Compacted-powder opposed twin-helical gears and method

Abstract

A multiply-acting powder metal press is disclosed for making green form double helical gear compacts. The press has inner and outer lower punches, and an upper, outer punch. The upper and lower outer punches have left hand and right hand external helical profiles as chosen to produce a desired helical gear. The punches co-operate with left hand and right hand helical dies carried by the press about the punches. The helical faces require that the dies rotate relative to the punches during operation. A cam and roller mechanism may drive this rotation. The compact forming process commences with an open position in which powder is introduced to a vacant lower die cavity. The upper portions of the press advance downward to close the cavity. All parts of the press except the lower inner, or transfer, punch then move downward at the same speed to transfer powder to the extremities of the cavity. When transfer is complete both lower punches may be stopped, while the upper punches continue to advance. The dies advance at half the speed of the upper punches, rotating partially as they do so. Once the powder reaches its compacted density the upper and lower punches cease motion, but they dies continue to turn, separating themselves and compressed part. Finally the part is ejected and the press returns to the initial condition.