JP7031921B1 - Cylindrical heater manufacturing method and jig for tubular heater manufacturing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular heater or the like having improved heating efficiency of a fluid to be heated. SOLUTION: A tubular heater 10 having a heating element having a cylindrical outer shape is wound by a first winding diameter, a first coil portion 12a, and a second winding diameter larger than the first winding diameter. The cross section of the heating element contained in the first coil portion and the second coil portion in the cross section seen by cutting in a plane including the central axis A of the first coil portion and having the second coil portion 12b wound by the first coil portion. The cross sections of the heating elements included in the above are arranged alternately along the central axis direction. [Selection diagram] FIG. 8

Description

The present invention relates to a method for manufacturing a tubular heater and a jig for manufacturing a tubular heater.

The sheathed heater is a tubular resistance-heating electric heater in which a heating wire is housed inside a sheath, which is a tubular member, and is filled with an insulator powder such as magnesia.
The sheathed heater has excellent electrical insulation and can safely heat the fluid to be heated, and can also be used at a high temperature by appropriately selecting the material.
Further, by bending the sheath, it is possible to form the heat generating portion into an arbitrary shape according to the installation space.

As a prior art relating to a fluid heater that heats a fluid to be heated by a sheathed heater, for example, Patent Document 1 describes a sheathed heater having a spirally wound coil portion inside a tubular body through which the fluid to be heated is passed. A gas heater containing the above is described.

Japanese Unexamined Patent Publication No. 2004-69256

In the technique described in Patent Document 1 described above, since the winding diameter of the coil portion in which the sheath is spirally wound in the sheathed heater is uniform, when the coil portion is arranged in the flow path, the sheath is wound. In some cases, only a part of the surface layer portion along the flow direction of the flow path contributes effectively to the heating of the fluid to be heated on the outer peripheral surface of the above.
Therefore, it is required to expand the effective contact area between the outer peripheral surface of the tubular heater and the fluid to be heated to improve the heating efficiency of the fluid to be heated.
In view of the above-mentioned problems, an object of the present invention is to provide a method for manufacturing a tubular heater and a jig for manufacturing a tubular heater, which can easily manufacture a tubular heater having improved heating efficiency of a fluid to be heated. That is.

In order to solve the above-mentioned problems, the method for manufacturing a tubular heater according to the first aspect of the present invention is a method for manufacturing a tubular heater including a heating element having a cylindrical outer shape, and is formed in a shaft shape. A ridge portion spirally wound so as to protrude from the outer peripheral surface of the core material is provided around the core material, and the ridge portion is cut along a plane including the central axis of the core material. The cross section is arranged so as to have a gap in the central axis direction, and the first portion of the heating element is wound around the gap of the ridge portion to form the first coil portion, and the outer peripheral surface of the ridge portion is formed. The second coil portion having a larger winding diameter than the first coil portion is formed by winding the second portion of the heating element along the above.
According to this, by winding the first part and the second part of the heating element along the gap of the ridge portion and the protrusion end surface of the ridge portion, respectively, the first coil portion and the second coil portion can be accurately aligned. It can be easily formed with a large winding diameter.
Further, the shape accuracy in the pitch direction can be improved by the ridge portion functioning as a guide for guiding the pitch (sheath spacing in the central axis direction) around which each heating element is wound.
In the tubular heater manufactured by the invention of the first aspect, the first coil portion and the second coil portion having different winding diameters are arranged in a so-called double helix (two-row winding) to provide a fluid to be heated. When flowing in the direction of the central axis of each coil portion, the fluid to be heated passes in a zigzag manner so as to avoid the heating elements arranged in a stepped manner.
As a result, the fluid to be heated wraps around along the outer peripheral surface of the heating element, and comes into contact with each heating element in a wide range in the circumferential direction. Therefore, the area of the effective contact surface (fluid contact surface) between the fluid to be heated and the heating element can be expanded, and the heating efficiency of the fluid to be heated can be improved.
Further, by generating a turbulent flow in the flow of the fluid to be heated in the flow path, heat transfer from the heating element to the fluid to be heated can be promoted, and the heating efficiency can be further improved.
In the invention of the first aspect, the tubular heater may be configured as a sheathed heater in which a heating wire and an insulator powder are housed inside a cylindrical sheath.

