Using physical surface finishing for rapid and effective surface depth measurement of metal components

Abstract

This invention is titled "Rapid and Effective Measurement of Surface Depth of Metal Components Using Physical Surface Trimming." A method for determining the effective surface depth of a metal component includes forming a trimmed core surface by blasting or shot peening an exposed surface of the metal component with a blasting medium. The exposed surface is a continuous exposed surface of the surface and the core. The method includes measuring the surface texture, compressive stress, or another suitable feature of the trimmed core surface using a surface metrology sensor, and using the measured features to identify the surface-core boundary, including identifying the location of predetermined differences or gradients within the exposed surface. The method also includes measuring the effective surface depth as the vertical distance between a reference surface of the surface and the surface-core boundary.

Description

Background Technology

[0001] Metal components typically experience sliding contact along critical working surfaces, leading to component damage and failure over time. For this reason, selectively hardening critical working surfaces is beneficial. For example, the interface surfaces of rotating gear elements or rotating shafts can be selectively infused with elements suitable for the application to produce a final product with the desired mechanical properties. This process is known in the art as case hardening, where the hardened / infused layer (one or more) or surface layer has increased surface hardness relative to the uninfused areas of the component (i.e., the core), resulting in increased wear resistance and fatigue resistance. A softer core material is better suited to absorbing loads transmitted through the metal component, which is in turn crucial to the component's performance and long-term durability. Similar beneficial effects can be achieved by cladding compatible hard and soft alloys together as a composite metal material.

[0002] Despite close control and monitoring of surface hardening process parameters during component manufacturing, it remains necessary to verify the effective surface depth (surface hardened layer depth, carburized layer depth, case depth) of metal components. Hardness testing techniques are relatively straightforward when applied to accessible surfaces of metal components. However, in aerospace, transportation, and other industries utilizing surface hardening technologies, the availability of surface hardening data alone is insufficient. Consequently, accurate and repeatable measurements of the effective surface depth or comparable depth of other mechanically reinforced surfaces or layers often require sacrificial test samples and extensive, time-consuming processing steps, such as sample removal / cutting, mounting, and polishing, followed by hardness measurements and data processing.

[0003] Indentation-based macroscopic hardness testing systems are commonly used to measure the surface hardness of metal components. Since hardness generally refers to a given metal component's resistance to plastic deformation under calibrated loads, such hardness testing systems operate by indenting an indenter constructed of a baseline hard material (such as diamond or tungsten carbide) into the test surface at single / discrete locations under a specific load or a set of loads, and then measuring the depth to which the indenter penetrates the test surface. When evaluating the effective case depth of a surface-hardened layer, a series of micro-hardness indentations are placed at specific distances from the component's surface and measured. The resulting hardness profile is used to determine the effective case depth, which is the vertical distance from the surface of the hardened layer to a point where the hardness level equals the specified material / application value. It will be understood that "effective case depth" differs from "total case depth," which is the vertical distance from the surface of the layer to a point where differences in chemical or physical properties cannot be distinguished within the microstructure of the metal component.

[0004] In contrast to macroscopic hardness testing, microscopic hardness testing systems can be used to generate hardness distribution maps. The technical principle of these systems is almost identical to that of macroscopic hardness testing systems, except that specialized software is used to measure the size and shape of the indentation rather than the penetration depth to generate hardness values. When the surface geometry of a metal component is relatively intricate, it may be necessary to verify the effective surface depth at several discrete locations, potentially requiring hundreds or even thousands of individual indentations to verify the effective surface depth in the desired critical areas.

[0005] Due to the sensitivity of microhardness testing, minute variations in the tester's or operator's actions can affect the reported depth and hardness values. These variations include factors such as calibration blocks, indentation spacing, microscope illumination, and the position / orientation of the traverse. Similarly, visual techniques used to provide coarse estimates of hardness depth tend to rely on surface notches and therefore on the chemical exposure of the test sample. This, in turn, introduces measurement variability due to factors such as etchant age, etching duration, and the uniformity of the microstructure of the test surface. Summary of the Invention

[0006] This document discloses methods and related systems for rapidly measuring the effective surface depth or similar depth of a metal assembly having a relatively hard layer positioned adjacent to a relatively soft layer. For consistency, the harder layer is referred to herein as the surface layer, and the softer layer as the core, without specifically limiting this teaching to surface-hardened metal. That is, this disclosure can also be applied to the effective depth measurement of different layers of a metal assembly constructed by using cladding and / or other layered materials, as well as to metal assemblies having surfaces selectively hardened by heat treatment or other processes.

[0007] The solution disclosed herein can replace or be combined with conventional indentation-based hardness testing methods of the types generally described above as an integral part of a quality inspection or quality assurance process. The proposed solution allows users to bypass some of the most time-consuming steps in conventional hardness testing processes to rapidly measure the effective surface depth over a larger area. As a result, the additional time and variability typically associated with indentation-based hardness testing strategies are significantly reduced.

