ROLLS OF MILL

Principle of Operation

Products supplying the equipment are initially distributed between two rollers whose distance is adjustable . The working cylinders Products by compression and shear .
The roller speed and roller type are defined in accordance with the work . The slow ( internal) and mobile roll and fast roll ( external) is fixed.
Separating the endosperm goal of ensuring peel the finish of sharps without harming the very bark and consequently alter the quality of flour, mainly in ash content .
Parts of a cylinder :

1.Distribuição
* Globe supply.
Globe Power is intended to facilitate the distribution of the product throughout the length distribution , and lung also serves to maintain product flow in the cylinders. It is necessary that the product is distributed precisely along the entire length of the roll grinding to keep uniform , avoiding vibrations and reduction in yield. In a perfect distribution , the product mono falls layers over the entire length of the rollers being driven in the region between the rollers . The product should be distributed and homogeneous monolayers quantitatively and qualitatively .
* Rollers product distribution
Types of Rollers Distribution :
* It is used spline roller anterior and posterior reduction and compression in the cylinders . The fluted cylinder brings with slight slope 5 for better distribution of the product . The slope encourages distribution throughout the length of the roller.
* It is used in posterior position to extract the product from crushing .
* It is used in the previous position of the passages grinding - diamond tips .
The speed of the rollers of distribution can be done in two ways :
* Mechanically : using pulleys
* Electronically : automatic when banks are independent motors to move the rollers distribution , we can vary the speed of the same electronically via frequency inverters .
2.Válvulas :
It is of great importance for adjustment of the grinding cylinder banks , it is from these that standardizes the layer thickness of the product to be milled.
3.Defletores :
Are sets of plates that direct the product to the grinding zone .
They should cushion the product, therefore, should have a slope close to 90 ° and must break parallel paths to ensure a mono layer between the cylinders . It serves as the air deflector ( not allow the whirling air between the rollers) to break the flow of air from the interior of the cylinder banks .
Grinding Cylinders :

The grinding rolls perform various functions , depending on their position in the diagram of the mill. In Crunch , they have the effect of cutting to open the grain of wheat and scrape the endosperm with minimal dust production bran . Reduction and Compression in , however, the goal is to reduce the size of the endosperm to obtain a flour with minimal damage to the starch .
Grinding rolls consist of a pair of rollers and brushes to clean the surface . The pair of rollers rotates inward, where it is crushed or reduced by the pressure exerted by them.
Length of rolls:

1000 mm

1250 mm

800 mm
diameter :

250 mm

220 mm
The rolls are cast iron , externally treated to provide a hard surface, the hard surface depth is approximately 1 cm. During milling, and because heating of the rolls there is a tendency for a small expansion of the rolls , particularly in the extremities. To avoid such a problem, the rolls are gradually lowered approximately 15 cm 0.04 mm at each end . ( Bulging )
The two rollers do not rotate at the same speed because they could make flakes of the product , making screening difficult and reduces the efficiency of the process. Generally the upper roller ( external) is faster than the lower (inner ) .
In Crushing speed difference is 2.5:1
T1/T2 - Rapid roller rotates 650 rpm .
T3/T4/T5 - Quick rollers reduce gradually to 550 rpm .
speed difference is 1.25:1 , the rapid roller rotates 500 rpm .
Flights to Germ: whose behavior when going through smooth rolls is to increase in size, the speed ratio is 1 : 1 .
Nature of the surface and position of Rolls:
* ROLLS rifled :

NOTE: Position the rollers : First fast , then slow.

