A laser cladding method for a valve seat sealing surface

Abstract

The application provides a laser cladding method for a valve seat sealing surface, and comprises the following steps: firstly, a groove required for machining is opened on the valve seat sealing surface according to the valve seat specification; then, laser cladding is performed on the valve seat sealing surface by using coaxial wire feeding type laser according to the wire material selected according to the valve seat sealing surface material; then, the slag is removed, the powder is selected according to the valve seat sealing surface material, and the powder is prepositioned by using a powder laying device; finally, the prepositioned powder is irradiated by using a rectangular light spot. Relying on laser melting wire-laser melting powder collaborative machining, an alloy element content distribution reasonable and macroscopic morphology close to the requirements of the finished product cladding layer is obtained.

Description

A laser cladding method for valve seat sealing surfaces Technical Field

[0001] This invention belongs to the field of surface modification technology, and specifically relates to a laser cladding method for valve seat sealing surfaces. Background Technology

[0002] Valves are devices that control the direction, pressure, and flow rate of fluids. The valve seat is a key component of a valve, primarily responsible for forming a seal when the valve is closed to prevent fluid leakage. The valve sealing surface, as the core area on the valve seat for achieving fluid sealing, directly affects the valve's sealing performance and service life. Therefore, surface modification techniques are needed to improve the wear resistance and corrosion resistance of the valve seat sealing surface.

[0003] Currently, surface modification processes for valve seat sealing surfaces mainly include welding and laser cladding. Welding typically uses an electric arc as the heat source and wire as the raw material. For example, patent application number CN201510326842.0 proposes a process for welding stainless steel sealing surfaces onto ductile iron valve substrates. The welded sealing surfaces exhibit reliable strength, stable performance, and are free from defects such as porosity and cracks. The welding material utilization rate is high, and the process is simple and convenient to operate. However, welding often suffers from problems such as high dilution rates and severe thermal deformation. Therefore, laser cladding, with its advantages of low dilution rates and minimal thermal deformation, shows broad application prospects in the field of valve seat sealing surface processing. For example, patent application CN202411646134.0 proposes a nickel-based superalloy, a valve sealing surface containing the same, and a method for preparing the valve sealing surface. Through optimization and design of the chemical composition of the nickel-based superalloy, a powder-feeding laser cladding process is used to enable the valve sealing surface to withstand the alternating stress generated by frequent contact and impact between the valve core and valve seat, as well as steam erosion, thereby significantly improving the reliability and lifespan of the high-temperature and high-pressure valve sealing surface. It can be observed that existing laser cladding processes struggle to meet the high-quality, low-cost surface modification requirements of valve seats. This is mainly because the macroscopic morphology of the cladding layer under existing laser cladding processes differs significantly from the finished product dimensions, resulting in a large workload for subsequent machining. Furthermore, the powder-feeding laser cladding process suffers from low raw material utilization and a thin cladding layer.

[0004] Therefore, this patent proposes a laser cladding method for valve sealing surfaces, which achieves a smooth cladding layer surface and a reasonable distribution of alloy elements through the synergistic processing of laser filament and laser powder, providing a high-quality and low-cost solution for the surface modification of valve seats. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by proposing a laser cladding method for valve seat sealing surfaces. This method, based on the synergistic processing of laser filament and laser powder, offers advantages such as a smooth cladding layer surface, reasonable elemental content distribution, high quality, and low cost. To achieve the above objectives, the technical solution of this invention is as follows:

[0006] (1) Grooving: Grooves are made at the locations where the valve seat needs to be surface-strengthened. The groove depth is 2.3 to 3.5 mm and the bottom width of the groove is 5 to 12 mm.

