Stainless steel water pump impeller and manufacturing method thereof

Abstract

The invention provides a stainless steel water pump impeller and a manufacturing method thereof, and belongs to the technical field of water pump components. The problems that in the prior art, a water pump impeller is uneven in strength distribution and insufficient in production precision are solved. The impeller comprises an impeller base, a plurality of impellers and an impeller cover, the impeller cover and impeller fan blades are disc-shaped, the impeller cover and the impeller fan blades have the same radius, the impeller cover and the impeller fan blades are installed in a concentric structure, the impeller base and the impellers are of an integrally-formed structure, the number of the impellers is multiple, and the impellers are of an arc-shaped structure and are arranged in a circumferential array mode. A shaft hole is formed in the center of the impeller base, and reinforcing convex bodies are formed around the shaft hole. The method has the advantages of uniform strength distribution, good anti-fatigue performance and high production precision.

Description

Technical Field

[0001] The invention belongs to the technical field of water pump components and relates to a stainless steel water pump impeller and a manufacturing method thereof. Background Art

[0002] Stainless steel products are widely used due to their good corrosion resistance and mechanical properties. Traditional stainless steel processing techniques, such as casting and forging, have limitations in the manufacture of some complex-shaped parts. Powder metallurgy technology solves the problem of shape complexity to a certain extent, but the existing technology still has defects such as insufficient density and unstable product performance. As an emerging technology, the injection stainless steel powder metallurgy process improves the density, mechanical properties and production efficiency of stainless steel powder metallurgy products, and accurately controls the product dimensional accuracy.

[0003] The Chinese patent with patent announcement number CN1887509A discloses a method for manufacturing a stainless steel water pump impeller, and its manufacturing process includes the following steps: (1) firstly, the mouth ring, blades, rear sealing ring, front cover plate and rear cover plate are formed by stainless steel stamping, and a plurality of insertion convex points are set on one side of the blade, and the front cover plate is provided with insertion holes equal to and matched with the number of the blade insertion convex points; (2) then the blade is placed in the positioning plate and positioned by the positioning block, and then welded to the rear cover plate; (3) the rear cover plate and blades welded together are installed in the positioning body, and then the insertion convex points of each blade are inserted into the corresponding insertion holes on the front cover plate, and then the insertion convex points are melted and welded to the front cover plate; (4) then the impeller hub, rear sealing ring and mouth ring are gradually welded into an integral structure; (5) finally, the burrs are removed to obtain the finished product. The welding is carried out by argon arc welding.

[0004] The patent provides a method for manufacturing a stainless steel water pump impeller, which uses a process for welding blades and rear cover plates. The heat generated during welding will cause thermal deformation of the blades and cover plates, making it difficult to accurately control the amount of deformation. The deformation may cause deviations in the shape and size of the blades, which may reduce the hydraulic performance of the blades. In addition, it is difficult to make the welding conditions of different welding points completely consistent, which may lead to inconsistent quality of each welding point and differences in the mechanical properties of the weld, affecting the reliability of the entire structure. Summary of the invention

[0005] The purpose of the present invention is to provide a stainless steel water pump impeller and a manufacturing method thereof in view of the above problems existing in the prior art.

[0006] One purpose of the present invention can be achieved through the following technical scheme: a stainless steel water pump impeller, comprising an impeller base, an impeller and an impeller cover, the impeller cover and the impeller are both disc-shaped and the impeller cover has the same radius and the impeller cover and the impeller are installed in a concentric structure, the impeller base and the impeller are an integrally formed structure and the number of impellers is several, the impeller is an arc-shaped structure and is arranged in a circular array, an axial hole is opened at the center of the impeller base, and a reinforcing convex body is formed around the outside of the axial hole.

[0007] In the above-mentioned stainless steel water pump impeller, a through hole is opened on the inner side of the impeller cover, and a protective ring is integrally formed at the through hole.

[0008] In the above-mentioned stainless steel water pump impeller, a limiting groove is formed on the inner side of the impeller cover, and the limiting groove has the same shape and size as the upper end of the blade.

