JP2006130636A - Wire saw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire saw, optimizing the number of abrasive grains, the array interval of abrasive grains, and the projecting amount of abrasive grains to improve the cutting performance. <P>SOLUTION: A projected image of the wire saw to which abrasive grains 23 are fixed to the periphery of a core wire 21 by bonding material is photographed, and according to the brightness of the projected image of the photographed wire saw, the contour of the wire saw is detected to detect the number of abrasive grains 23, the interval of the abrasive grains 23 and the projecting amount of abrasive grains 23. The respective values are optimized to manufacture the wire saw. When the wire saw is manufactured by this method, separation of bonding material can be prevented, the abrasive grain holding force is superior, and the cutting performance is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wire saw in which cutting performance is improved by optimizing the number of abrasive grains, the arrangement interval of abrasive grains, and the protruding amount of abrasive grains.

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.
Patent Document 1 discloses a method of manufacturing a wire saw for the purpose of improving the state of fixing the abrasive grains on the surface of the wire saw.

JP 2002-36091 A

  However, this manufacturing method controls the cutting performance of the wire saw by limiting the area occupied by the abrasive grains on the surface of the wire saw, that is, the number of abrasive grains, and optimizes the abrasive grain spacing and the protruding amount of the abrasive grains. I can't. Thus, it is not possible to effectively prevent the abrasive grains from dropping simply by managing the number of abrasive grains.

  The present invention has been made in consideration of such circumstances, and an object thereof is to provide a wire saw with improved cutting performance by optimizing the number of abrasive grains, the spacing between the abrasive grains, and the protruding amount of the abrasive grains. And

  In order to solve the above-mentioned problems, the present invention takes a projected image of a wire saw in which abrasive grains are fixed around a core wire by a bond material, and outlines the wire saw based on the brightness of the photographed projected image of the wire saw. A wire saw manufactured by detecting and controlling the number of abrasive grains, when comparing the number of abrasive grains located on one side of the wire saw with the core wire sandwiched between the number of abrasive grains located on the opposite side And a ratio of the number of abrasive grains on the side with few abrasive grains to the number of abrasive grains on the side with many abrasive grains is 0.6 or more and 1 or less.

  If the ratio of the number of abrasive grains on the side with few abrasive grains to the number of abrasive grains on the side with many abrasive grains is less than 0.6, the eccentricity of the abrasive layer is large, and the work surface of the work material As the accuracy decreases, uneven wear occurs.

When comparing the number of abrasive grains located on one side of the wire saw with the core wire interposed therebetween and the number of abrasive grains located on the opposite side, the location and range are set as follows.
About measurement length, the measurement length of 1.0 mm or more is required. The measurement interval needs to be 30 m or less. Outside this range, the measurement length is too short, or the measurement interval is too long, making it difficult to perform appropriate measurement.

  When the density is controlled as in the case of a spiral structure, it cannot be optimized by limiting the measurement length. In this case, the average value of the measurement results at a plurality of locations is used. Use to evaluate.

The present invention takes a projected image of a wire saw in which abrasive grains are fixed around a core wire by a bond material, detects the outline of the wire saw based on the brightness of the photographed image of the wire saw, and sets the array interval of the abrasive grains. A wire saw manufactured under control, wherein the standard deviation of the arrangement interval of the abrasive grains is 200 μm or less.
When the standard deviation of the array interval of the abrasive grains exceeds 200 μm, the processing surface accuracy of the work material decreases in the area where the abrasive grains are dense, and the bond material comes into contact with the work material in the area where the abrasive grain distance is wide. Peeling of material is likely to occur.

