers  14  and, also, to ensure radially outward flow of the wet concrete toward the inner wall of the mold, not shown. The roller hood  17  is spaced from the roller mounting plate  15  by a plurality, here eight, support pins  18  which are removeably secured to the roller mounting plate  15  by bolts  19  and, at their upper ends, welded to the underside of the roller hood  17 .  
         [0018]    The rollerhead further includes an upper drive tube  20 , the upper and lower portions of the drive tube being connected by flange means  21  consisting of a lower flange  22  surrounding the upper end of lower drive tube  16 , an upper flange  23  surrounding the lower end of upper drive tube  20  and bolts  24  which connect the upper and lower drive tubes  16  and  20 .  
         [0019]    A protective enclosure is indicated generally at  25  surrounding the upper end of the upper drive tube  20 .  
         [0020]    The longbottom  12  includes a circular bottom plate  28  having apertures  29  therein for access to rollers  14 . A circular mounting flange is indicated at  30  at the extremity of bottom plate  28 , the mounting flange carrying a smooth, circular troweling member  31  which is secured entirely around the periphery of the mounting flange by any suitable fastening means, here recessed bolts  32 . The troweling member  31  is usually composed of a plurality of individual sections, each of which is contoured, when assembled, to form a circular outer periphery.  
         [0021]    The circular bottom plate  28  is connected to a stub sleeve  34  by bolts  35  and flange  36  which is fast with the stub sleeve  34 . A spline ring having an interval spline is indicated at  37  extending upwardly from stub sleeve  34 . The splined stub sleeve  34  mates with an external spline  38  located near the bottom of longbottom drive shaft  39 . The lowermost end  40  of drive shaft  39  is received in the bore in stub sleeve  34 . Drive shaft  39  is secured to longbottom plate  28  by nut  42  which is screwed onto the threaded end of drive shaft  39 . Bushings  44  and  45  space the longbottom drive shaft  39  from the lower drive tube  16  and the upper drive tube  20 .  
         [0022]    The upper ends of upper drive tube  20  and shaft  39  are secured by bolts  48 ,  49  respectively to stationary supporting structure and a drive system which powers drive tube  20  and drive shaft  39 . For an understanding of supporting structure which is suitable for both the prior art disclosure of FIG. 1 and the invention disclosed herein, reference is made to U.S. Pat. No. 4,540,539 and particularly FIG. 1 thereof.  
         [0023]    Referring now to FIG. 2 the packerhead of this invention is indicated generally at  50 . The packerhead includes a rollerhead indicated generally at  51 , and a longbottom, indicated generally at  52 .  
         [0024]    The rollerhead  51  includes a roller assembly, indicated generally at  53 , which comprises a plurality of smoothing rollers, here four, one of which is indicated generally at  54 . The rollers  54  are carried by a roller mounting plate  55  which is secured to lower drive tube assembly  56  by bolts  57  which connect the drive tube assembly flange  58  to an inner circle of threaded holes in roller mounting plate  55 .  
         [0025]    The roller  54  is mounted on a bearing supported shaft  59  whose lower portion  60  is received in an eccentric bearing  61 , the rotatable shaft  59  being secured to the roller mounting plate  55  by nut  62 . It will be understood that in operation it is desirable that the edge of the smoothing roller  54  in contact with the freshly layed up wet concrete be at the same radial distance from the axial center line  63  of the packerhead as is the periphery of the longbottom  52 , and, on occasion depending on circumstances, even at a slightly greater radial distance. From an examination of the eccentric bushing  61  it will be seen that the wall thickness of the bushing varies so that the outer, concrete contacting surface of roller  54  can be moved radially inwardly and outwardly depending on the rotative relationship between the bushing  61  and roller mounting plate  55  derived from the placement of radial adjustment bolts  64  in the bottom flange  65  of bushing  61 . Often the operator desires that the concrete contacting surface of roller  54  project radially outward from axis  63  a slightly greater distance than the periphery of longbottom  52 .  
         [0026]    A roller hood is indicated at  68 , the hood  68  being essentially a circular flat plate with round cutouts to accommodate the rollers, the top surface of the roller hood  68  preferably being co-planar with the top surface of the rollers  54 . Wet concrete distributing blades  69  are welded to and extend upwardly from the roller hood  68 .  
