JP4434903B2 - Wire saw inspection method, wire saw inspection device, and cutting device - Google Patents

Description

  The present invention relates to a wire saw inspection method and inspection apparatus for inspecting the state of adhesion of abrasive grains on a wire saw surface.

In recent years, fixed-abrasive wire saws have begun to be used in ingot slicing of silicon, glass, magnetic material, crystal, sapphire and the like.
The fixed abrasive wire saw has a structure in which abrasive grains are fixed to a high-strength core wire with a bond material. The main types of bond materials are resin type using photosensitive resin or thermosetting resin, Ni There are electrodeposition type using plating such as, and brazing type using silver brazing.

On the surface of the fixed abrasive wire saw, it is ideal that a certain amount of abrasive grains adheres regularly at substantially equal intervals, but the adhesion state of the abrasive grains may be disturbed due to manufacturing errors. Since the wire saw is manufactured at a high speed, it is difficult to inspect during the manufacturing process, and the inspection of the state of adhesion of the abrasive grains on the surface of the wire saw has been performed visually or by observation with a microscope. However, this method has a problem in terms of productivity because it is difficult to manage the quality of the wire saw at a certain level because the inspection criteria are easily changed by the inspector, and the inspection has a long time.
In order to improve such a situation, an apparatus for inspecting the surface state of a wire saw is disclosed in Patent Document 1.

Japanese Patent No. 3475942

  In this inspection device, at the end of the manufacturing process of a wire saw coated with hard abrasive grains, the entire circumference of the wire saw is slanted so that the difference between the brightness of the coated abrasive grains and the brightness of the bare wire surface background becomes the largest. Apply multiple spot illuminations, and capture a still image of the surface of the wire saw with a plurality of CCD cameras arranged evenly around the entire circumference, and input the signal to the arithmetic unit to continuously determine the number of abrasive grains, the abrasive area, etc. Counting and comparing with a preset threshold value to determine whether the surface state of the wire saw is acceptable or not.

  By using this apparatus, visual inspection after the manufacture of the wire saw is eliminated, the inspection accuracy can be improved and the inspection process can be speeded up, and the coating state of the abrasive grains on the surface of the wire saw is stored for each production lot. It is said that subsequent correction of manufacturing conditions can be facilitated with reference to those.

  However, with this apparatus, the number of abrasive grains on the wire saw surface and the area occupied by the abrasive grains can be inspected, but the interval between the abrasive grains and the amount of protruding abrasive grains cannot be inspected. The cutting performance of a wire saw often depends on the abrasive grain spacing and the amount of protruding grain, but if the abrasive grain spacing and abrasive grain protruding amount cannot be inspected, the cutting performance of the wire saw cannot be kept good. .

In addition, the above inspection device can detect the change in the number of abrasive grains due to the falling off of the abrasive grains to know the wear state of the abrasive grains, but the abrasive grains remain even if they are worn before the abrasive grains fall off. Therefore, it is determined that abrasive grains are present, and it is impossible to know the wear state of the abrasive grains (abrasion wear or uneven wear).
The present invention has been made in view of such circumstances, and it is possible to detect the abrasive interval between the wire saws by detecting the interval between the abrasive grains so that the cutting performance of the wire saw can be kept good. It is an object of the present invention to provide a wire saw inspection method and inspection apparatus that can prevent a reduction in sharpness and stably manufacture a wire saw having high processing performance.

In order to solve the above-described problems, the wire saw inspection method of the present invention is a wire saw inspection method in which abrasive grains are fixed around a core wire by a bonding material. It is characterized by detecting the number, the interval between the abrasive grains, and the protruding amount of the abrasive grains, and inspecting the fixed state of the abrasive grains.
The cutting performance of a wire saw is often influenced by the abrasive grain spacing. However, according to the present invention, since the abrasive grain spacing can be detected, it is possible to prevent the production of a wire saw that causes a problem in the cutting performance. Can improve the quality of the wire saw.
Moreover, since the number of abrasive grains and the amount of protruding abrasive grains can be detected, it is possible not only to detect the falling off of the abrasive grains but also to detect the worn state of the abrasive grains and to prevent the sharpness from being lowered. .

  The number of the abrasive grains, the abrasive grain interval, and the protruding amount of the abrasive grains can be detected by detecting the outline of the wire saw based on the brightness of the projected image of the wire saw and detecting the position of the abrasive grains. it can.

  The protruding amount of the abrasive grains is obtained from the peak value and the bottom value of the contour line obtained by moving average processing the contour data of the wire saw detected based on the brightness of the projected image of the wire saw. By performing the moving average process, the influence of fine irregularities on the surface of the wire saw or irregularities due to fillers can be removed, and the abrasive protrusion amount can be accurately detected.

