- Published: Thursday, 01 October 2009 08:00
- Written by CP Staff
AmeriTex Pipe & Products, LLC has launched with a Seguin, Texas, greenfield operation just off coast-to-coast Interstate 10. Equipped with European machinery, the plant is geared to versatility in small-, medium- and large-bore pipe and box products. Instead of full-scale automation, AmeriTex founder Kevin Thompson has steered initial investment toward 1) a deep formwork inventory supporting round and box structures across the size spectrum; 2) machinery whose proprietary compaction and vibration mechanisms assure quality, while limiting pipe and box production line workers' exposure to excessive noise; and, 3) tall mast forklift trucks that speed pipe handling, enable casting of product in 12-ft. lengths, and help optimize ambient-curing area footprint.
Greater automation can be achieved one robotic device at a time, as production requirements change and the company secures a foothold in the central Texas concrete drainage products market. For now, AmeriTex has a sufficiently speedy configuration around two machines, each capable of running with two-man crews.
Located about an hour east of San Antonio, the Seguin plant marks the North American premier of current-generation pipe and box machinery from Schlosser-Pfeiffer GmbH, as well as the company's first delivery to this side of the Atlantic since merging with German neighbor Hess Group. Separate high bays house SP Radial Press and Variant machines; they flank a taller central bay sheltering floor-mounted cement silos and a twin-mixer mezzanine. Atlanta-based H/P Industries Inc., Schlosser-Pfeiffer's North American representative, provides Concrete Products the following machinery and technology overview.
SP RADIAL PRESS
The high-speed, high-performance model produces 12-in. to 60-in.-diameter pipe in 4-, 8- and 12-ft. lengths. With high drive power, it is geared to reinforced and nonreinforced bell end pipe, jacking and rocker pipe, pipes with two spigot ends, and manhole risers. In lieu of a machine operator, forklift drivers activate the SP Radial Press Û running on a Siemens S7 electronic PLC Û with remote controls.
Belted from a dedicated mixer on the central bay mezzanine, concrete is compacted during the radial pressing process, whereby a distributor head moves in the opposite direction of a pressing head. Independently controlled, the torque of each head largely cancels the other out, imparting precise and tension-free reinforcing cage embedment. The pressing tools' high-performance electro-hydraulic drive unit replicates the curve characteristic of a radial press, securing maximum process capacity at minimum energy consumption.
SP Radial Press pipe molds are fitted with cage positioners, eliminating the need for spacers on the outside of reinforcement cages. The absence of spacers reduces the points of potential water intrusion to finished products' inner reinforcement.
The SP Radial Press has a host of options for off-bearing and handling of finished pipes inside the molds: forklift truck, crane, or demolding robot and evacuating robot, the latter with or without a moving floor. AmeriTex opted for forklift off-bearing with an overhead stripping process, a mode that matches tonnage output and product variety targets.
Schlosser-Pfeiffer engineers one-piece molds with a seam that opens slightly to assist stripping. A special forklift attachment picks the molds, and opens and closes the seam and pallet retainers. The overhead form-stripping method affords tight spacing of green pipe. The forklift mechanism's automatic latching and unlatching of the seams and retainers eliminates the need for a worker performing those functions manually within the curing area. AmeriTex has started the SP Radial Press line using two forklifts. At optimal speed, the machine requires two forms for medium-bore and three forms for small-bore products.
The two-station Variant dry-cast machine is the first of its kind from Schlosser-Pfeiffer. Each station is equipped with a central tree consisting of three powerful vibrators. Solid pipe or box mold cores slide down over the vibrator tree and are locked in place. For box culverts, there are adjustable form jackets and base pallets. The configuration equips AmeriTex with a wide range of capability, from 4- _ 2-ft. to 12- _ 12-ft. boxes, to large-diameter round, arch or elliptical pipe.
The Variant works below floor level to minimize noise and absorb vibrations. Compaction is achieved by a central vibrator connected to the core via a hydraulic clamping device, a feature promoting rapid mold changes. The jacket with base pallet is rubber-buffer isolated and mounted separately from other machine components to ensure proper induction of vibration into the product. The centrifugal force is also individually adjustable in accordance with box size or pipe diameter.
Concrete for the two Variant stations travels an incline conveyor from a dedicated mixer on the mezzanine in the adjacent bay. The conveyor feeds a hopper, which in turn charges a rotating belt. The latter feeds mix evenly into the molds without the potential segregation encountered using a chute. Mold-filling speed is individually adjustable for all production circumstances.
The advantages of this feeding and vibration technology, Schlosser-Pfeiffer contends, include high-grade and uniform compacting, consistent product wall thickness, optimal coating of the reinforcements, smooth inside and outside surfaces, and dimensional accuracy.
To shape the spigot ends, a forming ring is first applied with its dead weight only (free load), allowing even mix distribution. A hydraulic superimposed load can be added as needed. The spigot end is smoothed by a forming ring's oscillating rotary movements. The result, product engineers note, is precisely shaped spigot ends suitable for gaskets designed to conform to narrow tolerances.
To maintain dimensional accuracy, boxes and pipes remain inside their mold jackets while being transported to the de-molding area, which like the SP Radial Press bay is set up for ambient curing. Optional hydraulic cylinders augment de-molding and reduce crane loads. The Variant can run with two operators, including one to control the bridge crane. During the return transport back to the subfloor stations, the reinforcing cage and the next base pallet are loaded and again inserted into the machine. Reinforcements may be designed as single or multiple cages, as required. Precision positioning is also possible via the hydraulically operated centering units at the mold jacket.