JP6153750B2 - Spiral spring and manufacturing method thereof - Google Patents

Description

  The present invention relates to a spiral spring used for, for example, a seat back of a vehicle seat, a tumble mechanism, a seat height adjuster, and the like, and a manufacturing method thereof.

  The spiral spring includes a spiral portion, an inner end portion, and an outer end portion. In use, the inner end is fixed to the inner counterpart. On the other hand, the outer end is fixed to the outer counterpart. In this way, the spiral spring is disposed in the space between the inner counterpart and the outer counterpart. For this reason, there are restrictions on the dimensions of the spiral spring.

JP-A-1-303333

  The spiral spring is formed, for example, by winding a spring material around a cored bar. For this reason, dimensional control is difficult. Therefore, a method for reducing the size of the spiral spring by setting the formed spiral spring compact is conceivable.

  At the time of setting, stress is generated in the spiral portion. Specifically, a compressive stress is generated on the radially inner side of the spring material, and a tensile stress is generated on the radially outer side. The generated stress varies over the entire length of the spiral portion in the extending direction. That is, the stress distribution in the spiral portion during setting is not uniform. For example, stress tends to increase at winding positions such as 0.5, 1.5, and 2.5 from the inner end. At these winding positions, it is assumed that the amount of plastic deformation is large. On the other hand, at the winding position such as 1st, 2nd, 3rd, etc. from the inner end, the stress tends to be small. In these winding positions, it is assumed that the amount of plastic deformation is small. Thus, the stress distribution in the spiral portion during setting is non-uniform. For this reason, at the time of setting, there exists a possibility that a spiral part may change to an ellipse shape.

  In this case, it becomes difficult to obtain the effect of downsizing by setting. Further, the spiral spring after setting may interfere with an adjacent member (for example, an inner counterpart). Further, there is a possibility that the curvature change and the residual stress distribution vary over the entire length of the spiral portion in the extending direction after the setting.

  Patent Document 1 discloses a spiral spring manufacturing method in which a spacer is inserted between spring members adjacent in the radial direction during setting. According to the manufacturing method of the same document, as shown in FIG. 3 of the same document, it is possible to form a spiral spring having an unequal pitch and being eccentric. According to the spiral spring manufacturing method described in this document, as shown in FIG. 4, contact between adjacent spring materials can be avoided when tightened. For this reason, as shown in FIG. 5, the torque characteristics can be improved. As described above, Patent Document 1 discloses a method of manufacturing a non-contact spiral spring that prohibits contact between spring members adjacent in the radial direction during use.

  However, Patent Document 1 does not describe the variation in stress distribution during setting as described above. Moreover, the manufacturing method described in Patent Document 1 intentionally imparts an irregular shape (unequal pitch) to the spiral spring by setting. In contrast, the object of the present invention is to suppress the deformation (ellipticalization) of the spiral spring during setting. In this regard, Patent Document 1 discloses a technique in the opposite direction to the present invention.

  The spiral spring and the manufacturing method thereof according to the present invention have been completed in view of the above problems. An object of the present invention is to provide a spiral spring in which the residual stress distribution is less likely to vary over the entire length of the spiral portion in the extending direction, and a method for manufacturing the spiral spring.

  (1) In order to solve the above-described problem, the spiral spring manufacturing method of the present invention is made of a strip-shaped spring material, and includes an inner end portion, an outer end portion, the inner end portion, and the outer end portion. A spiral spring formed in a spiral shape, the inner end of the spiral spring molded body is fixed to the inner end fixing member, the outer end is swingably locked to the outer end fixing member, and the spiral An inner reference portion is arranged on the inner side in the radial direction of the portion, and the spiral section is adjacent to the contact section in which all of the spring materials adjacent to the radial direction are arranged on the outer side in the radial direction of the inner reference portion. By setting a non-contact section where at least a part of the spring material does not contact, a setting step of imparting permanent distortion to the spiral spring molded body is provided.

  Here, “strip-shaped” includes “linear”. That is, the lateral width of the spring material is not particularly limited. The “spiral spring molded body” corresponds to an incomplete “spiral spring” before the setting process.