[0008] The reliability of this method is based on an identifiable correlation between hardness-related characteristics (such as, but not limited to, surface texture and internal stress) and the corresponding surface hardness of the metal component. Therefore, the method according to embodiments of this disclosure produces these characteristics by physically conditioning (cleaning, adjusting, treating, conditioning) the exposed surfaces of the metal component, wherein the term "physical conditioning" excludes the use of chemical etchants and other chemical surface treatment processes that would favor controlled plastic deformation over a wider area of ​​the exposed surface in embodiments of this disclosure.

[0009] Sufficient physical surface finishing within the scope of this disclosure can be achieved by blasting or shot peening the exposed surfaces of metal components with a suitable blasting medium, such as spherical beads and / or asymmetric glass sheets, metal, or ceramics collectively having a well-defined medium hardness level. Although each individual sheet or bead of the blasting medium used in a given batch will not necessarily have exactly the same hardness level, the bulk of the medium material or shot peening medium hardness level in a common batch falls within a defined hardness tolerance or maximum-minimum hardness range, where the medium hardness level for a given batch is typically set by the manufacturer. Therefore, the medium hardness level is an optional fixed parameter as part of the methods of this disclosure. After physical surface finishing of the exposed surface, a surface metrology sensor is used to measure and quantify the resulting characteristics.

[0010] Using the appropriate selection and application of control parameters as shown in this paper, uniform physical trimming of the exposed surfaces (including the exposed continuous surfaces of the core and the surface layer) will result in little or no surface deformation on the exposed surface layer. In contrast to the surface layer, the exposed core surface will be altered in a measurable and quantifiable manner to produce a trimmed core surface. Therefore, a surface metrology sensor can be used as part of this method to detect the transition or boundary between the surface and the core, where such a boundary is referred to below as the surface-core boundary, and then used to measure the effective surface depth.

[0011] Therefore, the proposed solution utilizes a physical media jetting operation with well-defined parameters such as blast pressure, average and peak blasted media hardness, media shape and size distribution, standoff distance, and coverage, all of which contribute to ensuring process repeatability. Similarly, compared to existing indentation-based microhardness testing systems, the proposed solution is better suited for simultaneously evaluating larger, more complex samples and multiple test locations.

[0012] According to an exemplary embodiment, a method for determining the effective surface depth of a metal assembly includes physically trimming exposed surfaces of the metal assembly to form trimmed surfaces, including subjecting continuous regions of the surface and core of the metal assembly to a physical surface trimming process. The trimmed surfaces include trimmed surfaces of the surface and core, wherein these surfaces are continuous. The method according to this embodiment includes measuring features of the trimmed surfaces using a surface metrology sensor, and then using the measured features to locate the surface-core boundary. Locating the surface-core boundary includes identifying locations on the trimmed surface where predetermined differences or gradients in the measured features indicating the surface-core boundary are present. The method also includes measuring the effective surface depth as a vertical distance between a reference surface of the surface and the surface-core boundary.

[0013] Physical finishing of exposed surfaces may include blasting or shot peening the exposed surfaces using a blasting medium. For example, when the metal assembly is optionally constructed of carburized steel (e.g., 9310 steel) having a surface hardness of about 50 HRC, the hardness level of the blasting medium may be in the range of about 48 HRC to 52 HRC, and physical finishing of the exposed surfaces of the metal assembly may include blasting or shot peening the exposed surfaces at a pressure of about 40 psig and a coverage level of about 200% from a projection distance of about 6 inches.

[0014] In some embodiments, the measurement feature includes the measured surface texture or roughness, where the surface metrology sensor includes a profilometer (surface finish meter). The profilometer can be configured as a non-contact profilometer, such as a laser profilometer, scanning interferometer, or reflectometer. Other configurations of the metrology sensor include an X-ray diffractometer, where the measurement feature is the level of internal compressive stress.

[0015] The metal component can represent a build quantity or batch. In such applications, the method may optionally include, for example, comparing the measured effective surface depth with a threshold effective surface depth (from a blueprint of the metal component or another calibrated reference), and automatically performing quality assurance and / or control actions for the build quantity or batch when the measured effective surface depth is less than the threshold effective surface depth.

[0016] Some implementations of the method involve cutting the metal component to form an exposed surface such that the exposed surface is a cross-sectional area of ​​the metal component. Additionally, this disclosure can drive backward design modifications that allow cross-sections (such as gear endfaces) of continuous regions of the surface and core to be visible, thereby allowing for effective surface depth measurements without such cutting.

[0017] A system for determining the effective surface depth of a metal assembly is also disclosed. One embodiment of this system includes the aforementioned surface measurement sensor, an electronic control unit (ECU), and a measuring tool. The surface measurement sensor is configured to measure features of a trimmed core surface of the metal assembly. The trimmed core surface is part of the exposed surface of the metal assembly following the exposed surface, wherein the successive surface and core surfaces undergo a physical surface trimming process uniformly. The ECU is in communication with the surface measurement sensor and is configured to use measurement features to identify the surface-core boundary of the exposed surface. The surface-core boundary includes the location where a predetermined difference or gradient in the measurement features exists on the exposed surface. The measuring tool, also in communication with the ECU, is configured to measure the effective surface depth as the vertical distance between a reference surface of the surface and the surface-core boundary.

