A deep-well pump and a multi-beam laser welding method for an impeller thereof

Abstract

This invention discloses a multi-beam laser welding method for a deep well pump and its impeller. The impeller hub inlet radial end face has a groove, and the guide vane hub outlet radial end face has an end face convex ring and a flow channel side convex ring. The end face convex ring is clearance-fitted with the groove, and the flow channel side convex ring abuts against the flow channel side hub surface of the impeller. A through-flow channel is provided on the impeller hub outlet end face, and guide vanes are radially arranged within the channel. A through-jet channel is provided on the guide vane hub inlet end face, and guide rings are arranged within the jet channel. The axis of the through-flow channel and the axis of the jet channel are collinear, and the axis points towards the guide vane outlet position. This invention solves problems such as chatter, cavitation, noise vibration, and maintenance, thereby improving the service life of the deep well pump.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, specifically to a deep well pump, and more specifically to a multi-beam laser welding method for the deep well pump and its impeller. Background Technology

[0002] A deep well pump is a mechanical device used to extract groundwater from deep wells. Deep well pumps are characterized by their compact structure, high efficiency, and stable performance, and are widely used in agricultural irrigation, industrial water supply, and urban water supply and drainage. However, existing deep well pumps on the market typically suffer from poor flow stability at high speeds, high noise and vibration, and difficult maintenance. As demands for deep well pumps increase, the need for performance improvements is growing. Therefore, optimizing the design of deep well pumps is essential.

[0003] The prior art CN220850045U discloses a novel high-speed deep well pump, including a motor 1 and a pump body 2. The motor 1 shaft 3 directly passes through multiple impellers 4 located inside the pump body 2, thereby synchronously driving them to rotate. The motor 1 includes a barrel 5 and a front cover 6 and a rear cover 7 disposed inside the barrel 5. The front cover 6 and the barrel 5, and the rear cover 7 and the barrel 5 are fixedly connected by laser welding. In order to improve the coaxiality and stability of the shaft 3, the bearing grooves in the front cover 6 and the rear cover 7 must be concentric. The front cover 6 and the barrel 5, and the rear cover 7 and the barrel 5, which are laser welded, can obtain a strong connection. Then, they are placed in a double-spindle lathe, and the bearing grooves in the front cover 6 and the rear cover 7 are clamped once and processed twice to ensure their concentricity. In this way, the motor 1 shaft 3 can also ensure stability under high-speed operation.

[0004] However, the above structure has design limitations, and the applicant has discovered several defects during the actual application of deep well pumps: 1. At high speeds, the impeller exhibits flutter, generating significant noise that can lead to safety accidents; 2. As the pump's operating time increases, the guide vanes experience severe cavitation, resulting in severe wear and low flow efficiency; 3. The impeller, a working component, suffers from severe wear and multiple cracks, posing a significant safety hazard. Considering the complex internal waterway structure of deep well pumps and the challenges of flutter, cavitation, noise, vibration, and maintenance, the applicant proposes a multi-beam laser welding method for deep well pumps and their impellers to address these issues. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a multi-beam laser welding method for deep well pumps and their impellers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A deep well pump includes a motor, the lower end of which is connected to a support base, and the upper end of which is connected to an inlet section via a coupling. A multi-stage pump casing is fitted onto a pump shaft and fixed downstream of the inlet section. A multi-stage impeller guide vane assembly is mounted on the pump shaft and located within the multi-stage pump casing. An outlet section is installed downstream of the multi-stage pump casing. The multi-stage impeller guide vane assembly comprises an impeller and guide vanes. The impeller hub inlet radial end face has a groove, and the guide vane hub outlet radial end face has an end face convex ring and a flow channel side convex ring, wherein the end face convex ring is clearance-fitted with the groove, and the flow channel side convex ring abuts against the flow channel side hub face of the impeller. A through-flow channel is provided on the impeller hub outlet end face, and guide vanes are radially arranged within the channel. A through-flow jet channel is provided on the guide vane hub inlet end face, and guide rings are arranged within the jet channel. The axis of the channel and the axis of the jet channel are collinear, and the axis points towards the guide vane outlet position.