[0007] (2) Construction of laser cladding optical path system: A ring-shaped spot suitable for laser filament processing is formed by using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder processing is formed by using a microlens array;

[0008] Specifically, the laser cladding optical path system consists of a collimating lens, a double-sided ring-shaped reflecting integrator, a wire processing homogenizing integrator, a wire processing focusing lens, a wire processing protective lens, a powder processing reflecting mirror, a powder processing microlens I, a powder processing microlens II, a powder processing focusing lens, and a powder processing protective lens. After passing through the collimating lens, the laser beam passes through the double-sided ring-shaped reflecting integrator, which splits the incident beam into several sub-beams and selectively reflects them onto the wire processing homogenizing integrator, forming two symmetrically spaced semi-annular beams. This provides sufficient space for the wire feeding device to pass through. The wire processing homogenizing integrator merges the two incident semi-annular beams into a single ring and homogenizes them before passing through... The wire-processing focusing lens focuses the light to obtain an annular beam with an inner diameter of 1.7±0.2mm and a ring width of 0.4~0.7mm. At the same time, the wire-processing protective lens prevents spatter from damaging the internal lenses. When switching from laser wire-processing to laser powder-processing, the double-sided annular reflecting integrator is rotated 90° counterclockwise. The collimated beam is reflected twice by the double-sided annular reflecting integrator and the powder-processing reflector and enters the powder-processing microlens I, powder-processing microlens II and powder-processing focusing lens. At the same time, by adjusting the distance between powder-processing microlens I and powder-processing microlens II, a rectangular spot with variable spot size and uniform spot energy distribution is obtained.

[0009] (3) Laser wire melting: Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 1200-2700W, the scanning speed is 8-12mm / s, the wire feeding speed is 35-55mm / s, the overlap rate is 30%-60%, and the protective gas is argon.

[0010] (4) Powder pre-setting: The powder pre-setting treatment is performed on the valve seat sealing surface after laser filament processing using an integrated powder conveying and roller pressing device;

[0011] Specifically, the powder conveying-roller pressing integrated device consists of a powder feeding body, a power mechanism, a lifting block, a powder feeding connector, rollers, and roller limit frames. The power mechanism consists of a fixed bracket, a motor, a small bevel gear, a screw, and a large bevel gear. The device is fixed to the powder feeding laser processing head by the clamping structure of the powder feeding body. Its installation height is based on the bottom of the roller contacting the valve seat surface and the bottom of the processing head being higher than the valve seat surface. The specific powder spreading operation process is as follows: Powder is fed out from the powder feeder, fed into the powder feeding body through the powder feeding connector, and then fed out through the powder feeding nozzle of the powder feeding body. The power mechanism controls the rollers to press the powder downward to reduce gaps. Finally, the three-axis motion platform controls the powder feeding laser processing head to move in a ring around the valve seat sealing surface. The combination of these three steps achieves powder spreading.

[0012] (5) Laser powder melting process: The pre-placed powder is irradiated using a rectangular spot. The laser power is 4200-5500W, the scanning speed is 3-7mm / s, and the protective gas is argon.

[0013] According to the above technical solution, in the preferred case, the slope angle of the groove in step (1) is 20±3°.

[0014] According to the above technical solution, in the preferred case, the uniformity of the energy distribution of the annular spot and the rectangular spot in step (2) is not less than 95%.

[0015] According to the above technical solution, in the preferred case, the length of the rectangular light spot in step (2) is 6 to 20 mm and the width is 2 to 5 mm.

[0016] According to the above technical solution, in the preferred case, the rotation of the double-sided ring-shaped reflective integrator (12) in step (2) is achieved by stepper motor control.

[0017] According to the above technical solution, in the preferred case, in step (3), if the valve seat material is carbon steel, the wire material is selected with 0.08%≤C≤0.15%, 11.0%≤Cr≤13.0%, 0.5%≤Mn≤1.5%, 0.1%≤Ni≤0.2%, 0.5%≤Si≤1.5%, and Fe balance; if the valve seat material is stainless steel, the wire material is selected with 0.9%≤C≤1.4%, 27.0%≤Cr≤29.0%, 3.5%≤W≤4.5%, Ni≤3.0%, Si≤1.5%, and Co balance.

[0018] According to the above technical solution, in a preferred case, the particle size of the spherical powder in step (4) is 53 to 150 μm.

