JP2018202426A - Multiple twisted tube with spirally grooved inner surface - Google Patents

Abstract

To provide a multiple twisted tube with a spirally grooved inner surface, the tube being provided with a plurality of flow paths inside and being provided with spiral grooves in the flow paths, and thereby having an increased heat exchange efficiency.SOLUTION: The multiple twisted tube with a spirally grooved inner surface is provided that is formed by twisting an extruded stock tube and comprises: a first tube part; a second tube part arranged inside the first tube part; and a plurality of rib parts connecting an inner circumferential surface of the first tube part to an outer circumferential surface of the second tube part, and partitioning a space between the first tube part and the second tube part into a plurality of flow paths. The multiple torsion tube with a spirally grooved inner surface is constituted in such a way that: a plurality of fins arranged along the circumferential direction are provided in at least one of the inner circumferential surface of the first tube part, the inner circumferential surface of the second tube part and the outer circumferential surface of the second tube part; grooves are constituted between the fins; and the rib parts and the fins spirally extend along the axial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inner spiral grooved multiple twisted tube used for a heat transfer tube of a heat exchanger or the like.

2. Description of the Related Art Conventionally, there are known multiple tubes that perform heat exchange between refrigerants flowing in an inner flow path and an outer flow path disposed around the inner flow path in the pipe.
Patent Document 1 discloses a double-pipe heat exchanger that improves heat exchange performance while suppressing an increase in cost in a heat pump heat source machine.

JP-A-2006-99075

  The problem of the double-pipe heat exchanger is to satisfy the demand of suppressing the increase in cost and improving the heat exchange performance. The heat exchange performance can be improved by increasing the length of the double-pipe heat exchanger. On the other hand, there is a problem that the heat exchanger increases in size and increases in material costs. is there.

  An object of the present invention is to provide a multi-twisted tube with an inner surface spiral groove that can improve heat exchange performance and is excellent in formability while suppressing an increase in size and cost of a heat exchanger.

  An inner spiral grooved multiple twisted tube according to the present invention is an inner spiral grooved multiple twisted tube that is a twisted material of an extruded element tube, and is disposed inside a first tube portion and the first tube portion. A space between the first tube portion and the second tube portion connecting the second tube portion, the inner peripheral surface of the first tube portion and the outer peripheral surface of the second tube portion. A plurality of ribs that divide the flow path into a plurality of flow paths, and an inner peripheral surface of the first tube portion, an inner peripheral surface of the second tube portion, and an outer peripheral surface of the second tube portion The at least one fin is provided with a plurality of fins arranged in the circumferential direction, a groove is formed between the fins, and the rib portion and the fin extend spirally along the axial direction. .

  In the above-mentioned inner spiral grooved multiple twisted tube, either the inner peripheral surface of the second tube portion, the outer peripheral surface of the second tube portion, or the inner peripheral surface of the first tube portion, A plurality of the fins arranged along the circumferential direction may be provided.

  In the above-mentioned inner spiral grooved multiple twisted tube, the twist lead angle on the outer peripheral surface of the inner spiral grooved multiple twisted tube may be 10 ° or more and 80 ° or less.

  In the above-described inner spiral grooved multiple twisted tube, the number of the plurality of fins arranged along the circumferential direction may be 15 or more.

  In the above-described inner spiral grooved multiple twisted tube, the height of the fin provided in the first tube portion is 20% or more and 80% or less with respect to the bottom wall thickness of the first tube portion. The height of the fin provided in the second pipe part may be 20% or more and 80% or less with respect to the bottom wall thickness of the second pipe part.

  ADVANTAGE OF THE INVENTION According to this invention, the multiple twisted pipe | tube with an internal spiral groove which improved the heat exchange efficiency can be provided by providing a several groove | channel inside and providing a spiral groove in a flow path.

It is a cross-sectional schematic diagram of the multiple twisted tube with an inner surface spiral groove of embodiment. It is a longitudinal cross-sectional schematic diagram of the multiple twisted tube with an inner surface spiral groove of embodiment. It is a side view of the multiple twisted tube with an inner surface spiral groove of an embodiment. It is a cross-sectional schematic diagram of the multiple twisted tube with an inner surface spiral groove of the modification 1. It is a longitudinal cross-sectional view of the extrusion element pipe in the manufacturing method of an embodiment. It is a side view which shows the manufacturing apparatus which performs a twist process in the manufacturing method of embodiment. It is a top view of the floating frame seen from the arrow VII direction in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the drawings used in the following description, for the purpose of emphasizing the feature portion, the feature portion may be shown in an enlarged manner for convenience, and the dimensional ratios of the respective constituent elements are not always the same as in practice. Absent. In addition, for the same purpose, portions that are not characteristic may be omitted from illustration.

[Heat transfer tube (multi-twisted tube with inner spiral groove)]
FIG. 1 is a schematic cross-sectional view of a heat transfer tube (multi-twisted tube with an inner spiral groove) 10 of the embodiment. FIG. 2 is a schematic vertical sectional view of the heat transfer tube 10. FIG. 3 is a side view of the heat transfer tube 10.
The heat transfer tube 10 of the present embodiment is a twisted material of an extruded element tube. The heat transfer tube 10 can be made of aluminum or an aluminum alloy. Moreover, the heat exchanger tube 10 may be comprised from other metal materials, such as a copper alloy. However, the heat transfer tube 10 of the present embodiment is made of aluminum or an aluminum alloy, so that it is light and inexpensive, has high heat exchange efficiency, and can exhibit various effects described below more remarkably.
When an aluminum alloy is used for the heat transfer tube 10, the aluminum alloy is not particularly limited, and is typically pure aluminum such as 1050, 1100, 1200, etc. defined by JIS, or 3000 represented by 3003 with Mn added thereto. A series aluminum alloy or the like can be applied. Moreover, you may comprise the heat exchanger tube 10 using either the 5000 series-7000 series aluminum alloy prescribed | regulated to JIS. In this specification, “aluminum” is a concept including an aluminum alloy and pure aluminum.

  The heat transfer tube 10 is a tube having a circular outer cross-section. The heat transfer tube 10 includes a first tube portion 41, a second tube portion 42 disposed inside the first tube portion 41, and a plurality (four in this embodiment) of rib portions 43. .

  The first tube portion 41 and the second tube portion 42 have a tube shape with a substantially circular cross section. The 1st pipe part 41 and the 2nd pipe part 42 are arrange | positioned concentrically. A space 44 is provided between the first tube portion 41 and the second tube portion 42. The space 44 extends in the circumferential direction along the inner peripheral surface 41 a of the first tube portion 41 and the inner peripheral surface 42 a of the second tube portion 42. The space 44 is partitioned into four first flow paths 44 a by the four rib portions 43.

  The outer peripheral surface of the first tube portion 41 constitutes the outer peripheral surface 10 a of the heat transfer tube 10. A plurality of first fins 46 are provided on the inner peripheral surface 41 a of the first pipe portion 41. The first fin 46 extends spirally along the length direction. A first groove 46g is formed between the first fins 46. The first groove 46g extends in a spiral shape along the axial direction together with the first fin 46.

  The outer peripheral surface 42b of the second pipe part 42 faces the inner peripheral surface 41a of the first pipe part 41 in the radial direction. In other words, the outer peripheral surface 42b of the second tube portion 42 is surrounded by the inner peripheral surface 41a of the first tube portion 41 from the radially outer side. A plurality of second fins 47 are provided on the inner peripheral surface 42 a of the second pipe portion 42. The second fin 47 extends spirally along the length direction. A second groove 47g is formed between the second fins 47. The second groove 47g extends spirally along the axial direction together with the second fin 47.

