Cutting device and method using laser

Abstract

The present invention relates to an apparatus and a method for cutting using a laser, the apparatus comprising: a laser generating unit that generates a laser beam that penetrates a surface of an object to be processed and is only partially absorbed; and a beam generating optical unit that focuses the laser beam at a desired cutting depth from the surface of the processing object into a shape that extends parallel to the surface of the processing object and perpendicular to the processing direction, generating a laser beam that is heated to a temperature not lower than the melting point at which the cut surface of the workpiece is not melted, and a temperature at which internal stress that separates the cut portion from the workpiece is generated; and a starting point generation means that causes damage to the cutting starting point of the outer contour of the cutting surface to be cut in the object to be processed, achieves a structure in which the object to be processed is cut without melting the object to be processed and the damage is reduced, and can cut the object to be processed having a hot brittleness property into a desired thickness in a slicing manner.

Description

Technical Field

[0001] This invention relates to a laser cutting apparatus and method, and more specifically, to a laser cutting apparatus and method for cutting objects with thermally brittle properties, such as glass or ceramic ingots, by irradiating them with a laser beam in a slicing manner. Background Technology

[0002] The wafer slicing process is the process of turning block-shaped silicon ingots into wafers that are commonly used.

[0003] The wafer slicing process includes ID (Inner Diamond) sawing, wire sawing, and laser cutting.

[0004] For example, Patent Document 1 and Patent Document 2 below each disclose a cutting structure utilizing a wire saw and a laser.

[0005] On the other hand, the processes for cutting wafers, ceramics, and glass, which have thermally brittle properties, often result in low yields and excessive losses of processed objects such as ingots due to frequent defects caused by cracking and thermal damage.

[0006] In particular, the process of processing wafers from ingots not only includes wafer dicing but also requires multiple additional steps such as ingot and wafer grinding, which leads to reduced operability and lower production efficiency.

[0007] (Patent Document 1) Korean Patent Publication No. 10-2008-0001394 (Published on January 3, 2008)

[0008] (Patent Document 2) Korean Patent Registration No. 10-2368338 (Published on March 2, 2002) Summary of the Invention

[0009] Technical issues

[0010] The present invention aims to solve the problems described above. The purpose of the present invention is to provide a laser cutting device and method that can cut processing objects with thermal brittleness, such as glass, ceramics, and ingots, into slices of the required thickness.

[0011] Another object of the present invention is to provide a laser cutting apparatus and method that can cut a workpiece by irradiating it with a laser beam to heat it and simultaneously cooling it, without melting or vaporizing the workpiece.

[0012] Technical solution

[0013] To achieve the aforementioned objective, the laser-based cutting apparatus of the present invention includes: a laser generating unit that generates a laser beam that penetrates the surface of the workpiece and is absorbed only in a portion thereon; a beam generating optical unit that focuses the laser beam at a desired cutting depth, measured from the surface of the workpiece, into a shape that extends parallel to the surface of the workpiece and perpendicular to the processing direction, generating a laser beam heated to a temperature below the melting point of the cut surface of the workpiece and at a temperature that generates internal stress that causes the cut portion to separate from the workpiece; and a starting point generating unit that damages the cutting starting point of the desired cut surface outline in the workpiece, thereby cutting in a slicing manner without melting the workpiece and reducing damage.

[0014] Furthermore, in order to achieve the aforementioned objective, the laser beam cutting method of the present invention includes the following steps: step (a), a laser generating unit generates a laser beam that penetrates the surface of the workpiece and is only partially absorbed; step (b), a starting point generating unit damages the cutting starting point of the outer contour of the cut surface to be cut in the workpiece; and step (c), a beam generating optical unit focuses the laser beam at a desired cutting depth measured from the surface of the workpiece into a shape that extends parallel to the surface of the workpiece and perpendicular to the processing direction, generates a laser beam heated to a temperature below the melting point of the cut surface of the workpiece and a temperature that generates internal stress that causes the cut portion to separate from the workpiece, and then irradiates the workpiece to cut it in a slicing manner without melting the workpiece and reducing damage.

[0015] Invention Effects

[0016] As previously stated, the laser-based cutting apparatus and method according to the present invention can cut workpieces with thermal brittleness into slices of the required thickness.

