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Researchers Submit Patent Application, "Laser Measurement System and Method in a Cnc Machine", for Approval

January 30, 2014



By a News Reporter-Staff News Editor at Computer Weekly News -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Zebe, Gerhard (Zhuhai, CN); Li, Zhuo (Shanghai, CN), filed on June 27, 2013, was made available online on January 16, 2014.

The patent's assignee is Flextronics AP, LLC.

News editors obtained the following quote from the background information supplied by the inventors: "A CNC machine is a computer numerical controlled machine tool. The CNC machine is used to process a material or a part known as 'the work.' The CNC machine comprises a translation stage to which the work is fixed. The translation stage is translatable along an X-axis and a Y-axis. Typically, the X- and Y-axes define a substantially horizontal plane, but other translation orientations are possible. The CNC machine further comprises at least one tool mount that is independent of the translation stage to which the work is fixed. The tool mount is translatable along the X, Y, and Z axes and can be translated in conjunction with, or independent from, the translation stage.

"Before the work can be processed by the CNC machine, a detailed lateral measurement of the work must be made and entered into the CNC machine. In the prior art, measurement is performed using a mechanical gauge. The measurement typically comprises about 100 data points and takes almost one minute. By comparison, the actual processing of the work, after the measurement, takes only about 15 seconds. If the CNC machine translation stage does not comprise a mounting system that inherently squares up the work to the translation stage, it is desirable to account for skew in the mounting of the work with respect to the coordinate system of the CNC machine so that the work is accurately processed. Manually accounting for skew in the mounting of the work to the translation stage takes additional time in measurement and entry of skew data into the CNC machine.

"Current methods of performing a lateral measurement of the work are slow, yield a small number of data points, and are not easily integrated into the CNC machine."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "To ensure that a work is processed correctly, its dimensions must be accurately measured. Among other things, these measured dimensions indicate whether the unprocessed work meets product specifications and ensures that the work is machined at the correct locations. Preferably, the dimensions are measured optically, using a laser beam, though, in accordance with the principles of the invention, sonic or other measurement techniques can also be used.

"In one embodiment, a time-of-flight laser scanner is coupled to an XYZ-translatable tool mount of a CNC machine. The work is fixed to an XY translation stage of the CNC machine. The work is surrounded by reflectors, such as mirrors or prisms, fixed to the XY translation stage. Alternatively, the laser scanner incorporates a reflector mounted at the output of the laser scanner. The CNC machine moves the tool mount, and thus the laser scanner, to a predetermined XYZ coordinate above the XY translation stage. A beam of the laser scanner is directed toward the XY translation stage at a predetermined angle with respect to the XY plane defined by the translation stage. Preferably, the beam is directed along the Z axis, perpendicular to the XY plane, such that the predetermined angle is 90.degree. with respect to the XY plane. The beam is directed onto a reflector mounted along an edge of the work such that the beam is reflected by the reflector, onto the edge of the work, reflected back by the edge of the work, to the reflector, and to a detector within the laser scanner. Alternatively, the beam is reflected by a reflector coupled to the output of the laser scanner that directs the beam onto the edge of the work. The laser scanner measures the distance from the laser scanner to the edge of the work. The distance is correlated with the predetermined XYZ coordinate of the laser scanner to produce an XY coordinate of a point on an edge of the work. The laser scanner is then translated along an axis that is parallel to the reflector and more data points are collected. Each reflector is similarly scanned, thereby producing a lateral measurement of the work. In accordance with the presently-claimed invention, a complete scan is able to be performed in only a few seconds, producing over 1,000 data points, thereby increasing both the speed and accuracy of the lateral measurement of the work over the prior art.

"The CNC machine comprises a control system having a processor, a computer-readable storage medium, read/write memory, a user interface, a network interface, other I/O, and auxiliary I/O. Auxiliary I/O comprises analog and digital inputs and outputs. The processor and/or the auxiliary I/O can further comprise a PWM generation module, interrupt controllers, a digital signal processing module, counters, and other I/O's known in the art of embedded systems design. The CNC machine control software comprises one or more programs that integrate the above-described measurement system with the CNC machine.