[0009] Another object of the present invention can be achieved by the following technical solution: A method for manufacturing a stainless steel water pump impeller, comprising the following steps: A. Raw material preparation: stainless steel powder is selected and mixed evenly with the binder mixer. The binder is a mixture of polyethylene wax and polypropylene; B. Injection molding: the mold is made of mold steel that is resistant to high temperature, high strength and has good demoulding performance. The mold is equipped with a cooling system and the cooling water channels are evenly distributed. The mixed stainless steel metal powder raw materials are added to the barrel of the injection machine, heated and molten, and then injected into the pre-designed mold cavity. After cooling, demoulding is performed to obtain the injection blank; C. Degreasing treatment: the injection molded blank is placed in a degreasing furnace, which is equipped with inert gas, and the temperature is raised and kept warm for a period of time. A certain time is required to remove the binder; D. Sintering: The degreased green body is placed in a vacuum sintering furnace, and after heating and keeping the temperature, the temperature is further raised to a higher temperature and kept for a certain period of time, and then cooled to room temperature with the furnace to obtain a preliminary sintered product; E: Forging: The preliminary sintered product is forged with a special mold to improve the consistency of the density and thickness of the product material; F. Density and size refinement: The sintered product after forging is processed by hot isostatic pressing process. After the final product density reaches the required density, the product size is refined by mechanical processing. According to the product design requirements, a stainless steel powder metallurgy product that meets the precision requirements is obtained.

[0010] In the above-mentioned method for manufacturing a stainless steel water pump impeller, the mass ratio of the polyethylene wax to the polypropylene is 3:7-5:5.

[0011] In the above-mentioned method for manufacturing a stainless steel water pump impeller, the surface roughness Ra of the mold cavity is between 0.2-0.8 μm, the heating temperature of the stainless steel metal powder raw material added to the injection machine barrel is 150-200°C, the injection pressure injected into the mold cavity is 50-100 MPa, and the holding time is 5-10s.

[0012] In the above-mentioned method for manufacturing a stainless steel water pump impeller, the injection-molded blank placed in the degreasing furnace is heated to 400-500° C. at a heating rate of 0.5-1.5° C. / min and kept warm for 2-4 hours.

[0013] In the above-mentioned method for manufacturing a stainless steel water pump impeller, the degreased blank placed in a vacuum sintering furnace is first heated at a rate of 5-10°C / min to 900-1000°C, and kept warm for 1-2h. The second heating rate is 10-15°C / min and heated to 1200-1350°C, and kept warm for 2-3h.

[0014] In the above-mentioned method for manufacturing a stainless steel water pump impeller, the hot isostatic pressing pressure is 100-200MPa, the temperature is 1000-1200℃, the processing time is 1-3h, the final product density reaches 95%-99% of the theoretical density, and the product with dimension refinement through mechanical processing has a dimensional tolerance within the range of ±0.05-±0.2mm.

[0015] Compared with the prior art, the stainless steel water pump impeller and the manufacturing method thereof provided by the present invention have the following beneficial effects: 1. Through the process of integrally forming the impeller base and the impeller, there is no welding or mechanical connection between the end face of the impeller and the impeller base, so that the present invention has the advantages of uniform strength distribution, good overall strength and fatigue resistance; 2. Through the use of injection stainless steel powder metallurgy process, the density, mechanical properties and production efficiency of stainless steel powder metallurgy products are improved, and the product dimensional accuracy can be accurately controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of the stainless steel water pump impeller; Figure 2 It is a schematic diagram of the structure of the impeller base, impeller and impeller cover on one side; Figure 3 It is a schematic diagram of hydraulic efficiency data when a universal impeller is used in a water pump; Figure 4 It is a schematic diagram of hydraulic efficiency data when the present invention is used for a water pump; Figure 5 It is a diagram showing the relationship between efficiency, head and power when a universal impeller is used in a water pump; Figure 6It is a data diagram showing the relationship between efficiency, head and power when the present invention is used for a water pump.

[0017] In the figure: 1. impeller base; 11. shaft hole; 12. reinforcing convex body; 2. impeller; 3. impeller cover; 31. through hole; 32. protective ring; 33. limiting groove. DETAILED DESCRIPTION

[0018] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0019] like Figure 1 to Figure 2 As shown, the stainless steel water pump impeller includes an impeller base 1, an impeller 2 and an impeller cover 3. The impeller cover 3 and the impeller base 1 are both disc-shaped. The impeller cover 3 and the impeller base 1 have the same radius and the impeller cover 3 and the impeller base 1 are installed in a concentric structure. The impeller base 1 and the impeller 2 are formed by an integral molding process of injection molding. The number of impellers 2 is several, the impeller 2 is an arc structure and is arranged in a circular array. An axial hole 11 is opened at the center of the impeller base 1, and a reinforcing convex body 12 is formed around the outside of the axial hole 11. A through hole 31 is opened on the inner side of the impeller cover 3, and a protective ring 32 is integrally formed at the through hole 31.

[0020] To elaborate further, Figure 2 As shown, a limiting groove 33 is formed on the inner side of the impeller cover 3. The limiting groove 33 has the same shape and size as the upper end of the impeller 2. When the impeller cover 3 and the impeller 2 are welded, the upper end of the impeller 2 is aligned with the limiting groove 33 and welded to improve the fixing accuracy.

