Core considerations for blade design of spiral sand washing machine
The blade is the core component of the spiral sand washing machine for
material mixing, cleaning, and conveying. Its design rationality directly
determines the equipment cleanliness, fine sand recovery rate, operational
stability, and service life. Considering the high hardness of quartz sand, large
fluctuations in mud content, and continuous heavy loading of large-scale
production lines, blade design needs to comprehensively consider multiple
factors such as material adaptation, structural parameters, material selection,
operational efficiency, and installation and maintenance to ensure compatibility
with actual production needs.
1、 Material characteristic adaptation factors
The material characteristics are the core basis for blade design, and it is
necessary to focus on matching the particle size composition, mud content, and
hardness of quartz sand to avoid poor sand washing effect or rapid blade wear
due to insufficient adaptability.
For particle size composition, when dealing with coarse sand (20-40 mesh), it
is necessary to enhance the stirring impact force of the blades. A larger
curvature radius (150-200mm) and a wider blade width (80-100mm) can be used to
ensure that the mud powder is fully peeled off; When dealing with fine sand
(40-70 mesh), it is necessary to weaken the mixing intensity to reduce the loss
of fine sand. A smaller curvature radius (200-250mm) and relatively narrower
blades (60-80mm) should be selected, while optimizing the pitch to reduce the
propulsion speed. In terms of mud content, when the feed mud content exceeds 8%,
it is necessary to extend the residence time of the material in the tank, which
can be achieved by reducing the blade installation angle (12-13 °) and
increasing the blade distribution; When the mud content is ≤ 5%, the
installation angle (14-15 °) can be increased to improve the conveying
efficiency. In response to the characteristics of quartz sand with a Mohs
hardness of 7-8 levels, the blades need to have high-strength wear resistance to
avoid short-term wear that may cause a decrease in stirring force.
2、 Structural parameter optimization factors
The structural parameters such as blade shape, pitch, installation angle, and
distribution directly affect the sand water mixing effect, material retention
time, and conveying efficiency, and require precise design and matching.
In terms of form design, it is recommended to adopt a "curved gradient"
structure, with large blade curvature and steep cutting angle at the feeding
end, which can enhance the impact stirring of materials and quickly peel off
surface mud powder; The curvature of the middle cleaning section is moderate to
ensure sufficient mixing and friction of sand and water; The discharge end has a
gentle curvature, reducing water flow disturbance and minimizing the loss of
fine sand carried by it. The pitch needs to be designed in sections, with a feed
section pitch of 280-300mm, to improve material propulsion speed and avoid
material accumulation; The middle section is 250-280mm, ensuring a material
retention time of 40-60s to achieve thorough cleaning; The discharge section is
220-250mm, which assists in the sedimentation and separation of sand and water.
The installation angle needs to be dynamically adjusted according to the
processing capacity. Large equipment (daily processing capacity ≥ 3000t) is
usually controlled at 12-15 °. A too small angle can easily cause water
accumulation and material retention in the tank, while a too large angle can
result in insufficient cleaning. The distribution method adopts "staggered
distribution", with adjacent blades staggered by 15-20 ° to avoid mixing dead
corners and ensure uniform cleaning of materials in the tank.
3、 Material selection and adaptation factors
The material directly determines the service life of the blade, and it is
necessary to combine the wear characteristics of quartz sand to select materials
with high strength, high wear resistance, and corrosion resistance to reduce
operation and maintenance costs.
Under normal working conditions, high chromium alloy materials are preferred,
with a wear-resistant layer (thickness ≥ 5mm) welded on the surface. The
hardness can reach HRC60 or above, and the wear resistance is 3-5 times that of
ordinary steel plates. The service life can be extended to over 8000 hours; For
harsh working conditions with high mud content and impurities, bimetallic
composite materials can be used, with a base material of 40Cr to ensure strength
and a working layer of tungsten carbide overlay welding to further enhance wear
resistance. At the same time, it is necessary to consider the corrosive effect
of water flow during the sand washing process, and the material should have a
certain degree of rust resistance to avoid long-term immersion that may cause
blade cracking. It is necessary to avoid using ordinary steel plates or
low-alloy materials, which have poor wear resistance and are prone to short-term
wear and deformation, affecting the normal operation of the equipment.
4、 Operational efficiency and stability factors
The blade design should take into account both sand washing efficiency and
operational stability, to avoid excessive energy consumption, equipment
vibration, or frequent malfunctions caused by unreasonable structure.
In terms of speed matching, the blade structure needs to be designed in
conjunction with the spiral speed. When the conventional speed is 22-28r/min,
the blade pitch and speed need to meet the stable product of "pitch x speed" at
550-650mm · r/min to ensure that the material propulsion and cleaning rhythm are
compatible; When the speed is too high, it is necessary to optimize the
streamlined design of the blades to reduce water flow resistance and equipment
vibration. The weight and balance of the blades also need to be strictly
controlled. The weight deviation of a single set of blades should be ≤ 50g.
After installation, dynamic balance testing should be carried out to ensure that
the amplitude of the shaft rotation is ≤ 1.5mm/s, to avoid shaft wear and
bearing damage caused by imbalance. In addition, the gap between the blades and
the inner wall of the sand washing tank should be controlled at 30-50mm. If the
gap is too small, friction may occur, and if it is too large, it may cause
material residue and affect the cleaning effect.
5、 Factors affecting installation and maintenance convenience
Blade design needs to consider the convenience of subsequent installation,
debugging, and maintenance, in order to reduce equipment downtime and
maintenance difficulties.
The recommended installation method is to use a dual structure of
"welding+bolt reinforcement". After welding the blades and spiral shaft,
high-strength stainless steel bolts are used to tighten them, which not only
ensures the firmness of the connection, but also facilitates subsequent local
replacement. The blade needs to reserve a calibration reference surface, which
can be quickly calibrated using a laser collimator during installation to ensure
that the end face runout deviation of the blade is ≤ 0.2mm/m and the parallelism
deviation is ≤ 0.5mm/m. In terms of maintenance, the parts of the blades that
are prone to wear should be designed as replaceable modules, and the replacement
of worn blades can be completed without disassembling the screw shaft as a
whole; At the same time, the surface of the blade should avoid complex
structures to facilitate daily cleaning of attached mud powder and impurities,
reducing maintenance workload.
In summary, the blade design of the spiral sand washing machine needs to be
centered on material characteristics, taking into account factors such as
structural parameters, material selection, operational efficiency, and
installation and maintenance. Through precise matching, a balance between sand
washing effect, operational stability, and economy can be achieved. In actual
design, targeted optimization should be carried out based on equipment model,
processing capacity, and on-site working conditions to ensure maximum
performance of the blades.