A paraxial laser cladding head for machining surfaces in tight spaces

Abstract

This invention relates to the field of laser processing equipment technology, and in particular to a side-axis laser cladding head for processing surfaces in confined spaces. It includes an optical fiber access module, a powder feeding assembly, a distance adjustment assembly, and a guiding module. The powder feeding assembly is located on one side of the optical fiber access module via the distance adjustment assembly, and the guiding module is located on the other side. The cladding laser beam and the guiding laser beam form a fixed intersection area on the surface to be processed, and this intersection area is located at a predetermined distance in front of the powder feeding nozzle. The powder feeding nozzle has a unique shaping flow channel, which sequentially includes a powder inlet channel, a tapering transition section, a constant flow shaping section, and a final slit shaping section, for outputting a uniform, flat powder beam. This invention, through its side-axis layout, front-intersecting laser beam path, and adjustable distance and angle assembly, synergistically solves the technical problems of the cladding head's difficulty in entering confined spaces such as the inner side of spiral blades, powder rebound, and uneven cladding layer, significantly improving the process stability and forming quality of laser cladding in confined spaces.

Description

Technical Field

[0001] This invention relates to the field of laser processing equipment technology, and in particular to a paraxial laser cladding head for processing surfaces in confined spaces. Background Technology

[0002] Laser cladding technology, as an efficient surface repair and remanufacturing method, has been widely used in various industrial parts. However, when dealing with narrow spaces such as the inner side of turbine and compressor rotor blades, the sidewalls of deep and narrow channels, and local areas obstructed by adjacent structures, existing conventional laser cladding heads have shown significant limitations.

[0003] First, traditional coaxial powder feeding cladding heads or large-volume off-axis heads are difficult to insert into narrow cavities, or even if they do, they are prone to colliding with the workpiece due to the lack of effective guidance and positioning references.

[0004] Secondly, in confined spaces, if a conventional circular powder feeder is used, the resulting conical powder stream is highly likely to impact the wall or adjacent structures on the side of the workpiece, causing severe powder rebound and splashing. This not only leads to powder waste but also makes the powder flow into the molten pool unstable, resulting in defects such as thin sides and thick middle, or even localized accumulation and undercut in the cladding layer, making it difficult to meet the requirements for high-quality repair. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a lateral laser cladding head for processing surfaces in confined spaces, so as to solve the problems of difficult operation of the cladding head in narrow cavities, severe powder rebound, and poor uniformity of the cladding layer.

[0006] This invention provides a paraxial laser cladding head for machining surfaces in confined spaces, comprising: The fiber optic access module is used to emit a cladding laser beam directed toward the surface of the workpiece to be processed; The powder feeding assembly has a powder feeding nozzle for outputting powder bundles to the workpiece surface to be processed. The distance adjustment component and the powder feeding component are set on one side of the optical fiber access module. The distance adjustment component is used to adjust and lock the distance between the powder feeding nozzle and the workpiece surface to be processed and the output angle of the powder bundle. The guiding module is located on the other side of the fiber optic access module and is used to emit a guiding laser beam toward the surface of the workpiece to be processed. The cladding laser beam and the guide laser beam form a fixed intersection area on the surface to be processed, and this fixed intersection area is located at a predetermined distance in front of the powder feeding nozzle.

[0007] By guiding the laser beam to form a spot on the surface to be processed, operators or automated systems can intuitively determine the position of the cladding laser beam. Combined with the precise control of the distance of the powder feeding nozzle and the angle of the powder beam by the distance adjustment component, the risk of collision between the cladding head and the workpiece can be effectively avoided. At the same time, the output angle of the powder feeding nozzle can be adjusted according to the specific structure of the confined space, so that the powder beam can be delivered to the fixed intersection area (i.e., the molten pool) formed by the cladding laser beam at a better angle, reducing the collision between the powder beam and the side wall or adjacent structure of the processed surface, thereby reducing powder rebound and splashing, improving powder utilization and the uniformity of the cladding layer, and meeting the needs of high-quality repair of the processed surface in confined spaces.

