Electrolytic polishing apparatus and method for manufacturing medical tubular bodies using the same

Abstract

The present invention provides an electropolishing apparatus that can stably hold medical tubular materials in an electrolyte solution with minimal stress, and perform electropolishing in a suitable manner. [Solution] An electrolytic polishing apparatus 1 for medical tubular bodies comprises an electrolyte tank 3 holding an electrolyte solution 2, a medical tubular body 10 immersed in the electrolyte solution 2, a first roller 4 positioned inside the lumen of the medical tubular body 10, and a second roller 5 positioned outside the medical tubular body 10 and above the first roller 4. The medical tubular body 10 is the anode, and a cathode 6 is placed in the electrolyte solution 2. The outer diameter of the first roller 4 is smaller than the inner diameter of the medical tubular body 10, the inner surface of the medical tubular body 10 is in contact with the circumferential surface of the first roller 4, and the outer surface of the medical tubular body 10 is in contact with the circumferential surface of the second roller 5.

Description

Technical Field

[0001] The present invention relates to an electrolytic polishing apparatus and a method for manufacturing a medical tubular body having a step of electrolytically polishing using the same.

Background Art

[0002] Medical tubular bodies are medical tools for treating various diseases caused by stenosis or occlusion of internal lumens such as blood vessels. A stent, which is a typical medical tubular body, is a medical tool that is placed in a lesion such as a stenosis or occlusion site of an internal lumen to expand the lesion from the inside and maintain the inner diameter of the lumen.

[0003] Medical tubular bodies typified by stents are required to have a smooth surface. If there are sharp portions on the surface of a medical tubular body, it may cause inflammation by damaging the inner wall of the internal lumen or overly stimulating it when the medical tubular body is placed in the internal lumen or after placement. Therefore, during the manufacture of medical tubular bodies such as stents, a process for finishing the surface smoothly is usually performed.

[0004] As a method for smoothing the surface of a medical tubular body, electrolytic polishing can be mentioned. As an electrolytic polishing apparatus for performing electrolytic polishing of a medical tubular body, for example, Patent Document 1 discloses an electrolytic polishing apparatus including an anode pair set having at least one pair of anodes that are paired, and a movable part that approaches or separates the anodes in the anode pair. Patent Document 2 discloses an electrolytic polishing apparatus for electrolytically polishing a tubular body that is deformable in the radial direction, the apparatus including an anode conductive member, and the anode conductive member contacts and supports the inner side of the tubular body so as to substantially expand the diameter of the tubular body in a circular shape from the inside thereof.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the electropolishing of medical tubular materials, it is desirable that the medical tubular material to be electropolished be held stably in the electrolyte with as little load as possible and that it be able to rotate stably in the circumferential direction. This allows for suitable electropolishing of the medical tubular material over its entire circumference while suppressing deformation of the medical tubular material during electropolishing. The present invention has been made in view of the above circumstances, and its object is to provide an electropolishing apparatus that can stably hold a medical tubular material in the electrolyte with as little load as possible and perform suitable electropolishing, and a method for manufacturing a medical tubular material using the same. [Means for solving the problem]

[0007] The electrolytic polishing apparatus and method for manufacturing a medical tubular body of the present invention, which have solved the aforementioned problems, are as follows. [1] An electrolytic polishing apparatus for a medical tubular body, comprising: an electrolyte tank holding an electrolyte solution; a medical tubular body immersed in the electrolyte solution; a first roller positioned in the lumen of the medical tubular body; and a second roller positioned on the outside of the medical tubular body and above the first roller, wherein the medical tubular body is the anode, the cathode is placed in the electrolyte solution, the outer diameter of the first roller is smaller than the inner diameter of the medical tubular body, the inner surface of the medical tubular body is in contact with the circumferential surface of the first roller, and the outer surface of the medical tubular body is in contact with the circumferential surface of the second roller. [2] The electrolytic polishing apparatus according to [1], wherein the first roller is a drive roller. [3] The electrolytic polishing apparatus according to [2], wherein the second roller is a free roller. [4] An electrolytic polishing apparatus according to any one of [1] to [3], further comprising a power supply, wherein the circumferential surface of the first roller is conductive, the positive electrode of the power supply is electrically connected to the medical tubular body via the first roller, and the negative electrode of the power supply is electrically connected to the cathode. [5] The electrolytic polishing apparatus according to any one of [1] to [4], wherein the outer diameter of the second roller is larger than the outer diameter of the first roller. [6] The medical tubular body is a stent.[1] to [5] The electrolytic polishing apparatus according to any one of these. A method for manufacturing a medical tubular body, comprising the step of electropolishing the medical tubular body using an electropolishing apparatus described in any of [7] [1] to [6]. [Effects of the Invention]

