JP5065078B2 - Dry ice snow cleaning apparatus and method - Google Patents

Description

  The present invention relates to a dry ice snow cleaning apparatus and method capable of performing pulse injection control of dry ice snow and reducing the consumption of carbon dioxide gas.

Conventionally, fine dry ice is produced by adiabatic expansion of liquefied carbon dioxide gas by a throttle mechanism such as an orifice or a needle valve, and the gas is injected at a point of use while condensing the dry ice by flowing through a capillary called a capillary. The object to be cleaned is sprayed together with the object to be cleaned. Such a dry ice snow cleaning method is expected to be applied in the electronics field because high-purity liquefied carbon dioxide gas is used as a raw material gas.
JP 2001-259555 A JP 2003-145429 A

  In such a dry ice / snow cleaning method, in order to obtain the dry ice particle size and density necessary to remove strongly adhered foreign matter, generally, liquefied carbon dioxide gas is circulated in a narrow tube called a capillary to dry ice. Getting snow is done. When dry ice snow is generated in this way, there is a problem that the inside of the capillary is excessively cooled and a flow path blocking phenomenon occurs, and stable dry ice snow cannot be jetted. Therefore, it is possible to stabilize the dry ice snow injection by preventing the clogging due to excessive cooling by flowing dry ice snow through the inner tube with a double tube structure and flowing heated injection gas through the outer tube. (Patent Documents 1 and 2 above).

  However, in the double pipe structure as described above, since the injection gas flowing through the outer pipe takes away cold heat, cooling of the capillary at the initial start-up is hindered, and after the liquefied carbon dioxide valve is opened, the nozzle is dried from the nozzle at the point of use. There was a time lag before the ice snow was jetted. If there is such a time lag, pulse injection control that repeats injection cleaning for a relatively short time of about several seconds cannot be performed, and the loss time of the entire cleaning process becomes longer, resulting in longer cleaning time and liquefaction. There is a problem that it leads to an increase in the consumption of carbon dioxide gas.

  In order to shorten the time lag as described above, it is conceivable to increase the flow rate of carbon dioxide gas, for example, by increasing the orifice diameter. However, in this case, the consumption of carbon dioxide gas is further increased and excess carbon dioxide is increased. The flow of gas leads to a decrease in the density of dry ice snow, and a desired cleaning effect cannot be obtained. In addition, another problem arises that the object to be cleaned is excessively cooled to cause dew condensation.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dry ice snow cleaning apparatus and method that can perform pulse injection control of dry ice snow and reduce the consumption of carbon dioxide gas.

In order to achieve the above object, the dry ice snow cleaning apparatus of the present invention performs cleaning by injecting dry ice snow formed by adiabatic expansion of pressurized liquefied carbon dioxide gas from an injection nozzle onto an object to be cleaned. A device comprising: a supply valve that opens and closes the supply of pressurized liquefied carbon dioxide; a throttle that adiabatically expands the liquefied carbon dioxide supplied from the supply valve; and a flow pipe that extends from the throttle to the injection nozzle. The gist is that the internal volume of the flow path from the valve seat to the throttle portion of the supply valve is set to 0.58 cm ³ or less.

In order to achieve the above object, the dry ice snow cleaning method of the present invention performs cleaning by injecting dry ice snow formed by adiabatic expansion of pressurized liquefied carbon dioxide gas from an injection nozzle onto an object to be cleaned. The liquefied carbon dioxide gas supplied from a supply valve that opens and closes the supply of pressurized liquefied carbon dioxide gas is adiabatically expanded at the throttle portion, and is circulated through the flow pipe extending from the throttle portion to the injection nozzle. The gist is that the internal volume of the flow path from the valve seat to the throttle portion of the supply valve is 0.58 cm ³ or less when spraying more.