In the invention of the first aspect, the first part and the second part of the heating element are integrally formed so as to be continuous via a folded portion formed in the middle portion of the heating element. can do.
According to this, it is easy without increasing the number of parts , heating power in the case of an electric heater, and the number of terminals for supplying a heat medium in the case of a heat generator (heat exchanger) using a fluid as a heat medium . Can be configured as such.

In the invention of the first aspect, after the first coil portion and the second coil portion are formed, the ridge portion is rotated around the central axis of the core material with respect to the first coil portion and the second coil portion. The ridge portion can be removed from the first coil portion and the second coil portion by rotating the ridge portion relative to the first coil portion.
According to this, after the first coil portion and the second coil portion are formed, the ridge portion can be easily removed by relatively rotating the ridge portion.
In particular, the ridge portion is not easily damaged during removal, and the jig for manufacturing a tubular heater can be reused.

In the invention of the first aspect, the ridge portion may be formed by a three-dimensional modeling method in which a plurality of layered objects are laminated along the central axis direction of the core material.
According to this, when the heating element is wound in a "happiness" shape so as to straddle the interface on which the layered shaped objects are laminated, and the ridge portion is formed by the three-dimensional modeling method, the interface is excessive. It is possible to prevent the action of internal force and prevent the ridge portion from being damaged.

In the invention of the first aspect, the ridge portion may be made of a material having a lower elastic modulus than the material of the heating element.
According to this, after the first coil portion and the second coil portion are formed, the ridge portion can be elastically deformed and easily removed.

In order to solve the above-mentioned problems, the jig for manufacturing a tubular heater according to the second aspect of the present invention is used for manufacturing a tubular heater having a heating element having a cylindrical outer shape. It is a jig and has a ridge portion that is spirally wound and arranged so as to protrude from the outer peripheral surface of the core material around a core material formed in a shaft shape, and the ridge portion is provided. It is characterized in that the cross section cut in a plane including the central axis of the core material is arranged so as to have a gap in the central axis direction.
In the invention of the second aspect, the tubular heater may be configured as a sheathed heater in which a heating wire and an insulator powder are housed inside a cylindrical sheath.
In the invention of the second aspect, the ridge portion may be formed by a three-dimensional modeling method in which a plurality of layered objects are laminated along the central axis direction of the core material.
In the invention of the second aspect, the ridge portion may be made of a material having a lower elastic modulus than the material of the heating element.
In each of these inventions, the same effect as that of the invention of the first aspect described above can be obtained.

As described above, according to the present invention, there is provided a method for manufacturing a tubular heater and a jig for manufacturing a tubular heater, which can easily manufacture a tubular heater with improved heating efficiency of the fluid to be heated. be able to.

It is sectional drawing of the fluid heater which has the tubular heater (seeds heater) manufactured by the embodiment of the manufacturing method of the tubular heater to which this invention is applied. It is a figure which shows the jig for manufacturing the sheathed heater used for manufacturing the sheathed heater of an embodiment. It is a figure which shows the state which attached the jig for manufacturing a sheathed heater of FIG. 2 to a core material. It is a figure which shows the state of the sheath before being wound around a jig for manufacturing a sheathed heater of FIG. 2 and a core material. It is a figure which shows the state which the sheath is wound around the core material of FIG. 3 and the jig for manufacturing a sheathed heater. It is sectional drawing of the fluid heater which is a comparative example of this invention. It is a figure which shows typically the flow of the fluid to be heated around the coil part of the sheathed heater in the fluid heater of the comparative example. It is a figure which shows typically the flow of the fluid to be heated around the coil part of the sheathed heater in the fluid heater of an embodiment.

<Embodiment>
Hereinafter, a method for manufacturing a tubular heater and an embodiment of a jig for manufacturing a tubular heater to which the present invention is applied will be described.
The tubular heater of the embodiment is a sheathed heater used as a heat source of a fluid heater for heating various fluids to be heated such as various gases, steams, liquids, and gas-liquid mixed fluids.

FIG. 1 is a cross-sectional view of a fluid heater having a tubular heater (seeds heater) manufactured by the method for manufacturing a tubular heater of the embodiment, and includes a central axis A of the first cylinder 110 of the case 100 and the like. It is a figure which shows the state which we cut in a plane and see.
The fluid heater 1 includes a sheathed heater 10, a case 100, and the like.

