JP7551462B2 - Manufacturing method of spiral tube - Google Patents

Description

The technology disclosed in this specification relates to a method for manufacturing a spiral tube.

Heat exchange cycles (also called refrigeration cycles) in automotive air conditioners and the like are equipped with a condenser, evaporator, compressor, and expansion valve, and it has been proposed to improve heat exchange performance by placing a double pipe in the circulation path connecting these devices, for freon, _CO2 , and ammonia, and flowing a high-temperature refrigerant coming from the condenser and a low-temperature refrigerant coming from the evaporator in opposite directions in the two-layer space formed by the double pipe to exchange heat (see Patent Documents 1 and 2).

Such a double pipe is constructed by using an inner pipe as a helical pipe having a helical uneven portion in which the uneven shape is displaced in a helical manner in the longitudinal direction, and attaching an outer pipe having a circular cross section to the outer periphery of the inner pipe. The inner pipe needs to be molded to give the helical uneven portion to the circular cross section of the circular pipe. A conventional molding method for a helical pipe having a helical uneven portion is described in, for example, Patent Document 3.

JP 2002-318015 A JP 2006-162241 A Patent No. 4628858

The method described in Patent Document 3 uses a straight tube cut into short lengths as a base tube, and processes a helical uneven portion in the center while holding both ends. This method not only has limitations on the length of tube that can be processed, but also leaves room for improvement in manufacturing efficiency, as the base tubes must be set into the equipment one by one.

The technology described in this specification was developed in light of this background, and aims to provide a method for manufacturing helical tubes with improved manufacturing efficiency.

(1) The method for manufacturing a helical tube according to the technology disclosed in this specification is a method for manufacturing a helical tube having a helical uneven portion in which the uneven shape is displaced helically in the longitudinal direction, and includes the steps of continuously supplying a base tube having a circular cross section, pressing a pressing portion against the outer circumferential surface of the base tube while rotating the pressing portion in the circumferential direction around the base tube to form the helical uneven portion in the base tube, and performing the steps intermittently in the longitudinal direction of the base tube to provide the helical uneven portion and a circular tube portion having a circular cross section alternately in the longitudinal direction, and cutting the base tube at the position of the circular tube portion.

(2) In addition to the above (1), the manufacturing method of the spiral tube further includes a step of forming a dummy spiral uneven portion in the blank tube, the uneven shape of which is displaced spirally in the longitudinal direction, on the blank tube by pressing the pressing portion against the outer peripheral surface of the blank tube at a position spaced from one end of the blank tube while rotating the pressing portion in a circumferential direction around the blank tube, and then setting the step of forming the spiral uneven portion to be started at a position spaced from the one end side of the blank tube relative to the dummy spiral uneven portion, thereby providing the circular tube portion on the opposite side of the one end side of the dummy spiral uneven portion, and cutting the blank tube at the position of the circular tube portion to extract a dummy spiral tube having the dummy spiral uneven portion.

(3) In addition to the above (2), the manufacturing method for the spiral tube further includes forming the dummy spiral uneven portion on the base tube, the dummy spiral uneven portion being shorter than the spiral uneven portion.

(4) In addition to any one of (1) to (3), the manufacturing method of the spiral tube further includes the steps of: starting to press the pressing portion against the outer peripheral surface of the raw tube; relatively displacing the raw tube and the pressing portion in a first direction along the longitudinal direction of the raw tube; and rotating the pressing portion in a first rotational direction along the circumferential direction of the raw tube, thereby forming a part of the spiral uneven portion on the raw tube; then relatively displacing the raw tube and the pressing portion in a second direction opposite to the first direction; and rotating the pressing portion in a second rotational direction opposite to the first rotational direction, thereby causing the pressing portion to trace a part of the spiral uneven portion; and then continuing to relatively displace the raw tube and the pressing portion in the second direction; and continuing to rotate the pressing portion in the second rotational direction, thereby forming the remaining part of the spiral uneven portion on the raw tube.

(5) In addition to any one of (1) to (4), the method for manufacturing the spiral tube further includes a step of forming the spiral uneven portion on the raw tube by rotating the pressing part circumferentially around the raw tube while conveying the raw tube from upstream to downstream along its longitudinal direction by a conveying device, and then measuring the length of the portion of the raw tube including the spiral uneven portion and the circular tube portion by a measuring device arranged downstream of the conveying device in the longitudinal direction of the raw tube, and cutting the raw tube at a position of the circular tube portion based on the measurement result by the measuring device.

(6) In addition to any one of (1) to (5), the method for manufacturing the spiral tube further includes forming the nth spiral uneven portion on the base tube, and then cutting the base tube at the circular tube portion that is located between the nth spiral uneven portion and the (n+1)th spiral uneven portion after starting to form the (n+1)th spiral uneven portion.

The technology described in this specification can provide a method for manufacturing a spiral tube with improved manufacturing efficiency.

1 is a side view of an aluminum alloy spiral tube according to a first embodiment. FIG. 1 is a side view showing a schematic configuration of a manufacturing apparatus according to a first embodiment; FIG. 1 is a side view showing a configuration of a manufacturing apparatus according to a first embodiment, illustrating a state before a raw pipe is subjected to a forming process. FIG. 1 is a front view of a molding device according to a first embodiment; FIG. 1 is a side view showing a state in the middle of forming a dummy spiral concave-convex portion on a blank tube using the manufacturing apparatus according to embodiment 1. FIG. 1 is a side view showing an operation of cutting a blank tube and extracting a dummy helical tube using the manufacturing apparatus according to the first embodiment. FIG. 1 is a side view showing a state in the middle of forming a first helical concave-convex portion on a blank tube using the manufacturing apparatus according to the first embodiment; FIG. 1 is a side view showing a state in which a first helical concave-convex portion is formed on a blank tube using the manufacturing apparatus according to the first embodiment and then a second helical concave-convex portion is started to be formed on the blank tube. FIG. 1 is a side view showing an operation of cutting a blank tube using the manufacturing apparatus according to the first embodiment to extract an aluminum alloy helical tube on which a first helical concave-convex portion is formed. FIG. 11 is a side view showing a state in which a first spiral concave-convex portion is beginning to be formed on a blank tube using the manufacturing apparatus according to embodiment 2. FIG. 11 is a side view showing a state in which the conveying direction of the blank tube and the rotation direction of the pressing unit are started to be reversed after a part of the first helical concave-convex portion is formed on the blank tube using the manufacturing apparatus according to the second embodiment. FIG. 11 is a side view showing a state in which a part of the first spiral concave-convex portion is traced by a pressing portion using the manufacturing device according to the second embodiment. FIG. 11 is a side view showing an operation of cutting a blank tube using the manufacturing apparatus according to the second embodiment to extract an aluminum alloy helical tube on which a first helical concave-convex portion is formed.

