A method for ion nitriding of an austenitic stainless steel medical suture needle

Abstract

The application relates to the field of medical suture needle surface treatment technology, in particular to a processing method for ion nitriding of an austenitic stainless steel medical suture needle, wherein the S4-processed medical suture needle is placed at a cathode plate of an ion nitriding furnace, an anode plate covers the needle tip of the medical suture needle, the ion nitriding furnace is set to a voltage of 550 V and an air pressure of 300 Pa, nitriding is carried out for 1 hour, the temperature is controlled between 350 DEG C and 430 DEG C according to the size of the medical suture needle, the process gas ratio adopts two ratios of N2:H2=1:9 or N2:H2=1:3, and the surface hardness of the nitriding layer of the medical suture needle is HV750-1200. In the application, the anode plate covers the needle tip of the medical suture needle, a plasma zone is formed between the needle tip of the medical suture needle and the anode plate, nitrogen ions are high-speed bombarded on the surface of the needle tip under the action of an electric field and are penetrated into the surface, rapid nitriding of the needle tip part is achieved, the hardness and puncture sharpness of the needle tip are improved, and the needle body and the needle tail have lower hardness and higher toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical suture needle surface treatment technology, in particular to an austenitic stainless steel medical suture needle ion nitriding processing method. BACKGROUND

[0002] Medical stainless steel has become a widely used medical implant material and medical tool material in clinical application due to its good biocompatibility, mechanical properties, body fluid corrosion resistance, excellent processing performance and low cost. The medical suture needle is a very common and frequently used instrument in surgical operations, and the medical suture needle is usually made of a needle tail drilled or slotted with stainless steel as the raw material.

[0003] Medical suture needle stainless steel mainly includes martensitic stainless steel and austenitic stainless steel. The austenitic stainless steel has an austenitic structure at room temperature, and such structure and properties have a small response to temperature change, no magnetism, excellent corrosion resistance, weldability, good toughness and biocompatibility. However, the austenitic stainless steel cannot be strengthened by phase change, and the carbon content is lower than 0.03%, so the solid solution strengthening effect is low. Therefore, the hardness (HV200-250) and strength (500-800MPa) of the austenitic stainless steel in the solid solution treatment state are low, and it is difficult to meet the performance requirements of high strength, high hardness and high sharpness of the medical suture needle.

[0004] At present, the method for improving the hardness and sharpness of the austenitic medical suture needle is mainly to work harden the raw material wire, and to improve the hardness to HV600 and the strength to 1500-1800MPa by cold drawing large plastic deformation, which is beneficial to the high strength, high hardness and high sharpness required by the medical suture needle. However, the high hardness (≥HV480) of the medical suture needle will cause difficulties in subsequent mechanical processing of the medical suture needle, such as bending and needle hole processing, and the high hardness of the medical suture needle will cause a sharp decrease in its plasticity and toughness, thereby increasing the tendency of brittle fracture of the medical suture needle. SUMMARY

[0005] In order to improve the hardness and sharpness of the medical suture needle, the present application provides an austenitic stainless steel medical suture needle ion nitriding processing method.

[0006] The austenitic stainless steel medical suture needle ion nitriding processing method provided by the present application adopts the following technical scheme:

[0007] An austenitic stainless steel medical suture needle ion nitriding processing method, comprising the following steps:

[0008] S1. Forming a medical suture needle, an austenitic stainless steel wire is first cold drawn to a required different diameter specification and a hardness of HV330-380, and the austenitic stainless steel wire is sequentially formed into a medical suture needle through processes of uncoiling, straightening, cutting, needle hole processing and needle tip processing, and the medical suture needle is straight;

[0009] S2. Needle tip finishing, the medical suture needle formed in S1 is subjected to needle tip finishing to achieve a sharp needle tip without a false tip;

[0010] S3. Medical suture needle polishing, the medical suture needle processed in S2 is subjected to chemical or electrochemical surface polishing treatment;

[0011] S4. Medical suture needle cleaning and drying, the medical suture needle processed in S3 is cleaned and then dried;

[0012] S5. Needle tip ion nitriding, the medical suture needle processed in S4 is placed at a cathode plate of an ion nitriding furnace, and an anode plate is moved to cover the needle tip of the medical suture needle, the ion nitriding furnace is set at a voltage of 550V and a gas pressure of 300Pa for nitriding for 1 hour, the temperature is controlled between 350-430℃ according to the size of the medical suture needle, the process gas ratio is N2:H2=1:9 or N2:H2=1:3, and the medical suture needle is taken out after ion nitriding and air cooling to obtain a nitriding layer with a surface hardness of HV750-1200;

