A method for enhancing the wear resistance of a shield machine cutter using laser cladding technology

Abstract

The application discloses a method for enhancing wear resistance of a shield machine cutter by using a laser cladding technology, adopts swing laser processing forming, uses shield machine cutter base material powder, MAX phase particle Ti2AlC powder, rare earth element CeO2 powder and cooperates grain refinement. The energy of the swing laser beam is more uniform and plays a stirring role on the molten pool, the MAX phase particle and the rare earth element play a role in inhibiting grain growth, reducing grain size and increasing crystal nucleation rate to realize grain refinement; meanwhile, the MAX phase particle Ti2AlC can increase the hardness of the coating, and the typical layered structure can reduce the friction coefficient of the coating. The swing laser stirring molten pool promotes the uniform distribution of the MAX phase particle and the rare earth element in the molten pool, meanwhile, the MAX phase particle gathers on the grain boundary to limit the growth of the grain from outside to inside, the rare earth element is easy to nucleate as a particle, and the grain is refined from inside to outside, and under the comprehensive action of the swing laser and the MAX phase particle and the rare earth element, the wear resistance of the coating is improved.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing, and more specifically to improving the wear resistance of tunnel boring machine cutters during laser cladding. Background Technology

[0002] The cutterhead is a critical component of a tunnel boring machine (TBM), and its quality directly determines the TBM's tunneling speed and quality. There are many types of cutterheads, broadly categorized by function as rolling cutters, cutting cutters, and scrapers. Rolling cutters play a primary role because they are used for the longest time, directly contacting the hard rock and continuously rubbing and breaking down rock particles to achieve tunneling. Cutterhead wear failure is generally caused by wear on the external structure of the cutterhead in direct contact with the rock, while the main structure of the cutterhead remains in good condition. Therefore, using remanufacturing technology to repair failed cutterheads can significantly save costs and resources.

[0003] Laser cladding (LC) is an advanced surface modification technology. Its heat source is provided by a laser, which melts and solidifies the filler material (powder, sheet, or wire) together with the surface of the shield cutter ring substrate, achieving a good metallurgical bond between the substrate and the coating, enabling remanufacturing, and thereby changing the surface properties of the substrate material, including changing hardness, corrosion resistance, and wear resistance. Summary of the Invention

[0004] This invention discloses a method for enhancing the wear resistance of tunnel boring machine (TBM) cutters using laser cladding technology. The purpose of this invention is to provide a method for comprehensively improving the wear resistance of TBM cutters during LC additive manufacturing by using a oscillating laser and MAX phase particles Ti2AlC and rare earth element Ce.

[0005] To achieve the objective of this invention, the following technical solution is adopted:

[0006] A method for enhancing the wear resistance of tunnel boring machine cutters using laser cladding technology, characterized in that:

[0007] The laser cladding device includes a computer, a laser system, a scanning galvanometer, a coaxial powder feeder, a protective gas cylinder, and a substrate. The computer is used to construct the cladding path and adjust the mode and parameters of the oscillating laser. The scanning galvanometer is used to realize the oscillation of the laser beam in different modes. The coaxial powder feeder is used to transport the mixed powder, and the protective gas cylinder injects protective gas during the processing. The computer, laser system, scanning galvanometer, and coaxial powder feeder are mounted on the substrate, and the cutting tool is fixed to the substrate by a fixture.

[0008] The cladding material is a mixture of shield machine cutter substrate powder, MAX phase particle Ti2AlC powder, and rare earth element CeO2 powder, wherein the mass ratio of substrate powder: MAX phase particle Ti2AlC powder: rare earth element CeO2 powder is 87:10:3.

[0009] The cladding process is as follows:

[0010] (1) Mix the shield machine base material powder, MAX phase particle Ti2AlC powder and rare earth element CeO2 powder in a certain proportion, and then ball mill them to fully mix the base material powder, MAX phase particle Ti2AlC and rare earth element CeO2 evenly.

