Heat treatment furnace and heat treatment method

Abstract

To provide a heat treatment furnace and a heat treatment method capable of avoiding the use of petroleum-based gas in atmosphere gas and improving work efficiency by suppressing the consumption of the atmosphere gas.SOLUTION: A heat treatment furnace 10 for heat-treating a metal pipe W in atmospheric gas comprises: a purge device 12 for feeding at least one kind selected from the group consisting of hydrogen gas and inert gas into the metal pipe W as purge gas and replacing in-pipe gas of the metal pipe W with the purge gas; and a furnace body 11 for storing, in the furnace, the metal pipe W in which the in-pipe gas is replaced with the purge gas, and performing heat treatment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat treatment furnace and a heat treatment method for heat-treating a metal tube in an atmospheric gas.

Background Art

[0002] Generally, parts, products, etc. made of metal are heat-treated for various purposes such as removing internal stress, adjusting hardness, and improving workability. This heat treatment is performed using a heat treatment furnace, filling the inside of the heat treatment furnace with an atmospheric gas, and setting the atmosphere according to the purpose. As parts, products, etc. to be heat-treated, when a metal tube is heat-treated with air remaining inside, the atmospheric gas becomes contaminated and the atmosphere inside the furnace is impaired, or the inner surface of the metal tube is oxidized or decarburized. Therefore, when the metal tube is heat-treated, air purging is performed by replacing the air inside with an atmospheric gas. Patent Documents 1 and 2 describe an apparatus or method for purging air inside a metal tube. The gas replacement device described in Patent Document 1 is characterized in that a plurality of atmospheric gas injection nozzles inclined toward the loading port side are provided in the plenum chamber in the loading side zone inside the furnace, and atmospheric gas is injected from these nozzles to push out the air inside the metal tube. The purging method described in Patent Document 2 is characterized in that a purge box connected to an exhaust means is provided, and with one end of the metal tube positioned inside the furnace and the other end positioned inside the purge box, the inside of the purge box is forcibly exhausted by the exhaust means, thereby sucking the atmospheric gas inside the furnace into the metal tube to purge the air.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding purging the air inside a metal pipe, Patent Document 1 describes the procedure with the entire metal pipe located inside the furnace, while Patent Document 2 describes the procedure with one end of the metal pipe located inside the furnace. In other words, in Patent Documents 1 and 2, when purging the air inside a metal pipe, all or one end of the metal pipe is located inside the furnace before purging. When purging is performed with at least a part of the metal pipe located inside the furnace in this way, problems arise such as the atmosphere inside the furnace being damaged by air leaking from inside the metal pipe, the need to purge the leaked air from inside the furnace, reduced safety and deterioration of the working environment due to the high-temperature atmospheric gas inside the furnace being drawn into the metal pipe and discharged outside the furnace, and increased consumption of atmospheric gas and decreased work efficiency. Furthermore, while petroleum-based gases, such as propane, are typically used as atmospheric gases, in recent years, with the growing awareness of environmental concerns such as carbon neutrality, decarbonization is being demanded, and the use of hydrogen gas and other alternatives is being considered to avoid the use of petroleum-based gases. However, the use of hydrogen gas and other alternatives as atmospheric gases leads to increased operating costs, so there is a need to reduce the consumption of atmospheric gases.

[0005] The present invention aims to solve the problems of the conventional technology and to provide a heat treatment furnace and heat treatment method that can avoid the use of petroleum-based gases as atmospheric gas, reduce atmospheric gas consumption, and improve work efficiency. [Means for solving the problem]

[0006] To solve the above problems, the invention described in claim 1 is a heat treatment furnace for heat-treating a metal tube in an atmospheric gas, A purging device that introduces at least one gas selected from the group consisting of hydrogen gas and inert gas as a purge gas into the metal pipe and replaces the gas inside the metal pipe with the purge gas, The gist of the invention is a furnace body that houses the metal pipe, in which the gas inside the pipe has been replaced with the purge gas, and heat-treats it. The invention described in claim 2 is the invention described in claim 1, wherein the purging device is The main body has a filling chamber inside, A gas supply system connected to the main body and supplying the purge gas to the filling chamber, The main body is provided with an insertion portion for inserting one end of the metal tube into the filling chamber. The invention described in claim 3 is the invention described in claim 2, wherein the purging device is A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, The gist of the system is that it further includes a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter. The invention described in claim 4 is the invention described in claim 2, wherein the purging device is A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, A measuring instrument for measuring the static pressure of the filling chamber, The gist of the system is that it further includes a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter and the static pressure obtained from the measuring instrument. The invention described in claim 5 is characterized in that, in the invention described in any one of claims 1 to 4, a conveying speed adjustment means is provided to increase the conveying speed of the metal tubes that are to be replaced by the purging device compared to the furnace speed of the metal tubes in the furnace body. The invention described in claim 6 is a heat treatment method for heat treating a metal tube using the heat treatment furnace described in claim 1 or 2, A purging process involves using a purging device to introduce the purge gas into the metal pipe and replacing the gas inside the metal pipe with the purge gas. The gist of the invention is that, after the purging step, the metal pipe, in which the gas inside the pipe has been replaced with the purging gas, is inserted into the furnace body and placed inside the furnace. The invention according to claim 7 is the invention according to claim 6, wherein the purging step comprises: a first step of inserting one end of the metal pipe into the purging device and leaving the other end open to the outside; a second step of fixing the metal pipe to the purging device; a third step of feeding the purging gas into the pipe from one end of the metal pipe inserted into the purging device, discharging the gas inside the pipe from the other end, and replacing the gas inside the pipe with the purging gas.

Advantages of the Invention

[0007] According to the present invention, it is possible to avoid using petroleum-based gas as the atmosphere gas, suppress the consumption of the atmosphere gas, and provide a heat treatment furnace and a heat treatment method capable of improving the working efficiency.

