Method for forming the neck of cylindrical components

Abstract

A method for forming a necked section of a cylindrical member is provided, which can prevent variations in the wall thickness of the necked portion and a reduction in the roundness of the cross-section of the cylindrical member without damaging the inner circumferential surface of the cylindrical member. The device comprises: a clamping process in which the cylindrical member is clamped between a first clamping member and a second clamping member, the first clamping member having a cylindrical mandrel inserted into the hollow interior from one open end of the cylindrical member, and the second clamping member having a cylindrical mandrel head inserted into the hollow interior from the other open end of the cylindrical member; a rotation process in which the cylindrical member, the first clamping member, and the second clamping member are rotated together about a cylindrical axis; and a necking forming process in which a processing roller capable of rotating the cylindrical member about a rotation axis parallel to the cylindrical axis is pressed against the outer peripheral surface of the rotating cylindrical member between the mandrel and the mandrel head to form the neck, and the gap between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the mandrel is set to less than 10% of the inner diameter of the cylindrical member.

Description

Technical Field

[0001] The present invention relates to a method for forming a neck on the outer peripheral surface of a cylindrical member. Background Technology

[0002] For example, as a power storage system, the development of a secondary battery utilizing the reaction of sodium and sulfur, namely a sodium-sulfur battery (hereinafter referred to as a NaS battery), is underway. This NaS battery is constructed, for example, as follows: a β-alumina solid electrolyte tube is placed inside a cylindrical positive electrode container made of aluminum or the like; sulfur is filled in the space between the positive electrode container and the β-alumina solid electrolyte tube; and sodium is filled inside the β-alumina solid electrolyte tube.

[0003] Furthermore, the configuration is set as follows: for example, the ionic conductivity of the β-alumina solid electrolyte is improved in a high-temperature environment above 300°C, and sodium and sulfur undergo a reversible reaction through the solid electrolyte, thereby repeatedly charging and discharging.

[0004] When such a NaS battery is repeatedly charged and discharged, for example, as the temperature changes between 100°C and 300°C, the internal pressure of the positive electrode container also fluctuates significantly. As a damper to absorb such internal pressure fluctuations in the positive electrode container, a circumferentially extending neck (recess) is formed on the outer circumferential surface of the cylindrical positive electrode container. By forming such a neck, damage to the positive electrode container can be prevented when it expands, for example, in the longitudinal direction.

[0005] Conventionally, when forming a neck on the outer circumferential surface of a cylindrical component such as the positive electrode container of a NaS battery, after inserting a cylindrical core called a mandrel into the interior of the cylindrical component, a processing roller that rotates together with the cylindrical component is pressed against the outer circumferential surface of the rotating cylindrical component and pressed in radially, thereby forming a long groove, i.e., a neck, that is recessed in a manner that extends circumferentially along the cylindrical component (for example, see Patent Documents 1 and 2).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 8-132145

[0009] Patent Document 2: Japanese Patent No. 3429658 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, in conventional methods for forming the neck of cylindrical components, the mandrel inserted to prevent the cylindrical component from being flattened will be in close contact with the inner circumferential surface of the necked cylindrical component, making it difficult to remove the mandrel from the necked cylindrical component and causing damage to the inner circumferential surface of the cylindrical component.

[0012] On the other hand, if the gap between the inner circumferential surface of the cylindrical component and the outer circumferential surface of the mandrel is made too large in order to make it easier to pull out the mandrel after necking, there will be problems such as the cylindrical component deforming during necking and the roundness of the cross section decreasing and / or the wall thickness of the formed necking portion changing more.

[0013] The present invention was made in view of the above-mentioned problems, and its object is to provide a method for forming a neck of a cylindrical member that can prevent changes in the wall thickness of the necked portion and a reduction in the roundness of the cross-section of the cylindrical member without damaging the inner circumferential surface of the cylindrical member.

[0014] Methods for solving problems

[0015] To address the aforementioned issues, a method for forming a necked-down cylindrical member according to an embodiment of the present invention provides the following means.