[0018] A method according to another embodiment can be used to determine the effective surface depth of a carburized steel assembly having a surface layer and a core. The surface layer hardness level is greater than about 50 HRC. The core hardness level is less than about 48 HRC. The method includes forming a trimmed core surface by uniformly blasting or shot peening the exposed surface of the metal assembly with a blasting medium having a hardness level in the range of about 50 HRC to 52 HRC. The exposed surface of the metal assembly is a continuous surface of the surface layer and the core. The method also includes measuring the surface texture of the trimmed core surface using a profilometer, and then using the surface texture to identify the surface-core boundary, including identifying the location of predetermined differences or gradients in the surface texture present throughout the exposed surface, which indicate the surface-core boundary.

[0019] Additionally, the method in this embodiment includes measuring the effective surface depth as the vertical distance between a reference surface of the surface and the surface-core boundary. Forming the trimmed core surface involves blasting or shot peening the exposed surfaces of the carburized assembly at approximately 40 psig with a blasting medium or shot peening, achieving approximately 200% coverage.

[0020] The foregoing summary is not intended to represent every embodiment or aspect of this disclosure. Rather, the foregoing summary provides only examples of some novel concepts and features set forth herein. These features and advantages, as well as others, will become apparent when taken in conjunction with the accompanying drawings and the appended claims, based on the following detailed description of exemplary embodiments and representative modes for carrying out this disclosure. Furthermore, this disclosure expressly includes any and all combinations and sub-combinations of the elements and features presented above and below. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a representative metal component with a relatively hard layer or surface (whose effective depth can be measured using this method).

[0022] Figure 2 This is a schematic flowchart depicting an exemplary method for determining the effective surface depth of a metal component.

[0023] Figure 3 Is as Figure 2 The diagram illustrates a portion of a shot peening process, which can be used to physically finish one or more surfaces of a metal component.

[0024] Figure 4 This is a schematic diagram of a system for measuring surface texture and effective surface depth as part of this method.

[0025] Figure 5 These are representative charts showing surface hardness and surface roughness on the horizontal and vertical axes, respectively.

[0026] This disclosure can be extended to modifications and alternatives, wherein representative embodiments are shown by way of example in the accompanying drawings and described in detail below. The inventive aspects of this disclosure are not limited to the disclosed embodiments. Rather, this disclosure is intended to cover modifications, equivalents, combinations, and alternatives that fall within the scope of this disclosure as defined by the appended claims. Detailed Implementation

[0027] This disclosure can be implemented in many different forms. Representative embodiments of this disclosure are shown in the accompanying drawings and will be described in detail herein, and are to be understood as providing these embodiments as examples of the principles of this disclosure, rather than limiting the broad aspects of this disclosure. In this regard, elements and limitations described, for example in the abstract, background, summary, and detailed description sections but not expressly set forth in the claims, should not be incorporated, alone or jointly, into the claims by implication, inference, or otherwise.

[0028] For the purposes of this detailed description, unless specifically stated otherwise: the singular includes the plural and vice versa; for example, “a” means “at least one” or “one or more”; the words “and” and “or” should be conjunctions or disjuncts; the words “any” and “all” should both mean “any and all”; and the words “including,” “containing,” “comprising,” “having,” etc., should all mean “including but not limited to.” Furthermore, approximate words such as “about,” “almost,” “substantially,” “approximately,” “approximately,” “generally,” etc., may be used herein in the sense of “in, near, or in the vicinity,” “within 0-5%,” “within acceptable manufacturing tolerances,” or any logical combination thereof.

[0029] Referring to the accompanying drawings, where the same reference numerals denote the same features throughout several views, Figure 1 A simplified embodiment of the metal assembly 10 is schematically depicted. For simplicity of example, the metal assembly 10 is shown as a non-limiting exemplary axial end view of a rotating shaft 10R having an outer diameter surface 11 and a longitudinal central axis 12. However, this teaching is extendable to numerous other embodiments of the metal assembly 10, such as gear elements, panels, beams, turbine blades, etc., and therefore... Figure 1 The simplified implementation is intended to be exemplary and not restrictive.

[0030] The metal assembly 10 according to this disclosure includes one or more layers of relatively hard metallic material (collectively referred to below as surface layer 14) and one or more additional layers of relatively soft metallic material (collectively referred to below as core 16). While both surface layer 14 and core 16 are constructed of metal and are therefore nominally “hard,” unlike core 16, surface layer 14 may undergo a hardening process or be constructed by coating with a harder metal. In any embodiment, as those skilled in the art will understand, the hardness level of surface layer 14 exceeds that of core 16. Due to this surface-core hardness difference, a surface-core boundary 18 exists between surface layer 14 and core 16. The perpendicular distance between a reference surface 11R of surface layer 14 and the surface-core boundary 18 is referred to as the effective surface depth (D). EC In the various surface hardening examples presented in this article, i.e., excluding overcoating or other alternatives, the hardness will decrease with depth until it matches the core hardness.

