Multidisc floor grinder

Information

  • Patent Grant
  • 6238277
  • Patent Number
    6,238,277
  • Date Filed
    Thursday, May 27, 1999
    25 years ago
  • Date Issued
    Tuesday, May 29, 2001
    23 years ago
Abstract
A multidisc floor grinder is constructed as a wheeled device that may be moved about the floor by means of a handle. The chassis of the floor grinder supports a bearing housing on gimbals that allow the bearing housing to vary in orientation as the device is moved across an uneven floor. The gimbals are aligned to allow rotation of the bearing housing about a bearing housing axis that is parallel to the floor. The bearing housing supports a main drive shaft which extends downwardly from the bearing housing. The main drive shaft is rotatable relative to the bearing housing within its bearings. A grinder mounting frame is rotatably mounted about the main drive shaft and is supported therefrom. The grinder mounting frame is driven in rotation about the main drive shaft at a greatly reduced speed relative to the rotation of the main drive shaft. The grinder mounting frame carries a plurality of grinding elements which are also driven from the main drive shaft, but at a substantially increased speed of rotation relative thereto. The grinding elements thereby rotate not only about their own axes, but also about the axis of the main drive shaft so as to cover a relatively large floor area with relatively small grinding elements. This arrangement substantially reduces the time required to grind paint or other matter from a floor surface.
Description




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 drive mechanism coupled to rotate the grinders about their respective axes at a greater angular speed than the grinder mounting frame rotates about the main drive shaft; and a power source mounted on the chassis and coupled to drive the grinder mounting frame and the plurality of grinders by rotating the main drive shaft.




The system is constructed so that the entire operating mechanism is suspended relative to the chassis by the gimbals that support the bearing housing. The bearing housing then supports the main drive shaft which remains in a substantially vertical orientation, although it can change slightly in its orientation to accommodate uneven floor surfaces. Bearings interposed between the main drive shaft and the grinder mounting frame permit relative rotation between the grinder mounting frame and the main drive shaft.




The grinder mounting frame drive mechanism may include a transfer shaft mounted in the grinder mounting frame and aligned along a transfer shaft axis that is parallel to and radially displaced from the main drive shaft axis. The transfer shaft is mounted in bearings on the grinder mounting frame so that it can rotate relative thereto. In the preferred embodiment the transfer shaft carries a grinder mounting frame pinion sprocket, while a much larger, base sprocket is secured to the bearing housing. The grinder mounting frame pinion sprocket is rotatably mounted to the grinder mounting frame, since it is clamped or otherwise firmly secured to the transfer shaft. The grinder mounting frame pinion sprocket has a much smaller pitch diameter than the base sprocket. An endless drive chain is engaged with both the base sprocket and the grinder mounting frame pinion sprocket.




The grinder mounting frame drive mechanism also includes an orbital power transfer mechanism coupled to the main drive shaft and to the transfer shaft to transfer power from the main drive shaft to the grinder mounting frame pinion sprocket. The orbital power transfer mechanism preferably includes an intermediate shaft secured to the grinder mounting frame for rotation relative thereto. The transfer shaft, the intermediate shaft, and the main drive shaft have gears mounted thereon which are in meshed engagement. These speed reducing gears drive the grinder mounting frame in rotation at just a small fraction of the speed of rotation of the main drive shaft.




The first gear on the main drive shaft is in meshed engagement with a second and larger gear on the intermediate shaft and rotates the intermediate shaft at a reduced speed relative to the main drive shaft, since the pitch diameter of the first gear is less than that of the second. A third small transfer gear on the intermediate shaft is engaged with a much larger transfer gear on the transfer shaft. Power transferred from the main drive shaft through the transfer gears causes the transfer shaft to rotate at considerably reduced angular velocity relative to the speed of rotation of the main drive shaft. The rotation of the transfer shaft causes the grinder mounting frame pinion sprocket to rotate as well.




An endless chain is engaged with the teeth on the periphery of the base sprocket, which is coaxially mounted relative to the main drive shaft, but is firmly secured relative to the bearing housing. The chain is also engaged with the teeth of the grinder mounting frame pinion sprocket, which is located at a spaced radial distance from the main drive shaft. The rotation of the grinder mounting frame pinion sprocket causes the pinion sprocket to advance along the links of the chain that is also engaged with the fixed base sprocket. The rotation and advancement of the grinder mounting frame pinion sprocket exerts a force on the transfer axle that carries the transfer axle in a orbital path about the main drive shaft axis.




