JP2011067383A - Flexible tube for endoscope, and apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent separation of the respective layers of a skin layer molded in a multi-layer and to improve moldability. <P>SOLUTION: A flexible tube 10 includes: a cylindrical flexible tube raw material 14; and a two-layer skin layer 15 molded by stacking an inner layer 17 covering the whole peripheral surface in the circumferential direction of the flexible tube raw material 14 and an outer layer 18 covering the whole peripheral surface in the circumferential direction of the inner layer 17. When seen in a cross-section orthogonal to the axial direction of the flexible tube raw material 14, an interface 19 where the outer peripheral surface of the inner layer 17 and the inner peripheral surface of the outer layer 18 touch each other is shaped like an imperfect circle, to be concrete, an ellipse having the major axis R<SB>L</SB>and the minor axis R<SB>S</SB>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an endoscope flexible tube having a multilayered outer skin layer, a manufacturing apparatus for manufacturing the endoscope flexible tube, and a manufacturing method.

  A medical endoscope for observing the inside of a body cavity of a patient is known. A flexible tube, which is a main part constituting an insertion portion of an endoscope that is inserted into a body cavity, is composed of a spiral tube formed by winding a metal strip in a spiral shape, and a mesh tube that covers this outer periphery. While the flexible tube material is conveyed in the longitudinal direction (axial direction), a thermoplastic resin such as urethane resin is discharged onto the outer peripheral surface to form an outer skin layer.

  Since the insertion portion is inserted into a complicated and winding duct such as the large intestine, a high insertion property (ease of insertion) is required for the flexible tube. For this reason, as shown below, a flexible tube in which various devices for improving the insertability have been proposed.

  Patent Documents 1 and 2 describe a flexible tube in which an outer skin layer is molded (mixed molding) with a mixed resin obtained by mixing two types of resins having different hardnesses. According to such mixed molding, by changing the mixing ratio of the two types of resin in the axial direction of the flexible tube, for example, the distal end side of the insertion portion is highly flexible (soft) in order to increase the bendability, and can be operated. The flexibility can be changed in the axial direction of the flexible tube, such that the flexibility is lowered (hardened) in order to enhance the transmission of the operating force on the rear end side connected to the portion.

  Patent Document 3 describes a flexible tube having an outer skin layer in which two layers of an inner layer and an outer layer are laminated by two-layer molding. In the two-layer molding, the flexibility can be changed similarly to the mixed molding by changing the ratio of the thickness of the inner layer and the outer layer in the axial direction of the flexible tube to the thickness of the entire outer skin layer.

  Also, unlike mixed molding, two-layer molding uses a resin with higher chemical resistance than the inner layer resin for the outer layer, or makes the elastic force of each resin of the outer layer and inner layer different from each other. However, since it is possible to combine two types of resins with different physical properties, it is easy to make a flexible tube that exhibits performance that meets various purposes, and its application range is wider than that of mixed molding. Furthermore, the two-layer molding is easier to mold than the mixed molding in which it is difficult to adjust the mixing ratio of the two types of resins.

  Patent Document 4 describes a flexible tube to which two-layer molding is applied. The flexible tube of Patent Document 4 is provided with a denatured portion having physical properties different from those of other portions in a part around the axis of the outer skin layer (circumferential direction) in order to bend easily in a specific direction. The denatured part cuts out a part of the outer layer to form a cutout part, and the cutout part is embedded with a thick part formed in a part of the inner layer in the circumferential direction or a material different from the outer layer and the inner layer. Consists of.

  As described above, the two-layer molding has an advantage that a flexible tube suitable for various purposes can be easily formed and the moldability is good as compared with the mixed molding.

Japanese Patent Publication No.7-110270 Japanese Patent No. 2641789 Japanese Patent Publication No. 5-50287 JP 2002-85335 A

  However, if the shape of the boundary between the inner layer and the outer layer is a perfect circle in a cross section orthogonal to the axial direction as in the flexible tube of Patent Document 3, the twisting force is applied when twisting is applied around the axis of the flexible tube. Acts on the entire circumference of the boundary in parallel with the tangential direction of the boundary, so that a large shear force is applied to the boundary. For this reason, there existed a problem that an outer layer and an inner layer were easy to peel. In Patent Document 3, no consideration is given to such a problem, and there is no description or suggestion of a measure for preventing peeling.

  If a modified portion is provided by cutting out a part of the outer layer as in Patent Document 4, the cross-sectional shape of the boundary between the outer layer and the inner layer is not a perfect circle, so the shearing force applied to the boundary by torsion can be reduced. . However, if a modified part is provided in a part of the outer skin layer as in Patent Document 4, the boundary between the outer layer and the modified part is exposed to the outside, and this tends to cause a decrease in adhesive force due to degradation of the exposed boundary part. There is a problem that peeling easily occurs.

  In addition, the configuration in which the modified portion is provided in a part of the outer circumferential direction of the outer skin layer as in Patent Document 4 is poor in moldability because the layer structure is complicated compared to the case of forming two layers without providing the modified portion. There is also a problem. Formability is a particular problem because it is an important factor that affects production costs and ensuring stable production quality.

