Worm Gear Theory
The Worm Gear model is defined as a rigid body. A finite stiffness for the gear mesh (or gear tooth) can be specified in the Worm and Wheel node while connecting to a wheel. Similar to the rigid domain, the worm gear is a material model, which is mutually exclusive to all other material models. The only material property needed is the mass density.
Figure 3-7: Sketch of a worm gear, showing the tooth cross-section and various parameters such as center of rotation, gear axis, pitch radius, pressure angle, and lead angle.
For details about the theory of a rigid body, see the Rigid Domain Material Model section in the Structural Mechanics Module User’s Guide.
The following section is an addition to the Spur Gear Theory, section some of which is also applicable for the worm gear.
Connection with other gears
A worm gear can be connected to a Helical Gear, or Spur Gear through the Worm and Wheel node. A single gear can be connected to one or more gears.
Gear properties
The following quantities are required on define a worm gear.
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Number of starts (n)
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Pitch diameter (dp)
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Pressure angle (α)
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Lead angle (φ)
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Handedness: Right or left
The helix angle for the right handed worm gear is defined as:
The helix angle for the left handed worm gear is defined as:
The transverse module of the gear is defined as:
The normal module of the gear is defined as: