Tube heating device and tube heating method

Abstract

To provide a pipe heating device that efficiently heats the entire pipe, including its inner surface. [Solution] The pipe heating device (1) comprises a flow path (21) that guides the hot air generated in the hot air generating unit (10) to the heating chamber (30), and a heating chamber (30) connected to the flow path (21) and housing the pipe to be heated. The flow path (21) directs the hot air generated in the hot air generating unit (10) along the pipe axis direction of the pipe to be heated housed in the heating chamber (30).

Description

Technical Field

[0001] The present invention relates to a tube heating device and a tube heating method.

Background Art

[0002] Generally, metal pipes for various fluids such as tap water and gas, or other various metal products are commonly painted for corrosion prevention. In particular, ductile iron pipes for water supply are often powder-coated from the viewpoints of chemical stability, durability, workability, etc. As a tube heating technique therefor, there is, for example, one disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique disclosed in Patent Document 1, the tube is heated by blowing hot air only on the outer surface of the tube body. Since hot air is blown only on the outer surface of the tube body, the heating time for reaching a sufficient temperature becomes long. Therefore, if the heating time is insufficient, the inner surface of the tube is not sufficiently heated, and there is a possibility of causing painting defects.

[0005] One aspect of the present invention aims to realize a tube heating device and a tube heating method capable of efficiently heating the entire tube including the inner surface of the tube.

Means for Solving the Problems

[0006] To solve the aforementioned problems, a pipe heating device according to one aspect of the present invention is a pipe heating device for heating a pipe, comprising: a hot air generating unit for generating hot air; a flow path for guiding the hot air generated in the hot air generating unit to a heating chamber; and a heating chamber connected to the flow path and housing a pipe to be heated, wherein the flow path is configured to cause the hot air generated in the hot air generating unit to flow along the pipe axis direction of the pipe to be heated housed in the heating chamber.

[0007] According to the above configuration, hot air is blown onto the pipe to be heated along the pipe axis, and the hot air hits the inner and outer surfaces of the pipe, allowing the entire pipe to be heated efficiently.

[0008] In one aspect of the present invention, a pipe heating device may be configured such that, in the above configuration, a wind speed assist unit for increasing the wind speed of the hot air is provided in the flow path at the inlet to the heating chamber for the hot air.

[0009] According to the above configuration, the heating efficiency of the tube to be heated is improved by increasing the air velocity before the hot air flows into the heating chamber.

[0010] In one aspect of the present invention, a pipe heating device may be configured such that, in the above configuration, a compression section is provided in the heating chamber to compress the hot air and guide it to the end of the pipe to be heated, such that when the passage path of the hot air, which starts from the inlet to the heating chamber for the hot air and ends at the end of the pipe to be heated, is cut by a plane perpendicular to the direction of travel of the hot air, the cross-sectional area at the end of the pipe to be heated is smaller than the cross-sectional area at the starting point when the cross-sectional area at the starting point and the end of the pipe to be heated are compared.

[0011] According to the above configuration, hot air can be effectively blown onto both the inner and outer surfaces of the pipe to be heated, thereby improving the heating efficiency of the pipe.

[0012] In one aspect of the present invention, the pipe heating apparatus may be configured such that a conveying unit for conveying the pipe to be heated is provided in the heating chamber.

[0013] According to the above configuration, the efficiency of the pipe heating operation can be improved by continuously transporting multiple pipes to be heated into the heating chamber using the transport unit.

[0014] In one aspect of the present invention, the pipe heating apparatus may be configured such that, in the above configuration, a shutter is provided in the heating chamber that is closed when the pipe to be heated is being heated in the heating chamber, and opens when the pipe to be heated is being transported by passing it through the end of the heating chamber.

[0015] According to the above configuration, when heating the pipe to be heated in the heating chamber, the shutter can be closed to improve heating efficiency, and when loading / unloading pipes into / out of the heating chamber, the shutter can be opened to prevent the loading / unloading of pipes from being obstructed by the shutter.

