Hammer crushers – design and operating principle
The Strommashina plant has proven itself to be a manufacturer of very reliable hammer crushers. Having started the manufacture of crushers back in the middle of the 20th century, the Strommashina has permanently been improving their design.
The hammer crushers are the impact action crushing equipment. The primary crushing is carried out by hammers blowing the material lumps, and as a result of mutual collision of particles.
The first devices of such a type appeared as early as in the 19th century. At that time they were used for grinding not very hard mineral raw material. The operating surfaces of the first crushers used to get worn very fast. They had to be replaced often which was inconvenient and decreased the unit capacity before another replacement. At the beginning of the 20th century the upgraded devices were successfully used for grinding ore and metals.
The main classifications
In terms of shaft quantity, the hammer crushers are classified as:
- single-shaft (single-rotor)
- double-shaft (double-rotor)
In terms of the hammer attachment method:
- with hinged hammers;
- with rigid hammers.
In terms of arrangement of hammers:
- single-row (the hammers are arranged in the same plane);
In terms of the rotor rotation direction:
Design and operating principle
The hammer crusher consists of a housing inside which the rotor is installed. The latter can rotate at high speed. Impact elements (hammer, hammer stone) are hinged (or fixed) on the rotor. The rotor drives the hammers, thus starting the process of grinding the particles which get into the crusher operating space.
The materials charged into the hammer crusher strike against hammers, armour plates and against each other and are destroyed. There are modifications with special impact elements which are designed for grinding scrap metal. In this case grinding is effected die to twists, kinking and stretching of metal the components of which engage the crusher operating members.
The ground material is poured through grate bar and gets into the intake device.
The crushers vary in rotor size, impact hammer (hammer stone) type and other characteristics (motor power, etc.). However, except for small differences, the operating principle remains the same – impact action.
* length – 200 to 3000 mm, 4 diameter – 300 to 2000 mm.
Width of gaps in the grate bar is up to 25 mm. Capacity is up to 1000 t per hour. Rotation frequency is up to 1000 rpm. Motor power is 7 to 1250 kW.
Grinding degree is 10 to 15 (for single-rotor mechanisms) and 3040 (for double-rotor crushers).
Advantages and application
It is used in industry for grinding rock salt, black coal, gypsum, limestone, crushed bricks, saltpetre, some ores and other materials the moisture of which does not exceed 8%. The latter limitation is due to design features of the crusher. The processed substance is poured through a special grating. Moist materials can cause its clogging. However, some hammer crusher models being developed currently are equipped with special bottom plates instead of the ordinary grating. They allow processing moist raw materials also.
Advantages of such crusher units:
- simple design
- compact device
- comparatively light weight of the unit
- possibility of continuous operation,
- high capacity
- high grinding degree