Cylindrical member, method for manufacturing cylindrical member, and endoscope

Abstract

This cylindrical member includes: a first sheath 22 having a distal end and a proximal end; a second sheath 23 having a distal end and a proximal end and through which the first sheath is inserted; and a cylindrical sleeve 21 having a first connection part 21a inserted into the inside of the distal end of the first sheath and a second connection part 21b inserted into the inside of the distal end of the second sheath and having an outer diameter larger than that of the first connection part.

Description

Cylindrical member, method for manufacturing a cylindrical member, endoscope

[0001] This invention relates to a cylindrical member that is inserted and disposed in an insertion portion of an endoscope or the like and through which a wire member or the like can be inserted and withdrawn freely, a method for manufacturing the cylindrical member, and an endoscope to which the cylindrical member is applied.

[0002] Conventionally, endoscopes have been widely used in, for example, the medical field and the industrial field. A medical endoscope used in the medical field has an insertion portion that is flexible, formed in an elongated tube shape, and provided with an imaging unit or the like at the distal end, and an operation portion that is connected to the proximal end side of the insertion portion and provided with various operation members or the like on the outer surface.

[0003] A conventional medical endoscope has a function of inserting the insertion portion into a body cavity of a living body (subject) to acquire, display, and record an image inside an organ or the like. A user observes and inspects a lesion or the like of an organ or the like based on the image acquired and displayed by the endoscope.

[0004] In a conventional medical endoscope of this type, various linear members or cylindrical members are inserted and disposed inside the insertion portion. Here, as various linear members or cylindrical members, for example, an operation wire member (treatment tool lifting operation wire) for performing a lifting and inversion operation of a treatment tool lifting table provided at the distal end, a light guide fiber bundle for guiding illumination light emitted from a lighting device to the distal end, an operation wire member (curving operation wire) for performing a curving operation of a bending portion, a treatment tool channel for guiding a treatment tool from the operation portion to the distal end, an air supply and water supply pipeline for guiding gas, liquid, or the like from the operation portion and the insertion portion to the distal end, and the like.

[0005] Conventionally, in order to avoid interference with other built-in objects disposed inside the insertion portion or to ensure flexibility and smooth insertion and withdrawal operations while protecting the outer surface, these linear members or cylindrical members are generally inserted and disposed inside the insertion portion in a state of being inserted into a cylindrical member composed of a plurality of layers.

[0006] For example, Japanese Utility Model Publication No. 1-23441 and International Publication No. WO2011 / 148894 disclose a cylindrical member through which an operating wire member of a treatment instrument lifting stand is inserted. Also, Japanese Patent Application Publication No. 2007-37649 discloses a cylindrical member through which a light guide fiber bundle is inserted. Furthermore, Japanese Patent No. 6100214 discloses a cylindrical member through which an operating wire member of a curved section is inserted. All of the conventional cylindrical members disclosed in these publications employ a configuration in which multiple cylindrical members are stacked in layers.

[0007] In this case, for example, a commonly used method is to stack multiple cylindrical members and then bond and fix them together using an adhesive or the like.

[0008] However, conventional fastening methods using adhesives and the like have various problems, such as requiring long assembly times due to the drying time of the adhesives, or the difficulty of assembly work required to form multiple layers, such as assembling metal cylindrical members or handling resin parts.

[0009] On the other hand, in recent years, so-called single-use endoscopes, which are disposed of after a single use, have become widely used in medical endoscopes, for example, to take infection control into consideration. This type of single-use endoscope has the advantage of eliminating the need for cleaning and sterilization processes that are carried out for reuse in conventional reusable endoscopes.

[0010] Furthermore, there is a constant demand for reducing manufacturing costs and lowering product prices in conventional endoscopes, and this demand is particularly strong for single-use endoscopes.

[0011] The present invention aims to provide a cylindrical member that can reduce manufacturing costs while reducing assembly man-hours and simplifying assembly work, a method for manufacturing the cylindrical member, and an endoscope to which the cylindrical member is applied.

[0012] To achieve the above objective, a cylindrical member according to one aspect of the present invention includes a first sheath having a tip and a base, a second sheath having a tip and a base through which the first sheath is inserted, a first connecting portion inserted into the inside of the tip of the first sheath, and a second connecting portion inserted into the inside of the tip of the second sheath having a larger outer diameter than the first connecting portion, and also includes a cylindrical sleeve.

[0013] A method for manufacturing a cylindrical member according to one aspect of the present invention is a method for manufacturing the cylindrical member, wherein the tip of the second sheath is brought into contact with the second connecting portion, and the second sheath is rotated in a direction that expands its diameter while pressing one of the second sheath and the second connecting portion against the other, and the second connecting portion is inserted into the inside of the tip of the second sheath.

[0014] An endoscope according to one aspect of the present invention comprises an insertion section having an elongated tube shape in which a tip portion, a curved portion, and a flexible tube portion are connected in order; an operating section to which the base end of the insertion section is connected and which is equipped with various operating members; a wire member positioned to pass through the insertion section and the operating section; and a cylindrical member through which the wire member is inserted, wherein the cylindrical member is formed by a first sheath having a tip and a base end; a second sheath having the tip and base end through which the first sheath is inserted; a sleeve having a cylindrical shape and a first connecting portion inserted into the tip of the first sheath and a second connecting portion inserted into the tip of the second sheath having a larger outer diameter than the first connecting portion, and through which the wire member is inserted. A method for manufacturing a cylindrical member according to another aspect of the present invention is a method for manufacturing a cylindrical member comprising a coil sheath having a tip and a base, and a sleeve having a cylindrical shape and a connecting portion having an outer diameter larger than the inner diameter of the tip of the coil sheath, wherein the tip of the coil sheath is brought into contact with the connecting portion, and the coil sheath is rotated in a direction that expands its diameter while pressing one of the coil sheath and the connecting portion against the other, thereby inserting the connecting portion into the inside of the tip of the coil sheath.

[0015] According to the present invention, it is possible to provide a cylindrical member that can contribute to reducing manufacturing costs while reducing assembly man-hours and simplifying assembly work, a method for manufacturing the cylindrical member, and an endoscope to which the cylindrical member is applied.

