A laser cladding anti-rust strengthening method for a rail surface

Abstract

The present application relates to the technical field of metal surface treatment, and particularly provides a laser cladding rust-proof reinforcing method for a rail surface, comprising the following steps: S1, performing rust removal and cleaning treatment on the surface of a rail sampling section; S2, matching a robot plane program setting with a walking shaft speed; S3, laser cladding an alloy layer on the surface of the rail sampling section; S4, performing a salt spray test on the rail sampling section; and S5, performing a hardness test on the rail sampling section. The cladding layer surface is smooth and free of pores, the reinforcing efficiency can reach 40-45 meters / hour (the length of the rail), and the surface is free of obvious rust after 24 hours of salt spray test.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, and specifically relates to a laser cladding method for rust prevention and strengthening of track surfaces. Background Technology

[0002] Tracks are a crucial component of rail transit. Because track surfaces are constantly exposed to the elements, they are subject to wear, sun exposure, wind, and rain, leading to oxidation and corrosion. Rust on the rail surface directly affects the data collected by train sensors and causes wear on the wheels, thus impacting train operation. Traditional track surface repair methods involve flame spraying, but this method has poor adhesion and is prone to peeling. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a laser cladding rust prevention and strengthening method for track surfaces to solve the above-mentioned technical problems.

[0004] This invention provides a laser cladding method for rust prevention and strengthening of track surfaces, comprising:

[0005] S1. Perform rust removal and cleaning treatment on the surface of the track sampling section;

[0006] S2. Robot planar program settings and travel axis speed matching;

[0007] S3. Laser cladding of alloy layer on the surface of the track sampling section;

[0008] S4. Conduct salt spray testing on the track sampling section;

[0009] S5. Perform hardness testing on the track sampling section.

[0010] In an optional implementation, step S1, the rust removal and cleaning process includes: manually polishing to remove the rust and oxide layer from the guide rail surface, and wiping the surface of the part to be strengthened with industrial detergent or industrial alcohol.

[0011] In an optional implementation, in step S2, the cladding head swings back and forth as the robot guide rail moves, and the cladding trajectory posture presents a V-shaped plane. The two ends of the rail are set with pre-activated and pre-activated lights to reduce the protrusion of the cladding layer at both ends, match the movement speed of the guide rail, and complete the program logic editing.

[0012] In one optional implementation, the method of setting the laser on and off at both ends of the track includes: if the cladding head swings toward the V-shaped inflection point, the laser is turned off when it reaches a point 2mm away from the V-shaped inflection point; if the cladding head swings away from the V-shaped inflection point, the laser is turned on when it reaches a point 2mm away from the V-shaped inflection point.

[0013] In an optional embodiment, in step S3, the material is selected as nickel-based superalloy powder, comprising the following chemical composition by weight percentage: Cr 19.27%, Ni 51.58%, Fe 19.03%, Ti 1.25%, Mo 3.18%, Nb 5.42%, Mn 0.29%, with the balance being unavoidable impurities.

[0014] In an optional embodiment, in step S3, the nickel-based alloy powder has a particle size of 53-150 mesh and an average hardness of 38-42 HRC.

[0015] In an optional implementation, in step S3, the laser cladding method parameters for the cladding layer are as follows: laser power is 1200W, spot size is 3mm, robot walking axis running speed is 7.5cm / min, cladding head swing speed is 400cm / min, protective gas is Ar, gas flow rate is 8-9L / min, laser head is at a 75° angle to track surface, powder feeding rate is 1.5-2r / min, and cladding layer thickness on one side is 50 mils.

[0016] In an optional implementation, in step S4, the track sampling section undergoes a neutral salt spray test for 24 hours.

[0017] In an optional implementation, in step S5, the hardness of the track sampling section surface is detected. The cladding layer surface is smooth and free of pores, and the average hardness is 40 HRC.

