Patent Application
20180246034
During a combustion cycle of an internal combustion engine (ICE), air/fuel mixtures are provided to cylinders within an engine block of the ICE. The air/fuel mixtures are compressed and/or ignited and combusted to provide output torque via pistons positioned within the cylinders. As the pistons move within the cylinders, friction between the piston and cylinder and the presence of fuel can wear and degrade the cylinder surfaces. Additionally, combustion pressure and piston side loading can pose significant amount of stresses on the cylinder bores.
Historically. ICEs have employed cylinder liners to prevent wear or damage to the engine block. Cylinder liners can comprise thermal spray compositions, such as those comprising steel. Thermal spraying is a coating process which applies a material to a substrate by heating and optionally melting the material via combustion or an electrical plasma or arc, for example. The process is capable of rapidly applying a relatively thick coating over a large area relative to other coating processes such as electroplating, sputtering and physical and vapor deposition.
Applying a thermal spray composition to a cylinder bore requires a sufficient bore surface roughness to ensure proper adhesion between the thermal spray and the cylinder bore surface. Characterizing cylinder bore surface roughness, particularly in manufacturing environments, remains a challenge.
According to an aspect of an exemplary embodiment, a method for profiling an engine block bore surface during manufacturing is provided. The method includes profiling the bore surface with a qualitative optical device (QlOD) to determine a qualitative surface characteristic map of the bore surface, and comparing the qualitative surface characteristic map to a calibration value to determine the suitability of the bore surface for thermal spray deposition. The QlOD can include a light source configured to emit light toward the bore surface at an emitting angle, and a sensor array configured to sense scattered light reflected from the bore surface. The light source can be configured to emit light towards the bore surface at an emitting angle of between about 45 degrees to about 5 degrees. Scattered light can include light reflected from the bore surface at a scattering angle which is at least about 5 degrees greater than the emitting angle.
According to an aspect of an exemplary embodiment, a method for profiling a bore of an engine block is provided. The method can include profiling a first sample area of the bore surface with a quantitative optical device (QnOD) to determine a quantitative surface characteristic of the first sample area, profiling the first sample area with a qualitative optical device (QlOD) to determine a qualitative surface characteristic of the first sample area, comparing the quantitative surface characteristic of the first sample area with the qualitative surface characteristic of the first sample area to determine a quantitative-qualitative correlation, profiling one or more additional sample areas of the bore surface with the QlOD to determine a qualitative surface characteristic map of the bore surface, and applying the quantitative-qualitative correlation to the qualitative surface characteristic map of the bore surface to determine the suitability of the bore surface for thermal spray deposition. The QlOD can include a light source configured to emit light toward the bore surface at an emitting angle, and a sensor array configured to sense scattered light reflected from the bore surface. The sensor array of the QlOD can be capable of sensing specularly reflected light and scattered light. The qualitative surface characteristic map can include one or more qualitative surface roughness assessments, wherein each assessment is associated with a location relative to the bore surface. The light source can be configured to emit light towards the bore surface at an emitting angle of between about 15 degrees to about 5 degrees. The QnOD can be a stylus profilometer, an optical interferometer, a confocal microscope, or a structured light source (SLS) 3D camera. The first sample area can include a diameter of less than about 10 millimeters. The method can further include profiling a second sample area of the bore surface with the QnOD to determine a quantitative surface characteristic of the second sample area and profiling the second sample area with the QlOD to determine a qualitative surface characteristic of the second sample area subsequent to comparing. Comparing can further include comparing the quantitative surface characteristic of the first sample area with the qualitative surface characteristic of the first sample area and comparing the quantitative surface characteristic of the second sample area with the qualitative surface characteristic of the second sample area to determine a quantitative-qualitative correlation model.
According to an aspect of an exemplary embodiment, an apparatus for profiling the bore of an engine block is provided. The apparatus can include a body and a quantitative optical device (QnOD) and a plurality of qualitative optical devices (QlODs) disposed thereon, wherein each of the QlODs comprises a light source configured to emit light radially outward from the body and toward the bore surface at an emitting angle, and a sensor array configured to sense scattered light reflected from the bore surface. The apparatus can include a positioning element capable of adjusting the position of the measurement device within the engine block bore relative to an axial height of the bore. The apparatus can include a spacing angle of at least 90 degrees between adjacent QlODs. The QnOD can include a stylus profilometer, an optical interferometer, a confocal microscope, or a structured light source (SLS) 3D camera. The apparatus can further include a plurality of shrouds extending radially outward from the apparatus between adjacent QlODs.
