Patent Application
20250237586
The present disclosure relates to methods of manufacturing carbon brake disks, such as may be used for example in aircraft brake stacks or comparable applications, and in particular the present disclosure relates to a method of quality assurance testing for such brake disks.
The present disclosure is focused on ensuring high quality and reliability of the brake disk components of the brake stacks to ensure the brake disks can handle applicable loads that occur during braking. To ensure quality and reliability at the time of manufacturing, quality assurance testing of the brake disks is performed to provide confidence in load bearing capabilities of a manufactured batch lot of brake disks. Currently, quality assurance testing for carbon brake disks, including carbon aircraft brake disks, is accomplished by destructively testing a portion of finished brake disk product of a batch lot. A common method of destructive testing is a proof type test in which a lug area of the brake disk is fixtured in a tensile test machine. The disk lug area is then pulled to failure, and the resulting load is measured and reported for batch acceptance. The destructive nature of such testing is costly in that the tested brake disk can no longer be used. Typically, the factory cost value of a carbon brake disk is about $1000 each, with the sales value being substantially higher. Approximately 1-2% of carbon brake disks are destroyed for quality assurance testing, resulting in significant loss of otherwise saleable product.
There is a need in the art, therefore, for an improved method of brake disk quality assurance testing that eliminates the destructive nature of such testing and the resultant loss of saleable product. Embodiments of the present disclosure provide for numerous carbon disk designs to be non-destructively quality assurance tested, thus increasing revenue, reducing costs of testing, and improving expediency of test results. Increased quality assurance testing may be performed for more brake disks as compared to conventional quality assurance testing without significantly increasing cost, which results in improved statistical process control and reduced scrap through advanced warning and correction.
In embodiments of the present disclosure, effective quality assurance testing is achieved by replacing the conventional test, which destroys the tested finished brake disk product, with testing of a small “coupon” test sample taken from a blank brake disk source, whereby the coupon sample is acquired without causing damage to the brake disk source, which then can be finished into a saleable brake disk product. Brake disks typically are manufactured by machining using a computer numerical control (CNC) milling machine. By making minor modifications to the CNC mill machining program, small compression coupon test samples are made in a lug area of the brake disk source that is subsequently machined away for keying with the wheel assembly, and therefore not part of the finished brake disk product. The small coupon samples are easily removed from a blank brake disk source without taking the brake disk source from the milling machine, and thus not losing any brake disk part indexing or additional time.
A compression coupon sample portion is held in place on the brake disk source only by thin remaining material, and therefore the coupon sample easily can be snipped off from the brake disk source, such as with a scissors or comparable simple cutting tool. The coupon sample then can be subjected to quality assurance testing, such as being inspected, measured, and then submitted for load testing. When the CNC mill machine is combined with or proximate to a tensile test machine, the entire operation including manufacturing and quality assurance testing can be performed efficiently, providing prompt batch acceptance data for a batch lot of brake disk material being machined. The method of the present disclosure in particular has proven suitable for multiple larger diameter rotor disk designs, and similarly is feasible for larger diameter stator disk designs.
An aspect of the invention, therefore, is a method of quality assurance testing for a brake disk that does not result in destruction of the brake disk. In exemplary embodiments, the method includes the steps of: forming a blank brake disk source to be processed into a finished brake disk; forming a lug area in the brake disk source for alignment of the finished brake disk; notching a portion of an outer periphery of the lug area of the brake disk source to define a sample portion within the brake disk source; removing the sample portion from the lug area of the brake disk source, wherein the brake disk source is not destroyed by formation and removal of the sample portion, the removed sample portion being a coupon sample; and strength testing the coupon sample. Removal of the sample portion is performed without removing the brake disk source from a machine, such as a CNC mill, that holds the brake disk source while the sample portion is formed. After removing the coupon sample from the brake disk source, the brake disk source is further processed as needed to form the finished brake disk.
In an exemplary embodiment of the method of quality assurance testing, the coupon sample is formed from at least a majority of the lug area of the outer periphery of the brake disk source.
In an exemplary embodiment of the method of quality assurance testing, the coupon sample is formed including a portion of the outer periphery of the brake disk source outside of the lug area.
In an exemplary embodiment of the method of quality assurance testing, removal of the sample portion is performed without removing the brake disk source from a machine that holds the brake disk source while the sample portion is formed.
In an exemplary embodiment of the method of quality assurance testing, upon removal from the brake disk source, the sample portion retains ridges that result from the notching, the method further comprising dressing off the ridges to form the coupon sample.
In an exemplary embodiment of the method of quality assurance testing, removing the sample portion from the brake disk source comprises cutting the sample portion from brake disk source with a cutting tool.
In an exemplary embodiment of the method of quality assurance testing, the cutting tool is a scissors.
In an exemplary embodiment of the method of quality assurance testing, strength testing the coupon sample comprises compression testing the coupon sample in a testing machine.
In an exemplary embodiment of the method of quality assurance testing, the method further includes, after removing the coupon sample from the brake disk source, finish processing the brake disk source to form the finished brake disk.
In an exemplary embodiment of the method of quality assurance testing, the finish processing includes removing material of the lug area from the brake disk source and forming rivet holes in the brake disk source.
In an exemplary embodiment of the method of quality assurance testing, at least the step of notching the portion of the outer periphery of the lug area of the brake disk source is performed by a CNC milling machine.
In an exemplary embodiment of the method of quality assurance testing, the steps of forming the lug area in the brake disk source and notching the portion of the outer periphery of the lug area are performed by a same machine.