  The present invention has been made in consideration of the above circumstances, and prevents the peeling of each layer of the outer layer formed by multilayer molding with resin layers having different physical properties, and a flexible tube for an endoscope having good moldability and its It aims at providing a manufacturing apparatus and a manufacturing method at low cost.

  To achieve the above object, a flexible tubular flexible tube material, an inner layer covering the entire circumference of the flexible tube material around the axis, and an entire circumference of the inner layer around the axis are covered. The outer layer is an outer layer formed by laminating at least two layers of the outer layer, and each of the inner layer and the outer layer is made of resin having different physical properties, and in the cross section orthogonal to the axial direction of the flexible tube material, the outer periphery of the inner layer and the inner periphery of the outer layer It is characterized by comprising the outer skin layer having a non-circular shape in the shape of the boundary that touches.

  Moreover, it is preferable that the shape of the boundary is any one of an ellipse, a polygon, and a gear shape in which irregularities are formed in the circumferential direction. Furthermore, it is preferable that the shape of the boundary is an ellipse, and the difference between the major axis and the minor axis is 200 μm or more and 1000 μm or less.

  It is preferable that the ratio of the thickness of the inner layer and the outer layer to the thickness of the entire outer skin layer is changed in the axial direction of the flexible tube material. Moreover, it is preferable that the shape of the said boundary is similar over the axial direction of the said flexible tube raw material.

  In the inner layer and the outer layer, a soft resin is used for one layer and a hard resin is used for the other layer, and the ratio of the thickness of the layer in which the soft resin is used on the distal end side in the axial direction of the flexible tube material is It is preferable that the ratio of the thickness of the layer in which the hard resin is used on the base end side is high.

  The endoscope flexible tube manufacturing apparatus according to the present invention is a passage through which a flexible tubular flexible tube material is conveyed along the axial direction, and the entire circumference of the flexible tube material around the axis thereof. A molding passage for extruding at least a two-layered outer skin layer composed of an inner layer and an outer layer, and a resin passage for supplying molten resin as a material for the outer skin layer to the molding passage. In the endoscope flexible tube manufacturing apparatus, the first resin serving as the material of the inner layer is disposed outside the passage and has a circular resin passage whose cross-sectional shape perpendicular to the axial direction is concentric with the molding passage. A first gate having a cross-sectional shape that is concentric with the molding passage, and a second resin that is different in physical properties from the first resin and that serves as a material for the outer layer. A second gate for feeding into the resin passage; A circular second gate disposed outside the first gate and having a cross-sectional shape concentric with the first gate, and first and second gates sent out at the downstream ends of the first gate and the second gate. 2 is formed in the separation portion, the separation portion for separating the first and second gates on the upstream side of the merge portion, and the separation portion. An edge that is tapered toward the downstream side to join the first resin and the second resin, and has an edge whose cross-sectional shape perpendicular to the axial direction is a non-circular shape, By passing the edge and supplying the melted first and second resins to the molding passage through the resin passage, the shape of the boundary between the inner layer and the outer layer is not shown in the cross section orthogonal to the axial direction. Round outer skin Characterized by forming a.

  In addition, it is preferable that the cross-sectional shape of the edge is any one of an ellipse, a polygon, and a gear shape in which irregularities are formed in the circumferential direction.

In the endoscope flexible tube manufacturing method of the present invention, a flexible tubular flexible tube material is disposed outside the molding passage while conveying the molding passage along the axial direction. By supplying molten resin to the molding passage through a circular resin passage whose cross-sectional shape orthogonal to the direction is concentric with the molding passage, the entire circumference surface around the axis of the flexible tube material is supplied. Then, in a method of manufacturing an endoscope flexible tube in which an outer skin layer composed of at least an inner layer and an outer layer is extruded, the inner layer is passed through a circular first gate whose cross-sectional shape is concentric with the molding passage. A first resin delivery step of delivering a first resin as a material to the resin passage, and a second gate disposed outside the first gate and having a cross-sectional shape concentric with the first gate, through the first gate. 1 resin Have different physical properties, and a second resin delivery step for delivering the second resin, which is the material of the outer layer, to the resin passage at the same timing as the first resin delivery step, and downstream ends of the first gate and the second gate, Connecting, and joining the first and second resins sent out by the respective gates in the joining portion having a circular cross-sectional shape, and in the joining step, the first and second upstream of the joining portion. Formed in a separation portion for separating the gate of the first and second edges, and tapered toward the downstream side to join the first resin and the second resin, and a cross-sectional shape orthogonal to the axial direction is a non-circular shape An edge passing step for passing the edge, and supplying the molding passage through the resin passage in a state where the first and second resins passing through the edge are overlapped with each other. And a supply step that,
In the cross section orthogonal to the axial direction, an outer skin layer having a non-circular shape at the boundary between the inner layer and the outer layer is formed.

  In addition, it is preferable that the cross-sectional shape of the edge is any one of an ellipse, a polygon, and a gear shape in which irregularities are formed in the circumferential direction.

