A method for manufacturing a water pump impeller by using additive and subtractive materials in a shipboard condition

Abstract

This invention relates to an emergency manufacturing method for a water pump impeller under shipboard conditions, comprising the following steps: S1. Acquiring the three-dimensional geometric data of the target impeller; S2. Dividing the manufacturing object; S3. Manufacturing a hub blank using arc wire feeding additive manufacturing; S4. Performing intermediate five-axis subtractive machining; S5. Installing the machined hub on the rotary shaft of a five-axis machine, and forming blades layer by layer from the outer surface of the hub using laser coaxial powder feeding; S6. Performing secondary finishing of the blades using five-axis CNC machining; S7. Deburring, surface treatment, and machine verification. This invention utilizes only arc wire feeding to manufacture the cylindrical hub, reducing laser deposition volume and powder consumption; the blades are formed by laser coaxial powder feeding additive manufacturing, reducing heat input in the blade area and improving the near-net-shape forming capability of complex blades. After the hub is rotated 90°, the workpiece datum is repeatedly established using the fit between the mandrel and the central through hole, the end face, and the circumferential positioning features, reducing positioning errors during rotation and finishing.

Description

Technical Field

[0001] This invention relates to the field of impeller manufacturing, and more specifically, to an emergency manufacturing method for a water pump impeller with partitioned addition and subtraction of materials under shipboard conditions. Background Technology

[0002] Impellers in marine sewage treatment pumps, circulating pumps, and other equipment are in constant contact with media containing chloride ions, salts, and suspended particles. Some copper alloy impellers are prone to corrosion, erosion, and wear during actual use. For imported or non-standard pump sets, there are often problems with the high price and long delivery time of spare parts after impeller damage, making it difficult to meet the needs of quickly restoring equipment operation on site.

[0003] Traditional impellers are generally manufactured by casting followed by machining or by cutting from a single piece. For single-piece or small-batch emergency replacements, the cycle of re-molding and casting is relatively long; when using cutting from a single piece, the space between the continuous helical blades and the central hub is limited, the amount of material removed is large, and both machining accessibility and machining efficiency are restricted.

[0004] Current additive-subtractive composite manufacturing typically focuses on alternating between a single additive heat source and subtractive processing, or selecting different additive methods only based on whether the area is thick or complex. If arc wire feeding and coaxial laser powder feeding additive manufacturing are combined for impeller manufacturing, three interrelated problems need to be addressed: First, how to ensure that the hub formed by arc wire feeding becomes a high-precision, repeatable substrate after intermediate subtractive processing; second, how to ensure that the nozzle, powder flow, and laser beam always act at the appropriate posture at each deposition position during the coaxial laser powder feeding stage, thereby completely forming the entire continuous helical blade; and third, how to ensure that the blade after laser additive manufacturing continues to use the same reference system as the final five-axis finishing process, avoiding positioning errors caused by process transitions. Summary of the Invention

[0005] In view of this, the present invention aims to propose an emergency manufacturing method for pump impellers under shipboard conditions, which involves the addition and subtraction of materials in a partitioned manner. This method addresses the problems in the prior art where the emergency manufacturing of impellers under shipboard conditions requires the creation of new molds and casting, resulting in a long cycle, or where the material removal allowance is large when using solid material cutting.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for emergency manufacturing of a water pump impeller with modular addition and subtraction components under shipboard conditions includes the following steps:

[0008] S1. Obtain the three-dimensional geometric data of the target impeller;

[0009] S2. The target impeller is divided into manufacturing objects. The hub is the hub base area and is manufactured by electric arc wire feeding additive manufacturing. The continuous spiral blade is the blade area and is manufactured by laser coaxial powder feeding additive manufacturing. The central through hole is formed in the intermediate five-axis subtractive manufacturing stage.

