JP2016159417A - Groove width measurement method for processing groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a groove width measurement method for a processing groove that can make the groove width of an ingot processing groove finer.SOLUTION: The movement of an ingot in a cut-in feed direction (X axis direction) is stopped to move the ingot in a thickness direction (Y axis direction), and a movement distance L to an ingot's contact with a wire R for short circuit is measured to calculate the groove width Dw of a processing groove D from the measured movement distance L and the diameter of the wire R. For example, a doubled length of the movement distance L is added to the diameter of the wire R to calculate the groove width Dw. This operation enables an easy measurement of the groove width Dw of the processing groove D in an ingot under discharge processing. Therefore, when the measured groove width Dw is thick, discharge processing can be executed so as to make the groove width Dw finer.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a groove width measuring method of a machining groove using a multi-wire electric discharge machining apparatus.

  Conventionally, a wire saw using abrasive grains is known as a cutting means for cutting a wafer from a cylindrical ingot. However, in such a wire saw, it is necessary to simultaneously supply a processing liquid (slurry) in which processing abrasive grains are mixed, and handling thereof is not easy. In addition, since the wire is in direct contact with the workpiece, particularly in the case of SiC (silicon carbide) with high hardness, there is a risk that the wire may be disconnected during processing. was there.

  Therefore, a multi-wire electric discharge machining device has been devised (Patent Document 1). Since the wire and the ingot are not in contact with each other by electric discharge machining, the load applied to the ingot is very low, and there is no effect of scratches such as scratches due to the slurry.

  The width of the groove formed by EDM depends on the applied voltage, pulse frequency, relative movement speed of the wire and ingot, variation in crystal state of the ingot, etc., as well as the diameter of the wire. It is desirable to slice the ingot into wafers.

JP 2011-140088 A

  By the way, measuring the groove width of the processed groove of the wafer is generally performed after the electric discharge machining is completed. This is because the electric discharge machining is performed in the machining liquid, and it is difficult to measure the groove width of the machining groove during the electric discharge machining. For this reason, the condition selection for narrowing the groove width cannot be performed during electric discharge machining, and the ingot may be completely machined under unsuitable conditions. It was.

  Then, this invention is made | formed in view of the above, Comprising: It aims at providing the groove width measuring method of the processing groove which can make the groove width of the processing groove of an ingot thin.

  In order to solve the above-mentioned problems and achieve the object, the groove width measuring method of a processed groove according to the present invention is a groove width measuring method of a processed groove formed when slicing an ingot into a wafer by wire electric discharge machining. X-axis direction by relatively moving the ingot and the wire so that the wire wound around the guide rollers adjacent to each other at a distance in the axial direction and the ingot is cut in parallel to the wire. Cutting feed means for cutting and feeding into the wafer, and index feeding means for indexing and feeding in the Y-axis direction orthogonal to the X-axis direction by relatively moving the wire and the ingot in the thickness direction of the wafer formed by slicing with the wire A multi-wire comprising: a high-frequency pulse power supply unit for supplying high-frequency pulse power to the wire and the ingot; and a control means for controlling each component Using an electromachining device, the wire and the ingot are cut and fed while applying high-frequency pulse power, and a machining groove is formed in the ingot by electric discharge machining. After performing the machining step, the wire is While being positioned in the groove, the wire and the ingot are indexed and fed while applying a high-frequency pulse power having a voltage lower than that of the machining step where the electric discharge machining is not performed, and the wire comes into contact with the ingot and the wire And a measuring step for measuring a moving distance until the current flowing in the ingot exceeds a threshold value, a groove width calculating step for calculating the width of the processed groove from the moving distance measured in the measuring step and the diameter of the wire; It is characterized by providing.

  In the groove width measuring method of the machining groove of the present invention, the movement distance until the wire comes into contact with the ingot is measured, and the groove width of the machining groove is calculated from the measured movement distance and the diameter of the wire. In addition, the groove width of the machining groove of the ingot can be easily calculated. Thereby, when the calculated groove width is large, there is an effect that the electric discharge machining can be performed so as to reduce the groove width.

