In Construction, What is a Cement Mixer?

Mixer is a kind of construction engineering machinery. It is mainly used for mixing cement, sand, various dry powder mortar and other building materials. This is a bladed shaft that rotates in a cylinder or tank to stir and mix multiple raw materials to make it a mixture or a suitable consistency machine. There are many types of mixers, including forced mixers, single horizontal shaft mixers, double horizontal shaft mixers and so on.

The mixer is determined by multiple parameters, and it is impossible to describe a mixer with any single parameter. Shaft power (P), blade discharge (Q), pressure head (H), blade diameter (D), and stirring speed (N) are the five basic parameters describing a mixer. The discharge amount of the blade is proportional to the flow rate of the blade itself, the first power of the blade rotation speed and the third power of the blade diameter. The shaft power consumed by the stirring is proportional to the specific gravity of the fluid, the power of the blade itself, the third power of the rotation speed, and the fifth power of the blade diameter. Under a certain power and blade form, the blade discharge (Q) and pressure head (H) can be adjusted by changing the matching of the diameter (D) and speed (N) of the blade, that is, the large diameter blade Mixers with low speed (to ensure constant shaft power) produce higher flow and lower pressure, while small diameter blades with high speed produce higher pressure and lower flow. In a stirred tank, the only way to make micelles collide with each other is to provide a sufficient shear rate. From the perspective of the stirring mechanism, it is precisely because of the fluid velocity difference that the fluid layers are mixed with each other. Therefore, the fluid shear rate is always involved in the stirring process. Shear stress is a force that is the real cause of bubble dispersion and droplet breakage in stirring applications. It must be pointed out that the magnitude of the shear rate at each point of the fluid in the entire stirred tank is not consistent. The study of shear rate distribution shows that there are at least four types of shear rate values in a stirred tank. They are: Experimental research shows that, as far as the blade area is concerned, no matter what type of slurry is, when the blade diameter is constant, The maximum shear rate and the average shear rate increase with the increase of the rotation speed. However, when the speed is constant, the relationship between the maximum shear rate and the average shear rate and the blade diameter is related to the slurry type. When the speed is constant, the maximum shear rate of the radial blade increases with the increase of the blade diameter, and the average shear rate has nothing to do with the diameter of the blade. These concepts concerning the shear rate in the blade area need special attention in the design of mixer reduction and enlargement. Because small tanks are compared with large tanks, small tank mixers often have characteristics such as high speed (N), small blade diameter (D), and low tip speed (ND), while large tank mixers often have low speed (N). Blade diameter (D) and high tip speed (ND). ^[1]

The purpose of the cement concrete mixer is to mechanize the mixed cement concrete. There are many types of cement concrete mixers.

1. The mixer should be set in a flat position, and the front and rear wheel axles should be cushioned with square wood to keep the tires overhead, so as not to move when starting.

2. The mixer should be implemented with secondary leakage protection. After the power is turned on before work, it must be carefully checked, and it can be used after being tested as empty after trial running. During the test run, it should be checked whether the speed of the mixing drum is appropriate. Generally, the speed of the empty car is slightly faster than that of the heavy car (after loading) by 2 to 3 turns.

3. The rotation direction of the mixer should conform to the direction indicated by the arrow. If it is not true, the motor wiring should be corrected.

4. Check whether the transmission clutch and brake are flexible and reliable, whether the wire rope is damaged, whether the track pulley is good, whether there are obstacles around it, and the lubrication of various parts.

5. After starting up, pay attention to the normal operation of each part of the mixer. When stopping, often check whether the blades of the mixer are bent and whether the screws have fallen or loosened.

6. When the concrete is stirred or is expected to stop for more than 1 hour, in addition to removing the remaining material, pour stones and water into the shaker, turn it on, and wash out the mortar adhered to the bucket. There must be no stagnant water in the barrel to prevent the barrel and blade from rusting. At the same time, the ash accumulated on the outside of the mixer should be cleaned to keep the machine clean and intact.

7. After work and when the machine is not in use, the gate should be turned off and the switch box should be locked to ensure safety. ^[2]

Concrete mixer is a machine that mixes cement, sand aggregate and water and mixes it into concrete mixture. It is mainly composed of mixing drum, feeding and unloading mechanism, water supply system, prime mover, transmission mechanism, frame and supporting device. According to the nature of work, it is divided into batch (batch) and continuous; according to the mixing principle, it is divided into self-dropping and forced; it is divided into fixed and mobile according to the installation method; it is divided into tipping and non-tilting according to the discharge method; According to the structure of the mixing drum, it is divided into pear type, drum type, double cone, disc vertical shaft type and round groove horizontal shaft type.

A concrete mixer includes a power mechanism connected to a transmission mechanism through a shaft and a roller driven by the transmission mechanism. A roller ring body is installed on the roller cylinder body, and a gear meshing with the ring gear is provided on the transmission shaft. The utility model has a simple and reasonable structure. After the gears and ring gears are meshed, the slipping phenomenon between the supporting roller and the mixer roller can be effectively overcome in rainy and foggy weather; the transmission mechanism can further ensure the elimination between the supporting roller and the mixer roller. Slipping phenomenon. ^[3]