JP7085946B2 - Plasma generator and heater warm-up method - Google Patents

Description

The present disclosure relates to a plasma generator that monitors the temperature of a plasma head.

Conventionally, various techniques for monitoring the temperature of a plasma head have been proposed for a plasma generator.

For example, in the atmospheric pressure plasma generator described in Patent Document 1 below, in the plasma head, a first inert gas is introduced from the upper end of the reaction vessel, and a high frequency voltage is applied to an antenna or an electrode arranged near the outside of the reaction vessel. By applying, the plasma generated in the reaction vessel is blown out as a primary plasma from the outlet, and this primary plasma collides with the mixed gas region formed by supplying the mixed gas into the mixed gas space, and the mixture is mixed. The gas turns into plasma in a snowfall phenomenon and is blown out from the mixed gas space as secondary plasma. At that time, the antenna or the electrode generates heat due to the flow of a high-frequency current, but the heat is dissipated through the non-conductive heat-dissipating member arranged in close contact with the antenna or the electrode to prevent the temperature from becoming high. The temperature of the non-conductive heat dissipation member is detected, and when the detected temperature exceeds the upper limit set temperature, the forced cooling means is operated to forcibly cool, and when the temperature falls below the lower limit set temperature, the forced cooling means is operated. Stop and stop forced cooling.

Japanese Unexamined Patent Publication No. 2008-47446

However, although the atmospheric pressure plasma generator described in Patent Document 1 can control the temperature of the plasma head during plasma generation, it is difficult to monitor the temperature rise process in the warm-up stage before plasma generation. rice field.

Therefore, the present disclosure has been made in view of the above-mentioned points, and is a plasma generator and a heater capable of monitoring the temperature rise process during warming of the heater that heats the plasma irradiated from the plasma head. The challenge is to provide a warm-up method.

This specification describes a plasma head, a heater that heats the plasma emitted from the plasma head, a storage device that stores reference data for determining the warm-up state of the heater, and a temperature for measuring the temperature of the heater. A sensor and a control device are provided, and the control device acquires the first temperature by measuring the temperature of the temperature sensor during the warm-up start process of starting the warm-up of the heater and the warm-up of the heater. A calculation process that calculates the lower limit temperature of the heater corresponding to the reference time point after a predetermined time has passed from the acquisition time of the first temperature based on the reference data of the storage device, and the temperature measurement of the temperature sensor at the reference time point. The second temperature acquisition process for acquiring two temperatures, and when the second temperature is equal to or higher than the lower limit temperature, the second temperature is regarded as the first temperature, and the calculation process and the second temperature acquisition process are repeated . The return process and the warm-up stop process for stopping the warm-up of the heater when the second temperature is less than the lower limit temperature are executed , and the reference data includes the temperature range for classifying the first temperature and the first temperature. A plasma generator , which is a data table associated with a temperature difference from to the lower limit temperature, is disclosed.

According to the present disclosure, the plasma generator can monitor the temperature rise process during warming up of the heater that heats the plasma emitted from the plasma head.

It is a perspective view which shows the plasma head of the atmospheric pressure plasma generator. It is a perspective view which shows the lower end part of the plasma head of the atmospheric pressure plasma generator. It is sectional drawing which shows the main part of the plasma head of the atmospheric pressure plasma generator. It is a block diagram which shows the control system of the atmospheric pressure plasma generator. It is a flowchart which shows the control program of a heater warm-up method. It is a figure which shows an example of the temperature rise process of a heater during a warm-up operation. It is a figure which shows an example of the correspondence relation between the 1st temperature and the lower limit temperature of a heater. It is a flowchart which shows the control program of the plasma head cooling method. It is a figure which shows the schematic structure of the atmospheric pressure plasma generator attached to the industrial robot.

Overall configuration The atmospheric pressure plasma generator is a device for generating plasma under atmospheric pressure. As shown in FIG. 9, the atmospheric pressure plasma generator 10 includes a plasma head 18, a control device 16, a power cable 140, a gas pipe 180, and the like. The atmospheric pressure plasma generator 10 transmits power from the control device 16 to the plasma head 18 via the power cable 140, supplies the processing gas or the like via the gas pipe 180, and irradiates the plasma gas from the plasma head 18. The plasma head 18 is attached to the tip of the robot arm 201 of the industrial robot 200. The power cable 140 and the gas pipe 180 are attached along the robot arm 201. The robot arm 201 is an articulated robot in which two arm portions 205 and 205 are connected in one direction. The industrial robot 200 drives the robot arm 201 to move the plasma head 18 and irradiates the work W supported by the work table 5 with plasma gas. The control device 16 includes a processing gas supply device 74 and a heating gas supply device 86. The processing gas supply device 74 supplies at least one of an inert gas such as nitrogen and an active gas such as oxygen as a processing gas. The heating gas supply device 86 supplies an active gas such as oxygen or an inert gas such as nitrogen. Further, the control device 16 includes a display device 115. The display device 115 includes a screen on which various information and the like are displayed.