[0008] Furthermore, the two ends of the guide vanes are movably mounted on the wall of the guide channel via short shafts.

[0009] Furthermore, the guide ring has a triangular cross-section and is installed on the outlet side of the jet channel.

[0010] Furthermore, the impeller includes a first blade and a second blade, with the second blade fixed to the outlet end of the first blade via a connecting plate.

[0011] Furthermore, the first blade is installed between the impeller hub and the impeller cover plate, and there are buffer gaps between the second blade and the first blade, the impeller hub and the impeller cover plate.

[0012] Furthermore, the radial length of the second blade is L1, and the radial width of the inlet channel of the guide vane is L2, where 0.3L2≤L1<0.8L2.

[0013] Furthermore, the second blade is a straight-plate type blade.

[0014] A multi-beam laser welding method for an impeller, wherein the impeller is the impeller of the deep well pump, includes the following steps:

[0015] Pre-treat each impeller component to be welded to remove surface impurities and oil stains, ensuring a clean welding surface;

[0016] Fix each impeller component to be welded onto the welding fixture, and adjust the impeller position using the fixture to ensure the impeller position remains stable during the welding process;

[0017] At least three laser beams are applied simultaneously to the impeller to be welded, with one main laser beam incident vertically onto the welding area and the other auxiliary laser beams incident at an angle of 10° to 30° to the main laser beam.

[0018] During the welding process, the energy distribution and pulse frequency of each laser beam are adjusted in real time according to the material and thickness of the impeller; at the same time, the deformation of the impeller is monitored in real time by a high-precision displacement sensor, and when the deformation exceeds the preset threshold, the energy input of the laser beam and the welding speed are automatically adjusted.

[0019] After welding, the welded joint is heat-treated by heating the welded impeller to 300-500℃, holding it at that temperature for 2-4 hours, and then cooling it in the furnace to eliminate residual welding stress.

[0020] Furthermore, in the pretreatment step, a combination of chemical corrosion and mechanical grinding is used. First, the impeller surface to be welded is corroded with a nitric acid solution with a mass fraction of 5-10% for 3-5 minutes, and then mechanically ground with sandpaper with a grit size of 800-1200.

[0021] Furthermore, the tooling fixture adopts an adaptive flexible clamping structure, which can automatically adjust the clamping point and clamping force, and the tooling fixture has vibration isolation function.

[0022] Furthermore, a high-speed camera is used to acquire real-time image information of the molten pool during the welding process. Image processing algorithms are used to analyze the shape, size, and dynamic changes of the molten pool, and the parameters of the laser beam are adjusted based on the analysis results.

[0023] Furthermore, after heat treatment, ultrasonic testing and metallographic analysis are performed on the welded joint, and the defective areas are repaired by welding.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. When the impeller moves at high speed, chatter and noise problems can be caused by factors such as fluid dynamics (cavitation, unstable flow, etc.), mechanical failures (bearing damage, shaft deformation, etc.), installation and connection issues (insufficient installation accuracy, loose connections, etc.), and imbalances (uneven mass distribution, impeller damage or missing parts, etc.). Therefore, in order to better stabilize the impeller and reduce chatter, the applicant has designed a groove on the radial end face of the impeller hub inlet and an end face convex ring and a flow channel side convex ring on the radial end face of the guide vane hub outlet. The end face convex ring is fitted with the groove with a clearance, and a buffer fluid is provided in the clearance, which greatly alleviates the occurrence of chatter. In addition, the flow channel side convex ring abuts against the flow channel side hub surface of the impeller, which limits the impeller's offset in the radial direction and stabilizes the high-speed operation of the impeller.

[0026] 2. Due to unstable pressure and excessive resistance in the guide vanes, and with changes in operating conditions such as flow rate and speed, cavitation is easily generated in the guide vanes. Cavitation causes abnormal noise in the deep well pump, and the formation and rupture of bubbles seriously affect the quality and service life of the guide vanes. The applicant has installed a through-flow channel on the hub outlet side of the impeller, with guide vanes arranged radially inside the channel. A through-flow jet channel is installed on the hub inlet side of the guide vanes, with guide rings inside the jet channel. The axis of the through-flow channel is aligned with the axis of the jet channel. With collinear centerlines and the centerlines pointing towards the guide vane outlet, this structure increases the pressure of the fluid inside the guide vane, stabilizes the operating conditions, and reduces noise. In addition, the applicant has also made pressurization improvements to the guide vane inlet. For example, the impeller includes a first blade and a second blade. The second blade is fixed to the outlet end of the first blade by a connecting plate. The first blade is installed between the impeller hub and the impeller cover plate. There are buffer gaps between the second blade and the first blade, as well as between the impeller hub and the impeller cover plate. These gaps also help improve the inlet flow pattern of the guide vane, and noise and vibration are naturally reduced as a result.

[0027] 3. Prolonged operation can easily damage the impeller, primarily due to improper selection of welding materials and processes. This includes incompatible welding materials, unreasonable welding process parameters, and issues such as porosity, slag inclusions, and incomplete penetration. To address these issues, the applicant optimized the laser welding process for the impeller. This included pre-treating each impeller component to remove surface impurities and oil, ensuring a clean welding surface; fixing each component to a welding fixture and adjusting the impeller position using the fixture to ensure stability during welding; and using at least three laser beams simultaneously to target the impeller components for welding. One main laser beam is incident perpendicularly to the welding area, while the remaining auxiliary laser beams are incident at an angle of 10° to 30° to the main laser beam. During the welding process, the energy distribution and pulse frequency of each laser beam are adjusted in real time according to the impeller's material and thickness. Simultaneously, a high-precision displacement sensor monitors the impeller's deformation in real time; when the deformation exceeds a preset threshold, the energy input of the laser beams and the welding speed are automatically adjusted. After welding, the welded joint undergoes heat treatment, with the welded impeller heated to 300-500℃, held at that temperature for 2-4 hours, and then cooled in the furnace to eliminate residual welding stress. This laser welding process results in a more robust impeller weld, thereby reducing the overall machine failure rate. Attached Figure Description

[0028] Figure 1 An axial cross-sectional view of a deep well pump in the prior art;

[0029] Figure 2 This is a schematic diagram of a partially improved structure of the deep well pump of the present invention;

[0030] Figure 3 for Figure 2 An enlarged schematic diagram of part of the improved structure A of the deep well pump;

[0031] Figure 4 for Figure 2 An enlarged schematic diagram of part of the improved structure B of the deep well pump.

[0032] In the diagram: 1. Motor; 2. Support base; 3. Coupling; 4. Inlet section; 5. Multistage pump casing; 6. Pump shaft; 7. Outlet section; 8. Impeller; 81. Groove; 82. Guide channel groove; 83. Guide vane; 84. First vane; 85. Impeller cover plate; 86. Connecting plate; 87. Second vane; 9. Guide vane; 91. End face protrusion ring; 92. Flow channel side protrusion ring; 93. Jet channel groove; 94. Guide ring; 87. Radial length L1 of the second vane; 98. Radial width L2 of the inlet flow channel of the guide vane 9. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings.

[0035] like Figure 1-4 As shown, a deep well pump includes a motor 1, the lower end of which is connected to a support base 2, and the upper end of which is connected to an inlet section 4 via a coupling 3. A multi-stage pump casing 5 is fitted onto a pump shaft 6 and fixed downstream of the inlet section 4. A multi-stage impeller guide vane assembly is mounted on the pump shaft 6 and located inside the multi-stage pump casing 5. An outlet section 7 is installed downstream of the multi-stage pump casing 5. The multi-stage impeller guide vane assembly includes an impeller 8 and guide vanes 9. The impeller 8 has a groove 81 on its hub inlet radial end face, and the guide vane 9 has an end face on its hub outlet radial end face. The impeller has a convex ring 91 and a flow channel side convex ring 92, wherein the end face convex ring 91 is clearance-fitted with the groove 81, and the flow channel side convex ring 92 abuts against the flow channel side hub surface of the impeller 8; a through guide groove 82 is provided on the hub outlet end side of the impeller 8, and a guide vane 83 is provided radially inside the guide groove 82; a through jet groove 93 is provided on the hub inlet end side of the guide vane 9, and a guide ring 94 is provided inside the jet groove 93; the axis of the guide groove 82 and the axis of the jet groove 93 are collinear, and the axis points to the outlet position of the guide vane 9.