FIG. 1 is a schematic diagram illustrating a configuration example of a multi-wire electric discharge machining apparatus. FIG. 2 is a flowchart (main routine) showing an operation example of the multi-wire electric discharge machining apparatus. FIG. 3 is a flowchart (subroutine) showing an operation example of the multi-wire electric discharge machining apparatus. FIG. 4 is a side view showing an example of electric discharge machining of an ingot. FIG. 5 is an enlarged view showing an example of electric discharge machining of an ingot. FIG. 6 is a diagram showing the current value of the high-frequency pulse power during electric discharge machining. FIG. 7 is a side view showing a first calculation example of the groove width of the machining groove. FIG. 8 is an enlarged view showing a first calculation example of the groove width of the processed groove. FIG. 9 is a diagram showing the current value of the high-frequency pulse power during measurement. FIG. 10 is a side view showing a second calculation example of the groove width of the machining groove. FIG. 11 is an enlarged view showing a second calculation example of the groove width of the machining groove.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment
A configuration example of the multi-wire electric discharge machining apparatus according to the embodiment will be described. FIG. 1 is a schematic diagram illustrating a configuration example of a multi-wire electric discharge machining apparatus. The multi-wire electric discharge machining apparatus 1 performs electric discharge machining of the ingot I with a wire R, and includes a feeding bobbin 20, a take-up bobbin 21, and a guide roller unit 30, as shown in FIG.

  A wire R, which is a metal wire such as brass, is wound around the feeding bobbin 20 by a certain amount. The feeding bobbin 20 feeds the wire R toward the guide roller unit 30. The guide roller unit 30 is disposed in the vicinity of the feeding bobbin 20 and guides the wire R fed from the feeding bobbin 20. The guide roller unit 30 is composed of a plurality of guide rollers 30a to 30j. The guide rollers 30a to 30j are formed in a cylindrical shape, and are arranged at intervals in the direction in which the wire R travels.

  The guide rollers 30a and 30b are disposed in the vicinity of the feeding bobbin 20, wind the wire R fed by the feeding bobbin 20, and feed the wire R toward the guide rollers 30c to 30i.

  The guide rollers 30c to 30i constitute a parallel wire portion 310 and are disposed so as to support the wire R in an annular shape. For example, the guide rollers 30c, 30d, 30e, 30g, 30h, and 30i of the parallel wire portion 310 support the annular wire R from the inside, and the guide roller 30f is connected to the wire R of the parallel wire portion 310 configured in an annular shape. On the other hand, it arrange | positions so that it may support from an outer side. The parallel wire section 310 winds the wire R sent out by the guide rollers 30a and 30b a plurality of times at a constant interval in the axial direction (Y-axis direction). For example, the wire R of the parallel wire portion 310 is wound eight times around the guide rollers 30c to 30i with an interval of about 0.5 mm to several mm in the axial direction.

  Here, the Y-axis direction is the axial direction of the guide rollers 30a to 30j. The X-axis direction is a direction orthogonal to the Y-axis direction. The Z-axis direction is a direction orthogonal to the X-axis direction and the Y-axis direction, which is the vertical direction in this embodiment.

  In the parallel wire section 310, the guide roller 30c winds the wire R sent out by the guide roller 30b and sends it out to the guide roller 30d. The guide roller 30d winds the wire R sent out by the guide roller 30c and sends it out to the guide roller 30e. The guide roller 30e winds the wire R sent out by the guide roller 30d and sends it out to the guide roller 30f. The guide roller 30f winds the wire R sent out by the guide roller 30e and sends it out to the guide roller 30g. The guide roller 30g winds the wire R sent out by the guide roller 30f and sends it out to the guide roller 30h. The guide roller 30h winds the wire R sent out by the guide roller 30g and sends it out to the guide roller 30i. The guide roller 30i winds the wire R sent out by the guide roller 30h and sends it out to the guide roller 30c. Now, the guide roller 30c-30i which comprises the parallel wire part 310 was wound around 1 round. The wire R is wound around the remaining seven turns on the guide rollers 30c to 30i of the parallel wire portion 310 with an interval of about 0.5 mm to several mm in the axial direction. The parallel wire portion 310 sends out the last wire R wound eight times to the guide roller 30j.

  The guide roller 30j is disposed in the vicinity of the take-up bobbin 21, winds the wire R sent from the parallel wire portion 310, and sends it to the take-up bobbin 21. The winding bobbin 21 winds up and collects the used wire R sent out from the guide roller 30j.

