Cooling device and cooling method

Abstract

To provide a cooling device and a cooling method that are more excellent in cooling effect than a conventional cooling method using dry ice particles.SOLUTION: A cooling device, which cools a processing part which is an area in vicinity of a tool and a work-piece, comprises: a first injection part which injects a first fluid containing dry ice particles toward the processing part; nd a second injection part which injects a second fluid different from the first fluid toward the processing part. A cooling method, which cools a processing part which is an area in vicinity of a tool and a work-piece, injects a second fluid different from a first fluid containing dry ice particles together with the first fluid toward the processing part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cooling device and a cooling method. [Background technology]

[0002] When a workpiece is machined using a tool, frictional heat is generated between the tool and the workpiece. Because frictional heat can deteriorate the tool and affect machining accuracy, cooling is performed in the machining process around the machining point, which is the contact point between the tool and the workpiece.

[0003] One method known for cooling a processing area is to spray dry ice particles onto the processing area (Patent Documents 1 and 2). This method, known as DIPS, involves generating dry ice particles by controlling the temperature and distance when releasing liquefied carbon dioxide gas, which is filled under high pressure in a liquid state at room temperature, into the atmosphere, and then spraying the dry ice particles on dry air with a dew point of -40°C or lower, a temperature of 60°C, and a pressure of approximately 350 to 450 kPa to cool the processing area.

[0004] The method of spraying dry ice particles is expected to have a physical cooling effect due to the dry ice particles' temperature of -79.8°C, a cooling effect due to the heat of vaporization, and an effect of suppressing temperature rise by reducing the oxygen concentration. The limit oxygen concentration for combustion of materials is generally said to be 17%, but near the processing area where the dry ice particles repeatedly collide and sublimate, the oxygen concentration drops to 14%, making it impossible for the material to continue burning and suppressing temperature rise in the processing area. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-41464 [Patent Document 2] Japanese Patent Application Publication No. 2018-187765 Summary of the Invention [Problem to be solved by the invention]

[0006] Cooling methods using dry ice microparticles can be expected to have the effects described above, but with conventional cooling methods using dry ice microparticles, the dry ice microparticles may not be effectively supplied to the tip of the tool due to the direction of tool movement, and sufficient cooling effect may not be achieved.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cooling device and a cooling method that have a superior cooling effect compared to conventional cooling methods that use dry ice particulates. [Means for solving the problem]

[0008] [Cooling device] The cooling device of the present invention is a device for cooling a processing portion, which is an area near a tool and a workpiece, and is equipped with a first injection portion that injects a first fluid containing dry ice microparticles toward the processing portion, and a second injection portion that injects a second fluid, different from the first fluid, toward the processing portion.

[0009] [Cooling method] The cooling method of the present invention is a method for cooling the processing area, which is the area near the tool and the workpiece, by spraying a second fluid, separate from the first fluid, toward the processing area together with a first fluid containing dry ice particles.

[0010] In this application, the phrase "directed toward the processing portion" includes not only the case of directing toward the processing point, but also the case of directing toward the area in the vicinity of the processing point. [Effects of the Invention]

[0011] According to the present invention, a second fluid containing dry ice microparticles is sprayed toward the processing area together with a first fluid containing dry ice microparticles, and the residence time of the dry ice microparticles at the processing area is increased, thereby increasing the amount of dry ice microparticles that the tool entrains in its rotational direction, allowing for effective cooling all the way to the tip of the tool, thereby achieving a higher cooling effect than conventional cooling methods. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1A is a front view showing an example of a cooling device, and FIG. 1B is a bottom view of FIG. [Figure 2] FIG. 2( a ) is a schematic explanatory diagram of a first injection section, and FIG. 2( b ) is a schematic explanatory diagram of a second injection section. [Figure 3] FIG. 4 is an explanatory diagram of the internal structure of the first injection nozzle. [Figure 4] 1(a) and 1(b) are explanatory diagrams illustrating the positional relationship between the first injection part and the second injection part. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Embodiment of Cooling Device) An example of an embodiment of a cooling device of the present invention will be described with reference to the drawings. The cooling device of this embodiment is a cooling device that cools a processing portion X, which is an area in the vicinity of a tool T and a workpiece W. Here, the tool T includes a cutting tool, a grinding tool, a drilling tool, etc., and the workpiece W includes a metal, ceramic, resin, etc.