Brief Description of the Drawings

[0008] [Figure 1] Schematic side view showing one form of the heat treatment furnace of the present invention. [Figure 2] Perspective view showing the purging device. [Figure 3] Enlarged front view showing a part of the purging device. [Figure 4] Side view for explaining an example of the purging step in the heat treatment method of the present invention. [Figure 5] (a) and (b) are side views for explaining an example of the insertion step in the heat treatment method of the present invention. [Figure 6] Enlarged plan view showing a modified example of the purging device.

Embodiments for Carrying Out the Invention

[0009] The matters shown here are exemplary and for exemplarily explaining the embodiments of the present invention, and are described for the purpose of providing an explanation that is considered to be most effective and easily understandable for the principles and conceptual features of the present invention. In this regard, it is not intended to show the structural details of the present invention more than necessary for a fundamental understanding of the present invention, and it is to clarify to those skilled in the art how some forms of the present invention are actually embodied by the description in combination with the drawings.

[0010] [1] Heat treatment furnace The heat treatment furnace of the present invention is a heat treatment furnace 10 for heat-treating a metal tube W in an atmosphere gas, a purge device 12 that feeds at least one selected from the group consisting of hydrogen gas and inert gas into the metal tube W as a purge gas and replaces the gas inside the metal tube W with the purge gas, and a furnace body 11 that accommodates the metal tube W with the inside gas replaced with the purge gas in the furnace and performs heat treatment, and is characterized by this (see FIG. 1).

[0011] The heat treatment using the heat treatment furnace 10 is not particularly limited, and examples include annealing, normalizing, quenching, tempering, etc. Among these heat treatments, annealing is useful, and among annealing, bright annealing is particularly useful because it enables a bright finish (cloudiness) of the inner surface of the metal tube W by using the heat treatment furnace 10 of the present invention. Regarding the metal tube W to be used in the heat treatment furnace 10, the type of metal is not particularly limited, and examples include metals such as iron, copper, aluminum, titanium, silver, tungsten, etc., and alloys such as stainless steel, titanium alloy, nickel alloy, copper alloy, etc. Among these, stainless steel is useful because many of its products are subjected to bright annealing. The shape of the metal tube W is not particularly limited as long as it is tubular, such as a circular tube, a square tube, a hexagonal tube, or other angular tubes.

[0012] Regarding the size of the metal tube W, there are no particular limitations on its length, but as it gets longer, it becomes more difficult for internal air and other substances (hereinafter referred to as "tube gas") to escape. Therefore, a longer metal tube W is useful for use in the heat treatment furnace 10 of the present invention. Specifically, the lower limit of the length of the metal tube W is preferably 0.5 m or more, more preferably 0.8 m or more, and even more preferably 1 m or more. There are no particular limitations on the upper limit of the length of the metal tube W, but it is usually 10 m or less. The inner diameter of the metal tube W is not particularly limited, but as it becomes smaller, gas inside the tube is less likely to escape, so a metal tube W with a small inner diameter is useful for use in the heat treatment furnace 10 of the present invention. Specifically, the upper limit of the inner diameter of the metal tube W can be preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 8 mm or less. The lower limit of the inner diameter of the metal tube W is not particularly limited, but can usually be 0.1 mm or more.

[0013] The following describes the furnace body 11, purging device 12, and other components of the heat treatment furnace 10. (1) Furnace body The furnace body 11 is for housing and heat-treating the metal tube W (see Figure 1). The furnace body 11 is not limited in terms of the processing and transport method, configuration, materials used, shape, size, internal volume, heating and cooling method, etc., of the metal tubes W, as long as it is applicable to heat treatment. The processing and transport method for the furnace body 11 can be a continuous type in which the heating and cooling of the metal tubes W involved in heat treatment are performed continuously, or a batch type in which the heating and cooling of the metal tubes W are performed intermittently.

[0014] The furnace body 11 may be equipped with a conveying device 111 for transporting metal tubes W inside the furnace (see Figure 1). The conveying device 111 is not particularly limited in its configuration, as long as it is capable of transporting metal tubes W. Typically, a belt conveyor or the like can be used as the conveying device 111. The furnace body 11 may be equipped with an inlet 112 for inserting the metal tube W into the furnace (see Figure 1). The furnace body 11 may also be equipped with an outlet (not shown) for removing the metal tube W from the furnace. These inlet 112 and outlet can be opened and closed as needed by providing doors (not shown). Within the furnace body 11, the metal tube W can be transported by the transport device 111 from the inlet 112 to the outlet at a constant furnace speed.

[0015] A loading device 13 for loading metal pipes W into the furnace body 11 can be provided between the furnace body 11 and the purging device 12 (see Figure 1). The loading device 13 is not particularly limited in its configuration, as long as it is capable of loading the metal pipes W into the furnace body 11. Typically, a roller conveyor or the like can be used for the loading device 13. The loading device 13 can set the loading speed of the metal pipes W to be the same as the furnace speed of the furnace body 11 by the conveying device 111. In other words, the heat treatment furnace 10 can be configured such that the timing of the metal pipes W being fed into the furnace body 11 and the timing of their transport within the furnace body 11 are synchronized, by setting the feeding speed of the metal pipes W by the feeding device 13 and the furnace speed by the transport device 111 to the same speed. This configuration is useful when processing multiple lots of metal pipes W continuously, as it can suppress time losses due to timing differences between lots and shorten the working time.

[0016] The furnace body 11 can be divided into multiple chambers, or it can consist of only one chamber. When the furnace body 11 is divided into multiple chambers, it can be configured to include a heating chamber (not shown) for applying heat treatment related to heat treatment to the metal tubes W, and a cooling chamber (not shown) for applying cooling treatment related to heat treatment. The heating chamber and cooling chamber are not particularly limited in their internal configuration, structure, etc., and may be designed according to their respective purposes. Typically, the heating chamber can be configured to include a heating device such as an electric heater or a combustion burner for heating the metal tube W. The cooling chamber can be configured to include a cooling device such as a cooler, fan, or blower for cooling the metal tube W.

