Mitigating Impact Damage: Strategies and Technologies for Enhancing Conveyor System Resilience
Transfer points often cause material leakage and damage to conveyor systems. One of the primary causes is the impact of heavy objects or materials with sharp edges.
These significant impacts often occur due to items falling long distances through transfer chutes. Alternatively, they can result from the size and characteristics of the materials themselves, such as large lumps, boulders, timber, or scrap metal. In both scenarios, these impacts can severely damage components like idlers and sealing strips. They can also cause the belt to ripple, destabilizing its path and leading to increased material spillage. Over time, these impacts can harm the belt's top cover and carcass, causing further issues downstream. To mitigate these problems, engineers employ various strategies in loading zones, such as engineered chutes, rock boxes, or designs that separate fines from larger lumps during loading.
Despite these efforts, it's often impossible to eliminate the risk of impact damage in transfer belts. Therefore, designers must incorporate systems that absorb the energy from falling materials at the loading zone.
For instance, striking a belt laid directly on concrete with an ax or hammer typically damages or splits the belt. However, if the belt is placed on a layer of foam, the damage is significantly reduced. In conveyor systems, impact cradles serve a similar function to foam by absorbing the shock of materials hitting the belt during loading.
Impact cradles are positioned directly beneath the material-drop zone to absorb the shock. Similar to edge-sealing supports, they use low-friction bars under the belt to facilitate movement. However, impact cradles also incorporate elastomeric materials with sponge-like layers to absorb the impact energy.
There are two main configurations for impact cradles: long bars that run parallel to the belt's direction of travel, and shorter modular bars arranged perpendicular to the movement direction, resembling a saddle. Typically, long bars are about 1.2 meters (4 feet) in length, while shorter bars are around 300 millimeters (12 inches) wide. The number of bars required depends on the conveyor belt's width, while the number of cradles or saddles is determined by the length of the impact zone, not necessarily the transfer point.
Some designs integrate separate layers for reducing friction and absorbing impact, which are permanently attached. Others require these layers to be installed separately. Additionally, impact cradles are available in a track-mounted design, which simplifies bar replacement when necessary.
The ability of the belt to absorb impact, combined with an impact cradle, is limited by its capacity to resist crushing energy. Conveyor systems facing strong impacts or damaging materials can enhance the impact cradle's effectiveness by mounting it on further shock-absorbing structures, such as springs or air cushions. However, these enhancements increase the belt's flexibility, making edge sealing more challenging.