  In the present embodiment, the second tube portion 42 has a circular shape, but the shape of the second tube portion 42 is not particularly limited. As will be described later, the heat transfer tube 10 is reduced in diameter in the drawing process during the manufacturing process. Since the second pipe portion 42 receives the stress at the time of diameter reduction through the rib portion 43, the diameter of the portion to which the rib portion 43 is connected may be smaller than the other portions. is there. The heat transfer tube 10 can exhibit various effects even when the second tube portion 42 has such a distorted shape.

  The rib part 43 is located between the first pipe part 41 and the second pipe part 42 in the radial direction. The rib portion 43 extends along the radial direction and connects the inner peripheral surface 41 a of the first tube portion 41 and the outer peripheral surface 42 b of the second tube portion 42. The rib portion 43 extends spirally along the axial direction. Since the rib portion 43 defines the first flow paths 44a, the first flow paths 44a extend spirally along the axial direction.

  The plurality of rib portions 43 are arranged at equal intervals along the circumferential direction. Since the four rib portions 43 of the present embodiment are provided in the heat transfer tube 10, the adjacent rib portions 43 are arranged so as to rotate 90 ° around the center of the heat transfer tube 10. The number of the rib portions 43 is appropriately set according to the diameter of the heat transfer tube 10 and the bottom wall thicknesses of the first tube portion 41 and the second tube portion 42, but is preferably 3 or more. By providing three or more rib portions 43, the heat transfer tube 10 can uniformly reduce the diameter of the second tube portion 42 in accordance with the diameter reduction of the first tube portion 41 in the drawing step during the manufacturing process. Therefore, it is possible to suppress the radial distortion of the second pipe portion 42 and to sufficiently secure the flow path cross-sectional area of the first flow path 44a.

  Inside the heat transfer tube 10, there are four first flow paths 44 a positioned between the first tube portion 41 and the second tube portion 42, and a second position positioned inside the second tube portion 42. The flow path 45 is formed. Two or more kinds of fluids as a refrigerant or a heat medium flow through the plurality of flow paths (four first flow paths 44a and second flow paths 45).

  According to the present embodiment, the fluid in each flow path (four first flow paths 44a and second flow path 45) is a fin (first fin 46 or second fin 47) extending in a spiral shape. Therefore, highly efficient heat exchange with the heat transfer tube 10 can be performed. Further, highly efficient heat exchange can be performed between two or more kinds of fluids via the heat transfer tube 10. In particular, when heat exchange is performed between the heat medium and the refrigerant, the flow paths through which the heat medium and the refrigerant flow are preferably disposed adjacent to each other. Thereby, the heat exchange efficiency between a refrigerant | coolant and a heat medium can further be improved. If fins are arranged in at least one of the first flow path 44a and the second flow path 45, a certain effect of increasing the heat exchange efficiency between the flow path flowing through the flow path and the heat transfer tube 10 can be obtained. Can play. That is, at least one of the inner peripheral surface 41a of the first tube portion 41, the inner peripheral surface 42a of the second tube portion 42, and the outer peripheral surface 42b of the second tube portion 42 is along the circumferential direction. When a plurality of fins arranged side by side are provided, the above-described certain effect can be obtained.

  According to this embodiment, the 1st fin 46 and the 2nd fin 47 are provided in the internal peripheral surface 41a of the 1st pipe part 41, and the internal peripheral surface 42a of the 2nd pipe part 42, respectively. . Therefore, the first fins 46 are located in the first flow path 44 a, and the second fins 47 are provided in the second flow path 45. For this reason, the heat exchange efficiency of the fluid of each flow path (the four 1st flow paths 44a and the 2nd flow path 45) and the heat exchanger tube 10 can further be improved. As a result, the heat exchange efficiency between the fluids can also be increased.

  In addition, such an effect is an effect which can be show | played if the fin is arrange | positioned in each flow path. That is, such an effect is obtained by either the inner peripheral surface 42a of the second pipe portion 42, the outer peripheral surface 42b of the second pipe portion 42, or the inner peripheral surface 41a of the first pipe portion 41, This can be achieved when a plurality of the fins arranged along the circumferential direction are provided. FIG. 4 shows a schematic cross-sectional view of a heat transfer tube (multi-twisted tube with inner spiral groove) 110 of Modification 1. In addition, about the component of the same aspect as the heat exchanger tube 10 of this embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted. In the heat transfer tube 110, the first fin 146 is provided on the outer peripheral surface 42 b of the second tube portion 42, and no fin is provided on the inner peripheral surface 41 a of the first tube portion 41. The first fin 146 and the second fin 47 extend spirally along the axial direction. In the heat transfer tube 110, the first fin 146 and the second fin 47 are provided in the first flow path 44a and the second flow path 45, respectively, and the heat exchange efficiency between the fluid, the heat transfer pipe 110, and the fluid is provided. Can be effectively increased. Moreover, as shown in the modification 1, the 2nd pipe part 42 is provided by providing the 1st fin 146 and the 2nd fin 47 in the internal peripheral surface 42a and the outer peripheral surface 42b of the 2nd pipe part 42, respectively. The heat exchange efficiency between the first flow path 44a and the second flow path 45 can be increased more effectively.

  As shown in FIG. 2, according to the present embodiment, the rib portion 43 that divides the space 44 between the first tube portion 41 and the second tube portion 42 into a plurality of first flow paths 44a is It extends spirally along the axial direction. Thereby, each 1st flow path 44a is extended spirally along an axial direction. This makes it possible to ensure a long length along the axial direction of the first flow path 44a, and increase the heat exchange efficiency between the fluid flowing through the first flow path 44a and the heat transfer tube 10. Can do.

It is preferable that 15 or more first fins 46 are provided along the circumferential direction. When the number of the first fins 46 is 15 or more along the circumferential direction, the surface area of the inner peripheral surface 41a of the first pipe portion 41 is sufficiently increased so that the first pipe portion 41 and the second pipe The heat exchange efficiency with the fluid flowing in the space 44 between the portions 42 can be sufficiently increased.
It is preferable that 15 or more second fins 47 are provided along the circumferential direction. When the number of the second fins 47 is 15 or more along the circumferential direction, the surface area of the inner peripheral surface 42a of the second pipe part 42 is sufficiently increased, and the fluid flowing in the second pipe part 42 The heat exchange efficiency can be sufficiently increased.
In the present embodiment, fins (first fin 46 and second fin 47) are provided on the inner peripheral surface 41a of the first tube portion 41 and the inner peripheral surface 42a of the second tube portion 42, respectively. However, even when fins are provided on the outer peripheral surface 42b of the second pipe portion 42, it is preferable to provide 15 or more fins along the circumferential direction.

  In addition, the number of fins (first fins 46 in the present embodiment, first fins 146 in Modification 1) positioned in the first flow path 44a is preferably 5 or more. Thereby, the flow-path cross-sectional area of the 1st flow path 44a can be enlarged enough, and the heat exchange efficiency between the fluid which flows through the 1st flow path 44a, and the heat exchanger tube 10 can be improved.

  The number of fins (second fins 47) located in the second flow path 45 is preferably 15 or more. Thereby, the flow path cross-sectional area of the 2nd flow path 45 can be enlarged enough, and the heat exchange rate between the fluid which flows through the 2nd flow path 45, and the heat exchanger tube 10 can be raised.