The wire saw inspection apparatus according to the present invention includes a light source disposed substantially perpendicular to the longitudinal direction of the wire saw, a camera that captures a projection image of the wire saw using light irradiated to the wire saw from the light source, and the image And an arithmetic unit for detecting the quality of the wire saw by detecting at least the number of abrasive grains, the interval between the abrasive grains, and the protruding amount of the abrasive grains.
In this inspection device, the number of abrasive grains, the abrasive grain spacing, the amount of protruding abrasive grains can be detected accurately, and a wire saw with excellent cutting performance can be obtained with an appropriate distribution of abrasive grains, It is possible to realize a wire saw inspection apparatus that can detect a drop of abrasive grains or a worn state to prevent a reduction in sharpness of the wire saw.

  The cutting device of the present invention is characterized by including the above-described wire saw inspection device, and it is possible to set the cutting conditions in accordance with the abrasive state of the abrasive grains detected by the inspection device and to perform cutting. , Cutting efficiency can be increased.

  According to the present invention, the number of abrasive grains and the protruding amount of abrasive grains can be detected, so that not only the falling of abrasive grains can be detected, but also the wear state of abrasive grains can be detected, and the sharpness can be prevented from being lowered. be able to.

Hereinafter, the present invention will be described based on the embodiments.
The wire saw inspection apparatus of the present invention will be described with reference to FIG.
In FIG. 1, a CCD camera 2 is disposed in two axial directions perpendicular to the longitudinal direction of the wire saw 1, and an LED light source 3 is disposed so as to face the CCD camera 2 and sandwich the wire saw 1. A camera power supply 4 is connected to the CCD camera 2, and an LED light source 5 is connected to the LED light source 3. A camera switch 6 is connected to the two camera power sources 4, the camera switch 6 and the two LED light sources 3 are connected to the control device 7, and the control device 7 is connected to the arithmetic device 8. The arithmetic device 8 is connected to a display 9, a keyboard 10, and a mouse 11 as peripheral devices.

  In this inspection apparatus, a still image of the wire saw 1 is taken by the CCD camera 2. At this time, the LED light source 3 irradiates the wire saw 1 with light. Therefore, the CCD camera 2 takes a projected image of the wire saw 1 using the light irradiated on the wire saw 1. The camera switcher 6 switches which of the two CCD cameras 2 is selected, and the controller 7 controls on / off of the camera power supply 4 and LED light source power supply 5 and switching of the camera switcher 6. Is done. The projection image of the wire saw 1 is taken into the arithmetic unit 8, and the data is processed to determine the quality of the wire saw.

A wire saw inspection method using the above inspection apparatus will be described below.
FIG. 2A shows an example of a projected image of the wire saw 1 taken by the CCD camera 2. The wire saw 1 is formed by adhering abrasive grains 23 around a core wire 21 using a bond material. In this inspection method, first, the brightness of an image is obtained by reading the brightness of the image. Pull. The rising part of the curve I is defined as both ends of the wire saw 1, a straight line I is drawn in the longitudinal direction of the wire saw 1 through a point equidistant from the both ends, and the straight line I is set as the center line of the wire saw 1.

Next, the brightness of the outline portion of the wire saw 1 is set, and the curve II which is the outline of the wire saw 1 is drawn by connecting the points of the brightness.
In order to accurately detect the protruding amount of the abrasive grains, it is necessary to remove the influence of fine irregularities on the surface of the wire saw or irregularities due to fillers. Therefore, the process which smoothes the curve II by the moving average process by a filter is given. FIG. 4 shows the procedure of the moving average process. (A) is the curve II which is the outline of the wire saw before an average process, (b) is the curve II after an average process. In (a), F (X1), F (X2), F (X3), F (X4), F (, which are measured values of brightness at measurement points X1, X2, X3, X4, X5, X6, etc. The curve II is represented by the function F (X) by connecting X5), F (X6) and the like.

Based on these measurements,
G (X3) = (F (X1) + F (X2) + F (X3) + F (X4) + F (X5)) / 5
G (X4) = (F (X2) + F (X3) + F (X4) + F (X5) + F (X6)) / 5
G (XN) = (F (XN-2) + F (XN-1) + F (XN) + F (XN + 1) + F (XN + 2)) / 5
A moving average value is obtained, and a function based on this moving average value is defined as G (X) to obtain an averaged contour line.

Next, in order to detect the protrusion amount of the abrasive grains, the peak and bottom of the abrasive grains are detected.
FIG. 5 shows an example of the averaged contour line. The position (X3) at which the differential value (G (X + 1) −G (X)) of the averaged contour line G (X) finally becomes positive is set as the peak start, and the differential value (G (X + 1) is first set. ) -G (X)) is negative (X5) is the peak end. The midpoint between this peak start and peak end is the peak (X4).
The number of abrasive grains can be detected from the number of peaks, and the abrasive grain interval can be detected from the interval between adjacent peaks.