[0008] Furthermore, the powder feeding assembly includes a slender powder feeding rod with a hollow interior forming a powder feeding channel. One end of the powder feeding rod is connected to a powder feeding connector, and the other end is connected to a powder feeding nozzle. The powder feeding assembly is slender and rod-shaped, which greatly reduces its radial dimension and space occupation, allowing the cladding head to penetrate into narrow cavities such as the inner side of the spiral blade. The powder feeding connector facilitates quick connection to external powder feeding pipelines.

[0009] Furthermore, the distance adjustment assembly includes a mounting base and an angle adjustment base. The mounting base has a mounting hole for accommodating the powder feeding rod, and a locking component is also provided on the mounting base. The locking component is perpendicular to the mounting hole, and the mounting base is rotatably connected to the angle adjustment base via an adapter block mounted on it. The cooperation between the mounting base and the locking component enables adjustment and locking of the powder feeding rod's extension length, allowing precise control of the distance from the tip of the powder feeding nozzle to the processing surface. The rotatable connection between the mounting base and the angle adjustment base via the adapter block provides the structural basis for adjusting the powder feeding angle.

[0010] Furthermore, the distance adjustment assembly also includes a height adjustment seat, which includes a scale rod. An angle adjustment seat is connected to the scale rod, and the upper part of the angle adjustment seat has an adjustment hole to accommodate the scale rod. The lower part of the angle adjustment seat has a notch to accommodate the adapter block, and the lower part of the angle adjustment seat also has an arc-shaped hole communicating with the notch. The scale rod provides a coarse adjustment reference and a height scale. The adjustment hole, notch, and arc-shaped hole on the angle adjustment seat constitute a composite adjustment mechanism: the adjustment hole is used to adjust the overall installation height of the angle adjustment seat; the arc-shaped hole allows the mounting seat (along with the powder feeding rod) to rotate within a certain angle range, and can be fixed by locking after adjustment. This achieves adjustment of the powder feeding nozzle in two degrees of freedom: height and angle, allowing the operator to quickly adjust the powder feeding nozzle to the optimal working posture and reliably lock it according to the geometry of a narrow space.

[0011] Furthermore, the guiding module includes a mounting frame and a laser head. The mounting frame consists of a fixed end and a movable end, with the laser head positioned at the movable end. The fixed end is connected to the outer wall of the fiber optic access module, and the movable end is hinged to the fixed end. This hinged mounting frame allows for fine-tuning of the illumination angle of the guiding laser head. This facilitates calibration during assembly, ensuring the guiding laser beam and the cladding laser beam precisely intersect at a predetermined position. Furthermore, in specific application scenarios, the position of the guiding spot can be independently adjusted, providing the operator with a more flexible visual positioning reference.

[0012] Furthermore, the powder feeding nozzle includes a nozzle body and a shaping channel formed inside the nozzle body. The shaping channel, along the powder output direction, includes a powder inlet channel, a tapering transition section, a constant flow shaping section, and a final slit shaping section. The final slit shaping section forms a flat powder feeding nozzle, used to output a flat powder bundle that widens in one direction and converges in another. The traditional conical powder flow is transformed into a flat powder bundle with a regular cross-sectional shape and uniform powder concentration distribution through a process of gradual flattening (tapering transition section), uniform distribution (constant flow shaping section), and final shaping (final slit shaping section).

[0013] Furthermore, the cross-section of the tapered transition section gradually transitions from a circular shape to a flattened elongated shape along the powder flow direction, and the inner wall surface of the tapered transition section is a continuous smooth curved surface. The continuous smooth curved inner wall avoids abrupt structural changes such as steps and edges in the flow channel, which can greatly reduce the collision, retention and turbulence of powder in the transition section, and ensure a smooth transition of the powder-gas two-phase flow.