Configuration of Plasma Head 18 As shown in FIG. 1, the plasma head 18 includes a plasma gas ejection device 12 and a heated gas ejection device 14. In the following description, the width direction of the plasma head 18 is referred to as the X direction, the depth direction of the plasma head 18 is referred to as the Y direction, and the direction orthogonal to the X direction and the Y direction, that is, the vertical direction is referred to as the Z direction.

The plasma gas ejection device 12 is composed of a housing 20, a cover 22, and a pair of electrodes (see FIGS. 3 and 4) 24 and 26. As shown in FIG. 3, the housing 20 includes a main housing 30, a heat sink 31, a ground plate 32, a lower housing 34, and a nozzle block 36. The main housing 30 is generally in the shape of a block, and a reaction chamber 38 is formed inside the main housing 30. Further, the main housing 30 is formed with a plurality of first gas flow paths (only one first gas flow path is shown in FIG. 3) 50 so as to extend in the vertical direction, and a plurality of first gas flow paths are formed. The first gas flow paths 50 are arranged at predetermined intervals in the X direction (in FIG. 3, the direction perpendicular to the paper surface). The upper end of each first gas flow path 50 is open to the reaction chamber 38, and the lower end is open to the bottom surface of the main housing 30.

The heat radiating plate 31 is arranged on one side surface of the main housing 30 in the Y direction. The heat sink 31 has a plurality of fins (not shown) and dissipates heat from the main housing 30. Further, the ground plate 32 functions as a lightning rod and is fixed to the lower surface of the main housing 30. The ground plate 32 is formed with a plurality of through holes 56 penetrating in the vertical direction corresponding to the plurality of first gas flow paths 50, and each through hole 56 is formed in the corresponding first gas flow path 50. It is connected.

The lower housing 34 has a block shape and is fixed to the lower surface of the ground plate 32. The lower housing 34 is formed so that a plurality of second gas flow paths 62 extend in the vertical direction corresponding to the plurality of through holes 56. The upper end of each second gas flow path 62 is connected to the corresponding through hole 56, and the lower end is open to the bottom surface of the lower housing 34.

As shown in FIG. 2, the nozzle block 36 is fixed to the lower surface of the lower housing 34, and the plurality of third gas flow paths 66 correspond to the plurality of second gas flow paths 62 of the lower housing 34. It is formed so as to extend in the vertical direction. The upper end of each third gas flow path 66 is connected to the corresponding second gas flow path 62, and the lower end is open to the bottom surface of the nozzle block 36.

Returning to FIG. 3, the cover 22 is generally box-shaped and is arranged on the lower surface of the ground plate 32 so as to cover the lower housing 34 and the nozzle block 36. A through hole 70 is formed on the lower surface of the cover 22. The through hole 70 is larger than the lower surface of the nozzle block 36, and the lower surface of the nozzle block 36 is located inside the through hole 70. Further, a through hole 72 is also formed on the side surface of the cover 22 on the heating gas ejection device 14 side so as to extend in the Y direction.

The pair of electrodes 24, 26 are arranged so as to face each other inside the reaction chamber 38 of the main housing 30. A processing gas supply device (see FIG. 4) 74 is connected to the reaction chamber 38 via the gas pipe 180 shown in FIG. As described above, the processing gas supply device 74 is a device that supplies at least one of an inert gas such as nitrogen and an active gas such as oxygen as a processing gas. As a result, the processing gas is supplied to the reaction chamber 38. The processing gas may be dry air.

Further, the heating gas ejection device 14 includes a protective cover 80, a gas pipe 82, a heater 83, and a connecting block 84. The protective cover 80 is arranged so as to cover the heat radiating plate 31 of the plasma gas ejection device 12. The gas pipe 82 is arranged so as to extend in the vertical direction inside the protective cover 80, and the gas pipe 82 is provided with a heating gas supply device (FIG. 9) via the gas pipe 180 shown in FIG. 4) 86 is connected. However, the gas pipe 180 is two different tubes, one is a tube connected to the reaction chamber 38 and the above processing gas supply device 74, and the other is a tube connected to the gas pipe 82 and the heating gas supply device 86. Consists of. As described above, the heating gas supply device 86 is a device that supplies an active gas such as oxygen or an inert gas such as nitrogen (hereinafter referred to as gas). As a result, gas is supplied from the heating gas supply device 86 into the gas pipe 82, and the gas flows downward. Further, for example, a coil-shaped heater 83 is suspended in the gas pipe 82. As a result, the gas supplied from the heating gas supply device 86 to the gas pipe 82 is heated. Further, as shown in FIG. 1, a generally cylindrical thermocouple cover 91 is attached to the gas pipe 82 along the longitudinal direction (that is, the vertical direction) of the gas pipe 82.

