Cutting edge forming process method of medical elbow scissor body

Abstract

The invention relates to the technical field of medical instrument manufacturing, in particular to a cutting edge forming process method of a medical elbow scissor body. The method comprises the following steps: S1, taking a shear body elbow curved surface forming standard as a reference, performing real-time monitoring through a multi-gradient allowance decreasing cutting and image acquisition device, avoiding cutting edge cracking and notch defects in a rough machining stage in advance, and reserving subsequent finish machining allowance; s2, the pre-formed shear body is subjected to heating, heat preservation, cooling and tempering, S3, the shear body subjected to heat treatment is fixed, secondary calibration is conducted based on a dynamic positioning system, cutting edge tiny deformation caused by heat treatment in S2 is accurately compensated, multiple times of precision machining of a high-precision hard alloy tool are matched, and deviation possibly accumulated in the early-stage process is effectively eliminated; s4, online detection is carried out to simulate the binding force of the test piece of the human tissue and the sensing assembly, and real-time parameter adjustment in the machining process is achieved; and local micro-cutting correction in the final inspection stage further compensates for tiny errors possibly existing in the preorder link, and the quality of the cutting edge is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical instrument manufacturing, and particularly relates to a blade edge forming process method of a medical elbow scissors. BACKGROUND

[0002] The medical elbow scissors is a key instrument for realizing tissue separation and suture shearing in minimally invasive surgery, and the precision and performance of the blade edge of the scissors directly determine the safety and effectiveness of the operation.

[0003] The existing blade edge forming process of the medical elbow scissors has significant technical shortcomings. Specifically, to achieve the required hardness and wear resistance of the blade edge, the blade edge substrate after preliminary forming is usually subjected to cutting processing, and then the material performance is strengthened through heat treatment such as quenching and tempering, and finally the blade edge is subjected to fine cutting to reach the design size. However, the blade edge of the scissors made of martensitic stainless steel will inevitably produce slight deformation during the heat treatment process due to the influence of heating temperature gradient and cooling rate difference, such as slight warping of the edge and slight deviation of the preset angle.

[0004] However, for the slight deformation that inevitably occurs after heat treatment, the existing process lacks effective solutions. When the blade edge is subjected to fine cutting, the initial positioning reference set in the previous cutting processing stage is still completely used, without considering the deviation of the actual position of the blade edge during the heat treatment process. The tool is directly guided for processing based on the initial reference. In this way, not only the slight deformation caused by heat treatment cannot be corrected, but the deformation amount is further enlarged during fine cutting, which finally leads to the fact that the angle tolerance of the blade edge exceeds the precise range required in clinical practice, and even the deviation of the blade edge on both sides of the scissors occurs, which seriously affects the shearing coordination of the scissors. More importantly, due to the mismatch between the positioning reference and the actual position of the blade edge, the problem of excessive or insufficient local cutting amount is prone to occur during fine cutting.

[0005] Therefore, it is urgent for technical personnel to solve the above problems. SUMMARY

[0006] The purpose of the present application is to provide a blade edge forming process method of a medical elbow scissors, which aims to solve the problem that the existing design is prone to slight deformation after heat treatment of the blade edge, and the subsequent fine cutting still uses the initial positioning reference, which cannot correct the deformation, resulting in the fact that the angle tolerance of the blade edge is out of tolerance, the deviation occurs, and the problems of excessive cutting and insufficient burr are prone to occur.

