Crossed overlapping powder feeding cladding laser head, laser cladding system and method of using same

Abstract

The application discloses a kind of cross superimposed powder feeding cladding laser heads, laser cladding system and its use method, including carousel powder feeder, control system, water cooling machine, continuous laser generator and collaborative robot arm, the free end of the collaborative robot arm is equipped with the cross superimposed powder feeding cladding laser head;Control system is electrically connected with collaborative robot arm, continuous laser generator, carousel powder feeder, water cooling machine and cross superimposed powder feeding cladding laser head respectively;Continuous laser generator is connected with cross superimposed powder feeding cladding laser head by transmission optical fiber, and water cooling machine is connected with continuous laser generator and cross superimposed powder feeding cladding laser head by pipeline respectively;Carousel powder feeder is connected with inert gas and cross superimposed powder feeding cladding laser head by pipeline respectively.By the above structure, under the same laser energy power, the cladding spot area can be increased, and the laser cladding repair efficiency of the hydroelectric generator top cover coaxial powder feeding is improved.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a cross-over powder feeding cladding laser head, a laser cladding system, and a method of using the same. Background Technology

[0002] During laser cladding, once the laser energy reaches the absorption energy threshold of the cladding powder, a "keyhole effect" occurs, opening the molten pool. This increases the powder's absorption rate of laser energy, thus melting the cladding layer and the substrate. A stable molten pool is formed during cladding, resulting in a good metallurgical bond between the cladding layer and the substrate. In coaxial powder cladding, the laser beam passes through a collimating lens group and a focusing lens group to form a circular spot for cladding. However, because the area of ​​the focused circular spot is too small, the width of each cladding layer is small, leading to low efficiency when coaxially feeding laser cladding the entire workpiece plane.

[0003] As one of the most critical flow-through components of a hydro-generator unit, the generator top cover is subjected to long-term cavitation erosion by water flow during turbine operation. Numerous cavitation pits form on the flow surface, posing a significant safety hazard to the generator unit's safe operation. Traditional manual welding and grinding methods are ineffective. Furthermore, the area to be repaired on the generator top cover is relatively large, while traditional laser cladding focuses on a small spot area, resulting in low repair efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the problems existing in the background art and provide a cross-over superimposed powder feeding cladding laser head. By optimizing the optical path structure inside the laser cladding head, the focused laser beam is split, and the split laser beams are cross-over superimposed to form a cross-over superimposed light spot through a total reflection mirror.

[0005] The second technical problem to be solved by the present invention is to provide a laser cladding system using a cross-stacked powder feeding cladding laser head.

[0006] The third technical problem to be solved by the present invention is to provide a method for using a laser cladding system to perform laser cladding repair on the top cover of a hydro-generator.

[0007] To achieve the above-mentioned technical features, the present invention aims to provide a cross-over superimposed powder feeding cladding laser head, comprising a laser cladding head, wherein the laser cladding head includes a powder feeding mechanism and an optical mechanism. The optical mechanism is installed at one end of the powder feeding mechanism and includes a collimating lens group, a focusing lens group, a three-way beam splitting prism group, a first total reflection mirror, and a second total reflection mirror. The focusing lens group and the three-way beam splitting prism group are sequentially arranged on one side of the collimating lens group. The first and second total reflection mirrors are respectively arranged outside the three-way beam splitting prism group. In use, the laser beam is collimated by the collimating lens group, then focused by the focusing lens group, and then the focused laser beam is split into three beams by the three-way beam splitting prism group. The beam reflected by the three-way beam splitting prism group forms the first beam, the beam passing through the three-way beam splitting prism group forms the second beam, and the beam refracted by the three-way beam splitting prism group forms the third beam. The first beam is reflected by the second total reflection mirror, and the third beam is reflected by the first total reflection mirror. The first beam, the second beam, and the third beam converge to form a cross-over superimposed light spot.

[0008] The overlapping light spots are arranged in a triangular pattern.

[0009] The three-way beam splitter prism group is equipped with a protective mirror on the side away from the focusing mirror group. The first beam, the second beam, and the third beam pass through the protective mirror to form a cross-over superimposed light spot.

