3D visualization of depositions

Abstract

The invention provides a method for analyzing deposits on a machine component lubricated with a lubricating composition during use of the machine component, the method comprising the steps of: i) using a 3D scanner to create a 3D model of the machine component after use; ii) mounting the machine component on a rotating device; iii) obtaining a digital microscope image of an initial section of the outer surface of the machine component; iv) rotating the machine part about its central axis by a specific amount; v) obtaining a digital microscope image of a further section of the outer surface of the machine component, the further section of the outer surface overlapping the initial section of the outer surface of the machine component; vi) repeating steps iii) to v) until the entire outer surface of the machine part has been imaged; vii) removing overlapping sections of the digital microscope image and creating a single continuous image of the outer surface of the machine component; viii) processing the single continuous image by assigning, to each pixel in the image, a value related to the deposit present in the each pixel and optionally the thickness of the deposit; and (ix) applying the data set obtained in step viii) to the 3D model created in step i) to produce a precise 3D representation for visualization and quantification of the deposit on the machine part.

Description

Technical Field

[0001] The present invention relates to an improved method and system for quantifying and 3D visualizing deposits on used machine parts. Background Art

[0002] A widely used method for determining the quality of one or more lubricant compositions is to perform field trials or bench tests on the machines using the lubricant compositions. After the trials or tests, the machine parts are removed and the cleanliness and deposits are evaluated. For example, after a field trial of an engine, the piston is removed from the engine and the cleanliness is evaluated. During the field trial, coke will form in the combustion chamber of the engine and accumulate on the surface of the piston. Therefore, the deposit structure will accumulate over time. The deposits on the ring lands and in the ring grooves of the piston may increase the friction and wear during the operation of the engine.

[0003] In the case of severe deposits in the ring grooves, the free movement of the piston rings may be impeded. This can lead to higher friction, blow-by or even piston seizure and piston ring breakage. By using a high-quality lubricant composition, the formation of deposits in the combustion chamber can be reduced and existing deposits may even be removed. Therefore, the quality of the lubricant composition used in an engine is closely related to the deposits that accumulate on the piston during engine operation. Therefore, being able to accurately and consistently visualize and measure these deposits is a desirable goal.

[0004] Currently, the established method for evaluating deposits on pistons to evaluate the performance of lubricant compositions is based on an expert rating system. The system involves the disassembly of a test engine and the evaluation of deposits on the piston by an expert. For this evaluation, the top land, the first groove and the second land are usually analyzed (see Figure 1 ). The structure (discoloration) and thickness of the deposit on the piston are assigned a grade. Generally speaking, the thicker and more structured the deposit appears, the worse the grade.

[0005] Although an established rating system that is widely used, the system also has disadvantages such as subjectivity of the rater and the inability to provide a quantifiable physical value for the deposits. In addition, the rating report for piston deposits contains a large amount of cumbersome information. The comparison of lubricant compositions can be complex and may not be understood by a non-expert, such as a customer who wants to choose between two lubricant types. Therefore, it is highly desirable to create a simpler system for evaluating piston deposits with quantifiable results.

[0006] The use of laser scanning to produce 3D models of pistons before and after use in field trials has been reported, for example by the SouthWest Research Institute: www.swri.org / sites / default / files / brochures / precision-analysis.pdfThis 3D model can be used to analyze piston deposits that accumulate during testing and provide comparative results to lubricant developers and customers at the same time. However, this technology itself does not have the resolution required to accurately quantify very fine deposits or small pistons (such as those used in motorcycle engines). For such applications, new methods are needed. Summary of the invention

[0007] The present invention therefore provides a method for analyzing deposits accumulated on a machine part lubricated with a lubricating composition during use of the machine part, the method comprising the following steps:

[0008] i) using a 3D scanner to create a 3D model of the machine component after use;

[0009] ii) mounting the machine component on a rotating device;

[0010] iii) obtaining a digital microscope image of an initial section of the outer surface of the machine component;

[0011] iv) rotating the machine component about its central axis by a specified amount;

[0012] v) obtaining a digital microscope image of another section of the outer surface of the machine component, the another section of the outer surface overlapping the initial section of the outer surface of the machine component;

[0013] vi) repeating steps iii) to v) until the entire outer surface of the machine part has been imaged;

[0014] vii) removing overlapping sections of the digital microscope image and creating a single continuous image of the outer surface of the machine component;

[0015] viii) processing the single continuous image by assigning to each pixel in the image a value related to the deposit present in each pixel and optionally the thickness of the deposit; and

[0016] ix) applying the data set obtained in step viii) to the 3D model created in step i) to produce an accurate 3D representation for visualization and quantification of the deposits on the machine component. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A typical piston is shown with the lands and grooves shown.