That is, according to the present invention, the internal volume of the flow path from the valve seat of the supply valve to the throttle portion is 0.58 cm ³ or less, so that the residual gas in the flow path from the valve seat of the supply valve to the throttle portion is reduced. The capacity is reduced accordingly, and the time from when the supply valve is opened until the remaining gas is exhausted is shortened. For this reason, the time lag from when the supply valve is opened until dry ice snow starts to be injected from the injection nozzle is greatly reduced. During dry ice snow injection, the flow from the valve seat to the throttle is filled with liquefied carbon dioxide, so the volume of the flow path is small, so the supply valve is closed and the dry ice snow is discharged from the injection nozzle. The time until injection stops is also shortened. In this manner, the injection is started and stopped in response to the opening and closing of the supply valve, thereby enabling the dry ice snow pulse injection control. In addition, since pulse injection control is possible, it becomes possible to inject and clean dry ice snow as much as necessary to the required parts to be cleaned, greatly reducing unnecessary injection of dry ice snow. This saves carbon dioxide consumption.

  In the present invention, when the time from when the supply valve is closed to when no dry ice snow is injected from the injection nozzle is within 1 second, the injection starts in response to the opening and closing of the supply valve. The dry ice snow pulse injection control becomes possible.

In the present invention, when set to be the opening area of the throttle portion and 0.007 mm ² or more 0.032 mm ² within the flow rate of the carbon dioxide gas is optimized, the consumption of carbon dioxide does not increase unnecessarily Also, dry ice snow can maintain the proper density and the necessary cleaning effect is obtained, and troubles such as the occurrence of condensation due to the object to be cleaned being cooled too much do not occur.

  In the present invention, when the supply pressure of liquefied carbon dioxide gas is set to be within 7 MPa ± 1 MPa, the flow rate of carbon dioxide gas is optimized, the consumption of carbon dioxide gas does not increase unnecessarily, and dry ice snow is also appropriate The density can be maintained and a necessary cleaning effect can be obtained, and troubles such as dew condensation due to excessive cooling of the object to be cleaned do not occur.

  In the present invention, when the injection gas supply pipe for supplying the injection gas in the vicinity of the injection port of the injection nozzle exists in a state of being thermally isolated from the flow pipe, the conventional double pipe structure is used. Thus, since the cooling of the flow pipe is not hindered at the initial stage of startup, the time lag between the opening of the valve and the injection of dry ice snow is greatly reduced. Further, excessive cooling of the flow pipe is effectively prevented, and the spray of dry ice snow is stabilized.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 1 is a diagram showing an embodiment of a dry ice snow cleaning apparatus to which the present invention is applied.

  This dry ice snow cleaning apparatus is an apparatus for cleaning by spraying dry ice snow formed by adiabatic expansion of pressurized liquefied carbon dioxide gas from an injection nozzle 1 onto an object to be cleaned (not shown). .

  More specifically, a carbon dioxide gas supply valve 8 as a supply valve for opening and closing the supply of pressurized liquefied carbon dioxide gas, and an orifice 3 as a throttle part for adiabatic expansion of the liquefied carbon dioxide gas supplied from the carbon dioxide gas supply valve 8; A flow pipe 2 extending from the orifice 3 to the injection nozzle 1 is provided.

  Liquefied carbon dioxide gas from a supply source such as a liquefied carbon dioxide gas cylinder is supplied by opening a carbon dioxide gas supply valve 8 provided in the supply path 6 and guided to the orifice 3. Once formed, it is introduced into the injection nozzle 1 through the elongated flow pipe 2 and injected from the tip of the injection nozzle 1. The supply path 6 is provided with a carbon dioxide gas supply valve 8 and a pressure gauge 9 for detecting the supply pressure of the liquefied carbon dioxide gas. The supply of the liquefied carbon dioxide gas is turned on and off by opening and closing the carbon dioxide gas supply valve 8. The supply pressure of the liquefied carbon dioxide gas is adjusted to a desired pressure by adjusting the temperature with a heater provided in a cylinder (not shown).

