AGMA 05FTM14-2005 pdf free.Determining the Shaper Cut Helical Gear Fillet Profile.
The shaper tool discussed in this paper can be divided into three zones (Fig. 8):
1) Zone 1, is the portion of cutter profile that coincides with the outside diameter of the shaper tool. It starts from the outside diameter of the cutter on the y-axis, and ends at the end tangent point, E(1. The tool profile in this zone generates the root circle of the gear. If the shaper tool has a full tip radius, Zone 1 reduces to a single point on the outside diameter of the tool.
2) Zone 2, is the elliptical tool tip starting at E() and ends where the tool tip joins the main shaper tool profile (Zone 3).
3) Zone 3, is the main cutter profile that generates involute profile on the semi-finished gear.
The shaper tool generated trochoid can be determined by calculating the conjugate points of tool tip in Zone 2. Begin the calculation at E0 (Fig.
8), and continue in small increments towards P0. The conjugate point of P0 will usually penetrate deepest from the surface of the involute profile (Fig.
9). Continue the calculation procedure until the trochoid intersects the involute tooth profile. Additional trochoid points can be calculated if desired.
7 Using shaper tool algorithm to calculate fillet profile of a hobbed gear
The tooth profile of a shaper tool with infinite number of teeth will approach a rack. Naturally, if a shaper tool algorithm could handle an infinite number of tool teeth, a hobbed trochoid could be accurately approximated. Unfortunately, the shaper tool algorithm presented in this paper does not allow infinite number of tool teeth. A shaper tool with a finitely large number of teeth is permitted.
To investigate the feasibility of approximating a hobbed trochoid with the shaper algorithm using a shaper tool with a large number of teeth， a numerical example (Ex. 3.1.5 of AGMA 918-A93 [8]) was calculated. The number of shaper tool teeth used were 100，1000, and 10000. Table 1 compares the distances between the trochoid curves generated with the shaper cutters and the one generated with a hob. The form diameters or the start of involute (SOI) (to be discussed in 8.1) based on shaper tool were also compared to that generated with a hob. Fig. 10 showed the trochoid curves superimposed for a visual comparison.
Table 1 showed that the maximum distance between the trochoid curves generated with a 100 tooth shaper cutter and the hob to be 0.001085″. For a 10000 tooth shaper cutter, the difference reduced to merely 0.000011″.
The difference between the shaper generated and the hobbed SOl’s followed a similar trend. For the 100 tooth shaper cutter, the difference was 0.010209″ and for 10000 tooth shaper cutter, 0.0001 17″.The trochoid curves plotted in Fig. 10 showed that the shaper generated trochoid converging to that of the hobbed one when the number of teeth in shaper tool was large (e.g. 10000).AGMA 05FTM14 pdf free download.