A magnetic nail fixing arrangement method for free edge double side polishing of a ship body part

Abstract

The application provides a magnetic nail fixing arrangement method for free edge double-sided polishing of a ship body part, comprising the following steps: generating an initial layout scheme of an electromagnetic chuck full of magnetic nails according to electromagnetic chuck and magnetic nail data; calculating a minimum envelope rectangle of the part according to size information of the part, and moving the part to the center of the electromagnetic chuck with the minimum envelope rectangle center as a reference point; generating polishing tracks and tool movement areas of a tool according to polishing information of the part, and determining interfering magnetic nails in the tool movement areas; determining a position and an angle with the least interfering magnetic nails according to initial attitude information of the part, generating a remaining magnetic nail arrangement scheme, and obtaining a final magnetic nail arrangement scheme; and removing magnetic nails that do not play a supporting and fixing role on the part in the final magnetic nail arrangement scheme, and outputting a final magnetic nail arrangement scheme that meets polishing requirements of the part. The magnetic nail arrangement scheme of all parts is generated through the above method, and one-time polishing of the part is completed without turning over.

Description

Technical Field

[0001] This application relates to the field of bilateral grinding technology for free edges of ship hull parts, specifically, to a method for fixing magnetic nails for bilateral grinding of free edges of ship hull parts. Background Technology

[0002] Chamfering of ship parts is an essential process throughout the entire ship assembly production and construction process, and is a crucial foundation for ensuring the coating requirements of the parts. According to the relevant requirements of the Performance Standard of Protective Coatings (PSPC), the free edges of ballast tank hull parts cut from ship products must be chamfered to at least R2 radius rounded corners or undergo equivalent treatment before coating. R2 grinding is a grinding process that requires polishing and treating the edges of the steel plate surface to a radius of 2mm to achieve a certain degree of smoothness and flatness, avoiding burrs, protrusions, or other irregularities on the surface.

[0003] Traditionally, the free edges of ship assembly parts are processed by workers using hand-held grinding wheels, repeating the same path three times. Currently, some shipyards in China are using pneumatic milling cutters instead of grinding wheels to round the free edges of ship parts. This requires only one milling operation, increasing speed by three times and reducing dust pollution compared to using grinding wheels. However, after processing the free edges, the components need to be flipped. Flipping the parts requires the use of gantry cranes, which is time-consuming and labor-intensive, affecting work efficiency, increasing costs, and having a significant impact on worker health and the environment.

[0004] To address this, a magnetic nail layout suitable for most parts was developed, enabling simultaneous grinding of the top and bottom free edges of typical parts without flipping them over. Furthermore, a double-headed blade was used for grinding, allowing the machining center to complete the grinding in a single feed, greatly improving grinding efficiency and achieving the precision and requirements that manual grinding cannot reach. This has significant practical implications for improving the quality of hull parts and the efficiency of ship assembly and manufacturing.

[0005] In existing technologies, shipyards use manual grinding, which is inefficient, produces poor quality, and parts are fixed manually. Some shipyards use lifting support columns, which require adjusting the height of the support columns by algorithm or manual means when a part arrives. In addition, lifting support columns are expensive. Grinding one side of the part, flipping it over, and then grinding the other side increases the number of machines or workers needed to flip the parts. Furthermore, the flipping process may cause deviations in the position of the parts. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this application is to provide a magnetic nail fixing arrangement method for double-sided grinding of free edges of ship hull parts. This method can generate magnetic nail arrangement schemes suitable for grinding most parts of different shapes. By performing simultaneous grinding on both sides and fixing the parts with magnetic attraction to prevent them from moving, it overcomes the problems of existing technologies where manual fixing or support column fixing methods are difficult to guarantee grinding quality and parts need to be flipped over to achieve double-sided grinding.

[0007] One aspect of this application provides a method for fixing magnetic nails on both sides of the free edge of a hull part by grinding, comprising:

[0008] Based on the data of the electromagnetic chuck and magnetic nails, an initial layout scheme is generated in which the electromagnetic chuck is filled with the magnetic nails;

[0009] Based on the size information of the parts, calculate the minimum envelope rectangle of the parts, and move all the parts to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point;

[0010] Based on the grinding information of the part, the grinding trajectory of the tool and the tool movement area are generated, and the interference magnetic nails in the tool movement area are determined.

[0011] Based on the initial attitude information of the parts, determine the position and angle of the interference magnetic nails with the minimum, generate the remaining magnetic nail arrangement scheme, and obtain the final magnetic nail arrangement scheme;

[0012] Based on the obtained final magnetic nail arrangement scheme, remove the magnetic nails that do not provide support and fixation for the part, and output the final magnetic nail arrangement scheme that meets the grinding requirements of the part.

[0013] Further, the step of calculating the minimum envelope rectangle of the parts based on their size information, and moving all the parts to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point, includes:

[0014] Obtain the dimensional information of all parts, including the dimensional information of each side of the part;

[0015] The edges of the part include welded edges and free edges;

[0016] Based on the free edges of the part, find the maximum and minimum values ​​of the coordinates of the free edges of the part in the horizontal and vertical directions, and generate the boundary of the rectangle to obtain the minimum envelope rectangle of the part.

