JP3741305B2 - Wire saw and method for controlling wire tension thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire saw and a wire tension control method for the wire saw, and more particularly to a wire saw for controlling a tension of an ingot cut of a wire laid between groove rollers and a wire tension control method thereof.
[0002]
[Prior art]
In the wire saw, an ingot cutting wire led out from a wire feeding reel (or bobbin) of a feeding device is wound around a plurality of wire saw groove rollers in a coil shape, and then the wire winding of the winding device is performed. The device configuration is such that it is wound on a take-up reel (or bobbin).
In the basic structure of these groove rollers, the outer peripheral surface of a cylindrical base metal is coated with a lining material (urethane rubber) having a predetermined thickness, and a wire groove is formed on the outer peripheral surface of the urethane rubber.
At the time of cutting the single crystal silicon ingot by the wire saw, the ingot is relatively pressed against the wire row that is traveling reciprocally while supplying slurry-like abrasive liquid containing loose abrasive grains to the wrapping oil. Thereby, an ingot is cut | disconnected to many wafers with the grinding effect | action of an abrasive grain.
[0003]
[Problems to be solved by the invention]
By the way, between the groove rollers, one long wire is wound about 350 to 450 times. As a result, a wire row having a shape in which one wire is bundled in a horizontal row appears.
At that time, the wire was wound between the groove rollers with a tension of 20 to 40 N per winding. Thereby, each groove roller was fastened in the direction between the rollers with a large force of about 1 t, and the distance between the rollers was shorter than before the wire was wound.
[0004]
By the way, if the wire is new, variation in the tension of the wire hardly occurs in the axial direction of the groove roller. However, if the ingot is cut for a long time, wear on the winding side of the wire becomes severe. As a result, the tension of the wire is reduced as compared with the new line, and the distance between the groove rollers is increased.
As described above, when the displacement of the distance between the rollers is increased, it is generally expected that the wear of the wire is increased. When this phenomenon occurs, there is a concern that the wire will loosen and the ingot cutting accuracy will decrease. In addition, this large distance displacement also occurs when an abnormality occurs in the spindle of the groove roller.
[0005]
Therefore, as a result of earnest research over a long period of time, the inventor detects the distance between the groove rollers during ingot cutting, and adjusts the tension of the wire wound between the rollers based on the detected value, thereby The present invention was completed by discovering that it is possible to prevent a decrease in cutting accuracy of the ingot due to loosening.
Further, the present invention has been completed by discovering that the abnormality of the spindle of the groove roller can be detected at an early stage by monitoring the distance between the groove rollers during ingot cutting.
[0006]
OBJECT OF THE INVENTION
The present invention can suppress a decrease in cutting accuracy of an ingot caused by the elongation of a wire, and can also detect an abnormality of a spindle of a groove roller for a wire saw at an early stage, and a wire tension control method used therefor The purpose is to provide.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a plurality of wire saw groove rollers in which a plurality of wire grooves on which wires are laid are engraved on each outer peripheral surface, and a feeding device that feeds the wires to these wire saw groove rollers; A winding device that winds the wire led out from the wire saw groove roller, and drives the feeding device and the winding device to reciprocate the wire spanned between the wire saw groove rollers to move the ingot. In the wire saw to be cut, the distance between the axes of the wire saw groove roller is detected during the cutting of the ingot, and the driving of the feeding device and / or the winding device is controlled based on the detected value, thereby controlling the wire tension. Wire saw to be adjusted.
[0008]
The kind of wire saw to which this invention is applied is not limited. For example, an ingot may be moved to press and contact the wire row and cut. On the contrary, the wire row may be moved to press and contact the ingot and cut. Further, the lower surface of the ingot may be in contact with the upper part of the wire row. Further, the upper surface of the ingot may be pressed against the lower part of the wire row.
Examples of the ingot cut by the wire saw include a silicon single crystal, a compound semiconductor single crystal, a magnetic material, quartz, and ceramics.
As the abrasive liquid used for cutting, for example, a well-known one containing abrasive grains such as SiC having an average particle diameter of 5 to 50 μm can be used.
[0009]
The number of wire saw groove rollers assembled and arranged in the wire saw is not limited as long as it is plural. For example, two may be sufficient and three or more may be sufficient.
