Gravity casting technology of Babbitt bearing

Sliding bearing plays a supporting role in the operation of the motor, bears the radial load and ensures the high-speed operation of the steam turbine engine. It is the key component of the steam turbine engine. The bearing bush is the main component of the bearing (see Figure 1). The bearing bush is a bimetallic workpiece, which is composed of Babbitt alloy inner layer and low-carbon alloy steel bush body. The structure is shown in Figure 2. Babbitt alloy (also known as tungsten gold) is combined with the bush body by gravity casting. The strength of the joint surface directly affects the operation quality of the unit. Therefore, ensuring the strength of the joint surface is the most critical quality requirement for bearing bush production.

Gravity casting is one of the common methods for bearing bush preparation. It is to pour molten Babbitt alloy onto the surface of low-carbon alloy steel substrate that has been tinned, and form bimetallic structure after cooling. Low carbon alloy steel matrix mainly adopts zg230-450 steel. Bearing Babbitt alloy is a specific material used to manufacture sliding bearing bush. There are many kinds of bearing materials, including tin antimony bearing alloy, lead antimony bearing alloy, copper base bearing alloy, aluminum base bearing alloy and zinc base bearing alloy. Among them, tin antimony bearing alloy has the longest history and the most common application. In the actual production of Electromechanical industry, ZSnSb11Cu6 tin based Babbitt alloy is mainly used.

The application of vertical sequential water cooling process has greatly improved the qualification rate of bearing bush gravity casting, from 68% to 75%. At the same time, it greatly saves the economic loss caused by bearing bush shelling repair, and has great popularization value.