Although many of the embodiments herein describe method and apparatus for profiling the surface of an engine block bore surface, particularly for use during manufacturing, the methods and apparatus provided herein are generally suitable for profiling other surfaces, and for applications beyond manufacturing. Other objects, advantages and novel features of the exemplary embodiments will become more apparent from the following detailed description of exemplary embodiments and the accompanying drawings.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
This disclosure provides method and apparatus for profiling the bore surface of an engine block. In particular, the methods and apparatus disclosed herein are suitably utilized for profiling the bore surface of an engine block during manufacture, and prior to the deposition of thermal spray coatings to one or more of the bore surfaces. It has been determined that high surface roughness facilitates proper adhesion of a thermal spray to a bore surface, as evidenced by, for example, increased bond strength between the thermal spray coating and the bore surface, and reduced or eliminated delamination and/or cracking of the thermal spray coating. Profiling the bore surface prior to thermal spraying allows for the surface roughness, and accordingly subsequent bond strength, ruggedness, and durability of the coating, to be assessed. Surface texture or roughness can be defined by parameters such as average two dimensional roughness (Ra), average three dimensional roughness (Sa) and developed interfacial area ratio (Sdr), among others. Sa can be calculated using Equation (1):
Sa=∫∫
a
Z|(x,y)|dxdy (1)
Sdr, expressed as a percentage can be calculated using Equation (2) below:
Increasing Sdr can relate linearly to increasing thermal spray adhesion strength, in some instances, wherein x, y, and z are measurements in the three orthogonal axes. It should be understood that both of these measurements are three dimensional and that the surface texture, such as textures represented by Sdr and Sa, may be thought of or considered as a fractal, that is, a surface having a never ending pattern that is self-similar at different scales. Such surface texture is believed to enhance adhesion of the thermal spray coating by providing connections between the textured surface of the substrate and the thermal spray coating at multiple dimensional sizes or scales from sub-microscopic to microscopic. For example, in one embodiment, a suitable Ra of an engine block bore can be between about 4 μm to about 25 μm. In another example, in one embodiment, a suitable Sdr of an engine block bore can be above about 100%. In another example, in one embodiment, a suitable Sa of an engine block bore can be between about 7 μm to about 18 μm, or about 9 μm to about 15 μm.
It has been determined that a surface roughness can be determined, and/or expediently profiled via qualitative profiling methods in order to determine the suitability of a surface for thermal spray deposition. Qualitative surface profiling methods and apparatus disclosed herein advantageously apply the correlation between surface roughness, thermal spray coating-bore surface bond strength and qualitative optical scattering effects to provide accurate and quick characterization methods for manufacturing applications, among others. Particularly, the methods and apparatus herein can quickly characterize the surface roughness of aluminum engine block bore surfaces and relate the same to potential bond strength between a bore surface and a thermal spray coating. In one embodiment, Sdr can be directly correlated to bond strength.
The thermal spray coating may be a steel alloy, another metal or alloy, a ceramic, or any other thermal spray material suited for the service conditions of the product (e.g., an engine block cylinder liner) and may be applied by any one of the numerous thermal spray processes such as plasma, detonation, wire arc, flame or HVOF suited to the substrate and material applied. In some embodiments, the engine block and/or bore surface comprise aluminum.
The QlOD 300 can further comprise a sensor array 320 configured to sense scattered light reflected from the bore surface 115. A smooth bore surface 115 will reflect light at an angle identical to or similar to the emitting angle 315, whereas a rough bore surface 115 (e.g., a surface with localized non-uniformities) will reflect light at an angle which deviates from the emitting angle 315. Sensor array 320 is configured to sense specularly reflected light 322 which is reflected from the bore surface 115 at a specular reflection angle 323 within about 3 degrees, within about 2 degrees, or within about 1 degree of the emitting angle 315. In some embodiments, sensor array 320 is configured to sense specularly reflected light 322 reflected from the bore surface 115 at about the emitting angle 315. Sensor array 320 is further configured to sense scattered light 326 which is reflected from the bore surface 115 at a scattering angle 327 which is at least about 5 degrees, at least about 7.5 degrees, or at least about 10 degrees greater than the emitting angle 315. In some embodiments, scattered light 326 includes light which is reflected from the bore surface 115 at a scattering angle 327 that deviates from the emitting angle 315 by at least about 5 degrees, at least about 7.5 degrees, or at least about 10 degrees. In some embodiments, sensor array 320 is further configured to sense scattered light 326 which is reflected from the bore surface 115 at a scattering angle 327 which deviates from the emitting angle 315 by at least about 5 degrees, at least about 7.5 degrees, or at least about 10. Sensor array 320 can comprise a single sensor, or a plurality of sensors, such as specular sensor 321 and scattering sensor 325. In some embodiments, sensor array 320 can comprise a plurality of specular sensors 321 and/or a plurality of scattering sensors 325. Sensor array 320 can utilize the one or more sensors to qualitatively assess the roughness of the bore surface 115 at a given sample area (i.e., the location at which the emitted light is focused on the bore surface 115). A sample area can be 7.5 mm to about 2.5 mm in diameter, in some embodiments. In one embodiment, the sample area can be about 5 mm in diameter. In some embodiments, a sample area can be less than about 10 mm, less than about 7.5 mm, less than about 5 mm, or less than about 2.5 mm in diameter.