[0011] (2) Set the cladding path on the computer, including the scanning trajectory, scanning spacing, and oscillating laser mode settings; then import it into the continuous laser control device;

[0012] (3) Turn on the protective gas cylinder to supply gas; load the ball-milled mixed powder into the coaxial powder feeder and adjust the powder feeding amount;

[0013] (4) The laser is turned on to scan the powder, and a deposition layer is formed by laser cladding;

[0014] (5) After the cladding is completed, turn off the laser, close the valve, remove the component, vacuum the dust, and the cladding is completed.

[0015] The scanning cladding path of the oscillating laser described in this invention includes straight lines, circles, and figure-eight shapes.

[0016] This invention addresses the issue of poor wear resistance in existing tunnel boring machine cutterhead materials by employing a method of oscillating laser and synergistic reinforcement with nanoparticles and rare earth elements to improve the wear resistance of the cutterhead.

[0017] The paths of the oscillating laser can be straight, circular, or figure-eight shaped. The oscillating behavior of the laser can achieve the following optimization effects: First, it can increase the effective area of ​​the heat source, resulting in a superior and more aesthetically pleasing cladding layer and improving the gap adaptability of laser cladding. Second, it can increase the stirring effect of the molten pool, making the distribution of MAX phase particles and rare earth elements in the molten pool more uniform, suppressing the generation of defects such as porosity and cracks. Third, it can promote non-spontaneous nucleation within the molten pool, refining the grain size.

[0018] MAX phase particles and rare earth elements have a synergistic strengthening effect. The addition of MAX phase particles Ti2AlC can, on the one hand, aggregate at grain boundaries, thus acting as a "pinning" effect to restrict grain growth. On the other hand, Ti2AlC, as a layered MAX phase material, can reduce the friction coefficient of the coating, and the TiC hard phase formed by its in-situ decomposition can increase the hardness of the coating. The rare earth element Ce can refine the grains and, on the other hand, act as nucleation sites to promote crystal nucleation, thereby refining the grains and significantly improving the wear resistance of the coating. Currently, adding nanoparticles alone often results in uneven distribution of nanoparticles in the molten pool and excessive aggregation at grain boundaries, thus reducing the toughness of the coating. Similarly, adding rare earth elements alone also results in uneven distribution of rare earth elements and insignificant grain refinement.

[0019] This invention promotes the uniform distribution of MAX phase particles and rare earth elements in the molten pool by oscillating laser stirring. At the same time, the MAX phase particles aggregate at the grain boundaries to restrict grain growth from the outside in, while the rare earth elements, as easy nucleation particles, refine the grains from the inside out. Under the combined effect of oscillating laser, MAX phase particles and rare earth elements, the wear resistance of the coating is greatly improved. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the device for enhancing the preparation of high wear-resistant tunnel boring machine cutters by the method of the present invention.

[0021] In the diagram, 1 is the computer, 2 is the continuous laser control device, 3 is the scanning galvanometer, 4 is the coaxial powder feeder, 5 is the protective gas cylinder, 6 is the substrate, and 7 is the oscillating laser. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments. These specific embodiments are further explanations of the principles of the present invention and are not intended to limit the present invention in any way. Any technology that is the same as or similar to the present invention does not exceed the scope of protection of the present invention.

[0023] like Figure 1 As shown, the present invention provides a method for enhancing the wear resistance of tunnel boring machine cutters using laser cladding technology, including a laser cladding device and its application cladding steps;

[0024] The laser cladding device includes: a computer 1, a continuous laser control device 2, a scanning galvanometer 3, a coaxial powder feeder 4, a protective gas cylinder 5, and a substrate 6. The computer 1 is used to construct the cladding path, the continuous laser control device 2 adjusts the mode and parameters of the continuous laser, the scanning galvanometer 3 melts and adds metal powder layers, the coaxial powder feeder 4 provides coaxial powder feeding during the laser cladding process, and the protective gas cylinder 5 provides protective gas during the laser cladding process.

[0025] The cladding material is a mixture of shield machine cutter substrate powder, MAX phase particle Ti2AlC powder, and rare earth element CeO2 powder.

[0026] The cladding process is as follows:

[0027] (1) Mix the shield machine base material powder, MAX phase particle Ti2AlC powder and rare earth element CeO2 powder in a certain proportion, and then ball mill them to fully mix the base material powder, MAX phase particle Ti2AlC and rare earth element CeO2 evenly.

