Method and device for cooling member to be cooled

Abstract

The present invention relates to a cooling method for cooling a member to be cooled using a cooling device, the cooling device comprising: a plurality of spray nozzles for spraying a droplet group onto a heated member to be cooled to cool the member to be cooled; an injection adjustment unit; and a control unit for controlling the ejection of the droplets, the control unit causing the ejection of the droplet group to be pulsed and repeating the pulsed ejection in accordance with a set value and controlling the ejection of the droplet group, and the cooling method for repeatedly ejecting the droplet group to the heated member to be cooled in a pulsed manner and cooling the member to be cooled. At least one of the magnitude of the pulse, the pulse width, and the pulse interval is varied over time.

Description

[0001] This invention application is a divisional application of the invention application with an international filing date of October 14, 2020, international application number PCT / JP2020 / 038820, national application number 202080073643.2 which entered the Chinese national phase, and the invention title "Cooling method and cooling device for cooled components". Technical Field

[0002] The present invention relates to a cooling method and a cooling apparatus for cooling a component heated to a high temperature by spraying a group of droplets. Background Technology

[0003] Oil quenching of steel offers the advantage of rapidly cooling the high-temperature region (the ferrite precipitation temperature range) while simultaneously allowing for gradual cooling in the low-temperature region where martensitic transformation occurs. This provides the benefit of ensuring steel quality while preventing quenching cracks. However, oil quenching also presents disadvantages such as fire hazards and a deteriorated working environment caused by oil fumes. Therefore, alternative cooling methods to oil quenching have been investigated, and spray cooling has been proposed. Spray cooling utilizes a series of microparticle-sized droplets to cool the material through the movement of sensible and latent heat.

[0004] Numerous studies have reported on controlling the cooling of materials such as steel in spray cooling by increasing or decreasing the spray flow rate.

[0005] For example, in Patent Document 1, the jet flow rate can be adjusted by providing multiple jet nozzles and changing the number of jet nozzles used in cooling.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 6-322449 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in oil quenching, a cooling state is obtained in which the cooling rate varies around 500°C during the temperature drop from 700°C to 400°C. That is, regarding the temperature at a depth of 10 mm from the surface of the steel 100, a cooling rate of 50°C / min is obtained from 700°C to 500°C, and approximately 10°C / min is obtained from 500°C to 400°C. When using the spraying of droplet groups as an alternative to oil quenching, the same cooling state is required.

[0011] However, if this state is to be achieved simply by reducing the jet flow rate from each nozzle, then within a unit area (1m²) below a certain constant...2 The jet flow rate (L / m) 2 When the temperature reaches 0.00000 min, the microparticle-sized droplet group evaporates before reaching the high temperature of the steel, becoming the same cooling state as air cooling, which means that the oil quenching characteristics cannot be obtained.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a cooling method and cooling apparatus for a cooled component that can obtain a desired cooling state by pulsed jetting of droplet groups.

[0013] Methods for solving problems

[0014] That is, the first aspect of the cooling method for the cooled component of the present invention is a cooling method that sprays a group of liquid droplets onto the heated component to cool it, characterized in that...

[0015] The jetting of the droplet group is pulsed and repeated, with at least one of the pulse size, pulse width, and pulse interval changing over time.

[0016] The invention of the cooling method for the cooled component in the second manner is characterized in that, based on the invention of the aforementioned manner, the cooling performance is adjusted according to the changes over time.

[0017] The invention of the cooling method for the cooled component in the third manner is characterized in that, based on the invention of the aforementioned manner, in adjusting the cooling performance, the unit area (m²) of the droplet group at each fixed time interval is determined. 2 () average jet flow rate.

[0018] The invention of the cooling method for the cooled component in the fourth manner is characterized in that, based on the invention of the aforementioned manner, the size of the pulse is set to a unit area (m²) of the surface of the cooled component that the droplet array can reach. 2 The jet flow rate is above 1000 rpm.

[0019] The invention of the cooling method for the cooled component in the fifth manner is characterized by, based on the invention of the aforementioned manner, at least comprising: an initial first step that maximizes the cooling performance; a second step after the first step that relatively reduces the cooling performance relative to the first step; and a third step after the second step that relatively reduces the cooling performance relative to the second step.

