JPH09276284A - Medical knife - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical knife having an uniform strength and free from rusting by forming a round bar-like shank, a blade part continued to the shank, and a cutting edge in a desired part of the blade part by use of an austenite stainless steel having a fibrously extended tissue. SOLUTION: A crescent knife has a spatula-like blade part 1 on the tip of a shank 3, a cutting edge, 2 is formed on the circumference of the blade part 1, and the rear end of the shank 3 is mounted on a handle. A recessed surface part 1a is formed substantially on the center part of both upper and lower surfaces of the blade part 1 along the axial direction of the crescent knife, and the blade part 1 and the shank 3 are integrally formed by use of austenite stainless steel. Since the austenite stainless steel represented by 18-8 stainless steel can not be hardened by thermal treatment, it made into a fibrous tissue, whereby a prescribed hardness is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical knife used for surgery and the like, and more particularly to a medical knife used for cutting cornea, sclera and the like in surgery such as ophthalmology.

[0002]

2. Description of the Related Art A knife used for incision in ophthalmic surgery is a golf sword or Paufique sword used for semilayer incision of the sclera or delamination of the cornea, and a scleral tunnel for small incision cataract surgery. There are circular swords, crescent knives, etc. used to make them.

Not only in ophthalmic knives, but also in medical knives, not to destroy the tissue of the cut surface accurately,
Precise and sharp cutting is required. Generally, the sharpness of a knife depends on the hardness of the blade portion, and the higher the hardness, the better the sharpness and the durability. Therefore, conventionally, a predetermined hardness is obtained by subjecting martensitic stainless steel to heat treatment to harden it.

[0004]

However, it is difficult to uniformly heat the whole body in the quenching process, and the quenching method largely depends on the cooling rate. Due to the difficulty of temperature control, quality problems such as hardness change depending on the part occur in mass production.

Each of these medical knives is sterilized by being subjected to steam sterilization (sterilization at 121 to 126 degrees for 15 to 20 minutes) each time it is used for treatment, and then used again. Then, since it is composed of martensitic stainless steel as a material, there is a problem that rust is generated unless rust-proof treatment is sufficiently performed after sterilization treatment.

Therefore, it is conceivable to use austenitic stainless steel, which is excellent in corrosion resistance, as a material. However, since austenitic stainless steel cannot be quenched and hardened by heat treatment, it cannot obtain sufficient hardness as a knife.

An object of the present invention is to provide a medical knife made of austenitic stainless steel which has uniform strength, does not cause rust, and has hardness equivalent to that of hardened steel or martensitic stainless steel. To provide.

[0008]

In order to solve the above problems, a medical knife according to the present invention comprises an austenitic stainless steel having a fiber-stretched structure, a round bar-shaped shank and a continuous shank. And a cutting blade formed at a predetermined portion of the blade portion.

With the above structure, a medical knife having a desired hardness can be formed using austenitic stainless steel.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A crescent knife used in ophthalmic surgery will be described as an example of a medical knife according to the present invention with reference to the drawings. FIG. 1 is an overall view of a crescent knife according to an embodiment of the present invention, FIG. 2 is an enlarged view and a sectional view of a blade portion, and FIG. 3 is a diagram illustrating a process of forming the blade portion.

As shown in FIGS. 1 and 2, the crescent knife a has a spatula-shaped blade portion 1 at the tip of a shank 3, and a cutting blade 2 is formed on the outer periphery of the blade portion 1. The rear end of the shank 3 is attached to the handle 4 so that an operator can grip it.

As can be seen from the cross section AA of the blade portion 1 shown in FIG. 2, a concave surface portion 1a is formed along the axial direction of the crescent knife a at substantially the center of both upper and lower surfaces of the blade portion. . Further, one surface of the blade portion is ground and polished to a flat surface, and the other surface is ground and polished to have an inclined surface on the outer periphery thereof to form a cutting edge. Such a single-edged structure allows the living tissue to be cut accurately. Further, the shank 3 is formed in a round bar shape as shown in the section BB.

The blade portion 1 and the shank 3 are integrally formed of austenitic stainless steel. 1
Since austenitic stainless steel represented by 8-8 stainless steel cannot be quenched and hardened by heat treatment,
A predetermined hardness is obtained by forming a fibrous structure.