[0028] (2) Set the cladding path on the computer, including the scanning trajectory, scanning spacing, and oscillating laser mode settings; then import it into the continuous laser control device. The specific process parameters are: oscillating laser is in figure-eight shape, power is 2400W, scanning speed is 15mm / s, spot diameter is 3.5mm, overlap rate is 50%, powder feeding rate is 6r / min, when Ti2AlC powder content is 5wt%, 10wt%, 15wt%, and CeO2 content is 1wt%, 3wt%, 5wt%;

[0029] (3) Open the protective gas cylinder to supply gas; use a scanning galvanometer and a continuous laser control device to scan the ground mixed powder, and use a coaxial powder feeder to transport the mixed powder to achieve laser cladding to form a deposition layer;

[0030] (4) After the cladding is completed, turn off the laser license, clean the powder, remove the components, vacuum the dust, and turn off the machine.

[0031] The scanning cladding path of the oscillating laser includes straight lines, circles, and figure-eight shapes.

[0032] This invention optimizes the wear resistance of the prepared shield machine material coating from both process and material aspects. First, by oscillating laser stirring the molten pool, the uniform distribution of MAX phase particles and rare earth elements in the molten pool is promoted. At the same time, the MAX phase particles aggregate at the grain boundaries to restrict grain growth from the outside to the inside. Rare earth elements, as easily nucleated particles, refine the grains from the inside to the outside. Under the combined effect of oscillating laser, nanoparticles and rare earth elements, the wear resistance of the coating is greatly improved.

[0033] This invention addresses the issue of poor wear resistance in existing tunnel boring machine cutterhead materials by proposing a method that utilizes oscillating lasers and synergistic reinforcement with MAX phase particles and rare earth elements to improve the wear resistance of the cutterhead. The oscillating laser path can be straight, circular, figure-eight shaped, or infinite. The laser oscillation behavior increases the effective area of ​​the heat source, resulting in a superior and more aesthetically pleasing cladding layer and improved gap adaptability in laser cladding; it also increases the stirring effect of the molten pool, leading to a more uniform distribution of MAX phase particles and rare earth elements within the molten pool, suppressing defects such as porosity and cracks; and it promotes non-spontaneous nucleation within the molten pool, refining the grain size.

Claims

1. A method for enhancing the wear resistance of tunnel boring machine cutters using laser cladding technology, characterized in that: The laser cladding device includes a computer, a laser system, a scanning galvanometer, a coaxial powder feeder, a protective gas cylinder, and a substrate. The computer is used to construct the cladding path and adjust the mode and parameters of the oscillating laser. The scanning galvanometer is used to realize the oscillation of the laser beam in different modes. The coaxial powder feeder is used to transport the mixed powder, and the protective gas cylinder injects protective gas during the processing. The computer, laser system, scanning galvanometer, and coaxial powder feeder are mounted on the substrate, and the cutting tool is fixed to the substrate by a fixture. The cladding material is a mixture of shield machine cutter substrate powder, MAX phase particle Ti2AlC powder, and rare earth element CeO2 powder, wherein the mass ratio of substrate powder: MAX phase particle Ti2AlC powder: rare earth element CeO2 powder is 87:10:

3. The cladding process is as follows: (1) Mix the shield machine cutter substrate powder, MAX phase particle Ti2AlC powder and rare earth element CeO2 powder in a certain proportion, and then ball mill them to fully mix the substrate powder, MAX phase particle Ti2AlC and rare earth element CeO2 evenly. (2) Set the cladding path on the computer, including the scanning trajectory, scanning spacing, and oscillating laser mode settings; then import it into the continuous laser control device; (3) Open the protective gas cylinder to supply gas; load the mixed powder after ball milling into the coaxial powder feeder and adjust the powder feeding amount; (4) The laser is turned on to scan the powder, and a deposition layer is formed by laser cladding; (5) After the cladding is completed, turn off the laser, close the valve, remove the component, vacuum the dust, and the cladding is completed.

2. The method for enhancing the wear resistance of tunnel boring machine cutters using laser cladding technology according to claim 1, characterized in that: The scanning cladding path of the oscillating laser includes straight lines, circles, and figure-eight shapes.

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