[0017] Furthermore, according to the present invention, the workpiece is heated by irradiating it with a laser beam and simultaneously cooled, thereby enabling cutting without melting or vaporizing the workpiece and minimizing damage.

[0018] Furthermore, according to the present invention, the cutting portion of the workpiece can be easily separated using the separation unit, thereby improving the flatness of the cutting surface.

[0019] Therefore, according to the present invention, the operability of cutting operations on the cut portion of the workpiece is improved, and post-processing of the cut portion, such as polishing processes performed during wafer manufacturing, can be eliminated or minimized, thereby significantly improving productivity. Attached Figure Description

[0020] Figure 1 This is a configuration diagram of a laser-based cutting device according to a preferred embodiment of the present invention.

[0021] Figure 2 yes Figure 1 The diagram shows a block configuration of a laser-based cutting device.

[0022] Figure 3 and Figure 4 Each example illustrates the configuration of the separate unit.

[0023] Figures 5 to 7 Each example illustrates the configuration structure of the cooling unit and the laser generation unit.

[0024] Figure 8 This is a flowchart illustrating the laser-based cutting method of a preferred embodiment of the present invention, step by step. Detailed Implementation

[0025] The preferred embodiments of the laser-based cutting apparatus and method of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Figure 1 This is a configuration diagram of a laser-based cutting apparatus according to a preferred embodiment of the present invention. Figure 2 yes Figure 1 The diagram shows a block configuration of a laser-based cutting device.

[0027] The following directional terms, such as “left,” “right,” “front,” “back,” “above,” and “below,” are defined as indicating each direction based on the state shown in each diagram.

[0028] In this embodiment, the structure of a dicing apparatus for processing wafers by dicing ingots in a slicing manner according to a preset thickness will be described.

[0029] Of course, please note that the present invention is not necessarily limited to this. It can be applied not only to cutting devices for cutting ingots to process wafers, but also to cutting devices for cutting objects with thermal brittleness, such as glass and ceramics.

[0030] Moreover, the present invention is not only applicable to cutting devices for silicon wafers, but also applicable to cutting devices for high-hardness and high-brittle materials such as silicon carbide (hereinafter referred to as "SiC") wafers and gallium nitride (hereinafter referred to as "GaN") wafers, which have a hardness higher than that of silicon wafers.

[0031] like Figure 1 and Figure 2As shown, the laser-based cutting apparatus 10 of a preferred embodiment of the present invention includes: a laser generating unit 20 that generates a laser beam 21 that penetrates the surface of a workpiece 11 and is only partially absorbed; a beam generating optical unit 20 that focuses the laser beam 21 at a desired cutting depth measured from the surface of the workpiece 11 into a shape that extends parallel to the surface of the workpiece 11 and perpendicular to the cutting direction, generating a laser beam 21 heated to a temperature below the melting point of the cut surface of the workpiece 11 and at a temperature that generates internal stress that causes the cut portion 14 to separate from the workpiece 11; and a starting point generating unit 50 that damages the cutting starting point 13 of the outer contour of the cut surface 12 to be cut in the workpiece 11; and cuts without melting the workpiece and with reduced damage.

[0032] Furthermore, the laser-based cutting apparatus 10 of the preferred embodiment of the present invention may further include: a cooling unit 40, which supplies coolant to the cutting portion 14 heated by the laser beam 21 for cooling; a separation unit 60, which separates the cut portion 14 from the workpiece 11; and a control unit 70, which controls the driving of each device.

[0033] The control unit 70 can control the diameter of the workpiece 11 (e.g., an ingot) and the thickness of the workpiece to be cut, i.e., the cutting depth based on the upper surface of the ingot, the intensity of the laser beam 21 irradiated by the laser generating unit 20, the cutting speed of the ingot by moving the laser beam along the cutting direction, and the cooling rate based on the amount and speed of the coolant sprayed by the cooling unit 30.

[0034] For example, the control unit 70 can change the laser beam 21 to have various shapes and energy distributions according to the diameter and cutting depth of the ingot, the cutting speed and the cooling speed, and can generate a control signal that automatically adjusts the output of the laser beam 21 in a manner proportional to the cutting speed.

[0035] The laser generating unit 20 is configured as a beam generator that generates a laser beam 21. The beam generating optical unit can be configured as a lens unit that adjusts the focal point of the laser beam 21 generated by the beam generator to correspond to the cutting depth and then irradiates the workpiece 11.