[0036] Furthermore, the guide vanes 83 are movably mounted on the wall of the guide channel 82 via short shafts at both ends.

[0037] Furthermore, the guide ring 94 has a triangular cross-section and is installed on the outlet side of the jet channel 93.

[0038] Furthermore, the impeller 8 includes a first blade 84 and a second blade 87, with the second blade 87 fixed to the outlet end of the first blade 84 via a connecting plate 86.

[0039] Furthermore, the first blade 84 is installed between the impeller hub 8 and the impeller cover plate 85, and there are buffer gaps between the second blade 87 and the first blade 84, the impeller hub 8 and the impeller cover plate 85.

[0040] Furthermore, the radial length of the second blade 87 is L1, and the radial width of the inlet channel of the guide vane 9 is L2, where 0.3L2≤L1<0.8L2.

[0041] Furthermore, the second blade 87 is a straight-plate type blade.

[0042] The second blade is not integrally formed with the first blade and installed between the impeller hub 8 and the impeller cover plate 85. This is because the second blade is placed in the cavity at the outlet of the first blade, which can better guide and rectify the flow. After rectification, the disturbance is reduced, the efficiency of the fluid entering the guide blade is improved, the guiding effect is better, and the noise and vibration are less.

[0043] A multi-beam laser welding method for an impeller, wherein the impeller is the impeller of the deep well pump, includes the following steps:

[0044] Pre-treat each impeller component to be welded to remove surface impurities and oil stains, ensuring a clean welding surface;

[0045] Fix each impeller component to be welded onto the welding fixture, and adjust the impeller position using the fixture to ensure the impeller position remains stable during the welding process;

[0046] At least three laser beams are applied simultaneously to the impeller to be welded, with one main laser beam incident vertically onto the welding area and the other auxiliary laser beams incident at an angle of 10° to 30° to the main laser beam.

[0047] During the welding process, the energy distribution and pulse frequency of each laser beam are adjusted in real time according to the material and thickness of the impeller; at the same time, the deformation of the impeller is monitored in real time by a high-precision displacement sensor, and when the deformation exceeds the preset threshold, the energy input of the laser beam and the welding speed are automatically adjusted.

[0048] After welding, the welded joint is heat-treated by heating the welded impeller to 300-500℃, holding it at that temperature for 2-4 hours, and then cooling it in the furnace to eliminate residual welding stress.

[0049] Furthermore, in the pretreatment step, a combination of chemical corrosion and mechanical grinding is used. First, the impeller surface to be welded is corroded with a nitric acid solution with a mass fraction of 5-10% for 3-5 minutes, and then mechanically ground with sandpaper with a grit size of 800-1200.

[0050] Furthermore, the tooling fixture adopts an adaptive flexible clamping structure, which can automatically adjust the clamping point and clamping force, and the tooling fixture has vibration isolation function.

[0051] Furthermore, a high-speed camera is used to acquire real-time image information of the molten pool during the welding process. Image processing algorithms are used to analyze the shape, size, and dynamic changes of the molten pool, and the parameters of the laser beam are adjusted based on the analysis results.

[0052] Furthermore, after heat treatment, ultrasonic testing and metallographic analysis are performed on the welded joint, and the defective areas are repaired by welding.