  The feeding bobbin 20, the take-up bobbin 21, and the guide rollers 30a to 30j are rotationally driven by a motor (not shown). It is not necessary to drive all the guide rollers 30a to 30j. For example, the guide rollers 30a, 30b, and 30j that do not constitute the parallel wire portion 310 may be driven rollers.

  The wire R of the parallel wire portion 310 is stretched with a certain tension along the Z-axis direction by a pair of guide rollers 30g and 30h. The wire R stretched by the guide rollers 30g and 30h constitutes a cutting wire portion 320 that slices the ingot I. The wire R of the cutting wire portion 320 travels upward along the Z-axis direction.

  The ingot I has a cylindrical shape and is sliced into a disc shape at intervals of the wires R of the cutting wire portion 320. The ingot I is a conductive material and is made of SiC, single crystal diamond, silicon, GaN (gallium nitride), or the like.

  A support mechanism 40 for supporting the ingot I is provided in the vicinity of the cutting wire portion 320. The support mechanism 40 includes a base portion 41, a support column 42, a cutting feed means 43, and an index feed means 44. The base part 41 fixes the ingot I. The base portion 41 is fixed to the front surface 41a by adhering the side surface Ia of the ingot I with the conductive adhesive B. The ingot I is fixed to the front surface 41a of the base portion 41 so that the end surface Ie thereof is substantially parallel to the Z-axis direction in which the wire R of the cutting wire portion 320 travels.

  The support column 42 is formed in a rod shape and is erected in the Z-axis direction. The support column 42 has a base 41 fixed at one end and a cut feed means 43 and an index feed means 44 fixed at the other end. The cutting feed means 43 moves the ingot I and the wire R relative to each other in the X-axis direction. For example, the cutting and feeding means 43 includes a ball screw (not shown) that extends along the X-axis direction, and a drive source that includes a pulse motor or the like. The cutting feed means 43 moves the support column 42 fixed to the nut of the ball screw along the X-axis direction, and converts the ingot I of the base portion 41 fixed to the support column 42 to the wire R of the cutting wire portion 320. Cut it.

  The index feeding means 44 moves the wire R and the ingot I relative to each other in the thickness direction (Y-axis direction) of a wafer (not shown) formed by slicing with the wire R. For example, the index feeding means 44 includes a ball screw (not shown) that extends along the Y-axis direction, and a drive source that includes a pulse motor or the like. The index feeding means 44 moves the support column 42 fixed to the nut of the ball screw along the Y axis direction, and indexes and feeds the ingot I of the base portion 41 fixed to the support column 42 in the Y axis direction.

  Multi-wire electric discharge machining is performed in a working fluid F such as water or oil which is a dielectric. The cutting wire part 320 is immersed in the processing tank 50 in which the processing liquid F is stored. In the processing tank 50, the wire R of the cutting wire portion 320 immersed in the processing liquid F processes the ingot I.

  A circular opening hole 52 for attaching the base portion 41 is provided in the front surface 51 of the processing tank 50. The base portion 41 is inserted into the opening hole 52 of the processing tank 50, and the gap between the opening hole 52 and the base portion 41 is sealed by a seal member such as rubber packing (not shown). Since the gap between the opening hole 52 and the base portion 41 is sealed by a sealing member, the base portion 41 is not allowed to leak from the opening hole 52 of the processing tank 50, so Thus, reciprocal movement in the X-axis direction is possible. Further, although the base part 41 moves in the Y-axis direction, the moving distance in the Y-axis direction is about several tens of μm, so that the machining liquid F is kept in a sealed state by the seal member, and the machining tank There is no leakage from the 50 opening holes 52.

  The processing tank 50 has an opening 53 on its upper surface, and the wire R sent out by the guide roller 30 f enters the processing tank 50 from the opening 53. The wire R that has entered the inside of the processing tank 50 is fed out of the processing tank 50 from the opening 53 by a guide roller 30 g disposed in the processing tank 50.

  The multi-wire electric discharge machining apparatus 1 includes a power feeding mechanism 60 that feeds power to the wire R and the ingot I. The power feeding mechanism 60 includes a high frequency pulse power supply unit 61, a wire electrode 62, and a base electrode (not shown).

