JP2006308176A - Coolant, cooling method and coolant feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coolant, a cooling method and a coolant feeder capable of effectively cooling an article to be cooled such as a welding part. <P>SOLUTION: The coolant containing liquefied carbon dioxide and an additive is stored in a cylinder 1, the coolant is fed to a nozzle 3 through a hose 2, the coolant is heat-insulated and expanded in the nozzle 3, and sherbet wherein dry ice and the additive are mixed is obtained, and is sprayed to the article 4 to be cooled. Fluoroeters kept in the liquid form near the sublimation temperature of the dry ice may be used for the additive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coolant used for cooling an object to be cooled, a cooling method, and a coolant supply device, and in particular, to be effectively used to reduce thermal distortion or the like generated in a welded part during welding. It is a thing.

  The act of cooling things is done everywhere in the industry. For example, welding is performed by locally and rapidly heating the welded portion to melt the base material. The base material exposed to high temperature during welding is then cooled by heat conduction through the base material and simultaneously cooled by radiation to the atmosphere. With such rapid cooling, welding distortion (thermal distortion) occurs in the vicinity of the bead portion.

This weld distortion generates tensile and compressive residual stresses and can even deform in a relatively thin base metal. If deformation occurs in the base material, it becomes a problem in processing, so it is desirable to remove welding distortion. Moreover, if this residual stress cannot be removed, stress corrosion cracking and hydrogen cracking may occur.
As described above, since various problems occur due to residual welding strain, many methods for removing or reducing thermal strain associated with welding have been studied.

  Conventionally, welding distortion has been reduced by heat treatment or mechanical processing such as pressing, rollers, and hammering, but it is difficult to completely remove welding distortion. On the other hand, in order to reduce welding distortion, it is effective to cool the vicinity of the bead portion immediately after welding, and thus water, low-temperature gas, dry ice, or the like may be sprayed onto the bead portion as a coolant.

However, when cooling with water, if water adheres to the surface of the welded portion, an oxide film is formed on the surface, and there is a problem that corrosion resistance and aesthetics are impaired. Further, it is necessary to take measures to prevent water from being scattered and collect water at the welding work site.
Moreover, when spraying low temperature gas, there exists a problem that cooling efficiency is very bad.

Furthermore, there is a method of cooling by directly spraying dry ice on the welded part, but if solid dry ice is used, rebounding occurs due to jetting, and all dry ice cannot be used for cooling, efficiency There is a problem that is bad.
In addition, when snow-like dry ice is used, there is a problem that the dry ice is accompanied by the gas flow accompanying the injection, and the welded part may not be reached, resulting in poor efficiency.
Japanese Patent No. 3627194

  Therefore, the subject in this invention is obtaining the coolant, the cooling method, and coolant supply apparatus which can cool to-be-cooled objects, such as a welding part, efficiently.

To solve this problem,
The invention according to claim 1 is a coolant that is brought into contact with an object to be cooled and cools the object, and the coolant immediately before contacting the object to be cooled is a sherbet containing dry ice and an additive. Provide some coolant.

The invention according to claim 2 is a coolant that contacts and cools an object to be cooled, comprising a liquefied carbon dioxide and an additive, and a coolant that becomes a sherbet when the mixture is adiabatically expanded. provide.
The invention according to claim 3 provides the coolant according to claim 1 or 2, wherein the additive maintains a liquid state at a temperature near the sublimation temperature of dry ice.

The invention according to claim 4 provides a cooling method in which dry ice and a sherbet containing an additive that maintains a liquid state at a temperature near the sublimation temperature of dry ice are brought into contact with an object to be cooled.
The invention according to claim 5 provides the cooling method according to claim 4, wherein the dry ice is obtained by adiabatic expansion of liquefied carbon dioxide.

  The invention according to claim 6 is an apparatus for supplying a coolant to an object to be cooled, comprising a container containing the coolant and a nozzle for adiabatically expanding and injecting the coolant from the container, and cooling. Provided is a coolant supply device in which an agent contains liquefied carbon dioxide and an additive, and the additive is kept in a liquid state at a temperature near the sublimation temperature of carbon dioxide.

The invention according to claim 7 is an apparatus for supplying a coolant to an object to be cooled, comprising a container containing liquefied carbon dioxide and a nozzle for adiabatically expanding and injecting carbon dioxide from the container. A coolant comprising an additive supply unit comprising a dry ice supply unit, a container containing an additive that maintains a liquid state at a temperature near the sublimation temperature of dry ice, and a supply unit that supplies the additive from the container A supply device is provided.
The invention according to claim 8 provides the coolant supply apparatus according to claim 7, wherein the supply part of the additive supply part is connected to the nozzle of the dry ice supply part.