  According to the present invention, in the cross section orthogonal to the axial direction of the flexible tube material, the boundary shape where the outer periphery of the inner layer and the inner periphery of the outer layer are in contact with each other is formed in a non-circular shape. Can be prevented. In addition, the inner layer covers the entire circumferential surface around the axis of the flexible tube material, and the outer layer covers the entire circumferential surface around the axis of the inner layer, so that the layer structure is not complicated and good moldability is achieved. Can be secured.

It is an external view which shows the structure of an electronic endoscope. It is a fragmentary sectional view showing a schematic structure of a flexible tube. It is sectional drawing of the flexible tube cut | disconnected in the direction orthogonal to an axial direction. It is explanatory drawing which shows a state when twist arises in the conventional flexible tube (A) and the flexible tube of this invention. It is a block diagram which shows roughly the structure of the manufacturing apparatus of the flexible tube for endoscopes. It is principal part sectional drawing which shows the structure of a head part. It is principal part sectional drawing of the head part cut | disconnected by the AA line of FIG. It is sectional drawing which shows the example which formed the boundary surface of the outer skin layer in the polygon. It is sectional drawing which shows the example which formed the boundary surface of the outer skin layer in the gear shape of the triangular tooth. It is sectional drawing which shows the example which formed the boundary surface of the outer skin layer in the shape of a square-tooth gear. It is a fragmentary sectional view showing a schematic structure of a flexible tube for universal cords.

  In FIG. 1 showing an electronic endoscope incorporating a flexible tube according to the present invention, an electronic endoscope 2 widely used for medical purposes includes an insertion portion 3 to be inserted into a body cavity, and a base of the insertion portion 3. A main body operation unit 5 connected to the end portion, a connector unit 6 connected to the processor device and the light source device, a main body operation unit 5 and a universal cord 7 connecting the connector unit 6 are provided.

  The insertion section 3 is provided with a flexible tube portion 3a provided continuously with the main body operation portion 5, an angle portion 3b provided continuously with the flexible tube portion 3a, and an imaging device for photographing inside the body cavity. (Not shown) is comprised from the front-end | tip part 3c with which it was incorporated. The flexible tube portion 3a, which is the length of most of the insertion portion 3, has flexibility over almost the entire length thereof, and in particular, the portion inserted into the body cavity or the like has a more flexible structure. .

  As shown in FIG. 2, the flexible tube 10 (endoscopic flexible tube) constituting the flexible tube portion 3a is a spiral formed by spirally winding a metal strip 11a on the innermost side. The tube 11 is covered with a tubular mesh body 12 formed by braiding a metal wire, and a flexible tube material 14 is fitted with caps 13 at both ends, and an outer skin layer 15 made of resin is coated on the outer peripheral surface thereof. It has been configured. The outer surface of the outer skin layer 15 is coated with a coating film 16 containing, for example, fluorine having chemical resistance. The outer skin layer 15 and the coating film 16 are drawn thicker than the diameter of the flexible tube material 14 in order to clearly show the layer structure.

  The outer skin layer 15 covers the outer peripheral surface of the flexible tube material 14. The outer skin layer 15 has a two-layer structure in which an inner layer 17 that covers the outer peripheral surface of the flexible tube material 14 and an outer layer 18 that covers the outer peripheral surface of the inner layer 17 are laminated. For the inner layer 17 and the outer layer 18, two types of soft resins and hard resins having different hardnesses are used. A soft resin is used as the material of the inner layer 17, and a hard resin is used as the material of the outer layer 18.

  The outer skin layer 15 is formed with a substantially uniform thickness in the longitudinal direction (axial direction) of the flexible tube material 14. The thicknesses of the inner layer 17 and the outer layer 18 are formed such that the ratio of the thicknesses of the layers 17 and 18 to the entire thickness of the outer skin layer 15 changes in the axial direction of the flexible tube material 14. Specifically, on the one end 14 a side (base end side) of the flexible tube material 14 attached to the main body operation unit 5, the outer layer 18 is thicker than the entire outer layer 15. The thickness of the outer layer 18 gradually decreases from the one end 14a to the other end 14b side (tip side) attached to the angle portion 3b. On the other end 14b side, the thickness of the inner layer 17 is the thickness of the outer layer 18. Is bigger than. Therefore, the flexibility of the flexible tube 10 is changed in the axial direction of the flexible tube 10 so that the flexibility on the one end 14a side is low (hard) and the flexibility on the other end 14b side is high (soft). Yes.

As shown in FIG. 3, in the outer skin layer 15, the inner layer 17 covers the entire circumferential surface around the axis of the flexible tube material 14 (circumferential direction), and the outer layer 18 covers the entire circumferential surface of the inner layer 17. ing. In addition, in the cross section orthogonal to the axial direction of the flexible tube material 14, the outer circumference of the outer layer 18 and the inner circumference of the inner layer 17 are perfect circles. On the other hand, in the same cross section, the boundary 19 where the outer peripheral surface of the inner layer 17 and the inner peripheral surface of the outer layer 18 are in contact with each other has a non-circular shape. Specifically, the major axis _RL and the minor axis _RS are It has an oval shape.

