Herringbone gear is a cylindrical gear with right-handed teeth on a certain part of the tooth width, and left-handed teeth on the other part of the tooth width. Herringbone gear is translated as double-helical gear in English. Herringbone gears have the advantages of high carrying capacity, smooth transmission and small axial load, and are widely used in the transmission system of heavy machinery. The two sides of the herringbone gear shaft can be manufactured separately according to needs, and then combined; or although the two sides are made into one body, but the necessary overtravel grooves are left between the effective tooth surfaces on both sides; or the gear shaping is adopted Method, but also need to disconnect the tooth surfaces on both sides. Compared with the processing of ordinary gears, the processing technology of herringbone teeth is more complicated and difficult, and the commonly used processing method is generally to use finger gear milling cutters.

First, the processing points of herringbone gears

The intersection of the left and right spirals of the herringbone gear can form many planes. Usually, the plane symmetrical to the end face of the gear is called the herringbone center plane. Limited by the structure of the reducer and in order to meet the conditions of normal gear meshing and transmission, the herringbone gear shaft must be placed in its position during assembly, and the position error of the herringbone center plane must be controlled within the allowable range of the assembly adjustment.

2. Process analysis

From the assembly points of herringbone gears, it can be seen that the greatest difficulty in processing herringbone gears is to control the position of the herringbone center plane. This article mainly discusses the hobbing processing methods of herringbone gears by using the generative method.

1. Processing ideas

In this paper, the main method to control the position tolerance of the herringbone center plane is to first process the tooth profile on one side and then draw the tooth tip spiral line to the outer circle of the other side tooth blank by scribing to minimize the deflection of the herringbone center plane position. The error can be processed according to the following processing route: hobbing one side gear → fitter marking → hobbing the other side gear, the specific method is as follows:

2. Selection of equipment and tools

Because the processing equipment is subject to certain restrictions, the processing equipment used in this article is the Y320 type gear hobbing machine manufactured by Wuhan Heavy Machine Tool Factory. The hob uses m10, a20°, γ4°40' right-handed single head according to the drawing requirements. High-speed steel standard hob for processing.