Method for restarting operation of wire saw

Abstract

Technical problem: The present invention provides a method for restarting the operation of a wire saw, wherein, in a wire saw using a fixed abrasive metal wire, when restarting the cutting of a workpiece that has been interrupted in the middle due to an abnormality such as wire breakage, the wire will not break due to the wire pulling the workpiece. Solution: A method for restarting the operation of a wire saw, the method being an operation restart method in the following case, wherein, in the operation of a wire saw that forms a metal wire array by winding a fixed abrasive metal wire having abrasive grains fixed on its surface onto a plurality of grooved rollers, and cutting and feeding the workpiece relatively against the metal wire array while reciprocating the fixed abrasive metal wire in an axial direction, thereby cutting the workpiece into a wafer shape, when the cutting of the workpiece is temporarily interrupted in the middle of the workpiece, the cutting of the workpiece is restarted, wherein the fixed abrasive metal wire after the abrasive grains have been worn away is arranged at the cutting position of the workpiece where the cutting of the workpiece was interrupted, and the cutting of the workpiece is restarted.

Description

Technical Field

[0001] The present invention relates to cutting of a workpiece by a metal wire, and more particularly to a method for resuming operation of a wire saw when cutting is interrupted. Background Art

[0002] Conventionally, wire saws are known as devices for slicing wafers from silicon ingots, compound semiconductor ingots, and the like. In such wire saws, for example, a free abrasive method is employed. Multiple cutting wires are wound around multiple rollers to form a wire array. These wires are then driven axially at high speed. A workpiece is fed into the wire array while slurry is appropriately supplied. The workpiece is then cut at the locations of the individual wires, thereby slicing multiple wafers simultaneously (Patent Document 1).

[0003] Here, Figure 2 An example of a common wire saw is shown. Figure 2 As shown, the wire saw 201 is mainly composed of the following components: a metal wire 202 (high-tension steel wire) for cutting the workpiece W, a grooved roller 103 wound with the metal wire 202, a tension adjustment mechanism 104 for adjusting the tension of the metal wire 202, a mechanism 105 for sending the workpiece W to be cut downward, and a mechanism 206 for supplying slurry during cutting.

[0004] The metal wire 202 is pulled out from a metal wire reel 107, passes through a traverse 108, a pulley 109 and a tension adjustment mechanism 104, is wound around a grooved roller 103 for about 300 to 500 turns, and then passes through another tension adjustment mechanism 104', a pulley 109' and a traverse 108' before being wound onto the metal wire reel 107'.

[0005] In addition, the grooved roller 103 is a roller in which polyurethane resin is pressed around a steel cylinder and grooves are cut on its surface at a roughly constant pitch. The wound metal wire 202 can be driven unidirectionally or reciprocatingly in the axial direction at a predetermined period by the grooved roller drive motor 110.

[0006] The wire reels 107 and 107 ′ are rotationally driven by wire reel drive motors 111 and 111 ′. The speeds of the grooved roller drive motor 110 and the wire reel drive motors 111 and 111 ′ are controlled to adjust the tension applied to the wire 202 .

[0007] In addition, if Figure 3 As shown, Figure 2 The mechanism 105 for feeding the workpiece W downward includes a workpiece holding device 114 composed of a workpiece holding portion 112 and a workpiece plate 113 . The workpiece W is bonded to the workpiece plate 113 via a joining member (beam) 120 attached to the workpiece W.

[0008] When the workpiece W is cut, the workpiece W is held and relatively pressed by the mechanism 105 that feeds the workpiece W downward, and is fed toward a wire array composed of the wire 202 wound around the grooved roller 103 .

[0009] In the wire saw 201, a suitable tension is applied to the wire 202 by the tension adjustment mechanism 104, 104', and the wire 202 is reciprocated in the axial direction by the wire roller drive motor 111, 111', while the slurry is supplied from the slurry supply mechanism 206, and the workpiece W is cut into and fed by the mechanism 105 that feeds the workpiece downward.

[0010] However, although the steel wire used in the wire saw is highly resistant to wear and tension, and a resin roller with a predetermined hardness is used as the grooved roller to prevent damage to the wire, the wire may sometimes break during cutting of the workpiece due to wear and fatigue over time, making it impossible to continue cutting the workpiece.

[0011] In this case, the conventional method is as follows: after the wire is separated from the workpiece cutting point, the broken wire section is connected to a new wire. The connected section is then reeled onto the wire reel 107' on the recovery side, and the rows of wire are engaged with the respective cutting points of the workpiece. The wire rows are then positioned at the workpiece cutting point at the time of the wire break, and the workpiece cutting process is resumed.