[0020] In the first step, the pulse size and pulse width are set to the largest relative first pulse size and first pulse width. In the second step, the pulse size is set to the second pulse size, which is smaller than the first pulse size, and the pulse width is set to the second pulse width, which is smaller than the first pulse width. The pulse interval is set to the second pulse interval. In the third step, the pulse size is set to the third pulse size, which is less than the second pulse size, and the pulse width is set to the third pulse width, which is less than the second pulse width. The pulse interval is set to the third pulse interval, which is greater than the second pulse interval.

[0021] The invention of the cooling method for the cooled component in the sixth manner is characterized in that, based on the invention of the aforementioned manner, the droplet group is sprayed using a single-fluid nozzle.

[0022] The invention of the cooling method for the cooled component in the seventh manner is characterized in that, based on the invention of the aforementioned manner, the cooled component is steel with a thickness of 200 mm or more.

[0023] The invention of the cooling method for the cooled component in the eighth manner is characterized in that, based on the invention of the aforementioned manner, cooling based on the droplet group achieves the same cooling state as cooling based on oil cooling.

[0024] The first aspect of the cooling device for the cooled component of the present invention is characterized by having:

[0025] Multiple nozzles are used to spray droplets onto the heated component to cool it.

[0026] A jet adjustment unit that adjusts the jet volume of the droplet assembly ejected from the nozzle; and

[0027] The control unit controls the ejection of the droplet assembly from the nozzle.

[0028] The control unit controls the spraying of the droplet group in a pulsed manner corresponding to a set value, and repeats the pulsed spraying, and controls the spraying of the droplet group in such a manner that at least one of the pulse size, pulse width, and pulse interval changes over time.

[0029] The invention of the cooling device for the cooled component in the second manner is characterized in that, based on the invention of the aforementioned manner, the nozzle is composed of multiple categories.

[0030] The invention of the cooling device for the cooled component in the third manner is characterized in that, based on the invention of the aforementioned manner, the injection adjustment unit is capable of switching the type of the injection nozzle used.

[0031] The invention of the cooling device for the cooled component in the fourth aspect is characterized in that, based on the invention of the aforementioned aspects, the control unit measures the temperature of the cooled component being cooled and adjusts the jet flow rate of the droplet assembly based on the measurement result.

[0032] The invention of the cooling device for the cooled component in the fifth manner is characterized in that, based on the invention of the aforementioned manner, the nozzle is a single-fluid nozzle.

[0033] It should be noted that the pulse size represents the pulse height, which in this application refers to the jet flow rate of the droplet group. The pulse width represents the pulse width, which in this application represents the time of jetting the droplet group. The pulse interval represents the interval between pulses, which in this application represents the time from the end of jetting to the start of the next jetting.

[0034] The effects of the invention

[0035] That is, according to the present invention, it is possible to use pulse jets of droplet arrays to cool the component to a desired cooling state.

[0036] For example, in the quenching of steel, pulse width modulation (PWM) control can arbitrarily determine the pulse time and pulse interval during cooling, thereby determining the area per unit area (1m²) at a given time interval. 2 The average jet flow rate,

[0037] Therefore, when the temperature at a depth of 10 mm from the surface of steel 100 is 700°C to 500°C, most droplet groups can reach a larger unit area (1 m²) of the high-temperature surface of the steel. 2 The jet flow rate is cooled by continuous jetting.

[0038] Furthermore, when the temperature at a depth of 10 mm from the surface of the steel 100 is 500℃ to 400℃, compared to the case where the temperature at a depth of 10 mm from the surface of the steel 100 is 700℃ to 500℃, spraying with a smaller jet flow rate, pulse width, and larger pulse interval results in a smaller number of droplet groups reaching the high-temperature surface of the steel, thus creating a smaller unit area (1m²). 2 () average jet flow rate.

[0039] As a result, the characteristics of oil quenching, namely a larger cooling rate at 700℃ to 500℃ and a smaller cooling rate at 500℃ to 400℃, can be obtained through continuous injection and pulse injection. Attached Figure Description

[0040] Figure 1 This is a front view of a cooling device according to one embodiment of the present invention.

