Concrete mixer is one of the commonly used mechanical equipment in the construction industry. Its main function is to mix cement, sand and 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 supporting device.
1. Classification of concrete mixer
According to the working nature, it is divided into intermittent (batch) and continuous type, according to the mixing principle, it is divided into self-falling type and forced type, according to the installation method, it is divided into fixed type and mobile type, according to the discharging method, it is divided into tipping type and non-tipping type, according to the mixing drum structure, it is 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 beginning of the 20th century, drum-type concrete mixers driven by steam engines began to appear. After the 1950s, reverse discharging type and tipping discharging type double cone mixers and split drum mixers have been introduced and developed one after another. There are radially arranged mixing blades on the inner wall of the mixing drum of the self-falling concrete mixer. When working, the mixing drum rotates around its horizontal axis, and the materials added to the mixing drum are lifted to a certain height by the blades and then fall by their own weight. This repetitive movement achieves the effect of uniform mixing. The structure of the self-falling concrete mixer is simple, and it is generally used to mix plastic concrete.
- Forced mixer
Since its rise in the early 1950s, it has 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 and planetary. After the 1870s, with the application of lightweight aggregates, the circular trough horizontal shaft forced mixer appeared. It is divided into single horizontal shaft and double horizontal shaft, and has the characteristics of both self-falling and forced mixing. The linear speed of its mixing blades is small, the wear resistance is good, the energy consumption is low, and it develops rapidly. The rotating shaft arm in the mixing drum of the forced concrete mixer is equipped with mixing blades. The materials added to the mixing drum form a cross flow under the strong stirring of the mixing blades. This mixing method is much stronger 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 fed into the mixer after continuous weighing according to the mix ratio, and the mixed concrete is continuously discharged from the discharge end. This mixer has a short mixing time, high productivity, and its development is eye-catching.
With the development of concrete materials and construction technology, many new types of concrete mixers have appeared one after another, such as steam heating mixers, supercritical speed mixers, sonic mixers, swing pan mixers without mixing blades, and secondary mixing concrete mixers.
- Horizontal concrete mixer
Horizontal concrete mixer is a common concrete mixer. Its main feature is that it occupies a small area and is suitable for occasions with limited space. Its structure is compact, the operation is simple, and the mixing effect is good. Horizontal concrete mixer is suitable for the production of precast concrete, concrete pipes, reinforced concrete and other materials.
- Vertical concrete mixer
Vertical concrete mixer is a vertically placed concrete mixer. Its main feature is that it has a compact structure and occupies a small area. It is suitable for occasions with limited space. Vertical concrete mixer has good mixing effect and is suitable for the production of high-strength concrete, bridges, water conservancy projects and other materials.
- Mobile concrete mixer
Mobile concrete mixer is suitable for occasions that require frequent transfer. Its main feature is mobility, which is convenient for working in different construction sites. Mobile concrete mixer is suitable for on-site construction, road and bridge construction and other materials.
2. Performance parameters of concrete mixer
The main performance parameters of concrete mixer include production efficiency, mixing capacity, mixing time and motor power.
- Production efficiency
The production efficiency of concrete mixer refers to its ability to produce concrete per hour, which is generally between 30 and 90 cubic meters per hour.
- Mixing capacity
The mixing capacity of concrete mixer refers to the amount of concrete it can mix each time, which is generally between 0.5 and 4 cubic meters.
- Mixing time
The mixing time of concrete mixer refers to the time required for each mixing, which is generally between 2 and 5 minutes.
- Motor power
The power of concrete mixer motor determines its mixing capacity and efficiency, which is generally between 5.5kw and 45kw.
3. Concrete mixer purchase guide
- Concrete mixer power
The power of concrete mixer is one of the important factors to consider when choosing a mixer. Generally speaking, the greater the power of a concrete mixer, the higher the speed, and the better the quality of the concrete produced. However, the greater the power, the more expensive it is. Generally speaking, for home use or small construction sites, a concrete mixer with a power of 1-2 horsepower can meet the requirements. For large construction sites, you can choose a concrete mixer with a power of more than 3 horsepower.
- Capacity of concrete mixer
The capacity of the concrete mixer is also one of the factors to consider when purchasing. Depending on the usage scenario, you can choose concrete mixers of different capacities. Generally speaking, for home use or small construction sites, a mixer with 1-2 bags of concrete can meet the requirements. For large construction sites, you need to choose a concrete mixer with a larger capacity to improve work efficiency.
- Use scenario of concrete mixer
The use scenario of the concrete mixer is also one of the factors that affect the choice. Before choosing a concrete mixer, you need to understand your usage scenario and choose the appropriate model and specifications. For example, portable concrete mixers can be selected for home use and small construction sites, while large construction sites need to choose concrete mixers with larger capacity and higher power.
- Maintenance of concrete mixer
After purchasing a concrete mixer, correct maintenance and care are also very important. Before operation, it is necessary to make a good inspection to ensure that every component is in good condition to avoid accidents. At the same time, it is also necessary to clean and maintain regularly, and replace wearing parts in time to ensure the normal service life of the concrete mixer.
4. Precautions for the use of concrete mixers
The concrete mixer should be set in a flat position, and the front and rear axles should be padded with square wood to make the tires high and overhead to prevent them from moving when starting.
- The concrete mixer should implement secondary leakage protection. After the power is turned on before work, it must be carefully checked. It can only be used after the empty car test run is qualified. During the test run, the mixing drum speed should be checked to see if it is appropriate. Under normal circumstances, the empty car speed is slightly faster than the heavy car (after loading) by 2~3 revolutions. If the difference is large, the ratio of the driving wheel to the transmission wheel should be adjusted.
- The rotation direction of the mixing drum should be consistent with the direction indicated by the arrow. If it is not true, the motor wiring should be corrected.
- Check whether the transmission clutch and brake are flexible and reliable, whether the wire rope is damaged, whether the track pulley is in good condition, whether there are obstacles around, and the lubrication of various parts.
- After starting the machine, always pay attention to whether the various parts of the concrete mixer are operating normally. When stopping the machine, always check whether the blades of the concrete mixer are bent, whether the screws are knocked off or loose.
- When the concrete mixing is completed or it is expected to stop for more than 1 hour, in addition to draining the remaining material, pour stones and clean water into the shaking barrel, start the machine and turn it, rinse the mortar stuck on the barrel and unload it all. There should be no water accumulation in the barrel to prevent the barrel and blades from rusting. At the same time, the dust outside the mixing barrel should be cleaned to keep the machine clean and intact.
- After get off work and when the machine is not in use, the power should be turned off and the switch box should be locked to ensure safety.
5. Precautions for cleaning concrete mixers
When cleaning concrete mixers, the following matters should be noted:
- Perform maintenance and maintenance operations specified in the maintenance regulations regularly, such as cleaning, lubrication, and refueling.
- Before starting the concrete mixer, check whether the controllers are in good condition. After stopping work, pour water and gravel into the mixing drum for 10 to 15 minutes for cleaning, and then clear out the water and gravel. If the operator needs to enter the mixing drum for cleaning, in addition to cutting off the power supply and removing the fuse, the switch box must be locked.
- It is forbidden to use a sledgehammer to remove the concrete accumulated in the concrete mixer drum. It can only be removed with a chisel.
- In severe cold seasons, after work, the mixer drum should be cleaned with water and the accumulated water in the water pump, water tank, and water pipe should be drained to prevent the water pump, water tank, water pipe, etc. from freezing.
