Brakes – Elements – Brake wheels
Reexamination Certificate
2001-05-04
2001-11-27
Schwartz, Christopher P. (Department: 3613)
Brakes
Elements
Brake wheels
C188S078000
Reexamination Certificate
active
06321886
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to vehicle brake drums and in particular to an improved final balanced brake drum having an integral squealer band and method for producing the same.
The production of cast metal brake drums for heavy duty vehicles begins with a conventional sand-patterned mold casting operation. After cleaning, the brake drum casting is precision drilled and concentrically machined to predetermined dimensional tolerances. However, at this point, the machined brake drum typically incorporates a sufficient imbalance which renders the brake drum unsatisfactory for use on a vehicle. As a result of this, the brake drum is generally subjected to a “final balancing” operation. Conventionally, this final balancing operation has been achieved by determining the location and amount of the imbalance using a static balancer, and then welding correcting weights to an outer surface of the drum.
Typically, a heavy duty brake drum is provided with an integral raised squealer band. One method which can be used to final balance a brake drum having a squealer band subjects the drum to a final machining operation. According to this method, a static balancer is fist used to determine the location and amount of the imbalance. An operator then marks the location of the imbalance on the squealer band, and transfers the marked drum to a milling machine. The milling machine is operated and flattens off an outer surface of the squealer band at the marked imbalance location to produce a final balanced brake drum.
U.S. Pat. No. 4,986,149 to Carmel et al. discloses another method for correcting the imbalance in a brake drum having an integral squealer band by subjecting the drum to a final machining operation. According to the method of this patent, a static balancer is first used to determine the location and amount of to the imbalance. Then a crescent or wedge or material is preferably cut away from an outer surface of a squealer band of the brake drum by a lathe during an eccentric turning process to produce a final balanced brake drum.
SUMMARY OF THE INVENTION
This invention is an improvement on the method of the above discussed U.S. patent to Carmel et al. The improved method for final balancing a brake drum determines the location and length of a first constant depth cut and a second constant depth cut along the squealer band which are necessary to correct the imbalance, and using a cutting machine, makes the first and second constant depth cuts at the predetermined location and for the predetermined length along the squealer band to produce a final balanced brake drum. Preferably, the cutting machine is a milling machine which produces a plunge type entrance/exit cut. It is a further feature of the invention to provide a feather type entrance/exit cut to reduce the stress concentrations, and produce a cosmetically more appealing final balanced brake drum.
As a result of correcting the imbalance by making the first and second constant depth cuts along the squealer band, a greater imbalance in the brake drum can be corrected compared to the prior art.
Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawing.
REFERENCES:
patent: 3817149 (1974-06-01), Reutlinger
patent: 4986149 (1991-01-01), Carmel et al.
patent: 5352305 (1994-10-01), Hester
patent: 5483855 (1996-01-01), Julow et al.
patent: 5538111 (1996-07-01), Gee
patent: 5586625 (1996-12-01), Julow et al.
patent: 5664648 (1997-09-01), Hester
patent: 5782324 (1998-07-01), Wall
patent: 5992581 (1999-11-01), Julow et al.
Micro-poise Model 2897-DPMA Automatic In-Line Transfer Drum Balancing and Mill Correction Machine With LVDT Balance Measurement System, Operation and Maintenance Manual With Parts List, Apr. 1986, pp. i-ii, 1-2 and 11-12, with cover letter of Apr. 27, 2000.
Information Disclosure Statement filed Dec. 31, 1998 (7 pages) during prosecution of 5,992,581.
DeRegnaucourt Robert A.
Hall John C.
Hester Larry B.
Julow Jay K.
Carlson & Gaskey & Olds
Meritor Heavy Vehicle Technology LLC
Schwartz Christopher P.
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