Technical characteristics of the grinding rollers
Technical characteristics of the grinding rollers
The grinding roller is made of cast iron alloy material, and the surface requires a large hardness.
There are different specifications such as 600mm, 800mm, 900mm, 1000mm, etc. There are two kinds of grinding rolls: light rolls and toothed rolls. The surface of the light roller is not serrated and is polished to a smooth surface, while the toothed roller is serrated or drawn on the surface of the grinding roller. Grinding machine Most of the grinding rolls are toothed rolls. Smooth rolls are less common and are limited to the core grinding system. The technical characteristics of the grinding rolls are different for different types of mills and for different front and rear positions of the same mill.
The technical characteristics of the grinding rollers are different.
The speed and speed difference of the grinding rollers: The two grinding rollers are divided into a fast roller and a slow roller, with a speed ratio of 2.5:1. With a large speed ratio, the fast roller The speed ratio is large, the surface of the fast roller is scraping the wheat grain length is large, the wheat is scraped more times in the unit time, the degree of wheat crushing is high, and the output is high. High yield. However, the power consumption is large and the mechanical wear is fast. 2.
The number of teeth of the grinding roller is the number of teeth per centimeter of the circumference of the grinding roller surface. The more the number of teeth, the stronger the grinding effect, the greater the material crushing. In actual production, the number of teeth should be thin for the skin mill and dense for the heart mill, for the skin mill and the heart mill system, it should be thin for the front road and dense for the back road, such as 5.5-6 teeth/cm for the front road skin mill, 8.5-9.5 teeth/cm for the back road skin mill, 10-12 teeth/cm for the heart mill system, the number of teeth increases 1-1.5 teeth/cm with the number of passes of the mill, the powder road is long, the number of passes of the mill is more, the number of teeth increases less with each pass, the powder road is short The number of teeth increases with the number of passes.
3. Tooth angle: The cross section of grinding teeth is two asymmetric sides. The narrower side is called the front side, the wider side is called the blunt side. The line from the top of the tooth to the center of the tooth roller can be divided into two parts, the angle between the line and the front surface is called the front angle: α, the angle between the line and the obtuse surface is called the obtuse angle, β, the angle formed by the two sides is the tooth angle, γ, γ = α + β. The top of the tooth is a plane, which plays a grinding role on the material, and the size of the top of the tooth is also determined according to the requirements of the grinding process. The grinding effect of the material, affected by the size of the tooth angle. The larger the tooth angle, the greater the crushing effect, the grinding effect is also affected by the size of the front angle, the front angle is fast roller grinding teeth and material contact, and the material for the crushing effect of the sharp or obtuse angle. Specifically related to the arrangement of grinding teeth. In actual production, in order to produce more flour, less dregs, wheat heart, and keep the bran flakes intact, can use a larger tooth angle, especially the use of a larger front angle, processing durum wheat and low moisture wheat should be more so.
4. Slope of grinding teeth: The teeth grooves on the surface of the grinding roller are created in a spiral line, so that the grinding teeth form a certain slope with the bus line of the grinding roller. The slope of the grinding teeth is designed to improve the shear of the material in the grinding process. When a pair of grinding rollers rotate in opposite directions, the teeth of the fast rollers and the shear of the material can be adjusted. When a pair of grinding rollers rotate in opposite directions, the teeth of the fast roller and the teeth of the slow roller will form many intersection points. The greater the slope of the grinding teeth, the more intersections the two rolls will have. The greater the slope of the grinding teeth, the more intersections between the two rolls, the stronger the shearing effect in grinding, the smaller the scraping force and the power saving, but the bran flakes are easily broken and the product quality is poor. For soft wheat, high For soft wheat and high moisture wheat, a grinder with a large slope of the grinding teeth can be used, while the processing of durum wheat, low moisture wheat, it is appropriate to use a smaller slope. The slope of the grinding teeth is usually expressed as the ratio of the distance (arc length) between the two ends of the same grinding teeth on the circumference of the grinding roller end face and the length of the grinding roller, i.e. The slope of the grinding teeth in a milling plant is generally 1:7, 1:8, 1:9, 1:10. 5.
The arrangement of grinding teeth: Since the grinding teeth have a sharp (narrow surface) and a blunt (wide surface), for each pair of grinding rollers, the grinding teeth are arranged as follows For each pair of grinding rollers, there are 4 different arrangements according to the relative positions of the teeth of the fast and slow rollers.
①Front-to-front arrangement, in which the fast roller is installed with the front edge facing downward and the slow roller with the front edge facing upward. In this arrangement, the front angle of grinding teeth is small. The shearing effect on the material is strong, the crushing rate is high, and the produced dregs, wheat cores, bran flakes are broken, the power is saved, and the processing capacity is large, but it affects flour quality.
②Blunt to blunt arrangement: In the installation, the fast roller's sharp edge facing up, the slow roller's sharp edge facing down, the material into the grinding area first by the squeezing The material enters the grinding area first by the squeezing effect, and then by the shearing effect, the crushing effect is slow, the bran flakes are big, the dregs of wheat heart is less, the output of more flour, flour is good, but the power But the power consumption is large.
③Front-to-blunt arrangement: In the installation of the fast roller and slow roller, the front opening is facing down.
④Blunt-to-blunt arrangement: When installing the fast roller and slow roller, the sharp end is facing up. In addition to tooth grinding, light grinding mainly plays a role in grinding pressure. It is used to deal with the powder bran that cannot be scraped by the tooth mill.
The greater the linear speed of the rollers, the greater the amount of material passing through the mill per unit time.
The greater the linear speed of the roller, the more material passes through the mill per unit time, and the higher the output of the mill. If the flow rate is fixed, the thickness of the flow layer of the material through the grinding area is thinned, then strengthen the Scraping effect. However, when the speed of the mill reaches a certain limit, the machine will vibrate, the bearings will heat up, and even the grinding rollers will break the shaft. and other accidents. Fast roller line speed of 6-7.2m/s is generally appropriate.
The ratio of the speed of the fast and slow rollers is called the speed ratio. Under the condition that the unit flow rate and the line speed of the fast roller remain unchanged, the speed ratio K increases, and the produced crumbs, cores, and cereals will be produced.
The higher the speed ratio, the stronger the scraping effect. The larger the speed ratio, the stronger the scraping effect.