General skills of the most popular UG reverse mode

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General skills of UG reverse modeling

general methods and skills of UG reverse modeling Abstract: basic concepts of indexable cutters the first super large gear measuring center in China has successfully developed CAD technology in Harbin Development Trend application and development trend of stamping materials programming coordinate system brief introduction to scraper middle slot tandem double wire welding process research and application of China's CNC machine tool technology innovation strategy (Part 2) Research on the process law of micro WEDM based on uniform design "1025" During the research period, the numerical control simulation of China's aviation and military industry has made a breakthrough. China's equipment manufacturing industry should guard against local protectionism. Lead free process control release agent. Research status of ultra precision machining in the plastic domain of brittle materials. Adaptive processing parameters of plane milling based on artificial neural network and genetic algorithm. Foundation and enterprise standardization. FANUC lathe programming skills. NC lathe processing programming source program for threaded parts 7. Non-standard tool based on pro/e With parametric design, Japan has strengthened its efforts to open up China's machine tool and mold market. The manufacturing industry of heavy machine tools is facing both opportunities and challenges [label: tag] in the process of product development and manufacturing, geometric modeling technology has been widely used. However, for various reasons, there are still many products that are not described by CAD models, and designers and manufacturers are faced with physical samples. In order to adapt to the development of advanced manufacturing technology, it is necessary to transform these objects into CAD models through certain ways, so that they can be processed by using CAD, cam and other advanced technologies. Item

in the process of product development and manufacturing, geometric modeling technology has been widely used. However, for various reasons, there are still many products that are not described by CAD models, and designers and manufacturers are faced with physical samples. In order to adapt to the development of advanced manufacturing technology, it is necessary to transform these objects into CAD models through certain ways, so that they can be processed by using CAD, cam and other advanced technologies. At present, the technology related to the technology of obtaining product mathematical models from physical samples has developed into a relatively independent category in CAD and cam, which is called reverse engineering. Through reverse engineering to reproduce the CAD model of the physical object, it is possible for those products based on the physical object to make full use of CAD, cam and other advanced technologies in the process of design and manufacturing. Because the implementation of reverse engineering can accurately and reliably copy the physical samples in a very short time, reverse engineering has become one of the hot topics in the current enterprise advanced manufacturing technology. Using some non professional reverse design software (such as UG, pro/engineer, CATIA, etc.) and some professional reverse design software (such as surfacer, CopyCAD, trace, etc.) for reverse modeling of fixture structure and requirements of tensile testing machine is a typical example of the application of reverse engineering in enterprises at this stage. Due to the need of new product development of the company, the author uses UG software to reverse the parts, and has achieved good application results in the reverse modeling design of automotive stamping parts with complex shapes. The measuring equipment we selected is the CMM of UK LK company, which can be used to measure the spatial coordinates of features, scanning profiles, measuring parting lines and contour lines. The amount of data obtained by this device is not as large as that scanned by the laser scanner, so it is appropriate to use some non professional reverse design software. UG reverse modeling follows the general principle of point, line and surface

I. measuring points

plan how to manage the measuring points before measuring points. The designer shall put forward the requirements for surface dotting. The general principle is that the dots should be denser in places with large curvature changes, and thinner in smooth places. Since the efficiency of general CMM is much lower than that of laser scanner, it is necessary to have a definite aim when measuring points of parts. It is worth noting that in addition to scanning the profile and measuring the parting line, it is also necessary to measure the contour line and other characteristic lines, which will bring convenience when constructing the surface

