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石油、矿山、冶金等大型机械的齿轮具有体积大、载荷重、服役条件差的特点,不少齿轮还要求锻造.通常采用自由锻造的余量大、精度低。辗环(又称环锻)能生产等截面的环形齿轮坯(图1 ),比自由锻造的齿轮坯余量要少,但对不等截面的大齿轮(图2)的锻坯余量减少不多。如采用辗轧工艺,将大齿轮的内型腔和外齿轮缘都辗轧成不等截面的齿轮坯,齿轮坯的材料利用率、精度和经济效益明显提高。 1.辗轧工艺的特点 众所周知,轧制是通过轧辊的旋转将坯料逐渐轧压成型的锻造工艺。辗环是通过辗压轮和芯辊相互作用将坯料辗成等截面环形坯的锻造工艺。如果将辗环的辗压轮和芯辊按需要制成一定的形状,采用辗、轧的复合工艺,制造的齿轮坯与齿轮相近,能达到减少加工余量的目的。
Large gears such as oil, mine and metallurgy have the characteristics of large volume, heavy load and poor service conditions, and many gears also require forging, usually with large margin of free forging and low precision. Rings (also known as ring forging) can produce ring gear blanks of equal cross section (Figure 1), with less allowance for free-forging gear blanks but less allowance for forging blanks for larger gear wheels of unequal cross section (Figure 2) not much. Such as the use of rolling process, the gear inside the cavity and the outer gear rim are rolled into unequal cross-section of the gear blank, gear blanks material utilization, accuracy and economic benefits improved significantly. 1. Characteristics of the rolling process It is well known that rolling is a forging process in which a blank is gradually rolled and formed by the rotation of a roll. Ring rolling is the rolling wheel and the core roller by rolling the billet into a cross-section billet forging process. If the rolling ring rolling wheel and the core roll into a certain shape as needed, the use of rolling, rolling composite process, the gear billet and gear manufacturing are similar to achieve the purpose of reducing the machining allowance.