Rotary kilns are always subjected to a natural down thrust due to their inclination. The down thrust is absorbed by the thrust device – hydraulic or mechanical. The function of the thrust device is to transfer the axial load from the rotary kiln to one or several supports and to maintain the rotary kiln in the axial position. Retrofitting of an existing older model of thrust device or a non-Valmet model to either a mechanic or hydraulic thrust device can be done during a short stop. This makes it possible to install the updated technology during scheduled shutdown and optimize kiln availability without loss of production.
Hydraulic thrust consists of thrust roller, hydraulic cylinder and stand. Thrust roller is installed on axis of rolling bearings. Axis is pressed on post moving along the stand and driven by means of hydraulic cylinder. Bearings lubrication is liquid, circulating lubrication is performed by means of individual lubrication system. It is allowed to use lubrication from centralized lubrication system or grease embedded lubrication. Hydraulic thrust cooling is air and natural.
Large girth gears are used where heavy loads need to be carried in rotary tubular kilns and tube mills. As the dimensions of such gears can be huge, it is often difficult to protect the gear teeth effectively against external media. In contrast to enclosed gears, dirt, abrasive cement and coal dust and salt water may enter the open drives, accelerating wear and corrosion. Additionally, girth gear drives are subject to heavy shock loads. - Adopt special heat treatment technology to improve the structure optimization, the hardness, and enhance the wear-resistant and anti-impacting performances. - Adopts high strength steel materials. - Optimize girth gear based on the operation characteristics of the rotary kiln and ball mill, to ensure the stability of the girth gear during the long time operation and extend its service life. - With advanced equipment and technology, the large ring gear can be fully quenched and tempered, so that the processing of the large ring gear has a good comprehensive mechanical properties, while ensuring high strength while also has good plasticity and toughness
Kiln tyre, also called riding ring, is one important part of rotary kiln. It transmits all gravity of rotary barrel (including refractory bricks, internal devices and raw material, etc.) to supporting roller, and ensures that barrel rotates smoothly on supporting rollers, as well as strengthens radial stiffness of barrel, therefore enough strength, durability and rigidity of rotary tyre are necessary. - High strength and good durability - High quenching hardness - Good wear resistance - Simple structure and easy to adjust and repair
The support rollers are mounted on a massive cast iron or steel base plate which provides the inward horizontal forces on the rollers and distributes the weight of the kiln over the pier. The spacing between the support rollers has to be small enough to prevent large horizontal forces, but large enough to keep the kiln laterally stable. Rollers are designed to subtend 60° at the Rotary kiln tyre center, and this seems always to have been the case.
Our company can provide various types of rollers in line with different roll squeezers. It has been widely applied in grinding industry and is fit for mill. Applicable for the cement processing industry; it can be installed before the ball mill as pre-milling equipment or consist of mixing grinding system with ball mill . The hard surface welding technology can service a roller welding service life to long. -The press roller surface adopts hard alloy stud setting-in structure to increase the life time of the roller sleeve -Multi-layer welding enables long running times without stoppages. -The complete hard face welded surface is used for feed material of normal wear characteristic. Surface repair can be carried out quickly.