Multi-strand coil

Abstract

To provide a multi-strand coil in which a bending rigidity changes along a longitudinal direction.SOLUTION: A multi-strand coil including a plurality of strands has a first section in which the plurality of strands are spirally wound and a second section in which one or more strands continuous from the first section are wound. The number of strands constituting the first section is larger than the number of strands constituting the second section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a multi-strand coil for use in industrial equipment and medical equipment. [Background technology]

[0002] 2. Description of the Related Art Conventionally, multi-strand coils formed by winding a plurality of strands in a spiral shape have been known. Patent Document 1 describes a multi-strand coil used as a component of a medical guidewire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-47451 A Summary of the Invention [Problem to be solved by the invention]

[0004] In multi-filament coils used in many applications such as industrial equipment and medical equipment, the mechanical properties of the multi-filament coil can be changed along the longitudinal direction of the multi-filament coil to improve the performance of the products in which the multi-filament coil is used. In particular, in medical equipment, it is required to change the bending rigidity of the multi-filament coil along the longitudinal direction of the multi-filament coil.

[0005] An object of the present invention is to provide a multi-strand coil whose bending stiffness varies along the longitudinal direction. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) One form of the present invention is a multi-strand coil made of a plurality of strands, the multi-strand coil having a first section in which the plurality of strands are wound in a spiral shape, and a second section in which one or more strands are wound continuing from the first section, the number of strands constituting the first section being greater than the number of strands constituting the second section.

[0008] According to this configuration, the number of wires constituting the first section is greater than the number of wires constituting the second section, so that the bending rigidity can be changed along the longitudinal direction of the multi-thread coil.

[0009] (2) In the multi-strand coil of the above embodiment, adjacent wires may be in contact with each other in both the first section and the second section.

[0010] According to this configuration, adjacent wires are in contact with each other, so that the torque transmission performance of the multi-strand coil can be improved.

[0011] (3) In the multi-thread coil of the above-described form, when the multi-thread coil is viewed from a direction perpendicular to the axial direction, the inclination of the strands constituting the first section with respect to the normal to the axis of the multi-thread coil may be greater than the inclination of the strands constituting the second section with respect to the normal to the axis of the multi-thread coil.

[0012] With this configuration, the inclination of the wires constituting the first section relative to the axis of the multi-thread coil is greater than the inclination of the wires constituting the second section relative to the axis of the multi-thread coil, thereby making it possible to change the bending rigidity of the multi-thread coil along the longitudinal direction of the multi-thread coil.

[0013] (4) In the multi-strand coil of the above form, an end of at least one of the wires constituting the first section is arranged on the outer periphery of the wire constituting the second section, the end having a cross-sectional area smaller than the cross-sectional area of ​​the cross-sectional area of ​​the wire in the first section that is continuous with the end.

[0014] According to this configuration, by arranging the end of the wire having a smaller cross-sectional area in the second section, the bending rigidity of the multi-thread coil can be changed along the longitudinal direction of the multi-thread coil.

