Why are the teeth of many P/M gears oblique?
Dec 27, 2022
Why are the teeth of many P/M gears oblique?
Powder metallurgy gear is a kind of powder metallurgy part widely used in various automobile engines. Through one-time forming and finishing process, it does not need other post-treatment processes, and can fully meet the requirements of dimensional accuracy, especially the tooth profile accuracy. Therefore, compared with the traditional machining method, the material input and manufacturing are greatly reduced. It is a typical product reflecting the characteristics of powder metallurgy.
Powder metallurgy gear
However, many people will have a doubt, why are many P/M gear teeth oblique? Here, three reasons are summarized by Zhongwei Precision Editor:
1. Compared with the flat gear, the position of the shaft is more free: for example, the differential transmission shaft with bevel gear does not have to be on the same horizontal plane with the rear axle, but it is necessary if it is a flat gear.
2. Noise reduction: the noise of helical gear is less than that of flat gear at the same speed: the reason is that the surface of helical gear is in point contact first, then transited to surface contact, and then to point contact. The flat gear is in line to surface contact, and the transition of helical gear is smoother. Therefore, the noise generated by the sudden change of contact is much smaller than that of flat teeth.
3. The production is convenient. The hobbing machine can produce various numbers of P/M gear teeth on the cylindrical blank. A group of helical teeth with the same surface width and different width of P/M gear components can be cut into different face widths according to customer needs in the later stage.
Commonly used powder metallurgy gear tooth profile: involute tooth profile and circular arc tooth profile. See GB/T1356-1988 for basic involute tooth profile. The characteristics of involute gear magic meshing transmission: 1. The transmission ratio is constant; 2. The change of center distance does not affect the transmission ratio; 3. The meshing line is a straight line passing through the node.