[0017] Calculate the coordinates of the center point of the minimum envelope rectangle based on the minimum envelope rectangle of the part;

[0018] Based on the coordinates of the center point, calculate the distance that the part needs to move to the center of the electromagnetic chuck, including the lateral movement distance and the longitudinal movement distance;

[0019] Move the part to the center of the electromagnetic chuck.

[0020] Further, the step of generating the grinding trajectory and tool movement area of ​​the tool based on the grinding information of the part, and determining the interference magnetic nails within the tool movement area, includes:

[0021] Obtain the free edge information, tool diameter, and tool offset of the part; the free edge information includes straight edges and arc edges;

[0022] Determine whether the arc edge of the part has a concave arc segment with a radius smaller than the offset of the tool. If so, determine that the concave arc segment does not need to be ground; otherwise, determine that the concave arc segment needs to be ground.

[0023] The concave arc segment is replaced with a straight line to obtain the free edge information of the part after the initial processing;

[0024] Based on the processed free edge information of the part and the offset of the tool, the free edge of the part is offset outward by the offset distance of the tool to generate a new free edge segment;

[0025] Based on the new free edge segment, determine whether the new free edge segment is connected. If so, generate a continuous tool movement trajectory for the part.

[0026] Based on the tool movement trajectory, the feed and retraction amounts of the tool are added at the start and end points of the tool movement trajectory to generate the final tool movement trajectory of the part.

[0027] Based on the final tool movement trajectory of the part, the interference magnetic nails within the tool movement trajectory are determined.

[0028] Further, the step of offsetting the free edge of the part outward by the offset distance of the tool center based on the processed free edge information of the part and the offset of the tool center to generate a new free edge segment includes:

[0029] Obtain the free edge information of the processed part and the offset of the tool center, and offset the free edge of the part outward;

[0030] The straight edge is obtained by calculating its normal vector to get the offset line segment, and the arc edge is obtained by calculating the vector of the line connecting the starting point and the ending point to the center of the circle to get the offset arc segment. After all the free edges are offset outward, a new set of free edge segments is obtained.

[0031] Furthermore, based on the new free edge segment, it is determined whether the new free edge segment is connected. If not, the unconnected segment is transitioned by an arc with the offset of the tool as the radius, thereby generating a continuous tool movement trajectory for the part.

[0032] Further, the step of determining the position and angle of the minimum interference magnetic nails based on the initial attitude information of the part, generating the remaining magnetic nail arrangement scheme, and obtaining the final magnetic nail arrangement scheme includes:

[0033] Obtain the initial posture information of the part and the final tool movement trajectory of the part, and calculate the position and number of interference magnetic nails in the initial state;

[0034] Based on the movement range and step size, rotation angle range and step size of the part on the electromagnetic chuck, generate all postures of the part;

[0035] Based on all the orientations of the parts, calculate the position and number of interference magnetic nails under different orientations;

[0036] Based on the positions and numbers of the interference magnetic nails under different postures, and by comparison, the position and angle with the fewest interference magnetic nails are determined as the optimal posture, generating the remaining magnetic nail arrangement scheme, and obtaining the final magnetic nail arrangement scheme.

[0037] Furthermore, the step of calculating the position and number of interference magnetic nails under different orientations based on all orientations of the component includes:

[0038] Obtain the current posture of the part, determine whether the part exceeds the electromagnetic chuck in the current posture, if so, skip the current posture and continue to move and rotate the part to the next posture, if not, calculate the position and number of interference magnetic nails in the current posture.

[0039] Further, based on the positions and numbers of the interference magnetic nails under different attitudes, and through comparison, the optimal attitude is determined by the position and angle with the fewest interference magnetic nails. This process generates the remaining magnetic nail arrangement scheme and yields the final magnetic nail arrangement scheme, including:

[0040] Obtain the position and number of the interference magnetic nails in the current posture and the position and number of the interference magnetic nails in the previous posture;

[0041] The positions and numbers of the interference magnetic nails in the current posture are compared with those in the previous posture. If the number of interference magnetic nails in the previous posture is less than the number of interference magnetic nails in the current posture, then the previous posture is retained as the optimal posture.

[0042] If the number of interference magnetic nails in the previous posture is greater than the number of interference magnetic nails in the current posture, then the current posture is updated to the optimal posture.

[0043] If the number of interference magnetic nails in the previous posture is equal to the number of interference magnetic nails in the current posture, then calculate the number of magnetic nails surrounded or contacted by the part contour in the current posture and the previous posture, and take the posture with the larger number as the optimal posture.

[0044] Furthermore, after determining the optimal pose, the process also includes:

[0045] Determine whether all poses have been traversed. If yes, the process ends and the remaining magnetic nail placement scheme is generated. If not, continue traversing the remaining poses.

[0046] The remaining magnetic nail arrangement scheme is output as the final magnetic nail arrangement scheme.

[0047] Further, the step of removing magnetic nails that do not provide support and fixation for the part from the obtained final magnetic nail arrangement scheme, and outputting a final magnetic nail arrangement scheme that meets the grinding requirements of the part, includes:

[0048] Obtain the optimal magnetic nail placement scheme under the optimal orientation of all parts;

[0049] Based on the optimal magnetic nail layout scheme of all the parts, determine whether each magnetic nail is completely outside of all the parts. If so, remove the magnetic nail from the magnetic nail layout scheme; otherwise, retain it.

