Light filament coaxial laser cladding method facing valve sealing surface

Abstract

The invention provides a smooth wire coaxial laser cladding method for a valve sealing surface, which is characterized in that a wire for smooth wire coaxial laser cladding, which has the diameter of 1.2-1.6 mm and is suitable for valve substrates made of carbon steel and stainless steel, is obtained through a bending-powder feeding-rolling sealing-diameter reducing process on the basis of optimal design of chemical components of a powder core wire. Afterwards, annular light spots are used for conducting preheating treatment on the powder core wire before laser cladding, meanwhile, double annular light spots with independently-adjustable middle core power / ring core power are adopted for conducting coaxial laser cladding forming on the powder core wire, the single-layer cladding thickness reaches 2-4.5 mm, the splashing phenomenon is eliminated, and the stability of a molten pool is improved; and high-quality and high-efficiency surface hardening treatment of the sealing surface of the valve is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cladding, and in particular relates to a light filament coaxial laser cladding method facing a valve sealing surface. Background Art

[0002] The sealing surface is the most critical working surface of the valve. It is mainly used to control the medium in pipelines and equipment. It has the advantages of small fluid resistance, good sealing performance, quick and easy opening and closing, and no restrictions on installation direction. The quality of the sealing surface directly affects the service life of the valve. How to improve the service performance of the sealing surface through surface engineering technology has become a key common problem that needs to be solved in the valve industry. At present, the sealing surface of the valve is mainly processed by manual surfacing, which has problems such as high dilution rate, severe thermal deformation, high labor intensity, and poor working environment. Although the powder feeding / powder spreading laser cladding technology has the advantages of extremely low dilution rate, small heat-affected zone, small workpiece deformation, and easy automation, it uses atomized spherical powder as raw material, and the powder utilization rate is low, resulting in high processing costs.

[0003] To this end, researchers proposed the technical concept of "replacing powder with wire", that is, wire feeding laser cladding process. According to the spatial position relationship between the supply wire and the laser beam, the wire feeding laser cladding process can be divided into two categories: coaxial wire feeding and side-axis wire feeding. Among them, the side-axis wire feeding laser cladding method has the problem of limited processing path, and the valve sealing surface is often a spatial curved surface, so the coaxial wire feeding laser cladding process is more suitable for the valve sealing surface. At present, the patent with application number 201911411770.4 proposes an optical path splitting unit and its coaxial wire feeding cladding head, that is, the incident light beam is formed into multiple split light paths by a splitting unit, and then the spatial angle between the split light beam and the wire is adjusted by an adjustable reflector, so as to realize the focusing of the split light beam on the wire extending from the coaxial wire feeding nozzle; the patent with application number 201810376757.9 proposes a coaxial wire feeding cladding head for laser metal printing, which realizes the coaxialization of the wire and the annular hollow beam by the synergistic effect of a beam expander, a collimator, a conical mirror, an annular beam splitter, a reflector, a focusing mirror, etc. However, when the above patent implements the coaxial wire feeding laser cladding processing, the temperature difference between the molten pool and its surroundings is large, which is very easy to produce molten pool splashing and other phenomena. At the same time, the wire is not preheated before laser cladding processing, and the laser damage threshold of the optical lens in the wire-feeding laser cladding processing head is limited. Therefore, the existing wire-feeding laser cladding technology often has the problem of limited single-layer cladding thickness, that is, the laser cladding efficiency is low.

[0004] The patent of this invention is based on the chemical composition design of the powder core wire, and proposes a ring preheating light-double ring forming light coupled light wire coaxial laser cladding method for the valve sealing surface to improve the molten pool stability and laser cladding deposition efficiency, significantly increase the single-layer cladding thickness and improve the cladding quality. Summary of the invention

[0005] Based on the above background technology analysis, the patent of this invention proposes a light filament coaxial laser cladding technology method of annular spot preheating-double annular spot forming to reduce molten pool splashing, improve molten pool stability, increase laser cladding deposition efficiency, etc., to meet the needs of high-efficiency and high-quality laser cladding processing of valve sealing surfaces.