  Thus, if the cross-sectional shape of the boundary 19 is elliptical, the peel strength at the boundary surface between the inner layer 17 and the outer layer 18 when twisting is applied around the axis of the flexible tube 10 can be improved. As in the conventional flexible tube 111 shown in FIG. 4A, when the boundary 119 is a perfect circle, when the twist is applied in the direction around the axis, the torsional force P is spread over the entire circumference of the boundary 119. Therefore, a large shearing force is applied to the boundary 119. For this reason, peeling easily occurs at the boundary 119 between the inner layer 117 and the outer layer 118.

  On the other hand, according to the flexible tube 10 of the present invention shown in FIG. 4B, since the boundary 19 is elliptical, when the flexible tube 10 is twisted about its axis, the torsional force P Some will not work parallel to the tangential direction of the boundary 19. Therefore, compared with the case where the cross-sectional shape is circular, the shearing force applied to the boundary 19 having an elliptical cross-sectional shape is small, and separation at the boundary 19 between the inner layer 17 and the outer layer 18 is difficult.

Further, when the boundary 19 is elliptical, the outer periphery becomes longer compared to a perfect circle having the short axis R _S as a diameter, so the area of the boundary surface where the inner layer 17 and the outer layer 18 are in contact increases. By increasing the contact area, peeling of the boundary 19 between the inner layer 17 and the outer layer 18 can be further prevented.

Further, when the boundary 19 is elliptical, the flexibility of the flexible tube 10 can be given directionality. That is, the ratio of the thickness of the inner layer 17 using the soft resin to the entire thickness of the outer skin layer 15 is larger in the major axis _RL direction than in the minor axis _RS direction. On the contrary, in the minor axis _RS direction, the ratio of the thickness of the outer layer 18 using the hard resin increases. Therefore, for example, when the long axis _RL direction is the left-right direction and the short axis _RS direction is the up-down direction, the flexible tube 10 is more easily bent in the left-right direction than in the up-down direction.

In this way, when the flexibility of the flexible tube 10 is given directionality, there are many cases where it is advantageous for insertion into a conduit having a small radius of curvature, which contributes to improvement of the insertability. However, if the difference in ease of bending depending on the direction is too large, the operability of the flexible tube 10 may be lowered. For this reason, when the flexible tube 10 formed with the entire outer skin layer 15 having a thickness of 200 μm or more and 1500 μm or less is taken as an example, the dimension of the ellipse is, for example, the difference between the long axis R _L and the short axis R _S Is preferably formed to 200 μm or more and 1000 μm or less. If it is this range, insertability can be improved, without reducing the operativity of the flexible tube 10. FIG.

Further, as described above, the outer skin layer 15 is formed so that the thicknesses of the inner layer 17 and the outer layer 18 change in the axial direction of the flexible tube material 14. For this reason, in the axial direction of the flexible tube material 14, the cross-sectional shape of the boundary 19 changes in the dimensions of the major axis _RL and the minor axis _RS as the thickness of the inner layer 17 and the outer layer 18 changes. The tube material 14 has a similar shape over the entire length in the axial direction.

  As the resin used for the inner layer 17 and the outer layer 18, for example, two types of polyurethane elastomers having different hardnesses are used. The resin of the inner layer 17 and the outer layer 18 is not limited to the above, and various resins can be used according to the intended performance. For example, when it is desired to change the elastic force between the inner layer 17 and the outer layer 18, it is preferable to use a polyester elastomer or a polystyrene elastomer. In addition, when it is desired to change the chemical resistance between the inner layer 17 and the outer layer 18, it is preferable to select from a group of polyolefin elastomers, polyamide elastomers, and fluorine elastomers.

  In addition, the two types of resins used for the inner layer 17 and the outer layer 18 may change various physical properties such as insulation and surface slipperiness in addition to hardness, elasticity, and chemical resistance. Further, the physical properties may be changed using resins having different compositions, or the physical properties may be changed using resins of the same kind but having different densities.

  Hereinafter, a method for manufacturing the flexible tube 10 having the above configuration will be described. In FIG. 5 which shows the structure of the continuous molding machine 20 which shape | molds the outer skin layer 15, the continuous molding machine 20 is the well-known extrusion parts 21 and 22 consisting of a hopper, screw 21a, 22a, etc., and the outer peripheral surface of the flexible tube raw material 14. The head part 23 for covering and forming the outer skin layer 15, the cooling part 24, the transport part 25 for transporting the connected flexible tube material 31 to the head part 23, and the control part 26 for controlling them.

  The transport unit 25 includes a supply drum 28 and a take-up drum 29, and a connected flexible tube material 31 in which a plurality of flexible tube materials 14 are connected by a joint member 30 is wound around the supply drum 28. After being wound around the supply drum 28, it is sequentially drawn out and wound around the winding drum 29 through the head portion 23 where the outer skin layer 15 is formed and the cooling portion 24 where the outer skin layer 15 is cooled. The rotation speed of the supply drum 28 and the take-up drum 29 is controlled by the control unit 26, and the conveyance speed for conveying the connected flexible tube material 31 is switched.

  As shown in FIGS. 5 and 6, the head portion 23 includes a nipple 32, a die 33, and a support 34 that fixedly supports these. The support 34 is formed with gates 35 and 36 for feeding the soft resin and the hard resin in a molten state extruded from the extrusion portions 21 and 22 to the resin passage 38, respectively.