[0016] Figure 1 shows an external view illustrating the schematic configuration of an endoscope to which a cylindrical member of one embodiment of the present invention is applied; Figure 2 shows an enlarged cross-sectional view of a key part showing an enlarged portion of the internal configuration of the tip of the endoscope in Figure 1; Figure 3 shows a disassembled cross-sectional view of the cylindrical member of this embodiment; Figure 3 shows a diagram illustrating the assembly procedure of the cylindrical member of Figure 3, showing the assembled state of the first unit and the second unit, respectively; Figure 5 shows an intermediate cross-sectional view and an enlarged cross-sectional view of a key part showing the process of attaching the second unit to the first unit; Figure 3 shows a cross-sectional view and an enlarged cross-sectional view of a key part showing the completed assembly state of the cylindrical member; Figure 3 shows a reference example of the present invention, and a table showing the results of heat and moisture resistance tests performed for each PVC base material specification (example) applied to a cylindrical member constituting a part of a medical endoscope.

[0017] The present invention will be described below with reference to the illustrated embodiments. The drawings used in the following description are schematic. Therefore, in these drawings, each component is shown at a size that is recognizable on the drawing. For this reason, the dimensional relationships and scales of each component may differ on the drawing. The present invention is not limited to the illustrated forms with respect to the quantity, shape, size ratio, relative positional relationships, etc., of each component shown in each drawing.

[0018] First, before describing the detailed configuration of the cylindrical member of one embodiment of the present invention, the general configuration of the endoscope to which the cylindrical member is applied will be described below using Figure 1. Figure 1 is an external view showing the general configuration of the endoscope to which the cylindrical member of one embodiment of the present invention is applied.

[0019] As shown in Figure 1, the endoscope 1 is composed of an insertion section 2, an operating section 3, a universal cable 4, and the like.

[0020] The insertion section 2 is a long member shaped to be inserted into the lumen (inside organs, etc.) of a subject such as a living organism. The insertion section 2 has a flexible, elongated tube shape. The insertion section 2 is composed of a tip section 5, a curved section 6, and a flexible tube section 7. The insertion section 2 is connected to the operating section 3.

[0021] In the following explanation, the side of the insertion section 2 with the tip 5 will be referred to as the tip end of the endoscope 1. The side with the operating section 3 will be referred to as the proximal end of the endoscope 1.

[0022] The tip section 5 is located at the tip of the insertion section 2. Although not shown in the illustration, the tip section 5 is equipped with an imaging unit including an imaging optical system and an image sensor, an illumination unit including an observation optical system, an air and water supply nozzle, and an air and water supply pipeline. In addition, a treatment instrument lifting stand 50 is also provided at the tip section 5.

[0023] Here, the treatment instrument lifting stand 50 is a component unit provided to change the direction of protrusion of the treatment instrument (not shown) that is inserted into the treatment instrument insertion conduit 18 which is inserted into the insertion part 2 and then protrudes outward from the tip part 5.

[0024] Although not shown in the illustration here, the treatment instrument is, for example, equipped with forceps or the like at its tip, and is used to perform various procedures such as biopsies to collect a portion of living tissue from within a body cavity, or excisions of lesions within a body cavity.

[0025] The treatment instrument lifting stand 50 is connected to the treatment instrument operating lever 10 (described later; see Figure 1) provided on the operating unit 3 by a treatment instrument lifting operation wire member 17, which is positioned from the tip 5 through the insertion part 2 to the inside of the operating unit 3. This treatment instrument lifting operation wire member 17 is made of a flexible, elongated linear member.

[0026] The treatment tool lifting operation wire member 17 is inserted so as to be able to move back and forth along its long axis within the treatment tool lifting wire insertion conduit 20 (shown as a dotted line in Figure 1 for simplification; see Figure 2, etc. for details), which is a hollow cylindrical member inserted between the insertion part 2 and the operation part 3.

[0027] Here, the treatment tool lifting wire insertion conduit 20 is positioned to pass through the inside of the insertion section 2 from the tip section 5 to the base end (inside the operating section 3). This treatment tool lifting wire insertion conduit 20 has a flexible structure that allows it to freely follow the bending or flexing movement of the insertion section 2. At the same time, the treatment tool lifting wire insertion conduit 20 protects the outer surface of the treatment tool lifting operation wire member 17 and ensures that the treatment tool lifting operation wire member 17 moves smoothly back and forth inside the treatment tool lifting wire insertion conduit 20.

[0028] With this configuration, the instrument lifting stand 50 is driven in response to the operation input of the instrument operating lever 10 and rotates in a predetermined direction, so that the raising and lowering of the instrument relative to the tip 5 can always be performed smoothly.

[0029] The curved section 6 has its tip connected to the base end of the tip section 5. The curved section 6 is a tubular unit that is configured to bend actively in response to the input of the bending operation knob 9, which will be described later.

[0030] The flexible tube section 7 has its tip connected to the base end of the curved section 6. The flexible tube section 7 has its base end connected to the tip of the operating section 3. The flexible tube section 7 is formed from a flexible tube.

[0031] The operating section 3 is connected to the base end of the insertion section 2. In other words, the insertion section 2 is located on the tip side of the operating section 3. The operating section 3 is composed of a treatment instrument insertion port 8, a bending operation knob 9, a treatment instrument operation lever 10, a bending locking lever 11, and a plurality of operating members 12, etc.

[0032] The instrument insertion port 8 is an opening that connects to the instrument insertion conduit 18, which is inserted into the insertion section 2. A forceps plug 8a is provided in the instrument insertion port 8.

[0033] The curvature control knob 9 is an operating member for performing curvature operations on the curvature section 6. The curvature control knob 9 consists of two operating members: one for vertical curvature operation and another for horizontal curvature operation. The two operating members of the curvature control knob 9 are arranged on the outer surface of the operating section 3 in a superimposed configuration. In this case, the two operating members of the curvature control knob 9 are arranged to rotate freely around the same central axis, the pivot axis Ax. The curvature control knob is also called an angle knob.

[0034] The treatment instrument operating lever 10 is an operating member that inputs the operating force for raising and lowering the treatment instrument lifting base 50 provided at the tip 5. The treatment instrument operating lever 10 is configured to rotate freely within a predetermined range with the same pivot axis Ax as the curved operation knob 9 as the center of rotation.

[0035] The treatment instrument operating lever 10 is connected to the treatment instrument lifting stand 50 through a drive mechanism (not shown) disposed inside the operating section 3 and a treatment instrument lifting operation wire member 17 that passes through the insertion section 2.

