A casting method for partial blades of large propellers

Abstract

The present invention discloses a method for casting and molding a partial blade of a large propeller, comprising the following steps: S1: determining a damaged area of ​​the propeller blade; S2: determining a position of the damaged area in a large pitch gauge coordinate system; S3: determining the origin of a small pitch gauge coordinate system; S4: converting the coordinates of a measuring point in the large pitch gauge and small pitch gauge coordinate systems; S5: casting and molding the damaged partial blade, measuring the measuring point on a sand mold, making a pressure surface and a false blade mold, and pounding the mold into a box, cleaning the false blade mold after unpacking, and obtaining the mold of the damaged partial blade after packing the box; the present invention converts the coordinates in the large and small pitch gauge coordinate systems and performs blade casting. The partial blade manufactured by this method can accurately measure the sand mold of the damaged blade and mold it without occupying a large workstation and a large digital pitch gauge, thereby improving the propeller repair efficiency and reducing the production cost. The method is used for quickly and segmentally manufacturing a large propeller sand mold when only low-cost and convenient small tools are available.

Description

Technical Field

[0001] The invention relates to a casting molding technology, in particular to a casting molding method for a partial blade of a large propeller. Background Art

[0002] Modern ship propellers rotate at high speeds during use, and sometimes colliding with hard objects can cause damage to the blade tips, which can be as minor as bending and deformation, or even severe as fracture. The most efficient and economical remedial measure for ship propellers with damaged blade tips is to remove the damaged tip, cast a new tip, and butt-weld the new cast part to the original propeller. In the existing technology, the newly cast propeller tip is often measured using the same casting sand mold method as the original propeller. This casting method requires the use of a large digital pitch gauge and occupies the already tight large propeller casting molding station. If a large pitch gauge is not used for measurement and only cross-sectional template molding is used, problems such as large blank size deviation and large margins will result, increasing the workload of subsequent processes. Summary of the Invention

[0003] In order to overcome the problems of large deviation, occupation of large casting stations and low propeller repair efficiency in existing propeller blade casting methods, the present invention provides a casting method for partial blades of a large propeller.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned object is: a casting molding method for a partial blade of a large propeller, comprising the following steps:

[0005] S1: Determine the damaged area of ​​the propeller blade;

[0006] S2: Determine the position of the damaged area in the large pitch gauge coordinate system;

[0007] S3: Determine the origin of the small pitch gauge coordinate system, including the following steps:

[0008] S3-1: Draw the orthographic projection contour diagram 5 of the damaged propeller blade area, the center of the large pitch gauge coordinate system 1, the reference axis, the center line, and arcs of different measuring ranges on the mapping software, and select multiple measurement points 6 where the orthographic projection contour diagram and the arcs of different measuring ranges overlap;

[0009] S3-2: Draw a circle based on the measuring range of the small pitch gauge: The center 2 of the small pitch gauge is set on the center line of the large pitch gauge. Move the small pitch gauge range 4 along the center line to draw a circle. The circle drawn completely covers the orthographic projection outline of the damaged area. Ensure that all measuring points 6 are within the measuring radius of the small pitch gauge.

[0010] S4: Coordinate conversion: The coordinates of measuring point 6 are all cylindrical coordinates, which include radius, angle, and height. The coordinates of measuring point 6 in the large pitch gauge coordinate system are converted to the small pitch gauge coordinate system. During the conversion, the reference axis of the coordinate system is translated, and the height value remains unchanged. The radius and angle of each measuring point 6 are changed. According to the cosine theorem and trigonometric function formulas, the coordinates of each measuring point 6 in the small pitch gauge coordinate system after conversion are calculated;

[0011] S5: Casting the damaged blade part, including the following steps:

[0012] S5-1: According to the coordinates of each measuring point 6 in the small pitch gauge coordinate system after conversion in S4, measure each measuring point 6 on the sand mold, use the points to draw lines, use the lines to draw surfaces, and make a pressure surface;

[0013] S5-2: Use section plates to create a false leaf shape in the damaged area;

[0014] S5-3: Apply mold release agent to the entire suction surface of the false blade, put it into the box, clean the false blade after unpacking, and obtain the shape of the damaged blade after closing the box.

