JPH0523749A - Manufacture of spiral plate and its manufacturing device - Google Patents

Abstract

PURPOSE:To form a spiral plate to precise shape and dimensions with arbitrary length by twisting a band-like stock with a prescribed angle each successively in the periphery of the center axis in a longitudinal direction at every prescribed length and forming it to a continuous spiral shape. CONSTITUTION:A band-like stock W is formed to a continous spiral shape by twisting it by a prescribed angle each in the periphery of the center axis 0 in the longitudinal direction successively at every prescribed length. A spiral plate P is obtained as a spiral curve drawn by a virtual line, in the case the virtual line is drawn in the direction for going straight to the center axis 0 going along the longitudinal direction of the spiral plate P, and this vitrual line is subjected to a constant speed linear motion in the direction of the center axis 0, while rotating it at an equal speed in the periphery of the center axis 0. A twist forming die 1 is constituted of the upper die 1A and the lower die 1B, and the band-like stock W is pressurized from the upper and the lower parts by these upper die 1A and lower die 1B and subjected to plastic deformation to a twisted shape. In such a manner, the spiral plate can be formed to an exact dimension shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a spiral plate applied to inner fins and the like for improving the thermal efficiency of boilers and dryers.

[0002]

2. Description of the Related Art A conventional spiral plate of this type is manufactured by, for example, chucking one end and twisting the other end by applying a rotational force by a lathe or the like. And
In order to make it easier to twist the strip-shaped material in a spiral shape, the strip-shaped material is formed into a corrugated shape at a predetermined pitch.

[0003]

However, in the case of the above-mentioned prior art, since the strip-shaped material is only twisted by applying the rotational force, the length that can be formed is restricted, and the spiral-shaped material having a desired length is formed. No plate could be obtained.

Further, it is difficult to form the spiral shape into a desired size and shape.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its object is a method of manufacturing a spiral plate which can be easily formed into a desired length and shape. And to provide a manufacturing apparatus.

[0006]

In order to achieve the above object, in the method for manufacturing a spiral plate according to the present invention, a strip-shaped material is sequentially arranged at predetermined angles around a central axis of the longitudinal direction. It is characterized by forming into a continuous spiral shape by twisting one by one.

Further, it is preferable that after the strip-shaped material is formed into a corrugated shape along the longitudinal direction of the strip-shaped material, the corrugated portion is sequentially twisted by a predetermined angle.

It is effective to mold the band-shaped material by using a twist molding die having a spiral curved surface as a unit when the spiral shape to be molded is divided into predetermined lengths.

An apparatus for manufacturing a spiral plate according to the present invention comprises a twist forming die for twisting a strip-shaped material at a predetermined length and a predetermined angle, and a pressurizing means for pressurizing the twist forming die, Conveying means for intermittently feeding the belt-shaped material at a predetermined pitch, and operating the pressurizing means in response to the intermittent feeding of the conveying means to cause the belt-shaped material to have a predetermined length by the twist molding die. It is characterized by twisting each time.

Further, the corrugated molding die for forming the corrugated material provided in the preceding stage of the twist molding die for corrugating along the longitudinal direction of the corrugated material, and a pressing member for pressing the corrugated molding die. A pressure means, the pressure means is operated in response to intermittent feeding of the conveying means, and the band-shaped material is cut at a predetermined length by the corrugated molding die and the twist molding die. It is effective to sequentially form the corrugated portion and to sequentially twist the corrugated portion.

It is preferable that the twist molding die has a spiral curved surface of a unit obtained by dividing a spiral shape to be molded into a predetermined length.

Further, the corrugated molding die and the torsion molding die are pressed by the same pressing means, and it is preferable that they are provided adjacent to each other in the order in which the belt-shaped material is conveyed.

The twist forming die is divided into two parts, that is, a pre-stage twist type on the inlet side of the belt-shaped material in the feed direction and a post-stage twist type on the exit side, and the twist angle of the post-stage twist type is larger than that of the pre-stage twist type. It is effective to set and increase the degree of torsional deformation of the band-shaped material stepwise.

[0014]

In the above-described method for manufacturing the spiral plate, the strip-shaped material is twisted by a predetermined twist angle for each predetermined length and continuously formed into a spiral shape. You can

Further, if the molding is carried out using a mold, a spiral plate having an accurate size and shape can be easily manufactured by selecting the twist angle of the mold for torsion molding.