[0036] With this configuration, the operating input from the instrument operating lever 10 is transmitted to the instrument lifting stand 50. As a result, the instrument lifting stand 50 is configured to change the direction in which the tip of an instrument (not shown) inserted into the instrument insertion conduit 18 protrudes.

[0037] The curvature fixing lever 11 is an operating member that acts on the curvature operation knob 9 to fix the curvature of the curvature section 6 at a desired position. The curvature fixing lever 11 is configured to rotate freely within a predetermined range with the same pivot axis Ax as the curvature operation knob 9 as its center of rotation.

[0038] The bending locking mechanism of the bending section 6 by the bending locking lever 11 is not directly related to the present invention. Therefore, the configuration of the bending locking lever 11 and the bending locking mechanism is assumed to be the same as that used in conventional endoscopes, and their detailed configuration and illustrations are omitted.

[0039] The multiple operating members 12 include, for example, operating switches for appropriately performing predetermined operations on image data acquired by the endoscope 1. These predetermined operations on image data include, for example, switching between displaying moving and still images, zooming in on images, recording images, and editing images.

[0040] Furthermore, the multiple operating members 12 include, for example, operating members for air supply / water supply operations and suction operations. Here, the air supply / water supply operation is an operating member that controls the fluid supply operation from a fluid supply unit (not shown) provided at the tip 5. The suction operation is an operating member that controls the pressure inside the treatment instrument insertion conduit 18 to a negative pressure. By performing this suction operation, for example, mucus adhering to the tip 5 can be sucked out and removed from the opening (not shown) of the treatment instrument insertion conduit 18 provided at the tip 5.

[0041] The universal cable 4 is a composite cable extending from one side of the operating unit 3. A scope connector 14 is provided at the end of the universal cable 4. This scope connector 14 is a connector component that connects to an external device, a video processor (not shown), which includes a light source device. The scope connector 14 is composed of electrical contacts and other components, as well as a light guide connector 13.

[0042] Between the scope connector 14, the universal cable 4, the operating unit 3, and the tip 5 of the insertion unit 2, a light guide bundle 15 and various signal lines 16 are inserted. The light guide bundle 15 is a component that transmits a light beam emitted from a light source device included in a video processor (not shown) to the tip 5 of the insertion unit 2. The light beam transmitted to the tip 5 by the light guide bundle 15 is emitted as illumination light that irradiates the object to be observed from an illumination unit (not shown) provided at the tip 5.

[0043] Further, the various signal lines 16 include, for example, an imaging cable that transmits an image signal (image data) acquired by an imaging unit (not shown) provided inside the tip portion 5 to a video processor (not shown), and a control signal cable that transmits a control signal emitted from the video processor to a component unit such as the imaging unit. The schematic configuration of the endoscope 1 is as described above.

[0044] Next, the configuration of the treatment tool lifting wire insertion conduit, which is a cylindrical member according to an embodiment of the present invention, will be described in detail below with reference to FIGS. 2 to 7. FIG. 2 is an enlarged cross-sectional view of a main part showing a part of the internal configuration of the tip portion of the endoscope in FIG. 1. In FIG. 2, the tip side portion of the cylindrical member (treatment tool lifting wire insertion conduit) of the present embodiment is mainly shown. FIG. 3 is a cross-sectional view showing the cylindrical member (treatment tool lifting wire insertion conduit) of the present embodiment taken out. Also in FIG. 3, the tip side portion of the cylindrical member (treatment tool lifting wire insertion conduit) is mainly shown. In FIGS. 2 and 3, detailed illustrations of the details of each component member are omitted, and only the schematic shape is shown. On the other hand, in FIGS. 4 to 7 below, each component member is shown in more detail. FIG. 4 is a cross-sectional view showing the cylindrical member (treatment tool lifting wire insertion conduit) of FIG. 3 disassembled.

[0045] FIGS. 5 to 7 are diagrams for explaining the assembly procedure of the cylindrical member (treatment tool lifting wire insertion conduit) of FIG. 3. Among these, FIG. 5 shows a state in which the first unit and the second unit are assembled respectively. FIG. 6 is a cross-sectional view showing the intermediate process when the second unit is assembled to the first unit, and also shows a partially enlarged cross-sectional view of the main part shown in detail. The diagram indicated by the reference sign [6Aa] in FIG. 6 is a partially enlarged cross-sectional view of the region indicated by the reference sign [6A] in FIG. 6. FIG. 7 is a cross-sectional view showing the completed state of assembly of the cylindrical member (treatment tool lifting wire insertion conduit) of FIG. 3, and also shows a partially enlarged cross-sectional view of the main part shown in detail. The diagram indicated by the reference sign [7Aa] in FIG. 7 is a partially enlarged cross-sectional view of the region indicated by the reference sign [7A] in FIG. 7.

[0046] The treatment tool lifting wire insertion conduit 20 exemplified in the present embodiment is a cylindrical member formed by laminating a plurality of hollow cylindrical members (tubular members) in layers.

[0047] As shown in FIG. 2 and the like, the lifting wire insertion pipe 20 of the treatment instrument is mainly composed of a sleeve 21, a resin tube 22, a coil pipe 23, and a heat shrinkable tube 24.

[0048] The sleeve 21 is a hollow cylindrical member of the first layer in the lifting wire insertion pipe 20 of the treatment instrument. The sleeve 21 is formed by processing a metal material, for example. As shown in FIG. 4 and the like, the sleeve 21 is formed having a first connection portion 21a, a second connection portion 21b, a tip tapered portion 21c, a flange portion 21d, and a through hole 21k.

[0049] The first connection portion 21a is a cylindrical portion inserted inside the tip of the resin tube 22 (details will be described later; the first sheath). The first connection portion 21a is formed having a predetermined region in the major axis direction from the base end side. In this case, the predetermined region of the first connection portion 21a in the present embodiment corresponds to the region within the range indicated by the symbol L1 in FIGS. 3 and 4, for example.

[0050] The second connection portion 21b is a cylindrical portion inserted inside the tip of the coil pipe 23 (details will be described later; the second sheath). The second connection portion 21b is formed having a predetermined region in the major axis direction from the tip of the first connection portion 21a toward the tip side of the sleeve 21. In this case, the predetermined region of the second connection portion 21b in the present embodiment corresponds to the region within the range indicated by the symbol L2 in FIGS. 3 and 4, for example.

[0051] In the sleeve 21, the second connection portion 21b is provided on the tip side of the first connection portion 21a.