  In the setting step, a non-contact section where at least a part of the spring material adjacent in the radial direction does not contact the spiral spring molded body and a contact section where all the spring materials adjacent in the radial direction contact are set. That is, in the setting step, at least one non-contact section and at least one contact section are arranged in the circumferential direction of the spiral spring molded body. In other words, in the setting process, only the non-contact section is not arranged over the entire circumferential direction of the spiral spring molded body. In the setting process, only the contact section is not arranged over the entire circumferential direction of the spiral spring molded body.

  In the contact section, all spring materials adjacent in the radial direction are in contact. On the other hand, in the non-contact section, at least a part of the spring materials adjacent in the radial direction is not in contact. For this reason, the frictional resistance in the circumferential direction is greater in the contact section than in the non-contact section.

  In the spiral spring manufacturing method of the present invention, the stress generated in the spiral spring molded body in the setting process is controlled by intentionally setting the contact section. That is, the contact section is intentionally created by setting the inner reference portion.

  According to the spiral spring manufacturing method of the present invention, the spiral spring molded body is less likely to be deformed (elliptical) in the setting step. For this reason, the dispersion | variation in the stress distribution in a spiral part can be made small. Therefore, in the spiral spring completed after setting, the variation in curvature (the degree of change in the curvature per unit length in the direction in which the spiral portion extends) and the variation in the residual stress distribution over the entire length in the direction in which the spiral portion extends. Can be suppressed. Moreover, the spiral spring after completion can be reduced in size (smaller diameter). Further, by setting the inner reference portion, it is possible to suppress the interference of the spiral portion with the inner counterpart (the one to which the inner end portion of the completed spiral spring is fixed).

  (2) Preferably, in the configuration of the above (1), in the setting step, a straight line connecting a vortex shape center of the spiral portion and an outer contact portion where the outer end portion and the outer end fixing member are in contact with each other. The inner reference portion is preferably arranged in a section having a central angle of 80 ° or more and 160 ° or less around the center of the spiral shape along the extending direction of the spiral portion with reference to the reference line .

  Here, the circumferential position when the end on the inner end side of the spiral part in the setting step is set to 0 is the “winding position”, and the “vortex shape center of the spiral part” is the winding position of the spiral part of 0 or more The center of the approximate circle in the section of 0.25 or less.

  The inner reference portion is along the extending direction of the spiral portion, with a straight line connecting the center of the spiral shape of the spiral portion and the outer contact portion where the outer end portion and the outer end fixing member are in contact in the setting process as a reference line. Thus, it is arranged in a section having a central angle of 80 ° or more and 160 ° or less with the vortex shape center as the center. And the inner side reference | standard part is arrange | positioned at the radial direction inner side of a spiral part. Here, the position of the inner reference portion is set to a section having a central angle of 80 ° or more and 160 ° or less. When the angle is less than 80 ° or more than 160 °, the stress distribution varies over the entire length of the spiral portion in the extending direction. It is easy.

  According to this configuration, the position of the contact section is adjusted by setting the position of the inner reference portion to a section having a central angle of 80 ° to 160 °. When the position of the contact section is adjusted, the bending moment of each part of the spiral part can be controlled. For this reason, the curvature change and the dispersion | distribution of stress distribution over the extension direction full length of a spiral part can be suppressed.

  (3) Preferably, in the configuration of (1) or (2), the inner reference portion is a boundary between the inner end portion and the spiral portion, or a contact point between the inner end fixing member and the spiral portion. Of these, the inner contact portion arranged at the contact point closest to the inner end portion is preferable.

  According to this configuration, the inner contact portion is arranged at a contact point closest to the inner end portion among (α) a boundary between the inner end portion and the spiral portion, or (β) a contact point between the inner end fixing member and the spiral portion. . In the case of (β) and when the contact between the inner end fixing member and the spiral portion is single, the inner contact portion is disposed at the contact. Further, in the case of (β) and when there are a plurality of contacts between the inner end fixing member and the spiral portion, the inner contact portion is arranged at the contact closest to the inner end portion among the plurality of contacts. . According to this configuration, the inner contact portion can be arranged at a desired position by adjusting the positions of the inner end portion and the inner end fixing member.

  (3-1) Preferably, in the configuration of the above (3), the inner end portion includes a straight portion and a curved portion having a constant curvature connected to the spiral portion, and the inner contact portion is It is better to have a configuration that is arranged at the boundary between the curved portion and the spiral portion. According to this configuration, the inner contact portion can be arranged using the boundary between the curved portion and the spiral portion.