[0016] Furthermore, in order to solve the above-mentioned problems, a pipe heating method according to one aspect of the present invention is a pipe heating method for heating a pipe, comprising: a transport step of transporting a pipe to be heated into a heating chamber; and a heating step of heating the pipe by flowing hot air into the heating chamber along the pipe axis direction of the pipe to be heated.

[0017] According to the above configuration, in the heating step, hot air is blown onto the pipe to be heated along the pipe axis direction, so that the hot air hits both the inner and outer surfaces of the pipe, allowing the entire pipe to be heated efficiently.

[0018] A pipe heating method according to one aspect of the present invention may include an opening / closing control step that controls the opening and closing of a shutter provided at the end of the heating chamber when the pipe to be heated is being heated in the heating chamber or when the pipe to be heated is being transported by passing it through the end of the heating chamber.

[0019] According to the above configuration, when heating the tube to be heated in the heating chamber, the shutter can be closed to improve the heating efficiency. Also, when loading the tube into the heating chamber / removing the tube from the heating chamber, the shutter can be opened so that the loading / removing of the tube into / from the heating chamber is not hindered by the shutter.

Advantages of the Invention

[0020] According to one aspect of the present invention, it is possible to realize a tube heating device and a tube heating method capable of efficiently heating the entire body including the inner surface of the tube.

Brief Description of the Drawings

[0021] [Figure 1] It is an external perspective view of a tube heating device according to an embodiment of the present invention. [Figure 2] It is a perspective view showing the internal configuration of the tube heating device of FIG. 1. [Figure 3] It is a front view showing the internal configuration of the tube heating device of FIG. 1. [Figure 4] It is an enlarged perspective view showing the configuration of the wind speed assisting part included in the tube heating device of FIG. 1. [Figure 5] It is a front view for explaining the configuration of the heating chamber included in the tube heating device of FIG. 1. [Figure 6] It is a flowchart of a tube heating method using the tube heating device of FIG. 1. [Figure 7] It is a diagram showing the result of heat distribution simulation in an example based on the tube heating device of FIG. 1.

Modes for Carrying Out the Invention

[0022] 〔Tube Heating Device〕 Figure 1 is a perspective view of a tube heating device 1 according to one embodiment of the present invention. Figure 2 is a perspective view of the tube heating device 1 in Figure 1 with a portion of the side wall removed to expose the internal structure. The tube heating device 1 includes a hot air generating unit 10 and a heating chamber 30, and also includes flow paths 21 and 22 connecting the hot air generating unit 10 and the heating chamber 30. The tube heating device 1 can heat a tube to be heated housed in the heating chamber 30 by blowing hot air onto it.

[0023] Here, the pipe to be heated by the pipe heating device 1 is, for example, a ductile cast iron pipe used as an earthquake-resistant pipe for water supply. In the case of ductile cast iron pipes for water supply, it has traditionally been common to cover the inner surface of the pipe with cement lining, but as mentioned above, the use of powder coating is increasing from the standpoint of chemical stability, durability, and ease of installation. When applying powder coating to the inner surface of a ductile cast iron pipe, the pipe is often heated before coating due to the large heat capacity of the cast iron pipe and the relatively thick target film thickness. When the pipe is heated to about 200°C to 300°C, the powder coating melts and hardens due to the heat, and a predetermined coating film is fixed to the inner surface of the pipe. The pipe heating device of this embodiment is used as a means of heating the pipe to the temperature required for powder coating.

[0024] In this embodiment, as an example of a ductile cast iron pipe, a pipe 500 having a socket 501 and a spigot 502 at both ends of a straight pipe section 503 will be used for explanation. The pipes 500 can be connected to each other, and when connecting them, the spigot 502 of the second pipe is inserted into the socket 501 of the first pipe. An annular groove is formed on the inner circumferential surface of the socket 501 for attaching a locking ring to prevent the pipes 500 from coming apart when connected. In addition, a projection or the like may be formed on the outer circumferential surface of the spigot 502.

[0025] Furthermore, the pipe to be heated is not limited to a pipe 500 having a socket 501 and a spigot 502. For example, it may be a pipe with spigots at both ends. Also, any straight tubular structure is acceptable, and it is possible to target a pipe body that does not have a socket or spigot.