  The height of the fin (first fin 46) provided in the first tube portion 41 is preferably 20% or more and 80% or less with respect to the bottom wall thickness of the first tube portion 41. Similarly, the height of the fins (second fin 47 in the present embodiment, first fin 146 in Modification 1) provided in the second pipe portion 42 is the thickness of the bottom wall of the second pipe portion 42. On the other hand, it is preferably 20% or more and 80% or less. By setting the height of each fin in this way, the ease of manufacturing is ensured, and the cross-sectional area of each flow path is sufficiently increased so that the heat exchange efficiency between the heat transfer tube 10 and the fluid is sufficient. Can be increased.

It is preferable that the torsion lead angle θ2 on the outer peripheral surface 10a of the heat transfer tube 10 shown in FIG. The heat transfer tube 10 of the present embodiment is a twisted material of the extruded element tube 10B. The heat transfer tube 10 including the spiral fins (the first fin 46 and the second fin 47) and the rib portion 43 is an extruded element tube in which fins and rib portions extending linearly in the length direction are formed by extrusion. It can be formed by applying twist while pulling out to 10B (see FIG. 5). The fins (the first fin 46 and the second fin 47) and the rib portion 43 are formed in a spiral shape with a lead angle corresponding to the twist lead angle θ2 on the outer peripheral surface 10a. By setting the torsion lead angle θ2 at the outer peripheral surface 10a to 10 ° or more and 80 ° or less, a sufficient lead angle torsion can be imparted to the fins (first fin 46 and second fin 47) and the rib portion 43. The heat exchange efficiency between the heat transfer tube 10 and the fluid flowing through the heat transfer tube 10 can be increased.
A spiral dice mark DM is formed on the outer peripheral surface 10 a of the heat transfer tube 10 on the outer peripheral surface of the heat transfer tube 10. The die mark DM is a linear recess formed along the extrusion direction on the peripheral surface of a member formed by extrusion. The die mark DM is formed due to the influence of a scratch on the extrusion mold or the bearing surface. The heat transfer tube 10 of the present embodiment is manufactured by adding a twist while drawing the extruded extruded tube. For this reason, the die mark DM formed in a linear shape by extrusion processing becomes a spiral shape with the application of twist.
The twist lead angle θ2 on the outer peripheral surface 10a of the heat transfer tube 10 can be measured as the twist lead angle of the die mark DM.
Note that the dice mark DM in FIG. 3 is illustrated as a single dice mark DM formed continuously for easy understanding. Actual dice marks are formed intermittently along the length direction. A plurality of dice marks DM extend spirally and in parallel along the circumferential direction on the outer peripheral surface 10 a of the heat transfer tube 10.
Here, a method of obtaining the twist lead angle θ2 on the outer peripheral surface 10a of the heat transfer tube 10 will be described.
First, the raw pipe before being twisted (extruded raw pipe 10B described later) is mounted on a surface plate, and a linear scoring line extending in the length direction is formed on the outer peripheral surface of the raw pipe using a height gauge. Form.
Next, twisting is applied to manufacture the heat transfer tube 10. The ruled line of the manufactured heat transfer tube 10 is spiral.
Next, it is determined from the pitch p of the spiral ruled line and the circumferential length a of the outer peripheral surface 10a of the heat transfer tube 10 using the following (Equation 1).
θ2 = tan−1 (a / p) (Formula 1)
If the die mark DM or the weld line generated when forming the raw tube is clearly formed, the die mark DM or the weld line may be used as a reference for the pitch p instead of the above-mentioned ruled line. .

[Production method]
Hereinafter, an embodiment of a method for manufacturing a heat transfer tube 10 according to the present invention will be described with reference to the drawings. The manufacturing method of the heat exchanger tube 10 includes an extrusion molding process and a twisting process in this order.

<Extrusion process>
First, the extrusion molding process will be described.
FIG. 5 is a vertical cross-sectional view of an extruded raw pipe (multiple pipe with straight grooves) 10B formed by an extrusion molding process. The extruded element tube has a cross-sectional shape that extends uniformly along the axial direction. The extruded tube 10B has a cross-sectional shape similar to that of the heat transfer tube 10 although the diameter and the size of each part are different. Although not shown in FIG. 5, a rib portion 43 is provided between the first tube portion 41 and the second tube portion 42. In addition, linear fins 46 </ b> B and 47 </ b> B extending linearly along the axial direction are provided on the inner peripheral surfaces of the first tube portion 41 and the second tube portion 42. Further, linear grooves 46Bg and 47Bg are provided between the linear fins 46B and 47B. A plurality of linear grooves 46Bg and 47Bg are formed at intervals in the circumferential direction.
The extrusion molding process is a process of manufacturing the extruded element pipe 10B (multi-pipe extrusion process with straight grooves) by extruding a billet made of an aluminum material.

<Drawing twisting process, empty drawing process>
Next, the drawing twisting process and the empty drawing process will be described.
The drawing twisting process is a process in which the fins (first fins 46 and second fins 47) and the ribs 43 are spiraled by applying twist to the above-described extruded element tube 10B while performing drawing.
In addition, the emptying step is a step of drawing the tube material without imparting a twist to adjust the outer shape of the tube material.

In addition, in this specification, the pipe material (that is, the above-described extruded element pipe 10B) before being twisted is referred to as a “straight grooved multiple pipe”. Further, the tube material after twisting (that is, the above-described heat transfer tube 10) is referred to as an “inner spiral grooved multiple twisted tube”. Further, in the process from the straight grooved multiple tube to the inner spiral grooved multiple twisted tube, an intermediate formed product to which about half of the twist is applied as compared with the inner surface spiral grooved multiple twisted tube is called an “intermediate twisted tube”. . Furthermore, “tube material” in the present specification is a superordinate concept of a multi-ply pipe with a straight groove, an intermediate twist pipe and a multi-ply pipe with an inner spiral groove, and means a pipe to be processed regardless of the stage of the manufacturing process. To do.
In the present specification, the “front stage” and the “rear stage” mean the front-rear relationship (that is, upstream and downstream) along the processing order of the pipe material, and do not mean the arrangement of each part in the apparatus.
The pipe material is conveyed from the front stage (upstream) side to the rear stage (downstream) side in the multi-twisted tube manufacturing apparatus with inner spiral grooves. The part arranged in the front stage is not necessarily arranged in the front, and the part arranged in the rear stage is not necessarily arranged in the rear.

<Manufacturing apparatus that performs a drawing twist process and an empty drawing process>
FIG. 6 is a side view showing a manufacturing apparatus A for producing an inner spiral grooved multiple twisted tube (heat transfer tube) 10 by applying two twists to the straight grooved multiple tube (extrusion element tube) 10B. First, after explaining the manufacturing apparatus A, a drawing twisting process and an empty drawing process using the manufacturing apparatus A will be described.
In FIG. 6, the support bases for the respective drawing dies provided in the manufacturing apparatus A are omitted.

The manufacturing apparatus A includes a revolving mechanism 30, a floating frame 34, an unwinding bobbin (first bobbin) 11, a first guide capstan 18, a first drawing die 1, and a first revolving capstan. 21, a revolution flyer 23, a second revolution capstan 22, a second drawing die 2, a second guide capstan 61, and a take-up bobbin (second bobbin) 71.
Hereinafter, details of each unit will be described in detail.

(Revolution mechanism)
The revolution mechanism 30 includes a rotating shaft 35 including a front shaft 35A and a rear shaft 35B, a drive unit 39, a front stand 37A, and a rear stand 37B.
The revolution mechanism 30 rotates the rotation shaft 35, the first revolution capstan 21, the second revolution capstan 22, and the revolution flyer 23 fixed to the rotation shaft 35.
In addition, the revolution mechanism 30 maintains the stationary state of the floating frame 34 that is positioned coaxially with the rotation shaft 35 and supported by the rotation shaft 35. As a result, the unwinding bobbin 11, the first guide capstan 18 and the first drawing die 1 supported by the floating frame 34 are kept stationary.