"In a first aspect, a method of performing a lateral measurement of a work having a plurality of reflective edges is performed on a machine with the work in a fixed position relative to the machine and the machine comprising a laser scanner coupled to an XYZ translation stage, and the laser scanner initially positioned at a predetermined XYZ coordinate relative to the work. The method comprises positioning, by the XYZ translation stage, the laser scanner to a next XYZ coordinate (the first time this is done, the 'next' XYZ coordinate are the initial XYZ coordinates), reading, by the laser scanner, a distance from the laser scanner to a point of reflection on a first reflective edge of the plurality of reflective edges of the work, using a beam emitted by the laser scanner, determining an XY coordinate of the point of reflection, and repeating these steps to determine XY coordinates of additional points on the reflective edges of the work until a complete lateral measurement of the work has been performed. Performing a lateral measurement preferably comprises determining an XY coordinate of a point of reflection at a plurality of points on each of the plurality of reflective edges. In one embodiment, a complete lateral measurement occurs when measurements at discrete distances along the entire periphery of the work (e.g., along each edge) have been taken. In a preferred embodiment, the work is substantially rectangular and the work is oriented substantially in alignment with the XY plane of the XYZ translation stage such that repositioning the laser scanner comprises incrementing the position of the laser scanner along one of the X and Y axes. The method preferably also comprises storing the XY coordinate. When no reflection is received in response to the beam emitted by the laser scanner, an invalid coordinate is stored. In a preferred embodiment, the method further comprises determining an identifier for the work. Preferably the identifier for the work is scanned using the laser scanner. From the identifier, a predetermined set of ideal coordinates associated with the identifier can be retrieved. The method preferably further comprises comparing the stored coordinates to the predetermined set of ideal coordinates. In such embodiments, the machine further comprises a notification system, and the method further comprises issuing a notification that one of: the stored coordinates substantially match and do not substantially match, the predetermined set of ideal coordinates.

"In a second aspect, a system for performing a lateral measurement of a work having a plurality of reflective edges, comprises an XYZ translation stage, a laser scanner coupled to the XYZ translation stage, a platen configured to receive the work in a fixed position relative to the XYZ translation stage, and a controller. The controller is configured to position the XYZ translation stage at a predetermined next XYZ coordinate relative to the work, control the laser scanner to read the distance to a point of reflection on a first reflective edge of the plurality of reflective edges of the work, using a beam emitted by the laser scanner, determine an XY coordinate of the point of reflection, and repeat these steps to determine XY coordinates for additional points on the reflective edges of the work until a complete lateral measurement of the work has been performed. In some embodiments, the platen comprises a plurality of reflectors configured to reflect the beam onto a point on each of the plurality of reflective edges of the work. Preferably the work is substantially rectangular and the reflectors are disposed parallel to the reflective edges of the work. In a preferred embodiment, the laser scanner comprises a reflector configured to reflect the beam onto a point on a reflective edge of the work. In such embodiments, the XYZ translation stage is configured to rotate the laser scanner on a Z axis, perpendicular to a top surface of the platen. In a preferred embodiment, the controller is configured to reposition the XYZ translation stage to a second predetermined XYZ coordinate that is on a line through the first predetermined XYZ coordinate and parallel to one of the plurality of the reflective edges. In some embodiments, the controller is configured to reposition the XYZ translate stage to a second predetermined XYZ coordinate that is on line defined by an axis of one of the plurality of reflectors.

"In a third aspect, a non-transitory computer readable medium is programmed with processor-executable instructions that, when executed, perform any of the above methods.

BRIEF DESCRIPTION OF THE DRAWINGS

"In the detailed description of the drawings that follows, the embodiments described are intended to illustrate features of the presently claimed invention. Similar labels refer to similar or identical elements.

"FIG. 1 is illustrates a system for laser measurement according to some embodiments.

"FIG. 2A illustrates a partial side cross-sectional view of a system for performing lateral measurement of a work according to some embodiments.

"FIG. 2B illustrates a partial side cross-sectional view of a system for performing lateral measurement of a work according to some embodiments.

"FIG. 3A illustrates lateral measurement of a work having a rounded corner according to system embodiments.

"FIG. 3B illustrates lateral measurement of a work having an offset according to some embodiments.

"FIG. 4A illustrates a measurement grid for performing a lateral measurement of a work according to some embodiments.

"FIG. 4B illustrates a side cross-sectional view of the measurement grid of FIG. 4A.

"FIG. 5 illustrates the steps of a method of lateral measurement of a work according to some embodiments.

"FIG. 6 illustrates the steps of a method of identifying a work for performing a lateral measurement according to some embodiments."

For additional information on this patent application, see: Zebe, Gerhard; Li, Zhuo. Laser Measurement System and Method in a Cnc Machine. Filed June 27, 2013 and posted January 16, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3711&p=75&f=G&l=50&d=PG01&S1=20140109.PD.&OS=PD/20140109&RS=PD/20140109

Keywords for this news article include: Flextronics AP LLC.

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Source: Computer Weekly News


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