JP4378496B2 - Measuring device for uneven profile on object surface - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an apparatus for measuring an uneven surface profile of an object using a laser beam, which is suitable for inspecting the quality of stamps and embossed characters attached to products such as automobile engines and transmissions and discriminating the type of characters. About.
[0002]
[Prior art]
Car engines and transmissions are stamped with letters and symbols for identifying products by a stamping device. Of course, it is desirable that the clarity or the marking depth of the marking is always constant, but the actual marking quality is subtly affected by the characteristics of the marking device and the surface condition of the product. It is. On the other hand, the stamping quality has a certain standard from the competent authority, and the preservation of Takumoto is also obligatory. Therefore, the automobile company must check whether all the product stamps meet the quality standards, and must manually collect the Takumoto one by one, but the conventional method for checking the stamp quality is stamped. The quality of the stamping quality is determined based on the result of image processing of the grayscale image obtained by capturing the image with a CCD camera with threshold setting.
[0003]
[Problems to be solved by the invention]
However, in the method for confirming the quality of stamping by image processing, the image density and the stamping depth do not always match because of the degree of illumination and reflection on the product, the cast surface condition of the product, surface contamination, etc. However, there are inconveniences such as the fact that a sufficiently cut depth is actually obtained even in a partially cut mark portion, and on the contrary, the mark depth does not reach the standard even in a continuous mark portion on the image. obtain. As described above, there is a problem in checking the quality of engraving by image processing in terms of reliability.
[0004]
The object of the present invention is to directly measure the uneven surface profile of the object surface by applying laser ranging technology, so that various uneven surface profiles such as engraving can be made with high accuracy without being influenced by the apparent state of the object surface. It is to measure.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the uneven surface profile measuring apparatus of the object surface of the present invention is arranged adjacent to the laser beam irradiating means, a laser beam irradiating means for irradiating a laser beam toward the object surface having a concave portion or a convex portion, Laser beam receiving means for receiving a reflected laser beam from the object surface, and a distance from the laser beam irradiation means to the laser beam irradiation point on the object surface based on signals from the laser beam irradiation means and the laser beam receiving means. A first computing means for computing, and the laser beam irradiating means and the laser beam receiving means for scanning the laser beam along the existence area of the concave or convex portion on the surface of the object as an integrated laser beam irradiation / receiving assembly; And a profile of a concave portion or a convex portion on the surface of the object on the basis of a signal from the moving means to be moved relative to the first calculating means and the moving means. And a second calculating means for calculating a Lumpur, the moving means, after the laser beam irradiation light assembly, is rotated in one only shaft around a predetermined rotation stroke, predetermined feeding stroke Is shifted to one side only in the direction of the support shaft, and then is rotated to the other side around the support shaft by a predetermined rotation stroke, and then is shifted to one side in the direction of the support shaft by a predetermined feed stroke. The second calculation means is incorporated with a correction means for canceling and correcting an increase / decrease in the calculation result of the first calculation means accompanying the rotation . As the type of laser beam, an infrared laser is practically convenient, but other types of laser beam can also be used.
[0006]
The concave portion or convex portion of the object surface is typically a stamped or raised character on the product surface, and based on the concave or convex profile of the object surface obtained by the second calculation means, The depth or height quality of the stamp or embossed character can be inspected.
[0007]
It is also possible to determine the type of the stamped or raised character based on the profile of the concave portion or convex portion of the object surface obtained by the second calculating means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an uneven surface profile measuring apparatus for an object surface according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a plate with a mark 2, which is a surface of an engine or transmission case. The part is virtually shown. 3 is a laser laser distance measuring unit in which a laser irradiation unit 3a and a laser light receiving unit 3b are arranged adjacent to each other, 4 is a personal computer, 5 is a monitor, 6 is a sequencer for managing the manufacturing process of the engine and transmission, and 7 is a hard disk. It is.