[0050] Determine whether to evaluate all magnetic nails. If not, continue evaluating. If yes, output the final magnetic nail arrangement scheme that meets the part grinding requirements.

[0051] Compared with the prior art, this application has at least one of the following beneficial effects:

[0052] 1. This application adopts a magnetic nail support scheme, which can fix the workpiece by adjusting the magnetic attraction of the magnetic nail, ensuring that the part does not move or vibrate during grinding. This solves the problem that the traditional manual fixing method or multi-point support method with support columns may cause the part to move due to excessive cutting force during grinding, thus affecting the grinding quality.

[0053] 2. By arranging magnetic nails on a disk, this application can design a magnetic nail arrangement scheme that is suitable for the dual-sided grinding requirements of most parts according to different shapes. It has high adaptability and solves the problem that the traditional method of fixing with a whole electromagnetic chuck can only grind one side. If the other side needs to be ground, the part needs to be flipped, which increases the working time and affects the grinding quality. Attached Figure Description

[0054] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0055] Figure 1 This is a flowchart of a magnetic nail fixing arrangement method for double-sided grinding of the free edge of a ship hull part according to an embodiment of this application.

[0056] Figure 2 This is a flowchart illustrating the tool trajectory during the grinding of the free edge of a part in one embodiment of this application.

[0057] Figure 3 This is a flowchart illustrating the process of finding the optimal orientation for placing parts in one embodiment of this application.

[0058] Figure 4 This is a flowchart illustrating the process of generating the final magnetic nail layout after traversing and searching all parts in one embodiment of this application.

[0059] Figure 5 This is a schematic diagram of parts of different shapes used in one embodiment of this application.

[0060] Figure 6 This is an initial magnetic nail layout diagram generated in one embodiment of this application.

[0061] Figure 7 This is a schematic diagram of the movement trajectory of the cutting tool during the grinding of a part in one embodiment of this application.

[0062] Figure 8 This is a schematic diagram of a component in an initial posture with the interference magnetic nail removed, according to one embodiment of this application.

[0063] Figure 9 This is a diagram illustrating the process of each component sequentially searching for the least interfering magnetic nail in one embodiment of this application.

[0064] Figure 10 This is a final magnetic nail layout diagram generated after deleting parts that do not serve to fix the parts, according to one embodiment of this application.

[0065] Figure 11 This is a schematic diagram showing the calculated placement of parts under the final magnetic nail layout diagram in one embodiment of this application. Detailed Implementation

[0066] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application. These all fall within the protection scope of the present application.

[0067] Reference Figure 1 As shown, this embodiment of the present application illustrates a method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part, comprising:

[0068] S1. Based on the data of the electromagnetic chuck and magnetic nails, generate an initial layout scheme in which the electromagnetic chuck is filled with magnetic nails.

[0069] S2. Based on the part's size information, calculate the minimum envelope rectangle of the part, and move all parts to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point.

[0070] S3. Based on the grinding information of the part, generate the grinding trajectory of the tool and the tool movement area, and determine the interference magnetic nails in the tool movement area.

[0071] S4. Based on the initial attitude information of the parts, determine the position and angle of the magnetic nails with the least interference, generate the remaining magnetic nail arrangement scheme, and obtain the final magnetic nail arrangement scheme.

[0072] S5. Based on the final magnetic nail arrangement scheme obtained, remove the magnetic nails that do not provide support and fixation for the parts, and output the final magnetic nail arrangement scheme that meets the grinding requirements of the parts.

[0073] This application, through the above process, can generate a magnetic nail arrangement scheme suitable for grinding most of the parts according to different shapes. It can perform simultaneous grinding on both sides through double-headed blade feed, and the magnetic nails fix the parts with magnetic attraction to prevent the parts from moving. This overcomes the problems of existing technologies where manual fixing of parts or fixing by support columns is difficult to guarantee grinding quality and parts need to be flipped to achieve double-sided grinding.

[0074] Specifically, firstly, an initial layout scheme is generated based on the parameters of the electromagnetic chuck and magnetic nails. Then, the center of the part is aligned with the center of the electromagnetic chuck based on the part's dimensions, facilitating subsequent adjustments to the part's position and angle to find the optimal magnetic nail layout. Next, based on the part's free edge, tool diameter, and reserved buffer space, a grinding trajectory and tool movement area are generated, and potentially interfering magnetic nails are identified. Then, by adjusting the part's initial orientation, the position and angle of the magnetic nails with minimal interference are determined, generating the final magnetic nail arrangement scheme. Finally, unnecessary magnetic nails are removed, resulting in a final magnetic nail arrangement scheme that satisfies the part's grinding requirements while being economical and efficient.

[0075] In some possible embodiments, the minimum envelope rectangle of the parts is calculated based on the size information of the parts, and all parts are moved to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point. This includes: obtaining the size information of all parts, which includes the information of each side of the parts; wherein the sides of the parts include welded edges and free edges.