In the apparatus for manufacturing a spiral plate of the present invention, the belt-shaped material is conveyed by the conveying means at a predetermined pitch,
The corrugated mold is formed into a corrugated shape, and the corrugated portion is transferred to the twist molding die, and the twist molding die is used to form the corrugated portion at a predetermined twist angle for each predetermined length.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. FIG. 1 conceptually shows a method for manufacturing a spiral plate of the present invention, in which a strip-shaped material W is successively twisted around a central axis O in the longitudinal direction by a predetermined angle for each predetermined length to form a continuous spiral. It is formed into a shape.

As shown in FIGS. 2 (a) and 2 (b), the spiral plate P is ideally a virtual line in a direction orthogonal to the central axis O along the longitudinal direction of the spiral plate P. It is understood as a spiral curved surface drawn by the virtual line I when I is drawn and the virtual line I is rotated at a constant speed around the central axis O while being moved linearly at a constant speed in the central axis O direction. Therefore,
When divided into a predetermined length, all the regions have the same twisted shape and can be completely overlapped. This division length is arbitrary, and the shape of the divided areas is the same for all areas, whether long or short. However, the same shape is not limited to the ideal spiral shape, and various spiral shapes can be selected according to the place of use.

As described above, it is preferable that the spiral plate P is formed by using the mold 1 for twist forming, paying attention to the fact that the spiral plate P has exactly the same shape when it is divided into a predetermined length.

The twist molding die 1 is composed of an upper die 1A and a lower die 1B. The upper and lower dies 1A and 1B press the strip-shaped material W from above and below to give a predetermined length of the strip-shaped material W. The material is plastically deformed into a twisted shape in the right or left rotation direction (left rotation in the drawing) in the feed direction by the amount.

The molding surfaces 1C and 1D for contacting the strip-shaped material W of the upper and lower molds 1A and 1B for pressure molding have a spiral curved surface P1 having a spiral shape of a predetermined length to be molded as a unit. The spiral curved surface P1 of this unit has a shape corresponding to the front and back surfaces, and the molding surfaces 1C and 1D are formed so as to mesh with each other.

FIG. 4 shows the lower mold 1B of the molding die 1. Since the same applies to the upper mold 1A, only the lower mold 1B will be described, and the description of the upper mold 1A will be omitted.

As shown in the figure, in the lower mold 1B, a front end edge 1a on the front side in the feeding direction (indicated by an arrow in the figure) of the band-shaped material is arranged horizontally, and its molding surface 1C is centered along the feeding direction. It is a spiral curved surface that is twisted in the counterclockwise direction by a predetermined angle around the axis O. For example, with the intersection of the front edge 1a and the central axis O as the origin X0, the coordinate X is taken on the central axis O, and the distance to the intersection of the rear edge 1b and the central axis 0 is A
And the twist angle formed by the rear edge 1b and the horizontal reference plane H is α, the orthogonal line drawn on the spiral curved surface at the position of the coordinate X so as to be orthogonal to the central axis O and the horizontal reference plane H.
The angle θ formed by and is expressed by X (α / A).

FIG. 3 shows the basic steps of the method for manufacturing the spiral plate of the present invention. In order to simplify the explanation, it is assumed that the twist angle α twisted by the one-shot twist forming die 1 is 45 degrees.

First, in a state where the twist forming die 1 is opened, the band-shaped material W is fed at a predetermined feed pitch d to allow a gap between the upper die 1A and the lower die 1B of the opened die 1 to be formed. The molding region W11 of the first stage is inserted into. The feed pitch d is set to the same length as the length A of the molding die 1 in the feed direction (see FIG. 3 (a)).

Next, the upper and lower molds 1A and 1B are pressed by a pressing means such as a press or a hammer. Then, the strip-shaped material W is twisted by a predetermined angle α following the spiral curved surfaces of the molding surfaces 1C and 1D of the upper and lower molds 1A and 1B (Fig. 3 (b)).
reference).

After the molding, the upper and lower molds 1A and 1B are opened, and the strip-shaped material W is fed at a predetermined pitch d.
The molding region W12 of the step is inserted between the upper and lower molds 1A and 1B (see FIGS. 3 (c) and 3 (d)).

