Concrete mixer is a machine that mixes cement, gravel aggregate and water into concrete mixture. It is mainly composed of mixing drum, feeding and unloading mechanism, water supply system, prime mover, transmission mechanism, frame and support device. According to the nature of work, it is divided into intermittent type (batch type) and continuous type; According to the mixing principle, it is divided into self falling type and forced type; According to the installation mode, it is divided into fixed type and mobile type; According to the discharging mode, it is divided into tipping type and non tipping type; According to the structure of mixing drum, it can be divided into pear type, drum type, double cone, disc vertical shaft type and circular groove horizontal shaft type.
Self falling mixer: it has a long history. As early as the early 20th century, drum concrete mixer driven by steam engine began to appear. After the 1950s, double cone mixers with reverse discharge and tilting discharge and split drum mixers came out and developed one after another. The inner wall of the mixing drum of the self falling concrete mixer is provided with mixing blades arranged radially. During operation, the mixing drum rotates around its horizontal axis, adds the materials in the mixing drum, is lifted to a certain height by the blade, and falls by its own weight. In this way, it moves again and again to achieve the effect of uniform mixing. The structure of self falling concrete mixer is simple, and generally it is mainly used to mix plastic concrete.
Forced mixer: since its rise in the early 1950s, it has been rapidly developed and popularized. The disk vertical shaft forced concrete mixer appeared first. This mixer is divided into two types: turboprop type and planetary type. After the 1870s, with the application of lightweight aggregate, circular groove horizontal shaft forced mixer appeared. It is divided into single horizontal shaft type and double horizontal shaft type, with the characteristics of self falling and forced mixing. The stirring blade has the advantages of small linear speed, good wear resistance and less energy consumption. Mixing blades are installed on the rotating shaft boom in the mixing drum of the forced concrete mixer. The materials in the mixing drum are added to form a cross logistics under the strong stirring of the mixing blades. This mixing method is far more powerful than the self falling mixing method, and is mainly suitable for mixing dry and hard concrete.
Continuous concrete mixer: equipped with spiral mixing blades, various materials are continuously weighed according to the mix proportion, and then sent to the mixer. The mixed concrete is continuously discharged from the discharge end. This mixer has the advantages of short mixing time, high productivity and remarkable development.
With the development of concrete materials and construction technology, many new concrete mixers have emerged, such as steam heated mixer, supercritical speed mixer, acoustic mixer, swing disc mixer without mixing blade and secondary mixing concrete mixer.