[0014] As an example, the cooling device shown in Fig. 1 includes a first injection unit 10 that injects a first fluid toward the processing area X (Figs. 4(a) and (b)), and a second injection unit 20 that injects a second fluid, different from the first fluid, toward the processing area X. The first injection unit 10 and the second injection unit 20 are disposed on the outer periphery of the tool T when in use.

[0015] The first injection section 10 of this embodiment injects a mixed fluid containing dry ice particles and gas as the first fluid, and is equipped with a liquefied carbon dioxide gas supply system 11, an injection gas supply system 12, a flow pipe 13, and a first injection nozzle 14.

[0016] 2(a), the liquefied carbon dioxide gas supply system 11 includes a high-pressure gas container 11a that supplies liquefied carbon dioxide gas, a gas inlet 11b that takes in liquefied carbon dioxide gas supplied from the high-pressure gas container 11a, a gas filter 11c that removes impurities from the taken-in liquefied carbon dioxide gas, a liquefied carbon dioxide gas solenoid valve 11d that adjusts the flow rate and pressure of the liquefied carbon dioxide gas, and a needle valve 11e that adjusts the amount of liquefied carbon dioxide gas that is discharged. These are connected in this order from the upstream side and function as a series of flow paths through which the liquefied carbon dioxide gas flows.

[0017] The injection gas supply system 12 includes an injection gas supply source 12a, a gas inlet 12b that takes in the gas supplied from the injection gas supply source 12a, a gas electromagnetic valve 12c that adjusts the flow rate and pressure of the gas, a heater 12d that heats the gas, a gas filter 12e that removes impurities from the taken-in gas, and a relief valve 12f that releases pressure when excessive pressure occurs. These components are connected in this order from the upstream side and function as a series of flow paths through which the gas flows.

[0018] The gas supplied by the injection gas supply system 12 is used to inject (transport) the dry ice particles to the processing point. The injection gas may be nitrogen gas, carbon dioxide gas, argon gas, compressed air, or the like.

[0019] In this embodiment, compressed factory air is heated to about 60° C. by a heater 12d and dried, and used as the injected gas. A spot heater or the like can be used as the heater 12d.

[0020] The flow pipe 13 is a pipe member for introducing the liquefied carbon dioxide gas that has passed through the liquefied carbon dioxide gas supply system 11 and the gas that has passed through the injection gas supply system 12 into the first injection nozzle 14, and is equipped with a liquefied carbon dioxide gas flow path 13a through which the liquefied carbon dioxide gas passes and a gas flow path 13b through which the gas passes.

[0021] The upstream side of the liquefied carbon dioxide gas flow path 13a is connected to the downstream end side of the liquefied carbon dioxide gas supply system 11, and the upstream side of the gas flow path 13b is connected to the downstream end side of the injection gas supply system 12. In addition, the downstream sides of the liquefied carbon dioxide gas flow path 13a and the gas flow path 13b are both connected to a first injection nozzle 14.

[0022] The first injection nozzle 14 is a component that generates and injects dry ice particles. As shown in Fig. 3, the first injection nozzle 14 of this embodiment includes a hollow outer tube 14a and a hollow inner tube 14b. The internal space of the inner tube 14b functions as a liquefied carbon dioxide gas passage 14c through which the liquefied carbon dioxide gas passes, and the space between the inner tube 14b and the outer tube 14a functions as a gas passage 14d through which the gas passes.

[0023] A mixing chamber 14e is provided at the end of the liquefied carbon dioxide gas passage 14c, where the liquefied carbon dioxide gas that has passed through the liquefied carbon dioxide gas passage 14c and the gas that has passed through the gas passage 14d are mixed. The mixing chamber 14e functions as a space in which the liquefied carbon dioxide gas expands to produce dry ice particles.

[0024] The particle size of the dry ice particles generated in the mixing chamber 14e is approximately 30 μm. This particle size is an example, and the dry ice particles may be larger or smaller than this. For example, the particle size may be approximately 10 to 50 μm, preferably approximately 20 to 40 μm, and more preferably approximately 25 to 35 μm.

