A method for manufacturing a stainless steel composite stirring shaft support frame

Abstract

A method for manufacturing a stainless steel composite stirring shaft and support frame is disclosed. The main shaft is made of large-diameter, thick-walled carbon steel pipe lined with 6-12mm thick 904L stainless steel. A reasonable design of the connection node structure between the main shaft and the support frame, along with a complete manufacturing process, significantly reduces the cost of chemical reaction tank agitators while ensuring the rigidity and operational stability of the stirring shaft in chemical production, extending the overall service life of the agitator, and improving the stirring effect of the chemical reaction tank. The steps are as follows: First, design the support frame; then, process the large-diameter, thick-walled carbon steel pipe and the stainless steel sleeve; cut and weld the support frame; process the blade mounting end face; assemble and weld the stainless steel composite stirring shaft to the carbon steel pipe; conduct an airtightness test; and then accept the product. This invention is simple, easy to operate, and low-cost. The stainless steel sleeve over the carbon steel pipe is resistant to high-temperature and strong acid corrosion and abrasion, ensuring the rigidity of the stirring shaft, extending its service life and improving the stirring effect. It is easy to promote and apply, and has good economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of machining, specifically a method for manufacturing a stainless steel composite stirring shaft support frame. Background Technology

[0002] The operation of agitators in chemical reaction tanks (vessels, tanks) plays a crucial role in material mixing, reaction, dissolution, suspension, dispersion, and heat transfer. Proper mixing of reactants ensures heat and mass transfer within the tank, thereby improving reaction rate and efficiency. However, in chemical reactions, especially in phosphorus and copper-lead-zinc chemical reaction tanks, agitation often occurs in high-temperature, strong-acid, and high-solids-content environments, containing highly corrosive media such as chloride and fluoride ions. This easily causes wear and corrosion to the agitator shaft. Therefore, chemical agitator shafts often require corrosion-resistant stainless steel materials such as 2205, 2507, and 904L. However, these stainless steels are expensive, increasing production and operating costs.

[0003] Furthermore, due to corrosion prevention requirements, bottom bearings are not permitted in the tanks of chemical agitators, and the agitator shafts are mostly cantilevered structures. Therefore, high rigidity is required for the agitator shaft, necessitating the use of large-diameter, thick-walled steel pipes in the design, which further increases production costs. Thus, how to reduce the cost of chemical reaction agitators while ensuring the rigidity, service life, and agitation effect of the agitator shaft is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] To address the above issues and overcome the shortcomings of existing technologies, the present invention aims to provide a method for manufacturing a stainless steel composite stirring shaft and support frame. The main shaft is constructed using a large-diameter, thick-walled carbon steel pipe lined with 6-12mm thick 904L stainless steel. A rationally designed connection structure between the main shaft and the support frame, along with a complete manufacturing process, significantly reduces the cost of chemical reaction tank agitators while ensuring the rigidity and operational stability of the stirring shaft in chemical production, extending the overall service life of the agitator, and improving the stirring effect of the chemical reaction tank. The steps are as follows: (1) First, design a support frame. The support frame includes a stainless steel sleeve, a carbon steel pipe and a support frame. The carbon steel pipe 1 has stainless steel sleeves 5 tightly fitted on both ends and connected together symmetrically. The support frame is a frame formed by connecting a transverse support 2 and a longitudinal support 6. The corresponding end of the transverse support 2 is welded to the corresponding end of the stainless steel sleeve 5 and the carbon steel pipe 1 via a welding point 4. The longitudinal support 6 has symmetrical mounting holes 7 at both ends for installing the stirring blades. (2) Processing of large diameter thick-walled carbon steel pipes: Due to the ellipticity and perpendicularity deviation of carbon steel pipe materials, the outer wall surface of carbon steel pipes needs to be processed. According to the tolerance requirements of the straightness, perpendicularity, surface roughness and other aspects of the composite stirring shaft, the required carbon steel pipes are prepared. (3) Stainless steel sleeve processing: one end of the stainless steel sleeve is processed into a 30° bevel to facilitate welding; (4) Support frame cutting: The support frame is a frame composed of horizontal support and longitudinal support connected together. The corresponding end of the horizontal support is welded to the corresponding end of the stainless steel sleeve and the carbon steel pipe through a welding point. The upper and lower ends of the longitudinal support are provided with symmetrical mounting holes for installing the stirring blades. Laser cutting is used for cutting. (5) Welding of support frame: The support frame is spliced ​​on the platform and welded in multiple layers and multiple passes in sequence. Welding slag and spatter are removed with a stainless steel wire brush. (6) Processing of blade mounting end face: First, process the support frame panel at the connection with the blade base plate, then process the 20° single-sided bevel at the panel hole diameter at the connection with the tube shaft, and process the connecting bolt mounting holes of the blade base plate and the support frame on the blade base plate. (7) Pipe and shaft assembly: The stainless steel composite stirring shaft and the carbon steel pipe are assembled on the platform. The stainless steel pipe and the carbon steel pipe are welded together to ensure the fit between them.