[0010] The splitting energy ratio of the first beam, the second beam, and the third beam is 2:1:1.

[0011] It also includes a linear adjustment mechanism, a first rotation adjustment mechanism, and a second rotation adjustment mechanism. The three-way beam splitter prism group is installed and connected to the linear adjustment mechanism so that the three-way beam splitter prism group can be adjusted up and down. The first total reflection mirror is installed and connected to the first rotation adjustment mechanism so that the first total reflection mirror can be rotated to adjust the angle. The second total reflection mirror is installed and connected to the second rotation adjustment mechanism so that the second total reflection mirror can be rotated to adjust the angle.

[0012] The linear adjustment mechanism is a linear module structure. The three-way beam splitter prism group is installed on the sliding block of the linear module structure. The first rotation adjustment mechanism and the second rotation adjustment mechanism are deflection digital motors, and the first total reflection mirror and the second total reflection mirror are respectively installed and connected to the deflection digital motors.

[0013] A laser cladding system includes a rotary powder feeder, a control system, a water chiller, a continuous laser generator, and a collaborative robotic arm. The free end of the collaborative robotic arm is equipped with the cross-overlay powder feeding cladding laser head. The control system is electrically connected to the collaborative robotic arm, the continuous laser generator, the rotary powder feeder, the water chiller, and the cross-overlay powder feeding cladding laser head. The continuous laser generator is connected to the cross-overlay powder feeding cladding laser head via a transmission optical fiber. The water chiller is connected to both the continuous laser generator and the cross-overlay powder feeding cladding laser head via pipes. The rotary powder feeder is connected to both an inert gas storage tank and the cross-overlay powder feeding cladding laser head via pipes.

[0014] A method for using a laser cladding system to repair the top cover of a hydro generator using laser cladding includes the following steps:

[0015] S1: Turn on the switches of the inert gas storage tank, water chiller, rotary powder feeder, control system, collaborative robotic arm, and continuous laser generator in sequence to start the equipment to the standby state;

[0016] S2: The cross-over powder feeding cladding laser head is vertically upward, and the cladding work is carried out in an overhead melting manner. Before the cladding work is carried out, the cooperating robotic arm is first adjusted so that the cross-over powder feeding cladding laser head is in a safe position with the bottom surface of the top cover. The continuous laser generator outputs indicator red light to the bottom surface of the top cover to measure the working focal length. The cooperating robotic arm is adjusted so that the cross-over light spot can radiate on the bottom surface of the top cover.

[0017] S3: Set the working path trajectory and running speed parameters of the collaborative robotic arm through the control system, as well as the laser output energy parameters of the continuous laser generator;

[0018] S4: Start the equipment. Driven by the collaborative robotic arm, the cross-overlay powder feeding cladding laser head moves along the preset path on the bottom surface of the top cover. At the same time, the continuous laser generator emits a laser beam. After the laser beam is split into three beams by the cross-overlay powder feeding cladding laser head, it converges on the bottom surface of the top cover to form a cross-overlay spot. During the cladding process, the high energy density of the superimposed spot area at the center of the cross-overlay spot causes the molten pool to open rapidly, while the low-energy spot area of ​​the surrounding non-overlay area preheats the surrounding area.

[0019] The present invention has the following beneficial effects:

[0020] 1. The cross-overlay powder feeding cladding laser head of the present invention optimizes the internal optical path structure of the laser cladding head, splits the focused laser beam, and uses a total reflection mirror to make the split laser beams cross-overlay to form a cross-overlay spot. Under the same laser energy power, the spot area is increased, thereby improving the laser cladding repair efficiency of coaxial powder feeding on the top cover of a hydro-generator. During the cladding process, the overlapping spot area at the center of the cross-overlay spot has a high energy density, causing the molten pool to open rapidly. The low-energy spot area in the surrounding non-overlay area preheats the surrounding area, thus quickly forming a stable molten pool.