  (4) Preferably, in the configuration of the above (1) or (2), the inner reference portion is disposed at a contact point between the contact guiding member disposed independently of the inner end fixing member and the spiral portion. It is better to have a configuration.

  According to this configuration, the inner reference portion is independent of the inner end fixing member. For this reason, the freedom degree of the position setting of an inner edge part and an inner edge fixing member becomes high. Further, the degree of freedom in setting the position of the inner reference portion is increased.

  (5) In order to solve the above-described problem, the spiral spring of the present invention is manufactured by the spiral spring manufacturing method according to any one of the above (1) to (4). According to the spiral spring of the present invention, it is possible to suppress variations in curvature and residual stress distribution over the entire length of the spiral portion in the extending direction. Moreover, the spiral spring after completion can be reduced in size (smaller diameter). Moreover, interference of the spiral portion with respect to the inner counterpart can be suppressed.

  According to the present invention, it is possible to provide a spiral spring in which the residual stress distribution is less likely to vary over the entire length of the spiral portion in the extending direction, and a method for manufacturing the spiral spring.

It is a side view of the spiral spring of the first embodiment. It is a side view of the spiral spring molded object in the setting process of the manufacturing method of the spiral spring. FIG. 3 is an enlarged view in a circle III in FIG. 2. FIG. 4 is an enlarged view in a circle IV in FIG. 2. (A) is a schematic diagram (the 1) of the setting method of the vortex shape center of the spiral part in a setting state. (B) is the schematic diagram (the 2) of the setting method. (C) is the schematic diagram (the 3) of the setting method. It is a side view of the spiral spring molded object in the setting process of the manufacturing method of the spiral spring of 2nd embodiment. It is a graph which shows the relationship between the position of the inner side reference | standard part of Example 1 in a setting state, and a stress increase rate. It is a graph which shows the relationship between the winding position of Example 1 in a setting state, and stress.

  Embodiments of the spiral spring and the manufacturing method thereof according to the present invention will be described below.

<First embodiment>
[Configuration of spiral spring]
First, the configuration of the spiral spring of this embodiment will be described. In FIG. 1, the side view of the spiral spring of this embodiment is shown. As shown in FIG. 1, the spiral spring 1 of the present embodiment includes an inner end portion 20, a spiral portion 21, and an outer end portion 22. The spiral spring 1 is formed of a strip-shaped spring material S. In the natural state (no load state) G1, the spiral portion 21 has an Archimedean curve shape. That is, in the natural state G1, the winding interval (interval between the spring materials S adjacent in the radial direction) of the spiral portion 21 is constant. The spiral spring 1 is used for swinging a seat back of a vehicle seat (not shown).

  As shown by a thin line in FIG. 1, the inner end portion 20 is fixed to the inner counterpart 3 in the attached state (the state in which the spiral spring 1 is attached to the vehicle seat). The inner counterpart 3 is disposed on a cushion frame (not shown). Further, the outer end portion 22 is locked to the outer counterpart 4 so as to be swingable. The outer counterpart 4 is disposed on a back frame (not shown). When the seat back is swung, the outer counterpart 4, that is, the outer end portion 22 is swung. The positions of the outer counterpart 4 and the outer end portion 22 shown in FIG. 1 correspond to the maximum deformation state G2 (the state in which the amount of deformation in the winding direction with respect to the natural state G1 is the largest).

[Method of manufacturing spiral spring]
Next, the manufacturing method of the spiral spring of this embodiment is demonstrated. The manufacturing method of the spiral spring 1 of this embodiment has a formation process and a setting process. In FIG. 2, the side view of the spiral spring molded object in the setting process of the manufacturing method of the spiral spring of this embodiment is shown.

  In the forming step, the spring material S is wound around the core bar to give the spring material S a spiral shape. That is, the spiral spring molded body 5 is produced. The spiral spring molded body 5 includes an inner end portion 50, a spiral portion 51, and an outer end portion 52. In the natural state G3 (the natural state of the spiral spring molded body 5 before setting), the spiral portion 51 has an Archimedean curve shape. That is, in the natural state, the winding interval of the spiral portion 51 is constant. The spiral spring molded body 5 has a larger diameter than the spiral spring 1 shown in FIG.