         [0027]    Roller hood  68  is connected to and fixedly spaced from mounting plate  55  by support pins  70 . Upper bolts  71  secure the roller hood  68  to the upper ends of pins  70  and lower bolts  72  secure the lower ends of pins  70  to the mounting plate  55 .  
         [0028]    Roller mounting plate connecting flange  58  projects outwardly from the lower portion  73  of the drive tube assembly  56 . The bottom interior bore of lower portion  73  is recessed as at  74  to snugly, but rotatably, receive the upstanding portion of the longbottom drive system as will be more fully explained hereafter. A very slight clearance exists between the outside of lower portion  73  of the drive tube assembly and the center hole in the roller hood  68 , the clearance being sufficiently large to preclude any binding between the two components but close enough to preclude fresh wet concrete from penetrating past the roller hood  68 .  
         [0029]    The lower portion  73  of the drive tube assembly  56  extends upwardly a short distance to its top end, indicated generally at  76 . An external spline  77  is formed on the upper end of lower portion  73 .  
         [0030]    The upper portion of drive tube assembly  56  is indicated generally at  79 , see FIG. 3 as well. A drive transfer sleeve  80  is welded as at  81  to the lower end portion  82  of upper portion  79 . An internal spline  83  is formed on the periphery of lower end portion  82 , said internal spline  83  matching the external spline  77  on lower portion  56 .  
         [0031]    The upper end of upper portion  79  terminates in a top flange  84  which is secured by bolts  85 , see also FIG. 4, to the stationary support structure described earlier and the drive system to be described hereinafter.  
         [0032]    Longbottom  52  includes a circular bottom plate  88  having center mounting hole  89 . A circular mounting flange is indicated at  90  at the periphery of the bottom plate  88 , the mounting flange carrying a smooth circular troweling member  91  which is secured entirely around the periphery of mounting flange  90  by a suitable fastening means, here recessed bolts  92 . The troweling member is usually composed of a plurality of individual sections, each of which is contoured, when assembled, to form a circular outer periphery.  
         [0033]    The bottom plate  88  is connected to a flange  93  on the bottom end portion of spline socket  94  by bolts  95 . Plate  88  is a horizontal plate that is part of the longbottom frame. The plate has openings  87  cut in it that are oriented to the roller locations. The roller mounting assembly and longbottom assembly can be rotated in respect to each other so that the openings  87  in plate  88  are aligned with the rollers. It is therefore possible to access the bottom nut  62  of the roller and remove it without disassembling the two main rollerhead assembly components or having to remove the entire unit from the machine.  
         [0034]    Openings  88  also allow the following:  
         [0035]    Access to the eccentric bushings  61  of the rollers for radial position adjustment when necessary, while the unit is still assembled;  
         [0036]    Access to the bearing outside housing screws  103  to allow disassembly of the two main units;  
         [0037]    Enable any concrete slurry that passes between the wear plates  108 ,  110 , of the mountings to flow out through plate  88  of the longbottom frame;  
         [0038]    Weight reduction without affecting the strength significantly of the longbottom frame.  
         [0039]    Spline socket  94  extends upwardly inside the recess  74  in the lower portion of the drive tube assembly  56  in a snug fitting, non-binding relationship so that the spline socket  94  and lower portion  73  of drive tube assembly  56  can rotate relative to one another. A lower internal recess in spline socket  94  is indicated at  96  and an upper larger internal recess is indicated at  97 . Recess  96  has an internal spline  98 , and recess  97  has the aforementioned internal spline  74 .  
         [0040]    A longbottom drive shaft is indicated at  100 . An upper external spline is indicated at  101 , said upper spline mating with the internal spline  97  on the spline socket  94 . A lower external spline is indicated at  102 , said lower spline mating with the internal spline in the lower socket recess  96  of spline socket  94 . Although in this instance two spline and socket systems have been illustrated on the single drive shaft  100 , it is preferable that the upper spline system be used to drive larger sized longbottom assemblies and the lower spline system be used to drive smaller sized longbottom assemblies. In other words, the spline socket  94  may carry only one internal spline, the location of the spline depending on the size of the longbottom.  
