Factors affecting crushing capacity

hammer mill screen

Impact of crushed screens

1、Hole arrangement

Sieve holes are arranged in the form of horizontal and longitudinal rows of holes, both equilateral triangles. The sieves in the horizontal row of holes are the direction in which the material runs perpendicular to one side of the triangle. 

A vertical row of holes is the direction of travel of the material parallel to one side of the triangle. When choosing the large aperture screen (aperture >Φ4.0), the way of row hole has no effect on the production capacity, because of high production capacity, the material impact on the screen is very large, so it is easy to choose vertical row hole screen, the vertical interval between the two holes just to form strong support for the screen. 

When using small aperture sieves (aperture ≤Φ4.0), the overall reduction in material capacity also reduces the impact force on the sieves. Therefore, horizontal rows of holes with no material incidence blind zone should be used. It has been proven that when using small aperture sieves, with the same aperture rate and the same thickness, the capacity of the sieves with transverse apertures is 5%-10% higher than the sieves with longitudinal apertures.

crusher screen

2、Screen opening rate

When selecting sieves, priority is given to meeting the product particle size requirements, and then to selecting sieves with the highest possible density and large apertures according to the strength of the sieves. The relationship between sieve diameter and crushed particle size is roughly: the strength of the finished product ≈ (1/4-1∕3) sieve hole diameter. We have achieved a 45% opening rate of Φ2.0 sieves. 

The problem is that while the opening rate of the sieve has increased and the efficiency of the powder output has increased, the impact value of the sieve has decreased. The cleaning of raw materials can not be done absolutely clean, some of the larger sand and gravel is very easy to break the screen, producing back to the machine material, but increased production costs. 

After several tests, the aperture of the dorsal side of the screen was increased while ensuring the original high aperture rate of 42%. A ring-mold-like guide hole is formed. Use so that the burr face is facing the rotor. Because in the direction of the material flow, the material passes through the sieve hole when colliding with the angle of the burr surface, can play a frictional crushing effect, but also can increase the screening capacity. At this time, the horn increases the material feeding inclination, just like the role of the ring mold guide hole, crushing efficiency is significantly improved than the original screen

3、Screen installation

When the screen is installed on the front side of the side of the installation of the material particle size requirements of the aperture of the screen, the back side of the installation of the large one of the screen, can meet the particle size requirements of the material and improve the efficiency of crushing. 

When the sieve is punched, microscopic indentations are formed on the front side, the sieve hole circumference becomes smooth and dull, and the cutting ratio decreases. If the sieve is loaded with anti-burr towards the outside, it will also cause the burrs to hang material to block the sieve hole, affecting the efficiency of powder output.

screen

4、Screen failure

Most of the breakage of the sieve is to have entered the hammer mill chamber of foreign objects break, small holes after welding repair can be followed by reuse, when there are multiple holes, the repair of the effective sieve screen area greatly reduced, and then repair the use of the loss of use, only to replace the new sieve. When a comet pit appears in the sieve hole, the cutting ratio drops the powder slower, even if no foreign object strikes break, the sieve should be replaced, if used again, the wasted electricity consumption far exceeds the residual value of the sieve.

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