[0010] S3. Using electric arc wire feeding additive manufacturing, a single cylindrical wheel hub blank is manufactured;

[0011] S4. Perform intermediate five-axis subtractive processing on the cylindrical hub blank obtained by arc wire feeding additive manufacturing;

[0012] S5. The completed wheel hub is installed on the rotary shaft of the five-axis equipment, and the blade is formed by layer-by-layer deposition of powder from the outer surface of the wheel hub through laser coaxial feeding, starting from the target spiral trajectory;

[0013] S6. The blade is subjected to secondary finishing using five-axis CNC machining to remove the laser additive allowance and obtain the thickness, pitch and flow channel profile of the target blade.

[0014] S7. Complete dimensional, geometrical, static or dynamic balance tests, and perform deburring, surface treatment and installation verification as needed.

[0015] Optionally, in step S1, the three-dimensional geometric data includes at least the dimensions of the central through hole, the dimensions of the end face, the blade pitch, and the blade thickness.

[0016] Optionally, in step S3, the wheel hub blank only includes the cylindrical solid that forms the wheel hub, and reserves intermediate material reduction allowance for the central through hole, the outer circle of the wheel hub and the two end faces.

[0017] Optionally, in step S4, the center through hole or the outer circle of the positioning hub is first machined to establish the rotation axis reference, and the axial end face and circumferential positioning features are machined; then the outer circle of the hub is finished to make the hub the substrate for subsequent laser additive manufacturing, and the circumferential positioning features are used to cooperate with the positioning fixture to determine the angular position of the hub around its own axis.

[0018] Optionally, in step S5, the processed hub is rotated 90° relative to the axial orientation during arc wire feeding additive manufacturing, and the hub is horizontally mounted on the rotary shaft of the five-axis equipment, so that the central axis of the hub coincides with the axis of the rotary shaft. The laser coaxial powder feeding nozzle is arranged above the working point of the outer circle of the hub or in its local normal direction. Through the linkage of continuous rotation of the rotary shaft and linear axial feed, the first layer makes the laser beam and powder flow act on the outer surface of the hub in the same convergence area. Subsequent layers act on the growth part of the deposited blade, and the nozzle position is adjusted according to the radial height of the blade to form the blade layer by layer along the target spiral trajectory.

[0019] Optionally, in step S5, the blades are deposited layer by layer and channel by channel from the outer surface of the hub to the target radial near-net height. The entire continuous spiral blade is formed by powder deposition, and a uniform allowance is reserved for the final five-axis subtractive material.

[0020] Optionally, in step S6, after the laser coaxial powder feeding additive manufacturing is completed, the workpiece is cooled and repositioned using the rotation axis of the central through hole formed in step S4 or the rotation axis of the outer circle of the hub, end face and circumferential positioning features. Alternatively, the same reference clamping is maintained, and then five-axis CNC machining is used to perform secondary finishing on the hydraulic surface on both sides of the blade, the blade edge, the blade root transition area and the hub mating surface to remove the laser additive manufacturing allowance and obtain the thickness, pitch and flow channel profile of the target blade.

[0021] Optionally, the hub and blades can be made of the same grade or metallurgically compatible materials.

[0022] Optionally, the arc wire feeding additive manufacturing process can employ any of the following methods: CMT, MIG / MAG, TIG wire feeding, or plasma wire feeding.

[0023] Optionally, the blade additive manufacturing adopts a laser coaxial powder feeding method instead of lateral powder feeding.

[0024] Compared with the prior art, the emergency manufacturing method of a water pump impeller under shipboard conditions using a composite material addition and subtraction method has the following advantages:

[0025] (1) The present invention uses only electric arc wire feeding to manufacture a geometrically simple single cylindrical hub, which can reduce the laser deposition volume and powder consumption; the entire continuous spiral blade is formed by laser coaxial powder feeding additive manufacturing, which can reduce the heat input in the blade area and improve the near-net-shape forming capability of complex blades.