Since the transfer shaft is mounted in bearings in the grinder mounting frame, the force rotating the pinion sprocket is transmitted to the grinder mounting frame to rotate the grinder mounting frame about the main drive shaft axis, but at a greatly reduced speed compared to the speed of rotation of the main drive shaft. The power transfer elements of the grinder mounting frame drive mechanism preferably effectuate a speed reduction of at least twenty-five to one, and preferably about forty to one, from the main drive shaft to the grinder mounting frame. Therefore, if the main drive shaft rotates at a speed of about two thousand rpm, the grinder mounting frame will rotate at a speed of about fifty rpm.




All of the several grinders that are mounted in the grinding mounting frame are also powered from the main drive shaft. The grinder drive mechanism preferably includes a primary grinder power transfer gear coupled to the main drive shaft and rotatable therewith. Separate grinder power take-off gears are coupled to each of the plurality of grinders for driving the grinders separably in rotation about their own axes. All of the grinder power take-off gears are meshed with the primary grinder power transfer gear. To achieve the required speed increase, the primary grinder power transfer gear preferably has a pitch diameter considerably greater than the pitch diameters of the grinder power take-off gears. The pitch diameter of the primary grinder power transfer gear is preferably at least about twice the pitch diameter of the grinder power take-off gears. If the ratio of the pitch diameter of the primary grinder power transfer gear to the pitch diameters of each of the power take-off gears is about four to one and the main drive shaft rotates at a speed of about two thousand rpm, each of the grinders will be rotated at a speed of about eight thousand rpm.




Since the bearing housing is gimbaled relative to the chassis the power source is preferably coupled to the main drive shaft with a flexible coupling so that the power source can be firmly secured to the chassis. For example, a drive pulley may be coupled to the main drive shaft and driven through an endless belt by the power source, which may be an electrical or gasoline driven motor. Due to the gimbaled mounting of the bearing housing, the driven pulley on the main drive shaft will vary in orientation slightly from a horizontal alignment as the floor grinding apparatus travels across uneven locations on the floor. However, the departure of the pulley on the main drive shaft from horizontal alignment is relatively slight, and can be accommodated by flexure of the driving belt.




In another broad aspect, the invention may be considered to be a multidisc floor grinding machine comprising: a chassis supported upon a plurality of wheels for movement across a floor; a bearing housing supported by the chassis upon a bearing housing support axis oriented parallel to the floor; a main drive shaft mounted on the bearing housing for rotation relative thereto about a main drive shaft axis; a grinder mounting frame located beneath and oriented parallel to the bearing support axis and oriented perpendicular to the drive shaft axis for rotation relative thereto about a grinder mounting frame axis oriented perpendicular to and intersecting the bearing housing support axis; a grinder mounting frame drive mechanism that couples the main drive shaft to drive the grinder mounting frame in rotation at a reduced angular velocity relative to that of the main drive shaft; a plurality of grinders each having a grinding element and a grinder axis oriented parallel to the grinder mounting frame axis, wherein the grinders are all mounted for rotation on the grinder frame in spaced separation from each other and from the grinder mounting frame axis; a grinder drive mechanism coupling the main drive shaft to the plurality of grinders to drive the grinder elements at an increased angular velocity relative to that of the grinder mounting frame; and a power source coupled to drive the main drive shaft in rotation.




In still another broad aspect the invention may be described as a multidisc floor grinder comprising: a chassis; wheels supporting the chassis to carry it across a floor surface; a bearing housing mounted by gimbals on the chassis for movement relative thereto about a bearing housing axis that is parallel to the floor; a main drive shaft supported by bearings in the bearing housing to depend from the bearing housing and rotatable thereto about a main drive shaft axis that is perpendicular to and intersects the bearing housing axis; a grinder mounting frame supported by the main drive shaft and extending radially therefrom for rotation about the main drive shaft axis relative to the main drive shaft; a grinder mounting frame drive mechanism coupled between the main drive shaft and the grinder mounting frame to drive the grinder mounting frame in rotation relative to the chassis at a speed reduced from that of the main drive shaft; a plurality of grinders mounted on the grinder mounting frame for rotation relative thereto about grinder axes that are parallel to and radially displaced from the main drive shaft axis, and wherein each of the grinders is equipped with a grinder element depending therefrom which has a radius smaller than the distance of displacement of the grinder axes from the main drive shaft axis; a grinder drive mechanism coupled between the main drive shaft and the grinders to rotate the grinder elements about their respective grinder axes at a speed greater than that of the main drive shaft; a power source mounted on the chassis; and a main drive mechanism coupled between the power source and the main drive shaft to rotate the main drive shaft about the main drive shaft axis while permitting movement of the bearing housing in the gimbals.











The invention may be described with greater clarity and particularity with respect to the accompanying drawings.




DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a multidisc floor grinder machine according to the invention.