[0041] Figure 2This is a top view of a cooling device according to one embodiment of the present invention.

[0042] Figure 3 This is a graph showing the measured values ​​and analytical results of the cooling state in oil cooling.

[0043] Figure 4 The heat transfer coefficient for oil cooling is obtained through analytical inverse calculation using FEM.

[0044] Figure 5 (a) is a graph showing the time variation of the jet flow rate per unit area when cooling of steel is achieved by the required continuous jetting. Figure 5 (b) is a graph showing the time variation of the jet flow rate in one embodiment of cooling steel by the required continuous jetting.

[0045] Figure 6 This is a graph showing the temperature change of steel when cooling is achieved by varying the jet flow rate of the droplet group and through continuous jetting.

[0046] Figure 7 This is a graph showing the time variation of the jet flow rate of the droplet group caused by pulsed jetting of the droplet group.

[0047] Figure 8 This is a graph showing the temperature changes when cooling steel by a cooling method according to this embodiment and when cooling steel by oil quenching. Detailed Implementation

[0048] The following is based on Figure 1 , 2 This invention will now be used to illustrate one embodiment of the cooling device.

[0049] The cooling device 1 has a plurality of nozzles 2 (e.g., 48) arranged around the steel 100 at four locations along the longitudinal direction. The steel corresponds to the part to be cooled according to the present invention. The part to be cooled can be a metal part other than steel, or other non-metallic parts.

[0050] It should be noted that the configuration of the nozzles is not limited to those described above, and the appropriate position and number can be changed according to the type and shape of the part being cooled.

[0051] The nozzle 2 is connected to the piping 3, and the piping 3 is connected to the jet adjustment unit 4. The jet adjustment unit 4 is connected to a water source (not shown) to supply water as a droplet assembly. The water source may include a water tank or the like, and is pressurized by a pressurizing unit to supply water. It is connected to a tap water supply path, so tap water can be used as the water source, and the pressurizing unit can also be used to pressurize the water. It should be noted that in this embodiment, water is described as the material used for the droplet assembly; however, the present invention can also use liquids other than water.

[0052] The nozzle's construction is not specific, as long as it can produce the desired droplet configuration. The nozzle can also be composed of multiple types, and the spray adjustment unit can switch the type of nozzle used during cooling.

[0053] Preferably, the droplets have an appropriate size; for example, the droplet diameter is preferably 100 μm or more and 1500 μm or less. It should be noted that the size of the droplets in this invention is not specific.

[0054] In this embodiment, the nozzle 2 is a single-fluid nozzle. The nozzle of the present invention is not limited to a single-fluid nozzle; it can also be a dual-fluid nozzle using air or the like. However, in a dual-fluid nozzle, the droplet range widens due to airflow, potentially worsening the working environment and hindering the maintenance and management of surrounding equipment. Furthermore, it increases costs due to equipment investment. Therefore, in this embodiment, a single-fluid nozzle is preferred.

[0055] In addition, this embodiment describes a scheme in which each nozzle 2 is connected to the same piping 3, but piping may also be used separately for each nozzle or for each nozzle in a specific group.

[0056] Furthermore, while the same reference numerals are used to indicate and describe nozzle 2, nozzles of different types and sizes, such as droplet size and spray volume, may also be used. Different types of nozzles allow for a fixed installation location, and the nozzles used can be switched between the same and different locations during cooling.

[0057] The jet adjustment unit 4 is connected to the control unit 5 to control the jetting of the droplet group performed by the jet adjustment unit 4.

[0058] The jet adjustment unit 4 includes an on / off valve for switching the jet on and off, a flow regulating valve, and a flow meter (none shown). The flow meter readings are sent to the control unit 5. Additionally, a switching unit for switching the jet nozzles supplying water can be provided.

[0059] In the above configuration, the pulsed jetting of the droplet group ejected from the nozzle 2 can be achieved by the operation of the opening and closing valve, and the pulse width and pulse interval can be adjusted. Furthermore, the pulse size can be adjusted by regulating the flow rate through the flow regulating valve.