Next, the upper and lower molds 1A and 1B are pressed to twist the second-stage molding region W12 by a predetermined angle α. Then,
The tip of the molding region W11 of the first stage turns at an angle 2α with respect to the horizontal reference plane H, that is, 90 degrees (FIG. 3 (e)).
reference).

Next, the upper and lower dies 1A and 1B are opened, the strip-shaped material W is fed at a predetermined pitch d, and the molding region W13 of the next stage is located between the upper and lower dies 1A and 1B. (See FIGS. 3 (f) and 3 (g)).

Then, the upper and lower molds 1A and 1B are pressurized to 3
The forming region W13 of the step is twisted by an angle α. Then 1
The tip of the forming area W11 of the second stage turns by an angle 3α, that is, 135 degrees with respect to the horizontal reference plane H, and the forming area W12 of the second stage turns by an angle 2α (FIG. 3 (h)).
reference).

Next, the upper and lower molds 1A and 1B are opened, and the strip-shaped material W is fed at a predetermined pitch d, and the next 4
The molding region W14 of the step is inserted between the upper and lower molds 1A and 1B (see FIGS. 3 (i) and 3 (j)).

Then, the upper and lower molds 1A and 1B are pressurized to 4
The forming region W14 of the step is twisted by an angle α. This result 1
The tip of the molding region W11 of the step is angle 4α, that is, 18
It turns only 0 degrees and the second stage forming area W12 has an angle of 3α.
(135 degrees), the angle α (90
It will only turn).

After that, by sequentially forming the fifth step and the sixth step, the spiral shape is continuously formed.

The length of the spiral plate P to be formed may be infinite as long as the length of the strip material W is allowed, and the spiral plate P may be cut to any desired length.

The twist angle α and the feed pitch d of the band-shaped material W can be selected arbitrarily.

That is, the degree of twist of the spiral plate P can be expressed by the twist angle per unit length of the spiral plate P, and the front end edge 1a and the rear end edge 1b of the twist forming die 1 and the horizontal reference plane H are shown. The degree of twist can be changed with the angle α formed by and the length dimension A along the longitudinal direction of the strip-shaped material W of the upper and lower dies 1A and 1B as parameters. For example, when A is kept constant and the angle α is increased, the degree of twist becomes large and the spiral pitch becomes small. On the contrary, when the angle α is made small, the degree of twist per unit length becomes small and the spiral pitch of the spiral plate P becomes small. Grows larger. Therefore, it is possible to easily obtain the spiral plate P having an arbitrary pitch simply by replacing the torsion molding die 1. Further, as shown in FIG. 5, before twisting the strip-shaped material W, it is preliminarily formed into a corrugation in the longitudinal direction in the same manner as in the conventional case, and the corrugated portion W1 is sequentially formed at a predetermined angle α.
Twisting one by one is preferable in terms of processing. The corrugated shape can be selected from various shapes such as a rectangular shape, a mountain shape, an arc shape, a triangular shape, and a trapezoidal shape, and are continuously provided at a predetermined pitch in the longitudinal direction of the strip material W.

In this corrugation, the strip material W may be preformed over the entire length of the strip material W before it is twisted. However, the strip material W is formed into a corrugated shape and simultaneously twisted by a predetermined length. It is advantageous in terms of manufacturing process.

That is, the corrugation is also performed as the corrugation, the corrugation molding die 2 is arranged in front of the twist molding die 1, and the strip-shaped material W is corrugated at a predetermined length to form the corrugation. If the portion W1 is twisted by a predetermined length by the twisting mold 1 of the next stage, the strip-shaped material W can be continuously spirally formed by one production line.

FIG. 6 shows a conceptual configuration of a spiral plate manufacturing apparatus according to the present invention. A corrugated molding die 2 for corrugating the band-shaped material W and a predetermined angle for each predetermined length of the band-shaped material W. Twisting mold 1 for twisting one by one, and band-shaped material W
Conveying means 3 such as a conveying roller for conveying the sheet at a predetermined pitch d, pressurizing means 4 such as a press or hammer for pressurizing the corrugated molding die 2 and the torsion molding die 1, and the torsion molding die. The cutter 5 is provided at a subsequent stage of the mold 1 to cut a spirally formed portion with an arbitrary length.