[0013] S6. Medical suture needle cleaning and drying, the medical suture needle processed in S5 is cleaned with water and then dried;

[0014] S7. Medical suture needle bending, the medical suture needle processed in S6 is bent according to requirements to achieve a medical suture needle with a required 1 / 2 arc, 3 / 8 arc or 5 / 8 arc shape;

[0015] S8. Medical suture needle cleaning and drying, the medical suture needle processed in S7 is cleaned with water and then dried.

[0016] By adopting the technical scheme, firstly, the treatment temperature of the ion nitriding furnace in S5 is controlled between 350 DEG C and 430 DEG C according to the size of the medical suture needle, so as to avoid the hardness reduction caused by the processing strengthening of the austenitic stainless steel wire formed by cold drawing, and to control the nitriding depth of the medical suture needle, so as to avoid the complete nitriding of the needle tip of the medical suture needle, and the internal hardness of the nitrided medical suture needle is kept at HV330-380, which is beneficial to keeping the hardness, sharpness and toughness of the medical suture needle. After the nitriding treatment, the hardness of the needle tip part is increased from HV330-380 to HV750 or above, even to HV1200. With the increase of the hardness of the needle tip part of the medical suture needle, the required piercing force is reduced. According to the provisions in the medical industry standard (YY / T 0043-2016) of the People's Republic of China, the required piercing force of the triangular suture needle with a diameter of 0.6 mm should be less than or equal to 0.58 N, and the required piercing force of the ion nitrided medical suture needle of the same specification is only 0.18 N, which is much better than the industry standard. Secondly, the hardness and toughness of the needle tip core and the needle body tail are kept at HV330-380, so as to realize the high hardness and high sharpness of the needle tip part of the medical suture needle, and the toughness and elasticity of the needle body and the needle tail, so as to solve the contradiction between the high hardness and the high toughness of the medical suture needle. Thirdly, the lower hardness and higher toughness of the needle body and the needle tail improve the processability of the austenitic stainless steel medical suture needle in bending and needle hole forming, and reduce the damage of the high-hardness austenitic stainless steel medical suture needle to the processing equipment. Finally, the ion nitriding will introduce a certain proportion of nitrogen element into the stainless steel medical suture needle, form a chromium nitride layer, prevent intergranular corrosion, and inhibit the excessive passivation and dissolution of chromium and other elements, so that the stainless steel medical suture needle has stronger corrosion resistance.

[0017] Optionally, the cathode plate in the S5 step has a plurality of positioning holes for embedding the needle tail of the medical suture needle, the outer peripheral surface of the needle tail abuts against the inner wall of the positioning hole to form a limit, the inner wall of the positioning hole is flared towards the direction close to the axis of the positioning hole, the anode plate has a plurality of nitriding holes for embedding the needle tip of the medical suture needle, the inner wall of the nitriding hole is flared towards the direction close to the axis of the nitriding hole, and the inner wall of the nitriding hole surrounds the outer peripheral surface of the needle tip.