[0060] Furthermore, when a switching unit is included, the type of nozzle used can be changed by switching the water supply piping. The switching unit can be operated manually or controlled by the control unit 5.

[0061] The control unit 5 consists of a CPU, a ROM storing the program that operates on the CPU, RAM serving as the operating area, and a storage unit storing the program, operation parameters, etc. Alternatively, it can be configured with an operation unit capable of setting the size, width, and interval of pulses over time. These parameters can be changed within the operation unit.

[0062] The control unit 5 can control the injection adjustment unit 4 to control the opening and closing action of the on-off valve, the opening degree of the flow regulating valve, the switching action of the switching unit, etc.

[0063] The droplet group 10 ejected from the nozzle 2 can be sprayed onto the steel 100 to cool the steel 100.

[0064] Next, the cooling method using the above-described cooling device 1 will be explained.

[0065] First, prepare 100g of steel for the experiment.

[0066] In this example, steel 100 is made of NiCrMo steel, is cylindrical in shape, weighs 670 kg, has a diameter of 300 mm, and a length of 1200 mm.

[0067] It should be noted that, as a whole, the size of the cooled component is not limited in this invention. As for the steel, a minimum weight of at least 100 kg and a minimum thickness (in a cylinder) are acceptable. ( ) refers to materials with a minimum size of 200mm or more.

[0068] Next, based on actual temperature measurements during oil quenching starting from 860℃, the heat transfer coefficient during oil cooling was calculated analytically using the FEM (Finite Element Method). The measured temperature change (exp.) and the analytically calculated temperature change (sim.) are shown below. Figure 3 The obtained heat transfer coefficient is shown in Figure 4 It should be noted that, in Figure 3 In this context, "D / 4" indicates a position where the depth from the surface is 1 / 4 of the diameter (D), "D / 8" indicates a position where the depth from the surface is 1 / 8 of the diameter (D), and "10mm depth" indicates a position where the depth from the surface is 10mm. Furthermore, based on literature values, the relationship between the flow rate of the droplet assembly and the heat transfer coefficient is calculated, and the corresponding unit area (m²) for the heat transfer coefficient during oil quenching is determined according to temperature.2 The results of the jet flow rate are shown in Figure 5 (a)

[0069] Figure 5 (a) is a graph showing the time variation of the jet flow rate per unit area during steel cooling via the required continuous jetting. To achieve this state, the jet flow rate, pulse width, and pulse interval need to be adjusted according to the shape of the steel, the extent of the droplet formation, the jetting angle, and the positional relationship between the steel and the cooling device. Figure 5 The flow rate per unit area shown in (a) is calculated for a surface area of ​​approximately 1 m². 2 The results of the injection flow rate under the condition of 100 steel spraying are shown in Figure 5 (b)

[0070] Figure 6 Is Figure 5 The result of continuously spraying droplet arrays onto steel heated to above 800°C under conditions (b). Figure 6 In the study, it was observed that the temperature decreased at a depth of 10 mm from the steel surface, then rose again after reaching approximately 500°C. This suggests that, due to the changes in steel temperature and spraying conditions over time, there is a possibility that the atomized droplet arrays could evaporate upon reaching the high temperature of the steel. It should be noted that... Figure 6 In the text, "D / 8" indicates a position where the depth from the surface is 1 / 8 of the diameter (D), and "10mm dep." indicates a position where the depth from the surface is 10mm.

[0071] In this way, within a unit area (1m²) below a certain constant... 2 The jet flow rate (L / m) 2 At a certain time (min), since the microparticle-sized droplet group evaporates before reaching the high temperature of the steel, in order to avoid this situation, the jet flow rate is increased and the jet of the droplet group is pulsed in a way that can obtain an appropriate heat transfer coefficient.

[0072] It should be noted that, depending on the location and shape of the steel, and if different spray flow rates are required at the same time, the spray control of each nozzle can be changed or different types of nozzles can be used.

[0073] Figure 7 Therefore, it is obtained through pulse jet. Figure 5 The result of the condition setting is achieved by varying the flow rate in continuous injection of (b).

