Stroke control device of multi-wire saw and control method thereof

Abstract

The present invention provides a stroke control device of a multi-wire saw, the device comprising: a spool having a cylindrical shape, having flanges at both ends, which protrude from the outer circumferential surface thereof in the circumferential direction, having a starting point of a wire unwinding point formed adjacent to the inner surface of any one of the flanges, and having a wire wound thereon through rotation; a pulley which guides a wire delivered from a cutting area, to the unwinding point; a traverse which linearly reciprocates a traverse arm having the pulley installed thereon, along the axial direction of the spool to correspond to a stroke by which the wire is wound on the spool; a lidar sensor which detects a position of each flange or a distance between the flanges; and a control unit which controls the traverse such that the wire delivered from the pulley at the unwinding point formed on the outer circumferential surface of the spool maintains a direction orthogonal to the axial direction.

Description

Stroke control device for a multi-wire saw and control method thereof

[0001] The present invention relates to a stroke control device for a multi-wire saw and a control method thereof, and more specifically, to a stroke control device for a multi-wire saw and a control method thereof capable of automatically controlling the stroke position so that the wire unwound from the pulley always maintains a right angle at the position where it is wound onto the spool while maintaining a constant tension between the pulley and the spool during the process of winding the wire onto the spool.

[0002] Silicon substrates, sapphire substrates, quartz substrates (auxiliary materials), and silicon parts (auxiliary materials) used in semiconductor processes are generally cut from large specimens using multi-wires.

[0003] For example, a wafer is a thin silicon sheet made from silicon, which is widely used as a material for manufacturing semiconductor devices, and consists of a slicing process that cuts a grown silicon ingot into a wafer shape, a lapping process that homogenizes and flattens the thickness of the wafer, an etching process that removes or mitigates damage caused by mechanical polishing, a polishing process that mirrors the wafer surface, and a cleaning process that washes the polished wafer and removes foreign substances attached to the surface. Among these, the slicing process is a process of grinding the outer surface of a silicon single-crystal ingot to form a cylindrical shape of a predetermined size and cutting it into individual wafers.

[0004] Generally, various types of slicing devices are used for the slicing process, one of which is a wire saw device using a wire. A wire saw is a device that cuts by bringing a wire into contact with the material and frictionally rubbing it at high speed, cutting through the friction between the wire and the material. Such wire saw devices are widely used because they can cut an ingot into multiple wafers simultaneously, resulting in excellent production yield per unit time.

[0005] Recently, methods involving coating the wire itself with diamond and utilizing this for cutting products are being widely used.

[0006] Since this type of wire saw is equipment that performs processing operations by winding and unwinding the wire while maintaining constant tension on the rotating body, the spools that supply and retrieve the wire are replaced periodically.

[0007] However, the method of replacing the spool involves manual replacement by an operator, and as displacement occurs depending on the operator's skill level and the mounting position of the spool, the unwinding point of the traverse that discharges or supplies the wire from or to the spool within the spool's stroke range changes, causing problems in precisely winding or unwinding the wire. Consequently, wire breakage occurs, leading to issues such as wafer quality degradation and time delays due to stroke settings.

[0008] The present invention aims to solve such problems, and more specifically, to provide a stroke control device for a multi-wire saw and a control method thereof that can automatically control the stroke position so that the wire unwound from the pulley always maintains a right angle at the position where it is wound onto the spool while maintaining constant tension between the pulley and the spool during the process of winding the wire onto the spool.

[0009] The problems of the present invention are not limited to those mentioned above, and other unmentioned objectives will be clearly understood by those skilled in the art from the description below.

[0010] To achieve the above objective, the present invention provides a stroke control device for a multi-wire saw comprising: a spool having a cylindrical shape, each having wing portions protruding circumferentially from the outer surface at both ends, and a starting point of a wire unwinding point formed adjacent to the inner surface of one of the wing portions, for winding a wire through rotation; a pulley for transmitting a wire transmitted from a cutting area to the unwinding point; a traverse for linearly reciprocating a traverse arm on which the pulley is installed along the axial direction of the spool to correspond to the stroke in which the wire is wound on the spool; a lidar sensor for detecting the position of each wing portion or the distance between the wing portions; and a control unit for controlling the traverse so that the wire transmitted from the pulley at the unwinding point formed on the outer surface of the spool maintains a direction orthogonal to the axial direction.