The internal volume of the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice 3 is set to be 0.58 cm ³ or less. Thereby, the volume of the residual gas in the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice 3 is reduced accordingly, and the time from when the carbon dioxide gas supply valve 8 is opened until the residual gas is exhausted is shortened. The For this reason, the time lag from when the carbon dioxide gas supply valve 8 is opened to when the dry ice snow starts to be injected from the injection nozzle 1 is greatly reduced. In addition, during the dry ice snow injection, the flow path from the valve seat to the orifice 3 is filled with liquefied carbon dioxide gas, so the volume of the flow path is small, and the carbon dioxide gas supply valve 8 is closed before the injection nozzle 1 The time until the dry ice snow injection stops is also shortened.

As described above, the inner volume of the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice 3 is preferably 0.58 cm ³ or less, more preferably 0.38 cm ³ or less, and 26cm ³ or less, or more preferably equal to 0.063Cm ³ or less.

  The supply pressure of the liquefied carbon dioxide gas is preferably set to be within 7 MPa ± 1 MPa. By doing so, the flow rate of carbon dioxide gas is optimized, the consumption amount of carbon dioxide gas is not increased unnecessarily, the dry ice snow can maintain the proper density, and the necessary cleaning effect can be obtained, and the object to be cleaned is Troubles such as condensation that occur due to excessive cooling will not occur.

The orifice 3 is preferably set so that the opening area and 0.007 mm ² or more 0.032 mm ² within. For example, in the case of an orifice having a circular opening, the diameter is 0.1 to 0.2 mm. By doing so, the flow rate of carbon dioxide gas is optimized, the consumption amount of carbon dioxide gas is not increased unnecessarily, the dry ice snow can maintain the proper density, and the necessary cleaning effect can be obtained, and the object to be cleaned is Troubles such as condensation that occur due to excessive cooling will not occur.

  The thickness of the orifice 3 was set to be within 0.5 mm ± 0.3 mm in this example. For example, a needle valve can be applied as long as the orifice 3 functions as a throttle portion that can adiabatically expand the supplied liquefied carbon dioxide gas.

  The dry ice snow generated by adiabatic expansion at the orifice 3 is connected between the orifice 3 and the injection nozzle 1 by a flow pipe 2 which is an elongated pipe, and the dry ice is condensed while flowing through the flow pipe 2. And is ejected from the ejection nozzle 1.

  The flow pipe 2 is preferably set so that the inner diameter of the flow pipe 2 is not less than φ0.25 mm and not more than φ1.5 mm. By setting the inner diameter of the flow pipe 2 within the above range, excessive cooling of the flow pipe is effectively prevented, and the injection of dry ice snow is also stabilized. The length of the flow pipe 2 is not particularly limited, but can be about 0.5 to 5 m, about 0.6 to 3 m, or about 0.6 to 2.5 m. .

  For example, a flexible tube formed of a fluororesin or the like is used as the flow pipe 2. In this example, the heat pipe 7 is wrapped in a heat insulating material 7 to be insulated from the outside. Further, the injection gas supply pipe 4 is not arranged in parallel with the flow pipe 2 as in the conventional double pipe structure, but is arranged separately from the flow pipe 2 via a heat insulating material 7. Thereby, the injection gas supply pipe 4 that supplies the injection gas in the vicinity of the injection port of the injection nozzle 1 is present in a state of being thermally isolated from the flow pipe 2. By doing in this way, the cooling in the distribution pipe 2 at the initial stage of startup can be made smoother and the injection waiting time can be shortened.

  In this example, the front end of the flow pipe 2 extends to the vicinity of the front end opening in the internal passage of the injection nozzle 1, and the front end of the injection gas supply pipe 4 communicates with a branch portion provided in the injection nozzle 1. .

  The injection gas supply pipe 4 is provided with a pressure gauge 13 for detecting supply pressure. The injection gas supply pipe 4 is provided with an injection gas supply valve 14 for turning on / off the supply of the injection gas, and a pressure adjusting valve 12 capable of adjusting the supply pressure of the injection gas. The supply pressure of the injection gas is adjusted by the pressure adjusting valve 12.

