When designing the pin gear, the tip circle should not be enlarged in principle. It should be avoided that the tooth tip circle is outside the intersection of the tooth profile curve. On the other hand, when designing the pin gear, it should be considered to ensure the smoothness of the transmission, so that the overlap coefficient of the mesh is greater than 1.0, that is, the front pair of gear teeth and the pin can not be disengaged before entering the meshing. The first pair of gear teeth and the pin must be disengaged after the latter pair of gear teeth and the pin enter the engagement for a period of time. Therefore, the gear teeth should not be too short, which requires the tip circle not to be too small. The magnitude of the overlap factor is related to the diameter of the addendum circle, so the overlap factor is determined when the tip circle diameter is determined.
The tooth profile is an envelope, and it is difficult to determine the starting point and the separation point of the mesh in one step on the envelope. In order to facilitate the trimming of the tooth profile curve, a dynamic design software for the pin gear transmission is designed, and the software interface is as shown.
Pin gear transmission simulation software interface Changzhou Institute of Technology in the middle, the pin wheel rotates counterclockwise, the drive pin gear rotates clockwise, the pin wheel is the drive wheel; it can also be understood that the pin gear is the drive wheel, the pin gear rotates counterclockwise, The drive pin wheel rotates clockwise. Inside the software there are program modules that specifically calculate the diameter of the tip circle and the overlap factor of the drive. As long as the operator selects the meshing mode and sets the initial structural parameters in turn, the software immediately displays the tooth shape corresponding to the parameter setting, and the value of the tip circle diameter and the transmission overlap coefficient. If the displayed value of the tip circle diameter and the transmission overlap factor do not meet the design requirements, the initial structural parameters and the tip adjustment amount can be adjusted, and the pin gear tooth shape, and the value of the tip circle diameter and the transmission overlap coefficient are displayed again. Until the value meets the design requirements. The amount of crest adjustment in the interface is a parameter used by the program. The operator interacts with the software by changing the value of the crest adjustment amount to quickly determine the tip circle diameter and the meshing overlap factor. The value of the crown adjustment is negative, the effect is to shorten the tooth length, reduce the diameter of the tip circle and the meshing overlap coefficient; the value of the crown adjustment is positive, the effect is to increase the tooth length, increase the diameter of the tip circle and Engage the overlap factor.
The three-dimensional model of the pin gear example 4 The application parameters obtained by the simulation example are the number of teeth of the pin gear, the pitch circle diameter, the tip circle diameter, the cogging arc radius, and the pin wheel pitch diameter and the pin diameter. Based on these parameters and the pin gear profile equation, a three-dimensional model of the pin gear can be easily established in the three-dimensional mechanical CAD/CAM software. It is a three-dimensional model of the external meshing pin gear established in Pro/ENGINEER. The model has a number of teeth of 8, a pitch circle diameter of 320 mm, a tip circle diameter of 437 mm, a bore diameter of 100 mm, a cogging arc radius of 25.5 mm, a paired pin wheel diameter of 480 mm, and a pin diameter of 50 mm. In 3D modeling, the excessive arc radius of the cogging and flank curve is 20mm.
Conclusion The pin gear profile equation established in this paper has been verified by simulation software to prove its correctness. The pin gear tooth curve equation covers all three kinds of transmission modes of external meshing, internal meshing and rack and pinion meshing, which lays a foundation for the digital design and manufacture of pin gears. The dynamic design of the pin gear prepares data for 3D modeling, which is easy to operate and has high work efficiency. With this software, the dynamic design of the pin gear can be completed in just a few minutes, and all the data needed for 3D modeling of the pin gear can be obtained.
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