JP7721497B2 - Operating rope - Google Patents

Description

The present invention relates to a control rope suitable for medical equipment.

In endoscopic treatment tools, a control rope is used to transmit hand-operated operations to the treatment section at the tip. Japanese Patent Application Laid-Open No. 8-126648 discloses an endoscopic treatment tool. In this treatment tool, the treatment section is inserted into a patient's body cavity, and the control wire rope transmits pushing and pulling forces and rotational forces (torque) from the hand-operated control section to the treatment section at the tip. The transmitted forces allow the treatment section to reach the treatment target area, where medical treatment is performed. The control rope is required to transmit hand-operated operations without delay. In particular, it is required to have torque transmission capabilities (rotational tracking capabilities) that transmit hand-operated rotational operations without delay. Furthermore, flexibility is required when the endoscope is inserted into a curved section inside the body.

JP 2019-44305 A discloses an operating rope with twisted side wires. This operating rope has excellent torque transmission properties and is flexible.

JP 2005-13296 A discloses an operating rope in which a parallel-twisted outer layer is twisted with a first-twisted lower layer, and the outer periphery of the first-twisted outer layer is resin-coated.

Japanese Patent Application Publication No. 8-126648 JP 2019-44305 A JP 2005-13296 A

With the development of medical equipment, there is a demand for even better torque transmission capabilities in operating ropes. The present invention provides a medical equipment operating rope with even better torque transmission capabilities.

The operating rope for medical equipment according to the present invention has a layered twisted structure with a core wire and side wires twisted helically around the core wire, with at least one of the wires coated with resin.

Preferably, the wire whose periphery is coated with resin is the core wire.

Preferably, the resin is a fluorine-based resin.

Preferably, the coating thickness of the resin is 1 μm or more and 100 μm or less.

Preferably, the wire is made of carbon steel.

The present invention may also be a method for manufacturing a rope for operating medical equipment, which comprises drawing a metal material to obtain metal wires, coating the metal wires with resin, twisting the metal wires together, and subjecting the twisted wires to a heat treatment at a temperature below the melting point of the resin.

The operating rope of the present invention has excellent torque transmission properties.

FIG. 1 is a cross-sectional view showing an embodiment of an operating rope according to the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the operating rope according to the present invention. FIG. 3 is a cross-sectional view showing still another embodiment of the operating rope according to the present invention. FIG. 4 is a cross-sectional view showing still another embodiment of the operating rope according to the present invention. FIG. 5 is a cross-sectional view showing still another embodiment of the operating rope according to the present invention. FIG. 6 is a cross-sectional view showing still another embodiment of the operating rope according to the present invention. FIG. 7 is a cross-sectional view of a conventional operating rope. FIG. 8 is a cross-sectional view of another conventional operating rope. FIG. 9 is a diagram showing a part of a manufacturing process for an operating rope according to the present invention. FIG. 10 is an explanatory diagram showing a method for measuring the torque transmission property of the operating rope of FIG. FIG. 11 is a graph showing the evaluation results of the torque transmission properties of the operating rope measured by the method of FIG.

The present invention will now be described in detail based on preferred embodiments, with appropriate reference to the drawings.

Figures 1 to 6 show enlarged cross-sectional views of several embodiments of the operating wire rope (hereinafter simply referred to as rope) according to the present invention. Each shows a cross section perpendicular to the length of the operating rope. Each of ropes 1, 5, 9, 13, 17, and 23 is composed of a strand made of multiple wires twisted together. The wires are made of a metal material. The present invention is not limited to the configurations of the embodiments shown in Figures 1 to 6.

This operating rope is cut to a predetermined length and used as a component of a medical device. For example, one end is connected to the hand-operated operating section of the medical device, and the other end is connected to the treatment section as the tip. Pushing, pulling, and torque applied to the hand-operated section are transmitted to the tip section via the operating rope. This positions the treatment section at the treatment site and performs treatment. The typical diameter D of the operating rope is 0.3 mm to 5 mm. Figures 7 and 8 show examples of conventional wire ropes. Figure 7 shows a rope without a resin coating on the wires. Figure 8 shows a rope in which the outer circumference of the rope is coated with an integral resin 34.