[0074] Currently, the unit area (1m²) of droplet arrays capable of colliding with the high-temperature surface of steel is limited. 2 The minimum injection flow rate is 10 L / m³. 2•min., assuming that the entire group of droplets ejected from the nozzle contributes to cooling. In this case, if the initial 2min. is based on a unit area (1m²) 2 The injection flow rate is initially 40 L / min, then reduced to 10 L / min in the next stage. Simultaneously, a timer installed on the solenoid valve sets the pulse width to pulse interval ratio to 1:1 (duty cycle: 1 / 2), and the mixture is cooled for 1 minute. Then, the pulse width to pulse interval ratio is set to 1:4 (duty cycle: 1 / 5) to achieve the target injection flow rate.

[0075] That is, in the initial first step to maximize cooling performance, the flow rate needs to be the same as the total flow rate when continuously spraying at 35-40 L / min for 2 minutes, and the droplet group is a constant flow rate of 40 L / min in this example when continuously spraying for 2 minutes.

[0076] Next, in the second process after the first process, which reduces the cooling performance relative to the first process, the flow rate needs to be the same as the total flow rate when continuously spraying at 4-5 L / min for 1 minute. The droplet group of 10 L / min (equivalent to the size of the pulse) is set as a pulse, and pulsed for 1 minute with a pulse interval of 10 seconds and a pulse width of 10 seconds.

[0077] Furthermore, in the third process, where the cooling performance is relatively reduced compared to the second process, it is necessary to make the flow rate the same as the total flow rate when continuously spraying at 1.5 to 2 L / min for 30 minutes, set the pulse interval to 40 seconds or more, and pulse spray at 10 L / min (equivalent to the pulse size) for 30 minutes or more with a pulse width of 10 seconds.

[0078] The above-mentioned pulsed spraying can avoid the phenomenon that the droplet group evaporates and does not reach the high-temperature surface of the steel, and can properly cool the steel.

[0079] The jet flow rate per unit area becomes Figure 7 The flow rate was pre-calculated, and the flow rate was adjusted while monitoring actual temperature changes. Simultaneously, the droplet array was pulsed and sprayed to cool the steel. The resulting cooling test results are shown below. Figure 8 Achieving approximately the same temperature change as during oil quenching, appropriate cooling results were obtained through the spraying of droplet arrays. It should be noted that... Figure 8 In the diagram, "D / 4" indicates a position where the depth from the surface is 1 / 4 of the diameter (D), "D / 8" indicates a position where the depth from the surface is 1 / 8 of the diameter (D), and "10mm depth" indicates a position where the depth from the surface is 10mm.

[0080] As described above, by pre-calculating the target flow rate and adjusting the flow rate while monitoring actual temperature changes, it is possible to achieve the same cooling state as oil cooling through pulse injection. That is, in the example above, the cooling rate can be varied within a temperature range of approximately 500°C.

[0081] It should be noted that, in the above description, the pulse jetting of droplet groups was performed in order to make the cooling state the same as that of oil cooling. However, the present invention is not based solely on achieving this purpose. In order to obtain any cooling state, the pulse jetting of droplet groups can be performed by changing at least one of the pulse size, pulse width, and pulse interval over time.

[0082] In addition, in the aforementioned embodiment, the pulse size, i.e. the injection flow rate, is set to a minimum of zero. However, it is also possible to replace this by setting a non-zero certain flow rate as the minimum injection quantity for injection.

[0083] The present invention has been described above based on the above embodiments, but the scope of the present invention is not limited to the description of the above embodiments. As long as the scope of the present invention is not departed, appropriate changes can be made to the embodiments.

[0084] Industrial availability

[0085] According to the present invention, it is possible to cool the component to be cooled by pulse jetting of droplet groups to achieve the desired cooling state.

[0086] For example, in the quenching of steel, pulse width modulation (PWM) control can arbitrarily determine the pulse time and pulse interval during cooling, thereby determining the area per unit area (1m²) at a given time interval. 2 The jet flow rate can be controlled to reach a unit area (1m²), thereby controlling the jet flow rate. 2 The amount of liquid droplets on the high-temperature surface of steel can be measured, for example, by pulse-jet-based cooling or oil quenching, to obtain a cooling state in which the cooling rate varies during cooling.