[0036] The ingot is typically formed in a roughly cylindrical shape, with the focal point positioned at a predetermined thickness. That is, the laser beam 21, which is irradiated with the upper surface of the ingot as a reference and the focal point positioned at a predetermined cutting depth while the ingot is standing upright in the vertical direction, can cut in a slicing manner.

[0037] For example, in Figure 1During inspection, the laser beam 21 irradiating the workpiece 11 moves along the X-axis direction from the damage formed at the cutting starting point 13 located on the outer contour of the cutting surface 12. Therefore, the laser beam 21 can cut the cutting portion 14 with a thickness corresponding to the cutting depth along the -Z-axis direction on the upper surface of the workpiece 11.

[0038] That is, the laser beam 21 can be a straight line beam that extends long along the Y-axis direction perpendicular to the cutting surface 13 parallel to the upper surface of the workpiece 11.

[0039] For example, the output of laser beam 21 has approximately 1x10 -3 μm to 1x10 -2 μm wavelength and approximately 1x10 -2 mW / ㎜ 2 Up to 1x10 5 mW / ㎜ 2 The above energy density can be achieved at approximately 1 x 102 -2 mm / s to 1x10 4 Traveling at a speed of mm / s.

[0040] exist Figure 1 The position of the laser beam 21 focused for cutting the object 11 will have a slight gap from the actual cutting line on the cutting surface 12. Figure 1 When viewed, there is a slight gap between the laser beam 11 and the right end. This is because, after the workpiece 11 is irradiated by the laser beam 21, it is cut at the location where the coolant is supplied, resulting in a gap between the laser beam position and the actual cutting line. The stronger the laser beam 21, the narrower the gap between the laser beam 21 and the cutting line; conversely, the weaker the laser beam 21, the larger the gap.

[0041] As previously described, in this embodiment, before heating the workpiece 11 to recrystallize or melt it, the laser generating unit 20 sets the output of the laser beam 21 in such a way that it heats the workpiece 11 to a temperature below the melting point of the cut surface 13 that does not melt the workpiece 11 and generates internal stress that causes the cut portion 14 to separate from the workpiece 11, and then generates the laser beam 21 with the set output.

[0042] Therefore, the present invention can cut the workpiece heated by the laser beam without melting or vaporizing it and with minimal damage.

[0043] For this purpose, the laser generating unit 20 generates a laser beam 21 with wavelength and intensity corresponding to the signal of the control unit 70, and the beam generating optical unit 30 focuses the laser beam 21 generated by the laser generating unit 20 and, according to the control signal, enables the laser beam 21 to irradiate the focal position corresponding to the cutting depth.

[0044] Here, the laser beam 21 can be formed in a straight line shape with the same diameter as or slightly longer than that of the ingot. Of course, the present invention is not necessarily limited to this, and the laser beam 21 can be changed into various shapes, such as having a certain area or a certain thickness, according to the control signal of the control unit. However, when the length of the laser beam 21 is less than the diameter of the ingot, the laser beam 21 can be moved back and forth multiple times to cut the ingot.

[0045] That is, the surface of the object 11 is heated by the penetrating laser beam 21, but the interior of the object 11, especially the cutting surface 12 corresponding to the focal point of the laser beam 21, is heated to a higher temperature than the surface of the object 11. At this time, internal stress is generated in the cutting surface 12, causing the cutting portion 14 to separate from the object 11.

[0046] Furthermore, the beam generating optical unit 30 may also include a moving unit (not shown) that moves the lens unit along the cutting direction. The moving unit can move or adjust the angle of the lens unit according to the control signal of the control unit 70, thereby moving the laser beam 21.

[0047] For example, the moving unit may include: a drive motor that generates driving force according to a control signal from the control unit 70; and a moving body that moves after receiving the driving force from the drive motor through a transmission unit constructed in various ways such as gears, idlers, belts, and chains.

[0048] On the other hand, the cutting starting point 13 of the outer contour of the cutting surface 12 to be cut in the workpiece 11 can generate minute damage so that the cutting part 14 can be easily cut.

[0049] Therefore, in this embodiment, a starting point generation unit 50 that causes minor damage to the cutting starting point 13 can also be provided.

[0050] For example, the starting point generation unit 50 can create initial damage using a diamond grinding wheel (not shown), or create minor damage by irradiating the cutting starting point 13 with a laser beam irradiated by an additional laser generator (not shown).