  The high frequency pulse power supply unit 61 supplies high frequency pulse power to the wire R and the ingot I fixed to the base portion 41. For example, the high-frequency pulse power supply unit 61 is connected to the wire electrode 62 and supplies high-frequency pulse power to the wire R via the wire electrode 62. The wire electrode 62 is formed in a rod shape and is in contact with a wire R stretched between the guide roller 30h and the guide roller 30i. The high-frequency pulse power supply unit 61 is connected to a base electrode (not shown) fixed to the base 41 and supplies high-frequency pulse power to the ingot I through the base 41.

  When high-frequency pulse power is supplied from the high-frequency pulse power supply unit 61 and a voltage is applied between the electrodes of the wire R and the ingot I, the wire R discharges the ingot I arranged on the front surface. For example, when the distance between the ingot I and the wire R, which are in an insulating state in the machining fluid F, approaches about several tens of μm, the insulation between the two is destroyed and discharge occurs. By this discharge, the ingot I is heated and melted, and the temperature of the liquid is rapidly increased, whereby the liquid is vaporized, and the melted portion is scattered by volume expansion. In this way, by supplying the high-frequency pulse power to the wire R of the cutting wire portion 320, the ingot I is melted and scattered, and the ingot I is subjected to electric discharge machining.

  The high-frequency pulse power supply unit 61 includes a voltage adjustment unit 610, a pulse adjustment unit 611, and a calculation unit for calculating a groove width Dw of a processing groove D (see FIG. 5 and the like) formed when slicing the ingot I into a wafer. Means 612.

  The voltage adjusting means 610 adjusts the voltage of the high frequency pulse power. The voltage adjusting means 610 adjusts the voltage to be one of a machining voltage used during electric discharge machining and a measurement voltage used when calculating the groove width Dw of the machining groove D of the ingot I. The measurement voltage is a voltage lower than the machining voltage, and is a voltage at which electric discharge machining is not performed even when the wire R and the ingot I approach each other. For example, the processing voltage is about 150V to 200V, and the measurement voltage is about 100V.

  The pulse adjusting means 611 adjusts the frequency of the high frequency pulse power to a predetermined frequency. For example, the pulse adjusting unit 611 adjusts the frequency of the high-frequency pulse power used during the electric discharge machining and the frequency of the high-frequency pulse power used when calculating the groove width Dw of the machining groove D of the ingot I to the same frequency.

  The calculating means 612 measures the moving distance of the ingot I in the thickness direction (Y-axis direction) and calculates the groove width Dw of the processed groove D. For example, the calculation unit 612 measures the moving distance until the wire R contacts the ingot I and the current flowing through the wire R and the ingot I exceeds a threshold value. Then, the calculation unit 612 calculates the groove width Dw of the machining groove D from the measured moving distance and the diameter of the wire R.

  The multi-wire electric discharge machining apparatus 1 includes a feeding bobbin 20, a take-up bobbin 21, guide rollers 30 a to 30 j, a cutting feed means 43, an index feed means 44, and a control means 70 that controls the high-frequency pulse power supply unit 61. The control means 70 outputs a motor drive signal to the feeding bobbin 20, the winding bobbin 21, and the guide rollers 30a to 30j, and performs control so that the wire R is fed and wound, and the wire R is guided. Further, the control means 70 outputs a motor drive signal to the cutting and feeding means 43 to control the ingot I to be cut into the wire R of the cutting wire portion 320. Further, the control means 70 outputs a motor drive signal to the index feeding means 44 to control the ingot I to move in the index feeding direction (Y-axis direction). The control means 70 outputs a control signal to the high frequency pulse power supply unit 61 to control the output time of the high frequency pulse power.

  Next, an operation example of the multi-wire electric discharge machining apparatus 1 will be described. FIG. 2 is a flowchart (main routine) showing an operation example of the multi-wire electric discharge machining apparatus. FIG. 3 is a flowchart (subroutine) showing an operation example of the multi-wire electric discharge machining apparatus. FIG. 4 is a side view showing an example of electric discharge machining of an ingot. FIG. 5 is an enlarged view showing an example of ingot electric discharge machining, and is an enlarged view of the circular range K1 shown in FIG. FIG. 6 is a diagram showing the current value of the high-frequency pulse power during electric discharge machining. FIG. 7 is a side view showing a first calculation example of the groove width of the machining groove. FIG. 8 is an enlarged view showing a first calculation example of the groove width of the machining groove, and is an enlarged view of the circular range K2 shown in FIG. FIG. 9 is a diagram showing the current value of the high-frequency pulse power during measurement.