[0018] By adopting the technical scheme, the needle tail of the medical suture needle is embedded into the positioning hole, the outer circumferential surface of the medical suture needle abuts against the inner wall of the positioning hole to form limiting, the positioning of the medical suture needle on the cathode plate is realized, meanwhile, the inner wall of the positioning hole is flared towards the direction close to the axis of the positioning hole, so that the cathode plate can meet the placement requirement of medical suture needles with different diameters, the anode plate is moved, the needle tip of the medical suture needle is embedded into the nitriding hole, the inner wall of the nitriding hole surrounds the outer circumferential surface of the needle tip of the medical suture needle, when the nitriding furnace is operated, the plasma area is formed between the outer circumferential surface of the needle tip and the inner wall of the nitriding hole, the furnace body serves as an anode, the medical suture needle serves as a cathode, there is several hundred volts of direct current voltage between the two, the hydrogen and nitrogen in the furnace body glow discharge, so that the plasma is formed, the nitrogen molecules are ionized under the bombardment of high-energy electrons, nitrogen atoms and nitrogen ions are formed, and the nitrogen atoms and the nitrogen ions move at high speed to the needle tip of the medical suture needle under the action of the electric field and chemically react with the carbon atoms on the surface of the needle tip of the medical suture needle to form nitrides, the nitrides form a dense nitriding layer on the surface of the needle tip of the medical suture needle, so that the hardness, wear resistance and corrosion resistance of the surface of the needle tip of the medical suture needle are improved, in the process of plasma nitriding, the nitrogen ions and hydrogen ions bombard and sputter at high speed to the surface of the needle tip of the medical suture needle, which not only helps the diffusion and penetration of the nitrogen atoms, but also removes the impurities such as oil stains and oxides on the surface of the needle tip of the medical suture needle to realize the surface purification; meanwhile, in the process of nitriding, the needle tip of the medical suture needle is bombarded by high-energy nitrogen ions, the nitrogen ions convert kinetic energy into heat energy to heat the workpiece, and this heating mode is more uniform and efficient than the traditional external heating; in the process of bombarding the surface of the suture needle, cathode sputtering is also generated, iron ions and nitrogen ions are sputtered out to form iron nitride, the compound is reattached to the surface of the workpiece, and then decomposed into Fe2N and Fe3N, and nitrogen atoms are released to diffuse into the workpiece to realize nitriding, which has higher efficiency and better treatment effect, not only can significantly improve the surface hardness, wear resistance and fatigue strength of the austenitic stainless steel medical suture needle, but also can keep the basic shape and size of the medical suture needle unchanged, so as to greatly prolong the service life of the medical suture needle.

[0019] Optionally, the nitriding furnace treatment temperature in the S5 step is set to 350℃, the process gas ratio is N2:H2=1:9, and the medical suture needle is taken out after air cooling, so that the nitriding layer depth of the medical suture needle is 6±2μm and the surface hardness is HV780±30.

[0020] By adopting the technical scheme, when the nitriding furnace treatment temperature is set to 350℃ and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle is 6±2μm and the surface hardness is HV780±30, the hardness and sharpness of the needle tip of the medical suture needle are improved, meanwhile, the needle body and the needle tail of the medical suture needle still have relatively low hardness and high toughness, the bending resistance of the needle body of the medical suture needle is significantly improved, the problem of difficult machining of the needle hole of the medical suture needle is reduced, and the requirements for the machining equipment and the wear of the machining die are reduced.

[0021] Optionally, the nitriding furnace treatment temperature in the S5 step is set to 370 DEG C, the process gas ratio is N2:H2=1:9, and after nitriding, the air cooling is taken out, so that the nitriding layer depth of the medical suture needle is 9+ / -2 mu m, and the surface hardness is HV890+ / -30.

[0022] By adopting the above technical scheme, when the nitriding furnace treatment temperature is set to 370 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle can be 9+ / -2 mu m, and the surface hardness is HV890+ / -30, so that the precise processing of the medical suture needle is realized.

[0023] Optionally, the nitriding furnace treatment temperature in the S5 step is set to 400 DEG C, the process gas ratio is N2:H2=1:9, and after nitriding, the air cooling is taken out, so that the nitriding layer depth of the medical suture needle is 13+ / -2 mu m, and the surface hardness is HV1010+ / -30.

[0024] By adopting the above technical scheme, when the nitriding furnace treatment temperature is set to 400 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle can be 13+ / -2 mu m, and the surface hardness is HV1010+ / -30, so that the precise processing of the medical suture needle is realized.

[0025] Optionally, the nitriding furnace treatment temperature in the S5 step is set to 430 DEG C, the process gas ratio is N2:H2=1:9, and after nitriding, the air cooling is taken out, so that the nitriding layer depth of the medical suture needle is 17+ / -2 mu m, and the surface hardness is HV1110+ / -30.

[0026] By adopting the above technical scheme, when the nitriding furnace treatment temperature is set to 430 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle can be 17+ / -2 mu m, and the surface hardness is HV1110+ / -30, so that the precise processing of the medical suture needle is realized.

[0027] Optionally, the nitriding furnace treatment temperature in the S5 step is set to 350 DEG C, the process gas ratio is N2:H2=1:3, and after nitriding, the air cooling is taken out, so that the nitriding layer depth of the medical suture needle is 11+ / -2 mu m, and the surface hardness is HV830+ / -30.

[0028] By adopting the above technical scheme, when the nitriding furnace treatment temperature is set to 350 DEG C and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle can be 11+ / -2 mu m, and the surface hardness is HV830+ / -30, so that the precise processing of the medical suture needle is realized.

[0029] Optionally, the nitriding furnace treatment temperature in S5 is set to 370℃, the process gas ratio is N2:H2=1:3, and after nitriding, the needle is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle is 14±2μm, and the surface hardness is HV950±30.

[0030] By adopting the above technical solution, when the nitriding furnace treatment temperature is set to 370℃ and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle is 14±2μm, and the surface hardness is HV950±30, achieving precise processing of the medical suture needle.

[0031] Optionally, the nitriding furnace treatment temperature in S5 is set to 400℃, the process gas ratio is N2:H2=1:3, and after nitriding, the needle is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle is 19±2μm, and the surface hardness is HV1080±30.

[0032] By adopting the above technical solution, when the nitriding furnace treatment temperature is set to 400℃ and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle is 19±2μm, and the surface hardness is HV1080±30, achieving precise processing of the medical suture needle.

[0033] Optionally, the nitriding furnace treatment temperature in S5 is set to 430℃, the process gas ratio is N2:H2=1:3, and after nitriding, the needle is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle is 23±2μm, and the surface hardness is HV1190±30.

[0034] By adopting the above technical solution, when the nitriding furnace treatment temperature is set to 430℃ and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle is 23±2μm, and the surface hardness is HV1190±30, achieving precise processing of the medical suture needle.

[0035] In summary, the present application includes at least one of the following beneficial technical effects:

[0036] 1. The anode plate covers the needle tip of the medical suture needle, and an ionization zone is formed between the needle tip of the medical suture needle and the anode plate, so that nitrogen ions can penetrate into the surface of the needle tip under the action of the electric field, achieving rapid nitriding of the needle tip to improve the hardness and puncture sharpness of the needle tip, while not reducing the hardness and increasing the toughness of the needle body and needle tail;

[0037] 2. The positioning hole and the nitriding hole are arranged, and the axis of the positioning hole is in an expanded shape, so that the cathode plate can meet the placement requirements of medical suture needles of different diameters, significantly improving the surface hardness, wear resistance and fatigue strength of the austenitic stainless steel medical suture needle, and also maintaining the basic shape and size of the medical suture needle unchanged, thereby greatly prolonging the service life of the medical suture needle.

[0038] 3. The nitriding furnace processing temperature is set to 350℃ and the process gas ratio is N2:H2=1:9. The hardness and sharpness of the needle tip of the medical suture needle are improved, while the needle body and needle tail of the medical suture needle still maintain lower hardness and higher toughness. The bending resistance of the medical suture needle body is significantly improved, the problem of difficult processing of the medical suture needle hole is reduced, and the requirements for processing equipment and the wear of processing molds are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is the overall structure schematic diagram in embodiment 1 of the present application.

[0040] Figure 2 is the partial sectional view in embodiment 1 of the present application, mainly showing the positioning hole.

[0041] Figure 3 is the partial sectional view in embodiment 1 of the present application, mainly showing the nitriding hole.

[0042] BRIEF DESCRIPTION OF DRAWINGS 1. Cathode plate; 11. Positioning hole; 2. Anode plate; 21. Nitriding hole; 3. Medical suture needle. DETAILED DESCRIPTION

[0043] The following will be described in detail in combination with the accompanying drawings. Figures 1-3 The present application will be further described in detail.

[0044] The embodiment of the present application discloses a processing method for ion nitriding of an austenitic stainless steel medical suture needle. The present application is suitable for all austenitic stainless steels. In the embodiment of the present application, the material of the austenitic stainless steel is 304 stainless steel. The hardness of the stainless steel can be divided into multiple grades according to its processing state and heat treatment process, such as soft state, 1 / 4 hard state, half hard state, 3 / 4 hard state and hard state, etc. In the embodiment of the present application, the hardness of the raw steel wire of the austenitic stainless steel medical suture needle 3 is half hard state (HV330-380), so that the medical suture needle 3 has good bending and needle hole machining processability.

[0045] Embodiment 1

[0046] A processing method for ion nitriding of an austenitic stainless steel medical suture needle, comprising the following steps:

[0047] S1. Forming the medical suture needle 3, the austenitic stainless steel wire is first cold drawn to the required different diameter specifications and the hardness is HV330-380. In the embodiment of the present application, the austenitic stainless steel wire is cold drawn to a hardness of HV360. The austenitic stainless steel wire is sequentially subjected to processes such as uncoiling, straightening, cutting, needle hole processing and needle tip processing to form the medical suture needle 3, and the medical suture needle 3 is straight.

