Fast and accurate modeling and Simulation of gears

Rapid and accurate modeling and simulation analysis of gears based on CAXA and UG

Abstract: This paper introduces the methods commonly used for gear three-stage modeling and their respective advantages and disadvantages. Taking the design of spur cylindrical gears of a certain type of reducer as an example, this paper introduces the process of rapid and accurate modeling and design of gears using CAXA and UG software, and carries out a real analysis of the imitation of the designed gears with software according to the actual design requirements. The process shows that the combination of these two software for gear design and modeling is fast and effective, and provides an effective basis for the R & D and design of other similar products

key words: spur gear; CAXA、UG； Modeling; Simulation analysis

gear transmission has the remarkable characteristics of high efficiency, compact structure, reliable operation, long service life and stable transmission. It is the most important type of transmission in mechanical transmission, which is widely used. The most commonly used transmission gear is involute gear

because the tooth profile curve is involute, when designing the gear for three-dimensional modeling, the tooth profile curve needs to meet the involute equation. Modeling directly with the involute equation is troublesome, time-consuming, and the accuracy is limited, and the accuracy of modeling will affect the subsequent finite element analysis, simulation results, gear manufacturing accuracy, etc. The commonly used gear modeling methods in engineering mainly use secondary development to realize its modeling or use the powerful modeling function provided by the three-dimensional modeling software to complete the modeling of gears. Among them, the secondary development method has large investment, long cycle and poor versatility, while using CAD software can realize the three-dimensional modeling of complex parts in a short time, and carry out the corresponding subsequent simulation analysis. UG is a widely used CAD software, which has powerful three-dimensional modeling function, and can carry out subsequent force analysis, motion simulation and NC machining on the built model. CAXA electronic drawing board is an efficient, convenient and intelligent domestic two-dimensional drawing CAD software with a complete range of parametric national standard drawing libraries. Therefore, when designing gears, we can often use the two software together to achieve rapid and accurate modeling and improve the efficiency of product R & D and design. The following is an example to introduce this method

1 create a three-dimensional solid model of the gear

1.1 establish the tooth profile curve of the gear end face

If a cylindrical spur gear is designed for a certain type of reducer, the tooth profile curve is involute. The requirements of gear design parameters are as follows: modulus m=4mm, number of teeth z=21, pressure angle α= 2O °, tooth width b=54mm. When establishing the tooth profile curve of gear end face, the parametric design function based on feature, dimensional constraint, data correlation and dimension driven design modification in UG can be used to design. However, it is necessary to first use the "expression" module of UG to express the involute equation, and then use the "curve" module to generate an involute curve on the first side of a single tooth, and trim the tooth profile curve on the first side of a tooth through the parameters such as the addendum circle and root circle of the gear; Then draw the center line of the single tooth, and use the "mirror" command to make the tooth profile curve of the corresponding side, that is, make the tooth profile curve of the single tooth; Then use "transform", "multiple copy" and other commands to draw the contour curve of all teeth, that is, the tooth profile curve of the gear end face. However, this construction process is cumbersome, error prone, low precision and slow speed. CAXA electronic drawing board software can be used to draw gear commands directly by using its own characteristics of parameter national standard drawing library. As long as the corresponding parameters of the gear are input, the end face tooth profile curve of the corresponding gear can be drawn directly, and then the generated end face tooth profile curve can be saved into *.dwg, *.dxf or *.igs format, which can be imported into UG. The generation process and results of gear end face profile curve drawn by CAXA electronic drawing board parametric national standard drawing library are shown in Figure 1 and Figure 2

it can be seen from the graphic process that it is convenient, fast and accurate to use CAXA electronic drawing board to parameterize the establishment of gear end face tooth profile curve

1.2 complete the solid model of the gear

when building the solid model of the gear with UG, directly import the two-dimensional gear end face profile curve file generated by CAXA electronic drawing board, directly stretch the gear end face profile curve with the "stretch" command to the width of the gear tooth b=54 mm, and then obtain the accurate model of the gear tooth, and then complete the relevant geometric dimensions such as the keyway with the "stretch removal" and other related commands, that is, complete the construction of the accurate solid model of the gear, The process is shown in Figure 3

2 gear simulation analysis

the "advanced simulation" module of UG is used to simulate and analyze the designed gear. First, define the material of the gear. In this example, the material is defined according to the actual material of the gear and the performance parameters of the material. The material is 45 steel, the density is 7.8g/cm3, the elastic modulus E is taken as 21ogpa, the shear modulus G is taken as 8L GPA, and the crack position of the sample may occur at the time of strong force. The loose ratio is taken as 0.25, and the thermal expansion coefficient is taken as 18. This technology has been widely used in chemical fiber, film, profile, pipe, plate, cable, composite extrusion, granulation and other production lines.48 ×/℃, the strength limit is 650mpa, and the yield limit is 360 MPa. According to the actual working conditions of the gear, add constraints, load, select the defined materials, divide into cells, and then conduct simulation analysis. The results of simulation analysis can be given in the form of diagrams or reports. According to the results, the deformation and stress-strain of gear teeth under load can be analyzed to see whether they meet the design requirements. If the vast majority of plastic processing enterprises are mainly made in China and do not meet the requirements, they can re design and analyze by changing their materials or other corresponding dimensional parameters until they meet the design requirements

3 conclusion

using CAXA electronic drawing board, it has the function of accurately and quickly drawing the tooth profile curve of gear end face in the parametric national standard gear library and the powerful modeling and design analysis function of UG three-dimensional software, which realizes the rapid and accurate modeling and design analysis of gear, improves the efficiency of product research and development, and provides an effective method for the research and design of similar products. (end)