  Both the front shaft 35A and the rear shaft 35B have a hollow cylindrical shape. Both the front shaft 35 </ b> A and the rear shaft 35 </ b> B are arranged coaxially with the revolution rotation central axis C (pass line of the first drawing die) as the central axis. The front shaft 35A is rotatably supported by the front stand 37A via a bearing 36, and extends rearward (from the rear stand 37B side) from the front stand 37A. Similarly, the rear shaft 35B is rotatably supported by the rear stand 37B via a bearing, and extends from the rear stand 37B to the front (front stand 37A side). A floating frame 34 is bridged between the front shaft 35A and the rear shaft 35B.

The drive unit 39 includes a drive motor 39c, a linear motion shaft 39f, belts 39a and 39d, and pulleys 39b and 39e. The drive unit 39 rotates the front shaft 35A and the rear shaft 35B.
The drive motor 39c rotates the linear motion shaft 39f. The linear motion shaft 39f extends in the front-rear direction at the lower part of the front stand 37A and the rear stand 37B.
A pulley 39b is attached to the front end 35Ab of the front shaft 35A at the tip that penetrates the front stand 37A. The pulley 39b is interlocked with the linear motion shaft 39f via the belt 39a. Similarly, the rear end portion 35Bb of the rear shaft 35B has a pulley 39e attached to the tip that penetrates the rear stand 37B, and interlocks with the linear motion shaft 39f via a belt 39d. Thereby, the front shaft 35A and the rear shaft 35B rotate synchronously around the revolution rotation center axis C.

  A first revolving capstan 21, a second revolving capstan 22, and a revolving flyer 23 are fixed to the rotating shaft 35 (the front shaft 35A and the rear shaft 35B). As the rotary shaft 35 rotates, these members fixed to the rotary shaft 35 revolve around the revolution rotation center axis C.

(Floating frame)
The floating frame 34 is supported via bearings 34a on end portions 35Aa and 35Ba of the front shaft 35A and the rear shaft 35B of the rotary shaft 35 facing each other. Further, the floating frame 34 supports the unwinding bobbin 11, the first guide capstan 18, and the first drawing die 1.

  FIG. 7 is a plan view of the floating frame 34 as seen from the direction of arrow VII in FIG. As shown in FIGS. 6 and 7, the floating frame 34 has a box shape that opens up and down. The floating frame 34 includes a front wall 34b and a rear wall 34c that are opposed to each other in the front-rear direction, and a pair of support walls 34d that are opposed to the left-right side and extend in the front-rear direction.

  A through hole is provided in the front wall 34b and the rear wall 34c, and ends 35Aa and 35Ba of the front shaft 35A and the rear shaft 35B are inserted, respectively. A bearing 34a is interposed between the end portions 35Aa and 35Ba and the through holes of the front wall 34b and the rear wall 34c. Thereby, the rotation of the rotation shaft 35 (the front shaft 35A and the rear shaft 35B) is not easily transmitted to the floating frame 34. The floating frame 34 remains stationary with respect to the ground G even when the rotating shaft 35 is in a rotating state. Note that a weight that biases the center of gravity of the floating frame 34 with respect to the revolution rotation center axis C may be provided to stabilize the stationary state of the floating frame 34.

  As shown in FIG. 7, the pair of support walls 34d are arranged on both sides of the unwinding bobbin 11, the first guide capstan 18 and the first drawing die 1 in the left-right direction (vertical direction in FIG. 7). Yes. The pair of support walls 34d rotatably support the bobbin support shaft 12 that holds the unwinding bobbin 11 and the rotation axis J18 of the first guide capstan 18. The support wall 34d supports the first drawing die 1 via a die support (not shown).

(Unwinding bobbin)
The unwinding bobbin 11 is wound with a multi-tube 10B (see FIG. 7) with straight grooves in which straight grooves 46Bg and 47Bg are formed. The unwinding bobbin 11 unwinds the straight grooved multiple tube 10B and supplies it to the subsequent stage.
The unwinding bobbin 11 is detachably attached to the bobbin support shaft 12.

  As shown in FIG. 7, the bobbin support shaft 12 extends in a direction orthogonal to the rotation shaft 35. The bobbin support shaft 12 is supported by the floating frame 34 so as to be able to rotate and rotate. In addition, autorotation means rotating around the central axis of the bobbin support shaft 12 itself here. The bobbin support shaft 12 holds the unwinding bobbin 11 and rotates in the supply direction of the unwinding bobbin 11 to assist the unwinding of the tube material 5 of the unwinding bobbin 11.

  The unwinding bobbin 11 is removed when all of the wound multi-tubes 10B with straight grooves are supplied, and replaced with another unwinding bobbin. The removed empty unwinding bobbin 11 is attached to an extrusion device that forms a multi-tube 10B with a straight groove, and the multi-tube 10B with a straight groove is wound again. The unwinding bobbin 11 is supported by the floating frame 34 and does not revolve. Therefore, even if the straight-grooved multiple tube 10B is turbulently wound around the unwinding bobbin 11, it can be supplied without hindrance and can be used without rewinding. Further, the number of revolutions for imparting twist to the pipe 5 in the manufacturing apparatus A is not limited by the weight of the unwinding bobbin 11. Therefore, the long tube material 5 can be wound around the unwinding bobbin 11. Thereby, a twist can be provided with respect to the elongate pipe material 5, and manufacturing efficiency can be improved.

  A brake unit 15 is provided on the bobbin support shaft 12. The brake unit 15 applies a braking force to the rotation of the bobbin support shaft 12 with respect to the floating frame 34. That is, the brake unit 15 restricts the rotation of the unwinding bobbin 11 in the unwinding direction. Backward tension is applied to the pipe material 5 conveyed in the unwinding direction by the braking force of the brake unit 15. As the brake unit 15, for example, a powder brake or a band brake capable of adjusting a torque as a braking force can be adopted.

(First guide capstan)
The first guide capstan 18 has a disk shape. The tube material 5 fed out from the unwinding bobbin 11 is wound around the first guide capstan 18 once. The tangential direction of the outer periphery of the first guide capstan 18 coincides with the revolution rotation center axis C. The first guide capstan 18 guides the tube material 5 onto the revolution rotation center axis C along the first direction D1.
The first guide capstan 18 is supported by the floating frame 34. In addition, on the outer periphery of the first guide capstan 18, a guide roller 18b capable of rotating and rotating is arranged side by side. The first guide capstan 18 of the present embodiment smoothly conveys the tube material 5 as the guide roller 18b rolls. Further, when the guide roller 18b is not provided on the outer periphery of the first guide capstan 18, the pipe material 5 can be conveyed by the first guide capstan 18 itself rotating and rotating. In FIG. 7, the guide roller 18b is not shown.

  As shown in FIG. 7, a pipe guiding portion 18 a is provided between the first guide capstan 18 and the unwinding bobbin 11. The pipe guide part 18a is a plurality of guide rollers arranged so as to surround the pipe material 5, for example. The pipe guide part 18 a guides the pipe material 5 supplied from the unwinding bobbin 11 to the first guide capstan 18.

  Instead of the first guide capstan 18, a guide tube having a traverse function may be provided between the unwinding bobbin 11 and the first drawing die 1. When the guide tube is provided, the distance between the unwinding bobbin 11 and the first drawing die 1 can be shortened, and the space in the factory can be effectively used.

