3D simulation modeling of the tooth surface of the

2022-08-16
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Three dimensional simulation modeling of worm gear tooth surface

introduction

at present, in Chinese enterprises, computer aided design CAD (CAD) is being welcomed and valued, and has been gradually popularized and applied. Computer aided design can greatly improve the design quality, reduce the workload of designers, shorten the design cycle, reduce product costs, and create favorable conditions for the development of new products and new processes

The tooth surface of the worm gear is a complex curved surface. At present, the approximate drawing method is usually used to draw the tooth profile of worm gear in common CAD software, so it is difficult to accurately draw the complex tooth surface of worm gear

solidworks is a set of Feature-Based Parametric mechanical design automation software. SolidWorks has gradually become the mainstream 3d terminal CAD solution with its powerful function, friendly interface and continuous technological innovation. The following will introduce how to call the API (application program interface) function of SolidWorks through programming, simulate the relative motion of worm gear hob and worm gear blank when machining worm gear, and realize the three-dimensional simulation modeling of worm gear complex tooth surface in the interface of SolidWorks through solid Boolean difference operation

1 SolidWorks secondary development tools and methods

the author selects Visual Basic as the secondary development tool of SolidWorks. The application program interface developed with Visual Basic is very friendly. VB has powerful functions and convenient database operation, which is easy for beginners to master. Using VB to develop software has short development cycle and high program code efficiency. SolidWorks also provides macro recording function, which brings great convenience to the programming. We can first record the operations performed in the SolidWorks user interface and create a macro file whose code syntax fully conforms to visual basic. Obtain the required SolidWorks objects through macro files, replace the key parameters in API functions with variables, modify this macro code and add it to the program, so that the operation on the required SolidWorks interface can be controlled and executed in the program. For example, draw a circle in SolidWorks, macro record its process, and establish a macro file (internal programming). Then, in this macro file, you can find the object of drawing circles and its method part:: CreateCircle in the macro file. With the help of API, you can understand the meaning of parameters in API functions, and then use variables to replace the key data in the macro file, such as center coordinates, circle radius, etc. in this way, you can drive and add the function of drawing circles in your own program

the calls contained in macros are equivalent to calls to APIs when operations are performed using the user interface. By recording macros and executing tasks interactively, you can get the commands and syntax of the required code. Before writing any code, you record macros as the basis of your program. That is, when adding functions to the program, return to SolidWorks, record the added macro, and then clip and paste the recorded macro code into the program code, which is very helpful for programming

when using VB to carry out secondary development of Solidworks, we must first connect VB with Solidworks, which requires two steps: first, before writing VB code, reference SolidWorks object library SolidWorks 2005 type library in VB programming environment. Secondly, write VB program code to create SolidWorks objects, and start and run SolidWorks. Variant type in VB can be used to declare OLE object variables, and create0object function is used to create OLE objects. SolidWorks' reference objects include SolidWorks application objects (sldworks) and all its subordinate objects. When writing your own application code, the program code can refer to the code of the macro file and make necessary modifications. Finally compile and generate * Exe executable

2 ActiveX Automation Technology

active x is a new technology proposed by Microsoft. It is based on COM, including OLE technology and various technologies applied to the Internet. It enables different processes (even processes on the network) to communicate with each other, and develops towards multimedia. ActiveX is an object-oriented component system, which includes all aspects of component software, including composite documents, custom control, OLE automation, interactive application scripts, data transmission and the interaction of other distributed software. These component objects provide users with various functions, so that components provided by different software suppliers can connect and communicate between binaries. Objects realize the interaction between components and between components and systems through interfaces. ActiveX is a standard by which software components developed in different languages can interoperate in a stand-alone or network environment. Through ActiveX Automation Technology, SolidWorks can be operated from outside the SolidWorks operating environment. We take the program developed by VB as the client and SolidWorks as the server. VB programs can establish associations with Solidworks objects at all levels; In addition, the SolidWorks type library must be loaded through "reference" in VB, so that VB can recognize the types, properties and methods of SolidWorks objects used in the program

