Automatic manufacturing method of section sample plate for ship propeller blade modeling

Abstract

The invention relates to the technical field of propeller manufacturing, in particular to an automatic manufacturing method of a section sample plate for ship propeller blade modeling. Comprising the steps of obtaining parameters and radial parameters, unifying paddle section profile values, adding casting allowance, adding a reduced scale, obtaining profile value points of a smooth section sample plate, obtaining coordinates of a chord line and a mark point, manufacturing a three-dimensional model through UG, and machining. Compared with the prior art, the method has the beneficial effects that the shape of the section sample plate can be more accurate by adding the casting allowance at the normal position of the blade section contour line; according to the method, the position of the value point added with the reduced scale is fitted by adopting a cubic B-spline interpolation method, the smooth coordinates of the value point of the section sample plate are obtained, the problem of process errors caused by errors of the reduced scale and allowance calculation is avoided, the added casting allowance contour line is smoother, manual fairing is not needed, and the working efficiency of machining is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of propeller manufacturing, and in particular to an automated manufacturing method for a cross-section template for shaping a marine propeller blade. Background Art

[0002] Marine propeller blades with complex shapes are usually manufactured using sand casting methods. The key to whether the size of the molded blank casting meets the requirements lies in the production of the propeller blade cross-section template. Usually, the propeller blade cross-section template is made by manual hand-drawing. The wood sample maker marks the position of each data point according to the horizontal and vertical data point coordinates given in the design drawing to obtain a 1:1 propeller blade cross-section template scattered point outline, and then combines the scale and allowance of the casting process design to determine the position of each data point on the blade blank cross-section through calculation. Finally, with the help of a bending ruler, the scattered data points on the blade blank cross-section are connected one by one to obtain the blade blank cross-section template drawing for the casting modeling of the blade blank. Due to technical limitations, in this traditional method of making cross-section templates of propeller blade shapes, the casting allowance of the cross-section template is applied in the axial direction, which deviates from the actual position where the allowance should be applied. In actual operation, it takes up a lot of time for the wood sample makers. Moreover, when there is a deviation between the manually drawn wood sample and the theoretical value of the casting process, in order to ensure the integrity of the blade, the blade shape needs to be manually smoothed, which is very easy to make mistakes, resulting in a very low degree of consistency between the actual cross-section template shape and the theoretical design shape. Summary of the invention

[0003] In order to overcome the technical problems in the prior art of low efficiency in drawing drawings and deviations in theoretical numerical values ​​of the obtained casting process, the present invention provides an automated method for making cross-section templates for shaping marine propeller blades.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: an automated production method for a cross-section template for marine propeller blade shaping, comprising the following steps:

[0005] S1: Obtain the main parameters of the blade designed by the propeller drawing, the propeller section radius, the radial parameters of the propeller section radius coaxially, the blade section value and the casting allowance;

[0006] S2: The propeller section radius, the section chord-wise shape value point position, the radial parameters, and the blade section shape value are fitted by cubic B-spline interpolation, and the radial parameters and blade section shape value at the same section radius and the same section chord-wise shape value point are obtained by the fitted curve;

[0007] S3: Obtaining the blade cross-sectional contour line at each cross-sectional radius, adding casting allowances in the normal direction of the blade cross-sectional shape value points at each cross-sectional radius, and obtaining the blade cross-sectional shape value point coordinates after the allowances are added;

[0008] S4: adding a scale value to the coordinates of the blade cross-section value point after adding the casting allowance, and obtaining the position of the value point after adding the scale;

[0009] S5: Add the scaled type value point positions through cubic B-spline difference fitting to obtain the type value point coordinates of the smooth cross-section sample;

[0010] S6: Obtain the position of the chord in the coordinates of the smoothed section template value points at each section radius, and obtain the coordinates of the marking points, including the point on the chord at 0%, the point at 25%, the point at 75%, the point at 100%, the point at the maximum thickness, and perform a pitch angle rotation on the chord obtained in S6, and the intersection of the rotated chord with the suction surface and the pressure surface;

[0011] S7: Output the coordinates of the smoothed section template value points under each section radius;

[0012] S8: Output the coordinates of the marking points at each section radius;

[0013] S9: Input the coordinates of the smoothed cross-section template value points under each cross-section radius and the coordinates of the marking points at each cross-section radius into the UG software, draw the contour line of the cross-section template, and mark the positions of the chord line and the marking points;

[0014] S10: UG software outputs a 3D model that can be directly used by CNC machine tools;

[0015] S11: Mill the section template using a CNC milling machine.