[0008] According to the electropolishing apparatus and method for manufacturing medical tubular bodies of the present invention, it is possible to stably hold a medical tubular body in an electrolyte solution while rotating the medical tubular body in the circumferential direction, and to suitably electropolish the medical tubular body over its entire circumference. In this case, the load on the medical tubular body can be reduced, so deformation of the medical tubular body during electropolishing can be suppressed, and even flexible medical tubular bodies with low rigidity can be suitably electropolished. [Brief explanation of the drawing]

[0009] [Figure 1] This is an example of the configuration of the electrolytic polishing apparatus of the present invention, and shows a schematic diagram of the electrolytic polishing apparatus. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below based on the embodiments described below. However, the present invention is not limited by the embodiments described below, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority has been given to helping to understand the features of the present invention.

[0011] The present invention relates to an electrolytic polishing apparatus for medical tubular bodies. Examples of medical tubular bodies include stents, stent grafts, occlusion devices, injection catheters, and prosthesis valves. Medical tubular bodies can be manufactured, for example, by cutting out metal tubes with a laser or the like, but in this case, the cut end surface of the metal tube may become sharp. If a medical tubular body with a sharply formed cut end surface is used without polishing, when the medical tubular body is transported to the treatment area in the body lumen by a medical tubular body transport device and deployed, the medical tubular body may get caught inside the medical tubular body transport device, hindering deployment, or the body lumen in which the medical tubular body is implanted may be damaged. Therefore, in the manufacture of medical tubular bodies, it is necessary to polish the cut end surface after cutting out the metal tube, and the electrolytic polishing apparatus of the present invention can be suitably used for such polishing processes.

[0012] Electropolishing is a technique for polishing metal surfaces by dissolving them using electrolysis. Electropolishing causes metal atoms on the surface to dissolve as ions, removing fine protrusions and resulting in a polished surface. In the case of medical tubular materials, electropolishing can round off sharp edges on the cut ends of metal tubes and smooth the surface. Electropolishing medical tubular materials can improve the reliability and safety of their placement in internal tubular structures.

[0013] Medical tubular bodies are not particularly limited as long as they are made of metal. Examples of metals that make up medical tubular bodies include stainless steel such as SUS304 and SUS316, carbon steel, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, nickel-titanium alloy, cobalt-chromium alloy, tungsten alloy, and magnesium alloy.

[0014] The electrolytic polishing apparatus of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram of the electrolytic polishing apparatus, which is an example of the configuration of the electrolytic polishing apparatus according to an embodiment of the present invention. The electrolytic polishing apparatus 1 includes an electrolyte tank 3 that holds an electrolyte 2, a medical tubular body 10 immersed in the electrolyte 2, a first roller 4 positioned in the lumen of the medical tubular body 10, and a second roller 5 positioned on the outside of the medical tubular body 10 and above the first roller 4. The outer diameter of the first roller 4 is smaller than the inner diameter of the medical tubular body 10, the inner surface of the medical tubular body 10 is in contact with the circumferential surface of the first roller 4, and the outer surface of the medical tubular body 10 is in contact with the circumferential surface of the second roller 5. The medical tubular body 10 is used as the anode, and a cathode 6 is installed in the electrolyte 2. By passing an electric current between the medical tubular body 10, which is the anode, and the cathode 6 installed in the electrolyte 2, the medical tubular body 10 can be electrolytically polished. The electrolytic polishing apparatus 1 preferably includes a power supply 7, wherein the positive electrode of the power supply 7 is electrically connected to the medical tubular body 10 so that the medical tubular body 10 can function as an anode, and the negative electrode of the power supply 7 is electrically connected to the cathode 6.