[0015] The present invention can be realized in various aspects, for example, in the form of a guidewire, a method for manufacturing a guidewire, a catheter, a method for manufacturing a catheter, an endoscope, a dilator, and the like. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is an explanatory diagram illustrating a vertical cross section of the overall configuration of the multi-strand coil of the first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram illustrating the A1-A1 cross section of FIG. [Diagram 3] 2 is an explanatory diagram illustrating a cross section taken along the line B1-B1 of FIG. 1; [Figure 4] FIG. 4 is an explanatory diagram showing a schematic shape of a wire piece. [Diagram 5] 2 is an explanatory diagram illustrating a cross section taken along the line C1-C1 of FIG. 1; [Figure 6] FIG. 4 is an explanatory diagram illustrating a portion of a vertical cross section of a first section. [Figure 7] 11 is an explanatory diagram illustrating a portion of a vertical cross section of a second section. FIG. [Figure 8] FIG. 2 is an explanatory diagram illustrating an example of the appearance of a multi-thread coil. [Figure 9] FIG. 11 is an explanatory diagram illustrating a vertical cross section of the overall configuration of a multi-strand coil according to a second embodiment. [Figure 10] 10 is an explanatory diagram illustrating a cross section taken along the line A2-A2 of FIG. 9; [Figure 11] 10 is an explanatory diagram illustrating a cross section taken along the line B2-B2 of FIG. 9; [Figure 12] 10 is an explanatory diagram illustrating a cross section taken along the line C2-C2 of FIG. 9; [Figure 13] FIG. 11 is an explanatory diagram illustrating a portion of a vertical cross section of a third section. [Figure 14] FIG. 11 is an explanatory diagram illustrating a vertical cross section of the overall configuration of a multi-strand coil according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] First Embodiment FIG. 1 is an explanatory diagram illustrating a vertical cross section of the overall configuration of the multi-strand coil 1 of the first embodiment. The multi-strand coil 1 will be described with reference to FIGS. 1 to 8. The size of each component of the multi-strand coil 1 shown in FIGS. 1 to 8 is an example, and may be expressed on a scale different from the actual size. In the following, the end portion of each component of the multi-strand coil 1 located on the tip side will be referred to as the "tip", and the portion including the "tip" and extending from the tip to the middle toward the rear end will be referred to as the "tip portion". Similarly, the end portion of each component located on the rear end side will be referred to as the "rear end", and the portion including the "rear end" and extending from the rear end to the middle toward the tip side will be referred to as the "rear portion".

[0018] The multi-thread coil 1 is a coil body used as a component of industrial equipment, medical equipment, and the like.

[0019] The multi-wire coil 1 is formed by winding a plurality of wires (31-38) in a spiral shape. The multi-wire coil 1 has a first section S1 and a second section S2 in the order from the rear end side to the front end side in the longitudinal direction of the multi-wire coil 1. The first section S1 is formed by winding eight wires (31-38) in a spiral shape. The second section S2 is formed by winding seven wires (31-37) in a spiral shape. That is, the multi-wire coil 1 has a different number of wires (31-38) constituting the sections (S1, S2) in the longitudinal direction. In addition, a wire piece 50 at the end of the wire 38 is wound around the outer periphery of the wires (31-37) constituting the second section S2. Details of each section (S1, S2) will be described later.

[0020] The wires (31-38) have a circular cross section, but the cross section may be a shape other than a circle, such as a rectangle. The wire piece 50 has a substantially semicircular cross section, but the cross section may be a shape other than a semicircular cross section, such as a circle. The wires (31-38) in the first section S1 are densely wound so that adjacent wires (31-38) in the longitudinal direction come into contact with each other. The wires (31-37) in the second section S2 are similarly densely wound so that adjacent wires (31-38) in the longitudinal direction come into contact with each other.

[0021] The material of the wires (31-38) and wire piece 50 is not particularly limited, but examples of materials that can be used include stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, platinum, gold, tungsten, etc.

[0022] <Details of the first section S1> Fig. 2 is an explanatory diagram illustrating the A1-A1 cross section of Fig. 1. Fig. 2 illustrates a cross section of the first section S1. The first section S1 is formed by wire 31, wire 32, wire 33, wire 34, wire 35, wire 36, wire 37, and wire 38. The wires (31-38) are wound such that adjacent wires (31-38) in the circumferential direction of the multi-strand coil 1 are in contact with each other.

[0023] <Details of the second section S2> Fig. 3 is an explanatory diagram illustrating a cross section taken along line B1-B1 in Fig. 1. Fig. 4 is an explanatory diagram illustrating a schematic shape of the wire piece 50. Fig. 5 illustrates a cross section of a portion of the second section S2 including the wire piece 50. As described above, the second section S2 is formed by the wires 31, 32, 33, 34, 35, 36, and 37. The wires (31-37) are wound such that adjacent wires (31-37) in the circumferential direction of the multi-strand coil 1 are in contact with each other.

