The establishment principle and method of 3D stand

Principles and methods of establishing 3D standard parts library based on UG

I. concrete, principles of establishing standard parts library based on UG

1. Each standard part should have a central datum (such as datum point or datum axis or datum plane, which mainly uses three plane datum). When establishing a standard part, the coordinate system (relative coordinate and absolute coordinate) should be at the symmetrical center of the standard part

2. the number of features should be reduced as much as possible, and the size between features should be expressed by relational expression. The feature parameters are divided into primary parameters and secondary parameters, and the primary parameters are used to control and constrain the secondary parameters

3. each standard part should set "reference rets" in the menu "assemblies", and only feature entities (solid) will be displayed when called out

4. for a standard part composed of several standard parts assembled together, attention should be paid to establishing the parameter value transmission between the standard parts in the standard part, that is, establishing the normal force transmitted to the sample by the dimensional link relationship between the standard parts, and using a main standard part to control and constrain other secondary standard parts

II. Creation method of standard parts

1. Spreadsheet method

(1) file → new, enter a standard part file name

(2) application → modeling, select appropriate parameters and method steps to establish a specific part (template part) in the standard part. Since the method and steps of establishing template part will directly determine the selection of parameters, it should be considered as a whole

(3) toolbox → expression, rename and edit the parameter expression

(4) toolbox → part families, select parameters in the available columns column, click add column to put them in the choose column column, and after selecting all parameters, click create to enter the spreadsheet

(5) fill in and spread sheet. Enter the part number (P turn off the controller and computer; art_name) and relevant parameter values in the spreadsheet. After filling in, you can select the verify part of part family to generate a part to clarify whether the parameter selection is correct. After the above work is correct, select the save family of part family to save the spreadsheet

(6) call of standard parts. Assemblies → edit structure, click Add; Specify the selected standard part in part name; Specify the position of the part to be added in the point subfunction [such as (0, 0, 0)], so that the standard part is generated at the specified point

advantages: it provides a standard part library system defined by UG 3D solid format, which is intuitive and easy to create, and can be transferred into the assembly through an intuitive graphical interface; It can make standard parts have sub assembly function and can be encapsulated into Iman and ug/manager. It is a general method to establish UG standard parts library system. Disadvantages: when calling, the name must be changed and stored. If the name is not changed, it can only be stored in the current directory and cannot be modified. When the model is selected and needs to be changed, it must be reassembled

2. Expression method

(1) file → new, enter a standard part file name

(2) application → modeling, select appropriate parameters and methods to establish a specific part (template part) in the standard part

(3) toolbox → expression, rename and edit parameter expressions

expression method: 1) in the "multiple expressions" dialog box, click "output", give a file name (such as P) in the directory and exit UG. 2) The expression file P is and stored. 3) Return to UG, open the part file, enter the "multiple expressions" dialog box, click "input", and enter the expression file

(4) file → save, store the part (.Prt)

(5) part call. Assemblies → edit structure, click Add; Specify the selected standard part in part name; Specify the position of the part to be added in the point subfunction [such as (0, 0, 0)], so that the standard part is generated at the specified point. Then, the part is stored under another name and converted into a specific part in the assembly model. Finally, the part is transformed into a working part and its parameters are modified to meet the design requirements

advantages: easy to create and modify. Disadvantages: only a template is transferred in during assembly, and its variables need to be modified after assembly; It is necessary to check the standard. These investments have brought huge economic benefits: in 2004, Langsheng company separated from Bayer Group Company and revised the variable value according to the standard manual

3. user defined feature (.Udf) method

(1) file → new enter a standard part file name, and application → modeling generates a part file

(2) toolbox → expression user names (rename) and (Edit) parameter expressions

(3) file → export, generate, define and store a UDF file

(4) toolbox → features → user defined implementation call

advantages: it is easy to create; You can establish the relationship between characteristic parameters, define characteristic variables, set default values, and prompt for key values; Easy to recover and. Disadvantages: you must create a new part to enter user-defined features

4. Use program design (＊.Grx or *.dll): UG/open grip and/or UG/open API (ufun) development programming to realize the generation and call of standard parts

advantages: interactive call in is the most convenient and the highest application level. Disadvantages: it needs to be written by program, and the workload is large

III. conclusion

establishing a CAD standard parts library is the cornerstone of implementing CAD application and an important way to improve the level of CAD application. The establishment method of 3D CAD standard parts library based on UG described in this paper has been implemented in the factory where the author works and achieved the expected effect