JP2015120232A - Wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire saw which can prevent occurrence of a wire jump while preventing an increase in working resistance.SOLUTION: The wire saw performs working of a workpiece by making wire rows with a lot of wires wound around a plurality of multiple-groove rollers travel and pushing the workpiece onto the wire rows. The wire saw includes a fixture where a plurality of grooves are formed, the fixture is disposed so that respective wires of the wire rows travel one by one in each of the plurality of grooves, and the width of each of the plurality of grooves is larger than the diameter of the wire.

Description

  The present invention relates to a wire saw.

  A silicon wafer serving as a solar cell substrate is manufactured by slicing a silicon ingot with a wire saw. The wire saw is characterized by high production efficiency because it can slice several hundred to one thousand wafers at a time by one processing.

  On the other hand, high productivity includes the danger that damage will be serious once trouble occurs. As a specific trouble, there is a phenomenon called “wire jump” in a multi-groove roller. When “wire jump” occurs, a large loss occurs.

  Therefore, in order to prevent “wire jump”, a conventional wire saw provided with a partition plate is known. FIG. 8 is a view showing a conventional wire saw described in Patent Document 1. As shown in FIG.

  In FIG. 8, the wire S is wound a plurality of times between the multi-groove rollers 31, 32, 33 to form a wire row SL at equal intervals. The workpiece W is disposed between the multi-groove rollers 32 and 33. The partition plates 55 and 66 are installed so as to sandwich the workpiece W, and the lower ends of the partition plates 55 and 66 are in contact with the wire row SL. The workpiece W is pressed against the wire row SL traveling by driving of the motor 44.

  In the technique described in Patent Document 1, it is considered that foreign matter mixed in the slurry and coolant and fragments of the workpiece W enter the multi-groove rollers 32 and 33 to cause “wire jump”. ing. From this idea, in Patent Document 1, foreign matter mixed in the slurry and coolant, and fragments of the workpiece W are scraped off by the partition plates 55 and 66 so as not to enter into the multi-groove rollers 32 and 33. I have to.

JP-A-7-136922

  However, the conventional configuration has a problem that slurry and coolant are also removed by the partition plate, resulting in an increase in processing resistance.

  Also, if the cause of “wire jump” is the entry of foreign matter or workpiece pieces into the multi-slot roller, the “wire jump” should not occur when the multi-slot roller is rotated during non-machining. is there. However, those skilled in the art also experience “wire jumping” when not working. In other words, the conventional configuration has a problem that the occurrence of “wire jump” cannot be suppressed even if foreign objects or workpiece pieces are removed by the partition plates 55 and 66.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a wire saw capable of suppressing the occurrence of “wire jump” while preventing an increase in machining resistance.

  In order to achieve the above object, a wire saw according to the present invention travels a wire row in which a number of wires are wound between a plurality of multi-slotted rollers, and presses the workpiece against the wire row to process the workpiece. In the wire saw to be performed, the jig includes a jig in which a plurality of grooves are formed, and the jig is arranged so that each wire of the wire row runs one by one in each of the plurality of grooves. The width of each groove is larger than the diameter of the wire.

  As described above, according to the wire saw of the present invention, it is possible to suppress the occurrence of “wire jump” while preventing an increase in processing resistance.

The figure which shows the wire saw in this Embodiment Diagram showing “wire jump” (A) (b) The figure which shows the place where "wire jump" occurs when there is no work piece (A) (b) The figure which shows the occurrence place of "wire jump" when there is a work piece The figure which shows arrangement | positioning with the correction jig and wire row | line | column in this Embodiment (A) (b) The figure for demonstrating the effect | action of the correction jig | tool in this Embodiment. The figure which shows the mechanism which aligns the correction jig | tool in this Embodiment. The figure which shows the conventional wire saw described in patent document 1

  Hereinafter, the present embodiment will be described with reference to the drawings.

  FIG. 1 is a diagram showing a main part of a wire saw in the present embodiment. After the wire 1 extending from the supply-side spool is wound a plurality of times at a uniform pitch so as not to be folded around the drive-side multi-slot roller 3 and the driven-side multi-slot roller 4 to form a wire row To the collection side spool. A plurality of V-grooves are formed on the multi-groove rollers 3 and 4 at a uniform pitch, and one wire 1 is accommodated in each V-groove. The workpiece 2 is pressed against the wire row between the multi-groove rollers 3 and 4. The wire row is formed by winding a large number of one wire between a plurality of multi-slotted rollers. The correction jig 5 is installed on the side without the workpiece 2 between the multi-groove rollers 3 and 4 (lower side in the direction of gravity). The correction jig 5 is a jig useful for suppressing “wire jump”.