[0024] The cross-sectional area of ​​the tip of the wire 38 (FIG. 1) is smaller than that of the rear end of the wire 38. The end of the wire 38, which is provided on the tip side and has a smaller cross-sectional area than that of the rear end of the wire 38, is called the "wire piece 50". The wire piece 50 has a substantially semicircular cross section and is wound around the outer periphery of the wires (31-37) constituting the second section S2. Specifically, the wire piece 50 has a substantially semicircular cross section formed by leaving a part of the outer periphery of the wire 38 with a circular cross section and cutting the other part (see FIG. 4), and is wound along the recess 60 (FIG. 3) between the wire 31 and the wire 37. As described above, one of the wires (31-38) constituting the first section S1 becomes a wire piece 50 with a small cross-sectional area at the transition portion from the first section S1 to the second section S2 and is wound around the outer periphery of the second section S2. On the other hand, the wires (31-37) other than the wire 38 are continuously provided from the first section S1 to the second section S2. The wire piece 50 is the remainder of the wire 38, and since it does not function as a wire in itself, it is not counted in the number of wires.

[0025] 4 shows the continuous change in the cross section 52 of the wire piece 50. The wire piece 50 is composed of a transition section 55 in which the area of ​​the cross section 52 (cross-sectional area) gradually decreases from the rear end side to the front end side, and a constant section 56 in which the area and shape of the cross section 52 (cross-sectional shape) are approximately constant. When the cross section of the wire 50 is circular, the shape of the cross section 52 of the transition section 55 has a semicircular arc shape consisting of an arc 53 and a chord 54 thereof, and the area gradually decreases from the rear end side to the front end side. In this case, the length of the arc 53 gradually decreases as the area of ​​the cross section 52 decreases, and the length of the chord 54 gradually increases until it reaches a position where the chord 54 passes through the center of the circle, and gradually decreases after it reaches the center of the circle.

[0026] FIG. 5 is an explanatory diagram illustrating a cross section taken along the line C1-C1 in FIG. 1. FIG. 5 illustrates a cross section of the second section S2, which is close to the tip of the first section S1. The first section S1 and the second section S2 can be formed, for example, as follows. First, when the multiple-strand coil 1 is formed by winding a plurality of strands 31-38 in a spiral shape around a core bar, the distance between the strands 31 and 37 in the first section S1 in the axial direction of the multiple-strand coil 1 is reduced during the winding of the strands 31-38 from the rear end side to the front end side. As a result, the strands 38 located between the strands 31 and 37 are pushed outward in the radial direction of the multiple-strand coil 1. There is no particular limitation on the method for reducing the distance in the axial direction, but it can be performed, for example, by changing the pitch of the strands when winding them to be shorter halfway through. A part of the pushed-out strands 38 is polished with a polishing machine or the like to form a strand piece 50 having a substantially semicircular arc shape. This allows the number of strands (31 to 38) to be changed along the longitudinal direction of multi-strand coil 1.

[0027] In the present embodiment, the number of wires (31-37) constituting the second section S2 is reduced by processing an end of one wire 38 of the wires (31-38) constituting the first section S1 into a wire piece 50. In this way, the number of wires (31-38) constituting the multi-wire coil 1 along the longitudinal direction of the multi-wire coil 1 is changed without joining wires manufactured separately. Since the multi-wire coil 1 does not have joints between the wires (31-38), it is possible to prevent the multi-wire coil 1 from locally hardening due to the joints.

[0028] In this embodiment, "the number of wires (31-38) constituting each section (S1, S2)" ("the number of wires (31-38) in each section (S1, S2)") refers to the number of multiple wires (31-38) wound in a substantially cylindrical shape constituting each section (S1, S2) and having substantially the same cross-sectional area as each other. As described above, the number of wires (31-37) constituting the second section S2 does not include the wire pieces 50 that do not function as wires. In other words, the number of wires (31-37) constituting the second section S2 is seven.