         [0041]    An important feature of the invention is that the packerhead  50  is unitized in the sense that the rollerhead  51  beginning with the roller hood  68  and the longbottom  52  are one piece, and only a single connection step is needed to change from one packerhead, say a 12″ size, to another packerhead size, say a 60″ size, or vice versa, or any combination of sizes between the extremes the machine is designed to use. This will become apparent from the following description.  
         [0042]    Referring to FIG. 2 a large sealed bearing is indicated generally at  103 . The bearing  103  is secured to the underside of roller mounting plate  55  by bolts  102 . The inner race  104  of the bearing seats on an external ledge  105  in spline socket  94 . The parts are assembled as illustrated in FIG. 2 by screwing drive shaft nut  106  onto the bottom, threaded end of longbottom drive shaft  100 . To disassemble, the nut  106  is unscrewed and both the longbottom  52  and the rollerhead  51  are slid off the drive shaft  100  as a unit, thereby making possible an exceedingly quick change of packerheads either for reasons of a need to make a different size pipe or to service the initial packerhead while a duplicate packerhead is assembled as a replacement. These changes are accomplished by putting on or taking off a single component, nut  106 , and the removed packerhead can be worked on at leisure and without requiring down time on the machine.  
         [0043]    Alternatively, to disassemble rollerhead  51  from longbottom  52 , the screws  102  in bearing  103  of the outer housing can be removed. These screws can be accessed through the openings in plate  88 , or bolts  95  can be removed dropping the longbottom  52  from the unit. Unless there is a specific reason for doing different, the preferred way is to remove fasteners  95  rather than risk possible contamination or damage to bearing  103  by removing the outside housing retainer.  
         [0044]    Other important features of the invention are (i) its capability to far more effectively compensate for wear and (ii) drastically reduce jamming of the rollers due to the presence of wet concrete which seemp around the rollers and into the interior of the rollerhead  51 .  
         [0045]    Referring to FIG. 2 a wear ring  108  composed of a hard, wear resistant material, such as manganese steel, is tack welded to a base ring  109  which in turn is welded to the upper inside rim portion of mounting flange  90  so that the ring  108  moves with the longbottom.  
         [0046]    A second wear ring, or band, is indicated at  110 , said second wear ring being tack welded to the external periphery of mounting plate  55 . It therefore moves with the roller assembly  51 . The radial gap between the two rings is fixed at the optimum spacing which, for many mixes, is on the order of about ⅛ inch. This spacing precludes the entry of wet concrete, which has momentarily slipped below the bottom of rollers  54 , from penetrating into the interior of longbottom  52  from whence it could foul the ball bearing  103  or otherwise interfere with the performance of the machine, particularly the rollerhead  51  by causing the rollers to jam up.  
         [0047]    It should be understood that only one specific type of material is ideal for all sizes of rings  108  and  110 . In this connection, material cut from hot rolled chrome-moly steel plate stock of medium hardness having a significant manganese content and a Brinnell hardness diameter in the range of 212-255 will be quite satisfactory. This type of alloy steel, known by the trade name AR, has been used in such applications as a chute lining for gravel sand, cement, grain, clay and mud. For even tougher, higher strength applications, a similar chromium, molybdenum and manganese steel which is available under the trade name Kromite will give good performance. Such a steel may have a Brinnell hardness diameter of about 360, and even, as the application requires, up to 400 which is considerably more abrasion resistant than the AR type steel.  
         [0048]    The width of the rings or wear bands will most usually be on the order of about {fraction (3/16)}″ to ⅜″ depending on the viscosity and composition of the wet concrete. A typical width which is suitable for a very wide number of applications is ¼″. For smaller rollerheads, such as the 12″ or 18″ size and possibly even the 24″ size, a width of about {fraction (3/16)}″ will be quite satisfactory.  
         [0049]    When the type and composition of the two wear bands acting jointly are tched to the application, the wear problem, which was encountered in the cold rolled 1018, 1020 and A-36 type steel bands used in the machine disclosed in U.S. Pat. No. 5,080,571, were eliminated.  
         [0050]    The feature of adjusting the twisting forces exerted by the rollerhead assembly  51  and the longbottom  52  on the freshly layed up and still wet concrete, and thereby on the wire reinforcement cage encased therein, is illustrated in FIGS. 2 and 4.  
         [0051]    Referring to FIG. 4 primarily, a rollerhead drive gear box is indicated at  112 , said gear box  112  being bolted to and spaced underneath the stationary support structure  113  by bolts  114 . The gear box  112  is driven by a variable displacement speed hydraulic motor  115  which in turn is powered by an electronics driven variable displacement hydraulic pump circuit.  
         [0052]    The output shaft of the rollerhead drive gear box  112  is represented schematically at  116 . Bolts  117  connect the top flange  84 , see also FIG. 2, of the upper portion  79  of the drive tube assembly  56  to the output shaft  116  of the rollerhead gear box  112 . Since the output of the hydraulic motor  115  is infinitely variable within the maximum system operating parameters, the speed of rotation of the drive tube assembly  56 , and thereby the roller assembly  53 , may be infinitely varied.  
         [0053]    A longbottom drive gear box is indicated at  120 , said gear box  120  being bolted to the stationary support structure  113  by bolts  121 . The longbottom gear box  120  is driven by a variable hydraulic motor  122  which in turn is powered by a hydraulic circuit and the electric motor in a conventional manner as earlier referred to.  
         [0054]    The output shaft of the longbottom drive gear box  120  is represented schematically at  123 . Bolts  124  connect the top flange  86 , see also FIG. 2, of the upper end of longbottom drive shaft  100  to the output shaft  123  of the longbottom gear box  120 . Since the output of the hydraulic motor  122  is infinitely variable within the maximum system operating parameters, the speed of rotation of the longbottom drive shaft  100 , and thereby the longbottom  52 , may be infinitely variable.  
         [0055]    Such a dual, infinitely variable hydraulic drive system lends itself to automatic control which results in consistent production of quality pipe on the machine.  
         [0056]    The use and operation of the invention are as follows.  
         [0057]    The manufacture of reinforced concrete pipe will be assumed since this type of pipe represents the most stringent and demanding operation of the pipe machine. In the reinforced pipe process it will be remembered that a circular cross-section wire cage composed of vertical stringers and circular rings of reinforcing wire are embedded within the wall of the concrete pipe. The concrete must completely envelope the wires because a close, contacting bond between the wire and the set up concrete must be achieved to avoid deficient performance of the pipe in use. Stated another way, there must be no voids between the wire cage and the concrete, due primarily, to uncompensated twisting forces of the wet concrete on the wire cage during manufacture; cage twist must be zeroed out as discussed in greater detail in U.S. Pat. No. 4,540,539.  
         [0058]    Since every pipe production operation never runs a given pipe production machine continuously on one size of pipe, and even those that have long runs require periodic checking and cleaning, the machine must be shut down periodically to remove a used packerhead and install a fresh packerhead.  
         [0059]    At the current time the shut down, removal and reinstallation is a lengthy process. To disassemble the conventional prior art packerhead of FIG. 1 for example longbottom drive shaft nut  42  must be removed and the longbottom  12  slid off longbottom drive shaft  39 . Thereafter bolts  24  must be removed to drop the rollerhead assembly  11 . To reinstall, the above described steps must be repeated in reverse order. However said steps cannot be simply repeated sequentially because the positioning of the rollers  14  must be done while the rollerhead assembly  11  is in its illustrated position, but prior to the further assembly of the longbottom to its drive shaft. Adjusting the rollers  14  is difficult and time consuming. All the while the reassembly of the rollerhead assembly, its adjustment, and the reassembly of the longbottom are taking place the machine is out of production. In today&#39;s highly competitive environment, down time results in lost production which eventually equates to lost revenue and lost profits.  
         [0060]    In the system of this invention by contrast it is only necessary to remove one component, drive shaft nut  106 , to slide the entire packerhead, that is, the rollerhead assembly  51  and longbottom  52 , simultaneously off the drive system. The moment the first packerhead is removed, a replacement packerhead can be assembled by threading one component, drive shaft nut,  106 , back onto drive shaft  100  and production resumed. If the removed packerhead requires readjustment or repair, that can be done in the plant&#39;s repair shop while the replacement packerhead is producing pipe. And of course the replacement packerhead will have been adjusted to the exact operating condition desired before it is assembled to the drive system. Of significance in the quick disassemble/assemble operation is the flexibility in making adjustments attributable to bearing  103 . Thus after the packerhead  51  is disassembled the longbottom  52  may be separated from the rollerhead  51  and conveniently reworked separately from the rollerhead. It may for example be only necessary to replace the longbottom wear ring  108 , and after this is done the packerhead is ready for quick reassembly.  