[0048] S2. Needle tip finishing, the needle tip of the medical stitching needle 3 processed in S1 is finished to achieve a sharp needle tip without a blunt tip;

[0049] S3. Medical stitching needle 3 polishing, the chemical (ordinary pickling) or electrochemical surface polishing treatment of the medical stitching needle 3 processed in S2 is completed;

[0050] S4. Medical stitching needle 3 cleaning and drying, the medical stitching needle 3 processed in S3 is cleaned and then dried;

[0051] S5. Needle tip ion nitriding, the medical stitching needle 3 processed in S4 is placed on the cathode plate 1 of the ion nitriding furnace, and the anode plate 2 is moved to cover the needle tip of the medical stitching needle 3. The parameters of the ion nitriding furnace are adjusted to a voltage of 550 V, a gas pressure of 300 Pa, and an auxiliary temperature of 300 ℃, and the medical stitching needle 3 is nitrided for 1 hour. The temperature is controlled between 350 ℃ and 430 ℃ according to the size of the medical stitching needle 3. The process gas ratio is N2:H2=1:9 or N2:H2=1:3. After nitriding, the medical stitching needle 3 is taken out and air-cooled. The surface hardness of the medical stitching needle 3 is HV750~1200. In the embodiment of the application, the treatment temperature is 350 ℃ and the process gas ratio is N2:H2=1:9. The surface hardness of the medical stitching needle 3 detected is HV780±30, and the nitriding layer depth of the medical stitching needle 3 is 6±2 μm;

[0052] S6. Medical stitching needle 3 cleaning and drying, the medical stitching needle 3 processed in S5 is cleaned with water and then dried;

[0053] S7. Medical stitching needle 3 bending, the medical stitching needle 3 processed in S6 is bent according to the requirements to achieve a medical stitching needle 3 with a required 1 / 2 arc, 3 / 8 arc, or 5 / 8 arc shape;

[0054] S8. Medical stitching needle 3 cleaning and drying, the medical stitching needle 3 processed in S7 is cleaned with water and then dried;

[0055] Referring to Figure 1 and Figure 2 The plate surface of the cathode plate 1 in the S5 step facing the anode plate 2 has a plurality of positioning holes 11 for embedding the needle tail of the medical stitching needle 3. The inner wall of the positioning hole 11 abuts against the outer peripheral surface of the needle tail to form a limit, so as to realize the positioning of the medical stitching needle 3 on the cathode plate 1. At the same time, the inner wall of the positioning hole 11 is flared towards the direction close to the axis of the positioning hole 11, so that the cathode plate 1 can adapt to the limiting of medical stitching needles 3 with different diameters, thereby improving the universality of the use of the nitriding furnace.

[0056] Referring to Figure 1 and Figure 3The plate surface of the anode plate 2 in the S5 step faces the cathode plate 1 and has a plurality of nitriding holes 21 for embedding the needle tip of the medical suture needle 3, the nitriding holes 21 correspond to the positioning holes 11 one by one, the inner wall of the nitriding hole 21 is flared towards the direction close to the axis of the nitriding hole 21, and the nitriding hole 21 inner wall surrounds the needle tip outer peripheral surface, and the plasma zone is formed between the needle tip outer peripheral surface and the nitriding hole 21 inner wall during the operation of the nitriding furnace, and the nitrogen ions bombard the needle tip surface at high speed under the action of the electric field, so as to achieve the purpose of local nitriding of the needle tip of the medical suture needle 3.

[0057] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding of the embodiment 1 is that the austenitic stainless steel suture needle is divided into a needle tip, a needle body and a needle tail, and the ion nitriding can be locally nitrided, so that the needle tip part of the medical suture needle 3 is nitrided, and the hardness of the needle tip is improved, while the elasticity and toughness of the needle body and the needle tail are maintained, so as to improve the processability of the austenitic stainless steel medical suture needle 3 bending and needle hole forming, and reduce the damage of the high-hardness austenitic stainless steel medical suture needle 3 to the processing equipment.

[0058] Embodiment 2

[0059] The difference between the embodiment 2 and the embodiment 1 is that the treatment temperature of the ion nitriding furnace in S5 is set to 370 DEG C, the process gas ratio is N2:H2=1:9, and the medical suture needle 3 is taken out and air-cooled after nitriding, the nitriding layer depth of the medical suture needle 3 is detected as 9±2μm, and the surface hardness is HV890±30.