[0011] The above lidar sensor is positioned in front of the traverse arm toward the spool and can map the space between the spool and the pulley in real time.

[0012] The above lidar sensor can measure the angle of the wire transmitted from the pulley with respect to the unwinding point of the wire wound on the outer surface of the spool or the outermost edge of the spool.

[0013] The pulley may be positioned to be tiltable around a tilting axis arranged parallel to the axial direction on the traverse.

[0014] The control unit can repeat the process of measuring a new stroke for the replaced spool through the lidar sensor and resetting the stroke of the traverse arm in response to the new stroke.

[0015] The control unit can repeat the process of measuring the position of a new wing portion for a replaced spool through the lidar sensor and resetting the release point of the pulley in correspondence with the position of the new wing portion.

[0016] The above lidar sensor can measure the distance and angle to the spool or wire in a non-contact manner.

[0017] The control unit can control the lidar sensor to continuously scan the distance from the inner surface of one wing to the inner surface of another wing as the traverse moves along the axial direction.

[0018] The above traverse arm may include a weight whose coupling gap is adjusted from the traverse arm to induce a right angle of the pulley by adjusting the tilting angle from the traverse.

[0019] The lidar sensor detects that the spool is tilted or rotates eccentrically, and the control unit can control the movement of the traverse arm to correspond to the tilting or eccentric rotation of the spool.

[0020] In addition, the present invention provides a stroke control method for a multi-wire saw comprising a spool on which a wire is wound, a pulley that transmits the wire to the spool, and a traverse that moves the pulley in a linear reciprocating motion along the axial direction of the spool, the method comprising: a first step of replacing a new spool; a second step of moving the traverse arm of the traverse to a center position of the spool; a third step of measuring the available stroke of the spool through a lidar sensor provided on the traverse arm; a fourth step of setting a conversion stroke of the traverse to correspond to the available stroke of the spool; and a fifth step of adjusting the movement speed or direction of the traverse arm so that the wire maintains a direction orthogonal to the axial direction at the unwinding point of the wire transmitted from the pulley to the outer surface of the spool.

[0021] The above third step may include a third-1 step of measuring the position of one wing portion of the spool through the lidar sensor, a third-2 step of measuring the position of the other wing portion of the spool, and a third-3 step of measuring the distance from one wing portion of the spool to the other wing portion.

[0022] The stroke control method of the multi-wire saw described above may further include a sixth step of measuring the angle of the wire transmitted from the pulley to the spool through the lidar sensor when the wire is wound onto the spool.

[0023] The stroke control method of the multi-wire saw described above may further include a seventh step of detecting whether the spool is tilted or rotates eccentrically through the lidar sensor.

[0024] The above fifth step can map the space between the spool and the pulley in real time by repeating any one or more of the above third to fifth steps.

[0025] Specific details of other embodiments are included in the detailed description and drawings.

[0026] According to the stroke control device of a multi-wire saw and the control method thereof according to an embodiment of the present invention,

[0027] First, by utilizing a LiDAR sensor, the stroke and disintegration point of the replaced spool can be precisely detected, and

[0028] Second, the stroke of each replaced spool can be automatically corrected to correspond to a different stroke for each commercial spool, and

[0029] Third, since the operator no longer needs to manually set the spool stroke displacement visually, it has the effect of increasing accuracy and significantly reducing work fatigue.

[0030] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0031] The summary described above, as well as the detailed description of the preferred embodiments of the present application described below, will be better understood when read in conjunction with the accompanying drawings. Preferred embodiments are illustrated in the drawings for the purpose of illustrating the present invention. However, it should be understood that the present application is not limited to the exact arrangements and means illustrated.

[0032] FIG. 1 is a front view illustrating a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0033] FIG. 2 is a block diagram briefly illustrating a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0034] Figure 3 is a side view illustrating the stroke control device of the multi-wire saw shown in Figure 1.

[0035] FIG. 4 is a perspective view illustrating the stroke control device of the multi-wire saw shown in FIG. 1.

[0036] FIG. 5 is a front view showing the state in which the stroke control device of the multi-wire saw shown in FIG. 1 has been replaced with a new spool.

[0037] FIG. 6 is a front view illustrating the state in which the traverse has moved by the stroke in the stroke control device of the multi-wire saw shown in FIG. 5.