<Embodiment 1>
A first embodiment will be described with reference to Figures 1 to 9. In this first embodiment, a method for manufacturing an aluminum alloy helical tube (helical tube) 20 will be described.

1 is a side view of an aluminum alloy spiral tube 20. The aluminum alloy spiral tube 20 has a spiral uneven portion 21 in which the uneven shape is displaced in a spiral shape in the longitudinal direction (axial direction) of the aluminum alloy spiral tube 20. The spiral uneven portion 21 has concave portions 21A and convex portions 21B arranged alternately in the circumferential direction on the outer circumferential surface of the aluminum alloy spiral tube 20, and these concave portions 21A and convex portions 21B are configured to displace in the longitudinal direction while rotating around the axis of the aluminum alloy spiral tube 20. The spiral uneven portion 21 includes a plurality of such concave portions 21A and convex portions 21B (for example, about 3 to 10 pairs), and FIG. 1 illustrates the case of three pairs. The spiral uneven portion 21 is provided in the central portion of the aluminum alloy spiral tube 20 in the longitudinal direction. At both end portions of the aluminum alloy spiral tube 20 in the longitudinal direction, circular tube portions 22 having a circular cross section are provided. An aluminum alloy spiral tube 20 configured in this manner can be used, for example, as the inner tube of a heat transfer double tube.

Figure 2 is a side view showing the schematic configuration of a manufacturing apparatus 30 used to manufacture the aluminum alloy spiral tube 20 having the above-mentioned configuration. When manufacturing the aluminum alloy spiral tube 20 using the manufacturing apparatus 30 shown in Figure 2, a long blank tube 10 is used. The blank tube 10 is a tube material with a circular cross section that extends almost straight along the longitudinal direction, and can be made of, for example, 1000 series, 3000 series, 5000 series, or other aluminum alloys. In terms of cost, it is preferable to use an extruded material that has not been subjected to drawing processing as the state of the blank tube 10. The size of the blank tube 10 can be, for example, an outer diameter of 10 to 30 mmφ and a wall thickness of 0.5 to 2.0 mm. The size of the blank tube 10 may be outside the above-mentioned numerical ranges.

The blank tube 10 as described above is continuously supplied to the manufacturing apparatus 30 shown in FIG. 2. When supplying the blank tube 10, for example, the blank tube 10 extruded from an extruder can be continuously supplied as is, or a coiled material wound into a coil can be used. The former allows the most efficient manufacturing by, for example, using a manufacturing line configuration directly connected to the outlet side of the extruder. On the other hand, the latter makes it easy to perform stable continuous unwinding by, for example, using a configuration in which the blank tube 10 is unwound from a level wound coil set in an uncoiler.

As shown in FIG. 2, the manufacturing apparatus 30 includes at least conveying devices 31 and 32 for conveying the blank tube 10, a forming device 33 for forming the blank tube 10 being conveyed, and a cutting device 34 for cutting the formed blank tube 10. The conveying devices 31 and 32 convey the blank tube 10 along its longitudinal direction (the left-right direction in FIG. 2), and in this embodiment, the blank tube 10 can be continuously conveyed from the upstream side (the right side in FIG. 2) to the downstream side (the left side in FIG. 2). The conveying devices 31 and 32 are arranged so as to sandwich the forming device 33 from the upstream side and the downstream side in the longitudinal direction of the blank tube 10, and the one located upstream of the forming device 33 is referred to as the upstream conveying device 31, and the one located downstream of the forming device 33 is referred to as the downstream conveying device 32. The forming device 33 is interposed between the upstream conveying device 31 and the downstream conveying device 32 in the longitudinal direction of the blank tube 10, and forms the spiral uneven portion 21 on the portion of the blank tube 10 that is sandwiched between the upstream conveying device 31 and the downstream conveying device 32. The cutting device 34 is disposed downstream of the downstream conveying device 32 in the longitudinal direction of the blank tube 10, and cuts the portion of the blank tube 10 that has passed through the forming device 33 and is disposed downstream of the downstream conveying device 32.

Figure 3 is a side view showing the configuration of the manufacturing device 30, showing the state before the blank tube 10 is molded. As shown in Figure 3, the conveying devices 31 and 32 each have a pair of upper and lower caterpillars 31A and 32A. The blank tube 10 is sandwiched between the upper and lower caterpillars 31A and 32A, and the blank tube 10 is conveyed from the upstream side to the downstream side as the upper and lower caterpillars 31A and 32A rotate. In detail, each caterpillar 31A and 32A has, for example, a pair of rotatable rollers and a belt stretched across the pair of rollers. As each roller of each caterpillar 31A and 32A rotates around its axis, the belt rotates, and the blank tube 10 in contact with the rotating belt is conveyed from the upstream side to the downstream side along its own longitudinal direction. The conveying devices 31 and 32 have the function of moving the blank tube 10 in the axial direction inside the forming device 33 while applying an appropriate tension to the blank tube 10, and also have a holding force that resists the torsional moment acting in the axial direction of the blank tube 10 when pressed by the pressing part 33A of the forming device 33 described below, and also have the function of suppressing flattening of the blank tube 10 before and after forming. The downstream conveying device 32 may be omitted or may be composed of a driven roller.

As shown in FIG. 3, the molding device 33 includes a pressing unit 33A capable of pressing the outer circumferential surface of the blank tube 10 to form the helical uneven portion 21. The pressing unit 33A will be described with reference to FIG. 4. FIG. 4 is a front view of the molding device 33. As shown in FIG. 4, the molding device 33 is configured to rotate the pressing units 33A in the circumferential direction around the blank tube 10 while pressing the pressing units 33A against the outer circumferential surface of the blank tube 10. More specifically, the molding device 33 has a plurality of pressing units 33A arranged with gaps in the circumferential direction facing the outer circumferential surface of the blank tube 10, and a block 33B to which the pressing units 33A are attached. The pressing unit 33A is made of a bolt and has a pressing surface 33A1 at the tip of its shaft. The block 33B is disk-shaped, and a blank tube insertion hole 33B1 through which the blank tube 10 is inserted is formed at its center. The blank pipe insertion hole 33B1 is coaxial with the central axis C of the blank pipe 10. The block 33B has a plurality of pressing part attachment holes 33B2 that extend radially from the blank pipe insertion hole 33B1 and penetrate inward and outward. A plurality of pressing parts 33A are attached to the pressing part attachment holes 33B2 by being fastened from the outside. The pressing parts 33A attached to the pressing part attachment holes 33B2 are capable of having their tips advance into the blank pipe insertion hole 33B1. The outer peripheral surface of the blank pipe 10 is pressed by the pressing surface 33A1 of the pressing part 33A that advances into the blank pipe insertion hole 33B1.

