Endoscopic laser cladding-forming-selective laser welding co-sealing method

Abstract

This invention provides a method for the coordinated sealing of endoscopes by laser cladding, forming, and selective laser welding, comprising: (1) cladding Ag-Cu-Ti powder onto the surface of a medical stainless steel plate substrate; (2) sequentially performing plastic processing, laser welding, wire cutting, and brightening treatment on the clad stainless steel plate to prepare a tubular structure; (3) embedding an endoscope protective lens into the front end of the tubular structure of a matching size and clamping it in place; (4) selectively laser welding the endoscope protective lens and the tubular structure at local locations using selective laser welding technology, melting the Ag-Cu-Ti cladding alloy layer in the irradiated area, so that the endoscope protective lens and the tubular structure can be sealed together; while the Ag-Cu-Ti cladding alloy layer in the unirradiated area does not melt. This invention solves the problems of poor endoscope sealing, complex and difficult processes, and high processing costs, enabling endoscopes under high temperature and high pressure sterilization conditions to serve for a long time with high performance.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, specifically relating to a method for synergistic sealing of endoscope laser cladding, processing and shaping, and selective laser welding. Background Technology

[0002] An endoscope is a specialized diagnostic instrument that enters the human body through the mouth, stomach, or other natural orifices, allowing it to visualize lesions that X-rays cannot detect. Rigid endoscopes are one of the main types of endoscopes used in medical examinations. They primarily consist of an optical imaging system and an illumination system, and are suitable for use in superficial and shallow cavities of the body, such as the ear, nose, throat, uterus, and bronchi, as well as for opening the oral cavity via puncture.

[0003] The connection between the protective lens and the surrounding metal of a rigid endoscope directly affects the endoscope's sealing performance, thus impacting its service performance and lifespan. Utility model patent application number 201621097975.1 proposes an endoscope objective lens sealing structure, which uses adhesive bonding to connect the lens to the endoscope tube. However, this bonding process has poor tolerance to high-temperature and high-pressure sterilization, and the number of sterilization cycles is very limited. Utility model patent application number 201821972952.X proposes endoscope end-lens, objective lens, and eyepiece end structures, primarily using a method of coating the lens circumferentially with a metal film, and then welding the lens to the metal endoscope tube based on this metal film. However, circumferential coating of the lens is difficult and costly. The invention patent with application number 202210386571.8 proposes a high-temperature resistant rigid tube endoscope, which uses brazing to weld a sapphire lens to a stainless steel tube. However, after the endoscope is brazed, the brazing filler material often flows to the location where brazing is not needed and is difficult to remove. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a method for the coordinated sealing of endoscopes by laser cladding, forming, and selective laser welding. This method solves problems such as poor endoscope sealing, complex and difficult processes, and high processing costs, enabling endoscopes to serve for extended periods and with high performance under high-temperature and high-pressure sterilization conditions.

[0005] This invention is achieved through the following technical solution:

[0006] A method for synergistic sealing of endoscopes via laser cladding, forming, and selective laser welding includes the following steps:

[0007] (1) Medical stainless steel plate is selected as the substrate. A high-speed laser cladding method is used to focus the laser beam at a position 0.2-3 mm above the substrate surface and clad Ag-Cu-Ti powder is clad on the substrate surface. The thickness of the cladding layer is controlled at 0.2-0.65 mm. The chemical composition of Ag-Cu-Ti powder is as follows: Ag contains 60-66%, Cu contains 28-36%, Ti contains 1.5-3%, In contains 0-3%, and Li contains 0-10%.

[0008] (2) The stainless steel plate with Ag-Cu-Ti powder fused to its surface is subjected to plastic processing, laser welding, wire cutting and brightening treatment in sequence to prepare a tubular structural component with a diameter of 2-10 mm, a length of 13-35 mm and an inner wall surface with Ag-Cu-Ti fused alloy layer.

[0009] (3) Embed the endoscope protective lens into the front end of the tubular structure of the matching size and clamp it in place;

[0010] (4) Based on selective laser welding technology, the endoscope protective lens and the tubular structure are selectively laser welded at local locations. The laser spot is arrayed and selectively irradiated on the Ag-Cu-Ti cladding alloy layer. The Ag-Cu-Ti cladding alloy layer in the irradiated area melts, so that the endoscope protective lens and the tubular structure can be encapsulated. The Ag-Cu-Ti cladding alloy layer in the unirradiated area does not melt.

[0011] Furthermore, in step (1), before using the stainless steel plate, first use coarse sandpaper to remove rust and dirt, then use fine sandpaper to polish the surface until it is smooth, then clean it with ethanol, and finally let it cool and dry in a clean and ventilated place for later use.