The structure of the wire saw groove roller is not limited. Usually, the outer peripheral surface of a cylindrical base metal is covered with a lining material (urethane rubber) having a predetermined thickness, and a wire groove is formed on the outer peripheral surface of the lining material.
[0010]
According to a second aspect of the present invention, there is provided a detection unit that detects a distance between the axes of the wire saw groove rollers during the cutting of the ingot, and when the detection value by the detection unit is larger than a reference value, Control for decreasing the feeding speed of the wire and / or control for increasing the winding speed of the wire to the winding apparatus, and control for increasing the feeding speed of the wire from the feeding apparatus when the detected value is smaller than the reference value. And / or a wire saw according to claim 1, further comprising tension control means for performing control for reducing the winding speed of the wire to the winding device.
The detection unit is not limited as long as it can detect the distance between the axes of the wire saw groove rollers. For example, various sensors such as a capacitance type displacement sensor can be arranged close to the axis.
[0011]
The method for measuring the distance between the axes of the wire saw groove rollers is not limited. For example, the distance between the axes of the wire saw groove rollers may be measured directly. In addition, in any wire saw groove roller or all wire saw groove rollers, the displacement of the roller axis due to the elongation of the wire during ingot cutting is measured, and the distance between the axes of the wire saw groove roller is indirectly determined from this measured value. It may be detected. Further, in any wire saw groove roller or all wire saw groove rollers, the displacement of the roller axis may be measured only on the wire winding side. On the contrary, the displacement of the roller axis may be measured only on the winding end side of the wire. Further, in order to control the tension of the wire with higher accuracy, the displacement of the roller axis may be measured on the wire winding side and the wire winding end side.
[0012]
The reference value means one specific value of the wire tension that can cut the ingot well, and also means a specific range of the wire tension that can cut the ingot well. Therefore, when the value of this specific range is indicated, the wire is tensioned if the detected value of the distance between the groove rollers is larger than the upper limit reference value, and conversely if the detected value is smaller than the lower limit reference value, the wire is tensioned. The control of loosening is performed.
The specific configuration of the tension control means is not limited. In short, when the detected value exceeds the reference value, the wire feeding speed of the feeding device is lowered and the wire winding speed to the winding device is increased, or one of them is controlled. When the detected value is lower than the reference value, the wire feeding speed of the feeding device is increased and the winding speed of the wire to the winding device is decreased, or either one of them can be controlled. I can do it.
[0013]
The invention according to claim 3 is a wire tension control method of a wire saw for controlling the tension during ingot cutting of a wire spanned between a plurality of wire saw groove rollers in the wire saw. The distance between the axes of the wire saw groove roller is detected, and when the detected value is larger than the reference value, the tension of the wired wire is increased, and when the detected value is smaller than the reference value, This is a wire tension control method for a wire saw that reduces the tension of the wire.
As a specific tension control method for such wire elongation, for example, a method using the above-described tension control means may be used.
For example, in order to increase the wire tension, the control may be merely to lower the feeding speed of the wire from the feeding device to the wire saw groove roller, or only to increase the winding speed of the wire from the wire saw groove roller to the winding device. Control may be used.
[0014]
[Action]
According to the first to third aspects of the present invention, the distance between the axes of the wire saw groove rollers is detected during ingot cutting.
That is, when the wire is worn by cutting the ingot, the wire is extended. As a result, the clamping force between the wire saw groove rollers by the wire is reduced, and the distance between the roller axes is increased. When the detection unit detects this state, the tension of the wire is increased until it returns to the reference value.
By controlling in this way, it is possible to suppress a decrease in ingot cutting accuracy due to the elongation of the wire.
In addition, the detection of the looseness of the wire leads to early detection of an abnormality in the spindle of the wire saw groove roller.
[0015]
In particular, according to the second aspect of the present invention, when the detection value of the detection unit is larger than a preset reference value, the wire feeding speed from the feeding device is controlled by a command from the tension control means. The tension of the wire is increased by lowering, increasing the winding speed of the wire around the winding device, or controlling both of these wire speeds.
In addition, when the detected value is smaller than the reference value, the wire feeding speed from the feeding device is increased or the wire winding speed to the winding device is decreased according to a command from the tension control means. The wire tension is reduced by controlling the wire speed.