[0052] As shown in FIGS. 3 and 4, the outer diameter D2 of the second connection portion 21b is set larger than the outer diameter D1 of the first connection portion 21a (D2 > D1). As a result, a step is formed at the boundary portion [A] (see FIGS. 3 and 4) between the first connection portion 21a and the second connection portion 21b.

[0053] A step is formed at position [A], resulting in a stepped end face 21g (see Figure 4) at the base end of the second connecting portion 21b. This stepped end face 21g has the function of positioning the resin tube 22 in the axial direction when the tip surface 22a (see Figures 4 and 5) of the resin tube 22 comes into contact with the first connecting portion 21a when it is inserted into the inside of the tip of the resin tube 22 and the treatment tool lifting wire insertion conduit 20 is assembled.

[0054] Furthermore, the second connecting portion 21b has a circumferential groove 21m and a chamfered portion 21n, as shown in Figure 4, etc. Note that in Figure 3, the circumferential groove 21m and the chamfered portion 21n are omitted from the illustration to avoid cluttering the drawing.

[0055] As shown in Figure 4, the circumferential groove 21m is a concave circumferential groove formed over the entire circumference of the outer periphery of the second connecting portion 21b in a predetermined area near the tip of the second connecting portion 21b. In this embodiment, the circumferential groove 21m is located at the tip of the second connecting portion 21b, adjacent to the base end side of the flange portion 21d (described later).

[0056] The circumferential groove 21m has the function of restricting the axial movement of the coil pipe 23 by fitting and locking a part of the tip region of the coil pipe 23 when the second connecting portion 21b is inserted inside the tip of the coil pipe 23 and the treatment tool lifting wire insertion conduit 20 is assembled (see Figure 7). Therefore, the circumferential groove 21m prevents the coil pipe 23, which has been press-fitted into the second connecting portion 21b, from being easily removed from the second connecting portion 21b.

[0057] In this case, a predetermined area of ​​the circumferential groove 21m has a length S (see Figures 4 and 7) that is approximately the length of two turns at the tip of the coil pipe 23, as shown in Figure 7. The depth dimension G1 (see Figures 4, 6, and 7) of the circumferential groove 21m is set to, for example, at least about 0.1 mm.

[0058] As shown in Figure 4, the chamfered portion 21n is formed by chamfering the corner between the stepped end face 21g formed on the base end side of the second connecting portion 21b and the outer circumferential surface of the second connecting portion 21b.

[0059] The chamfered portion 21n has the function of assisting the smooth insertion of the second connecting portion 21b into the inside of the tip of the coil pipe 23 without the tip surface 23a (see Figures 4 and 6) of the coil pipe 23 being obstructed by the stepped end surface 21g when the second connecting portion 21b is inserted into the inside of the tip of the coil pipe 23 and the treatment tool lifting wire insertion conduit 20 is assembled.

[0060] In other words, because the chamfered portion 21n is provided, the tip surface 23a of the coil pipe 23 smoothly overcomes the stepped end surface 21g of the sleeve 21 and is positioned on the outer surface of the second connecting portion 21b. Therefore, the second connecting portion 21b is smoothly inserted into the inside of the tip of the coil pipe 23.

[0061] The tip tapered portion 21c is a tapered-shaped region formed in a predetermined area on the tip side of the sleeve 21. In this embodiment, the predetermined area of ​​the tip tapered portion 21c corresponds to, for example, the area indicated by reference numeral L3 in Figures 3 and 4.

[0062] The tapered tip portion 21c is formed with a tapered shape that tapers towards the tip of the sleeve 21, with the tip of the flange portion 21d as its base. As shown in Figure 2, this tapered tip portion 21c is fitted and fixed to a predetermined part (fixing hole 5b) of the hard tip portion 5a, which constitutes a part of the tip portion 5. With this configuration, the treatment tool lifting wire insertion conduit 20 is fixed to the tip portion 5. The tapered tip portion 21c of the sleeve 21 has the function of fixing the tip region of the treatment tool lifting wire insertion conduit 20 to the fixing hole 5b of the tip portion 5.

[0063] The flange portion 21d is an outward-facing flange-shaped portion formed between the base end of the tip tapered portion 21c and the tip end of the second connecting portion 21b. The tip end face 21e of the flange portion 21d (see Figure 4) has the function of positioning the sleeve 21 in the longitudinal direction when the sleeve 21 is fitted into the fixing hole 5b of the tip hard portion 5a.

[0064] Furthermore, the end face 21f (see Figure 4) on the base end side of the flange portion 21d has the function of positioning the coil pipe 23 in the longitudinal direction when the second connecting portion 21b is inserted inside the tip of the coil pipe 23 and the treatment tool lifting wire insertion conduit 20 is assembled, by contacting the tip surface 23a (see Figures 4 and 7) of the coil pipe 23.

[0065] As shown in Figure 4, the sleeve 21 formed in this manner has a through hole 21k that penetrates in the longitudinal direction. This through hole 21k penetrates from the base end face 21h of the sleeve 21 through the inner regions corresponding to the first connecting portion 21a, the second connecting portion 21b, the flange portion 21d, and the tapered tip portion 21c, with approximately the same diameter to the tip face of the tapered tip portion 21c. As a result, the sleeve 21 forms a hollow cylindrical shape.

[0066] The resin tube 22 is the second layer of hollow cylindrical member in the treatment tool lifting wire insertion conduit 20. The resin tube 22 has a tip and a base, and is made of a resin material that is flexible and expandable overall. Inside the resin tube 22, the treatment tool lifting operation wire member 17 (see Figure 1) is inserted and arranged so as to be able to move back and forth in the longitudinal direction.

[0067] Here, the resin tube 22 has a smooth inner surface to ensure the smooth forward and backward movement of the treatment instrument lifting operation wire member 17. In this way, the resin tube 22 functions as a first sheath that protects the outer surface of the treatment instrument lifting operation wire member 17 and ensures the smooth forward and backward movement of the treatment instrument lifting operation wire member 17 in the longitudinal direction.

[0068] Furthermore, as described above, the first connecting portion 21a is inserted into the inner tip of the resin tube 22. At this time, the inner surface of the resin tube 22 and the outer surface of the first connecting portion 21a are configured to be in a watertight seal. For this purpose, the inner diameter D5 of the resin tube 22 is formed to be smaller than the outer diameter D1 of the first connecting portion 21a (D1 > D5; see Figures 3 and 4).

