JP6181135B2 - Straight knife manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an ophthalmic straight knife.

  Straight knives and LRI knives used in ophthalmic surgery have a thin and sharp tip followed by a straight cutting blade with a length of several millimeters. And when using it, it cuts into the cornea and sclera mainly by moving the tip and the cutting blade part about 1 mm from the tip in a direction intersecting the knife axial direction and parallel to the blade part. .

  Conventionally, martensitic stainless steel has been used as a material for medical knives. Since martensitic stainless steel can be quenched, desired hardness and good sharpness can be obtained.

  However, since martensitic stainless steel is less susceptible to rust than austenitic stainless steel, it is desirable for medical use to use austenitic stainless steel that is more resistant to rust. However, austenitic stainless steel cannot be quenched and it is difficult to obtain a desired hardness.

  On the other hand, austenitic stainless steel wire is drawn and work hardened to obtain a predetermined hardness. The stainless steel wire that has been drawn and hardened in this way has a crystal structure that is elongated in the length direction of the steel wire, and is called a fiber-like structure.

  The method of manufacturing a medical knife from such austenitic stainless steel having a fibrous structure is almost the same as that of manufacturing from martensitic stainless steel. That is, austenitic stainless steel wire rod is cut into a predetermined length to make a round bar shape, one end side of this round bar is flattened with a press, and the crushed part is formed into a knife shape in the next press step, A medical knife is manufactured by forming a cutting edge by grinding with a grindstone or the like. In the case of the martensite system, heat treatment and finish polishing are performed thereafter. However, in the case of the austenite system, the heat treatment process is not performed.

  Since sharpness is a problem for medical knives, various measures have been taken to improve sharpness. As a countermeasure against this, silicone is often applied. This is because the silicone film reduces the frictional resistance (for example, Patent Document 1).

  Patent Document 2 proposes an eye formed in a direction substantially orthogonal to the central axis of the suture needle and an eye along the central axis. This is because the material of the crystal structure of the fibrous structure is polished in a direction perpendicular to the direction of the fibrous structure, and the abrasive grains are lined up in the direction perpendicular to the direction of the fibrous structure, and then electropolishing and chemical By performing a treatment such as polishing, the stitches by the abrasive grains are etched to partially expose the fibrous structure. The streak along the central axis is formed by electrolytic polishing of the fiber-like texture pattern, and the streak in the direction substantially perpendicular to the central axis is a streak formed by abrasive grains during polishing. In this way, silicone is applied to a suture needle that is straight and used. With such a configuration, the adhesion force of silicone can be increased.

  Moreover, in patent document 3, the technique which removes the burr | flash made by grinding by performing electrolytic polishing to a blade edge part, makes a blade edge part into a mirror surface, sharply finishes a cutting blade, and improves a sharpness is proposed. .

JP 2003-116866 A Japanese Patent No. 3140508 JP-A-8-238245

  5A and 5B are diagrams of a conventional straight knife, where FIG. 5A is a plan view and FIG. 5B is a cross-sectional view taken along line EE of FIG. (C) is the figure seen from F of (a), and is an enlarged view of the blade edge | tip part of a knife, (d) is a figure which shows the state which the blade edge bent.

  The straight knife 1 shown in the figure uses austenitic stainless steel. As described above, a stainless steel round bar 1a is cut to a predetermined length, and the tip is flattened by pressing to form a flat blade portion 1b. One side of the blade portion 1b is slanted by grinding from both sides. 1c, a linear cutting edge 1d and an edge 1e are formed at the end of the inclined surface 1c.

  In general, in order to improve the sharpness of the straight knife 1, as shown in FIG. 5 (a), the angle α of the blade edge 1f is reduced or the knife thickness t is reduced. Therefore, when an incision is formed in the cornea, sclera, etc. in ophthalmic surgery, there is a problem that the cutting edge 1f is likely to be bent with an austenitic stainless steel knife. FIG. 5 (d) is a view of the peripheral portion of the blade edge 1f (hereinafter referred to as "blade edge portion"), which is the same as (c). Show. If the cutting edge portion is easily bent in this way, it becomes difficult to use as a knife. In addition, if the deformation is large, there is a problem that it cannot return to its original shape and can no longer be used as a knife.

