Coal mill is an important equipment for pulverizing coal powder. Coal mill trunnion is a very key component of the mill. It withstands the dynamic loads of the entire mill body and the grinding media, and continues to operate under the action of alternating stress. It is the weak link in the body of the coal mill, and also is difficult to control the manufacturing quality. So how can we produce high-quality coal mill trunnion?

As a professional coal mill trunnion casting manufacturer, CHAENG believes that the molding process and pouring system have an important influence on the quality of the mill trunnion.

1.The basic principle of the coal mill trunnion molding process

The surface with high quality requirements or the main processed surface should be below; the large plane should be placed below; the thick part should be placed on top; the number of sand cores should be minimized; try to use straight parting surfaces.

2.The basic requirements of the coal mill trunnion molding process

Wooden mold: It requires a complete outline, no cracks, no damage, no defects, smooth surface, the size meeting the requirements of the casting process drawings, and frequent size verification. Sand box: The size of the sand box should be determined according to the specifications of the wooden mold. The large and medium sand boxes should be welded with box ribs.

3. Pouring system of coal mill trunnion molding process

According to the technological requirements of the structural characteristics of the casting part, select the appropriate pouring system, usually using top injection type and bottom injection type.

(1) The basic principles of setting the pouring system: the gate and riser are placed in a reasonable position, and the size should not hinder the shrinkage of the casting, and it is convenient for air exhaust, sand dropping and cleaning. The mold size should be minimized, and the molding operation should be simplified, so as to save the amount of molding sand and reduce the labor intensity.

(2) Precautions for the position of the inner sprue: the internal sprue should not be located in important positions of castings; the distance that the metal liquid flows to each part of the cavity should be the shortest; the molten metal should not impact the mold and sand core positively; the metal liquid should be evenly dispersed and fill the cavity quickly; do not face the cold iron and core support in the mold.

4. Riser

(1) The basic principle of the riser setting: Correctly select the shape, size and placement of the riser according to the structure and process requirements of the casting; determine the number of risers reasonably according to the effective feeding range of the riser.

(2) Basic requirements for riser setting: For castings with uneven wall thickness, a riser must be set at each hot joint; the riser should be set as far as possible on or near the top of the casting; when the casting has hot joints at different heights that need to be supplemented, multiple risers can be set, but the supplement areas of each riser must be separated; it is better not to set up the riser in an important or stressful part of the casting; should try to make the sprue through the riser; the riser should not be set at the stress concentration place of the casting as much as possible; the riser is preferably placed on the surface of the casting that needs to be machined.

In the production of the coal mill trunnion, the molding process of the coal mill trunnion should follow the above points to ensure the excellent quality.