[0060] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding of the embodiment 2 is that when the treatment temperature of the nitriding furnace is set to 370 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle 3 is 9±2μm, and the surface hardness is HV890±30, so that the medical suture needle 3 can be accurately processed according to the actual use requirement.

[0061] Embodiment 3

[0062] The difference between the embodiment 3 and the embodiment 1 is that the treatment temperature of the ion nitriding furnace in S5 is set to 400 DEG C, the process gas ratio is N2:H2=1:9, and the medical suture needle 3 is taken out and air-cooled after nitriding, the nitriding layer depth of the medical suture needle 3 is detected as 13±2μm, and the surface hardness is HV1010±30.

[0063] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 3 of the application is that when the processing temperature of the ion nitriding furnace is set to 400 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle 3 can be 13+ / -2 microns, the surface hardness can be HV1010+ / -30, and the medical suture needle 3 can be precisely processed according to actual use requirements.

[0064] Embodiment 4

[0065] The difference between the embodiment 4 and the embodiment 1 is that the processing temperature of the ion nitriding furnace in S5 is set to 430 DEG C, the process gas ratio is N2:H2=1:9, and after nitriding, the medical suture needle 3 is taken out and air-cooled, the nitriding layer depth of the medical suture needle 3 is detected to be 17+ / -2 microns, and the surface hardness is HV1110+ / -30.

[0066] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 4 of the application is that when the processing temperature of the ion nitriding furnace is set to 430 DEG C and the process gas ratio is N2:H2=1:9, the nitriding layer depth of the medical suture needle 3 can be 17+ / -2 microns, the surface hardness can be HV1110+ / -30, and the medical suture needle 3 can be precisely processed according to actual use requirements.

[0067] Embodiment 5

[0068] The difference between the embodiment 5 and the embodiment 1 is that the processing temperature of the ion nitriding furnace in S5 is set to 350 DEG C, the process gas ratio is N2:H2=1:3, and after nitriding, the medical suture needle 3 is taken out and air-cooled, the nitriding layer depth of the medical suture needle 3 is detected to be 11+ / -2 microns, and the surface hardness is HV830+ / -30.

[0069] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 5 of the application is that when the processing temperature of the ion nitriding furnace is set to 350 DEG C and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle 3 can be 11+ / -2 microns, the surface hardness can be HV830+ / -30, and the medical suture needle 3 can be precisely processed according to actual use requirements.

[0070] Embodiment 6

[0071] The difference between the embodiment 6 and the embodiment 1 is that the processing temperature of the ion nitriding furnace in S5 is set to 370 DEG C, the process gas ratio is N2:H2=1:3, and after nitriding, the medical suture needle 3 is taken out and air-cooled, the nitriding layer depth of the medical suture needle 3 is detected to be 14+ / -2 microns, and the surface hardness is HV950+ / -30.

[0072] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 6 of the application is that: when the processing temperature of the ion nitriding furnace is set to 370 DEG C and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle 3 can be 14+ / -2 microns, the surface hardness can be HV950+ / -30, and the medical suture needle 3 can be accurately processed according to the actual use requirement.

[0073] Embodiment 7

[0074] The difference between the embodiment 7 and the embodiment 1 is that the processing temperature of the ion nitriding furnace in S5 is set to 400 DEG C, the process gas ratio is N2:H2=1:3, and the medical suture needle 3 is taken out for air cooling after nitriding, the nitriding layer depth is detected to be 19+ / -2 microns, and the surface hardness is HV1080+ / -30.

[0075] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 7 of the application is that: when the processing temperature of the ion nitriding furnace is set to 400 DEG C and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle 3 can be 19+ / -2 microns, the surface hardness can be HV1080+ / -30, and the medical suture needle 3 can be accurately processed according to the actual use requirement.

[0076] Embodiment 8

[0077] The difference between the embodiment 8 and the embodiment 1 is that the processing temperature of the ion nitriding furnace in S5 is set to 430 DEG C, the process gas ratio is N2:H2=1:3, and the medical suture needle 3 is taken out for air cooling after nitriding, the nitriding layer depth is detected to be 23+ / -2 microns, and the surface hardness is HV1190+ / -30.

