The fracture of the crossbeam during the operation of the vibrating
dewatering screen is a serious structural failure, and cracks often occur at the
weld joint between the crossbeam and the side plate or in the middle of the
crossbeam. When the crossbeam breaks, the overall stiffness of the screen frame
drops sharply, the screen surface collapses, and the entire equipment is forced
to stop. The problems usually arise in three aspects: weld quality, beam
material, and operating load.
The primary reason for fracture is the incorrect selection of beam material
or insufficient wall thickness. Quartz sand has a high density and strong
feeding impact, and the crossbeam is subjected to alternating bending stress for
a long time. When the wall thickness of ordinary carbon steel beams is
insufficient, fatigue cracks appear first at the point of maximum bending moment
in the middle. It is recommended to use Q345B low-alloy steel or wear-resistant
steel to make the crossbeam, with a wall thickness increase of 20% -30% compared
to ordinary carbon steel. The broken crossbeam should not be simply repaired by
welding. It is necessary to calculate the actual load and select new materials
for production.
The weld quality is not up to standard, and the connection cracks first. If
there are defects such as undercutting and incomplete penetration in the weld
seam connecting the crossbeam and side plate, stress will be concentrated here
during operation, and cracks will propagate from the root of the weld seam.
During inspection, it is important to observe whether there is rust seepage on
the surface of the weld seam. Rust water marks are often the starting point of
cracks. When repairing welding, make a V-shaped groove along the direction of
the crack, clean it thoroughly, and weld it layer by layer. After welding,
polish it flat and perform stress relief treatment.
The uneven loading caused by feeding impact will also accelerate the fracture
of the crossbeam. When materials are concentrated on one side of the screen
surface for a long time, the impact load borne by the crossbeam on that side is
much greater than that on the other side, leading to local fatigue acceleration.
Install a fabric board at the feed inlet of the dehydration screen to evenly
spread the material across the entire screen surface. When the feeding amount
exceeds the rated processing capacity, the vibration load borne by the crossbeam
increases, and the feeding amount should be appropriately reduced. In addition,
loosening of the foundation bolts of the screen frame can cause relative
displacement between the screen body and the foundation, adding additional
twisting stress to the crossbeam. The fastening situation should be checked once
a month.
During daily inspections, check the welds and middle of the crossbeam once a
week for cracks, and promptly address any rust or abnormal vibrations found.
Encountering problems during equipment operation, welcome to contact the
technical team of Shandong Heavy Industry for communication: Manager Zhang
13583776655 (same as WeChat).