A thermocouple 92 is inserted in the thermocouple cover 91. The temperature measuring contact 92A of the thermocouple 92 is inserted into the gas pipe 82 from the lower end of the thermocouple cover 91 and is arranged below the heater 83. The arrow AR shown in FIG. 1 indicates the direction in which the gas flows in the gas pipe 82. Therefore, the thermocouple 92 measures the temperature of the gas flowing in the gas pipe 82 at a position close to the heater 83 from the downstream side of the gas in the gas pipe 82. In the atmospheric pressure plasma generator 10, the temperature measured by the thermocouple 92 is treated as the temperature of the heater 83 or the temperature of the plasma head 18.

Returning to FIG. 3, the connecting block 84 is connected to the lower end of the gas pipe 82 and fixed to the side surface of the cover 22 on the heating gas ejection device 14 side in the Y direction. The connecting block 84 is formed with a connecting passage 88 that is generally bent in an L shape. One end of the connecting passage 88 opens to the upper surface of the connecting block 84, and the other end of the connecting passage 88 is connected. It is open on the side surface of the block 84 on the plasma gas ejection device 12 side. Then, one end of the communication passage 88 communicates with the gas pipe 82, and the other end of the communication passage 88 communicates with the through hole 72 of the cover 22.
The plasma gas ejection device 12 does not have to be provided with the ground plate 32.

Control system of the atmospheric pressure plasma generator Next, the control system of the atmospheric pressure plasma generator 10 will be described. As shown in FIG. 9, the atmospheric pressure plasma generator 10 includes a control device 16. Further, as shown in FIG. 4, in addition to the above-mentioned processing gas supply device 74, heating gas supply device 86, and display device 115, the control device 16 includes a controller 100, a high frequency power supply 102, a drive circuit 105, and a flow rate controller. It includes 103, 104, a control circuit 106, a communication unit 107, a power supply device 108, an input device 116, and the like. The controller 100 is realized by a computer or the like equipped with a CPU 120, a ROM 122, a RAM 124, and the like. The controller 100 controls the plasma gas ejection device 12 and the heated gas ejection device 14 by controlling the high frequency power supply 102, the drive circuit 105, the flow rate controllers 103, 104, and the like. Further, the controller 100 is connected to the display device 115 via the control circuit 106. As a result, the image is displayed on the display device 115 according to the command of the controller 100. Further, the controller 100 is connected to the input device 116. The input device 116 is composed of operation buttons and the like, and outputs operation information by operating the operation buttons. As a result, the operation information obtained by operating the operation buttons is input to the controller 100. The communication unit 107 communicates with a communication device connected to a network (not shown). The form of communication is not particularly limited, and is, for example, LAN, serial communication, or the like.

The high-frequency power supply 102 generates high-frequency AC power to be supplied to the electrodes 24 and 26 from a commercial power source (not shown), and supplies the generated AC power to the electrodes 24 and 26.

The flow rate controller 103 is realized by, for example, a mass flow controller or the like. The flow rate controller 103 controls the flow rate of the processing gas supplied from the processing gas supply device 74 to the reaction chamber 38. Further, the flow rate controller 103 outputs the value of the flow rate of the supplied processing gas to the controller 100.

Like the flow controller 103, the flow controller 104 controls the flow rate of the gas supplied from the heating gas supply device 86 to the gas pipe 82. Further, the flow rate controller 103 outputs the flow rate value of the supplied gas to the controller 100.

A power supply device 108 and a thermocouple 92 attached near the lower end of the heater 83 are electrically connected to the drive circuit 105. The power supply device 108 supplies AC power generated from a commercial power source (not shown) to the heater 83. The drive circuit 105 heats the heater 83 and adjusts the temperature of the heater 83 by controlling the power supply device 108 based on the output value of the thermocouple 92 so as to reach the target temperature instructed by the controller 100. .. Further, the drive circuit 105 outputs the temperature corresponding to the output value of the thermocouple 92 to the controller 100.

Plasma processing by the atmospheric pressure plasma generator In the atmospheric pressure plasma generator 10, in the plasma gas ejection device 12, the processing gas is converted into plasma inside the reaction chamber 38 by the above-mentioned configuration, and the third gas flow path of the nozzle block 36 is formed. Plasma gas is ejected from the lower end of 66. Further, the gas heated by the heating gas ejection device 14 is supplied to the inside of the cover 22. Then, plasma gas is ejected from the through hole 70 of the cover 22 together with the heated gas, and the work W is plasma-treated.