3 simulation modeling of worm gear tooth profile

when machining worm gear with worm gear hob, it is necessary to determine the center distance between tool and blank, the transmission ratio and shaft angle of tool spindle and blank spindle. When the worm gear hob is processing the worm gear, the worm gear hob rotates around its axis at a certain speed and makes a straight-line feeding motion at the same time; At the same time, the worm gear blank also rotates around its axis at a certain speed, so as to realize processing. Because the simulation modeling is carried out in the computer, the cutting processing of the blank is realized through the Boolean difference operation between entities (the combined operation in the SolidWorks menu). You can also choose to determine the shaft angle before machining. According to the principle of relative motion, if the blank body does not move during the simulation processing, but after the tool body rotates, it rotates around the center of the blank body in the opposite direction of the rotation of the blank body, and the effect is the same as the actual processing. Therefore, the author adopts the method that the workpiece does not move and the tool rotates around the center of the workpiece. In this way, only the tool entity needs to be operated, and the entity Boolean difference operation can be carried out conveniently

start the SolidWorks software automatically by running the program and insert the selected tool entity and blank entity. The program calls the required API function of Solidworks, controls the relative motion relationship and relative position of the tool entity according to the key parameters entered, and performs Boolean difference operation between entities (that is, the combination in the SolidWorks menu hopes to help you operate), so as to realize the cutting and processing of the tool entity to the blank entity, So as to get the required surface

by calling the properties and methods of soiidworks objects, a series of operations of simulation processing are realized. Call partdoc:: insertpart to insert the worm gear hob entity and worm gear blank entity into the SolidWorks software interface; Call feature ianger:: insertmove copybody2 to copy, move and rotate the entity; Call feature manager:: insertcombinefeature to make worm gear blanks generate pruned combined features (Boolean difference operation) and realize the simulation of cutting machining. The continuous action of cutting tools in machining blanks in reality is processed in segments in the simulation machining system. For example, assuming that the transmission ratio between the worm gear hob and the worm gear blank is 12/1, and the worm gear hob rotates by 12 °, the revolution angle around the worm gear center is 10> when this angle is rotated, the worm gear hob is copied once. During the simulation processing, the system continuously copies and rotates the worm gear hob to generate the hob envelope formed by the worm gear cutter movement, as shown in Figure 2. Through the solid Boolean difference operation between Liu Yi worm gear blank and the hob envelope formed by the worm gear hob movement, the tool envelope and the intersection with the worm gear blank are deleted, so as to process the tooth surface of the worm gear. When determining how to process a complete tooth, first determine the angle of a tooth according to the number of teeth of the worm gear to be processed, and then ensure to process a complete tooth roll 1 In case of random error in the universal experimental machine, the cutter must move two teeth, and then determine the number of times that the worm gear hob needs to move to process a complete tooth according to the machining accuracy set by the system program (that is, the angle that the worm gear hob copies once per revolution along the center of the worm gear blank), so as to process a complete worm gear tooth

the envelope formed by the movement of the worm gear hob

the figure shows part of the worm gear tooth profile processed by simulation

4 program example

some relevant codes are as follows:

5 Conclusion

on the SolidWorks platform, make full use of the API function provided by the software to simulate the motion relationship of worm gear hob machining worm gear blank in real machining on its interface, and calculate the solid Boolean difference between the tool envelope formed by the worm gear blank and the worm gear hob motion, and the three-dimensional model of worm gear blank. As the cutting process is constantly updated, the tooth surface of the worm gear is simulated and machined. Based on the method that solid manufacturing is twice the size of industrial standard adhesive, the expression of geometric model is consistent with the actual processing process, which makes it possible to accurately compare the final results of simulation modeling with the designed products. (end)

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