[0007] The present application relates to a blade edge forming process method of a medical elbow scissors, which comprises the following steps: S1, with the shearing body elbow curved surface forming reference as the reference, a multi-gradient allowance decreasing cutting strategy is adopted to process the cutting edge, a preset angle of the cutting edge basic angle is processed synchronously, and the image acquisition device is used to monitor the cutting edge edge state in real time during the processing process; and a precision machining allowance is reserved after rough machining; S2, the preformed shearing body is placed in a heating device, heated and kept warm, and after cooling to room temperature, it is transferred to a tempering device for tempering and cooling; S3, the shearing body after heat treatment is fixed on a processing device, secondary calibration is carried out based on a dynamic positioning system, a high-precision hard alloy cutter is used to implement repeated precision machining on the cutting edge, and micro-round angle passivation treatment is completed; S4, during the processing, a test piece simulating human tissue is used, the shearing force value is collected in real time by a shearing test device and a force sensing component, the cutting parameters are automatically adjusted when the force value fluctuation exceeds the preset range; the cutting performance test equipment is used to verify the shearing performance in the final inspection stage, the cutting edge angle is detected by a contour measuring device, the unqualified products are corrected to qualified by local micro-cutting, and the cutting edge forming is completed.

[0008] As a further improvement of the disclosed technical scheme of the application, in step S1, the initial cutting allowance is 0.15-0.35mm, the allowance decreases by 0.03-0.06mm at each gradient, the cutting edge basic angle is 20-35°, and the precision machining allowance reserved after rough machining is 0.03-0.07mm; the cutting speed of gradient cutting is adjusted synchronously with the decrease of the allowance, the initial gradient cutting speed is set to 75-105m / min, and the final gradient cutting speed is reduced to 55-75m / min.

[0009] As a further improvement of the disclosed technical scheme of the application, in step S2, the heating device adopts a segmented heating mode, first heated to above Ac3 by 40-110℃ and kept warm for 1-2H, then heated to 830-920℃ and kept warm for 1.2-2.2H; the tempering temperature of the tempering device is 160-270℃, and the holding time is 1.8-3.2H; the preset range of the cutting edge hardness is HRC50-56, and the preset value of the key size change is ≤0.03mm.

[0010] As a further improvement of the disclosed technical scheme of the application, in step S2, inert gas protection is used in the segmented heating stage, the inert gas is argon or nitrogen, and the gas flow is controlled at 4-9L / min; when cooled after tempering, the shearing body is placed in a holding container for slow cooling, and the cooling rate is controlled at 25-45℃ / H.

[0011] As a further improvement of the disclosed technical solution, in step S3, the dynamic positioning system comprises a displacement sensing module and a coordinate compensation module; the coordinate compensation module is in real-time communication with the numerical control system of the machining equipment, and the compensation response delay is ≤0.8S, and the positioning deviation of the secondary calibration is ≤±0.008mm; before the secondary calibration, a cleaning piece with a diameter of 0.008-0.012mm smaller than the positioning hole of the shear body is used to reciprocally clean the chip residues in the positioning hole.

[0012] As a further improvement of the disclosed technical solution, in step S3, the high-precision hard alloy cutter is made of ultra-fine grain hard alloy material, the cutter cutting edge arc radius is ≤0.012mm, and the cutting edge runout is ≤0.003mm; the number of repeated precise machining is set to 2-4 times, the cutting allowance of each machining is sequentially decreased, and the cutting speed difference between adjacent two machinings is controlled to be 15-25m / min; the micro-round corner radius of the passivation treatment is R0.008-0.025mm.

[0013] As a further improvement of the disclosed technical solution, a blade edge cleaning step is added between step S3 and step S4: a high-pressure air gun with a gas pressure of 0.25-0.55MPa is used to blow off the cutting debris on the blade edge surface, and then a dust-free cloth soaked with anhydrous ethanol or isopropyl alcohol is used to wipe the blade edge; after cleaning, a laser interferometer is used to detect the flatness of the blade edge surface, and the flatness deviation is ≤0.005mm.