Of these, in the case of control in which the feeding speed of the wire from the feeding device to the groove roller and the winding speed of the wire from the groove roller to the winding device are simultaneously performed in accordance with the variation in the distance between the axes of the groove rollers. Compared to simply stopping the feeding speed of the wire from the feeding device or stopping the winding speed of the wire to the winding device, the tension control of the wire wound between the groove rollers can be performed in a short time. It can be carried out. In addition, the control accuracy can be improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view of a main part of a wire saw according to a first embodiment of the present invention.
In FIG. 1, reference numeral 10 denotes a wire saw according to a first embodiment of the present invention. This wire saw 10 is an apparatus for cutting a single crystal silicon ingot I pulled by a CZ method into a plurality of wafers. . The wire saw 10 has three groove rollers 12 arranged in an inverted triangle shape when viewed from the front. Between these groove rollers 12, one wire 11a is wound at a constant pitch so as to be parallel to each other. As a result, the wire row 11 appears between the groove rollers 12. The wire row 11 is reciprocated between the three groove rollers 12 by a drive motor. The middle of the two groove rollers 12 arranged on the upper side is the cutting position of the ingot I. Above the both side portions of the cutting position, for example, a pair of abrasive liquid supply units (not shown) for continuously supplying the abrasive liquid onto the wire row 11 are provided.
In the internal space between these three groove rollers 12, an end material receiving member (not shown) that normally has an upward U shape and receives the end material of the ingot I from below is accommodated.
[0017]
The wire 11a is led out from the bobbin 20 of the feeding device 13, and is passed over these groove rollers 12 through a guide roller (not shown) on the supply side, and then a guide roller (not shown) on the lead side. Is wound around the bobbin 21 of the winding device 15. The rotation shafts of the feeding device 13 and the winding device 15 are connected to the output shafts of the drive motors 16 and 17, respectively.
When the drive motors 16 and 17 are periodically driven, the bobbins 20 and 21 pivotally supported by the pair of bearings 18 rotate in the clockwise direction or the counterclockwise direction in FIG. 1 about the respective axis lines. Thus, the wire 11a reciprocates.
[0018]
In FIG. 1, reference numeral 19 denotes a lifting platform for the ingot I, and 19 a a carbon bed for fixing the ingot I to the lifting platform 19. 60 is a control device for the entire wire saw 10, 61 is incorporated in the control device 60, and adjusts the tension of the wire 11 a wound between the groove rollers 12 based on detection signals from the detection units S 1 and S 2. And tension control means for preventing a decrease in cutting accuracy of the ingot I due to loosening of the wire 11a. These control device 60 and tension control means 61 are configured using a known computer.
Capacitance displacement sensors are employed for the detection units S1 and S2.
Among these, the detection part S1 on the wire introduction side detects the displacement of the interval d1 between the shaft part 40a on the wire introduction side of the groove roller 12 and the detection part S1. On the other hand, the detection unit S2 on the wire lead-out side detects the displacement of the interval d2 between the shaft part 40b on the wire lead-out side of the groove roller 12 and the detection unit S2.
In the memory of the control device 60, the upper limit reference value Xa of the interval d1, the lower limit reference value Xb of the interval d1, and the interval d2 based on the values of the intervals d1 and d2 measured before the ingot I is cut in advance. The upper limit reference value Ya and the lower limit reference value Yb of the interval d2 are stored.
[0019]
Next, the groove roller 12 according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 2 is an enlarged cross-sectional view of a wire saw groove roller incorporated in a wire saw according to a first embodiment of the present invention.
Here, the groove roller (driving side groove roller) 12 disposed on the lower side of the three groove rollers 12 is taken as an example. Similarly, the remaining two groove rollers 12 (driven-side groove rollers) 12 may be provided with the detecting portions S1 and S1 outside the shaft portions 40a and 40b, respectively.
As shown in FIG. 2, the groove roller 12 is pivotally supported between a pair of bearings 30 and 31 arranged at a predetermined interval.
Each bearing 30, 31 has a cylindrical casing 32 fixed to an external member via a connecting plate. An inner sleeve 33 is fitted in the cylindrical casing 32. Inside the inner sleeve 33, spindles 35 and 36 are mounted via six bearings 34 so as to be rotatable in the circumferential direction. Further, a water cooling jacket is disposed between the outer surface of the inner sleeve 33 and the inner surface of the cylindrical casing 32 to prevent these heating.