Specifically, in the plasma gas ejection device 12, the processing gas is supplied to the reaction chamber 38 by the processing gas supply device 74. At that time, in the reaction chamber 38, electric power is supplied to the pair of electrodes 24 and 26, and a current flows between the pair of electrodes 24 and 26. As a result, an electric discharge is generated between the pair of electrodes 24 and 26, and the electric discharge turns the processing gas into plasma to become plasma gas. The plasma gas generated in the reaction chamber 38 flows downward in the first gas flow path 50 and flows into the second gas flow path 62 through the through hole 56. Then, the plasma gas flows downward in the second gas flow path 62 and the third gas flow path 66. As a result, plasma gas is ejected from the lower end of the third gas flow path 66 through the through hole 70 of the cover 22.

Further, in the heating gas ejection device 14, gas is supplied to the gas pipe 82 by the heating gas supply device 86, and the gas supplied to the gas pipe 82 is heated by the heater 83. As a result, the gas supplied to the gas pipe 82 is heated to 600 ° C to 800 ° C. The heated gas (hereinafter referred to as heating gas) flows into the inside of the cover 22 from the through hole 72 of the cover 22 through the communication passage 88 of the connecting block 84. Then, the heating gas that has flowed into the cover 22 is ejected from the through hole 70 of the cover 22. At this time, the plasma gas ejected from the lower end of the third gas flow path 66 of the nozzle block 36 is protected by the heating gas. As a result, the plasma gas surrounded by the heating gas is discharged from the plasma head 18, and the plasma treatment can be appropriately performed.

Specifically, at the time of plasma processing, the work W is placed at a predetermined distance from the through hole 70 for ejecting the plasma gas, and the plasma gas is ejected from the through hole 70 into the work W. That is, at the time of plasma processing, the plasma gas is ejected into the air, and the plasma gas ejected into the air is irradiated to the work W.

When the controller 100 receives the instruction to start plasma generation via the input device 116, the controller 100 starts plasma generation control. In the plasma generation control, the controller 100 starts the control of supplying a predetermined electric power to the electrodes 24 and 26 to the high frequency power supply 102, and supplies the processing gas and the gas to the flow rate controllers 103 and 104 at a predetermined gas flow rate, respectively. To start. Further, the controller 100 causes the drive circuit 105 to start controlling the heater 83 so as to reach a predetermined temperature.

Warm-up operation of the heater in the atmospheric pressure plasma generator As described above, the atmospheric pressure plasma generator 10 heats the gas supplied to the gas pipe 82 to 600 ° C. to 800 ° C. when plasma-treating the work W. It is heated by. Therefore, the heater 83 is warmed up at the time of starting the atmospheric pressure plasma generator 10. During the warm-up operation of the heater 83, for example, when the thermocouple 92 fails due to a short circuit or disconnection, the measured temperature of the thermocouple 92 is constant, for example, without always indicating the room temperature or rising from a predetermined temperature. Since the temperature is indicated, the temperature of the heater 83 cannot be accurately measured by the thermocouple 92. Therefore, the temperature of the heater 83 cannot be adjusted, and the heater 83 may break down. Therefore, the atmospheric pressure plasma generator 10 monitors the temperature rise process of the heater 83 during the warm-up operation of the heater 83. The details will be described below.

FIG. 5 is a flowchart showing a heater warm-up method 110 for monitoring the temperature rise process of the heater 83. The control program shown in the flowchart of FIG. 5 is stored in the ROM 122 of the controller 100, and when the user performs a predetermined operation on the input device 116 at the time of starting the atmospheric pressure plasma generator 10 or the like, the controller 100 It is executed by the CPU 120.

Hereinafter, each process shown in the flowchart of FIG. 5 will be described with reference to FIGS. 6 and 7 in addition to FIG. 4 described above. Incidentally, the curve L1 in FIG. 6 shows an example of the temperature change of the heater 83 during the warm-up operation. Further, the data table DT of FIG. 7 is stored in the ROM 122 of the controller 100.

When the heater warm-up method 110 is executed, first, the warm-up start process S110 is performed. In this process, the warm-up operation of the heater 83 is started by starting the power supply from the power supply device 108 to the heater 83.

Subsequently, the first temperature acquisition process S112 is performed. In this process, the thermocouple 92 acquires the temperature MT1 as the first temperature.

Subsequently, the calculation process S114 is performed. In this process, the lower limit temperature LM1 of the heater 83 is calculated. The lower limit temperature LM1 of the heater 83 is the temperature of the heater 83 whose temperature is rising due to the warm-up operation, and the DP (for example, 10 seconds) for the first predetermined time from the time when the temperature MT1 is acquired as the first temperature is It means the minimum temperature of the heater 83 that is assumed in consideration of the allowable fluctuation range of the power supply device 108 at the time when it has elapsed. In the following, the time point at which the first predetermined time DP has elapsed from the time point at which the first temperature is acquired may be referred to as a reference time point.

The lower limit temperature LM1 of the heater 83 is calculated from the first temperature and the data table DT.