As shown in FIGS. 7 and 8, the corrugated molding die 2 and the torsion molding die 1 are arranged so that the strip-shaped material W is adjoined in order along the conveying direction from the front side in the conveying direction. And the same pressurizing means 4 upper and lower pressurizing plates 6, 7
Installed in between.

An inlet guide 8 is provided in front of the corrugated molding die 2 and an outlet guide 9 is provided on the outlet side of the twist molding die 1.

The corrugated metal mold 2 is composed of an upper mold 2A and a lower mold 2B, and corrugated teeth 10 and 11 having corrugations to be machined are formed at a predetermined pitch on opposite surfaces thereof. In this embodiment, the corrugated teeth 10 and 11 have a triangular cross section, and their phases are shifted so as to mesh with each other. The cross-sectional shape of the corrugated teeth 10 and 11 is not limited to the triangular shape, and various shapes such as a rectangular shape and a mountain shape can be selected.

The twist molding die 1 is the first die 1
01 and the second mold 102 have a two-stage configuration, and the band-shaped material is pressure-molded in two stages. The first and second molds 101 and 102 are arranged in this order from the front side of the first and second molds 101 and 102 along the feeding direction of the band-shaped material W.

Each of the first and second molds 101 and 102 basically has the same structure as that shown in FIG. 4, and its molding surface is in the left rotation direction in the feeding direction of the band-shaped material. It has a twisted spiral shape and has the same length A along the feed direction of the strip-shaped material, and the strip-shaped material is intermittently fed at a feed pitch equal to this length A.

In this specific example, the band-shaped material W is fed while being inclined by a predetermined angle α1 with respect to the horizontal reference plane H, and the molding surface of the corrugated molding die 2 is also inclined by the predetermined angle α1. The upper mold 101A and the lower mold 10 of the first mold
The front end edge 101a of 1B is inclined in the right rotation direction by α1 with respect to the horizontal reference plane H in accordance with the inclination angle α1 of the strip-shaped material W. On the other hand, the rear edge 101b of the first die 101
Are arranged on the horizontal reference plane H, and the band-shaped material W is twisted by the angle α1 by the first mold 101.

The second die 102 has an upper die 102.
A and the front edge 102a of the lower mold 102B are the first mold 101.
The rear end edge 102b is arranged on the horizontal reference plane H that coincides with the rear end edge 101b, and the rear end edge 102b is inclined with respect to the horizontal reference plane H in the counterclockwise direction by an angle α2. 102 will be twisted by an angle α2.

Torsional angle α by the first die 101 in the preceding stage
1 is smaller than the twisting angle α2 by the second mold 102 in the subsequent stage, and after being twisted by the angle α1 by the first mold 101, the second mold 102 finally performs the stepwise twisting up to the angle α2. It has become.

The outlet guide 9 has a cylindrical shape and its outer periphery is guided along the inner periphery of the outlet guide 9, and the tip of the spiral forming portion W2 of the strip-shaped material W is held to retain the strip-shaped material W. The inlet guide 8 and the outlet guide 9 are used for pressure molding while supporting both ends thereof. Furthermore, it is effective to pull the tip of the material W that is preferably twist-formed.

According to the apparatus for manufacturing the spiral plate having the above-described structure, the belt-shaped material W is intermittently transferred at a predetermined pitch by the conveying means 4 such as rollers, and the pressurizing means corresponding to the intermittent feeding of the conveying means 4. 4 is actuated, and the corrugated forming die 2 and the torsion forming die 1 successively form the belt-shaped material W into a corrugated shape for each predetermined length, and at the same time, the corrugated forming portion W
1 is sequentially twisted by the angle α1 by the first die 101, and the portion twisted at the angle α1 is twisted by the angle α2 by the second die, so that the strip-shaped material W is continuously spirally formed.

FIG. 9 shows the first die 101 and the second die 1.
2 schematically shows a two-step molding process according to No. 02. In order to make the molding state easy to understand, the waveform is omitted, and the lower mold 101B of the first and second molds 101, 102 at the time of mold opening,
102B and the strip-shaped material W are described separately.