[0026] (2) The intermediate five-axis subtraction establishes a unified reference for the central through hole, outer circle and end face, and makes the hub have a high-precision geometric basis that can be repeatedly indexed; after the hub rotates 90°, the workpiece reference and corresponding coordinate relationship can still be repeatedly established through the cooperation of the mandrel and the central through hole, the end face and circumferential positioning features, thereby reducing the positioning error in the additive manufacturing process and final finishing.

[0027] (3) After the hub is installed horizontally, the rotation shaft moves in coordination with the linear / swing shaft of the equipment, which enables the coaxial powder deposition point to move stably along a continuous spiral trajectory, providing a clear and feasible movement mode for the entire blade to be directly formed from powder into near-net-shape. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a schematic diagram of the impeller structure of the present invention;

[0030] Figure 2 This is a partial flowchart of the impeller partitioning additive and subtractive composite emergency manufacturing method of the present invention;

[0031] Figure 3 This is a schematic diagram of step S6, secondary finishing of the blade, in the impeller partitioning additive and subtractive composite emergency manufacturing method of the present invention;

[0032] Figure 4 This is a schematic diagram of the near-net-shape blank of the impeller described in this invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Central through hole; 2. Hub; 3. Blade; 4. End face. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these alterations or modifications also fall within the scope of protection of this application.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] This invention provides an emergency manufacturing method for a water pump impeller under shipboard conditions, using a composite additive and subtractive manufacturing method for processing and manufacturing impellers, such as... Figure 1 As shown, the impeller includes a hub 2 and continuous helical blades 3 disposed on the outside of the hub 2. The hub 2 is cylindrical with a central through hole 1, and the two sides of the hub 2 along its axial direction are end faces 4.

[0038] like Figure 2 As shown, the emergency manufacturing method for a water pump impeller under shipboard conditions, which involves adding or subtracting materials in different sections, includes the following steps:

[0039] S1. Obtain the three-dimensional geometric data of the target impeller;

[0040] Specifically, in step S1, the three-dimensional geometric data includes at least the dimensions of the central through hole 1, the dimensions of the end face 4, the blade pitch of the blade 3, and the thickness of the blade 3. For impellers with complete drawings or models, the target three-dimensional model is directly established. For impellers with missing drawings or local corrosion of the original parts, the impeller shape can be restored by combining measurements of undamaged parts, three-dimensional scanning, and the dimensions of the matching pump body.

[0041] S2. The target impeller is divided into manufacturing objects. The hub 2 is the hub base area and is manufactured by electric arc wire feeding additive manufacturing. The continuous spiral blade 3 is the blade area and is manufactured by laser coaxial powder feeding additive manufacturing. The central through hole 1 is formed in the intermediate five-axis subtractive manufacturing stage.

[0042] Specifically, in step S2, no blade 3 skeleton, blade segments, or blade root support are prefabricated in the arc-fed additive manufacturing stage. The entire blade 3 is formed layer by layer from the outer surface of the hub 2 in the subsequent laser coaxial powder feeding additive manufacturing stage. Arc-fed additive manufacturing has the characteristics of high deposition efficiency and high material utilization, making it suitable for rapidly forming a hub 2 substrate with a simple structure and relatively large volume. However, if arc-fed additive manufacturing is used directly to form continuous helical blades 3, the blade 3 thickness is easily too large, thermal deformation is obvious, and the subsequent finishing allowance is uneven due to the large single-pass size and high heat input. In laser coaxial powder feeding additive manufacturing, the energy and powder converge near the same axis, and the deposition width is smaller, which makes it easier to form complex continuous blades 3 layer by layer on the outer surface of the hub 2 through multi-axis linkage.

[0043] S3. An electric arc wire feeding additive manufacturing process is used to manufacture a single cylindrical hub 2 blank. The hub 2 blank only includes the cylindrical solid that forms the hub 2, and intermediate material reduction allowance is reserved for the central through hole 1, the outer circle of the hub 2 and the two end faces 4.