[0012] On the other hand, Figure 1 As shown, a method of cutting a workpiece using a fixed abrasive wire 402 in which diamond abrasive grains are fixed to the wire surface instead of a slurry containing abrasive grains is also known, and has been put into practical use in cutting small-diameter ingots with a diameter of approximately 150 mm or less.

[0013] In the cutting process performed by the fixed abrasive wire 402, Figure 1 As shown, instead of Figure 2 The steel wire 202 in the conventional wire saw 201 shown is replaced with a fixed abrasive wire 402. In addition, the wire saw 101 including the mechanism 106 for supplying cooling liquid is used. Figure 1 In the wire saw 101 shown, the mechanism 106 supplies the wire to Figure 2 The slurry of the conventional wire saw 201 shown is changed to a coolant such as cooling water that does not contain abrasive grains. In this way, the conventional wire saw can be used as it is for cutting by the fixed abrasive wire 402.

[0014] Fixed abrasive metal wire may also break. Like free abrasive metal wire, the following method must be used: the metal wire must be separated from the workpiece cutting point, and the broken part is connected with the new wire, and the connected part is wound to the metal wire reel 107' on the recovery side, and each column of metal wire is correspondingly engaged with each cutting point of the workpiece, and the metal wire column is arranged at the workpiece cutting position when the wire is broken to restart the cutting of the workpiece.

[0015] Prior art literature

[0016] Patent Literature

[0017] Patent Document 1: Japanese Patent Application Laid-Open No. 9-262826 Summary of the Invention

[0018] (1) Technical issues to be resolved

[0019] In the case of using the above-mentioned free abrasive wire saw, due to the Figure 4 As shown in (a), a gap (spacing) of the width of the free abrasive grains G is formed between the metal wire 202 and the workpiece W, so it is relatively easy to make each row of metal wires correspondingly engage with each cutting point of the workpiece and arrange the metal wire rows at the cutting position of the workpiece when the wire breaks. Figure 4 As shown in (b), when using the fixed abrasive wire saw, since there is no gap between the fixed abrasive wire 402 and the workpiece W, it is difficult to make each row of the wire correspond to each cutting position of the workpiece.

[0020] In addition, if the wire is pulled too far against the workpiece, it may break, which requires re-winding the wire and requiring additional space for rewinding the fixed abrasive wire, resulting in significant losses.

[0021] The present invention is made in view of the problems as described above, and its purpose is to provide a method for restarting the operation of a wire saw. In this method, when cutting a workpiece by a wire saw using a fixed abrasive metal wire, even if the cutting of the workpiece is interrupted in the middle due to an abnormality such as metal wire breakage, the metal wire can be returned to the cutting position of the workpiece, and the metal wire will not break when it is set to the cutting position.

[0022] (2) Technical solution

[0023] In order to achieve the above-mentioned purpose, the present invention provides a method for resuming operation of a wire saw, which is an operation resuming method in the following situation, wherein a metal wire array is formed by winding a fixed abrasive metal wire with abrasive grains fixed on the surface onto a plurality of grooved rollers, and the workpiece is cut into a wafer shape by reciprocating the fixed abrasive metal wire in the axial direction while the workpiece is relatively pressed against the metal wire array for cutting-in feeding. During the operation of the wire saw, the cutting of the workpiece is temporarily interrupted in the middle of the workpiece, and then the cutting of the workpiece is restarted, wherein the fixed abrasive metal wire after the abrasive grains are worn is arranged at the cutting position of the workpiece where the cutting of the workpiece was interrupted, and the cutting of the workpiece is restarted.

[0024] In the wire saw operation restart method of the present invention, since a gap can be formed between the workpiece and the metal wire by wearing away the abrasive grains of the fixed abrasive metal wire, it is easy to engage each column of the metal wire with each cutting point of the workpiece, thereby preventing the metal wire from breaking when the metal wire is set to the cutting position.

[0025] In addition, at this time, preferably, when the diameter of the core wire of the fixed abrasive metal wire is set to R, the diameter of the fixed abrasive metal wire as a new wire is set to R1, and the diameter of the metal wire after the abrasive is worn is set to R2, the fixed abrasive metal wire after the abrasive is worn is arranged at the cutting position of the workpiece where the cutting of the workpiece is interrupted, and the cutting of the workpiece is restarted.