The rope 1 shown in Figure 1 is constructed with a 1+6 layer twist consisting of one core wire (core wire) 2 and six outermost layer wires (also called side wires) 3. The core wire is coated with resin 4. The rope 5 shown in Figure 2 is constructed with a 1+6 layer twist consisting of one core wire (core wire) 6 and six outermost layer side wires 7. The core wire and three side wires are coated with resin 8. The rope 9 shown in Figure 3 is constructed with a 1+6 layer twist consisting of one core wire (core wire) 10 and six outermost layer side wires 11. All six side wires are coated with resin 12. The rope 13 shown in Figure 4 is constructed with a 1+6 layer twist consisting of one core wire (core wire) 14 and six outermost layer side wires 15. The core wire and all six side wires are coated with resin 16. Because at least one of the wires of the present invention is coated with resin, the coated area has good slipperiness, making the rope flexible. Because the rope is flexible, there is less energy loss when the rope transmits rotation in a bent state, making it easier to transmit rotational force from the base end to the tip, and improving torque transmission. The effects of the present invention are achieved when at least one of the core wire and side wires is resin coated. Figure 1, in which the core wire is resin coated, is preferred because it contacts all of the side wires. The configurations of Figures 2 and 3, in which there is no metal-to-metal contact between the wires, are even more preferred. The configuration of Figure 4, in which all wires are resin coated, is particularly preferred.

The rope 7 shown in Figure 5 is constructed with a 1+6+12 layer twist consisting of a core strand 21, which is the lower layer of the 1+6 layer twist, and 12 side wires 20. In this rope 17, side wires 20 of a different diameter than the lower layers are used in the outermost layer to make the cross-sectional shape closer to a circle, but all side wires may be of the same diameter. The core wire 18 is coated with resin. In Figure 8, the side wires in the outermost layer have the same diameter as the side wires in the lower layers and are tightly twisted together. All wires are coated with resin. All of these are suitable twist configurations for operating ropes, but are not limited to these.

The resin used for coating may be a thermosetting resin such as polyimide resin, or a thermoplastic resin such as polyurethane. Fluorine resins are preferred from the standpoints of slipperiness, biocompatibility, and chemical resistance. Examples of fluororesins include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylene-propene copolymer (FEP), and polyvinylidene fluoride (PVDF). PTFE is particularly preferred from the standpoint of versatility.

The thickness of the resin coating is preferably between 1 μm and 100 μm, more preferably between 5 μm and 80 μm, and particularly preferably between 10 μm and 50 μm. If it is less than 1 μm, the slipperiness may decrease with repeated use. If it is more than 100 μm, the overall strength of the rope will decrease, reducing the ability to transmit pushing and pulling forces, and increasing costs more than necessary.

When multiple wires are coated, the type of resin may be the same for each wire or different for each wire.

Each wire of this operating rope is made from a metal material. Preferred metal materials include austenitic stainless steels SUS304 and SUS316, and nickel-titanium alloys. The strength is preferably 2000 MPa or more, and more preferably 2500 MPa or more. In addition, carbon steel is an example of a metal material for each wire. Carbon steel can be made stronger than stainless steel. The strength is preferably 3000 MPa or more, and more preferably 3500 MPa or more. From the perspective of medical use, it is preferable that the carbon steel wire is coated with resin. Of course, there is no limitation to these materials.

This operating rope 1 is manufactured by the following method, but is not limited to this. The manufacturing process consists of the following steps: wire drawing, resin coating, drying and heat treatment, stranding, and straightening heat treatment. In the resin coating and drying and heat treatment processes, resin coating can be achieved by applying resin, immersing in a resin liquid or resin dispersion, or spraying with a resin liquid or resin liquid dispersion. Co-extrusion of molten resin and metal is also acceptable. The resin-coated wires are dried as needed. They may be heated in a heat treatment furnace after drying. The drying and heat treatment steps may be omitted. The resin coating process may involve continuous resin coating of the wires, as shown in Figure 9. The wires 2 wound around a reel 36 pass through a coating tank 37 containing a resin liquid or a coating liquid with a resin dispersion, are dried, heated in a heat treatment furnace 38, and wound onto a reel 39. In the stranding process, the resin-coated wires serve as core wires, and are twisted together with uncoated wires to form a rope. In the twisting process, a twisting machine is used. Examples include tubular-type twisting machines and buncher-type twisting machines. In the straightening heat treatment process, tension is applied to the rope, and the rope is straightened by heat treatment. The heat treatment temperature is preferably lower than the melting point of the resin.

The material of the side wires may be the same as or different from the material of the core wires. Furthermore, the materials of the side wires may be the same as or different from each other. The tensile strength of the core wires and side wires is preferably 2000 MPa or more, more preferably 2500 MPa or more, and particularly preferably 2800 MPa or more.

The effects of the present invention will be demonstrated by the following examples, but the present invention should not be construed as being limited based on the description of these examples.