FIG. 2

is a sectional elevational view of the operating components of the multidisc floor grinding machine of

FIG. 1

taken along the lines


2





2


of FIG.


5


.





FIG. 3

is a perspective detail illustrating the power source, the bearing housing, and the grinder mounting frame of the multidisc floor grinder of FIG.


1


.





FIG. 4

is a bottom plan view taken along the lines


4





4


of FIG.


2


.





FIG. 5

is a diagrammatic bottom plan view illustrating the operating components of the grinder mounting frame drive mechanism and the grinder drive mechanism.





FIG. 6

is a sectional elevational view taken along the lines


6





6


of FIG.


5


.











DESCRIPTION OF THE EMBODIMENT





FIG. 1

shows in perspective a multidisc floor grinding machine


10


constructed according to the invention. The grinding machine


10


is comprised of a chassis, indicated generally at


12


, supported upon a pair of wheels


14


that are coaxially aligned with each other on the opposite sides of the chassis


12


. The grinding machine


10


also includes a handle


16


that is secured to the chassis


12


and which includes operating control levers and switches indicated generally at


18


. The floor grinding machine


10


has a conventional gasoline-driven engine


20


with an air filter


22


thereatop. The engine


20


drives a motor


24


, which serves as the power source for the operating components of the floor grinder. These components are largely concealed from view by an upper aluminum cover


26


and a lower aluminum cover


27


which are provided for cosmetic purposes. A confining dust collection shroud or skirt


29


extends down from the lower cover


27


to the floor to confine and collect dust, dirt grit, and other debris. Suction ducts


31


lead from the dust collection skirt


29


to a conventional vacuum source (not visible).




The operating components of the floor grinder


10


are best depicted in

FIGS. 2 and 6

. The chassis


12


of the machine


10


includes, on both of its opposite sides, forward of the wheels


14


and remote from the handle


16


, a pair of upright gimbal mounting posts


28


and


30


, indicated in phantom in

FIGS. 2 and 6

. The gimbal mounting posts


28


and


30


are rigidly secured to the remaining structure of the chassis


12


and support a pair of stub axles


32


and


34


that are threadably engaged in internally tapped, coaxially aligned bores in the side walls


36


and


38


of a generally box-shaped bearing housing


40


, illustrated in perspective in FIG.


3


. The bearing housing


40


is formed with a transverse front wall


42


that is rigidly secured to the upright fore and aft side walls


36


and


38


. A rectangular-shaped top plate


44


(partially broken away in

FIG. 3

) and a corresponding bottom plate


46


are also rigidly secured transversely across the front end wall


42


and the fore and aft side walls


36


and


38


. The box-shaped bearing housing


40


is open at the rear so as to permit the passage of an endless, flexible vee-belt


134


that is coupled to the power source, namely the motor pulley


132


of the motor


24


.




The stub axles


32


and


34


extend outwardly into coaxially aligned openings in the gimbal mounting posts


28


and


30


. The bearing housing


40


can thereby rotate freely about the generally horizontal, transverse bearing housing support axis


48


along which the stub axles


32


and


34


are aligned. The inner ends of the stub axles


32


and


34


are externally threaded and are threadably engaged in internally tapped, coaxially aligned bores in the bearing housing side walls


36


and


38


, respectively. Nuts


49


are welded or otherwise rigidly secured to both the stub axles


32


and


34


so as to allow the stub axles


32


and


34


to be firmly attached to the fore and aft side walls


36


and


38


of the bearing housing


40


. The stub axles


32


and


34


thereby support the bearing housing


40


on the chassis


12


by the gimbaled connections in the gimbal mounting posts


28


and


30


. The gimbaled connections allow the bearing housing


40


to rock in a fore and aft direction of rotatable movement about the bearing housing support axis


48


, which is parallel to the floor.




A cylindrical main drive shaft


50


is provided and is mounted for rotation by means of bearings


52


in the top plate


44


and the bottom plate


46


of the bearing housing


40


. The main drive shaft


50


rotates about its own longitudinal axis


71


, which is perpendicular to and intersects the bearing housing support axis


48


. The main drive shaft


50


preferably has an outer diameter of about 3.85 inches and is externally threaded at both of its opposite ends. Thrust bearing nuts


54


are threadably engaged and secured to both the upper and lower threaded ends of the main drive shaft


50


. Thrust bearings


56


are interposed between the thrust bearing nuts


54


and the annular bearings


52


within which the main drive shaft


50


turns. Retaining plates


58


are secured by bolts to both the top plate


44


and to the bottom plate


46


of the bearing housing


40


and reside in abutment against the bearing rings


52


to prevent longitudinal movement of the main drive shaft


50


relative to the bearing housing


40


, yet permit high speed rotation of the main drive shaft


50


relative to the bearing housing


40


. The retaining plates


58


each have a square outer perimeter with a central circular opening therewithin. The retaining plates


58


are fastened by bolts at their corners spaced 5.6 inches apart from each other. The retaining plates


58


have snap rings


55


that engage and longitudinally immobilize the annular bearings


52


. The snap rings


55


have a circumferential span of about 355°.




