JP6275551B2 - Multi-wire electric discharge machine - Google Patents

Description

  The present invention relates to a multi-wire electric discharge machining apparatus.

  Conventionally, a wire saw using abrasive grains has been known as a cutting means for cutting a wafer from a cylindrical ingot. In this wire saw, a cutting wire wound between a plurality of guide rollers is driven at a high speed in the longitudinal direction, and the workpiece is cut and fed to the wire, whereby a large number of thin pieces are simultaneously removed from the workpiece. Cut out. The cut wafer is flattened while grinding and removing scratches generated by the wire saw, and a device is formed on the surface to become a semiconductor wafer.

  However, in such a wire saw, it is necessary to simultaneously supply a processing fluid (slurry) mixed with processing abrasive grains to a plurality of cutting wire portions formed between the guide rollers, and the handling is easy. Not. In addition, since the wire is in direct contact with the workpiece, the wire may be disconnected during cutting. If such a disconnection occurs, there is a disadvantage that it takes a long time to recover.

  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.

JP 2000-94221 A

  However, since the wire is partially burnt and disappears due to electric discharge machining generated between the wire and the ingot, there is a possibility that the wire burns and is cut when the discharge continues locally. For this reason, the number of pulses and the pulse width are adjusted to such an extent that the wire is not cut, thereby limiting the processing rate.

  Therefore, the problem to be solved by the present invention is to provide a multi-wire electric discharge machining apparatus that suppresses deterioration due to electric discharge machining of the wire and makes the wire difficult to break.

  In order to solve the above-described problem, a multi-wire electric discharge machining apparatus according to the present invention includes a plurality of guides that are disposed at intervals and include a first guide roller and a second guide roller that are adjacently arranged in parallel. A roller and a plurality of the guide rollers are wound a plurality of times in the axial direction and arranged in parallel with each other, and the ingot is divided into a plurality of cut pieces between the first guide roller and the second guide roller. A wire to be cut, a reversing roller for reversing the winding direction of the wire wound around the guide roller, a wire supply means for supplying the wire, a wire winding means for winding the wire, and a high frequency to the wire A multi-wire electric discharge machining apparatus comprising a high-frequency pulse power supply for supplying pulse power and a base portion for fixing an ingot, wherein the first guide roller is axially forward A first rotating roller that rotates clockwise and a second rotating roller that rotates rearward in the axial direction and counterclockwise, and the second guide roller rotates clockwise in the axially forward direction. A third rotating roller that rotates, and a fourth rotating roller that rotates counterclockwise in the axial direction, and the wire is disposed between the first rotating roller and the third rotating roller. After being wound clockwise, the wire is wound counterclockwise between the second rotating roller and the fourth rotating roller via the reversing roller, and then wound clockwise. Is cut into an ingot from one circumferential surface in the circumferential direction, and the wire wound counterclockwise is cut into the ingot from the other circumferential surface, so that the two circumferential surfaces of the wire can be used for electric discharge machining. To do.

  According to the multi-wire electric discharge machining apparatus of the present invention, by reversing the direction of the wire in the middle, the curved surfaces in the two directions facing in the circumferential direction of the wire can be used for electric discharge machining. There is an effect that the deterioration can be suppressed and the disconnection can be made difficult. Further, since the number of surfaces that can be processed is two, it is possible to increase the number of windings, and it is possible to use the wires discarded after the processing without waste.

FIG. 1 is a perspective view showing a configuration example of a multi-wire electric discharge machining apparatus. FIG. 2 is a front view illustrating a configuration example of the guide roller. FIG. 3 is a top view illustrating a function example of the reversing roller. FIG. 4 is a schematic diagram showing an example of using a wire. FIG. 5 is a flowchart showing an operation example of the multi-wire electric discharge machining apparatus.

  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 multi-wire electric discharge machining apparatus according to an embodiment will be described. FIG. 1 is a perspective view showing a configuration example of a multi-wire electric discharge machining apparatus. A multi-wire electric discharge machining apparatus 1 shown in FIG. 1 includes a feeding bobbin 2 that feeds and feeds a wire R, cylindrical guide rollers 30 to 35 that guide the wire R fed by the feeding bobbin 2 at six locations, A reversing roller 36 for reversing R and a winding bobbin 4 for winding the wire R are provided. The feeding bobbin 2 functions as a wire supply unit, and the winding bobbin 4 functions as a wire winding unit. A wire R which is a metal wire such as brass used for electric discharge machining is wound around the feeding bobbin 2. The six guide rollers 30 to 35 are arranged at a predetermined interval.