  First, electric discharge machining of ingot I is performed (step S1 shown in FIG. 2). For example, the control means 70 feeds the wire R from the feeding bobbin 20 and causes the wire R to travel at a constant speed. The control means 70 controls the high frequency pulse power supply unit 61 to supply high frequency pulse power to the wire R and the ingot I. The control means 70 controls the cutting feed means 43 to move the ingot I toward the wire R of the cutting wire portion 320, and a voltage is generated between the wires R and the ingot I as shown in FIGS. Is applied to perform electric discharge machining to form a machining groove D in the ingot I. At this time, as shown in FIG. 6, the current i1 of the high-frequency pulse power has a constant current waveform. In the machining groove D, machining waste U of the ingot I is generated by electric discharge machining.

  Next, it is determined whether or not the groove width Dw of the machining groove D of the ingot I is to be calculated (step S2). For example, the control means 70 compares the reference machining amount serving as a reference for calculating the groove width Dw with the machining amount of the ingot I, that is, the length obtained by cutting the ingot I in the X-axis direction. When the control means 70 determines that the machining amount of the ingot I has reached the reference machining amount (step S2: YES), the control means 70 calculates the groove width Dw of the machining groove D of the ingot I (step S3). The timing for calculating the groove width Dw is preferably performed at the initial stage of the electric discharge machining of the ingot I, that is, at the time when the outer peripheral portion of the ingot I is cut.

  When calculating the groove width Dw of the machining groove D of the ingot I, the control means 70 first controls the cutting feed means 43 to move the ingot I in the X-axis direction, that is, in the direction of machining the ingot I. The movement is stopped (step S31 shown in FIG. 3).

  Next, the voltage of the high frequency pulse power is adjusted (step S32). For example, the voltage adjustment unit 610 switches the voltage of the high-frequency pulse power from the processing voltage to the measurement voltage. Next, the control means 70 controls the index feeding means 44, and the wall surface Ds of the machining groove D becomes the wire R in a state where the wire R is positioned in the machining groove D as shown in FIGS. The ingot I is moved in the approaching direction (Y-axis direction) (step S33).

  Next, it is determined whether the ingot I and the wire R are in contact with each other and short-circuited (step S34). For example, as shown in FIG. 9, the control means 70 compares the threshold value Th for determining a short circuit with the current i2 of the measurement high-frequency pulse power flowing through the ingot I, and the current i2 does not exceed the threshold value Th. In this case, it is determined that the short circuit has not occurred (step S34: NO), and the movement of the ingot I in the Y-axis direction is continued. Further, when the current i2 of the high-frequency pulse power exceeds the threshold Th, the control means 70 determines that the ingot I and the wire R are in contact and short-circuited (step S34: YES). For example, in FIG. 9, when five high-frequency pulse powers for measurement are supplied, the current i2 of the high-frequency pulse power exceeds the threshold value Th, so that it is determined that a short circuit has occurred at the fifth pulse. When it is determined that the ingot I and the wire R are short-circuited, the control unit 70 controls the index feeding unit 44 to stop the movement of the ingot I in the Y-axis direction (step S35).

  Next, the moving distance L of the ingot I in the Y-axis direction is measured (step S36). For example, the calculation unit 612 counts the number of pulses from the start of supply of high-frequency pulse power for measurement until the current i2 of the high-frequency pulse power exceeds the threshold Th. For example, as shown in FIG. 9, the number of pulses is 5 pulses. The calculating means 612 calculates the moving time T of the wire R in the Y-axis direction based on the counted number of pulses, and calculates the moving distance L of the wire R in the Y-axis direction based on the calculated moving time T. Note that the time of the pulse interval for supplying the high-frequency pulse power is specified in advance, and the moving speed of the ingot I in the Y-axis direction is also specified in advance. The movement distance L may be calculated based on the number of times that a pulse signal for driving the pulse motor of the index feeding means 44 is output during the movement time T.

  Next, the groove width Dw of the machining groove D of the ingot I is calculated (step S37). For example, the calculation unit 612 calculates the groove width Dw based on the movement distance L and the diameter of the wire R. For example, the calculating unit 612 calculates the groove width Dw by adding the length obtained by doubling the moving distance L and the diameter of the wire R. Here, since the electric discharge machining is performed radially by the approach of the wire R and the ingot I, the distance between the one wall surface Ds of the machining groove D and the wire R and the other of the machining groove D at the time of electric discharge machining. The distance between the side wall Ds and the wire R is equal.