(First drawing die)
The first drawing die 1 reduces the diameter of the tube material 5 (the straight grooved multiple tube 10B). The first drawing die 1 is fixed to the floating frame 34. The first drawing die 1 has the first direction D1 as the drawing direction. The center of the first drawing die 1 coincides with the revolution rotation center axis C of the rotation shaft 35. The first direction D1 is parallel to the revolution rotation center axis C.
Lubricating oil is supplied to the first drawing die 1 by a lubricating oil supply device 9 </ b> A fixed to the floating frame 34. Thereby, the drawing force in the first drawing die 1 can be reduced.
The pipe material 5 that has passed through the first drawing die 1 is introduced into the front shaft 35 </ b> A through a through hole provided in the front wall 34 b of the floating frame 34.

(First Recap Capstan)
The first revolution capstan 21 has a disk shape. The first revolving capstan 21 is disposed in a lateral hole 35Ac that penetrates the inside and outside of the hollow front shaft 35A in the radial direction. The first revolving capstan 21 is supported by a support body 21a fixed to the outer peripheral portion of the rotation shaft 35 (front shaft 35A) with the center of the disk as the rotation axis J21.

One of the outer tangents of the first revolution capstan 21 coincides with the revolution rotation center axis C.
The tube material 5 conveyed in the first direction D1 on the revolution rotation center axis C is wound around the first revolution capstan 21 by one or more rounds. The first revolving capstan 21 winds the pipe material 5, draws it from the inside of the front shaft 35 </ b> A to the outside, and guides it to the revolving flyer 23.

  The first revolving capstan 21 revolves around the revolving rotation center axis C together with the front shaft 35A. The revolution rotation center axis C extends in a direction orthogonal to the rotation axis J21 of the rotation of the first revolution capstan 21. The pipe 5 is twisted between the first revolving capstan 21 and the first drawing die 1. As a result, the pipe material 5 changes from the straight grooved multiple pipe 10B to the intermediate twisted pipe 10C.

  Along with the first revolving capstan 21, a drive motor 20 is provided on the front shaft 35A. The drive motor 20 drives and rotates the first revolving capstan 21 in the winding direction (conveying direction) of the tube material 5. As a result, the first revolving capstan 21 imparts a forward tension for passing the first drawing die 1 to the tube material 5.

  It is preferable that the first revolving capstan 21 and the drive motor 20 are arranged symmetrically with respect to the revolution rotation center axis C so that the center of gravity is located at the revolution rotation center axis C of the front shaft 35A. Thereby, the balance of rotation of the front shaft 35A can be stabilized. When the difference in weight between the first revolving capstan 21 and the drive motor 20 is large, a weight may be provided to stabilize the center of gravity.

(Revolution flyer)
The revolution flyer 23 inverts the pipe line of the pipe material 5 between the first drawing die 1 and the second drawing die 2. The revolution flyer 23 reverses the tube material 5 conveyed in the first direction D1 which is the drawing direction of the first drawing die 1, and the conveying direction is the second direction D2 which is the drawing direction of the second drawing die 2. Turn to. More specifically, the revolution flyer 23 guides the pipe material 5 from the first revolution capstan 21 to the second revolution capstan 22.

The revolution flyer 23 has a plurality of guide rollers 23a and a guide roller support (not shown) that supports the guide rollers 23a. Here, the guide roller support is not shown in order to eliminate complexity, but the guide roller support is supported by the rotating shaft 35.
However, the guide roller is not indispensable for the structure of the flyer, and it may be a plate-like structure for allowing the tube to pass therethrough and having a shape attached with a ring for passing it. This ring may be provided on a plate-shaped member. A part of this ring may be constituted by a part of this plate-shaped member. The plate-shaped member may be supported on the rotating shaft 35 in the same manner as the guide roller support.
The guide rollers 23 a are arranged in a bow shape that curves outward with respect to the revolution rotation center axis C. The guide roller 23a itself rolls to convey the tube material 5 smoothly. The revolution flyer 23 rotates around the revolution rotation center axis C around the floating frame 34 and the first drawing die 1 and the unwinding bobbin 11 supported in the floating frame 34.

  One end of the revolution flyer 23 is located outside the first revolution capstan 21 with respect to the revolution rotation center axis C. The other end of the revolution flyer 23 passes through a lateral hole 35Bc that penetrates the inside and outside of the hollow rear shaft 35B in the radial direction and extends into the rear shaft 35B. The revolution flyer 23 guides the pipe member 5 wound around the first revolution capstan 21 and fed outward to the rear shaft 35B side. Further, the revolution flyer 23 feeds the pipe material 5 on the revolution rotation center axis C along the second direction D2 inside the rear shaft 35B.

In addition, the revolution flyer 23 of this embodiment was demonstrated as what conveys the pipe material 5 with the guide roller 23a. However, the revolution flyer 23 may be formed from a strip formed in an arcuate shape, and the tube material 5 may be transported by sliding on one surface of the strip.
Moreover, in FIG. 6, the case where the pipe material 5 passes the outer side of the guide roller 23a was illustrated.
However, when the rotational speed of the revolution flyer 23 is high, the pipe material 5 may be derailed from the revolution flyer by centrifugal force. In such a case, it is preferable to further provide a guide roller 23a outside the tube material 5.
A plurality of dummy fryer having the same weight as the revolution flyer 23 and extending from the front shaft 35 </ b> A to the rear shaft 35 </ b> B and rotating synchronously with the revolution flyer 23 may be provided. Thereby, rotation of the rotating shaft 35 can be stabilized.

(Second Revolving Capstan)
The second revolution capstan 22 has a disk shape, like the first revolution capstan 21. The second revolving capstan 22 is supported by a support body 22a provided at the tip of the end portion 35Bb of the rear shaft 35B. In addition, on the outer periphery of the second revolving capstan 22, guide rollers 22c that are capable of rotating and rotating are arranged side by side. The second revolving capstan 22 of the present embodiment smoothly conveys the tube material 5 as the guide roller 22c rolls. Moreover, when the guide roller 22c is not provided in the outer periphery of the 2nd revolution capstan 22, the pipe material 5 can be conveyed because the 2nd revolution capstan 22 itself rotates and rotates.

One of the outer tangents of the second revolution capstan 22 coincides with the revolution rotation center axis C.
The tube material 5 conveyed in the second direction D2 on the revolution rotation center axis C is wound around the second revolution capstan 22 by one turn or more. The second revolution capstan 22 feeds the wound pipe material in the second direction D2 on the revolution rotation center axis C.

  The second revolution capstan 22 revolves around the revolution rotation center axis C together with the rear shaft 35B. The revolution rotation center axis C extends in a direction perpendicular to the rotation axis J22 of the rotation of the second revolution capstan 22. The pipe material 5 drawn out from the second revolution capstan 22 is reduced in diameter at the second drawing die 2. Since the second drawing die 2 is stationary with respect to the ground G, the pipe material 5 can be twisted between the second revolving capstan 22 and the second drawing die 2. Thereby, the pipe material 5 changes from the intermediate twisted tube 10C to the multiple twisted tube 10 with the inner surface spiral groove.

  The support 22 a that supports the second revolution capstan 22 supports the weight 22 b at a position symmetrical to the second revolution capstan 22 with respect to the revolution center axis C. The weight 22b stabilizes the balance of rotation of the rear shaft 35B.

(Second drawing die)
The second drawing die 2 is disposed at the rear stage of the second revolving capstan 22. The second drawing die 2 has an opposite second direction D2 as the drawing direction. The second direction D2 is a direction parallel to the revolution center axis C. The second direction D2 is opposite to the first direction D1, which is the drawing direction of the first drawing die 1. The pipe material 5 passes through the second drawing die 2 along the second direction D2. The second drawing die 2 is stationary with respect to the ground G. The center of the second drawing die 2 coincides with the revolution rotation center axis C of the rotation shaft 35.