[0021] 2. This invention can change the size of the converged light spot and the area of ​​the overlapping region of the cross-over light spots by adjusting the position of the three-way beam-splitting prism group and the deflection angle of the first and second total reflection mirrors. This achieves the effect of changing the size of the light spot in the cladding area and improving the cladding efficiency of the turbine top cover.

[0022] 3. This invention utilizes the advantages of the collaborative robotic arm in terms of its flexible processing and high positioning accuracy, as well as the non-contact and metallurgically integrated repair characteristics of the laser cladding process, to complete the rapid repair processing of surfaces of different sizes and regions after the top cover is damaged by cavitation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the optical mechanism structure in the cross-stacked powder feeding cladding laser head of the present invention.

[0024] Figure 2 This is a schematic diagram of the cross-stacked light spot structure of the present invention.

[0025] Figure 3 This is a schematic diagram of the laser cladding system of the present invention.

[0026] In the diagram: 1. Inert gas storage tank; 2. Rotary powder feeder; 3. Control system; 4. Water chiller; 5. Continuous laser generator; 51. Transmission fiber; 6. Collaborative robotic arm; 7. Laser cladding head; 71. Collimating lens group; 72. Focusing lens group; 73. Three-way beam splitter prism group; 731. Linear adjustment mechanism; 74. First total reflection mirror; 741. First rotation adjustment mechanism; 75. Second total reflection mirror; 751. Second rotation adjustment mechanism; 76. Protective mirror; 77. Laser beam; 771. First beam; 772. Second beam; 773. Third beam; 774. Cross-over superimposed light spot; 8. Top cover. Detailed Implementation

[0027] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0028] Example 1:

[0029] See Figure 1-3A cross-overlay powder feeding cladding laser head includes a laser cladding head 7, which comprises a powder feeding mechanism and an optical mechanism. The optical mechanism is installed at one end of the powder feeding mechanism and includes a collimating lens group 71, a focusing lens group 72, a three-way beam splitter prism group 73, a first total reflection mirror 74, and a second total reflection mirror 75. The focusing lens group 72, the three-way beam splitter prism group 73, the first total reflection mirror 74, and the second total reflection mirror 75 are sequentially arranged on one side of the collimating lens group 71, respectively positioned on both sides of the three-way beam splitter prism group 73. In this state, the laser beam 77 is collimated by the collimating lens group 71, then focused by the focusing lens group 72, and then split into three beams by the three-way beam splitting prism group 73. The beam reflected by the three-way beam splitting prism group 73 forms the first beam 771, the beam passing through the three-way beam splitting prism group 73 forms the second beam 772, and the beam refracted by the three-way beam splitting prism group 73 forms the third beam 773. The first beam 771 is reflected by the second total reflection mirror 75, and the third beam 773 is reflected by the first total reflection mirror 74. (See also...) Figure 2 The first beam 771, the second beam 772 and the third beam 773 converge to form an intersecting superimposed light spot 774.

[0030] By optimizing the internal optical path structure of the laser cladding head 7, the focused laser beam 77 is split, and the split laser beams are cross-overlaid to form a cross-overlaid spot 774 through a total reflection mirror. Under the same laser energy power, the spot area is increased, thereby improving the laser cladding repair efficiency of coaxial powder feeding on the top cover of the hydro-generator. During the cladding process, the high energy density of the overlapping spot area at the center of the cross-overlaid spot 774 causes the molten pool to open rapidly, while the low-energy spot area in the surrounding non-overlaid area preheats the surrounding area, thus quickly forming a stable molten pool.

[0031] See Figure 1 The three-way beam splitter prism group 73 is an inclined optical block structure.

[0032] See Figure 2 The cross-over superimposed light spot 774 consists of three circular light spots superimposed in a triangular configuration. Preferably, the three circular light spots are superimposed in an equilateral triangle configuration, with the centers of the three circular light spots located at the three corners of the equilateral triangle.

[0033] Furthermore, the three-way beam splitter prism group 73 has a protective mirror 76 on the side away from the focusing lens group 72. The first beam 771, the second beam 772, and the third beam 773 pass through the protective mirror 76 and form an intersecting superimposed light spot 774. The protective mirror 76 is provided to protect the internal optical lenses.