[0006] In order to achieve the above objectives, the technical solution of the present invention is:

[0007] A method for coaxial laser cladding of light filaments facing the valve sealing surface is carried out according to the following steps:

[0008] (1) Powder core wire composition design: For valve bases made of carbon steel and stainless steel, powder core wire consisting of outer skin and core powder is used for coaxial laser cladding. Among them, for the carbon steel substrate, low carbon steel is selected as the outer skin, and the core powder composition is 0.15%≤C≤0.20%, 16.5%≤Cr≤26.5%, 7.5%≤Ni≤10.5%, 2.5%≤Mo≤4.5%, 1.5%≤W≤3.5%, 0.15%≤Ti≤0.35%, 0.40%≤V≤0.85%, 0.40%≤Nb≤0.85%, and Fe is the balance; for the stainless steel substrate, a high-purity cobalt strip is selected as the outer skin, and the core powder composition is 0.95%≤C≤1.70%, 28.0%≤Cr≤41%, 0.80%≤Si≤1.30%, 3.60%≤W≤10.50%, Mo≤0.45%, 0.70%≤Ni≤1.80%, Mn≤1.05%, and Co is the balance.

[0009] (2) Preparation of powder core wire: A 5.5-8 mm wide low carbon steel / cobalt strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.2-1.6 mm is obtained by multiple sets of reducing wheels.

[0010] (3) Construction of the optical path system for filament coaxial laser cladding: An annular light spot is used to preheat the powder core wire, and a double annular homogenized light spot is used to implement filament coaxial laser cladding forming.

[0011] Specifically, the filament coaxial laser cladding optical path system consists of a preheating collimator (1), a preheating reflector (2), a preheating cone lens group (3), a preheating beam splitter (4), a preheating reflector (5), a composite mirror (6), a forming beam splitter (7), a forming cone lens group (8), a forming collimator (9), a forming reflector (10), a beam splitter (11) and a focusing mirror (12).

[0012] The preheating laser beam is collimated by a preheating collimator (1) and then enters a preheating cone lens group (3) through a preheating reflector (2). The beam passes through the preheating cone lens group (3) to transform a circular beam into an annular beam. The diameter of the annular beam can be adjusted by changing the cone lens spacing. The preheating beam splitter (4) performs symmetrical open-loop processing on the annular beam. After passing through a preheating reflector (5) with a wire feeding hole and a beam combiner (6), the annular beam is coaxial with the forming beam. Finally, the preheating beam is closed through a beam splitter (11) and a focusing lens (12) and focused on the surface of the wire to achieve preheating of the laser cladding wire.

[0013] The shaping laser beam is a double annular light spot with independently adjustable center core power and ring core power. After being collimated by a collimator (9), it is reflected by a shaping reflector (10) into a shaping cone lens group (8) to obtain an annular homogenized light spot whose light spot size can be changed based on the cone lens spacing control. After open-loop processing by a shaping beam splitter prism (7), reflection by a beam combiner (6) with a wire feeding hole, and closed-loop processing by a beam splitter prism (11), the shaping laser beam is finally focused into an annular light spot by a focusing lens (12), so that the high-energy annular light spot acts on the wire and the substrate to realize the coaxial laser cladding processing of the light wire.

[0014] (4) Coaxial laser cladding of light wire: First, the valve sealing surface is grooved at the position to be laser clad, with a groove depth of 1.5 to 2.0 mm. Then, the powder core wire is preheated using an annular preheating light with a laser power of 400 to 900 W. Finally, the preheated powder core wire enters the double annular forming light irradiation area for coaxial laser cladding. The inner core power of the double annular forming light is 1100 to 2300 W, and the outer core power is 700 to 1400 W.

[0015] According to the above technical solution, preferably, the particle size of the medicine core powder in step (2) is controlled to be 60-100 meshes.