[0044] Specifically, in step S3, the arc-feed additive manufacturing can be completed using a circumferential or reciprocating layered method, without forming any final blade 3 structure. The parameters for arc-feed additive manufacturing can refer to existing technologies. When using an additive substrate for forming, after the blank cools, it is first separated from the substrate and residual connecting parts are removed, and then the two end faces 4 and the central through hole 1 are processed. Here, the outer circle refers to the outer cylindrical surface of the hub 2, not the envelope of the outer edge of the blade 3; the central through hole 1 is formed in step S4.

[0045] S4. Perform intermediate five-axis subtractive processing on the cylindrical hub blank obtained by arc wire feeding additive manufacturing;

[0046] Specifically, in step S4, the outer circle of the center through hole 1 or the positioning hub 2 is first machined to establish the rotation axis reference, and the axial end face 4 and circumferential positioning features are machined; then the outer circle of the hub 2 is precision machined so that the hub 2 becomes a high-precision substrate for subsequent laser additive manufacturing.

[0047] The central through hole 1 or the positioning outer circle is used to determine the rotation axis, the end face 4 determines the axial position, and the circumferential positioning feature determines the circumferential angle position. These three elements constitute the positioning reference for subsequent processes. The parameters for the intermediate five-axis subtractive machining are determined by those skilled in the art based on the three-dimensional geometric data of the impeller and empirical values. Optionally, the circumferential positioning feature is an eccentric process positioning hole set in the non-hydraulic working area of ​​the end face 4. The hole axis is parallel to the hub axis, and the hole center is offset from the hub axis. The hole position and size should retain the required wall thickness and avoid the pump shaft installation and final assembly area. When using this positioning hole, the central through hole 1 cooperates with the mandrel to determine the rotation axis, the end face 4 abuts against the tooling shoulder to determine the axial position, and the positioning hole cooperates with the positioning pin to determine the circumferential angle position. The positioning pin has a clearance along the line connecting the centers of the two holes and is only limited in the tangential direction to avoid repeatedly defining the radial position with the mandrel. After positioning, the end face 4 is pressed against the shoulder by the end clamping member, which avoids the blade forming and tool movement range.

[0048] S5. The completed hub 2 is installed on the rotary shaft of the five-axis equipment, and the blade 3 is formed by layer-by-layer deposition from the outer surface of the hub 2 along the target spiral trajectory through laser coaxial powder feeding.

[0049] Specifically, in step S5, the completed hub 2 is rotated 90° relative to its axial orientation during arc-feeding additive manufacturing, and the hub 2 is horizontally mounted on the rotary shaft of the five-axis equipment, aligning the central axis of the hub 2 with the axis of the rotary shaft. The laser coaxial powder feeding nozzle is positioned above the working point on the outer circumference of the hub 2 or in its local normal direction. Through the continuous rotation of the rotary shaft and the linkage of linear axial feed, the laser beam and powder flow of the first radial deposition layer converge on the outer surface of the hub. The axial feed amount per revolution of the rotary shaft corresponds to the target pitch. The deposition points of subsequent layers are located at the growth sites of the deposited blades. The nozzles are adjusted outward with the radial height of the blades, maintaining the defocusing amount and working distance determined by the process sample. The laser and powder feeding are turned off between layers, and the idle stroke is moved to the starting point of the next layer before continuing deposition. The blade 3 is deposited layer by layer and pass by pass from the outer surface of the hub 2 to the target radial near-net height. The entire continuous spiral blade 3 is formed by powder deposition, with a uniform allowance reserved for the final five-axis subtractive manufacturing. The size and orientation of the nozzle used should be adapted to the deposition space between adjacent spiral sections. Before executing the path, check the gap between the nozzle, the formed blade and the fixture to avoid interference.