  A molding passage 37 is formed in the nipple 32 and the die 33 so as to pass through the respective approximate centers. The forming passage 37 is a passage through which the connected flexible tube material 31 conveyed in the axial direction by the conveying unit 25 passes, and the cross-sectional shape orthogonal to the axial direction is circular (see FIG. 7). The molding passage 37 is connected to a discharge port corresponding to the downstream end of the resin passage 38, and molten resin is supplied from the resin passage 38 to the molding passage 37.

  The resin passage 38 is formed by a space sandwiched between the nipple 32 and the die 33. At the left end of the nipple 32 in the figure, a conical convex portion 32 b that forms a resin passage 38 together with the conical concave portion 33 a at the right end of the die 33 is formed. Further, a conical recess 32 a (see FIG. 5) is formed continuously to the right end of the forming passage 37 in the drawing and guides the insertion of the connecting flexible tube material 31.

  The die 33 is formed with an outlet hole 37 a of a molding passage 37. The connected flexible tube material 31 coated with the outer skin layer 15 passes through the outlet hole 37a and is conveyed to the cooling unit 24. The cooling unit 24 stores a coolant such as water, and cools and hardens the outer skin layer 15 by passing through the coolant. However, the present invention is not limited to this, and cooling liquid or air may be sprayed on the outer skin layer 15 to cool it.

  The resin passage 38 is disposed outside the molding passage 37, and the cross-sectional shape orthogonal to the axial direction of the molding passage 37 is a circle concentric with the molding passage 37. The discharge port of the resin passage 38 is connected to the entire circumference of the molding passage 37 in the circumferential direction. For this reason, molten resin is discharged toward the entire circumference of the connected flexible tube material 31 that passes through the discharge port of the resin passage 38.

  The extrusion parts 21 and 22 have discharge ports 21b and 22b coupled to the gates 35 and 36 of the head part 23, respectively, and a soft resin and a hard resin in a molten state, which are materials of the inner layer 17 and the outer layer 18, are made to pass through the resin passage. The material is extruded and supplied to the molding passage 37 of the head portion 23 via 38. By controlling the number of rotations of the screws 21a and 22a by the control unit 26, the amounts of the melted soft resin and hard resin discharged from the extruding units 21 and 22 are adjusted.

  The temperature of the soft resin and the hard resin is increased by heating and controlling the extruding parts 21 and 22 and the head part 23. In addition to this, the higher the rotational speeds of the screws 21a and 22a, the higher the soft resin and the hard resin. Each temperature of the resin becomes higher and the fluidity of each increases. The molding thicknesses of the inner layer 17 and the outer layer 18 are adjusted by changing the discharge amount of the soft resin and the hard resin in the molten state while keeping the conveying speed of the connected flexible tube material 31 constant.

  The gates 35 and 36 are centered on the molding passage 37 and are both disposed outside the molding passage 37, and the gate 36 is disposed outside the gate 35. The gates 35 and 36 are substantially cylindrical passages having a circular cross-sectional shape orthogonal to the axial direction of the forming passage 37. In the gates 35 and 36, the downstream end in the feeding direction of the soft resin and the hard resin is connected to the upstream end of the resin passage 38. This connecting portion serves as a joining portion where the soft resin and the hard resin join together. Between the gates 35 and 36, the separation part 39 which isolate | separates both is provided.

  The separating portion 39 has an edge 39a disposed at the joining portion, and separates the gates 35 and 36 on the upstream side of the joining portion. The soft resin and hard resin delivered from the gates 35 and 36 merge through the edge 39a. The edge 39a has a cross-sectional shape parallel to the axial direction that tapers toward the tip in order to join two kinds of resins.

  In the joining portion, the molten soft resin supplied from the gate 35 is joined inside, and the molten hard resin supplied from the gate 36 is joined outside. The merged soft resin and hard resin flow in the resin passage 38 in an overlapped state. The soft resin and the hard resin are discharged toward the entire circumference of the connected flexible tube material 31 from the discharge ports connected to the entire circumference in the circumferential direction of the molding passage 37 while maintaining the overlapping state. Thereby, the outer skin layer 15 which consists of the inner layer 17 and the outer layer 18 is formed.

  As shown in FIG. 7, the edge 39a portion arranged in the merge portion has an elliptical cross-sectional shape in the cross section orthogonal to the axial direction. This ellipse is formed in a similar shape to the ellipse at the boundary 19 between the inner layer 17 and the outer layer 18. The shape of the delivery port at the downstream end of each of the gates 35 and 36 is defined by the shape of the edge 39a. That is, in the major axis direction of the edge 39a, the delivery port of the soft resin gate 35 is wide and the delivery port of the hard resin gate 36 is narrow. On the contrary, in the short axis direction of the edge 39a, the delivery port of the gate 35 is narrow and the delivery port of the gate 36 is wide.

  The amount of delivery sent from each gate 35, 36 to the junction is determined according to the size of each delivery port defined by the shape of the edge 39a. In the joining portion, soft resin and hard resin in an amount corresponding to the delivery port are sent out to the resin passage 38 and joined together. In the resin passage 38, the resin is thick at the portion where the delivery port is wide, and the soft resin and the hard resin are overlapped with the resin being thin at the narrow portion.