[0016] (1) The method for forming a necked-off cylindrical member according to Scheme 1 of the present invention is a method for forming a necked-off cylindrical member having a hollow cylindrical shape and having a necked-off recessed inward along the circumferential direction. The method for forming a necked-off cylindrical member includes: a clamping step, wherein the cylindrical member is clamped between a first clamping member and a second clamping member, the first clamping member having a cylindrical mandrel inserted into the hollow interior from one open end of the cylindrical member, and the second clamping member having a mandrel inserted into the hollow interior from the other open end of the cylindrical member. The cylindrical mandrel head; a rotation process in which the cylindrical member, together with the first clamping member and the second clamping member, rotates about a cylindrical axis; and a necking formation process in which a processing roller capable of rotating the cylindrical member about a rotation axis parallel to the cylindrical axis is pressed against the outer peripheral surface of the rotating cylindrical member between the mandrel and the mandrel head to form the neck, and the gap between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the mandrel is set to less than 10% of the inner diameter of the cylindrical member.

[0017] (2) According to the method for forming the neck of the cylindrical member according to Scheme 1, in Scheme 2 of the present invention, the inner diameter of the cylindrical member is formed to be in the range of 0.1 mm or more and 2.0 mm or less larger than the outer diameter of the mandrel.

[0018] (3) According to the method of forming the neck of the cylindrical member according to Scheme 1 or 2, in Scheme 3 of the present invention, the insertion length of the mandrel relative to the cylindrical member is longer than the insertion length of the mandrel head relative to the cylindrical member.

[0019] (4) The method for forming the neck of the cylindrical member according to any of the embodiments 1 to 3, wherein in embodiment 4 of the present invention, the cylindrical member is made of a metal containing aluminum.

[0020] (5) A method for forming a necked-off cylindrical member according to any of the embodiments 1 to 4. In embodiment 5 of the present invention, the processing roller is composed of a first processing roller and a second processing roller with different outer peripheral shapes. In the necked-off forming process, the necked-off is formed by pressing the first processing roller and the second processing roller sequentially onto the outer peripheral surface of the cylindrical member.

[0021] (6) The method for forming the neck of the cylindrical member according to any one of the embodiments 1 to 5, in embodiment 6 of the present invention, the cylindrical member having the neck is a battery casing for a sodium-sulfur battery.

[0022] Invention Effects

[0023] According to the present invention, a method for forming a neck of a cylindrical member can be provided, which can prevent variations in the wall thickness of the necked portion and a reduction in the roundness of the cross-section of the cylindrical member without damaging the inner circumferential surface of the cylindrical member. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view showing an example of a NaS battery in a charging state.

[0025] Figure 2 This is a perspective view showing an example of a necking forming apparatus used in the necking forming method of the cylindrical member in this embodiment.

[0026] Figure 3 This is a schematic diagram of the necking forming device (cylindrical component processing device) viewed from the side.

[0027] Figure 4 This is a flowchart illustrating a method for forming a necked-down cylindrical component according to one embodiment of the present invention.

[0028] Figure 5 It is a cross-sectional view illustrating the gap when a mandrel and mandrel head are inserted into a cylindrical component.

[0029] Figure 6 This is an explanatory diagram showing the clamp used for inserting the mandrel.

[0030] Figure 7 In the diagram, (a) is a cross-sectional view showing the neck (intermediate body) formed using the first processing roll, and (b) is a cross-sectional view showing the neck formed using the second processing roll. Detailed Implementation

[0031] Hereinafter, a method for forming a necked-down cylindrical member according to an embodiment of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments shown below are specific embodiments described to better understand the gist of the invention, and are not intended to limit the invention unless otherwise specified. Additionally, in the accompanying drawings used in the following description, for ease of understanding of the features of the invention, some parts that will be considered major components are sometimes shown in enlarged form, and the dimensional ratios of the constituent elements may not be the same as in reality.

[0032] [Sodium-sulfur battery (NAS battery)]

[0033] First, a sodium-sulfur battery (NAS battery) formed by a method for forming a necked cylindrical member according to one embodiment will be described as an application example of a cylindrical member with a necked neck.

[0034] Figure 1 This is a cross-sectional view showing an example of a NaS battery in a charging state.

[0035] The NaS battery 50 includes: a positive electrode container 53 using a cylindrical member with a constricted neck; a solid electrolyte tube 55 housed within the positive electrode container 53; and an outer container (battery container) 51 housing the positive electrode container 53 and the solid electrolyte tube 55.

[0036] An annular insulating member 57 is disposed on the upper part of the positive electrode container 53. The annular insulating member 57 is configured to be embedded between the inner peripheral surface of the positive electrode container 53 and the outer peripheral surface of the solid electrolyte tube (sodium containing part) 55. An electrode cap 59 is disposed on the annular insulating member 57. That is, in this embodiment, the configuration is such that by disposing of the electrode cap 59 at the opening of the positive electrode container 53, the interior of the positive electrode container 53 is airtightly sealed.