[0014] In actual application, the blade edge forming process method of the medical elbow shear body disclosed by the application can at least achieve the following beneficial technical effects, specifically: 1) S1 avoids blade edge cracking and notch defects in the rough machining stage in advance through multi-gradient allowance decreasing cutting and real-time image monitoring, and reserves allowance for subsequent precision machining, laying a foundation for precision correction after heat treatment; the heat treatment link of S2 provides guarantee for blade edge hardness improvement, and S3 based on the secondary calibration of the dynamic positioning system accurately compensates the blade edge micro-deformation caused by the heat treatment in S2, cooperates with the multiple precise machining of the high-precision cutter, effectively eliminates the possible accumulated deviation in the previous process, and ensures the blade edge angle and form precision; 2) The online detection and final inspection correction of S4 form a closed-loop control, which realizes real-time parameter adjustment in the machining process by using a test piece simulating human tissue, connects the blade edge form of S3 precise machining, optimizes the cutting parameters through force value feedback, and avoids uneven sharpness caused by parameter mismatch; the local micro-cutting correction in the final inspection stage further compensates for the possible slight errors in the previous links. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and other accompanying drawings can be obtained by those skilled in the art without any creative effort.

[0016] Figure 1 It is a physical map of the medical elbow scissors body disclosed by the present application. DETAILED DESCRIPTION

[0017] The technical solutions disclosed by the present application will be further described in detail below in combination with specific embodiments. The blade edge forming process of the medical elbow scissors body mainly includes the following steps: S1, blade edge gradient pre-cutting forming; S2, blade edge base material heat treatment; S3, dynamic reference calibration and precision machining; S4, online detection and final inspection correction.

[0018] Among them, the blade edge gradient pre-cutting forming link (corresponding to step S1 in the process method) takes the elbow curved surface forming reference of the scissors body as the core reference, and constructs an adaptive cutting system according to the processing characteristics of different regions of the elbow. When the processing personnel adopts a multi-gradient allowance decreasing cutting strategy, the allowance distribution will be adjusted accordingly: the initial cutting allowance of the inner side of the elbow is appropriately increased, and the decreasing amount of each gradient is slowed down, so as to buffer the cutting stress by a larger allowance; the initial cutting allowance of the outer side is appropriately reduced, and the decreasing amount of each gradient is accelerated, so as to improve the processing efficiency while ensuring the surface quality.

[0019] When the basic angle of the cutting edge (20°-35°) is processed, the process integration is realized by optimizing the tool path: a ball nose end mill is selected, which simultaneously performs micro-chamfering on the edge of the blade (corner radius R0.02-0.03mm) while milling the basic angle, avoiding the collapse of the sharp edge during subsequent precision machining, and reducing the separate chamfering process. In order to find defects in time, this link is equipped with an image acquisition device, three high-definition industrial cameras are distributed at 120° to acquire images from the front, side and inclined surface of the blade, and a warm white ring light source is used to eliminate glare interference, and then combined with a defect recognition algorithm based on deep learning, the micro cracks, gaps and other problems are accurately identified.

[0020] The gradient cutting speed is adjusted in coordination with the allowance and the regional curvature: the speed of the inner region in the initial gradient is lower, and the speed of the outer region is higher, and the speed of the last gradient is uniformly reduced to the low speed range; the device automatically pauses to remove the cutting chips after completing each gradient cutting, avoiding secondary scratches. The precision machining allowance (0.03-0.07mm) reserved after rough machining is densely collected by a laser thickness gauge to ensure uniform distribution of the allowance, and to provide a stable base material for the precision connection of the subsequent process.

[0021] The blade base material heat treatment link (corresponding to the S2 step in the process method) is closely matched with the blade gradient pre-cutting link to solve the problems of heat treatment oxidation and deformation. The preformed shear body is placed into an atmosphere-protected box-type heating device by the processing personnel, and the temperature is raised to the Ac3 above interval (Ac3 is the austenitizing critical temperature of martensitic stainless steel) at a slow rate (5-8°C / min) during staged temperature rise, and the temperature is kept for 1-2H. The temperature is monitored in real time by the K-type thermocouple attached to the surface of the blade. When the temperature difference between different measuring points exceeds ±5°C, the device automatically adjusts the power of the corresponding area heating pipe to ensure the uniformity of the blade structure and avoid local grain coarsening. Then the temperature is raised to 830-920°C at a slower rate (3-5°C / min) and kept for 1.2-2.2H. In this stage, argon or nitrogen is used as the protective gas, and a pulse type gas supply method (gas supply pressure 0.12-0.15MPa, pulse frequency 30 times / min) is adopted. The periodic airflow disturbance is used to disperse the oxidation gas on the surface of the blade to avoid the formation of an excessively thick oxide skin.