The pressing portion 33A is configured to be rotatable together with the block 33B in the circumferential direction (around the central axis C) of the block 33B and the blank tube 10 by the driving force of the drive unit. The number of pressing portions 33A can be selected according to the desired shape of the helical uneven portion, but is usually selected from a range of about 3 to 10. In this embodiment, the number of pressing portions 33A is illustrated as a representative example. The multiple pressing portions 33A are radially advanced and retreated according to the amount of tightening in each pressing portion mounting hole 33B2 of the block 33B, and the amount of advancement of the tip of the shaft portion into the blank tube insertion hole 33B1, i.e., the amount of pressing (pressing depth) against the blank tube 10, is adjustable. Specifically, when each pressing part 33A advances toward the center of the blank tube 10 in the radial direction of the blank tube 10, the amount of pressure applied to the blank tube 10 increases, whereas when each pressing part 33A retreats away from the center of the blank tube 10 in the radial direction of the blank tube 10, the amount of pressure applied to the blank tube 10 decreases. Note that the adjustment of the tightening amount of each pressing part 33A can be automated or may be manual.

As shown in FIG. 3, the cutting device 34 cuts the part of the blank tube 10 located downstream of the downstream conveying device 32. The part of the blank tube 10 located downstream of the downstream conveying device 32 includes a part (formed part) that has been formed by the forming device 33 and a part (non-formed part) that has not been formed by the forming device 33, but the cutting position of the blank tube 10 by the cutting device 34 is the non-formed part upstream of the formed part, which is the circular tube part 22. In other words, the circular tube part 22 is composed of the non-formed part of the blank tube 10. When the non-formed part of the blank tube 10 is cut by the cutting device 34 in this way, an aluminum alloy spiral tube 20 including the circular tube part 22 and the spiral uneven part 21 (formed part) formed by the forming device 33 is taken out. For example, a rotary cutter can be used as the cutting device 34.

In addition to the above-mentioned conveying devices 31 and 32, forming device 33, and cutting device 34, the manufacturing apparatus 30 is equipped with a conveying measuring device 35 that measures the length of the blank tube 10. As shown in FIG. 3, the conveying measuring device 35 is arranged at a position downstream of the upstream conveying device 31 and upstream of the forming device 33 in the longitudinal direction of the blank tube 10 (a position interposed between the upstream conveying device 31 and the forming device 33). The conveying measuring device 35 can measure the length of the blank tube 10 that has passed through the upstream conveying device 31. The measurement result by this conveying measuring device 35 is fed back to the conveying control of the blank tube 10 by each conveying device 31 and 32. For example, a measuring roll can be used as the conveying measuring device 35. Furthermore, the manufacturing apparatus 30 is equipped with cutting measuring devices 36 to 38 that measure the length of the blank tube 10 that has passed through the cutting device 34. The cutting measuring devices 36-38 are all disposed downstream of the cutting device 34 in the longitudinal direction of the mother tube 10, and by detecting the position of the downstream end of the mother tube 10, the length of the mother tube 10 from the downstream end of the mother tube 10 to the cutting device 34 can be measured. The cutting measuring devices 36-38 include a downstream cutting measuring device (mass production cutting measuring device) 36 located at the most downstream side in the longitudinal direction of the mother tube 10, an upstream cutting measuring device (circular pipe portion adjustment cutting measuring device) 37 located at the most upstream side in the longitudinal direction of the mother tube 10, and an intermediate cutting measuring device (dummy cutting measuring device) 38 located midway between the downstream cutting measuring device 36 and the upstream cutting measuring device 37 in the longitudinal direction of the mother tube 10. Therefore, the distance from the cutting device 34 to the downstream measuring device 36 for cutting is the longest, the distance from the cutting device 34 to the upstream measuring device 37 for cutting is the shortest, and the distance from the cutting device 34 to the intermediate measuring device 38 for cutting is approximately intermediate. The measurement results (detection results) by these measuring devices for cutting 36-38 are fed back to the cutting device 34. That is, the timing at which the blank tube 10 is cut by the cutting device 34 is set to be synchronized with the timing at which the measuring devices for cutting 36-38 detect the positions of the downstream end of the blank tube 10, so that three different lengths of tube can be taken out when the blank tube 10 is cut. Specifically, the length of the tube (aluminum alloy spiral tube 20) taken out when the blank tube 10 is cut by the cutting device 34 based on the detection by the downstream measuring device 36 for cutting is the longest. The length of the tube taken out when the blank tube 10 is cut by the cutting device 34 based on the detection by the upstream measuring device 37 for cutting is the shortest. Based on the detection by the intermediate cut measuring device 38, the length of the tube (the dummy spiral tube 20D described below) that is taken out when the raw tube 10 is cut by the cutting device 34 is set to approximately the middle. For example, a photo sensor or the like can be used as the cutting measuring devices 36 to 38.

The aluminum alloy spiral tube 20 and the manufacturing device 30 according to the present embodiment are constructed as described above. Next, the manufacturing method of the aluminum alloy spiral tube 20 will be described with reference to FIG. 3, FIG. 5 to FIG. 9. In the manufacturing method of the aluminum alloy spiral tube 20 according to the present embodiment, the raw tube 10 is continuously supplied with a molding process to form the spiral uneven portion 21, and the length of the raw tube 10 on which the spiral uneven portion 21 is formed is continuously measured. The raw tube 10 on which the spiral uneven portion 21 is formed is then continuously cut to manufacture the aluminum alloy spiral tubes 20 one after another. In addition, in the manufacturing method of the aluminum alloy spiral tube 20 according to the present embodiment, the dummy spiral tube 20D is manufactured prior to the continuous manufacturing of the aluminum alloy spiral tube 20 as described above, and the condition of the manufactured dummy spiral tube 20D is checked to optimize the various conditions for manufacturing the aluminum alloy spiral tube 20. The manufacturing method of the aluminum alloy spiral tube 20 will be described in detail below.