[0005] (8) Welding: The support frame is welded to the carbon steel pipe and the support frame is welded to the stainless steel sleeve. The welding process is strictly carried out in accordance with the process card. (9) Air tightness test The airtightness test is strictly carried out in accordance with GB150.1-GB150.4 "Pressure Vessels" and "Safety Technical Inspection Regulations for Stationary Pressure Vessels". If there is a leak, it must be repaired and retested, pickled and passivated until it passes the test, so as to realize the fabrication of the stainless steel composite agitator shaft support frame.

[0006] The method of this invention is simple, easy to operate, and low in cost. The carbon steel pipe is fitted with a stainless steel sleeve, which is resistant to high temperature and strong acid corrosion and abrasion, ensuring the rigidity of the stirring shaft, extending its service life and stirring effect. It is easy to promote and apply, and has good economic and social benefits. Attached Figure Description

[0007] Figure 1 This is a structural diagram of the stainless steel composite stirring shaft support frame of the present invention. Detailed Implementation

[0008] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and specific circumstances.

[0009] Depend on Figure 1 As shown, the manufacturing method of a stainless steel composite stirring shaft support frame of the present invention includes the following steps: (1) First, design a support frame. The support frame includes a stainless steel sleeve, a carbon steel pipe and a support frame. The carbon steel pipe 1 has stainless steel sleeves 5 tightly fitted on both ends and connected together symmetrically. The support frame is a frame formed by connecting a transverse support 2 and a longitudinal support 6. The corresponding end of the transverse support 2 is welded to the corresponding end of the stainless steel sleeve 5 and the carbon steel pipe 1 via a welding point 4. The longitudinal support 6 has symmetrical mounting holes 7 at both ends for installing the stirring blades. (2) Processing of large diameter thick-walled carbon steel pipe: Carbon steel pipe 1 is made of φ508×40 carbon steel pipe material. Due to the ellipticity, straightness and roughness deviation of carbon steel pipe material, in the case of stainless steel composite stirring shaft, the outer circle of carbon steel pipe needs to be machined by turning, with 1mm machining on one side, to process into carbon steel pipe with size of φ506×38, while ensuring its roundness ≤0.5mm, straightness ≤5mm / m and roughness ≤3.2μm design and manufacturing requirements; (3) Stainless steel sleeve processing: 904L stainless steel is rolled into a matching arc, small holes are drilled on the stainless steel for plug welding to make stainless steel sleeve 5, and one end of it is processed into a 30° bevel for easy welding. (4) Support frame cutting: The support frame is a 2507 stainless steel frame formed by connecting the transverse support 2 and the longitudinal support 6. The corresponding end of the transverse support is welded to the corresponding end of the stainless steel sleeve and the carbon steel pipe by solder (soldering point). The upper and lower ends of the longitudinal support are provided with symmetrical mounting holes for installing the stirring blades. Laser cutting is used when cutting the material. (5) Welding of support frame: Place the laser-cut horizontal support 2 and longitudinal support 6 on the platform and weld them together in multiple layers and multiple passes. Use a stainless steel wire brush to remove welding slag and spatter. (6) Processing of blade mounting end face: First, process the support frame panel at the connection with the blade base plate. Process the thickness 0-5mm according to the deviation. Then, process the hole diameter of the panel at the connection with the tube shaft to φ508mm and process a 20° single-sided bevel. Then, process the bolt mounting holes for connecting the blade base plate and the support frame. Drill the bolt holes for connecting the blade base plate and the support frame. (7) Pipe and shaft assembly: The stainless steel composite stirring shaft and carbon steel pipe 1 are assembled on the platform. The carbon steel pipe is fitted with a stainless steel sleeve. The support frame is assembled with carbon steel pipe 1. During the assembly process, the support frame is kept horizontal and vertical. Welding points are added between the stainless steel pipe and the carbon steel pipe to ensure the fit between the two. (8) Welding: The support frame is welded to the carbon steel pipe 1 using ER2594 welding wire, and the support frame is welded to the stainless steel sleeve 5 using ER385 welding wire to form weld point 4. The welding process is strictly carried out according to the process card. (9) Air tightness test The airtightness test is strictly carried out in accordance with GB150.1-GB150.4 "Pressure Vessels" and "Safety Technical Inspection Regulations for Stationary Pressure Vessels". If there is a leak, it must be repaired and retested, pickled and passivated until it passes the test, so as to realize the fabrication of the stainless steel composite agitator shaft support frame.