  According to the present invention, since the additive is kept in a liquid state near the sublimation temperature of dry ice, a mixture of dry ice and additive becomes a sherbet, and this is sprayed on the object to be cooled. For this reason, it is possible to prevent the dry ice from splashing, rebounding, and accompanying with the injection gas, the entire amount of the dry ice contacts the object to be cooled, the cooling capacity of the dry ice can be fully utilized, and the object to be cooled can be efficiently cooled. be able to.

Further, if liquefied carbon dioxide and additives are mixed in advance and stored in a container such as a cylinder, no special equipment other than the nozzle is required, and cooling work can be performed simply by supplying a coolant.
Furthermore, by connecting the additive feeding section to a nozzle for injecting liquefied carbon dioxide, the additive can be sucked and supplied by the carbon dioxide ejector effect, and the equipment becomes simple.

The present invention will be described in detail below.
The coolant of the present invention is a sherbet containing dry ice and an additive in a state just before contacting the object to be cooled. The coolant of the present invention is used by being sprayed on an object to be cooled, and a sherbet in which dry ice and an additive are mixed just before 0.01 seconds to 0.5 seconds in contact with the object to be cooled. The sherbet comes into contact with the object to be cooled and cools it.

The dry ice here may be in the form of snow, powder or pellet, and is preferably obtained by adiabatic expansion of liquefied carbon dioxide.
In addition, the additive used here is a liquid that maintains a liquid state at a sublimation temperature of dry ice and at a temperature around −78.5 ° C. under atmospheric pressure. The sublimation temperature of dry ice varies depending on the ambient pressure, but it may be any liquid as long as it maintains a liquid state near the sublimation temperature of dry ice under that pressure.

Specific examples of such additives include methyl chloride (melting point-97.4 ° C), methylene chloride (melting point-96.8 ° C), ethyl chloride (melting point-142.5 ° C), trichloroethylene (melting point- 86.4 ° C.) halogenated hydrocarbons such _{as, C 2 F 5 COC 3 F} 7, C 4 F 9 OCH 3, C 4 F 9 OC 2 H 5 but like fluoroethers such as human safety In view of nonflammability, fluoroethers are preferable.
Table 1 shows the physical properties of these fluoroethers.

  In addition, this additive is sprayed on the object to be cooled together with dry ice. Even if it is cooled below its melting point by dry ice, it only needs to reach the object to be cooled before solidifying. It only has to be solved before reaching the object. For this reason, it does not have to be liquid at the sublimation temperature of dry ice strictly, and it may be liquid near the sublimation temperature.

  Furthermore, the ratio of the additive in the sherbet is not particularly limited as long as it is a range in which the sherbet shape can be maintained, but is usually about 1 to 20 wt%.

  The coolant of the present invention may be composed of liquefied carbon dioxide and an additive. This form of coolant is in a state prior to the operation of spraying the object to be cooled, in a state where a mixture of liquefied carbon dioxide and additive is contained in a container such as a cylinder, or in a separate container. It refers to those containing carbon dioxide and additives.

In this form of coolant, a mixture of liquefied carbon dioxide and an additive is adiabatically expanded to produce dry ice from the liquefied carbon dioxide, and the additive is mixed with the dry ice to form a sherbet, which is sprayed onto the object to be cooled. .
Further, only liquefied carbon dioxide is adiabatically expanded to form dry ice, and an additive is added to this to form a sherbet, which is sprayed on the object to be cooled.
The ratio of the additive shown in the coolant in this form is not particularly limited, but is usually about 1 to 20 wt%.

FIG. 1 shows a first example of the coolant supply apparatus of the present invention, and reference numeral 1 in the drawing denotes a cylinder. The cylinder 1 contains liquefied carbon dioxide and additives.
One end of a hose 2 such as a flexible hose is connected to the on-off valve 1A of the cylinder 1, and the nozzle 3 is connected to the other end. This nozzle 3 adiabatically expands the coolant that has flowed through the hose 2 to make liquefied carbon dioxide into dry ice and spray it onto a welded part 4 such as a welded part as a sherbet mixed with an additive. It is.

FIG. 2 shows an example of the nozzle 3. The nozzle 3 includes a connecting pipe 5, a main body 6 and an injection pipe 7.
The connecting pipe 5 is a metal pipe having an inner diameter of 2 to 10 mm. One end of the connecting pipe 5 is connected to the hose 2 and the other end is connected to the cavity 8 of the main body 6. The distal end portion of the cavity portion 8 of the main body portion 6 is reduced in diameter to about 1 mm to form a throttle portion 9, which is adiabatically expanded when the coolant passes therethrough.