  Further, the injection gas supply pipe 4 is provided with a primary heater 15 for heating the injection gas, a temperature controller 17 for adjusting the heating temperature of the primary heater 15, and a thermometer 16 for detecting the heating temperature. Further, a secondary heater 18 is provided in the injection gas supply pipe 4 on the downstream side of the primary heater 15. Furthermore, a temperature controller 20 for adjusting the heating temperature of the secondary heater 18 and a thermometer 19 for detecting the heating temperature are provided.

  The secondary heater 18 is disposed on the downstream side of the primary heater 15 so as to be elongated around the vicinity of the communicating portion with the injection nozzle 1 and around the injection gas supply pipe 4. By doing so, the injection gas is introduced into the injection nozzle 1 while maintaining a uniform and constant temperature without being cooled. Therefore, the temperature of the spray nozzle 1 can be kept uniform and constant, and the spray state of dry ice snow can be further stabilized. As the injection gas, for example, high-pressure nitrogen gas can be used.

  The primary heater 15 and the secondary heater 18 are used when the spray nozzle 1 is excessively cooled, and may not be used when the spray nozzle 1 is not cooled excessively. Depending on the cooling state of the injection nozzle 1, only the primary heater 15 or the secondary heater 18 can be used, or the primary heater 15 and the secondary heater 18 can be used together.

  As mentioned above, according to this embodiment, there exist the following effects.

That is, by setting the internal volume of the flow path from the valve seat of the carbon dioxide supply valve 8 to the orifice 3 to 0.58 cm ³ or less, the remaining volume in the flow path from the valve seat of the carbon dioxide supply valve 8 to the orifice 3 is maintained. The gas capacity is reduced accordingly, and the time from when the carbon dioxide supply valve 8 is opened until the remaining gas is exhausted is shortened. For this reason, the time lag from when the carbon dioxide gas supply valve 8 is opened to when the dry ice snow starts to be injected from the injection nozzle 1 is greatly reduced. In addition, during the dry ice snow injection, the flow path from the valve seat to the orifice 3 is filled with liquefied carbon dioxide gas, so the volume of the flow path is small, and the carbon dioxide gas supply valve 8 is closed before the injection nozzle 1 The time until the dry ice snow injection stops is also shortened. In this way, the injection is started and stopped in response to the opening and closing of the carbon dioxide supply valve 8, and pulse injection control of dry ice snow becomes possible. In addition, since pulse injection control is possible, it becomes possible to inject and clean dry ice snow as much as necessary to the required parts to be cleaned, greatly reducing unnecessary injection of dry ice snow. This saves carbon dioxide consumption.

  In addition, since the inner diameter of the flow pipe 2 is set to be 0.25 mm to 1.5 mm, excessive cooling of the flow pipe 2 is effectively prevented by setting the inner diameter of the flow pipe 2 within the above range. Dry ice snow injection is also stabilized.

Further, because the set so that the opening area of the orifice 3 and 0.007 mm ² or more 0.032 mm ² within the flow rate of the carbon dioxide gas is optimized, the consumption of carbon dioxide does not increase unnecessarily, dry ice snow An appropriate density can be maintained and a necessary cleaning effect can be obtained, and troubles such as dew condensation due to excessive cooling of an object to be cleaned do not occur.

  In addition, since the supply pressure of liquefied carbon dioxide gas is set to be within 7 MPa ± 1 MPa, the flow rate of carbon dioxide gas is optimized, the consumption of carbon dioxide gas is not increased unnecessarily, and dry ice snow can maintain the proper density. The necessary cleaning effect can be obtained, and troubles such as dew condensation due to excessive cooling of the object to be cleaned will not occur.