[0019] According to the above technical solution, in the preferred case, before pre-powdering in step (4), a bowl-shaped steel wire wheel head angle grinder is needed to remove the surface slag shell of the laser filament layer.

[0020] According to the above technical solution, in the preferred case, in step (5), if the valve seat material is carbon steel, the powder should be 0.08%≤C≤0.15%, 13.0%≤Cr≤15.0%, 0.5%≤Mn≤1.5%, 0.2%≤Ni≤0.3%, 0.5%≤Si≤1.5%, with Fe as the balance; if the valve seat material is stainless steel, the powder should be 0.9%≤C≤1.4%, 29.0%≤Cr≤31.0%, 4.5%≤W≤5.5%, Ni≤3.0%, Si≤1.5%, with Co as the balance.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) In view of the surface modification processing requirements of valve seat sealing surface, the present invention proposes a laser filament-laser powder synergistic processing method, that is, the online switching of the annular spot and the rectangular spot is realized by flipping the double-sided ring-shaped reflective integrator. On the one hand, the bottom of the cladding layer with relatively low alloy element content and excellent forming quality is obtained by laser filament process with high raw material utilization rate; on the other hand, the macroscopic morphology of the cladding layer is close to the finished product requirements by using powder pre-placement + rectangular homogenization spot irradiation, which significantly reduces the amount of subsequent machining work.

[0023] (2) The present invention involves directly spreading and compacting powder on the laser filament layer, followed by laser irradiation, thereby greatly improving the utilization rate of powder. At the same time, the compacted pre-placed powder will reduce the number of pores in the cladding layer. Attached Figure Description

[0024] Figure 1 shows the optical path system of the laser cladding head.

[0025] Figure 2 is a three-dimensional isometric view of the powder spreading device;

[0026] Figure 3 is a three-dimensional isometric view of the power mechanism of the powder spreading device; Detailed Implementation

[0027] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0028] The hardness of the laser cladding coating of the present invention was tested on a hardness tester in accordance with the standard GB / T 230.1-2018.

[0029] The porosity of the laser cladding layer of the present invention was tested using a metallographic microscope in accordance with the GB / T 3488.4-2022 standard.

[0030] The dilution rate of the laser cladding layer of the present invention was tested using a metallographic microscope in accordance with the GB / T 40737-2021 standard.

[0031] A laser cladding method for valve seat sealing surfaces according to the present invention is illustrated in the following specific implementation example:

[0032] Example 1

[0033] (1) Before cladding, grooves are made at the position of the valve seat to be surface strengthened. The groove depth is 2.3mm, the bottom width of the groove is 5mm, and the slope angle of the groove is 17°.

[0034] (2) A ring-shaped spot suitable for laser filament processing is formed using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder processing is formed using a microlens array; the inner diameter of the ring-shaped spot is 1.5 mm and the ring width is 0.4 mm; the rectangular spot is 6 mm long and 2 mm wide.

[0035] (3) The valve seat material is A105 carbon steel, the wire composition is 0.08% C, 11.7% Cr, 0.94% Mn, 0.16% Ni, 1.04% Si, with Fe as the balance. Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 2100W, the scanning speed is 9mm / s, the wire feeding speed is 40mm / s, the overlap rate is 60%, and the protective gas is argon.

[0036] (4) After removing the slag shell generated by laser filament processing, the powder composition is 0.11% C, 14.1% Cr, 0.5% Mn, 0.3% Ni, 1.2% Si, with Fe as the balance. The powder pre-treatment is carried out on the valve seat sealing surface after laser filament processing using an integrated powder conveying and rolling device.

[0037] (5) Irradiate the pre-placed powder using a rectangular spot. The laser power is 4200W, the scanning speed is 5mm / s, and the protective gas is argon.

[0038] This embodiment utilizes laser filament-laser powder co-processing to achieve laser cladding treatment on the valve seat sealing surface. The cladding layer has a dilution rate of 8.9%, a porosity of 0.9%, and a hardness of 38.6 HRC.