[0026] The pipe heating device 1 shown in Figure 1 is used to perform a step of heating the pipe before coating during the process of powder coating the pipe. Note that this process may include a preheating device to preheat the pipe before the pipe heating step by the pipe heating device 1. Furthermore, a device (soaking furnace) may be provided to perform a soaking step to equalize the heat of the heated pipe after the pipe heating step by the pipe heating device 1. Below, as an example, a configuration in which a pipe preheated by the preheating device is further heated to a higher temperature by the pipe heating device 1 will be described.

[0027] The tube heating device 1 constitutes a furnace, and within the furnace, it includes a hot air generating unit 10 (Figure 2), flow paths 21 and 22, and a heating chamber 30.

[0028] The hot air generating unit 10 (Figure 2) is configured to heat the air inside the furnace. There are various methods for heating the air, but from the viewpoint of ensuring stable finished quality and reducing costs, a combustion-type hot air circulation system using natural gas or the like can be used.

[0029] The hot air generated in the hot air generation unit 10 flows through the upstream channel 21 and is sent into the heating chamber 30 through the inlet for the hot air. After flowing through the heating chamber 30, the hot air flows out through the outlet for the hot air from the heating chamber into the downstream channel 22. This downstream channel 22 is connected to the hot air generation unit 10, and the hot air that returns to the hot air generation unit 10 from the downstream channel 22 is heated again in the hot air generation unit 10. In this way, the hot air circulates within the furnace.

[0030] The heating chamber 30 heats the pipe 500 using the hot air generated in the hot air generating unit 10. The heating chamber 30 includes a space 31 in which the pipe 500 can be positioned such that its axis is parallel to the Y-axis in the three-dimensional coordinate system XYZ shown in Figure 1. This space 31 and the hot air generating unit 10 are separated by a partition wall 34.

[0031] The heating chamber 30 allows the hot air generated by the hot air generating unit 10 to flow in the positive Y-axis direction within the space 31. Therefore, by arranging the pipe 500 in the space 31 so that its axis is parallel to the Y-axis direction, the heating chamber 30 is configured to allow the hot air to flow in the direction of the pipe axis of the pipe 500.

[0032] More specifically, as shown in Figure 2, the heating chamber 30 includes an inlet 32 ​​on the negative Y-axis side of the space 31 and an outlet 33 on the positive Y-axis side. The inlet 32 ​​is the part through which the hot air generated in the hot air generation unit 10 flows into the space 31 via the upstream flow path 21. The outlet 33 is the part through which the hot air that has flowed through the space 31 flows out into the downstream flow path 22. In the space 31, a pipe 500 is arranged between the inlet 32 ​​and the outlet 33 such that its pipe axis is parallel to the Y-axis direction. In this embodiment, the receiving end 501 faces the inlet 32, and the insertion end 502 faces the outlet 33. As a result, the hot air flowing in from the inlet 32 ​​flows from the receiving end 501 side to the insertion end 502 side, including the inside of the pipe 500, in the pipe axis direction (Y-axis direction).

[0033] The heating chamber 30 is located within a transport path in which the pipes 500 are transported in the positive X-axis direction as shown in Figures 1 and 2. Multiple pipes 500 are transported in the positive X-axis direction within this transport path, with their respective pipe axes arranged parallel to the Y-axis direction. This transport path, for example, connects an upstream section where a preheating device is installed and a downstream section where a soaking furnace is installed. The pipe heating device 1 can also be described as including a transport section 40 that transports the pipes 500 within this transport path. The transport section 40 may also be a component of the heating chamber 30.

[0034] The method of transporting the pipe 500 in the transport section 40 is not particularly limited. In one example, as shown in Figure 2, a configuration can be adopted in which there are support parts 41 that support the outer circumference of the pipe 500 at three different locations along the pipe axis of the pipe 500. Each support part 41 is spaced apart from each other along the Y axis.