[0069] Here, when inserting the first connecting portion 21a into the inside of the tip of the resin tube 22, the tip of the resin tube 22 is deformed to an expanded diameter state. For this purpose, the resin tube 22 is formed to be particularly flexible in the radial direction.

[0070] When the first connecting portion 21a is inserted into the inner tip of the resin tube 22, the resin tube 22 adheres tightly to the outer surface of the first connecting portion 21a due to its own expansion and contraction force. In this case, adhesive 25 or the like is applied to the surfaces where the resin tube 22 and the first connecting portion 21a adhere to each other to bond and fix them in place.

[0071] Furthermore, when the first connecting portion 21a is inserted into the inner tip of the resin tube 22, the tip surface 22a of the resin tube 22 is positioned to abut against the stepped end surface 21g. When the resin tube 22 is positioned in this location, it is fixed using adhesive 25 or the like in predetermined areas between the inner tip of the resin tube 22 and the outer tip surface of the first connecting portion 21a.

[0072] With this configuration, when the first connecting portion 21a is inserted into the inner tip of the resin tube 22, the resin tube 22 is in close contact with the outer circumference of the first connecting portion 21a, pressing against it. In addition, the inner surface of the tip of the resin tube 22 and the outer surface of the first connecting portion 21a are bonded and fixed together. Therefore, the resin tube 22 is not easily removed from the first connecting portion 21a and is integrally incorporated with the sleeve 21 through the first connecting portion 21a.

[0073] Here, the unit in which the sleeve 21 and the resin tube 22 are integrated is referred to as the first unit 20A (see Figure 5).

[0074] The coil pipe 23 is the third layer of hollow cylindrical member in the wire insertion conduit 20 for the treatment tool. The coil pipe 23 has a tip and a base, and is made of a material that is flexible and rigid overall. The coil pipe 23 is a cylindrical member (pipe) formed into a coil shape by tightly winding a circular wire or plate made of a metal material, for example.

[0075] A resin tube 22 (first sheath) is inserted and positioned inside the coil pipe 23. As a result, the coil pipe 23 covers and protects the outer surface of the resin tube 22 (first sheath) and functions as a second sheath through which the resin tube 22 is inserted.

[0076] Furthermore, as described above, the second connecting portion 21b is inserted into the inner tip of the coil pipe 23. At this time (when the second connecting portion 21b is inserted into the inner tip of the coil pipe 23), the coil pipe 23 is set to have a pressing force acting in a direction that reduces its diameter toward the outer surface of the second connecting portion 21b.

[0077] For this reason, the inner diameter D4 of the coil pipe 23 in its natural state or unloaded state (hereinafter simply referred to as the natural state) is formed to be slightly smaller in diameter than the outer diameter D2 of the second connection portion 21b (D2 > D4; see Figures 6 and 7). In this case, a gap G4 is created between the inner diameter D4 of the coil pipe 23 and the outer diameter D2 of the second connection portion 21b, as shown in Figures 6 and 7. This gap G4 is, for example, about 0.1 mm.

[0078] With this configuration (D2 > D4), when the second connecting portion 21b is inserted into the inside of the tip of the coil pipe 23, the coil pipe 23 is in a press-fit state, pressing against the outer circumference of the second connecting portion 21b. Therefore, the coil pipe 23 cannot be easily removed and is integrated with the sleeve 21 through the second connecting portion 21b.

[0079] Furthermore, when inserting the second connecting portion 21b into the inside of the tip of the coil pipe 23, it is necessary to expand the diameter of the tip of the coil pipe 23. This is because the outer diameter D2 of the second connecting portion 21b is different from the inner diameter D4 of the coil pipe 23 in its natural state (D2 > D4).

[0080] To this end, the coil pipe 23 is formed to be particularly flexible in the radial direction. Furthermore, when inserting the second connecting portion 21b, which has a large outer diameter D2, into the inner tip of the coil pipe 23, which has a small inner diameter D4, a chamfered portion 21n is provided so that the tip surface 23a of the coil pipe 23 can smoothly overcome the stepped end surface 21g without being obstructed by it.

[0081] Furthermore, in order to expand the diameter of the tip of the coil pipe 23, means such as rotating the coil pipe 23 in a direction that expands its inner diameter relative to the fixed sleeve 21 (second connection part 21b) are used. A detailed explanation of the assembly of the treatment tool lifting wire insertion conduit 20 will be given later.

[0082] Furthermore, the outer diameter D2 of the second connection portion 21b is slightly larger than the inner diameter D4 of the coil pipe 23 at the position corresponding to the first connection portion 21a (the region in which the first connection portion 21a is inserted) (in its natural state; see Figure 7) (D2 > D4).

[0083] Furthermore, the outer diameter D2 of the second connection portion 21b is larger than the outer diameter D3 of the resin tube 22 when it is connected to the first connection portion 21a (expanded state) (D2 > D3; see Figures 6 and 7).

[0084] Furthermore, the inner diameter D4 of the second sheath 23 at the position corresponding to the first connection portion 21a (in its natural state) is larger than the outer diameter D3 of the first sheath 22 when it is connected to the first connection portion 21a (in its expanded diameter state) (D4 > D3).

[0085] Furthermore, the inner diameter D4 (natural state) of the coil pipe 23 in the region where the first connecting portion 21a is inserted is smaller than the inner diameter of the coil pipe 23 (expanded state) in the region where the second connecting portion 21b is inserted. Here, the inner diameter of the coil pipe 23 (expanded state) in the region where the second connecting portion 21b is inserted is approximately equal to the outer diameter D2 of the second connecting portion 21b (therefore, D2 > D4).

[0086] With this configuration, in the treatment tool lifting wire insertion conduit 20 of this embodiment, a small gap is always created between the inner surface of the coil pipe 23 (second sheath) and the outer surface of the resin tube 22 (first sheath) in the region on the base end side of the second connection portion 21b.

[0087] Specifically, for example, in the region of the first connection portion 21a, a gap G2 always exists between the inner surface of the coil pipe 23 (see reference numeral D4) and the outer surface of the resin tube 22 in its expanded diameter state (see reference numeral D3) (see enlarged view [6Aa] in Figure 6 and enlarged view [7Aa] in Figure 7; D4).

[0088] Furthermore, in the region further towards the base end [B] of the first connection portion 21a, a gap G3 always exists between the inner surface (inner diameter D4) of the coil pipe 23 and the natural outer surface (outer diameter D6) of the resin tube 22 (see Figures 6 and 7).