[0022] The cooling stage controls the structure transformation through multi-stage oil cooling: first, immerse the shear body in 60-80°C rapid quenching oil to cool to 300-350°C (martensite transformation critical interval) at a cooling rate of 15-20°C / s to quickly obtain high-hardness martensite structure; then transfer the shear body to an isothermal oil tank at 180-200°C for 30-40 minutes to allow the residual austenite to slowly transform and reduce the internal stress generated by the structure transformation; finally, take out the shear body and cool it to room temperature naturally. During the tempering process, first place the shear body in an environment of 160-270°C for 1H, and then use a portable Rockwell hardness tester to measure the hardness at three different points on the blade. If the measured hardness value does not fall within the target range of HRC50-56, adjust the tempering temperature according to the hardness deviation (for every 1HRC of hardness deviation, adjust the tempering temperature by ±5°C), and continue to keep the temperature for 0.8-2.2H after adjustment. After tempering, the shear body is placed in a container filled with alumina insulation cotton and slowly cooled at a rate of 25-45°C / H controlled by the temperature control system, and the key dimensions of the blade are checked every H using a micrometer to ensure that the dimensional change is ≤0.03mm.

[0023] Here, it is important to note that for the thin area of the blade (thickness ≤0.5mm), a high-temperature ceramic protective sheet needs to be pasted before heat treatment to effectively prevent the thin area of the blade from having hardness deviation due to rapid heat conduction, thereby ensuring the consistency of the overall performance of the blade.

[0024] Dynamic reference calibration and precision machining (corresponding to the S3 step in the process method) is the core of correcting heat treatment deformation and achieving micron-level precision. After heat treatment, the shear body may have a slight deformation, and the processing personnel will fix it on the tooling table with a pneumatic clamping device to ensure that the initial positioning deviation is ≤±0.01 mm. The dynamic positioning system is composed of a laser displacement sensor and a six-axis coordinate compensation module: the laser displacement sensor collects X, Y, Z axis displacement data of 10 key measurement points along the length of the blade at a frequency of 15-20 times / min, the compensation module compares the collected data with the initial design reference, and adjusts the machining coordinates in real time through the PID algorithm. After each compensation is completed, the reference is automatically re-measured to ensure that the positioning deviation is ≤±0.008 mm, and the compensation response delay is ≤0.8S, effectively correcting the deformation caused by heat treatment.

[0025] Before the second calibration, high-pressure dry air with a pressure of 0.4-0.6 MPa is used to blow away the debris in the hole, and a polyurethane cleaning piece with a diameter of 0.008-0.012 mm smaller than the positioning hole is used to wipe back and forth 3-5 times to avoid scratching the hole wall with metal cleaning pieces and affecting the positioning accuracy.

[0026] The selected high-precision hard alloy tool is made of WC-Co ultra-fine grain material, and the tool surface is coated with AlTiN / TiSiN multi-layer coating. After fine grinding with a diamond grinding wheel, the cutting edge arc radius is ≤0.012 mm, and the runout is ≤0.003 mm, significantly improving the tool wear resistance.

