Method and apparatus for forging gear teeth
a gear tooth and gear technology, applied in gearing, hoisting equipment, transportation and packaging, etc., can solve the problems of large flash, inability to achieve commercially acceptable die life, and inability to achieve high-precision net shap
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first embodiment
[0080]FIG. 5a depicts a forged gear tooth 205 and is based on the machine cut gear tooth 5 shown in FIG. 4a. The outline of the “parent” machine cut gear tooth 5 is represented by the chain dotted lines 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 230, 232 and the solid lines 226, the latter representing the loci of the lowest points in root radii 214.
[0081] For the purposes of this document, the length 270 of gear tooth 205 is measured in the curvilinear direction along the bottom of root radius 214 (ie: along line 226, see FIG. 5c).
[0082] Curvilinear direction t lies in reference surface S of FIG. 1. Surface S is a curved vertical surface and intersects gear 1 in line P-P which is coincident with lines 26 in the roots of gear teeth 5 (see also FIG. 2). Direction z is at right angles to curvilinear direction t and is parallel to the root 14 of gear tooth 5 (see FIG. 1). As shown in FIG. 3, direction z is in general not parallel to the axis Z of gear 1.
[0083] The corresp...
second embodiment
[0096]FIG. 5g depicts a second embodiment where tooth tip 234 has a convex crowned portion 260 extending the full length of tip 234 along curvilinear direction t.
[0097] In the context of this specification, crowning is defined as the convex upward profile of tooth tip 234 when viewed in direction C of FIG. 5a. To facilitate comparison FIG. 5g and not yet discussed FIGS. 6k, 7d and 7e are shown together on the same page.
[0098]FIG. 6a shows a third embodiment of a forged tooth 305 which is a variation on forged tooth 205 of the first embodiment. In this third embodiment tooth tip 334 has been allowed to come into contact with the bottom of tooth die cavity 337 over tip contact area 370. In this case, the pressure acting on tip contact area 370 at the end of the forging process will be non-zero, and the corresponding die pressures and stresses experienced in forming forged tooth 305 will be higher than those experienced in forming forged tooth 205. Whether the die cavity fills uniform...
fourth embodiment
[0106]FIG. 6g shows a forged tooth 705 in which tooth tip 734 is allowed to extend outside the envelope of the parent machine cut gear tooth tip 11, here indicated by tooth tip 711. This is because the conical (approximately flat) surface of tooth tip 11 of parent machine cut tooth 5 may be replaced, when designing the corresponding tooth die cavity, by curved surface 738 that extends outside the envelope of parent machine cut tooth 5 provided curved surface 738 does not interfere with its not shown conjugate meshing gear. If curved surface 738 causes interference, then a portion 749 of tooth tip 734 may be removed by machining after forging. Although this introduces an extra operation and wastes material, this may be preferable if one is unable to achieve acceptable die life using small corner radii 740 and 741 in an endeavour to keep the forged tooth form within the envelope of the parent machine cut tooth 5.
[0107] The shape of curved surface 738 is similar to that of curved surfa...
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Abstract
Description
Claims
Application Information
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