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US 5,392,568 AGranted
Random orbit sander having braking member
AssigneeBlack & Decker Inc.
InventorsThomas J. Howard, Jr., David L. Sutton
Life of this patent
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AssigneeBlack & Decker Inc.
InventorsThomas J. Howard, Jr., David L. Sutton
Estimating the term…
A random orbit sander having a braking member for frictionally controlling the speed of a platen of the sander when the sander is removed from a workpiece during operation. The braking member includes a base portion, an outwardly flaring, relatively thin wall portion and an enlarged outermost edge portion adapted to frictionally engage an upper surface of the platen. The braking member is secured to the bottom of the shroud of the housing via a groove formed in its base portion. The braking member exerts a relatively constant spring force against the upper surface of the platen which limits the rotational speed of the platen to approximately 1200 rpm when the platen is lifted off of a work surface, without significantly degrading the performance of the sander under load. This prevents swirl marks and other undesirable scratches from being made in a workpiece when the platen is reapplied to the workpiece as a result of the platen having increased in speed to an unloaded, free-wheeling speed, and yet allows the platen to operate at or above the minimum desired working speed of about 800 rpm. The braking member is formed from polyester butylene terephthalate which is doped with approximately 2% silicon and approximately 15% teflon in the preferred embodiments. This material formulation, plus its geometry, allows the braking member to exert and maintain a relatively constant spring force of about 3.5 lbs. against the platen and to resist frictional wear once past an initial break-in period. The braking member also acts as a seal between the lower surface of the shroud and the upper surface of the platen.
A random orbit sander having a motor, a platen driven rotationally by said motor and spaced axially apart from a lower surface of a housing of said sander, the improvement comprising:
A random orbit sander comprising a motor, a platen driven rotationally by said motor and spaced axially apart from a lower surface of a housing of said sander, the platen having at least one opening therethrough, a fan for drawing dust and particulate matter through said opening, and braking means for controllably, frictionally braking said platen to control the rotational speed of said platen when said platen is lifted off of a work surface during operation of said sander without significantly degrading the performance of the sander under load;
A random orbit sander comprising a motor, a platen driven rotationally by said motor and spaced axially apart from a lower surface of a housing of said sander, and a braking member interposed between the lower surface of the housing and an upper surface of the platen for controllably, frictionally engaging said upper surface of said platen to thereby effect a braking action on the rotation of said platen to limit the rotational speed of said platen when said platen is lifted off of a work surface during operation of said sander without significantly degrading the performance of the sander under load;
Dependencies are inferred from the claim text.