[0015] In the electropolishing of the medical tubular body 10, the areas of the medical tubular body 10 that are close to the cathode 6 are preferentially electropolished. Since the electropolishing apparatus 1 can rotate the medical tubular body 10 in the electrolyte solution 2 in the circumferential direction, the entire circumferential direction of the medical tubular body 10 can be positioned close to the cathode 6 at some point, and the medical tubular body 10 can be suitably electropolished over its entire circumference. Furthermore, by installing the first roller 4 and the second roller 5 as described above to hold the medical tubular body 10, the load on the medical tubular body 10 can be reduced. Therefore, deformation of the medical tubular body 10 during electropolishing can be suppressed, and even a flexible medical tubular body 10 with low rigidity can be suitably electropolished.

[0016] The electrolyte cell 3 holds the electrolyte 2, and the medical tubular body 10 is immersed in the electrolyte 2, and a cathode 6 is installed therein. Preferably, the entire medical tubular body 10 is immersed in the electrolyte 2. The electrolyte 2 may be an aqueous solution such as an acid or inorganic salt solution, or an organic solution, as long as it is a liquid that can conduct electric current. Specific examples of the electrolyte 2 include phosphoric acid, sulfuric acid, nitric acid, chromic acid, sodium chloride solution, ethanol, methanol, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, etc., which may be used individually or in mixtures. The electrolyte 2 may contain additives.

[0017] The medical tubular body 10 immersed in the electrolytic solution 2 is held sandwiched between the first roller 4 and the second roller 5. Specifically, the first roller 4 is disposed inside the lumen of the medical tubular body 10, and the second roller 5 is disposed outside the medical tubular body 10 and above the first roller 4. The inner surface of the medical tubular body 10 contacts the circumferential surface of the first roller 4, and the outer surface of the medical tubular body 10 contacts the circumferential surface of the second roller 5. The rotation axes of the first roller 4 and the second roller 5 are arranged to extend in a substantially horizontal direction and are parallel to each other. By holding the medical tubular body 10 sandwiched between the first roller 4 and the second roller 5 in this way, the medical tubular body 10 can be rotated in the circumferential direction while being stably held in the electrolytic solution 2.

[0018] Regarding the positional relationship between the first roller 4 and the second roller 5, as long as the rotation axis of the second roller 5 is located above the rotation axis of the first roller 4, the inner surface of the medical tubular body 10 contacts the circumferential surface of the first roller 4, and the outer surface of the medical tubular body 10 contacts the circumferential surface of the second roller 5, the second roller 5 may be disposed vertically above the first roller 4 or may be disposed obliquely above the first roller 4. Incidentally, the rotation axis of the second roller 5 is preferably located above the upper end of the circumferential surface of the first roller 4. <000,0093>

[0019] In a vertical cross-section in the direction of the extension of the rotation axes of the first roller 4 and the second roller 5, the straight line connecting the rotation axis of the first roller 4 and the rotation axis of the second roller 5 is preferably inclined at an angle within 45° with respect to the vertical direction, more preferably within 30°, even more preferably within 15°, and even more preferably within 10°. Also, at least a part of the second roller 5 is preferably disposed vertically above at least a part of the first roller 4, and more preferably, the rotation axis of the second roller 5 is located vertically above the rotation axis of the first roller 4. Since the outer diameter of the first roller 4 is smaller than the inner diameter of the medical tubular body 10, when an upward force such as buoyancy acts on the medical tubular body 10 in the electrolytic solution 2, the medical tubular body 10 may move along the circumferential surface of the first roller 4, and the distance between the medical tubular body 10 and the cathode 6 may change. By arranging the first roller 4 and the second roller 5 in this way and sandwiching and holding them with the first roller 4 and the second roller 5, it becomes easier to hold the medical tubular body 10 at a predetermined position. Therefore, it becomes easier to keep the distance between the medical tubular body 10 and the cathode 6 within a certain range.

