Road structure – process – or apparatus – Apparatus – Material distribution means
Reexamination Certificate
1999-10-08
2001-08-14
Will, Thomas B. (Department: 3673)
Road structure, process, or apparatus
Apparatus
Material distribution means
C404S096000, C404S118000
Reexamination Certificate
active
06273636
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to paving machines, and more particularly to paving screed assemblies for paving machines.
Screed assemblies used with paving machines to level paving material, typically asphalt, applied by the machine onto a generally horizontal base surface, such as a road bed, are well known. A screed assembly often includes both a main screed and one or more screed extensions connected with the main screed. The screed extension may either be fixedly attached (e.g., bolted) to a lateral end of the main screed (or an outer end of another screed extension) or movably attached to the main screed.
In general, a typical screed assembly levels the paving material into a mat having the general form of an elongated strip. When it is desired to pave a mat of material having a width that exceeds the maximum width of the screed assembly, the paving machine must typically pave two or more parallel mat strips to achieve the desired overall mat width. Each of these mat strips has a longitudinally-extending side edge that must either abut or overlap the proximal edge of the adjacent mat strip so that a continuous surface is formed across the overall width of the mat of material. It is preferred to closely abut the edges of the adjacent mat strips such that, after a subsequent compacting or rolling operation, an integral zone of paving material, referred to as a “joint”, exists at the intersection of the adjacent mat strips.
However, if the subsequently paved or “second” mat strip is not carefully applied, one of two adverse conditions may be created at the intersection of the adjacent mat strips. If the second mat strip overlaps the other or “first” strip by a more than certain distance, an upraised section or bump is created at the joint, which may not be eliminated by a subsequent rolling operation. If the second mat strip is applied such that the proximal edges of the first and second mat strips are spaced apart by more than a minimal distance, a gap is created between the mat strips that cannot be eliminated by a rolling operation. In this situation, a subsequent operation to fill the gap with paving material is necessary, creating a weakened zone in the mat of material. Typically, this weakened zone of a material mat will be the first section of the mat that fails (i.e., cracks or crumbles) after a period of use.
In order to eliminate the occurrence of the adverse mat conditions described above, it is known to form a downward step at the edge of the first mat strip and then to pave the second mat strip such that the proximal edge of the second strip overlaps this stepped edge. The joint formed by this procedure is relatively strong and level. Devices for forming the edges of a mat strip to create stepped edges are known. These devices typically have a frame that attaches to a screed assembly and an edge-forming plate connected to the frame. The forming plate is located vertically lower than the screed plate(s) of the screed assembly and may be also be angled so as to create a downwardly-tapered step. However, these known devices generally have minimal or no capability to adjust the vertical height, taper angle and/or angle of attack of the forming plate with respect to the screed plates of the main screed assembly.
It is therefore desirable to provide a device for an edge-forming device for a screed assembly that has a fully adjustable edge-forming plate. Further, it is also desirable to provide such a device that is capable of being connected with existing screed assemblies without the need for any substantial modifications to the existing screed assemblies.
SUMMARY OF THE INVENTION
In a first aspect, the present invention is an edge-forming device for a screed assembly having lateral ends and a screed plate extending between the lateral ends, the screed plate having a generally horizontal working surface. The edge-forming device comprises a frame connected with one of the lateral ends of the screed assembly. A plate is disposed generally below the frame and has a generally horizontal working surface. The plate extends outwardly beyond the one screed assembly lateral end such that the edge-forming plate working surface and the screed plate working surface are spaced horizontally and laterally from each other. An adjustment mechanism is connected with the frame and with the edge-forming plate. The adjustment mechanism is configured to displace the plate with respect to the frame to adjust a vertical position of the edge-forming plate with respect to the screed plate. The edge-forming plate working surface is positionable vertically lower than the screed plate working surface so as to form a vertical step in a mat of material paved by the screed assembly proximal to a lateral edge of the mat.
In another aspect, the present invention is an edge-forming device for use with a screed assembly. The edge-forming device comprises a frame connectable with the screed assembly and a plate disposed generally below the frame. An adjustment mechanism adjustably connects the plate with the frame and includes a base attached to the frame. The adjustment mechanism also includes first and second connective members. Each connective member has a first end connected with the base and a second end connected with the plate. Each second end is vertically displaceable with respect to the base such that displacement of two second ends in a same vertical direction adjusts a vertical position of the plate with respect to the frame. Further, vertical displacement of one second end with respect to the other second end adjusts an angle between the plate and the frame.
REFERENCES:
patent: 3680451 (1972-08-01), Birtchet
patent: 3936211 (1976-02-01), Miller et al.
patent: 4093410 (1978-06-01), Miller
patent: 4379653 (1983-04-01), Brown
patent: 4818140 (1989-04-01), Carlson
patent: 4900185 (1990-02-01), Foertsch
patent: 5924819 (1999-07-01), Breidenbach
Addie Raymond W
Blaw-Knox Construction Equipment Corporation
Michael & Best & Friedrich LLP
Will Thomas B.
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