Abrading – Machine – Rotary tool
Reexamination Certificate
1999-05-27
2001-05-29
Eley, Timothy V. (Department: 3723)
Abrading
Machine
Rotary tool
C451S353000
Reexamination Certificate
active
06238277
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile machine for grinding the surface of a floor, with particular utility of use on concrete floors.
2. Description of the Prior Art
For many years a need has existed for resurfacing concrete floors. That is, concrete floors that have once been surfaced are often ultimately resurfaced. In order to resurface a concrete floor it is often necessary, and certainly desirable, to remove remnants of the old surfacing material. For example, the paint on concrete floor surfaces with time often becomes chipped and the floors themselves become pitted. Before repainting or otherwise applying a new surface to the floor, it is highly advisable to remove the old paint.
Linoleum and other floor surfacing that is secured by adhesive to a floor often becomes cracked and broken with time. Individual tiles or even sections of sheets of floor finishing materials that are secured by adhesives to the floor often become loose over a period of time. In order to resurface the floor, it is necessary to remove the remnants remaining of the old surfacing material, as well as the hardened adhesive that once held the original material to the floor.
A variety of scraping, grinding, and blasting machines have been utilized to refinish floor surfaces. For example, hand-manipulated, electrically powered grinding machines are sometime used for this purpose. Such hand grinding machines typically have abrasive grinding blades or pads about seven inches in diameter. An operator must laboriously move the device across the floor surface from a kneeling position in order to remove old paint or old adhesive material. Due to the small surface area that can be ground or sanded at any particular time, the use of hand-manipulated grinders is extremely time consuming.
Also, the operator must manipulate the device from a stooped position, or more typically while resting on hands and knees. This is an extremely uncomfortable and tiring position in which to work. Furthermore, operation of hand-manipulated machines in this manner requires the operator's face to be positioned close to the surface area of the floor being ground. This subjects the operator to inhalation at close quarters of a large amount of ground floor surfacing particulate matter, grit, and dust. This aggravates the operator's discomfort, and additionally creates a health hazard to the machine operator.
There has been a considerable need for larger machines that have larger grinding pads or blades. Such machines can be constructed in the approximate size and shape of a power lawnmower, and can be manipulated by an operator from a standing position. These larger, wheeled floor grinding machines can cover a much larger floor area within a given time, and are much easier to operate than hand-manipulated grinders. However, the use of a mobile, wheeled floor grinding machine pushed using an operator handle is often impractical due to the considerable danger that high speed rotation of such a large blade or pad presents. For example, the high speed rotation of a thirty inch diameter blade presents a considerable safety hazard. If the blade strikes a hard object the wrong way, it can shatter and send broken portions of the blade flying with dangerous and even deadly effect.
Power consumption for such a machine, the size of the machine itself, and the cost of blades which may be utilized with such a machines are other factors that dictate against the use of a machine constructed with such a large grinding element. Thus, although the need for a large floor grinding machine that can be operated from a standing position has existed for many years, conventional devices of this type have been simply too dangerous or too expensive to gain significant commercial acceptance.
SUMMARY OF THE INVENTION
The present invention is a floor grinding machine that dramatically reduces the problems that have characterized conventional large floor surface refinishing machines. The present invention combines the advantages of a large, wheeled floor resurfacing machine while eliminating the disadvantages historically associated therewith. The floor resurfacing machine of the present invention can be manipulated by an operator from a standing position and can finish a large floor surface, for example thirty inches in diameter, at any given position. However, the present invention does not employ a large, high speed blade having this diameter. To the contrary, the present invention employs a plurality of smaller grinders, comparable in size to the grinding elements utilized in hand-manipulated grinding machines. These grinders are mounted at spatially separated locations on a large, but relatively slowly rotating grinder frame.
The multielement grinding machine of the present invention uses the commercially available styles of five inch, seven, inch or ten inch grinding blades and pads that are currently utilized separately on hand-manipulated grinders. Several of these relatively small, commercially available grinding blades are operated at a high speed on a plate or grinder mounting frame which is also rotated but at a much lower speed.
The invention is particular advantageous since it operates both the relatively small grinder elements and the relatively large grinder mounting frame from a single power source and through a single main driving shaft.
The grinder mounting frame employed in the invention is preferably configured as a combined gearbox that includes elements that operate from a main drive shaft to concurrently increase the speed of the shafts of the grinding elements and at the same time reduce the speed of rotation of the grinder mounting frame or gearbox. For example, each of a plurality of grinding elements may be operated at an angular speed of rotation of eighty-five hundred revolutions per minute, while the plate or grinder mounting frame upon which these grinding elements are mounted rotates at a speed of only about fifty revolutions per minute.
The advantage of such a grinding device is that it may be manipulated with the ease and safety of a typical, hand-held, seven inch grinder. However, because the system employs a plurality of grinding blades and since the grinding units carrying these blades are all mounted on a common, relatively slowly rotating grinder mounting frame, the machine resurfaces over swaths much larger in area than is possible utilizing hand-held grinders. As a consequence, the machine can be operated to achieve a much higher rate of productivity.
Preferably also the bearing housing that carries all of the rotating components is supported on a wheeled chassis by gimbals. As a consequence, the entire operating assembly accommodates uneven areas in the floor surface so that the faces of the grinding units remain in full face-to-face contact with the floor and grind the surface clean of any slight imperfections. Because the grinder mounting frame in effect floats relative to the chassis of the machine, the edges of the grinding elements remain in full surface contact with the floor and are not lifted off of the floor or oriented so as to dig into the floor as the wheels of the device travel across uneven areas of the floor.
In one broad aspect the present invention may be considered to be a multidisc floor grinding apparatus comprising: a chassis supported by wheels to roll across a floor; a bearing housing supported by gimbals on the chassis; a main drive shaft rotatably mounted in the bearing housing to project downwardly therefrom; an annular grinder mounting frame extending radially about the main drive shaft and mounted coaxially therewith for rotation relative thereto; a grinding mounting frame drive mechanism by which the main drive shaft rotates the grinder mounting frame thereabout at a reduced speed relative thereto; a plurality of grinders supported by the grinder mounting frame for rotation relative thereto at respective axes parallel to and radially displaced at a common grinder axis displacement distance from the main drive shaft; a grinder
Duncan C. Warren
Glynn William D.
Eley Timothy V.
Nguyen Dung Van
Thomas Charles H.
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