[0038] FIG. 7 is a flowchart illustrating a control method of a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0039] FIG. 8 is a block diagram illustrating a control method of a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0041] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in the drawings.

[0042] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0043] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms.

[0044] The above terms are used solely for the purpose of distinguishing one component from another.

[0045] For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component.

[0046] The term "and / or" includes a combination of multiple related listed items or any of the multiple related listed items.

[0047] When it is stated that one component is "connected" or "joined" to another component, it should be understood that while it may be directly connected or joined to that other component, there may also be other components in between.

[0048] On the other hand, when it is stated that one component is "directly connected" or "directly coupled" to another component, it should be understood that there are no other components in between.

[0049] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention.

[0050] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0051] In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0052] Hereinafter, embodiments will be described in detail with reference to the attached drawings, provided that identical or corresponding components are given the same reference number regardless of the drawing symbols, and redundant descriptions thereof will be omitted.

[0053] FIG. 1 is a front view illustrating a stroke control device of a multi-wire saw according to an embodiment of the present invention, and FIG. 2 is a block diagram briefly illustrating a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0054] Referring to FIGS. 1 and 2, a stroke control device for a multi-wire saw according to an embodiment of the present invention may be configured to be positioned outside the cutting area of ​​the multi-wire saw and to rotate a spool on both sides of the cutting area to unwind or wind a wire wound on the spool. At this time, since the structure for rotating the spool on both sides has the same structure, only one of these structures will be described.

[0055] Of course, although not illustrated in the drawings, the control device of the multi-wire saw according to an embodiment of the present invention may have a structure in which a wire is unwound from one spool and wound onto another spool. Below, the structure of the side where the wire is wound onto the spool will be described.

[0056] A stroke control device for a multi-wire saw according to an embodiment of the present invention may include a driving unit (110), a spool (120), a traverse (130), a pulley (140), a lidar sensor (150), and a control unit (160).

[0057] First, the driving unit (110) can provide driving force to rotate the rotation shaft (111). The spool is detachably coupled to the rotation shaft (111) and can rotate simultaneously along the rotation direction of the rotation shaft (111).

[0058] In addition, the spool is formed in the shape of a cylindrical bobbin, and the wire (W) can be wound by the rotation of the rotation axis (111).

[0059] The spool (120) has a starting point (SP) for unwinding or winding the wire in one direction centered on the axial direction, and an ending point (EP) for unwinding or winding the wire again in another direction on the opposite side from the starting point, and the distance between the starting point (SP) and the ending point (EP) can be set as a stroke range.

[0060] The starting point (SP) and ending point (EP) of the spool (120) may be formed adjacent to the inner surface of each wing portion provided at both ends of the spool (120). These wing portions (121) can prevent the wire from coming off the outer surface of the spool, or limit the height at which the wire (W) is wound on the outer surface of the spool (120).

[0061] The spool (120) is fastened onto the rotation axis (111), and a predetermined assembly tolerance may occur depending on the fastening torque. Alternatively, during the process of fastening the spool onto the rotation axis (111), it may be coupled to rotate eccentrically while inclined at a predetermined angle rather than parallel to the rotation axis (111).

[0062] Additionally, a traverse arm (131) is coupled to the traverse (130) so as to be able to move in a straight line along the axial direction (D), and an actuator (132) is provided to drive the traverse arm (131) so as to be able to perform the straight line reciprocating movement of the traverse arm (131).

[0063] The traverse arm (131) can move the pulley (140) along the axial direction on the traverse to deliver the wire (W) to the unwinding point in a direction orthogonal to the axial direction (D) of the spool (120). That is, the traverse arm (131) can continuously move so that the point where the wire (W) is unwinded is always delivered in a direction normal to the circumferential direction of the spool (120), and the direction change can be accurately made at the corresponding timing at the wire start point and end point on the spool (120).

[0064] Additionally, the pulley (140) is coupled to the traverse arm (131) to transmit the wire (W) in the direction of the spool. The pulley (140) is rotatably coupled to the traverse arm (131) to guide the transmission of the wire to the unspool point.

[0065] Additionally, the LiDAR (Light Detection and Ranging) sensor (140) can measure the position of each wing section provided on the spool (120) or the distance between two wing sections.

