Concrete spraying machine classification Types and advantages of wet concrete spraying machine
Concrete spraying machineClassification
According to the different methods of adding water to the concrete mixture, it can be divided into three types: dry type, wet type and semi-wet type in between.
Dry type: After mixing cement and aggregate in a certain proportion evenly, the compressed air is blown to the nozzle and mixed with the pressure water from the pressure water tank and then sprayed out. This method of construction is simple and fast, but the dust is too large, the rebound loss of the sprayed material is large, and high-grade cement must be used. Most of the domestically produced ones are dry type.
Wet type What enters the spray machine is the concrete mixture that has been added with water. Therefore, the dust content in the spray is low and the rebound amount is also reduced, making it an ideal spray method. However, wet materials are easy to condense in the material pipeline, causing blockage and troublesome cleaning, so it has not been widely used.
Semi-wet type is also called tidal type, that is, the concrete mixture is tidal material with a moisture content of 5% to 8% (by volume). This type of material reduces dust when sprayed because it adheres to the wet material. It is less toxic and non-stick to the can. It is an improved method of dry and wet methods.
According to the structural type of the jet, it can be divided into three types: tank type, spiral type and rotor type
Tank type tank type jet machine is sturdy and durable. However, the machine body is too heavy, and the opening and closing of the upper and lower bell valves require heavy manual operations, which is labor-intensive and can easily cause pipe blockage, so it has been gradually eliminated.
Spiral Spiral jets have simple structure, small size, low mass and good maneuverability. However, when the conveying distance exceeds 30m, it is easy to return air, the productivity is low and unstable, and it is only suitable for spray support of small tunnels.
The rotor-type rotor-type spray machine has the advantages of large production capacity, long conveying distance, continuous and stable discharging, low feeding height, easy operation, suitable for mechanized supporting operations, and can be used for dry spraying and semi-wet spraying. It is a widely used machine with various spray methods such as spray and wet spray.
Dry machine
According to different structures, there are two-tank concrete dry spraying machines, spiral concrete dry spraying machines, rotor concrete dry spraying machines and drum concrete drying machines. jets, etc.
Double-tank type
It consists of an upper tank storage room, a lower tank feeder, a feeding impeller, a bell-shaped door, a compressed air pipeline, a motor, etc. Close the lower bell-shaped door between the upper and lower tanks and introduce compressed air into the lower tank. The dry mixture is continuously and evenly sent to the discharge port through the feeding impeller, and is blown to the nozzle by compressed air along the conveying pipe.
Spiral type
The dry mix unloaded from the hopper is evenly pushed to the blowing chamber by the screw feeder, and the mixed concrete is filled in the tank. Then the compressed air introduced by the hollow shaft of the screw feeder and the blowing pipe blows the dry mixture along the conveying pipe to the nozzle.
Rotor type
There are many material holes on the vertical rotor. During the rotation of the rotor, when the material hole is aligned with the discharge port of the upper hopper, material is added to the material hole; when the material hole is aligned with the upper blowing port, the compressed air blows the dry mixture along the conveying pipe to the nozzle.
Drum type
Eight V-shaped grooves are evenly distributed on the circumference of the circular drum. The drum rotates at a low speed, and the dry mixture in the hopper falls into the V-shaped groove through the bar screen. When the V-shaped groove filled with the mixture turns downward, the mixture enters the blowing chamber, and is blown along the conveying pipe by the compressed air. Blow to the nozzle.
Types and advantages of wet concrete spraying machines
With the enhancement of people’s environmental awareness and the improvement of quality requirements for shotcrete, there are more and more Many wet concrete spraying machines have come into use. In some large-scale water conservancy projects under international bidding, such as the Ertan Hydropower Station, the Xiaolangdi Project on the Yellow River, the Three Gorges Project, etc., wet concrete spraying is used. Most of the various wet concrete spray machines currently used in China are equipment imported from abroad. in recent years. Some domestic units have also begun to develop several wet concrete spraying machines, but the production scale has yet to be expanded. To sum up, the main advantages of wet concrete spraying machines are:
(1) It greatly reduces the dust concentration next to the machine and outside the nozzle, eliminating hazards to workers’ health.
(2) High productivity. Dry concrete spraying machines generally do not exceed 5m3/h. When using a wet concrete spraying machine, it can reach 10m3/h when working manually; when using a robot, it can reach 20m3/h.
(3) Low resilience. When dry sprayed, the concrete resilience can reach 15%-50%. Using wet spray technology. The rebound rate can be reduced to less than 10%.
(4) During wet spraying, since the water-cement ratio is easy to control and the concrete is not chemically degraded, the quality of the sprayed concrete can be greatly improved and the homogeneity of the concrete can be greatly improved. However, during dry spraying, the concrete The water-cement ratio is adjusted by the sprayer based on experience and visual inspection. The quality of concrete depends to a large extent on the correct operation of the sprayer.
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