Claims

1. A deep well pump, comprising a motor (1), the lower end of which is connected to a support base (2), the upper end of which is connected to an inlet section (4) via a coupling (3), a multi-stage pump casing (5) fitted onto a pump shaft (6) and fixed downstream of the inlet section (4), a multi-stage impeller guide vane assembly mounted on the pump shaft (6) and located inside the multi-stage pump casing (5), and an outlet section (7) installed downstream of the multi-stage pump casing (5); characterized in that: The multi-stage impeller guide vane assembly includes an impeller (8) and a guide vane (9); the impeller (8) has a groove (81) on its hub inlet radial end face, and the guide vane (9) has an end face convex ring (91) and a flow channel side convex ring (92) on its hub outlet radial end face, wherein the end face convex ring (91) is clearance-fitted with the groove (81), and the flow channel side convex ring (92) abuts against the flow channel side hub face of the impeller (8); the impeller (8) has a through-flow channel (82) on its hub outlet end face, and a guide vane (83) is provided radially inside the through-flow channel (82); the guide vane (9) has a through-flow jet channel (93) on its hub inlet end face, and a guide ring (94) is provided inside the jet channel (93); the through-flow channel (82) has a through-flow channel (93) on its hub inlet end face, and a guide ring (94) is provided inside the jet channel (93); the through-flow channel (82) has a through-flow channel (93) on its hub outlet end face, and a guide vane (94) is provided inside the jet channel (93). The axis of the guide vane (93) is collinear with the axis of the jet channel (93) and the axis of the guide vane (9) points to the outlet position of the guide vane (9); the two ends of the guide vane (83) are movably mounted on the channel wall of the guide channel (82) through short shafts; the cross section of the guide ring (94) is triangular and the guide ring (94) is installed on the outlet side of the jet channel (93); the impeller (8) includes a first blade (84) and a second blade (87), the second blade (87) is fixed to the outlet end of the first blade (84) through a connecting plate (86); the first blade (84) is installed between the impeller hub (8) and the impeller cover plate (85), and there are buffer gaps between the second blade (87) and the first blade (84), and between the impeller hub (8) and the impeller cover plate (85).

2. A deep well pump as described in claim 1, characterized in that, The radial length of the second blade (87) is L1, and the radial width of the inlet channel of the guide vane (9) is L2, where 0.3L2≤L1<0.8L2.

3. A deep well pump as described in claim 2, characterized in that, The second blade (87) is a straight blade.

4. A multi-beam laser welding method for an impeller, wherein the impeller is the impeller of a deep well pump as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Pre-treat each impeller component to be welded to remove surface impurities and oil stains, ensuring a clean welding surface; Fix each impeller component to be welded onto the welding fixture, and adjust the impeller position using the fixture to ensure the impeller position remains stable during the welding process; At least three laser beams are applied simultaneously to the impeller to be welded, with one main laser beam incident vertically onto the welding area and the other auxiliary laser beams incident at an angle of 10° to 30° to the main laser beam. During the welding process, the energy distribution and pulse frequency of each laser beam are adjusted in real time according to the material and thickness of the impeller; at the same time, the deformation of the impeller is monitored in real time by a high-precision displacement sensor, and when the deformation exceeds the preset threshold, the energy input of the laser beam and the welding speed are automatically adjusted. After welding, the welded joint is heat-treated by heating the welded impeller to 300-500℃, holding it at that temperature for 2-4 hours, and then cooling it in the furnace to eliminate residual welding stress.

5. The multi-beam laser welding method for impellers as described in claim 4, characterized in that, In the pretreatment step, a combination of chemical corrosion and mechanical grinding is used. First, the impeller surface to be welded is corroded for 3-5 minutes with a nitric acid solution with a mass fraction of 5-10%, and then mechanically ground with sandpaper with a grit of 800-1200.

6. The multi-beam laser welding method for impellers as described in claim 4, characterized in that, The tooling fixture adopts an adaptive flexible clamping structure, which can automatically adjust the clamping point and clamping force, and the tooling fixture has vibration isolation function.

7. The multi-beam laser welding method for impellers as described in claim 4, characterized in that, A high-speed camera is used to acquire real-time image information of the molten pool during the welding process. Image processing algorithms are used to analyze the shape, size and dynamic changes of the molten pool, and the parameters of the laser beam are adjusted based on the analysis results.

8. The multi-beam laser welding method for an impeller as described in claim 4, characterized in that, After heat treatment, ultrasonic testing and metallographic analysis were performed on the welded joint, and the defective areas were repaired by welding.

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