First, the manufacture of the dummy spiral tube 20D will be described. As shown in FIG. 3, when one end 10A of the supplied blank tube 10 reaches the downstream conveying device 32 after passing through the upstream conveying device 31 and the forming device 33, the multiple pressing parts 33A provided in the forming device 33 are advanced in the radial direction of the blank tube 10 so as to approach the center of the blank tube 10, and the multiple pressing parts 33A are abutted against the outer circumferential surface of the blank tube 10 at a position spaced apart from the one end 10A. Then, the blank tube 10 is conveyed downstream along its longitudinal direction by the conveying devices 31 and 32 to displace the blank tube 10 relative to the forming device 33, and the multiple pressing parts 33A are rotated in the circumferential direction around the blank tube 10 while pressing the multiple pressing parts 33A against the outer circumferential surface of the blank tube 10, thereby forming a dummy spiral uneven portion 21D on the blank tube 10 as shown in FIG. 5 (dummy forming process). FIG. 5 is a side view showing a state in the middle of forming the dummy spiral uneven portion 21D on the mother tube 10. The dummy spiral uneven portion 21D has an uneven shape that is displaced in a spiral shape in the longitudinal direction of the mother tube 10, similar to the spiral uneven portion 21. The multiple pressing portions 33A are retracted away from the center of the mother tube 10 in the radial direction of the mother tube 10 at a predetermined timing and separated from the outer circumferential surface of the mother tube 10, thereby stopping the formation of the dummy spiral uneven portion 21D. The timing for stopping the formation of the dummy spiral uneven portion 21D is set based on, for example, the elapsed time from the start of the formation of the dummy spiral uneven portion 21D so that the dummy spiral uneven portion 21D is shorter than the spiral uneven portion 21.

Then, when one end 10A (the downstream end) of the blank tube 10 reaches the intermediate cut measuring device 38, it is detected by the intermediate cut measuring device 38, as shown in FIG. 6, and the length from the one end 10A of the blank tube 10 to the cutting device 34 is measured. Based on the measurement results by the intermediate cut measuring device 38, the blank tube 10 is cut by the cutting device 34 (dummy cutting process). FIG. 6 is a side view showing the work of cutting the blank tube 10 and taking out the dummy spiral tube 20D. The cutting position of the blank tube 10 by the cutting device 34 is the circular tube portion 22 adjacent to the upstream side of the already formed dummy spiral uneven portion 21D. The dummy spiral tube 20D on which the dummy spiral uneven portion 21D is formed as a result of the cutting is taken out. The dummy spiral tube 20D has an overall length shorter than that of the aluminum alloy spiral tube 20, a dummy spiral uneven portion 21D shorter than the spiral uneven portion 21 is provided in the central portion in the longitudinal direction, and a circular tube portion 22 is provided at each of the end portions in the longitudinal direction. The state of the dummy spiral uneven portion 21D in the extracted dummy spiral tube 20D (e.g., the shape of the recessed portion 21A and the protruding portion 21B and the depth of the recessed portion 21A, etc.) is confirmed and various information is extracted. By using this extracted information, various conditions (e.g., the pressing amount of the pressing portion 33A against the outer circumferential surface of the blank tube 10, etc.) during the manufacturing of the aluminum alloy spiral tube 20 can be adjusted and optimized.

After the various conditions for manufacturing the aluminum alloy spiral tube 20 are adjusted, the manufacturing of the aluminum alloy spiral tube 20 is started. The multiple pressing parts 33A of the forming device 33 are advanced in the radial direction of the blank tube 10 so as to approach the center of the blank tube 10, and the multiple pressing parts 33A are abutted against the outer circumferential surface of the blank tube 10 at the portion sandwiched between the upstream conveying device 31 and the downstream conveying device 32. The blank tube 10 is then conveyed downstream along its longitudinal direction by the conveying devices 31 and 32 to displace the blank tube 10 relative to the forming device 33, and the multiple pressing parts 33A are rotated around the blank tube 10 in the circumferential direction while pressing the multiple pressing parts 33A against the outer circumferential surface of the blank tube 10, thereby forming the spiral uneven portion 21 on the blank tube 10 as shown in FIG. 7 (forming process). FIG. 7 is a side view showing a state in the middle of forming the first spiral uneven portion 21 on the blank tube 10. Since this forming process is performed under conditions optimized in advance based on the dummy helical tube 20D, the shape of the recesses 21A and the protrusions 21B in the formed helical irregularity portion 21 and the depth of the recesses 21A are excellent, and the yield rate of the aluminum alloy helical tube 20 is improved. When the downstream end of the blank tube 10 reaches the upstream cutting measuring device 37, it is detected by the upstream cutting measuring device 37 and the length from the downstream end of the blank tube 10 to the cutting device 34 is measured. Based on the measurement result by the upstream cutting measuring device 37, the blank tube 10 is cut by the cutting device 34. The cutting position of the blank tube 10 by the cutting device 34 at this time is set to the circular tube portion 22 adjacent to the downstream side of the first helical irregularity portion 21 being formed. The tube taken out by the cutting is composed of only the non-formed portion (circular tube portion 22) that has not been formed by the forming device 33. As a result, the length of the circular pipe portion 22 adjacent to the downstream side of the first helical uneven portion 21 is adjusted to an appropriate length. After that, the molding of the first helical uneven portion 21 is continued. Then, as shown in FIG. 8, the multiple pressing portions 33A are retracted away from the center of the mother tube 10 in the radial direction of the mother tube 10 at a predetermined timing and separated from the outer circumferential surface of the mother tube 10, thereby stopping the formation of the helical uneven portion 21. The timing for stopping the formation of the helical uneven portion 21 is set based on, for example, the elapsed time from the start of the formation of the helical uneven portion 21 so that the helical uneven portion 21 has a set length. As a result, the helical uneven portion 21 is longer than the dummy helical uneven portion 21D. FIG. 8 is a side view showing a state in which the second helical uneven portion 21 begins to be formed after the first helical uneven portion 21 is formed on the mother tube 10.

