Road structure – process – or apparatus – Apparatus – With means for profile shaping – e.g. – crown
Reexamination Certificate
2000-11-16
2003-04-01
Hartmann, Gary S. (Department: 3671)
Road structure, process, or apparatus
Apparatus
With means for profile shaping, e.g., crown
C404S096000, C425S063000, C425S064000, C249S002000, C249S008000
Reexamination Certificate
active
06540435
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a curb mold and extruding system used in forming concrete, cement or other building materials into curbs, gutters, barrier walls, sidewalks, and the like quick and easily on construction projects.
BACKGROUND OF THE INVENTION
The present invention relates to a mold used for concrete formation. More particularly, it relates to an extrusion molding device, which when connected to a conventional concrete pump, or other like apparatus, extrudes concrete, cement or other similar building materials into a multitude of shapes to be used in the construction field as curbs, gutters, barrier walls, sidewalks, and the like. In the past, it has been necessary to use hand placed, wood, or metal forms to be assembled, taken apart, and reassembled through out the project. This process is labor and time intensive, requiring the material to harden before the molds may be removed. In the area of sidewalks, the concrete must be roughly smoothed between the forms, this is called screeding, then it is float finished with either a bull float or hand float. The edges must be finished with an edging tool, then, after the material has reached a desired degree of hardness, it is hand or machine finished with trowels to a smooth surface and given any number of textured surfaces, the most common being a broom finish.
In the act of constructing extended concrete structures, a control or expansion joint must be installed periodically by either scribing or inserting a fiber or metal insert. When concrete is placed between forms, varying degrees of water may be added to allow ease of spreading. This is usually left to the digression of the finishers, sometimes to excess, which they call self-leveling. Too much water in concrete decreases the hardness or pounds per square inch (PSI) hardness rating of the material, it also allows a separation of materials with the rock and reinforcing bar going to the bottom.
When concrete is dispensed through a pump, the water content may be strictly controlled producing a harder and more consistent grade of material, with written verification available, if required. A broad range in size and capabilities of portable concrete pumping services are available in most cities, where the pump is towed behind or part of a separate vehicle, and material is dispensed from a supply truck into the pump hopper and pumped through a hose to the desired location. Reinforcement of the extruded material may be accomplished through the introduction of various fibrous materials, such as polypropylene fiber, called fiber mesh. This material strengthens the structure mainly against the small hairline cracks and spalling caused by freezing, but does not help with the large cracks caused by heaving of the ground in the areas with alluvial soils, or lack of adequate compaction of the underlying soils. Nothing can replace the structural strength of a continuous reinforcing bar added to the building material.
Many types of curb forming machines have been developed, from large slip-form machines used in freeway construction, to the smaller curb forming and extruding machines used in general construction. In most of these machines, the construction material must be manually placed into the hopper, on the device where it is either manually or mechanically transported by pressure into the extrusion cavity. Such devices require an engine or pump onboard the formation machine itself and render it heavy, requiring a power source, and otherwise inconvenient. The weight and the adhesion of the material to the surface along with the pressure pushing the material into the extrusion cavity propels the device in a forward direction, although being difficult to go up or down inclined surfaces, because of the excessive weight of the apparatus. In general, these machines use an attached motor to supply the driving force required, making them very cumbersome even in the lightest models. The act of adding reinforcing bar is made difficult, due to the required location of the auger or plunger pushing the material into the extrusion cavity. Some manufactures claim reinforcing bar is not necessary with the introduction of fiber mesh, which is not correct.
Cleaning concrete equipment and keeping it clean is a major problem in the industry. When concrete is left on any tools or equipment for a period of time it is extremely hard to remove, thus a piece of equipment with many moving internal parts is very hard to keep clean.
Transportation of the material to the extruding equipment from the mixer or truck is another major problem with the conventional curb machines where the hopper must be loaded by hand and the material transported by wheelbarrow. These processes being difficult with small extrusions where minimal amounts of material are required are impossible with larger cross sectional areas, as in side walks and road dividers.
U.S. Pat. No. 4,566,823 by George N. May describes a manually operable curb extrusion device for extruding curb, barrier, or the like from concrete, cement, or some other moldable building material. The building material is manually placed in a receiving hopper and falls into a compacting chamber where a power driven reciprocating compacting member compacts the material into the extrusion mold where it is shaped before extrusion. There is no means to insert reinforcing bar into the cavity because the inventor states that with the use of fiber mesh it is not required; although, on some Municipal and Federal contracts reinforcing bar is required. This device would not be capable of any large cross sectional concrete extrusions.
U.S. Pat. No. 5,527,129 by Paul G. McKinnon discloses a manually operable and steerable curb extrusion device for extruding curb, barrier, wall, gutter, or the like from concrete, cement, or some other moldable building material. The curb extrusion device has a hopper into which building materials are placed to fall into a reciprocating orbital compaction member which compacts, kneads, and forces the building materials through an open-ended extrusion mold where it is shaped before extrusion. This is another motorized concrete compressing device supplied with a hand fed hopper. Here again not capable of large cross sectional concrete extrusions and labor intensive.
U.S. Pat. No. 5,354,189 by Paul M. McKinnon additionally discloses a manually operable and steerable curb extrusion device for extruding curb, barrier, wall, gutter, or the like from concrete, cement, or some other moldable building material. The curb extrusion device has a segmented vibrating hopper into which building materials are placed to fall onto two tapered vibrating augers that compact and force the building material through an extrusion mold where it is shaped before molding. This is another motorized curb extruding device. Though larger with a vibratory action and two steering wheels, it requires a wider operating footprint to be cleared prior to the operation and also relies on the hopper being manually filled.
U.S. Pat. No. 5,018,955 by Robert W. Parrish teaches of an apparatus for shaping and extruding concrete or other moldable material as a decorative curbing. Moldable material is placed in a hopper and flows into an auger which compresses, mixes, and extrudes the material through a shaped, non-flanged mold into the desired curb bed. A fueled engine or electric motor drives a hydraulic pump to pressurize hydraulic fluid. The pressurized fluid drives a hydraulic motor which turns the auger. This device, having greater capacity and a more controlled power source, would require an even wider footprint to be cleared prior to operation and still requires the hopper to be hand fed. U.S. Pat. No. 4,310,293 by Richard C. Eggleton describes a machine for compacting and molding concrete mix or other plastic materials. This machine incorporates a powered ram plate which reciprocally moves from a first position adjacent to the body structure to a second position wholly within the molding member, picking up the material from the base of the hopper. This machine is
Harms Donn K.
Hartmann Gary S.
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