[0018] The beneficial effects of this invention are as follows: The laser cladding rust prevention and strengthening method for track surfaces provided by this invention involves laser cladding of the track surface using nickel-based high-temperature alloy powder. The cladding trajectory adopts a V-shaped trajectory to ensure the uniformity of the cladding. Simultaneously, the relationship between the switching time of the cladding head and the travel position of the cladding head is carefully controlled to avoid uneven cladding or lifting at the V-shaped inflection points. This method results in a smooth, pore-free cladding layer, a strengthening efficiency of 40-45 meters per hour (track length), and no obvious rust after a 24-hour salt spray test.

[0019] Furthermore, the design principle of this invention is reliable, the structure is simple, and it has a very wide range of application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0024] To facilitate understanding of the present invention, the laser cladding rust prevention and strengthening method for track surfaces provided by the present invention will be further described below with reference to the principle of the laser cladding rust prevention and strengthening method for track surfaces provided by the present invention and in conjunction with embodiments.

[0025] Example 1

[0026] For details, please refer to Figure 1 The laser cladding rust prevention and strengthening method for the track surface includes:

[0027] Step 1: Cleaning the areas of the track surface to be reinforced: Manually grind and polish to remove rust, oxide layers, etc. from the surface of the guide rail, and wipe the surface of the areas to be reinforced with industrial detergent or industrial alcohol. The purpose of this process is to reduce the negative impact that impurities and stains on the substrate surface may have on the cladding layer.

[0028] Step 2: Move along the robot guide rail, swing the cladding head back and forth, and the cladding trajectory posture presents a V-shaped plane. Set the pre-light on and off at both ends of the track to reduce the cladding layer protrusion at both ends, and complete the program logic editing.

[0029] The parameters for the laser cladding method of the cladding layer are as follows: laser power is 1200W, spot size is 3mm, robot walking axis running speed is 7.5cm / min, cladding head swing speed is 400cm / min, protective gas is Ar, gas flow rate is 8-9L / min, laser head is at a 75° angle to track surface, powder feeding rate is 1.5-2r / min, and cladding layer thickness on one side is 50 mils.

[0030] The main reason for the protrusions at both ends is that the robot (cladding head) only sends the laser-stop command during the deceleration phase or after stopping, causing the powder and molten pool to remain in place for too long. Therefore, a pre-switching laser was added to this motion control, allowing the robot to send the laser on / off signal during movement, effectively reducing the dwell time at the actual points. Specifically, the cladding head swings towards the V-shaped inflection point, turning off the laser when it reaches a point 2mm away from the V-shaped inflection point; the cladding head then swings away from the V-shaped inflection point, turning on the laser when it reaches a point 2mm away from the V-shaped inflection point.

[0031] To avoid changes in the robot's position due to deviations in the target track shape, which would alter the actual distance between the robot and the target track, the robot's movement according to the programmed trajectory might cause the laser trajectory to deviate. Therefore, it is necessary to collect the actual distance between the two to verify whether any deviation exists.

[0032] A distance measuring sensor is installed on the side of the robot facing the target track. The distance measuring sensor collects the distance between the robot and the target track. The controller obtains the distance collected by the distance measuring sensor through a signal line and determines whether the difference between the distance and the preset standard distance reaches a set threshold. If yes, the controller controls the robot to stop walking, controls the cladding head to stop swinging and turns off the laser, and adjusts the position of the target track. If no, the distance is written to a record file.

[0033] Step 3: Select nickel-based high-temperature alloy powder as the material, which includes the following chemical composition by weight percentage: Cr 19.27%, Ni 51.58%, Fe 19.03%, Ti 1.25%, Mo 3.18%, Nb 5.42%, Mn 0.29%, with the balance being unavoidable impurities; the particle size of the nickel-based alloy powder is 53~150 mesh, and the average hardness is 38-42 HRC.

[0034] Step 4: The track sample underwent a neutral salt spray test for 24 hours. No obvious rust was observed on the reinforced surface of the track after the salt spray test.

[0035] Step 5: Surface hardness test of track sample. The surface of the cladding layer is smooth and free of pores, with an average hardness of about 40 HRC. There is no heat-affected zone on the surface of the track substrate after grinding and polishing.