  Since the soft resin and the hard resin are supplied to the molding passage 37 through the resin passage 38 in a state of being overlapped and laminated on the connecting flexible tube material 31, the boundary 19 between the inner layer 17 and the outer layer 18 is formed as shown in FIG. It becomes an elliptical shape similar to the edge 39a.

  A process when the outer skin layer 15 is formed on the connected flexible tube material 31 by the continuous molding machine 20 having the above configuration will be described. When the continuous molding machine 20 performs the molding process, melted soft resin and hard resin are extruded from the extruding units 21 and 22 to the head unit 23, and the conveying unit 25 operates to connect the connected flexible tube material 31. It is conveyed to the head unit 23.

  At this time, the extruding portions 21 and 22 are in a state of always extruding soft resin and hard resin and supplying them to the head portion 23, and the soft resin and hard resin extruded from the extruding portions 21 and 22 to the gates 35 and 36 are The cross-sectional shape passes through the elliptical edge 39a, merges, and is supplied to the molding passage 37 through the resin passage 38 in an overlapping state. As a result, a two-layered outer skin layer 15 is formed in which the boundary 19 between the inner layer 17 using the soft resin and the outer layer 18 using the hard resin is elliptical.

  The connected flexible tube material 31 is formed by connecting a plurality of flexible tube materials 14, and the outer skin layer 15 is continuously formed with respect to the plurality of flexible tube materials 14 while being conveyed through the forming passage 37. Is done. When the outer skin layer 15 is formed from one end 14 a side (base end side) to the other end 14 b side (tip end side) of one flexible tube material 14, the outer layer 18 is formed at one end 14 a of the flexible tube material 14 rather than the inner layer 17. And the ratio of the inner layer 17 gradually increases from the one end 14 a side to the other end 14 b side of the flexible tube material 14, and the inner layer 17 is larger than the outer layer 18 on the other end 14 b side of the flexible tube material 14. The control unit 26 controls the amount of resin discharged by the extruding units 21 and 22 so that the thickness of the resin increases.

  On the other hand, when the outer skin layer 15 is formed on the outer peripheral surface of the joint member 30, the inner layer 17 is thicker than the outer layer 18 at a position adjacent to the other end 14 b of the flexible tube material 14. The ratio of the outer layer 18 gradually increases from the other end 14 b side toward the one end 14 a side of the next flexible tube material 14, and at a position adjacent to the one end 14 a of the next flexible tube material 14 than the inner layer 17. The control unit 26 controls the discharge amount of the extruding units 21 and 22 so that the thickness of the outer layer 18 is increased. That is, by using the joint member 30, the discharge amount is switched according to the thicknesses of the outer layer 18 and the inner layer 17 when transitioning from one flexible tube material 14 to the next flexible tube material 14.

  When the outer skin layer 15 is formed from the one end 14a side to the other end 14b side of the next flexible tube material 14, the thickness of the inner layer 17 gradually increases from the one end 14a side to the other end 14b side. Thus, the extrusion parts 21 and 22 are controlled. Thereafter, similarly, the discharge amount of the extruding portions 21 and 22 is switched to form the outer skin layer 15 on the connected flexible tube material 31.

  The connected flexible tube material 31 in which the outer skin layer 15 has been molded to the end is removed from the continuous molding machine 20, and then the joint member 30 is removed from the flexible tube material 14 and separated into each flexible tube material 14. The Next, the separated flexible tube material 14 is coated with a coating film 16 on the outer skin layer 15 to complete the flexible tube 10. The completed flexible tube 10 is conveyed to the assembly process of the electronic endoscope 2.

  As described above, the continuous molding machine 20 joins two types of molten resin fed from the plurality of gates 35 and 36, and sends them to the molding passage through the resin passage 38 in a state where they are overlapped to be molded. The outer skin layer 15 is formed by the same process as the conventional two-layer forming process. For this reason, compared with the case where a modified part is provided in a part in the circumferential direction of the outer skin layer, there is no complicated process and the moldability is good. Further, since the continuous molding machine 20 is different from the conventional continuous molding only in the shape of the edge 39a, it is easy to modify the conventional continuous molding machine.

  Further, the outer skin layer 15 of the flexible tube 10 has an elliptical boundary 19 between the inner layer 17 and the outer layer 18, so that the boundary is true even when the insertion portion 3 of the electronic endoscope 2 is twisted. Compared to the case of a circle, the inner layer 17 and the outer layer 18 are less likely to peel off.

  In the above example, the cross-sectional shape of the boundary 19 of the outer skin layer 15 is an ellipse in the cross section orthogonal to the axial direction. However, it may not be an ellipse as long as it is a non-circular shape. If the cross-sectional shape of the boundary 19 of the outer skin layer 15 is a non-circular shape, the shear force acting on the boundary 19 when the torsion around the axis is applied to the flexible tube 10 can be reduced. The same effect can be obtained.