[0039] Example 2

[0040] (1) Before cladding, grooves are made at the position of the valve seat to be surface strengthened. The groove depth is 2.5mm, the bottom width of the groove is 7mm, and the slope angle of the groove is 20°.

[0041] (2) A ring-shaped spot suitable for laser wire melting is formed by using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder melting is formed by using a microlens array; the inner diameter of the ring-shaped spot is 1.7 mm and the ring width is 0.5 mm; the rectangular spot is 9 mm long and 3 mm wide.

[0042] (3) The valve seat material is A105 carbon steel, and the wire composition is 0.15% C, 12.7% Cr, 1.48% Mn, 0.11% Ni, 0.54% Si, with Fe as the balance. Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 1200W, the scanning speed is 8mm / s, the wire feeding speed is 35mm / s, the overlap rate is 40%, and the protective gas is argon.

[0043] (4) After removing the slag shell generated by laser filament processing, the powder composition is 0.08% C, 14.9% Cr, 1.4% Mn, 0.2% Ni, 0.6% Si, with Fe as the balance. The powder pre-treatment is carried out on the valve seat sealing surface after laser filament processing using an integrated powder conveying and rolling device.

[0044] (5) Irradiate the pre-placed powder using a rectangular spot with a laser power of 4500W, a scanning speed of 3mm / s, and argon as the protective gas.

[0045] This embodiment utilizes laser filament-laser powder co-processing to achieve laser cladding treatment on the valve seat sealing surface. The cladding layer has a dilution rate of 8.2%, a porosity of 0.8%, and a hardness of 39.4 HRC.

[0046] Example 3

[0047] (1) Before cladding, grooves are made at the position of the valve seat to be surface strengthened. The groove depth is 3.5mm, the bottom width of the groove is 12mm, and the slope angle of the groove is 23°.

[0048] (2) A ring-shaped spot suitable for laser wire melting is formed by using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder melting is formed by using a microlens array; the inner diameter of the ring-shaped spot is 1.7 mm and the ring width is 0.6 mm; the rectangular spot is 20 mm long and 5 mm wide.

[0049] (3) The valve seat material is 316 stainless steel, the wire composition is 0.9% C, 28.7% Cr, 4.4% W, 2.7% Ni, 1.2% Si, with Co as the balance. Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 2700W, the scanning speed is 12mm / s, the wire feeding speed is 55mm / s, the overlap rate is 30%, and the protective gas is argon.

[0050] (4) After removing the slag shell generated by laser filament processing, the powder composition is 0.9% C, 30.8% Cr, 5.4% W, 2.9% Ni, 1.3% Si, with Co as the balance. The powder pre-treatment is carried out on the valve seat sealing surface after laser filament processing using an integrated powder conveying and rolling device.

[0051] (5) The pre-placed powder is irradiated using a rectangular spot with a laser power of 5500W, a scanning speed of 5mm / s, and argon as the protective gas.

[0052] This embodiment utilizes laser filament-laser powder co-processing to achieve laser cladding treatment on the valve seat sealing surface. The cladding layer has a dilution rate of 8.4%, a porosity of 0.9%, and a hardness of 44.8 HRC.

[0053] Example 4

[0054] (1) Before cladding, grooves are made at the position of the valve seat to be surface strengthened. The groove depth is 2.7mm, the bottom width of the groove is 9mm, and the slope angle of the groove is 20°.

[0055] (2) A ring-shaped spot suitable for laser wire melting is formed by using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder melting is formed by using a microlens array; the inner diameter of the ring-shaped spot is 1.9 mm and the ring width is 0.7 mm; the rectangular spot is 12 mm long and 4 mm wide.

[0056] (3) The valve seat material is 316 stainless steel, the wire composition is 1.3% C, 27.2% Cr, 3.6% W, 0.1% Ni, 0.3% Si, with Co as the balance. Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 2100W, the scanning speed is 10mm / s, the wire feeding speed is 45mm / s, the overlap rate is 40%, and the protective gas is argon.