[0016] Preferably, the main parameters include propeller diameter, cross-sectional value arrangement direction, global scale, and suction surface measurement reference.

[0017] Preferably, the radial parameters include pitch, longitudinal inclination, maximum thickness, chord length, center guide distance, and distance from the maximum thickness position to the guide edge.

[0018] Preferably, the pitch angle rotation is calculated by a two-dimensional matrix, and the expression of the two-dimensional matrix is:

[0019]

[0020] Where θ is the pitch angle.

[0021] Preferably, after marking the positions of the chord lines and the marking points in step S9, the contour lines of the cross-sectional templates at each radius are flattened in a unified plane, and the thickness of the cross-sectional template model to be processed is adjusted according to the number of cross-sectional templates processed simultaneously at a single time.

[0022] Compared with the prior art, the beneficial effect of the present invention lies in that, by adding casting allowance at the normal position of the blade cross-section contour line, the shape of the cross-section template can be made more accurate; by fitting the mold value point positions after adding the scale by using the cubic B-spline interpolation method, the mold value point coordinates of the smooth cross-section template are obtained, thereby avoiding the problem of process errors caused by errors in scaling and allowance calculation, and the added casting allowance contour line is smoother, without the need for manual smoothing, thereby greatly improving the processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the method of the present invention.

[0024] Figure 2 It is a schematic cross-sectional view of a blade of the present invention.

[0025] In the figure: 1: blade cross-section contour line; 2: chord line; 3: maximum position; 4: 0% point in the chord direction; 5: 25% point in the chord direction; 6: 75% point in the chord direction; 7: 100% point in the chord direction; 8; normal direction. DETAILED DESCRIPTION

[0026] The present invention provides an automated manufacturing method for a cross-section template for marine propeller blade shaping, and the specific implementation method is as follows Figure 1 to Figure 2 As shown, including:

[0027] S1: Obtain the main parameters of the propeller blade designed in the propeller drawing, the propeller section radius, the radial parameters coaxial with the propeller section radius direction, the blade section type value and the casting allowance. The main parameters include the propeller diameter, the section type value arrangement direction, the global scale, and the suction surface measurement reference. The radial parameters include the pitch, the longitudinal inclination, the maximum thickness, the chord length, the mid-guide distance, and the distance from the maximum thickness position to the guide edge;

[0028] S2: The propeller section radius, the section chord-wise shape value point position, the radial parameters, and the blade section shape value are fitted by cubic B-spline interpolation, and the radial parameters and blade section shape value at the same section radius and the same section chord-wise shape value point are obtained by the fitted curve;

[0029] S3: obtaining a blade cross-sectional contour line 1 at each cross-sectional radius, adding a casting allowance to the normal 8 of the blade cross-sectional value point at each cross-sectional radius, and obtaining the coordinates of the blade cross-sectional value point after the allowance is added;

[0030] S4: adding a scale value to the coordinates of the blade cross-section value point after adding the casting allowance, and obtaining the position of the value point after adding the scale;

[0031] S5: Add the scaled type value point positions through cubic B-spline difference fitting to obtain the type value point coordinates of the smooth cross-section sample;

[0032] S6: The position of chord 2 is obtained in the coordinates of the smooth section template value points under each section radius, and the coordinates of the marking points are obtained, the marking points include point 4 at 0% of the chord direction, point 5 at 25% of the chord direction, point 6 at 75% of the chord direction, point 7 at 100% of the chord direction, point 3 at the maximum thickness, and the chord obtained in S6 is rotated by a pitch angle, and the intersection of the rotated chord with the suction surface and the pressure surface; the pitch angle rotation is calculated by a two-dimensional matrix, and the expression of the two-dimensional matrix is:

