Abrading – Frame or mount – Portable abrader
Reexamination Certificate
1999-09-29
2001-07-10
Morgan, Eileen P. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S344000
Reexamination Certificate
active
06257970
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The present invention relates to an improved ergonomically friendly surface-treating tool in which a flat surface of a rotary pad engages the surface of a workpiece for the purpose of abrading or polishing it and more particularly to an improved random orbital sander.
By way of background, in operation, random orbital sanders create forces at the sanding surface which are transmitted back to the operator's hand and arm through a lever which is the height of the random orbital sander between the face of the sanding disc and the top of the casing at the vertical centerline of the sander. Therefore, if this height is as short as possible, the operator's effort in overcoming the forces produced at the face of the sanding disc are less than if the height was greater. In addition, there is a second force which must be overcome by the operator, namely, the force produced by the flexible dust discharge hose which acts through a lever arm having a length between the vertical centerline of the orbital sander and the outer end of the dust discharge fitting which conveys dust from the shroud. When any one of the foregoing two dimensions are lessened, the effort required by the operator in using an orbital sander is accordingly lessened. Also, it has been observed that lower heights of the compressed air inlet connection and the dust discharge tube outlet above a sanding surface result in less effort to operate the sander. When all of the foregoing distances are lessened, the effort involved in using the orbital sander is all the more lessened.
Furthermore, in the past the outer end of the dust discharge tube always accepted a flexible dust carrying hose at a horizontal attitude. This had the disadvantage that the horizontal dust carrying hose could droop downwardly and contact external bodies relatively close to the sander with the attendant creation of frictional drag which the operator had to overcome. In addition, when the outer end of the dust discharge tube was relatively far from the vertical centerline of the sander there was a relatively long lever arm through which the force created by the flexible hose at the outer end of the dust discharge tube acted.
In addition, insofar as known, in the past a fitting was utilized at the outer end of the dust discharge tube which effectively increased the length of the dust discharge tube and thus increased the dimension between the vertical centerline of the sander and the outer end of the dust discharge fitting with the attendant increase of the lever arm through which the force exerted by the flexible dust discharge tube acted.
In addition, insofar as known, the compressed air inlet valve structure was not capable of providing small increments of adjustment to the rotary speed of the sander.
In the type of random orbital sanders using central vacuum systems to carry away the abrasives and foreign particles, a high volume of air is drawn through the housing. This causes eddy currents at the various sharp edges including the edges of the eccentric housing which contains the bearings which mount the spindle to which the pad is attached. Abrasives and foreign particles may thus enter the bearing area because they are sucked in to this area because of changes in positive and negative pressures due to the operation of the tool. One attempt to reduce the amount of foreign matter entering the bearing area is shown in U.S. Pat. No. 4,854,085 which utilized a triple seal. This approach did increase the bearing life to a certain degree.
BRIEF SUMMARY OF THE INVENTION
It is one object of the present invention to provide an improved random orbital sander which possesses a plurality of structural features which include a relatively low height and a relatively short inclined dust discharge tube which contribute toward making the sander ergonomically friendly.
Another object of the present invention is to provide an improved random orbital sander which possesses the structural characteristics of the immediately preceding paragraph and also possesses a lower compressed air inlet which further contributes toward making the sander ergonomically friendly.
A further object of the present invention is to provide an improved random orbital sander in which the relatively short dust discharge tube is angled upwardly, thereby further contributing to the ergonomically friendliness of the sander.
A still further object of the present invention is to provide an improved compressed air inlet valve construction which permits small increments of adjustability of the speed of the orbital sander.
Yet another object of the present invention is to provide the dust discharge fitting which is attached to the shroud with an outer end which is internally threaded which receives a flexible hose directly without requiring a special fitting mounted at the outer end of the dust discharge fitting, thereby shortening the lever arm through which the connected end of the flexible hose acts.
Another object of the present invention is to provide an improved structural arrangement for essentially preventing foreign matter from entering the spindle bearing area of a random orbital sander and thus prolonging the life of the bearings to a much greater extent than was heretofore possible by the use of seals.
Other objects and attendant advantages of the present invention will readily be perceived hereafter.
The present invention relates to a surface-treating tool comprising a housing, a motor having a vertical axis in said housing, a pad coupled to said motor, a face on said pad extending substantially perpendicularly to said vertical axis, a shroud surrounding said pad, an opening in said shroud, a dust discharge tube having an inner end in communication with said opening, and an outer end on said dust discharge end extending at an acute angle to said face of said pad.
The present invention also relates to a surface-treating tool comprising a housing having a top, an air motor having a vertical axis in said housing, said motor including a cylinder and rotor and end plates and a shaft, an eccentric on said shaft, and a pad having a face coupled to said eccentric, said surface-treating tool having a height along said vertical axis between said top and said face of said pad which is less than about 86 millimeters.
The present invention also relates to a surface-treating tool comprising a housing having a top, an air motor having a vertical axis in said housing, said motor including a cylinder and rotor and end plates and a shaft, an eccentric on said shaft, and a pad having a face coupled to said eccentric, said surface-treating tool having a weight of less than about 0.75 kilograms.
The present invention also relates to a compressed air flow control valve for a surface-treating tool having a housing, an air motor in said housing, and a compressed air conduit extending through said housing in communication with said air motor, the compressed air flow control valve structure being in communication with said compressed air conduit and comprising a housing unit, a first bore having a first cylindrical wall surface in said housing unit in communication with said compressed air conduit, a valve in said first bore, a base on said valve in engagement with said first cylindrical wall surface, a second wall having an outer cylindrical surface extending outwardly from said base in complementary sliding circumferential engagement with said first cylindrical wall surface, a second bore in said second wall for selective communication with said compressed air conduit, and an inclined groove on said outer cylindrical surface extending away from said second bore.
The present invention also relates to a random orbital action surface-treating tool comprising a housing, a compressed air motor in said housing, a shaft in said motor, a rotor mounted on said shaft, compressed air ducts in said motor for conducting compressed air to said rotor, an eccentric housing mounted on said shaft, a chamber in s
Chao Hao Chien
Gastel Joseph P.
Morgan Eileen P.
LandOfFree
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