[0057] (4) After removing the slag shell generated by laser filament processing, the powder composition is 1.4% C, 29.2% Cr, 4.7% W, 0.2% Ni, 1.1% Si, with Co as the balance. The powder pre-treatment is carried out on the valve seat sealing surface after laser filament processing using an integrated powder conveying and rolling device.

[0058] (5) The pre-placed powder was irradiated using a rectangular spot with a laser power of 5100W, a scanning speed of 7mm / s, and argon as the protective gas.

[0059] This embodiment utilizes laser filament-laser powder co-processing to achieve laser cladding treatment on the valve seat sealing surface. The cladding layer has a dilution rate of 9.7%, a porosity of 0.7%, and a hardness of 41.3 HRC.

[0060] Example 5

[0061] (1) Before cladding, grooves are made at the position of the valve seat to be surface strengthened. The groove depth is 3.0 mm, the bottom width of the groove is 10 mm, and the slope angle of the groove is 20°.

[0062] (2) A ring-shaped spot suitable for laser wire melting is formed by using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder melting is formed by using a microlens array; the inner diameter of the ring-shaped spot is 1.7 mm and the ring width is 0.6 mm; the rectangular spot is 15 mm long and 4 mm wide.

[0063] (3) The valve seat material is 316 stainless steel, and the wire composition is 1.1% C, 28.1% Cr, 3.9% W, 1.8% Ni, 0.8% Si, with Co as the balance. Laser wire melting is carried out by optical coaxial wire feeding method. The laser power is 2100W, the scanning speed is 10mm / s, the wire feeding speed is 45mm / s, the overlap rate is 40%, and the protective gas is argon.

[0064] (4) After removing the slag shell generated by laser filament processing, the powder composition is 1.0% C, 30.2% Cr, 5.1% W, 1.7% Ni, 1.2% Si, with Co as the balance. The powder pre-treatment is carried out on the valve seat sealing surface after laser filament processing using an integrated powder conveying and rolling device.

[0065] (5) The pre-placed powder is irradiated using a rectangular spot. The laser power is 4200W, the scanning speed is 4mm / s, and the protective gas is argon.

[0066] This embodiment utilizes laser filament-laser powder co-processing to achieve laser cladding treatment on the valve seat sealing surface. The cladding layer has a dilution rate of 9.4%, a porosity of 0.7%, and a hardness of 42.7 HRC.