[0016] According to the above technical solution, preferably, after the shaping and homogenization treatment in step (3), the uniformity of the spot energy distribution of the preheating light and the shaping light is greater than or equal to 95%.

[0017] According to the above technical solution, preferably, in step (4), the scanning speed is 9-15 mm / s, the wire feeding speed is 35-55 mm / s, the overlap rate is 30%-60%, and the shielding gas is argon.

[0018] According to the above technical solution, preferably, the thickness of the single layer cladding in step (4) is 2 to 4.5 mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The patent of this invention uses an annular spot to preheat the wire, and uses a double annular spot with independently adjustable core power and ring core power to implement coaxial laser cladding of the wire to eliminate spatter, improve the stability of the molten pool and increase the thickness of the single-layer cladding. In addition, both the preheating light and the forming light have the characteristics of adjustable spot size, thus meeting the needs of coaxial laser cladding of wires of multiple specifications.

[0021] The patent of this invention proposes a corresponding control range of the chemical composition of powder core wire for valve sealing surfaces based on carbon steel and stainless steel, so as to meet the use requirements of the valve sealing surface in terms of wear resistance, corrosion resistance, etc. during service.

[0022] In the filament coaxial laser cladding method proposed in the patent of the present invention, after the wire is acted upon by the preheating beam, it immediately enters the double-annular forming light irradiation area, that is, the preheated wire can be laser clad within a very short time interval, which means that the preheating effect can significantly reduce the laser power requirement of the forming light and increase the single-layer cladding thickness, while reducing the thermal effect and spot distortion of the optical lens caused by preheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the optical path system design diagram for the light wire coaxial laser cladding method for the valve sealing surface; DETAILED DESCRIPTION

[0024] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0025] The hardness test of the laser cladding coating of the present invention was carried out on a Rockwell hardness tester in accordance with GB / T 230.1-2018 standard.

[0026] According to a light filament coaxial laser cladding method facing the valve sealing surface of the present invention, the specific implementation case is as follows:

[0027] Example 1

[0028] (1) The valve base material is A105 carbon steel, the wire sheath is Q235 steel strip, and the core powder composition is C 0.15%, Cr16.5%, Ni 7.5%, Mo 2.5%, W 1.5%, Ti 0.15%, V 0.40%, Nb 0.40%, and the balance Fe.

[0029] (2) The 8 mm wide Q235 steel strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated 60-100 mesh core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.6 mm is obtained by multiple sets of reducing wheels.

[0030] (3) After the preheating laser beam passes through the preheating collimator, preheating reflector, preheating conical lens group, preheating beam splitter, preheating reflector and beam combiner, it is coaxial with the forming beam. Finally, the preheating beam is closed by the beam splitter and focusing lens and focused on the wire surface to achieve preheating treatment of the laser cladding wire. The uniformity of the energy distribution of the preheating beam spot is ≥95%.

[0031] The shaping laser beam is a double annular spot with independently adjustable core power and ring core power. After passing through a collimator, a shaping reflector, and a shaping conical lens group, a ring-shaped homogenized spot is obtained, which can change the spot size based on the conical lens spacing. After the open-loop processing of the shaping beam splitter prism, the reflection of the beam combiner with a wire feeding hole, and the closed-loop processing of the beam splitter prism, the shaping laser beam is finally focused into an annular spot through a focusing lens, so that the high-energy annular spot acts on the wire and the substrate, and the uniformity of the spot energy distribution is ≥95%.

[0032] (4) First, the valve sealing surface was grooved at the position to be laser clad, with a groove depth of 1.7 mm. Then, the powder core wire was preheated using an annular preheating light, with a laser power of 650 W. Finally, the preheated powder core wire entered the double annular forming light irradiation area for coaxial laser cladding processing. The inner core power of the double annular forming light was 1800 W, the outer core power was 1000 W, the scanning speed was 10 mm / s, the wire feeding speed was 40 mm / s, the overlap rate was 40%, and the shielding gas was argon.