When manufacturing the medical knife according to the present invention, first, an austenitic stainless steel wire rod is cold-drawn at a predetermined surface reduction rate. Then, the metal structure undergoes transformation and hardens by work hardening, and it is elongated and elongated in the axial direction to form a fibrous structure, improving bending strength and hardness, and exhibiting uniform strength throughout the whole. You can Further, it is possible to set a predetermined strength and hardness by appropriately setting the surface reduction rate.

The round bar formed by cold drawing as described above is cut into a predetermined length to form a raw material, one end of which is used as a shank and the other end is formed into a flat surface by pressing to form a prototype of the blade portion. Form. That is, the shank and the blade portion have a continuous fibrous structure, and thus have high toughness and hardness.

FIG. 3 shows a step of forming the blade portion and the cutting blade. First, FIG. 3 (a) shows a material obtained by cutting the stretched wire rod into a predetermined length. The blade portion is formed by pressing the tip portion of the material, but if a flat press die is used here, the stress applied to the contact portion of the die is high and the die may be cracked.
Therefore, as shown in FIG. 3 (b), press working is performed using a convex press die.

By pressing with the convex mold in this manner, the metal structure easily flows to the outside and the stress easily escapes. Therefore, the blade of the press can be easily pressed without cracking the press die, and the durability of the press die can be improved. Further, the low hardness portion left in the central portion of the wire can be efficiently work-hardened, and the sharpness is improved because the contact area with the biological tissue surface is reduced during surgery.

The round bar-shaped material obtained by cold drawing has a concentric hardness distribution. That is, the hardness of the surface is the highest, and the hardness tends to gradually decrease toward the center. However, if cold pressing is performed, the deformation in the center becomes the largest, and work hardening can occur in the center as well, and the hardness of the material can be made uniform. Note that the formed fibrous structure is not lost by performing the press working in the cold.

Next, as shown in FIG. 3 (c), one surface of the blade portion of the intermediate material 6 formed by press molding is ground and polished to a flat surface, and the outer periphery of the other surface is ground to an inclined surface. The cutting edge 2 is formed by polishing.

Further, in the work of forming the blade portion as described above, since the shank is a round bar, the gripping property is good, and the work such as pressing, grinding and polishing is easy. Further, even in the patterning process, the work can be facilitated, and the pattern can be used as a separate disposable knife.

In the present embodiment, the crescent knife was used for explanation, but the present invention is applied to all knives whose dimensions are so small that a cold-drawn wire rod can be used as a raw material. It goes without saying that you can do it.

Further, as shown in the above embodiment, when pressing is performed using a convex mold, both the press mold and the material form a convex cylindrical surface, so that the centers of the molds may deviate from each other. Conceivable. In such a case, the pressing process may be divided into two stages, the pressing may be performed in advance using a flat die, and then the pressing may be performed to a desired thickness using a convex die.

[0023]

As described above, since the medical knife according to the present invention uses austenitic stainless steel as a material, it does not cause rust even after repeated use and steam sterilization treatment, and is always A clean state can be maintained.

Further, by extending the metallographic structure of austenitic stainless steel into a fiber shape along the longitudinal direction, it is possible to provide a high toughness and hardness in spite of being austenitic stainless steel and to exhibit a desired sharpness. You can In addition, since the blade part is formed to a predetermined hardness by work hardening, it is possible to exert uniform and stable strength as compared with an object whose hardness is increased by heat treatment, and the surface is stably set to a predetermined hardness. The strength can be improved while being cured.

[Brief description of drawings]

FIG. 1 is an overall view of a crescent knife according to an embodiment of the present invention.

FIG. 2 is an enlarged view and a sectional view of a blade portion.

FIG. 3 is a diagram illustrating a step of forming a blade portion.

[Explanation of symbols]

 a ... Crescent knife AA ... blade section BB ... shank section 1 ... blade section 1a ... concave section 2 ... cutting edge 3 ... shank 4 ... handle 5 ... wire 6 ... intermediate material 10 ... press

Claims (1)

[Claims] 1. A rod-shaped shank made of austenitic stainless steel having a fiber-stretched structure, a blade portion formed continuously with the shank, and a cut formed at a predetermined portion of the blade portion. A medical knife having a blade.