[0036] Comparative Example 1

[0037] Comparative Example 1 changed the moving speed of the walking axis in Example 1 (reduced), as shown in Table 1. The track surface was strengthened while the core data such as laser cladding power parameters and the thickness of the cladding layer remained unchanged.

[0038] Table 1. Design of travel axis moving speed for Comparative Example 1

[0039]

[0040] As shown in Table 1, increasing the powder amount and accelerating the travel axis speed improved efficiency, but corrosion appeared on the track surface. Conversely, reducing the powder amount and decreasing the travel axis speed, while preventing corrosion in the salt spray test, resulted in a 6 m / h decrease in efficiency compared to Example 1. Therefore, the method parameters in Example 1 effectively balanced efficiency with corrosion resistance.

[0041] Comparative Example 2

[0042] Comparative Example 2 changed the thickness of the cladding layer on the track surface in Example 1, as shown in Table 2. Track surface strengthening was carried out while keeping the core data such as laser cladding power parameters unchanged (only the thickness of the cladding layer was changed).

[0043] Table 2 Comparative Example 2 Track Surface Cladding Thickness Design

[0044]

[0045] As can be seen from Table 2, as the thickness of the cladding layer on the track surface decreases (from top to bottom), the corrosion state of the track surface (from left to right) gradually worsens. Therefore, the cladding layer thickness method parameters in Example 1 not only meet the corrosion resistance requirements, but also have reasonable core method parameters such as powder dosage.

[0046] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. A laser cladding method for rust prevention and strengthening of track surfaces, characterized in that, include: S1. Perform rust removal and cleaning treatment on the surface of the track sampling section; S2. Robot planar program settings and travel axis speed matching; S3. Laser cladding of alloy layer on the surface of the track sampling section; S4. Conduct salt spray testing on the track sampling section; S5. Perform hardness testing on the sampled track section; In S2, the cladding head swings back and forth as the robot moves along the guide rail, and the cladding trajectory posture presents a V-shaped plane. The two ends of the track are set to turn on and off in advance to reduce the cladding layer protrusion at both ends, match the guide rail movement speed, and complete the program logic editing. The method of setting the laser on and off at both ends of the track includes: if the cladding head swings towards the V-shaped inflection point, the laser is turned off when it reaches a point 2mm away from the V-shaped inflection point; if the cladding head swings away from the V-shaped inflection point, the laser is turned on when it reaches a point 2mm away from the V-shaped inflection point.

2. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 1, characterized in that, In step S1, the rust removal and cleaning process includes: manually polishing to remove the rust and oxide layer from the guide rail surface, and wiping the surface of the area to be strengthened with industrial detergent or industrial alcohol.

3. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 1, characterized in that, In step S3, the material selected is a nickel-based high-temperature alloy powder, which includes the following chemical composition by weight percentage: Cr 19.27%, Ni 51.58%, Fe 19.03%, Ti 1.25%, Mo 3.18%, Nb 5.42%, Mn 0.29%, with the balance being unavoidable impurities.

4. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 3, characterized in that, In step S3, the nickel-based alloy powder has a particle size of 53-150 mesh and an average hardness of 38-42 HRC.

5. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 1, characterized in that, In step S3, the parameters of the laser cladding method for the cladding layer are as follows: laser power is 1200W, spot size is 3mm, robot walking axis running speed is 7.5cm / min, cladding head swing speed is 400cm / min, protective gas is Ar, gas flow rate is 8-9L / min, laser head is at a 75° angle to track surface, powder feeding rate is 1.5-2r / min, and cladding layer thickness on one side is 50 mils.

6. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 1, characterized in that, In step S4, the track sampling section undergoes a neutral salt spray test for 24 hours.

7. The laser cladding rust prevention and strengthening method for track surfaces as described in claim 1, characterized in that, In step S5, the hardness of the track sampling section surface is tested. The cladding layer surface is smooth and free of pores, and the average hardness is 40 HRC.

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