[0017] If the furnace body 11 is equipped with a heating chamber, it can be configured to have a pre-chamber (not shown) on the inlet 112 side of the heating chamber. The pre-chamber is a chamber for inserting a metal tube W into the furnace and is a chamber that suppresses the flow of outside air into the heating chamber when the metal tube W is inserted. If the furnace body 11 is equipped with a cooling chamber inside the furnace, it may be configured to have a rear chamber (not shown) on the outlet side of the cooling chamber. The rear chamber is a chamber for removing the metal tubes W from inside the furnace and is a chamber that suppresses the flow of outside air into the cooling chamber when the metal tubes W are removed.

[0018] In the heat treatment furnace 10 of the present invention, at least one gas selected from the group consisting of hydrogen gas and inert gas can be used as the atmospheric gas to create an atmosphere suitable for heat treatment inside the furnace body 11. In other words, the atmospheric gas can be a mixture of hydrogen gas and inert gas, hydrogen gas alone, or inert gas alone. Hydrogen (H2) gas can prevent oxidation of the surface and inner surface of the metal tube W by creating a reducing atmosphere inside the furnace and removing oxygen (O2) from the furnace. Inert gases are inert to the metal used in the metal tube W under high-temperature conditions during heat treatment, thus maintaining an oxidation-free atmosphere inside the furnace with hydrogen (H2) gas. Examples of inert gases include nitrogen (N2) gas, helium gas, neon gas, and argon gas. Among inert gases, nitrogen (N2) gas is readily available and its use is cost-effective, making it useful as an atmospheric gas. The aforementioned hydrogen (H2) gas and inert gases do not contain carbon-based gases such as carbon monoxide and carbon dioxide found in petroleum-based gases, and are useful because they can contribute to decarbonization when used as atmospheric gases.

[0019] The furnace body 11 can be configured to have an atmosphere gas supply system connected to it that supplies the aforementioned atmosphere gas into the furnace. The connection location of the atmosphere gas supply system to the furnace body 11 is not particularly limited and can be any location on the furnace body 11. If the furnace body 11 has the above-mentioned heating chamber inside the furnace, the atmosphere gas supply system can be connected to the heating chamber of the furnace body 11. A valve for opening and closing the system can be connected to the atmospheric gas supply system. This valve can be of any type, such as an electric valve, solenoid valve, or check valve.

[0020] The number of circuits in the atmosphere gas supply system connected to the furnace body 11 is not particularly limited. The number of circuits in the atmosphere gas supply system may be one or two or more. When using hydrogen (H2) gas and an inert gas as the atmospheric gas, the atmospheric gas supply system can be configured with two systems: a first supply system for supplying hydrogen (H2) gas and a second supply system for supplying inert gas. With this configuration, the supply amounts of hydrogen (H2) gas and the inert gas to the furnace body 11 can be adjusted individually, and effects such as reducing operating costs by keeping the amount of hydrogen (H2) gas used to the minimum necessary can be obtained. Alternatively, the atmospheric gas supply system can be configured with only one circuit, supplying a mixture of inert gas and hydrogen (H2) gas into the furnace body 11. This configuration simplifies the structure of the atmospheric gas supply system.

[0021] (2) Purge device The purging device 12 injects at least one gas selected from the group consisting of hydrogen gas and inert gases as a purge gas into the metal pipe W, thereby replacing the gas inside the metal pipe W with the purge gas (see Figure 1). The purge device 12 is The main body 21 has a filling chamber 214 inside, A gas supply system 22 connected to the main unit 21 and supplying purge gas to the filling chamber 214, The main body 21 can be configured to include an insertion section 23 into which one end of the metal tube W is inserted into the filling chamber 214 (see Figures 1-3).

[0022] (2-1) Main body The main body 21 is not limited in terms of its configuration, shape, or the volume of the filling chamber 214, as long as it is capable of sending the purge gas stored in the internal filling chamber 214 into the metal pipe W. As a specific example, the main body 21 can be configured to include a box portion 211 and a lid portion 212 (see Figure 2). The box portion 211 can be formed in a box shape with the top and the upper half of the front surface open. The lid portion 212 can be formed in a horizontal L-shape in cross-section so as to close the opening of the box portion 211. The lid portion 212 can be rotatably connected to the rear upper end of the box portion 211 via a hinge (not shown) provided at its rear end (see Figure 2).

[0023] A cylinder 213 is attached to the upper surface of the lid 212. The contraction of the cylinder 213 causes the lid 212 to open the opening of the box 211, and the extension of the cylinder 213 causes the lid 212 to close the opening of the box 211. With the lid portion 212 closing the opening of the box portion 211, a filling chamber 214 can be formed as a space inside the main body 21 (see Figure 1). A supply nozzle 215 is provided on the rear surface of the main body 21 so as to communicate with this filling chamber 214.

[0024] (2-2) Gas supply system The gas supply system 22 is not limited in its configuration, as long as it is connected to the main unit 21 and capable of supplying purge gas to the filling chamber 214. The purge gas used is at least one selected from the group consisting of hydrogen gas and inert gases. Hydrogen (H2) gas is a reducing gas, and when used as a purge gas, it can prevent oxidation of the inner surface of the metal tube W. Inert gases are inert to the metal used in the metal tube W, and when used as a purge gas, they prevent oxidation of the inner surface of the metal tube W. Examples of inert gases include nitrogen (N2) gas, helium gas, neon gas, and argon gas. Among these, argon gas is useful as a purge gas because it can prevent hydrogen embrittlement and nitriding of the metal tube W.

[0025] The purge gas can have the same composition as the atmosphere gas mentioned above, or it can have a different composition. For example, when using a purge gas with the same composition as the ambient gas, a mixture of hydrogen gas and an inert gas, hydrogen gas only, or an inert gas only can be used, depending on the ambient gas. Furthermore, when using a purge gas with a different composition from the atmosphere gas, for example, if the atmosphere gas is a mixture of hydrogen gas and the inert gas nitrogen gas, then hydrogen gas alone, argon gas alone, nitrogen gas alone, or a mixture of hydrogen gas and argon gas can be used.

