The Warm Plastic Precision Forming Of Spur Gear

Gears are essential power transmission parts of practical application, which arewidely used in various types of machinery. In recent years, with the rapid development ofautomobile，ship，high-speed rail，wind power and other industries, the performanceof the gears need to be improved, the conventional machining process cannot meet theneeds of practical applications. Precision plastic forming of gears is different fromconventional forming process, it has got gradually attentions and developments because ofits great advantages, not only efficiency and low consumption, but also can make the gearhas a good mechanical properties. As a very important category of gears, the precisionplastic forming of spur gears has also got a great improvement.The geometry of spur gears is very complex. Shortcomings such as heavy load,incomplete filling at the addendum position, short die life and micro cracks at theaddendum position always exist in its precision plastic forming process. For largemodulus spur gears, the situation is worse. The paper presents warm plastic precisionforming process based on the combination forming process of upsetting and extruding forthe study of spur gears, which Z=4. The combination forming process of upsetting andextruding is a new technology that can effectively reduce the forming load, improve thegear tooth root stress state, and reduce the production of micro-cracks. The combinationforming process of upsetting and extruding will be used twice during the new warmplastic precision forming process of spur gears: The first stage is to use the combinationforming process of upsetting and extruding process to forge the blank into a long toothedspur gear blank, the second stage is to use of the combination forming process ofupsetting and extruding process to forge the long toothed spur gear blank into standardspur gear.Use DEFORM-3D to execute numerical simulation analysis of upsetting process,combination forming process of upsetting and extruding process, two-step combinationforming of upsetting and extruding. And the results showed that: during the warmupsetting process, the phenomenon of incomplete filling at the addendum position、heavyload and load increased sharply were obviously; Comparing with upsetting process, the combination forming process of upsetting and extruding can improved the filling at theaddendum position, lower the forming force load, besides, because of the existence of theextruding force, the equivalent stress falls down at addendum position; two-stepcombination forming of upsetting and extruding process of spur gears inherit advantagesof the combination forming process of upsetting and extruding, to make things better, itcan further improved the stress state of the addendum position,to make the spur gears hasa better mechanical properties. The paper has also focused on the effects of differentrelative upsetting and temperature parameters: at the first stage, with the increase ofrelative upsetting, the stress-effective increased firstly, then decreased; during the secondstage, with the increase of relative upsetting, the stress-effective increased firstly, thendecreased, at last it increased again; the relative upsetting has little effect on shaping force;the higher is the initial temperature of the billet, the smaller is the shaping force.