The second drawing die 2 is supported by the gantry 62 via a die support body (not shown), for example. The second drawing die 2 is supplied with lubricating oil by a lubricating oil supply device 9B attached to the gantry 62. Thereby, the drawing force in the second drawing die 2 can be reduced.
By reducing the diameter and applying the twist in the second drawing die 2, the pipe material 5 changes from the intermediate twisted tube 10 </ b> C to the multiple twisted tube 10 with the inner surface spiral groove.

(Second guide capstan)
The second guide capstan 61 has a disk shape. The tangential direction of the outer periphery of the second guide capstan 61 coincides with the revolution rotation center axis C. The pipe material 5 conveyed in the second direction D2 on the revolution rotation center axis C is wound around the second guide capstan 61 by one turn or more.

  The second guide capstan 61 is rotatably supported by the gantry 62 around the rotation axis J61. The rotation axis J61 of the second guide capstan 61 is connected to the drive motor 63 via a drive belt or the like. The second guide capstan 61 is driven to rotate in the winding direction (conveying direction) of the tube material 5 by the drive motor 63. The drive motor 63 is preferably a torque motor capable of torque control.

  When the second guide capstan 61 is driven, a forward tension is applied to the pipe material 5. As a result, the pipe 5 is conveyed forward with a drawing stress necessary for processing in the second drawing die 2.

<Finished drawing die>
The finish drawing die 7 is located between the second guide capstan 61 and the take-up bobbin 71. The finish drawing die 7 finishes and shapes the pipe material 5. The finish drawing die 7 is provided for the skin pass of the pipe material 5 that has passed through the first and second drawing dies 1 and 2. In the empty drawing process (finish drawing process) by the finishing drawing die 7, the change in the cross section due to drawing is small, the surface and dimensions are finished and the roundness of the pipe material 5 is restored. Further, in the emptying step, nonuniformity of the bottom wall thickness of the pipe material 5 is reduced.
The finish drawing die 7 may be provided at any position as long as it is between the second drawing die 2 and the winding bobbin 71.

(Winding bobbin)
The winding bobbin 71 is provided at the end of the pipe line of the pipe material 5 and collects the pipe material 5. A guiding portion 72 is provided in the front stage of the winding bobbin 71. The guiding portion 72 has a traverse function and winds the tube material 5 around the winding bobbin 71. In the present embodiment, the case where the guide portion 72 has a traverse function is illustrated, but the winding bobbin 71 may reciprocate in the direction of the rotation axis.

  The take-up bobbin 71 is detachably attached to the bobbin support shaft 73. The bobbin support shaft 73 is supported by the gantry 75 and is connected to the drive motor 74 via a drive belt or the like. The take-up bobbin 71 is driven and rotated by the drive motor 74 and takes up the tube material 5 without slackening it. The winding bobbin 71 is removed when the pipe material 5 is sufficiently wound, and is replaced with another winding bobbin 71.

<Drawing twisting process>
A method for manufacturing the inner spiral grooved multiple twisted tube 10 using the inner spiral grooved multiple twisted tube manufacturing apparatus A will be described.
First, as a preliminary process, the straight grooved multiple tube 10B is wound around the unwinding bobbin 11 in a coil shape. Further, the unwind bobbin 11 is set on the floating frame 34 of the manufacturing apparatus A. Moreover, the pipe material 5 (multiple pipe 10B with a linear groove) is drawn out from the unwinding bobbin 11, and is set in the pipe line of the multi pipe 10B with a straight groove in advance. Specifically, the pipe material 5 is made up of a first guide capstan 18, a first drawing die 1, a first revolution capstan 21, a revolution flyer 23, a second revolution capstan 22, and a second drawing die 2. The second guide capstan 61 and the take-up bobbin 71 are passed through and set in this order.

In the manufacturing process of the multi-twisted tube 10 with the inner surface spiral groove, a description will be given along the pipe material conveyance path.
First, the pipe material 5 is sequentially unwound from the unwinding bobbin 11.
Next, the pipe material 5 fed out from the unwinding bobbin 11 is wound around the first guide capstan 18. The first guide capstan 18 guides the pipe member 5 to the die hole of the first drawing die 1 located on the revolution rotation center axis C (first guiding step).

Next, the pipe material 5 is passed through the first drawing die 1. Further, the tube material 5 is wound around the first revolving capstan 21 at the subsequent stage of the first drawing die 1 and rotated around the rotation axis.
As a result, the diameter of the tube material 5 is reduced and twist is applied (first twist extraction step).

  In the first twist drawing process, a forward tension is applied to the pipe member 5 by the drive motor 20 that drives the first revolving capstan 21. At the same time, rear tension is applied to the pipe member 5 by the brake portion 15 of the unwinding bobbin 11. For this reason, it is possible to apply an appropriate tension to the tube material 5, and it is possible to provide a stable twist angle without causing the tube material 5 to buckle and break.

  After passing through the first drawing die 1, the pipe material 5 is wound around a first revolving capstan 21 that revolves and rotates. The tube material 5 is reduced in diameter by the first drawing die 1 and is twisted by the first revolving capstan 21. As a result, twist is applied to the straight grooves 46Bg and 47Bg (see FIG. 5) on the inner surface of the tube material 5 (multiple tube 10B with straight grooves), and spiral grooves 46g and 47g (see FIG. 2) are formed on the inner surface. The straight grooved multiple tube 10B becomes the intermediate twisted tube 10C by the first twist drawing process. The intermediate twisted tube 10 </ b> C is a tube material at an intermediate stage in the manufacturing process of the inner spiral grooved multiple twisted tube 10, and is in a state in which a spiral groove having a shallower twist angle is formed than the inner spiral grooved multiple twisted tube 10. .

  In the first twist drawing process, the tube material 5 is twisted and simultaneously drawn by a drawing die. That is, the pipe material 5 is given a composite stress by simultaneous processing of twisting and diameter reduction. Under the combined stress, the shear stress of the tube material 5 becomes smaller than when only twisting is performed, and a large twist can be imparted to the tube material 5 before reaching the buckling stress of the tube material 5. Thereby, a big twist can be provided, suppressing generation | occurrence | production of the buckling of the pipe material 5. FIG.

A first guide capstan 18 is provided in the preceding stage of the first drawing die 1 to restrict the rotation of the tube material 5. That is, the pipe 5 is constrained from being deformed in the twisting direction before the first drawing die 1. The tube material 5 is twisted between the first drawing die 1 and the first revolving capstan 21. That is, in the first twist drawing process, a region (working region) where the tube material 5 is twisted is limited between the first drawing die 1 and the first revolving capstan 21.
There is a correlation between the length of the machining area and the limit torsion angle (the maximum torsion angle that can be twisted without buckling), and even if a large torsion angle is applied by shortening the machining area Buckling is unlikely to occur. By providing the first guide capstan 18, the processing area can be set short without being twisted before the first drawing die 1. Further, by shortening the distance between the first drawing die 1 and the first revolving capstan 21, the machining area can be set short, and a large twist can be imparted to the tube material 5 without causing buckling.