A- Cut / Cut

B - Back / Cutting

C-Corte/Dorso

D - Back / Back
OBS :
The back / back position favors compression , lower production Meal .
The court / court position favors the shear , higher production Meal .
Mirror Streak :

100 º to 115 º

40 º to 45 º

60 º to 70 º
Characteristics of rays :

* Dimensions : no. per cm :
Grows from T1 to T5 going from 4 lanes / cm to 10 or 11 rays / cm .
* Profile :
It is characterized by the angles ( on the cut) and ( on the back) , their values ​​are generally presented in the figure above .
* Mirror :
Its function is to prevent the cutting edge of the tooth . It is also called as a witness because it was draw conclusions on the wear of the roll or her perfect alignment. Width: 2 to 3/ 10 mm on T1 2/10 mm in T2 1/10 mm to T3 on.
OBS :
** The number of rays per cm both in slow roll in as fast is the same .
The higher ** No. of streaks per inch , the higher the attack to the product .
** The thicker is the smallest product is no. of rays per cm .
** The steeper the slope between the rays , the greater the paragraph . actions that the streak has on the product .
In ** milling head tilt is less increasing as it approaches the end of the milling group .
Table raiação rolls tickets streaks Tilt Angles % Mirror Position n.raias mm / cm T1 Total 3.82 300 45/65 8 0.3 D / D T2 5.41 425 45/65 10 0.2 D / D T3 7.32 575 45/65 12 0.1 C / C T4G 9.23 725 45/65 12 0.1 C / C T4F/T5G 10.5 825 45/65 14 0.1 C / C T5F 11.45 900 45/65 14 0.1 C / C
The maintenance of rays is a function of:
* The size of streaks ( thick or thin ) .
* From the slope of rays .
* The conduct of the mill , run empty as little as possible .
* The speed of the roller , the outer spins faster and therefore wears faster than the internal roll.
Result of worn lanes:
* Increased power consumption
Abnormal heating of the product, making it difficult to mill and sieve the increasing water loss.
* Difficulty in finishing the meal and increased extraction .
Table maintenance rays Ton for Cheap T1 to 1DM long T1 T2 2500-3000 4000-5000 6000-8000 T3 T4 T5 8000-9000 10000-15000
EXCHANGE OF ROLLS MUST BE ENCLOSED IN PREVENTIVE MAINTENANCE .
* ROLLS SMOOTH :

Can be smooth or rough , smooth over rough compressions and used in the reductions .
The rough cylinders receive a blast of air with particles of steel for the roughness . This roughness provides an increase in yield of flour to increase the shear .
Smooth cylinders should never be touched , because if the metal occurs if destempera .
The rollers are hollow and its inner wall must have a thickness such that does not allow warping ( small thickness ) , but also does not cause much dilation during labor .
The rifled cylinders are harder than smooth , hence one can turn the cylinder in smooth and rifled never smooth in rifled .
Relative disposition of Reels :
* Horizontal : It is the most used , facilitates feeding and product output .
* Vertical : In disuse entry very difficult product.
* Diagonal : The fastest roller is positioned at 45 º slow .
Transmission between rollers :
The drive is made by the bank roll fast and can be done by:
* For Gears : Resists high power , is simple , but has a drawback of losing the alignment of the gears after raiações .
* For current: Allows alignment of rollers after raiações , is noisy and the power ratio is limited .
* For Toothed Belts : You with a notched side and the two toothed sides . Approach allows the rollers after raiações absorbs satisfactory power being easy to maintain .
NOTE: There is a transmission system that uses a combination of gear and toothed belts .
Command cylinders .
* By Transmission: Made by belts
Advantages : better than the command by individual motors , simpler wiring installed power .
Disadvantages : inefficient Automation .
* For Solo Engines: Each cylinder has its individual engine.
Advantages : Facilitates the management and automation of the mill .
Disadvantages : Power consumption is higher . Cleaning the Rollers : Rollers T1 and T2 dispense cleaning, the other cylinders using :
Brushes : It is only used in the grinding , should just touch the rollers .
The brushes can be synthetic or animal hair or feathers .
Scraper : steel knives are tangent to the roll , making scraping the same . Are used only for plain rolls .
5.Regulagem the distance between the rolls :
The lower pair of rollers are adjustable . The support of each end is carried by an arm with a wheel bolt " handwheel ." This wheel is placed on both sides to adjust the grinding at both ends.
The roller mill is equipped with a release mechanism for the rollers, which can be done manually or automatically ( by compressed air ) when no food product in preventing wear of the rollers by friction .