[0020] The outer diameter of the first roller 4 is formed smaller than the inner diameter of the medical tubular body 10. Thereby, the outer surface of the first roller 4 does not contact the entire inner surface of the medical tubular body 10, and the load applied to the medical tubular body 10 can be reduced. Also, when installing the first roller 4 in the inner cavity of the medical tubular body 10 or removing the medical tubular body 10 from the first roller 4, an excessive force is not applied to the medical tubular body 10, and it is possible to suppress the medical tubular body 10 from being distorted. Therefore, it becomes easier to install the first roller 4 in the inner cavity of the medical tubular body 10 when electro-polishing the medical tubular body 10, or to remove the medical tubular body 10 from the first roller 4 after electro-polishing. For example, even for a flexible medical tubular body 10 with low rigidity, it becomes easier to install the first roller 4 in the inner cavity of the medical tubular body 10 or to remove the medical tubular body 10 from the first roller 4 without distorting the medical tubular body 10. Note that it is preferable that no roller other than the first roller 4 is arranged in the inner cavity of the medical tubular body 10.

[0021] The outer diameter of the first roller 4 is preferably 0.9 times or less the inner diameter of the medical tubular body 10, and more preferably 0.8 times or less. This makes it easy to install the first roller 4 into the lumen of the medical tubular body 10 and to remove the medical tubular body 10 from the first roller 4. The outer diameter of the first roller 4 is preferably 0.3 times or more the inner diameter of the medical tubular body 10, and more preferably 0.4 times or more. This makes it easier to hold the medical tubular body 10 in a predetermined position on the circumferential surface of the first roller 4.

[0022] The sizes of the first roller 4 and the second roller 5 are not particularly limited. The outer diameter of the first roller 4 may be larger or smaller than the outer diameter of the second roller 5, and the outer diameter of the first roller 4 may be the same as the outer diameter of the second roller 5. However, it is preferable that the outer diameter of the second roller 5 be larger than the outer diameter of the first roller 4, in order to make it easier for the medical tubular body 10 to be held in a predetermined position when an upward force such as buoyancy acts on it in the electrolyte 2. In this case, the outer diameter of the second roller 5 is preferably 1.1 times or more than the outer diameter of the first roller 4, more preferably 1.2 times or more, even more preferably 1.3 times or more, and preferably 5.0 times or less, more preferably 4.0 times or less, and even more preferably 3.0 times or less.

[0023] It is preferable that the first roller 4 and the second roller 5 are smooth rollers. That is, it is preferable that the surfaces of the rollers be smooth. This makes it less likely for the medical tubular body 10 to get caught on the surfaces of the first roller 4 and the second roller 5 when the medical tubular body 10 is sandwiched between the first roller 4 and the second roller 5 and rotated, thus reducing the likelihood of damage to the medical tubular body 10.

[0024] The first roller 4 and the second roller 5 may be drive rollers or free rollers. The drive rollers may be driven by human power or by electricity. The free rollers rotate subordinately to the circumferential rotation of the medical tubular body 10.

[0025] Preferably, at least one of the first roller 4 and the second roller 5 is a drive roller, and more preferably, the first roller 4 is the drive roller. Since the outer diameter of the first roller 4 is smaller than the inner diameter of the medical tubular body 10, by making the first roller 4 a drive roller, it becomes easy to accurately adjust the circumferential position of the medical tubular body 10 by the rotation of the first roller 4. On the other hand, it is preferable that the second roller 5 is a free roller, which prevents the outer surface of the medical tubular body 10 from being scratched by the second roller 5, and makes it easier to form a smooth outer surface of the medical tubular body 10.