  An injection tube 7 is attached to the tip of the main body 6. The injection pipe 7 is a metal pipe having an inner diameter of 5 to 10 mm and a length of 100 to 200 mm. The coolant that is adiabatically expanded by the throttle portion 9 to become a sherbet is injected from the tip of the pipe. ing.

In the supply device of this example, the opening / closing valve 1A of the cylinder 1 is opened, the coolant in the cylinder 1 is sent from the hose 2 to the nozzle 3, and the nozzle 3 is directed to the object 4 to be cooled, thereby forming a sherbet. The coolant can be sprayed onto the object 4 to be cooled.
At this time, the distance between the tip of the injection pipe 7 of the nozzle 3 and the object 4 to be cooled is about 5 to 30 cm.

  FIG. 3 shows a second example of the supply apparatus according to the present invention. The same components as those shown in FIG. In this example, the cylinder 1 contains only liquefied carbon dioxide, and the liquefied carbon dioxide from the cylinder 1 passes through the hose 2 and is sent to the nozzle 3 to be adiabatically expanded to become dry ice and blown to the object 4 to be cooled. It has become.

  On the other hand, the additive is separately stored in the tank 10, sent to the coolant nozzle 14 through the on-off valve 11, the hose 12, and the pump 13, sprayed from the coolant nozzle 14, and dried from the nozzle 3. It is mixed with ice so that it becomes a sherbet and is sprayed on the object 4 to be cooled.

FIG. 4 shows a third example of the supply device of the present invention, and this example is a modification of the second example. In this example, the additive feeding hose 12 is connected to the connecting pipe 5 of the nozzle 3 so that the additive and liquefied carbon dioxide are mixed and injected from the nozzle 3 as a sherbet. It has become.
In this example, since the additive is sucked by the ejector effect in the nozzle 3, the additive feeding pump 13 can be dispensed with.

FIG. 5 and FIG. 6 show preferred embodiments when the object to be cooled 4 is a welded part immediately after welding.
In FIG. 5, the code | symbol 21 shows a welding torch. An arc electrode 22 is provided at the tip of the welding torch 21, and a shield gas supply unit 23 for blowing out shield gas is formed around the arc electrode 22.

  The welding torch 21 is attached to the holder 24. A box-like cooling box 25 is integrally attached to the holder 24. A coolant supply port 26 is formed on the upper surface of the cooling box 25, and the nozzle 3 (not shown) is inserted and fixed therein. The lower surface side of the cooling box 25 is directly directed to the bead 27 of the welded portion.

Further, the tip 24 a of the holder 24 extends to the tip of the shield gas supply 23, so that carbon dioxide vaporized from the sherbet blown into the cooling box 25 flows into the welding torch 21. The shield gas flow during welding is prevented from being interfered by the carbon dioxide flow.
In this case, the sherbet of the coolant is sprayed on the bead 27 immediately after welding, so that the bead 27 can be rapidly cooled.

  FIG. 6 shows another embodiment. In this apparatus, the nozzle 3 for injecting the coolant is attached to the side of the welding torch 21 by appropriate holding means. Further, the welding torch 21 is arranged so that the direction thereof is perpendicular to the steel plate that is the object 4 to be cooled, and the direction of the nozzle 3 is about 60 degrees with respect to the steel plate 4 as shown in the drawing. In this arrangement, the carbon dioxide injected from the nozzle 3 does not interfere with the flow of the shielding gas flowing out from the welding torch 21 as in the previous example. Yes.

  FIGS. 7A and 7B show other forms of the arrangement relationship between the welding torch 21 and the coolant injection nozzle 3. In this example, the form in the case of semi-automatic welding is shown, the nozzle 3 is arranged on the opposite side of the welding torch 21, and cooling is performed by injecting a coolant from the back of the welded portion.

  In the present invention, in addition to using liquefied carbon dioxide as a supply source of dry ice, powdery dry ice or solid dry ice such as pelletized dry ice is used and supplied to the nozzle 3. You may employ | adopt the method and apparatus which deliver an additive.

FIG. 8 shows a supply apparatus in the case of using such solid dry ice.
Solid dry ice is stored in the hopper 31, and this dry ice is supplied from the hose 32 to the nozzle 33. A hose 35 extending from an injection compressed gas supply source 34 is connected to the nozzle 33, and an injection compressed gas such as compressed air from the injection compressed gas supply source 34 is supplied to the nozzle 33. Dry ice is sent from the hopper 31 by the ejector effect by supply.