According to the data table DT, for the first temperature of 0 ° C. or higher and lower than 400 ° C., the temperature obtained by adding 50 ° C. to the first temperature is calculated as the lower limit temperature of the heater 83. Hereinafter, as the lower limit temperature of the heater 83, the temperature obtained by adding 20 ° C. to the first temperature is calculated for the first temperature of 400 ° C. or higher and lower than 500 ° C., and the first temperature of 500 ° C. or higher and lower than 600 ° C. is calculated. The temperature obtained by adding 5 ° C. to the first temperature is calculated, and the temperature added by 3 ° C. to the first temperature is calculated for the first temperature of 600 ° C. or higher and lower than 650 ° C. Therefore, the data table DT has a temperature range for classifying the first temperature (in FIG. 7, 0 ° C. or higher and lower than 400 ° C., 400 ° C. or higher and lower than 500 ° C., 500 ° C. or higher and lower than 600 ° C., and 600 ° C. or higher and lower than 650 ° C.). , Is a data table associated with the temperature difference from the first temperature to the lower limit temperature (50 ° C, 20 ° C, 5 ° C, and 3 ° C in FIG. 7).

In this way, the lower limit temperature LM1 of the heater 83 is calculated based on the data stored in the data table DT. When the lower limit temperature LM1 of the heater 83 is calculated, it waits until the first predetermined time DP elapses from the time when the temperature MT1 is acquired as the first temperature, that is, until the reference time is reached (S116: NO). Then, when the first predetermined time DP elapses from the time when the temperature MT1 is acquired as the first temperature (S116: YES), that is, when the reference time is reached, the second temperature acquisition process S118 is performed. In this process, the thermocouple 92 acquires the temperature MT2 as the second temperature.

Subsequently, it is determined whether or not the temperature MT2 acquired as the second temperature is equal to or higher than the lower limit temperature LM1 (S120). Here, when the temperature MT2 acquired as the second temperature is less than the lower limit temperature LM1 (S120: NO), when the first predetermined time DP elapses from the time when the temperature MT1 is acquired as the first temperature. That is, it can be said that the temperature MT2 (that is, the temperature of the heater 83) acquired as the second temperature does not rise to the lower limit temperature LM1 when the reference time point is reached. Therefore, assuming that there is an abnormality, the warm-up stop process S122 is performed. In this process, the warm-up operation of the heater 83 is stopped by stopping the power supply from the power supply device 108 to the heater 83. Further, on the screen of the display device 115, for example, the entire area is displayed in red and a message indicating that the warm-up operation has been stopped is displayed. In addition, the message to the effect that the warm-up operation has been stopped is sent by the terminal of the administrator who manages the atmospheric pressure plasma generator 10 or the support desk operated by the supplier of the atmospheric pressure plasma generator 10 by the network communication of the communication unit 107. It is sent to the terminal of. After that, the heater warm-up method 110 ends.

On the other hand, when the temperature MT2 acquired as the second temperature is equal to or higher than the lower limit temperature LM1 (S120: YES), the deemed processing S124 is performed. In this process, the temperature MT2 acquired as the second temperature is treated as the first temperature instead of the above temperature MT1.

After that, each of the above processes S114, S116, S118, and S120 is repeated. As a result, in the above calculation process S114, the lower limit temperature LM2 of the heater 83 is calculated from the temperature MT2 treated as the first temperature and the data table DT. The lower limit temperature LM2 of the heater 83 calculated in this way is the same as the above lower limit temperature LM1. That is, the lower limit temperature LM2 of the heater 83 is the temperature of the heater 83 whose temperature is rising due to the warm-up operation, and the first predetermined time DP has elapsed from the time when the temperature MT2 treated as the first temperature is acquired. At the reference time point, it is the minimum temperature of the heater 83 assumed in consideration of the allowable fluctuation range of the power supply device 108.

Then, when the first predetermined time DP elapses from the time when the temperature MT2 treated as the first temperature is acquired (S116: YES), that is, when the reference time is reached, the above-mentioned second temperature acquisition process S118 is performed. The temperature MT3 is acquired as the second temperature.

When the temperature MT3 acquired as the second temperature is less than the lower limit temperature LM2 (S120: NO), it is considered that there is an abnormality and the warm-up operation of the heater 83 is stopped (S122). On the other hand, when the temperature MT3 acquired as the second temperature is equal to or higher than the lower limit temperature LM2 (S120: YES), the deemed processing S124 is performed again, and the temperature MT3 acquired as the second temperature is set to the temperature MT3. Instead of the above temperature MT2, it is treated as the first temperature (S124).

In the same manner thereafter, the lower limit temperature LM3 of the heater 83 is calculated from the temperature MT3 treated as the first temperature and the data table DT (S114), and further, from the time when the temperature MT3 treated as the first temperature is acquired. When the first predetermined time DP has elapsed (S116: YES), that is, when the reference time point has been reached, the temperature MT4 is acquired as the second temperature (S118). When the temperature MT4 acquired as the second temperature is less than the lower limit temperature LM3 (S120: NO), it is considered that there is an abnormality and the warm-up operation of the heater 83 is stopped (S122). On the other hand, when the temperature MT4 acquired as the second temperature is equal to or higher than the lower limit temperature LM3 (S120: YES), the temperature MT4 acquired as the second temperature is replaced with the above temperature MT3. It is treated as one temperature (S124).