[0033] In this embodiment, the carbon steel valve sealing surface is surface hardened by using a light wire coaxial laser cladding method. The thickness of a single layer of cladding is 3.9 mm, and the hardness of the cladding layer is 38.7 HRC.

[0034] Example 2

[0035] (1) The valve base material is A105 carbon steel, the wire sheath is Q235 steel strip, and the core powder composition is C 0.21%, Cr17.2%, Ni 8.2%, Mo 3.3%, W2.1%, Ti 0.22%, V 0.47%, Nb 0.51%, and the balance Fe.

[0036] (2) A 7 mm wide Q235 steel strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated 60-100 mesh core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.2 mm is obtained by passing through multiple sets of reducing wheels.

[0037] (3) After the preheating laser beam passes through the preheating collimator, preheating reflector, preheating conical lens group, preheating beam splitter, preheating reflector and beam combiner, it is coaxial with the forming beam. Finally, the preheating beam is closed by the beam splitter and focusing lens and focused on the wire surface to achieve preheating treatment of the laser cladding wire. The uniformity of the energy distribution of the preheating beam spot is ≥95%.

[0038] The shaping laser beam is a double annular spot with independently adjustable core power and ring core power. After passing through a collimator, a shaping reflector, and a shaping conical lens group, a ring-shaped homogenized spot is obtained, which can change the spot size based on the conical lens spacing. After the open-loop processing of the shaping beam splitter prism, the reflection of the beam combiner with a wire feeding hole, and the closed-loop processing of the beam splitter prism, the shaping laser beam is finally focused into an annular spot through a focusing lens, so that the high-energy annular spot acts on the wire and the substrate, and the uniformity of the spot energy distribution is ≥95%.

[0039] (4) First, the valve sealing surface was grooved at the position to be laser clad, with a groove depth of 1.7 mm. Then, the powder core wire was preheated using an annular preheating light, with a laser power of 550 W. Finally, the preheated powder core wire entered the double annular forming light irradiation area for coaxial laser cladding processing. The inner core power of the double annular forming light was 1600 W, the outer core power was 900 W, the scanning speed was 9 mm / s, the wire feeding speed was 50 mm / s, the overlap rate was 40%, and the shielding gas was argon.

[0040] In this embodiment, the carbon steel valve sealing surface is surface hardened by using a light wire coaxial laser cladding method. The thickness of a single layer of cladding is 3.4 mm, and the hardness of the cladding layer is 39.4 HRC.

[0041] Example 3

[0042] (1) The valve base is made of 316 stainless steel, the outer skin of the wire is a high-purity cobalt strip, and the core powder composition is C1.22%, Cr 39.2%, Si 1.07%, W 8.7%, Mo 0.32%, Ni 1.32%, Mn 0.57%, and the balance is Co.

[0043] (2) A 7 mm wide high-purity cobalt strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated 60-100 mesh core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.2 mm is obtained by passing through multiple sets of reducing wheels.

[0044] (3) After the preheating laser beam passes through the preheating collimator, preheating reflector, preheating conical lens group, preheating beam splitter, preheating reflector and beam combiner, it is coaxial with the forming beam. Finally, the preheating beam is closed by the beam splitter and focusing lens and focused on the wire surface to achieve preheating treatment of the laser cladding wire. The uniformity of the energy distribution of the preheating beam spot is ≥95%.

[0045] The shaping laser beam is a double annular spot with independently adjustable core power and ring core power. After passing through a collimator, a shaping reflector, and a shaping conical lens group, a ring-shaped homogenized spot is obtained, which can change the spot size based on the conical lens spacing. After the open-loop processing of the shaping beam splitter prism, the reflection of the beam combiner with a wire feeding hole, and the closed-loop processing of the beam splitter prism, the shaping laser beam is finally focused into an annular spot through a focusing lens, so that the high-energy annular spot acts on the wire and the substrate, and the uniformity of the spot energy distribution is ≥95%.

