Big gear processing

XNUMX. Big gear product definition:

The diameter of the addendum circle is relatively largergearIt is called the big gear, also called the big gear ring, and the more suitable quenching method is flame quenching.The large gear generally has a relatively large load, and the surface layer of the product is required to have a high hardness, while the inner layer has a moderate hardness and strong stress resistance.

A large gear is a mechanical element with teeth on the rim that can continuously mesh and transmit motion and power. The number of teeth of the gear is an even number, and the opening must be on the tooth groove. The two halves of the gear ring must match. It is used in mining, electric power, forging, metallurgy, cement, Special and general equipment for transportation and other industries.

The large gear transmission structure, when connected with the pinion gear, will speed up its speed, which is very important for certain machines such as mixers that require a certain speed.

XNUMX. Big gear product structure:

There are several structural parts such as tooth groove, gear tooth, normal surface, end surface, tooth root circle, tooth tip circle, index circle and base circle. Each structure has different functions.

XNUMX. Characteristics of large gear casting process:

Large gears have large diameters and thin walls, and are prone to various irregular deformations during hot and cold processing, especially the tooth surface. For this reason, it is necessary to control and master the hot processing deformation laws of ring gears with different diameters to reduce deformation and stabilize cold and heat. Processing technology.

In heavy-duty gear transmissions, there are generally two heat treatment requirements for thin-walled parts with large ring gears, one is quenching and tempering treatment, the other is carburizing and quenching treatment, and the fine cutting and grinding of the teeth are after quenching and tempering. It is not affected by heat treatment deformation.The main form of deformation is cutting deformation.Eliminating cutting stress, reducing machining deformation, and ensuring the quenched and tempered hardness of the tooth surface after cutting is the key to process optimization.

1. When the ring gear diameter is greater than 1000mm and the wall thickness is less than 100mm (depending on the specific structure), due to the large cutting stress of cold processing, turning, gear hobbing and clamping methods during cutting are likely to cause processing deformation and internal stress accumulation. To change the ovality and size after processing, it is necessary to separate the semi-finished turning and the finishing turning, and increase the stabilization process to eliminate the internal stress and then finish to ensure the stability of the product quality.

2. The quenched and tempered gear ring generally adopts medium carbon steel or medium carbon alloy steel.Due to the hardenability of the material, the tooth-grabbing depth of the large-modulus gear ring often exceeds the hardenability depth of the material, which affects the hardness of the tooth surface. Therefore, it is necessary to use the method of rough hobbing or rough shaping to ensure quenching and tempering. The later tooth surface hardness is often used for blanking processing of gears with a modulus ≥12.

XNUMX. Installation of big gear:

The big gear is often made into two parts, which are firmly connected with bolts for easy transportation, installation and replacement.There are three ways to install the big gear on the cylinder: tangential and longitudinal spring plate installation, and rigid connection with the cylinder.

The general choice for assembling the big gear is to fix the ring gear to the cylinder or the flange of the end cover with bolts.Some use a row of bolts to fix the end cover of the grinding head, the flange of the cylinder and the flange of the large ring gear.

XNUMX. The stable operation of the big gear has requirements for the selection of the number of teeth:

In the selection of the number of teeth of the large gear, each tooth system has a smaller value. The main reason is to prevent undercutting during gear hobbing. Therefore, the number of teeth should be as small as possible when selecting the gear. When determining the number of teeth, it should be in accordance with the transmission speed chart. Ratio requirements, the number of teeth of a pair of meshing gears are mutually prime, at least not an integer multiple of each other, so as to avoid serious local tooth wear.So it is very important to determine the transmission ratio.When selecting the number of teeth, it is also necessary to select the relationship between the center distance and the transmission ratio to balance the number of teeth and the modulus.

Sixth, the maintenance and maintenance methods of the big gear:

1. As a part often used in large equipment, regular maintenance of large gears is very important. Careful maintenance and maintenance can avoid unnecessary damage.

2. While installing the gear, you should pay attention to the tightness of the big gear. Too loose or too tight will affect the normal use of the product, and at the same time will aggravate the wear of the product.During use, you should add wheel oil to the gear regularly for lubrication, and check the tightness of the connection.If damage is found, it should be replaced in time.

The big gear of the ball mill is made of high-quality cast steel and gear hobbing. It is durable and has strong bearing capacity. It will be worn to a certain extent during use. Therefore, the material of the big gear is required to have sufficient wear resistance and high hardness.At present, the material of the large gear of the ball mill is usually ZG310~570, but it must be normalized and tempered before processing to reduce the hardness to HB170~200.

Most gears are made by cutting with milling machines and rolling machines.However, in some machines with low precision requirements, cast gears are often used, because cast gears have better wear resistance than milling and hobbing, and the cost is low.The shape and casting process of the cast-tooth large gear can adopt several different modeling methods according to the number of castings.