The casing that is based on draft unit feature to embed is sectional devise a method

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  • source:EAMOM CNC Machining
0 overviews mature with each passing day in fundamental theory respect as CAD/CAM technology, a lot of outstanding three-dimensional design software already won wide application, these current software offerred powerful three-dimensional parameter to change design function. But the operation of 2 dimension draft, the user can produce dot, line, arc through the picture only (round) will design spare parts outline to undertake restraining then with basic 2 dimension geometry, do not provide the faces a feature operation method as three-dimensional operation in 2 dimension operation. Special to complex swing tower (for example aviation engine casing) for, in sectional draft local the structure that has a lot of likeness, every time modelling can begin a definition from basic geometry element only, the repetition in creating molding process works, the article put forward to use unit of feature of 2 dimension draft to embed the new method of another draft, the operation of three-dimensional feature the technology introduces in 2 dimension draft, it is OK to make draft of 2 dimensions feature unit as three-dimensional feature same, through dimension drive can finish model, can raise draft to design efficiency greatly thereby. The means that the article offers is in platform of existing CAD software (UG) go up of development, its are basic the method can popularize other CAD platform, apply in design of other and complex draft. Graph 1 casing draft is sectional structure of likeness of draft of structure of graph draft likeness 1 draft the casing of analytic aviation engine of 2 dimension feature is the typical part that has complex and sectional structure, interior has a lot of similar groove, graph 1 for some model casing circumgyrate is sectional line outline, sectional graph discovers analytic casing draft has multistage likeness structure, if the graph is shown 2 times, if use parameter to change a tie to construct this kind of draft not only trival, and easy make mistake. Graph 3 undertake restraining for a from inside similar structure is taken out in sectional draft. This structure tie needs more than 40 geometric constraint and tie of more than 30 dimension, and this model such structure in casing has 3, 4 class, bring about repeat have same job, every time draw the outline of is identical the sectional line of appearance, undertake identical geometric constraint, only the measurement that dimension restrains is different. The modelling of this kind of spare parts is designed, draft tie holds very large proportion. 2 dimension draft can be its understanding a kind of special feature, in three-dimensional feature, the operation of every feature is OK and ordinal undertake, a feature can be in after undertake operating on diagnostic foundation before, be in for example already entity goes up to found an aperture directly. This is a kind of feature operation that is based on the history. To feature of 2 dimension draft, the local geometry figure inside draft cannot have been defined beforehand like three-dimensional feature, can operate interactively by the user only when the design geometrical element undertakes restraining, efficiency is inferior. Graph structure of 2 casing draft analyses a scheme the insertion of draft feature unit that the article offers hint of tie of draft of 3 constructions unit, can make draft designs these pair of feature unit to undertake going all out installing, come true " diagnostic piece " operation, and its the tie is taken along with all the others, form an onefold draft, if pursue,1 is shown. The principle is: The draft of will similar structure is unit (pursue for example a similar structure of 3) the definition is a special 2 dimension feature hand-in-hand travel tie, the diagnostic member that regards a feature as the library is saved. Should have a part when sectional design, in current working draft (call target draft) in when wanting to design a certain similar structure, call the 2 dimension feature in diagnostic library, in inserting unit feature draft directly, read in geometrical element of the feature, geometric constraint and dimension tie the draft of current design, with part of dimension of a group of drive new break fulfils the obligation of draft unit. And geometric constraint and dimension tie are taken along with all the others. Because enclosed draft to design a process,geometry, dimension restrains an operation, can improve design efficiency greatly. But current CAD is not inserted of unit of supportive draft feature directly, to fast draft the design brings greater difficulty, the definition that solves unit feature accordingly and enclose and of the feature cite become the crucial problem that should solve. This method includes two parts content: ① defines diagnostic unit: The draft of tectonic feature unit, restrain draft like regular draft, in keeping existence feature library. ② is in the target draft of current job, the 2 dimension draft that through diagnostic library the choice is about to insert is unit, comparative target draft and the basic message of 2 dimension draft, keep diagnostic geometry the corresponding position of target draft, take geometric constraint and dimension obligation at the same time. It is OK that such users are operated through one pace the geometry in diagnostic draft, geometric constraint, measure the tie keeps current draft, can finish through dimension drive insert draft unit, to casing this kind has the part of identical structure administrative levels, such design method can improve design efficiency greatly. 2 crucial technologies 2.