[0031] In the example implementation, the outer diameter surface 11 serves as the reference surface 11R. However, other implementations with complex external and / or internal surface geometries are conceivable, and therefore, the identity of the reference surface 11R will vary depending on the application or end use. Similarly, although for simplicity and clarity, the surface 14 and core 16 are... Figure 1 The surface 14 is represented as a clearly uniform region spaced apart from each other by the surface-core boundary 18. However, in actual implementations, the hardness level of the surface 14 may gradually decrease until it eventually matches the hardness level of the core 16, as described above. In such implementations, for example, based on the blueprint of the metal assembly 10 or another calibrated reference for a specific assembly / application, the surface-core boundary 18 is a location beneath the surface 11 where the hardness is equal to or below a specified threshold hardness level.

[0032] Hardened metal components (e.g., Figure 1 The effective surface depth (D) of the exemplary metal component 10 depicted in the figure EC This method can be used 100% (see below for reference). Figure 2 The exemplary embodiments described are quickly determined. As a fundamental aspect of method 100, the exposed surface 20 of the metal component 10 is physically finished by using a well-controlled medium blasting or shot peening process. The specific medium used for this preliminary process of physical surface finishing should have a hardness level that effectively matches the hardness level of the surface-core boundary 18, i.e., within the small tolerances shown below.

[0033] By way of example rather than limitation, a threshold hardness level of approximately 50 HRC on the Rockwell hardness C scale (HRC) and a core hardness level of less than approximately 48 HRC for core 16 are used. Figure 3The specific blasting medium or shot peening medium shown as 30 and used for physical surface finishing of the metal assembly 10 should have a hardness level of about 50 HRC, thus matching or equal to the threshold hardness level in this example. However, in exemplary embodiments, a blasting medium 30 with a slightly higher hardness level (such as about 102% to 105% of the hardness level of the surface-core boundary 18, or about 51-52 HRC) may be used, where such a hardness level may reveal the surface-core boundary 18 slightly more effectively than using a blasting medium 30 whose hardness level is precisely matched to the threshold boundary hardness level. In other words, the hardness level of the blasting medium 30 does not need to precisely match the threshold boundary hardness level within the scope of this disclosure, as long as the blasting medium 30 exceeds the hardness level of the core 16 by a certain margin, sufficient to plastically deform the exposed surface of the core 16 without plastically deforming the exposed surface of the surface layer 14.

[0034] Therefore, the exposed surface 20 of the metal component 10 (which may be) Figure 1 The outer surface (or cross-sectional surface in different embodiments) shown is physically trimmed so that the properties of the core 16 (e.g., its surface texture or internal stress) are altered in a detectable manner. By selecting a jet medium 30 whose hardness level sufficiently matches the hardness level of the surface-core boundary 18 or the aforementioned threshold boundary hardness level, the core 16 is plastically deformed to a controlled degree without altering the surface of the surface layer 14. Therefore, the resulting differences in surface texture, internal stress, or other characteristics between the surface layer 14 and the core 16 are readily susceptible to automatic detection, quantification, and interpretation within the scope of this disclosure. Furthermore, this method enables precise determination of the location of the surface-core boundary 18, which can then be used to measure the effective surface depth (D). EC ).

[0035] refer to Figure 2 The implementation of method 100 begins at frame B102 (“physical surface finishing”), wherein the exposed surface 20 of the metal component 10 (see [link to documentation]) is finished. Figure 3 Controlled surface finishing is performed. Box B102 may optionally include a sample preparation step. For example, when it is desired to measure the effective surface depth (D) at the inner surface of the metal assembly 10. EC When doing so, frame B102 may need to cut the metal component 10 (e.g., using a band saw or laser cutting device) so that the exposed surface 20 is the cross-sectional area of ​​the metal component 10. The surface layer 14 and core 16 may already be adequately exposed in other ways, such as by... Figure 1 The exposed end surface will reduce or eliminate the need for cross-sectioning or cutting of the metal component 10.

[0036] Notification box B102 can establish a set of baseline data that correlates a given surface texture feature or other characteristic of the metal component 10 with surface hardness after surface trimming. This data is used by method 100 to ultimately determine the effective surface depth (D). EC The specific material of a given is unique. This non-limiting example of hardness correlation is described in... Figure 5 middle.

[0037] Brief reference Figure 5 The horizontal axis depicts the Rockwell hardness C scale (HRC). The vertical axis depicts non-limiting example features, in this case showing surface texture features in the form of average surface roughness (Ra) in microinches, but in another embodiment, it may manifest as internal compressive residual stress. As shown by a series of data points 55 and the best-fit line 55L, there is a correlation between surface roughness and hardness, where higher surface roughness levels are closely associated with softer materials. Therefore, with Figure 1 Unlike the softer material of the core 16, which is schematically shown in the diagram, the harder material of the surface layer 14 should be highly resistant to plastic deformation during a carefully planned and executed media spraying process. Therefore, as illustrated herein, it is possible to use... Figure 5 The type of correlation indicated in the text helps to set useful reference parameters for executing box B102.