It is preferable that the diameter reduction ratio of the pipe material 5 by the first drawing die 1 is 2% or more. There is a correlation between the limit torsion angle and the diameter reduction rate, and a tendency for the limit torsion angle to increase as the diameter reduction rate at the time of drawing increases is observed. That is, when the diameter reduction rate is too small, the effect of drawing is poor and it is difficult to obtain a large twist angle, so it is preferable to set it to 2% or more. For the same reason, it is more preferable that the diameter reduction rate is 5% or more.
On the other hand, if the diameter reduction rate becomes too large, breakage tends to occur at the processing limit, so 25% or less is preferable.

  Next, the pipe material 5 is wound around the revolution flyer 23 and the conveyance direction of the pipe material 5 is directed to the second direction D2 on the revolution rotation central axis C. Further, the pipe material 5 is wound around the second revolution capstan 22 and the pipe material 5 is introduced into the second drawing die 2 (second induction step). Thereby, the conveyance direction of the pipe material 5 is reversed from the first direction D1 to the second direction D2, and is aligned with the center of the second drawing die 2. The revolution flyer 23 rotates about the revolution rotation center axis C around the floating frame 34. The first revolution capstan 21, the revolution flyer 23, and the second revolution capstan 22 rotate synchronously around the revolution rotation center axis C. Therefore, the tube material 5 does not rotate relatively between the first revolving capstan 21 and the second revolving capstan 22, so that no twist is applied.

  Next, the tube material 5 that rotates together with the second revolving capstan 22 is passed through the second drawing die 2. As a result, the tube material 5 is reduced in diameter and twisted, and the twist angles of the spiral grooves 46g and 47g are further increased (second twist-drawing step). The intermediate twisted tube 10 </ b> C becomes the multiple twisted tube 10 with the inner surface spiral groove by the second twist pulling process.

  In the second torsion drawing process, a forward tension is applied to the pipe member 5 by the drive motor 63 that drives the second guide capstan 61. When a torque motor capable of torque control is used as the drive motor 63, the second guide capstan 61 can adjust the front tension applied to the tube material 5. By adjusting the front tension by the second guide capstan 61, it is possible to apply an appropriate tension to the tube material 5 in the second twist drawing process. Thereby, a stable twist angle can be imparted to the tube material 5 without causing buckling and fracture.

  The pipe material 5 passes through the second drawing die 2 after being wound around the second revolving capstan 22 that revolves and rotates. The tube material 5 is reduced in diameter by the second drawing die 2 and twisted by the second revolving capstan 22. Thereby, a larger twist is imparted to the spiral grooves 46g and 47g on the inner surface of the tube material 5, and the twist angle of the spiral grooves 46g and 47g is increased. The intermediate twisted tube 10 </ b> C becomes the multiple twisted tube 10 with the inner surface spiral groove by the second twist pulling process.

  In the front stage of the second drawing die 2, the pipe material 5 is wound around the second revolution capstan 22. In the subsequent stage of the second drawing die 2, a second guide capstan 61 is provided to restrict the rotation of the tube material 5. That is, the pipe 5 is constrained from being deformed in the twisting direction before and after the second drawing die 2, and the pipe 5 is twisted between the second revolving capstan 22 and the second guide capstan 61. Is granted. That is, in the second twist drawing process, the region (working region) where the tube material 5 is twisted is limited between the second revolution capstan 22 and the second drawing die 2. As described above, by shortening the machining area, buckling is unlikely to occur even when a large twist angle is applied. By providing the second guide capstan 61, twisting is not applied in the subsequent stage of the second drawing die 2, and the processing area can be set short.

  In the present embodiment, the second revolution capstan 22 is provided behind the rear stand 37B (on the second drawing die 2 side), but the second revolution capstan 22 is connected to the front stand 37A. You may be located between back stand 37B. However, by arranging the second revolving capstan 22 rearward with respect to the rear stand 37B and bringing it closer to the second drawing die 2, the processing area in the second twist drawing step can be shortened. Thereby, generation | occurrence | production of buckling can be suppressed more effectively.

  In the second twist drawing process, twisting and drawing are performed in the same manner as in the first twist drawing process, and a composite stress is applied to the tube material 5. Thereby, before reaching the buckling stress of the pipe material 5, a big twist can be provided to the pipe material while suppressing the occurrence of buckling.

The diameter reduction rate of the tube material 5 by the second drawing die 2 is preferably 2% or more (more preferably 5% or more) and 25% or less, as in the first twist drawing process.
In addition, in the 1st drawing die 1, when a big diameter reduction (for example, diameter reduction of 30% or more of diameter reduction) is performed, since the pipe material 5 will work harden | cure, the large diameter reduction in the 2nd drawing die 2 is performed. It becomes difficult. Therefore, the total of the diameter reduction rate of the first drawing die 1 and the diameter reduction rate of the second drawing die 2 is preferably 4% or more and 50% or less.

<Empty drawing process>
Next, the pipe material 5 is passed through the finish drawing die 7 (finish drawing step). The pipe material 5 passes through the finish drawing die 7 so that the surface is shaped and the uneven thickness of the bottom wall thickness is reduced. Further, even when the pipe material 5 is slightly deformed such as being crushed, the finishing pulling process is performed to correct the deformation to obtain a multi-twisted pipe 5R with an inner surface spiral groove having a predetermined roundness. be able to. A force for conveying the tube material 5 with respect to the drawing load of the finish drawing die 7 is applied by a drive motor 74 provided on the winding bobbin 71. Lubricating oil is supplied to the pipe member 5 passing through the finish drawing die 7 by a lubricating oil supply device (not shown).

  Moreover, a heat transfer tube having a stable surface property and shape can be manufactured by performing an empty drawing step after the twist drawing step (the first twist drawing step and the second twist drawing step). The diameter reduction ratio of the tube material 5 in the emptying step is preferably 25% or less. Furthermore, it is preferable that the total diameter reduction ratio of the first drawing step, the second drawing step, and the empty drawing step is 30% or more.

<Recovery process>
Next, the pipe material 5 is wound around the winding bobbin 71 and collected. The take-up bobbin 71 is able to take up the tube material 5 without slack by rotating in synchronization with the conveying speed of the tube material 5 by the drive motor 74.
Through the above steps, the multi-twisted tube 10 with the inner surface spiral groove can be manufactured using the manufacturing apparatus A.

<O materialization process>
Next, the O materializing step will be described.
The O materializing process is performed after the twisting process. The O materializing process is a heat treatment process in which the pipe material 5 is subjected to an annealing process. By performing the O material forming step, the distortion of the aluminum material can be removed and the internal stress can be removed.

<Summary of manufacturing method>
According to the manufacturing method of the present embodiment, the total diameter reduction ratio of each step (the first drawing step, the second drawing step, and the empty drawing step) is 30% or more. By setting the reduction ratio to 30% or more, a large twist can be imparted. Moreover, according to the manufacturing method of this embodiment, the diameter reduction rate of each process is 25% or less. When the diameter reduction rate in each step is 25% or less, the work hardening can be suppressed and the diameter reduction in the subsequent process can be performed smoothly.

  In the drawing and twisting process of the present embodiment, the first twist-drawing process and the second twist-drawing process are performed again on the inner spiral grooved multiple twisted tube 10 formed through the above-described process, and a larger twist angle is obtained. May be given. In this case, heat treatment (annealing) is performed on the inner spiral grooved multiple twisted tube 10 that has undergone the above-described steps. Furthermore, it winds around the unwinding bobbin 11, and this unwinding bobbin 11 is attached to the manufacturing apparatus A which has the 1st drawing die which has a suitable diameter reduction rate, and a 2nd drawing die. Furthermore, the multi-twisted tube with the inner surface spiral groove having a larger twist angle can be manufactured by performing the same steps (first twist drawing step and second twist drawing step) as those described above by the manufacturing apparatus A. .

