A method for manufacturing hollow paddle blades

Abstract

This invention discloses a method for manufacturing hollow blades, comprising the following steps: (1) 3D modeling: creating a 3D model of the blade using SolidWorks; (2) Fabrication of the blanking drawing: importing the 3D model of the blade into 2D CAD software for unfolding and drawing the planar blanking drawing of the blade; (3) Blanking: cutting steel plates and round steel into hollow blade upper flange plates, lower flange plates, and reinforcing plates; (4) Fabrication of the jig; (5) Pressing of the hollow blade upper and lower flange plates; (6) Blade assembly: assembling the hollow blades using horizontal tooling; (7) Welding; (8) Inspection. This invention uses jig pressing molding, which is simple in process, does not damage the internal structure, has a large adjustment space, and allows for controllable size and shape, resulting in high blade forming accuracy.

Description

Technical Field

[0001] This invention relates to the field of agitator blade technology, and more specifically to a method for manufacturing hollow blades. Background Technology

[0002] Hollow impellers are a crucial component of mixing equipment, and their molding quality directly determines the equipment's performance. Due to the special material, high quality requirements, and difficulty in manufacturing hollow impellers, poor casting quality directly affects the mixing operation, easily leading to excessive vibration and noise during equipment operation, and impacting the service life of the bearing housing and reducer.

[0003] To address the challenges of hollow blade forming and the problems associated with excessive vibration and rapid bearing housing wear during equipment operation, and to meet stringent dimensional accuracy requirements—ensuring each blade bears uniform weight with a weight tolerance of no more than 0.5%, and the difference between blade tip and root angles ≤1°—we urgently need to improve our existing production process to resolve these defects in hollow blade manufacturing. Summary of the Invention

[0004] In view of this, the purpose of this invention is to address the shortcomings of the prior art by providing a method for manufacturing hollow blades that is simple, low-cost, and produces blades with reasonable design and stable quality.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for manufacturing hollow propeller blades includes the following steps:

[0007] (1) 3D modeling: Draw the central axis of the blade using SolidWorks, define the arc radius and inclination angle of each section along the central axis, and complete the overall profile design of the blade by lofting. Decompose the drawn profile and decompose the blade into an airfoil welded hollow blade surrounded by an upper wing plate, a lower wing plate and round steel.

[0008] (2) Making the blanking drawing: Import the three-dimensional model created in step (1) into the two-dimensional CAD software for unfolding, and draw the planar blanking drawing of the blade;

[0009] (3) Cutting: According to the cutting diagram in step (2), the steel plate and round steel are cut into hollow blade upper flange plate, lower flange plate and reinforcing plate by CNC laser and CNC plasma cutting.

[0010] (4) Making of the mold

[0011] 1) First, calculate the blade pressing springback amount based on the blade material and shape parameters. Then, model the forming surface of the jig using 3D software based on the formed blade and the springback amount. Considering the strength of the jig and the interference of the longest protruding end of the blade during pressing, offset the conversion plane downward by a set thickness and stretch it according to the shape of the projection of the contour around the surface to obtain the solid model of the 3D jig.

[0012] 2) Assemble the steel plate of the required thickness into the two curved surfaces of the jig and perform a test press;

[0013] 3) By testing the actual springback of the blades through pressure testing, the low and high point dimensions of the die are adjusted to ensure the accuracy of the actual blade pressing and forming.

[0014] 4) Fabricate the pressing die according to the adjusted die drawing;

[0015] (5) Pressing of the upper and lower blades of the hollow propeller

[0016] The upper wing section is a two-section circular arc-shaped variable cross-section variable angle curved surface, and the lower wing section is a variable angle curved surface, which are pressed by corresponding curved surface jigs respectively; (6) Blade assembly

[0017] The hollow blades are assembled using horizontal tooling. The hollow blades include an upper blade and a lower blade. After the upper blade and the lower blade are pressed and formed separately, the intersection of the upper blade and the lower blade is sealed with round steel and then welded together.

[0018] (7) Welding

[0019] The upper and lower blades are welded together using a round tube to form a hollow blade; the weld should smoothly transition to the surface of the base material, and its surface should be free of defects such as cracks, lack of fusion, porosity, slag inclusions, and burn-through.

[0020] (8) Inspection

[0021] Use a slope meter to check the angle of the hollow blades. The blade tip angle error is ≤ ±1°, and the blade root error is ≤ ±1°.

