Patent Application
20060169868
This invention relates to meter pits; and more particularly relates to a novel and improved precast concrete meter pit and to a method and apparatus for manufacturing same.
Meter pits for water meters are customarily fabricated out of plastic or stacked concrete in the form of a cylindrical pipe. The plastic meter pits typically sell at a higher price than concrete pits and tend to deform under certain conditions. The concrete-sectioned meter pits are assembled in segments using a tongue-and-groove connection which is labor intensive and also poses a safety risk when assembling the meter pits by hand which must be transported and assembled on site. The pipes are then buried in the ground, typically below frost level, and have an upper end which is adapted to receive a cover in order to withstand extremely cold temperatures and particularly to insulate the water meter from cold temperatures. However, there is a need for a meter pit which can be made of one-piece construction in a one-step slip form operation and which will afford the necessary support ledge for a cover.
In addition, packerhead assemblies have been devised for slip forming concrete pipe including a trowel assembly at one end of the packerhead assembly to form an outwardly directed, offset end but for several reasons are not practical for use as a meter pit. A representative patent is U.S. Pat. No. 5,080,571 to Crawford incorporated by reference herein in which a trowel assembly is employed in association with the packerhead assembly to specially shape one end of the concrete pipe; however, as will become hereinafter more apparent, the concrete pipe as manufactured in accordance with that patent is not conformable for use as a meter pit. Accordingly, there is also a need for a novel and improved method and apparatus for fabricating meter pits of one-piece construction with an upper edge which is capable of accommodating a cover.
Other representative patents in the field of concrete pipe making are U.S. Pat. No. 2,751,657 to Holston, U.S. Pat. No. 3,632,270 to Baker, U.S. Pat. No. 3,724,506 to Crowe, U.S. Pat. No. 3,922,133 to Crawford et al, U.S. Pat. No. 4,118,165 to Christian, U.S. Pat. No. 4,248,580 to Christian, U.S. Pat. No. 4,253,814 to Christian, U.S. Pat. No. 4,540,539 to Crawford et al, U.S. Pat. No. 4,690,631 to Haddy, U.S. Pat. No. 5,080,571 to Crawford, U.S. Pat. No. 5,215,604 to Crawford, U.S. Pat. No. 5,248,248 to Adly, U.S. Pat. No. 5,364,578 to Grau, U.S. Pat. No. 5,456,590 to Volmari, U.S. Pat. No. 5,616,351 to Wensauer and U.S. Pat. No. 5,648,108 to Hvidegaard.
It is therefore an object of the present invention to provide for a novel and improved meter pit and to a method and apparatus for making same.
It is another object of the present invention to provide for a novel and improved meter pit which can be fabricated out of concrete in a one-step slip forming operation.
It is a further object of the present invention to provide for a novel and improved apparatus for manufacturing precast concrete meter pits in a simple and efficient manner.
It is a still further object of the present invention to provide for a precast concrete meter pit having a thickened support ledge at one end which is capable of supporting the standard cover for meter pits.
In accordance with the present invention, a meter pit is comprised of an elongated precast concrete pipe of generally cylindrical configuration having a support ledge at one end and wherein the pit is made from the steps of positioning a pallet of a packerhead assembly on a turntable, the packerhead assembly including an outer concentric jacket and an inner spaced concentric rollerhead provided with a trowel, the trowel having a radially inwardly and downwardly inclined lower edge which forms an inner surface of the support ledge, injecting concrete into an annular space between the jacket and rollerhead for downward flow until the space is entirely filled, and raising the rollerhead and trowel as the annular space is being filled.
The preferred apparatus is of the type for making a precast concrete meter pipe characterized by a packerhead assembly including a longbottom assembly and a rollerhead assembly, a jacket in outer spaced concentric relation to the packerhead assembly, and means for rotating the packerhead assembly and characterized by the longbottom assembly including a trowel being of generally cylindrical configuration and terminating in a radially inwardly and downwardly inclined lower edge, and an annular pallet positioned beneath the trowel having a riser circumscribing an inner annular edge thereof and extending upwardly within the trowel. In practice, the pallet is vibrated as the concrete is advanced by gravity flow through the space between the jacket and packerhead assembly to rapidly fill and pack the entire space beginning with the enlarged area between the lower end of the trowel and jacket.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of preferred and modified forms of the present invention when taken together with the accompanying drawings in which:
There is illustrated in
The terminal end 14 of the beveled edge 13 is substantially flat and squared to the longitudinal axis of the pipe so as to form a ledge or seat for supporting a generally bell-shaped cover 16. The cover 16 is of standard construction including spaced projections or posts 18 which fit inside the ledge 13 and help to position and situate the cover 16 on the support ledge 13. The cover 16 is commonly referred to as a double lid cover which provides a dead air space between the top lid and the interior of the pit 10. The dead air space acts as an insulator, retaining pit heat and keeping outside cold air from entering. The meter pit as described is equally conformable for use with single lid covers and flat covers which may be utilized in milder climates. Grade rings (not shown) may also be inserted between the cover 16 and the support ledge 13 to adjust the height of the cover 16 to match the surface grade.
