Concrete Products

SEP 2015

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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www.concreteproducts.com September 2015 • 39 The Molin Concrete Ramsey production line, as configured by Weckenmann and companion equipment suppliers, routes the 12- x 40-ft. panel pallets on an efficient course: Cleaning/plotting/oiling station. Production data is transferred via a CAD interface to a host computer. Pallets move through a cleaning machine. Mould station. Lasers plot the outline for shuttering moulds on the pallet. Cleaned moulds are picked up with the shuttering transport cross beam and either stored in a magazine or placed directly on the pallet as required. Custom formwork, if necessary, is executed by hand. Pallets and moulds are automatically oiled. Reinforcement station. Prefabricated panel reinforcement cages or mats and lifting anchors are placed in the mould by crane; sockets and conduits are attached to the pallet surface. Buffer station. Pallets with panels that require complex elements, such as upstands, are moved from the conveyor line to the buffer station by transverse trolleys so that this operation does not slow down the plant circulation system. The buffer stations handle anything that takes more time than normal to set up, such as laying in brick in a form liner, placing numerous reveals not created by a form liner, and complex shapes (circles, curves, angles, etc.). Concreting/shake table station. Concrete is poured into the formwork contour according to the product being manufactured. Concrete discharge dosage is controlled via a moving control panel by opening and closing the dosing flaps in the concrete spreader. Concrete test cubes are taken. Following this process, the agitator or shake table is activated. The station includes two transverse trolleys to move the pouring buckets under the mixers to be recharged with concrete. Insulation station. For sandwich wall panels, insulation (either foam or board) is inserted at this station using cross-lifting trucks. This is done after the first shell is concreted. Reinforcement station. Reinforcement for the load-bearing shell of sandwich wall panels is laid on the insulation layer by crane and anchors for lifting are mounted. The second shell is then concreted and placed on this assembly. Screeding station. A screed board on the concrete spreader, along with vibration or shaking, removes protruding concrete and excess water. Curing chamber/storage stations. The pallet is then passed via an elevator system to a shelf in the storage and retrieval area and into the curing chamber racks for curing. The curing camber is considered two work stations in the plant since it has two bays, each with nine pallet positions. Demoulding station. Moulds are removed at this station. Integrated magnets of the moulds are manually released with lever tools and lifted from the pallet with a cross beam and handling traverse and placed on the shuttering conveyor transport. The moulds pass automatically through the cleaning equipment and are then available for shut- tering again. Custom formwork is stored in a special magazine. Troweling station. Panels are elevatored up to a helicopter troweling machine area atop the curing chamber. After troweling by the hand-held tool, the panel is automatically stored on a rack again by the stacking device. Buffer/lifting station for horizontal loading. Pallets are moved to this station right before demoulding via two cross-lifting trucks. Tilting/lifting station for vertical loading. Station con- sists of two hydraulically pow- ered tilting arms actuated by hydraulic cylinders designed to tip pallets vertical to allow an unloading crane to lift wall ele- ments undamaged from the pal- let and either stored or loaded for shipping to a job site. Molin Concrete crews and equipment suppli- ers turned the Ramsey plant project in well under 12 months. PALLETS' PATH: 14 WORK STATIONS FEATURE MOLIN CONCRETE The insulated panel is then screeded and shuttled off to the curing chamber. It sits in the curing chamber, set at 120°F with 100 percent humidity, for two to three hours. Initially, the curing chamber will be able to stack 18 pallets but capacity will eventually be expanded to 27 pallets. The panel is then pulled out and lifted to the top of the cham- ber by an automated elevator system, where helicopter troweling machines screed it smooth; then, back into the curing chamber for a final cure. To save plant space, the trow- eling station sits atop the curing chamber. Next stop on the plant-long conveyor sys- tem is the stripping station, which consists of a large tilt table. It automatically tilts the completed assembly horizontal and the pan- el is de-molded from the shuttering profile elements and form. The tilt table is a crit- ical piece of equipment. Traditional precast plants strip panels when they are laid flat. A poured concrete panel undergoes extra stress from the suction when it is stripped from its form while flat. In typical precast plants, wall panels are handled, stored and shipped flat, and rotated at the job site. In the new Molin plant, the panels are stripped, stored and shipped vertically. Finally, automated equipment sets the finished precast panel on a run-off bunker or truck that holds multiple panels. The bunker is rolled outside the plant beneath a gantry system that electronically picks up each panel and places it either in storage in the plant yard or loads it on a truck for speedy delivery to a project. Additional information on the plant and car- ousel production method can be obtained from Molin Chief Operations Officer Matt West- gaard, 612/889-6794, mattw@molin.com; or, John Saccoman, 612/720-2883, johns@ molin.com. Overhead view of the concrete spreader with the batch plant in the upper left-hand corner and curing chamber to the right.

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