[0034] Further, see Figure 2The three-way beam splitter prism group 73 splits the focused laser beam into three circular beams, with the splitting energy ratio of the first beam 771, the second beam 772, and the third beam 773 being 2:1:1.

[0035] It also includes a linear adjustment mechanism 731, a first rotation adjustment mechanism 741, and a second rotation adjustment mechanism 751. The three-way beam splitter prism group 73 is installed and connected to the linear adjustment mechanism 731, allowing the three-way beam splitter prism group 73 to be adjusted vertically. The first total reflection mirror 74 is installed and connected to the first rotation adjustment mechanism 741, allowing the first total reflection mirror 74 to be rotated and adjusted at an angle. The second total reflection mirror 75 is installed and connected to the second rotation adjustment mechanism 751, allowing the second total reflection mirror 75 to be rotated and adjusted at an angle. By adjusting the position of the three-way beam splitter prism group 73 vertically and adjusting the deflection angles of the first total reflection mirror 74 and the second total reflection mirror 75, the size of the converged light spot and the area of ​​the overlapping region of the cross-overlay light spots 774 can be changed.

[0036] Specifically, the linear adjustment mechanism 731 is a linear module structure, the three-way beam splitter prism group 73 is mounted on the sliding block of the linear module structure, the first rotation adjustment mechanism 741 and the second rotation adjustment mechanism 751 are deflection digital motors respectively, and the first total reflection mirror 74 and the second total reflection mirror 75 are respectively installed and connected to the deflection digital motors. The linear module structure and the deflection digital motor are both existing technologies.

[0037] Example 2:

[0038] A laser cladding system includes a rotary powder feeder 2, a control system 3, a water chiller 4, a continuous laser generator 5, and a collaborative robotic arm 6. The free end of the collaborative robotic arm 6 is equipped with the cross-overlay powder feeding cladding laser head. The control system 3 is electrically connected to the collaborative robotic arm 6, the continuous laser generator 5, the rotary powder feeder 2, the water chiller 4, and the cross-overlay powder feeding cladding laser head. The continuous laser generator 5 is connected to the cross-overlay powder feeding cladding laser head via a transmission optical fiber 51. The water chiller 4 is connected to the continuous laser generator 5 and the cross-overlay powder feeding cladding laser head via pipes. The rotary powder feeder 2 is connected to the inert gas storage tank 1 and the cross-overlay powder feeding cladding laser head via pipes.

[0039] The cladding powder in the rotary powder feeder 2 is transported to the cross-over powder feeding cladding laser head by the inert gas storage tank 1, and converges to the focal point of the cross-over beam spot 774 radiating on the workpiece surface.

[0040] The control system 3 is used to control the collaborative robotic arm 6, the continuous laser generator 5, the rotary powder feeder 2, the water chiller 4, and the cross-over powder feeding and cladding laser head to operate according to preset parameters and paths.

[0041] Water chiller 4 is used to cool continuous laser generator 5 and cross-over powder feeding cladding laser head.

[0042] The continuous laser generator 5 is used to generate a continuous laser beam 77. The rated output power of the continuous laser is 1KW-6KW, the operating power is continuously adjustable from 5% to 100%, and the wavelength of the laser beam is 1040-1090nm.

[0043] The collaborative robotic arm 6 is used for cross-stacking and powder-feeding cladding laser heads. Preferably, the collaborative robotic arm 6 is a six-degree-of-freedom robot.

[0044] The core diameter of the transmission fiber 51 is 200-1000μm, and the locking fiber optic connector type is LLK-D, QD or QBH.

[0045] Example 3:

[0046] A method for using a laser cladding system to repair the top cover of a hydro generator using laser cladding includes the following steps:

[0047] S1: Turn on the switches of inert gas storage tank 1, water chiller 4, rotary powder feeder 2, control system 3, cooperative robotic arm 6, and continuous laser generator 5 in sequence to start the equipment to the standby state.