Next, the position (X7) where the differential value (G (X + 1) −G (X)) of G (X), which is the averaged contour line, has finally become negative is set as the bottom start, and the differential value ( The position (X9) where G (X + 1) -G (X)) becomes positive is taken as the bottom end. The midpoint of this bottom start and bottom end is the bottom (X8).
In FIG. 2B, the peak position of the abrasive grains is represented by a straight line II, and the bottom position of the abrasive grains is represented by a straight line III.
By obtaining the difference between the peak value and the bottom value based on the peak value G (X4) at the peak (X4) detected by the above method and the bottom value G (X8) at the bottom (X8), abrasive grains Can be obtained.
The inspection contents will be described below step by step.

Step 1
First, it is determined whether the number of abrasive grains is equal to or greater than a threshold value. FIG. 3 shows an example in which the abrasive grains 23 are fixed, in which five abrasive grains 23 are fixed to the left and right portions in the portion of the length L in the longitudinal direction of the wire saw 1. Those having 5 or more abrasive grains fixed to the portion L are determined as non-defective products. This determination is made for both the left and right sides of the wire saw,
Number of abrasive grains on the left side ≧ 5
Number of abrasive grains on the right side ≧ 5
At this time, it is judged as good and the process proceeds to step 2, and otherwise it is judged as impossible and the number of abrasive grains is displayed in red and the inspection is finished.

Step 2
The deviation of the number of abrasive grains 23 on the right side and the left side is determined. If the ratio between the number of abrasive grains on the left side and the number of abrasive grains on the right side is 0.9 or more, it is determined to be good, and if it is 0.6 or more and less than 0.9, it is determined to be acceptable and the process proceeds to Step 3. That is,
When the number of abrasive grains on the left side ≥ the number of abrasive grains on the right side,
Number of abrasive grains on the right side / number of abrasive grains on the left side ≧ 0.9: good judgment 0.6 ≦ number of abrasive grains on the right side / number of abrasive grains on the left side <0.9: number of abrasive grains on the left side ≦ possible judgment When the number of abrasive grains
Number of abrasive grains on the left side / number of abrasive grains on the right side ≧ 0.9: good judgment 0.6 ≦ number of abrasive grains on the left side / number of abrasive grains on the right side <0.9: acceptable judgment, otherwise it is impossible And the numerical value is displayed in red, and the inspection is terminated.

Step 3
The standard deviation of the abrasive grain interval obtained by detecting the interval of the straight line II in FIG. 2 is determined, and the quality of the dispersed state of the abrasive grains is determined.
The standard deviation of the abrasive grain interval is determined to be good when both the right abrasive grain and the left abrasive grain satisfy the condition for determining good. That is, in FIG. 3, and L _L are collectively abrasive intervals left, when the L _R are collectively abrasive spacing right,
Standard deviation of L _L ≦ 120 μm and standard deviation of L _R ≦ 120 μm
Good and determined, the standard deviation ≦ 200 [mu] m for L _L except the range and standard deviation ≦ 200 [mu] m of L _R, when
At this time, it is determined to be acceptable, and the process proceeds to Step 4. Otherwise, it is determined to be impossible and the numerical value is displayed in red, and the inspection is terminated.
In addition, the numerical value in the above standard deviation can be calculated from the number of pixels in the projection image.

Step 4
The quality determination is performed on the amount of abrasive grain protrusion obtained by detecting the difference between the peak value and the bottom value in FIG. For one abrasive grain, two abrasive grain protrusion amounts are calculated by subtracting the bottom value at both ends of the abrasive grain from the peak value. For the abrasive protrusion amount thus calculated, the average abrasive protrusion amount for all the abrasive grains on the image is obtained, and this average abrasive protrusion amount is 25% or more and 40% or less of the average abrasive grain size. If it is, it will be judged as good. Further, it is determined that the value is 15% or more and less than 25%, or more than 40% and 70% or less. That is,
0.25 ≦ average abrasive grain protrusion amount / average abrasive grain diameter ≦ 0.40: good judgment 0.15 ≦ average abrasive grain protrusion quantity / average abrasive grain diameter <0.25: acceptable judgment 0.40 < Average abrasive grain protrusion / average abrasive grain size ≦ 0.70: Acceptability is determined. Otherwise, it is determined as impossible and the numerical value is displayed in red, and the inspection is terminated.

If it is determined to be good by the above steps, the production of the wire saw is continued as it is. When it is determined to be possible, if the determination of “possible” continues for a preset number of times, an alarm is sounded and measures such as stopping the apparatus are taken. If it is determined that the test is impossible, an alarm is sounded after the inspection is completed, and the apparatus is stopped.
In addition, the numerical value in said description is an example, Comprising: It is not limited to said thing, It can set suitably as needed.