[0038] Brief reference Figure 3 A simplified illustration of a media jetting process 150, which can be used as part of frame B102, is provided. The exposed surface 20 of the metal assembly 10 is positioned relative to the jetting nozzle 22. The jetting nozzle 22 is supplied with air pressure (arrow AA) from a compressor (not shown) and is also supplied with jetting medium 30 (e.g., spherical and / or asymmetric medium), such that the jetting medium 30 is discharged under pressure from one end 24 of the jetting nozzle 22, as indicated by arrow A. When the discharged jetting medium 30 impacts portions of the exposed surface 20 with a surface hardness less than that of the indentation jetting medium 30, the jetting medium 30 will plastically deform those portions of the exposed surface 20 corresponding to the softer core 16, thus forming a trimmed core surface 20-CORE. Surface asperities 25 will be produced that produce the trimmed core surface 20-CORE, wherein such surface asperities 25 are commonly detected as surface texture, roughness, or another detectable feature (such as subsurface / internal stress) over a broad area of ​​the exposed surface 20.

[0039] At the same time, the spray medium 30, due to its construction, will not cause the corresponding harder surface layer 14 (i.e. Figure 3The plastic deformation of the exposed surface 20 (the trimmed surface 20-CASE) shown is partial. Therefore, although the exposed surface 20 is uniformly trimmed overall, the trimmed surface 20-CASE remains unaffected, at least not to a degree considered significant for the purposes of performing this method 100. In other words, a material with a known surface hardness will plastically deform in a detectable and quantifiable manner in response to continuous contact with the harder jetting medium 30. Therefore, the selection and control of the execution... Figure 2 The parameters used in box B102 are used to ensure this result.

[0040] To ensure Figure 1 Core 16 (especially the material of Core 16) in Figure 3 To ensure optimal repeatability and sufficient uniformity of plastic deformation on the exposed surface 20, a set of application-specific surface finishing control parameters is established for a given construction of the metal assembly 10. These parameters may include any or all of the following: the composition, shape, and hardness of the spray medium 30; the nozzle pressure at which this spray medium 30 is discharged toward the exposed surface 20; the projection distance between the nozzle tip 24 and the exposed surface 20; and the percentage of coverage. Since a given batch or supplied spray medium 30 can vary to at least some extent in terms of hardness, size, and shape, the parameters used to select an appropriate spray medium 30 may be average values ​​and / or maximum / minimum ranges.

[0041] By way of example, and not limitation, the metal component 10 may be constructed of carburized steel (e.g., 9310 carburized steel), and the spray medium 30, according to AMS2431 / 6, may be #13 glass beads with a hardness level of 48-52 HRC. In this embodiment, a nozzle pressure of approximately 40 psig at a projection distance of approximately 6 inches and a spray duration sufficient to ensure at least approximately 200% coverage can be used to construct the system. Figure 3 The core surface 20 is repaired. Since the entire exposed surface 20 is repaired using the same media spraying conditions, it should be noted that the surface layer 14 is also exposed, but this exposure does not have a significant deformation effect, because only the softer part of the exposed surface 20 will undergo plastic deformation and / or have compressive stress applied to it.

[0042] As will be understood by those skilled in the art, “coverage” or “coverage percentage” refers to the percentage of surface area affected by indentations, dents, or divots caused by shot blasting, where higher coverage ultimately results in uniform surface depression or dimpling. 100% coverage is defined as uniform depression of the entire surface when viewed with the naked eye (i.e., without device-assisted magnification). When viewed at magnification (e.g., up to 30x), individual un-blasted islands are permissible, provided that such islands are randomly distributed and the width of any individual un-blasted island is smaller than the typical indentation diameter. Coverage greater than 100% is defined as a multiple of the 100% exposure time of the shot blasting treatment; therefore, the representative 200% of this non-limiting example requires twice the time required for sustained media blasting / shot blasting to achieve complete coverage. Approximate vertical blasting angles (e.g., 80-100 degrees) may be used in this particular embodiment. Those skilled in the art will understand that the defined parameters used in block B102 will vary with other implementations; therefore, the above example is merely one possible method for implementing method 100.

[0043] refer to Figure 2 and 4 Once the exposed surface 20 has been physically trimmed, method 100 proceeds to frame B104. Figure 2 Box B104 (“Measuring Surface Texture Features”) includes, for example, using Figure 4 A surface metrology sensor 32, schematically depicted, measures one or more surface texture features or other characteristics of the trimmed core surface 20-CORE. In some embodiments, the surface texture feature may include the surface roughness of the trimmed core surface 20-CORE. In such embodiments, the surface metrology sensor 32 may be embodied as a profilometer 32P. As those skilled in the art will understand, a profilometer 32P is an instrument used to measure surface roughness as a means of determining surface unevenness. In some embodiments, a stylus or other contact gauge may be used to measure surface roughness.