[0026] As a specific example, if we consider a configuration in which only hydrogen gas is used as the purge gas, the gas supply system 22 can have a tank 221 that stores hydrogen (H2) gas as a gas supply source, and a connection can be made from the tank 221 to the supply nozzle 215 of the main body 21 (see Figure 1). Furthermore, the gas supply system 22 can be configured such that the tank 221 and the main unit 21 (supply nozzle 215) are connected by a flexible hose. In this configuration, the movement of the purge device 12 can be avoided.

[0027] When a mixed gas of hydrogen gas and an inert gas is used as the purge gas, the gas supply system may have two or more circuits, such as a first circuit for supplying hydrogen (H2) gas and a second circuit for supplying the inert gas, although not specifically shown in the diagram. When the gas supply system has multiple lines, each line can be connected to a supply nozzle 215 of the main unit 21, or the multiple lines can be merged into a single line and that merged line can be connected to a supply nozzle 215 of the main unit 21. When argon gas is used as the inert gas, the gas supply system can be configured to include a tank for storing argon gas as the gas supply source. Furthermore, when nitrogen gas is used as the inert gas, the gas supply system can be configured to include, for example, a tank for storing nitrogen gas, a PSA-type nitrogen gas production device for producing nitrogen gas, etc., as the gas supply source. Regarding the gas supply system described above, the gas supply source and the main unit 21 (supply nozzle 215) can be connected by a flexible hose.

[0028] A flow meter 222 can be connected to the gas supply system 22 (see Figure 1). The flow meter 222 can measure the flow rate of purge gas (hydrogen gas) in the gas supply system 22, and by using the flow meter 222, the amount of purge gas (hydrogen gas) supplied to the filling chamber 214 of the main unit 21 can be measured. Furthermore, when multiple gas supply systems are provided, flow meters can be connected to each system, such as the system supplying hydrogen (H2) gas and the system supplying inert gas. When flow meters are connected to each of the multiple systems, the sum of the values ​​measured by each flow meter can be used as the flow rate of the purge gas to measure the amount of purge gas supplied to the filling chamber 214 of the main unit 21.

[0029] A control valve 223 can be connected to the gas supply system 22 (see Figure 1). The amount of purge gas supplied to the filling chamber 214 of the main body 21 can be adjusted using the adjustment valve 223. The adjustment valve 223 adjusts the supply amount to 0 (m³) as needed. 3By setting it to / h, the supply of purge gas to the filling chamber 214 of the main body 21 can be stopped. The type of valve body used in the adjustment valve 223 is not particularly limited, but an electric valve that can linearly adjust the supply amount can be used. Furthermore, when multiple gas supply lines are provided, the control valve can be connected to each line, such as the line supplying hydrogen (H2) gas and the line supplying inert gas. When the control valve is connected to each of the multiple lines, the supply amount of each gas used as purging gas, such as hydrogen gas and inert gas, can be adjusted.

[0030] (2-3) Insertion part The insertion section 23 is provided on the main body 21 and allows one end of the metal tube W to be inserted into the filling chamber 214; however, there are no particular restrictions on its configuration. As a specific example, the insertion portion 23 can be provided in the shape of an elongated hole on the front surface of the main body 21 (see Figure 3). This elongated insertion portion 23 can be formed in the main body 21 by a gap provided between the upper front end of the box portion 211 and the lower front end of the lid portion 212, with the lid portion 212 closing the opening of the box portion 211. In the elongated insertion section 23, multiple metal tubes W can be inserted side-by-side so that one end of each tube is located inside the main body 21, i.e., in the filling chamber 214 (see Figures 2 and 3). The metal tube W is held in a state where one end is inserted into the filling chamber 214 of the main body 21, and the other end remains exposed to the outside of the main body 21 (see Figure 1).

[0031] A sealing material 231 can be provided inside the insertion portion 23. The sealing material 231 is intended to prevent leakage of purge gas from the insertion portion 23. There are no particular restrictions on the material of the sealing material 231, but typically, elastic materials or foams made of synthetic resins such as silicone resin or urethane resin can be used. As a specific example, the sealing material 231 is provided at the upper front end of the box portion 211 and at the lower front end of the lid portion 212. When the lid portion 212 closes the opening of the box portion 211, the sealing material 231 sandwiches the metal pipe W between them, deforms according to the outer shape of the metal pipe W, and presses against the outer surface of the metal pipe W, thereby preventing leakage of purge gas from the insertion portion 23 (see Figure 3).

[0032] (2-4) Measuring device The purging device 12 can have a measuring instrument 24 connected to its main body 21 to measure the static pressure of the filling chamber 214. Here, the static pressure of the filling chamber 214 refers to the force (pressure) exerted by the purge gas filling the filling chamber 214 to push the gas inside the metal pipe W out of the pipe. The purging device 12 purges the gas inside the metal pipe W by supplying purge gas to the filling chamber 214 of the main body 21, sending the gas into the metal pipe W, and pressurizing the gas inside the pipe (mainly oxygen) out of the pipe. Therefore, if leakage occurs from the filling chamber 214 of the purge gas unit 21, the force (pressure) of the purge gas to push out the gas inside the metal pipe W will be insufficient. In particular, when hydrogen gas is used as the purge gas, hydrogen gas molecules are very small and therefore prone to leaking from the filling chamber 214 of the unit 21.

[0033] The measuring instrument 24 can measure the static pressure in the filling chamber 214. Therefore, based on the measurement results from the measuring instrument 24, it is possible to determine whether the static pressure is sufficient to purge the gas inside the metal pipe W. In other words, the purge device 12 can maintain sufficient static pressure to purge the gas inside the metal pipe W by equipping the main body 21 with a measuring instrument 24. The type of measuring instrument 24 is not particularly limited as long as it can measure static pressure, but a pressure gauge can usually be used.