[0018] Figure 2 Shown is a 3D model of a piston created using a 3D laser scanner.

[0019] FIG3 shows an apparatus for obtaining digital microscope images.

[0020] Figure 4 An original digital microscope image of a used piston is shown.

[0021] Figure 5 A processed microscope image of a used piston is shown. DETAILED DESCRIPTION

[0022] The inventors have developed a method for accurately visualizing deposits formed on machine parts during their use. The method is particularly useful for the visualization and evaluation of small machine parts and fine deposits. The method of the invention allows the deposits to be evaluated and quantified, thereby allowing the lubricant composition used to lubricate the machine parts to be evaluated. Deposits related to fuel use in an engine can also be evaluated, thereby allowing comparisons between fuel compositions.

[0023] The method is applicable to any machine part used under lubrication. The machine part can be any moving part that operates in the presence of the lubricating composition. The machine part can be from an industrial machine or an engine, including automotive, aviation and marine engines. Of particular relevance to the method of the invention are pistons, especially small pistons, and even pistons from motorcycle engines.

[0024] The first step in the method of the present invention is to create a 3D model of the machine component after use. This can be achieved by scanning the piston before and after field testing using 3D laser or blue light scanning technology. Any suitable 3D scanning technology is suitable for the method of the present invention. Those skilled in the art will readily appreciate that a finer wavelength source will be required for smaller machine components in order to accurately image small grooves, or for finer deposits.

[0025] Appropriately, before scanning the machine parts, these parts can be sprayed with a coating to prevent reflections which could distort the recording of the image. For alignment, it is useful to place measuring points as reference positions on the surface of the machine part. Scanners are usually calibrated using a calibration plate.

[0026] Typically, the entire machine component can be scanned at a coarse initial resolution. A second scan is then performed at a higher resolution to obtain a more accurate image of finer details, such as piston grooves and lands in the case where the machine component is a piston. After recording the scanned images, unnecessary information is deleted and the measurement sequence is polygonized. The resulting data for each machine component is then computationally analyzed before and after field testing in order to create a virtual 3D model of the machine component after use.

[0027] The machine component is then mounted on a rotating device that allows it to be rotated about its central axis and digital images of each section of the outer surface of the machine component are collected using a high-resolution digital microscope. The resolution of the microscope to be used and the resolution of the images to be taken will be easily determined based on the size of the machine component, the field of view of each image and the size or fineness of the deposits to be visualized and / or quantified. In addition, the shape of the machine component will also be relevant in determining how many images are needed to accurately assess the entire surface area of ​​the machine component and therefore the resolution to be used. Depending on these factors, a "4K" high-resolution microscope may be appropriate, but lower resolution microscopes may also be used.

[0028] In order to collect a complete digital image of the entire circumference of the outer surface of the machine component, it is necessary to obtain an image of an initial section before rotating the machine component by a controlled amount, and then obtain images of further slightly overlapping sections. This process is then repeated several times until the entire outer surface of the machine component has been imaged.

[0029] The number of sections required will depend on the size of the machine part, the size of the deposit and the resolution of the captured microscope images. For example, for a car or motorcycle piston, at least 10 images may be collected, preferably at least 15 images, and suitably about 20 images. Obviously, any number of overlapping images may be collected, but for a car or motorcycle piston, suitably no more than 40 images, preferably no more than 30 images are collected. It will be readily appreciated that for larger machine parts, a larger number of images may be required.

[0030] The controlled amount of rotation of the machine part will be determined by the number of images required to produce a complete image of the outer surface of the machine part. For example, if 20 images are required, a rotation of about 18° between the centers of each image is appropriate.

[0031] Each digital image is collected in a manner that the deposit remains focused and there is a small overlap between the continuous images. The image must then be processed so that a series of images are merged in a manner that removes the overlapping areas between the images. It may be most effective to perform image registration only on a portion of the image of the machine component. For example, in an embodiment where the machine component is a piston, the image portion covering a single ring bank can be used to match the deposition pattern between the continuous images. This information can then be used to determine how many rows of pixels need to be removed from one end of the entire image. Most simply, the image registration process can be completed using an algorithm on a computer and applied to each pair of continuous images. The images are then combined to produce a single image of the entire surface area of ​​the machine component.

[0032] This image is then analyzed to identify the sediment. This can be done by assigning a value to each pixel in the image. Classical image processing algorithms can be applied to assign a value to each pixel based on its color. Alternatively, a small number of pixels can be manually labeled and a machine learning algorithm used to assign a value to each pixel.