[0044] In other embodiments, block B104 can be implemented using a non-contact profilometer (e.g., a laser profilometer, scanning interferometer, optical surface profilometer, 3D optical microscope, and / or other suitable non-contact profilometer) that emits a beam of light LL of an applicable wavelength or electromagnetic energy range toward the trimmed core surface 20-CORE. In yet another embodiment, Figure 4The surface measurement sensor 32 can also be embodied as a reflectometer 32R, such as radar, lidar, particle beam, ultrasound, or other incident electromagnetic energy beams. In this embodiment, the surface texture feature includes the reflectivity level of the trimmed core surface 20-CORE. Once the measurement of the surface texture feature or other features is completed, method 100 proceeds to... Figure 2 Box B106.

[0045] As described above, other types of surface metrology sensors 32 can be used as possible alternatives to the contact and non-contact profilometer 32P, possessing features other than those for detecting surface texture at the surface-core boundary 18. For example, when this surface 20-CORE is irradiated by an incident X-ray beam or neutron beam in the beam LL embodiment, an X-ray diffractometer 32X can be used to measure internal compressive stress using X-ray diffraction from the trimmed core surface 20-CORE. It will be understood that X-ray diffraction can be used to measure lattice spacing at the atomic level, and therefore can be beneficial when applied to the current problem of quantifying the measurable features of the trimmed core surface 20-CORE. This approach focuses on the internal compression of the subsurface microstructure rather than surface roughness to achieve a similar end effect.

[0046] exist Figure 2 At box B106, method 100 includes outputting and / or recording measured surface texture features (“output STC data”) or another measurement feature as a data file. This data file can be represented in various ways, such as a digital output signal and / or a physical file, for example, printed out or displayed results. Once the STC data has been generated and recorded, method 100 proceeds to box B108.

[0047] Box B108 includes analyzing data files from box B106 (e.g., surface texture feature data (“STC analysis”) or other feature data) to locate the surface-core boundary 18 (see [link]). Figure 1 Box B108 may include identifying the location of a threshold difference or gradient in a surface texture feature or other feature used in a given embodiment, present in a contiguous region of the currently trimmed surface 14 and core 16, wherein the threshold difference indicates the presence of the surface-core boundary 18. Because the physical surface trimming process performed at box B102 is configured not to alter the exposed surface 20-CASE or to plastically deform the exposed surface 20-CASE (see... Figure 3Therefore, the position of the surface-core boundary 18 can be easily detected by detecting the transition from the plastically deformable surface region (or compressive stress) indicating the softer core 16 to the undisturbed or relatively undisturbed surface indicating the harder surface 14. Once the coordinates of the surface-core boundary 18 are known, for example, using calipers, gauges, or optical measuring tools, method 100 proceeds to frame B110.

[0048] Box B110 (“Effective Surface Depth”) includes the effective surface depth (D) EC The measurement is the linear vertical distance between the surface-core boundary 18 and the reference surface 11R of the surface 14. Figure 1 In some implementations, for example, the effective surface depth (D) EC The effective surface depth (D) can be measured as the vertical distance between the outer diameter surface 11 of the surface layer 14 and the surface-core boundary 18, such as by using a similar gauge, caliper, or optical measuring tool as used in frame B108. Once measured, the effective surface depth (D) EC It can be used in countless automated or manual processes, including but not limited to quality assurance and / or end-of-line quality inspection processes.

[0049] Through examples, the effective surface depth (D) is determined according to method 100. EC The metal component 10 itself can represent a specific build quantity or batch. As an example, the manufacturer of the surface-hardened pinion can select a sample pinion from the batch and perform method 100 on the sample pinion to obtain its effective surface depth (D). EC Then, the effective surface depth (D) is measured. EC This is compared to a threshold effective surface depth (e.g., a reference or requirement from blueprints, tables, charts, or other calibrations for a specific component and / or application), where an example of such a threshold effective surface depth is approximately 2 mm. Whenever the effective surface depth (D) is... EC When the effective surface depth is less than the threshold surface depth, quality assurance actions or other control actions can be taken regarding the number of builds or batches. In this particular exemplary instance, in response to the effective surface depth (D) EC For samples smaller than 2mm, appropriate actions may include testing additional sample pinions to reject the number or batch of builds.

[0050] like Figure 4 As schematically shown and as will be understood by those skilled in the art, the various blocks of method 100 can be executed automatically by a host computer device or electronic control unit (ECU) 50 equipped with the necessary hardware and software associated with said block and / or with its assistance. That is, for determining the effective surface depth (D) of the metal component 10... ECSystem 60 may include surface metrology sensors 32 in any or all of the disclosed embodiments above, including but not limited to a profilometer 32P, an X-ray diffractometer 32X, and / or a reflectometer 32R configured to use the aforementioned surface texture features (one or more) to identify the surface-core boundary 18, and one or more ECUs 50. System 60 may also include a contact or optical / non-contact measurement tool (“MSMT tool”) 70 configured to... Figure 1 The effective surface depth (D) in the example EC The measurement is the linear vertical distance between the reference surface 11R of the surface layer 14 and the surface-core boundary 18.