         [0061]    If on the other hand it is necessary to adjust the radial spacing of the rollers with respect to the central axis  63  this can be easily done because roller shaft nuts  62  are easily accessible as contrasted to having to work upwardly through the apertures  29  in the longbottom plate  28  of the prior art construction of FIG. 1.  
         [0062]    A further advantage of the present invention is the ability to quickly disassemble and reassemble the rollers only for cleaning. Since pin  18  in the prior art configuration of FIG. 1 is welded to hood  17 , the hood  17  can be easily removed to allow cleaning of the rollers  14 . Fasteners, or upper bolts  71  now provide easy removal of roller hood  68  whereby the rollers can be cleaned without removal of the rollerhead  51  from its drive system. As a result, the roller cleaning time has been considerably reduced, and potential damage of the components attributable to assembly and disassembly has been eliminated.  
         [0063]    It should also be noted that entry of wet concrete into the interior of the longbottom can be easily prevented without any degradation of any custom designed operating part of the longbottom. Although the use of a wear ring to impede the leakage of wet concrete into a longbottom has been tried, wear invariably occurred on one or more of the expensive, custom designed permanent operating components of the machine, resulting in its replacement and consequent substantial part replacement expense and production down time. By contrast in the system of this invention, whichever one, or both, of wear rings  108  and/or  110  require replacement, such replacement can be quickly accomplished by tack welding and the machine is immediately back into operation—with all the original, customized parts totally and permanently unaffected by contact with the erosive concrete.  
         [0064]    The invention provides a significant increase in the feed of wet concrete in machines of all sizes. Concrete feed to the rollerhead for internal forming of the pipe wall in the machine is done by using a conveyor which drops the concrete to the center of the rollerhead down along the perimeter of the drive shaft. The bolted flange means  21  on the prior art construction of FIG. 1 was a restricting factor on the amount of concrete that can be effectively dropped into the formation area formed by the top of roller hood  17  and the rollers  14 . In the present invention the elimination of the obstructing flange means  21  eliminates the prior significant obstruction and provides much better concrete flow into the compaction area. Elimination of the impediment to flow is derived from the use of the splined connections illustrated best in FIGS. 2 and 3 at  77  and  83 .  
         [0065]    A further significant contributing factor to the greatly improved consistency of the final product and increased production per unit of time is shown in FIGS. 2 and 4. In all known prior art systems only incremental speed steps for the drive system are possible. As a consequence a premium is placed on operator skill to produce consistently acceptable product because other operating factors, such as rate of feed of the wet concrete, have to be made to accommodate operational changes which cannot be achieved, by comparison, by the somewhat crude drive speed control systems currently in use. This problem is completely eliminated by the layering of one infinitely variable drive speed control for one component in the packerhead onto the other infinitely variable control of the other component in the packerhead. Thus, as best visualized from FIG. 4, the speed of both the longbottom and the rollerhead can be set to any desired ratio. This is especially useful in the counter rotating packerhead system because, even if one of the rotating components is infinitely variable, the step-only adjustment of the other rotating component would not produce the optimum speed relationships to produce high quality pipe in a high output pipe plant.  
         [0066]    The illustrated system has the further advantage of being ideally suited to automated production in which operator expertise is greatly reduced in importance. Thus, once the final product specifications are known and the characteristics of the raw materials and their mixture ratios are decided, the parameters can be dialed into the control console and the plant started up with the assurance that the first pipe and the last pipe in any run will be of the same uniform acceptable quality.  
         [0067]    Although a specific embodiment of the invention has been illustrated and described it will be apparent to those that modifications can be made within the skill of the art. Accodingly it is intended that the scope of the invention be limited only by the scope of the hereafter appended claims in light of the relevant prior art.