Patent Application
20130268109
1. Technical Field
Embodiments of the present disclosure relate to three-dimensional (3D) measurement technology, and more particularly to a system and a method for measuring a cutting tool.
2. Description of Related Art
Cutting tools are used to remove materials from workpieces for producing products. Determining whether a cutting tool is qualified or not is often achieved by measuring the cutting tool using rulers or measuring the precision to which the workpieces were cut. The aforementioned measurement methods often involve directing human intervention, which may result in measurement errors. Therefore, an improved measurement system and method is desired.
The present disclosure, including the accompanying drawings, is illustrated by way of examples and not by way of limitation. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one.”
In general, the word “module”, as used herein, refers to logic embodied in hardware or firmware, or to a collection of software instructions, written in a programming language. One or more software instructions in the modules may be embedded in firmware, such as in an erasable programmable read only memory (EPROM). The modules described herein may be implemented as either software and/or hardware modules and may be stored in any type of non-transitory computer-readable medium or other storage device. Some non-limiting examples of non-transitory computer-readable media include CDs, DVDs, BLU-RAY, flash memory, and hard disk drives.
The rotatable holder 4 rotates the cutting tool 3 in preset steps, such as 0.2 millimeters/per step. Every time the rotatable holder 4 stops rotating, the image capturing device 2 captures one or more images of each cutting edge of the cutting tool 3. The X, Y raster rulers measure X, Y coordinate values of pixels in each image, and the Z raster rulers measures a Z coordinate value of each image. The image measurement machine 200 transmits the images and the measurement data in relation to the images, such as the X, Y, and Z coordinate values measured by the X, Y, and Z rulers 5-7, to the computing device 100.
The computing device 100 controls rotation of the rotatable holder 4, determines three-dimensional (3D) contour points of the cutting tool 3 by processing the images and the measurement data in relation to the images, determines differences between the 3D contour points and a reference contour image of the cutting tool 3, and determines whether a design of the cutting tool 3 is qualified according to the differences.
The measurement unit 10 includes a driving module 11, an information reading module 12, an image processing module 13, a difference determination module 14, and a comparison module 15. The modules 11-15 include computerized code in the form of one or more programs (computer-readable program code) that are stored in the storage device 20. The computerized code includes instructions that are executed by the processor 30, to provide the functions of the computing device 100 as described above. A description of functions of the modules 11-14 is given below and with reference to
In step S301, the driving module 11 sends a control command to the image measurement machine 200, and the image measurement machine 200 drives the rotatable holder 4 to rotate the cutting tool 3 according to the control command In one embodiment, the rotatable holder 4 rotates the cutting tool 3 in preset steps, such as 0.2 millimeters/per step. Every time the rotatable holder 4 stops rotating, the image capturing device 2 captures one or more images of each cutting edge of the cutting tool 3. The X, Y raster rulers measure X, Y coordinate values of pixels in each image, and the Z raster ruler measures a Z coordinate value of each image. The image measurement machine 200 transmits the image data, such as the images and the X, Y, Z coordinate values in relation to each image measured by the X, Y, and Z raster rulers 5-7, to the computing device 100.
In step S303, the information reading module 12 receives and stores the image data in the storage device 20.
In step S305, the image processing module 13 determines a set of 3D contour points of the cutting tool 3 according to the image data. For example, the image processing module 13 reads one image M1, determines contour points in the image M1, where the contour points in the image M1 are 2D points with X, Y coordinate values. Further, the image processing module 13 reads the Z coordinate value of the image M1 measured by the Z raster ruler 7, and takes the Z coordinate value of the image M1 as the Z coordinate value of each contour point in the image M1, so as to obtain a portion of 3D contour points of the cutting tool 3. In such a way, all images are processed until all of the 3D contour points (hereinafter, all of the 3D contour points are referred to “a set of 3D contour points”) of the cutting tool 3 are obtained. In addition, the image processing module 13 may further deletes duplicate 3D contour points from the set of 3D contour points.
In step S307, the image processing module 13 reads a reference contour image of the cutting tool 3 from the storage device 20, and aligns the set of 3D contour points with the reference contour image. In one embodiment, the alignment operation is performed according to an algorithm, such as the least square method with the following equation:
where (X1, Y1, Z1) represent contour points in the reference contour image of the cutting tool 3, and (X2, Y2, Z2) represent contour points in the set of 3D contour points. When f(X) has the minimum value, it represents the set of 3D contour points in alignment with the reference contour image. For example, as shown in
In step S309, the difference determination module 14 determines a shortest distance from each 3D contour point to the reference contour image, and determines a deviation value of the cutting tool 3 according to a maximum value and a minimum value of the shortest distances. For example, as shown in
In step S311, the comparison module 15 compares the deviation value of the cutting tool 3 with a allowable tolerance of the cutting tool 3, and determines whether a design of the cutting tool 3 is qualified according to the comparison result. For example, if the deviation value is less than or equal to the allowable tolerance, the design of the cutting tool 3 is qualified. Otherwise, if the deviation value is more than the allowable tolerance, the design of the cutting tool 3 is not qualified.
Although certain disclosed embodiments of the present disclosure have been specifically described, the present disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the present disclosure without departing from the scope and spirit of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201210100800.1 | Apr 2012 | CN | national |