[0029] FIG. 6 is an explanatory diagram illustrating a portion of a vertical cross section of the first section S1 of the multi-strand coil 1. Each strand (31-38) is wound at a predetermined angle with respect to the axis O1 of the multi-strand coil 1. In this embodiment, when the multi-strand coil 1 is viewed from a direction perpendicular to the axis O1, the angle between each strand (31-38) and a normal N1 to the axis O1 of the multi-strand coil 1 is called the "inclination angle β" of each strand (31-38). As the inclination of the strand (31-38) increases, the inclination angle β also increases. Here, the inclination angle β of the strands (31-38) constituting the first section S1 is called the "inclination angle β1." The inclination angles β1 of each strand (31-38) constituting the first section S1 are substantially the same. Moreover, the angle of each wire (31-38) of the multi-wrap coil 1 with respect to the axis O1 of the multi-wrap coil 1 is referred to as the "twist angle α" of each wire (31-38). In particular, the twist angle α of the wires (31-38) constituting the first section S1 is referred to as the "twist angle α1." The twist angles α1 of the wires (31-38) constituting the first section S1 are substantially the same. The inclination angle β1 and the twist angle α1 have a relationship that satisfies the equation α1 + β1 = 90°.

[0030] FIG. 7 is an explanatory diagram illustrating a portion of a vertical cross section of the second section S2 of the multi-wrap coil 1. The inclination angle β of the wires (31-37) that make up the second section S2 is called the "inclination angle β2." The inclination angles β2 of the wires (31-37) that make up the second section S2 are approximately the same. The twist angle α of the wires (31-37) that make up the second section S2 is called the "twist angle α2." The twist angles α2 of the wires (31-37) that make up the second section S2 are approximately the same. The inclination angle β2 and the twist angle α2 satisfy the formula α2+β2=90°.

[0031] The inclination angle β1 of the wires (31-38) constituting the first section S1 is larger than the inclination angle β2 of the wires (31-37) constituting the second section S2 (β1>β2). In other words, the inclination angles (β1, β2) of the multi-strand coil 1 decrease from the rear end to the front end.

[0032] The twist angle α2 of the wires (31-37) constituting the second section S2 is larger than the twist angle α1 (FIG. 6) of the wires (31-38) constituting the first section S1 (α2>α1). In other words, the twist angles (α1, α2) of the multi-thread coil 1 increase from the rear end side toward the front end side. This allows the bending rigidity of the multi-thread coil 1 to change along the longitudinal direction of the multi-thread coil 1. Specifically, the bending rigidity of the second section S2 can be made smaller than the bending rigidity of the first section S1.

[0033] 8 is an explanatory diagram illustrating an example of the appearance of the first section S1. As described above, in the first section S1, the wire piece 50 is wound along the recess 60 (FIG. 3) formed between the wires 31 and 37. As a result, the outer diameter of the multi-thread coil 1 is approximately constant along the longitudinal direction of the multi-thread coil 1. The inner diameter of the multi-thread coil 1 is also approximately constant along the longitudinal direction of the multi-thread coil 1. Since the inner and outer diameters of the multi-thread coil 1 are approximately constant along the longitudinal direction of the multi-thread coil 1, the multi-thread coil 1 is suitable as a component of a medical device to be inserted into the body, such as a guidewire or a catheter.

[0034] According to the multi-filament coil 1 of the present embodiment described above, the number of strands (31-38) constituting the first section S1 is greater than the number of strands (31-37) constituting the second section S2. This makes it possible to change the bending rigidity in the longitudinal direction of the multi-filament coil 1. For example, when the multi-filament coil 1 is used in a long medical device such as a guidewire or a catheter, by changing the bending rigidity of the multi-filament coil 1 along the longitudinal direction of the multi-filament coil 1, it is possible to change the flexibility, etc. of the medical device along the longitudinal direction of the medical device.