In an exemplary embodiment of the method of quality assurance testing, the steps of forming the lug area in the brake disk source, notching the portion of the outer periphery of the lug area, removing material of the lug area from the brake disk source, and forming rivet holes in the brake disk source are performed by a same machine.
In an exemplary embodiment of the method of quality assurance testing, the same machine is a CNC milling machine.
These and further features of the present invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the invention may be employed, but it is understood that the invention is not limited correspondingly in scope. Rather, the invention includes all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
Embodiments of the present application will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. It will be understood that the figures are not necessarily to scale.
Reference first is made again to the overall wheel brake system 10 of
As further detailed below, in accordance with embodiments of the present application, prior to machining away all the material in a given lug area, a coupon sample is taken from the lug area material for subsequent quality assurance testing. By taking the coupon sample from lug area material that otherwise is machined away for brake disk alignment and keying, quality assurance testing is performed without having to destroy the broader brake disk or otherwise damaging the brake disk. As a result, even a brake disk that specifically is subjected to quality assurance testing can be used as a finished brake disk product.
During manufacture, a lug area 52 is formed by notching out a portion adjacent to an outer edge or periphery 49 of the brake disk source 50. In particular, the lug area 52 is defined by keying notches or slots 51 which define the lug area 52 that subsequently will be machine away to create the notches that are used for alignment with a wheel assembly. During manufacture, rivet holes 53 also may be formed in the brake disk source 50. In typical brake disk formation, U-shaped channels (not shown) are applied over a portion of the face of the brake disk source 50 along the outer periphery 49. The U-shaped channels typically are formed as metal plates that lie over the carbon material of the brake disk source, such that the U-shaped channels act as reinforcing impact areas for interacting with the wheel keys during braking. Rivets (also not shown) extend through the U-shaped channels and through the rivet holes 53 to fasten the U-shaped channels to the carbon brake disk source 50.
A compression coupon sample 54 is formed in the lug area 52 of the brake disk source 50 between the keying notches 51. By forming a coupon sample in an area of the brake disk source where the keying notches already are being formed, a machining program readily can be adapted to form the compression coupon sample 54 in addition to the keying notches 51.
In conventional manufacturing processes, a blank brake disk source is formed using a lathe. The blank brake disk source is then transferred to a CNC mill machine, which as programmed forms the lug area, alignment notches, and rivet holes. As referenced above, material within the lug area is machined away for alignment with and keying into the wheel assembly. By making minor modifications to the CNC mill machining program, small compression test coupon samples are made in the lug area of the brake disk source that subsequently is to be machined away, and therefore not part of the finished brake disk product. By taking the coupon sample from lug area material that otherwise is machined away for brake disk alignment and keying, quality assurance testing can be performed on the coupon sample without having to destroy the broader brake disk or otherwise damaging the brake disk. As a result, even a brake disk that specifically is subjected to quality assurance testing can be used as a finished brake disk product. The small coupon samples are easily removed from a blank brake disk source without taking the brake disk source from the milling machine, and thus without losing any brake disk part indexing or additional time.
Referring to
As further shown in
As referenced above, a blank brake disk source typically is formed using a lathe. In one exemplary embodiment, a largely blank brake disk source is quality assurance tested prior to machining into a finished brake disk product. A blank brake disk source essentially comes off the lathe as a featureless donut disk. A CNC mill machine then may be employed to form the coupon sample as described above, and the coupon sample is quality tested at the donut stage. This process is repeated on numerous blank disk sources to manufacture a batch of quality-tested brake disk sources. When needed at a subsequent time, these quality-tested brake disk sources can be inserted again into a CNC mill machine to perform the additional finishing steps, such as removing the remaining material from the lug area, forming the rivet holes, and other finishing steps that may be required for a given application. By testing blank brake disk sources at the donut stage, quality assurance is verified early in the manufacturing process, although the quality assurance machining and the finishing machining are divided into separate machining programs and operations.
Alternatively, the donut blank disk sources may be completely machined into finished brake disk products within a single process. In such process, the coupon samples are formed as described above, which is followed in a single machining program by the additional finishing steps, such as removing the remaining material from the lug area, forming the rivet holes, and other finishing steps that may be required for a given application. By removing the coupon sample for testing the brake disk source as part of a single program that results in a finished brake disk product, quality assurance is verified later in the manufacturing process, but the quality assurance machining and finishing machining are combined more efficiently into a single machining program and operation. When the CNC mill machine is combined with or proximate to a strength testing machine, the entire operation including manufacturing and quality assurance testing can be performed efficiently, providing prompt batch acceptance data for a batch lot of brake disk material being machined.
Preliminary studies have shown the above processes to be particularly suitable to work for multiple larger diameter rotor disks, and also is feasible for large diameter stator disk designs. With relatively larger diameter brake disks, the outer diameter of the brake disk may be large enough and/or the coupon sample may be small enough such that the size of the coupon sample relative to the brake disk is negligible. The methods of the present disclosure provide for numerous carbon disk designs to be non-destructively quality assurance tested, thus increasing revenue, reducing costs of testing, and improving expediency of test results. Increased quality assurance testing may be performed for more brake disks as compared to conventional quality assurance testing without significantly increasing cost, which results in improved statistical process control and reduced scrap through advanced warning and correction.
Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
| Number | Date | Country | |
|---|---|---|---|
| 63623884 | Jan 2024 | US |