[0020]
The groove roller 12 has a thick cylindrical base metal 12A made of SUS. The outer peripheral surface of the base metal 12A is covered with a urethane rubber lining material 12c having a thickness of 5 to 20 mm. A large number of wire grooves 12a, which are parallel grooves with a short pitch, are formed on the outer peripheral surface of the urethane rubber 12c.
Further, a relatively thin roller reinforcing cylinder 39 is fitted from the central part of the base metal 12A to the vicinity of both ends. However, the roller reinforcing cylinder 39 is not always necessary.
Further, a sleeve end plate 40 made of SUS is also fitted into both ends of the base metal 12A. Shaft portions 40a and 40b whose tip portions are gradually tapered are integrally formed at the center portion of the outer end surface of each sleeve end plate 40. Among these, the introduction side of the wire 11a is the shaft portion 40a, and the lead-out side of the wire 11a is the shaft portion 40b. Both shaft portions 40a and 40b are fitted into a concave fitting portion formed in a recessed manner at the end surface central portion of the spindle 35 or 36 on the groove roller 12 side. As a result, the left and right spindles 35 and 36 and the central groove roller 12 rotate integrally.
A pair of detectors S1 and S2 for detecting the distance between the groove rollers 12 during ingot cutting are disposed inside the wire saw from both shaft portions 40a and 40b. Here, the inside of the wire saw means that the direction is between the groove rollers 12 rather than the two shaft portions 40a, 40b. Further, it is assumed that the interval d1 and the interval d2 are set to the same distance before the ingot I is cut.
[0021]
Next, based on FIGS. 1-3, the cutting method of the ingot I by this wire saw 10 is demonstrated. FIG. 3 is a flowchart showing a wire tension control method according to the first embodiment of the present invention.
As shown in FIGS. 1 and 2, the wire saw 10 rotates the bobbin 20 of the feeding device 13 by the drive motor 16 while supplying the abrasive liquid from the abrasive liquid supply unit, and the wire 11a is used as a supply-side guide roller. Then, while being supplied to the groove roller 12, the bobbin 21 of the take-up reel 15 is rotated by the drive motor 17, and the wire 11a is taken up through the groove roller 12 and the guide roller on the lead-out side. And the wire 11a is reciprocated by changing the rotation direction of each bobbin 20 and 21 suitably.
[0022]
At this time, the drive side groove roller 12 is rotated by a rotation motor (not shown) to reciprocate the wire row 11. Along with this, the other two driven-side groove rollers 12 rotate between the bearings 30 and 31, and both guide rollers also rotate.
During the reciprocating traveling of the wire row 11, the ingot I is pressed against the wire row 11 from above. Thereby, the ingot I is cut into several wafers. That is, when the wire row 11 reciprocates, the loose abrasive grains in the abrasive liquid are rubbed against the bottom of the cutting groove by the wire 11a of the wire row 11 so that the bottom portion is gradually scraped, and finally a large number of sheets Cut into thin wafers.
[0023]
When the ingot I is cut by the wire saw 10 for a long period of time, the pressing force of the ingot I increases the wear on the winding side of the wire 11a. As a result, the tension of the wire 11a is reduced as compared with the new line, and the distance between the groove rollers 12 is increased. This is detected by the detectors S1 and S2 as displacements of the interval between the shaft 40a and the detector S1 and the interval d2 between the shaft 40b and the detector S2. Hereinafter, the method for controlling the tension of the wire 11a during ingot cutting will be described in detail with reference to the flowchart of FIG.
[0024]
First, in step 101, initialization of the memory and the like is performed. Next, the reference values Xa, Xb, Ya, Yb set and stored in advance from the memory of the control device 60 are read (step 102). During the ingot cutting, the interval d1 between the shaft portion 40a and the detection portion S1 is always detected by the detection portion S1, and these detection signals are sent to the tension control means 61 (step 103). Further, the distance d2 between the shaft part 40b and the detection part S2 is also detected from the detection part S2, and the detection signal is sent to the tension control means 61 (step 104). At this time, the detected value of the interval d1 is X1, and the detected value of the interval d2 is Y1. In addition, at the time of a new wire, the detected value X1 exists in the range from the upper limit reference value Xa to the lower limit reference value Xb in the memory of the control device 60, and the detected value Y1 is from the upper limit reference value Ya to the lower limit reference value Yb. Exists in range.