[0027] Multiple repeated precision machining optimizes precision through the cooperation of excess and milling: the first removal of 0.02-0.03 mm excess, using the face milling method to reduce cutting vibration; the second removal of 0.01-0.015 mm excess, using the inverse milling method to improve surface finish; the third removal of 0.005-0.01 mm excess, using the spiral milling method to correct the micro-morphology deviation. Micro- fillet passivation treatment uses ultrasonic vibration cutting technology, the tool vibrates at a frequency of 20-30 kHz, and moves along the edge at a speed of 2-3 mm / min, accurately controls the fillet radius (R0.008-0.025 mm) and ensures uniformity. A blade cleaning step is added between this step and the S4 step: first remove surface debris by high-pressure air blowing and dust-free cloth wiping, then immerse the shear body in anhydrous ethanol at 40-50°C, and clean the residual debris in the micro-gap of the blade edge with 40 kHz ultrasonic cleaning for 5-8 minutes; after cleaning, use a laser interferometer to detect the flatness of the blade surface to ensure that the flatness deviation is ≤0.005 mm, avoiding the interference of debris on subsequent detection data.

[0028] The online detection and final inspection modification link (corresponding to the S4 step in the process method) realizes the real-time linkage of processing, detection and modification, and forms a complete guarantee system with the dynamic reference calibration precision processing link. The simulated human tissue test piece used in the processing process covers the commonly used types in clinical practice: for the shear demand of blood vessels, Shore A30-40 silicone strips are selected, for the shear demand of fascia, Shore A50 silicone strips are selected, and for the shear demand of sutures, nylon threads with a diameter of 0.3-0.8 mm are selected. The automatic feeding mechanism is used to alternate shear testing to ensure the adaptability of the blade edge to different tissues. The shear testing device is equipped with high-precision force and displacement sensors to collect shear force-displacement curves in real time. When the curve fluctuation exceeds ±3N, the system automatically analyzes the reasons and adjusts the parameters: if the shear force is too high due to insufficient sharpness of the blade edge, the feed speed is reduced by 0.005-0.01 mm / r; if the curve fluctuation is frequent due to uneven cutting force, the cutting speed is adjusted by 5-10 m / min to ensure the stability of the blade shear force and avoid damage to the tissue due to force differences during surgery.

[0029] The final inspection stage verifies the blade edge quality from three aspects: performance testing by shearing pig aortic blood vessels, requiring smooth shear process and blood vessel tear length ≤0.05 mm; profile measurement selects a three-coordinate measuring instrument (accuracy ±0.001 mm), collects 1 measurement point every 0.5 mm along the length direction of the blade edge to ensure that the angle tolerance is ≤±0.3°; in surface finish detection, the blade shear surface needs to reach Ra0.2-0.4 to reduce tissue adhesion, and the non-shear surface needs to reach Ra0.8-1.6 to reduce the risk of dirt residue during sterilization. For unqualified blade edges, nanoscale cutting technology is used for modification: single-point diamond tools (cutting edge arc radius ≤0.005 mm) are selected, the cutting depth is controlled at 0.001-0.005 mm, and the feed speed is 5-8 mm / min. The micron-level positioning of the slow wire machine tool realizes accurate correction; after correction, full detection is performed again until all indicators meet the standards, reducing the scrap of the shear body due to local defects and improving material utilization.

[0030] In summary, in the entire blade edge forming process, gradient pre-cutting lays a foundation for high-quality base materials through regional adaptation and defect interception, heat treatment balances hardness and deformation through precise temperature control and multi-stage cooling, dynamic calibration corrects deviations through real-time compensation and precise cutting and guarantees precision, online detection and final inspection modification ensure that the blade edge performance meets the standards, thereby significantly improving the service life and shear stability of the blade edge, fully meeting the stringent requirements of minimally invasive surgery for high precision, high wear resistance and high safety of the blade edge.