[0022] All welds shall be subjected to 100% dye penetrant testing in accordance with the provisions of JB4730-94 "Standard for Non-destructive Testing of Pressure Vessels", and shall be qualified at Level 1; the weight deviation of the blades in the same layer shall be ≤5‰.

[0023] Preferably, in step (3), a protective film is laid on the surface of the steel plate and round steel during the cutting and processing. This is to prevent scratches on the steel plate and round steel from affecting the stirring performance of the blades.

[0024] Preferably, the horizontal fixture in step (6) includes a support platform, a fixed plate and a support plate respectively vertically arranged at both ends of the support platform, an angle steel inclined between the two support plates, and multiple connecting holes on both sides of the fixed plate. The bottom plate of the hollow blade is installed on the fixed plate through the connecting holes and bolts, and the blade end of the hollow blade is fixed on the angle steel for easy measurement of the blade angle.

[0025] The beneficial effects of this invention are:

[0026] This invention employs a die-pressing molding process, which is simple, does not damage the internal structure, offers a large adjustment range, allows for controllable dimensions and shape, and results in high blade forming precision. By designing a blanking and layout diagram, cutting is more rational, saving raw materials and reducing costs. Horizontal tooling is used for blade assembly, which is easy to operate, facilitates blade angle measurement, and improves assembly accuracy. Round steel filler is used for welding, resulting in high strength, good stress resistance, and a long service life. Attached Figure Description

[0027] Figure 1 This is a three-dimensional view of the hollow blade of the present invention;

[0028] Figure 2 This is a structural diagram of a horizontal tooling fixture.

[0029] In the diagram: 1. Supporting platform, 2. Fixing plate, 3. Supporting plate, 4. Angle steel, 5. Connecting hole. Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] A method for manufacturing hollow propeller blades includes the following steps:

[0032] (1) 3D Modeling: Draw the central axis of the blade using SolidWorks, define the radius of the arc segment and the inclination angle of each section along the central axis, and complete the overall profile design of the blade by lofting. Decompose the drawn profile and decompose the blade into a hollow blade with airfoil welded together by an upper wingplate, a lower wingplate and round steel. Figure 1 As shown;

[0033] (2) Making the blanking drawing: Import the three-dimensional model created in step (1) into the two-dimensional CAD software for unfolding, and draw the planar blanking drawing of the blade;

[0034] (3) Cutting: According to the cutting diagram in step (2), the steel plate and round steel are cut into hollow blade upper flange plate, lower flange plate and reinforcing plate by CNC laser and CNC plasma cutting.

[0035] A protective film is laid on the surface of steel plates and round bars during cutting and processing to prevent scratches from appearing on the steel plates and round bars, which would affect the stirring performance of the blades.

[0036] (4) Making of the mold

[0037] 1) First, calculate the blade pressing springback amount based on the blade material and shape parameters. Then, model the forming surface of the jig using 3D software based on the formed blade and the springback amount. Considering the strength of the jig and the interference of the longest protruding end of the blade during pressing, offset the conversion plane downward by a set thickness and stretch it according to the shape of the projection of the contour around the surface to obtain the solid model of the 3D jig.

[0038] 2) Assemble the steel plate of the required thickness into the two curved surfaces of the jig and perform a test press;

[0039] 3) By testing the actual springback of the blades through pressure testing, the low and high point dimensions of the die are adjusted to ensure the accuracy of the actual blade pressing and forming.

[0040] 4) Fabricate the pressing die according to the adjusted die drawing;

[0041] (5) Pressing of the upper and lower blades of the hollow propeller

[0042] The upper flange has a cross-section consisting of two segments of circular arc-shaped variable cross-section and variable inclination surface, while the lower flange has a variable inclination surface. Both are pressed using corresponding surface jigs.

[0043] The die set is determined based on the shape and dimensions of the hollow propeller and the amount of rebound. The complete die set consists of two die sets, upper and lower, used together to press the hollow propeller blades, including the upper and lower blades.

[0044] Fabrication of the upper and lower support bases: First, based on the dimensions of the hollow propeller blades, evenly divide the upper and lower support bases into 20 left and right rib positioning lines. Cut the ribs using a CNC cutting machine or semi-automatic cutting machine according to the drawings and layout diagrams. Clean away iron oxide and spatter. Cut 20 vertical ribs, carefully identifying the specifications and materials before cutting and marking them. Then, weld the marked vertical ribs onto the fixed base of the upper and lower support bases according to their serial numbers.