The present invention aims to solve the above problems, and even a straight knife manufactured from austenitic stainless steel can increase the strength of a thin and sharp blade edge, is difficult to deform, and has a reduced sharpness. It aims at providing the straight knife which can prevent.

In order to achieve the above object, the straight knife manufacturing method of the present invention flattenes the tip side of an austenitic stainless steel round bar, and cuts the excess part with a press to form a blade on a flat plate. A step of forming an inclined surface and an edge along a peripheral edge of at least a part of the blade portion by grinding, removing burrs on the inclined surface and the edge by electrolytic polishing or chemical polishing, and further performing electrolytic polishing or chemical And a step of forming a cutting edge having a curved surface with a convex cross-sectional shape at the tip of the inclined surface by continuing polishing.

According to the straight knife manufactured by the manufacturing method of the present invention, since the cutting edge is rounded by electrolytic polishing or chemical polishing, the thickness of the cutting edge becomes thick and difficult to bend, and austenitic stainless steel is used. However, it is possible to prevent bending at the time of use, and an excellent effect of being easy to use can be obtained. Moreover, since austenitic stainless steel is used, a straight knife resistant to rust can be obtained.

  Note that the sharpness of the knife may be reduced by the amount the blade is rounded. However, since it is rounded by electrolytic polishing or chemical polishing, it is only a very small portion of the blade edge. Moreover, when the cutting blade is formed, burrs generated by grinding are removed by electrolytic polishing or chemical polishing, and the sharpness is improved. Accordingly, it is possible to ensure the same sharpness as that of the case of only grinding processing as a total.

In addition, when a knife as a subject of the present invention is cut by inserting a cutting edge into an object such as a sclera to a predetermined depth (in the axial direction) and moving it in a direction crossing the axis while maintaining substantially the same depth. This is a straight knife that is mainly used, so that the sharpness of the cutting edge only affects the first insertion of the knife into the tissue, and after that, the edge on the lower side (handle side) than the rounded part of the cutting edge. It is considered that even if the cutting edge is rounded because it is torn, it does not affect how the operator feels the sharpness during use.

Furthermore, the straight knife that is the subject of the present invention is not the subject of the present invention, and the maximum blade width dimension is accurately formed in order to form an incision for inserting an intraocular lens. Unlike knives that are moved in parallel directions and inserted into tissues, they are often used by inserting and cutting about 1-2 mm from the tip, so the angle of the cutting edge does not affect the sharpness as it is, Even if the angle of the knife and the cutting blade that forms the incision for inserting the intraocular lens is the same, the sharpness can be felt well

  The reason why the knife for forming the incision for inserting the intraocular lens is not the object of the present invention is that the knife for inserting the intraocular lens has a maximum blade width dimension when formed only by grinding. This is because it is easy to control and can be accurately formed.

  In addition, since the cutting blade is configured to be gently warped in the shape of a central bulge, the edge of the knife is not warped, and the angle of the handle of the knife with respect to the tissue is larger than that of the straight shape. The inclination angle of the edge can be reduced. Therefore, the sharpness is improved and the knife can be easily used. In addition, since the inclined surface is formed of a wrapping film, the inclined surface gently warps in a central protruding shape, and both end portions of the inclined surface (tip end side and end on the shank side) become convex curved surfaces. The angle of the inclined surface increases. By applying electrolytic polishing or chemical polishing there, the cutting edge is formed by following the central protruding shape as it is, and both end portions with a large angle are polished less, and the center portion with a small angle is polished more. As a whole, a uniform cutting edge angle can be formed, and the usability is improved.