The main drive shaft


50


is rotatably mounted in the bearing housing


40


and projects upwardly and downwardly therefrom through central, coaxially aligned openings in the bearing housing top plate


44


and bottom plate


46


, as illustrated in

FIGS. 2 and 6

. Near the upper end of the main drive shaft


50


, but within the bearing housing


40


, a main drive shaft vee-belt pulley


60


is secured by means an allen head set screw


62


that acts radially through a depending collar on the underside of the belt pulley


60


.




Beneath the bearing housing


40


the main drive shaft


50


is provided with a large primary grinder power spur gear


64


having an upwardly extending attachment collar through which another allen head set screw


66


is fastened. The allen head set screw


66


locks the primary grinder power gear


64


to the outer surface of the main drive shaft


50


for rotation therewith. The gear


64


preferably has a pitch diameter of about twelve inches.




Beneath the primary grinder power gear


64


the main drive shaft


50


is provided with a first orbital power transfer gear


68


that has an upwardly projecting fastening collar through which another allen head set screw


69


is engaged. The set screw


69


clamps the first orbital power transfer gear


68


to the outer surface of the main drive shaft


50


. The first orbital power transfer gear


68


preferably has a pitch diameter of six inches.




The multidisc floor grinding machine


10


also includes an annular grinder mounting frame


70


that extends radially about the main drive shaft


50


and is mounted coaxially therewith for rotation about the main drive shaft axis


71


. The grinder mounting frame


70


is a generally disc-shaped structure with central, axial openings defined therethrough. The grinder mounting frame


70


is formed with a laterally expansive, annular upper mounting plate


72


and a corresponding lower annular mounting plate


74


. The upper and lower mounting plates


72


and


74


are secured together about their perimeters by a cylindrical grinder mounting frame housing wall


76


that is rigidly secured to the upper and lower plates


72


and


74


by some conventional fastening means such as bolts


81


, visible in FIG.


4


.




At the central, axial openings in the upper grinder mounting plate


72


and the lower grinding mounting plate


74


a pair of bearing rings


76


are provided. The bearing rings


76


are interposed between the main drive shaft


50


and the structure of the grinder mounting frame


70


. Retaining plates


77


are bolted to both the upper grinder mounting frame plate


72


and the lower grinder mounting frame plate


74


as illustrated in

FIGS. 2

,


4


, and


6


to prevent longitudinal movement, but permit rotational movement between the grinder mounting frame


70


and the main drive shaft


50


. The retaining plates


77


are the same size as the retaining plates


58


and are bolted to the grinder mounting frame


70


with the same bolt spacing as the retaining plates


58


. The retaining plates


77


also have annular snap rings


55


that engage and longitudinally immobilize the annular bearings


76


.




A plurality of grinders


78


,


80


, and


82


are provided in the multidisc floor grinding machine


10


and are arranged at equally spaced intervals about the main drive shaft axis


71


. The grinders


78


,


80


, and


82


are supported by the grinder mounting frame


70


for rotation relative thereto. While any plural number of grinders may be employed, in the preferred embodiment there are three grinders


78


,


80


, and


82


spaced at one hundred twenty degree intervals over the expanse of the grinder mounting frame


70


.




Each of the grinders


78


,


80


, and


82


includes a grinder shaft


84


one and one-half inches in diameter that is oriented parallel to and radially displaced from the main drive shaft


50


. The grinder shafts


84


of each of the grinders


78


,


80


, and


82


rotate about their respective grinder shaft axes


86


,


88


, and


90


. The grinder shaft axes


86


,


88


, and


90


are parallel to the main drive shaft axis


71


and are located at a common grinder axis displacement distance therefrom. In the embodiment illustrated the grinder axes


86


,


88


, and


90


are located at a distance of 7.750 inches from the main drive shaft axis


71


.




Each of the grinder shafts


84


is supported for rotation within bearing rings


92


located at openings in both the top grinder mounting frame plate


72


and the bottom grinder mounting frame plate


74


. The bearing rings


92


are also held in place by annular retaining plates


94


that are bolted to both the top grinder mounting frame plate


72


and the bottom grinder mounting frame plate


74


by bolts spaced 2.75 inches apart, as best illustrated in FIG.