  A guide roller 30 that receives one wire R from the feeding bobbin 2 and a guide roller 35 that sends the wire R toward the winding bobbin 4 are disposed adjacent to each other. The four guide rollers 31 to 34 are arranged side by side with the above-described guide rollers 30 and 35, and are arranged at rectangular corners so as to form a rectangular shape. The guide rollers 31 to 34 are arranged so that a line segment formed by the adjacent guide roller 31 and the guide roller 32 is parallel to a line segment formed by the adjacent guide roller 34 and the guide roller 33. It is arranged. The guide roller 34 functions as a first guide roller, and the guide roller 33 functions as a second guide roller.

  The wire R is wound around the guide rollers 31 to 34 a plurality of times at intervals in the axial direction and is parallel to each other, and cuts the ingot I into a plurality of cut pieces between the guide roller 34 and the guide roller 33.

  A reverse roller 36 is disposed in the vicinity of the guide roller 34. The reversing roller 36 winds the wire R counterclockwise and reverses the winding direction of the wire R wound around the guide rollers 31 to 34. For example, the reverse roller 36 winds the wire R sent out from the guide roller 34, reverses the wire R, and sends it back to the guide roller 34.

  The guide rollers 31 to 34 wind the wire R fed from the feeding bobbin 2 and fed from the guide roller 30 a plurality of times and feed it in the normal rotation direction U, and wind the wire R reversed by the reversing roller 36 a plurality of times. Rotate and feed in the reverse direction V, and feed the wire R to the take-up bobbin 4 via the guide roller 35.

  The feeding bobbin 2, the guide rollers 30, 35, the take-up bobbin 4, and the reverse roller 36 are rotationally driven by a rotation motor (not shown). The guide rollers 30 and 35 are not necessarily driven by a motor, and may be idle rollers.

  The wire R wound a plurality of times at intervals in the longitudinal direction of the guide rollers 31 to 34 constitutes a parallel cutting wire portion 5 formed between a pair of adjacent guide rollers 33 and guide rollers 34. .

  The cutting wire portion 5 is composed of a plurality of wires R which are stretched with a certain tension by the guide roller 33 and the guide roller 34 and are arranged in the longitudinal direction of the guide rollers 33 and 34 at a predetermined interval. ing. These wires R are stretched so as to be perpendicular to the vertical direction (Z-axis direction) (Y-axis direction).

  An ingot installation means 6 for installing the ingot I is provided at a position facing the cutting wire portion 5. Ingot I is a SiC (Silicon Carbide) single crystal. The ingot installation means 6 is installed on the upper surface side of the cutting wire portion 5 and includes a base portion 61 and a support member 62. The base portion 61 is disposed so as to face the wire R of the cutting wire portion 5, has a rectangular parallelepiped shape that is formed slightly larger than the length of the cylindrical ingot I in the longitudinal direction and the short-side direction, and the support member 62 is attached to the base portion 61. The ingot I is fixed through. The base portion 61 is engaged with a ball screw (not shown) extending in parallel to the X-axis direction, and the traveling direction (Y of the wire R of the cutting wire portion 5 is driven by a drive source configured by a pulse motor or the like. It is attached so as to be movable in the X-axis direction perpendicular to the (axial direction). Thereby, the position where the cutting of the ingot I is started by the wire R of the cutting wire portion 5 can be adjusted. The base portion 61 is engaged with a ball screw (not shown) extending in parallel with the Z-axis direction, and approaches the wire R of the cutting wire portion 5 by a drive source configured by a pulse motor or the like. It is attached so as to be movable in the Z-axis direction away from each other. Thereby, the progress in the cutting direction in which the ingot I is cut by the wire R of the cutting wire portion 5 can be adjusted. The drive source is connected to the control means 8, and the rotation of the pulse motor is controlled by the control means 8.

  A support member 62 is fixed to the lower surface side of the base portion 61. A conductive adhesive 63 is applied to the lower surface side of the support member 62, and the ingot I is bonded to the support member 62 through the conductive adhesive 63. When the ingot I is cut by the wire R of the cutting wire portion 5, the ingot I is cut so that the wire R passes through the ingot I and slightly cuts the support member 62. That is, a part of the support member 62 is cut simultaneously with the ingot I. Thereby, the ingot I can be cut | disconnected reliably.

  Multi-wire electric discharge machining is performed in a working fluid such as water or oil that is a dielectric, and the cutting wire portion 5 is immersed in a machining tank 9 filled with the machining fluid. In the processing tank 9, the wire R of the cutting wire portion 5 immersed in the stored processing liquid processes the ingot I.

