Turning – Portable lathe for brake drum – disc – or shoe
Reexamination Certificate
2001-04-26
2003-10-14
Howell, Daniel W. (Department: 3722)
Turning
Portable lathe for brake drum, disc, or shoe
C082S168000, C411S432000, C411S533000
Reexamination Certificate
active
06631660
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains generally to arbor nuts. More particularly, the new and useful invention claimed in this document pertains to a self-aligning arbor system that overcomes unwanted effects of various forces on a rotor, drum such as a brake drum, adapter components, and related components on a rotating arbor. The present invention is particularly, but not exclusively, useful for use in connection with arbors on vehicular brake lathes.
BACKGROUND OF THE INVENTION
A motor vehicle brake is any mechanical device for arresting the motion of a wheel or a vehicle by means of friction. Kinetic energy is converted into heat energy through the use of frictional force applied to the wheels, causing a car to slow or stop. One component of a modern motor vehicle brake is a brake disc, which is the rotating part of a disc brake; the disc often is called a rotor. Another component of a drum brake system is a drum-shaped metal cylinder attached to the inner surface of the wheel that rotates with the wheel. See, for example,
The Road
&
Track Illustrated Automotive Dictionary, ©
2000 John Dinkel, Bentley Publishers, pages 66 and 72. Due to significant heat, to forces applied during braking, and to the environment in which brake systems operate, rotors are subjected to warp, damage, and wear, yet may be correctable and repairable. A rotor or drum may be resurfaced, refinished or otherwise ground or shaped (collectively, “resurfaced”) on a brake lathe. While the present invention is useful in connection with resurfacing at least disks and drums of vehicular brakes, to avoid repetition, primary reference will be made to rotors in this document.
Resurfacing a rotor results in a less expensive aftermarket replacement part. An exemplary brake lathe adapter system for securing a workpiece like a rotor to a rotatable machine member such as an arbor used in the resurfacing process is disclosed in U.S. application Ser. No. 09/394,381, filed on Sep. 9, 1999, since issued as U.S. Pat. No. 6,279,919 B1, issued Aug. 28, 2001, a document incorporated by reference into this document, which names as the sole inventor the inventor of the present invention. Using a brake lathe to resurface, refinish or otherwise work on a rotor associated with a brake system of a car, truck, or other motor vehicles is a major after-market industry in the United States. At least one report of the Automotive Market Research Council indicated projections of sales of aftermarket brake products would increase almost 11% between 1997 and 2000. In the year 2000, sales of drums and rotors were projected to approximate $938,000,000.
Annually, a significant portion of brake rotors and drums are resurfaced, refinished or otherwise worked on by mounting a rotor on a shaft ( frequently called an “arbor”) of a brake lathe machine, securing the brake rotor in a brake lathe adapter, causing the arbor to rotate, and applying one or more tools to the surface of the rotor to resurface, refinish or otherwise perform work on one or more surfaces of the rotor.
At least one of the purposes of a brake lathe adapter and an arbor nut, or arbor locking nut, is to ensure parallelism in a resurfaced rotor. Tolerances are frequently as demanding as plus-or-minus 0.001 inch. Objectives include eliminating runout and taper of the rotor surface, also known as wobbling. Spacers and adapters may be used to keep a rotor's axis substantially perpendicular to the longitudinal axis of the rotating arbor. Excessive torque applied to an locking arbor nut also may significantly affect the parallelism of a refinished rotor.
During refinishing or resurfacing of a rotating workpiece mounted on a rotatable shaft, a rotor and an arbor may be subjected to a variety of forces, and phenomena resulting from such forces. In general, forces due to rotation and gravity tend to preclude uniform rotation of a rotating shaft and a rotating workpiece such as a rotor in a single, unvarying plane of rotation. If the workpiece is a rotor or drum, such as a brake rotor or brake drum mounted on a rotating arbor of a machine such as a lathe, forces acting on the arbor and workpiece during rotation of the arbor and workpiece may distort one or more planes and axes of rotation in connection with the rotor, and exert a variety of angular and planar forces that may affect how accurately and quickly an operator of the lathe may work on the rotor. Forces and force vectors may cause harmonics and vibrations that may be transmitted to the shaft, rotor and other components of the lathe during rotation. Any nonuniform rotation of a rotor during a resurfacing operation may cause a cutting tool brought in contact with a rotor to produce an inferior surface on a working area or surface of a rotor.
During operation of a brake lathe arbor forces include gravity, friction, velocity of rotation, and a variety of load forces applied during operation to bearings, driven shafts, turning spindles, retaining devices, locking nuts, and other components of driving machines and driven shafts (collectively, “machine members”). Similar forces may be induced in a rotor. For example, circular rotation of arbors may give rise to centripetal force, a force that may be reacted to by centrifugal reaction. Angular velocity and angular acceleration of rotating workpieces subjected not only to varying velocities during operation, but also to differing loads or pressures, also may cause gyroscopic effects on a rotor that may turn or rotate over a range of different speeds. Machine members and workpieces also may be subjected to significant loads about their geometric and rotational axes. When more than one force act on a rotatable arbor, a torque may be formed whose vector along an x-axis may produce a rotation about the y-axis known as precession. Such rotation may generate significant angular velocities. All of the foregoing forces, phenomena, torque and related effects (collectively, “forces”) may individually and collectively contribute to causing nonuniform rotation of an arbor and a workpiece attached to an arbor.
In addition to such forces, angular accelerations and velocities may be present in connection with rotating machine members, leading to unbalanced forces that may induce high harmonics, chattering, and vibrations. In some but not all instances, if the speed of rotation of a shaft is slowly increased from rest, a speed may be achieved at which a deflection increases suddenly, a phenomenon known as “whirling.” A shaft that is balanced will rotate around the center of gravity or axis of rotation of a shaft. A shaft rotating at an angular velocity, however, may deflect a distance from the center of gravity or axis of rotation due to centripetal reaction. An unbalanced shaft, for example an arbor that has been deflected or bent and therefore does not rotate around a true center of rotation, also presents additional rotational problems. Rotation also may induce undamped free vibrations.
A variety of apparatus have been proposed to reduce or eliminate such forces and phenomena, seeking to enable a machine operator, including a brake lathe operator, to more effectively resurface a rotating workpiece such as a brake rotor. As indicated, an exemplary solution to the problems is presented by the brake lathe adaptor system disclosed in U.S. application Ser. No. 09/394,381 since issued as U.S. Pat. No. 6,279,919 B1, issued Aug. 28, 2001.
Overlooked, however, until now, among components other than a brake lather adaptor system for an effective brake lathe system has been the arbor nut, or arbor locking nut (collectively, “arbor nut”). At least one objective of the components, individually or collectively, used to position a rotor on an arbor is to position the rotor during operation substantially perpendicular to the rotating arbor. In turn, that objective seeks to overcome the inherent effect of forces that induce vibration and chattering in the rotor. The typical conventional arbor nut is not capable of applying a consistent, predictable, uniform force against brake lather adapter
Howell Daniel W.
Law Office of Ray R. Regan, P.A.
Sun Standard, Inc.
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