When the downstream end of the blank tube 10 on which the first spiral uneven portion 21 is formed reaches the downstream cutting measuring device 36 as shown in FIG. 9, it is detected by the downstream cutting measuring device 36, and the length from the downstream end of the blank tube 10 to the cutting device 34 is measured. Based on the measurement result by the downstream cutting measuring device 36, the blank tube 10 is cut by the cutting device 34. FIG. 9 is a side view showing the work of cutting the blank tube 10 to take out the aluminum alloy spiral tube 20 on which the first spiral uneven portion 21 is formed. Here, when comparing the part of the blank tube 10 between the upstream conveying device 31 and the downstream conveying device 32 and the part located downstream of the downstream conveying device 32, the former may be distorted due to the action of stress accompanying transportation, while the latter is in a state where such stress hardly acts and the distortion is released. Therefore, by using the downstream cutting measuring device 36 to measure the length of the blank tube 10 located downstream of the downstream conveying device 32 and in a distortion-free state as described above, it is possible to obtain highly accurate measurement values that are free from the effects of distortion. In this embodiment, the cut aluminum alloy spiral tube 20 is longer than the dummy spiral tube 20D (cutting process). The cutting position of the blank tube 10 by the cutting device 34 is the circular tube portion 22 adjacent to the upstream side of the formed spiral uneven portion 21. The aluminum alloy spiral tube 20 with the spiral uneven portion 21 formed therein is taken out as a result of the cutting. The taken out aluminum alloy spiral tube 20 has excellent dimensional accuracy in length.

When the aluminum alloy spiral tube 20 manufactured by cutting the blank tube 10 as described above is taken out, the spiral uneven portion 21 of the aluminum alloy spiral tube 20 to be manufactured next is in a state of being partially formed, as shown in FIG. 9. In other words, the outer peripheral surface of the blank tube 10 is pressed by the multiple pressing parts 33A before the blank tube 10 is cut, and the spiral uneven portion 21 of the aluminum alloy spiral tube 20 to be manufactured next has begun to be formed (see FIG. 8). Therefore, the cutting position of the blank tube 10 is the circular tube portion 22 interposed between the previously formed spiral uneven portion 21 and the next spiral uneven portion 21 that is being formed. This can be generalized as follows. That is, when the order of forming the helical uneven portions 21 successively formed on the mother tube 10 is a natural number "n", after the nth helical uneven portion 21 is formed on the mother tube 10, the mother tube 10 is cut at the circular tube portion 22 interposed between the nth helical uneven portion 21 and the (n+1)th helical uneven portion 21 after starting to form the (n+1)th helical uneven portion 21. This improves manufacturing efficiency compared to a case where the mother tube is cut at the circular tube portion to produce a helical tube with the nth helical uneven portion formed thereon, and then the formation of the (n+1)th helical uneven portion is started.

In the manufacturing method of the aluminum alloy spiral tube 20 according to this embodiment, the above-mentioned forming process is performed intermittently in the longitudinal direction of the continuously supplied blank tube 10, so that the blank tube 10 is provided with alternating spiral irregularity sections 21 and circular tube sections 22 in the longitudinal direction. The blank tube 10 is cut at the position of the circular tube section 22 out of the alternating spiral irregularity sections 21 and circular tube sections 22, so that aluminum alloy spiral tubes 20 of a predetermined length are manufactured one after another. As a result, manufacturing efficiency can be significantly improved compared to the case where a pre-cut short blank tube is used.

In addition to the conveying devices 31 and 32, the molding device 33, the cutting device 34, and the measuring devices 35 to 38, the manufacturing device 30 can also incorporate a cleaning device for cleaning the blank tube 10, as necessary.

As described above, the manufacturing method of the aluminum alloy spiral tube (spiral tube) 20 of this embodiment is a method for manufacturing an aluminum alloy spiral tube 20 having a spiral uneven portion 21 whose uneven shape displaces in a spiral shape in the longitudinal direction, and the process of forming the spiral uneven portion 21 on the blank tube 10 by continuously supplying a blank tube 10 having a circular cross section and rotating the pressing portion 33A circumferentially around the blank tube 10 while pressing the pressing portion 33A against the outer circumferential surface of the blank tube 10 is performed intermittently in the longitudinal direction of the blank tube 10, thereby alternately providing the spiral uneven portion 21 and the circular tube portion 22 having a circular cross section in the longitudinal direction, and cutting the blank tube 10 at the position of the circular tube portion 22.

In such a method for manufacturing an aluminum alloy spiral tube 20, a blank tube 10 having a circular cross section is continuously supplied, and is pressed from its outer periphery by a pressing part 33A, which is rotated circumferentially around the blank tube 10 to form a spiral uneven portion 21 in which the uneven shape is displaced in a spiral shape in the longitudinal direction. The process for forming the spiral uneven portion 21 is performed intermittently in the longitudinal direction of the blank tube 10, so that the blank tube 10 is provided with alternating spiral uneven portions 21 and circular tube portions 22 in the longitudinal direction. Then, the blank tube 10 is cut at the position of the circular tube portion 22 among the alternating spiral uneven portions 21 and circular tube portions 22, so that aluminum alloy spiral tubes 20 of a predetermined length are manufactured one after another. As a result, the manufacturing efficiency can be significantly improved compared to the case where a short blank tube cut in advance is used.

In addition, a process is performed in which the pressing portion 33A is pressed against the outer peripheral surface of the mother tube 10 at a position spaced from one end 10A of the mother tube 10 while the pressing portion 33A is rotated circumferentially around the mother tube 10 to form a dummy spiral uneven portion 21D in the mother tube 10, in which the uneven shape is displaced spirally in the longitudinal direction. Then, the process of forming the spiral uneven portion 21 is started at a position spaced from the dummy spiral uneven portion 21D on the mother tube 10 opposite the one end 10A side, thereby providing a circular tube portion 22 on the opposite side from the one end 10A side of the dummy spiral uneven portion 21D, and the mother tube 10 is cut at the position of the circular tube portion 22 to extract a dummy spiral tube 20D having the dummy spiral uneven portion 21D. In such a manufacturing method of the aluminum alloy helical tube 20, a dummy helical uneven portion 21D is formed at a position spaced from one end 10A of the mother tube 10 prior to the formation of the helical uneven portion 21, and the process of forming the helical uneven portion 21 is started at a position spaced from the dummy helical uneven portion 21D on the mother tube 10 on the opposite side to the one end 10A side. Accordingly, a circular tube portion 22 is provided on the mother tube 10 on the opposite side to the one end 10A side of the dummy helical uneven portion 21D, and the mother tube 10 is cut at the position of this circular tube portion 22 to extract the dummy helical tube 20D. By checking the state of the dummy helical uneven portion 21D formed in the extracted dummy helical tube 20D, information necessary for adjusting various conditions, such as the pressing depth of the pressing portion 33A against the outer circumferential surface of the mother tube 10 in the process of forming the helical uneven portion 21, can be obtained. This allows a good spiral irregularity 21 to be formed on the base tube 10, improving the yield rate of the aluminum alloy spiral tube 20.