  Next, the ingot I is moved in the Y-axis direction to return to the original position (step S38). For example, the control means 70 controls the index feeding means 44, and the wall surface Ds of the machining groove D contacting the wire R is separated from the wire R by the movement distance L obtained by moving the ingot I in step S33. The ingot I is moved in the direction to go. Thereby, the wire R is positioned at the center of the machining groove D in the width direction (Y-axis direction) of the machining groove D of the ingot I.

  Next, electric discharge machining is performed based on the groove width Dw calculated in step S37 (step S39). For example, when the calculated groove width Dw is thicker than a prescribed groove width, it is necessary to reduce the groove width Dw in the remaining electric discharge machining of the ingot I. In this case, the control means 70 increases the speed at which the ingot I is cut into the wire R, increases the frequency of the high-frequency pulse power, decreases the voltage of the high-frequency pulse power, and suppresses the machining amount, thereby reducing the groove width Dw. To make it thinner. In addition, when the calculated groove width Dw is equal to the predetermined groove width or within the allowable range, the current machining conditions are continued and the electric discharge machining is performed.

  Next, it is determined whether or not the electric discharge machining of the ingot I has been completed (step S4 shown in FIG. 2). For example, the control means 70 determines that the electric discharge machining has been completed when the ingot I is completely sliced and the current flowing through the wire R and the ingot I changes. Further, it may be determined that the electric discharge machining has been completed based on the machining amount of the ingot I, that is, the moving distance of the ingot I in the X-axis direction. When the control means 70 determines that the groove width Dw of the machining groove D has not yet been calculated and the electric discharge machining of the ingot I has not been completed (step S4: NO), the control means 70 returns to step S2 and returns to the machining groove of the ingot I. It is determined whether or not the groove width Dw of D is to be calculated. Moreover, the control means 70 complete | finishes the electrical discharge machining of the ingot I, when it is judged that the electrical discharge machining of the ingot I was complete | finished (step S4: YES).

  If the calculation of the groove width Dw of the machining groove D has been performed and the electric discharge machining of the ingot I has not been completed, the electric discharge machining is performed until the ingot I is completely cut.

  In Step S2, the control means 70 determines that the machining amount of the ingot I has not reached the reference machining amount that is the reference for calculating the groove width Dw (Step S2: NO). The process of calculating the width Dw (step S3) is skipped and electric discharge machining is performed.

  As described above, according to the groove width measuring method of the processed groove according to the embodiment, the moving distance L until the wire R contacts the ingot I and short-circuits is measured, and the measured moving distance L and the wire R are measured. The groove width Dw of the machining groove D is calculated from the diameter. Thereby, there exists an effect that the groove width Dw of the process groove | channel D in the ingot I in electrical discharge machining can be calculated easily.

  In addition, electric discharge machining may be performed in the machining fluid F, and when the machining groove D is imaged and the groove width Dw is calculated by an imaging means or the like as in the prior art, the groove width Dw is calculated during electric discharge machining. However, in the present invention, since the groove width Dw can be calculated during the electric discharge machining, the optimum machining conditions can be set at an early stage. Thereby, it can suppress that the groove width Dw of the process groove | channel D becomes thick, and can process the ingot I with the thin groove width Dw. Therefore, a large number of wafers W can be formed from the ingot I, and productivity can be improved.

  In addition, the measurement voltage is set to a voltage that is low enough to prevent electric discharge, so that it is possible to suppress an increase in the groove width Dw of the processed groove D due to generation of unnecessary electric discharge, and a short circuit occurs. Moreover, it can also suppress that the wire R becomes high heat. Thereby, when calculating groove width Dw, it can control that wire R is damaged or it breaks.