4


.




Each grinder shaft


84


has a separate grinder power take-off gear


96


. The grinder power take-off gears


96


are spur gears having pitch diameters of five inches. The grinder power take-off gears


96


reside in coplanar relationship and in meshed engagement with the primary grinder power gear


64


that is rigidly secured to the main drive shaft


50


.




At the lower extremity of each of the grinders


78


,


80


, and


82


, a grinding element


98


is mounted. The grinding element


98


may be a conventional five inch diameter, seven inch diameter, or ten inch diameter blade of the type which is utilized on commercially available, hand manipulated grinding machines. Alternatively, the grinding elements


98


may be grit covered discs which are commercially available in the same five inch, seven inch, and ten inch diameters. In either case, either a blade or a grit covered disc is fastened as a grinding element to the lower extremity of the grinder shaft


84


of each of the grinders


78


,


80


, and


82


.




A large base sprocket


100


having a pitch diameter of fifteen inches is rigidly secured to the bottom plate


46


at the underside of the bearing housing


40


by bolts, welding, or other conventional means. The base sprocket


100


is a large, annular sprocket that has a central opening therethrough that accommodates the bearing ring


52


within which the main drive shaft


50


is journaled.




The grinder mounting frame


70


carries a transfer shaft


102


that is oriented parallel to and radially displaced from the drive shaft


50


. Preferably, the transfer shaft axis


104


of the transfer shaft


102


is radially displaced from the main drive shaft axis


71


a distance of about 9.5 inches. The transfer shaft


102


is journaled for rotation relative to the grinder mounting frame


70


in bearing rings


106


and is best illustrated in FIG.


6


. The bearing rings


106


are held in position and the transfer shaft


102


is captured by means of annular bearing retaining plates


108


. The bearing plates


108


are bolted at their corners to the upper grinder mounting frame plate


72


and the lower grinder mounting frame plate


74


by bolts spaced 2.75 inches from each other.




The upper end of the transfer axle


102


protrudes above the grinder mounting frame


70


a sufficient distance for a mounting frame pinion sprocket


112


to be attached thereto. The pitch diameter of the mounting frame pinion sprocket


112


is preferably one and one-half inches. The grinder mounting frame pinion sprocket


112


has a depending collar that is clamped onto the upper end of the transfer shaft axle


102


by means of an allen head set screw


110


in a conventional manner. An endless drive chain


114


is looped about and engaged with the teeth of both the base sprocket


100


and the teeth of the grinder mounting frame pinion sprocket


112


.




Below the grinder mounting frame pinion sprocket


112


and within the confines of the grinder mounting frame


70


, the transfer shaft


102


carries a spur gear


116


that is preferably 8.5 inches in diameter. The spur gear


116


is secured to rotate with the transfer shaft


102


by means of an allen head set screw


117


that clamps a collar depending from the underside of the gear


116


to the transfer shaft


102


in a conventional manner.




The grinder mounting frame drive mechanism also includes an intermediate speed reduction shaft


118


that is carried by means of bearings


120


in the grinder mounting frame


70


. The intermediate speed reduction shaft


118


is captured within the grinder mounting frame


70


by means of annular retaining plates


122


that are bolted to the top and bottom plates


72


and


74


of the grinding mounting frame


70


, as illustrated in

FIGS. 2 and 4

. The axis


119


of the intermediate speed reduction shaft


118


is parallel to and radially displaced from the main drive shaft axis


71


, preferably at a distance of seven inches therefrom. The intermediate speed reduction shaft


118


has a small 2.5 inch pitch diameter upper spur gear


126


and a larger, eight and a half inch diameter lower spur gear


128


. Both of the intermediate gears


126


and


128


have collars which are respectively secured to the intermediate speed reduction shaft


118


by means of allen head set screws


127


and


129


in a conventional manner. The intermediate speed reduction shaft


118


and its gears


126


and


128


are visible in FIG.


2


. The gear


128


on the intermediate shaft


118


lies in coplanar relationship with and is engaged with the gear


68


that is secured to the main drive shaft


50


.