[0076] Based on the free edges of the part, find the maximum and minimum values ​​of the coordinates of the free edges in the horizontal and vertical directions, and generate the boundary of the rectangle to obtain the minimum envelope rectangle of the part; based on the minimum envelope rectangle of the part, calculate the coordinates of the center point of the minimum envelope rectangle; based on the center point coordinates, calculate the distance that the part needs to be moved to the center of the electromagnetic chuck, including the horizontal and vertical movement distances; move the part to the center of the electromagnetic chuck.

[0077] The hull parts include welded edges and free edges, with free edges being the edges that are not welded. Free edges include two types: straight edges and curved edges. Straight edges include the coordinates of the starting point and ending point, as well as the dimension information of the edge length. Curved edges additionally include the dimension information such as the center of the arc and the radius of the arc.

[0078] Specifically, during operation, firstly, based on the information of each edge of the part (including straight edges and curved edges), the system finds the maximum and minimum values ​​of the coordinates of all edges in the horizontal and vertical directions. Using these four maximum and minimum values ​​as the boundaries of a rectangle, it obtains the minimum envelope rectangle of the part. Then, it calculates the coordinates of the center point of this minimum envelope rectangle. Next, it calculates the distance the part needs to be moved to the center of the disk, including both horizontal and vertical movement. Finally, it moves the part to the center of the disk.

[0079] By accurately acquiring and processing the dimensional information of the parts (including straight edges and curved edges), the minimum envelope rectangle of the parts can be accurately found and generated. The exact moving distance required to move the parts to the center of the electromagnetic chuck can be calculated using the center coordinates of the minimum envelope rectangle. This improves the accuracy and efficiency of part positioning and ensures the stability and consistency of the parts during the grinding process.

[0080] like Figure 2As shown, in some specific embodiments, based on the grinding information of the part, a grinding trajectory and a tool movement area are generated, and interference magnetic nails within the tool movement area are determined. This includes: acquiring the free edge information of the part, the tool diameter, and the tool offset; the free edge information includes straight edges and arc edges; determining whether the arc edge of the part has an inward concave arc segment with a radius smaller than the tool offset; if so, determining that the inward concave arc segment does not need to be ground; if not, determining that the inward concave arc segment needs to be ground; replacing the inward concave arc segment with a straight line to obtain the free edge information of the part after the initial processing; based on the free edge information of the processed part and the tool offset, offsetting the free edge of the part outward to generate a new free edge segment; based on the new free edge segment, determining whether the new free edge segment is connected; if so, generating a continuous tool movement trajectory for the part; based on the tool movement trajectory, adding the tool feed and retraction amounts at the start and end points of the tool movement trajectory to generate the final tool movement trajectory for the part; and determining the interference magnetic nails within the tool movement trajectory based on the final tool movement trajectory for the part.

[0081] The grinding information for the parts includes the free edge information of the parts, the tool diameter, and the tool offset.

[0082] This application efficiently generates the grinding trajectory and movement area of ​​the tool by accurately analyzing the free edge information of the part and combining it with the specific parameters of the tool (such as diameter and offset). This avoids unnecessary grinding of concave arc segments, reduces material waste and tool wear, and improves the accuracy and efficiency of grinding by adding feed and retraction amounts. Simultaneously, the determination of interference magnetic nails within the tool movement trajectory provides an important basis for subsequent magnetic nail placement and grinding operations, further ensuring the smooth progress of the grinding operation and the quality of the finished product.

[0083] The tool buffer amount is a safety margin reserved to account for the possibility that the tool may deviate from the trajectory curve during grinding.

[0084] When generating the grinding path for a part, the following steps are taken: First, the free edge information (including straight and curved edges), tool diameter, and pre-set tool offset are obtained. For curved edges, concave arc segments with radii smaller than the tool offset are identified and determined not to require grinding. These arc segments are replaced with straight lines connecting their start and end points, resulting in processed free edge information. Next, using the processed free edge information and tool offset, the free edges are offset outwards by the corresponding distance to generate new free edge segments. If these segments are connected, a continuous tool movement path is formed. If they are not connected, a curved arc with a radius equal to the tool offset is used for transition, resulting in a continuous grinding tool path. Further, feed and retraction amounts are added at the start and end points of the path to complete the generation of the final tool movement path. Finally, the position of the interference magnetic pin is determined based on the path.

[0085] In this process, it is determined whether the free edge of the part is still connected after the offset. If not, a smooth transition is achieved by using an arc with a radius equal to the tool offset and a center at the point where the two line segments overlap before the offset, thus obtaining the continuous tool movement trajectory of the part.

[0086] Specifically, based on the free edge information of the processed part and the offset of the tool, the free edge of the part is offset outward to generate a new free edge segment.

[0087] In this application, considering that the tool may come into contact with the part during the initial approach and retraction processes, dedicated approach and retraction trajectories are set at the approach and retraction points. Specifically, if the first approach segment is a straight line segment, an approach segment trajectory perpendicular to that segment and away from the part is generated; if the first approach segment is an arc segment, an approach segment trajectory perpendicular to the assembly edge and away from the part is generated. The process for retraction is similar and will not be described here.