  According to the drawing twisting process of this embodiment, since the diameter is reduced simultaneously with the twisting, the outer diameter and the cross-sectional area of the starting material and the final product are different. In addition, since a combined stress of twisting and reducing diameter is applied to the pipe material, it becomes possible to reduce the shear stress necessary for the twisting process, and before the buckling stress of the pipe material 5 is reached, a large twist is applied to the pipe material 5. it can. Therefore, a heat transfer tube having a fin with a large lead angle (first fin 46 and second fin 47) and rib portion 43 and a thin bottom wall can be manufactured without causing buckling. The inner spiral grooved multiple twisted tube 10 can increase the heat exchange efficiency by increasing the lead angle of the fins (the first fin 46 and the second fin 47) and the rib portion 43. Further, the inner spiral grooved multiple twisted tube 10 can be reduced in weight by reducing the thickness of the bottom wall and reducing the material cost. That is, according to the present embodiment, it is possible to manufacture the multi-twisted tube 10 with the inner surface spiral groove that is lightweight, inexpensive, and has high heat exchange efficiency.

  According to the drawing torsion process of the present embodiment, a twist is applied to the straight grooved multiple tube 10B and the diameter is reduced, so that a large twist angle can be applied while suppressing the occurrence of buckling. In the present embodiment, the outer diameter of the straight grooved multiple tube 10B as the material is 1.1 times or more than the outer diameter of the inner spiral grooved multiple twisted tube 10 as the final product.

According to the drawing twisting process of the present embodiment, the tube material 5 is twisted by the first revolving capstan 21 between the first drawing die 1 and the second drawing die 2. Furthermore, the drawing directions of the first drawing die 1 and the second drawing die 2 are reversed. Thereby, the twist can be imparted to the tube material 5 by matching the twist directions in the first twist pulling process and the second twist pulling process. Further, it is not necessary to revolve the unwinding bobbin 11 that is the starting end of the pipe line of the pipe material 5 and the winding bobbin 71 that is the terminal end of the pipe line. Since the speed of the line depends on the rotational speed, the rotational speed can be easily increased in the drawing and twisting process of the present embodiment in which the unwinding bobbin 11 or the winding bobbin 71 which is a heavy object is not rotated. That is, according to this embodiment, the line speed can be easily increased.
Furthermore, in this embodiment, since the unwinding bobbin 11 is not revolved, a long straight grooved multiple tube 10B (tubing material 5) can be wound around the unwinding bobbin 11. For this reason, according to the drawing twist process of this embodiment, without twisting out the unwinding bobbin 11, a twist can be imparted to the long tubular material 5 at once. That is, according to the present embodiment, mass production of the multi-twisted tube 10 with the inner spiral groove becomes easy.

  The drawing and twisting process of the present embodiment imparts twist to the tube material 5 through at least two twisting and drawing processes. For this reason, the twist angle provided by the twist extraction process of each step can be piled up and a big twist angle can be provided.

  According to the drawing torsion process of the present embodiment, a front tension and a rear tension are applied to the tube material 5 in the first twist drawing process and the second twist drawing process. The front tension is applied to the pipe material 5 by the second guide capstan 61, and the rear tension is applied to the pipe material 5 by the brake portion 15 that brakes the unwinding bobbin 11. Thereby, an appropriate tension can be stably applied to the pipe material 5 to be processed. Since there is no slack in the pipe line of the pipe material 5 and the straight grooved multiple pipe 10B enters the drawing die without being misaligned, a stable twist angle can be imparted without causing the pipe material 5 to buckle or break.

  In the present embodiment, the centers of the first drawing die 1 and the second drawing die 2 die hole are located on the revolution rotation center axis C. Thereby, since the pipe material 5 passing through the die hole can be arranged linearly with respect to the die hole, the pipe material 5 can be uniformly reduced in diameter, and buckling at the time of applying a twist can be suppressed. In the first drawing die 1 and the second drawing die 2, the die hole is allowed to be misaligned with respect to the revolution rotation center axis C as long as the tube material 5 can be normally reduced in diameter.

  In the present embodiment, the unwinding bobbin 11 is supported by the floating frame 34 and the winding bobbin 71 is installed on the ground G. However, either the unwinding bobbin 11 or the winding bobbin 71 may be supported by the floating frame 34. That is, in FIG. 6, the unwinding bobbin 11 and the winding bobbin 71 may be replaced with each other. In this case, the conveyance path of the pipe material 5 is reversed. In addition, the first drawing die 1 and the second drawing die 2 are replaced and arranged, and the drawing directions of the respective drawing dies 1 and 2 are reversed along the conveying direction. Further, in the capstans positioned before and after the drawing dies 1 and 2, the capstan located after the drawing dies is driven in the winding direction (conveying direction) of the pipe material, and the front tension against the pulling force in the drawing dies is obtained. give.

  In the present embodiment, as a method for manufacturing the heat transfer tube 10, a case has been described in which a manufacturing method in which twisting is performed twice by the first drawing step and the second drawing step is employed. However, the heat transfer tube 10 of this embodiment may be manufactured by adopting a manufacturing process having only the first twist drawing process. Such a manufacturing process is disclosed in Japanese Unexamined Patent Application Publication No. 2016-22505.

  Although various embodiments of the present invention have been described above, each configuration in each embodiment and combinations thereof are examples, and addition, omission, replacement, and configuration of configurations are within the scope without departing from the spirit of the present invention. Other changes are possible. Further, the present invention is not limited by the embodiment.

  5R, 10, 110 ... heat transfer tubes (multi-twisted tubes with inner spiral grooves), 10a, 42b ... outer peripheral surface, 10B ... multi-tubes with straight grooves (extrusion element tubes), 41 ... first tube portion, 41a, 42a ... Inner peripheral surface, 42 ... second pipe part, 43 ... rib part, 44 ... space, 46 ... first fin (fin), 46 g ... first groove (groove), 47 ... second fin (fin) , 47 g ... second groove (groove)

Claims (5)

It is a multi-twisted tube with an inner spiral groove that is a twisted material of an extruded element tube,
A first pipe section;
A second tube disposed inside the first tube;
A plurality of partitions that connect the inner peripheral surface of the first tube portion and the outer peripheral surface of the second tube portion to divide a space between the first tube portion and the second tube portion into a plurality of flow paths. And a rib part of
At least one of the inner peripheral surface of the first tube portion, the inner peripheral surface of the second tube portion, and the outer peripheral surface of the second tube portion has a plurality of fins arranged in the circumferential direction. Provided,
A groove is formed between the fins,
The rib part and the fin extend spirally along the axial direction.
Multiple twisted tube with inner spiral groove. A plurality of the inner circumferential surfaces of the second pipe portion and the outer circumferential surface of the second pipe portion and the inner circumferential surface of the first pipe portion are arranged along the circumferential direction, respectively. Fins are provided,
The multiple twisted tube with an inner surface spiral groove according to claim 1. The lead angle of twisting on the outer peripheral surface of the inner spiral grooved multiple twisted tube is 10 ° or more and 80 ° or less,
The multiple twisted tube with an inner surface spiral groove according to claim 1 or 2. A plurality of the fins arranged along the circumferential direction is 15 or more.
The multiple twisted tube with an inner surface spiral groove according to any one of claims 1 to 3. The height of the fin provided in the first pipe part is 20% or more and 80% or less with respect to the bottom wall thickness of the first pipe part,
The height of the fin provided in the second pipe part is 20% or more and 80% or less with respect to the bottom wall thickness of the second pipe part.
The multiple twisted tube with an inner surface spiral groove according to any one of claims 1 to 4.

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