[0051] The starting point generation unit 50 can drive a diamond grinding wheel to rotate by a drive module (not shown) driven by a control signal from the control unit 70, or drive a laser generator to irradiate a laser beam onto the cutting starting point 13 to cause damage with a preset size.

[0052] The separation unit 60 performs the function of easily separating the cut portion 14 of the workpiece 11 by moving it upward.

[0053] For example, Figure 3 and Figure 4 Each example illustrates the configuration of the separate unit.

[0054] like Figure 3 As shown, the separation unit 60 can be constructed with an outer contour support member, which is roughly formed in a ring shape and fixed to the outer contour of the cutting portion 14. The cutting portion is moved upward by the tensile force provided by the tensile tool (not shown) to separate it from the workpiece 11.

[0055] Moreover, such as Figure 4 As shown, the separation unit 60 is formed by closely adhering to the support member, which is roughly in the shape of a disc or cylinder and closely adhering to the upper part of the cutting part 14. While it is attached to the cutting part 14 with an adhesive or the like, the laser beam 21 penetrates the cutting part 14, and the cutting part 14 is separated from the workpiece 11 by the tensile force.

[0056] Preferably, the upper support and the adhesive are made of a light-transmitting material that does not reflect or scatter the laser beam 21 and allows all or most of the laser beam 21 to penetrate toward the workpiece 11.

[0057] Furthermore, the separation unit 60 can also be configured as a tensile force supply component, which includes an upper jig (not shown) and a lower jig (not shown) that provide tensile force to the lower end and the cut portion of the workpiece 11.

[0058] The cooling unit 40 may include: a spray nozzle (not shown) that sprays coolant onto the surface of the workpiece 11; and a regulator (not shown) that adjusts the cooling rate based on the spray volume and spray speed of the coolant sprayed through the spray nozzle.

[0059] The spray nozzle can mix the coolant with the fluid and then spray the coolant mixed with the fluid at a preset pressure. The coolant is used to cool the surface of the workpiece 11 irradiated by the laser beam 21 into its interior.

[0060] For example, the coolant can mix water and air and then spray it onto the irradiation area of ​​the laser beam 21 at a preset pressure.

[0061] Therefore, the cooling area sprayed with coolant allows the laser beam 21 to penetrate to the cutting depth.

[0062] For example, Figures 5 to 7 Each example illustrates the configuration structure of the cooling unit and the laser generation unit.

[0063] like Figure 5 As shown, the cooling unit 40 can be positioned behind the laser generating unit 20 with the cutting direction as the reference, that is, in Figure 5 When viewed in the middle, the configuration is on the left.

[0064] Therefore, the cooling unit 40 can cool the heated cutting portion 14 of the workpiece 11 immediately after the laser generating unit 20 irradiates the workpiece 11 with the laser beam 21.

[0065] like Figure 6 As shown, the cooling unit 40 can be configured to supply coolant to a cooling region that is formed more extensively than the irradiation region, in a manner that includes the irradiation region of the laser beam 21 irradiated by the laser generating unit 20.

[0066] Therefore, the cooling unit 40 can cool the heated cutting portion 14 of the workpiece 11 by supplying coolant after the laser generating unit 20 irradiates the workpiece 11 with the laser beam 21.

[0067] On the other hand, in this embodiment, in order to solve the problem that the coolant sprayed by the cooling unit 40 interferes with the laser beam 21 when it is heated or vaporized by heat exchange with the cutting part 14, a coolant removal unit 41 may also be included.

[0068] For example, such as Figure 7 As shown, the coolant removal unit 41 includes a fan (not shown) positioned in front of the laser generation unit 20 in the cutting direction, that is, from... Figure 7 The fan (not shown) located on the right side during inspection can remove the heated or vaporized coolant that has passed through the heat exchange section 14 by blowing air.

[0069] As previously mentioned, the cooling region is formed to cool all or part of the irradiated area irradiated by the laser beam 21.

[0070] Therefore, the depth to which the laser beam 21 is absorbed inside the workpiece 11 can be changed according to the cutting depth of the workpiece 11.

[0071] As mentioned above, the present invention can cut workpieces with thermal brittleness into slices of the required thickness.

[0072] Next, combined Figure 8 The laser-based cutting method of the preferred embodiment of the present invention is described in detail below.