[0015] Preferably, in said S1, the damaged area of ​​the propeller blade is located at the tip of the propeller blade, is curled toward the inside of the blade and has a large number of microcracks thereon.

[0016] Preferably, said S2 includes the following steps:

[0017] S2-1: Measure the outer dimensions of the damaged area;

[0018] S2-2: Prepare the propeller blade orthographic outline drawing according to the propeller blade drawing and make a 1:1 sample;

[0019] S2-3: Compare and analyze the measured outer contour dimensions of the damaged area with the prepared blade orthographic projection contour map to determine the position of the damaged area in the large pitch gauge coordinate system.

[0020] Preferably, in S3-2, a margin of 10-20 mm is added along the cutting line at the edge of the orthographic projection contour.

[0021] Preferably, in said S4, the radius of the large pitch gauge is set to R, the coordinates of the measuring point on the large pitch gauge are (R, α, H), and the coordinates of the measuring point on the small pitch gauge coordinate system after conversion are (r, α x , h), according to the cosine theorem and trigonometric function formula, the conversion formula is as follows:

[0022]

[0023]

[0024] h=H

[0025] Where R is the radius of the measuring point on the large pitch gauge coordinate system section, α is the angle of the measuring point relative to the center of the large pitch gauge, H is the height of the measuring point in the large pitch gauge coordinate system, R x is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r is the radius of the measuring point in the small pitch gauge coordinate system, α x is the angle of the measuring point relative to the center of the small pitch gauge, and h is the height of the measuring point in the small pitch gauge coordinate system.

[0026] Preferably, three measuring points A, B, and C are selected on the 0.9R section, and the coordinate of point A on the large pitch gauge coordinate system is (R 0.9 , 0°, H1), that is, α=0°. After conversion, the coordinates in the small pitch gauge coordinate system are (r1, α1, h1). The conversion process is as follows:

[0027] r1=|R 0.9 -R0|

[0028] α1=0°

[0029] h1=H1

[0030] Among them, R 0.9 is the radius of point A on the 0.9R section of the large pitch gauge coordinate system, 0° is the angle of point A relative to the center of the large pitch gauge, H1 is the height of point A in the large pitch gauge coordinate system, R0 is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r1 is the radius of point A in the small pitch gauge coordinate system, α1 is the angle of point A relative to the center of the small pitch gauge, and h1 is the height of point A in the small pitch gauge coordinate system;

[0031] The coordinates of point B in the large pitch gauge coordinate system are (R 0.9 , 5°, H2), that is, α=5°. After conversion, the coordinates in the small pitch gauge coordinate system are (r2, α2, h2). The conversion process is as follows:

[0032]

[0033]

[0034] h2=H2

[0035] Among them, R 0.9 is the radius of point B on the 0.9R section of the large pitch gauge coordinate system, 5° is the angle of point B relative to the center of the large pitch gauge, H2 is the height of point B in the large pitch gauge coordinate system, r2 is the radius of point B in the small pitch gauge coordinate system, α2 is the angle of point B relative to the center of the small pitch gauge, and h2 is the height of point B in the small pitch gauge coordinate system;

[0036] The coordinates of point C on the large pitch gauge coordinate system are set as (R 0.9 , 10°, H3), that is, α=10°. After conversion, the coordinates in the small pitch gauge coordinate system are (r3, α3, h3). The conversion process is as follows:

[0037]

[0038]

[0039] h3=H3

[0040] Among them, R 0.9 is the radius of point C on the 0.9R section of the large pitch gauge coordinate system, 10° is the angle of point C relative to the center of the large pitch gauge, H3 is the height of point C in the large pitch gauge coordinate system, r3 is the radius of point C in the small pitch gauge coordinate system, α3 is the angle of point C relative to the center of the small pitch gauge, and h3 is the height of point C in the small and large pitch gauge coordinate systems.