[0035] Here, the pipe to be heated by the pipe heating device 1 may be a long pipe, for example, 6 meters in length, or a shorter pipe, for example, 4 meters in length. Even pipes of different lengths can be transported smoothly as long as the transport unit 40 is equipped with support parts 41 at multiple locations along the Y-axis. In one example, a long pipe is supported by three support parts 41 as shown in Figure 2. On the other hand, a short pipe is supported by the support part 41 at the negative end of the Y-axis and the adjacent support part 41.

[0036] In the heating chamber 30, the pipes 500 are arranged such that their receiving end 501 is close to the inlet 32, regardless of their length. This allows the pipes 500 to be efficiently heated by the hot air flowing in from the inlet 32.

[0037] Furthermore, the heating chamber 30 has shutters 50 at both the negative X-axis end and the positive X-axis end of the space 31. Note that the shutter 50 on the front side is not shown in Figure 2.

[0038] The shutter 50 is open to open the space 31 when the pipe 500 to be heated is transported to the space 31 in the positive X-axis direction. On the other hand, once the transport of the pipe 500 to the space 31 is complete, the shutter 50 closes the space 31 by closing. While the pipe 500 is being heated by hot air in the space 31 of the heating chamber 30, the space 31 is closed on the sides by the shutter 50, which prevents the hot air from escaping outside the space 31 and contributes to improving the heating efficiency of the pipe 500. Once the heating of the pipe 500 is complete, the shutter 50 opens again and the pipe 500 is discharged from the space 31.

[0039] The opening and closing operation of the shutter 50 is not particularly limited, but in this embodiment, the shutter 50 in the open state may be an opening and closing door that closes when it descends in the negative Z-axis direction and opens when it rises in the positive Z-axis direction.

[0040] In other words, the shutter 50 provided in the heating chamber 30 is closed when the pipe to be heated 500 is being heated in the heating chamber 30, and is open when the pipe to be heated 500 is being transported by passing it through the end of the heating chamber 30. Here, passing it through the end of the heating chamber 30 includes both cases where the pipe to be heated 500 is brought into the heating chamber 30 (space 31) from the outside, and conversely, where the pipe to be heated 500 is brought out from the inside of the heating chamber 30 (space 31) to the outside.

[0041] Here, Figure 3 shows the tube heating device 1 from the negative X-axis direction toward the positive X-axis direction, with the internal structure of the tube heating device 1 visible, similar to Figure 2. As shown in Figure 3, the hot air generating unit 10 is located on the upper side (positive Z-axis side) of the heating chamber 30. The hot air generating unit 10 has a circulation fan 11, which directs the hot air generated by the hot air generating unit 10 to the upstream flow path 21 located below, and down to the heating chamber 30 located on the lower level.

[0042] The hot air, pushed down by the circulation fan 11 through the upstream flow path 21, flows into the space 31 from the inlet 32 ​​of the heating chamber 30. The hot air that has flowed through the space 31 is discharged from the outlet 33 into the downstream flow path 22, and then sent through the downstream flow path 22 to the hot air generating unit 10 on the upper floor where it is heated. In this way, the pipe heating device 1 has a two-tiered configuration with circulating airflow.

[0043] As an example, the circulation fan 11 is installed on the wall on the negative Y-axis side of the hot air generating unit 10, as shown in Figures 2 and 3.

[0044] The heating chamber 30 further includes a wind speed assist unit 35 at the inlet 32 ​​to increase the wind speed. As shown in the enlarged view of Figure 4, the wind speed assist unit 35 can employ an axial fan that draws in ambient air (hot air) at the intake section 35a and exhausts it in the positive Y-axis direction from the exhaust section 35b.

[0045] The wind speed of the hot air exhausted by the wind speed assist unit 35 is faster than the wind speed of the hot air sent to the upstream flow path 21 by the circulation fan 11. The wind speed of the hot air exhausted by the wind speed assist unit 35 can generate a strong wind of approximately 10 m / s or more, as an example. In terms of air volume, the air volume of the hot air exhausted by the wind speed assist unit 35 is approximately 700 m³. 3 It can be set to more than one minute.