The sheathed heater 10 arranges, for example, a heating wire made of a nichrome-based metal along the longitudinal direction of the sheath, which is a cylindrical member (cylindrical body) made of a metal such as a stainless steel alloy. At the same time, it is configured by enclosing an insulator powder such as magnesia inside the sheath.
The sheathed heater 10 is a kind of a tubular heater provided with a heating element having a tubular outer shape.
The sheathed heater 10 has a loop portion 11, a coil portion 12, a folded portion 13, a straight portion 14, a lead-out portion 15, and the like.

The sheathed heater 10 is integrally configured, for example, by bending a sheathed heater having one sheath.
The loop portion 11 is an arc-shaped portion (folded portion) formed by winding a sheath around, for example, a shaft-shaped member in an intermediate portion in the longitudinal direction of the sheathed heater 10.
The loop portion 11 is used to lock and temporarily fix one end portion when the coil portion 12 is bent (wound).

The coil portion 12 is a portion in which two sheaths extending from both ends of the arc shape of the loop portion 11 are wound in a double helix around a core material and a jig for manufacturing a sheathed heater, which will be described later.
The coil portion 12 has a first coil portion 12a and a second coil portion 12b.
As shown in FIG. 1, the first coil portion 12a and the second coil portion 12b have a central axis A (in a state of being incorporated in the fluid heater 1) of the winding diameters of the first coil portion 12a and the second coil portion 12b. In a cross section cut along a plane including the central axis A of the cylinder 110 or the like), the cross section of the sheath included in the first coil portion 12a and the cross section of the sheath included in the second coil portion 12b are the centers. They are arranged in a so-called double spiral, which is alternately arranged along the axis A direction (the winding axis direction of the coil).
A gap through which the fluid to be heated can pass is formed between the cross section of the sheath included in the first coil portion 12a and the cross section of the sheath included in the second coil portion 12b.
The winding diameter of the second coil portion 12b is larger than the winding diameter of the first coil portion 12a.
The method for manufacturing the coil portion 12 and the like will be described in detail later.

The folded-back portion 13 is provided at an end portion of the coil portion 12 opposite to the loop portion 11 side, and is a curved portion that is folded back so that the sheath passes through the winding diameter outer diameter side of the coil portion 12 and returns to the loop portion 11 side. ..
The straight portion 14 is a linear portion extending from the end portion of the folded portion 13 opposite to the coil portion 12 side and extending in parallel with the winding axis direction of the coil portion 12.
The lead-out portion 15 is provided at an end portion of the straight portion 14 opposite to the folded-back portion 13 side, and is a portion protruding from the inlet side flange 140 to the outside of the case 100.
The tip of the lead-out portion 15 is provided with a pair of terminal portions connected to the heating power source of the sheathed heater 10.

The case 100 includes a first cylinder 110, a second cylinder 120, a third cylinder 130, an inlet side flange 140, an outlet side flange 150, an inlet pipe 160, an outlet pipe 170, and the like.
Unless otherwise specified, each component of the case 100 is made of a heat-resistant metal material such as a stainless steel alloy, and each component is joined by welding.

The first cylinder 110 is a cylindrical member constituting the outer surface portion of the case 100.
The second cylinder 120 is a cylindrical member arranged concentrically with the central axis A of the first cylinder 110 on the inner diameter side of the first cylinder 110.
Both ends of the second cylinder 120 are arranged so that the positions in the central axis A direction are inside the case 100 with respect to both ends of the first cylinder 110.
The inner peripheral surface of the first cylinder 110 and the outer peripheral surface of the second cylinder 120 are arranged so as to face each other with a distance in the radial direction of each cylinder.
The inner peripheral surface of the first cylinder 110 and the outer peripheral surface of the second cylinder 120 form a part of the flow path through which the fluid to be heated flows.
The end of the second cylinder 120 on the inlet pipe 160 side (left side in FIG. 1) is closed by the end face 121.
The end face 121 is a disk-shaped member along a plane orthogonal to the central axis A of the second cylinder 120.