[0037] Furthermore, in the charging state, the NaS battery 50 has a solid electrolyte tube 55 filled with single-cell metallic sodium 65. Additionally, a sulfur electrode 67, formed by impregnating graphite felt with sulfur, is disposed in the space between the positive electrode container 53 and the solid electrolyte tube 55. Furthermore, a positive terminal 61 is connected to the upper end of the positive electrode container 53, and a negative terminal 62 is disposed on the electrode cap 59.

[0038] The positive electrode container 53 can be configured to close one open end of a cylindrical member with a necking formed by the necking method of the cylindrical member described later in this embodiment. A necking 53a is formed near one open end, in such a way that a recessed portion that is recessed toward the inward (center) surrounds the outer peripheral surface.

[0039] Such a positive electrode container 53 can be made entirely of, for example, aluminum alloy. Furthermore, the outer casing (battery container) 51 covering the outer periphery of the positive electrode container 53 is made of, for example, nickel-containing stainless steel. Additionally, the solid electrolyte tube (sodium containment section) 55 is made of β-alumina. Moreover, the annular insulating member 57 is made of α-alumina, and the electrode cap 59 is made of aluminum or the like. Furthermore, the positive terminal 61 and the negative terminal 62 are made of aluminum or the like.

[0040] The NaS battery 50 with this configuration is configured such that sodium (Na) filled inside the solid electrolyte tube 55 reacts with sulfur (S) disposed outside the solid electrolyte tube 55 via the solid electrolyte tube 55 made of β-alumina, thereby charging and discharging.

[0041] That is, through 2Na + XS → Na2S X (Discharge), Na2S X →2Na + XS (charging) is a reversible reaction, thus repeatedly charging and discharging. Here, sodium polysulfide (Na2S) is generated through the reaction. X Sodium 65 is present in the sulfur electrode 67 described above. Therefore, in the discharge state, the solid electrolyte tube 55 is empty and becomes a cavity, while in the charging state, the solid electrolyte tube 55 is filled with sodium 65.

[0042] The positive electrode container 53 of such a NaS battery 50, due to the aforementioned charging and discharging process and changes in the external temperature environment, extends along its length direction ( Figure 1 Stress is applied in a way that stretches and contracts in the vertical direction. Therefore, it is configured such that by narrowing the neck 53a, the positive electrode container 53 is prevented from breaking by utilizing its function as a damper that allows such expansion and contraction of the positive electrode container 53 due to temperature changes.

[0043] Hereinafter, an embodiment of a method for forming a necked-down member suitable for use as the positive electrode container of a NaS battery as described above will be described.

[0044] Figure 2 This is a perspective view showing an example of a necking forming apparatus (cylindrical component processing apparatus) used in the necking forming method of the cylindrical component in this embodiment. Additionally, Figure 3This is a schematic diagram of the necking forming device (cylindrical component processing device) viewed from the side.

[0045] The necking forming apparatus (cylindrical component processing apparatus) 10 includes a first clamping member 11, a second clamping member 12, and a processing roller device 19.

[0046] The first clamping member 11 includes: a workpiece stop 13, which is connected to one end We1 of the cylindrical member W during processing and applies force to the cylindrical member W in the direction of the second clamping member 12; a cylindrical mandrel (core) 14, which extends from one end We1 of the cylindrical member W and is rotatably formed; and a mandrel stop 15, which adjusts the position of the mandrel 14 along a direction perpendicular to the cylindrical axis of the mandrel 14.

[0047] The second clamping member 12 includes: a spindle head (core) 16; a workpiece stop 17, which is connected to the other end We2 of the cylindrical member W during processing and applies force to the cylindrical member W in the direction of the first clamping member 11; and a rotating device (motor) 18, which rotates the workpiece stop 17.

[0048] During the necking process, the cylindrical member W is clamped between the first clamping member 11 and the second clamping member 12. Furthermore, by using the rotating device (motor) 18 to rotate the workpiece stop 17, the cylindrical member W, whose other end We2 is connected to the workpiece stop 17, rotates about the cylindrical axis.