  For example, the cross-sectional shape may be a polygon (an octagon in FIG. 8) like a boundary 41 shown in FIG. Moreover, the cross-sectional shape may be a gear shape in which unevenness is formed in the circumferential direction like a boundary 42 shown in FIG. The shape of the teeth constituting the unevenness does not have to be a triangle like the tooth 42a shown in FIG. 9, and may be a rectangle (the groove is also a square) like the tooth 43a of the boundary 43 shown in FIG. Moreover, the tooth | gear may be formed in the curve.

  Similarly to the case where the boundaries are elliptical, if the edges 39a of the continuous molding machine 20 are matched to the various cross-sectional shapes of the respective boundaries 41 to 43 and similar to them, the outer shape having these boundaries 41 to 43 will be obtained. A skin layer can be formed.

  In the above embodiment, a soft resin is used for the inner layer and a hard resin is used for the outer layer. Conversely, a hard resin may be used for the inner layer and a soft resin may be used for the outer layer. Although the two-layer molding has been described as an example, the outer skin layer may be composed of two or more multilayers such that three outer skin layers are formed by three layers of an inner layer, a middle layer, and an outer layer.

  In the above-described embodiment, an electronic endoscope that observes an image obtained by imaging the state of the subject using the imaging apparatus is described as an example. However, the present invention is not limited to this, and an optical image is not limited thereto. The present invention can also be applied to an endoscope that employs a guide and observes the state of a subject.

  Moreover, in the said embodiment, although the flexible tube 10 is applied to the insertion part 3 of the electronic endoscope 2, you may apply to the flexible tube for endoscopes, such as the universal cord 7. FIG.

  Moreover, although the said embodiment demonstrated the example which changes the softness | flexibility of the outer skin layer 15 by changing the ratio of the thickness of an inner layer and an outer layer in the axial direction of the flexible tube 10, The outer skin layer also needs to change its flexibility in the axial direction. Below, the example of how to change the softness | flexibility suitable for the outer skin layer of the universal cord 7 is demonstrated.

  The universal cord 7 stores a light guide and a wiring cable, and one end side is connected to the main body operation unit 5 of the electronic endoscope 2 and the other end side is connected to the connector unit 6. For this reason, if both ends of the universal cord 7, that is, the outer skin layer in the vicinity of the main body operation unit 5 and the connector unit 6 are soft, the contents, particularly the light guide, will be buckled or twisted. It is not preferable from the viewpoint. On the other hand, when the outer skin layer is hardened over the entire length of the universal cord 7 in the axial direction, the universal cord 7 becomes difficult to handle, and the operability of the electronic endoscope 2 is lowered.

  Therefore, as in the flexible tube 50 for the universal cord 7 shown in FIG. 11, the outer skin layer 52 is formed so that the flexibility at both ends is low (hard) and the flexibility at the center is high (soft). Is preferred.

  The flexible tube 50 has a configuration in which an outer skin layer 52 formed by forming two layers of a soft resin layer 53 and a hard resin layer 54 on the outer peripheral surface of a flexible tube material 51 is covered. The configuration of the flexible tube material 51 is similar to the flexible tube material 14 described in the above embodiment, in which the spiral tube 11 is covered with the cylindrical mesh body 12 and the base 13 is fitted to both ends. There will be no description below.

  The outer skin layer 52 is formed with a uniform thickness over the entire length in the axial direction. The outer skin layer 52 has the hard resin layer 54 having a thickness larger than the soft resin layer 53 on both ends 51a and 51b side of the flexible tube material 51 attached to the main body operation section 5 and the connector section 6. The thickness of the soft resin layer 53 gradually decreases from 51b toward the central portion of the flexible tube material 51. In the central portion of the flexible tube material 51, the thickness of the soft resin layer 53 is greater than the thickness of the hard resin layer 54. Is also getting bigger.

  Thereby, the flexible tube 50 has low flexibility (hard) on both ends 51a and 51b side, and high flexibility (soft) at the center. Conventionally, in order to increase the strength around the main body operation unit 5 and the connector unit 6, a rubber cover is attached to the end of the universal cord 7 on the main body operation unit 5 and the connector unit 6 side. Since the both ends 51a and 51b side of the flexible part 50 is hardened as described above, a cover is unnecessary, and the cost can be reduced.

  When the outer skin layer 52 is coated and formed on the flexible tube material 51, the continuous forming machine 20 of the above embodiment is used, and the forming process is performed as a connected flexible tube material in which the flexible tube material 51 is connected by the joint member 30. It can be carried out. The method for forming the outer skin layer 52 on the flexible tube material 51 is the same as the method for forming the outer skin layer 15 on the flexible tube material 14. The thickness of each of the layers 53 and 54 of the outer skin layer 52 is changed by controlling the discharge amount of the resin by the extrusion units 21 and 22 by the control unit 26.

