Data processing: measuring – calibrating – or testing – Calibration or correction system – Error due to component compatibility
Reexamination Certificate
1998-06-04
2001-05-15
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Error due to component compatibility
C702S091000, C702S113000, C702S168000, C701S070000
Reexamination Certificate
active
06233533
ABSTRACT:
FIELD OF THE INVENTION
This invention relates machining rotors and, more specifically, to a non-contact inspection system integrated with a turning center for machining rotatable brake rotors.
BACKGROUND OF THE INVENTION
Motor vehicles use various mechanisms to facilitate braking. Well known among these braking mechanisms is a combination of a disc rotor connected to a wheel of the vehicle. In order to stop or slow the vehicle, pressure is applied by a brake caliper clamping brake pads against one or more outer surfaces of the disc rotor (e.g., using so-called disc brakes), thereby slowing or stopping the rotation the wheel.
Some rotors have a veined construction. A typical veined rotor
100
is depicted in
FIGS. 1 and 2
, wherein
FIG. 1
shows a front view and
FIG. 2
shows a side view of the rotor
100
. A portion of the rotor
100
(between the lines I and II) is cut away to show the inside veined structure of the rotor. The veined rotor essentially is made up of two disc plates separated and connected by a number of veins. The veins can be straight or curved and the number of veins varies from one rotor to another. For example,
FIGS. 3 and 4
show an example of an unmachined veined rotor with curved veins. The rotor
100
has two outside surfaces
102
,
104
, these surfaces being provided by the outer surfaces of the two discs comprising the rotor. It is against these two surfaces
102
,
104
that pressure is applied (e.g., by brake pads (not shown)) in order to slow or stop the rotation of the wheel drive connected to the rotor
100
. Ideally, the rotor
100
is perfectly circular and these surfaces
102
,
104
are parallel to each other.
A typical rotor
100
is manufactured by machining a pre-cast rotor. A cast, pre-machined rotor
106
is shown in
FIGS. 5 and 6
which depict front and side views of the pre-cast, un-machined rotor
100
, respectively. The rotor
100
shown in
FIGS. 1 and 2
is produced by appropriately machining the cast rotor
106
.
A number of problems or defects can exist with existing rotors, and some of these problems or defects can be traced back to the manner in which the rotors were machined. For example, as noted above, in order to prevent or avoid uneven wear and heat of the rotors surfaces, the two surfaces
102
,
104
are ideally parallel. In prior machining systems, the parallelness of the two surfaces was not determined prior to machining. Further, after machining, it is desirable to minimize thickness variation (TV) and lateral run-out (LRO) of each rotor as well as to have a symmetric rotors. A summary of these problems can be found in “Using Capacitive Probes in Automotive Brake Component Testing,” Steve Muldoon and Rick Sandberg,
Test Engineering & Management
, August/September 1997 (hereinafter “Muldoon”). Muldoon is hereby incorporated herein in its entirety by reference. Muldoon shows the use of non-contact capacitance probes in post-production brake testing.
SUMMARY OF THE INVENTION
It is desirable to produce brake rotors that are of superior quality and that do not suffer from the drawbacks of prior systems. It is therefore desirable to incorporate the non-contact inspection systems into a brake turning center so as to dynamically test and, when appropriate, alter the instructions to the center. In this manner, potential problems are caught during rather than after machining.
Accordingly, this invention solves the above and other problems by providing, in one aspect, a system, incorporated into a turning center, the system having pairs of non-contact sensors, pointing at the braking surfaces and a non-contact sensor pointing at the outer and/or inner diameters of the disc. The non-contact sensors can be inductive sensors, capacitive probes and/or laser sensors. A controller is connected to each sensor for signal processing and measurement output. Each sensor can be calibrated by a gauge block, master part or in any appropriate manner. The system can measure various features and characteristics, such as, but not limited to, braking surface thickness variation, lateral and/or radial run-out, flatness, parallelism and diameters and other appropriate and useful features.
Measurements are made while the disc rotates at a specified, known speed or is stationary. The one or more pairs of non-contact sensors continuously measure the distance from the sensor or calibrated surface to the pointed surface. Therefore the lateral and/or radial run-out and thickness variation can be calculated from the measurements at multiple (preferably three) different radii. By combining the measurements on the same braking surface, the flatness and parallelism can be calculated. The other two sensors continuously measure the distance from the sensor or the calibrated surface to the pointed surface. A diameter can be calculated knowing the center of the disc.
The lateral and/or radial run-out, thickness variation, flatness and parallelism can be measured on each brake disc within the turning center for final inspection and/or statistical process control. The diameter measurement and its run-out can be fed back to the turning center to monitor and compensate tool wear.
In another aspect, this invention is a method of machining a part mounted in a chuck of a computer-controlled turning system. The method includes positioning a plurality of non-contact sensors to point at the part; obtaining measurements from the sensors; calculating attributes of the part based on the measurements; and dynamically adjusting the clamping force of the chuck on the part based on the calculated attributes. The measurements can be obtained from the sensors while the part is mounted in the turning system or while the part is removed from the system.
In preferred embodiments, the part is a disc brake rotor and wherein the attributes include at least some of: braking surface thickness variation of the disc, lateral and/or radial run-out of the disc, flatness of the disc, and parallelism of the disc.
Preferably the non-contact sensors are selected from inductive sensors, capacitive probes and laser sensors.
In some embodiments other aspects of the machining center itself are measured. For example, the method can include measuring, while turning, at least some of: (a) the deflection of the rotor; (b) spindle movement and/or run-out; (c) chuck movement and/or run-out; (d) tool movement. These measurements can be used to adjust the clamping force of the chuck on the part based on the measured attributes.
REFERENCES:
patent: 4290510 (1981-09-01), Warren
patent: 4457172 (1984-07-01), Mathes
patent: 4523499 (1985-06-01), Aldridge, Jr.
patent: 4669046 (1987-05-01), Kubo
patent: 4823071 (1989-04-01), Ding et al.
patent: 4899218 (1990-02-01), Waldecker et al.
patent: 4945763 (1990-08-01), Mueller
patent: 5046361 (1991-09-01), Sandstrom
patent: 5077806 (1991-12-01), Peters et al.
patent: 5125187 (1992-06-01), Thiem
patent: 5239486 (1993-08-01), Mortier
patent: 5327782 (1994-07-01), Sato et al.
patent: 5352305 (1994-10-01), Hester
patent: 5378994 (1995-01-01), Novak et al.
patent: 5485678 (1996-01-01), Wagg et al.
patent: 5566244 (1996-10-01), Kato et al.
patent: 5615589 (1997-04-01), Roach
patent: 5657233 (1997-08-01), Cherrington et al.
patent: 5717595 (1998-02-01), Cherrington et al.
patent: 5734569 (1998-03-01), Rogers et al.
Burgoon Donald Lee
Xu Hong
Performance Friction Corporation
Pillsbury & Winthrop
Shah Kamini
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