[0066] For example, the lidar sensor (150) can be mounted on the traverse arm (131) to measure the position of the wing portion (121), the stroke (S) which is the distance between each wing portion, and the distance and angle of the wire in real time. Of course, the lidar sensor (150) can also be placed in an external area of ​​the traverse arm (131) to measure the space and distance between the pulley (140) and the spool (120). In this embodiment, the lidar sensor (150) is provided on the traverse arm (131) as an example.

[0067] The lidar sensor (150) can measure distance in a non-contact manner and can continuously or intermittently map the space between the spool (120) and the pulley (140) in a non-contact manner.

[0068] The LiDAR sensor (150) measures distance using laser light by emitting laser pulses and measuring the time it takes for the light to be reflected back from the object, thereby determining the distance and shape of the object. The LiDAR sensor (150) emits numerous laser pulses to detect the light reflected between the pulley (140) and the spool (120), and at this time, the distance to each wing and the shape of the wing can be determined. In addition, the measured distance information can be converted into coordinates to generate a point cloud of space. By analyzing the generated point cloud, a 3D spatial map can be obtained, and the location, size, shape, etc. of objects within the space can be verified.

[0069] Of course, in addition to the point cloud processing method, the LiDAR sensor (150) can perform spatial mapping using a simultaneous location tracking and mapping method or a sensor fusion method.

[0070] When real-time mapping is performed through the lidar sensor (150), high accuracy and precision can be secured, and since real-time data collection is possible, real-time precise measurement can be performed even when the spool is replaced or when displacement occurs at the replacement position of the spool.

[0071] Additionally, the control unit (160) can receive position information and stroke (S) information of the wing unit (121) from the lidar sensor (150) and control the traverse arm (131) or pulley (140) to move in parallel in correspondence with the available stroke (S) range of the spool.

[0072] That is, the control unit (160) can receive position information of the wing portion (121) and determine the displacement of the replacement position of the spool (120) that occurs depending on the degree to which the replaced spool (120) is coupled on the rotation axis, and can receive stroke (S) information of the spool (120) and continuously check the new available stroke range of the replaced spool (120). Accordingly, the control unit (160) can control the unwinding point to move by the displacement of the replacement position of the spool (120) (not shown), and can set the conversion stroke of the traverse arm (131) to correspond to the new available stroke range. In addition, the control unit (160) can control the process of resetting the wing portion position of the new spool and the unwinding point of the pulley to be repeated.

[0073] The control unit (160) may include a storage unit (161) that stores distance data, angle data, and available stroke data provided from the lidar sensor (150). The storage unit (161) may store first distance data for one spool (120) and second distance data for another replaced spool.

[0074] Additionally, the control unit (160) may include a judgment unit (162) that derives offset data according to the amount of change in distance by comparing the distance of the first distance data and the second distance data. The offset data may be distance information in which the traverse arm (131) moves in parallel in response to the amount of change in distance.

[0075] Additionally, the lidar sensor (150) can measure multiple first distance data and second distance data and store them in the storage unit (161). At this time, the lidar sensor (150) can measure the first distance data multiple times while rotating the first spool (120), and also measure the second distance data multiple times while rotating the replaced second spool.

[0076] Additionally, the judgment unit (162) can set offset data based on real-time measured distance data. Of course, the judgment unit (162) can derive a change in distance as an average value using each distance data stored in the storage unit (161) and set offset data based on the average value. Additionally, the judgment unit (162) can derive a change in distance as a maximum value using each distance data stored in the storage unit (161) and set offset data based on the maximum value.

[0077] Although not shown in the drawing, the control unit (160) can control the positional movement of the traverse arm (131) as well as the rotational speed or rotational direction of the drive unit (110), or can control the replacement timing or cycle of the spool (120) and the overall operation of the lidar sensor (150).

[0078] FIG. 3 is a side view illustrating the stroke control device of the multi-wire saw shown in FIG. 1, FIG. 4 is a perspective view illustrating the stroke control device of the multi-wire saw shown in FIG. 1, FIG. 5 is a front view illustrating the state in which the stroke control device of the multi-wire saw shown in FIG. 1 is replaced with a new spool, and FIG. 6 is a front view illustrating the state in which the traverse has moved by the stroke in the stroke control device of the multi-wire saw shown in FIG. 5.

[0079] Referring to FIGS. 3 to 6, the traverse (130) may include a traverse arm (131) configured to be capable of linear reciprocating movement along the axial direction (D), a pulley (140) coupled to the traverse arm (131), a lidar sensor (150), and a weight (133).

