The ROI 4E is suitable for grinding of limestone or other rock or inert material where it is necessary to comply with a predetermined granulometric curve.

PRINCIPLE OF OPERATION

The machine is suitable to obtain a reduction of particle size of an incoming product by grinding and not crushing.
Through two pairs of rollers (which may be grooved or smooth) and which rotate at different speeds the product's granulometry is reduced by undergoing a mainly cutting effect and in certain cases by compression.
Never occurs in this machine an effect of crushing due to a collision, therefore, the output particle size is easily adjusted, without changing the number of revolutions or replace parts.

Crushing: reduction of particle size by impact, not controllable and production of fragments of various sizes, very different from each other.

Grinding: reduction of granulometry in a progressive manner, without excessive production of fragments with very different sizes, and generation of fragments of fairly uniform size.

This machine finds its optimal location in the secondary grinding and grinding of redundancies.Although it can be used for grinding rock up to 10-20 mm in size, it is actually particularly advantageous, compared to other systems, for grinding size of 1-4 mm.And it is especially profitable to get sand with a particle size 600 or 300 microns with little filler.

In the downloadable attachment 'PRESENTATION ROI 4E' you can see graphs and tables of sands obtained. You can see how the grinding system is progressive and not particularly aggressive and this is accompanied by two advantages:

1) low consumption of electricity;

2) not excessive production of product with a particle size of less than 0:09.

The feed inlet is located in the upper part of the machine.
The distribution of the product, which is an integral part of the machine, is housed in the upper part of the supporting structure and is composed of two helically-grooved dosing rollers which allow an uniform distribution of the product to be ground.
The rollers are controlled by two hydraulic moto-vary-reductors.
The supporting structure of the machine is made of welded sheet carbon steel of high thickness;
The base is made HEB beams in order to ensure maximum rigidity to the structure and contain at maximum the vibrations.
The operating part of the machine is constituted by two pairs of horizontal rollers that allow two separate passages of grinding.
The rollers are approached through the action of two hydraulically driven cylinders.
The fine adjustment of the distance and parallelism of the rollers is obtained through adjustment wheels.
The variation of the distance of the rollers determines the particle size of the final product.
The rotation of these rollers is supported by tapered roller bearings with double ring cylindrical roller set, designed to withstand very high loads.
The lubrication of these bearings is done through the grease nipples.
The support bearing is made by means of fixed media and removable media.
-the fixed supports, made in spheroidal cast iron, are fixed to the supporting structure by jaws which ensure rigidity and lack of vibrations to the machine.
-the mobile supports, made in welded steel, are supported by a pin in hardened and ground steel, which allows for maximum flexibility and vibration absorption.

Always with the intention of improving the machine we brought in the new version the following enhancements:
1) roll gap adjustment system, blocker / shock absorber.

In a single enclosed block and operating hydraulic / static, it is met the possibility to adjust the working distance between the rollers, to compensate and dampen the vibrations and automatic disengagement of the rollers at a standstill.Compared with the previous version does not have the inconvenience of the presence of dust and a much wider adjustment range.

2) three-way taps excluders, allow to exclude with simplicity the hydraulic unit from a side of the machine.

3) Carter watertight, changing the shape of the casing and seals ensure absolute tightness.

4) Seals roll supports distribution. Changing the seals, the new maze and the possibility of a greased independently protect the bearings of the rollers distribution and allow less strain on the motor of the distribution.

5) The hydraulic motovariator allows to vary the speed in a continuous mode up to zero rpm, without straining the motor, the lack of gears in the group variatoreidraulico allows a long life of it.

It is possible to greatly increase the performance of the rollers (which already have a good behavior) with a tungsten carbide coating which brings the surface hardness and abrasion resistance at the highest levels. From the findings of experiments carried out for several years, the duration of the roller has at least tripled.
This coating is recommended for companies that need to grind rock with high hardness and containing abrasive components.