[0025] A first injection passage 14f having an inner diameter smaller than that of the mixing chamber 14e is provided downstream of the mixing chamber 14e, and a first injection port 14g is provided at the tip of the first injection passage 14f. The dry ice particles generated in the mixing chamber 14e pass through the first injection passage 14f together with the gas that has passed through the gas passage 14d, and are injected as a mixed fluid from the first injection port 14g at the tip of the first injection passage 14f toward the processing area X.

[0026] In this embodiment, the injection pressure of the mixed fluid is set to about 450 kPa. If the influence of the second fluid (gas) injected from the second injection part 20 is not taken into consideration, the mixed fluid is set to reach a range of about φ12 to φ20 mm from the center of the injection point. However, this value is just an example, and the injection pressure of the mixed fluid can be higher or lower.

[0027] The temperature of the mixed fluid injected from the first injection part 10, specifically, the temperature when measured at a position 50 mm from the tip of the first injection nozzle 14, is about −12° C. However, this value shows an example of the optimum temperature of the mixed fluid, and the temperature of the mixed fluid may be higher or lower than this.

[0028] The configuration of the first jetting unit 10 described here is one example, and the first jetting unit 10 may have any structure as long as it can generate dry ice microparticles and jet them toward the processing area X.

[0029] The second jetting unit 20 is a member that jets a fluid toward the processing area X from a direction different from that of the first jetting unit 10. As shown in Fig. 2(b), the second jetting unit 20 of this embodiment includes a fluid supply system 21, a fluid circulation pipe 22, and a second jet nozzle 23. In this embodiment, the second jetting unit 20 jets a gas (air) that does not contain dry ice particles as the second fluid.

[0030] The fluid supply system 21 includes a compressed fluid source (e.g., a compressor) 21a that supplies compressed fluid, a fluid inlet 21b that takes in fluid supplied from the compressed fluid source 21a, a fluid electromagnetic valve 21c that adjusts the flow rate and pressure of the fluid, a fluid filter 21d that removes impurities from the taken-in fluid, and a relief valve 21e that releases pressure when excessive pressure occurs. These are connected in this order from the upstream side and function as a series of flow paths through which the fluid flows.

[0031] A coolant hose or the like, to the tip of which the second injection nozzle 23 can be attached, can be used as the fluid circulation pipe 22. In this embodiment, a coolant hose having flexibility so that it can be deformed into a desired shape is used as the fluid circulation pipe 22.

[0032] A second injection nozzle 23 is connected to the tip of the fluid circulation pipe 22, and injects the gas that has passed through the fluid circulation pipe 22. A second injection port 23a is provided at the tip of the second injection nozzle 23, and injects the gas that has passed through the fluid circulation pipe 22.

[0033] In this embodiment, two second injection units 20 having the same structure are provided. Both second injection units 20 are arranged so that their second injection ports 23a face the processing area X. The two second injection units 20 are provided in different orientations so that they can inject the fluid (gas) from different directions toward the processing area X. Furthermore, both second injection nozzles 23 are also provided in a different orientation from the first injection nozzle 14 so that they can inject the fluid (gas) toward the processing area X from a different direction from the first injection unit 10.

[0034] Specifically, as shown in Figure 4(a), when the first injection section 10 and the two second injection sections 20 are viewed from the planar side, the angle θ1 formed by the injection direction line L1 of the first injection nozzle 14 and the injection direction line L2 of one of the second injection nozzles 23 is approximately 120 degrees, the angle θ2 formed by the injection direction line L1 of the first injection nozzle 14 and the injection direction line L3 of the other second injection nozzle 23 is approximately 120 degrees, and the angle θ3 formed by the injection direction lines L2, L3 of the two second injection nozzles 23 is approximately 120 degrees.

[0035] This angle is one example, and the first injection section 10 and the second injection section 20 can also be provided at angles other than these. For example, the respective angles θ1, θ2, and θ3 can be set to approximately 110 to 150 degrees. However, since the purpose of injecting gas from the second injection nozzle 23 is to slow down the movement of the mixed fluid injected from the first injection nozzle 14 (suppress diffusion) and increase the residence time in the vicinity of the processing area X, the second injection nozzle 23 needs to be provided in an orientation that can achieve this purpose.

[0036] For example, if the first injection nozzle 14 is arranged from one side of the imaginary line VL that bisects the tool T located at the center of the processing area X, the second injection nozzle 23 can be arranged from the other side of the imaginary line VL toward the processing area X.