[0033] Suitably, sediment may be identified by assigning to each pixel a value of "contains a lot of sediment" or "contains little sediment". Alternatively, each pixel may be assigned a value based on the amount of sediment, with a range of values ​​being given depending on the amount of sediment present. The assignment may be made with reference to the colour of each pixel.

[0034] The data set obtained in step viii) is then applied to the 3D model. The resulting 3D representation of the used machine part provides an accurate representation of the deposit on the used machine part. This representation can then be used to evaluate the effect of a particular lubricant composition and / or demonstrate the effect to a customer. If a range of values ​​are assigned to the thickness of the deposit in step viii), the deposit can be accurately quantitatively assessed, thereby avoiding any subjectivity in assessing deposit formation.

[0035] Various tools can be created using the 3D representation of the used machine parts. For example, the 3D representation can be visualized in a computer using any standard visualization software installed on the system or viewed via a web browser, on a screen, or within any extended reality system (virtual reality system or augmented reality system). Alternatively, the model can be 3D printed.

[0036] Detailed description of the drawings

[0037] The following drawings and their description are intended to illustrate the method of the invention, rather than to limit the invention.The drawings show an embodiment of the invention in which the machine component is a piston.

[0038] Figure 1 An example of a typical piston is provided. The first ring groove (1), the second ring groove (2), the third ring groove (3), the top ring land (4), the second ring land (5) and the third ring land (6) are clearly shown. The deposits accumulated on each of these ring lands and grooves can be easily evaluated using the method of the present invention.

[0039] In this embodiment of the method of the present invention, a digital 3D model of the piston is made using a blue light scan of the piston before and after use to produce a digital 3D piston model, such as Figure 2 shown.

[0040] The used piston is then mounted on a rotating device and a digital microscope image is obtained. Figures 3a and 3b show different views of a typical rotating device suitable for taking a series of digital microscope images. The base (7) supports an upright member (8). A rotating device (9) (such as a handle or knob) is supported by the upright member (8) and is attached to a holder (10) via the upright member (8). The piston (11) is securely fixed in the holder (10) by an attachment device (12) in such a way that the grooves and lands (1 to 6) are clearly visible. The rotating device is positioned so that the field of view of the digital microscope (13) clearly covers a portion of the surface area of ​​the piston (11) and a first image is taken. In order to capture an image of the entire outer surface of the piston, a series of digital images are taken with the piston rotated a set amount between each image, the rotation being achieved by rotating the rotating device (9) by a preset amount.

[0041] Figure 4 A series of 20 images taken of a used piston are shown. These images are then digitally combined, removing any overlap, to form a single complete image of the entire piston outer surface.

[0042] Figure 5 A digitally processed image is shown where areas with a lot of sediment are colored black, while areas with little sediment are colored gray. This is an example of designating each pixel as "containing a lot of sediment" or "containing little sediment." In an alternative embodiment, each pixel can be assigned a value based on the amount of sediment present, and a grayscale or color based illustration can be created.

[0043] In the method of the present invention, detailed deposit photographs are combined with a 3D model of the piston to provide a tool for evaluating used pistons and thereby a tool for evaluating the effects of lubricant compositions applied in engines.

Claims

1. A method for analyzing deposits on a machine part lubricated with a lubricating composition during use of the machine part, the method comprising the following steps: i) using a 3D scanner to create a 3D model of the machine component after use; ii) mounting the machine component on a rotating device; iii) obtaining a digital microscope image of an initial section of the outer surface of the machine component; iv) rotating the machine component about its central axis by a specified amount; v) obtaining a digital microscope image of a further section of the outer surface of the machine component, the further section of the outer surface overlapping the initial section of the outer surface of the machine component; vi) repeating steps iii) to v) until the entire outer surface of the machine part has been imaged; vii) removing overlapping sections of the digital microscope images and creating a single continuous image of the outer surface of the machine component; viii) processing said single continuous image by assigning to each pixel in said image a value related to the deposit present in said each pixel and optionally the thickness of said deposit; as well as ix) applying the data set obtained in step viii) to said 3D model created in step i) to produce an accurate 3D representation for visualization and quantification of said deposits on said machine component.

2. The method of claim 1, wherein the machine component is a piston for use in an engine.

3. The method of claim 2, wherein the piston is a motorcycle piston.

4. The method according to any one of claims 1 to 3, wherein the total number of digital microscope images obtained is at least 10 and no more than 40.

5. The method according to any one of claims 1 to 4, wherein step viii) is performed using a machine learning algorithm.

6. The method according to any one of claims 1 to 5, wherein the 3D representation is visualized in an extended reality system.

7. Evaluation of a lubricant composition using the method according to any one of claims 1 to 6.

8. Use of the method of claim 2 to assess the composition of fuel used in the engine.

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