[0026] According to this method, since the abrasive grains of the fixed abrasive wire are worn away, a gap is formed between the workpiece and the wire. This makes it easier to align each row of wires with each entry point of the workpiece, thereby preventing wire breakage when the wires are positioned at the entry point. When the wire rows are positioned at the entry point of the workpiece where they would break, they avoid contact with the workpiece and the resulting pull, thus preventing saw marks on the cut surface of the workpiece and any degradation of warp quality.

[0027] In addition, at this time, preferably, when the diameter of the metal wire after the abrasive wear of the fixed abrasive metal wire is set to R3, which is different from the R2, the fixed abrasive metal wire after the abrasive wear is arranged at a position between the fixed abrasive metal wire after the abrasive wear that satisfies R2 and the supplied new wire, and the cutting of the workpiece is restarted.

[0028] According to this method, since the abrasive wear of the fixed abrasive wire creates a gap between the workpiece and the wire, it is easier to align the rows of wires with the workpiece's respective cut points when the wire is positioned at the cut point, further preventing wire breakage. When the rows of wires are positioned at the workpiece's cut point when wire breakage occurs, they avoid contact and pull on the workpiece, thus preventing saw marks on the cut surface and deterioration in warp quality. Furthermore, since the wire diameter fluctuates minimally, the load on the wire during cut does not increase dramatically, thus preventing wire breakage when resuming cutting.

[0029] In addition, at this time, it is preferable to relatively press the grindstone against the fixed abrasive grain wire to wear the abrasive grains.

[0030] This method effectively removes fixed abrasive grains from the surface of the fixed abrasive wire, making it easier to return the wire to the workpiece cutting position. This makes it easier to control the wire diameter to prevent wire breakage when restarting the process, further reducing the risk of the wire pulling on the workpiece, causing saw marks, deteriorating workpiece quality, or causing wire breakage.

[0031] In addition, in this case, it is preferable to use a WA (White Alundum) grindstone as the grindstone.

[0032] This type of grindstone effectively removes fixed abrasive grains from the surface of the fixed abrasive wire, making it easier to return the wire to the workpiece cutting position. This makes it easier to control the wire diameter to prevent wire breakage when restarting the operation, further reducing the risk of the wire pulling on the workpiece, causing saw marks, deteriorating workpiece quality, and causing wire breakage.

[0033] (3) Beneficial effects

[0034] As described above, since the abrasive wear of the fixed abrasive wire creates a gap between the workpiece and the wire, it is easier to align each row of wires with the workpiece's incision points, thus preventing wire breakage when positioning the wires at the incision points. When the wire rows are positioned at the workpiece incision points where they would otherwise break, they avoid contact and pull on the workpiece, thus preventing saw marks on the cut surface and deterioration in warp quality. Furthermore, since the wire diameter fluctuates minimally, the load on the wire during incision does not increase dramatically, thus preventing wire breakage when resuming cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 An example of a fixed abrasive wire saw is shown.

[0036] Figure 2An example of a wire saw showing the loose abrasive method.

[0037] Figure 3 Displays the mechanism that sends the workpiece downward.

[0038] Figure 4 A cross-sectional view of the workpiece and the wire is shown when the wire is positioned at the workpiece cutting position in order to resume cutting of the workpiece.

[0039] Description of Reference Numerals

[0040] 101…wire saw (fixed abrasive method); 103…grooved roller; 104, 104'…tension adjustment mechanism; 105…mechanism for sending the workpiece downward; 106…mechanism for supplying cooling liquid; 107, 107'…wire reel; 108, 108'…cross arm; 109, 109'…pulley; 110…grooved roller drive motor; 111, 111'…wire reel drive motor; 112…workpiece holding portion; 113…workpiece plate; 114…workpiece holding device; 120…joining component (beam); 201…wire saw (free abrasive method); 202…metal wire (high-tension steel wire); 206…mechanism for supplying slurry; 402…fixed abrasive metal wire; W…workpiece; G…abrasive DETAILED DESCRIPTION

[0041] The present invention will be described in detail below, but the present invention is not limited thereto.

[0042] As described above, when a wire saw with fixed abrasive is used, since there is no gap between the fixed abrasive metal wire 402 and the workpiece W, it is difficult to make each column of the metal wire correspond to the cutting position of the workpiece when the metal wire is set to the cutting position. Therefore, a method is sought to prevent the metal wire from breaking.