The third cylinder 130 is a cylindrical member arranged concentrically with the first cylinder 110 and the second cylinder 120 on the inner diameter side of the second cylinder 120.
The end portion of the third cylinder 130 on the inlet pipe 160 side is arranged so as to face the end surface 121 of the second cylinder 120 at a distance from each other.
The end of the third cylinder 130 on the outlet pipe 170 side is joined in a state of being abutted against the outlet side flange 150.
The inner peripheral surface of the second cylinder 120 and the outer peripheral surface of the third cylinder 130 are arranged so as to face each other with a distance in the radial direction of each cylinder.
The space between the inner peripheral surface of the second cylinder 120 and the outer peripheral surface of the third cylinder 130 and the inner diameter side of the third cylinder 130 form a part of the flow path through which the fluid to be heated flows.

The coil portion 12 (first coil portion 12a, second coil portion 12b) of the sheathed heater 10 is arranged between the outer peripheral surface of the third cylinder 130 and the inner peripheral surface of the second cylinder 120.
The coil portions 12 are arranged at intervals in the radial direction of the outer peripheral surface of the third cylinder 130, the inner peripheral surface of the second cylinder 120, and the second cylinder 120 and the third cylinder 130.
Further, the straight portion 14 of the sheathed heater 10 is arranged between the outer peripheral surface of the second cylinder 120 and the inner peripheral surface of the first cylinder 110.

The inlet-side flange 140 is an end face provided so as to close the end opening on the inlet pipe 160 side of the first cylinder 110.
The inlet side flange 140 is a disk-shaped member along a plane orthogonal to the central axis A of the first cylinder 110.
An opening to which the inlet pipe 160 is connected is provided in the central portion of the inlet side flange 140.

The outlet side flange 150 is an end surface provided so as to close the end opening on the outlet pipe 170 side of the first cylinder 110.
The outlet side flange 150 is a disk-shaped member along a plane orthogonal to the central axis A of the first cylinder 110.
An opening to which the outlet pipe 170 is connected is provided in the central portion of the outlet side flange 150.

The inlet pipe 160 is a pipeline in which the fluid to be heated is introduced into the fluid heater 1.
The inlet pipe 160 is a cylindrical member concentric with the central axis of the first cylinder 110.
The inlet pipe 160 projects from the flange 140 on the inlet side to the outside of the case 100.
The end of the inlet pipe 160 on the inlet side flange 140 side is connected to an opening provided in the inlet side flange 140.
The inlet pipe 160 is made to communicate with the inner diameter side of the first cylinder 110, and has a function of introducing the fluid to be heated into the inside of the first cylinder 110.

The outlet pipe 170 is a pipeline through which the heated fluid after heating flows out from the fluid heater 1.
The outlet pipe 170 is a cylindrical member concentric with the central axis of the first cylinder 110.
The outlet pipe 170 projects from the outlet side flange 150 to the outside of the case 100.
The end of the outlet pipe 170 on the exit side flange 150 side is connected to an opening provided in the outlet side flange 150.

In FIG. 1, the flow F along the flow path of the fluid to be heated is shown by a broken line arrow.
First, the fluid to be heated is introduced from the inlet pipe 160 to the inner diameter side of the first cylinder 110 through the opening of the inlet side flange 140.
After that, the fluid to be heated travels toward the outer diameter side of the first cylinder 110 along the end surface 121 of the second cylinder 120, and passes between the inner peripheral surface of the first cylinder 110 and the outer peripheral surface of the second cylinder 120. To the exit side flange 150 side.

Between the inner peripheral surface of the first cylinder 110 and the outer peripheral surface of the second cylinder 120, the fluid to be heated is heated by heat transfer or the like from the outer peripheral surface of the second cylinder 120, but with respect to the downstream side thereof. , It is in a relatively low temperature state.
The fluid to be heated reverses the traveling direction in the vicinity of the outlet side flange 150 and flows in between the inner peripheral surface of the second cylinder 120 and the outer peripheral surface of the third cylinder 130.