First, in a state where the first and second molds 101 and 102 are opened, the strip-shaped material W is set to the first and second molds 101 and 102.
The upper die 101A and the lower die 1 of the first die 101 are opened by feeding by the same feed pitch d as the feed direction length A of 102.
The molding area W11 of the first step is inserted between the first molding area W01 and 01B (see FIG. 9A).

Next, the upper and lower molds 1A and 1B are pressed by a pressing means such as a press or a hammer. Then, the band-shaped material W is twisted by the upper and lower molds 101A and 101B by a predetermined angle α1 (see FIG. 9B).

After molding, first and second molds 101 and 102 are formed.
Open the mold, and feed the band-shaped material W at a predetermined pitch d,
The first-stage rough forming portion W11 ′ formed in the first stage is connected to the second stage in the second stage.
The mold 102 is inserted between the upper and lower molds 102A and 102B (see FIGS. 9C and 9D).

Next, when the first and second molds 101 and 102 are pressed by the upper and lower pressing plates 6 and 7, the one-step rough forming section W11 'is twisted by the angle α2 by the second mold,
The second-stage forming region W12 is twisted by a predetermined angle α1. That is, the molding region W12 of the second stage is twisted by the angle α1 and its tip is located on the horizontal reference plane H, and the
The two-stage rough-formed portion W12 ', which has been twist-formed by 1, is twisted from the horizontal reference plane H by an angle α2 (see FIG. 9 (e)).

Next, the upper and lower pressure plates 6 and 7 are separated from each other, the first and second molds 101 and 102 are opened, the strip-shaped material W is fed at a predetermined pitch d, and the next three stages. The eye forming region W13 is defined as the upper die 1 and the lower die 101
A two-stage rough forming part W12 ', which is inserted between A and 101B and is twist-formed by α1, is placed on the second mold 102,
Inserted between the lower molds 102A and 102B (Fig. 9 (f),
(See (g)).

Then, the first and second molds 101 and 102 are pressed to twist the forming region W13 of the third stage by an angle α1, and the two-stage rough forming portion W12 'of the preceding stage is twisted by an angle α2. Therefore, the leading end of the first-stage forming region W11 is swung by the angle 2α2 with respect to the horizontal reference plane H and by (α1 + 2α2) with respect to the unformed band-shaped material W. In addition, the tip of the second-stage molding region W12 has an angle (α1
It turns only + α2) (see Fig. 9 (h)).

Next, the first and second molds 101 and 102 are opened, and the strip-shaped material W is fed by a predetermined pitch d (see FIG. 9).
(See (i) and (j)), 3 step rough forming part W1 twisted by α1
3'is inserted between the upper and lower molds 102A and 102B of the second mold 102, and the fourth molding region W14 is inserted between the upper and lower molds 101A and 101B of the first mold 101.

When the first and second molds 101 and 102 are closed and pressed, the second mold 102 twists the three-stage rough molding portion W13 'by an angle α2, and the first mold 10 is pressed.
The four-step molding region W14 is twisted by the angle α1 by 1 (see FIG. 9 (k)). Therefore, the molding area W of the first stage
The tip of 11 is swung by an angle 3α2 with respect to the horizontal reference plane H and by (α1 + 3α2) with respect to the unformed band-shaped material W.

Next, the first and second molds 101 and 102 are opened (see FIG. 9 (l)), and thereafter, the fifth and sixth stages are sequentially formed, whereby a spiral is continuously formed. It will be shaped into a shape.

As described above, by forming in two steps, it is possible to form a spiral plate having a smaller spiral pitch, and it is possible to process the shape and size more precisely.

Then, a spiral plate having a desired length can be obtained by cutting it to an arbitrary length with a cutter (not shown).

[0062]

As described above, the present invention has the above-described structure and operation. Since the band-shaped material is twisted at a predetermined angle at a predetermined angle to form a spiral shape, the spiral plate can be formed into an arbitrary length. Can be molded into.

Further, if the twisting mold is used to form each of the spiral curved surfaces of the unit, the spiral plate can be formed into an accurate dimensional shape.

Further, if the band-shaped material is formed into a corrugated shape in advance and the corrugated portion is formed by twisting, it is possible to easily form the spiral shape.

Further, by simultaneously forming the corrugated molding and the torsional molding, the manufacturing process can be rationalized and the production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a conceptual configuration of a method for manufacturing a spiral plate according to an embodiment of the present invention.

