The vibration dewatering screen operates continuously in the quartz sand
production line, and the cracking of the screen frame is a serious structural
failure. Cracks often occur at the side plate welds, crossbeam connections, or
near the exciter mounting seat. If not detected in a timely manner, crack
propagation may lead to the scrapping of the entire screening machine. The
problems usually arise in three aspects: weld quality, stress concentration, and
operating load.
Poor weld quality is the primary cause of cracking in screen frames. If there
are defects such as undercutting, porosity, or incomplete penetration during the
welding of the connection welds between the screen frame side plate, crossbeam,
and reinforcement plate, the defects will gradually propagate into cracks under
the action of alternating vibration stress during operation. 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. After
discovering the crack, first use an angle grinder to make a V-shaped groove
along the direction of the crack, clean it thoroughly, and then re weld it.
After welding, polish it flat. When repairing welding, pay attention to
controlling the interlayer temperature to avoid new stress concentration caused
by excessive heat affected zone.
Stress concentration can also lead to cracking of the screen frame. Openings,
cuts, or sudden changes in cross-section on the sieve frame are sensitive areas
for stress concentration. If the transition between the installation seat of the
exciter and the side plate is not smooth, the vibration energy will be
concentrated and transmitted to this area, and cracks will appear over time. It
is recommended to weld reinforcement plates at stress concentration areas, and
polish the edges of the reinforcement plates into a sloping transition to reduce
abrupt changes in cross-section. During daily inspections, it is important to
focus on checking for any abnormal vibrations or noises in these areas.
Long term overload operation will accelerate screen frame fatigue. When the
feeding amount exceeds the rated processing capacity of the screening machine,
the vibration load borne by the screening frame increases, and the metal fatigue
speed accelerates. Check if the operating current exceeds the rated value for a
long time, and adjust the feeding amount appropriately if it exceeds the
standard. In addition, loosening of the foundation bolts of the screen frame can
also cause relative displacement between the screen body and the foundation,
adding additional twisting stress to the screen frame. Check the tightening of
the anchor bolts once a month and tighten them immediately if any looseness is
found.
During daily inspections, check the welding seams and connection parts of the
screen frame once a week, and promptly handle any rust, cracks, 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).