  The wire 1 moves in one direction or reciprocates. Alternatively, the wire 1 is fed out little by little from the supply side spool to the collection side spool while performing the cross-sewing movement. As a processing method, a free abrasive processing method for processing while supplying a suspension (slurry) in which abrasive grains (for example, SiC) are mixed to the wire 1, or diamond or the like that becomes abrasive grains is fixed by plating or resin. There is a fixed abrasive processing method in which the wire 1 is processed while supplying coolant. Either method can be applied to this embodiment.

  Here, “wire jump” will be described.

  FIG. 2 shows a state where “wire jump” occurs in the multi-groove roller 3. “Wire jump” refers to a phenomenon in which the wires 1 do not enter the V groove of the multi-slot groove roller 3 into which the wire 1 should originally enter, but the wires 1 enter multiple adjacent V grooves. Due to the occurrence of “wire jump”, the interval between the wire rows is shifted, and the sliced wafer does not have a uniform thickness, but has a sharp triangular shape. When processing proceeds in this state, the triangular portion with a sharp cross section of the wafer breaks, and the broken piece causes the wire 1 to break.

  This “wire jump” is likely to occur (place where it starts). It is in the vicinity of the multi-groove rollers 3 and 4. The reason for this will be described with reference to FIG.

  FIG. 3A shows the behavior of the wire 1 during acceleration. The wire 1 is wound around the multi-groove rollers 3 and 4 with a uniform tension T. At the time of acceleration, the multi-slot roller 3 as the main shaft acts so as to pull the multi-slot roller 4 as the slave shaft, so that the tension of the wire row above the gravitational direction is higher than the tension T2 of the wire row below the gravitational direction. T1 is lower. At this time, at a point in the vicinity where the wire 1 having a low tension is wound around the multi-slot groove roller 4 (a portion surrounded by a dotted line in the drawing), the wire row is expanded by the change in the tension. When the wire row swells, the “wire jump” occurs when the wire row moves in a direction perpendicular to the traveling direction. That is, a portion where the tension changes is a portion where “wire jump” is likely to occur as a result.

  FIG. 3B shows how the tension of the wire 1 changes during deceleration. Contrary to the acceleration, the tension T2 of the lower wire 1 is smaller than the upper tension T1. As a result, “wire jump” tends to occur on the lower side of the multi-slot groove roller (a portion surrounded by a dotted line in the figure).

  That is, when the multi-groove rollers 3 and 4 perform acceleration / deceleration, the tension of the wire 1 changes, and “wire jump” is likely to occur on the side where the wire tension is reduced. When the wire 1 traveling between the multi-groove rollers is wound around one multi-groove roller, the wire 1 moves in a direction perpendicular to the traveling direction of the wire 1 to cause “wire jump”. For this reason, if the movement of the wire 1 in the direction perpendicular to the traveling direction is suppressed, the occurrence of “wire jump” can be suppressed. At this time, it is more preferable to limit the movement of the wire 1 in the vicinity of the multi-groove roller, which is the place where “wire jump” is most likely to occur.

  Note that when the workpiece 2 is processed, the workpiece is pressed against the wire 1, and the place where “wire jump” is likely to occur changes. The workpiece 2 being processed descends from the upper side in the gravity direction to the lower side of the wire 1. At this time, the upper wire row is pressed downward by the workpiece 2. Therefore, the track of the upper wire row is fixed by the workpiece 2, and “wire jump” is less likely to occur in the upper wire row.

  Here, the mode at the time of deceleration of the wire 1 which advances to the direction of the arrow during the process of the to-be-processed object 2 is shown to Fig.4 (a). The relationship of the wire tension during the deceleration is (lower side) T2 <(upper side) T1. Further, the lower portion of the multi-slotted groove 3 as the main shaft is a place where the wire 1 starts to enter the multi-slotted groove, so that “wire jump” is most likely to occur.

  Further, as shown in FIG. 4B, when the wire 1 traveling in the direction of the arrow is accelerated, the relationship of the wire tension is also T2 <T1. Further, the lower portion of the multi-slot groove roller 4 which is the driven shaft is a place where the wire 1 starts to enter the multi-slot groove, so that “wire jump” is most likely to occur.