[0046] By providing the air velocity assist unit 35 in this manner, the air velocity of the hot air is increased before it flows into the heating chamber 30. This improves the heating efficiency of the heating target tube 500.

[0047] The wind speed and volume of the hot air exhausted by the wind speed assist unit 35 are predetermined according to the diameter and length of the pipe 500. Based on the diameter of the pipe to be heated, the control device 35c shown in Figure 4 adjusts the power of the wind speed assist unit 35, and for example, the fan speed of an axial fan.

[0048] The heating chamber 30 further has a first flap 36 (compression section) at the inlet 32, as shown in Figures 2 and 3. The first flap 36 has the function of narrowing the inlet 32. The first flap 36 is a plate-like structure having a main surface aligned with the XZ plane.

[0049] The first flap 36 is located above the pipe 500 positioned in the space 31, and more specifically above the receiving opening 501. The first flap 36 is fixed to the aforementioned partition wall 34 at its upper edge and is a plate-like body hanging down from its upper edge.

[0050] The first flap 36 compresses the hot air so that, when comparing the cross-sectional areas of the passage path of the hot air, which starts from the inlet 32 ​​and ends at the pipe end of the receiving port 501 of the pipe to be heated, when the path is cut by a plane perpendicular to the direction of travel of the hot air, the cross-sectional area at the ending point is smaller than the cross-sectional area at the starting point, and guides the hot air to the pipe end of the receiving port 501 of the pipe to be heated.

[0051] The presence of the first flap 36 allows hot air to be effectively blown onto both the inner and outer surfaces of the heating target tube 500, thereby improving heating efficiency.

[0052] Here, the first flap 36 is a plate that can rotate around its upper edge, which is fixed to the partition wall 34. The direction of rotation is indicated by an arrow in Figure 5. As the first flap 36 rotates in this manner, the distance between its lower edge and the conveying section 40 increases. This is advantageous for heating pipes 500 of different diameters.

[0053] For example, the diameter of pipe 500 shown in Figure 5 is larger than the diameters of the pipes shown in Figures 1 to 4. In this way, a pipe 500 with a larger diameter can be used as the heating target, and even in this case, the height of the lower edges of the flaps 36 and 37 can be adjusted, so that hot air can be effectively delivered to the inside and around the outer circumference of pipe 500. Thus, the height of the lower edge of the first flap 36 is adjustable according to the pipe diameter. By adjusting the height of the lower edge of the first flap 36, regardless of the pipe diameter, the hot air can be compressed and guided to the end of the receiving port 501 of the heating target pipe 500, as described above.

[0054] Furthermore, the heating chamber 30 has a second flap 37 at the outlet 33. The second flap 37 has the function of narrowing the outlet 33. The second flap 37 is a plate-like structure having a main surface aligned with the XZ plane.

[0055] The second flap 37 is located above the pipe 500 positioned in the space 31, and more specifically above the insertion opening 502. The second flap 37 is fixed to the aforementioned partition wall 34 at its upper edge and is a plate-like body hanging down from its upper edge.

[0056] Furthermore, the second flap 37, like the first flap 36, is a plate that can rotate around a fixed upper edge. The direction of rotation is indicated by an arrow in Figure 5. In short, the first flap 36 and the second flap 37 can rotate in the direction in which their respective lower edges move closer together.

[0057] As the second flap 37 rotates in the direction indicated by the arrow in Figure 5, the distance between its lower edge and the conveying section 40 increases. Similar to the first flap 36, this configuration allows for heating of pipes 500 with different diameters.

[0058] By providing the first flap 36 and the second flap 37 in this manner, the hot air sent from the inlet 32 ​​into the space 31 can be blown onto the pipe 500, thereby efficiently heating the pipe 500.

[0059] It should be noted that the configuration that allows hot air to be blown in this manner is not limited to the form of the first flap 36 and the second flap 37. For example, the partition wall 34 itself may be configured to be movable in the vertical direction. In this case, the flap may not be necessary, or if it is present, it may be a fixed, non-rotating hanging wall. In this case, the partition wall may move in the vertical direction (Z-axis direction) according to the diameter of the pipe 500 so as to face the pipe 500 at an appropriate distance from it.