  In the processing tank 9, a basket 10 for accommodating the wafer W is disposed. The flange 10 is disposed directly below the ingot setting means 6, is formed larger than the length of the ingot I in the longitudinal direction and the short direction, and has a certain depth. The wafer W separated from the ingot I fixed to the base portion 61 is sunk and accommodated in the basket 10 disposed in the processing tank 9.

  The multi-wire electric discharge machining apparatus 1 includes a power feeding unit 7 that feeds power to the cutting wire unit 5. The power supply means 7 includes a power supply 71 and a high-frequency pulse power source 72. The power supply 71 is disposed in contact with the wire R of the cutting wire portion 5 and is connected to the high-frequency pulse power source 72. The high-frequency pulse power source 72 supplies high-frequency pulse power to the wire R of the cutting wire unit 5 through the power supply 71. The high frequency pulse power source 72 is connected to the control means 8 and the frequency for supplying power is controlled.

  When high-frequency pulse power is supplied from the high-frequency pulse power source 72 to the power supply 71, the wire R of the cutting wire portion 5 that is in contact with the power supply 71 discharges the ingot I disposed 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, approaches to several tens of microns, the insulation between the two is destroyed and discharge is generated. By this discharge, the ingot I is heated and melted, and further, the temperature of the working fluid is rapidly increased, whereby the working fluid is vaporized and the melted portion is scattered by volume expansion. In this way, by supplying high-frequency pulse power to the wire R of the cutting wire portion 5, the ingot I is cut by intermittently performing the process of melting and scattering the ingot I.

  Next, the guide rollers 31 to 34 and the reverse roller 36 will be described in detail. FIG. 2 is a front view illustrating a configuration example of the guide roller. FIG. 3 is a top view illustrating a function example of the reversing roller. FIG. 4 is a schematic diagram showing an example of using a wire. The guide roller 34 shown in FIG. 2 rotates clockwise in the axial direction forward, and rotates in the forward direction U. The forward rotation roller 34a feeds the wire R in the forward rotation direction U. And a reverse roller 34b for feeding out. The normal rotation roller 34a functions as a first rotation roller, and the reverse rotation roller 34b functions as a second rotation roller. In the normal rotation roller 34a and the reverse rotation roller 34b, guide grooves P through which the wire R is guided are formed at five locations at regular intervals in the circumferential direction. The normal rotation roller 34a is driven in the normal rotation direction U by a rotation motor (not shown). For example, the rotation shaft of the rotation motor and the rotation shaft 34c of the normal rotation roller 34a are engaged with each other by a gear, and the normal rotation roller 34a fixed to the rotation shaft 34c is rotated by driving the rotation motor.

  The reverse rotation roller 34b is disposed so as to be idled. For example, the reverse roller 34b may employ a mechanism such as a bearing in order to reduce frictional resistance with respect to the support shaft 34d when idling. By pulling out the wire R wound around the guide groove P formed in the reverse rotation roller 34b, the reverse rotation roller 34b idles in the reverse rotation direction V in accordance with the pulling amount.

  The guide roller 33 is configured similarly to the guide roller 34. For example, the guide roller 33 rotates clockwise in the axial direction forward, and rotates in the forward direction U to rotate the wire R in the forward direction U. The reverse rotation rotates in the counterclockwise direction V to rotate counterclockwise in the axial direction and feeds the wire R in the reverse direction V. And a roller 33b. The normal rotation roller 33a functions as a third rotation roller, and the reverse rotation roller 33b functions as a fourth rotation roller. The normal rotation roller 33a is disposed so as to be idled, and the reverse rotation roller 33b is driven by a rotation motor.

  The guide roller 31 is configured similarly to the guide roller 34. For example, the guide roller 31 rotates clockwise in the forward direction in the axial direction, and rotates in the forward direction U to rotate the wire R in the forward direction U. The reverse rotation rotates in the counterclockwise direction in the counterclockwise direction and rotates the wire R in the reverse direction V. And a roller 31b. The normal rotation roller 31a idles, and the reverse rotation roller 31b is driven by a rotation motor.

  The guide roller 32 is configured in the same manner as the guide roller 34. For example, the guide roller 32 rotates clockwise at the front in the axial direction, and rotates in the forward direction U to rotate the wire R in the forward direction U. The reverse rotation rotates at the left in the axial direction and feeds the wire R in the reverse direction V. And a roller 32b. The normal rotation roller 32a is driven by a rotary motor, and the reverse rotation roller 32b rotates idly.