  In the setting step, the spiral spring molded body 5 is reduced in size by setting the spiral spring molded body 5. Specifically, the inner end portion 50 is fixed to the inner end fixing member 6. Further, the outer end portion 52 is locked to the outer end fixing member 7 so as to be swingable. That is, the spiral spring molded body 5 is set to the setting state G4. In the setting state G4, the inner end portion 50 cannot swing freely with respect to the inner end fixing member 6. On the other hand, the outer end portion 52 can freely swing with respect to the outer end fixing member 7. The outer end 52 is in a so-called free outer end state (the outer end 52 is locked to the outer end fixing member 7 so as to be swingable (moment free)).

  FIG. 3 shows an enlarged view in the circle III of FIG. As shown in FIG. 3, a contact guiding member 53 is disposed on the radially inner side of the spiral portion 51. The contact guide member 53 has a short-axis round bar shape (pin shape). The contact guide member 53 is in contact with the spiral portion 51 from the inside in the radial direction. The inner reference portion D is disposed at the contact point between the contact guide member 53 and the spiral portion 51. A contact section C occurs outside the inner reference portion D in the radial direction. The contact section C will be described in detail later.

  FIG. 4 shows an enlarged view in a circle IV in FIG. As shown in FIG. 4, the outer end portion 52 includes a straight portion 520 and a curved portion 521. The straight portion 520 is disposed on the radially outer side with respect to the spiral portion 51. The curved portion 521 connects the straight portion 520 and the spiral portion 51 in a C shape. The curvature of the curved portion 521 is constant. The center of curvature b of the curved portion 521 is set on the radially outer side of the spiral portion 51. The outer contact portion B is disposed at the circumferential end of the contact interface between the outer end fixing member 7 and the curved portion 521.

  As shown in FIG. 2, the inner end 50 in the setting state G4 and the inner end 20 in the maximum deformation state G2 are set at the same position. The outer end 52 in the setting state G4 is arranged so as to be shifted in the winding direction with respect to the outer end 22 in the maximum deformation state G2.

  As shown in FIG. 3, the contact section C occurs outside the inner reference portion D in the radial direction. In the contact section C, the spring materials S adjacent in the radial direction are all in contact. In addition, as shown in FIG. 2, the spring material S adjacent to radial direction is not contacting in areas other than the contact area C among the circumferential direction whole region of the spiral spring molded object 5. As shown in FIG. Sections other than the contact section C correspond to the “non-contact section” of the present invention.

  It is the inner reference portion D that creates the contact section C. Further, it is the inner reference portion D that adjusts the position of the contact section C. As shown in FIG. 2, the inner reference portion D is an extending direction of the spiral portion 51 with a straight line connecting the spiral shape center O of the spiral portion 51 and the outer contact portion B as a reference line L in the setting state G4. (Counterclockwise direction in FIG. 2) is arranged at a position θ having a central angle of 120 ° with the vortex shape center O as the center.

  Thus, in this step, the spiral spring molded body 5 is set. According to this step, the stress distribution is unlikely to vary over the entire length of the spiral portion 51 in the extending direction. Moreover, the spiral part 51 can be reduced in size (small diameter) over the full length of the spiral part 51 in the extending direction.

  As shown in FIG. 1, the spiral portion 21 of the spiral spring 1 after setting has an Archimedean curve shape in the natural state G1. In the natural state G1, the winding interval of the spiral portion 21 is constant. As shown in FIG. 2, the spiral part 51 can be plastically deformed in the winding direction by the difference between the natural state G1 and the natural state G3 by the setting process. That is, the spiral part 51 can be reduced in diameter.

[How to set the vortex shape center of the spiral in the setting state]
Next, a method for setting the vortex shape center of the spiral portion in the setting state of the spiral spring manufacturing method of the present embodiment will be described. FIGS. 5A to 5C are schematic diagrams illustrating a method for setting the center of the vortex shape of the spiral portion in the setting state.

  First, as shown in FIG. 5 (a), an approximate circle i1 of a predetermined section h1 starting from 0 is a winding position (a circumferential position when the end of the spiral portion 51 on the inner end 50 side is 0). The center o1 and the center angle θ1 of the approximate circle i1 are calculated. Next, as shown in FIG. 5B, an approximate circle i2 of a predetermined section h2 (> h1) starting from the winding position 0 is created, and the center o2 and the center angle θ2 of the approximate circle i2 are calculated. Thus, the center and the center angle are calculated while gradually expanding the predetermined section. As shown in FIG. 5C, when the approximate circle i3 of the predetermined section h3 (> h2) starting from the winding position 0 is created and the center o3 and the center angle θ3 of the approximate circle i3 are calculated, When θ3 reaches 90 ° (that is, the winding position 0.25), the center o3 at this time is set to the vortex shape center O (see FIG. 2) of the spiral portion 51 in the setting state G4.