[0026] Preferably, at least one of the first roller 4 and the second roller 5 has a conductive circumferential surface, and preferably the positive electrode of the power supply 7 is connected to the medical tubular body 10 via the first roller 4 or the second roller 5. This ensures that even when the medical tubular body 10 is rotated in the circumferential direction, the medical tubular body 10 remains electrically stable with the positive electrode of the power supply 7, allowing the medical tubular body 10 to function stably as an anode. On the other hand, the circumferential surfaces of both the first roller 4 and the second roller 5 may be non-conductive. In this case, for example, a brush electrode can be installed in contact with the medical tubular body 10, and the positive electrode of the power supply 7 can be connected to the medical tubular body 10 via the brush electrode.

[0027] The first roller 4 and the second roller 5 can be made of metal or resin. Preferably, at least one of the first roller 4 and the second roller 5 has a metal circumferential surface, which allows the circumferential surface of the first roller 4 or the circumferential surface of the second roller 5 to be made conductive. The entire first roller 4 or the entire second roller 5 may also be made of metal.

[0028] At least one of the first roller 4 and the second roller 5 may have a circumferential surface made of resin. This makes it less likely for the medical tubular body 10 to be distorted or damaged while sandwiched between the first roller 4 and the second roller 5. The entire first roller 4 or the entire second roller 5 may also be made of resin.

[0029] The circumferential surface of the first roller 4 is preferably conductive, and the positive electrode of the power supply 7 is preferably electrically connected to the medical tubular body 10 via the first roller 4. Since the first roller 4 is positioned inside the lumen of the medical tubular body 10, the electrical connection of the positive electrode of the power supply 7 to the medical tubular body 10 via the first roller 4 makes it easier for the medical tubular body 10, rather than the circumferential surface of the first roller 4, to function as the anode, and current preferentially flows between the medical tubular body 10 and the cathode 6. On the other hand, the circumferential surface of the second roller 5 is preferably non-conductive. For example, it is preferable that the circumferential surface of the first roller 4 is made of metal and the circumferential surface of the second roller 5 is made of resin.

[0030] The cathode 6 is installed in the electrolyte 2, and its installation configuration is not particularly limited. The entire cathode 6 may be installed in the electrolyte 2, or only a part of the cathode 6 may be installed in the electrolyte 2. The cathode 6 may be installed on the wall or bottom surface of the electrolyte tank 3, or it may be installed away from the wall and bottom surface of the electrolyte tank 3. It is preferable that the cathode 6 is provided facing the circumferential surface of the medical tubular body 10, and more preferably that it is provided facing only a part of the circumferential surface of the medical tubular body 10.

[0031] The shape of the cathode 6 is not particularly limited and can be, for example, planar, curved, or rod-shaped. If the cathode 6 is curved, it is preferable that the cathode 6 is curved along the circumferential surface of the medical tubular body 10.

[0032] It is preferable that the cathode 6 is not positioned vertically below the medical tubular body 10. This prevents sludge from accumulating on the surface of the cathode 6 when sludge is generated by the electrolytic polishing of the metal constituting the medical tubular body 10. It is preferable that the cathode 6 be installed, for example, to the side of the medical tubular body 10.

[0033] The medical tubular body 10 is preferably a stent. Since stents are structurally relatively weak against forces from the outer circumference, electrolytic polishing using the electrolytic polishing apparatus 1 makes it less likely for the medical tubular body 10 to deform during electrolytic polishing.

[0034] The electrolytic polishing apparatus 1 is particularly suitable for the electrolytic polishing of medical tubular bodies 10 made of metals with low specific gravity. Medical tubular bodies 10 made of metals with low specific gravity are susceptible to upward forces such as buoyancy in the electrolyte 2, making it difficult to stably hold them in a predetermined position. However, by performing electrolytic polishing using the electrolytic polishing apparatus 1, it becomes easier to stably hold the medical tubular bodies 10 in a predetermined position during electrolytic polishing. The specific gravity of the metal constituting the medical tubular bodies 10 is, for example, 4.0 g / cm³. 3 Below 3.0g / cm 3 The following or 2.0 g / cm³ 3 It may also be less than 1.0 g / cm³. 3 More than 1.2g / cm 3 or more, or 1.5 g / cm³ 3 That's fine too.

