The emergence period is in the form of self-falling stirring. With the increasing requirements for concrete, compulsory Medium concrete mixer appeared. Forced mixers can be divided into two types: vertical shaft type and horizontal shaft type. Almost all domestic mixers are of these two forms.
The free-fall Medium concrete mixer can be traced back to the beginning of the 20th century. Drum concrete mixers driven by steam engines in the early 20th century have begun to appear. In the next fifty years, double cone mixers of reverse discharge type and tilting discharge type and split drum mixers have been introduced and developed.
Since the self-falling Medium concrete mixer is mainly for mixing plastic concrete, forced mixers began to rise. Since its rise in the early 1950s, compulsory mixers have been rapidly developed and promoted. The first to appear was the disc vertical shaft forced concrete mixer. This type of mixer is divided into two types: turboprop type and planetary type.
After the 1970s, with the application of lightweight aggregates, circular trough horizontal shaft forced mixers, also known as horizontal shaft mixers, appeared. It is divided into single horizontal shaft type and double horizontal shaft type, and has the characteristics of both self-falling and forced mixing. It is a new type of mixer developed in the 1970s. It can be divided into single shaft type and double shaft type. This type of mixer has both self-falling and forced mixing functions. The linear speed of the mixing blade is higher than that of the vortex type. Small, so the wear resistance is smaller and higher than that of the vortex type. The single-shaft mixer is made in Germany with the advantages of compact structure, low power consumption, good wear resistance of the blade liner, full load start and the ability to mix lightweight concrete. my country also introduced prototypes to the company. The twin-shaft mixer is a new model gradually developed with the improvement of concrete construction technology. Foreign countries began to appear in the United States and Germany in the late 1940s, but due to the immaturity of shaft end sealing technology, its development was basically at a standstill.
Until the early 1970s, due to a breakthrough in this technology, twin-shaft mixers were re-developed in many countries, and now a series of products have been formed. Our country was successfully developed in the early 1980s, but it has developed rapidly. In terms of product specifications and product quantity, it far exceeds other models. The mixing mechanism is the core part of the twin-shaft mixer. The quality of concrete mixing, the level of productivity, and the use and maintenance costs are all related to it. The mixing mechanism is composed of a horizontally arranged double circular trough-shaped side drum, two mixing shafts rotating in opposite directions and a mixing blade installed on it. The action radii of the mixing blades intersect each other, and the blades are at a certain angle with the shaft centerline. When the mixing shaft rotates, the blades drive the mixed material to make a circular motion in the two mixing drums, rolling up and down, and at the same time the mixing blades In the part where they meet or overlap, the co-domain of the mixture between the two shafts exchanges; on the other hand, the mixture is pushed along the direction of the agitating axis, continuously moving from the rotating plane to the other rotating plane. Compared with the self-falling concrete mixer, this mixing method has a stronger effect and is mainly suitable for mixing dry hard concrete.
Then the continuous Medium concrete mixer appeared. Its working principle: equipped with spiral mixing blades, various materials are continuously weighed according to the mixing ratio and then sent into the mixer, and the mixed concrete is continuously discharged from the discharge end. Advantages of continuous concrete mixer: short mixing time and high productivity.
With the development of concrete materials and construction technology, many Medium concrete mixer with new structures have appeared one after another, such as steam heating mixers, supercritical speed mixers, sonic mixers, swing disc mixers without mixing blades and concrete mixers for secondary mixing.