[0080] The traverse arm (131) can be coupled to the traverse (130) to enable tilting rotation. That is, the traverse arm (131) can be provided with a tilting axis (TA) on the traverse (130). The tilting axis (TA) can be positioned parallel to the axial direction (D) described above. The tilting axis (TA) can be formed at the center of the structure connecting the traverse (130) and the traverse arm (131). The traverse arm (131) can be tilted around the tilting axis (TA) so that the wire (W) passing through the pulley (140) maintains a right angle toward the spool (120).

[0081] At this time, the weight (133) can be adjusted so that it moves closer to or further away from the traverse arm (131) and the tilting angle of the traverse arm (131) can be adjusted through the adjustment of the connection gap.

[0082] For example, when the weight (134) moves closer to the tilting axis (TA), the traverse arm (131) can rotate counterclockwise with respect to FIG. 3, and when the weight (133) moves further away from the tilting axis (TA), the traverse arm (131) can rotate clockwise.

[0083] Of course, based on FIG. 3, the traverse arm (131) can be positioned to automatically rotate counterclockwise around the tilting axis (TA) as the number of windings of the wire (W) on the spool (120) increases.

[0084] Also, the lidar sensor (150) can measure the rotation axis of the spool (120) and the state in which the spool (120) rotates concentrically or eccentrically, and the control unit (160) can control the movement of the traverse arm (131) to correspond to the degree of tilting or eccentric rotation of the spool (120).

[0085] Additionally, the lidar sensor (150) measures the position of each wing portion of the replaced spool (120) and stroke information in real time and transmits it to the control unit (160), and the control unit (160) can control the traverse arm (131) to correspond to the position of the wing portion of the replaced spool and the conversion stroke based on the information transmitted from the lidar sensor (150).

[0086] FIG. 7 is a flowchart illustrating a control method of a stroke control device of a multi-wire saw according to an embodiment of the present invention, and FIG. 8 is a block diagram illustrating a control method of a stroke control device of a multi-wire saw according to an embodiment of the present invention.

[0087] Referring to FIGS. 7 and 8, a control method (S100) of a stroke control device for a multi-wire saw according to an embodiment of the present invention may include a first step (S110) of replacing a new spool, a second step (S120) of moving a traverse arm to a center position of the spool, a third step (S130) of measuring the available stroke of the spool through a lidar sensor, a fourth step (S140) of setting a conversion stroke of the traverse to correspond to the available stroke of the spool, and a fifth step (S150) of controlling the movement speed or direction of the traverse arm so that the wire maintains a direction orthogonal to the axial direction at the wire unwinding point.

[0088] Here, the third step (S130) may include a third-1 step (S131) ​​for measuring the position of one wing portion of the spool through a lidar sensor, a third-2 step (S132) for measuring the position of the other wing portion of the spool, and a third-3 step (S133) for measuring the distance from one wing portion of the spool to the other wing portion.

[0089] In addition, the control method (S100) of the stroke control device of a multi-wire saw may further include a sixth step (S160) of measuring the angle of the wire transmitted from the pulley to the spool through a LiDAR sensor when the wire is wound onto the spool, and a seventh step (S170) of measuring whether the spool is tilted or rotates eccentrically.

[0090] Additionally, the fifth step (S150) can map the space between the spool and the pulley in real time by repeating any one or more of the third step (S130) and the fourth step (S140).

[0091] The control method (S100) of the stroke control device of such a multi-wire saw can be implemented through the stroke control device of the multi-wire saw described above.

[0092] Accordingly, according to the stroke control device and control method of a multi-wire saw according to an embodiment of the present invention, the stroke and release point of a replaced spool can be precisely detected by utilizing a LiDAR sensor, and the stroke of each replaced spool can be automatically corrected to correspond to a different stroke for each commercial spool. Furthermore, since there is no need for an operator to manually set the stroke displacement of the spool visually, accuracy is increased and work fatigue can be significantly reduced.

[0093] Although specific embodiments have been illustrated and described above to exemplify the technical concept of the present invention, the present invention is not limited to the configuration and operation identical to the specific embodiments described above, and various modifications may be implemented within the scope of the present invention. Accordingly, such modifications should also be considered to fall within the scope of the present invention, and the scope of the present invention should be determined by the claims set forth below.