[0009]
The laser distance measuring unit 3 is configured to be rotatable in the left-right direction by a servo motor or the like (not shown) around a support shaft 8 disposed at a fixed position, and is rotated once in the right or left direction. It is configured to be shifted by a constant pitch in the axial direction of the support shaft every time. Such a shift mechanism can be composed of, for example, an XY table on which the laser distance measuring unit 3 is placed, and other shift mechanisms include a combination of a stepping motor and a rack and pinion mechanism, a servo motor And a screw rod can be easily configured. FIG. 2 shows the movement trajectory of the laser point scanned on the plate by such rotation and shift movement of the laser distance measuring unit 3, for example, the scanning strokes (1) to (5) in the figure. The laser points irradiated from the laser beam irradiation unit 3a move in order. Note that the number of scanning strokes may be increased or decreased according to the type of measurement object, and about 8 scanning strokes are sufficient when the characters or symbols to be engraved are measurement objects.
[0010]
The laser beam irradiated on the plate 1 is reflected on the surface of the plate 1 and captured by the laser beam receiving unit 3b of the laser distance measuring unit 3, and based on the signals from the laser beam irradiating unit 3a and the laser beam receiving unit 3b, The distance from the irradiation unit 3a to the laser beam irradiation point or the laser beam reflection point on the surface of the plate 1 is calculated by the first calculation means inside the laser distance measuring unit 3. Such a laser ranging unit 3 is easily available on the market.
[0011]
The distance measurement data obtained from the laser distance measurement unit 3 is based on the position of the support shaft 8 and is graphed, for example, as shown in FIG. This waveform represents the data obtained by the scanning stroke (2) in FIG. 2, the left to right in the drawing is the scanning direction, and the scale from 0 to 5000 represents the number of irradiation points of the laser beam. The vertical axis in FIG. 2A represents the distance (unit: μm) to the laser beam irradiation point on the surface of the plate 1 with a virtual arc drawn below the surface of the plate 1 centered on the support shaft 8 as a reference line. Yes. However, since it is difficult to perform post-processing with the arc-shaped waveform of FIG. 3A, the waveform is converted as shown in FIG. In FIG. 3B, the reference height of the surface of the plate 1 is set on the horizontal axis, and the distance from the horizontal axis to the upper end of each waveform represents the depth of the marking (unit: μm). Accordingly, FIG. 3B represents the depth of the marking along the scanning stroke (2) of FIG. Specifically, the waveform conversion is performed by an algorithm that cancels and corrects an increase / decrease change in distance measurement data (calculated by a first calculation means (not shown)) accompanying rotation of the laser distance measurement unit 3. That is, the distance to the position directly below the support shaft 8 (near the marking “9”) is the shortest, and the distances to the markings “J” and “3” at both ends are the longest. Thus, the distance measurement data is corrected so as to be constant. When the laser distance measuring unit 3 linearly scans and moves in parallel with the surface of the plate 1, such waveform conversion is unnecessary, and a waveform as shown in FIG. 3B is directly obtained. If necessary, the number of laser beam irradiation points is converted into a distance along the scanning stroke (2) . In addition to the waveform conversion from (A) to (B) in FIG. 3, the convex data on the surface of the plate 1 which is unnecessary in the measurement of the engraving profile may be removed as noise. In FIG. The rising convex waveform C of the material of the plate 1 accompanying the formation of the stamp A) is removed as noise.
[0012]
The marking depth data is measured as described above. FIG. 4 shows the correspondence between the actual marking and the waveform shown in FIG. That is, when the laser point is moved in the order of the markings “3” and “0” by the scanning stroke (3) as shown in FIG. 9A, the depth data of the marking as shown in FIG. 3 is obtained.
[0013]
Next, an actual measurement process by the apparatus will be described with reference to FIG. In step S1, scanning of the laser beam by rotation and shift movement of the ranging unit is started. In step S2, ranging data from the laser ranging unit 3 is stored in the personal computer 4 via the A / D conversion circuit of the personal computer 4. Read into memory. Next, the convex portion of the waveform data as shown in FIG. 3A read into the personal computer 4 is noise-cut at step S3, and the waveform is converted at step S4 as shown in FIG. 3B.