[0087] The present invention has been described in detail with reference to specific embodiments, but those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the present invention.

[0088] This application is based on Japanese patent application (Taiwan Patent Application 2019-191869) filed on October 21, 2019, the contents of which are incorporated herein by reference. Explanation of reference numerals in the attached figures

[0089] 1. Cooling device

[0090] 2. Injector nozzle

[0091] 3 piping

[0092] 4. Injection Adjustment Section

[0093] 5. Control Department

[0094] 10 droplet groups

[0095] 100 steel

Claims

1. A method for cooling a component, comprising spraying an array of liquid droplets onto a heated component to cool it, characterized in that... The jet flow rate per unit area is calculated based on the temperature and the heat transfer coefficient during oil quenching, thus obtaining the time variation of the jet flow rate per unit area when cooling steel through the required continuous jetting. The jetting of the droplet group is pulsed and repeated, and at least one of the pulse size, pulse width, and pulse interval is varied over time to obtain the same jet flow rate in pulsed jetting as in continuous jetting.

2. The cooling method for the cooled component according to claim 1, characterized in that, Based on the changes, the cooling performance is adjusted according to the passage of time.

3. The cooling method for the cooled component according to claim 2, characterized in that, In adjusting the cooling performance, the unit area (m²) of the droplet group at regular intervals is determined. 2 () average jet flow rate.

4. The cooling method for the cooled component according to any one of claims 1 to 3, characterized in that, The size of the pulse is set to a value that allows the droplet array to reach a unit area (1m²) of the surface of the cooled component. 2 The jet flow rate is above 1000 rpm.

5. The cooling method for the cooled component according to claim 2 or 3, characterized in that, At least have: The process includes: an initial first step that maximizes the cooling performance; a second step that reduces the cooling performance relative to the first step; and a third step that reduces the cooling performance relative to the second step. In the first step, the pulse size and pulse width are set to the largest relative first pulse size and first pulse width. In the second step, the pulse size is set to the second pulse size, which is smaller than the first pulse size, and the pulse width is set to the second pulse width, which is smaller than the first pulse width. The pulse interval is set to the second pulse interval. In the third step, the pulse size is set to the third pulse size, which is less than the second pulse size, and the pulse width is set to the third pulse width, which is less than the second pulse width. The pulse interval is set to the third pulse interval, which is greater than the second pulse interval.

6. The cooling method for the cooled component according to any one of claims 1 to 5, characterized in that, The droplet group is sprayed using a single-fluid nozzle.

7. The cooling method for the cooled component according to any one of claims 1 to 6, characterized in that, The cooled component is made of steel with a thickness of 200 mm or more.

8. The cooling method for the cooled component according to any one of claims 1 to 7, characterized in that, Cooling based on the droplet array achieves the same cooling state as oil-based cooling.

9. A cooling device for a component being cooled, characterized in that, have: Multiple nozzles spray droplets onto a heated component to cool it. The injection adjustment unit adjusts the injection volume of the droplet group ejected from the injection nozzle; as well as The control unit controls the ejection of the droplet assembly from the nozzle. The control unit calculates the injection flow rate per unit area corresponding to the heat transfer coefficient during oil quenching based on temperature, and obtains the time variation of the injection flow rate per unit area when cooling the steel by the required continuous injection. The control unit controls the spraying of the droplet group in a pulsed manner, and repeatedly performs pulsed spraying, and controls the spraying of the droplet group in such a way that at least one of the pulse size, pulse width, and pulse interval changes over time, so as to obtain the same spray flow rate in pulse spraying as in continuous spraying.

10. The cooling device for the cooled component according to claim 9, characterized in that, The nozzles consist of several categories.

11. The cooling device for the cooled component according to claim 10, characterized in that, The injection adjustment unit can switch the type of the injection nozzle used.

12. The cooling device for the cooled component according to any one of claims 9 to 11, characterized in that, The control unit measures the temperature of the component being cooled and adjusts the jet flow rate of the droplet group based on the measurement results.

13. The cooling device for the cooled component according to any one of claims 9 to 12, characterized in that, The nozzle is a single-fluid nozzle.

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