[0050] For impellers with small diameters, low blade heights, or low laser heat input, the entire blade can be continuously deposited along a complete helical trajectory. For larger impellers or those with significant heat accumulation, segmented, intermittent, or alternating deposition of non-adjacent regions can be used as a thermal control method while maintaining coaxial powder feeding, horizontal rotation, and five-axis linkage. However, this thermal control method does not change the fundamental process that "the entire blade is formed by coaxial laser powder feeding." The parameters of the additive path for generating blade 3 through coaxial laser powder feeding additive manufacturing are determined by those skilled in the art based on the three-dimensional geometric data of blade 3 and empirical values.

[0051] S6. The blade 3 is subjected to secondary finishing using five-axis CNC machining to remove the laser additive allowance and obtain the thickness, pitch and flow channel profile of the target blade 3.

[0052] like Figure 3 As shown, after the laser coaxial powder feeding additive manufacturing is completed, the workpiece is cooled and repositioned using the rotation axis of the central through hole 1 formed in step S4 or the rotation axis of the outer circle of the hub 2, the end face and circumferential positioning features. Alternatively, the same reference clamping is maintained. Then, five-axis CNC machining is used to perform secondary finishing on the hydraulic surfaces on both sides of the blade 3, the blade edge, the blade root transition area and the mating surface of the hub 2 to remove the laser additive manufacturing allowance and obtain the thickness, pitch and flow channel profile of the target blade 3. Figure 2 S6 indicates the horizontal clamping and machining state. Figure 3 This diagram illustrates the vertical clamping machining state. Equipment capable of maintaining clamping can change the workpiece's orientation via indexing on a swing axis; when tooling needs to be changed, it should be re-clamped according to the aforementioned axis, end face, and circumferential positioning references. The machining coordinates after indexing are determined through machine tool kinematic transformation, and the machining coordinates after re-clamping are re-established according to the positioning references. The two diagrams illustrate the machining posture, with the tooling configured according to the aforementioned positioning and clamping relationships.

[0053] S7. Complete dimensional, geometrical, static or dynamic balance tests, and perform deburring, surface treatment and installation verification as needed.

[0054] As a preferred example of the present invention, the hub 2 and the blade 3 are made of the same grade or materials with good metallurgical compatibility. Preferably, the hub 2 is made of 316 stainless steel wire with a diameter of 1.2 mm, and the blade 3 is formed by coaxial feeding of 316 stainless steel powder with a particle size of 45-105 μm, so that the interface material system of the hub 2 and the blade 3 is consistent.

[0055] Arc-fed additive manufacturing can employ any of the following methods: CMT, MIG / MAG, TIG, or plasma-fed. Blade 3 additive manufacturing uses a coaxial laser powder feeding method, not lateral powder feeding. Arc-fed additive manufacturing, laser power, powder feeding rate, scanning speed, and protective gas flow rate are determined through process trials based on the hub 2 dimensions and equipment capabilities. During the laser additive manufacturing stage, it is essential to ensure that the hub 2 rotation axis coincides with the central axis established during intermediate sublimation, and to maintain a stable relative posture between the coaxial nozzle and the local deposition position through five-axis linkage.

[0056] The present invention provides an emergency manufacturing method for a water pump impeller under shipboard conditions, which involves the combination of additive and subtractive manufacturing processes. This method is not simply a series of "arc additive manufacturing, laser additive manufacturing, and five-axis subtractive manufacturing," but rather involves the following interrelationships in the formation of the shipboard water pump impeller:

[0057] (1) The manufacturing objects are clearly divided into two categories: "single cylindrical hub 2" and "complete continuous spiral blade 3", and high-efficiency electric arc wire feeding manufacturing and laser coaxial powder feeding additive manufacturing are respectively adopted to avoid the adverse effects of electric arc additive manufacturing on the geometric accuracy of thin-walled complex blade 3.