2 Electronic endoscope (endoscope)
3 Insertion portion 10, 50, 111 Flexible tube 14, 51 Flexible tube material 15, 52, 115 Outer layer 17, 53, 117 Inner layer 18, 54, 118 Outer layer 19, 41, 42, 43, 119 Boundary 20 Continuous molding Machine (manufacturing equipment)
23 Head (molding die)
35, 36 Gate 37 Molding passage 38 Resin passage 39 Separation part 39a Edge

Claims (10)

A tubular flexible tube material having flexibility;
At least two layers of an inner layer covering the entire peripheral surface around the axis of the flexible tube material and an outer layer covering the entire peripheral surface around the axis of the inner layer are laminated, and the inner layer and the outer layer are formed of resins having different physical properties. The outer layer is a non-circular outer layer having a non-circular shape at the boundary between the outer periphery of the inner layer and the inner periphery of the outer layer in a cross section perpendicular to the axial direction of the flexible tube material. Flexible tube for endoscope.   2. The flexible tube for an endoscope according to claim 1, wherein the shape of the boundary is any one of an ellipse, a polygon, and a gear shape in which irregularities are formed in a circumferential direction.   The flexible tube for an endoscope according to claim 2, wherein a shape of the boundary is an ellipse, and a difference between a major axis and a minor axis is 200 µm or more and 1000 µm or less.   The endoscope according to any one of claims 1 to 3, wherein a ratio of the thickness of the inner layer and the outer layer to the thickness of the entire outer skin layer changes in the axial direction of the flexible tube material. Flexible tube.   The flexible tube for an endoscope according to claim 4, wherein the shape of the boundary is similar to the shape of the flexible tube material in the axial direction.   In the inner layer and the outer layer, a soft resin is used for one layer and a hard resin is used for the other layer, and the ratio of the thickness of the layer in which the soft resin is used on the distal end side in the axial direction of the flexible tube material is The flexible tube for an endoscope according to claim 4 or 5, wherein the ratio of the thickness of the layer in which the hard resin is used on the base end side is high. It is a passage through which a flexible tubular flexible tube material is conveyed along the axial direction, and has a two-layer structure consisting of at least an inner layer and an outer layer with respect to the entire peripheral surface around the axis of the flexible tube material. A molding passage for extruding the outer skin layer, and a resin passage for supplying molten resin, which is a material of the outer skin layer, to the molding passage, and is disposed outside the molding passage, and is a cross section orthogonal to the axial direction. In an endoscope flexible tube manufacturing apparatus having a circular resin passage whose shape is concentric with the molding passage,
A first gate that feeds the first resin, which is a material of the inner layer, into the resin passage, and a circular first gate in which the cross-sectional shape is concentric with the molding passage;
The second resin has a physical property different from that of the first resin, and is a second gate for feeding the second resin, which is a material of the outer layer, to the resin passage. The second gate is disposed outside the first gate, and the cross-sectional shape is the same as that of the first gate. A concentric circular second gate,
A joining portion for joining the first and second resins sent out by the gates at the downstream ends of the first gate and the second gate, and a joining portion having a circular cross-sectional shape;
A separation unit that separates the first and second gates upstream of the merge unit;
An edge formed in the separation portion and tapered toward the downstream side in order to join the first resin and the second resin, and an edge whose cross-sectional shape perpendicular to the axial direction is a non-circular shape; With
The shape of the boundary between the inner layer and the outer layer in the cross section perpendicular to the axial direction is obtained by passing the edge and supplying the melted first and second resins to the molding passage through the resin passage. An apparatus for manufacturing an endoscope flexible tube, wherein a non-circular outer skin layer is formed.   8. The endoscope flexible tube manufacturing apparatus according to claim 7, wherein the cross-sectional shape of the edge is any one of an elliptical shape, a polygonal shape, and a gear shape in which irregularities are formed in a circumferential direction. A tubular flexible tube material having flexibility is disposed outside the molding passage while conveying the molding passage along the axial direction, and a cross-sectional shape perpendicular to the axial direction is concentric with the molding passage. By supplying molten resin to the molding passage through a circular resin passage, an outer skin layer having a two-layer structure composed of at least an inner layer and an outer layer with respect to the entire peripheral surface around the axis of the flexible tube material. In the method of manufacturing an endoscope flexible tube for extruding
A first resin delivery step of delivering a first resin as a material of the inner layer to the resin passage through a circular first gate having a cross-sectional shape concentric with the molding passage;
A second resin that is disposed outside the first gate and has a cross-sectional shape that is concentric with the first gate and having a physical property different from that of the first resin and serving as a material for the outer layer. A second resin delivery step for delivering to the resin passage at the same timing as the first resin delivery step;
A merging step for connecting the first and second resins sent out by the gates at a merging portion connected to the downstream ends of the first gate and the second gate and having a circular cross-sectional shape;
In the merging step, a separation portion that separates the first and second gates is formed on the upstream side of the merging portion, and is tapered toward the downstream side in order to merge the first resin and the second resin. An edge passing step for passing an edge having a non-circular cross-sectional shape perpendicular to the axial direction,
A supply step of passing through the edge and supplying the molten first and second resins to the molding passage through the resin passage in a state of being overlapped,
A method for manufacturing an endoscope flexible tube, comprising forming a skin layer having a non-circular shape at a boundary between an inner layer and an outer layer in a cross section perpendicular to the axial direction.   The method for manufacturing a flexible tube for an endoscope according to claim 9, wherein the cross-sectional shape of the edge is any one of an ellipse, a polygon, and a gear shape in which irregularities are formed in a circumferential direction.

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