[0089] The symbols D1, D2, D3, D4, D5, D6, G1, G2, G3, and G4 are defined as follows. That is, D1...Outer diameter of the first connection part 21a (=Inner diameter of the resin tube 22 when expanded), D2...Outer diameter of the second connection part 21b (=Inner diameter of the coil pipe 23 when expanded), D3...Outer diameter of the resin tube 22 (expanded state), D4...Inner diameter of the coil pipe 23 (natural state), D5...Inner diameter of the resin tube 22 (natural state), D6...Outer diameter of the resin tube 22 (natural state), G1...Depth of the circumferential groove 21m, G2...Gap between the inner diameter D4 of the coil pipe 23 (natural state) and the outer diameter D3 of the resin tube 22 (expanded state), G3...Gap between the inner diameter D4 of the coil pipe 23 (natural state) and the outer diameter D6 of the resin tube 22 (natural state), G4...Gap between the inner diameter D4 of the coil pipe 23 (natural state) and the outer diameter D2 of the second connection part 21b.

[0090] The heat-shrinkable tube 24 is the fourth layer of hollow cylindrical member in the wire insertion conduit 20 for the treatment device. The heat-shrinkable tube 24 is a flexible resin outer tube that covers and protects the outer surface of the coil pipe 23.

[0091] In the following explanation, the unit in which the coil pipe 23 and the heat shrink tubing 24 are integrated will be referred to as the second unit 20B (see Figure 5).

[0092] The heat shrink tubing 24 is positioned at a predetermined location on the outer circumference of the coil pipe 23. At this time, the tip surface 24a of the heat shrink tubing 24 is positioned to expose a predetermined region S2 (see Figures 5 to 7) near the tip of the coil pipe 23. The predetermined region S2 near the tip of the coil pipe 23 refers to the region between the position of the tip surface 23a of the coil pipe 23 and the position of the tip surface 24a of the heat shrink tubing 24.

[0093] Furthermore, when the first unit 20A and the second unit 20B are integrated to form the treatment tool lifting wire insertion conduit 20 (as shown in Figures 3 and 7), the tip surface 24a of the heat shrink tubing 24 is positioned on the outer surface of the coil pipe 23 within a region L1 between a position [A] corresponding to the tip of the first connection portion 21a and a position [B] corresponding to the base end of the first connection portion 21a.

[0094] This means that, for example, if the tip surface 24a of the heat shrink tube 24 is positioned further forward than the stepped end surface 21g of the first connection portion 21a (or if the tip region of the heat shrink tube 24 covers the outer surface of a predetermined region S2 of the coil pipe 23), when the coil pipe 23 is press-fitted into the second connection portion 21b of the sleeve 21 to attach the second unit 20B to the first unit 20A, the heat shrink tube 24 may obstruct the expansion of the coil pipe 23, or the heat shrink tube 24 may get caught in the coil gaps of the coil pipe 23. If this happens, the assembly process will be hindered, and efficient assembly will not be possible.

[0095] Therefore, it is desirable to avoid positioning the heat shrink tube 24 on the outer surface of a predetermined region S2 at the tip of the coil pipe 23, and to position the tip surface 24a of the heat shrink tube 24 closer to the base end than the stepped end surface 21g of the first connection portion 21a. This ensures the degree of freedom for diameter expansion and bending at the press-fit portion of the coil pipe 23.

[0096] As described above, the treatment instrument lifting wire insertion conduit 20 of this embodiment has a four-layer structure, with the treatment instrument lifting operation wire member 17 inserted and positioned inside the first layer sleeve 21 and the second layer resin tube 22. The treatment instrument lifting wire insertion conduit 20 is configured such that the sleeve 21 is fixed to a predetermined location (fixing hole 5b) of the tip portion 5 of the endoscope 1.

[0097] In this state, when the treatment tool lifting operation wire member 17 is inserted through the treatment tool lifting wire insertion conduit 20, the tip of the treatment tool lifting operation wire member 17 protrudes outward from the tip of the sleeve 21 and is connected to the treatment tool lifting base 50.

[0098] The treatment tool lifting wire insertion conduit 20 of this embodiment, configured as described above, is assembled and manufactured by the following procedure in general.

[0099] First, the tip of the resin tube 22 (first sheath) is inserted into the first connection portion 21a of the sleeve 21. At this time, the tip of the resin tube 22 is expanded in diameter so that the first connection portion 21a is inserted inside the tip of the resin tube 22.

[0100] Here, the tip of the resin tube 22 is positioned so that its tip surface 22a abuts against the stepped end surface 21g of the sleeve 21. As a result, the outer surface of the first connection portion 21a is covered and protected by the tip region of the resin tube 22.

[0101] At this time, the area near the tip of the outer surface of the first connecting portion 21a and the area near the tip of the inner surface of the tip of the resin tube 22 are bonded and fixed together with adhesive.

[0102] In this way, the sleeve 21 and the resin tube 22 are integrated, and the first unit 20A is assembled (see Figure 5).

[0103] Next, the heat-shrinkable tube 24 is heat-shrinkable and fixed to a predetermined area on the outer circumference of the coil pipe 23 (second sheath). This integrates the coil pipe 23 and the heat-shrinkable tube 24, and the second unit 20B is assembled (see Figure 5).

[0104] Next, one of the first unit 20A and the second unit 20B is fixed in place. Here, for example, we will illustrate the case where the first unit 20A is fixed in place during the work.

[0105] Here, we will explain the process of inserting the second connection portion 21b of the sleeve 21 in the fixed first unit 20A into the inside of the tip of the coil pipe 23 of the second unit 20B.

[0106] First, the tip surface 24a of the coil pipe 23 of the second unit 20B is brought into contact with the base end surface (chamfered portion 21n of the stepped end surface 21g) of the second connection portion 21b of the sleeve 21 of the fixed first unit 20A. At this time, the central axis of the first unit 20A and the central axis of the second unit 20B are brought into approximately coincidence.