2A and 2B show a spiral plate to be manufactured by the manufacturing method of FIG. 1, FIG. 2A is a schematic perspective view, and FIG. 2B is a front view.

3 (a) to 3 (l) are diagrams schematically showing the basic steps of the method for producing a spiral plate of the present invention.

FIG. 4 is a view showing the twist molding die of FIG.
(a) is a perspective view, (b) is a right side view, (c) is a front view, and (d) is a left side view.

FIG. 5 is a diagram showing a conceptual configuration of a method of manufacturing an end spiral plate according to another embodiment of the present invention.

FIG. 6 is a diagram schematically showing a configuration of a spiral plate manufacturing apparatus of the present invention.

FIG. 7 is a front view showing the configuration of a main part of the spiral plate manufacturing apparatus of the present invention shown in FIG.

FIG. 8 is an exploded perspective view of the twist molding die and the corrugation molding die of FIG. 7.

9 (a) to 9 (l) are diagrams schematically showing a two-step molding process when the twist molding die of FIG. 7 is used.

[Explanation of symbols]

1 Twisting Mold 1A Upper Mold 1B Lower Mold 1C, 1D Molding Surface 101 First Mold 102 Second Mold 2 Waveform Mold 2A Upper Mold 2B Lower Mold 3 Conveying Means 4 Pressurizing Means 5 Cutter 8 Inlet Guide 9 Outlet guide 10, 11 Corrugated teeth 1a, 1b Inlet side, outlet side edge W Strip material W1 Corrugated forming part W2 Spiral forming part O Longitudinal center axis P Spiral plate H Horizontal reference line P1 Spiral curved surface α Twist angle W11, W12, W13, W14 1st stage, 2nd stage, 3rd stage, 4th stage Forming area d Feed pitch

Claims (8)

[Claims] 1. A method for manufacturing a spiral plate, wherein a strip-shaped material is formed into a continuous spiral shape by sequentially twisting a predetermined length around a central axis of the longitudinal direction by a predetermined angle. 2. The method for producing a spiral plate according to claim 1, wherein after the band-shaped material is formed into a corrugated shape along the longitudinal direction of the band-shaped material, the corrugated portion is sequentially twisted at a predetermined angle. 3. The spiral shape according to claim 1 or 2, wherein the band-shaped material is molded by using a twist molding die having a spiral curved surface as a unit when the spiral shape to be molded is divided into predetermined lengths. Plate manufacturing method. 4. A twist forming die for twisting a strip-shaped material at a predetermined angle for each predetermined length, a pressurizing means for pressurizing the twist forming die, and an intermittent feed of the strip-shaped material at a predetermined pitch. And a conveyor means for operating the pressurizing means in response to the intermittent feeding of the conveyor means, and sequentially twisting the strip-shaped material by a predetermined length by the twist molding die. Device for manufacturing spiral plate. 5. The corrugated molding die for forming a corrugated strip-shaped material along the longitudinal direction of the strip-shaped material provided in the preceding stage of the twist molding die, and the corrugated molding die. A pressurizing means for pressing, the pressurizing means is actuated in response to intermittent feeding of the conveying means, and the corrugated forming die and the twist forming die allow the strip-shaped material to have a predetermined length. 5. The apparatus for manufacturing a spiral plate according to claim 4, wherein the corrugated portion is sequentially formed into a corrugated shape and the corrugated portion is sequentially twisted. 6. The twist forming die has a spiral curved surface of a unit obtained by dividing a spiral shape to be formed into a predetermined length.
Or the manufacturing apparatus of the spiral plate of 5 above. 7. The corrugated molding die and the torsion molding die are pressed by the same pressurizing means, and are provided adjacent to each other in the order in which the belt-shaped material is conveyed. An apparatus for manufacturing the spiral plate according to item 1. 8. The twist forming die has a two-part structure of a pre-stage twist type on the inlet side and a post-stage twist type on the exit side in the feeding direction of the band-shaped material, and the twist angle of the post-stage twist type is the twist angle of the pre-stage twist type. 8. The apparatus for manufacturing a spiral plate according to claim 4, 5, 6 or 7, wherein the setting is made larger to increase the degree of torsional deformation of the strip-shaped material stepwise.