Contrary to what appears to be popular belief, 5-axis CNC gear manufacturing is not limited to milling with end mill, ball mill or CoSIMT (Conical Side Milling Tool — it is the generic form of the Sandvik InvoMill and Gleason UpGear tools.) tools, where throughput is too low to prevent production at any significant level. Straight and spiral bevel gear manufacturing on 5-axis CNC machines using face mill cutters provides essentially the same throughput as conventional gear cutting machines — with added benefits.
In this paper local tooth contact analysis and standard calculation are
used to determine the load capacity for the failure modes pitting,
tooth root breakage, micropitting, and tooth flank fracture; analogies
and differences between both approaches are shown. An example gearset is introduced to show the optimization potential that arises from using a combination of both methods. Difficulties in combining local approaches with standard methods are indicated. The example calculation demonstrates
a valid possibility to optimize the gear design by using local tooth contact analysis while satisfying the requirement of documenting the load carrying capacity by standard calculations.
To achieve the requested quality, most gears today are ground. The usual grinding process includes treating the gear flank but disengaging before reaching the root rounding area. If the gear is premanufactured with a tool without protuberance, then at the position where the grinding tool retracts from the flank a grinding notch in the tooth root area is produced. Such a notch may increase the bending stresses in the root area, thus reducing the strength rating.
The properties of both shot-peened and cold rolled PM gears are analyzed and
compared. To quantify the effect of both manufacturing processes, the tooth root
bending fatigue strength will be evaluated and compared to wrought gears.
Powder metal (PM) gears normally sell due to the lower cost and their relatively high mechanical performance. The reason behind the lower cost is that most of the machining is omitted due to the net-shape forming process. So how net-shape are powder metal gears? In this article some hard-to-find information about the tolerances through the manufacturing steps will be presented.
This paper analyzes the different influences of the deviations between nominal and actual geometry for a first-cut bevel gear. In each section, the customary tolerances are quantified and the possibilities to reduce them are discussed.
Electrification has already started to have a noticeable impact on the global automotive industry. As a result, the drivetrains of hybrid (HEV) and full electric vehicles (EV) are facing many challenges, like increased requirements for NVH in high speed e-Drives and the need for performance improvements to deal with recuperation requirements. Motivated by the positive validation results of surface densified manual transmission gears which are also applicable for dedicated hybrid transmissions (DHTs) like
e-DCTs, GKN engineers have been looking for a more challenging application
for PM gears within those areas.
Highly loaded gears are usually casehardened to fulfill the high demands on
the load-carrying capacity. Several factors, such as material, heat treatment, or macro and micro geometry, can influence the load-carrying capacity. Furthermore, the residual stress condition also significantly
influences load-carrying capacity. The residual stress state results from heat treatment and can be further modified by manufacturing processes post heat treatment, e.g. grinding or shot peening.