[0034] (2-5) Controller The purging device 12 can be configured to include a controller 25 that manages the replacement of the gas inside the metal pipe W with purge gas. This controller 25 may use a computer that stores pre-set values ​​related to the management of replacement with purge gas, as well as a program related to that management. The controller 25 can be electrically connected to the flow meter 222 and the control valve 223 of the gas supply system 22 described above. The controller 25 can obtain the flow rate of the purge gas from the flow meter 222 and calculate the amount of purge gas to be supplied to the filling chamber 214 of the main unit 21 based on that flow rate. The controller 25 then compares the calculated supply amount of purge gas with a set value and controls the opening and closing of the adjustment valve 223 so that the supply amount is within the range of the set value, thereby managing the replacement of the gas inside the metal pipe W with purge gas.

[0035] Specifically, the amount of purge gas supplied to the filling chamber 214 of the main body 21 can be set to be equal to or greater than the internal volume of the metal pipe W (or the total internal volume of the multiple metal pipes W if there are multiple metal pipes W). The controller 25 can manage the supply amount of purge gas to the filling chamber 214 of the main unit 21 by opening the adjustment valve 223 until the supply amount reaches a set value, and then closing the adjustment valve 223 after the set value is reached.

[0036] Furthermore, the controller 25 can be electrically connected to the measuring instrument 24 described above. In this case, the controller 25 can have a function to obtain the static pressure of the filling chamber 214 of the main body 21 from the measuring instrument 24 and compare it with a range of preset values ​​to determine whether or not it is possible to replace the gas inside the metal pipe W with purge gas. Specifically, if the acquired static pressure falls below the set value, the controller 25 can increase the static pressure in the filling chamber 214 of the main body 21 by operating the adjustment valve 223 and increasing the flow rate of the purge gas (hydrogen gas in the case of Figure 1). Furthermore, after increasing the static pressure in the filling chamber 214 of the main unit 21 and bringing it within the set range, the controller 25 can operate the adjustment valve 223 again to return the flow rate of the purge gas (hydrogen gas in the case of Figure 1) to its original value.

[0037] (2-6) Conveying speed adjustment means The heat treatment furnace 10 can be configured to include a transport speed adjustment means that increases the transport speed of the metal tubes W targeted for replacement by the purging device 12 compared to the furnace speed of the metal tubes W in the furnace body 11. Normally, when a metal tube W is brought into the furnace body 11, if a purge device 12 is used to replace the gas inside the metal tube W with purge gas, the timing of bringing the tube in will be delayed by the time required for this operation. As described above, the heat treatment furnace 10 can shorten the working time by setting the speed of bringing the metal tube W in using the metal tube W bringing device 13 and the furnace speed using the transport device 111 to be the same, and synchronizing the timing of bringing the tube into the furnace body 11 with the timing of transport within the furnace body 11. To maintain the advantage of reduced working time, it is necessary to eliminate the delay in the timing of material delivery caused by the operation using the purging device 12. In other words, the transport speed adjustment means aims to eliminate the delay in the timing of material delivery by increasing the transport speed of the metal tubes W targeted for replacement by the purging device 12 compared to the furnace speed of the metal tubes W in the furnace body 11.

[0038] Specifically, the conveying speed adjustment means can be configured to include a mounting platform 31 and a conveyor 32 that transports the mounting platform 31 (see Figure 1). In the purging device 12, the main body 21 and other components are placed on a mounting platform 31 and are configured to be transportable by the movement of a conveyor belt 32. The metal pipe W targeted for replacement by the purging device 12 is supported on the mounting platform 31 with one end still inserted into the filling chamber 214 of the main body 21, and is configured to be transported together with the main body 21 of the purging device 12 by the movement of the conveyor 32.

[0039] In the conveying speed adjustment means, the conveying speed by the conveyor 32 is set to be faster than the furnace speed of the metal tubes W carried by the conveying device 111. That is, the mounting table 31 and conveyor 32 that constitute the conveying speed adjustment means can eliminate the delay in the timing of loading caused by the operation using the purging device 12 by increasing the conveying speed of the metal tubes W targeted for replacement by the purging device 12 compared to the furnace speed of the metal tubes W in the furnace body 11. Furthermore, in the conveying speed adjustment means, the mounting platform 31 is made capable of being transported by the conveyor 32, including the main body 21 of the purging device 12, together with the metal pipes W. In other words, the conveying speed adjustment means enables the transport of the metal pipes W to the furnace body 11 while simultaneously performing work on the metal pipes W using the purging device 12. This minimizes the delay in the timing of loading caused by work using the purging device 12.

[0040] (3) Purge device (example of modification) The purging device 12 sends purge gas into the metal pipe W and replaces the gas inside the metal pipe W with the purge gas. It is not limited to the above configuration, but can also be configured as follows. In other words, the purging device 12 can be configured to include a main body 21 having a filling chamber 214 inside, a gas supply system 22 connected to the main body 21 and supplying purge gas to the filling chamber 214, and a gas discharge section 27 extending from the main body 21 and inserted into one end of the metal pipe W (see Figure 6).

[0041] (3-1) Main body The main body 21 is not limited in terms of its configuration, shape, or the volume of the filling chamber 214, as long as it is capable of sending the purge gas stored in the internal filling chamber 214 into the metal pipe W. As a specific example, the main body 21 can be formed in a box shape, and its interior can be used as a filling chamber 214 (see Figure 6). A supply nozzle 215 can be provided on the rear surface of the main body 21 so as to communicate with the filling chamber 214. A discharge nozzle 216 can be provided on the front of the main body 21 so as to communicate with the filling chamber 214. Multiple discharge nozzles 216 can be provided depending on the number of metal pipes W to be processed.

[0042] (3-2) Gas supply system The gas supply system 22 is not limited in its configuration, as long as it is connected to the main unit 21 and capable of supplying purge gas to the filling chamber 214. This gas supply system 22 can be the same as the one described above in "(2) Purge device" and "(2-2) Gas supply system". Furthermore, the gas supply system 22 can be connected to a supply nozzle 215 provided on the rear surface of the main body 21, and purge gas can be supplied to the filling chamber 214 via the supply nozzle 215.