[0014] Furthermore, the isodynamic shaping section is a micro-compensation shaping section. The cross-section of this section is a rounded slit-shaped section with slightly widened ends and a slightly tapered middle section, ensuring that the minor axis dimension of the cross-section in the middle region along the long axis of the slit is smaller than that in the two end regions. Based on fluid dynamics principles, powder flow in narrow channels tends to exhibit high central velocity and high powder concentration. By designing the shaping section as a compensating cross-section with a slightly tapered middle section and slightly widened ends, more powder can be actively guided towards the two sides of the outlet, thereby achieving active homogenization of the powder distribution along the long axis of the outlet powder bundle at a physical level.

[0015] Furthermore, in the cross-section of the micro-compensation shaping section, the minor axis dimension of the two end regions is increased by 3% to 12% compared to the minor axis dimension of the middle region. If the compensation amount is less than 3%, the homogenization effect is not significant; if it is greater than 12%, it may cause flow field distortion, leading to powder accumulation at both ends or the generation of new inhomogeneities. Within this preferred range, optimal powder distribution homogenization can be achieved while ensuring flow field stability.

[0016] Furthermore, the exit cross-section of the end slit shaping section is either slit-shaped or a narrow, elongated groove with rounded ends. The length of the end slit shaping section is 1 to 4 times the narrow side dimension of the slit, or 0.1 to 0.5 times the long side dimension of the slit. This ensures that the powder bundle receives sufficient constraint before exiting to stabilize its flattened shape.

[0017] The beneficial effects of this invention are as follows: This invention provides a paraxial laser cladding head for machining surfaces in confined spaces. By placing the powder feeding assembly and the guide module on both sides of the fiber optic module, the overall radial dimension of the cladding head end is greatly reduced, allowing it to smoothly enter the narrow cavity. Combined with the precisely adjustable and lockable distance adjustment assembly, the distance and angle between the powder feeding nozzle and the processing surface can be accurately set and maintained according to the geometry of the narrow space, effectively preventing collisions and achieving operation at a stable focal length. The intersection area of ​​the cladding laser beam and the guide laser beam is set at a predetermined distance in front of the powder feeding nozzle. The guide laser serves as the aiming light, and the processing point is pre-marked in a narrow field of view. After the powder beam is ejected from the nozzle, it is obliquely projected forward to the front molten pool, avoiding the powder beam from being directly sprayed onto the opposite side wall of the narrow space. This fundamentally and significantly reduces powder rebound and splashing, and improves powder utilization and molten pool stability. The four-segment shaping channel inside the powder feeding nozzle enables precise transformation of the powder bundle from a round shape to a uniform flat shape. In particular, the micro-compensation shaping segment actively controls the powder flow distribution, effectively solving the problem of uneven distribution with a thicker middle and thinner sides that is common in flat powder bundles. This ensures that the output flat powder bundles have uniform concentration along the long axis, perfectly matching the processing surface shape of the narrow sidewalls, thereby obtaining a cladding layer with consistent thickness and excellent quality. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort. Figure 1 This is a schematic diagram of the cladding state from the first angle; Figure 2 This is a schematic diagram of the second angle of the cladding state; Figure 3 This is an exploded view of the cladding head; Figure 4 This is a schematic diagram of the internal structure of the powder delivery nozzle; Figure 5 This is a schematic diagram of the workpiece surface to be machined; In the diagram: 1. Fiber optic access module; 2. Powder feeding assembly; 21. Powder feeding rod; 22. Powder feeding nozzle; 221. Powder inlet channel; 222. Gradient transition section; 223. Isostatic shaping section; 224. End slit shaping section; 23. Powder feeding connector; 3. Distance adjustment assembly; 31. Scale rod; 32. Angle adjustment seat; 321. Notch; 322. Arc hole; 33. Mounting base; 34. Locking component; 4. Guide module; 41. Mounting bracket; 42. Laser head; 5. Cladding laser beam; 6. Guide laser beam; 7. Workpiece surface to be processed. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides a paraxial laser cladding head for processing surfaces in confined spaces. Its core components include an optical fiber access module 1, a powder feeding assembly 2, a distance adjustment assembly 3, and a guiding module 4.