The main drive shaft


50


rotates at a speed of twenty-five hundred revolutions per minute. The first orbital power transfer gear


68


is in meshed engagement with the intermediate gear


128


, thereby reducing the speed of the intermediate speed reduction shaft


118


relative to the speed of rotation of the main drive shaft


50


. The meshed engagement of the small gear


126


on the intermediate shaft


118


with the much larger gear


116


on the transfer shaft


102


reduces the speed of the transfer shaft


102


relative to the main drive shaft


50


still further down to about five hundred fifty rpm. The engagement of the small sprocket


112


on the transfer shaft


102


with the much larger fixed base gear


100


by means of the chain


114


effectuates a further ten to one speed reduction, so that the transfer shaft


118


is pulled in orbital motion about the axis


71


of the main drive shaft


50


at a speed of only about fifty rpm. The grinder mounting frame pinion sprocket


112


also rotates relative to the base sprocket


100


to carry the grinder mounting frame


70


in rotation about the main drive shaft


50


and its axis


71


. Since the transfer shaft


102


is rotatably secured by the bearings


106


and retaining plates


108


to the grinder mounting frame


70


, the advance of the sprocket


112


along the chain


114


causes the entire grinder mounting frame


70


to rotate at a speed of about fifty rpm about the main drive shaft axis


71


. The relatively slow rotation of the grinder mounting frame


70


about the main drive shaft axis


71


carries with it the several grinders


98


, which are rotating at a much higher speed, approximately eighty-five hundred rpm about their respective axes


86


,


88


, and


90


.




The gears


68


,


128


,


126


, and


116


on the main drive shaft


50


, the intermediate shaft


118


, and the transfer shaft


102


are in meshed engagement. In the orbital power transfer drive line the gear


68


secured to the main drive shaft


50


drives the gear


128


thereby rotating the intermediate shaft


118


. The gear


126


on the intermediate shaft


118


drives the gear


116


on the transfer shaft


102


. The rotation of the transfer shaft


102


rotates the sprocket


112


relative to the base sprocket


100


. The advancement of the sprocket


112


along the endless chain


114


carries the grinder mounting frame


70


in rotation about the main drive shaft


50


.




The grinder mounting frame


70


is coaxially mounted on the main drive shaft


50


. The grinder frame bearings


76


are interposed between the main drive shaft


50


and the grinder mounting frame


70


. The grinder mounting frame drive mechanism, which includes the meshed gears


68


,


128


,


126


, and


116


and the sprockets


112


and


100


coupled together by the endless chain


114


serve as speed reducing components. The main drive shaft


50


thereby drives the grinder mounting frame


70


in rotation at a small fraction of its own speed of rotation. The power transfer elements or components of the grinder mounting frame drive mechanism effectuate a speed reduction of at least twenty-five to one, and preferably about forty to one, from the main drive shaft


50


to the grinder mounting frame


70


.




The large, primary grinder power gear


64


that is coupled to the main drive shaft


50


and which is rotatable therewith is in coplanar relationship with all of the separate grinder power take-off gears


96


. The power take-off gears


96


are coupled to their respective grinder shafts


84


for driving the three grinders


78


,


80


, and


82


in rotation. The grinder power take-off gears


96


on the grinder shafts


84


are all meshed with the primary grinder power transfer gear


64


. The primary grinder power transfer gear


64


has a pitch diameter greater than the pitch diameters of the grinder power take-off gears


96


by a factor of at least about two to one, and preferably about four to one.




The meshed engagement of the gears


64


and


96


in the grinder power drive line are illustrated in FIG.


5


. The meshed engagement of the gears


68


,


128


,


126


, and


116


and the engagement of the sprockets


112


and


100


by means of the endless chain


114


are also illustrated in FIG.


5


.




The driving connection from the motor


24


to the main drive shaft


50


is best illustrated in FIG.


3


. As shown in that drawing figure, the motor output shaft


130


drives the motor pulley


132


, which in turn drives an endless vee-belt


134


. The vee-belt


134


in turn drives the pulley


60


that is secured to the main drive shaft


50


within the bearing housing


40


. As the grinders


78


,


80


, and


82


encounter uneven locations on the floor, the bearing housing


40


will swivel about the stub axles


32


and


34


relative to the chassis


12


in a fore and aft direction. This allows the grinders


78


,


80


, and


82


to accommodate uneven surfaces on the floor. The vee-belt


134


is flexible enough to accommodate the relative small deviations of the main drive shaft axis


71


from true vertical alignment while remaining engaged with the pulleys


60


and


132


.




The chassis


12


carries an annular dust collection shroud or skirt


29


that includes suction ducts


31


that are connected to a vacuum source that is also operated by the motor


24


. As the grinders


78


,


80


, and


82


grind away paint or other particulates, the dust collection shroud


13


confines the particulates so that they can be sucked to a dust collection bag in a conventional manner, thereby reducing the health hazard to the machine operator. The use of the dust collection system also reduces the likelihood that airborne particulate matter will get into other equipment in the vicinity, which could otherwise lead to malfunction of that equipment.