[0021] The manufacturing method of this stainless steel water pump impeller is as follows: First embodiment: Step 1: Raw material preparation, select stainless steel powder with a particle size of 10μm, mix it with a binder in a mixer at a mass ratio of 90:10, the binder is a mixture of polyethylene wax and polypropylene, wherein the mass ratio of polyethylene wax to polypropylene is 4:6; Step 2: Injection molding, the mold is made of mold steel with high temperature resistance, high strength and good demolding performance, the mold cavity surface roughness Ra is controlled at 0.2μm, the mold needs to be equipped with a cooling system, and the cooling water channel should be evenly distributed. Add the mixed raw materials into the injection machine barrel, heat to 150℃, make the raw materials molten, and then inject them into the pre-designed mold cavity. The injection pressure is 50MPa, the holding time is 5s, and the injection blank is demolded after cooling; Step 3: Degreasing treatment, place the injection blank in In the debinding furnace, under the protection of inert gas, the temperature is increased to 400°C at a heating rate of 0.5°C / min, kept warm for 2 hours, and the binder is removed; Step 4: Sintering, the debinded body is placed in a vacuum sintering furnace, first heated to 900°C at a heating rate of 5°C / min, kept warm for 1 hour, and then heated to 1200°C at a heating rate of 10°C / min, kept warm for 2 hours, and cooled to room temperature with the furnace; Step 5: Forging, the preliminary sintered product is forged with a special mold; Step 6: Density and size finishing, the sintered product after forging is processed by hot isostatic pressing process, the hot isostatic pressing pressure is 100MPa, the temperature is 1000°C, and the hot isostatic pressing treatment time is 1h, and then the product is fine-tuned by machining to control the dimensional tolerance within the range of ±0.05.

[0022] like Figure 3 to Figure 4 As shown, when driven by the same or similar current and voltage, the rotation speed of the universal impeller of model 650w in the water pump is significantly lower than the rotation speed of the water pump impeller made using this embodiment, and the hydraulic efficiency of the water pump impeller made by this embodiment is significantly higher than the hydraulic efficiency of the universal impeller of model 650w.

[0023] like Figures 5 and 6 As shown, the maximum efficiency of the water pump impeller made in this embodiment is significantly higher than the maximum efficiency of a general impeller of model 650w.

[0024] Second embodiment: Step 1: Raw material preparation, select stainless steel powder with a particle size of 30μm, mix it with a binder in a mixer at a mass ratio of 93:7, the binder is a mixture of polyethylene wax and polypropylene, and the mass ratio of polyethylene wax to polypropylene is 1:1; Step 2: Injection molding, the mold is made of mold steel with high temperature resistance, high strength and good demolding performance, the mold cavity surface roughness Ra is controlled at 0.5μm, the mold needs to be equipped with a cooling system, and the cooling water channel should be evenly distributed. Add the mixed raw materials into the injection machine barrel, heat to 180℃, make the raw materials molten, and then inject them into the pre-designed mold cavity. The injection pressure is 80MPa, the holding time is 8s, and the injection blank is demolded after cooling; Step 3: Degreasing treatment, place the injection blank in a degreasing In a fat furnace, under the protection of inert gas, the temperature is increased to 450°C at a heating rate of 1°C / min, kept warm for 3 hours, and the binder is removed; Step 4: Sintering, the degreased green body is placed in a vacuum sintering furnace, first heated to 950°C at a heating rate of 8°C / min, kept warm for 1.5 hours, and then heated to 1300°C at a heating rate of 13°C / min, kept warm for 2.5 hours, and cooled to room temperature with the furnace; Step 5: Forging, the preliminary sintered product is forged with a special mold; Step 6: Density and size refinement, the sintered product after forging is processed by hot isostatic pressing process, the hot isostatic pressing pressure is 150MPa, the temperature is 1100°C, and the hot isostatic pressing treatment time is 2 hours, and then the product is refined by machining to control the dimensional tolerance within the range of ±0.01.

[0025] Third embodiment: Step 1: Raw material preparation, select stainless steel powder with a particle size of 50μm, mix it with a binder in a mixer at a mass ratio of 95:5, the binder is a mixture of polyethylene wax and polypropylene, and the mass ratio of polyethylene wax to polypropylene is 5:5; Step 2: Injection molding, the mold is made of mold steel with high temperature resistance, high strength and good demolding performance, the mold cavity surface roughness Ra is controlled at 0.8μm, the mold needs to be equipped with a cooling system, and the cooling water channel should be evenly distributed. Add the mixed raw materials into the injection machine barrel, heat to 200℃, make the raw materials molten, and then inject them into the pre-designed mold cavity. The injection pressure is 100MPa, the holding time is 10s, and the injection blank is demolded after cooling; Step 3: Degreasing treatment, place the injection blank in In the debinding furnace, under the protection of inert gas, the temperature is increased to 500°C at a heating rate of 1.5°C / min, kept warm for 4 hours, and the binder is removed; Step 4: Sintering, the debinded body is placed in a vacuum sintering furnace, first heated to 1000°C at a heating rate of 10°C / min, kept warm for 2 hours, and then heated to 1350°C at a heating rate of 15°C / min, kept warm for 3 hours, and cooled to room temperature with the furnace; Step 5: Forging, the preliminary sintered product is forged with a special mold; Step 6: Density and size refinement, the sintered product after forging is processed by hot isostatic pressing process, the hot isostatic pressing pressure is 200MPa, the temperature is 1200°C, and the hot isostatic pressing treatment time is 3 hours, and then the product is refined by machining to control the dimensional tolerance within the range of ±0.02.