[0107] In this state, the coil pipe 23 is pressed toward the second connection portion 21b and rotated in a direction that expands the inner diameter of the coil pipe 23. As a result, the tip surface 23a of the coil pipe 23 expands in diameter along the bevel of the chamfered portion 21n. The pressing and rotation of the coil pipe 23 are continued. Eventually, the tip surface 23a of the coil pipe 23 goes over the chamfered portion 21n. The coil pipe 23 then reaches the outer circumferential surface of the second connection portion 21b. If the coil pipe 23 is pressed toward the second connection portion 21b further from this point, the tip surface 23a of the coil pipe 23 will eventually come into contact with the base end surface 21f of the flange portion 21d. The coil pipe 23 is positioned at this position.

[0108] In this way, the first unit 20A and the second unit 20B are assembled to form the treatment tool lifting wire insertion conduit 20 (cylindrical member) of this embodiment.

[0109] As described above, the treatment tool lifting wire insertion conduit 20, which is a cylindrical member according to the above embodiment, is a cylindrical member with a multi-layer structure formed by stacking multiple (three or four) cylindrical members in layers.

[0110] In other words, the treatment tool lifting wire insertion conduit 20 consists of a resin tube 22 (first sheath), a coil pipe 23 (second sheath) through which the resin tube 22 (first sheath) is inserted, and a cylindrical sleeve 21.

[0111] Here, the sleeve 21 has a first connecting portion 21a that is inserted into the inside of the tip of the resin tube 22 (first sheath), and a second connecting portion 21b that is inserted into the inside of the tip of the coil pipe 23 (second sheath). The second connecting portion (21b) has a larger outer diameter than the first connecting portion (21a).

[0112] Therefore, in the treatment tool lifting wire insertion conduit 20 of this embodiment, when the first connecting portion 21a is inserted inside the tip of the resin tube 22 and the second connecting portion 21b is inserted inside the tip of the coil pipe 23, the outer diameter D2 of the second connecting portion 21b is formed to be larger in diameter than the outer diameter D1 of the first connecting portion 21a, and a step is provided (D2 > D1).

[0113] In the sleeve (21), the second connecting portion 21b is provided closer to the tip than the first connecting portion 21a.

[0114] Furthermore, the outer diameter D2 of the second connecting portion 21b is larger than the outer diameter D3 of the first sheath 22 when it is connected to the first connecting portion 21a (in the expanded diameter state) (D2 > D3).

[0115] Furthermore, the inner diameter D4 of the second sheath 23 at the position corresponding to the first connection portion 21a (in its natural state) is larger than the outer diameter D3 of the first sheath 22 when it is connected to the first connection portion 21a (in its expanded diameter state) (D4 > D3).

[0116] Furthermore, in the coil pipe 23 (second sheath), the inner diameter D4 of the region where the first connecting portion 21a is inserted is smaller than the inner diameter D4 of the region where the second connecting portion 21b is inserted (approximately equal to the outer diameter D2 of the second connecting portion 21b) (D2 > D4), and the outer diameter D2 of the second connecting portion 21b is larger than the inner diameter D4 of the region where the first connecting portion 21a is inserted (D2 > D4).

[0117] Furthermore, the outer diameter D1 of the first connection portion 21a is larger than the inner diameter D5 of the resin tube 22 (first sheath) (D1 > D5).

[0118] Furthermore, when inserting the second connecting portion 21b into the inside of the tip of the coil pipe 23 (second sheath), it is done by press-fitting.

[0119] With this configuration, the wire insertion conduit 20 for lifting the treatment tool of this embodiment ensures a normal gap between the resin tube 22 and the coil pipe 23, preventing the resin tube 22 and the coil pipe 23 from rubbing against each other and thus preventing damage or breakage.

[0120] When inserting the first connecting portion 21a into the inside of the tip of the resin tube 22, the resin tube 22 is expanded in diameter and fitted over the outer surface of the first connecting portion 21a, thereby ensuring a tight seal between the outer surface of the first connecting portion 21a and the inner surface of the resin tube 22, and thus ensuring watertightness.

[0121] Since the second connecting portion 21b is inserted into the inside of the tip of the coil pipe 23 by press-fitting, it can contribute to reducing the number of man-hours required for manufacturing.

[0122] Furthermore, the coil pipe 23 (second sheath) has a heat-shrinkable tube 24 (outer tube) that covers the outer surface, and the tip of this heat-shrinkable tube 24 (outer tube) is positioned within a region L1 on the outer surface of the coil pipe 23 (second sheath) between a position [A] corresponding to the tip of the first connection portion 21a and a position [B] corresponding to the base end.

[0123] With this configuration, the press-fitting process of the second connecting portion 21b into the coil pipe 23 is not hindered, allowing for efficient assembly and thus contributing to a reduction in man-hours.

[0124] Furthermore, the sleeve 21 has a tapered tip portion 21c that forms a tapered region at the tip end, and a flange portion 21d is provided at the base end of the tapered tip portion 21c.

[0125] According to this, the insertion conduit 20 for the treatment instrument lifting wire can be reliably attached to the tip 5 of the endoscope 1, and its positioning can be reliably performed.

[0126] The sleeve 21 has a concave circumferential groove 21m on the base end side of the flange portion 21d. The depth of this circumferential groove 21m is at least 0.1 mm.

[0127] According to this, when the second connecting portion 21b is inserted into the inside of the tip of the coil pipe 23 and press-fitted, the tip of the coil pipe 23 can be locked in place by the circumferential groove 21m, thereby preventing the coil pipe 23 from being easily removed.

[0128] Incidentally, in recent years, in medical endoscopes, there has been a need to select lower-cost materials, taking into consideration the reduction of manufacturing costs. For example, there is a demand to use cheaper materials such as PVC (polyvinyl chloride) as the base material for the outer sheath (outer casing, outer tube) used for components consisting of elongated tube shapes such as the insertion section of an endoscope and universal cables, instead of the conventionally widely used urethane-based materials.

[0129] However, if PVC used for tubular components in medical applications (such as catheters) is applied to tubular components in endoscopes (such as insertion tubes and universal cables) with the same specifications, a problem arises: for example, the so-called bleed-out phenomenon occurs during the heat and moisture resistance test that is normally performed in medical endoscopes. Here, the bleed-out phenomenon is the phenomenon in which plasticizers contained in the base material rise to the surface over time.

[0130] Therefore, in tubular members used in medical endoscopes, which are made of PVC containing plasticizers, there is a need to suppress the bleed-out phenomenon that occurs after heat and moisture resistance testing.

[0131] One possible method for achieving this is to set the degree of polymerization of the PVC to 2000 or more and less than 3000 in a cylindrical member made of PVC containing a plasticizer, which is used in medical endoscopes.