[0043] (3-3) Gas discharge section The gas discharge section 27 extends from the main body 21 and can be inserted into one end of the metal pipe W; however, its configuration and other aspects are not particularly limited. As a specific example, the gas discharge section 27 can be configured to include an insertion nozzle 271 inserted into one end of the metal pipe W, and an air supply tube 272 connected between the insertion nozzle 271 and the discharge nozzle 216 of the main body 21 (see Figure 6). The insertion nozzle 271 is not particularly limited, but for example, it can be formed in the shape of a pipe with a smaller diameter than the metal pipe W so that it can be inserted into one end of the metal pipe W. The air supply tube 272 is not particularly limited, but for example, it can be formed using a resin tube and can supply purge gas discharged from the filling chamber 214 through the discharge nozzle 216 to the insertion nozzle 271. The metal pipe W is held in a state where an insertion nozzle 271 is inserted into one end and the other end is exposed to the outside.

[0044] (3-4) Measuring device This purging device 12 can be configured to include a measuring instrument similar to the one described in "(2) Purge device" above, specifically "(2-4) Measuring instrument".

[0045] (3-5) Controller This purge device 12 can be configured to include a controller similar to the one described in "(2) Purge Device" (2-5) above.

[0046] (3-6) Conveying speed adjustment means This purging device 12 can be configured to move together with the transported metal pipes W inside the heat treatment furnace 10 using a transport speed adjustment means similar to the "(2-6) transport speed adjustment means" of the "(2) purging device" described above.

[0047] [2] Heat treatment method The present invention is a heat treatment method for heat treating a metal tube W using the heat treatment furnace 10 described above, A purging step is performed by using a purging device 12 to introduce at least one gas selected from the group consisting of hydrogen gas and inert gases as a purge gas into the metal pipe W, thereby replacing the gas inside the metal pipe W with the purge gas. The invention is characterized by comprising an insertion step, in which, after the purging step, the metal pipe W, whose internal gas has been replaced with purging gas, is inserted into the furnace body 11 and housed inside the furnace.

[0048] (1) Purge process The purging process includes a first step of inserting one end of the metal pipe W into the purging device 12 and leaving the other end open to the outside, A second step involves fixing the metal pipe W to the purging device 12, The configuration may include a third step of supplying purge gas into the metal pipe W inserted into the purge device 12 from one end and discharging the gas inside the pipe from the other end, thereby replacing the gas inside the pipe with purge gas.

[0049] Figure 4 is an explanatory diagram illustrating the first, second, and third steps of the purging process. In the first step of the purging process, the lid portion 212 of the main body 21 is opened by the contraction of the cylinder 213, and the metal tube W is positioned in the insertion portion 23 with one end located in the filling chamber 214. At this time, the other end of the metal tube W is located outside the main body 21 and is in an open state. In the second step of the purging process, the lid portion 212 is closed in the main body 21 by the extension of the cylinder 213, and the metal pipe W is fixed in the insertion portion 23 by being sandwiched between the upper and lower sealing materials 231.

[0050] In the third step of the purging process, as a preceding step, the supply of purge gas to the filling chamber 214 of the main body 21 is started, and the filling chamber 214 is filled with purge gas. Furthermore, in the third step, as a subsequent step, the purge gas that filled the filling chamber 214 is sent into the metal pipe W from one end, and the gas inside the pipe is pushed out and discharged from the other end of the metal pipe W. Then, in the third step, the gas inside the metal pipe W is discharged and replaced with purge gas.

[0051] In the purging process using the purging device 12 described above, the entire metal tube W is placed outside the furnace body 10 (hereinafter referred to as "outside the furnace"), rather than inside the furnace body 10, and the gas inside the tube is replaced with purging gas. Then, the metal tube W, after the internal gas has been replaced with purge gas, is inserted into the furnace body 10. In other words, the gas inside the tube is discharged from the other end of the metal tube W outside the furnace body 10, and therefore does not enter the furnace. As a result, the atmosphere inside the furnace body 10 is not contaminated by the gas inside the metal tube W. Furthermore, when the metal tube W is inserted into the furnace body 10, the gas inside the tube is replaced with a purge gas consisting of an inert gas such as hydrogen gas, argon gas, or nitrogen gas, which prevents oxidation of the inner surface of the metal tube W due to the gas inside the tube.

[0052] In the third step, along with the replacement of the gas inside the metal tube W with purge gas in the preceding and succeeding steps described above, the transport of the metal tube W to the furnace body 11 by the mounting platform 31 and conveyor 32 can be started. The timing of the start of the transport can be at any point during the third process and is not particularly limited. For example, the start of the transport can be at the same time as the start of the process following the third process, or it can be between the start and end of the process following the third process, or it can be at the same time as the start of the process preceding the third process. Among these options, if the timing of the start of transport is set to coincide with the start of the post-processing step of the third process, or between the start and end of the post-processing step of the third process, the gas inside the metal tube W can be replaced with purge gas during transport to the furnace body 11, thereby improving work efficiency and proving useful.

[0053] The third step continues until the supply of purge gas to the filling chamber 214 reaches a certain value. This supply amount of purge gas can be set to an amount that allows the inside of the metal pipe W to be evenly replaced with purge gas. The amount of purge gas supplied to the filling chamber 214 is the flow rate of purge gas from the gas supply system 22 to the main body 21 (m³ 3 This is the cumulative value over time (supply time) in seconds.