[0051] Figure 4 The ECU 50 can encompass a single, independent, or multiple networked physical computer devices, each having one or more processors (P) and associated non-transitory memory (M), i.e., read-only memory, programmable read-only memory, random access memory, optical or magnetic memory, etc. The non-transitory memory considered herein can be used for software and / or firmware, as well as for host input / output circuitry and for connection to peripheral equipment, including non-contact / optical implementations of surface measurement sensors and surface depth measurement devices. Such ECU 50 may also include necessary signal conditioning and buffering circuitry, as well as other hardware components accessible to provide the functions described in method 100. As part of method 100, electronic control signals (arrow CC) 32 and CC 70 The signals can be sent to and from the metering sensors (one or more) 32 and the measuring tool 70, respectively.

[0052] Those skilled in the art will readily understand the accompanying benefits of the method 100 disclosed herein and its possible hardware implementations. For example, this teaching aims to greatly simplify and accelerate sample preparation and reduce human-to-human or machine-to-machine testing variability typically associated with indentation-based micro-hardness traverse testing systems. Furthermore, uniform surface trimming of the exposed surface (which does not have an equivalent effect on the surface texture of the different trimming materials described herein) ensures that more surface layers can be evaluated relative to existing methods, where the effective surface depth (D) is evaluated. ECThe required consumables are correspondingly reduced, and the time required to collect surface depth data is also reduced. Conventional macro and micro hardness testing processes rely on precise size / depth measurements of indentations at a large number of discrete locations, and therefore depend on the greater plastic deformation of softer materials relative to harder materials. Through feasible extensions of this disclosure, uniform surface trimming of exposed surface 20 results in plastic deformation of a wider area of ​​core 16, so that surface texture or another suitable feature (e.g., surface stress) can be used over a wider area while having the aforementioned incidental benefits. These and other benefits will be readily understood by those skilled in the art in light of the foregoing disclosure.

[0053] Clause 1. A method for determining the effective surface depth of a metal assembly having a relatively hard layer or surface and a relatively soft layer or core, the method comprising physically trimming an exposed surface of the metal assembly to form a trimmed surface, including subjecting a continuous region of the surface and core to a physical surface trimming process; measuring features of the trimmed surface as measurement features using a surface metrology sensor; using the measurement features to locate the surface-core boundary, including identifying locations in the measurement features that indicate the presence of a predetermined difference or gradient at the surface-core boundary on the trimmed surface; and determining the effective surface depth as a measurement depth, including measuring the vertical distance between a reference surface of the surface and the surface-core boundary.

[0054] Clause 2. The method of Clause 1, wherein physical finishing of the exposed surfaces of a metal component includes blasting or shot peening the exposed surfaces using a blasting medium.

[0055] Clause 3.2 The method wherein the metal component is constructed of carburized steel, the hardness level of the blasting medium is in the range of 48 HRC to 52 HRC, and the physical finishing of the exposed surface of the metal component includes blasting or shot peening the exposed surface of the metal component at a pressure of about 40 psig and a coverage level of about 200%, from a projection distance of about 6 inches.

[0056] Clause 4. The method of Clause 2, wherein the measurement features include the measured surface texture or roughness, and wherein the surface metrology sensor includes a profile measuring device.

[0057] Clause 5. The method of Clause 4, wherein the profile measuring device includes a non-contact profile measuring device.

[0058] Clause 6. The method of Clause 5, wherein the non-contact profilometer includes a laser profilometer or a scanning interferometer.

[0059] Clause 7. The method of Clause 5, wherein the non-contact profilometer includes a reflectometer.

[0060] Clause 8. The method of Clause 1, wherein the surface metrology sensor includes an X-ray diffractometer, and wherein the characteristic is the level of internal compressive stress of the metal component.

[0061] Clause 9. The method of Clause 1, wherein the metal component represents the build quantity or batch, the method further includes comparing a measured depth with a predetermined threshold depth; and automatically performing a quality assurance or control action relative to the build quantity or batch when the measured depth is less than the predetermined threshold depth.

[0062] Clause 10. The method of Clause 1 further includes cutting the metal component to form an exposed surface of the metal component such that the exposed surface is a cross-sectional area of ​​the metal component.

[0063] Clause 11. A system for determining the effective surface depth of a metal assembly having a relatively hard layer or surface layer including a reference surface and a relatively soft layer or core, the system comprising a surface metrology sensor configured to measure features of a trimmed core surface of the metal assembly as measurement features, wherein the trimmed core surface is a portion of the exposed surface of the metal assembly after the exposed surface has undergone a uniform physical surface trimming process; an electronic control unit (ECU) in communication with the surface metrology sensor and configured to use the measurement features to identify a surface-core boundary of the exposed surface, wherein the surface-core boundary includes the location of a predetermined difference or gradient in the measurement features present on the exposed surface; and a measuring tool in communication with the ECU, wherein the measuring tool is configured to measure the effective surface depth as the vertical distance between the reference surface of the surface layer and the surface-core boundary.

[0064] Clause 12. The system of Clause 11, wherein the measuring features include the surface roughness or texture of the trimmed core surface, and wherein the surface measurement sensor is a profile measuring device.

[0065] Clause 13. The system of Clause 12, wherein the profile measuring device is a non-contact profile measuring device.