[0058] (2) An intermediate five-axis subtractive manufacturing process is set between electric arc wire feeding additive manufacturing and laser coaxial powder feeding additive manufacturing. The central through hole 1, the outer circle of the hub 2 and the end face 4 are processed into high-precision reference surfaces, so that the subsequent 90° rotation of the hub 2, laser coaxial powder feeding additive manufacturing and the final five-axis secondary finishing can all be carried out with the same reference system for coordinate transfer, which is conducive to improving the processing accuracy.

[0059] (3) After the intermediate material is removed, the hub is rotated 90° and installed on the horizontal rotary shaft. The rotary motion is linked with the linear / oscillating shaft to enable the coaxial powder feeding nozzle to maintain a stable laser-powder convergence relationship throughout the entire spiral path. This indexing and motion relationship is the key to the complete blade 3 being formed.

[0060] (4) After the laser coaxial powder feeding completes the near-net-shape forming of the entire blade, the final five-axis secondary finishing continues to use the benchmark established by the intermediate subtraction to ensure the consistency of the position of the blade hydraulic profile, blade pitch, blade edge and blade root transition zone with the central hub. For larger impellers, segmented or intermittent deposition can be used to reduce heat accumulation.

[0061] Compared with traditional casting or solid material cutting manufacturing, this invention can quickly obtain near-net-shape blanks using additive manufacturing, reducing mold preparation and large-margin cutting processes. It is suitable for single-piece, small-batch emergency manufacturing on-site or near-site, as well as emergency manufacturing during shipboard processes.

[0062] Compared with the use of electric arc wire feeding additive manufacturing for the whole part, the present invention only uses electric arc wire feeding to manufacture a geometrically simple single cylindrical hub 2, while the entire continuous spiral blade 3 is formed by laser coaxial powder feeding additive manufacturing, which can reduce the heat input in the blade 3 area and improve the near-net-shape forming capability of complex blade 3.

[0063] Compared with laser powder feeding additive manufacturing of the whole part, the present invention uses electric arc wire feeding to quickly form the main body of the hub 2, which can reduce the laser deposition volume and powder consumption; at the same time, the high-precision outer circle of the hub 2 after intermediate subtraction can be directly used as a stable substrate for laser additive manufacturing of the blade 3.

[0064] The intermediate five-axis subtractive process establishes a unified datum for the central through hole 1, the outer circle, and the end face 4, and gives the hub 2 a high-precision geometric basis that can be repeatedly indexed. After the hub 2 rotates 90°, the workpiece datum and corresponding coordinate relationship can still be repeatedly established through the cooperation between the mandrel and the central through hole 1, the end face 4, and the circumferential positioning features, thereby reducing the positioning error in the additive manufacturing process and the final finishing.

[0065] After the hub 2 is installed horizontally, the rotation of the rotary shaft works in coordination with the linear / oscillating shaft of the equipment, enabling the coaxial powder deposition point to move stably along a continuous spiral trajectory, providing a clear and feasible motion mode for the entire blade to be directly formed from powder into near-net-shape.

[0066] The manufacturing cycle of a single impeller includes arc additive manufacturing, intermediate subtractive manufacturing, laser additive manufacturing, cooling, and final finishing. The specific time depends on the impeller size, equipment parameters, and clamping method. Installation verification should be conducted in conjunction with the actual medium, operating load, and inspection cycle to evaluate corrosion, wear, and operational stability.

[0067] Example 1

[0068] To address the issues of rapid corrosion and wear of the original copper alloy impeller in marine sewage treatment pumps, and the long procurement cycle for spare parts, a three-dimensional model was reconstructed based on the original impeller's geometry and installation relationship. The target impeller consists of a support frame with a central through hole 1 and spiral blades 3 extending continuously along the outer circumference of the support frame, where the support frame is the hub 2. To balance manufacturing efficiency, blade precision 3, and corrosion resistance, both the support frame and blades 3 are made of 316 stainless steel.

[0069] First, a unified coordinate system is established based on the central through hole 1, end face 4 and assembly direction of the impeller. Only a single cylindrical hub 2 blank is retained in the electric arc additive model, and intermediate material reduction allowances are reserved for the central through hole 1, the outer circle of hub 2 and end face 4 respectively. The entire continuous spiral blade 3 is not prefabricated in the electric arc additive stage.

[0070] A single cylindrical hub blank 2 is rapidly formed using arc-fed additive manufacturing. After the blank cools, if an additive substrate is used, it is first separated from the substrate and any remaining connection parts are removed. Then, it is clamped onto a five-axis CNC machine tool, where a central through hole 1, a positioning outer circle, and an axial end face 4 are machined sequentially to form a unified axis of rotation and a reference for the end face 4. The outer circle of the hub 2 is then precision-machined to meet the dimensional and surface quality requirements of the laser additive substrate. When repeated circumferential positioning is required, the eccentric positioning hole can be machined in the non-hydraulic working area of ​​the end face 4.

[0071] To implement intermediate five-axis subtractive machining, first machine the center through hole 1 or the outer circle of the positioning hub 2 to establish the rotation axis reference, and then machine the axial end face 4 and the circumferential positioning features; then finish machine the outer circle of the hub 2.

[0072] After completing the intermediate subtractive processing, the hub 2 is rotated 90° relative to the original arc additive manufacturing posture and horizontally installed onto the rotary axis of the five-axis equipment through the central through-hole 1, aligning the central axis of the hub 2 with the rotary axis of the five-axis equipment. The axial position is determined by the fit between the end face and the tooling shoulder. When using an eccentric process positioning hole, the circumferential angle position is determined by its cooperation with the tooling positioning pin with radial clearance. After positioning, it is tightened. A laser coaxial powder feeding nozzle is used. In the first layer, the laser beam and the 316 stainless steel powder flow are coaxially converged at the working point on the outer circle of the hub 2. Through the continuous rotation of the rotary axis and the linkage of the linear axial feed / oscillating axis, the deposition point moves along the target spiral trajectory and accumulates layer by layer from the outer surface of the hub 2 to form the entire continuous blade 3. In subsequent layers, the laser and powder converge at the growth part of the deposited blade. The nozzle position and working distance are adjusted according to the radial deposition height, and the interference with adjacent spiral sections and fixtures is checked before execution.

[0073] Figure 4 The near-net-shape blank with a central through hole 1, a cylindrical hub 2, and continuous helical blades 3 is shown. Figure 4 The bottom square plate is not part of the final impeller structure, nor is it used to define the clamping method in step S5. After the laser coaxial powder feeding additive manufacturing is completed, the thickness of blade 3, the blade edge, the blade root transition area, and the hydraulic profile still retain the final machining allowance. After the workpiece has cooled sufficiently, precise positioning is performed using the central through hole 1, the axis of rotation, the end face 4, and the circumferential positioning datum formed in the intermediate subtractive manufacturing stage. Five-axis CNC machining is used to finish the hydraulic profiles on both sides of blade 3, the blade edge, the blade root transition area, and the necessary mating surfaces of the hub 2, ultimately completing the dimensional, balancing, and assembly inspection.

[0074] In this embodiment, the electric arc wire feeding is responsible for the rapid forming of a single cylindrical hub 2, while the laser coaxial powder feeding is responsible for the near-net-shape forming of the entire continuous blade 3. The intermediate five-axis subtractive manufacturing process is responsible for forming the high-precision central through-hole 1, the outer circle of the hub 2, and the end face 4 reference. The 90° rotation and horizontal rotation of the hub provide the motion conditions for the stable forming of the coaxial powder feeding along the spiral trajectory. Finally, the five-axis subtractive manufacturing process is used to obtain the blade hydraulic profile required for actual operation. After dimensional, balancing, and installation testing confirms that it meets the usage requirements, it is put into use, and operational observations are conducted based on actual working conditions.