[0088] Specifically, based on the new free edge segment, it is determined whether the new free edge segment is connected. If not, the unconnected segment is transitioned by an arc with the offset of the tool as the radius, generating a continuous tool movement trajectory for the part.

[0089] The offset line segments are obtained by calculating the normal vector of the straight edge, and the offset arc segments are obtained by calculating the vectors of the lines connecting the starting point and the ending point to the center of the circle. After offsetting all the free edges outward, a new set of free edge segments is obtained.

[0090] Reference Figure 3 As shown, in some possible embodiments, based on the initial posture information of the part, the position and angle with the fewest interference magnetic nails are determined, the remaining magnetic nail arrangement scheme is generated, and the final magnetic nail arrangement scheme is obtained. This includes: acquiring the initial posture information of the part and the final tool movement trajectory of the part, and calculating the position and number of interference magnetic nails in the initial state; generating all postures of the part based on the movement range and step size, rotation angle range and step size of the part on the electromagnetic chuck; calculating the position and number of interference magnetic nails under different postures based on all postures of the part; comparing the position and number of interference magnetic nails under different postures, determining the position and angle with the fewest interference magnetic nails as the optimal posture, generating the remaining magnetic nail arrangement scheme, and obtaining the final magnetic nail arrangement scheme.

[0091] In the comparison, the optimal posture can be obtained by comparing the number of magnetic nails obtained from all postures.

[0092] Specifically, based on the full range of orientations of the part, the position and number of interference magnetic nails under different orientations are calculated, including: obtaining the current orientation of the part, determining whether the part exceeds the electromagnetic chuck in the current orientation, if so, skipping the current orientation and continuing to move and rotate the part to the next orientation, if not, calculating the position and number of interference magnetic nails in the current orientation.

[0093] Specifically, firstly, the initial posture information of the part (referring to the position and rotation angle of the part) and the grinding trajectory information in this posture are obtained, and the position and number of interference magnetic nails in this posture are calculated; according to the movement range and step size of the part, the rotation angle range and step size, the other postures of the part are traversed in turn; it is determined whether the part exceeds the electromagnetic chuck area in the current posture. If so, the posture is skipped and the part is moved and rotated to the next posture. Otherwise, the position and number of interference magnetic nails in this posture are calculated.

[0094] In some specific embodiments, the position and number of interference magnetic nails under different postures are compared to determine the optimal posture with the fewest interference magnetic nails, generate the remaining magnetic nail arrangement scheme, and obtain the final magnetic nail arrangement scheme, including: obtaining the position and number of interference magnetic nails under the current posture and the position and number of interference magnetic nails under the previous posture;

[0095] The positions and numbers of interference magnetic nails in the current posture are compared with those in the previous posture. If the number of interference magnetic nails in the previous posture is less than that in the current posture, the previous posture is retained as the optimal posture. If the number of interference magnetic nails in the previous posture is greater than that in the current posture, the current posture is updated as the optimal posture. If the number of interference magnetic nails in the previous posture is equal to that in the current posture, the number of magnetic nails enclosed or contacted by the part contour in the current posture and the previous posture is calculated, and the posture with the larger number is taken as the optimal posture.

[0096] By comparing the positions and numbers of interference magnetic nails under different orientations, the optimal orientation can be determined by minimizing the interference of the magnetic nails. Simultaneously, by comprehensively considering the number of magnetic nails and the contact between the part contour and the magnetic nails, a more reasonable magnetic nail arrangement scheme can be generated, improving arrangement efficiency and accuracy.

[0097] Specifically, the number of interference magnetic nails obtained in the current posture is compared with the number of interference magnetic nails in the previous posture (the number of interference magnetic nails in the previous posture). If the number of interference magnetic nails in the current posture is less, then the posture is updated to the optimal posture; if the number of interference magnetic nails in the current posture is more, the original posture is retained as the optimal posture; if the number is the same, then the number of magnetic nails surrounded or contacted by the part contour in the two postures is calculated, and the posture with the more magnetic nails is taken as the optimal posture.

[0098] Reference Figure 4 As shown, in some specific embodiments, after determining the optimal pose, the method further includes: determining whether all poses have been traversed; if so, the determination ends and a remaining magnetic nail placement scheme is generated; if not, the remaining poses are traversed; and the remaining magnetic nail placement scheme is output as the final magnetic nail placement scheme.

[0099] Among them, the remaining magnetic nail information, as the magnetic nail arrangement scheme, is the magnetic nail layout formed after removing all interfering magnetic nails from the initial magnetic nail layout.

[0100] The final magnetic nail arrangement scheme is as follows: an initial magnetic nail layout is used, and then each part is traversed in turn to find the posture that minimizes the interference of the magnetic nails on that part as the optimal posture. After traversing all parts, the interference magnetic nail area is reduced to obtain the final magnetic nail arrangement scheme.

[0101] In some specific embodiments, based on the final magnetic nail arrangement scheme obtained by removing magnetic nails that do not provide support and fixation for the parts, a final magnetic nail arrangement scheme that meets the grinding requirements of the parts is output. This includes: obtaining the magnetic nail arrangement scheme under the optimal posture of all parts; determining whether each magnetic nail is completely located outside all parts based on the magnetic nail layout scheme under the optimal posture of all parts; if so, removing the magnetic nail from the magnetic nail layout scheme; if not, retaining it; determining whether to judge all magnetic nails; if not, continuing to judge; if so, outputting the final magnetic nail arrangement scheme that meets the grinding requirements of the parts.