[0048] S2: The cross-over powder feeding cladding laser head is vertically upward, and the cladding work is carried out in an overhead melting manner; before the cladding work is carried out, the cooperating robotic arm 6 is first adjusted so that the cross-over powder feeding cladding laser head and the bottom surface of the top cover 8 are in a relatively safe position. The continuous laser generator 5 outputs indicator red light to the bottom surface of the top cover 8 to measure the working focal length. The cooperating robotic arm 6 is adjusted so that the cross-over light spot 774 can radiate on the bottom surface of the top cover 8.

[0049] S3: Set the working path trajectory and running speed parameters of the collaborative robotic arm 6 through the control system 3, and set the laser output energy parameters of the continuous laser generator 5;

[0050] S4: Start the equipment. Driven by the collaborative robotic arm 6, the cross-overlay powder feeding cladding laser head moves along a preset path on the bottom surface of the top cover 8. At the same time, the continuous laser generator 5 emits a laser beam 77. After the laser beam 77 is split into three beams by the cross-overlay powder feeding cladding laser head, it converges on the bottom surface of the top cover 8 to form a cross-overlay spot 774. During the cladding process, the high energy density of the superimposed spot area at the center of the cross-overlay spot 774 causes the molten pool to open rapidly, and the low-energy spot area of ​​the surrounding non-overlay area preheats the surrounding area.

[0051] In the above steps, the position of the three-way beam-splitting prism group 73 can be adjusted up and down by the control system 3, and the deflection angles of the first total reflection mirror 74 and the second total reflection mirror 75 can be adjusted to determine the size of the converged cross-over superimposed light spot 774 and the size of the overlapping area. The movement accuracy of the three-way beam-splitting prism group 73 is no less than 0.1 mm, and the rotation accuracy of the first total reflection mirror 74 and the second total reflection mirror 75 is no less than 0.1°.

[0052] Meanwhile, the above steps utilize a laser cladding system with a cross-overlay powder feeding cladding laser head to repair the top cover of the hydro-generator. This can increase the cladding spot area and improve the efficiency of laser cladding repair of the hydro-generator top cover by coaxial powder feeding under the same laser energy power.

Claims

1. A cross superimposed powder feeding cladding laser head, comprising a laser cladding head (7), the laser cladding head (7) comprising a powder feeding mechanism and an optical mechanism, the optical mechanism being installed at one end of the powder feeding mechanism, characterized in that: The optical mechanism comprises a collimating mirror group (71), a focusing mirror group (72), a three-way light splitting prism group (73), a first total reflection mirror (74) and a second total reflection mirror (75), the collimating mirror group (71) is sequentially provided with the focusing mirror group (72), the three-way light splitting prism group (73), the first total reflection mirror (74) and the second total reflection mirror (75) on one side, and the first total reflection mirror (74) and the second total reflection mirror (75) are respectively arranged outside the three-way light splitting prism group (73); in a use state, a laser beam (77) is collimated through the collimating mirror group (71), then focused through the focusing mirror group (72), and then split into three beams through the three-way light splitting prism group (73), wherein the light beam reflected by the three-way light splitting prism group (73) forms a first light beam (771), the light beam penetrating through the three-way light splitting prism group (73) forms a second light beam (772), and the light beam refracted by the three-way light splitting prism group (73) forms a third light beam (773), the first light beam (771) is reflected by the second total reflection mirror (75), and the third light beam (773) is reflected by the first total reflection mirror (74), and the first light beam (771), the second light beam (772) and the third light beam (773) are converged to form a cross superposition light spot (774); ​ The three-way light splitting prism group (73) is an inclined optical block structure; the light splitting energy ratio of the first light beam (771), the second light beam (772) and the third light beam (773) is 2:1:1; The three circular light spots are superimposed in an equilateral triangle state, and the centers of the three circular light spots are respectively located at three corners of the equilateral triangle; In use, the cladding powder is converged to the focus point of the cross superposition light spot (774) radiated on the surface of the workpiece.