[0041] The present invention provides a casting and molding method for a partial blade of a large propeller. The method determines the position of a damaged blade tip area in the coordinate system of a large pitch gauge, draws a contour diagram of the damaged blade tip area after adding a margin on a drawing software, draws a circle to cover the entire damaged blade tip contour area according to the measuring range of a small pitch gauge, converts the coordinates of the measuring point in the coordinate system of the large pitch gauge into the coordinates of the small pitch gauge coordinate system, and then measures the converted coordinates on a sand mold to cast the damaged blade. The partial blade manufactured by this method can accurately measure the sand mold and mold the damaged blade without occupying a large workstation and a large digital pitch gauge, thereby improving the propeller repair efficiency and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of coordinate conversion between a large pitch gauge and a small pitch gauge of the present invention;

[0043] Figure 2 This is a schematic diagram of a method for measuring the radius and angle of a small pitch gauge according to the present invention;

[0044] Figure 3 This is a schematic diagram of the 0.9R section measurement points.

[0045] In the figure: 1. Center of the large pitch gauge; 2. Center of the small pitch gauge; 3. Maximum measuring range of the large pitch gauge; 4. Measuring range of the small pitch gauge; 5. Orthographic projection outline of the damaged area; 6. Measuring point. DETAILED DESCRIPTION

[0046] The present invention provides a casting method for a partial blade of a large propeller, comprising: Figures 1 to 3As shown, a casting method for a partial blade of a large propeller includes the following steps:

[0047] S1: Identify the damaged area of ​​the propeller blade. The damaged area is located at the propeller blade tip, curling inward and with a large number of microcracks. If not replaced, accidents are likely to occur, and it cannot be remedied by heat correction or welding. It needs to be removed and replaced.

[0048] S2: Determine the position of the damaged area in the large pitch gauge coordinate system. The damaged propeller blade is generally still mounted on the tail shaft, and some parts are even immersed in seawater. To determine the position of the damaged blade tip in the large pitch gauge coordinate system, the following steps are included:

[0049] S2-1: Measure the outer dimensions of the damaged area;

[0050] S2-2: Prepare the propeller blade orthographic outline drawing according to the propeller blade drawing and make a 1:1 sample;

[0051] S2-3: Compare and analyze the measured outer contour dimensions of the damaged area with the manufactured blade orthographic projection contour map to determine the approximate position of the damaged area in the large pitch gauge coordinate system. For subsequent processing of the butt welding groove, a certain edge allowance needs to be added, generally 10-20 mm along the cutting line.

[0052] S3: Determine the origin of the small pitch gauge coordinate system, including the following steps:

[0053] S3-1: Draw the orthographic projection contour diagram 5 of the damaged propeller blade area, the center of the large pitch gauge coordinate system 1, the reference axis based on the center of the circle, the centerline, the maximum measuring range of the large pitch gauge, and arcs of different measuring ranges in CAD, SolidWorks, or Siemens NX7.0 drawing software. Select multiple measurement points 6 where the orthographic projection contour diagram and the arcs of different measuring ranges overlap.

[0054] S3-2: Draw a circle based on the measuring range 4 of the small pitch gauge: The center 2 of the small pitch gauge is set on the center line of the large pitch gauge. Draw a reference axis with the center 2 of the small pitch gauge as the reference. Move the measuring range 4 of the small pitch gauge along the center line to draw a circle so that the circle completely covers the orthographic projection contour of the damaged area. Ensure that all measuring points 6 are within the measuring radius of the small pitch gauge.

