Gear AT Shape Definition allows you to create a property file (WGP) that defines the topology of a worm and gear (both macro and micro geometry). In current release you can define a tooth profile only by KISSsoft data. Figure 171 shows how to access the tools you need to define your worm and gear geometry.

The Gear AT Shape Definition has following tabs to help you design a gear

 

Review basic geometrical parameters in the General tab (Figure 172). Since the tooth profile is defined already some of values in the fields are not editable.

 

 

The Mass card of the Shape Definition process allows you to define the mass of the gear based either on the Geometry and Material Type or by specific User Input (Figure 174). In the former case the mass, center of mass and inertia tensor is computed later on by the mesher based on FE mesh volume. In the latter case enter all required data in current model units. In either case, inertia data are written to the *.wgp file.

 

 

Gear tooth flank modifications are applied to compensate for manufacturing errors, deformation of the teeth due to load and also for shafts and gear housing deformation thus ensure a proper meshing to achieve more favorable load distribution and reduced transmission error. The ultimate goal is to reduce gear wear and vibrations induced by the gear pair operation, thus help to design durable gearbox fulfilling specified NVH parameters.

 

Gear AT supports following worm and worm gear profile modifications which are all superimposed over the tooth flank:

Profile Modifications

Profile modifications are mostly used to decrease the engagement shock and the involved strain and noise. Types of profile modifications for worm gear supported by Gear AT include tip and root relief, barreling (vertical crowning) and involute slope correction. The modifications can be set individually for left and right tooth flank or symmetrically on both flanks. The layout for profile modification parameters is depicted in Figure 178.

 

 

The use of tip relief will cause less noise during gear meshing. Tip relief is the most economical and most common method. If there are both, tip and root relief applied on one gear, the other gear needs not to be modified. In case the root relief is not applied, the tip relief is applied on both gears of a gear pair.

Both reliefs, and , are defined by a polynomial function of dimensionless involute curve parameters utip and uroot .

 

 

Profile barreling is a convex shape added to the involute curve to prevent hard contact near the tip and root. Barreling is defined as a polynomial function of the dimensionless involute curve parameter u.

 

 

Involute slope is used to compensate for tooth deflection differences between the two meshing gears and to compensate for system deflections that would otherwise result in hard contact near the root or the tip of one of the gears. It defines correction in pressure angle relative to lead line, defined by reference length along the line of contact. The positive correction removes material on tip as shown by Figure 181 for the left flank, while negative correction removes material on root.

 

You can define worm gear manufacturing errors to be taken into account in the contact simulation. Enter Radius Error for every tooth to describe deviations from ideal pitch circle and enter Pitch Error for every tooth to describe deviations from angular pitch, see Figure 182.You can also enter amplitude and phase shift to generate harmonic distribution of error by cosine function or apply generator of random numbers to get random distribution from interval of <-amplitude , + amplitude>. Positive value of Radius Error results in larger tooth radius and positive Pitch Error rotates tooth in counter clock-wise direction according to the right hand rule.