2. The cross-over build-up powder feeding cladding laser head according to claim 1, characterized in that: The three-way light splitting prism group (73) is provided with a protective mirror (76) on the side away from the focusing mirror group (72), and the first light beam (771), the second light beam (772) and the third light beam (773) form the cross superposition light spot (774) after penetrating through the protective mirror (76) respectively.

3. The cross-over build-up powder feeding cladding laser head according to claim 1, characterized in that: Further comprising a linear adjustment mechanism (731), a first rotation adjustment mechanism (741) and a second rotation adjustment mechanism (751), the three-way light splitting prism group (73) is installed and connected with the linear adjustment mechanism (731) so as to enable the three-way light splitting prism group (73) to be adjusted and moved up and down, the first total reflection mirror (74) is installed and connected with the first rotation adjustment mechanism (741) so as to enable the first total reflection mirror (74) to be rotationally adjusted in angle, and the second total reflection mirror (75) is installed and connected with the second rotation adjustment mechanism (751) so as to enable the second total reflection mirror (75) to be rotationally adjusted in angle.

4. The cross-over build-up powder feeding cladding laser head according to claim 3, characterized in that: The linear adjustment mechanism (731) is a linear module structure, the three-way light splitting prism group (73) is installed on a sliding block of the linear module structure, and the first rotation adjustment mechanism (741) and the second rotation adjustment mechanism (751) are respectively a deflection type digital motor, and the first total reflection mirror (74) and the second total reflection mirror (75) are respectively installed and connected with the deflection type digital motor.

5. Laser cladding system comprising a carousel powder feeder (2), a control system (3), a water chiller (4), a continuous laser generator (5) and a collaborative robot arm (6), characterized in that: The free end of the cooperative mechanical arm (6) is provided with the cross superimposed powder feeding cladding laser head according to any one of claims 1-4; the control system (3) is electrically connected with the cooperative mechanical arm (6), the continuous laser generator (5), the rotary disc powder feeder (2), the water cooler (4) and the cross superimposed powder feeding cladding laser head; the continuous laser generator (5) is connected with the cross superimposed powder feeding cladding laser head through the transmission optical fiber (51), and the water cooler (4) is connected with the continuous laser generator (5) and the cross superimposed powder feeding cladding laser head through pipelines; the rotary disc powder feeder (2) is connected with the inert gas storage tank (1) and the cross superimposed powder feeding cladding laser head through pipelines.

6. The method of using the laser cladding system of claim 5 for laser cladding repair of the top cover of the hydroelectric generator, characterized in that, The method comprises the following steps: S1: Turn on the switches of the inert gas storage tank (1), the water cooler (4), the rotary disc powder feeder (2), the control system (3), the cooperative mechanical arm (6) and the continuous laser generator (5) in sequence, and start the equipment to the working state; S2: The cross superimposed powder feeding cladding laser head is vertically upward, and the cladding work is performed in the way of upward melting; before the cladding work, the cooperative mechanical arm (6) is first adjusted, so that the cross superimposed powder feeding cladding laser head and the bottom surface of the top cover (8) keep a safe position, the continuous laser generator (5) outputs the indicating red light to the bottom surface of the top cover (8) to measure the working focal length, and the cooperative mechanical arm (6) is adjusted to position, so that the cross superimposed light spot (774) can be radiated on the bottom surface of the top cover (8); S3: The working path trajectory and the running speed parameters of the cooperative mechanical arm (6) are set through the control system (3), and the laser output energy parameters of the continuous laser generator (5) are set; S4: Start the equipment, the cross superimposed powder feeding cladding laser head moves along the preset path on the bottom surface of the top cover (8) under the driving of the cooperative mechanical arm (6), and the continuous laser generator (5) emits the laser beam (77); the laser beam (77) is divided into three beams after passing through the cross superimposed powder feeding cladding laser head, and then converges on the bottom surface of the top cover (8) to form the cross superimposed light spot (774); during the cladding process, the high-energy density of the superimposed light spot area in the center of the cross superimposed light spot (774) makes the molten pool open rapidly, and the low-energy light spot area around the non-superimposed area preheats the surrounding area.

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