Road structure – process – or apparatus – Apparatus – With surface marking
Reexamination Certificate
2000-01-07
2001-04-24
Bagnell, David (Department: 3673)
Road structure, process, or apparatus
Apparatus
With surface marking
C404S093000
Reexamination Certificate
active
06220783
ABSTRACT:
RELATED APPLICATIONS
(Not applicable)
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
(Not applicable)
FIELD OF THE INVENTION
This invention relates to an apparatus for cutting rumble strips into asphalt or cement pavement.
BACKGROUND OF THE INVENTION
Rumble strips are typically installed in new asphalt pavement by pressing depressions perpendicular to forward direction of travel when it is still hot during installation of the pavement. This is accomplished by a roller with steel bars of suitable size and spacing with adequate weight to form the depressions.
It is often desirable to install rumble strips in asphalt that is already installed, or to increase the width of the rumble strip depressions to increase the magnitude of rumble effect. To this end, machines have been designed and built to mill wider depressions in cold asphalt pavement along the shoulder of roads. These rumble strip milling machines typically use the same type of cutting teeth used on large asphalt milling machines. The teeth are mounted on a cylindrical cutting head, with a diameter the same as the arch of the depressions to be milled. As the milling machine moves forward, the cutting or milling head is rotated at a rapid rate against the forward motion of the milling machine to cut into the pavement. Since the cutting must be periodic and not continuous to form a rumble strip, the cutting head is raised and lowered at regular intervals to leave unmilled areas between the milled depressions. Accordingly, during the forward travel of the milling machine it is necessary to continuously move the cutting head up and down in a regular periodic motion. This up and down motion must be carefully coordinated with the forward speed of the milling machine. This coordinated motion severely limits the forward speed of the milling machine. Typically the forward speed of these rumble strip cutters can be no greater than one or two miles per hour, making the process a relatively slow procedure.
The up and down motion of the cutting head not only limits the speed of the milling machine, but adds significantly to the mechanical complexity and cost of the machine. Accordingly, there is a continuing need in the art to a rumble strip cutting system that not only permits a faster cutting speed but also is a mechanically simpler method than existing systems. A desirable system would be mechanically simpler, and thus more reliable and allow for a faster forward speed of the milling machine.
Objects of the Invention
It is, therefore, an object of the invention to provide a rumble strip milling apparatus that can cut rumble strips while traveling significantly faster that prior-art systems.
Another object of the invention is a rumble strip milling apparatus that is mechanically simpler than existing systems.
Further objects of the invention will become evident in the description below.
BRIEF SUMMARY OF THE INVENTION
The present invention involves a milling machine and method for cutting rumble strips into pavement, such as asphalt and Portland cement. The present invention involves a cutting wheel with alternating rows of cutting teeth. The cutting wheel is mounted with the cutting rows transverse to the direction of travel and it is rotated at a fixed distance above the pavement to move the cutting rows in and out of cutting position as the milling machine moves forward.
As the teeth on the cutting wheel are rotated in and out of cutting position, the forward motion of the machine provides the cutting force as the row of cutting teeth are dragged along the pavement to cut a depression in the pavement. The cutting row is then rotated from cutting into the pavement, leaving an uncut portion as the machine continues its forward motion. In this manner periodic cut and uncut portions are provided, which together form a rumble strip.
The invention is contrary to prior-art practice where the cutting wheel is rotated rapidly to provide the cutting force for the wheel and the wheel is moved up and down as the machine moves forward.
Since the rotating of the cutting wheel enables the milling machine to form the periodic cuts, it is not necessary to move the cutting wheel up and down. Accordingly, the cutting wheel rotates at a fixed distance above the pavement, such that the cutting rows cut into the pavement when they are at the bottom of the cutting wheel, and an uncut portion is left when the non-cutting surface is at the bottom of the cutting wheel.
In order that the forward motion provide the cutting force for the teeth in the cutting rows, the teeth must be dragged across the pavement, i.e., the peripheral speed of the cutting wheel is slower than or opposite the speed of the pavement under a cutting row as it cuts. There are several ways of accomplishing this end. One method, as illustrated in Example I, is to provide a cutting wheel that turns at the same RPM rate and in the same direction as a drive wheel of the machine, but where the cutting wheel has a smaller diameter. In this instance the forward side of the wheel is turning down, like the drive wheel, but because the peripheral speed of the cutting wheel is lower, its cutting rows are dragged along the pavement when in cutting position. Another method, as illustrated in Example II, is to provide cutting wheels that turn opposite the forward motion.
In any case, it is important that the cutting wheels function to present and withdraw a cutting row for cutting. In addition, the arc and spacing of the depression must be correct. Accordingly, the cutting wheel diameter, the number of cutting rows on the cutting wheel, rotation speed and direction, must be chosen to achieve the desired ends. In addition, the peripheral speed of the cutting wheel and the forward motion must be proportionally coordinated in order to provide a strip of regular periodic cut depressions.
Coordinating the forward speed and cutting wheel speed together proportionally is mechanically simpler and more trouble free than coordinating the up and down motion of a cutting wheel and its drive mechanism. Without the requirement of a up and down motion of cutting wheels, it is possible for the apparatus of the present invention to travel much faster than prior-art systems, up to 20 to 30 miles per hour. The order of magnitude increase in speed, and the overall simplicity of the present system, over prior-art systems, allows for a significant savings in capitol and operating costs.
REFERENCES:
patent: 5456547 (1995-10-01), Thomas et al.
patent: 5484228 (1996-01-01), Thomas et al.
patent: 5582490 (1996-12-01), Murray
patent: 5676490 (1997-10-01), Nelson
patent: 5695299 (1997-12-01), Thomas et al.
patent: 5743247 (1998-04-01), Kingsley et al.
patent: 5851086 (1998-12-01), Kurasako
patent: 5957620 (1999-09-01), Thomas et al.
Addie Raymond
Bagnell David
Sonntag James L
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