It is to be understood that different operating components from those depicted in the preferred embodiment of the invention may be employed in the grinder mounting frame drive mechanism, as well as in the grinder drive mechanism. Also, different speed reduction systems and ratios may be employed in rotating the grinder mounting frame relative to the main drive shaft. Likewise, different speed increasing systems and ratios may be employed in operating the grinders from the main drive shaft. In addition, different flexible coupling mechanisms and different power sources may be employed in rotating the main drive shaft. Accordingly, the scope of the invention should not be construed as limited to the specific embodiment depicted and described, as considerable variations and modifications of that embodiment will be come readily apparent to those skilled in the art.



Claims
  • 1. A multidisc floor grinding apparatus comprising:a chassis supported by wheels to roll across a floor, a bearing housing supported by gimbals on said chassis, a main drive shaft, rotatably mounted in said bearing housing to project downwardly therefrom, an annular grinder mounting frame extending radially about said main drive shaft and mounted coaxially therewith for rotation relative thereto; a grinder mounting frame drive mechanism by which said main drive shaft rotates said grinder mounting frame thereabout at a reduced speed relative thereto, a plurality of grinders supported by said grinder mounting frame for rotation relative thereto at respective axes parallel to and radially displaced at a common grinder axis displacement distance from said main drive shaft, a grinder drive mechanism coupled to rotate said grinders about their respective axes at a greater angular speed than said grinder mounting frame rotates about said main drive shaft, and a power source mounted on said chassis and coupled to drive said grinder mounting frame and said plurality of grinders by rotating said main drive shaft; further characterized in that said grinder mounting frame drive mechanism is comprised of a base sprocket secured to said bearing housing, a grinder mounting frame pinion sprocket rotatably mounted to said grinder mounting frame and having a smaller pitch diameter than said base sprocket, an endless drive chain engaged with both said base sprocket and said grinder mounting frame pinion sprocket, a transfer shaft carrying said grinder mounting frame pinion sprocket and oriented parallel to said main drive shaft and rotatably mounted on said grinder mounting frame, and an orbital power transfer mechanism coupled to said main drive shaft and to said transfer shaft to transfer power from said main drive shaft to said grinder mounting frame pinion sprocket, whereby said grinder mounting frame pinion sprocket rotates relative to said base sprocket and orbits about said main drive shaft to carry said grinder mounting frame in rotation about said main drive shaft.
  • 2. A multidisc floor grinding apparatus according to claim 1 wherein said orbital power transfer mechanism includes an intermediate shaft secured to said grinder mounting frame for rotation relative thereto, and said transfer shaft, said intermediate shaft, and said main drive shaft have gears mounted thereon which are in meshed engagement whereby said main drive shaft drives said grinder mounting frame in rotation at a fraction of its own speed of rotation.
  • 3. A multidisc floor grinding apparatus according to claim 1 wherein said grinder mounting frame drive mechanism includes power transfer elements that effectuate a speed reduction of at least twenty-five to one from said main drive shaft to said grinder mounting frame.
  • 4. A multidisc floor grinding apparatus according to claim 1 wherein said grinder mounting frame drive mechanism includes speed reducing components that rotate said grinder mounting frame with a speed reduction ratio of about forty to one.
  • 5. A multidisc floor grinding apparatus according to claim 1 wherein said grinder drive mechanism includes a primary grinder power gear coupled to said main drive shaft and rotatable therewith, and a separate grinder power take-off gear coupled to each of said plurality of grinders for driving said grinders in rotation, and said grinder power take-off gears are all meshed with said primary grinder power gear, and said primary grinder power gear has a pitch diameter greater than the pitch diameters of said grinder power take-off gears.
  • 6. A multidisc floor grinding apparatus according to claim 5 wherein said pitch diameter of said primary grinder power gear is at least about twice said pitch diameters of said grinder power take-off gears.
  • 7. A multidisc floor grinding apparatus according to claim 6 wherein the ratio of said pitch diameter of said primary grinder power gear to said pitch diameters of each said power take-off gears is about four to one.
  • 8. A multidisc floor grinding apparatus according to claim 1 further comprising a drive pulley coupled to said main drive shaft and an endless belt driving said drive pulley and driven by said power source thereby providing a flexible coupling between said power source and said main drive shaft.