[0010] For ease of use and to ensure effectiveness, the carbon steel pipe 1 is a hollow circle with an outer diameter ≥426mm and a wall thickness ≥25mm. The stainless steel sleeve 5 has a wall thickness of 6-12mm, and its inner diameter is 0.5-2mm larger than the outer diameter of the carbon steel pipe 1.

[0011] The end of the transverse support 2, the inner end of the stainless steel sleeve 5, and the outer wall of the carbon steel pipe 1 form a triangular weld, and the transverse support 2, the stainless steel sleeve 5, and the carbon steel pipe 1 are firmly welded together by the weld point 4. A reinforcing rib plate 9 is installed between the transverse support 2 and the longitudinal support 6.

[0012] The aforementioned airtightness test is: 1. After each product passes the overall inspection, an airtightness test is conducted.

[0013] 2. All safety accessories must be fully assembled, and all bolts at the connection points must be fully assembled and properly tightened.

[0014] 3. Gas source preparation: The gas used in the test should be dry, clean air, nitrogen, or other inert gas.

[0015] 4. Pressure gauges: Use two pressure gauges with the same range that have been calibrated and are within their validity period. The range of the pressure gauges should be 1.5 to 3 times the maximum allowable working pressure, and the accuracy of the pressure gauges should be no less than 1.6 grade.

[0016] 5. Pressure gauge installation: The pressure gauge should be installed on the top of the container being tested in a position that is easy to observe.

[0017] 6. Pressure test: 1) Pressure Test: First, slowly increase the pressure to 10% of the specified test pressure, hold the pressure for a sufficient time, and conduct an initial inspection of all welds and connections. If there is no leakage, continue to increase the pressure to 50% of the specified test pressure. If no abnormalities are observed, then gradually increase the pressure in increments of 10% of the specified test pressure until the test pressure is reached, and hold the pressure for 30 minutes. Then, reduce the pressure to the specified design pressure, hold the pressure for a sufficient time, and conduct an inspection.

[0018] 2) Air tightness test: The air tightness test can only be carried out after the pressure resistance test. During the test, the pressure should be increased slowly, and after reaching the specified test pressure, the pressure should be maintained for 10 minutes. All welded joints and connection parts should be checked for leakage.

[0019] 3) During the inspection, the pressure should remain constant, and continuous pressurization shall not be used to maintain the test pressure.

[0020] 4) Tightening bolts under pressure is strictly prohibited during the test.

[0021] 8. For the pneumatic and airtightness tests, the following conditions shall be met for passing: 1) There shall be no abnormal noise during the test. 2) There shall be no visible deformation. 3) There shall be no air leakage detected by soap solution or other leak detection methods.

[0022] 9. Repair: In case of leakage, retest shall be carried out after repair.

[0023] It can be clearly seen from the above that the method of the present invention is simple and easy to operate. It is an improvement on the stirring structure of the original stirrer. That is, a support device is installed on the stirring shaft, and the original stirring blades are directly installed on the stirring shaft and changed to be installed on the support device. This not only prevents the corrosion of the stainless steel composite stirring shaft by the material, strengthens the protection of the stainless steel composite stirring shaft, ensures the stiffness (rigidity) and service life, but also saves materials and reduces costs. Taking the φ508×40mm pipe shaft applied to a 700m³ reaction tank as an example, the pipe shaft length is about 10m. If the whole is made of 904L material, the pipe shaft weight is about 4.6t, and the unit price of 904L pipe material is about 100,000 yuan / t. If a carbon steel lined with 6mm stainless steel composite pipe shaft is used, the carbon steel pipe shaft weight is about 4.6t, the 904L stainless steel weight is 0.76t, and the unit price of Q355B material is about 4,500 yuan / t. The material cost of a single pipe shaft can be saved by about 380,000 yuan, having good economic and social benefits.