[0031] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for forming the cutting edge of a medical elbow scissor body, characterized in that, The method comprises the following steps: S1, referring to the shearing body elbow curved surface forming reference, adopting a multi-gradient allowance decreasing cutting strategy to process the cutting edge, synchronously processing a preset angle of the cutting edge basic angle, and monitoring the cutting edge edge state in real time through an image acquisition device during the processing process, and reserving a precision processing allowance after rough processing; S2, placing the preformed shearing body in a heating device, heating and heat preservation, cooling to room temperature, and then entering a tempering device for tempering and cooling; S3, fixing the shearing body after heat treatment on a processing device, performing secondary calibration based on a dynamic positioning system, and repeatedly performing precision processing on the cutting edge by using a high-precision hard alloy tool, and completing micro-radius rounding and passivation treatment; S4, during the processing, a test piece simulating human tissue is used, the shearing force value is collected in real time through a shearing test device and a force sensing assembly, and the cutting parameters are automatically adjusted when the force value fluctuation exceeds a preset range; in the final inspection stage, a cutting edge performance test equipment is used to verify the shearing performance, and a profile measuring equipment is used to detect the cutting edge angle, and unqualified products are corrected to be qualified through local micro-cutting, and the cutting edge forming is completed.

2. The method of claim 1, wherein the medical elbow scissors body is formed by a process comprising: In step S1, the initial cutting allowance is 0.15-0.35 mm, the allowance decreases by 0.03-0.06 mm at each gradient, the cutting edge basic angle is 20-35°, and the precision processing allowance reserved after rough processing is 0.03-0.07 mm; the cutting speed of gradient cutting is adjusted synchronously with the decrease of the allowance, the initial gradient cutting speed is set to 75-105 m / min, and the final gradient cutting speed is reduced to 55-75 m / min.

3. The method of claim 1, wherein the blade of the elbow scissors is formed by a process comprising: In step S2, the heating device adopts a segmented heating mode, first heated to above Ac3 by 40-110℃, and heat preserved for 1-2H, then heated to 830-920℃, and heat preserved for 1.2-2.2H; the tempering temperature of the tempering device is 160-270℃, and the heat preservation time is 1.8-3.2H; the preset range of the cutting edge hardness is HRC50-56, and the preset value of the key size change is ≤0.03 mm.

4. The method of claim 3, wherein the cutting edge of the elbow scissor is formed by a process comprising: In step S2, inert gas protection is used in the segmented heating stage, the inert gas is argon or nitrogen, and the gas flow is controlled to be 4-9 L / min; after tempering, the shearing body is placed in a heat preservation container for slow cooling, and the cooling rate is controlled to be 25-45℃ / H.

5. The method of claim 1, wherein the blade of the elbow scissor is formed by a process comprising: In step S3, the dynamic positioning system comprises a displacement sensing module and a coordinate compensation module; the coordinate compensation module communicates with the numerical control system of the processing device in real time, and the compensation response delay is ≤0.8S, and the positioning deviation of the secondary calibration is ≤±0.008 mm; before the secondary calibration, a cleaning piece with a diameter smaller than the shearing body positioning hole by 0.008-0.012 mm is used to clean the cutting chip residues in the positioning hole reciprocally.

6. The method of claim 1, wherein the blade of the elbow scissor is formed by a process comprising: In step S3, the high-precision hard alloy tool is made of ultra-fine grain hard alloy material, the tool cutting edge arc radius is ≤0.012 mm, and the cutting edge runout is ≤0.003 mm; the number of repeated precision processing is 2-4 times, the cutting allowance decreases successively for each processing, and the cutting speed difference between adjacent two processes is controlled to be 15-25 m / min; the radius of the micro-radius rounding and passivation treatment is R0.008-0.025 mm.

7. The method of claim 1, wherein the blade of the elbow scissor is formed by a process comprising: A blade cleaning step is added between step S3 and step S4: high-pressure air gun with air pressure of 0.25-0.55 MPa is used to blow off the cutting debris on the surface of the blade, and then the blade is wiped with a dust-free cloth soaked with anhydrous ethanol or isopropyl alcohol; After cleaning, the flatness of the blade surface is detected by a laser interferometer, and the flatness deviation is ≤0.005 mm.

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