In this way, as long as the second temperature is equal to or higher than the lower limit temperature calculated from the first temperature, the heater warm-up method 110 is continued.

From the above, the atmospheric pressure plasma generator 10 can monitor the temperature rise process of the heater 83 provided in the plasma head 18 during the warm-up by executing the heater warm-up method 110.

Even if the lower limit temperature LM1, LM2, LM3 of the heater 83 is calculated from an approximate formula showing the relationship with the elapsed time from the start time of power supply to the heater 83 (that is, the warm-up time of the heater 83). good. In FIG. 6, such an approximate expression is represented by a curve L2 shown by a two-dot chain line. The mathematical formula showing the curve L2 is stored in the ROM 122 of the controller 100.

In such a case, the lower limit temperature LM1, LM2, LM3 of the heater 83 is set at a reference time point in which the first predetermined time DP has elapsed from the time when the temperatures MT1, MT2, MT3 acquired or treated as the first temperature are acquired. Therefore, it is calculated by substituting the time point when the elapsed time is measured from the time when the power supply to the heater 83 is started to the formula (approximate formula) shown by the curve L2 in FIG.

Further, even if the heater 83 is not provided on the plasma head 18, it can be the target of the heater warm-up method 110 as long as it heats the plasma irradiated from the plasma head 18.

When the atmospheric pressure plasma generator 10 is stopped after the work W is plasma-processed by the atmospheric pressure plasma generator 10, the heater cooling operation controller 100 in the atmospheric pressure plasma generator is processed by the processing gas supply device 74. The plasma head 18 is cooled by continuing the gas supply and the gas supply by the heating gas supply device 86. After the plasma head 18 has cooled, there are cases where the user touches the plasma head 18 for maintenance. Therefore, the cooling of the plasma head 18 is continued on the assumption that the surface temperature of the plasma head 18 drops to, for example, around 40 ° C., but if the plasma head 18 is repeatedly cooled while measuring the temperature of the plasma head 18, further. It can be preferably performed. Therefore, the atmospheric pressure plasma generator 10 cools the plasma head 18 while measuring the temperature of the plasma head 18. The details will be described below.

FIG. 8 is a flowchart showing a plasma head cooling method 210 for cooling the plasma head 18 while measuring the temperature of the plasma head 18. The control program shown in the flowchart of FIG. 8 is stored in the ROM 122 of the controller 100, and is executed by the CPU 120 of the controller 100 when the plasma processing of the work W is being performed by the atmospheric pressure plasma generator 10. .. Therefore, when the plasma head cooling method 210 is executed, the processing gas is supplied by the processing gas supply device 74 and the gas is supplied by the heating gas supply device 86. Hereinafter, each process shown in the flowchart of FIG. 8 will be described.

The CPU 120 of the controller 100 uses the temperature of the heater 83 measured by the thermocouple 92 to perform each process shown in the flowchart of FIG. The temperature of the surface of the plasma head 18 while the work W is being plasma-processed varies depending on its position. However, the entire surface of the plasma head 18 tends to converge to the same temperature after a certain period of time has passed since the start of cooling. Therefore, in the plasma head cooling method 210 shown in the flowchart of FIG. 8, the temperature of the heater 83 measured by the thermocouple 92 is used as the temperature of the plasma head 18.

When the plasma head cooling method 210 is executed, it is determined whether or not the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 are stopped (S210). This determination is made based on a signal from the high frequency power supply 102, a signal from the drive circuit 105, and the like. Here, when the discharge between the pair of electrodes 24 and 26 or the heating of the heater 83 is not stopped (S210: NO), the plasma head cooling method 210 ends.

On the other hand, when the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 are stopped (S210: YES), the temperature of the heater 83 measured by the thermocouple 92 is below the predetermined temperature. It is determined whether or not there is (S212). Here, the predetermined temperature means a temperature (for example, a temperature near 40 ° C.) that does not hinder the user from touching the surface of the plasma head 18. Here, when the temperature of the heater 83 measured by the thermocouple 92 is equal to or lower than the predetermined temperature (S212: YES), the plasma head cooling method 210 ends.

On the other hand, when the temperature of the heater 83 measured by the thermocouple 92 is higher than the predetermined temperature (S).
In 212: NO), the cooling process S214 is performed. In this treatment, the supply of the processing gas by the processing gas supply device 74 and the supply of the gas by the heating gas supply device 86 are continued.