[0102] Specifically, based on the magnetic nail layout obtained in the previous step, the positional relationship between each magnetic nail and all parts is determined sequentially; if a magnetic nail is located inside any part or in contact with a part, it is retained; otherwise, it is deleted. This process yields the final magnetic nail arrangement.

[0103] This application, through the above steps, can generate a magnetic nail arrangement scheme suitable for grinding most of the parts according to different shapes. It can perform simultaneous grinding on both sides through double-headed blade feed, and the magnetic nails fix the parts with magnetic attraction to prevent the parts from moving. This overcomes the problems of existing technologies where manual fixing of parts or fixing by support columns is difficult to guarantee grinding quality and parts need to be flipped to achieve double-sided grinding.

[0104] See attached document Figure 1-4 The illustration shows a magnetic nail placement process. This application designs a magnetic nail placement method suitable for bilateral grinding of most free edges of parts. Based on the majority of different shaped parts processed in actual shipyards, this method reserves positions on the electromagnetic chuck for placing magnetic nails and designs a magnetic nail placement scheme that meets the grinding requirements of the parts based on the interference magnetic nail removal method. The part shapes used in this example are as follows: Figure 5As shown, the magenta edges are the free edges of the parts and require grinding, while the blue edges are the welded edges and do not require grinding. The specific process includes:

[0105] S1: Using the origin of the Cartesian coordinate system as the bottom left point of the rectangular disk, generate an initial arrangement of magnetic nails covering the disk based on the disk's length and width, and the spacing and diameter of the magnetic nails. In this example, the disk size is 800mm * 500mm, allowing for a nail spacing of 50mm and a nail diameter of 30mm. The generated initial disk layout is as follows: Figure 6 As shown;

[0106] S2: Calculate the minimum envelope rectangle of each part and the coordinates of the center point of the rectangle from the initial coordinate information of each side of each part, and move the center to the center of the disk as the initial position for moving and rotating the parts when designing the magnetic nail layout. This attitude can find more part attitudes, making it easier to find the solution that minimizes the number of interference magnetic nails.

[0107] S3: Based on the data such as the free edge of the part, the tool diameter, and the reserved safety margin, the tool diameter used in this example is 45mm, the reserved safety margin is 10mm, and the tool offset is 16.85mm. The tool grinding trajectory for each part is generated based on the above data. The area where the tool moves along the trajectory is called the interference region, and the magnetic nails within the interference region are called interference magnetic nails. The grinding trajectory of one part is as follows: Figure 7 As shown by the dashed line;

[0108] S4: Based on the given part movement range and step size, rotation angle range and step size, adjust the position and angle of each part sequentially to find the part position and angle that minimizes the number of interference magnetic nails under all orientations, and obtain the remaining magnetic nail layout scheme. In this example, the part movement range used is 100mm for both horizontal and vertical movement, with a step size of 5mm; the angle rotation range is 0-90° counterclockwise, with a step size of 5°. Figure 8 This demonstrates the non-interference situation of one of the components at its initial position and angle, and the specific process of this step is as follows: Figure 9 As shown, the last sub-figure is the magnetic nail layout scheme obtained after determining all parts;

[0109] S5: Further process the magnetic nail layout scheme obtained in the previous step, removing magnetic nails that do not provide support or fixation for the part, and outputting the final magnetic nail layout adapted to the part's grinding process. The specific magnetic nail layout is as follows: Figure 10 As shown.

[0110] In the above steps, the detailed steps in step S2 are as follows:

[0111] Based on the initial coordinate information of each edge of the part, the edges of the part include straight edges and arc edges. Straight edges include the coordinates of the starting point and the ending point, while arc edges include the coordinates of the starting point, the ending point, the center of the arc, and the radius of the arc. Find the maximum and minimum values ​​of the coordinates of all edges of the part in the horizontal and vertical directions. Use these four maximum and minimum values ​​as the boundary of the rectangle to obtain the minimum envelope rectangle of the part.

[0112] Calculate the coordinates of the center point of the rectangle obtained in the previous step, let's say they are x0 and y0.

[0113] Calculate the distance the part needs to be moved to the center of the disk, including the horizontal and vertical movement distances, where the horizontal movement distance x_move = 400 - x0 and y_move = 250 - y0.

[0114] The part is moved from its initial position to the center coordinates of the disk based on the center coordinates of the envelope rectangle.

[0115] The detailed steps of step S3 are as follows:

[0116] After the part is moved to the center of the disk, the data of each free edge is obtained. For straight line segments, the data includes the start coordinates and end coordinates. For arc segments, the data includes the start coordinates, end coordinates, arc center, and radius.

[0117] First, iterate through all the arc segments of the part. If the part contains an arc that is concave and the radius of the arc is less than the tool offset, then it is determined that the arc will not be ground and the arc will be replaced with a straight line so that the tool can move continuously. The remaining arcs and straight line segments are ground to obtain the processed free edge information.