[0025]
Next, the obtained detection value X1 is compared with the upper limit reference value Xa (step 105). If the ingot I is cut for a long time, the wire 11a is worn and the tension is weakened. Then, the groove roller 12 moves outward by that amount. When this state occurs on the feeding side of the groove roller 12, the shaft portion 40a is separated from the detection portion S1, and the detection value X1 becomes larger than the upper limit reference value Xa. In this case, the process proceeds to step 106, where the detected value Y1 is compared with the upper limit reference value Ya to determine whether or not the wire 11a is stretched on the winding side of the groove roller 12. On the other hand, if the detected value X1 is below the upper limit reference value Xa, the process proceeds to step 111.
In step 106, if the wire 11a is extended due to wear, the shaft portion 40b is separated from the corresponding detection portion S2, and the detection value Y1 becomes larger than the upper limit reference value Ya. That is, the wire 11a is stretched on both the feeding side and the winding side of the groove roller 12. In this case, a command is issued from the tension control means 61 to tension the wire 11a to the feeding device 13 and the winding device 15 (step 107).
Therefore, the rotation speed of the drive motor 16 is lowered by this command, and the feeding speed of the wire 11a supplied from the feeding device 13 to the groove roller 12 is lowered. In addition, a command to increase the rotational speed is issued from the tension control means 61 to the drive motor 17, and the winding speed of the wire 11a from the groove roller 12 to the winding device 15 is increased. Thus, the tension of the wire 11a is enhanced on both the feeding side and the winding side of the groove roller 12.
[0026]
If the detected value Y1 is below the upper reference value Ya in step 106, the process proceeds to step 108. Here, the detected value Y1 is compared with the lower limit reference value Yb. If the detected value Y1 is below the lower limit reference value Yb, the wire 11a is loose on the feeding side of the groove roller 12, and the wire 11a is stretched on the winding side of the groove roller 12. Therefore, the feeding speed of the wire 11a by the drive motor 16 is lowered, and the winding speed of the wire 11a by the drive motor 17 is also lowered (step 109).
If the detected value Y1 exceeds the lower limit reference value Yb in step 108, the wire 11a is loose on the feeding side of the groove roller 12, but the tension of the wire 11a is the reference value on the winding side of the groove roller 12. It is a range. Therefore, the feeding speed of the wire 11a by the drive motor 16 is lowered, and the winding of the wire 11a by the drive motor 17 is maintained at the normal speed (step 110).
[0027]
In step 105, if the detected value X1 is lower than the upper limit reference value Xa, the detected value X1 is compared with the lower limit reference value Xb in step 111. At this time, if the detected value X1 is lower than the lower limit reference value Xb, the wire 11a is too tight on the feeding side of the groove roller 12. At this time, the routine proceeds to step 112.
On the other hand, if the detected value X1 exceeds the lower limit reference value Xb, the tension of the wire 11a on the feeding side of the groove roller 12 is within the range of the reference value, and the process proceeds to step 117. In step 112, the detected value Y1 is compared with the upper limit reference value Ya. When the detection value Y1 is larger than the upper limit reference value Ya, the wire 11a is excessively stretched on the feeding side of the groove roller 12. On the other hand, the wire 11a is loose on the winding side of the groove roller 12. Therefore, the feeding speed of the wire 11a by the rotary motor 16 is increased, and the winding speed of the wire 11a by the drive motor 17 is increased (step 113).
[0028]
If the detected value Y1 is smaller than the upper limit reference value Ya in step 112, the process proceeds to step 114. Here, the detected value Y1 is compared with the lower limit reference value Yb. If the detected value Y1 is below the lower limit reference value Yb, the wire 11a is excessively stretched on the feeding side and the winding side of the groove roller 12. Therefore, the feeding speed of the wire 11a by the rotary motor 16 is increased, while the winding speed of the wire 11a by the drive motor 17 is decreased (step 115).
In step 114, if the detected value Y1 exceeds the lower limit reference value Yb, the wire 11a is excessively tensioned on the feeding side of the groove roller 12, but the tension of the wire 11a is standard on the winding side of the groove roller 12. A range of values. Therefore, the feeding speed of the wire 11a by the drive motor 16 is increased, and the winding of the wire 11a by the drive motor 17 is maintained at the normal speed (step 116).
[0029]
Further, in step 117, when the detected value Y1 is larger than the upper limit reference value Ya, the tension of the wire 11a on the feeding side of the groove roller 12 is in a normal range, but on the winding side of the groove roller 12 The wire 11a is loose. Therefore, the feeding of the wire 11a by the drive motor 16 is set to the normal speed, and the winding of the wire 11a by the drive motor 17 is increased (step 118).
