Understanding Roller Presses in One Article (1)

Chapter 1: Working principle and structural characteristics of roller presses

I. Working Principle

The roller press mainly relies on two horizontally mounted and synchronously rotating extrusion rollers for high-pressure material layer crushing. The enclosed material layer is forced to move downward in the process of the squeezing pressure gradually increased to large enough, until it is crushed and squeezed into a dense material cake from the machine under the discharge. The mechanical strength of this material cake is very low, high abrasiveness. Material particles less than 2mm in the cake account for about 60-70%, and there are many micro cracks.

Second, the structure of roller press
The structure of roller press is composed of frame, fixed extrusion roller, hopper, hydraulic system, cooling system, lubrication system and transmission device.

(A) Extrusion roller and roller surface
1、Squeeze roller: It is the core part of the roller press, mainly composed of roller body and overlay wear-resistant layer.
2、Roller surface: the design is developed by three layers of overlay welding.

(II) Feeding device

1、Feeding hopper: ensure the continuity of feeding material, and make the material enter the roller gap by material pressure.

2、Adjusting insert plate: Adjusting the material throughput and power required of the roller press within a certain range to keep the stable operation of the roller press.

3、Side baffle plate: Eliminate the "edge effect" of material extrusion in the roller press.

(C) Transmission system
It is mainly composed of reducer, hydraulic coupling, universal coupling, shrinkage coupling, motor, lubrication device and other parts.

(iv) Hydraulic system

The hydraulic system is mainly to provide and maintain the squeezing pressure to the roller press to ease the impact of the material on the roller press.

(E) Lubrication system

The lubrication system basically adopts the single-line centralized lubrication system which is more advanced at present. The cooling system is divided into extrusion roller cooling and reducer lubrication station cooling.

Chapter 2 Rolling press process system

I. Process system composition

The mismatch of process system largely affects the normal use of roller press, so with the development of roller press, people have developed key supporting parts such as weighing bin, pneumatic gate, electric dividing valve device, scattering and grading machine, etc. The feeding, stopping and returning of roller press are completed by actuators, so that the control of the whole grinding system can be completed in the central control room, and the automation degree and operation rate of roller press are improved.

Grinding systems with roller presses applied by the group

1、Pre-grinding system

After the material is extruded by the roller press, the material at the two ends of the roller slit is subjected to a smaller squeezing pressure and the particles are larger, which is the so-called "edge effect". This part of the material is returned to the weighing bin by the bucket elevator. The middle part of the material is fed into the ball mill through the dividing valve under the roller press, and part of the material is returned to the small bin of the roller press to improve the denseness of the material in the bin and ensure the extrusion effect of the roller press. The ball mill and the high efficiency powder separator form a ball mill system, and the high efficiency powder separator separates the qualified products, and the coarse powder is returned to the ball mill.

Features are simple process, small grinding task for roller press, material circulation cannot exceed 100% of the new feeding volume, system energy saving range of about 20%, mill output can be increased by about 40%, and easy equipment layout.

At present, the pre-powder grinding system group is mainly applied to the production line with mill type φ4.2×11m.

2、Union grinding system

After the material passes through the roller press, it has to go through the V-type powder separator for dispersion and classification, the coarse particles return to the roller press for extrusion again, and the fine particles are semi-finished into the mill. The fineness of the semi-finished products can be changed according to the requirements of the final products, and the roller presses take up more grinding tasks accordingly.

The characteristic is that the system is relatively complex, the material circulation of the roller press is 200-300% of the new feeding volume, the energy saving of the system is about 40%, and the mill output can be increased by about 100%.

At present, the combined grinding system group is mainly applied to the production line with mill model φ4.2×13m.