The present invention takes a projected image of a wire saw in which abrasive grains are fixed around a core wire by a bond material, detects the outline of the wire saw based on the brightness of the photographed image of the wire saw, and determines the protrusion amount of the abrasive grains. A wire saw manufactured under control, wherein the protruding amount of abrasive grains is 20% or more and 70% or less of the average grain diameter of the abrasive grains.
When the protruding amount of the abrasive grains is less than 20% of the average grain size of the abrasive grains, the protruding amount is small, so that the processing efficiency is lowered, and the bond material is likely to come into contact with the work material and the bond material is easily peeled off. . On the other hand, when the protruding amount of the abrasive grains exceeds 70% of the average particle diameter of the abrasive grains, the protruding amount is too large and the abrasive grain holding power is lowered, and the abrasive grains easily fall off and the life is shortened.

In the present invention, the bond material is preferably a resin bond. The wire saw is set on the wire guide via a large number of pulleys, and during processing, the contact with the work material is bent and the cutting proceeds. Therefore, the wire saw needs to be deformed flexibly with respect to this bending to absorb the load, and in order for the wire saw to have such flexibility, it is suitable to use a resin bond as a bonding material.
The elastic modulus of the bond material at this time is preferably 2000 MPa or less. When the elastic modulus exceeds 2000 MPa, the flexibility of the wire saw becomes poor, and the resin is peeled off at the contact position with the pulley and the contact portion with the work material, and the ratio of the number of abrasive grains, the abrasive grain spacing, or the abrasive grains Even if the protrusion amount is controlled, the abrasive grains fall off, and the processing efficiency and processing accuracy are lowered.

  According to the present invention, by optimizing the number of abrasive grains, the arrangement interval of abrasive grains, and the protruding amount of abrasive grains, the processing surface accuracy of the work material is improved, the peeling of the bond material is prevented, and the abrasive retention force Thus, it is possible to realize a wire saw with improved cutting performance.

Hereinafter, the present invention will be described based on the embodiments.
In the wire saw according to the embodiment of the present invention, the number of abrasive grains, the arrangement interval of the abrasive grains, and the protruding amount of the abrasive grains are optimized for the abrasive grains to be fixed. The inspection apparatus described below is used. This inspection apparatus 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 judged as good, and if it is 0.6 or more and less than 0.9, it is judged as 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. With respect to the abrasive protrusion amount thus calculated, an 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 it is acceptable if it is 20% 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 0.20 ≦ average abrasive grain protrusion quantity / average abrasive grain diameter <0.25: acceptable judgment 0.40 < Average abrasive grain protrusion amount / average abrasive grain size ≦ 0.70: Acceptable, otherwise judged as impossible, displaying the value in red and terminating the inspection.

  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.

  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.

Below, the manufacturing method of the wire saw which optimized the number of abrasive grains, the arrangement space | interval of an abrasive grain, and the protrusion amount of an abrasive grain is shown.
FIG. 6 illustrates a process of manufacturing a wire saw while controlling the distribution state of the abrasive grains of the wire saw.
The core wire 32 is passed through the bond tank 31 storing the resin mixed with abrasive grains, and the coating thickness of the covered wire 33 that has passed through the bond tank 31 is made uniform by the die 34.
Around the dice 34, as shown in FIG. 6 (b), the dice position control unit is arranged in two axis (X axis, Y axis) directions orthogonal to each other in a plane perpendicular to the direction in which the covered wire 33 passes. 35 is provided.
The covered wire 33 that has passed through the die 34 is cured with a liquid resin in the coating layer by a resin curing portion 36 formed of an ultraviolet irradiation device or the like.

Thereafter, the traveling direction of the coated wire 33 is changed by passing through the sandwiching roller 37, and the both ends of the coated wire 33 are sandwiched and held to suppress the rotation of the coated wire 33 in the axial direction. Is prevented. Subsequently, it passes through the first V-groove pulley 38 for preventing vibration. When passing through the first V-groove pulley 38, the Y-axis direction observation camera 39 takes a projected image of the wire saw. FIG. 6C shows the Y-axis direction and the X-axis direction perpendicular to the traveling direction of the covered wire 2.
Thereafter, the covered wire 33 passes through the second V-groove pulley 40 for preventing vibration. When passing through the second V-groove pulley 40, the X-axis direction observation camera 41 takes a projected image of the wire saw.
Thereafter, the covered wire 33 is wound after passing through the sandwiching roller 37.