Subsequently, the first notification process S216 is performed. In this process, a message indicating that the plasma head 18 is being cooled is displayed on the screen of the display device 115. Further, the message that the plasma head 18 is being cooled is operated by the terminal of the administrator who manages the atmospheric pressure plasma generator 10 or the supplier of the atmospheric pressure plasma generator 10 by the network communication of the communication unit 107. It is sent to the terminal of the support desk.

After that, it is determined whether or not the supply of the processing gas by the processing gas supply device 74 or the supply of the gas by the heating gas supply device 86 has stopped abnormally. This determination is made based on the signals from the flow rate controllers 103 and 104 and the like. Here, when the supply of the processing gas by the processing gas supply device 74 or the gas supply by the heating gas supply device 86 is abnormally stopped (S218: YES), the second notification process S220 is performed.

In the second notification process S220, a message indicating that the cooling of the plasma head 18 is abnormal due to the abnormality of the gas supply is displayed on the screen of the display device 115. Further, a message indicating that the cooling of the plasma head 18 is abnormal due to an abnormality in the gas supply is sent to the terminal of the administrator who manages the atmospheric pressure plasma generator 10 or the atmospheric pressure plasma generator 10 by the network communication of the communication unit 107. It is sent to the terminal of the support desk operated by the supplier of. After that, the plasma head cooling method 210 ends.

On the other hand, when the supply of the processing gas by the processing gas supply device 74 and the gas supply by the heating gas supply device 86 are not abnormally stopped (S218: NO), the thermocouple 92 shows an abnormality such as disconnection. It is determined whether or not the gas is present (S222). This determination is made based on the output voltage of the thermocouple 92 and the like. Here, when the thermocouple 92 indicates an abnormality such as disconnection (S222: YES), the third notification process S224 is performed.

In the third notification process S224, a message indicating that the cooling of the plasma head 18 is abnormal due to the abnormality of the thermocouple 92 is displayed on the screen of the display device 115. Further, a message indicating that the cooling of the plasma head 18 is abnormal due to the abnormality of the thermocouple 92 is sent to the terminal of the administrator who manages the atmospheric pressure plasma generator 10 or the atmospheric pressure plasma generator by the network communication of the communication unit 107. It is transmitted to the terminal of the support desk operated by 10 suppliers. After that, the plasma head cooling method 210 ends.

On the other hand, when the thermocouple 92 does not show an abnormality such as disconnection (S222: NO), the second predetermined time after the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 are stopped. Is determined (S226). This determination is made based on the elapsed time measured by triggering the reception of a signal from the high frequency power supply 102, a signal from the drive circuit 105, and the like. The second predetermined time is required for the entire surface of the plasma head 18 to be cooled to a temperature at which the user can touch the surface of the plasma head 18 without hindrance (for example, a temperature near 40 ° C.). It refers to time (for example, 20 minutes).

Here, when the second predetermined time has elapsed (S226: YES) after the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 are stopped, the fourth notification process S228 is performed. In this process, a message indicating that the cooling of the plasma head 18 is abnormal is displayed on the screen of the display device 115. Further, a message indicating that the cooling of the plasma head 18 is abnormal is operated by the terminal of the administrator who manages the atmospheric pressure plasma generator 10 or the supplier of the atmospheric pressure plasma generator 10 by the network communication of the communication unit 107. It is sent to the terminal of the support desk. In those messages, the surface temperature of the plasma head 18 (to be exact, the heater) even after the second predetermined time has elapsed since the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 were stopped. It is added that the temperature of 83) does not fall below the predetermined temperature. After that, the plasma head cooling method 210 ends.

On the other hand, when the second predetermined time has not elapsed since the discharge between the pair of electrodes 24 and 26 and the heating of the heater 83 are stopped (S226: NO), the determination process of S212 described above is performed. return.

After that, as described above, when the temperature of the heater 83 measured by the thermocouple 92 is higher than the predetermined temperature (S212: NO), the processing gas supply device 74 supplies the processing gas and the heating gas supply device. When the gas supply by the 86 is continued (S214) and the temperature of the heater 83 measured by the thermocouple 92 is equal to or lower than the predetermined temperature (S212: YES), the plasma head cooling method 210 ends.

In this way, the plasma head cooling method 210 is based on the temperature of the heater 83 (the temperature measured by the thermocouple 92) used as the temperature of the plasma head 18, even if the user touches the surface of the plasma head 18. It is assumed that the surface temperature of the plasma head 18 has dropped to a temperature that does not hinder (for example, a temperature near 40 ° C.), and the cooling of the plasma head 18 is terminated.

From the above, the atmospheric pressure plasma generator 10 can appropriately cool the plasma head 18 with improved maintainability by executing the plasma head cooling method 210.

The present disclosure is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.
For example, the atmospheric pressure plasma generator 10 may be provided with another sensor capable of measuring the temperature of the heater 83 or the temperature of the gas flowing in the gas tube 82, for example, a thermistor or an infrared sensor, instead of the thermocouple 92. good.