[0021] The fiber optic access module 1 includes a fiber optic connector, a collimating lens, and a focusing lens, used to connect to a high-energy laser fiber and focus the cladding laser beam 5 onto a fixed junction area. The powder feeding assembly 2 is located on the right side of the fiber optic module 1 and includes a slender powder feeding rod 21 with a powder feeding channel inside. The rear end of the powder feeding rod 21 is connected to a powder feeding connector 23 for connecting to a powder feeder, and the front end is connected to a specially designed powder feeding nozzle 22. The slender shape of the powder feeding rod 21 facilitates insertion into narrow cavities.

[0022] like Figure 3 As shown, the distance adjustment assembly 3 connects the powder feeding assembly 2 and the main frame. Specifically, it includes a height adjustment seat (using a graduated rod 31), an angle adjustment seat 32, and a mounting seat 33. The powder feeding rod 21 passes through the mounting hole of the mounting seat 33 and is locked in place by a vertical locking element 34 (such as a set screw), thus adjusting and locking the extension length of the powder feeding rod 21. This precisely controls the distance between the powder feeding nozzle 22 and the workpiece surface 7 to be processed. The mounting seat 33 engages with the notch 321 at the bottom of the angle adjustment seat 32 via an adapter block and can rotate within the arc-shaped hole 322. After adjustment, it is locked in place, thereby changing and locking the spray angle of the powder jet. The angle adjustment seat 32 is fitted onto the graduated rod 31 through its adjustment hole, allowing for overall height adjustment and locking. This assembly ensures that the cladding head always faces the processing surface with the optimal posture and distance when entering irregular and narrow spaces, providing both anti-collision and focus stabilization functions.

[0023] The guiding module 4 is located on the left side of the fiber optic module 1 and includes a two-section hinged mounting bracket 41 and a small laser head 42. The laser head 42 emits a low-power visible light guiding laser beam 6. The angle of the guiding laser beam 6 can be finely adjusted through the hinged structure so that it intersects with the cladding laser beam 5 on the workpiece surface 7 at a fixed intersection zone. The intersection zone is located at a predetermined distance in front of the powder feed nozzle 22 outlet. This predetermined distance ensures that the flat powder beam just converges and falls into the molten pool. During operation, the flat powder beam is ejected obliquely from the powder feed nozzle 22, flies forward a certain distance, and falls into the in front of the molten pool. This powder feeding method ensures that the main flight path of the powder beam avoids the opposite wall in the narrow space, thereby reducing powder rebound.

[0024] In actual operation, first connect the high-energy laser fiber to the fiber optic access module 1, and at the same time connect the powder feeder's pipeline to the powder feeding connector 23. Next, based on the specific dimensions of the narrow space to be processed and the position of the workpiece surface 7 to be processed, adjustments are made using the distance adjustment assembly 3: the locking device between the angle adjustment seat 32 and the scale rod 31 is loosened, and the angle adjustment seat 32 is moved up and down to change the overall height of the powder feeding assembly 2, so that the powder feeding nozzle 22 is approximately in a suitable height range; then the locking device between the mounting seat 33 and the angle adjustment seat 32 is loosened, and the mounting seat 33 is rotated within the notch 321 at the lower part of the angle adjustment seat 32 along the trajectory of the arc-shaped hole 322, thereby adjusting the angle of the powder feeding rod 21 and the powder feeding nozzle 22 to ensure that the powder beam can be accurately sprayed onto the area to be processed; then the locking device 34 on the mounting seat 33 is loosened, the powder feeding rod 21 is pushed and pulled, and the length of the powder feeding nozzle 22 is precisely set by observing the scale on the powder feeding rod 21, thereby controlling the distance between the powder feeding nozzle 22 and the workpiece surface 7 to be processed. After adjustment, each locking device is locked in sequence. Subsequently, the operation guide module 4 adjusts the angle of the two-section hinged mounting bracket 41 to ensure that the visible light guiding laser beam 6 emitted by the small laser head 42 and the cladding laser beam 5 precisely intersect at a preset fixed intersection area on the workpiece surface 7 to be processed. This intersection area is the actual point of action for the cladding process. After all adjustments are completed, the laser equipment and powder feeder are started. The cladding laser beam 5 is collimated from the fiber optic access module 1 and irradiates the intersection area on the workpiece surface 7 to be processed. At the same time, the powder feeder delivers powder to the powder feeding nozzle 22 through the powder feeding connector 23 and the powder feeding channel in the powder feeding rod 21. The powder is then sprayed onto the melting area by the powder feeding nozzle 22, realizing laser cladding operation on a narrow processing surface. During this process, the slender shape of the powder feeding rod 21 ensures that the cladding head can smoothly penetrate into narrow spaces such as narrow cavities, while the multi-dimensional adjustment function of the distance adjustment component 3 ensures that the relative position and angle between the powder feeding nozzle 22 and the processing surface are always in the optimal state in complex spaces. The guide laser beam 6 provides the operator with an intuitive processing positioning reference, effectively improving the accuracy and efficiency of the cladding process.