[0033]

[0034] Where θ is the pitch angle;

[0035] S7: Output the coordinates of the smoothed section template value points under each section radius;

[0036] S8: Output the coordinates of the marking points at each section radius;

[0037] S9: Input the coordinates of the smoothed cross-section template value points under each cross-section radius and the coordinates of the marking points at each cross-section radius into the UG software, draw the contour line of the cross-section template, mark the positions of the chord line 2 and the marking points, lay the contour lines of the cross-section templates at each radius flat on a unified plane, and adjust the thickness of the cross-section template model to be processed according to the number of cross-section templates processed simultaneously at a single time;

[0038] S10: UG software outputs a 3D model that can be directly used by CNC machine tools;

[0039] S11: Mill the section template using a CNC milling machine.

[0040] The present invention is described by way of embodiments, 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. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to 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 belong to the protection scope of the present invention.

Claims

1. An automated method for producing a cross-section template for marine propeller blade shaping, characterized in that: The following steps are involved: S1: Obtain the main parameters of the blade designed by the propeller drawing, the propeller section radius, the radial parameters of the propeller section radius coaxially, the blade section value and the casting allowance; S2: The propeller section radius, the section chord-wise shape value point position, the radial parameters, and the blade section shape value are fitted by cubic B-spline interpolation, and the radial parameters and blade section shape value at the same section radius and the same section chord-wise shape value point are obtained by the fitted curve; S3: Obtaining the blade cross-sectional contour line (1) at each cross-sectional radius, adding casting allowances on the normal (8) of the blade cross-sectional value points at each cross-sectional radius, and obtaining the blade cross-sectional value point coordinates after adding the allowances; S4: adding a scale value to the coordinates of the blade cross-section value point after adding the casting allowance, and obtaining the position of the value point after adding the scale; S5: Add the scaled type value point positions through cubic B-spline difference fitting to obtain the type value point coordinates of the smooth cross-section sample; S6: Obtain the position of the chord (2) in the coordinates of the smooth cross-section template value points at each cross-section radius, and obtain the coordinates of the marking points, the marking points including the 0% point (4) in the chord direction, the 25% point (5) in the chord direction, the 75% point (6) in the chord direction, the 100% point (7) in the chord direction, the point at the maximum thickness (3), and perform a pitch angle rotation on the chord obtained in S6, and the intersection of the rotated chord with the suction surface and the pressure surface; S7: Output the coordinates of the smoothed section template value points under each section radius; S8: Output the coordinates of the marking points at each section radius; S9: Input the coordinates of the smoothed cross-section sample value points at each cross-section radius and the coordinates of the marking points at each cross-section radius into the UG software, draw the contour line of the cross-section sample, and mark the positions of the chord line (2) and the marking points; S10: UG software outputs a 3D model that can be directly used by CNC machine tools; S11: Mill the section template using a CNC milling machine.

2. The method for automatically making a cross-section template for marine propeller blade shaping according to claim 1, characterized in that: The main parameters include propeller diameter, section value arrangement direction, global scale, and suction surface measurement reference.

3. The method for automatically making a cross-section template for marine propeller blade shaping according to claim 1, characterized in that: The radial parameters include pitch, longitudinal inclination, maximum thickness, chord length, center guide distance, and distance from the maximum thickness position to the guide edge.

4. The method for automatically making a cross-section template for marine propeller blade shaping according to claim 1, characterized in that: The pitch angle rotation is calculated by a two-dimensional matrix, and the expression of the two-dimensional matrix is: Where θ is the pitch angle.

5. The method for automatically making a cross-section template for marine propeller blade shaping according to claim 1, characterized in that: After marking the positions of the chord lines and the marking points in step S9, the contour lines of the cross-section templates at each radius are laid flat in a unified plane, and the thickness of the cross-section template model to be processed is adjusted according to the number of cross-section templates processed simultaneously at a single time.

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