Further, the atmospheric pressure plasma generator 10 may include a heater heated by a high temperature fluid such as a liquid or a gas instead of the heater 83 heated by the power supply device 108. In such a case, the temperature of the heater is adjusted by controlling the temperature and flow rate of the high temperature fluid.

Further, when the plasma head cooling method 210 is completed, the supply of the processing gas by the processing gas supply device 74 and the supply of the gas by the heating gas supply device 86 may or may not be continued.

Further, the plasma head cooling method 210 may be executed in a state where the temperature measuring contact 92A of the thermocouple 92 is embedded in the main housing 30 of the plasma head 18, for example. In such a case, the plasma head cooling method 210 can be applied to a case where the heating gas ejection device 14 including the heater 83 is not equipped in the plasma head 18.

Incidentally, in the present embodiment, the atmospheric pressure plasma generator 10 is an example of the plasma generator. The heating gas supply device 86 is an example of a gas supply device. The thermocouple 92 is an example of a temperature sensor. ROM 122 is an example of a storage device. The data table DT and the approximate expression shown by the curve L2 are examples of reference data. The first predetermined time DP is an example of a predetermined time. The temperatures MT1, MT2, and MT3 are examples of the first temperature. The temperatures MT2, MT3, and MT4 are examples of the second temperature. The warm-up start process S110 is an example of the warm-up start process. The first temperature acquisition process S112 is an example of the first temperature acquisition process. The calculation process S114 is an example of the calculation process. The second temperature acquisition process S118 is an example of the second temperature acquisition process. The warm-up stop process S122 is an example of the warm-up stop process. The deemed process S124 is an example of a repeat process and a repeat process.

10 Atmospheric pressure plasma generator 16 Control device 18 Plasma head 83 Heater 86 Heating gas supply device 92 Thermocouple 108 Power supply device 110 Heater warm-up method 122 ROM
DT reference data DP predetermined time L2 curve MT1 temperature MT2 temperature MT3 temperature LM1 lower limit temperature LM2 lower limit temperature LM3 lower limit temperature S110 warm-up start process S112 first temperature acquisition process S114 calculation process S118 second temperature acquisition process S122 warm-up stop process S124 Return processing

Claims (5)

With the plasma head
A heater that heats the plasma emitted from the plasma head, and
A storage device in which reference data for determining the warm-up state of the heater is stored, and
A temperature sensor that measures the temperature of the heater and
Equipped with a control device,
The control device is
The warm-up start process for starting the warm-up of the heater and the warm-up start process
During the warm-up of the heater, the first temperature acquisition process for acquiring the first temperature by measuring the temperature of the temperature sensor, and the first temperature acquisition process.
A calculation process for calculating the lower limit temperature of the heater corresponding to a reference time point in which a predetermined time has elapsed from the acquisition time point of the first temperature based on the reference data of the storage device.
At the reference time point, the second temperature acquisition process for acquiring the second temperature by measuring the temperature of the temperature sensor, and the second temperature acquisition process.
When the second temperature is equal to or higher than the lower limit temperature, the second temperature is regarded as the first temperature, and the calculation process and the second temperature acquisition process are repeated.
When the second temperature is less than the lower limit temperature, the warm-up stop process for stopping the warm-up of the heater is executed.
The reference data is a plasma generator which is a data table in which a temperature range for classifying the first temperature and a temperature difference from the first temperature to the lower limit temperature are associated with each other. The plasma generator according to claim 1 , wherein the heater is provided on the plasma head. A power supply device for supplying electric power to the heater is provided.
The control device is
By starting the power supply by the power supply device, the warm-up start process is executed.
The plasma generator according to claim 1 or 2 , wherein the warm-up stop process is executed by stopping the power supply by the power supply device. A gas supply device for supplying gas to the plasma head is provided.
The plasma generator according to any one of claims 1 to 3 , wherein the temperature sensor is a thermocouple provided at a position close to the heater on the downstream side of the gas. It is a heater warming method of a plasma generator equipped with a heater for heating plasma emitted from a plasma head.
The warm-up start process for starting the warm-up of the heater and
During the warm-up of the heater, the first temperature acquisition step of acquiring the first temperature of the heater and the first temperature acquisition step.
A calculation step of calculating the lower limit temperature of the heater corresponding to a reference time point in which a predetermined time has elapsed from the acquisition time point of the first temperature based on the reference data, and a calculation step.
In the second temperature acquisition step of acquiring the second temperature of the heater at the reference time point,
When the second temperature is equal to or higher than the lower limit temperature, the second temperature is regarded as the first temperature, and the calculation step and the second temperature acquisition step are repeated.
A warm-up stop step of stopping the warm-up of the heater when the second temperature is less than the lower limit temperature is provided.
The reference data is a heater warm-up method, which is a data table in which a temperature range for classifying the first temperature and a temperature difference from the first temperature to the lower limit temperature are associated with each other.

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