[0054] Specifically, the lower limit of the purge gas supply is the supply amount A(m 3 ) and the internal volume of the metal pipe W is d(m 3 In this case, it is preferably 1.5 times or more the internal volume of the pipe (1.5 × d ≤ A), and more preferably 2 times or more the internal volume of the pipe (2 × d ≤ A). Furthermore, when processing multiple metal pipes W together, let n be the number of metal pipes W, and let D be the total internal volume of the multiple metal pipes W [= d(m³)]. 3 Assuming [D × n], the lower limit of the supply amount of purge gas is preferably 1.5 times or more the total volume inside the pipe (1.5 × D ≤ A), and more preferably 2 times or more the total volume inside the pipe (2 × D ≤ A). The upper limit of the supply amount of purge gas is not particularly limited, but from the viewpoint of reducing the use of high-cost purge gases such as hydrogen gas and argon gas, it is preferably 3 times or less the internal volume of the pipe (or total internal volume) (A ≤ 3 × d or A ≤ 3 × D), and more preferably 2.5 times or less the internal volume of the pipe (or total internal volume) (A ≤ 2.5 × d or A ≤ 2.5 × D).

[0055] Furthermore, in the third step, the supply of purge gas to the filling chamber 214 can be controlled based on the static pressure of the filling chamber 214 obtained from the measuring instrument 24. In other words, in the third step, by measuring the static pressure of the filling chamber 214, it is possible to confirm whether or not there is any leakage of purge gas from the filling chamber 214 of the main body 21. The static pressure of the filling chamber 214 is not particularly limited, but from the viewpoint of effectively pushing out the gas inside the pipe with the purge gas, it is preferably at or above normal pressure (usually atmospheric pressure), and more preferably it can be a pressure exceeding normal pressure. Specifically, the static pressure can preferably be between 1 atmosphere and 3 atmospheres.

[0056] (2) Insertion process The insertion process involves inserting the metal tube W into the furnace body 11. During the insertion process, the metal tube W can be inserted into the furnace body 11 by only the other end (see Figure 5(b)), or the entire tube can be inserted into the furnace body 11. Figures 5(a) and 5(b) are explanatory diagrams illustrating the insertion process. The insertion process may include a release operation in which the lid 212 of the main body 21 of the purging device 12 is opened and the fixing of the metal pipe W to the main body 21 is released (see Figure 5(a)). In the third step of the purging process described above, the timing of the termination of the supply of purge gas to the metal pipe W can be approximately simultaneous with the start of the fixing release operation, or immediately before the start of the fixing release operation.

[0057] The insertion process may include a transfer operation in which the metal pipe W, which was transported in the third step of the purging process, is transferred from the purging device 12 to the loading device 13 (see Figure 5(a)). The insertion process may include a transfer operation in which the metal tube W on the loading device 13 is moved from the loading device 13 to the transport device 111 of the furnace body 11 (see Figure 5(b)). The insertion process may include inserting at least the other end of the metal tube W into the inlet 112 of the furnace body 11 (see Figure 5(b)). The insertion process allows for the prevention of outside air (air) entering the metal pipe W when at least the other end of the metal pipe W is inserted into the furnace body 11, thereby stopping the supply of purge gas to the metal pipe W by the purge device 12. Furthermore, after the insertion process, the metal tube W is placed on the transport device 111 and transported into the furnace through the inlet 112 of the furnace body 11.

[0058] In the insertion process, the release operation can be performed before the handover operation, or it can be performed after the insertion operation. If the release of the fixing is performed before the handover work, the specific order of each work related to the insertion process can be as follows: termination of the supply of purge gas to the metal pipe W (completion of the third step of the purging process), release of the fixing, handover work, transfer work, and insertion work. In this work sequence, the handover, transfer, and insertion operations can be performed continuously without interruption. In this case, by quickly transporting the metal pipe W, whose internal gas has been replaced with purge gas, to the furnace body 11 without stopping it outside the furnace body 11, the inflow of outside air into the metal pipe W can be effectively suppressed.

[0059] If the release operation is performed after the insertion operation, the specific order of each operation related to the insertion process can be as follows: handover operation, transfer operation, insertion operation, completion of supplying purge gas to the metal pipe W (completion of the third operation of the purge process), and release operation. In other words, in the third step of the purging process, the metal pipe W is also transported to the furnace body 11 by the mounting table 31 and the conveyor 32, and the metal pipe W is transported to a position where the other end is inserted into the furnace body 11. Furthermore, when the release operation is performed after the insertion operation, the other end of the metal pipe W can be inserted into the furnace body 11 before the supply of purge gas into the metal pipe W is stopped, thereby preventing outside air from flowing into the metal pipe W.

[0060] Furthermore, if the release operation is performed after the insertion operation, that is, if the other end of the metal pipe W is transported to the position where it is inserted into the furnace body 11 in the third step of the purging process, it is preferable to suppress the ingress of gas discharged from the other end of the metal pipe W into the furnace body 11. The intrusion of tube gas into the furnace body 11 can be suppressed by completing the replacement of tube gas in the metal tube W with purge gas in the third step of the purging process immediately before the insertion operation. Specifically, before the other end of the metal tube W reaches the position where it is inserted into the furnace body 11, the controller 25 controls the flow rate of the purge gas in the third step (m³) so that the amount of purge gas supplied reaches an amount that can evenly replace the inside of the metal tube W. 3 By appropriately adjusting the supply time ( / s), the static pressure of the filling chamber 214, etc., it is possible to suppress the intrusion of pipe gas into the furnace body 11.

[0061] In the insertion process described above, the conveying speed of the metal tube W by the loading device 13 [S2 (m / h)] and the conveying speed of the furnace body 11 inside the furnace by the conveying device 111 [S3 (m / h)] are the same (S2 = S3). As a result, when heat-treating multiple lots of metal tubes W, the timing of transport by the transport device 13 and the timing of transport within the furnace by the transport device 111 are synchronized, for example, when transferring the metal tubes W from the transport device 13 to the transport device 111, or when transporting the metal tubes W to each chamber in the furnace. In other words, since the insertion process is carried out at a constant transport speed for the metal tubes W, all timings related to the transport of the metal tubes W in the insertion process, such as the timing of inserting the metal tubes W into the furnace and the timing of transporting the metal tubes W to each chamber in the furnace, can be synchronized, making it useful for heat-treating multiple lots of metal tubes W.