(A)-(f) is a figure explaining the manufacturing method of the straight knife of this invention. (G), (h) is the figure which expanded the blade edge | tip part seen from A of (e), (g) is before electropolishing, (h) is after electropolishing. (A) is a top view of a straight knife, (b) is an enlarged view of a blade edge | tip part. FIG. 2B is a cross-sectional view taken along line BB in FIG. 2B, (a) before electropolishing and (b) after electropolishing. It is a figure of the LRI knife for astigmatism correction, (a) is a top view, (b) is a figure which shows the state before electrolytic polishing of CC sectional view of (a), (c) is the state after electrolytic polishing FIG. (D) is a figure which shows the state before electrolytic polishing of the DD sectional view taken on the line of (a), (e) is a figure which shows the state after electrolytic polishing. It is a figure of the prior art example of a straight knife, (a) is a top view, (b) shows the cross-sectional shape of a cutting blade in the EE sectional view taken on the line (a). (C) is the figure seen from F of (a), and is an enlarged view of the blade edge | tip part of a knife. (D) is a figure which shows the state which the blade edge | tip part bent.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 (a) to 1 (f) are diagrams for explaining a method of manufacturing a straight knife 10 of the present invention. First, as shown in (a), the material round bar 11 is cut into a predetermined length. As a material, an austenitic stainless steel round bar having a fiber-like crystal structure is used. Next, as shown in (b), the tip side is crushed flat with a press, and the excess part shown with a dotted line is cut in the next pressing process to have a flat point with a sharp tip, and the blade portion having a substantially rhombus in plan view 12 is formed. Then, as shown in (c) and (d), the flattened both sides 12 'are ground to make a flat surface, and the thickness t is set to a predetermined thickness. And both surfaces 12 'of the blade part 12 are made into an irregular reflection surface by blasting. By using the irregular reflection surface, it is possible to prevent the affected part from becoming difficult to see due to the knife shining when used under a microscope. Next, as shown in (e), an inclined surface 13 is formed on both surfaces 12 ′ by grinding, the tip of the inclined surface 13 is used as a cutting edge, and the tip edge (edge) 15 ′ of the cutting edge is sharpened sharply. Make it. The inclined surface 13 is formed up to the vicinity of the maximum width of the blade portion 12.

  The above is almost the same as the manufacturing method of the conventional straight knife. The present invention is characterized in that the electrolytic polishing process is performed without forming the cutting edge 14 by grinding.

FIG. 1G is an enlarged view of the blade edge portion 16 as viewed from A of FIG. 1E. FIG. 1G is before electropolishing and (h) is after electropolishing. The inclined surface 13 is formed by grinding with a grindstone, and although not shown in the figure, the lines of abrasive grains are uniformly formed in a direction orthogonal to the edge 15 ′, and further, the inclined surface 13 and the edge 15 ′ are further formed. A large number of burrs have occurred.

  In the present invention, after the inclined surface 13 is formed by grinding with a grindstone, electropolishing is performed. The electrolytic polishing treatment may be performed by a normal method. For example, a phosphoric acid solution is used as an electrolytic solution, the entire blade portion of a straight knife is immersed in the electrolytic solution and connected to the + electrode, and the electrolytic cell is connected to the negative electrode. And energize. The metal of the straight knife is eluted into the electrolytic solution, so that the polishing process is performed. At this time, the metal elutes first from the pointed part of the workpiece.

In the electrolytic polishing, first, burrs on the inclined surface 13 and the edge 15 ′ are eluted into the electrolytic solution, so that deburring is preferentially performed. Ordinary electropolishing is completed at this stage, but the present invention is characterized by further electropolishing.

If the electrolytic polishing is further continued after deburring, the streaks formed by the polishing are also reduced, the inclined surface 13 is dissolved, and a cutting edge 14 having a convex curved surface is formed at the end of the inclined surface 13. The leading edge of the cutting edge 14 is the edge 15 after polishing .

  FIG. 2A is an enlarged plan view of the blade portion 12 of the straight knife 10, and FIG. 2B is an enlarged view of the blade edge portion, in which both the electrolytic polishing is finished. . The cutting edge 16a has an arc surface having a radius R1 by melting the dotted line. After deburring, electrolytic polishing to this state increases the thickness of the blade edge 16a and increases the strength. By increasing the strength, the cutting edge 16 as shown in FIG. 5D can be prevented from bending. Further, the edge 15 of the cutting edge 14 is substantially linear, but the edge 15 is gently curved like a warp of a Japanese sword and has a shape close to an arc. A straight line n shown in FIG. 2A is a tangent to the edge 15.