The heated fluid that has entered between the inner peripheral surface of the second cylinder 120 and the outer peripheral surface of the third cylinder 130 flows toward the flange 140 on the inlet side, while the coil portion 12 of the sheathed heater 10 (first coil portion 12a). , The second coil portion 12b) is contacted and further heated.
After that, the fluid to be heated reverses the traveling direction again in the vicinity of the end face 121 of the second cylinder 120 and flows into the inner diameter side of the third cylinder 130.
The heated fluid passes through the inside of the third cylinder 130 and flows into the outlet pipe 170. At this time, the heated fluid is further passed through the inner peripheral surface of the third cylinder 130 by the coil portion 12 of the sheathed heater 10. It is heated and warms up.

Hereinafter, the manufacturing method and the manufacturing jig of the sheathed heater 10 (cylindrical heater) described above will be described.
The first coil portion 12a and the second coil portion 12b of the coil portion 12 of the sheathed heater 10 are, for example, a cylindrical core material 300 (see FIGS. 3, 5, etc.) and a jig for manufacturing a sheathed heater (cylinder) described below. It is formed by winding the first part and the second part of the sheath folded back in the middle part with the state heater manufacturing jig () 200 attached.
FIG. 2 is a diagram showing a jig for manufacturing a sheathed heater used for manufacturing the sheathed heater of the embodiment.

The sheathed heater manufacturing jig 200 of the embodiment has a ridge portion 210 having a spiral shape (coil shape).
The cross section of the ridge portion 210 cut along a plane including the central axis A such as the first cylinder 110 of the fluid heater 1 is formed in a rectangular shape having a long axis direction along the central axis A direction.
Here, a gap 220 is provided in the direction of the central axis A between a certain cross section and another cross section displaced by one pitch (one turn).

The ridge portion 210 has an outer peripheral surface 211, an inner peripheral surface 212, an end surface 213, and the like.
The outer peripheral surface 211 is a surface portion on the winding diameter outer diameter side of the ridge portion 210.
The outer peripheral surface 211 is a convex curved surface having a cylindrical outer peripheral surface concentric with the central axis A.
The inner peripheral surface 212 is a surface portion on the inner diameter side of the winding diameter of the ridge portion 210.
The inner peripheral surface 212 is a concave curved surface having a cylindrical inner peripheral surface concentric with the central axis A.
The curvature of the inner peripheral surface 212 is equal to the curvature of the outer peripheral surface of the core material 300.
The end surface 213 faces the central axis A direction, and is a surface portion connecting the outer peripheral surface 211 and the inner peripheral surface 212.

The sheathed heater manufacturing jig 200 can be formed by, for example, using a known 3D printer and a three-dimensional modeling method in which a plurality of layered objects made of a resin-based material are laminated.
At this time, the direction in which the plurality of layered objects are laminated can be the direction along the central axis A.
Further, the sheathed heater manufacturing jig 200 is made of a flexible material having a lower elastic modulus than the sheath material of the sheathed heater 10 (for example, a metal material such as a heat-resistant stainless alloy) and easily elastically deformed. Can be done.

FIG. 3 is a diagram showing a state in which the jig for manufacturing the sheathed heater of FIG. 2 is attached to the core material.
The core material 300 is a columnar member made of a metal material such as steel.
The core material 300 is used in a state of being inserted into the inner diameter side of the sheathed heater manufacturing jig 200.
The inner peripheral surface 212 of the ridge portion 210 of the sheathed heater manufacturing jig 200 is arranged so as to be in surface contact with the outer peripheral surface of the core material 300.
As a result, the ridge portion 210 functions as a ridge (a strip-shaped portion protruding so as to extend along a predetermined longitudinal direction (in this case, a spiral shape)) protruding from the outer peripheral surface of the core material 300.
At this time, a part of the outer peripheral surface of the core material 300 is exposed through the gap 220.
The coil portion 12 of the sheathed heater 10 is formed by winding the sheath around the core material 300 and the sheathed heater manufacturing jig 200 in this state.

FIG. 4 is a diagram showing a state of the sheath before being wound around the sheathed heater manufacturing jig and the core material of FIG. 2.
In the sheath S10 after encapsulating the heating wire and the insulator powder, first, a loop portion 11 curved in an arc shape is formed by winding an intermediate portion in the longitudinal direction around a shaft-shaped body (not shown).
From both ends of the loop portion 11, the first portion S11 and the second portion S12 of the sheath S10 in a straight state extend substantially in parallel.
The first part S11 and the second part S12 become the first coil part 12a and the second coil part 12b by the processing described below.