[Function and effect]
Next, the effect of the spiral spring of this embodiment and its manufacturing method will be described. According to the method for manufacturing the spiral spring 1 of the present embodiment, as shown in FIG. 2, the inner reference portion D is independent from the inner end fixing member 6 in the setting step. For this reason, the freedom degree of the position setting of the inner end part 50 and the inner end fixing member 6 becomes high. Further, the degree of freedom in setting the position of the inner reference portion D, that is, the contact guiding member 53 is increased.

  Further, as shown in FIG. 2, in the setting state G4, at least one of the contact section C where the spring material S adjacent to the spiral spring 5 is in contact with the spiral spring molded body 5 and the spring material S adjacent to the radial direction. A non-contact section (a section other than the contact section C in the entire circumferential direction of the spiral spring molded body 5) in which the portion does not contact is disposed. That is, in the setting state G4, at least one non-contact section and at least one contact section C are arranged in the circumferential direction of the spiral spring molded body 5. In the contact section C, all the spring materials S adjacent in the radial direction are in contact. On the other hand, in the non-contact section, at least a part of the spring material S adjacent in the radial direction is not in contact.

  In the setting process, the contact section C is intentionally created by setting the inner reference portion D. In addition, the position of the contact section C is adjusted by setting the position of the inner reference portion D to a position θ having a center angle of 120 ° (within a section having a center angle of 80 ° to 160 °). When the position of the contact section C is adjusted, the bending moment of each part of the spiral spring molded body 5 can be controlled. For this reason, it becomes difficult for the spiral spring molded body 5 to be deformed (elliptical). Therefore, the variation of the stress distribution in the spiral part 51 can be reduced. In addition, the maximum value of stress can be reduced.

  Moreover, according to the spiral spring 1 of this embodiment, the curvature change and the dispersion | distribution of residual stress distribution over the extending direction full length of the spiral part 21 can be suppressed. Moreover, the spiral spring 1 can be reduced in size (smaller diameter). Also, assuming the dimensions of the inner counterpart 3, by setting the inner reference portion D as shown in FIG. 2, the interference of the spiral portion 21 with the inner counterpart 3 is suppressed as shown in FIG. Can do.

<Second embodiment>
The difference between the spiral spring of this embodiment and the manufacturing method thereof and the spiral spring of the first embodiment and manufacturing method thereof is that no contact induction member is arranged in the setting step. Here, only differences will be described. In FIG. 6, the side view of the spiral spring molded object in the setting process of the manufacturing method of the spiral spring of this embodiment is shown. In addition, about the site | part corresponding to FIG. 2, it shows with the same code | symbol.

  As shown in FIG. 6, the inner end portion 50 includes a straight portion 500 and a curved portion 501. The straight portion 500 is disposed on the radially inner side with respect to the spiral portion 51. The curved portion 501 connects the straight portion 500 and the spiral portion 51. The curvature of the curved portion 501 is constant. The center of curvature of the curved portion 501 is set on the radially inner side of the spiral portion 51. The inner contact portion A is disposed at the boundary between the curved portion 501 and the spiral portion 51. Further, in the inner contact portion A, the spring material S is in contact with the inner end fixing member 6.

  The spiral spring of this embodiment and the manufacturing method thereof and the spiral spring of the first embodiment and the manufacturing method thereof have the same operational effects with respect to the parts having the same configuration. In the setting process of the spiral spring manufacturing method of the present embodiment, the contact section C is intentionally created by setting the inner contact portion A. In addition, the position of the contact section C is adjusted by setting the position of the inner contact portion A to a position θ having a center angle of 120 ° (within a section having a center angle of 80 ° to 160 °). When the position of the contact section C is adjusted, the bending moment of each part of the spiral spring molded body 5 can be controlled. For this reason, it becomes difficult for the spiral spring molded body 5 to be deformed (elliptical). Therefore, the variation of the stress distribution in the spiral part 51 can be reduced. In addition, the maximum value of stress can be reduced. Moreover, according to the manufacturing method of the spiral spring of this embodiment, the inner side contact part A can be arrange | positioned using the boundary of the curve part 501 and the spiral part 51. FIG.