  As shown in FIG. 3, the wire R is wound clockwise between the normal rotation roller 34 a of the guide roller 34 and the normal rotation roller 33 a of the guide roller 33, and then passes through the reverse roller 36 to guide the wire R. The roller 34 is wound counterclockwise between the reverse rotation roller 34 b of the roller 34 and the reverse rotation roller 33 b of the guide roller 33. For example, the wire R is wound a plurality of times in accordance with the guide grooves P formed in the normal rotation roller 34a of the guide roller 34 and the normal rotation roller 33a of the guide roller 33, and the rear end portion 34e side of the normal rotation roller 34a. After being wound around the guide groove P, it is sent out to the reverse roller 36. The wire R is wound around the reversing roller 36 once, wound around the guide groove P on the front end portion 34f side of the reversing roller 34b, and sent out to the reversing roller 33b of the guide roller 33.

  The wire R is sequentially wound along the guide groove P from the front end side to the rear end side of the normal rotation rollers 31a to 34a. For example, as shown in FIG. 3, the normal rotation roller 34a is sequentially wound along the guide groove P from the front end portion 34g side toward the rear end portion 34e side. Further, the wire R is sequentially wound along the guide groove P from the front end portion side to the rear end portion side of the reverse rotation rollers 31b to 34b. For example, as shown in FIG. 3, the reversing roller 34b is sequentially wound along the guide groove P from the front end portion 34f side to the rear end portion 34h side. The wire R wound on the rear end side of the reverse rotation roller 31b of the guide roller 31 is wound around the winding bobbin 4 and collected. As described above, the wire R wound around the guide groove P on the front end side of the forward rotation rollers 31a to 34a becomes the wire R that is not deteriorated most, and becomes the guide groove P on the rear end side of the reverse rotation rollers 31b to 34b. The wound wire R is the most deteriorated wire R.

  The wire R wound clockwise by the normal rotation roller 34a and the normal rotation roller 33a is cut into the ingot I from one peripheral surface r1 in the circumferential direction, as shown in FIG. Further, the wire R wound counterclockwise by the reverse rotation roller 34b and the reverse rotation roller 33b is cut into the ingot I from the other peripheral surface r2 located on the back side of the one peripheral surface r1, so that The surface can be used for electric discharge machining. As described above, the wire R can be cut into the ingot I from the other peripheral surface r2 that is not deteriorated by the discharge because the portion deteriorated by the discharge is reversed. Thereby, since the discharge of the wire R is not performed locally using only one peripheral surface r1, deterioration of the wire R can be suppressed.

  For example, the wires R1 to R4 shown in FIG. 4 are supported by the normal rotation roller 33a and the normal rotation roller 34a, and the wires R5 to R8 are supported by the reverse rotation roller 33b and the reverse rotation roller 34b. is there. For the wires R1 to R4, for example, as shown in the enlarged view of the wire R1, the deteriorated portion K is not generated. On the other hand, since the wires R5 to R8 are reversed by the reversing roller 36, for example, as shown in the enlarged view of the wire R7, a deteriorated portion K due to discharge is generated on one peripheral surface r1. . However, the reversed wires R5 to R8 can be subjected to electric discharge machining with the same accuracy as the wires R1 to R4 because the deteriorated portion K is not generated on the other peripheral surface r2 used for electric discharge machining. Thus, since the curved surfaces in the two directions facing each other in the circumferential direction of the wire R can be used for electric discharge machining, deterioration due to electric discharge machining of the wire R can be suppressed and disconnection can be made difficult. Note that the wires R1 to R8 shown in FIG. 4 heat and melt the ingot I by electric discharge, further vaporize the machining liquid by rapidly raising the temperature of the machining liquid, and scatter the melted portions by the bubbles B due to volume expansion. I am letting.

  In the present invention, the wire R is wound clockwise between the normal rotation roller 34 a (first rotation roller) and the normal rotation roller 33 a (third rotation roller), and then passes through the reverse roller 36. The counter-rotating roller 34b (second rotating roller) and the reverse rotating roller 33b (fourth rotating roller) are wound counterclockwise between the normal rotating roller 34a and the normal rotating roller 33a. Means that the winding direction of the wire R is changed by the reversing roller 36 and is wound in the other direction between the reverse rotation roller 34b and the reverse rotation roller 33b. The winding direction of the wire R is not limited to the forward rotation rollers 33a and 34a being clockwise and the reverse rotation rollers 33b and 34b being not counterclockwise.