Forming the wire saw so that the ratio of the number of abrasive grains on the side with few abrasive grains to the number of abrasive grains on the side with many abrasive grains is 0.6 or more and 1 or less is realized by the following method. It is possible. That is, when the ratio of the number of abrasive grains decreases to near 0.6, the position of the die 34 is adjusted, and the gap on the side where the abrasive grain ratio of the die 34 is small is expanded.
In addition, forming a wire saw having a standard deviation of the abrasive grain spacing of 200 μm or less means that when the standard deviation of the abrasive grain spacing increases to nearly 200 μm, the inside of the bond tank 31 is stirred to mix the abrasive grains and the resin. This is possible by increasing the dispersibility of.

  Further, the wire saw can be formed by the following two methods so that the protruding amount of the abrasive grains is 20% or more and 70% or less of the average grain diameter of the abrasive grains. The first method is to adjust the viscosity of the resin by adjusting the temperature of the bond tank 31 when the protruding amount of the abrasive grains is close to outside this range. That is, when the protruding amount of abrasive grains approaches 20% of the average grain diameter of the abrasive grains, the viscosity of the resin is lowered, and when it approaches 70%, the viscosity of the resin is increased. The second method is to adjust the volatile component in the resin when the protruding amount of the abrasive grains is close to outside this range. That is, when the protruding amount of the abrasive grains approaches 20% of the average grain diameter of the abrasive grains, the volatile component in the resin is increased, and when it approaches 70%, the volatile component in the resin is decreased.

Next, test results are shown.
The wire saw manufactured by the above method was subjected to a cutting test.
The core wires and abrasive grains forming the wire saw are as follows.
Core wire: φ0.18mm
Abrasive: Ni coated abrasive 40 / 60μm
The test conditions are as follows.
Cutting device: Single wire cutting device Wire speed: Average 400m / min
Wire tension: 25N
Material to be cut: single crystal silicon 40 mm width Table 1 shows test results for wire saws manufactured by changing the ratio of the number of abrasive grains.

In Table 1, the sharpness is expressed as an index when the grooving length for 5 minutes after the start of machining is 100 when the ratio of the number of abrasive grains is 0.95. The sharpness reduction rate represents the ratio of the sharpness for 5 minutes after 40 minutes from the start of processing to the sharpness in 5 minutes from the start of processing as an index. The wire wear rate is obtained by averaging the diameters of the wire saws measured at 10 locations after 40 minutes from the start of processing, and obtaining the difference from the diameter of the wire saw before starting processing as the amount of change in wire saw diameter.
(Wire saw diameter variation) / (Abrasive layer thickness × 2) × 100
The wire wear rate is calculated by the following formula. The surface roughness is expressed as an index when the surface roughness of the workpiece after processing is 100 when the ratio of the number of abrasive grains is 0.95.

As can be seen from Table 1, when the ratio of the number of abrasive grains on the side with few abrasive grains to the number of abrasive grains on the side with many abrasive grains is 0.6 or more and 1 or less, the sharpness and sharpness reduction rate Both the wire wear rate and the surface roughness are good values. In particular, a more preferable value is shown when the ratio is 0.8 or more and 1 or less. On the other hand, if it is less than 0.6, the sharpness, sharpness reduction rate, wire wear rate, and surface roughness are all poor.
Table 2 shows the test results for wire saws manufactured by changing the standard deviation of the abrasive grain spacing.