[0132] Thus, by setting the degree of polymerization of PVC higher than conventional methods, the three-dimensional structure becomes denser, and molecular mobility is suppressed even when using low-molecular-weight plasticizers. Therefore, it is expected that this will suppress the plasticizer bleed-out phenomenon after heat and humidity resistance tests.

[0133] Furthermore, when forming tubular members using PVC containing plasticizers as a base material, the degree of polymerization of the PVC is usually less than 2000 when using extrusion molding. It has been found that forming tubular members becomes difficult when using PVC with a degree of polymerization of 2000 or higher.

[0134] Therefore, in order to form a tubular member using PVC with a degree of polymerization of 2000 or higher, it is advisable to add a lubricant, for example. In this case, a metal stearate-based lubricant is preferable, for example.

[0135] Figure 8 is a diagram illustrating a reference example of the present invention, and is a table showing the results of heat and humidity resistance tests conducted for each PVC base material specification (example) applied to a tubular member constituting a part of a medical endoscope. Here, the conditions for the heat and humidity resistance test were a temperature of 60 degrees Celsius, a humidity of 50%, and storage for two weeks.

[0136] In Figure 8, in the appearance quality evaluation column, products that are free from bleeding (seepage) and have a "good" tube moldability rating can be evaluated as acceptable.

[0137] As shown in Figure 8, in a tubular member used in a medical endoscope and made of PVC containing a plasticizer, by adopting a configuration such as (1) setting the degree of polymerization of the PVC to 2000 or more and less than 3000, and (2) adding a metal stearate salt-based lubricant (Examples 1 to 4 in Figure 8), it can be confirmed that the plasticizer bleed-out phenomenon can be suppressed by condition (1) above, and that moldability can be maintained even at a high degree of polymerization by condition (2) above.

[0138] In Figure 8, Comparative Examples 1 and 2 are examples where the degree of polymerization is less than 2000. In this case, a bleed-out phenomenon occurs.

[0139] Furthermore, in Figure 8, Comparative Examples 3 and 4 are examples where the degree of polymerization is 3000 or higher. In this case, the tube moldability is judged as "impossible."

[0140] The present invention is not limited to the embodiments described above, and various modifications and applications can be implemented without departing from the spirit of the invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of the multiple constituent elements disclosed. For example, if the problem that the invention aims to solve can be solved and the effects of the invention can be obtained even if some constituent elements are deleted from all the constituent elements shown in one embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. Furthermore, constituent elements from different embodiments may be combined as appropriate. This invention is not limited by any particular embodiment other than being limited by the appended claims.

Claims

1. A cylindrical member characterized by comprising: a first sheath having a tip and a base; a second sheath having a tip and a base through which the first sheath is inserted; a first connecting portion inserted into the inside of the tip of the first sheath; and a second connecting portion inserted into the inside of the tip of the second sheath having a larger outer diameter than the first connecting portion; and a cylindrical sleeve.

2. The cylindrical member according to claim 1, wherein the sleeve is provided on the tip side of the first connecting portion, and the outer diameter of the second connecting portion is larger than the outer diameter of the region in the first sheath into which the first connecting portion is inserted.

3. The cylindrical member according to claim 2, characterized in that the inner diameter of the second sheath at the position corresponding to the first connecting portion is larger than the outer diameter of the region in the first sheath into which the first connecting portion is inserted.

4. The cylindrical member according to claim 1, wherein the sleeve further comprises an outer tube that covers the outer surface of the second sheath, wherein the second connecting portion is provided on the tip side of the first connecting portion, and the tip of the outer tube is positioned within a region of the outer surface of the second sheath between the position corresponding to the tip of the first connecting portion and the position corresponding to the base end.

5. The cylindrical member according to claim 1, characterized in that the second sheath has an inner diameter in the region into which the first connecting portion is inserted that is smaller than the inner diameter in the region into which the second connecting portion is inserted, and also smaller than the outer diameter of the second connecting portion.

6. The cylindrical member according to claim 4, characterized in that the first sheath is a flexible resin tube, the second sheath is a rigid metal coil pipe, and the outer tube is a flexible heat-shrinkable tube.

7. The cylindrical member according to claim 1, characterized in that the sleeve has a tapered region on the tip side and a flange on the base end side of the tapered region.

8. The cylindrical member according to claim 7, characterized in that the sleeve has a concave circumferential groove on the base end side of the flange.

9. The cylindrical member according to claim 8, characterized in that the depth of the circumferential groove is at least 0.1 mm.

10. The cylindrical member according to claim 1, characterized in that the outer diameter of the first connecting portion is larger than the inner diameter of the first sheath when the first connecting portion is not connected to the first sheath.

11. The cylindrical member according to claim 1, characterized in that the second connecting portion is inserted into the inside of the tip of the second sheath by press-fitting.

12. A method for manufacturing a cylindrical member according to claim 1, characterized in that the tip of the second sheath is brought into contact with the second connecting portion, one of the second sheath and the second connecting portion is pressed against the other while the second sheath is rotated in a direction that expands its diameter, and the second connecting portion is inserted into the inside of the tip of the second sheath.

13. An endoscope comprising: an insertion section having an elongated tube shape in which a tip, a curved section, and a flexible tube section are connected in order; an operating section to which the base end of the insertion section is connected and which is equipped with various operating members; a wire member positioned to pass through the insertion section and the operating section; and a cylindrical member through which the wire member is inserted, wherein the cylindrical member is formed by a first sheath having a tip and a base end; a second sheath having the tip and base end and through which the first sheath is inserted; a sleeve having a cylindrical shape and a first connecting portion inserted into the tip of the first sheath and a second connecting portion inserted into the tip of the second sheath having a larger outer diameter than the first connecting portion, and through which the wire member is inserted.

14. The endoscope according to claim 13, characterized in that the wire member is a treatment instrument raising wire that performs the raising and tilting operation of the treatment instrument raising platform disposed at the tip.

15. A method for manufacturing a cylindrical member, comprising a coil sheath having a tip and a base, and a sleeve having a cylindrical shape and a connecting portion having an outer diameter larger than the inner diameter of the tip of the coil sheath, characterized in that the tip of the coil sheath is brought into contact with the connecting portion, one of the coil sheath and the connecting portion is pressed against the other while the coil sheath is rotated in a direction that expands its diameter, and the connecting portion is inserted into the inside of the tip of the coil sheath.

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