In addition, in the process of forming the dummy spiral uneven portion 21D on the base tube 10, the dummy spiral uneven portion 21D is formed to be shorter than the spiral uneven portion 21. In this manufacturing method for the aluminum alloy spiral tube 20, the cost required for the dummy spiral tube 20D can be reduced.

In addition, the process of forming the spiral unevenness 21 on the blank tube 10 is performed by rotating the pressing part 33A circumferentially around the blank tube 10 while conveying the blank tube 10 from the upstream side to the downstream side by the conveying devices 31, 32 along its longitudinal direction, and then measuring the length of the part of the blank tube 10 including the spiral unevenness 21 and the circular tube part 22 by the downstream cutting measuring device (measuring device) 36 arranged downstream of the conveying devices 31, 32 in the longitudinal direction of the blank tube 10, and cutting the blank tube 10 at a position of the circular tube part 22 based on the measurement result by the downstream cutting measuring device 36. In such a manufacturing method of the aluminum alloy spiral tube 20, the blank tube 10 may be distorted due to the action of stress accompanying the conveying upstream of the downstream conveying device 32 constituting the conveying devices 31, 32 in the longitudinal direction, whereas the above-mentioned distortion is released downstream of the conveying devices 31, 32 in the longitudinal direction. Therefore, the measurement results obtained by measuring the length of the blank tube 10 using the downstream cutting measuring device 36, which is disposed downstream of the conveying devices 31 and 32 in the longitudinal direction of the blank tube 10, are highly accurate as the effects of distortion are eliminated. And, since the aluminum alloy spiral tube 20 is manufactured by cutting the blank tube 10 at a position in the circular tube portion 22 based on the measurement results by the downstream cutting measuring device 36, the dimensional accuracy of the length of the aluminum alloy spiral tube 20 is excellent.

After forming the n-th helical uneven portion 21 on the base tube 10, the base tube 10 is cut at the circular tube portion 22 that is located between the n-th helical uneven portion 21 and the (n+1)-th helical uneven portion 21 after starting to form the (n+1)-th helical uneven portion 21. In this manufacturing method for the aluminum alloy helical tube 20, the aluminum alloy helical tube 20 on which the n-th helical uneven portion 21 is formed is manufactured after starting to form the (n+1)-th helical uneven portion 21 on the base tube 10. Therefore, compared to the case where the base tube is cut at the circular tube portion to manufacture an aluminum alloy helical tube on which the n-th helical uneven portion is formed, and then the formation of the (n+1)-th helical uneven portion is started, the manufacturing efficiency can be further improved. Note that the above "n" is a natural number, and "n-th" and "(n+1)-th" indicate the order of formation of the helical uneven portion 21 that is formed continuously on the base tube 10.

<Embodiment 2>
A second embodiment will be described with reference to Figures 10 to 13. In this second embodiment, a forming step included in a manufacturing method of an aluminum alloy spiral tube 120 is modified. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, components that appear in the description of this embodiment and have the same names as those of the first embodiment will be given the same reference numerals and will be prefixed with the suffix "1".

In the manufacturing method of the aluminum alloy spiral tube 120 according to this embodiment, the conveying direction of the blank tube 110 and the rotation direction of the pressing part 133A are reversed midway through the forming process. In this embodiment, the case where the dummy spiral tube 20D is not manufactured prior to the manufacturing of the aluminum alloy spiral tube 20 as in the above-mentioned embodiment 1 is illustrated, but the dummy spiral tube 20D may be manufactured prior to the manufacturing as in the first embodiment. In this embodiment, instead of the downstream cutting measuring device 36 described in the above-mentioned embodiment 1, a cutting measuring device (measuring device) 39 is arranged downstream of the cutting device 134 (see FIG. 13). In this embodiment, the upstream cutting measuring device 37 and the intermediate cutting measuring device 38 described in the above-mentioned embodiment 1 are omitted.

In detail, when the production of the aluminum alloy spiral tube 120 is started, and one end 110A of the supplied blank tube 110 passes through the upstream conveying device 131 and the forming device 133 and reaches the downstream conveying device 132 as shown in FIG. 10, a plurality of pressing parts 133A provided in the forming device 133 advance in the radial direction of the blank tube 110, and the plurality of pressing parts 133A are abutted against the outer circumferential surface of the blank tube 110 at a position spaced apart from the one end 110A. FIG. 10 is a side view showing a state in which the first spiral uneven portion 121 has begun to be formed on the blank tube 110. The position of the one end 110A of the blank tube 110 at this time is set downstream of the position of the one end 10A of the blank tube 10 during the production of the dummy spiral tube 20D in embodiment 1 (see FIG. 3). Then, from this state, the mother tube 110 is transported along its longitudinal direction to the right side, i.e., the upstream side (first direction) as shown in Fig. 10 by the transport devices 131, 132 to displace the mother tube 110 relative to the forming device 133, and the plurality of pressing parts 133A are rotated around the mother tube 110 in a first rotation direction along the circumferential direction while pressing the plurality of pressing parts 133A against the outer circumferential surface of the mother tube 110, thereby forming a part of the helical uneven portion 121 in the mother tube 110 as shown in Fig. 11. At this time, the direction in which the mother tube 110 is moved is opposite to the direction in which the mother tube 10 is moved in the above-mentioned first embodiment (see Fig. 5), and similarly, the first rotation direction, which is the direction in which the pressing parts 133A are rotated along the circumferential direction of the mother tube 110, is opposite to the direction in which the pressing parts 33A are rotated in the above-mentioned first embodiment (see Fig. 5). At this time, a portion of the spiral uneven portion 121 formed on the blank tube 110 is adjacent to the upstream side in the longitudinal direction of the circular pipe portion 122 including one end 110A of the blank tube 110. FIG. 11 is a side view showing the state in which the conveying direction of the blank tube 110 and the rotation direction of the pressing portion 133A start to be reversed after a portion of the first spiral uneven portion 121 is formed on the blank tube 110.