[0055] The center point 2 of the small pitch gauge can also be set on the radial lines of 2.5°, 7.5°, 12.5°, etc. of the large pitch gauge, so that all measuring points with an interval of 5° are symmetrical, eliminating the work of repeatedly calculating the coordinates of the symmetrical points. The small pitch gauge range 4 is moved along the radial line to draw a circle, and the drawn circle completely covers the orthographic projection contour map of the damaged area, ensuring that all measuring points 6 are within the measuring radius range of the small pitch gauge.

[0056] S4: Coordinate conversion: The coordinates of measuring point 6 are all cylindrical coordinates, which include radius, angle and height. The coordinates of measuring point 6 in the large pitch gauge coordinate system are converted to the small pitch gauge coordinate system. During the conversion, the base axis of the coordinate system is translated, and the height value does not change. The radius and angle of each measuring point 6 are changed, that is, the original radius and angle of each measuring point need to be re-measured and determined on the orthographic projection contour drawing. According to the conversion formula, the coordinates of each measuring point 6 in the small pitch gauge coordinate system after conversion are calculated.

[0057] The radius of the large pitch gauge is set to R, the coordinates of the measuring point on the large pitch gauge are (R, α, H), and the coordinates of the measuring point on the small pitch gauge coordinate system after conversion are (r, α x ,h), according to the cosine theorem and trigonometric function formula, the conversion formula is as follows:

[0058]

[0059]

[0060] h=H

[0061] Where R is the radius of the measuring point on the large pitch gauge coordinate system section, α is the angle of the measuring point relative to the center of the large pitch gauge, H is the height of the measuring point in the large pitch gauge coordinate system, R x is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r is the radius of the measuring point in the small pitch gauge coordinate system, α x is the angle of the measuring point relative to the center of the small pitch gauge, and h is the height of the measuring point in the small pitch gauge coordinate system.

[0062] Taking the 0.9R section as an example, three measuring points A, B, and C are selected on the 0.9R section. The coordinate of point A on the large pitch gauge coordinate system is (R 0.9 , 0°, H1), that is, when α=0°, the coordinates in the small pitch gauge coordinate system after conversion are (r1, α1, h1). The conversion process obtained by substituting it into the conversion formula is as follows:

[0063] r1=|R 0.9 -R0|

[0064] α1=0°

[0065] h1=H1

[0066] Among them, R 0.9is the radius of point A on the 0.9R section of the large pitch gauge coordinate system, 0° is the angle of point A relative to the center of the large pitch gauge, H1 is the height of point A in the large pitch gauge coordinate system, R0 is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r1 is the radius of point A in the small pitch gauge coordinate system, α1 is the angle of point A relative to the center of the small pitch gauge, and h1 is the height of point A in the small pitch gauge coordinate system;

[0067] The coordinates of point B in the large pitch gauge coordinate system are (R 0.9 , 5°, H2), that is, when α=5°, the coordinates in the small pitch gauge coordinate system after conversion are (r2, α2, h2). Substituting it into the conversion formula, the conversion process is as follows:

[0068]

[0069]

[0070] h2=H2

[0071] Among them, R 0.9 is the radius of point B on the 0.9R section of the large pitch gauge coordinate system, 5° is the angle of point B relative to the center of the large pitch gauge, H2 is the height of point B in the large pitch gauge coordinate system, r2 is the radius of point B in the small pitch gauge coordinate system, α2 is the angle of point B relative to the center of the small pitch gauge, and h2 is the height of point B in the small pitch gauge coordinate system;

[0072] The coordinates of point C on the large pitch gauge coordinate system are set as (R 0.9 , 10°, H3), that is, when α=10°, the coordinates in the small pitch gauge coordinate system after conversion are (r3, α3, h3). The conversion process obtained by substituting it into the conversion formula is as follows:

[0073]

[0074]

[0075] h3=H3

[0076] Among them, R 0.9 is the radius of point C on the 0.9R section of the large pitch gauge coordinate system, 10° is the angle of point C relative to the center of the large pitch gauge, H3 is the height of point C in the large pitch gauge coordinate system, r3 is the radius of point C in the small pitch gauge coordinate system, α3 is the angle of point C relative to the center of the small pitch gauge, and h3 is the height of point C in the small and large pitch gauge coordinate systems.