  Even the cutting edge 16a of the straight knife 10 using conventional martensitic stainless steel is not sharp and slightly rounded when viewed with a microscope. Conventionally, this roundness is the cutting edge 16a and R is less than 0.1 mm, but the value of R1 of the cutting edge of the present invention is 0.3 to 0.7 mm, which is larger than the conventional one. This is because if the value of R1 is less than 0.3 mm, the thickness becomes thin and it is easy to bend. This is because if the value of R1 exceeds 0.7 mm, a desired sharpness cannot be obtained.

  In addition, the value of the radius R2 of the tip portion of the edge 15 has been a straight line in the past, but in the present invention, by continuing polishing after deburring, R2 = 100 to as shown in the figure with the center protruding. It has a 500 mm arc shape or a curve close to an arc shape. The central protruding warp shown in R2 is also caused by electrolytic polishing, but the sharpness of the knife can be improved by making such a warp. In particular, since the straight knife 10 uses a portion about 1 mm from the blade edge 16a, the sharpness of the blade edge portion 16 can be improved by warping the portion. In addition, as shown to Fig.2 (a), it is good also as a structure which provides curvature also about the maximum width | variety of the blade part 12. FIG. When electrolytic polishing or chemical polishing is applied to the entire length of the cutting edge 14, warpage is also formed near the maximum width. The reason why R2 is not less than 100 mm is that when it is less than 100 mm, the amount of polishing is too large and the sharpness is lowered. On the other hand, the upper limit of R2 is preferably set to 500 mm or less because the cross-sectional angle (blade angle) of the blade is apparently reduced when it is cut. This is because the effect of reducing the cross-sectional angle of the blade is almost lost when it exceeds 500 mm.

  When the grinding process for forming the inclined surface 13 is performed with a wrapping film, the blade 12 is warped by the processing pressure during the grinding process, and a central protruding warp indicated by R2 in FIG. 2 can be easily formed. Moreover, the front end side and the shank side of the inclined surface 13 are convex curved surfaces, and the inclination angle of the inclined surface 13 is increased. When electrolytic polishing or chemical polishing similar to the above is performed in this state, the cutting edge 14 is formed by following the central protruding shape as it is, and both end portions having a large angle are polished less, and the central portion having a small angle is Since a large amount of polishing is performed, a uniform cutting edge angle can be formed as a whole.

  In FIG. 2 (b), the cutting edge 16a is an arc, but in reality, there may be some unevenness and the arc may not be as beautiful as this. Therefore, “rounded” in the present invention includes various curved surfaces such as an elliptical arc surface other than an arc, a paraboloid, and the like, and includes a convex curved surface including some irregularities.

  Although the cutting edge is conventionally sharp as shown by the dotted line in FIG. 2B, it is rounded like the cutting edge 16a shown by the solid line, but the convex curved surface is also small as described above, and there is no burr. Therefore, the sharpness is improved, and the total sharpness is the same as that before the electrolytic polishing treatment. On the other hand, with the conventional sharp blade edge 16a, when the cornea or sclera is incised as described in FIG. 5D, the blade edge portion 16 was easy to bend, but the cutting edge made of the convex curved surface of the present invention. The cutting edge 16 at the tip of the blade 14 can be incised without bending, and the incision operation can be performed reliably and easily.

Fig.3 (a) is a figure corresponding to FIG.5 (b), and is the BB sectional drawing of FIG.2 (b). An inclined surface 13 and an edge 15 ′ formed by grinding are shown. A cutting edge 14 having a convex curved surface is formed between the inclined surface 13 and the polished edge 15 by electrolytic polishing or chemical polishing. The cutting edge 14 is approximately an arc surface and has a central axis in the length direction of the inclined surface 13. With such a configuration, the cutting edge 14 can easily enter the body tissue, and the sharpness can be improved.

  The above description has been made with the knife in which the inclined surface 13 and the cutting edge 14 are formed symmetrically on both surfaces of the blade portion 12, but the knife in which the inclined surface 13 and the cutting blade 14 are formed only on one surface of the blade portion 12. But the same is true. Although the straight knife has been described as an example, the present invention can also be applied to other medical knives such as an LRI knife for correcting astigmatism.

  4A and 4B are diagrams of an LRI knife for correcting astigmatism, in which FIG. 4A is a plan view, FIG. 4B is a cross-sectional view taken along the line C-C in FIG. It is a figure which shows the state after grinding | polishing. (D) is a figure which shows the state before electrolytic polishing of the DD sectional view taken on the line of (a), (e) is a figure which shows the state after electrolytic polishing.

  The LRI knife 40 has a V-shaped pointed blade portion 41 whose tip is close to 90 °, and inclined surfaces 42 are formed on two sides constituting the V-shape of the tip. Edges of the inclined surface 42 are sharp edges 43 and 43. The point where the two edges 43 intersect is the cutting edge 45.

When the inclined surface 42 and the edge 43 ′ are formed on the blade portion 41 by grinding, the LRI knife 40 has a cross-sectional shape as shown in (b) and (d). By being polished, cross-sectional shapes such as (c) and (e) are obtained.

  That is, a cutting edge 44 made of a convex curved surface is formed on the tip side of the inclined surface 42, and an edge 43 is formed on the tip. However, the blade edge 45 is not rounded like the straight knife 10 shown in FIG. 2B on the plan view shown in FIG. This is because if the LRI knife 40 is originally a thick knife, the V-shaped angle is large, and the cutting blade 44 made of a convex curved surface is formed, the problem of bending is not necessary even if the cutting edge 45 is rounded. It doesn't happen. But the blade edge | tip 45 may be round on a top view as shown in FIG.2 (b).

  Tables 1 and 2 are examples in which the sharpness of the straight knife 10 of the present invention is compared with that of a conventional straight knife. Table 1 investigated 10 samples 1 to 10 with the straight knife of the present invention. Table 2 investigates two samples 11 and 12 with a straight knife made of conventional martensitic stainless steel. Both the straight knife of the present invention and the conventional straight knife have the same shape with a blade angle of 15 ° and a plate thickness (value of t) of 0.11 mm. The test method is measured by the piercing force (unit: “mN” millinewton) when a 0.45 mm thick artificial leather (pole bear) with hardness similar to cornea and sclera is pierced with a straight knife. did.

  Table 1 shows the straight knife of the present invention, and the piercing test was performed three times for 10 samples. As a result, there was no one where the blade edge portion was bent, and all of them could be pierced. Further, the piercing resistance is slightly improved compared to the conventional straight martensitic stainless steel knife.

  From the above, according to the present invention, it was found that the straight knife can be manufactured from austenitic stainless steel, and the sharpness is not inferior to that of the conventional one.

In the above embodiment, the electrolytic polishing process is used, but a chemical polishing process may be used. However, since the roundness of the cutting edge 16a of the cutting edge 14 shown in FIG. 1 ( h ) is small, it is not possible to form such a roundness of the small cutting edge 16a of R by grinding. Roundness that can be formed only by electrolytic polishing or chemical polishing.

DESCRIPTION OF SYMBOLS 10 Straight knife 11 Round bar 12 Blade part 13 Inclined surface 14 Cutting blade 15 Cutting edge 16 Cutting edge part 16a Cutting edge 17 Curved surface

Claims (1)

Crushing the tip side of the round bar of austenitic stainless steel flat, cutting the excess part with a press to form a flat blade part;
Forming an inclined surface and an edge along at least a peripheral edge of the blade portion by grinding;
Take the burr of the inclined surface and the edge by electrolytic polishing or chemical polishing, further electrolytic polishing or continued chemical polishing, and cutting edge cross-sectional shape consisting of a convex curved surface at the tip portion of the inclined surface, the edges Forming a polished edge that maintains the shape of the edge at the edge of the polished cutting edge; and
The manufacturing method of the straight knife characterized by having.

Images