[0078] The implementation principle of the processing method of the austenitic stainless steel medical suture needle ion nitriding in the embodiment 8 of the application is that: when the processing temperature of the ion nitriding furnace is set to 430 DEG C and the process gas ratio is N2:H2=1:3, the nitriding layer depth of the medical suture needle 3 can be 23+ / -2 microns, the surface hardness can be HV1190+ / -30, and the medical suture needle 3 can be accurately processed according to the actual use requirement.

[0079] The above are the preferred embodiments of the application, which do not limit the protection scope of the application, so: any equivalent changes made on the structure, shape, principle of the application shall be covered within the protection scope of the application.

Claims

1. A method for ion nitriding austenitic stainless steel medical suture needle, characterized in that: Includes the following steps: S1. Medical suture needle (3) forming: austenitic stainless steel wire is first cold-drawn to different diameter specifications and hardness of HV330~380. The austenitic stainless steel wire is then formed by uncoiling, straightening, cutting, needle hole processing and needle tip processing. The medical suture needle (3) is straight. S2. Needle tip finishing: The medical suture needle (3) processed in S1 is finished with needle tip finishing to achieve a sharp needle tip without any false tip. S3. Polishing of medical suture needle (3): The medical suture needle (3) processed in S2 is subjected to chemical or electrochemical surface polishing treatment. S4. Cleaning and drying of medical suture needles (3): The medical suture needles (3) processed in S3 are cleaned and dried. S5. Needle tip ion nitriding: The medical suture needle (3) processed in S4 is placed on the cathode plate (1) of the ion nitriding furnace, and the anode plate (2) is moved to cover the needle tip of the medical suture needle (3). The ion nitriding furnace is set to a voltage of 550V and a gas pressure of 300Pa for 1 hour. The temperature is controlled between 350℃ and 430℃ according to the size of the medical suture needle (3). The process gas ratio is N2:H2=1:9 or N2:H2=1:

3. After ion nitriding, the needle is taken out and air-cooled. The surface hardness of the nitrided layer of the medical suture needle (3) is HV750~1200. S6. Cleaning and drying of medical suture needles (3): The medical suture needles (3) processed in S5 are cleaned with water and then dried. S7. Bending the medical suture needle (3): The medical suture needle (3) after S6 is bent as required to achieve the required 1 / 2 arc, 3 / 8 arc or 5 / 8 arc shape. S8. Cleaning and drying of medical suture needles (3): The medical suture needles (3) processed in S7 are cleaned with water and then dried. In step S5, the cathode plate (1) facing the anode plate (2) has multiple positioning holes (11) for the needle tail of the medical suture needle (3) to be inserted. The outer peripheral surface of the needle tail of the medical suture needle (3) abuts against the inner wall of the positioning hole (11) to form a limit. The inner wall of the positioning hole (11) is flared in the direction close to the axis of the positioning hole (11). The anode plate (2) facing the cathode plate (1) has multiple nitriding holes (21) for the needle tip of the medical suture needle (3) to be inserted. The inner wall of the nitriding hole (21) is flared in the direction close to the axis of the nitriding hole (21), and the inner wall of the nitriding hole (21) surrounds the outer peripheral surface of the needle tip.

2. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 350℃, the process gas ratio is N2:H2=1:9, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 6±2μm and the surface hardness is HV780±30.

3. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 370℃, the process gas ratio is N2:H2=1:9, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 9±2μm and the surface hardness is HV890±30.

4. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 400℃, the process gas ratio is N2:H2=1:9, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 13±2μm and the surface hardness is HV1010±30.

5. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 430℃, the process gas ratio is N2:H2=1:9, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 17±2μm and the surface hardness is HV1110±30.

6. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 350℃, the process gas ratio is N2:H2=1:3, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 11±2μm and the surface hardness is HV830±30.

7. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 370℃, the process gas ratio is N2:H2=1:3, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 14±2μm and the surface hardness is HV950±30.

8. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 400℃, the process gas ratio is N2:H2=1:3, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 19±2μm and the surface hardness is HV1080±30.

9. The processing method for ion nitriding of austenitic stainless steel medical suture needles according to claim 1, characterized in that: The nitriding furnace treatment temperature in step S5 is set to 430℃, the process gas ratio is N2:H2=1:3, and after nitriding, it is taken out and air-cooled, so that the nitriding layer depth of the medical suture needle (3) is 23±2μm and the surface hardness is HV1190±30.

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