[0043] The inventors of the present invention have repeatedly studied the above-mentioned problems and found that a method for restarting the operation of a wire saw can suppress the occurrence of wire breakage when the wire is set to a cutting position, thereby completing the present invention. The method is an operation restart method in the following situation, in which a metal wire array is formed by winding a fixed abrasive metal wire with abrasive grains fixed on the surface onto a plurality of grooved rollers, and the workpiece is cut into and fed relative to the metal wire array while the fixed abrasive metal wire is moved back and forth in the axial direction, thereby cutting the workpiece into a wafer shape. During the operation of the wire saw, the cutting of the workpiece is temporarily interrupted in the middle of the workpiece and then the cutting of the workpiece is restarted, wherein the fixed abrasive metal wire after the abrasive grains are worn out is arranged at the cutting position of the workpiece where the cutting of the workpiece was interrupted.

[0044] Hereinafter, description will be given with reference to the accompanying drawings.

[0045] In the case of using a free abrasive wire saw, Figure 4 As shown in (a), since a gap (pitch) of the width of the free abrasive grains G is formed between the metal wire 202 and the workpiece W, it is relatively easy to make each row of metal wires correspondingly engage with each cutting point of the workpiece, and to arrange the metal wire rows at the cutting position of the workpiece when the wire breaks. Figure 4 As shown in (b), when the fixed abrasive wire saw is used, since there is no gap between the fixed abrasive wire 402 and the workpiece W, it is difficult to make each row of wires correspond to each cutting position of the workpiece.

[0046] Therefore, the inventors of the present invention have discovered a method for resuming operation of a wire saw, which is a method for resuming operation in the following situation, wherein a metal wire array is formed by winding a fixed abrasive metal wire with abrasive grains fixed on the surface onto a plurality of grooved rollers, and the workpiece is cut into a wafer shape by reciprocating the fixed abrasive metal wire in the axial direction while pressing the workpiece relative to the metal wire array for cutting-in feeding. During the operation of the wire saw, the cutting of the workpiece is temporarily interrupted in the middle of the workpiece and then the cutting of the workpiece is resumed. The method is characterized in that the fixed abrasive metal wire after the abrasive grains are worn is arranged at the cutting position of the workpiece where the cutting of the workpiece was interrupted, and the cutting of the workpiece is resumed.

[0047] In the wire saw operation restart method of the present invention, a gap can be formed between the workpiece and the metal wire by wearing away the abrasive grains of the fixed abrasive metal wire. Therefore, it is easy to engage each column of the metal wire with each cutting point of the workpiece, and the metal wire can be prevented from breaking when being set to the cutting position.

[0048] Furthermore, the present inventors have discovered that, when the diameter of the core wire of a fixed abrasive wire is set to R, the diameter of the new fixed abrasive wire is set to R1, and the diameter of the wire after abrasive wear is set to R2, and R2 is set so that the abrasive wear fixed abrasive wire is positioned at the workpiece cutting position where cutting of the workpiece is interrupted, such that R2 satisfies R≦R2≦R+(R1-R)×0.1, wire breakage can be further suppressed. Furthermore, since the wire does not come into contact with the workpiece and pull it, the occurrence of saw marks on the cut surface of the workpiece and the deterioration of warp quality can be suppressed.

[0049] Furthermore, during the investigation, it was discovered that while there were no problems until the wire was positioned at the workpiece cutting position, the wire sometimes broke again immediately after operation was resumed.

[0050] Investigation of the wire breakage revealed that the wire broke during passage through the workpiece near the boundary between the portion where the fixed abrasive wire had been worn to meet the R2 diameter and the new wire. The present inventors speculate that the significant difference in wire diameter between the portion where the fixed abrasive wire had been worn and the new wire caused the wire to penetrate the workpiece more deeply before and after the step, dramatically increasing the load on the wire and causing wire breakage.

[0051] Therefore, the inventors of this case have discovered a method for resuming operation of a wire saw as a method for preventing wire breakage again when the operation is resumed. When the diameter of the metal wire after the abrasive wear of the fixed abrasive metal wire is set to R3, which is different from R2, the fixed abrasive metal wire after the abrasive wear that satisfies R2<R3≦R2+(R1-R)×0.5 is arranged at a position between the fixed abrasive metal wire after the abrasive wear that satisfies R2 and the new wire supplied, and the cutting of the workpiece is resumed.

[0052] According to such a method, as the wire travels through the workpiece, the wire diameter is The order of the wire diameter increases, so the change in the wire diameter is smaller than When the metal wires are engaged in the order of cutting, the load applied to the metal wire will not increase sharply, thereby preventing the metal wire from breaking.