[0012] Furthermore, the plastic processing in step (2) includes three steps: pre-bending the steel plate, U-forming, and O-forming. First, a small pre-bending press is used to pre-bend the long edge of a stainless steel plate with a width of 6.28 to 31.41 mm and a wall thickness of 0.5 to 1.5 mm, so that the radius of curvature of the bend is the same as the radius of the pre-designed O-shaped steel plate. Then, the pre-bent steel plate is positioned on a small U-forming press and bent into a U-shaped steel plate under the action of a vertical die and a bottom die. Finally, the U-shaped steel plate is placed in the lower die of the small O-shaped press, and the upper die of the small O-shaped press squeezes the upper part of the U-shaped steel plate, so that the U-shaped steel plate is compressed into an O-shaped steel plate.

[0013] Furthermore, the laser welding process in step (2) includes: firstly, cleaning and grinding the parts of the O-shaped steel plate that need to be welded along its length; then, clamping and fixing the O-shaped steel plate using tooling fixtures; and finally, welding the O-shaped steel plate into a tubular structure using a 600W to 1000W fiber laser and a welding speed of 0.5 to 1.5m / min.

[0014] Furthermore, the wire cutting process in step (2) includes: wire cutting the welded tubular structure according to the length specifications of the endoscope to cut the tubular structure into a length of 13 to 35 mm, and the wire cutting accuracy is required to reach ±0.005 mm, the cutting speed is not less than 0.2 m / s, and the surface roughness of the cut surface is at least Ra0.8.

[0015] Furthermore, the brightening process in step (2) includes: using a pulsed laser with a maximum power of 300w to perform high-speed laser cleaning on the weld and cut surface of the cut tubular structure. After laser cleaning, the surface roughness Ra of the stainless steel tube reaches 0.38 to 0.8 μm.

[0016] Furthermore, in step (4), selective laser welding is performed under an argon atmosphere with the following parameters: laser spot size is 35-70 μm; laser power is 110W-170W; scanning speed is 2-5 mm / s; pulse width is 3-5 ms; and repetition frequency is 5-20 Hz.

[0017] The present invention has the following beneficial effects:

[0018] (1) The present invention obtains a tubular composite structure with an inner layer of Ag-Cu-Ti alloy with a low melting point and an outer layer of medical stainless steel by high-speed laser cladding and processing forming method. The endoscope protective lens is welded to the aforementioned tubular composite structure at a local position by selective laser welding method, thereby achieving a high-quality seal at the endoscope protective lens position.

[0019] (2) This invention achieves metallurgical bonding between medical stainless steel plate and low melting point Ag-Cu-Ti alloy by high-speed laser cladding, breaking through the traditional stainless steel-low melting point alloy bonding methods such as coating and brazing. Moreover, the chemical composition of the laser cladding layer is very convenient and flexible to control, and the thickness and uniformity of the cladding layer are highly controllable.

[0020] (3) The present invention uses high-speed scanning pulsed laser to brighten the exposed metal surface in tubular composite structure components. It can efficiently remove oxide layers, oil stains and other substances in specific areas with a region area of ​​micrometers, and does not damage the Ag-Cu-Ti alloy of the inner layer during the brightening process.

[0021] (4) The present invention uses selective laser welding to weld the endoscope protective lens and the outer metal ring. On the one hand, the heat input during selective laser welding is smaller than that during full-area laser welding, and the induced thermal deformation is smaller, which is beneficial to the control of the endoscope size accuracy. On the other hand, during high temperature and high pressure sterilization, the metal and glass are prone to cracks near the bonding interface due to inconsistent thermal expansion and deformation, which can lead to air and water leakage of the endoscope. Selective laser welding can use the unwelded area as a buffer layer to release stress and solve the problem of cracking induced by thermal deformation.

[0022] (5) The present invention uses a high-speed laser cladding method to uniformly and densely clad a 0.2-0.65 mm thick low melting point Ag-Cu-Ti alloy on medical stainless steel. The alloy acts as a brazing filler metal in the selective laser welding process, avoiding problems such as uneven brazing filler metal distribution and brazing filler metal overflow in the conventional brazing process.

[0023] (6) Endoscopes treated by laser cladding-processing and selective laser welding combined sealing method can withstand more than 3,000 high temperature and high pressure sterilization treatments at 134℃. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the pre-bending edge during the plastic forming process;

[0025] Figure 2 A schematic diagram of U-forming during the plastic processing;

[0026] Figure 3 This is a schematic diagram of O-forming during the plastic processing procedure.