[0049] Furthermore, a fitting protrusion (fitting member) 21 is formed at the center of the circular end face of the mandrel 14 facing the mandrel head 16. Additionally, a recess 22 capable of receiving the fitting protrusion 21 is formed at the center of the circular end face of the mandrel head 16 facing the mandrel 14.

[0050] During the necking process, the ends of the mandrel 14 and the mandrel head 16 approach each other, and the engagement of the fitting protrusion 21 and the recess 22 prevents the central axis of the mandrel 14 and the mandrel head (core) 16 from shifting.

[0051] Furthermore, in this embodiment, the mandrel 14 is formed such that its length along the cylindrical axis is longer than the length of the mandrel head 16 along the cylindrical axis. This ratio of the lengths of the mandrel 14 to the mandrel head 16 along the cylindrical axis is adjusted according to the position where the neck is formed in the cylindrical member W. That is, the position of the mandrel 14 and the mandrel head 16 facing each other becomes the position where the neck is formed in the cylindrical member W.

[0052] The processing roller assembly 19 comprises a first processing roller 24 and a second processing roller 25 with different outer peripheral shapes, and a sliding platform 26 supporting the first processing roller 24 and the second processing roller 25. The first processing roller 24 and the second processing roller 25 are driven rollers that are driven by contact with the outer peripheral surface Wf of the rotating cylindrical member W. Alternatively, the first processing roller 24 and the second processing roller 25 may also be configured to rotate by a rotating unit such as a motor.

[0053] For example, for a cylindrical member W, the first processing roller 24 forms a neck (intermediate form) in such a way that the cross section perpendicular to the circumferential direction is, for example, trapezoidal. In addition, the second processing roller 25 further necks the neck (intermediate form) formed by the first processing roller 24 with a trapezoidal cross section, so that the neck is formed in such a way that the cross section perpendicular to the circumferential direction is, for example, a trapezoid with a curved bottom.

[0054] Thus, in the necking forming apparatus 10 of this embodiment, by pressing the first processing roller 24 and the second processing roller 25, whose outer peripheral shapes are different from each other, onto the outer peripheral surface Wf of the rotating cylindrical member W in sequence, a neck with a target cross-sectional shape is formed on the cylindrical member W.

[0055] The sliding platform 26 of the necking forming apparatus 10 slides in a direction orthogonal to the cylindrical axis of the cylindrical member W. This causes the first processing roller 24 and the second processing roller 25 to move between a neutral position, a first processing position, and a second processing position. The neutral position is where neither the first processing roller 24 nor the second processing roller 25 contacts the outer peripheral surface Wf of the cylindrical member W. The first processing position is where only the first processing roller 24 contacts the outer peripheral surface Wf of the cylindrical member W. The second processing position is where only the second processing roller 25 contacts the outer peripheral surface Wf of the cylindrical member W.

[0056] Figure 4 This is a flowchart illustrating a method for forming a necked-down cylindrical component according to one embodiment of the present invention.

[0057] In the method for forming a necked-off cylindrical member according to this embodiment, the necked-off forming apparatus (cylindrical member processing apparatus) 10 configured as described above is used.

[0058] First, the mandrel 14 and mandrel head 16 are configured in the necking forming apparatus 10 to have a small diameter, which is less than 10% of the inner diameter of the cylindrical member W that is being processed. In this embodiment, the cylindrical member W is, for example, a cylindrical tube made of aluminum alloy, with a length of 500 mm, an inner diameter r1 of 84.6 mm, and a wall thickness of 1.3 mm.

[0059] Therefore, as Figure 5 As shown, when the mandrel 14 and mandrel head 16 are inserted into the cylindrical member W, the gap Δt between the inner circumferential surface Wr of the cylindrical member W and the outer circumferential surface 14f of the mandrel 14 and the outer circumferential surface 16f of the mandrel head 16 is set to at least 10% of the inner diameter r1 of the cylindrical member W.

[0060] For example, the inner diameter r1 of the cylindrical component W can be an inner diameter that is 0.1 mm larger than the outer diameter r2 of the mandrel 14 and the outer diameter r2 of the mandrel head 16 and is within the range of 2.0 mm larger.

[0061] As an example, the inner diameter r1 of the cylindrical component W is set to 84.6 mm, the outer diameter r2 of the mandrel 14 and mandrel head 16 is set to 84.2 mm, and the gap Δt is set to 0.2 mm.

[0062] Furthermore, when using a cylindrical member W with an inner diameter r1 of 84.6 mm, the optimal range for the gap Δt is, for example, 0.05 mm to 0.5 mm, and more preferably 0.2 mm to 0.4 mm.