[0062] (3) Adjustment of transport speed The heat treatment method of the present invention includes a purging step and an insertion step. For example, the first and second steps of the purging step, and the fixing release operation in the insertion step, must be performed with the transport of the metal tube W to the furnace body 11 stopped. As a result, a discrepancy occurs in the synchronization of the timing of transport of the metal tube W in the purging step and the timing of transport of the metal tube W in the insertion step. To eliminate this timing discrepancy in transport, the purging device 12 in the heat treatment furnace 10 described above is equipped with a means for adjusting the transport speed.

[0063] The conveying speed adjustment means conveys the main body 21 of the purging device 12 together with the metal pipe W using the mounting platform 31 and the conveyor 32 (see Figures 1 and 4). In the conveying speed adjustment means, the conveying speed [S1 (m / h)] by the conveyor 32, such as the metal pipe W or the purging device 12, is faster than the conveying speed [S2 (m / h)] by the loading device 13 and the conveying speed [S3 (m / h)] by the conveying device 111 (S1 > S2, S1 > S3). In other words, the delay in transport caused by the purging process described above can be eliminated by making the transport speed of the conveyor 32 (S1) faster than the transport speed of the loading device 13 (S2) and the transport speed of the transport device 111 (S3). Therefore, the timing of transporting the metal tube W in the purging process and the timing of transporting the metal tube W in the insertion process can be synchronized. [Industrial applicability]

[0064] This invention can be used in a wide range of products and is particularly useful from the standpoint of carbon neutrality. [Explanation of Symbols]

[0065] W; metal tube, 10; heat treatment furnace, 11; Furnace body, 111; Conveyor device, 112; Inlet, 12; purging device, 13; loading device, 21; Main body, 211; Box section, 212; Lid section, 213; Cylinder, 214; Filling chamber, 215; Supply nozzle, 216; Discharge nozzle, 22; Gas supply system, 221; Tank, 222; Flow meter, 223; Control valve, 23; Insertion part, 231; Sealing material, 24; Measuring instruments, 25; Controllers, 27; Gas discharge section, 271; Insertion nozzle, 272; Air supply tube, 31; Platform; 32; Conveyor.

Claims

1. A heat treatment furnace for heat-treating a metal tube in an atmospheric gas, A purging device that introduces at least one gas selected from the group consisting of hydrogen gas and inert gas as a purge gas into the metal pipe and replaces the gas inside the metal pipe with the purge gas, The furnace comprises a furnace body that houses the metal tube, in which the gas inside the tube has been replaced with the purge gas, and heat-treats it, The purging device is, The main body has a filling chamber inside, A gas supply system connected to the main body and supplying the purge gas to the filling chamber, The main body is provided with an insertion portion for inserting one end of the metal tube into the filling chamber, The purging device is, A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, A heat treatment furnace further comprising a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter.

2. A heat treatment furnace for heat-treating a metal tube in an atmospheric gas, A purging device that introduces at least one gas selected from the group consisting of hydrogen gas and inert gas as a purge gas into the metal pipe and replaces the gas inside the metal pipe with the purge gas, The furnace comprises a furnace body that houses the metal tube, in which the gas inside the tube has been replaced with the purge gas, and heat-treats it, The purging device is, The main body has a filling chamber inside, A gas supply system connected to the main body and supplying the purge gas to the filling chamber, The main body is provided with an insertion portion for inserting one end of the metal tube into the filling chamber, The purging device is, A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, A measuring instrument for measuring the static pressure of the filling chamber, A heat treatment furnace further comprising a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter and the static pressure obtained from the measuring instrument.

3. The heat treatment furnace according to claim 1 or 2, further comprising a transport speed adjustment means for increasing the transport speed of the metal tubes targeted for replacement by the purging device compared to the furnace speed of the metal tubes in the furnace body.

4. A heat treatment furnace for heat-treating a metal tube in an atmospheric gas, A purging device that introduces at least one gas selected from the group consisting of hydrogen gas and inert gas as a purge gas into the metal pipe and replaces the gas inside the metal pipe with the purge gas, The furnace comprises a furnace body that houses the metal tube, in which the gas inside the tube has been replaced with the purge gas, and heat-treats it, A heat treatment furnace characterized by comprising a transport speed adjustment means that increases the transport speed of the metal tubes targeted for replacement by the purging device compared to the furnace speed of the metal tubes in the furnace body.

5. The purging device is, The main body has a filling chamber inside, A gas supply system connected to the main body and supplying the purge gas to the filling chamber, The heat treatment furnace according to claim 4, further comprising an insertion portion provided in the main body for inserting one end of the metal pipe into the filling chamber.

6. The purging device is, A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, The heat treatment furnace according to claim 5, further comprising a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter.

7. The purging device is, A flow meter connected to the gas supply system for measuring the flow rate of the purge gas into the filling chamber, A measuring instrument for measuring the static pressure of the filling chamber, The heat treatment furnace according to claim 5, further comprising a controller that manages the replacement of the gas inside the metal pipe with the purge gas based on the flow rate of the purge gas obtained from the flow meter and the static pressure obtained from the measuring instrument.

8. A heat treatment method for heat-treating a metal tube using a heat treatment furnace according to claim 1, 2, or 4, A purging step involves using a purging device to introduce at least one gas selected from the group consisting of hydrogen gas and inert gases as a purge gas into the metal pipe, thereby replacing the gas inside the metal pipe with the purge gas. A heat treatment method characterized by comprising, after the purging step, an insertion step of inserting the metal pipe, in which the gas inside the pipe has been replaced with the purging gas, into a furnace body and housing it inside the furnace.

9. The purging process described above is: The first step involves inserting one end of the metal pipe into the purging device and leaving the other end open to the outside. A second step involves fixing the metal pipe to the purging device, The heat treatment method according to claim 8, comprising a third step of sending the purge gas into the metal pipe inserted into the purge device from one end of the pipe and discharging the gas inside the pipe from the other end, thereby replacing the gas inside the pipe with the purge gas.

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