  Further, since the injection gas supply pipe 4 for supplying the injection gas in the vicinity of the injection port of the injection nozzle 1 exists in a state of being thermally isolated from the flow pipe 2, it has a conventional double pipe structure. In addition, since the cooling of the flow pipe 2 is not hindered at the beginning of startup, the time lag from when the carbon dioxide gas supply valve 8 is opened to when dry ice snow is injected is greatly reduced. In addition, excessive cooling of the flow pipe 2 is effectively prevented, and the injection of dry ice snow is stabilized.

  FIG. 2 is a diagram illustrating an example of a time control sequence of the carbon dioxide supply valve 8 and the injection gas supply valve 14 and an injection state of the dry ice snow when the dry ice snow cleaning method of the present invention is performed.

  In this example, first, the injection gas supply valve 14 is turned on (opened; hereinafter the same), and then the carbon dioxide gas supply valve 8 is turned on after a predetermined preparation time. Prior to turning on the carbon dioxide supply valve 8, the injection gas supply valve 14 is turned on to prevent condensation on the injection nozzle 1.

After the carbon dioxide supply valve 8 is turned on, the injection of dry ice snow from the injection nozzle 1 starts after a predetermined snow start time, and the carbon dioxide supply valve 8 is turned off (closed; the same applies hereinafter) after a predetermined injection time. ). In this example, the snow activation time is about 0.5 seconds or less. Then, the on-time T _b of the carbon dioxide supply valve 8 is in this example can be set within about 1 second. The time from when the carbon dioxide gas supply valve 8 is turned off to when the injection of dry ice snow from the injection nozzle 1 is not recognized (snow remaining time in the drawing) can be made within 1 second. In this example, it is within 0.5 seconds. By doing so, the injection is started and stopped in response to the opening and closing of the carbon dioxide gas supply valve 8, and the pulse injection control of the dry ice snow becomes possible.

In this example, the sprayed gas supply valve 14 is kept on for about 1 second in order to blow off the sprayed dry ice snow, prevent cooling of the object to be cleaned, and prevent condensation of the spray nozzle 1. Do a gas blow. Thereafter, the injection gas supply valve 14 is turned off, thereby completing one cleaning sequence. Furthermore, in this example, since the snow remaining time described above is short, the interval T _i from when the carbon dioxide supply valve 8 is turned off to when the carbon dioxide supply valve 8 is turned on next can be shortened. In this example, it can be within 3 seconds.

The inner diameter of the flow pipe 2 is set to φ0.75 mm, the length of the flow pipe 2 is set to 1.8 m, and the internal volume of the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice 3 is changed to thereby dry ice snow. The collision pressure of dry ice snow was evaluated as an indicator of the consumption of liquefied carbon dioxide, the responsiveness of dry ice snow injection to opening and closing of the carbon dioxide supply valve 8, and the cleanability. The inner diameter of the orifice 3 was 0.16 mm, the opening time of the carbon dioxide gas supply valve 8 was 0.3 seconds, and the interval _Ti was 3 seconds. The results are shown in Table 1 below.

The responsiveness was evaluated as ○ when the remaining snow time from the closing of the carbon dioxide supply valve 8 until the injection of dry ice snow was not recognized was within 1.0 seconds. The collision pressure was measured with a prescale manufactured by Fuji Film Co., Ltd., and the collision pressure of 0.5 MPa or more was evaluated as ◯.

As can be seen from Table 1 above, it can be seen that good results are obtained when the internal volume of the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice 3 is within 0.58 cm ³ .

The inner diameter of the flow pipe 2 is set to φ0.75 mm, the length of the flow pipe 2 is set to 1.8 m, and the internal volume of the flow path from the valve seat of the carbon dioxide supply valve 8 to the orifice ³ is set to 0.063 cm ^3. , By changing the inner diameter of the orifice 3 to inject dry ice snow, the consumption of liquefied carbon dioxide gas, the response of the dry ice snow injection to the carbon dioxide gas supply valve 8 opening and closing, and the impact pressure of the dry ice snow as an index of cleanability evaluated. The opening time of the carbon dioxide supply valve 8 was 0.3 seconds, and the interval _Ti was 3 seconds. The results are shown in Table 2 below.