Claims

1. A method for manufacturing a stainless steel composite stir shaft support frame, characterized by, The steps are as follows: (1) First, design a support frame, which includes a stainless steel sleeve, a carbon steel pipe and a support frame. The carbon steel pipe (1) has symmetrical stainless steel sleeves (5) tightly fitted on both ends. The support frame is a frame formed by connecting a transverse support (2) and a longitudinal support (6). The corresponding end of the transverse support (2) is welded to the corresponding end of the stainless steel sleeve (5) and the carbon steel pipe (1) via a welding point (4). The longitudinal support (6) has symmetrical mounting holes (7) at both ends for installing the stirring blades. (2) Processing of large diameter thick-walled carbon steel pipe: (1) Carbon steel pipe (1) φ508×40 carbon steel pipe material. Due to the ellipticity, straightness and roughness deviation of carbon steel pipe material, in the case of stainless steel composite stirring shaft, the outer circle of carbon steel pipe needs to be machined by turning, with 1mm machining on one side, to process into carbon steel pipe with size of φ506×38, while ensuring its roundness ≤0.5mm, straightness ≤5mm / m and roughness ≤3.2μm design and manufacturing requirements; (3) Stainless steel sleeve processing: 904L stainless steel is rolled into a matching arc, small holes are drilled on the stainless steel for plug welding to make stainless steel sleeve (5), and one end of it is processed into a 30° bevel for easy welding. (4) Support frame cutting: The support frame is a 2507 stainless steel frame formed by connecting the transverse support (2) and the longitudinal support (6). The corresponding end of the transverse support is welded to the corresponding end of the stainless steel sleeve and the carbon steel pipe by solder. The upper and lower ends of the longitudinal support are provided with symmetrical mounting holes for installing the stirring blades. Laser cutting is used when cutting the material. (5) Welding of support frame: Place the laser-cut transverse support (2) and longitudinal support (6) on the platform and weld them together in multiple layers and multiple passes. Use a stainless steel wire brush to remove welding slag and spatter. (6) Processing of blade mounting end face: First, process the support frame panel at the connection with the blade base plate. Process the thickness 0-5mm according to the deviation. Then, process the panel hole diameter at the connection with the tube shaft to φ508mm and process a 20° single-sided bevel. Then, process the bolt mounting holes for connecting with the support frame on the blade base plate. The bolt holes for connecting the blade base plate and the support frame are drilled. (7) Pipe and shaft assembly: The stainless steel composite stirring shaft and the carbon steel pipe (1) are assembled on the platform. The carbon steel pipe is fitted with a stainless steel sleeve. The support frame is assembled with the carbon steel pipe (1). During the assembly process, the support frame is kept horizontal and vertical. The stainless steel pipe and the carbon steel pipe are added with plug welds to ensure the fit between the two. (8) Welding: The support frame is welded to the carbon steel pipe (1) with ER2594 welding wire, and the support frame is welded to the stainless steel sleeve (5) with ER385 welding wire, so that the end of the transverse support (2), the inner end of the stainless steel sleeve (5) and the outer wall of the carbon steel pipe (1) form a triangular weld. The transverse support (2), stainless steel sleeve (5) and carbon steel pipe (1) are firmly welded together through the welding point (4). The welding process is strictly carried out according to the process card. Then, an air tightness test is carried out, and pickling and passivation are performed until it is qualified, thereby realizing the production of the stainless steel composite stirring shaft support frame.

2. The method of claim 1, wherein the stainless steel composite stir shaft support frame is made of a plurality of stainless steel plates. The carbon steel pipe (1) is hollow and round, with an outer diameter ≥426mm and a wall thickness ≥25mm.

3. The method for manufacturing the stainless steel composite stirring shaft support frame according to claim 1, characterized in that, The stainless steel sleeve (5) has a wall thickness of 6-12mm, and the inner diameter of the stainless steel sleeve (5) is 0.5-2mm larger than the outer diameter of the carbon steel pipe (1).

4. The method for manufacturing the stainless steel composite stirring shaft support frame according to claim 1, characterized in that, A reinforcing rib (9) is installed between the lateral support (2) and the longitudinal support (6).

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