[0063] Next, the selected mandrel 14 is inserted into the hollow interior from the open end We1 side of the cylindrical member W. When inserting the cylindrical member W into the mandrel 14, for example, as... Figure 6 As shown, it is preferable to install the insertion clamp 29 on the top of the mandrel 14. By using such an insertion clamp 29, the mandrel 14 can be smoothly guided into the hollow part of the cylindrical member W, thus preventing damage to the mandrel 14.

[0064] Furthermore, when inserting such a mandrel 14 into the cylindrical member W, by setting the gap Δt to at least 10% or less of the inner diameter r1 of the cylindrical member W as described above, the cylindrical axis of the mandrel 14 is aligned with the cylindrical axis of the cylindrical member W, so that when the cylindrical member W is rotated, the cylindrical member W will not rotate eccentrically relative to the mandrel 14.

[0065] Next, the mandrel head 16 is inserted into the hollow interior from the open end on the We2 side of the other end of the cylindrical member W. Thus, inside the cylindrical member W, the fitting protrusion 21 of the mandrel 14 engages with the recess 22 of the mandrel head 16. This opposing portion of the mandrel 14 and mandrel head 16 forms the necked-off position of the cylindrical member W.

[0066] Furthermore, by applying force to one end We1 and the other end We2 of the cylindrical member W respectively to the workpiece stop 15 and the workpiece stop 17, the cylindrical member W is clamped between the first clamping member 11 and the second clamping member 12 (clamping process S1).

[0067] Next, the rotating device (motor) 18 is activated, causing the cylindrical member W to rotate around the cylindrical axis via the workpiece stop 17 (rotation step S2). In this rotation step S2, by setting the gap Δt between the inner circumferential surface Wr of the cylindrical member W and the outer circumferential surface 14f of the mandrel 14 and the outer circumferential surface 16f of the mandrel head 16 to at least 10% or less of the inner diameter r1 of the cylindrical member W, it is possible to prevent the cylindrical member W from rotating eccentrically relative to the mandrel 14.

[0068] Next, the sliding platform 26 of the necking forming apparatus 10 is slid, and firstly, the first processing roller 24 is moved to a position where it contacts the outer peripheral surface Wf of the cylindrical member W. Thus, the first processing roller 24 rotates passively due to the rotation of the cylindrical member W. Furthermore, in this embodiment, the necking processing position of the first processing roller 24 and the second processing roller 25 is set at a position 34 mm from the other end We2 of the cylindrical member W.

[0069] Then, the sliding platform 26 is slid further towards the inside of the cylindrical member W, pressing the first processing roller 24 at a predetermined processing rate. Thus, in the cylindrical member W, as... Figure 7 As shown in (a), a necked-out (intermediate form) V1 is formed with a cross section perpendicular to the circumferential direction, for example, in the form of a trapezoid.

[0070] Next, the sliding platform 26 is slid in the opposite direction to the processing of the first processing roller 24, causing the first processing roller 24 to move away from the cylindrical member W, and the second processing roller 25 is moved to the formation position of the neck (intermediate forming body) V1 of the cylindrical member W. As a result, the second processing roller 25 rotates passively due to the rotation of the cylindrical member W.

[0071] Then, the sliding platform 26 is slid further to overlap with the necked-out (intermediate forming body) V1 formed by the first processing roller 24, and the second processing roller 25 is pressed at a predetermined processing rate. Thus, in the cylindrical member W, as... Figure 7 As shown in (b), a necked neck V2 with a cross section perpendicular to the circumferential direction, for example, a trapezoidal shape with a curved bottom, is formed (necked neck forming process S3).

[0072] Thus, the necked-out V2 formed in two stages by the first processing roller 24 and the second processing roller 25 is formed such that, while maintaining the thickness of the cylindrical member W on its bottom surface V2e, the two inclined sides V2s extending toward the bottom surface are thinner than the thickness of the cylindrical member W.

[0073] Furthermore, in this embodiment, when a neck is formed in the cylindrical member W, it is performed in two stages by the first processing roller 24 and the second processing roller 25, but it is not limited to this. The neck can also be formed in one stage by one processing roller, or the neck can be formed in multiple stages by using three or more processing rollers.