[0037] 4(b), the first injection part 10 in this embodiment is provided so that the angle θ4 between the injection direction line L1 of the first injection nozzle 14 and the processed surface of the workpiece W is approximately 60 degrees, and the second injection part 20 is provided so that the angle θ5 between the injection direction lines L2, L3 of the second injection nozzle 23 and the processed surface of the workpiece W is approximately 30 degrees. This angle is one example, and the first injection part 10 and the second injection part 20 can also be provided at angles other than this.

[0038] In this embodiment, the injection pressure of the gas injected from the second injection part 20 is set to about 350 kPa, which is lower than the injection pressure of the mixed fluid. The injection pressure of the gas can also be adjusted within a certain range, but in any case, it is desirable to make it lower than the injection pressure of the mixed fluid.

[0039] If the injection pressure of the gas is higher than the injection pressure of the mixed fluid, it may be difficult for the mixed fluid to reach the processing area X. However, by making the injection pressure of the gas lower than the injection pressure of the mixed fluid, it is possible to ensure that the mixed fluid reaches the processing area X.

[0040] The configuration of the second injection section 20 described here is one example, and the second injection section 20 may have any structure as long as it is capable of injecting a fluid to slow down the movement of the second fluid.

[0041] (Embodiment of Cooling Method) Next, an example of an embodiment of the cooling method of the present invention will be described. In the cooling method of the present application, a first fluid containing dry ice particles (in this embodiment, a mixed fluid containing dry ice particles and gas) and a second fluid (in this embodiment, gas) separate from the first fluid are sprayed toward the processing area X. At this time, the second fluid is sprayed toward the processing area X from a direction different from that of the first fluid.

[0042] The second fluid is preferably injected from a direction that slows down the movement of the mixed fluid injected from the first injection nozzle 14 and increases the residence time in the vicinity of the processing area X, specifically, from a direction as described in the embodiment of the cooling device. The second fluid can also be injected toward the processing area X from two or more different directions.

[0043] The ejection pressure of the first fluid can be, for example, about 450 kPa, and the ejection pressure of the second fluid can be, for example, about 350 kPa. However, these numerical values ​​are just an example, and the ejection pressures of the first fluid and the second fluid can be higher or lower. For example, the ejection pressure of the first fluid is preferably about 350 to 475 kPa, and the ejection pressure of the second fluid is preferably about 300 to 425 kPa, and the ejection pressure of the second fluid is preferably at least 50 kPa lower than the ejection pressure of the first fluid.

[0044] In either case, it is desirable to set the injection pressure of the second fluid lower than the injection pressure of the first fluid, in order to achieve the purpose of slowing down the movement of the mixed fluid injected from the first injection nozzle 14 and lengthening the residence time in the vicinity of the processed portion X.

[0045] In the cooling method of this embodiment, the movement of the mixed fluid (especially the dry ice particles) can be slowed down and made to remain near the processing area X, and the remaining dry ice particles are caught up in the rotation of the tool T, so that the dry ice particles and the sublimated carbon dioxide gas reach the entire tip of the tool T.

[0046] This provides a physical cooling effect of the dry ice microparticles, a cooling effect due to the heat of vaporization of the dry ice microparticles, and a temperature rise suppression effect due to a decrease in oxygen concentration at the processing area X, including the tip of the tool T, thereby achieving a higher cooling effect than conventional methods using dry ice microparticles.

[0047] For ease of explanation, the present application describes the cooling device and the cooling method separately, but the matters described in the cooling device embodiment can also be applied to the cooling method, and conversely, the matters described in the cooling method embodiment can also be applied to the cooling device.

[0048] (Variation) The configurations of the above-described embodiments are merely examples, and the cooling device and cooling method of the present invention are not limited to the configurations of the above-described embodiments. The cooling device and cooling method of the present invention can be modified, such as by replacing, omitting, or adding components, within the scope of achieving the intended purpose. For example, the following modifications are possible.

[0049] -Variation 1- In each of the above embodiments, an example is given in which a gas not containing dry ice particles is sprayed from the second spraying section 20, but the second fluid sprayed from the second spraying section 20 may also be a mixed fluid (a fluid containing dry ice particles) similar to the mixed fluid sprayed from the first spraying section 10.

[0050] In this case, the mixed fluid may be jetted from some of the two or more second jetting portions 20, or may be jetted from all of the second jetting portions 20.