[0075] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for emergency manufacturing of a water pump impeller with modular addition and subtraction components under shipboard conditions, characterized in that, Includes the following steps: S1. Obtain the three-dimensional geometric data of the target impeller; S2. The target impeller is divided into manufacturing objects. The hub (2) is used as the hub base area and is manufactured by electric arc wire feeding additive manufacturing. The continuous spiral blade (3) is used as the blade area and is manufactured by laser coaxial powder feeding additive manufacturing. The central through hole (1) is formed in the intermediate five-axis subtractive manufacturing stage. S3. Using electric arc wire feeding additive manufacturing, a single cylindrical hub blank (2) is produced; S4. Perform intermediate five-axis subtractive processing on the cylindrical hub (2) blank obtained by arc wire feeding additive manufacturing; S5. The completed wheel hub (2) is installed on the rotary shaft of the five-axis equipment. Starting from the outer surface of the wheel hub (2), the powder is deposited layer by layer along the target spiral trajectory to form the blade (3) by laser coaxial feeding. S6. The blade (3) is subjected to secondary finishing by five-axis CNC machining to remove the laser additive allowance and obtain the thickness, pitch and flow channel profile of the target blade (3); S7. Complete dimensional, geometrical, static or dynamic balance tests, and perform deburring, surface treatment and installation verification as needed.

2. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S1, the three-dimensional geometric data includes at least the dimensions of the central through hole (1), the dimensions of the end face (4), the blade pitch of the blade (3), and the thickness of the blade (3).

3. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S3, the wheel hub (2) blank only includes the cylindrical solid that forms the wheel hub (2), and reserves intermediate material reduction allowance for the central through hole (1), the outer circle of the wheel hub (2) and the two end faces (4).

4. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S4, the outer circle of the center through hole (1) or the positioning hub (2) is first machined to establish the rotation axis reference, and the axial end face (4) and circumferential positioning features are machined; then the outer circle of the hub (2) is finished so that the hub (2) becomes the substrate for subsequent laser additive manufacturing. The circumferential positioning features are used to cooperate with the positioning fixture to determine the angular position of the hub around its own axis.

5. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S5, the completed hub (2) is rotated 90° relative to the axial posture during arc wire feeding additive manufacturing, and the hub (2) is horizontally mounted on the rotary shaft of the five-axis equipment so that the central axis of the hub (2) coincides with the axis of the rotary shaft. The nozzle for coaxial laser powder feeding is arranged above the working point of the outer circle of the hub (2) or in its local normal direction. Through the continuous rotation of the rotary shaft and the linkage of linear axial feed, the first layer makes the laser beam and powder flow act on the outer surface of the hub in the same convergence area. Subsequent layers act on the growth part of the deposited blade, and the nozzle position is adjusted according to the radial height of the blade to form the blade (3) layer by layer along the target spiral trajectory.

6. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S5, the blade (3) is deposited layer by layer and channel by channel from the outer surface of the hub (2) to the target radial near net height. The entire continuous spiral blade (3) is formed by powder deposition, and a uniform allowance is reserved for the final five-axis subtractive material.

7. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... In step S6, after the laser coaxial powder feeding additive is completed, the workpiece is cooled and repositioned using the rotation axis of the central through hole (1) formed in step S4 or the rotation axis of the outer circle of the hub (2), end face and circumferential positioning features, or the same reference clamping is maintained. Then, five-axis CNC machining is used to perform secondary finishing on the hydraulic surface, blade edge, blade root transition area and hub (2) mating surface on both sides of the blade (3), remove the laser additive allowance and obtain the thickness, pitch and flow channel profile of the target blade (3).

8. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... The hub (2) and blades (3) are made of the same grade or metallurgically compatible materials.

9. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... Arc wire feeding additive manufacturing can employ any of the following methods: CMT, MIG / MAG, TIG wire feeding, or plasma wire feeding.

10. The emergency manufacturing method for a water pump impeller under shipboard conditions, as described in claim 1, is characterized in that... The blade (3) uses laser coaxial powder feeding method instead of side powder feeding.

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