As shown in FIG. 11, when a part of the spiral unevenness 121 is formed on the blank tube 110, the conveying direction of the blank tube 110 and the rotation direction of the pressing part 133A are reversed. That is, the blank tube 110 is conveyed by the conveying devices 131 and 132 along its longitudinal direction to the left side shown in FIG. 11, that is, the downstream side (second direction) to displace the blank tube 110 relative to the forming device 133, and the multiple pressing parts 133A are rotated around the blank tube 110 in a second rotation direction opposite to the first rotation direction along the circumferential direction while pressing the multiple pressing parts 133A against the outer circumferential surface of the blank tube 110. Then, as shown in FIG. 12, a part (downstream end part) of the previously formed spiral unevenness 121 is traced by the multiple pressing parts 133A. This clarifies the shape of the part (downstream end part) of the spiral unevenness 121. Fig. 12 is a side view showing a state where a part of the first helical uneven portion 121 has been traced by the pressing part 133A. The mother tube 110 is then conveyed downstream along its longitudinal direction by the conveying devices 131, 132, and the pressing parts 133A are rotated around the mother tube 110 in a second rotation direction along the circumferential direction while pressing the pressing parts 133A against the outer circumferential surface of the mother tube 110, thereby forming the remaining part of the helical uneven portion 121 on the mother tube 110, as shown in Fig. 13. Fig. 13 is a side view showing an operation of cutting the mother tube 110 to take out the aluminum alloy helical tube 120 on which the first helical uneven portion 121 has been formed. Then, when it is determined that the helical uneven portion 121 has reached a set length based on the elapsed time from the start of formation of the helical uneven portion 121, the conveying direction of the mother tube 110 and the rotating direction of the pressing parts 133A are reversed again. That is, the conveying devices 131 and 132 convey the blank tube 110 to the upstream side (first direction) along its longitudinal direction to displace the blank tube 110 relative to the forming device 133, and the pressing parts 133A are rotated around the blank tube 110 in a first rotation direction along the circumferential direction while pressing the pressing parts 133A against the outer circumferential surface of the blank tube 110. Then, a part (upstream end part) of the previously formed helical uneven portion 121 is traced by the pressing parts 133A. This clarifies the shape of the part (upstream end part) of the helical uneven portion 121. As described above, the aluminum alloy helical tube 120 has clarified shapes at both end portions in the longitudinal direction of the helical uneven portion 121. Here, for example, when the aluminum alloy spiral tube 120 is used as a heat transfer tube for a heat exchanger, both ends of the aluminum alloy spiral tube 120 are inserted into a pair of header tubes and a refrigerant flows inside the aluminum alloy spiral tube 120. At this time, since the shapes of both end portions in the longitudinal direction of the spiral uneven portion 121 are both clearly defined, the effect of suppressing the pressure loss of the refrigerant can be obtained.

When the downstream end of the blank tube 110 on which the helical unevenness 121 is formed in this way reaches the cutting measuring device 39, it is detected by the cutting measuring device 39, and the length from the downstream end of the blank tube 110 to the cutting device 134 is measured. Based on the measurement result by the cutting measuring device 39, the blank tube 110 is cut at the circular tube portion 122 by the cutting device 134. As a result, an aluminum alloy helical tube 120 formed by pressing both end portions of the helical unevenness 121 twice each by the pressing part 133A is taken out. In addition, when manufacturing the second and subsequent aluminum alloy helical tubes 120, it is possible to form the helical unevenness 121 by pressing both end portions of the helical unevenness 121 twice each by the pressing part 133A, as in the first aluminum alloy helical tube 120 described above, but it is also possible to form them in the same manner as in the first embodiment described above.

As described above, according to this embodiment, in the process of forming the spiral uneven portion 121 on the blank tube 110, the pressing portion 133A is started to be pressed against the outer circumferential surface of the blank tube 110, and the blank tube 110 and the pressing portion 133A are relatively displaced in a first direction along the longitudinal direction of the blank tube 110, and the pressing portion 133A is rotated in a first rotational direction along the circumferential direction of the blank tube 110 to form a part of the spiral uneven portion 121 on the blank tube 110. Then, the blank tube 110 and the pressing portion 133A are pressed against each other. The press portion 133A is relatively displaced in a second direction opposite to the first direction and the press portion 133A is rotated in a second direction opposite to the first direction, causing the press portion 133A to trace a portion of the spiral uneven portion 121, and then the blank tube 110 and the press portion 133A are continued to be displaced relative to each other in the second direction and the press portion 133A is continued to be rotated in the second direction to form the remaining portion of the spiral uneven portion 121 on the blank tube 110.

In such a manufacturing method of the aluminum alloy spiral tube 120, the blank tube 110 and the pressing portion 133A are displaced relative to each other in a first direction, and the pressing portion 133A is rotated in a first rotation direction, so that a part of the spiral uneven portion 121 is formed in advance on the blank tube 110. Then, the blank tube 110 and the pressing portion 133A are displaced relative to each other in a second direction opposite to the first direction, and the pressing portion 133A is rotated in a second rotation direction opposite to the first rotation direction, so that the pressing portion 133A traces the part of the spiral uneven portion 121 formed in advance. This clarifies the shape of the part of the spiral uneven portion 121. Then, the blank tube 110 and the pressing portion 133A are continuously displaced relative to each other in the second direction, and the pressing portion 133A is continuously rotated in the second rotation direction, so that the remaining part of the spiral uneven portion 121 is formed on the blank tube 110.

<Other embodiments>
The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included in the technical scope.

(1) In the molding process, the multiple pressing parts 33A, 133A may be moved in the longitudinal direction relative to the blank tube 10, 110 and may be rotated in the circumferential direction around the blank tube 10, 110 to form the helical uneven part 21, 121.

(2) In the cutting process, the timing for cutting the blank tube 10, 110 to extract the aluminum alloy spiral tube 20, 120 on which the nth spiral uneven portion 21, 121 is formed may be before the (n+1)th spiral uneven portion 21, 121 begins to form. In addition, the specific timing for cutting the blank tube 10, 110 to extract the aluminum alloy spiral tube 20, 120 can be changed as appropriate.

(3) In embodiment 1, in the process of forming the dummy spiral uneven portion 21D on the base tube 10, the dummy spiral uneven portion 21D may be formed to be longer than the spiral uneven portion 21. Also, in the process of forming the dummy spiral uneven portion 21D on the base tube 10, the dummy spiral uneven portion 21D may be formed to be approximately the same length as the spiral uneven portion 21.