[0046] (4) First, the valve sealing surface was grooved at the position to be laser clad, with a groove depth of 1.7 mm. Then, the powder core wire was preheated using an annular preheating light, with a laser power of 450 W. Finally, the preheated powder core wire entered the double annular forming light irradiation area for coaxial laser cladding processing. The inner core power of the double annular forming light was 1900 W, the outer core power was 1150 W, the scanning speed was 10 mm / s, the wire feeding speed was 50 mm / s, the overlap rate was 60%, and the shielding gas was argon.

[0047] In this embodiment, the carbon steel valve sealing surface is surface hardened by using a light wire coaxial laser cladding method. The thickness of a single layer of cladding is 3.3 mm, and the hardness of the cladding layer is 43.2 HRC.

[0048] Example 4

[0049] (1) The valve base is made of 316 stainless steel, the wire sheath is a high-purity cobalt strip, and the core powder composition is C1.33%, Cr 32.7%, Si 0.94%, W 6.4%, Mo 0.32%, Ni 1.32%, Mn 0.43%, and the balance is Co.

[0050] (2) An 8 mm wide high-purity cobalt strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated 60-100 mesh core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.6 mm is obtained by passing through multiple sets of reducing wheels.

[0051] (3) After the preheating laser beam passes through the preheating collimator, preheating reflector, preheating conical lens group, preheating beam splitter, preheating reflector and beam combiner, it is coaxial with the forming beam. Finally, the preheating beam is closed by the beam splitter and focusing lens and focused on the wire surface to achieve preheating treatment of the laser cladding wire. The uniformity of the energy distribution of the preheating beam spot is ≥95%.

[0052] The shaping laser beam is a double annular spot with independently adjustable core power and ring core power. After passing through a collimator, a shaping reflector, and a shaping conical lens group, a ring-shaped homogenized spot is obtained, which can change the spot size based on the conical lens spacing. After the open-loop processing of the shaping beam splitter prism, the reflection of the beam combiner with a wire feeding hole, and the closed-loop processing of the beam splitter prism, the shaping laser beam is finally focused into an annular spot through a focusing lens, so that the high-energy annular spot acts on the wire and the substrate, and the uniformity of the spot energy distribution is ≥95%.

[0053] (4) First, the valve sealing surface was grooved at the position to be laser clad, with a groove depth of 1.7 mm. Then, the powder core wire was preheated using an annular preheating light, with a laser power of 550 W. Finally, the preheated powder core wire entered the double annular forming light irradiation area for coaxial laser cladding processing. The inner core power of the double annular forming light was 2100 W, the outer core power was 1200 W, the scanning speed was 10 mm / s, the wire feeding speed was 40 mm / s, the overlap rate was 40%, and the shielding gas was argon.

[0054] In this embodiment, the carbon steel valve sealing surface is surface hardened by using a light wire coaxial laser cladding method. The thickness of a single layer of cladding is 4.3 mm, and the hardness of the cladding layer is 44.1 HRC.