  Next, an operation example of the multi-wire electric discharge machining apparatus 1 will be described. FIG. 5 is a flowchart showing an operation example of the multi-wire electric discharge machining apparatus. In step ST1 shown in FIG. 5, alignment of the ingot I is performed. For example, after fixing the ingot I to the base portion 61, the base portion 61 is set in the X-axis direction so that the control means 8 sets the position where the ingot I is cut with respect to the wire R of the cutting wire portion 5. Move. Next, the process proceeds to step ST2.

  In step ST2, the ingot I is cut. For example, one circumferential surface r1 of four wires R stretched by the normal rotation roller 33a and the normal rotation roller 34a faces the ingot I, and four wires stretched by the reverse rotation roller 33b and the reverse rotation roller 34b. With the other peripheral surface r2 of R facing the ingot I, the base portion 61 to which the ingot I is fixed is moved in the Z-axis direction (approach direction). Thereby, the ingot I is heated and melted by the discharge of the wire R, and the temperature of the machining liquid is rapidly increased, whereby the machining liquid is vaporized, and the melted portion is scattered by volume expansion. In this way, the ingot I is cut by intermittently performing the process of being melted and scattered by the wire R, and the wafer W is formed. The base 61 is moved in the thickness direction (X-axis direction) of the wafer W to separate the wafer W from the support member 62, and the wafer W is submerged in the basket 10. After the wafer W is sunk in the cage 10, the base part 61 is moved in the Z-axis direction (separation direction) to separate the wire R from the base part 61. During the multi-wire electric discharge machining, a new amount of new wire R is always fed out from the feeding bobbin 2.

  As described above, according to the multi-wire electric discharge machining apparatus 1 according to the embodiment, the curved surfaces in two directions opposed in the circumferential direction of the wire R are used for electric discharge machining by reversing the direction of the wire R in the middle. Therefore, it is possible to suppress the deterioration of the wire R due to the electric discharge machining and to make it difficult to disconnect the wire R. In addition, since the number of surfaces that can be processed is two, the number of windings can be increased, and the wire R that is discarded after processing can be used without waste. Further, since the number of windings of the wire R can be increased, the number of wafers that can be formed from the ingot I at a time can be increased, and work efficiency can be improved.

  The ingot may be a single crystal diamond other than the SiC single crystal.

DESCRIPTION OF SYMBOLS 1 Multi-wire electric discharge machine 2 Feeding bobbin 30-35 Guide roller 31a-34a Normal rotation roller 31b-34b Reverse rotation roller 34c Rotating shaft 34d Support shaft 34e Rear end part 34f Front end part 34g Front end part 34h Rear end part 36 Reverse roller 4 Winding Take-up bobbin 5 Cutting wire part 61 Base part 72 High-frequency pulse power supply 9 Processing tank 10 籠 I Ingot W Wafer U Forward direction V Reverse direction K Degraded part

Claims (3)

A plurality of guide rollers including a first guide roller and a second guide roller which are disposed at intervals and are juxtaposed in parallel;
A wire that is wound around the plurality of guide rollers a plurality of times at intervals in the axial direction and is parallel to each other, and cuts the ingot into a plurality of cutting pieces between the first guide roller and the second guide roller When,
A reversing roller for reversing the winding direction of the wire wound around the guide roller;
Wire supply means for supplying the wire;
Wire winding means for winding the wire;
A high-frequency pulse power supply for supplying high-frequency pulse power to the wire;
A multi-wire electric discharge machining apparatus comprising a base for fixing an ingot,
The first guide roller is
A first rotating roller that rotates clockwise in front of the axial direction;
A second rotating roller that rotates counterclockwise in the axial direction, and
The second guide roller is
A third rotating roller that rotates axially forward and clockwise;
A fourth rotating roller that rotates counterclockwise at the rear in the axial direction,
The wire is
After being wound clockwise between the first rotating roller and the third rotating roller, via the reverse roller, between the second rotating roller and the fourth rotating roller. Is wound counterclockwise,
The wire wound clockwise is cut into an ingot from one circumferential surface in the circumferential direction, and the wire wound counterclockwise is cut into an ingot from the other circumferential surface, so that two circumferential surfaces of the wire Can be used for electric discharge machining.   The multi-wire electric discharge machining apparatus according to claim 1, wherein the wire is wound counterclockwise around the reverse roller. The first guide roller is arranged such that the first rotary roller is driven by a rotary motor, and the second rotary roller is idling.
3. The multi roller according to claim 1, wherein the fourth guide roller is arranged such that the fourth rotary roller is driven by a rotary motor and the third rotary roller is idling. Wire electrical discharge machining equipment.

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