Eliminate Belt Sag and Reduce The Escape Of Fugitive Material
While idlers provide a smooth, low-resistance surface for conveyor belts, the gaps between them can cause materials to dislodge the belt from its sealing system. Edge-sealing-support systems mitigate this risk by offering continuous belt support and ensuring a straight belt profile at the edges.
One common type of edge-seal support is the "side rail" cradle. These systems feature low-friction bars positioned alongside the conveyor to support the belt edges. Placing these rails directly under the skirtboard seal helps maintain effective sealing at the belt edge. It's crucial for designers to align these bars precisely with the skirtboard seal and ensure they match the height of the idlers on both the entry and exit sides to prevent friction and material entrapment. When using multiple edge-sealing cradles, including an idler between each cradle is recommended.
The number of edge-seal cradles required depends on various conveyor system factors, such as transfer point length and belt speed. Faster, wider, and heavier-loaded belts may necessitate multiple bars on each side of the cradle for adequate belt edge support. Wider belts might also require central support rolls or additional low-friction bars beneath the middle to distribute weight effectively.
Edge-support slider bars should minimize friction to reduce wear and heat generation. Typically, these bars are constructed from materials like Ultra-High Molecular Weight (UHMW) polyethylene. Some designs utilize "H" or "box" configurations to utilize both top and bottom surfaces efficiently.
For higher-speed conveyor belts exceeding 3.8 meters per second (750 feet per minute), stainless steel support bars are recommended to maintain performance and durability, especially in applications with temperatures above 82 degrees Celsius (180° F).
Local safety regulations often dictate material choices for conveyor components. For underground conveyor belts, antistatic and fire-resistant materials are typically required to comply with safety standards. Other regulatory requirements may further limit material options.
In addition to material considerations, the mounting structure of belt-edge-support systems should be adjustable for easy installation, alignment, and maintenance. It should accommodate various idler configurations and chute wall widths, with provisions for wear adjustments.
Designs should also prevent any contact between the belt and frame or fasteners. For instance, bolts holding the bars should be installed parallel to the belt rather than perpendicular.
While edge-support cradles may slightly increase belt friction and power consumption, these are offset by savings from reduced skirt leakage cleanup, belt damage, and unexpected downtime for maintenance or replacement of idlers.