The QlOD can profile the roughness of the bore surface 115 at a plurality of sample areas to create a qualitative surface characteristic map of the bore surface 115. A qualitative surface characteristic map comprises one or more qualitative surface roughness assessments, wherein each assessment is associated with a location relative to the bore surface 115. For example, a qualitative surface characteristic map can comprise a vector field. Accordingly, a surface characteristic map can be created for a portion of the bore surface 115 or the entire bore surface 115. In some embodiments, method 200 comprises profiling the roughness of the bore surface 115 at a plurality of sample areas simultaneously, utilizing a plurality of QlODs 300. Such methods can employ apparatus comprising a plurality of QlODs 300, such as apparatus 400 described below.
The qualitative assessment cannot define a particular quantitative feature of the bore surface 115 (e.g., average peak height). Accordingly, method 200 further comprises comparing 220 the amount of scattered light 26 detected to calibration value to determine the suitability of the bore surface 115 for thermal spray bonding. The calibration value can comprises a minimum light intensity value detected by the scattering sensor 325, wherein an increasing light intensity value relative to the calibration value indicates an increasing suitability of the bore surface 115 for thermal spray bonding. The calibration value can comprises a maximum light intensity value detected by the specular sensor 321, wherein a decreasing light intensity value relative to the calibration value indicates an increasing suitability of the bore surface 115 for thermal spray bonding. The calibration value can comprise a reflectivity curve wherein a particular quantitative surface characteristic (e.g., Sdr) or the suitability of the bore surface 115 for thermal spray bonding is defined as a function of a qualitative surface characteristic (e.g., scattered light 326 intensity detected by the scattering sensor 325.) Method 200 can be implemented during manufacturing, and allows for a bore surface 115 to be quickly assessed before thermal spray coating.
In some embodiments, apparatus 400 further comprises a quantitative optical device (QnOD) 450. A QnOD 450 includes devices capable of measuring a quantitative characteristic of a surface, or providing data relating to 3-dimensional topography of a surface. A quantitative characteristic can include numerical values relating to surface qualities, such as those defined by ISO 13565-2, including reduced peak height (Spk), core roughness depth (Sk), reduced valley depth (Svk), two dimensional roughness (Ra), average three dimensional roughness (Sa) and developed interfacial area ratio (Sdr), upper limit of the core roughness (MR1), and lowest limit of the core roughness (MR2). QnODs 450 can include contact and non-contact (e.g., optical) type devices. One example of a contact QnOD 450 is a stylus profilometer, which moves a stylus or chisel disposed on a moveable arm across a sample surface. Movement of the stylus relative to the surface is translated into quantitative measurements of the latter. One example of a non-contact QnOD 450 is an optical interferometer, such as a two-beam interferometer. One example of a non-contact QnOD 450 is a confocal microscope. One example of a non-contact QnOD 450 is a structured light source (SLS) 3D camera. One of skill in the art will recognize that other QnODs not expressly disclosed herein can be suitably utilized pursuant to this disclosure.
While QnODs can provide quantitative surface profile characteristics of high precision (e.g., nanometers), such devices can be time consuming and unsuitable for use on a manufacturing scale. Accordingly,
In some embodiments, method 500 further comprises profiling a second sample area of the bore surface 115 with the QnOD to determine a quantitative surface characteristic of the second sample area and profiling the second sample area with the QlOD to determine a qualitative surface characteristic of the second sample area subsequent to comparing 530. In such an embodiment, comparing accordingly comprises comparing the quantitative surface characteristic of the first sample area with the qualitative surface characteristic of the first sample area and comparing the quantitative surface characteristic of the second sample area with the qualitative surface characteristic of the second sample area to determine a quantitative-qualitative correlation model. In some embodiments, the QlOD and the QnOD utilized by method 500 can be combined in a single device, such as apparatus 400. Method 500 can further utilize a plurality of QlODs, and no two qualitative surface characteristics need be measured by the same QlOD.
A reflectometer was used to measure reflected light from a bore surface having a rough surface (having a Sdr of greater than 50%) and a smooth surface (having a Sdr of less than about 20%). The reflectometer included a red laser light source and a specular receiver configured to detect specularly reflected light within +/−2 degrees of the angle of incidence of the laser and the bore surface. The reflectometer also included a scattered receiver configured to detect scattered light reflected from the bore surface at an angle of about 5-10 degrees greater than the angle of incidence of the laser and the bore surface. The bore surface was measured using the reflectometer, and specularly reflected signal strength relative to bore position from deck face is illustrated in
A thermal spray comprising one or more alloy steels (e.g., 110, 5130M, and 1080) was applied to the bore surface and removed using a scratch test to measure a minimum failure load in order to determine bond strength of the thermal spray.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.
