Simply put, the indexing gearbox is a machine assembled with the cam and the output turret. It does not require other parts and can provide multi-station intermittent, swing and continuous motion under the action of the driving source. The indexing gearbox can also be literally understood as a mechanism or software that divides an article into several segments or pieces, but the indexing gearbox mentioned here is a stop on the output circle under the action of the cam mechanism And rotating movement to realize the mechanical action required for processing. Among them, the principle of the indexing gear box is also very simple. The cam rollers make linear contact with the tapered support ribs of the cam on their corresponding inclined surfaces. Since the cam structure of the indexing gearbox is composed of countless curves with a complex curved surface structure, it is called the profile processing of a globular cam in cam processing, and its processing technology is slightly cumbersome compared to other transmission cams.
Speaking of the process, we need to talk about the operating principle of the indexing gearbox. When the input shaft rotates, the cam roller rotates the output turret according to the given displacement curve, and at the same time rolls along the slope of the rib. In the area where the ribs are balanced with the end face of the cam, that is, in the static range, the roller is connected to its shaft, but the output turret itself does not rotate. The taper support rib is usually in contact with two or three cam rollers so that the rotation of the input shaft can be evenly transmitted to the output shaft. If there is unevenness between the cam surface of the taper support rib and the cam roller, the indexing gear box will be damaged. By adjusting the distance between the shafts, the phenomenon of unsmooth rotation can be eliminated. The preload can be adjusted to approach the elastic area of the cam roller and the cam, thereby enhancing the rigidity of the indexing gearbox. Its structure and function are the best performance of the combination of indexing cam and cam roller, enabling high-speed operation. From the perspective of the entire mechanical movement, the transmission cam plays a vital role in the indexing gearbox.
The machining process of the indexing gearbox cam is simple. The milling forming-carburizing heat treatment-rough grinding-fine grinding-inspection, such a process is generally foreign for the more mature process of cam processing, while for domestic, the arc surface The design and processing of cams are still in the stage of exploration and experimentation. The commonly used processing techniques are rough milling forming-fine milling-nitriding heat treatment-running-in adjustment-inspection. From the perspective of the two technological processes, in the two stages of heat treatment and fine grinding, there is a slight difference between domestic and foreign countries, because there are big differences between domestic and foreign countries in the heat treatment process of indexing gearboxes, and most foreign countries adopt medium Low-carbon alloy steel adopts carburizing treatment technology. Its advantage is that the carburized layer is thicker, generally 0.5-2mm. The purpose of carburizing treatment is to ensure that the carburized layer is evenly distributed along the contour of the steel with complex shapes. After quenching and low-temperature tempering, the hardness of the surface is strengthened, combined with the internal flexibility of medium and low carbon, so that the indexing gearbox cam has strong wear resistance and impact resistance, but the cam deformation is relatively large during high temperature carburization. , It must be trimmed after finishing grinding to ensure the accuracy of the cam profile. Most of the materials used in the domestic nitriding process are high-grade nitrided alloy steel, and after quenching and tempering, it can reach HB220-280. After the nitriding treatment, the surface of the base part has high hardness and wear resistance. The advantage is that the deformation of the workpiece is very small, but the surface depth of the nitride layer can reach 0.7mm. Because the surface is too thin, it will be inferior to the carburizing process under impact and heavy load, which is also the reason for the shorter cam life.
The heat treatment process of the indexing gearbox cam is quite different. So, why the domestic cam does not adopt the carburizing technology? The reason here is the difference between domestic and foreign processing and grinding equipment. At present, there are very few professional grinding in China. Equipment, there is no way to correct the deformation of the cam after the carburizing process. This is also the drawback of the domestic machining of the indexing gearbox cam, and the difference in the price of the cam. Technological changes and industrial development are a long-term topic. It is believed that in the near future, China will also be able to achieve considerable development in the machinery industry and technological research and development.
The processing technology of the indexing gearbox is closely related to the quality, effect, and life of the product. When selecting the product, the processing technology is also the main condition for product quality reference. It is hoped that the above analysis will be helpful to the demanding manufacturers in the selection of indexing gearboxes.