[0035] In the first section S1 and the second section S2, adjacent wires (31-38) are in contact with each other. This improves the torque transmission performance of the multi-wrap coil 1. In addition, because the gaps between adjacent wires (31-38) are small, when the outer periphery of the multi-wrap coil 1 is covered with a resin coating or the like, the possibility of the resin coating getting into the inside of the multi-wrap coil 1 can be reduced. This reduces the possibility of unevenness occurring on the outer periphery of the resin coating.

[0036] When the multi-filament coil 1 is viewed from a direction perpendicular to the axial direction, the inclination of the strands (31-38) constituting the first section S1 with respect to the normal to the axis O1 of the multi-filament coil 1 is greater than the inclination of the strands (31-37) constituting the second section S2 with respect to the normal to the axis O1 of the multi-filament coil 1. As a result, the twist angle α2 of the strands (31-37) constituting the second section S2 is greater than the twist angle α1 of the strands (31-38) constituting the first section S1, and the bending rigidity of the second section S2 is smaller than the bending rigidity of the first section S1. In addition, the number of strands in the second section S2 is smaller than the number of strands in the first section S1, and in addition, the twist angle α2 of the strands (31-37) constituting the second section S2 is greater than the twist angle α1 of the strands (31-38) constituting the first section S1, so that the bending rigidity can be changed over a larger range along the longitudinal direction of the multi-filament coil 1.

[0037] A wire piece 50, which is an end of the wire 38, is disposed on the outer periphery of the wires (31-37) constituting the second section S2. The cross-sectional area of ​​the wire piece 50 is smaller than the cross-sectional area of ​​the wire 38 in the first section S1. This can reduce the rigidity difference in the transition from the first section S1 to the second section S2. In addition, the torque transmission of the multi-filament coil 1 can be improved. In addition, for example, when the number of wires (31-38) constituting the multi-filament coil 1 is changed along the longitudinal direction by cutting the ends of the wires 38, the ends of the wires 38 remain on the outer periphery of the multi-filament coil 1, which may cause the wires 38 to protrude outside the multi-filament coil 1. However, in this embodiment, the wire piece 50 in the multi-filament coil 1 can reduce the possibility that the wires 38 will protrude outside the multi-filament coil 1.

[0038] <Second embodiment> 9 is an explanatory diagram illustrating a vertical cross section of the overall configuration of a multi-rand coil 1B of the second embodiment. The multi-rand coil 1B of the second embodiment differs from the multi-rand coil 1 of the first embodiment in that it has a third section S3B. Of the configuration of the multi-rand coil 1B, a description of the configuration common to the multi-rand coil 1 of the first embodiment will be omitted.

[0039] In addition to the first section S1B and the second section S2B, the multi-strand coil 1B has a third section S3B located further forward than the second section S2B. The third section S3B is composed of six wires (31-36). A wire piece 50B at the end of wire 38 is wound around the outer periphery of the wires (31-37) that constitute the second section S2B. In addition to the wire piece 50B, a wire piece 51 at the end of wire 37 is also wound around the outer periphery of the wires (31-36) that constitute the third section S3B. Details of the wire piece 51 will be described later.

[0040] Fig. 10 is an explanatory diagram illustrating the A2-A2 cross section of Fig. 9. Fig. 2 illustrates a cross section of the first section S1B. The first section S1B is formed by wires 31, 32, 33, 34, 35, 36, 37, and 38.

[0041] Fig. 11 is an explanatory diagram illustrating the cross section taken along line B2-B2 of Fig. 9. Fig. 11 illustrates a cross section of the second section S2B. The second section S2B is formed by wire 31, wire 32, wire 33, wire 34, wire 35, wire 36, wire 37, and wire piece 50B. Wire piece 50B is wound around the outer periphery of the wires (31-37) that form the second section S2. Wire piece 50B is wound along a recess 60B formed between wire 31 and wire 37.