[0051] -Variation 2- In each of the above embodiments, the case where there are two second injection units 20 is taken as an example, but there may be one or three or more second injection units 20. In either case, the second injection unit 20 needs to be installed at a position suited to its purpose of slowing down the movement of the mixed fluid injected from the first injection unit 10 and lengthening the residence time in the vicinity of the processing area X.

[0052] The embodiments disclosed herein are merely examples and are not intended to limit the technical scope of the cooling device and cooling method of the present invention. The technical scope of the cooling device and cooling method of the present invention is defined by the claims. The technical scope of the present invention also includes equivalents to the claims.

[0053] (Experimental example) The applicant of the present invention conducted an experiment to confirm the effects of the cooling device and cooling method of the present embodiment. The outline and results of the experiment are as follows.

[0054] <Experiment Overview> An overview of Experiments 1 to 5 is shown in Table 1. [Table 1]

[0055] In experiments 1 and 2, shape cutting was performed by scanning line step processing, in experiments 3 and 4, shape cutting was performed by circular step processing, and in experiment 5, hole drilling was performed.

[0056] In Experiments 1 and 2, a ceramic plate with a thickness of 20 mm before firing was used as the workpiece W, in Experiments 3 and 5, a ceramic plate with a thickness of 15 mm before firing, and in Experiment 4, a thin ceramic plate with a thickness of 2 mm. The other machining tools, tool rotation speeds, feed rates, and Z cutting depths used in each experiment are as shown in Table 1.

[0057] In each experiment, a mixed fluid containing dry ice particles and gas was sprayed from the first spraying unit 10, and a gas not containing dry ice particles was sprayed from the second spraying unit 20 toward the processing area X. Two second spraying units 20 were used, and the gas was sprayed from these second spraying units 20 toward the processing area X from two directions.

[0058] The first injection section 10 and the two second injection sections 20 were installed so that, when viewed from above, the angle between the injection direction line L1 of the first injection nozzle 14 and the injection direction line L2 of one of the second injection nozzles 23 was 120 degrees, the angle between the injection direction line L1 of the first injection nozzle 14 and the injection direction line L3 of the other second injection nozzle 23 was 120 degrees, and the angle between the injection direction lines L2 and L3 of the two second injection nozzles 23 was 120 degrees.

[0059] The injection pressure of the mixed fluid from the first injection section 10 was approximately 450 kPa, and the injection pressure of the gas from both second injection sections 20 was approximately 350 kPa. The distance from the first injection port 14g and the second injection port 23a to the processing section X was approximately 50 mm. In all experiments, the flow rate of the liquefied carbon dioxide gas was approximately 110 g / min, and the primary side temperature at injection was 60°C. The primary side temperature at injection means the factory air, which is compressed air, heated by the heater 12d.

[0060] <Experimental Results> In Experiment 1, the machining results were very good. The machined surface of workpiece W was very flat, a significant improvement compared to when DIPS was not used. In addition, no chips or adhesion of the base material was observed on the surface of tool T, and it was in a condition where it could continue machining in the same way.

[0061] In Experiment 2, as in Experiment 1, very good results were obtained. The machined end surface of the workpiece W was very flat, and it was confirmed that the quality was incomparable to that of conventional machining (dry machining, which will be described later). Considering that the feed rate was 1.5 times that of Experiment 1, which shortened the machining time, and that the post-process of finishing was no longer necessary, it can be said that this is a significant improvement in work efficiency.

[0062] In Experiment 3, very good results were obtained, similar to Experiments 1 and 2. In Experiment 4, very good results were obtained, similar to Experiments 1 to 3. No burrs were observed on either the tool T or the workpiece W, and no molten chips were observed.

[0063] Experiment 5 also yielded very good results, similar to Experiments 1 to 4. There were no major problems with machinability, and it was confirmed that chips were completely removed without welding or adhesion. There were no large burrs at the exit of Tool T, and no major problems were observed with hole quality.

[0064] <Consideration> Conventionally, ceramics have been processed using dry machining without the use of oil, with room temperature air being used for cooling. However, with the conventional method using air, the end face shape of the processed product was very poor after machining, requiring additional machining of the end face, which was a major issue in manufacturing.