[0053] In addition, preferably, a grindstone is pressed against the fixed abrasive wire to wear the abrasive grains. In addition, preferably, a WA (White Alundum) grindstone is used as the grindstone.

[0054] If such a method of resuming operation is used, the fixed abrasive grains on the surface of the fixed abrasive metal wire can be effectively removed, and the metal wire can be more easily returned to the cutting position of the workpiece. Moreover, the diameter of the metal wire can be easily controlled so that the wire will not break again when the metal wire is set to the cutting position and when the operation is restarted.

[0055] Example

[0056] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto.

[0057] Use as Figure 1 The wire saw shown starts cutting a cylindrical workpiece under the common conditions shown in Table 1, interrupts the cutting process midway, then removes the wire from the workpiece where it entered and feeds it to a reel on the recovery side until the unused portion of the wire reaches the workpiece.

[0058] Table 1

[0059]

[0060] (Example 1)

[0061] Try using the grindstone in Table 2. After wearing the metal wire to each condition in Table 3, make each column of the metal wire correspondingly engage with each cut-in position of the workpiece, and arrange the metal wire columns at the workpiece cut-in position when the cutting is interrupted.

[0062] Table 2

[0063]

[0064] Table 3

[0065]

[0066] (Comparative Example)

[0067] Try not to wear the metal wire, and make each column of the metal wire correspondingly engage with each cut-in position of the workpiece, and arrange the metal wire columns at the workpiece cut-in position when the workpiece cutting is interrupted.

[0068] The results of Example 1 and the comparative example are shown in Table 4. In the comparative example, saw marks and metal wire breakage occurred. For Example 1, under any conditions, no metal wire breakage occurred. When the conditions 3 - 5 of "R≦R2≦R+(R1 - R)×0.1" were satisfied, neither saw marks nor metal wire breakage occurred.

[0069] Table 4

[0070]

[0071] (Example 2)

[0072] Try using the grindstone in Table 2. After wearing the metal wire to each condition in Table 5, make each column of the metal wire correspondingly engage with each cut-in position of the workpiece, and arrange the metal wire columns at the workpiece cut-in position when the cutting is interrupted, and then start cutting.

[0073] Table 5

[0074]

[0075] The results of Example 2 are shown in Table 6. When the conditions 3 - 5 of "R2 < R3≦R2+(R1 - R)×0.5" were satisfied, no wire breakage occurred when restarting the operation.

[0076] Table 6

[0077]

[0078] The present invention is not limited to the above-described embodiments, which are merely examples, and any solution having substantially the same configuration and producing the same effects as the technical concept described in the claims of the present invention is included within the technical scope of the present invention.

Claims

1. A method for resuming operation of a wire saw, wherein the wire saw is operated by winding a fixed abrasive wire having abrasive grains fixed to its surface around a plurality of grooved rollers to form a wire array, and by cutting a workpiece into a wafer shape by relatively pressing the fixed abrasive wire against the wire array while reciprocating the fixed abrasive wire in an axial direction. When the cutting of the workpiece is temporarily interrupted in the middle of the workpiece, the cutting of the workpiece is restarted, characterized in that The fixed abrasive wire after the abrasive grains have been worn away is arranged at the cutting position of the workpiece where the cutting of the workpiece was interrupted, and the cutting of the workpiece is resumed. When the diameter of the core wire of the fixed abrasive metal wire is set to R, the diameter of the fixed abrasive metal wire as a new wire is set to R1, and the diameter of the metal wire after the abrasive grains are worn is set to R2, R2 satisfies R≦R2≦R+(R1-R)×0.1, and the fixed abrasive metal wire after the abrasive grains are worn is arranged at the cutting position of the workpiece where the cutting of the workpiece is interrupted, and the cutting of the workpiece is restarted.

2. The method for resuming operation of a wire saw according to claim 1, wherein: When the diameter of the metal wire after the abrasive wear of the fixed abrasive metal wire is set to R3, which is different from R2, the fixed abrasive metal wire after the abrasive wear is arranged at a position between the fixed abrasive metal wire after the abrasive wear that satisfies R2 and the supplied new wire, and the cutting of the workpiece is restarted.

3. The method for resuming operation of a wire saw according to claim 1 or 2, characterized in that: A grindstone is pressed against the fixed abrasive grit wire to wear the abrasive grit away.

4. The method for resuming operation of a wire saw according to claim 3, wherein: A white corundum grinding stone was used as the grinding stone.

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