<Others>
The embodiment of the spiral spring and the manufacturing method thereof according to the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  The number of arrangement of the contact section C and the non-contact section is not particularly limited. In the contact section C, as shown in FIG. 2, the spring materials S that are in contact with each other in the radial direction may not be arranged linearly in the radial direction. For example, they may be arranged in a curved line shape (such as an S shape or a C shape) or a polygonal line shape (such as a Z shape or a zigzag shape). For example, in the contact section C, all the contact interfaces (contact interfaces between the spring materials S contacting in the radial direction) need only overlap when viewed from the radially outer side or the radially inner side.

  The contact state between the spring materials S that are in contact with each other in the radial direction in the contact section C is not particularly limited. Any of surface contact, line contact, and point contact may be used. Alternatively, a contact state in which these contact states are appropriately combined may be used.

  In the said embodiment, the spring material S adjacent to radial direction is not contacting at all in the non-contact area. However, in the non-contact section, the spring material S adjacent in the radial direction may be in partial contact.

  The shape of the spiral part 51 in the natural state is not particularly limited. For example, a Fermat curve shape, a Rituus curve shape, a clothoid curve shape, a hyperbolic spiral shape, a logarithmic spiral shape, or the like may be used. The material of the spring material S is not particularly limited. For example, carbon steel wires such as hard steel wires and piano wires, carbon steel strips, stainless steel wires, and stainless steel strips may be used. The shape of the spring material S is not particularly limited. It may be plate-shaped or linear. The cross-sectional shape in the short direction of the spring material S is not particularly limited. It may be a perfect circle, an ellipse, a rectangle, a trapezoid, an I shape, an L shape, a T shape, or the like. The spring material S may be solid or hollow.

  The shapes of the inner end portion 50 and the inner end fixing member 6 are not particularly limited. The inner end portion 50 only needs to be fixed to the inner end fixing member 6 so as not to swing. The shapes of the outer end portion 52 and the outer end fixing member 7 are not particularly limited. The outer end portion 52 may be fixed to the outer end fixing member 7 so as to be swingable. The cross-sectional shape of the contact guide member 53 in the axial direction is not particularly limited. It may be a polygonal shape such as an arc shape, a perfect circle shape, an elliptical shape, a triangle, a quadrangle, a hexagon, or an octagon.

  The inner contact portion A may be disposed at the contact point between the inner end fixing member 6 and the spiral portion 51. As shown in FIG. 6, when there are a plurality of contacts between the inner end fixing member 6 and the spiral portion 51, the inner contact portion may be arranged at the contact closest to the inner end portion 50. Thus, the inner contact portion A may not be disposed at the boundary between the curved portion 501 and the spiral portion 51. The use of the spiral spring 1 is not particularly limited. For example, you may use for the tumble mechanism of a vehicle seat, a seat height adjuster, etc.

  Hereinafter, the result of the FEM (finite element method) analysis in the setting state performed on the spiral spring molded body (Example 1) having the same shape as the spiral spring molded body 5 of the first embodiment shown in FIG. 2 will be described. .

<Analysis conditions>
Analysis was performed using commercially available software. In the analysis, the contact between the spring material S and each fixing member (the inner end fixing member 6 and the outer end fixing member 7) and the contact between the spring materials S were also considered. However, the number of turns of the spiral portion 51 was slightly more than 3.

<About the position θ of the inner reference portion D>
In FIG. 7, the relationship between the position of the inner side reference | standard part of Example 1 in a setting state and a stress increase rate is shown. The stress increase rate means the maximum stress value of the spiral spring molded body 5 when the stress design value is 100%. The design value σ is calculated from the following equation (1), where M is the torque, b is the lateral width (band width) of the spring material S, and h is the plate thickness of the spring material S.
σ = (6 × M) / (b × h ² ) (1)

  The stress applied to the spiral spring molded body 5 is allowed up to a 10% increase state (allowable limit in FIG. 7) with respect to the design value σ. As shown in FIG. 7, when the position θ (see FIG. 2) of the inner reference portion D is set to 80 ° or more and 160 ° or less, the maximum value of the stress of the spiral spring molded body 5 can be made to be below the allowable limit. . That is, the maximum value of stress can be reduced. On the other hand, when the position θ is less than 80 ° and when the position θ exceeds 160 °, the maximum value of the stress cannot be reduced.