[0027] Figure 4 This is a schematic diagram showing the fit between the endoscope protective lens and the tubular structural component; Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] This invention provides a method for synergistic sealing of endoscopes via laser cladding, forming, and selective laser welding, comprising the following steps:

[0030] (1) Medical-grade stainless steel plate was selected as the substrate. A high-speed laser cladding method was used to focus the laser beam at a position 0.2–3 mm above the substrate surface, and Ag-Cu-Ti powder was clad onto the substrate surface, with the cladding layer thickness controlled at 0.2–0.65 mm. The chemical composition (mass fraction) of the Ag-Cu-Ti powder was 60–66% Ag, 28–36% Cu, 1.5–3% Ti, 0–3% In, and 0–10% Li.

[0031] Preferably, 304 stainless steel sheet is the first choice. Before using the stainless steel sheet, first use coarse sandpaper to remove rust and dirt, then use fine sandpaper to polish the surface until it is smooth, then clean it with ethanol, and finally let it air dry in a clean and ventilated place for later use.

[0032] (2) The 304 stainless steel plate with Ag-Cu-Ti powder fused to its surface is subjected to plastic processing, laser welding, wire cutting and brightening treatment in sequence to prepare a tubular structural component with a diameter of 2-10 mm, a length of 13-35 mm and an inner wall surface with Ag-Cu-Ti fused alloy layer.

[0033] Specifically, the plastic forming process includes three steps: pre-bending of the steel plate, U-forming, and O-forming, such as... Figure 1-3 As shown, firstly, a small pre-bending press is used to pre-bend the long edges of a 304 stainless steel plate with a width of 6.28–31.41 mm and a wall thickness of 0.5–1.5 mm, so that the radius of curvature of the bend is the same as the radius of the pre-designed O-shaped steel plate. Then, the pre-bent steel plate is positioned on a small U-forming press and bent into a U-shaped steel plate under the action of a vertical die and a bottom die. Finally, the U-shaped steel plate is placed in the lower die of the small O-shaped press, and the upper die of the small O-shaped press squeezes the upper part of the U-shaped steel plate, compressing the U-shaped steel plate into an O-shaped steel plate.

[0034] The laser welding process includes: first, cleaning and grinding the areas along the length of the O-shaped steel plate to be welded to improve the weld strength; then, clamping and fixing the O-shaped steel plate using a self-made fixture to ensure the weld position does not shift during the welding process; finally, using a 600W–1000W fiber laser and a welding speed of 0.5–1.5 m / min, the O-shaped steel plate is welded into a tubular structural component. Welding requirements include uniform weld shape, smooth transitions between weld beads and between weld beads and the base metal, and thorough removal of weld slag and spatter; surface porosity and undercut are not allowed in the weld; the roundness deviation of the welded tubular structural component is allowed to be ±0.1 mm.

[0035] The wire cutting process includes: cutting the welded tubular structure according to the length specifications of the endoscope to cut the tubular structure into a length of 13-35mm, with a wire cutting accuracy of ±0.005mm, a cutting speed of not less than 0.2m / s, and a surface roughness of at least Ra0.8 on the cut surface.

[0036] The brightening process includes: high-speed laser cleaning of the weld seams and cut surfaces of the pre-cut tubular structural components using a pulsed laser with a maximum power of 300W. The cleaning area and scanning speed can be adjusted by deflecting the laser scanning galvanometer. The laser power can be adjusted from 60W to 180W, and the scanning speed is from 2000mm / s to 11000mm / s for ultrafast cleaning. After laser cleaning, the surface roughness Ra of the stainless steel tube can reach 0.38 to 0.8μm. High-speed laser cleaning can achieve better processing quality and improve processing efficiency. At the same time, the short-pulse laser has a very small heat-affected zone, which will not damage the internal structure.

[0037] (3) Embed the endoscope protective lens into the front end of a tubular structure of matching size, and clamp the two together to increase the contact area between the lens and the tube wall, such as... Figure 4 As shown, 1 is a tubular structural component, 2 is an endoscope protective lens, and 3 is an Ag-Cu-Ti cladding alloy layer.

[0038] (4) Based on selective laser welding technology, the endoscope protective lens is selectively welded to the tubular structure at localized locations. The laser spot is arrayed (diagonal or grid pattern, etc.) and selectively irradiates the Ag-Cu-Ti cladding alloy layer. The irradiated areas of the Ag-Cu-Ti cladding alloy layer melt, allowing the endoscope protective lens to be encapsulated with the tubular structure. The unirradiated areas of the Ag-Cu-Ti cladding alloy layer do not melt and can act as a buffer layer to release stress. Simultaneously, the above operation should be performed in an argon atmosphere to ensure that the stainless steel tube does not oxidize during the selective laser welding process.