On the other hand, if the detected value Y1 is smaller than the upper limit reference value Ya in step 117, the process proceeds to step 119. Here, the detected value Y1 is compared with the lower limit reference value Yb. At this time, if the detection value Y1 is below the lower limit reference value Yb, the tension of the wire 11a on the feeding side of the groove roller 12 is in a normal range. On the other hand, the wire 11a on the winding side of the groove roller 12 is too tight. Therefore, the feeding speed of the wire 11a by the rotary motor 16 is set to a normal speed, and the winding speed of the wire 11a by the drive motor 17 is lowered (step 120).
[0030]
In step 119, if the detected value Y1 exceeds the lower limit reference value Yb, the tension of the wire 11a on the feeding side and the winding side of the groove roller 12 is within the range of the reference value. Therefore, the feeding speed of the wire 11a by the drive motor 16 and the winding speed of the wire 11a by the drive motor 17 are maintained at normal speeds (step 121).
As described above, after controlling any one of Step 107, Step 109, Step 110, Step 113, Step 115, Step 116, Step 118, Step 120, and Step 121, the tension control of the wire 11a is finished. Thereafter, the above control is repeated every predetermined time.
[0031]
As described above, since the tension control of the wire 11a is performed, it is possible to suppress a decrease in the cutting accuracy of the ingot I generated by the elongation of the wire 11a. In addition, since the looseness of the wire 11a is always detected during ingot cutting, changes in the tension of the wire 11a caused by the ingot elongation, for example, abnormalities in the spindles 35 and 36 of the groove roller 12, etc. are also detected early. can do.
When the ingot is cut, the feeding speed of the wire 11a from the feeding device to the groove roller 12 and the winding speed of the wire 11a from the groove roller 12 to the winding device 15 are adjusted in accordance with the variation in the distance between the groove rollers 12. Therefore, the wire wound between the groove rollers 12 is simply compared with the control in which the feeding speed of the wire 11a is stopped by the feeding device 13 or the winding speed of the wire 11a is stopped by the winding device 15. The tension control of 11a can be performed in a short time. In addition, the accuracy of tension control of the wire 11a can be improved.
[0032]
Next, a second embodiment of the present invention will be described based on the flowchart of FIG. FIG. 4 is a flowchart showing a wire tension control method according to the second embodiment of the present invention.
The feature of the wire saw according to the second embodiment and the tension control method of the wire used therein is that the tension control of the wire 11a at the time of cutting the ingot is detected by the detecting unit S1 in order to simplify the tension control of the wire 11a. This is a point performed only by the feeding device 13 on the basis of the detection signal from.
[0033]
First, in step 201, various devices are initialized by the tension control means 61 and the like. Next, the reference values Xa and Xb are read from the memory of the control device 60 (step 202). During the ingot cutting, the detection unit S1 always detects the interval d1 between the shaft 40a and the detection unit S1, and sends the detection signal to the tension control means 61 (step 203).
The obtained detection value X1 is compared with the upper limit reference value Xa (step 204). If the detected value X1 exceeds the upper limit reference value Xa, the wire 11a is loose on the feeding side of the groove roller 12. Therefore, the rotation of the drive motor 16 of the feeding device 13 is lowered and the wire 11a is stretched (step 205). On the other hand, if the detected value X1 is below the upper limit reference value Xa in step 204, the process proceeds to step 206, where the detected value X1 is compared with the lower limit reference value Xb. If the detected value X1 is below the lower limit reference value Xb, the wire 11a is too tight on the feeding side of the groove roller 12. Therefore, the rotation of the drive motor 16 of the feeding device 13 is increased to loosen the wire 11a (step 207). On the other hand, if the detected value X1 exceeds the lower limit reference value Xb in step 206, the tension of the wire 11a on the feeding side is within the reference value range. Therefore, the rotational speed of the drive motor 16 is set to a normal speed (step 208).
Other configurations, operations, and effects are the same as those of the first embodiment, and thus description thereof is omitted.
[0034]
Next, a third embodiment of the present invention will be described based on the flowchart of FIG. FIG. 5 is a flowchart showing a wire tension control method according to a third embodiment of the present invention.