[0042] <Details of wire piece 51> FIG. 12 is an explanatory diagram illustrating the cross section taken along line C2-C2 of FIG. 9. FIG. 12 illustrates a cross section of the third section S3B. The cross-sectional area of ​​the front end of the wire 37 (FIG. 9) is smaller than that of the rear end of the wire 37. The end of the wire 37, which is provided on the front end side and has a smaller cross-sectional area than that of the rear end of the wire 37, is called the "wire piece 51." The wire piece 51 has a cross section of a substantially semicircular arc shape, and is wound around the outer periphery of the wires (31-36) that constitute the third section S3B. The wire piece 51 has a shape similar to that of the wire piece 50. Specifically, the wire piece 51 has a substantially semicircular arc shape formed by leaving a part of the outer periphery of the wire 37 having a circular cross section and cutting the other part, and is wound along a recess 61 between the wires 31 and 32. As described above, one of the wires (31-37) constituting the second section S2B, wire 37, becomes wire piece 51 having a small cross-sectional area and is wound around the outer periphery of the third section S3B at the transition from the second section S2B to the third section S3B. On the other hand, the wires (31-36) other than wire 37 are continuously provided from the second section S2B to the third section S3B. Moreover, wire piece 50B is also wound in the third section S3B along the recess 60B formed between wire 31 and wire 36.

[0043] In this embodiment, "the number of wires (31-36) constituting the third section S3B" ("the number of wires (31-36) in the third section S3B") does not include the wire piece 50B and the wire piece 51. In other words, the number of wires (31-36) constituting the third section S3B is six.

[0044] FIG. 13 is an explanatory diagram illustrating a portion of the vertical cross section of the third section S3B of the multi-strand coil 1B. The inclination angle β of the strands (31-36) constituting the third section S3B is called the "inclination angle β3". The inclination angles β3 of the strands (31-36) constituting the third section S3B are substantially the same. The inclination angle β3 of the strands (31-36) constituting the third section S3B is smaller than the inclination angle β1 of the strands (31-37) constituting the first section S1B (β3>β1). Furthermore, the inclination angle β3 of the strands (31-36) constituting the third section S3B is smaller than the inclination angle β2 of the strands (31-37) constituting the second section S2B (β3>β2). That is, the inclination angle of the multi-strand coil 1B decreases from the rear end side to the front end side.

[0045] The twist angle α of the wires (31-36) constituting the third section S3B is called the "twist angle α3". The twist angles α3 of the wires (31-36) constituting the third section S3B are substantially the same. The twist angle α3 of the wires (31-36) constituting the third section S3B is larger than the twist angle α1 of the wires (31-37) constituting the first section S1B (α3>α1). Furthermore, the twist angle α3 of the wires (31-36) constituting the third section S3B is larger than the twist angle α2 of the wires (31-37) constituting the second section S2B (α3>α2). That is, the twist angle α of the multi-strand coil 1B increases from the rear end side toward the front end side. The multi-strand coil 1B described above can also change the bending rigidity in the longitudinal direction of the multi-strand coil 1B.

[0046] <Third embodiment> 14 is an explanatory diagram illustrating a vertical cross section of the overall configuration of a multi-wire coil 1C of the third embodiment. The multi-wire coil 1C of the third embodiment differs from the multi-wire coil 1 of the first embodiment in that a wire 38 is added between adjacent wires (31, 37), so that the number of wires (31-38) constituting the multi-wire coil 1C changes along the longitudinal direction. Of the configuration of the multi-wire coil 1C, a description of the configuration common to the multi-wire coil 1 of the first embodiment will be omitted.

[0047] The multi-thread coil 1C has a first section S1C and a second section S2C located rearward of the first section S1C. The second section S2C is composed of seven wires (31-37). In the first section S1C, a wire 38 is wound between the wire 31 and the wire 37. As a result, the number of wires (31-38) constituting the first section S1C is eight, which is more than the number of wires (31-37) constituting the second section S2C. The multi-thread coil 1C described above also makes it possible to change the bending rigidity in the longitudinal direction of the multi-thread coil 1C.

[0048] <Modification> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0049] <Variation 1> In the multi-wound coils (1, 1B, 1C) of the first to third embodiments, the cross-sectional shape of each of the wires (31-38) is circular. However, the cross-sectional shape of each of the wires (31-38) may be various shapes such as ellipse, square, rectangle, trapezoid, etc.