[0065] One of the reasons for the poor end face shape of the workpiece after machining is thought to be that the significant temperature rise in the machining area causes chips to melt and adhere to the tool surface, reducing the tool's sharpness. The adhered chips cause a decrease in the tool's cutting ability and increase cutting friction, leading to further chip welding. As a result, the end face of the workpiece is often crushed irregularly, resulting in an uneven, non-flat surface.

[0066] From this experiment, it was confirmed that the cooling method used in this experiment slows down the movement of the mixed fluid (especially the dry ice particles) and causes it to remain near the processing area X, thereby achieving the physical cooling effect of the dry ice particles, the cooling effect due to the heat of vaporization of the dry ice particles, and the effect of suppressing temperature rise by reducing the oxygen concentration.

[0067] This experiment also confirmed that the spray pressure of dry ice particles has the effect of preventing chip adhesion and removing chips, eliminating the adverse effects caused by chips adhering to the tool surface.

[0068] In the above experiment, ceramics (ceramic plates and thin ceramic plates) were used as the workpieces, but the cooling method used in this experiment achieves a high cooling effect by increasing the residence time of the dry ice microparticles in the processing area. As long as there are no factors that hinder the residence of the dry ice microparticles, the same effect can be obtained with workpieces other than ceramics, such as metals and resins. [Industrial Applicability]

[0069] The cooling device and cooling method of the present invention can be used when processing various workpieces that have traditionally required cooling, and can be particularly used favorably when processing metals, ceramics, resins, etc. In addition, they can also be used in the manufacturing process of semiconductors, etc. [Explanation of symbols]

[0070] 10 First injection part 11 Liquefied carbon dioxide supply system 11a High-pressure gas cylinders 11b Gas inlet 11c Gas Filter 11d Liquefied carbon dioxide solenoid valve 11e Needle valve 12 Injection gas supply system 12a Propellant gas supply source 12b Gas inlet 12c Gas solenoid valve 12d heater 12e Gas Filter 12f Relief valve 13 Flow pipe 13a Liquefied carbon dioxide gas flow path 13b Gas flow path 14 First injection nozzle 14a outer tube 14b Inner tube 14c Liquefied carbon dioxide gas passage 14d Gas passage 14e Mixing room 14f First injection path 14g First injection port 20 Second injection part 21 Fluid supply system 21a Compressed fluid source 21b Fluid inlet 21c Fluid solenoid valve 21d Fluid Filter 21e Relief valve 22 Fluid flow pipe 23 Second injection nozzle 23a Second injection port L1 First nozzle spray direction line L2: Spray direction line of one of the second jet nozzles L3: The other secondary nozzle's jet direction line T-tool VL Virtual Line W Workpiece X Processing section

Claims

1. In a cooling device for cooling a processing portion which is a region near a tool and a workpiece, a first jetting unit that jets a first fluid containing dry ice particles toward the processing unit; A second injection unit is provided which injects a second fluid different from the first fluid toward the processing unit. A cooling device characterized by:

2. 2. The cooling device according to claim 1, the second ejection portion is provided in an orientation such that it can eject the second fluid from a direction different from that of the first ejection portion; A cooling device characterized by:

3. 3. The cooling device according to claim 1 or 2, the second injection portion is provided in a direction capable of injecting a fluid in a direction that decelerates the movement of the mixed fluid of the first fluid injected from the first injection portion; A cooling device characterized by:

4. 3. The cooling device according to claim 1 or 2, The second fluid is a fluid containing dry ice particles or a fluid not containing dry ice particles. A cooling device characterized by:

5. 3. The cooling device according to claim 1 or 2, Two or more second injection parts are provided, A cooling device characterized by:

6. 6. The cooling device according to claim 5, The first jetting portion and the two or more second jetting portions are provided in such a direction that they can jet fluid from different directions. A cooling device characterized by:

7. 3. The cooling device according to claim 1 or 2, The injection pressure of the second injection section is lower than the injection pressure of the first injection section. A cooling device characterized by:

8. In a cooling method for cooling a processing portion, which is a region in the vicinity of a tool and a workpiece, A second fluid different from the first fluid is sprayed toward the processed portion together with the first fluid containing the dry ice particles. A cooling method characterized by:

9. The cooling method according to claim 8, The second fluid is sprayed toward the processed portion from a direction different from that of the first fluid. A cooling method characterized by:

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