Claims

1. A spool having a cylindrical shape, each having wing portions protruding circumferentially from the outer surface at both ends, a starting point of the wire unwinding point formed adjacent to the inner surface of one of the wing portions, and winding the wire through rotation; A pulley that transmits the wire transmitted from the cutting area to the above-mentioned sea point; A traverse that linearly reciprocates a traverse arm on which the pulley is installed along the axial direction of the spool to correspond to the stroke in which a wire is wound onto the spool; A LiDAR sensor for detecting the position of each of the above wing portions or the distance between the above wing portions; and A control unit that controls the traverse so that the wire transmitted from the pulley maintains a direction orthogonal to the axial direction at a spooling point formed on the outer surface of the spool; A stroke control device for a multi-wire saw, including 2. In Paragraph 1, The above LiDAR sensor is, A stroke control device for a multi-wire saw, positioned toward the spool in front of the traverse arm and mapping the space between the spool and the pulley in real time.

3. In Paragraph 1, The above LiDAR sensor is, A stroke control device for a multi-wire saw that measures the angle of a wire transmitted from the pulley with respect to the unwinding point of a wire wound on the outer surface of the spool or the outermost edge of the spool.

4. In Paragraph 1, The above pulley, A stroke control device for a multi-wire saw, positioned to be tiltable around a tilting axis arranged parallel to the axial direction on the traverse.

5. In Paragraph 2, The above control unit is, A stroke control device for a multi-wire saw that measures a new stroke for a replaced spool through the above-mentioned lidar sensor and repeats the process of resetting the stroke of the traverse arm in response to the new stroke.

6. In Paragraph 2, The above control unit is, A stroke control device for a multi-wire saw that measures the position of a new wing portion for a replaced spool using the above-mentioned lidar sensor and repeats the process of resetting the unwinding point of the pulley in correspondence with the above-mentioned new wing portion position.

7. In Paragraph 1, The above-described LiDAR sensor is a stroke control device for a multi-wire saw that measures distance and angle to the spool or wire in a non-contact manner.

8. In Paragraph 1, The above control unit is, A stroke control device for a multi-wire saw that controls the lidar sensor to continuously scan the distance from the inner surface of one wing to the inner surface of another wing during the process of the above-mentioned traverse moving along the axial direction.

9. In Paragraph 1, The above traverse arm is, A stroke control device for a multi-wire saw, comprising a weight whose coupling gap is adjusted from the traverse arm to induce a right angle of the pulley by adjusting the tilting angle from the traverse.

10. In Paragraph 1, The above lidar sensor detects whether the spool is tilted or rotates eccentrically, and The stroke control device of a multi-wire saw, wherein the control unit controls the movement of the traverse arm to correspond to the tilting or eccentric rotation of the spool.

11. A stroke control method for a multi-wire saw comprising a spool on which a wire is wound, a pulley for transmitting the wire to the spool, and a traverse for linearly reciprocating the pulley along the axial direction of the spool, Step 1 of replacing the new spool; A second step of moving the traverse arm of the above traverse to the center position of the spool; A third step of measuring the available stroke of the spool through a LiDAR sensor provided in the traverse arm; A fourth step of setting a conversion stroke of the traverse to correspond to the available stroke of the spool; and A fifth step of adjusting the movement speed or direction of the traverse arm so that the wire maintains a direction orthogonal to the axial direction at the point where the wire transmitted from the pulley to the outer surface of the spool is unwound; A stroke control method for a multi-wire saw including 12. In Paragraph 11, The above third step is, Step 3-1, which measures the position of one wing portion of the spool through the above lidar sensor, and Step 3-2 for measuring the position of the other wing portion of the above spool and A stroke control method for a multi-wire saw comprising a third step of measuring the distance from one wing portion to the other wing portion of the spool.

13. In Paragraph 11, A stroke control method for a multi-wire saw, further comprising a sixth step of measuring the angle of the wire transmitted from the pulley to the spool through the lidar sensor when the wire is wound onto the spool.

14. In Paragraph 11, A stroke control method for a multi-wire saw, further comprising a seventh step of detecting whether the spool is tilted or rotates eccentrically through the lidar sensor.

15. In Paragraph 11, The above fifth step is, A stroke control method for a multi-wire saw that maps the space between the spool and the pulley in real time by repeating any one or more of the above steps 3 through 5.

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