[0118] The free edges of the part are offset outwards using the straight offset method and the circular offset method. The straight edges are offset by calculating their normal vectors to obtain the offset line segments, and the circular edges are offset by calculating the vectors of the lines connecting the starting point and the ending point to the center of the circle. After offsetting all the edges outwards, a new set of line segments is formed.

[0119] Determine whether the free edge of the part is still connected after the offset. If not, use an arc with a radius equal to the tool offset and a center at the point where the two line segments overlap before the offset to smoothly transition and obtain a continuous grinding tool movement trajectory.

[0120] Considering that the tool may come into contact with the part during the initial approach and retraction, specific approach and retraction paths are set at the approach and retraction points. Specifically, if the first approach segment is a straight line, a path is generated perpendicular to that segment and away from the part; if the first approach segment is an arc, a path is generated perpendicular to the assembly edge and away from the part. The retraction process is similar and will not be described further. The generated grinding path for one part is as follows: Figure 7 As shown, the solid lines represent the outline of the part, and the dashed lines represent the grinding path of the part.

[0121] The detailed steps of step S4 are as follows:

[0122] Obtain the initial orientation information (position and rotation angle) of each part, and determine whether each magnetic pin is located in the interference region during the part grinding process by traversing each magnetic pin. Calculate the number of interfering magnetic pins in that orientation. Figure 8 As shown, the interference magnetic nails of one of the components are shown in the initial orientation. The interference magnetic nails have been removed from the original disk in the figure, and the number of interference magnetic nails is calculated to be 44.

[0123] Based on the part's movement range and step size, and rotation angle range and step size, the remaining postures of the part are traversed sequentially.

[0124] Determine whether the part exceeds the disk area in the current posture. If so, skip the posture and continue to move and rotate the part to the next posture. Otherwise, calculate the position and number of interference nails in the current posture.

[0125] Compare the number of interference magnetic nails obtained in the current posture with the number of interference magnetic nails found in the previous posture. If the number of interference magnetic nails in the current posture is less, then update the posture to the optimal posture; if the number of interference magnetic nails in the current posture is more, retain the original posture as the optimal posture; if the number is the same, then calculate the number of magnetic nails surrounded or contacted by the part contour in the two postures, and take the posture with more magnetic nails as the optimal posture.

[0126] Determine if all poses have been traversed. If so, output the remaining magnetic nail information as a magnetic nail placement scheme; otherwise, continue traversing the remaining poses. The optimal pose found for one of the parts is as follows: Figure 9 son Figure 1 As shown, the number of interference magnetic nails in this attitude is 38, which is less than the number of interference magnetic nails in the initial attitude.

[0127] Each component is evaluated sequentially, and its optimal orientation is found. The final magnetic nail layout scheme is then output. For example... Figure 9 The first eight sub-figures show the optimal poses of all parts in this example and the remaining non-interference magnetic nails, resulting in the magnetic nail layout as follows. Figure 9 The last sub-image is shown.

[0128] The detailed steps for S5 are as follows:

[0129] Based on the magnetic nail layout obtained in the previous step, it is determined in turn that each magnetic nail in the layout is either located inside the part or in contact with the part.

[0130] If a magnetic nail is located inside or in contact with any part, then retain the nail; otherwise, remove the nail from the nail layout. After traversing and searching all magnetic nails, the final nail layout scheme is obtained as follows: Figure 10 As shown, Figure 11 It shows the placement of each component in the final magnetic nail layout.

[0131] The specific embodiments of this application have been described above. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method for fixing magnetic nails on the free edge of a ship hull part by double-sided grinding, characterized in that, include: Based on the data of the electromagnetic chuck and magnetic nails, an initial layout scheme is generated in which the electromagnetic chuck is filled with the magnetic nails; Based on the size information of the parts, calculate the minimum envelope rectangle of the parts, and move all the parts to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point; Based on the grinding information of the part, the grinding trajectory of the tool and the tool movement area are generated, and the interference magnetic nails in the tool movement area are determined. Based on the initial attitude information of the parts, determine the position and angle of the interference magnetic nails with the minimum, generate the remaining magnetic nail arrangement scheme, and obtain the final magnetic nail arrangement scheme; Based on the obtained final magnetic nail arrangement scheme, remove the magnetic nails that do not provide support and fixation for the part, and output the final magnetic nail arrangement scheme that meets the grinding requirements of the part.

2. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 1, characterized in that, The step of calculating the minimum envelope rectangle of the parts based on their size information, and moving all the parts to the center of the electromagnetic chuck with the center of the minimum envelope rectangle as the reference point, includes: Obtain the dimensional information of all parts, including the dimensional information of each side of the part; The edges of the part include welded edges and free edges; Based on the free edges of the part, find the maximum and minimum values ​​of the coordinates of the free edges of the part in the horizontal and vertical directions, and generate the boundary of the rectangle to obtain the minimum envelope rectangle of the part. Calculate the coordinates of the center point of the minimum envelope rectangle based on the minimum envelope rectangle of the part; Based on the coordinates of the center point, calculate the distance that the part needs to move to the center of the electromagnetic chuck, including the lateral movement distance and the longitudinal movement distance; Move the part to the center of the electromagnetic chuck.

3. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 2, characterized in that, The step of generating the grinding trajectory and tool movement area of ​​the tool based on the grinding information of the part, and determining the interference magnetic nails within the tool movement area, includes: Obtain the free edge information, tool diameter, and tool offset of the part; the free edge information includes straight edges and arc edges; Determine whether the arc edge of the part has a concave arc segment with a radius smaller than the offset of the tool. If so, determine that the concave arc segment does not need to be ground; otherwise, determine that the concave arc segment needs to be ground. The concave arc segment is replaced with a straight line to obtain the free edge information of the part after the initial processing; Based on the processed free edge information of the part and the offset of the tool, the free edge of the part is offset outward by the offset distance of the tool to generate a new free edge segment; Based on the new free edge segment, determine whether the new free edge segment is connected. If so, generate a continuous tool movement trajectory for the part. Based on the tool movement trajectory, the feed and retraction amounts of the tool are added at the start and end points of the tool movement trajectory to generate the final tool movement trajectory of the part. Based on the final tool movement trajectory of the part, the interference magnetic nails within the tool movement trajectory are determined.

4. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 3, characterized in that, The step of generating a new free edge segment by offsetting the free edge of the part outward by the offset distance of the tool center based on the processed free edge information of the part and the offset of the tool center includes: Obtain the free edge information of the processed part and the offset of the tool center, and offset the free edge of the part outward; The straight edge is obtained by calculating its normal vector to get the offset line segment, and the arc edge is obtained by calculating the vector of the line connecting the starting point and the ending point to the center of the circle to get the offset arc segment. After all the free edges are offset outward, a new set of free edge segments is obtained.

5. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 3, characterized in that, The process involves determining whether the new free edge segment is connected. If not, the unconnected segment is transitioned by an arc with a radius equal to the offset of the tool, thereby generating a continuous tool movement trajectory for the part.

6. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 3, characterized in that, The process of determining the minimum position and angle of the interference magnetic nails based on the initial attitude information of the part, generating the remaining magnetic nail arrangement scheme, and obtaining the final magnetic nail arrangement scheme includes: Obtain the initial posture information of the part and the final tool movement trajectory of the part, and calculate the position and number of interference magnetic nails in the initial state; Based on the movement range and step size, rotation angle range and step size of the part on the electromagnetic chuck, generate all postures of the part; Based on all the orientations of the parts, calculate the position and number of interference magnetic nails under different orientations; Based on the positions and numbers of the interference magnetic nails under different postures, and by comparison, the position and angle with the fewest interference magnetic nails are determined as the optimal posture, generating the remaining magnetic nail arrangement scheme, and obtaining the final magnetic nail arrangement scheme.

7. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 6, characterized in that, The step of calculating the position and number of interference magnetic nails under different orientations based on all orientations of the component includes: Obtain the current posture of the part, determine whether the part exceeds the electromagnetic chuck in the current posture, if so, skip the current posture and continue to move and rotate the part to the next posture, if not, calculate the position and number of interference magnetic nails in the current posture.

8. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 7, characterized in that, The process involves comparing the positions and numbers of interference magnetic nails under different orientations to determine the optimal orientation with the fewest interference magnetic nails, generating the remaining magnetic nail arrangement schemes, and obtaining the final magnetic nail arrangement scheme, including: Obtain the position and number of the interference magnetic nails in the current posture and the position and number of the interference magnetic nails in the previous posture; The positions and numbers of the interference magnetic nails in the current posture are compared with those in the previous posture. If the number of interference magnetic nails in the previous posture is less than the number of interference magnetic nails in the current posture, then the previous posture is retained as the optimal posture. If the number of interference magnetic nails in the previous posture is greater than the number of interference magnetic nails in the current posture, then the current posture is updated to the optimal posture. If the number of interference magnetic nails in the previous posture is equal to the number of interference magnetic nails in the current posture, then calculate the number of magnetic nails surrounded or contacted by the part contour in the current posture and the previous posture, and take the posture with the larger number as the optimal posture.

9. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 8, characterized in that, After determining the optimal posture, the process also includes: Determine whether all poses have been traversed. If yes, the process ends and the remaining magnetic nail placement scheme is generated. If not, continue traversing the remaining poses. The remaining magnetic nail arrangement scheme is output as the final magnetic nail arrangement scheme.

10. The method for fixing magnetic nails during double-sided grinding of the free edge of a ship hull part according to claim 1, characterized in that, The step of removing magnetic nails that do not provide support and fixation for the part from the obtained final magnetic nail arrangement scheme, and outputting a final magnetic nail arrangement scheme that meets the grinding requirements of the part, includes: Obtain the optimal magnetic nail placement scheme under the optimal orientation of all parts; Based on the optimal magnetic nail layout scheme of all the parts, determine whether each magnetic nail is completely outside of all the parts. If so, remove the magnetic nail from the magnetic nail layout scheme; otherwise, retain it. Determine whether to evaluate all magnetic nails. If not, continue evaluating. If yes, output the final magnetic nail arrangement scheme that meets the part grinding requirements.

Images