[0045] Cold-pressed hollow blades: The hollow blade pressing die is fixed on a hydraulic press, the upper die seat and hydraulic rod are fixed together, and the lower die seat is fixed on the press's working platform. The hollow blade plate is placed on the die, pressed in one pass, and held for a certain period of time to release stress.

[0046] (6) Blade assembly

[0047] The hollow blades are assembled using horizontal tooling. The hollow blades include an upper blade and a lower blade. After the upper blade and the lower blade are pressed and formed separately, the intersection of the upper blade and the lower blade is sealed with round steel and then welded together.

[0048] like Figure 2The horizontal fixture includes a support platform 1, a fixed plate 2 and a support plate 3 respectively vertically arranged at both ends of the support platform 1, an angle steel 4 inclined between the two support plates 3, and multiple connecting holes 5 respectively on both sides of the fixed plate 2.

[0049] The base plate of the hollow blade is fixed on the fixed plate 2, and its front end overlaps the angle steel 4. The angle of the blade is controlled by adjusting the angle steel 4, thereby ensuring the accuracy of the blade assembly.

[0050] (7) Welding

[0051] The upper and lower blades are welded together using a round tube to form a hollow blade; the weld should smoothly transition to the surface of the base material, and its surface should be free of defects such as cracks, lack of fusion, porosity, slag inclusions, and burn-through.

[0052] (8) Inspection

[0053] Use a slope meter to check the angle of the hollow blades. The blade tip angle error is ≤ ±1°, and the blade root error is ≤ ±1°.

[0054] All welds shall be subjected to 100% dye penetrant testing in accordance with the provisions of JB4730-94 "Standard for Non-destructive Testing of Pressure Vessels", and shall be qualified at Level 1; the weight deviation of the blades in the same layer shall be ≤5‰.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for manufacturing hollow propeller blades, characterized in that, Includes the following steps: (1) 3D modeling: Draw the central axis of the blade using SolidWorks, define the arc radius and inclination angle of each section along the central axis, and complete the overall profile design of the blade by lofting. Decompose the drawn profile and decompose the blade into an airfoil welded hollow blade surrounded by an upper wing plate, a lower wing plate and round steel. (2) Making the blanking drawing: Import the three-dimensional model created in step (1) into the two-dimensional CAD software for unfolding, and draw the planar blanking drawing of the blade; (3) Cutting: According to the cutting diagram in step (2), the steel plate and round steel are cut into hollow blade upper flange plate, lower flange plate and reinforcing plate by CNC laser and CNC plasma cutting. (4) Making of the mold 1) First, calculate the blade pressing springback amount based on the blade material and shape parameters. Then, model the forming surface of the jig using 3D software based on the formed blade and the springback amount. Considering the strength of the jig and the interference of the longest protruding end of the blade during pressing, offset the conversion plane downward by the set thickness and stretch it according to the shape of the projection of the contour around the surface to obtain the solid model of the 3D jig. 2) Assemble the steel plate of the required thickness into the two curved surfaces of the jig and perform a test press; 3) By testing the actual springback of the blades through pressure testing, the low and high point dimensions of the die are adjusted to ensure the accuracy of the actual blade pressing and forming. 4) Fabricate the pressing die according to the adjusted die drawing; (5) Pressing of the upper and lower blades of the hollow propeller (6) Blade assembly The hollow blades are assembled using horizontal tooling. The hollow blades include an upper blade and a lower blade. After the upper blade and the lower blade are pressed and formed separately, the intersection of the upper blade and the lower blade is sealed with round steel and then welded together. (7) Welding The upper and lower blades are welded together using a round tube to form a hollow blade; the weld should smoothly transition to the surface of the base material, and its surface should be free of defects such as cracks, lack of fusion, porosity, slag inclusions, and burn-through. (8) Inspection Use a slope meter to check the angle of the hollow blades. The blade tip angle error is ≤ ±1°, and the blade root error is ≤ ±1°. All welds were subjected to 100% dye penetrant testing as specified in JB4730-94 "Standard for Non-destructive Testing of Pressure Vessels", and were rated as Grade 1 qualified. The weight deviation of the blades in the same layer is ≤5‰.

2. The method for manufacturing hollow blades according to claim 1, characterized in that, In step (3), a protective film is laid on the surface of the steel plate and round steel during the cutting and processing.

3. The method for manufacturing hollow blades according to claim 1, characterized in that, The horizontal fixture in step (6) includes a support platform, a fixed plate and a support plate respectively vertically arranged at both ends of the support platform, an angle steel inclined between the two support plates, and multiple connecting holes on both sides of the fixed plate.

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