[Example 1]
A 0.25 mm diameter wire was obtained by drawing SUS304 steel using a die. The tensile strength of this wire was 2800 MPa. This wire was then coated with polytetrafluoroethylene (PTFE) by dipping. The coating thickness was 10 μm. The coated wire was used as a core wire, and one core wire and six 0.23 mm diameter SUS304 side wires were fed into a tubular-type twisting machine to obtain a twisted wire having the structure shown in FIG. 1. The twist pitch of this twisted wire was 5.5 mm. This twisted wire was straightened in a continuous heat treatment furnace at 250°C to obtain the operating rope of Example 1.

[Example 2]
As in Example 1, a PTFE-coated wire with a wire diameter of 0.25 μm was obtained. Seven of these wires were used in a tubular-type twisting machine to obtain a rope with the 1+6 configuration shown in Figure 3. The twist pitch of this twisted wire was 5.5 mm. This twisted wire was subjected to continuous heat treatment at a temperature of 250°C to straighten it, yielding the operating rope of Example 2.

[Example 3]
The carbon steel material was brass-plated and then drawn using a die to obtain a wire with a diameter of 0.25 mm. The tensile strength of this wire was 3200 MPa. This wire was then coated with polytetrafluoroethylene (PTFE) by a dipping method. The coating thickness was 20 μm. The coated wire was used as a core wire, and one core wire and six SUS304 side wires with a diameter of 0.23 mm were fed into a tubular-type twisting machine to obtain a twisted wire having the structure shown in FIG. 1. The twist pitch of this twisted wire was 5.5 mm. This twisted wire was subjected to straightening in a continuous heat treatment furnace at a temperature of 250°C to obtain the operating rope of Example 1.

[Comparative Example 1]
An operating rope having the configuration shown in Figure 7, in which the core wires were not coated with resin, was obtained in the same manner as in Example 1. This was designated Comparative Example 1.

[Comparative Example 2]
A PTFE coating was applied to the periphery of the rope of Comparative Example 1 to obtain a coated rope having a circular cross section including the resin-coated portion, which had the same configuration as that shown in Fig. 8. This was designated Comparative Example 2.

[Evaluation of Torque Transmittance] As shown in Figure 10, torque transmittance is evaluated by the difference in rotation angle between the proximal end of the spiral and the distal end when the spiral is rotated. A rigid pipe with a double spiral, 41 as shown in Figure 10, is used. The double spiral 41 may be a single turn rather than a double spiral. A double spiral is preferred as it allows for clearer evaluation differences. The diameter of the double spiral portion 41 is 200 mm. A rotational force is applied to the proximal end 42 of the rope 1 passed through this rigid pipe in the direction indicated by arrow R1. This causes the distal end 43 of the operating rope 1 to rotate as indicated by arrow R2. The rotation angles of the proximal end 42 and the distal end 43 are measured simultaneously.

Figure 11 is a graph showing the results of torque transmission measured using the method shown in Figure 10. Figure 10 shows the correspondence between the rotation angle at the proximal end of the operating rope and the rotation angle at the distal end at the same time. The dashed line in the graph is a straight line indicating that the difference between the rotation angle at the proximal end and the rotation angle at the distal end is zero. The solid curve in the graph shows an example of a measured operating rope. The difference between the rotation angle at the proximal end and the rotation angle at the distal end is the difference on the vertical axis between the dashed line and the solid line. The smaller the maximum value of the rotation angle difference measured within the range of 0° to 360° for the proximal end rotation angle, the better the torque transmission.

Table 1 below shows the maximum angle difference for each rope in Examples 1-3 and Comparative Examples 1 and 2, expressed as a number when the maximum angle difference for Comparative Example 1 is set to 100. Operating ropes with a smaller index have excellent torque transmission properties.

As shown in Table 1, the evaluation results clearly demonstrate the superiority of the present invention.

The operating rope of the present invention can be applied to a variety of medical devices.

1, 5, 9, 13, 17, 23... Operating rope 2, 6, 10, 14, 18, 24... Core wire 3, 7, 11, 15, 20, 25... Side wire 4, 8, 12, 16, 22, 27, 34... Resin coating layer 21, 26... Core strand

Claims (3)

A medical device operating rope having a layered structure with a core wire and side wires twisted helically around the core wire, the core wire being coated with resin, and the outermost side wires of the layered structure not being coated with resin, and all of the side wires in the layered structure being made of austenitic stainless steel and having a tensile strength of 2500 MPa or more. 2. The operating rope according to claim 1, wherein the resin is a fluorine-based resin. The operating rope according to claim 1 or claim 2, wherein the resin coating thickness is 1 μm or more and 100 μm or less.