Claims

1. A filament coaxial laser cladding method facing the valve sealing surface, characterized in that: The steps include: (1) Powder core wire composition design: For valve bases made of carbon steel and stainless steel, powder core wire consisting of outer skin and core powder is used for coaxial laser cladding. Among them, for the carbon steel substrate, low carbon steel is selected as the outer skin, and the core powder composition is 0.15%≤C≤0.20%, 16.5%≤Cr≤26.5%, 7.5%≤Ni≤10.5%, 2.5%≤Mo≤4.5%, 1.5%≤W≤3.5%, 0.15%≤Ti≤0.35%, 0.40%≤V≤0.85%, 0.40%≤Nb≤0.85%, and Fe is the balance; for the stainless steel substrate, a high-purity cobalt strip is selected as the outer skin, and the core powder composition is 0.95%≤C≤1.70%, 28.0%≤Cr≤41%, 0.80%≤Si≤1.30%, 3.60%≤W≤10.50%, Mo≤0.45%, 0.70%≤Ni≤1.80%, Mn≤1.05%, and Co is the balance. (2) Preparation of powder core wire: A 5.5-8 mm wide low carbon steel / cobalt strip is rolled into a "U"-shaped outer skin by a roller, and then the prefabricated core powder is added into the "U"-shaped outer skin by a powder feeder, and then it is closed and rolled into an "o" shape by subsequent rollers, and finally a powder core wire with a diameter of 1.2-1.6 mm is obtained by passing through multiple sets of reducing wheels. (3) Construction of the optical path system for filament coaxial laser cladding: An annular light spot is used to preheat the powder core wire, and a double annular homogenized light spot is used to implement filament coaxial laser cladding forming. Specifically, the filament coaxial laser cladding optical path system consists of a preheating collimator (1), a preheating reflector (2), a preheating cone lens group (3), a preheating beam splitter (4), a preheating reflector (5), a composite mirror (6), a forming beam splitter (7), a forming cone lens group (8), a forming collimator (9), a forming reflector (10), a beam splitter (11) and a focusing mirror (12). The preheating laser beam is collimated by a preheating collimator (1) and then enters a preheating cone lens group (3) through a preheating reflector (2). The beam passes through the preheating cone lens group (3) to transform a circular beam into an annular beam. The diameter of the annular beam can be adjusted by changing the cone lens spacing. The preheating beam splitter (4) performs symmetrical open-loop processing on the annular beam. After passing through a preheating reflector (5) with a wire feeding hole and a beam combiner (6), the annular beam is coaxial with the forming beam. Finally, the preheating beam is closed through a beam splitter (11) and a focusing lens (12) and focused on the surface of the wire to achieve preheating of the laser cladding wire. The shaping laser beam is a double annular light spot with independently adjustable center core power and ring core power. After being collimated by a collimator (9), it is reflected by a shaping reflector (10) into a shaping cone lens group (8) to obtain an annular homogenized light spot whose light spot size can be changed based on the cone lens spacing control. After open-loop processing by a shaping beam splitter prism (7), reflection by a beam combiner (6) with a wire feeding hole, and closed-loop processing by a beam splitter prism (11), the shaping laser beam is finally focused into an annular light spot by a focusing lens (12), so that the high-energy annular light spot acts on the wire and the substrate to realize the coaxial laser cladding processing of the light wire. (4) Coaxial laser cladding of light wire: First, the valve sealing surface is grooved at the position to be laser clad, with a groove depth of 1.5 to 2.0 mm. Then, the powder core wire is preheated using an annular preheating light with a laser power of 400 to 900 W. Finally, the preheated powder core wire enters the double annular forming light irradiation area for coaxial laser cladding. The inner core power of the double annular forming light is 1100 to 2300 W, and the outer core power is 700 to 1400 W.

2. A powder core wire laser cladding method facing the valve sealing surface according to claim 1, characterized in that: According to the above technical solution, preferably, the particle size of the medicine core powder in step (2) is controlled to be 60-100 meshes.

3. A powder core wire laser cladding method facing the valve sealing surface according to claim 1, characterized in that: After the shaping and homogenization process in step (3), the spot energy distribution uniformity of the preheating light and the shaping light is greater than or equal to 95%.

4. A powder core wire laser cladding method facing the valve sealing surface according to claim 1, characterized in that: According to the above technical solution, preferably, in step (4), the scanning speed is 9-15 mm / s, the wire feeding speed is 35-55 mm / s, the overlap rate is 30%-60%, and the shielding gas is argon.

5. A powder core wire laser cladding method facing the valve sealing surface according to claim 1, characterized in that: Step (4) According to the above technical solution, preferably, the thickness of the single layer cladding in step (4) is 2 to 4.5 mm.

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