FIG. 5 is a diagram showing a state in which a sheath is wound around the core material of FIG. 3 and the jig for manufacturing a sheathed heater.
The first part S11 is spirally wound directly around the outer peripheral surface of the core material 300 along the gap 220 of the sheathed heater manufacturing jig 200. As a result, the first coil portion 12a is formed from the first portion S11.
The second part S12 is spirally wound along the outer peripheral surface 211 of the ridge portion 210. As a result, the second coil portion 12b is formed from the second portion S12.
At this time, the winding diameter of the second coil portion 12b increases by the diameter difference between the outer peripheral surface 211 and the inner peripheral surface 212 of the ridge portion 210.
After forming the first coil portion 12a and the second coil portion 12b, the ridge portion 210 of the sheathed heater manufacturing jig 200 is used alone or with respect to the first coil portion 12a and the second coil portion 12b. Together with the core material 300, it is relatively rotated around the central axis A.
As a result, the ridge portion 210 of the sheathed heater manufacturing jig 200 is fed out from the first coil portion 12a and the second coil portion 12b in a screw shape along the central axis A and is removed.
At this time, since the ridge portion 210 is made of a resin-based material having a relatively low elastic modulus, it exhibits elastic deformation such as compression deformation in response to input from the sheath, is difficult to be caught in each coil, and is removed. Is facilitated.

Hereinafter, the effect of the fluid heater having the tubular heater manufactured by the method for manufacturing the tubular heater of the above-described embodiment will be described in comparison with the comparative example of the present invention described below.
FIG. 6 is a cross-sectional view of a fluid heater of a comparative example.
In the comparative example, the parts common to the above-described embodiment are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.
The fluid heater 1 of the comparative example is provided with a coil portion 16 having a single winding diameter instead of the coil portion 12 of the embodiment.

FIG. 7 is a diagram schematically showing the flow of the fluid to be heated around the coil portion of the sheathed heater in the fluid heater of the comparative example.
In the comparative example, the sheaths constituting the coil portion 16 are arranged with the same winding diameter for each predetermined winding pitch.
Therefore, the main component in the flow F of the fluid to be heated passes, for example, substantially linearly along the winding diameter outer diameter side of the coil portion 16.
In this case, on the outer peripheral surface of the sheath, only a relatively narrow portion on the winding diameter outer diameter side of the coil portion 16 contributes as an effective fluid contact surface CA.
In addition, the formation of turbulent flow around the coil portion 16 is also suppressed.

FIG. 8 is a diagram schematically showing the flow of the fluid to be heated around the coil portion of the sheathed heater in the fluid heater of the embodiment.
In the embodiment, the first coil portion 12a and the second coil portion 12b having a larger winding diameter than the first coil portion 12a are alternately arranged along the winding pitch direction (center axis A direction). Therefore, as shown in FIG. 8, the main component of the flow F of the fluid to be heated passes alternately on the winding diameter outer diameter side of the first coil portion 12a and the winding diameter inner diameter side of the second coil portion 12b. , Will progress in a zigzag pattern.
As a result, on the outer peripheral surface of the sheath, the fluid contact surface CA that contributes to the heating of the fluid to be heated is expanded as compared with the comparative example.
Further, turbulence of the flow F of the fluid to be heated is promoted.