[0060] In this embodiment, the length of the space 31 along the Y-axis is the same as the length of the pipe 500, or slightly longer. The space 31 also has a length along the X-axis that is sufficient to accommodate three pipes 500 from the group of pipes transported by the transport unit 40. Thus, the space 31 can accommodate multiple pipes 500, and in this configuration, hot air is blown onto only one of the multiple pipes 500 accommodated. More specifically, for the pipe 500 located at the uppermost part of the transport path among the three pipes 500 accommodated in the space 31, the inlet 32 ​​is close to the receiving end, and the outlet 33 is close to the insertion end. While that one pipe 500 is being heated, the two pipes 500 located downstream are kept warm within the space 31, and the heating becomes more uniform.

[0061] Furthermore, a soaking furnace may be provided downstream of the tube heating device in this embodiment.

[0062] With the configuration of the tube heating device 1 described above, the hot air emitted from the hot air generator is forcibly circulated over all surfaces of the tube, both the inner and outer surfaces, allowing for efficient and even heating in a shorter heating time compared to conventional tube heating devices.

[0063] [Pipe heating method] Figure 6 shows the processing flow of the pipe heating method of this embodiment. The pipe heating method S1 of this embodiment includes a transport step S11 and a heating step S12.

[0064] The transport step S11 is the step of transporting the pipe to the pipe heating device 1. Note that, prior to step S11, there may be a step of preheating the pipe in a device different from the pipe heating device.

[0065] The transport step S11 is performed by the support portion 41 of the transport unit 40, and for example, the pipe 500 is transported in the positive X-axis direction as shown in Figure 2, and the three pipes 500 are housed in the space 31 of the heating chamber 30.

[0066] The heating step S12 is a step that follows the conveying step S11, in which hot air is blown in the direction of the pipe axis of the pipe 500 to heat the pipe 500. When the conveying step S11 is completed or when the heating step S12 is started, the shutter 50 closes the space 31.

[0067] In the heating step S12, the hot air generated in the hot air generating unit 10 shown in Figure 2, etc., is sent into the space 31 of the heating chamber 30 by the circulation fan 11 and the air velocity assist unit 35, and flows through the space 31 in the positive direction of the Y axis. As a result, hot air flows inside the pipe 500 and also flows around the outer circumference of the pipe 500, allowing the pipe 500 to be heated rapidly.

[0068] Furthermore, in heating step S12, a relatively high-speed hot air is flowed into the inside of the pipe 500 in the positive Y-axis direction by the air velocity assist unit 35 at the inlet 32. As a result, the pipe 500 is efficiently heated from the inside.

[0069] Furthermore, in heating step S12, the hot air is rectified by the first flap 36, and hot air is blown into the inside of the tube 500 and the outer circumference of the tube 500. This allows the tube to be heated efficiently from both the inside and the outer circumference.

[0070] In this manner, the circulation fan 11 circulates the hot air generated in the hot air generation unit 10 between the hot air generation unit 10 and the heating chamber 30, and the air velocity assist unit 35 and flaps 36 and 37 blow the hot air onto the pipe 500, thereby ensuring a large surface area of ​​the pipe that is exposed to the hot air. As a result, the heating efficiency of the pipe by the generated hot air can be increased compared to a configuration without such a setup. In other words, the pipe can be heated to the desired temperature even with a small amount of heat, contributing to energy savings required for pipe heating.

[0071] Furthermore, the system includes an opening / closing control step that controls the opening and closing of the aforementioned shutter 50 provided at the end of the heating chamber 30 when the pipe to be heated is being heated in the heating chamber 30, or when the pipe to be heated is being transported by passing it through the end of the heating chamber 30. This has the effect of retaining the hot air in the space 31, thereby contributing to an improvement in the heating efficiency of the pipe 500.