[0077] S5: Casting the damaged blade part, including the following steps:

[0078] S5-1: According to the coordinates of each measuring point 6 in the small pitch gauge coordinate system after conversion in S4, measure each measuring point 6 on the sand mold, use the points to draw lines, use the lines to draw surfaces, and use a trowel to make the pressure surface;

[0079] S5-2: Use section plates to create a false leaf shape in the damaged area;

[0080] S5-3: Apply mold release agent to the entire suction surface of the false blade, put it into the box, clean the false blade after unpacking, and obtain the shape of the damaged blade after closing the box.

[0081] The present invention first determines the position of the damaged blade tip area in the large pitch gauge coordinate system, and draws the outline of the damaged blade tip area after adding the margin on the mapping software, and draws a circle to cover the entire damaged blade tip outline area according to the measuring range of the small pitch gauge, and converts the coordinates of the measuring point in the large pitch gauge coordinate system into the coordinates in the small pitch gauge coordinate system, and then measures the converted coordinates on the sand mold to perform casting molding of the damaged blade. The partial blade prepared by this method can accurately measure the sand mold of the damaged blade and shape it without occupying a large workstation and a large digital pitch gauge, thereby improving the blade repair efficiency and reducing the production cost; when the product order volume increases sharply and the large workstation and large crane are insufficient, the large fixed-pitch propeller blade is molded in sections, and each section is molded using small tooling tools such as a low-cost and convenient small pitch gauge without occupying a large molding workstation and a large crane, and then assembled and matched on a large workstation, which can greatly improve the construction efficiency and shorten the construction period.

[0082] The present invention is described by way of example, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments may be modified to suit specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be within the scope of the present invention.

Claims

1. A casting method for partial blades of a large propeller, characterized in that: The following steps are involved: S1: Determine the damaged area of ​​the propeller blade; S2: Determine the position of the damaged area in the large pitch gauge coordinate system; S3: Determine the origin of the small pitch gauge coordinate system, including the following steps: S3-1: Draw the orthographic projection contour map (5) of the damaged area of ​​the propeller blade, the center of the large pitch gauge (1), the reference axis, the center line, and arcs of different ranges on the mapping software, and select multiple measurement points (6) where the orthographic projection contour map and the arcs of different ranges overlap; S3-2: Draw a circle based on the range of the small pitch gauge: The center of the small pitch gauge (2) is set on the center line of the large pitch gauge, and the small pitch gauge range (4) is moved along the center line to draw a circle. The circle drawn completely covers the orthographic projection contour of the damaged area, ensuring that all measuring points (6) are within the measuring radius of the small pitch gauge; S4: Coordinate conversion: The coordinates of the measuring point (6) are all cylindrical coordinates, which include radius, angle and height. The coordinates of the measuring point (6) in the large pitch gauge coordinate system are converted to the small pitch gauge coordinate system. During the conversion, the reference axis of the coordinate system is translated, and the height value does not change. The radius and angle of each measuring point (6) are changed. According to the conversion formula, the coordinates of each measuring point (6) in the small pitch gauge coordinate system after the conversion are calculated; S5: Casting the damaged blade part, including the following steps: S5-1: According to the coordinates of each measuring point (6) in the small pitch gauge coordinate system after conversion in S4, each measuring point (6) is measured on the sand mold, and the pressure surface is made by using the points to lead the lines and the lines to lead the surfaces; S5-2: Use section plates to create a false leaf shape in the damaged area; S5-3: Apply mold release agent to the entire suction surface of the false blade, put it into the box, clean the false blade after unpacking, and obtain the shape of the damaged blade after closing the box.