According to the embodiment described above, the following effects can be obtained.
(1) By arranging the first coil portion 12a and the second coil portion 12b having different winding diameters in a double helix, when the fluid to be heated flows in the direction of the central axis A, the fluid to be heated flows to each coil. It will pass in a zigzag manner so as to avoid the sheath that constitutes the part.
As a result, the fluid to be heated wraps around the outer peripheral surface of the sheath, and comes into contact with each sheath in a wide range in the circumferential direction.
Therefore, the effective fluid contact surface CA between the fluid to be heated and the sheath can be expanded, and the heating efficiency of the fluid to be heated by the sheathed heater 10 and the fluid heater 1 can be improved.
Further, since the turbulent flow F of the fluid to be heated is promoted, the heating efficiency can be further improved.
(2) Since the first coil portion 12a and the second coil portion 12b of the sheathed heater 10 are integrally formed so as to be continuous via the loop portion 11 formed in the intermediate portion of the sheath, the number of parts and the number of parts can be increased. The configuration can be simplified without increasing the number of terminals for supplying heating power.
Further, the fluid heater 1 can be easily incorporated into the case 100 and positioned.
(3) In the cross section seen by cutting in a plane including the central axis A, the cross section of the sheath included in the first coil portion 12a and the cross section of the sheath included in the second coil portion 12b are arranged at intervals. As a result, the heated fluid flows between the sheaths included in the first coil portion 12a and the second coil portion 12b, so that the above-mentioned effect of improving the heating efficiency can be surely obtained.
(4) A part of the flow path through which the fluid to be heated flows is the inner peripheral surface of the second cylinder 120 (outer cylinder) accommodating the first coil portion 12a and the second coil portion 12b on the inner diameter side, and the first. By providing the structure between the outer peripheral surface of the third cylinder 130 (inner cylinder) inserted into the inner diameter side of the coil portion 12a and the second coil portion 12b, the inner peripheral surface of the second cylinder 120 and the third cylinder portion 120 are provided. The above-mentioned heating is surely generated so that the fluid to be heated flows in a zigzag shape between the outer peripheral surface of the cylinder 130 and between the sheaths of the first coil portion 12a and the second coil portion 12b of the sheathed heater 10. The effect of improving efficiency can be promoted.
(5) The first portion S11 and the second portion S12 of the sheath S10 are provided along the gap 220 of the ridge portion 210 of the sheathed heater manufacturing jig 200 and the outer peripheral surface (protrusion surface) 211 of the ridge portion 210. By winding each of them, the first coil portion 12a and the second coil portion 12b can be easily formed with an accurate winding diameter.
Further, the ridge portion 210 functions as a guide for guiding the pitch (sheath spacing in the central axis A direction) around which the first portion S11 and the second portion S21 of the sheath S10 are wound, so that the shape accuracy in the pitch direction is also improved. be able to.
(6) After the first coil portion 12a and the second coil portion 12b are formed, the ridge portion 210 is removed by relatively rotating the ridge portion 210 around the central axis A with respect to each coil to remove the sheathed heater manufacturing jig 200. It can be easily removed from the coil portion 12.
In particular, the ridge portion 210 is less likely to be damaged during removal, and the sheathed heater manufacturing jig 200 can be reused.
(7) By forming the sheathed heater manufacturing jig 200 by a three-dimensional modeling method in which a plurality of layered shaped objects are laminated along the central axis A direction, a sheath is formed so as to straddle the interface on which the layered shaped objects are laminated. The first part S11 and the second part S12 of S10 will be wound in a "jag" shape, and when the ridge portion 210 is formed by the three-dimensional modeling method, excessive inside at the interface when the sheath is wound. It is possible to prevent the force from acting and prevent the protrusion 210 from being damaged.
(8) Since the ridge portion 210 is made of a material having a lower elastic modulus than the material of the sheath S10, after the first coil portion 12a and the second coil portion 12b are formed, the ridge portion 210 is elastically deformed to form the coil portion. It can be easily removed from 12.

(Modification example)
The present invention is not limited to the embodiments described above, and various modifications and changes can be made, and these are also within the technical scope of the present invention.
(1 ) The specific configuration of the tubular heater manufacturing method, the tubular heater manufacturing jig, the tubular heater manufactured using these, and the fluid heater shall be limited to each of the above-described embodiments. It is possible to change it as appropriate.
For example, the structure, shape, material, manufacturing method, quantity, arrangement, etc. of each member can be appropriately changed from the configuration of each embodiment.
(2) In the above -mentioned fluid heater, the cross-sectional shape of the first cylinder, the second cylinder, and the third cylinder is, for example, a circle (perfect circle), but the tubular heater manufactured by the present invention is limited to this. However, it can also be applied to a fluid heater having a flow path member having a cross-sectional shape of, for example, an ellipse, a rectangle, or another shape.
Further, the configurations of the case and the flow path are not limited to those having a triple cylinder structure as in the embodiment, and can be appropriately changed.
(3) In the embodiment, the jig for manufacturing a tubular heater is formed by, for example, a three-dimensional modeling method using a resin-based material, but the material and manufacturing method of the jig for manufacturing a tubular heater are not limited to this and are appropriate. Can be changed.
For example, a plate or tube material made of a flexible material such as rubber, a resin molded product, a relatively soft metal material, or the like may be formed into a spiral strip or the like.
Further, in each embodiment, a jig for manufacturing a tubular heater, which is a separate component, is attached to the cylindrical core material, but the jig for manufacturing a tubular heater is not limited to this, and the jig for manufacturing a tubular heater is a ridge portion and a core. It may be configured to be integrally formed with the material.
(4 ) In the embodiment , the first coil portion and the second coil portion of the tubular heater, and the cylinders constituting the case of the fluid heater are concentrically arranged so as to share the central axis A. However, the present invention is not limited to this, and the central axis of each member may be offset or may be arranged with a minute inclination angle.
(5) In the embodiment, the tubular heater is a sheathed heater as an example, but the present invention is not limited to this, for example, in a flow path made of a tubular body, high temperature oil, water, etc. with respect to the fluid to be heated, etc. It may have a heating element that allows the liquid or gas to flow as a heat medium.

