Road structure – process – or apparatus – Apparatus – Automatic control
Reexamination Certificate
1998-03-31
2001-02-06
Lisehora, James A. (Department: 3673)
Road structure, process, or apparatus
Apparatus
Automatic control
C404S084500, C404S102000, C404S120000
Reexamination Certificate
active
06183160
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to methods and machines for screeding, that is, spreading, distributing, grading and smoothing and/or leveling placed and/or poured, uncured concrete or like loose, spreadable material such as sand, gravel or relatively viscous, fluid materials. More particularly, the invention concerns an apparatus and method for screeding such materials without the need for pre-positioned rails or guides, especially rail guided paving and screeding machines such as slip form pavers. The invention is an improvement of an earlier apparatus and method for screeding such materials with a device which is supported above and moved along an area of such loose or plastic material like uncured concrete.
The present invention is an improved version of the screeding apparatus and methods of U.S. Pat. Nos. 4,930,935 and 4,655,633, both of which are assigned to the assignees of the present invention. In the device and method of U.S. Pat. No. 4,930,935, a self-propelled apparatus includes a steerable, self-propelled frame, a cantilevered boom, and an auger-type, vibratory screed having a strike-off member for engaging the concrete prior to engagement by the auger while the vibratory screed smooths the concrete after engagement by the auger. The elevation of the screed is adjusted automatically by a screed control assembly relative to a laser beacon reference plane positioned off of and remote from the apparatus such that the finished height of the concrete or other material is accurately controlled within close tolerances.
During use of the vibratory screed of U.S. Pat. No. 4,930,935, it was found that with certain types of materials, and especially stiffer or partially set concrete, or large aggregate concrete, the screed assembly of U.S. Pat. No. 4,930,935 encountered difficulties in closing all voids and openings in the concrete and producing the same high quality finished surface while operating at a normal screeding speed. Specifically, with concrete which had partially setup or was held in a concrete delivery truck for too long a time, or was placed in a thinner layer such as low slump two or three inch thick layers, or included large size stone or aggregate in the mixture, the screeding apparatus of U.S. Pat. No. 4,930,935 was required to labor more and be moved over the surface of the poured concrete more slowly in order to produce the same quality finished surface. Particularly when aggregate of large size was used in such concrete, unless the screed assembly was operated at a slower rate of movement, voids in the surface of the concrete were not fully closed. Accordingly, in such situations, the square footage area of concrete which could be finished and screeded in a given work period was reduced because of such slower operating speed. Completion of projects was, thus, delayed while the expense of concrete finishing was increased.
Accordingly, the present invention was devised to improve the screeding and/or finishing of material such as poured, uncured concrete and especially stiffer concrete which is low slump, large aggregate, or partially set, by including an additional oscillating/reciprocating element to better consolidate the concrete being worked at normal screeding speeds while eliminating voids and openings, and thereby provide a smooth high quality, properly finished surface.
SUMMARY OF THE INVENTION
The present invention is an improved screeding apparatus and method for spreading, distributing, smoothing, leveling and/or grading placed and/or poured, uncured concrete or like loose, spreadable, viscous fluid or plastic materials on the ground or on suspended decks, parking structures or other surfaces to allow finishing of the concrete or other material at normal screeding speeds and without the use of large, slip formed pavers or other apparatus requiring the use of preset guides or rails. More particularly, the present invention is adapted to allow screeding at normal speeds even when finishing stiffer concrete such as low slump, large aggregate, or partially set concrete which otherwise would incorporate significant voids or openings.
In one aspect, the invention is a screeding assembly for uncured concrete or other material adapted to be supported and moved along a path in a predetermined direction over an area of the material to be screeded. The assembly includes a support, an elongated, rotatable auger having an axis of rotation generally transverse to the predetermined direction and mounted on the support to move the material laterally of the predetermined direction and grade the material, and a vibratory screed mounted on the support and positioned behind the auger with respect to the predetermined direction to smooth the material. An elongated engaging member is mounted on the support and positioned intermediate the auger and the vibratory screed to engage and smooth the material. An oscillating assembly reciprocates the engaging member in a direction generally parallel to the axis of rotation of the auger whereby the material is spread across the path, graded and smoothed at a desired height above the ground or support surface by the assembly when the assembly is moved in the predetermined direction along the path.
Preferably, the screeding assembly also includes an elongated plow/striker mounted on the support and spaced in front of the auger with respect to the predetermined direction to remove excess material and spread the material as the screeding assembly is moved.
Preferably, the screeding assembly also includes an adjustment assembly for raising and lowering the elongated engaging member with respect to the material to be screeded. The oscillating assembly preferably includes at least one slide member on the engaging member, a bearing member on the support for slidingly supporting the slide member, a camming member attached to the engaging member, and a motor for moving the camming member to reciprocate the slide member and engaging member on the bearing member. In a preferred form, the adjustment mechanism includes a slide support mounted on the support, the oscillating assembly being mounted on the slide support, and a manually-operable adjustment member, such as a threaded rod, operable to slidably move the slide support and oscillating assembly with respect to the support toward an away from the material. Preferably, vibration isolation members, such as rubber or other resilient mounts, are provided for isolating any vibration of the engaging member and oscillating assembly from the remainder of the screeding apparatus.
In other aspects of the invention, an improved screeding apparatus for loose or plastic material, such as placed and/or poured, uncured concrete previously placed on the ground or another support surface includes a support for supporting the apparatus on the ground or a support surface, a boom extending outwardly from the support, a boom support which mounts the boom on the support, a screed assembly, and a screed mount for mounting the screed assembly on the boom. The screed assembly is elongated and includes an elongated, rotatable auger having an axis of rotation generally transverse to the predetermined direction and mounted on the screed mount to move the material laterally of the predetermined direction of the auger axis and grade the material. A vibratory screed is also mounted on the screed mount and is positioned behind the auger with respect to the predetermined direction to smooth the material. An elongated engaging member is mounted on the screed mount and positioned intermediate the auger and the vibratory screed to engage and smooth the material. An oscillating assembly reciprocates the engaging member in a direction generally parallel to the axis of rotation of the auger whereby the material is spread across the path, graded, and smoothed at a desired height above the ground or other support surface when the assembly is moved in the predetermined direction along the path.
In a preferred form, the screeding apparatus may include an elongated plow/striker mounted on the screed mount
Tapio John A.
Tapio Kyle J.
Tapio Nels D.
Delaware Capital Formation Inc.
Lisehora James A.
Van Dyke Gardner, Linn & Burkhart, LLP
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