2. The casting method for a partial blade of a large propeller according to claim 1, characterized in that: In S1, the damaged area of ​​the propeller blade is located at the tip of the propeller blade, curling toward the inside of the blade and having a large number of microcracks on it.

3. The casting method for a partial blade of a large propeller according to claim 1, characterized in that: The S2 includes the following steps: S2-1: Measure the outer dimensions of the damaged area; S2-2: Prepare the propeller blade orthographic outline drawing according to the propeller blade drawing and make a 1:1 sample; S2-3: Compare and analyze the measured outer contour dimensions of the damaged area with the prepared blade orthographic projection contour map to determine the position of the damaged area in the large pitch gauge coordinate system.

4. The casting method for partial blades of a large propeller according to claim 1, characterized in that: In the above S3-2, a margin of 10-20 mm is added along the cutting line at the edge of the orthographic projection contour.

5. The casting method for partial blades of a large propeller according to claim 1, characterized in that: In the above S4, the radius of the large pitch gauge is set to R, the coordinates of the measuring point on the large pitch gauge are (R, α, H), and the coordinates of the measuring point on the small pitch gauge coordinate system after conversion are (r, α x , h), according to the cosine theorem and trigonometric function formula, the conversion formula is as follows: h=H Where R is the radius of the measuring point on the large pitch gauge coordinate system section, α is the angle of the measuring point relative to the center of the large pitch gauge, H is the height of the measuring point in the large pitch gauge coordinate system, R x is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r is the radius of the measuring point in the small pitch gauge coordinate system, α x is the angle of the measuring point relative to the center of the small pitch gauge, and h is the height of the measuring point in the small pitch gauge coordinate system.

6. The casting method for partial blades of a large propeller according to claim 5, characterized in that: Select three measuring points A, B, and C on the 0.9R section. The coordinate of point A on the large pitch gauge coordinate system is (R 0.9 , 0°, H1), that is, α=0°. After conversion, the coordinates in the small pitch gauge coordinate system are (r1, α1, h1). The conversion process is as follows: r1=|R 0.9 -R0| α1＝0° h1=H1 Among them, R 0.9 is the radius of point A on the 0.9R section of the large pitch gauge coordinate system, 0° is the angle of point A relative to the center of the large pitch gauge, H1 is the height of point A in the large pitch gauge coordinate system, R0 is the radius of the center of the small pitch gauge in the large pitch gauge coordinate system, r1 is the radius of point A in the small pitch gauge coordinate system, α1 is the angle of point A relative to the center of the small pitch gauge, and h1 is the height of point A in the small pitch gauge coordinate system; The coordinates of point B in the large pitch gauge coordinate system are (R 0.9 , 5°, H2), that is, α=5°. After conversion, the coordinates in the small pitch gauge coordinate system are (r2, α2, h2). The conversion process is as follows: h2=H2 Among them, R 0.9 is the radius of point B on the 0.9R section of the large pitch gauge coordinate system, 5° is the angle of point B relative to the center of the large pitch gauge, H2 is the height of point B in the large pitch gauge coordinate system, r2 is the radius of point B in the small pitch gauge coordinate system, α2 is the angle of point B relative to the center of the small pitch gauge, and h2 is the height of point B in the small pitch gauge coordinate system; The coordinates of point C on the large pitch gauge coordinate system are set as (R 0.9 , 10°, H3), that is, α=10°. After conversion, the coordinates in the small pitch gauge coordinate system are (r3, α3, h3). The conversion process is as follows: h3=H3 Among them, R 0.9 Point C in the large pitch gauge coordinate system The radius on the 0.9R section, 10° is the angle of point C relative to the center of the large pitch gauge, H3 is the height of point C in the large pitch gauge coordinate system, r3 is the radius of point C in the small pitch gauge coordinate system, α3 is the angle of point C relative to the center of the small pitch gauge, and h3 is the height of point C in the small and large pitch gauge coordinate systems.

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