<About stress distribution>
FIG. 8 shows the relationship between the winding position and stress of Example 1 in the setting state. As Example 2, data in the case where the position of the inner reference portion D is set to θ = 30 ° in Example 1 is shown. Further, as Comparative Example 1, data of a spiral spring that is free from the outer end and is non-contact type is shown.

  The winding position means a circumferential position when the end portion on the inner end portion 50 side of the spiral portion 51 is zero. When the winding position increases by 1, the angle advances 360 ° (one rotation) toward the outer end portion 52. For example, winding position 0 is at 0 ° position, winding position 0.5 is at 180 ° position, winding position 1 is at 360 ° position, winding position 4.5 is at 1620 °, winding position 5 is at 1800 °, respectively. Correspond.

  As shown in FIG. 8, in the case of the comparative example 1, the stress of winding position 0, 1, 2, 3 is small. On the other hand, the stress at the winding positions 0.5, 1.5, and 2.5 is large. Thus, in the case of the comparative example 1, the dispersion | variation in stress distribution is large. Further, the maximum value G of stress (stress near the winding position 2.5) is large.

  In contrast, in the case of Example 1 (where the position θ of the inner reference portion D is 100 °), the stress is substantially constant regardless of the winding position. That is, in the case of Example 1, the variation in stress distribution can be reduced. In addition, the maximum value of stress can be reduced.

  Also in the case of the second embodiment, although not as much as the first embodiment, the variation in the stress distribution can be reduced. Further, the maximum value F of stress (stress near the winding position 0.5) can be reduced.

1: spiral spring, 20: inner end, 21: spiral, 22: outer end, 3: inner counterpart, 4: outer counterpart, 5: spiral spring molded body, 50: inner end, 500: straight line Part, 501: curved part, 51: spiral part, 52: outer end part, 520: linear part, 521: curved part, 53: contact guide member, 6: inner end fixing member, 7: outer end fixing member.
θ: position, θ1 to θ3: center angle, A: inner contact portion, B: outer contact portion, C: contact section, D: inner reference portion, F: maximum value, G: maximum value, G1: natural state, G2 : Maximum deformation state, G3: natural state, G4: setting state, L: reference line, M: torque, O: center of vortex shape, S: spring material, b: center of curvature, h: plate thickness, h1 to h3 : Predetermined section, i1 to i3: approximate circle, o1 to o3: center.

Claims (6)

An inner end of a spiral spring molded body made of a strip-shaped spring material, comprising an inner end portion, an outer end portion, and a spiral portion connecting the inner end portion and the outer end portion in a spiral shape Fixing the portion to the inner end fixing member, locking the outer end portion to the outer end fixing member so as to be swingable, and placing an inner reference portion radially inside the spiral portion,
A contact section where all the spring materials adjacent to each other in the radial direction are in contact with the spiral portion, and a non-contact section where at least a part of the spring materials adjacent in the radial direction are not in contact with each other. By setting and
A method for manufacturing a spiral spring, comprising a setting step of imparting permanent set to the spiral spring molded body.   In the setting step, along the extending direction of the spiral portion, a straight line connecting the center of the spiral shape of the spiral portion and the outer contact portion where the outer end portion and the outer end fixing member are in contact is a reference line. The method for manufacturing a spiral spring according to claim 1, wherein the inner reference portion is disposed in a section having a center angle of 80 ° or more and 160 ° or less with the center of the spiral shape as a center.   The inner reference portion is an inner contact portion arranged at a boundary between the inner end portion and the spiral portion, or a contact point closest to the inner end portion among contact points between the inner end fixing member and the spiral portion. The manufacturing method of the spiral spring of Claim 1 or Claim 2.   3. The method of manufacturing a spiral spring according to claim 1, wherein the inner reference portion is disposed at a contact point between a contact guiding member disposed independently of the inner end fixing member and the spiral portion.   The method for manufacturing a spiral spring according to any one of claims 1 to 4, wherein a winding interval in a natural state of the spiral portion after the setting step is constant.   The spiral spring manufactured by the manufacturing method of the spiral spring in any one of Claims 1 thru | or 5.

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