[0050] <Variation 2> In the multi-strand coil (1, 1B) of the first and second embodiments, the wire piece (50, 50B, 51) is formed by cutting a part of the wire (37, 38), etc. However, the wire piece (50, 50B, 51) can also be formed by connecting a wire rod manufactured separately from the wire 38 and having a smaller cross-sectional area than the cross-sectional area of ​​the wire (37, 38) to an end of the wire (37, 38).

[0051] <Variation 3> In the multi-filament coil 1 of the first embodiment, the wire piece 50 is wound up to the tip side of the multi-filament coil 1. However, the wire piece 50 may not be wound up to the tip of the multi-filament coil 1, and the tip of the wire piece 50 may be fixed to an intermediate portion of the multi-filament coil 1. In this case, a difference in bending rigidity of the multi-filament coil 1 can be generated before and after the tip of the wire piece 50. The end of the wire piece 50 may be joined to the outer periphery of the wires (31-37), and when the wire piece 50 is used as part of a medical device, it may be fixed to another member constituting the medical device.

[0052] <Variation 4> The multi-wrap coil (1, 1B) of the first and second embodiments may not have the wire piece (50, 50B, 51). When the multi-wrap coil (1, 1B) does not have the wire piece (50, 50B, 51), the number of wires (31-38) constituting each section (S1, S2, S3) can be changed by cutting a part of the wire (37, 38) at the tip of the wire (37, 38). When there is no wire piece, the difference in rigidity between adjacent sections can be increased.

[0053] <Variation 5> In the first embodiment, the wire piece 50 exists throughout the second section S2. In the second embodiment, the wire piece 50B exists throughout the second section S2B and the third section S3B, and the wire piece 51 exists throughout the third section S3B. However, in the multiple strand coil, the wire piece does not have to exist throughout the second section or the third section. For example, as shown in Fig. 4, the wire piece is formed of transition portion 55 and constant portion 56, but constant portion 56 may be cut so that the wire piece has only transition portion 55, or a portion of constant portion 56 may be cut so that the wire piece has both transition portion 55 and a portion of constant portion 56, and does not exist throughout the multi-strand coil. If no wire piece is present, there is a risk of a gap occurring at the boundary where the number of wires changes. By leaving constant portion 56 and transition portion 55, the gap can be filled. When the wire piece is not included or when a part of the wire piece is cut off, the tip of the cut wire (37, 38) or the wire piece may be fixed to the adjacent wire by any method, including, but not limited to, laser welding. [Explanation of symbols]

[0054] 1...Multi-strand coil 31~38…Plain wire 50, 51...piece of wire 52...Cross section 53...Arc 54…String 55…Transition part 56…Constant part 60, 61...recess O1…Axis S1: First section S2: Second section S3: Third section α1, α2, α3...Twist angle β1, β2, β3...Tilt angle

Claims

1. A multi-filament coil made up of a plurality of wires, a first section in which a plurality of wires are wound in a spiral shape; a second section wound with one or more wires continuing from the first section, A multi-filament coil in which the number of strands constituting the first section is greater than the number of strands constituting the second section.

2. The multi-thread coil according to claim 1, A multi-filament coil, wherein adjacent wires are in contact with each other in both the first section and the second section.

3. The multi-thread coil according to claim 1 or 2, A multi-thread coil, wherein when the multi-thread coil is viewed from a direction perpendicular to the axial direction, the inclination of the wires constituting the first section relative to the normal to the axis of the multi-thread coil is greater than the inclination of the wires constituting the second section relative to the normal to the axis of the multi-thread coil.

4. The multi-thread coil according to claim 1 or 2, A multi-thread coil, in which an end of at least one of the wires constituting the first section is arranged around the outer periphery of the wire constituting the second section, the end having a cross-sectional area smaller than the cross-sectional area of ​​the cross-sectional area of ​​the wire in the first section that is continuous with the end.

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