[0014]
Next, a stamped three-dimensional profile is created by the second calculation means (not shown) from the data obtained in the predetermined number of scanning strokes in step S5, and this three-dimensional profile and the hard disk attached to the personal computer 4 are stored in advance. It is compared with standard 3D profile data such as character symbols to determine whether or not the marking depth has reached the standard, and to determine what the characters or symbols represented by the markings on the plate 1 are. Is done. This determination result is collated with the character symbol of the stamp managed by the sequencer in step S7. If the determination result matches the character symbol output by the sequencer, it is determined that the planned product has passed through the stamp measuring device. The product is allowed to pass through the marking measuring device, and if it does not match, it is excluded from the production line on the downstream side of the marking measuring device as a product different from the plan. After step S8, the measurement data is cleared in step S9, the process returns to step S1 again, and the same process is repeated. In creating the three-dimensional profile data, the relational program of step S5 and step S8 is determined so that it is determined that there is an inscription above the threshold value T1 in FIG. 4B and that the reference inscription depth has been reached above the threshold value T2. Configure.
[0015]
As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the measurement of the concave profile of the marking on the product surface, but can be similarly applied to the measurement of the convex profile of various product objects. It can also be applied to profile measurement. Further, as the movement forms for scanning of the laser distance measuring unit 3 is moved form a combination of shift movement and rotation as described above, the irregular region is preferable when extending long straight line.
[0016]
【The invention's effect】
As described above, the present invention measures the concave / convex profile using a laser beam, so that, for example, the depth data of the marking on the product surface or the concave profile can be accurately measured regardless of the apparent surface condition of the product. In addition, it is also possible to store the obtained profile data electronically instead of the stamped copy.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an uneven surface profile measuring apparatus for an object surface according to an embodiment of the present invention.
FIG. 2 is a plan view of a plate with a mark.
FIG. 3A is a waveform diagram of primary data obtained from a laser ranging unit, and FIG. 3B is a waveform diagram obtained by converting the waveform of the primary data.
4A is a plan view of a part of a mark on a plate, and FIG. 4B is a waveform diagram of a concave profile of the mark.
FIG. 5 is a flowchart showing a measurement process of the measurement apparatus of the present invention.
[Explanation of symbols]
1 Plate 2 Marking 3 Laser Ranging Unit 4 Personal Computer 5 Monitor 6 Sequencer 7 Hard Disk 8 Spindle

Claims (3)

A laser beam irradiation means for irradiating a laser beam toward the surface of the object having a concave portion or a convex portion;
A laser beam receiving means that is arranged adjacent to the laser beam irradiation means and receives a reflected laser beam from the object surface;
First calculation means for calculating a distance from the laser beam irradiation means to a laser beam irradiation point on the object surface based on signals from the laser beam irradiation means and the laser beam receiving means;
Moving means for moving the laser beam irradiating means and the laser beam receiving means as an integrated laser beam irradiating and receiving assembly to scan the laser beam along the presence area of the concave or convex portion;
A second computing means for computing a profile of the concave portion or convex portion of the object surface based on the signal from the first computing means and the moving means ;
The moving means rotates the laser beam irradiation / light-receiving assembly to one side around the support shaft by a predetermined rotation stroke, and then shifts to one side in the support shaft direction by a predetermined feed stroke, and then the predetermined movement stroke. Is rotated around the support shaft by the other rotation stroke, and then shifted to one side in the support shaft direction by a predetermined feed stroke.
An uneven surface profile measuring device for an object surface , wherein a correction means for canceling and correcting an increase / decrease in a calculation result of the first calculation means accompanying the rotation is incorporated in the second calculation means . The concave or convex portion on the object surface is an imprinted or raised character, and the depth of the imprinted or raised character is based on the profile of the concave or convex portion on the object surface obtained by the second calculation means. uneven profile measuring apparatus according to claim 1, wherein the object surface, characterized in that so as to inspect of or the height quality. The concave or convex portion on the object surface is an imprinted or raised character, and the type of the imprinted or raised character based on the profile of the concave or convex portion on the object surface obtained by the second computing means The uneven surface profile measuring apparatus for an object surface according to claim 1, wherein:

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