  As the light used for the above measurement, for example, light in the wavelength region of visible light (wavelength 400 nm to 700 nm) can be used. As a light source that can be used for measurement, a fluorescent lamp, a halogen lamp, an LED, or the like can be used.

FIG. 6 shows an example of the configuration of a cutting device using the above-described wire saw inspection device.
In the cutting device 30, the wire saw 1 supplied from the unwinding bobbin 31 is wound around two guide rollers 34 each having a coolant nozzle 33, while the traveling direction and the passing position are changed by the pulley 32. As a result, between the two guide rollers 34, the wire saw 1 is stretched at a plurality of locations at intervals along the longitudinal direction.

  With this configuration, the wire saw 1 swings between the two guide rollers 34, and the workpiece 35 fixed by the block 36 for fixing the workpiece 35 is pressed against the wire saw 1. The workpiece 35 is cut at a plurality of locations.

  After a wire saw inspection device 37 is arranged on the wire saw 1 that has passed through the guide roller 34 and the state of the abrasive grains of the wire saw 1 is inspected, the wire saw 1 is wound by the pulley 32 with its traveling direction and passing position changed. It is wound up and collected by the take-up bobbin 38.

  Since the wire saw 1 is sequentially supplied with new lines from the unwinding bobbin 31 and cuts the material to be cut 35, the wire saw 1 becomes more worn toward the side closer to the winding bobbin 38. In this embodiment, by arranging the wire saw inspection device 37 on the winding bobbin 38 side from the guide roller 34, it is possible to inspect the wear state of the wire saw 1 caused by the cutting of the material to be cut 35. It is possible to prevent sharpness deterioration and disconnection.

  Further, the wear state of the wire saw 1 is affected by the supply speed of the new line from the unwinding bobbin 31, and the wear of the wire saw 1 becomes severe when the supply speed is low. Therefore, by adjusting the supply speed based on the inspection result of the wire saw inspection device 37, it becomes possible to set the cutting condition according to the wear state of the wire saw 1 and to cut, so that the cutting efficiency can be improved. .

  The present invention maintains the cutting performance of the wire saw by detecting the abrasive grain spacing, and can detect the protruding amount of the abrasive grain on the surface of the wire saw, thereby preventing the sharpness of the wire saw from being lowered, and high processing performance. It can be used as a wire saw inspection method and inspection apparatus that makes it possible to stably manufacture a wire saw having

It is a figure which shows an example of the inspection apparatus of the wire saw of this invention. It is a figure which shows an example of the projection image of the wire saw image | photographed with the CCD camera. It is a figure which shows typically a mode that a several wire is fixed to the circumference | surroundings of a core wire, and the wire saw is formed. It is a figure which shows the moving average process of the outline of a wire saw. It is a figure which shows the method of detecting the peak and bottom of an abrasive grain. It is a figure which shows an example of the cutting device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire saw 2 CCD camera 3 LED light source 4 Camera power supply 5 LED light source 6 Camera switcher 7 Control device 8 Arithmetic device 9 Display 10 Keyboard 11 Mouse 21 Core wire 23 Abrasive grain 30 Cutting device 31 Unwinding bobbin 32 Pulley 33 Coolant nozzle 34 Guide roller 35 Material to be cut 36 Block 37 Wire saw inspection device 38 Winding bobbin

Claims (3)

In the method of inspecting a wire saw in which abrasive grains are fixed around a core wire by a bond material, a projected image of the wire saw is photographed, and the outline of the wire saw is detected based on the brightness of the photographed projected image of the wire saw to determine the position of the abrasive grains. It detects,
Obtains the number of abrasive grains from the number of peaks in the contour line obtained by moving average processing contour data of the detected wire saw,
And from the interval between adjacent peaks in the contour line to determine the abrasive interval,
Further, the wire saw inspection method is characterized in that the amount of protrusion of the abrasive grains is obtained from the peak value and the bottom value of the contour line to inspect the fixed state of the abrasive grains . A light source arranged substantially perpendicular to the longitudinal direction of the wire saw;
A camera that shoots a projection image of the wire saw using light irradiated to the wire saw from this light source;
Based on the brightness of the projected image, the contour of the wire saw is detected to detect the position of the abrasive grain, and the number of abrasive grains is obtained from the number of peaks in the contour line obtained by moving average processing of the detected wire saw contour data. ,
And from the interval between adjacent peaks in the contour line to determine the abrasive interval,
Furthermore, the wire saw inspection apparatus provided with the arithmetic unit which calculates | requires the quality of a wire saw by calculating | requiring the protrusion amount of an abrasive grain from the peak value and bottom value of the said outline.   A cutting apparatus comprising the wire saw inspection apparatus according to claim 2.

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