[0066] Clause 14. The system of Clause 13, wherein the non-contact profilometer is a laser profilometer or a scanning interferometer.

[0067] Clause 15. Clause 13's system, wherein the non-contact profilometer is a reflectometer, and wherein the surface texture features include the reflectance level of a uniformly trimmed core surface.

[0068] Clause 16. Clause 11's system, wherein the surface metrology sensor is an X-ray diffractometer, and wherein the measurement characteristics include the measurement level of internal compressive stress.

[0069] Clause 17. A method for determining the effective surface depth of a carburized steel assembly having a surface layer and a core, wherein the surface hardness level of the surface layer is greater than 50 HRC and the core hardness level of the core is less than 48 HRC, the method comprising forming a trimmed core surface by uniformly blasting or shot peening an exposed surface of the carburized steel assembly with a blasting medium having a hardness level in the range of about 50 HRC to 52 HRC, wherein the exposed surface of the carburized steel assembly is a continuous surface of the surface layer and the core; measuring the surface texture of the trimmed core surface using a profilometer; identifying the surface-core boundary using the surface texture, including identifying the location of a predetermined difference or gradient in the surface texture present on the exposed surface, the predetermined difference or gradient indicating the surface-core boundary; and measuring the effective surface depth as a measurement depth, wherein the measurement depth is the perpendicular distance between a reference surface of the surface layer and the surface-core boundary; wherein forming the trimmed core surface comprises blasting or shot peening an exposed surface of the carburized steel assembly with a blasting medium or shot peening at about 40 psig, with a coverage of about 200%.

[0070] Clause 18. The method of Clause 17, wherein the profile measuring device is a non-contact laser profile measuring device or a scanning interferometer.

[0071] Clause 19. The method of Clause 17, wherein the carburized steel component represents a build quantity or batch, further includes comparing a measured depth with a predetermined threshold depth; and automatically performing quality assurance or control actions with respect to the build quantity or batch when the measured depth is less than the predetermined threshold depth.

[0072] The method of Clause 20. Clause 17 further includes cutting the carburized steel component to form an exposed surface such that the exposed surface is a cross-sectional area of ​​the carburized steel component.

[0073] Aspects of this disclosure have been described in detail with reference to exemplary embodiments. However, those skilled in the art will recognize that certain modifications can be made to the disclosed structures and / or methods without departing from the scope of this disclosure. This disclosure is also not limited to the precise construction and composition disclosed herein. Modifications apparent from the foregoing description are within the scope of the disclosure as defined by the appended claims. Moreover, this concept explicitly includes combinations and sub-combinations of the foregoing elements and features.

Claims

1. A method for determining the effective surface depth of a metal assembly having a relatively hard layer or surface layer and a relatively soft layer or core, the method comprising: Physically trimming the exposed surfaces of the metal components to form trimmed surfaces includes subjecting a continuous region of the surface layer and the core to a physical surface trimming process. The characteristics of the trimmed surface are measured using a surface metrology sensor as measurement features; Locating the surface-core boundary using the measurement features includes identifying the location of a predetermined difference or gradient in the measurement features that indicates the presence of the surface-core boundary on the trimmed surface. Determining the effective surface depth as the measurement depth includes measuring the vertical distance between the reference surface of the surface and the surface-core boundary; and The physical finishing of the exposed surface of the metal component includes blasting or shot peening the exposed surface with a blasting medium, wherein the hardness level of the blasting medium is sufficient to cause plastic deformation of the core metal component exposed surface without causing plastic deformation of the surface metal component exposed surface.

2. The method of claim 1, wherein the metal component is constructed of carburized steel, the hardness level of the blasting medium is in the range of 48 HRC to 52 HRC, and the physical finishing of the exposed surface of the metal component comprises blasting or shot peening the exposed surface of the metal component at a pressure of about 40 psig, with a coverage level of about 200%, from a projection distance of about 6 inches.

3. The method of claim 1, wherein the measurement feature includes the measured surface texture or roughness, and wherein the surface measurement sensor includes a profile measuring device.

4. The method of claim 3, wherein the contour measuring device comprises a non-contact contour measuring device.

5. The method according to claim 4, wherein the non-contact profile measuring device comprises a laser profile measuring device or a scanning interferometer.

6. The method of claim 4, wherein the non-contact profilometer comprises a reflectometer.

7. The method of claim 1, wherein the surface metrology sensor comprises an X-ray diffractometer, and wherein the characteristic is the level of internal compressive stress of the metal assembly.

8. The method of claim 1, wherein the metal components represent a build quantity or batch, the method further comprising: The measured depth is compared with a predetermined threshold depth; as well as When the measured depth is less than the predetermined threshold depth, quality assurance or control actions are automatically performed with respect to the number of builds or batches.

9. The method of claim 1, further comprising: The metal component is cut to form the exposed surface of the metal component, such that the exposed surface is a cross-sectional area of ​​the metal component.

10. The method of claim 1, wherein the surface-core boundary has a hardness level, and the hardness level of the sprayed medium adequately matches the hardness level of the surface-core boundary.

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