1 Fluid Heater (Embodiment) 1A Fluid Heater (Comparative Example)
10 Seeds heater 11 Loop part 12 Coil part 12a 1st coil part 12b 2nd coil part 13 Folded part 14 Straight part 15 Derivation part 16 Coil part (comparative example)
100 Case 110 1st cylinder 120 2nd cylinder 121 End face 130 3rd cylinder 140 Inlet side flange 150 Outlet side flange 160 Inlet pipe 170 Outlet pipe F Flow of fluid to be heated 200 Seeds heater manufacturing jig 210 Protruding part 211 Outer peripheral surface 212 Inner peripheral surface 213 End surface 300 Core material S10 Sheath S11 Part 1 S12 Part 2 A Central axis CA Fluid contact surface

Claims (10)

A method for manufacturing a tubular heater having a heating element having a cylindrical outer shape.
Around the core material formed in a shaft shape, a ridge portion spirally wound so as to protrude from the outer peripheral surface of the core material is provided.
The ridge portion is arranged so that the cross section cut in a plane including the central axis of the core material has a gap in the central axis direction.
The first part of the heating element is wound along the gap of the ridge portion to form a first coil portion, and the second part of the heating element is wound along the outer peripheral surface of the ridge portion. A method for manufacturing a tubular heater, which comprises forming a second coil portion having a winding diameter larger than that of the first coil portion. The method for manufacturing a tubular heater according to claim 1 , wherein the tubular heater is a sheathed heater in which a heating wire and an insulator powder are housed inside a cylindrical sheath. 1 . Item 2. The method for manufacturing a tubular heater according to Item 2. After forming the first coil portion and the second coil portion, the ridge portion is relatively rotated around the central axis of the core material with respect to the first coil portion and the second coil portion. The method for manufacturing a tubular heater according to any one of claims 1 to 3 , wherein the ridge portion is removed from the first coil portion and the second coil portion. The one according to any one of claims 1 to 4 , wherein the ridge portion is formed by a three-dimensional modeling method in which a plurality of layered shaped objects are laminated along the central axis direction of the core material. The method for manufacturing a tubular heater according to the description. The method for manufacturing a tubular heater according to any one of claims 1 to 5 , wherein the ridge portion is made of a material having a modulus of elasticity smaller than that of the material of the heating element. A jig for manufacturing a tubular heater used for manufacturing a tubular heater having a heating element having a cylindrical outer shape.
It has a ridge portion that is spirally wound and arranged so as to protrude from the outer peripheral surface of the core material around the core material formed in a shaft shape.
The ridge portion is a jig for manufacturing a tubular heater, characterized in that a cross section cut along a plane including the central axis of the core material is arranged so as to have a gap in the central axis direction. The jig for manufacturing a tubular heater according to claim 7 , wherein the tubular heater is a sheathed heater in which a heating wire and an insulator powder are housed inside a tubular sheath. The tubular heater manufacturing according to claim 7 or 8 , wherein the ridge portion is formed by a three-dimensional modeling method in which a plurality of layered shaped objects are laminated along the central axis direction of the core material. Jig. The jig for manufacturing a tubular heater according to any one of claims 7 to 9 , wherein the ridge portion is made of a material having a modulus of elasticity smaller than that of the material of the heating element.

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