[0025] Example 2 like Figure 4 As shown, this embodiment focuses on detailing the internal structure of the powder feeding nozzle 22 in Embodiment 1, thereby achieving high-quality flat powder feeding.

[0026] The powder feed nozzle 22 has a precision-machined shaping channel inside. This channel, along the powder flow direction, includes: a powder inlet channel 221 with a circular cross-section to receive powder from the powder feed rod 21; a tapering transition section 222, whose cross-sectional shape gradually transitions from a circular inlet shape along a continuous, smooth inner wall surface to a flattened elongated shape (like a racetrack) at the outlet. This process mainly compresses the channel in the height direction (short axis direction) while moderately widening it in the width direction (long axis direction), initially flattening the cylindrical powder flow; and a flow shaping section 223, which in this embodiment is a micro-compensation shaping section. Its cross-section is a rounded slit shape, but not a simple rectangle. Instead, in the long axis direction of the slit, the short axis dimension D1 in the middle of the channel is slightly smaller than the short axis dimension D2 at both ends, forming a slightly constricted shape with slightly widened ends. This design is based on active compensation according to fluid dynamics principles. Because the powder flow in the flattened elongated channel typically has a higher flow velocity and higher powder concentration in the middle, while the opposite is true at both ends. By slightly increasing the flow space at both ends, more powder can be attracted to flow towards both ends, thereby effectively balancing the powder distribution of the powder bundle at the outlet along the long axis and avoiding a cladding layer that is thick in the middle and thin at both ends. Preferably, D2 is 3% to 12% larger than D1 to obtain the best homogenization effect; the end slit shaping section 224: its cross-section is a narrow and long groove (racetrack shape) with rounded ends, and its length is optimized (for example, twice the narrow side dimension), which is used to finally constrain the homogenized flattened powder flow and output a flat powder bundle with uniform thickness and stable shape.

[0027] like Figure 5 As shown, the cladding head of this invention is adjusted to a suitable posture and inserted into a narrow space such as the inner side of the spiral blade. Positioning is achieved through the guide laser 6. After activation, the cladding laser 5 forms a molten pool at the guide spot position. The powder conveyed by the powder feeder enters the powder feeding nozzle 22 via the powder feeding rod 21, and sequentially undergoes four steps: circular powder feeding, smoothing and flattening, micro-compensation homogenization, and slit shaping, transforming it into a uniform, flat powder bundle, which is then obliquely projected forward and precisely deposited into the pre-positioned molten pool. Because the powder bundle is flat and its delivery direction is almost parallel to the sidewall, there is almost no powder impact on the sidewall; because the powder bundle is uniform, the cladding layer has a consistent width and thickness.

[0028] The above description is illustrative only and not restrictive of the present invention. Those skilled in the art will understand that many modifications, variations or equivalents can be made without departing from the spirit and scope defined by the appended claims, and all such modifications, variations or equivalents will fall within the protection scope of the present invention.