As can be seen from Table 2 above, the inner diameter of the orifice 3 is 0.12 mm (opening area 0.0113 mm ² ), 0.14 mm (opening area 0.0154 mm ² ), 0.16 mm (opening area 0.02 mm ² ),. It can be seen that good results are obtained in any case of 18 mm (opening area 0.0254 mm ² ).

The inner diameter of the flow pipe 2 is set to φ0.75 mm, the length of the flow pipe 2 is set to 1.8 m, the inner volume of the flow path from the valve seat of the carbon dioxide gas supply valve 8 to the orifice is set to 0.063 cm ³ , Dry ice snow is jetted by changing the opening time of the carbon dioxide supply valve 8, and the consumption of liquefied carbon dioxide, the response of the dry ice snow injection to the opening and closing of the carbon dioxide supply valve 8, and the dry ice snow as an index of cleanability The impact pressure was evaluated. Orifice 3 inside diameter was 3 seconds 0.16 mm, the interval _{T i.} The results are shown in Table 3 below.

  As can be seen from Table 3 above, good results were obtained when the carbon dioxide gas supply valve 8 was opened for 0.1 seconds, 0.3 seconds, 0.5 seconds, and 1.0 seconds. Recognize.

It is a schematic block diagram which shows one Embodiment of the dry ice snow washing | cleaning apparatus of this invention. It is a figure which shows the time control sequence of the dry ice snow washing | cleaning apparatus of this invention.

Explanation of symbols

1: Injection nozzle 2: Distribution pipe 3: Orifice 4: Injection gas supply pipe 6: Supply path 7: Heat insulating material 8: Carbon dioxide supply valve 9: Pressure gauge 12: Pressure adjustment valve 13: Pressure gauge 14: Injection gas supply valve 15: Primary heater 16: Thermometer 17: Temperature controller 18: Secondary heater 19: Thermometer 20: Temperature controller

Claims (6)

A device for cleaning by spraying dry ice snow formed by adiabatic expansion of pressurized liquefied carbon dioxide gas from an injection nozzle to an object to be cleaned,
A supply valve that opens and closes the supply of the pressurized liquefied carbon dioxide gas, a throttle part that adiabatically expands the liquefied carbon dioxide gas supplied from the supply valve, and a flow pipe that extends from the throttle part to the injection nozzle,
A dry ice snow cleaning apparatus, wherein an internal volume of a flow path from the valve seat to the throttle portion of the supply valve is set to 0.58 cm ³ or less. The claim 1 Symbol placing dry ice snow cleaning device time to the injection of the dry ice snow is not observed within one second from the injection nozzle to close the supply valve. Dry ice snow cleaning apparatus according to claim 1 or 2, wherein setting the opening area of the throttle portion 0.007 mm ² or more 0.032 mm ² within become so. The dry ice snow cleaning apparatus according to any one of claims 1 to 3 , wherein a supply pressure of the liquefied carbon dioxide gas is set to be within 7 MPa ± 1 MPa. The dry ice as described in any one of Claims 1-4 in which the injection gas supply pipe | tube which supplies injection gas to the injection nozzle vicinity of the said injection nozzle exists in the state isolated thermally from the said flow pipe. Snow cleaning device. A method of cleaning by spraying dry ice snow formed by adiabatic expansion of pressurized liquefied carbon dioxide gas from an injection nozzle to an object to be cleaned,
When the liquefied carbon dioxide gas supplied from the supply valve that opens and closes the supply of the pressurized liquefied carbon dioxide gas is adiabatically expanded in the throttle part, and circulates in the flow pipe from the throttle part to the injection nozzle and is injected from the injection nozzle, the above supply A dry ice snow cleaning method, wherein an internal volume of a flow path from a valve seat to a throttle portion of the valve is 0.58 cm ³ or less.

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