[0074] According to the method for forming the neck of the cylindrical member of this embodiment as described above, such as... Figure 5 As shown, by setting the gap Δt between the inner circumferential surface Wr of the cylindrical member W and the outer circumferential surface 14f of the mandrel 14 and the outer circumferential surface 16f of the mandrel head 16 when the mandrel 14 and mandrel head 16 are inserted into the cylindrical member W to at least 10% or less of the inner diameter r1 of the cylindrical member W, it is possible to suppress jamming when the cylindrical member W is inserted or disengaged relative to the mandrel 14 and mandrel head 16, thereby preventing damage to the inner circumferential surface Wr of the cylindrical member W due to friction.

[0075] In addition, if the gap Δt is set to less than 10%, the thickness variation (thickness non-uniformity) during the necking process is stable, and a neck with a stable and minimally variable wall thickness can be formed along the entire length of the cylindrical component W in the circumferential direction.

[0076] In addition, if the gap Δt is set to less than 10%, the roundness deterioration along the circumferential direction can be prevented, and a stable neck with minimal dimensional variation can be formed in the cylindrical member W.

[0077] The foregoing has described one embodiment of the present invention, but this embodiment is provided as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in a variety of other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and also within the scope of the invention as described in the claims and its equivalents.

[0078] Industrial availability

[0079] According to the method for forming a necked-off cylindrical member of the present invention, when forming the necked-off along the circumferential direction of the cylindrical member, a cylindrical member with a necked-off with high precision and low error can be obtained. A cylindrical member with such a necked-off can be preferably used in a battery container having a buffer function that allows for thermal expansion and contraction. Therefore, it has industrial applicability.

[0080] Explanation of reference numerals in the attached figures

[0081] 10…Neck Forming Device (Cylindrical Component Processing Device)

[0082] 11…First clamping component

[0083] 12…Second clamping component

[0084] 13, 17… Workpiece stop parts

[0085] 14… Spindle (core)

[0086] 15…Spindle stop

[0087] 16… Spindle head (core)

[0088] 18… Rotating device (motor)

[0089] 19…Processing Roller Device

[0090] 24…First processing roll

[0091] 25…Second processing roll

[0092] 26…sliding pedestal

[0093] W… cylindrical component

[0094] V2…neck retraction

Claims

1. A method for forming a necked-off section of a cylindrical member, comprising forming a necked-off section along the circumferential direction inward on a hollow cylindrical member, the method comprising: The clamping process involves clamping the cylindrical member between a first clamping member and a second clamping member. The first clamping member has a cylindrical mandrel inserted into the hollow interior from one open end of the cylindrical member, and the second clamping member has a cylindrical mandrel head inserted into the hollow interior from the other open end of the cylindrical member. A rotation process, in which the cylindrical member, together with the first clamping member and the second clamping member, rotates about a cylindrical axis; and In the necking formation process, a processing roller capable of rotating the cylindrical member about an axis parallel to the cylindrical axis is pressed against the outer circumferential surface of the rotating cylindrical member between the mandrel and the mandrel head to form the neck. The gap between the inner circumferential surface of the cylindrical component and the outer circumferential surface of the mandrel and the outer circumferential surface of the mandrel head is set to less than 10% of the inner diameter of the cylindrical component.

2. The method for forming a necked-off section of a cylindrical component according to claim 1, The inner diameter of the cylindrical member is formed to be 0.1 mm larger than the outer diameter of the mandrel and the outer diameter of the mandrel head, but less than 2.0 mm larger.

3. The method for forming a necked-off section of a cylindrical component according to claim 1 or 2, The insertion length of the mandrel relative to the cylindrical member is longer than the insertion length of the mandrel head relative to the cylindrical member.

4. The method for forming a necked-down cylindrical component according to claim 1 or 2, The cylindrical component is made of a metal containing aluminum.

5. The method for forming a necked-off section of a cylindrical component according to claim 1 or 2, The processing rollers consist of a first processing roller and a second processing roller with different outer peripheral shapes. In the necking forming process, the necking is formed by pressing the first processing roller and the second processing roller sequentially onto the outer peripheral surface of the cylindrical member.

6. The method for forming a necked-down cylindrical component according to claim 1 or 2, A fitting member is formed on the surface of the mandrel opposite to the mandrel head, which is capable of engaging with the mandrel head.

7. The method for forming a necked-off section of a cylindrical component according to claim 1 or 2, The cylindrical component with the constricted neck is used as a battery casing for sodium-sulfur batteries.

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