What are grinding machines?
The following types of loading are used in material grinding machines, depending on their functions and operating principle: smashing, impact, cracking, breaking, and abrasion. In most cases different load types act simultaneously, for example, smashing and abrasion, impact and abrasion, etc.
The necessity of different load types, and different grinding machine designs in terms of operating principles and sizes is caused by a variety of properties and sizes of the materials to be ground and the different requirements in the finished product particle size. Just like grinding processes, the machines applied for such processes are divided into crushers and mills. Let us take a closer look at what grinding machines are.
In terms of their operating type, the crushers can be:
1. Jaw type, in which material is crushed in an action of crushing, cracking and partial abrasion in the space between two jaws as they close together repeatedly.
2. Cone type, in which the material is crushed by smashing, breaking, partial abrasion between conical surfaces one of which moves eccentrically in relation to the other, thus crushing the material continuously.
3. Roll type, in which the material is crushed between two counter-rotating rollers. The rolls are often designed to rotate at different speeds, and then the material-crushing is accompanied by abrasion.
4. Impact type, which, in its turn, is divided into hammer and rotary types. The hammer crushers crush material mainly as a result of hinged hammers crushing it and as a result of abrasion. The rotary crushers crush material by striking it with breaker bars rigidly fixed to the rotor, collision of the material against the breaker plates and inter-collisions of the material pieces.
In terms of function, crushers are divided into those designed for low-, medium, and high-strength raw material.
For example, let’s look at a double-roll crusher with corrugated rolls. Our DVR-2/500 double-roll corrugated roll crusher is mainly designed for secondary crushing of medium non-ore medium-strength construction materials. It is used in chalk, marl, coal, slag, clinker, marble and other rocky materials, and for grinding viscous and moist materials - for example, clays.
The source material is fed into the crusher bin, then it is pulled by counter-rotating rolls, and the raw material is crushed. Due to single-stage compression in the crusher operation zone, the overground product output is low.
One of the advantages of the crusher is the low specific power consumed by the crusher, and reliability and ease of use.
Our DVG-2/500 double-roll crusher with smooth rolls is used solely for grinding (with simultaneous smashing) low-strength non-ore construction materials (viscous, moist, etc.). The special application of such double-roll crushers shows that they are more suitable for processing different materials which tend to sticking or contain sticky inclusions.
The crushers can also be used in lines and crushing complexes as the first and the second stages for crushing bulk material pieces.
To prevent overgrinding of the material, the up-to-date enrichment practice uses hammer crushers which operate mainly by smashing and impact with additional abrasion and bending action on the material to be ground.
Impact crushing is largely more efficient in grinding that crushing by means of smashing.
Hammer crushers have proven to be excellent in production of construction materials, ceramics and asphalt and concrete fillers and in grinding glass, crushed stone, chalk (anhydrous), dolomite, fireclay, anhydrous metal salts.
Crushing equipment operation rules
The following rules must be observed during the operation of rotary and hammer crushers. The room where the crusher is located must be lit according to safety standards. Loading of large lumps, metal objects could cause damage to the crusher parts, so metal catchers or metal detector alarm devices must be installed on feeding devices upstream from the crusher. Alarm devices are able to respond to different metals, including non-magnetic ones, and generate the feeding device shutdown signal.
It is prohibited to overload the crusher, as this may cause rotor shutdown when the crushing chamber is full. Removal of obstruction must be performed with due observance of safety precautions. In crushers with opening upper part of the housing the discharge is performed downwards when the housing is opened carefully. In this case staff must be in a safe location so as to avoid injury from material lumps falling from the crusher. In crushers with non-opening housings it is necessary to open the hatches carefully having taken measures against falling of pieces from suddenly opened shutters.
It is prohibited: to operate a malfunctioning crusher; to open latches to the crushing chamber or delivery tray during operation; to leave the operating crusher unattended; to stay in a zone where pieces may be thrown from the crusher and in pulley rotation zone during crusher operation; to shut down the crusher when the crushing chamber is full; to leave working tools or other objects which can fall from the crusher during crusher operation.
Before commencing repairs, it is necessary to make sure the feeder and delivery tray are free of material pieces which can fall into the crusher; preclude any possibility of the crusher or feeder actuation by switching off the main switches or removing fuse links; stop the crusher rotor so that it could not move spontaneously when people are on it.
Any worn parts must be replaced by at least two workers - one of whom shall be responsible for work safety and observation of safety rules.
Depending on physical properties of the source material (hardness, moisture content, sizes of incoming and outgoing material, etc.), specifications and design features of the crusher may vary.
The crusher can be installed either indoors, or outdoors under a canopy. The height and design of platforms and support stands is determined based on the material shipment conditions.
If the hammer crusher is installed onto a foundation immediately, then a reinforced process opening matching the size and position of the discharging device must be provided.
The Samara Strommashina plant offers a wide range of crushers for sale, crushing and grinding units and other industrial equipment for sale. We can offer a new look at processes of your enterprise.
Based on the equipment we manufacture we are able to select a technology and configure the main and customised equipment for mineral and artificial raw material grinding process lines.
The Samara Strommashina plant ensures high quality, reliability, ease of use, repairability, competitive prices, uninterrupted supply of spare parts and maintenance service of all our products. These are strong reasons to buy a crusher from us.
All our products are certified, they have permits for use and sanitary-epidemiological conclusion certificates. The original designs are patented.