The additive is stored in the tank 36 and supplied to the nozzle 33 through the pipe 37 and the valve 38. In the nozzle 33, solid dry ice and additive are mixed to form a sherbet, and this sherbet is sprayed onto the object to be cooled 4. The additive may be supplied from the pipe 39 to the hose 35 through which the compressed gas for injection flows, or sent from the hose 40 to the additive nozzle 41 and sprayed from here on the dry ice sprayed from the nozzle 33 to form a sherbet. Also good.
In addition, when using the hose 40, since an additive cannot acquire the ejector effect by the compressed gas for injection, it is desirable to provide the compression supply source (not shown) for additive injection.

Specific examples are shown below.
Using the coolant supply device shown in FIG. 1 and FIG. 2, the coolant was sprayed on the object 4 to be cooled, and the cooling state was observed.
At this time, in order to confirm the effect of the additive, an example in which liquefied carbon dioxide was used alone and an example in which C ₂ F ₅ COC ₃ F ₇ was added as an additive to the liquefied carbon dioxide were tested.
The diameter of the narrowed portion 9 of the nozzle 3 was 1 mm.

A stainless steel plate having a thickness of 3 mm was used for the object to be cooled 4, the interval between the nozzle 3 and the stainless steel plate was 10 cm, a thermocouple was attached to the back surface of the coolant injection point of the stainless steel plate, and the temperature was measured.
The test conditions are shown in Table 2.

FIG. 9 shows the results of temperature measurement using a stainless steel plate thermocouple. In the graph of FIG. 9, a curve A shows a temperature change when liquefied carbon dioxide and an additive are used together, and a curve B shows a temperature change when liquefied carbon dioxide is used alone.
From the graph of FIG. 9, the combined use of the additive allows the cooling rate to be approximately doubled even though the supply amount of liquefied carbon dioxide is small, and can be cooled to −68 ° C. It became clear that it can cool about 30 degreeC lower than the case of.

It is a schematic block diagram which shows the 1st example of the coolant supply apparatus of this invention. It is a schematic sectional drawing which shows the example of a nozzle with a coolant supply layer. It is a schematic block diagram which shows the 2nd example of the coolant supply apparatus of this invention. It is a schematic block diagram which shows the 3rd example of the coolant supply apparatus of this invention. It is a schematic sectional drawing which shows embodiment of the cooling method of this invention. It is a schematic block diagram which shows another thing of embodiment of the cooling method of this invention. It is a schematic block diagram which shows another thing of embodiment of the cooling method of this invention. It is a schematic block diagram which shows the 4th example of the coolant supply apparatus of this invention. It is a graph which shows the result of the specific example in this invention.

Explanation of symbols

1 .... cylinder, 2 .... hose, 3 .... nozzle, 4 .... object to be cooled, 10 .... tank, 14 .... additive nozzle

Claims (8)

A coolant that contacts and cools an object to be cooled,
A coolant in which the coolant just before coming into contact with an object to be cooled is a sherbet containing dry ice and an additive. A coolant that contacts and cools an object to be cooled,
A coolant comprising liquefied carbon dioxide and an additive, which becomes a sherbet when this mixture is adiabatically expanded.   The coolant according to claim 1 or 2, wherein the additive is in a liquid state at a temperature near the sublimation temperature of dry ice.   A cooling method in which dry ice and a sherbet containing an additive that maintains a liquid state at a temperature near the sublimation temperature of dry ice are brought into contact with an object to be cooled.   The cooling method according to claim 4, wherein the dry ice is obtained by adiabatic expansion of liquefied carbon dioxide. An apparatus for supplying a coolant to an object to be cooled,
A container containing a coolant, and a nozzle that insulates and injects the coolant from the container to insulate,
A coolant supply apparatus in which the coolant contains liquefied carbon dioxide and an additive, and the additive is kept in a liquid state at a temperature near the sublimation temperature of carbon dioxide. An apparatus for supplying a coolant to an object to be cooled,
A container containing liquefied carbon dioxide, and a dry ice supply unit provided with a nozzle for adiabatically expanding and injecting carbon dioxide from the container;
A coolant supply apparatus comprising an additive supply unit comprising a container containing an additive that maintains a liquid state at a temperature near the sublimation temperature of dry ice, and a supply unit that supplies the additive from the container. 8. The coolant supply apparatus according to claim 7, wherein the supply part of the additive supply part is connected to the nozzle of the dry ice supply part.

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