  4 (a) and 4 (b), it can be seen that during the processing of the workpiece 2, "wire jump" tends to occur below the upper side of the multi-groove rollers 3 and 4. Therefore, in the present embodiment, a jig for restricting the movement of the wire 1 in the direction perpendicular to the traveling direction is disposed only on the lower side of the multi-slot groove roller where “wire jump” is particularly likely to occur.

  Next, the correction jig 5 which is an example of a jig will be described with reference to FIG. FIG. 5 is a view taken in the direction of arrow A in FIG. A number of grooves are arranged on the correction jig 5 at the same pitch as the pitch p of the wire row formed by the wires 1. In order to accommodate the wire row in the groove, the groove depth d1 is made larger than the diameter of the wire 1. In the present embodiment, the groove depth d1 is set to the diameter of the wire 1 +0.5 mm in consideration of ease of manufacture and attachment adjustment.

  The width u of each groove is larger than the diameter of the wire 1. By this groove, the movement of the wire 1 in the direction orthogonal to the traveling direction can be restricted and the occurrence of “wire jump” can be prevented. At the same time, by setting the groove width u to be larger than the diameter of the wire 1, a space is created between the wire 1 and the groove, and the wire 1 can be run while sufficiently holding slurry and coolant. That is, the correction jig 5 having the groove width u larger than the diameter of the wire 1 can suppress the occurrence of “wire jump” and realize processing with low processing resistance.

  Furthermore, it is desirable that the width u of the groove provided in the correction jig 5 is larger than the diameter of the wire 1 by 0.02 mm or more. This is because if the width u of the groove is less than this, the wire 1 and the side wall of the groove come into contact with each other and the slurry and the like are removed. On the other hand, it is desirable that the width u of the groove is the diameter of the wire 1 +0.5 mm or less. If the groove width u is larger than the diameter of the wire 1 +0.5 mm, the gap between the grooves is narrowed, so that the side wall thickness (value of pu) becomes too thin and the trajectory of the wire 1 cannot be corrected. It is.

  The multi-groove rollers 3 and 4 have V-grooves, and the wires 1 are held in the V-grooves (see FIG. 2). The bottom of the V-groove is located on the center side of the multi-groove rollers 3 and 4, and the opening of the V-groove is located on the outer peripheral side of the multi-groove rollers 3 and 4. In order to hold the wire 1, the width of the opening of the V-groove is larger than the diameter of the wire 1. A “wire jump” occurs when the wire 1 jumps out of the V groove beyond the opening. In order to prevent this “wire jump”, the correction jig 5 may be operated so as to keep the wire 1 in the V-groove. The V groove has a shape in which the width gradually decreases from the opening toward the bottom. In order to prevent the wire 1 from jumping out of the V-groove, the width of the groove provided in the correction jig 5 may be made smaller than the opening of the V-groove of the multi-groove rollers 3 and 4. This is because the movement of the wire 1 can be restricted by the groove of the correction jig 5 before it jumps out of the opening of the V groove.

  Further, in this case, by making the width of the groove of the correction jig 5 larger than the diameter of the wire 1, “wire jump” can be suppressed without increasing the processing resistance. From the above, when summarizing the desirable requirements of the correction jig 5, the width of each groove of the plurality of grooves provided in the correction jig 5 is made smaller than the width of the opening of the V groove of the multi-groove rollers 3 and 4, And it will be larger than the diameter of the wire 1.

  In the present embodiment, for example, the diameter of the wire 1 is 0.1 mm, the wire pitch is 0.25 mm, and the groove width u is 0.12 mm. Further, the correction jig 5 shown in FIG. 1 has a width (w) of 30 mm, a thickness (t) of 5 mm, a total length (depth dimension of the paper surface) of 405 mm, and 5 mm longer than the wire row width.

  It is optimal to use cemented carbide, more specifically tungsten carbide, as the material of the correction jig 5. This is because cemented carbide is easy to process by wire electric discharge machining and has high hardness. Although the performance is inferior to cemented carbide, stainless steel, ceramics, CFRP (carbon fiber reinforced resin) or the like may be employed as the material of the correction jig 5.

  Although the example in which the correction jig 5 is installed at the lower two positions of the multi-groove rollers 3 and 4 is shown, the two correction jigs 5 may be integrally manufactured to cover the entire lower wire row. . By integrating, the alignment described later can be adjusted at a time.