[0072] The heating step S12 is performed by controlling the circulation fan 11 and the air velocity assist unit 35 with a control device so that hot air at a predetermined temperature can be circulated in the space 31 at a predetermined air volume and predetermined air velocity within a certain period of time. A control device (not shown) may also be connected to the circulation fan 11. The control device 35c that controls the air velocity assist unit 35 is shown in Figure 4. The control by these control devices is preset based on the length and diameter of the pipe 500.

[0073] Furthermore, the circulating fan 11 and the air velocity assist unit 35 (axial flow fan) may be configured to continue rotating even when the heating step S12 is not being performed, i.e., during the conveying step S11, and to reduce the fan speed.

[0074] The opening and closing of the shutter 50, the transport speed of the pipe 500 by the transport unit 40, and the control of the drive power of the circulation fan 11 and the wind speed assist unit 35 are all performed according to pre-programmed timings.

[0075] The transport unit 40 transports the pipes 500 by simultaneously removing one of the three pipes 500 housed in the space 31 (the downstream pipe) and introducing a new pipe 500 into the space 31 from the upstream side in the transport direction. The heating step S12 is performed on this new pipe 500. During the heating step S12, the transport of pipes 500 is stopped.

[0076] As described above, according to the pipe heating method of this embodiment, in the heating step, hot air is blown onto the pipe to be heated along the pipe axis direction, so that the hot air hits both the inner and outer surfaces of the pipe, and the entire pipe to be heated can be heated efficiently.

[0077] [Variation 1] In the above-described embodiment, hot air is supplied only from the receiving end 501 side, which is one end of the pipe 500, but the present invention is not limited thereto. That is, in addition to the receiving end 501 side, which is one end of the pipe 500, hot air may also be supplied from the insertion end 502 side.

[0078] In this configuration where hot air is supplied from both ends of the pipe 500, the hot air may be supplied simultaneously. However, for example, hot air may be supplied first only from the receiving end 501, and then in the next stage, the hot air supply from the receiving end 501 may be stopped or the airflow velocity reduced and hot air supplied from the insertion end 502.

[0079] By heating from both ends of the pipe in this way, the entire pipe 500 can be heated more efficiently.

[0080] Furthermore, when heating is performed from both ends of the pipe in this manner, the airflow rate of the hot air sent from the receiving port 501 side may be set to be greater than the airflow rate of the hot air sent from the insertion port 502 side. The airflow rate can be adjusted by the rotation speed of the axial flow fan, etc.

[0081] [Variation 2] In the embodiments described above, a configuration was described in which the heights of the inlet 32 ​​and outlet 33 of the space 31 are varied, and as an alternative, a configuration was described in which the partition wall 34 itself is movable in the vertical direction. However, the configuration is not limited to such a configuration in which the width of the space 31 in the vertical direction is varied. For example, to accommodate a pipe 500 with a short length, the outer wall of the furnace of the pipe heating device 1 located on the insertion end 502 side of the pipe 500, as shown in Figure 2, may be configured to move in the negative direction of the Y axis.

[0082] [Example 3] In the above-described embodiment, hot air is supplied to only the upstream of the three pipes 500 housed in the space 31. However, by widening the size of the inlet 32 ​​and outlet 33 and arranging multiple wind speed assist units 35 (axial fans) in parallel in the X-axis direction, hot air can be supplied simultaneously to two or more pipes 500 housed in the space 31.

[0083] [Variation 4] In the above-described embodiment, the heating chamber 30 is located at a lower level than the hot air generating unit 10. With this positional relationship, heat can be efficiently transferred to the tubes by circulating the hot air within the furnace using a fan. However, the positional relationship between the heating chamber 30 and the hot air generating unit 10 is not limited to this. The heating chamber 30 may be located at a higher level than the hot air generating unit 10, or they may be positioned horizontally side by side.

[0084] Furthermore, in the embodiments described above, the combustion-type hot air generator 15 (for example, a burner) provided in the hot air generating unit 10 is installed on the left side wall of the paper in Figures 2 and 3. However, it is not limited to this installation position. For example, the hot air generator may be installed on the upper side of the paper in Figures 2 and 3, that is, on the ceiling portion inside the furnace, or it may be installed on the bottom surface that constitutes the space of the hot air generating unit 10.