(4) In embodiment 1, the timing for cutting the blank tube 10 to extract the dummy spiral tube 20D on which the dummy spiral uneven portion 21D is formed may be after the first spiral uneven portion 21 begins to form. In addition, the specific timing for cutting the blank tube 10 to extract the dummy spiral tube 20D can be changed as appropriate.

(5) In embodiment 1, when forming the dummy spiral uneven portion 21D, it is also possible to form the dummy spiral uneven portion 21D by pressing a portion of the dummy spiral uneven portion 21D twice with the pressing portion 33A, as in embodiment 2.

(6) The specific configuration of the conveying devices 31, 32, 131, and 132 can be changed as appropriate beyond what is shown in each drawing.

(7) The specific configuration of the molding device 33 can be changed as appropriate beyond what is shown in each drawing.

(8) The specific configuration of the cutting devices 34, 134 can be changed as appropriate beyond what is shown in each drawing.

(9) The specific configuration of each measuring device 35-39 can be changed as appropriate to those not shown in the drawings. For example, the conveying measuring device 35 may be configured with a photosensor. Also, each cutting measuring device 36-39 may be configured with a measuring roll.

(10) The method may involve manufacturing a spiral tube using a material other than an aluminum alloy.

(11) The location of the transport measuring device 35 can be changed. Even in this case, it is preferable that the transport measuring device 35 is located upstream of the cutting device 34, 134, and it can be located between the forming device 33, 133 and the cutting device 34, 134.

(12) In the above-described first embodiment, it is also possible to omit the intermediate cutting measuring device 38. In that case, the lengths of the dummy spiral tube 20D and the dummy spiral uneven portion 21D are adjusted in advance, and during production, the dummy spiral tube 20D is extracted by cutting the blank tube 10 based on the measurement results by the upstream cutting measuring device 37.

(13) In embodiment 2, it is also possible to form only one end portion of the spiral concave-convex portion 121 in the longitudinal direction by pressing it twice with the pressing portion 133A.

(14) Of the conveying devices 31, 32, 131, and 132, it is also possible to omit the downstream conveying devices 32 and 132.

(15) The pressing portion 33A, 133A may be composed of a member other than a bolt. In that case, the configuration of the molding device 33, 133 other than the pressing portion 33A, 133A may be appropriately changed.

10,110...primary tube, 10A,110A...one end, 20,120...aluminum alloy spiral tube (spiral tube), 20D...dummy spiral tube, 21,121...spiral uneven portion, 21D...dummy spiral uneven portion, 22,122...circular tube portion, 31,131...upstream conveying device (conveying device), 32,132...downstream conveying device (conveying device), 33A,133A...pressing portion, 36...downstream cutting measuring device (measuring device), 39...cutting measuring device (measuring device)

Claims (6)

A method for manufacturing a helical tube having a helical uneven portion in which an uneven shape is displaced helically in a longitudinal direction, comprising the steps of:
a step of continuously supplying a mother tube having a circular cross section, and rotating a pressing portion around the mother tube in a circumferential direction while pressing the pressing portion against an outer circumferential surface of the mother tube to form the helical uneven portion on the mother tube, the step being performed intermittently in the longitudinal direction of the mother tube, thereby alternately providing the helical uneven portion and a circular tube portion having a circular cross section in the longitudinal direction;
The blank tube is cut at the position of the circular tube portion ,
the blank pipe is transported along its longitudinal direction by a transport device, the transport device including an upstream-side transport device disposed upstream of the pressing unit in the transport direction, and a downstream-side transport device disposed downstream of the pressing unit in the transport direction,
In the step of forming the helical concave-convex portion, the mother tube is transported from the upstream side to the downstream side by the transport device along the longitudinal direction of the mother tube while the pressing part is rotated in a circumferential direction around the mother tube, thereby forming the helical concave-convex portion on the mother tube;
A method for manufacturing a helical tube includes measuring a length of a portion of the mother tube including the helical irregularity portion and the circular tube portion using a measuring device arranged downstream of the downstream conveying device in the longitudinal direction of the mother tube, and cutting the mother tube at a position of the circular tube portion based on the measurement results by the measuring device. 2. A method for manufacturing a spiral tube as described in claim 1, wherein the measuring device is arranged along the conveying direction downstream of the device for cutting the blank tube, and a relatively short spiral tube is manufactured by cutting the tube based on the measurement results by the upstream measuring device, and a relatively long spiral tube is manufactured by cutting the tube based on the measurement results by the downstream measuring device. The method for manufacturing a helical tube according to claim 1 or claim 2, in which, after forming the nth helical uneven portion on the base tube, the base tube is cut at the circular tube portion located between the nth helical uneven portion and the (n+1)th helical uneven portion after starting to form the (n+1)th helical uneven portion. a step of pressing the pressing part against an outer circumferential surface of the mother tube at a position spaced from one end of the mother tube while the pressing part is rotating circumferentially around the mother tube to form a dummy spiral concave-convex portion in the mother tube, the concave-convex portion having a concave-convex shape that is displaced in a spiral shape in the longitudinal direction,
A method for manufacturing a helical tube according to any one of claims 1 to 3, wherein a process for forming the helical uneven portion is then started at a position on the base tube that is spaced apart from the one end side relative to the dummy helical uneven portion, thereby providing the circular tube portion on the opposite side from the one end side relative to the dummy helical uneven portion, and the base tube is cut at the position of the circular tube portion to extract a dummy helical tube having the dummy helical uneven portion. The method for manufacturing a helical tube according to claim 4, wherein in the step of forming the dummy helical uneven portion on the base tube, the dummy helical uneven portion is formed to be shorter than the helical uneven portion. In the step of forming the helical concave-convex portion on the mother tube, the pressing portion is started to press against an outer circumferential surface of the mother tube, the mother tube and the pressing portion are relatively displaced in a first direction along a longitudinal direction of the mother tube, and the pressing portion is rotated in a first rotational direction along a circumferential direction of the mother tube, thereby forming a part of the helical concave-convex portion on the mother tube,
Then, the blank tube and the pressing portion are relatively displaced in a second direction opposite to the first direction, and the pressing portion is rotated in a second rotation direction opposite to the first rotation direction, so that the pressing portion traces a part of the helical concave-convex portion, and then
A method for manufacturing a spiral tube according to any one of claims 1 to 5, wherein the remaining portion of the spiral irregularity portion is formed on the raw tube by continuing to displace the raw tube and the pressing portion relative to each other in the second direction while continuing to rotate the pressing portion in the second rotational direction.

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