  Next, the operation of the correction jig 5 will be described. FIG. 6A shows the correction jig 5 disposed in the vicinity of the multi-groove roller 3, and FIG. In FIG. 6B, only the grooves (hatched portions) formed on the surface of the correction jig 5 are drawn. The correction jig 5 is arranged so that each wire in the wire row travels one by one in each of the plurality of grooves provided in the correction jig 5. Even if an attempt is made to deviate from the original trajectory due to a change in tension of the wire 1, the trajectory is constrained by the correction jig 5, and the wire 1 fits in the V groove of the multi-groove roller 4 so as to be guided. Considering this action, it is desirable that the groove of the correction jig 5 is parallel to the wire 1 when the correction jig 5 is attached.

  Precise alignment adjustment is important for attaching the correction jig 5. Therefore, in the lower part of the correction jig 5, an example of a mechanism unit having an adjustment function of a total of 6 degrees of freedom of the three axes of x, y, and z, and the a, b, and c axes rotating around each axis. A certain stage 6 may be provided. Stage 6 is shown in FIG. Note that a mechanism portion that does not have six degrees of freedom and is omitted only for particularly important axes may be used.

  The stage 6 performs alignment so that the traveling direction of the wire 1 and the groove of the correction jig 5 are parallel and the wire 1 fits in the center of the groove. Thus, during normal wire travel, the grooves of the wire 1 and the correction jig 5 are not in contact with each other, and the processing resistance is not increased. On the other hand, when the trajectory of the wire 1 is disturbed due to a change in tension, the side wall of the groove of the correction jig 5 and the wire 1 are in contact with each other, thereby preventing the occurrence of “wire jump”. If the end of the straightening jig 5 is positioned so as to be about 5 mm inside (the position indicated by g in FIG. 1) from the vertical line passing through the rotation axis of the multi-groove rollers 3 and 4, it is effective for suppressing “wire jump”. The inventors have found that.

  Furthermore, you may have the control part 7 which corrects the alignment of the correction jig | tool 5 to the stage 6 during driving | running | working of a wire row | line. By correcting the alignment during traveling, the occurrence of “wire jump” can be further suppressed while the machining resistance is kept low.

  In addition, although the groove | channel which accommodates the wire 1 given to the correction jig 5 in this Embodiment was made into the U-shaped cross-sectional shape, a rectangular cross-sectional shape may be sufficient. Since the U-shaped groove is not restrained in the vertical direction when the wire 1 is accommodated in the groove, alignment adjustment is easy.

  The correction jig 5 may be arranged on the upper side of the wire row. However, since the “wire jump” hardly occurs on the upper side due to the presence of the workpiece 2, the correction jig 5 is arranged only on the lower side. Is desirable. By making the correction jig 5 only on the lower side, there is an advantage that the man-hour required for alignment adjustment can be minimized. As a more detailed arrangement, the wire row formed by the wires 1 forms a first wire row that runs horizontally, and a second wire row that is located below the first wire row in the direction of gravity, and The workpiece 2 is pressed against the first wire row from the upper side in the gravity direction, and the correction jig 5 is disposed only on the lower side in the gravity direction of the second wire row.

  The wire saw of the present invention can be applied to processing of semiconductors and metals.

1 Wire 2 Workpiece 3 Multi-Groove Roller 4 Multi-Groove Roller 5 Straightening Jig 6 Stage 7 Control Unit

Claims (5)

In a wire saw that runs a wire row in which a number of wires are wound between a plurality of multi-slot groove rollers, presses the workpiece against the wire row, and processes the workpiece,
Having a jig in which a plurality of grooves are formed;
The jig is arranged so that each wire of the wire row runs one by one in each of the plurality of grooves,
The wire saw, wherein a width of each of the plurality of grooves is larger than a diameter of the wire.   The wire saw according to claim 1, further comprising a mechanism that adjusts the alignment of the jig so that the wires and the plurality of grooves are not in contact with each other.   The wire saw according to claim 2, further comprising a control unit that causes the mechanism unit to correct the alignment of the jig while the wire row is traveling. The multi-groove roller is formed with a V-groove for holding the wire,
The wire saw according to any one of claims 1 to 3, wherein a width of each of the plurality of grooves of the jig is smaller than a width of an opening of the V groove. The wire row has a first wire row that runs horizontally, and a second wire row that is located below the first wire row in the direction of gravity,
The workpiece is pressed against the first wire row from above in the direction of gravity,
The wire saw according to any one of claims 1 to 4, wherein the jig is disposed only on a lower side in the gravity direction of the second wire row.

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