[0039] The selective laser welding parameters are as follows: laser spot size is 35–70 μm, laser power is 110 W–170 W, scanning speed is 2–5 mm / s, pulse width is 3–5 ms, and repetition frequency is 5–20 Hz. By adjusting the welding parameters, the final product can be repeatedly cleaned 2000–3000 times under high temperature and high pressure.

[0040] It will be apparent to those skilled in the art that the present invention can be modified in various ways, and such modifications are not considered to depart from the scope of the invention. All such modifications that are obvious to those skilled in the art are included within the scope of the claims.

Claims

1. A method for synergistic sealing of endoscopes via laser cladding, forming, and selective laser welding, characterized in that: Includes the following steps: (1) Medical stainless steel plate is selected as the substrate. A high-speed laser cladding method is used to focus the laser beam at a position 0.2-3 mm above the substrate surface and clad Ag-Cu-Ti powder is clad on the substrate surface. The thickness of the cladding layer is controlled at 0.2-0.65 mm. The chemical composition of Ag-Cu-Ti powder is as follows: Ag contains 60-66%, Cu contains 28-36%, Ti contains 1.5-3%, In contains 0-3%, and Li contains 0-10%. (2) The stainless steel plate with Ag-Cu-Ti powder fused to its surface is subjected to plastic processing, laser welding, wire cutting and brightening treatment in sequence to prepare a tubular structural component with a diameter of 2-10 mm, a length of 13-35 mm and an inner wall surface with Ag-Cu-Ti fused alloy layer. (3) Embed the endoscope protective lens into the front end of the tubular structure of the matching size and clamp it in place; (4) Based on selective laser welding technology, the endoscope protective lens and the tubular structure are selectively laser welded at local locations. That is, the laser spot is arrayed and selectively irradiated on the Ag-Cu-Ti cladding alloy layer. The Ag-Cu-Ti cladding alloy layer in the irradiated area melts, so that the endoscope protective lens and the tubular structure can be encapsulated; while the Ag-Cu-Ti cladding alloy layer in the unirradiated area does not melt.

2. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 1, characterized in that, Before using the stainless steel plate in step (1), first use coarse sandpaper to remove rust and dirt, then use fine sandpaper to polish the surface until it is smooth, then clean it with ethanol, and finally let it air dry in a clean and ventilated place for later use.

3. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 1, characterized in that, The plastic processing in step (2) includes three steps: pre-bending the steel plate, U-forming, and O-forming. First, a small pre-bending press is used to pre-bend the long edge of a stainless steel plate with a width of 6.28 to 31.41 mm and a wall thickness of 0.5 to 1.5 mm, so that the radius of curvature of the bend is the same as the radius of the pre-designed O-shaped steel plate. Then, the pre-bent steel plate is positioned on a small U-forming press and bent into a U-shaped steel plate under the action of a vertical die and a bottom die. Finally, the U-shaped steel plate is placed in the lower die of the small O-shaped press, and the upper die of the small O-shaped press squeezes the upper part of the U-shaped steel plate, so that the U-shaped steel plate is compressed into an O-shaped steel plate.

4. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 3, characterized in that, The laser welding process in step (2) includes: first, cleaning and grinding the parts of the O-shaped steel plate that need to be welded along its length; then, clamping and fixing the O-shaped steel plate with tooling fixtures; and finally, welding the O-shaped steel plate into a tubular structure using a 600W to 1000W fiber laser and a welding speed of 0.5 to 1.5m / min.

5. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 4, characterized in that, The wire cutting process in step (2) includes: cutting the welded tubular structure according to the length specifications of the endoscope to cut the tubular structure with a length of 13 to 35 mm, and the wire cutting accuracy is required to reach ±0.005 mm, the cutting speed is not less than 0.2 m / s, and the surface roughness of the cut surface is at least Ra0.

8.

6. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 5, characterized in that, The brightening process in step (2) includes: using a pulsed laser with a maximum power of 300w to perform high-speed laser cleaning on the weld and cut surface of the cut tubular structure. After laser cleaning, the surface roughness Ra of the stainless steel tube reaches 0.38 to 0.8 μm.

7. The endoscope laser cladding-processing-selective laser welding co-sealing method according to claim 6, characterized in that, In step (4), selective laser welding is performed in an argon atmosphere with the following parameters: laser spot size is 35-70 μm; laser power is 110 W-170 W; scanning speed is 2-5 mm / s; pulse width is 3-5 ms; and repetition frequency is 5-20 Hz.

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