Claims

1. A laser cladding method for a valve seat sealing surface, characterized in that, The process includes the following steps: (1) Grooving: Grooving is performed at the position where the valve seat needs to be surface strengthened. The groove depth is 2.3-3.5 mm and the bottom width of the groove is 5-12 mm; (2) Construction of the laser cladding optical path system: A ring-shaped spot suitable for laser wire cladding is formed using a copper integrating mirror, and a flat-top rectangular spot suitable for laser powder cladding is formed using a microlens array; Specifically, the laser cladding optical path system consists of a collimating mirror (11), a double-sided ring-shaped reflecting integrating mirror (12), a wire cladding homogenizing integrating mirror (13), a wire cladding focusing mirror (14), a wire cladding protective mirror (15), a powder cladding reflecting mirror (16), and a powder cladding... The system consists of microlens I (17), powder processing microlens II (18), powder processing focusing lens (19), and powder processing protective lens (110). After passing through collimating lens (11), the laser beam passes through double-sided ring-shaped reflecting integrator (12), which splits the incident beam into several sub-beams and selectively reflects them onto wire processing homogenizing integrator (13) to form two symmetrically spaced semi-circular beams, providing sufficient space for the wire feeding device to pass through. The wire processing homogenizing integrator (13) merges the two incident semi-circular beams into a ring and performs homogenization treatment. Then, the beam is focused by wire processing focusing lens (14) to obtain an inner diameter of 1.7±0.2mm and a ring width of 0.4~0.A 7mm annular beam is used, and a wire-processing protective mirror (15) is used to prevent spatter from damaging the internal lenses. When switching from laser wire-processing to laser powder-processing, the double-sided annular reflecting integrator (12) is rotated 90° counterclockwise so that the collimated beam enters the powder-processing microlens I (17), powder-processing microlens II (18) and powder-processing focusing mirror (19) after two reflections by the double-sided annular reflecting integrator (12) and the powder-processing reflecting mirror (16). At the same time, the distance between powder-processing microlens I (17) and powder-processing microlens II (18) is adjusted. (2) Spacing, to obtain a rectangular spot with variable spot size and uniform spot energy distribution; (3) Laser filament processing: Laser filament processing is carried out by optical coaxial wire feeding method, with laser power of 1200~2700W, scanning speed of 8~12mm / s, wire feeding speed of 35~55mm / s, overlap rate of 30%~60%, and protective gas of argon; (4) Powder pre-setting: Powder pre-setting treatment is carried out on the valve seat sealing surface after laser filament processing by powder conveying-roller pressing integrated device; Specifically, powder conveying-roller pressing integrated device It consists of a powder feeding body (21), a power mechanism (22), a lifting block (23), a powder feeding connector (24), a roller (25), and a roller limiting frame (26); the power mechanism (22) consists of a fixed bracket (221), a motor (222), a small bevel gear (223), a screw (224), and a large bevel gear (225); the device is fixed to the powder feeding laser processing head by the clamping structure of the powder feeding body, and its installation height is based on the bottom of the roller contacting the surface of the valve seat and the bottom of the processing head being higher than the surface of the valve seat; the specific powder spreading operation process is as follows: The powder is fed from the powder feeder, through the powder feeding connector (24) into the powder feeding body (21), and then fed out through the powder feeding nozzle of the powder feeding body (21). The roller (25) is controlled by the power mechanism (22) to press the powder downward to reduce the gap. Finally, the powder feeding laser processing head is controlled by the three-axis motion platform to move in a ring around the valve seat sealing surface. The three actions are combined to achieve powder spreading. (5) Laser powder melting processing: The pre-placed powder is irradiated with a rectangular spot. The laser power is 4200-5500W, the scanning speed is 3-7mm / s, and the protective gas is argon.

2. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (1), the slope angle of the groove is 20±3°.

3. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (2), the uniformity of the energy distribution of the annular and rectangular light spots is not less than 95%.

4. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (2), the length of the rectangular light spot is 6-20 mm and the width is 2-5 mm.

5. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (2), the rotation of the double-sided ring-shaped reflecting integrator (12) is achieved by stepper motor control.

6. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (3), if the valve seat material is carbon steel, the wire material should be 0.08%≤C≤0.15%, 11.0%≤Cr≤13.0%, 0.5%≤Mn≤1.5%, 0.1%≤Ni≤0.2%, 0.5%≤Si≤1.5%, with Fe as the balance; if the valve seat material is stainless steel, the wire material should be 0.9%≤C≤1.4%, 27.0%≤Cr≤29.0%, 3.5%≤W≤4.5%, Ni≤3.0%, Si≤1.5%, with Co as the balance.

7. The laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (4), the powder is spherical with a particle size of 53–150 μm.

8. A laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, Before pre-powdering in step (4), a bowl-shaped steel wire wheel head angle grinder is needed to remove the surface slag shell of the laser filament layer.

9. A laser cladding method for a valve seat sealing surface according to claim 1, characterized in that, In step (5), if the valve seat material is carbon steel, the powder should be 0.08%≤C≤0.15%, 13.0%≤Cr≤15.0%, 0.5%≤Mn≤1.5%, 0.2%≤Ni≤0.3%, 0.5%≤Si≤1.5%, with Fe as the balance; if the valve seat material is stainless steel, the powder should be 0.9%≤C≤1.4%, 29.0%≤Cr≤31.0%, 4.5%≤W≤5.5%, Ni≤3.0%, Si≤1.5%, with Co as the balance.

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