  • 9. A multidisc floor grinding machine comprising:a chassis supported upon a plurality of wheels for movement across a floor, a bearing housing supported by said chassis upon a bearing housing support axis oriented parallel to said floor, a main drive shaft mounted on said bearing housing for rotation relative thereto about a main drive shaft axis, a grinder mounting frame located beneath and oriented parallel to said bearing housing support axis and oriented perpendicular to said main drive shaft axis for rotation relative thereto about a grinder mounting frame axis oriented perpendicular to and intersecting said bearing housing support axis, a grinder mounting frame drive mechanism that couples said main drive shaft to drive said grinder mounting frame in rotation at a reduced angular velocity relative to that of said main drive shaft, a plurality of grinders each having a grinding element and a grinder axis oriented parallel to said grinder mounting frame axis, wherein said grinders are all mounted for rotation on said grinder frame in spaced separation from each other and from said grinder mounting frame axis, a grinder drive mechanism coupling said main drive shaft to said plurality of grinders to drive said grinder elements at an increased angular velocity relative to that of said grinder mounting frame, and a power source coupled to drive said main drive shaft in rotation; further characterized in that said grinder mounting frame is coaxially mounted on said main drive shaft and further comprising grinder frame bearings interposed between said main drive shaft and said grinder mounting frame, and said grinder mounting frame drive mechanism includes grinder mounting frame speed reducing components that effectuate a speed reduction from said main drive shaft to said grinder mounting frame of at least twenty-five to one.
  • 10. A multidisc floor grinding machine according to claim 9 wherein said grinder mounting frame speed reducing components include: a power transfer shaft journaled in said grinder mounting frame for rotation about a transfer shaft axis that is parallel to and radially spaced from said main drive shaft axis, a pinion sprocket coupled to said power transfer shaft, a base sprocket coupled to said bearing housing and coaxial with said main drive shaft axis, an endless chain engaged with both said base sprocket and said pinion sprocket, transfer elements secured to said main drive shaft and to said transfer shaft and engaged with each other, whereby rotation of said main drive shaft advances said power transfer shaft in circular orbital movement about said main drive shaft axis, carrying said grinder mounting frame therewith.
  • 11. A multidisc floor grinding machine according to claim 10 wherein said transfer elements include meshed gears on said main drive shaft and said power transfer shaft.
  • 12. A multidisc floor grinding machine according to claim 11 wherein said transfer elements further include an intermediate shaft having gears thereon that are meshed with said meshed gears on said main drive shaft and said power transfer shaft.
  • 13. A multidisc floor grinding machine according to claim 9 wherein said grinder drive mechanism is comprised of a set of grinder driving gears coupled between said main drive shaft and said plurality of grinders to drive said plurality of grinders at more than twice the angular velocity of said main drive shaft.
  • 14. A multidisc floor grinding machine according to claim 13 wherein said set of grinder driving gears rotates each of said grinders at an angular velocity about four times that of said main drive shaft.
  • 15. A multidisc floor grinding machine according to claim 9 further comprising gimbals that support said bearing housing on said chassis and a flexible coupling between said power source and said main drive shaft to accommodate movement of said bearing housing on said gimbals.
  • 16. A multidisc floor grinding mechanism according to claim 15 wherein said flexible coupling between said power source and said main drive shaft is comprised of a belt drive.
  • 17. A multidisc floor grinder comprising:a chassis, wheels supporting said chassis to carry it across a floor surface, a bearing housing mounted by gimbals on said chassis for movement relative thereto about a bearing housing axis that is parallel to said floor, a main drive shaft supported by bearings in said bearing housing to depend from said bearing housing and rotatable relative thereto about a main drive shaft axis that is perpendicular to and intersects said bearing housing axis, a grinder mounting frame supported by said main drive shaft and extending radially therefrom for rotation about said main drive shaft axis relative to said main drive shaft, a grinder mounting frame drive mechanism coupled between said main drive shaft and said grinder mounting frame to drive said grinder mounting frame is rotation relative to said chassis at a speed reduced from that of said main drive shaft, a plurality of grinders mounted on said grinder mounting frame for rotation relative thereto about grinder axes that are parallel to and radially displaced from said main drive shaft axis, and wherein each of said grinders is equipped with a grinder element depending therefrom which has a radius smaller than the distance of displacement of said grinder axes from said main drive shaft axis, a grinder drive mechanism coupled between said main drive shaft and said grinders to rotate said grinder elements about their respective grinder axes at a speed greater than that of said main drive shaft, a power source mounted on said chassis, and a main drive mechanism coupled between said power source and said main drive shaft to rotate said main drive shaft about said main drive shaft axis while permitting movement of said bearing housing in said gimbals; wherein said grinder mounting frame drive mechanism includes speed reduction components that reduce the speed of rotation of said grinder mounting frame to no less than about one-twenty-fifth that of said main drive shaft and said grinder drive mechanism includes speed increasing components that increase the speed of rotation of said grinders to at least twice that of said main drive shaft.
US Referenced Citations (5)
Number Name Date Kind
3701221 Vinella Oct 1972
4097950 Satterfield Jul 1978
4319434 Brejcha Mar 1982
5548860 Weltikol et al. Aug 1996
5863241 Rottschy Jan 1999