After the cogging is established successfully, and the skeleton is bent after all the teeth are made by the translation and the array, the gear modeling is completed. Thus, one tooth groove only needs to be a straight line and a rectangular cross section for the scanning track and the width is controlled. The cross-section scanning feature can be built, and the method has been simplified, so that the skeleton bending scheme no longer resembles the spur gear modeling/chicken ribs 0; and the gears with more complicated tooth shapes are more efficient and simplified, and more practical. significance.
The modeling scheme of direct-cutting and cutting the tooth groove by variable cross-section scanning is as follows: a) stretching the flat base member; b) drawing the straight line, paying attention to the tooth height and thus controlling, so the scanning starting end position should be controlled; c) variable cross-section scanning cutting Shear groove
The implementation process below takes a fixed-size parameter gear as an example to demonstrate the whole process of modeling according to this scheme. The main parameters of the gear are: modulus m=3, number of teeth z=40, pressure angle A0=20b. The remaining parameters are determined. The stretched flat base member is selected from the FRONT reference plane as a sketching surface, and the grass is drawn with the contour of the gear shaft. Note that in the future, the position of the plane profile bent to the top of the tooth should be at the correct distance from the origin of the coordinate to ensure that the center of the gear after the bending is the origin; the tension is established to establish the flat base member, and the tensile length is Pmz.
Sketching to create the scanning track sketching surface as before, set the base tooth top plane as the reference, sketch the straight line so that one end is aligned with it, the length is the gear full tooth height ie: mz(1-cos20b)/2 here is not the tooth The height is 2.25 m (m) of the gear modulus) because the radius of the base circle is larger than the radius of the root circle calculated according to the relationship, and there is no involute in the base circle. The above two features establish the results.
Copy, the array is made to be cogging along the long direction of the base, and then the signature array will be duplicated. Skeleton bending gear frame bending command, select the flat base member, the TOP base surface is the sketch surface, the origin is the center circle drawing <120 circle, and the coordinate is placed on the intersection of the circle and the FRONT surface. Exit the sketch selection panel end face as the stop plane and bend the final model.
Promote the application direction This solution is not only suitable for spur gear modeling, but also for helical gears, which is more time-saving and efficient. It is conceivable that if the end face modulus mt of the helical gear is equal to m in the aforementioned gear, and the remaining parameters are unchanged, then all we need to change is to change the rectangular section of the variable section scanning into a parallelogram: its long side and the middle FRONT face clamp The angle is the helix angle. The traditional method or the 5-bone scheme is much more complicated.
For more complex parts such as bevel gears and worm gears, the above scheme is used to model the inevitable effect. However, due to space limitations, it will not be repeated here. In particular, the success of this paper is not related to the relationship used, that is, a series of equations constructed with radius increments as parameter variables, and only pre-formed on the flat base before the skeleton is bent, / radial Scanning 0 is only possible.
Conclusion The variable cross-section scanning is incorporated into the gear skeleton bending modeling scheme, and satisfactory efficiency is obtained. Moreover, this improvement scheme can be easily applied to the modeling of other gear parts, and the performance of its efficient modeling is better, which is recommended.
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