[0026] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0027] Although various terms are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A stainless steel water pump impeller, characterized in that: The invention comprises an impeller base (1), an impeller (2) and an impeller cover (3) made of stainless steel. The impeller cover (3) and the impeller base (1) are both disc-shaped and have the same radius as the impeller base (1). The impeller cover (3) and the impeller base (1) are installed in a concentric structure. The impeller base (1) and the impeller (2) are an integrally formed structure. The number of impellers (2) is a plurality. The impellers (2) are arc-shaped and arranged in a circular array. An axial hole (11) is opened at the center of the impeller base (1), and a reinforcing convex body (12) is formed around the outer periphery of the axial hole (11).

2. A stainless steel water pump impeller according to claim 1, characterized in that: A through hole (31) is provided on the inner side of the impeller cover (3), and a protective ring (32) is integrally formed at the through hole (31).

3. A stainless steel water pump impeller according to claim 1, characterized in that: A limiting groove (33) is formed on the inner side of the impeller cover (3), and the limiting groove (33) has the same shape and size as the upper end of the impeller (2).

4. A method for manufacturing a stainless steel water pump impeller, characterized in that: The method comprises the following steps: A. Raw material preparation: stainless steel powder is selected and mixed evenly with the binder mixer. The binder is a mixture of polyethylene wax and polypropylene; B. Injection molding: the mold is made of mold steel that is resistant to high temperature, high strength and has good demoulding performance. The mold is equipped with a cooling system and the cooling water channels are evenly distributed. The mixed stainless steel metal powder raw materials are added to the barrel of the injection machine, heated and molten, and then injected into the pre-designed mold cavity. After cooling, demoulding is performed to obtain the injection blank; C. Degreasing treatment: the injection molded blank is placed in a degreasing furnace, which is equipped with inert gas, and the temperature is raised and kept warm for a period of time. A certain time is required to remove the binder; D. Sintering: The degreased green body is placed in a vacuum sintering furnace, and after heating and keeping the temperature, the temperature is further raised to a higher temperature and kept for a certain period of time, and then cooled to room temperature with the furnace to obtain a preliminary sintered product; E: Forging: The preliminary sintered product is forged with a special mold to improve the consistency of the density and thickness of the product material; F. Density and size refinement: The sintered product after forging is processed by hot isostatic pressing process. After the final product density reaches the required density, the product size is refined by mechanical processing. According to the product design requirements, a stainless steel powder metallurgy product that meets the precision requirements is obtained.

5. The method for manufacturing a stainless steel water pump impeller according to claim 4, characterized in that: The mass ratio of the polyethylene wax to polypropylene is 3:7-5:

5.

6. The method for manufacturing a stainless steel water pump impeller according to claim 4, characterized in that: The surface roughness Ra of the mold cavity is between 0.2-0.8 μm, the heating temperature of the stainless steel metal powder raw material added to the injection machine barrel is 150-200° C., the injection pressure into the mold cavity is 50-100 MPa, and the holding time is 5-10s.

7. The method for manufacturing a stainless steel water pump impeller according to claim 4, characterized in that: The injection molded green body placed in the degreasing furnace is heated to 400-500° C. at a heating rate of 0.5-1.5° C. / min and kept warm for 2-4 hours.

8. The method for manufacturing a stainless steel water pump impeller according to claim 4, characterized in that: The degreased green body placed in the vacuum sintering furnace is first heated to 900-1000°C at a rate of 5-10°C / min and kept warm for 1-2h, and then heated to 1200-1350°C at a secondary heating rate of 10-15°C / min and kept warm for 2-3h.

9. The method for manufacturing a stainless steel water pump impeller according to claim 4, characterized in that: The hot isostatic pressing pressure is 100-200MPa, the temperature is 1000-1200°C, the processing time is 1-3h, and the final product density reaches 95%-99% of the theoretical density. The product with refined dimensions through mechanical processing has a dimensional tolerance within the range of ±0.05-±0.2mm.

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