The feature of the wire saw according to the third embodiment and the wire tension control method used therein is that, in order to simplify the tension control of the wire 11a, the tension control of the wire 11a at the time of cutting the ingot is detected by the detecting unit S2. This is a point performed only by the winding device 15 based on the detection signal from.
[0035]
First, in step 301, various initialization processes are performed. Next, the reference values Ya and Yb are read from the memory of the control device 60 (step 302). During the ingot cutting, the detection unit S2 always detects the interval d2 between the shaft part 40b and the detection unit S2, and sends the detection signal to the tension control means 61 (step 303).
Thereafter, the obtained detection value Y1 is compared with the upper limit reference value Ya (step 304). If the detected value Y1 exceeds the upper reference value Ya, the wire 11a is loose. Therefore, the rotation of the drive motor 17 is increased and the wire 11a on the winding side of the groove roller 12 is stretched (step 305). On the other hand, if the detected value Y1 is below the upper limit reference value Ya in step 304, the process proceeds to step 306, where the detected value Y1 is compared with the lower limit reference value Yb. If the detected value Y1 is lower than the lower limit reference value Yb, the wire 11a is too tight, and the rotation of the drive motor 17 of the winding device 15 is lowered to loosen the wire 11a (step 307). If the detected value Y1 exceeds the lower limit reference value Yb, the tension of the wire 11a is within the reference value range, and the drive motor 16 maintains normal rotation (step 308).
Other configurations, operations, and effects are the same as those of the first embodiment, and thus description thereof is omitted.
[0036]
【The invention's effect】
According to this invention, since the displacement of the distance between the axis of the groove roller is detected by the detection unit, and the tension of the wire is controlled based on the detected value, the ingot cutting accuracy caused by the elongation of the wire is reduced. Can be suppressed. Also, abnormalities in the spindle of the wire saw groove roller can be detected early.
[0037]
In particular, according to the second aspect of the present invention, the wire feeding speed from the feeding device to the groove roller and the wire winding speed from the groove roller to the winding device in accordance with the variation in the distance between the axis lines of the groove rollers. When the control is performed simultaneously, the wire is wound between the groove rollers as compared with simply stopping the wire feeding speed from the feeding device or stopping the wire winding speed by the winding device. The tension of the wire can be controlled in a short time, and the control accuracy is increased.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of a wire saw according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a wire saw groove roller incorporated in a wire saw according to a first embodiment of the present invention.
FIG. 3 is a flowchart showing a wire tension control method according to the first embodiment of the present invention;
FIG. 4 is a flowchart showing a wire tension control method according to a second embodiment of the present invention;
FIG. 5 is a flowchart showing a wire tension control method according to a third embodiment of the present invention;
[Explanation of symbols]
10 Wire saw,
11a wire,
12a wire groove,
12 Groove roller for wire saw,
13 Feeding device,
15 winding device,
I ingot,
61 tension control means,
S1, S2 detector.

Claims (3)

A plurality of wire saw groove rollers in which a plurality of wire grooves on which wires are laid are engraved on each outer peripheral surface;
A feeding device for feeding the wire to these wire saw groove rollers;
A winding device that winds the wire led out from the wire saw groove roller, and drives the feeding device and the winding device to reciprocate the wire spanned between the wire saw groove rollers to move the ingot. In the wire saw to cut,
A wire saw that adjusts the wire tension by detecting the distance between the axes of the wire saw groove roller during cutting of the ingot and controlling the driving of the feeding device and / or winding device based on the detected value. A detection unit for detecting the distance between the axes of the wire saw groove rollers during cutting of the ingot is provided,
When the detection value by the detection unit is larger than the reference value, control for lowering the feeding speed of the wire of the feeding device and / or control for increasing the winding speed of the wire to the winding device are performed. 2. The wire saw according to claim 1, further comprising a tension control unit that performs control to increase a feeding speed of the wire from the feeding apparatus and / or control to decrease a winding speed of the wire to the winding apparatus when the value is smaller than the value. A wire saw wire tension control method for controlling the tension during ingot cutting of a wire spanned between a plurality of wire saw groove rollers in a wire saw,
Detect the distance between the axes of the wire saw groove roller during cutting the ingot,
A wire tension control method for a wire saw, wherein when the detected value is larger than a reference value, the tension of the laid wire is increased, and when the detected value is smaller than the reference value, the tension of the wire is decreased.

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