[0035] The electrolytic polishing apparatus 1 is also suitably applicable to the electrolytic polishing of medical tubular bodies 10 made of flexible metals with a low Young's modulus. Medical tubular bodies 10 made of flexible metals with a low Young's modulus are prone to deformation under external force. By performing electrolytic polishing using the electrolytic polishing apparatus 1, deformation of the medical tubular bodies 10 during electrolytic polishing can be reduced. The Young's modulus of the metal constituting the medical tubular bodies 10 may be, for example, 100 GPa or less, 80 GPa or less, or 60 GPa or less, or it may be 10 GPa or more, 20 GPa or more, or 30 GPa or more.

[0036] The present invention also provides a method for manufacturing a medical tubular body, comprising a step of electropolishing the medical tubular body 10 using an electropolishing apparatus 1 (hereinafter referred to as the "electropolishing step"). In the electropolishing step, an electric current is passed between the medical tubular body 10, which functions as an anode, and the cathode 6 in an electrolyte solution 2 to perform electropolishing of the medical tubular body 10. In the electropolishing step, the medical tubular body 10 can be rotated in the circumferential direction by rotating the first roller 4 or the second roller 5, but the electropolishing of the medical tubular body 10 may be performed while the medical tubular body 10 is rotated, or the electropolishing of the medical tubular body 10 and the rotation of the medical tubular body 10 may be performed alternately.

[0037] According to the method for manufacturing a medical tubular body of the present invention, the medical tubular body 10 can be stably held in the electrolyte 2 and rotated in the circumferential direction, allowing for suitable electropolishing of the medical tubular body 10 over its entire circumference. In this process, the load on the medical tubular body 10 can be reduced, thereby suppressing deformation of the medical tubular body 10 during electropolishing, and allowing for suitable electropolishing even of a flexible medical tubular body 10 with low rigidity. [Explanation of Symbols]

[0038] 1: Electrolytic polishing equipment 2: Electrolyte 3: Electrolyte tank 4: First Roller 5: Second Roller 6: Cathode 7: Power supply 10: Medical tubular body

Claims

1. An electrolytic polishing apparatus for medical tubular materials, An electrolyte cell containing the electrolyte, A medical tubular body immersed in the aforementioned electrolyte, A first roller is positioned inside the lumen of the aforementioned medical tubular body, The medical tubular body has a second roller located on the outside of the first roller and above the first roller, The aforementioned medical tubular body is used as the anode, and the cathode is placed in the electrolyte solution. The outer diameter of the first roller is smaller than the inner diameter of the medical tubular body. An electrolytic polishing apparatus in which the inner surface of the medical tubular body is in contact with the circumferential surface of the first roller, and the outer surface of the medical tubular body is in contact with the circumferential surface of the second roller.

2. The electrolytic polishing apparatus according to claim 1, wherein the first roller is a drive roller.

3. The electrolytic polishing apparatus according to claim 2, wherein the second roller is a free roller.

4. Furthermore, it has a power supply, The circumferential surface of the first roller is conductive, and the positive electrode of the power supply is electrically connected to the medical tubular body via the first roller. The electrolytic polishing apparatus according to claim 1, wherein the negative electrode of the power supply is electrically connected to the cathode.

5. The electrolytic polishing apparatus according to claim 1, wherein the outer diameter of the second roller is larger than the outer diameter of the first roller.

6. The electrolytic polishing apparatus according to claim 1, wherein the medical tubular body is a stent.

7. A method for manufacturing a medical tubular body, comprising the step of electropolishing the medical tubular body using an electropolishing apparatus according to any one of claims 1 to 6.

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