A preferred form of apparatus 20 for manufacturing meter pits 10 is illustrated in FIGS. 2 to 5 and is broadly comprised of a jacket or form 22 mounted on a pallet 34. The pallet 34 and the jacket 22 are mounted with a forklift onto a bottom centering plate 24 having upright centering blades 26 at uniformly spaced circumferential intervals along with shims 28 around the outside of the jacket 22. The centering plate 24 has been previously mounted on a turntable 32. The meter pit pallet 34 which is of special design allowing a trowel 44 to extend along an outer circumference of the pallet 34 is aligned for contact with a vibrator unit 36. The vibrator unit used is manufactured by Besser International Pipe Machinery of Sioux City, Iowa, Part No. 2100917 having a vibrational maximum of 3,600 rpm and an impact maximum of 10,000 lbs. An 18″ turning and vibrating standard or TV stand 53 also manufactured by Besser International Pipe Machinery, Part No. 0801433 is mounted above the vibrator unit 36. The pallet 34 rests on the TV stand allowing for both rotation and vibration of the pallet 34. A packerhead assembly 39 includes a rollerhead assembly 38 which is mounted for rotation on a packer shaft 40 and a longbottom assembly 42 which is comprised of a mounting flange (not shown) and the trowel or trowel assembly 44. The jacket 22 is in outer spaced concentric relation to the rollerhead and trowel assemblies. The rollerhead assembly 38 is of standard construction and, for example, is disclosed in hereinbefore referred to U.S. Pat. No. 5,080,571, incorporated by reference herein. However, the longbottom assembly 42 which is positioned directly beneath the rollerhead assembly and joined for rotation therewith includes the trowel 44 which inclines somewhat diagonally and inwardly in a downward direction with a lower edge 46 bearing lightly against a riser portion 48 of the pallet 34. The pallet 34 is annular and positioned beneath the trowel assembly 44, an inner annular edge 49 of the riser 48 extending upwardly within the trowel assembly 44. The pallet 34 is also at spaced intervals around the inner surface of the riser 48, and downwardly projecting flanges 52 which serve to aid in rotation and vibration of the pallet and also serve to act as stabilizers when the pallet 34 is placed on an uneven surface. A top centering plate or cover plate 55 is bolted to a top table 55 and is positioned on the jacket 22 with centering blades 26′ and has downwardly projecting lobes 56 at spaced circumferential intervals to form the notches 15 for insertion of the water lines as described.
In the standard pipe making process as employed in the hereinbefore referred to U.S. Pat. No. 5,080,571, concrete is injected into the space between the jacket and rollerhead wherein the longbottom assembly and rollerhead assembly are rotated in opposite directions as they are advanced upwardly so as to compact the concrete with centrifugal force and packing pressure from the rollerheads in accordance with standard pipe making procedures. Also, when used in association with the pallet in pipe making processes, the pallet is caused to spin and to vibrate. In the present invention, however, the pallet typically only vibrates but is capable of spinning.
In accordance with the present invention, the meter pit 10 is fabricated upside down by the apparatus 20. Specifically, the pallet 34 permits the longbottom assembly and more specifically the trowel 44 to extend around the outer circumference of the pallet in forming the support ledge 13 with an inner beveled surface portion 14′. For this purpose, the pallet 34 has the beveled edge 49 on the riser 48 to assist in centering and sliding the trowel assembly around the outer edge of the pallet. However, the pallet does not spin as typically required for pipe making but instead is journaled with respect to the table and caused to vibrate in a manner to be described. It is important to note that while the manufactured meter pits of this invention does not typically require rotation of the pallet 34, further compaction of the cement may be achieved with rotation as well as vibration of the pallet 34.
Summarizing the steps followed in the meter pit fabrication procedure:
1. Set up machine 10 for meter pit manufacture which consists of mounting the centering plates 24 to the turntable 32 and mounting the TV stand 53 onto the vibrator unit 36.
2. Mounting the jacket 22 onto the pallet 34.
3. Mounting the jacket 22 and the pallet 34 onto the centering plates 24 with a forklift.
4. Rotating the turntable 32 which includes the jacket 22, the pallet 34 and the centering plates 24 into alignment with the TV stand 53.
5. Lowering the packerhead assembly 39 within the interior of the jacket 22.
6. Aligning the trowel assembly 44 with the pallet 34 with the aid of the beveled edge 49 on the riser 48.
7. Start filling the form with concrete as the packerhead starts to spin. Preferably, a zero-slump concrete is utilized which will not tend to run or bulge out, and the concrete is packed in by the packerhead assembly as it starts to spin. The vibrator unit 36 also aids in packing the concrete. Thus, very little compaction time is required in forming the support ledge 13 before the packerhead assembly 39 starts to move upwardly.
8. Complete the filling operation as the rollerhead and trowel assemblies reach the top of the form.
9. Raise the packerhead assembly 39.
10. Rotate the turntable 32 away from the rollerhead and trowel assemblies and remove the jacket 22 and pallet 34 from the centering plate with a forklift.
11. Release jacket latches 23 and slide the jacket 22 vertically, using the forklift, off of the pallet and continue sliding until the jacket 22 clears the top of the concrete for the meter pit.
Basically no further finishing steps are required before the meter pit is installed in the ground in a right-side-up position with the support ledge 13 at the upper end and with the notches 15 being at the lower end and straddling the water lines.
It is therefore to be understood that while preferred forms of invention are herein set forth and described, the above and other modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and reasonable equivalents thereof.