Information of feature of 1 2 dimension filters diagnostic draft keeps existence feature library as unit of a feature in, here is the form with the file expresses. The feature that it gets when inserting is cultivated, inquire information of diagnostic draft geometry one by one, keep pertinent information to target draft. File of model of a draft contained all sorts of information, and what the article cares is draft message, it includes draft basic message, geometry information and tie information, basic message includes draft vector of draft coordinate department and origin. The basic message of the basic message of diagnostic draft and specific target draft is different, such diagnostic draft write the geometry of target draft to be about to have corresponding shift. From inside the information of diagnostic file the sieve singles out draft basic message, numerate basic message and target draft oppose compare diagnostic draft, the design changes function, the geometrical information that alternates the course and tie information write target draft correctly. 2.

2 geometry information and the draft unit demand that restrain map to add target sketch are but draft of editorial total obligation piece. In diagnostic draft read take, information is chosen, information of the requirement in the process that keeps is significant, did not lose. The order that the order that the article designs according to draft restrains by geometry, geometric constraint, dimension reads in information. When writing geometry to target draft, comparative two draft are absolutely coordinate and relative position, undertake coordinate is changed, in writing geometry target draft (discuss in detail see below at 4 o'clock) , founding geometry while the map list that builds diagnostic draft and target draft geometry. The geometric constraint of draft and dimension tie are mostly related to other geometry, after target draft builds geometry, the correspondence that geometry should find out when keeping a tie concerns, ability joins corresponding tie correctly to corresponding geometry, below it is a specification with a the simplest draft, hypothesis feature draft has 3 geometry element: Two linear (L1, L2) a circular arc (A1) , geometry and tie concern contrast as follows to express place to show: Relation of map of the geometry in expressing 1 draft expresses 2 geometric constraint to contrast to be inserted the watch is unitly to the feature every time, should build new, old geometry to contrast watch, assure the correct affiliation of tie of geometry, dimension. 2.

The control of type of 3 geometric constraint inserts a method as a result of diagnostic unit is based on UG platform development, the information that the API function of certain tie type numerates perhaps cannot rebuild not completely, to assure the integrality of target draft message, to the feature draft should choose logical tie way. For example, sectional line has casing a kind of typical tie: A linear position is used " on the point that the line gives coordinate in two " will restrain, but in the discovery in inserting map process this share information always is lost, the function of tie information API that the reason is concerned dot rebuilds not to support, put forward to use the equal in value tie that steep end points nods section in all to replace, avoid to restrain missing phenomenon. 2.

The draft of 4 fixed position feature that insert 2 dimension feature are the pattern plate of a static state, the position of draft and direction are certain, and the position of target draft and direction are trends, according to target draft different, the coordinate with general design changes algorithm to change the geometrical message of diagnostic draft correctly, write its correctly target draft, make sure geometry is inside target draft plane and mutual between develop attacks the relation is changeless. Coordinate changeover uses gyral train of thought twice, API function founds geometry to ask to input absolutely coordinate of geometry, plane of comparative target draft and the relative position with diagnostic planar draft, rotate geometry to go up to target plane first, what rotate to be fastened relative to target draft coordinate again is correct locally, pass commutation twice, get writing correct coordinate of geometry, found new geometry. Feature of similar draft unit embeds for many times same draft, the unity of the many similar geometry in needing to solve target draft names. The geometry of this module names regulation is to use read take diagnostic draft the name of corresponding geometry is added again suffixal the method that regards new geometry as the name. 3 algorithm realize the crucial technique that discusses above the basis, design algorithm is finished the inquiry that finishs pair of feature draft in condition of current draft editor, geometry is changed and insert, the accretion that geometrical dimension restrains, algorithmic flow shows 4 times like the graph: Brief summary of graph 4 4 pursues 2 development that the means that the article offers information of draft of 5 current editors has carried UG form a draft to design a tool, citing application is as follows: Graph the 5 parameter that go up for current job draft change a figure, graph the 6 diagnostic draft in be diagnostic library, should need to insert a graph on working draft when 6 medium parameter change a figure, need to find the diagnostic draft that should insert in diagnostic library only, the result that attainable graph shows 7 times, get one spells the draft after outfit thereby, this draft makes general draft namely, can undertake parameter is revised, very convenient. Graph the article uses information of 6 features draft this tool undertakes casing kind the design of the spare parts, obtained remarkable result, compressed a spare parts to design cycle apparently. Use the tool of the article, build unit of all sorts of commonly used similar feature draft warehouse of feature of 2 dimension draft, can operate like three-dimensional feature same, diagnostic draft is inputted in draft, change into travel parameter next revise. In the design that this method can popularize the other part that has similar structure, scale of the fast draft that finish works, make an user convenient the draft that receives total obligation, the parameter that raises this kind of part changes a design degree and the efficiency that build a model. Graph 7 after inserting pattern plate current draft message CNC Milling CNC Machining