Claims

1. A paraxial laser cladding head for machining surfaces in confined spaces, characterized in that: include The fiber optic access module (1) is used to emit a cladding laser beam (5) toward the surface (7) of the workpiece to be processed. The powder feeding assembly (2) has a powder feeding nozzle (22) for outputting powder bundles to the workpiece surface (7) to be processed; The distance adjustment component (3) is used to adjust and lock the distance between the powder feeding nozzle (22) and the workpiece surface (7) and the output angle of the powder bundle. The powder feeding component (22) is set on one side of the optical fiber access module (1) via the distance adjustment component (3). The guide module (4) is located on the other side of the optical fiber access module (1) and is used to emit a guide laser beam (6) toward the workpiece surface (7) to be processed. The cladding laser beam (5) and the guide laser beam (6) form a fixed intersection area on the surface to be processed, and the fixed intersection area is located at a predetermined distance in front of the powder feeding nozzle (22).

2. The off-axis laser cladding head for machining surfaces in confined spaces according to claim 1, characterized in that: The powder feeding assembly (2) includes a slender powder feeding rod (21), the powder feeding rod (21) being hollow to form a powder feeding channel. One end of the powder feeding rod (21) is connected to the powder feeding connector (23), and the other end is connected to the powder feeding nozzle (22).

3. The off-axis laser cladding head for machining surfaces in confined spaces according to claim 2, characterized in that: The distance adjustment assembly (3) includes a mounting base (33) and an angle adjustment base (32). The mounting base (33) has a mounting hole for accommodating the powder feeding rod (21). The mounting base (33) is also provided with a locking member (34), which is perpendicular to the mounting hole. The mounting base (33) is rotatably connected to the angle adjustment base (32) via an adapter block disposed thereon.

4. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 3, characterized in that: The distance adjustment assembly (3) further includes a height adjustment seat, which includes a scale rod (31). The angle adjustment seat (32) is connected to the scale rod (31). The upper part of the angle adjustment seat (32) is provided with an adjustment hole that can accommodate the scale rod (31), the lower part of the angle adjustment seat (32) can accommodate the notch (321) of the adapter block, and the lower part of the angle adjustment seat (32) is also provided with an arc-shaped hole (322) that communicates with the notch (321).

5. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 1, characterized in that: The guide module (4) includes a mounting frame (41) and a laser head (42). The mounting frame (41) consists of a fixed end and a movable end. The laser head (42) is located at the movable end. The fixed end is connected to the outer wall of the fiber optic access module (1). The movable end is hinged to the fixed end.

6. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 1, characterized in that: The powder feeding nozzle (22) includes a nozzle body and a shaping flow channel formed inside the nozzle body. The shaping channel includes, in sequence along the powder output direction, a powder inlet channel (221), a tapering transition section (222), an isotropic shaping section (223), and an end slit shaping section (224). The end slit shaping section (224) forms a flat powder feeding nozzle, which is used to output a flat powder bundle that widens in one direction and converges in another direction.

7. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 6, characterized in that: The cross-section of the tapered transition section (222) gradually transitions from a circular shape to a flat and elongated shape along the powder flow direction, and the inner wall surface of the tapered transition section (222) is a continuous smooth curved surface.

8. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 6, characterized in that: The constant flow shaping section (223) is a micro-compensation shaping section. The cross-section of the micro-compensation shaping section is a rounded slit-shaped cross-section with slightly expanded ends and slightly narrowed waist in the middle, so that the minor axis dimension of the cross-section in the middle region of the slit's long axis direction is smaller than the minor axis dimension of the two end regions.

9. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 8, characterized in that: In the cross-section of the micro-compensation shaping section, the minor axis dimension of the two end regions is increased by 3% to 12% relative to the minor axis dimension of the middle region.

10. A paraxial laser cladding head for machining surfaces in confined spaces according to claim 6, characterized in that: The outlet cross-section of the end slit shaping section (224) is a slit shape or a narrow long groove shape with rounded transitions at both ends. The length of the end slit shaping section (224) is 1 to 4 times the narrow side dimension of the slit, or 0.1 to 0.5 times the long side dimension of the slit.

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