[0085] As described above, according to one aspect of the present invention, the tube to be heated can be heated efficiently. Such effects contribute, for example, to achieving Sustainable Development Goal 13, "Take urgent action to combat climate change," as advocated by the United Nations.

[0086] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Examples]

[0087] An embodiment of the present invention will be described below. In this embodiment, the pipe heating device used is the one with the configuration shown in Figures 1 to 4. In the pipe heating device, a cast iron pipe with a length of 6 m (pipe diameter 800 mm) was arranged as shown in Figure 3 and heated. The hot air generated in the hot air generation unit 10 was flowed into the upstream flow path 21 using a circulation fan 11, and the hot air was sent into the heating chamber 30 using an axial flow fan (wind speed assist unit 35) at the inlet 32.

[0088] Figure 7 shows the results of a simulation using a simulation device to analyze the heat distribution based on wind speed analysis, as hot air was introduced into the heating chamber.

[0089] As shown in Figure 7, the furnace temperature of the tube heating device 1 is uniform, indicating no heat unevenness within the furnace. Furthermore, it was confirmed that hot air was flowing in the axial direction of the heated tube 500, and in particular, it was shown that the hot air was effectively supplied into the interior of the tube 500 from the inlet 32. Similar heat distribution can be obtained even when the hot air velocity is changed in the same tube heating device (data not shown).

[0090] Thus, the tube heating device of this embodiment has high heating efficiency, and can be said to have higher thermal efficiency compared to a comparative configuration in which hot air is blown radially onto the outer surface of the tube to heat it. [Explanation of symbols]

[0091] 1 Tube heating device 10 Hot air generating unit 11 Circulation fan 15. Hot air generator 21 Upstream channel (channel) 22 Downstream channel (channel) 30 Heating chamber 31 Space section 32 Inlet 33 Outlet 34 Bulkhead 35 Wind speed auxiliary part 35a Intake section 35b Exhaust section 35c control unit 36. First flap (compression section) 37. Second flap 40 Conveying section 50 shutters 500 heating target tubes 501 socket 503 Straight pipe section

Claims

1. A pipe heating device for heating pipes, A hot air generating unit that generates hot air, A flow path for guiding the hot air generated in the hot air generating unit to the heating chamber, It comprises a heating chamber connected to the aforementioned flow path and housing the pipe to be heated, A pipe heating device in which the flow path is configured to direct the hot air generated in the hot air generating unit along the axial direction of the pipe to be heated, which is housed in the heating chamber.

2. The pipe heating apparatus according to claim 1, wherein a wind speed assist unit for increasing the wind speed of the hot air is provided in the flow path at the inlet to the heating chamber for the hot air.

3. The pipe heating apparatus according to claim 1, wherein a compression section is provided in the heating chamber to compress the hot air and guide it to the end of the pipe to be heated, such that when the passage path of the hot air, which starts from the inlet to the heating chamber for the hot air and ends at the end of the pipe to be heated, is cut by a plane perpendicular to the direction of travel of the hot air, the cross-sectional areas at the starting point and the ending point are compared, the cross-sectional area at the ending point is smaller than the cross-sectional area at the starting point.

4. The pipe heating apparatus according to claim 1, wherein a conveying unit for conveying the pipe to be heated is provided in the heating chamber.

5. The pipe heating apparatus according to claim 1, wherein a shutter is provided in the heating chamber that is closed when the pipe to be heated is being heated in the heating chamber, and opens when the pipe to be heated is being transported by passing it through the end of the heating chamber.

6. A method for heating a pipe, A transport step in which the tube to be heated is transported into the heating chamber, A pipe heating method comprising: a heating step of heating the pipe to be heated by flowing hot air into the heating chamber along the pipe axis direction of the pipe to be heated.

7. The pipe heating method according to claim 6, further comprising an opening / closing control step for controlling the opening and closing of a shutter provided at the end of the heating chamber when the pipe to be heated is being heated in the heating chamber, or when the pipe to be heated is being transported by passing it through the end of the heating chamber.

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