[Modification]
Next, a modification of the embodiment will be described. Although the example which calculates the groove width Dw based on the movement distance L measured by moving the ingot I in the Y-axis direction has been described, the present invention is not limited to this. FIG. 10 is a side view showing a second calculation example of the groove width of the machining groove. FIG. 11 is an enlarged view showing a second calculation example of the groove width of the machining groove, and is an enlarged view of the circular range K3 shown in FIG. As shown in FIGS. 10 and 11, the ingot I is moved in the X-axis direction in a state where the voltage for measurement is set, and the movement distance L to the bottom Db of the processing groove D is measured, and the measured bottom Db is reached. The groove width Dw of the machining groove D may be calculated based on the moving distance L. For example, the groove width Dw is calculated by adding the length obtained by doubling the moving distance L to the bottom Db and the diameter of the wire R. Since the electric discharge machining of the ingot I by the wire R is performed radially when the wire R and the ingot I approach, the distance between the wall surface Ds of the machining groove D of the ingot I and the wire R, and the machining groove D The distance between the bottom Db and the wire R is equal. Therefore, the ingot I may be moved in the Y-axis direction with respect to the wire R to measure the moving distance L from the wall surface Ds, or the ingot I may be moved in the X-axis direction to move the moving distance L from the bottom Db. May be measured.

  Further, the groove width Dw is set based on the movement distance measured by moving the ingot I in the Y-axis direction from the state in which the ingot I is in contact with one wall surface Ds of the machining groove D until it is in contact with the other wall surface Ds. It may be calculated. In this case, the groove width Dw is obtained by adding the calculated moving distance and the diameter of the wire R.

  Further, although the short circuit between the ingot I and the wire R is determined based on the change in the measurement current i2, the short circuit between the ingot I and the wire R may be determined based on the change in the measurement voltage.

  In addition, the groove width Dw was calculated by moving the ingot I in the Y-axis direction (or X-axis direction) with the position of the wire R of the cutting wire portion 320 fixed, but with the position of the ingot I fixed The groove width Dw may be calculated by moving the wire R of the cutting wire portion 320 in the Y-axis direction (or X-axis direction). Alternatively, the groove width Dw may be calculated by moving both the ingot I and the wire R of the cutting wire portion 320 in the Y-axis direction (or the X-axis direction).

  Further, the process for calculating the groove width Dw of the processed groove D of the ingot I may be performed once or a plurality of times. When the process of calculating the groove width Dw is performed a plurality of times, for example, when the outer peripheral portion of the ingot I is cut, when the central portion of the ingot I is processed, and when the remaining outer peripheral portion of the ingot I is processed. Conceivable. Since the central portion of the ingot I tends to accumulate the machining waste U and the amount of machining tends to increase, the machining groove D can be obtained by changing the machining condition by calculating the groove width Dw according to the machining location of the ingot I. Are formed with a constant narrow groove width Dw. Further, when the calculated groove width Dw is different from the prescribed groove width and the machining conditions are changed, the ingot I is cut and fed to some extent, and then the groove width Dw is measured in order to confirm the groove width Dw again. Good.

DESCRIPTION OF SYMBOLS 1 Multi-wire electric discharge machining apparatus 30a-30j Guide roller 320 Cutting wire part 41 Base part 43 Cutting feed means 44 Index feed means 70 Control means D Machining groove Db Bottom part Ds Wall surface Dw Groove width I Ingot L Movement distance T Time time W Wafer

Claims (1)

A method for measuring a groove width of a processed groove formed when slicing an ingot into a wafer by wire electric discharge machining,
The wire wound around the guide roller several times at intervals in the axial direction at intervals, and the ingot and the wire move relative to each other so that the ingot cuts into the parallel wires, and cut in the X-axis direction. A cutting and feeding means, an index feeding means for relatively moving the wire and the ingot in the thickness direction of the wafer formed by slicing with the wire, and indexing and feeding in the Y-axis direction orthogonal to the X-axis direction, and the wire And a high-frequency pulse power supply unit for supplying high-frequency pulse power to the ingot, and a control means for controlling each component,
A cutting step of cutting and feeding the wire and the ingot while applying high-frequency pulse power, and forming a machining groove in the ingot by electric discharge machining,
After performing the machining step, the wire and the ingot are determined while applying high-frequency pulse power having a voltage lower than that of the machining step in which electric discharge machining is not performed in a state where the wire is positioned in the machining groove. Measuring step of measuring the moving distance until the wire contacts the ingot and the current flowing through the wire and the ingot exceeds a threshold value;
A groove width measuring method of a processed groove, comprising: a groove width calculating step of calculating a width of the processed groove from the moving distance measured in the measuring step and the diameter of the wire.

Images