In Table 2, the sharpness is expressed as an index when the groove length for 5 minutes after the start of machining is 100 when the standard deviation of the abrasive grain interval is 105 μm. The surface roughness is represented by an index when the surface roughness of the workpiece after processing is 100 when the standard deviation of the abrasive grain interval is 105 μm. The sharpness reduction rate and the wire wear rate are the same as in Table 1.
As can be seen from Table 2, when the standard deviation of the abrasive grain spacing exceeds 200 μm, the surface roughness is deteriorated. This is because, when the standard deviation of the abrasive grain spacing exceeds 200 μm, the dispersibility of the abrasive grain arrangement is poor, so that the processing surface accuracy of the work material is lowered at the part where the abrasive grains are aggregated, and the part where the abrasive grain spacing is wide. This is because the bond material is easily peeled off, and the surface roughness cannot be maintained in a good state. A more preferable value is shown when the standard deviation of the abrasive grain spacing is 150 μm or less.
Table 3 shows test results for wire saws manufactured with different abrasive grain protrusions.

  In Table 3, the sharpness is expressed as an index when the grooving length for 5 minutes after the start of processing is 100 when the abrasive protrusion amount is 38% of the average particle diameter of the abrasive grains. Further, the surface roughness is represented by an index when the surface roughness of the workpiece after processing is 100 when the abrasive grain protrusion amount is 38% of the average grain size of the abrasive grains. The sharpness reduction rate and the wire wear rate are the same as in Table 1.

  When the protruding amount of the abrasive grains is 20% or more and 70% or less of the average grain diameter of the abrasive grains, the sharpness, sharpness reduction rate, wire wear rate, and surface roughness all show good values. In particular, a more preferable value is shown when it is 25% or more and 40% or less. On the other hand, when the protruding amount of the abrasive grains is less than 20% of the average grain size of the abrasive grains, the sharpness is lowered. This is because the bond material is easy to come into contact with the work material because the protrusion amount is small. On the other hand, when the protruding amount of the abrasive grains exceeds 70% of the average grain diameter of the abrasive grains, the wire wear rate increases. This is because the protruding amount is too large, and the abrasive grain holding force is reduced, and the abrasive grains easily fall off.

  INDUSTRIAL APPLICABILITY The present invention can be used as a wire saw that has improved cutting performance by optimizing the number of abrasive grains, the arrangement interval of abrasive grains, and the protruding amount of abrasive grains.

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 the manufacturing process of the wire saw 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 apparatus 8 Arithmetic apparatus 9 Display 10 Keyboard 11 Mouse 21 Core wire 23 Abrasive grain 31 Bond tank 32 Core wire 33 Coated wire 34 Die 35 Dice Position control unit 36 Resin curing unit 37 Pinch roller 38 First V-groove pulley 39 Y-axis direction observation camera 40 Second V-groove pulley 41 X-axis direction observation camera

Claims (4)

  Manufactured by taking a projected image of a wire saw in which abrasive grains are fixed around the core wire by a bond material, detecting the outline of the wire saw based on the brightness of the photographed image of the wire saw, and controlling the number of abrasive grains The number of abrasive grains on the side where there are many abrasive grains when comparing the number of abrasive grains located on one side of the wire saw with the core wire sandwiched between the number of abrasive grains located on the opposite side A wire saw characterized in that the ratio of the number of abrasive grains on the side where few abrasive grains exist is 0.6 or more and 1 or less.   A projected image of a wire saw in which abrasive grains are fixed to the periphery of the core wire by a bond material is detected, the outline of the wire saw is detected based on the brightness of the photographed image of the wire saw, and the arrangement interval of the abrasive grains is controlled. A wire saw, characterized in that a standard deviation of an array interval of abrasive grains is 200 μm or less.   Takes a projected image of a wire saw in which abrasive grains are fixed around the core wire by a bond material, detects the outline of the wire saw based on the brightness of the photographed image of the wire saw, and manufactures by controlling the protruding amount of the abrasive grain A wire saw, characterized in that the protruding amount of abrasive grains is 20% or more and 70% or less of the average grain size of the abrasive grains. The wire saw according to any one of claims 1 to 3, wherein the bond material is a resin bond.

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