[0073] Figure 8 This is a flowchart illustrating the laser-based cutting method of a preferred embodiment of the present invention, step by step.

[0074] exist Figure 8In step S10, the laser generating unit 20 generates a laser beam 21 that penetrates the surface of the workpiece 11 and is only partially absorbed. At this time, the cutting starting point 13 of the outer contour of the cutting surface 12 to be cut in the workpiece 11 may be in a state where it has been slightly damaged by the starting point generating unit 50.

[0075] In step S12, the beam generating optical unit 30 uses a lens unit to focus the laser beam 21 into a shape that extends parallel to the surface of the workpiece 11 and perpendicular to the cutting direction at the desired cutting depth, measured from the surface of the workpiece 11. This generates a laser beam that is heated to a temperature that produces internal stress that causes the cutting portion 14 to separate from the workpiece 11 at a temperature below the melting point of the cutting surface 13, which does not melt the workpiece 11.

[0076] In this way, the interior of the workpiece 11 is heated by the laser beam 21, making it possible to cut without melting the cutting surface 13.

[0077] In step S14, the cooling unit 40 cools the surface of the workpiece 11 heated by the laser beam 21.

[0078] At this time, the cooling unit 40 can cool the heated cutting portion 14 of the workpiece 11 immediately after the laser generating unit 20 irradiates the workpiece 11 with the laser beam 21.

[0079] Alternatively, the cooling unit 40 can also cool the heated cutting portion 14 of the workpiece 11 by supplying coolant to the whole or part after the laser generating unit 20 irradiates the workpiece 11 with the laser beam 21.

[0080] Furthermore, the coolant removal unit 41 can drive a fan to remove the heated or vaporized coolant that has passed through the heat exchange section 14 by blowing air, thereby preventing interference between the coolant and the laser beam 21.

[0081] As mentioned above, during the process of heating and cooling the workpiece 11 by irradiating the laser beam 21, the control unit 70 controls in real time the diameter and cutting depth of the workpiece 110, the intensity of the laser beam 21 irradiated by the laser generating unit 20, the cutting speed of the workpiece 11 by moving the laser beam 21 along the cutting direction, and the cooling speed based on the amount and speed of the coolant sprayed by the cooling unit 40 (step S16).

[0082] In step S18, the separation unit 60 uses the tensile force provided by the stretching tool to move the cut portion 13 of the workpiece 11 upward and separate it.

[0083] Through the process described above, the present invention can cut a workpiece with thermal brittleness into slices of the required thickness.

[0084] Moreover, the present invention heats and cools the workpiece by irradiating it with a laser beam, thereby cutting the workpiece without melting or vaporizing it and minimizing damage.

[0085] Moreover, the present invention can easily separate the cut portion of the workpiece using the separation unit, thereby improving the flatness of the cut surface.

[0086] Therefore, the present invention improves the operability of cutting operations on the cut portion of the workpiece, and can significantly improve productivity by eliminating or minimizing post-processing of the cut portion, such as polishing processes performed during wafer manufacturing.

[0087] The invention implemented by the inventors has been specifically described above with reference to the embodiments described above. However, the invention is not limited to the embodiments described above. Various changes and modifications can be made without departing from its spirit, which is to be expected.

[0088] Industrial applications

[0089] This invention relates to a laser cutting apparatus and method for slicing workpieces with thermal brittleness to the required thickness using a slicing method.

Claims

1. A laser-based cutting device, characterized in that, include: The laser generating unit (20) generates a laser beam that penetrates the surface of the workpiece (11) and is only partially absorbed. The beam generating optical unit (30) focuses the laser beam into a shape that extends parallel to the surface of the workpiece (11) and perpendicular to the cutting direction at the desired cutting depth measured from the surface of the workpiece (11), generating a laser beam that is heated to a temperature below the melting point of the cutting surface (12) of the workpiece (11) and also to a temperature that generates internal stress that causes the cut portion to separate from the workpiece (11). The starting point generation unit (50) damages the cutting starting point (13) of the outer contour of the cutting surface (12) to be cut in the workpiece (11); and The separation unit (60) separates the cut portions from the processed object (11). The separation unit (60) is composed of one of an outer contour support, an upper close-fitting support, and a tensile force supply unit. The outer contour support is fixed to the outer contour of the cutting part, and the cutting part is separated from the workpiece (11) by the tensile force provided by the tensile tool. The upper close-fitting support is close to the upper part of the cutting part, so that the laser beam penetrates the cutting part and the cutting part is separated from the workpiece (11) by the tensile force. The tensile force supply unit provides tensile force to the lower end of the workpiece (11) and the cutting part. The workpiece is cut to the required thickness by slicing without melting it and to reduce damage. The cutting portion of the workpiece (11) is separated by moving it upward using the separation unit (60).