II. Connection

(1) the connection points shall be sorted out before sorting out the connection points, including removing the delay points and obvious defects. The section points in the same direction are placed in the same layer, the parting line points and hole points are placed in a separate layer, and the contour line points are also placed in a separate layer, which is convenient for management. Usually, this work is completed in the measuring point stage, or in UG software. The general measurement software can preset the placement layer of the points, measure the points and sort them out at the same time. (2) The point connecting line is connected with the parting line point to minimize the error and smooth. Because in many cases, the parting line is the assembly line of the product. For common parts in automobiles and motorcycles, the wiring error is generally controlled below 0.5mm. The connecting line shall be targeted, and the method of construction surface shall be roughly determined according to the shape and characteristics of the sample, so as to determine which lines need to be connected and which lines do not need to be connected. Lines can be straight lines, arcs, and splines. The most commonly used is spline, and the through point method is selected. The spacing of selected points shall be as uniform as possible. The places with rounded corners shall be ignored first and made into sharp corners. The rounded corners shall be made after the surface is completed. (3) Due to the measurement error and the unsmooth surface of the sample, the change of the curvature radius of the connected spline often has a sudden change, which has an impact on the smoothness of the future configuration. Therefore, the curve must be adjusted to make it smooth. The most common method of adjustment is edit spline. Select the edit pole option and drag the control point with the mouse. There are many options here, such as restrict the control point to a certain plane? ⑼? Easy to operate? (6) press the button to open the alarm? Allow the comb switch of pline, etc. In addition, to adjust spline, you often need to move one endpoint of spline to another point to make the curves of the constructed surface have intersections. However, it must be noted that no matter what command is used to adjust the curve, there will be deviation. The more adjustment times, the greater the cumulative error. The allowable error value depends on the specific requirements of the sample

III. facets

use various facet methods to build surfaces, including thought curve mesh, thought curves, rule, sweep, from point cloud, etc. The selection of the configuration method should be based on the specific characteristics of the sample. The most commonly used by the author is thought curve mesh, which weaves the adjusted curve into a surface with this command. The advantage of the thought curve mesh configuration surface is that it can ensure the continuity of the surface boundary curvature, because the thought curve mesh can control the curvature (tangency) of the surrounding boundary, so the quality of the configuration surface is higher. However, though curves can only guarantee the curvature of both sides, and the error is large in the configuration. If the intersection line of two surfaces needs to be rounded, a power battery enterprise employee who did not want to be named revealed to the reporter that the boundary of H is the intersection line of two surfaces. Obviously, this line is smoother than the intersection line of two thought curves surfaces. In this way, the fillet quality of blend is different. When you first learn reverse modeling, there are often creases between the two faces, which is mainly caused by the non tangency of the two faces. This problem can be solved by adjusting the tangent between the endpoint of the curve of the participating configuration surface and the corresponding curve in another surface, plus the tangent of the boundary of the thought curve mesh option. Only curve tangency guarantees surface tangency. In addition, sometimes it is more convenient to directly use the from point cloud when making a single flat surface. However, those half curvature shall be stopped for inspection; In case of failure during operation, the curved surface with large change of time and diameter shall not be inspected, and the error of structural surface is large. Sometimes the gap between faces needs to be bridged to ensure smooth transition of surfaces. In the process of building a surface, some lines are sometimes added to construct the surface. Lines and planes often alternate. After the surface is completed, the error of the surface shall be checked. Generally, the error from point to surface shall be measured. For the surface with high appearance requirements, the smoothness of the surface shall also be checked. When a surface is not smooth, you can find some sections of the surface, adjust these sections to make it smooth, and then use these sections to reconstruct the surface. The effect will be better. This is a common method. Attention should also be paid to the simplicity of the structural plane. The surface should be as large as possible, with a small number of sheets and not too broken. This is conducive to adding some features such as fillet, slope and thickening, and is also conducive to the next programming and processing. The amount of tool path calculation will be reduced and the NC file will be small

IV. structure

when the outer surface is completed, the next step is to build a solid model. When the model is simple and the quality of the outer surface is good, the solid can be established by using the sewing thickening command. However, in most cases, it cannot be thickened, so only offset the outer surface can be used. Use the offset command to select multiple faces at the same time or use the window to select all, which will improve the efficiency. For surfaces that cannot be offset, learn to analyze the cause. One possibility is that the curvature of the surface itself is too large, which will self intersect after offset, resulting in offset failure (some software algorithms are different from this algorithm, such as rhinoceros king can offset those surfaces that will self intersect), such as small rounded corners; Another possibility is that the quality of the offset surface is poor and there are local ripples. In this case, you can only offset after modifying the surface; Some other surfaces seem to have good smoothness, but they can't be offset. In this case, you can use extract geometry to form a B surface, and then offset it. It will basically succeed. Some offset surfaces need to be trimmed and some need to be patched. Various surface methods are used to construct the inner surface, and then the inner and outer surfaces are stitched to form a solid. Finally, the product structure is designed, such as stiffeners, mounting holes, etc

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