2. The laser-based cutting device according to claim 1, characterized in that, It also includes a cooling unit (40) that supplies coolant to the cut portion of the heated workpiece (11) immediately after the laser generating unit (20) irradiates the workpiece (11) with a laser beam.

3. The laser-based cutting device according to claim 1, characterized in that, Also includes: Cooling unit (40) supplies coolant to the cut portion of the heated workpiece (11) after the laser generating unit (20) irradiates the workpiece (11) with a laser beam; and The coolant removal unit (41) removes the coolant to prevent interference between the coolant heated or vaporized by heat exchange with the cutting portion and the laser beam.

4. The laser-based cutting apparatus according to claim 2 or 3, characterized in that, The system includes a control unit (70) that controls the driving of the laser generating unit (20), the beam generating optical unit (30), and the cooling unit (40). The control unit (70) generates control signals for the diameter and cutting depth of the workpiece (11), the intensity of the laser beam irradiated by the laser generating unit (20), the cutting speed of the workpiece (11) by moving the laser beam along the cutting direction, and the cooling speed based on the amount and speed of the coolant sprayed by the cooling unit (40).

5. A laser-based cutting method, characterized in that, Includes the following steps: In step (a), the laser generating unit (20) generates a laser beam that penetrates the surface of the workpiece (11) and is only partially absorbed; Step (b) uses the starting point generation unit (50) to damage the cutting starting point (13) of the outer contour of the cutting surface to be cut in the processing object (11); as well as Step (c), the beam generating optical unit (30) focuses the laser beam at the desired cutting depth, measured from the surface of the workpiece (11), into a shape parallel to the surface of the workpiece (11) and perpendicular to the cutting direction, and generates a laser beam that is heated to a temperature below the melting point of the cutting surface (12) of the workpiece (11) and also generates internal stress that causes the cut portion to separate from the workpiece (11); and Step (d) involves using the separation unit (60) to separate the cut portion from the workpiece (11). The workpiece (11) is cut into slices of the required thickness without melting the workpiece and to reduce damage. The cutting portion of the workpiece (11) is separated by moving it upward using the separation unit (60), which consists of one of the outer contour support, the upper close-fitting support, and the tension force supply unit. The outer support is fixed to the outer contour of the cutting part and the cutting part is separated from the workpiece (11) by the tensile force provided by the stretching tool; the upper support is close to the upper part of the cutting part, so that the laser beam penetrates the cutting part and the cutting part is separated from the workpiece (11) by the tensile force; the tensile force supply unit provides tensile force to the lower end of the workpiece (11) and the cutting part.

6. The laser-based cutting method according to claim 5, characterized in that, Step (c) involves using a cooling unit (40) to cool the surface of the workpiece (11) heated by the laser beam. The cooling unit (40) cools the heated workpiece (11) by immediately supplying coolant to the cut portion of the workpiece (11) after the laser generating unit (20) irradiates the workpiece (11) with a laser beam.

7. The laser-based cutting method according to claim 5, characterized in that, Step (c) involves using a cooling unit (40) to cool the surface of the workpiece (11) heated by the laser beam. The coolant removal unit (41) removes the coolant that has been heated or vaporized through heat exchange with the cutting section in order to prevent interference between the coolant and the laser beam. The cooling unit (40) cools the heated workpiece (11) by supplying coolant to the cut portion of the workpiece (11) after the laser generating unit (20) irradiates the workpiece (11) with a laser beam.

8. The laser-based cutting method according to claim 6 or 7, characterized in that, Step (c) uses the control unit (70) to control the diameter and cutting depth of the workpiece (11), the intensity of the laser beam irradiated by the laser generating unit (20), the cutting speed of the workpiece (11) by moving the laser beam along the cutting direction, and the cooling speed based on the amount and speed of the coolant sprayed by the cooling unit (40).

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