Concrete spraying machine is a machine that uses compressed air to continuously transport concrete along the pipeline and spray it onto the construction surface. Widely used in lining construction of underground engineering, wells, tunnels, culverts, etc. This article mainly introduces some classifications of concrete spraying machines.
According to the different methods of adding water to concrete mixture, it can be divided into dry type, wet type and semi-wet type in between.
Dry type A certain proportion of cement and aggregate, after being evenly mixed, blown to the nozzle by compressed air and mixed with the pressure water from the pressure water tank and sprayed. The construction method in this way is simple and fast, but the dust is too large, and the springback loss of the sprayed material is large, and high-grade cement is used. Most of the domestic production is dry.
The wet type enters the spray machine is the concrete mixture with water added. Therefore, the dust content in the spray is low, and the rebound amount is also reduced, which is the ideal spray method. However, the wet material is easy to condense in the material pipeline, causing clogging and troublesome cleaning, so it cannot be popularized.
The semi-wet type is also called the tidal type, that is, the concrete mixture is a tidal material with a moisture content of 5% to 8% (by volume). When this material is sprayed, the dust is reduced. Due to its lower adhesion than the wet material, it does not stick to the tank. It is an improved method of dry and wet.
According to the structure of the jet machine, it can be divided into three types: cylinder type, spiral type and rotor type
Cylinder type Cylinder type jet machine is durable. However, the body is too heavy, and the opening and closing of the upper and lower bell valves need to be manually operated, which is labor intensive and easy to cause pipe blockage, so it has been gradually eliminated.
Spiral type Spiral jet machine is simple in structure, small in volume, small in mass and good in mobility. 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 the spray support of small roadways.
The rotor type rotor jet machine has the advantages of large production capacity, long conveying distance, continuous and stable discharge, low feeding height, easy operation, suitable for mechanized supporting operations, and can be used for dry spray, semi-wet spray and wet spray. The spray method is a widely used model.
Dry machine
Depending on the structure, the double-tank concrete dry sprayer, the spiral concrete dry sprayer, the rotor concrete dry sprayer and the drum concrete dry sprayer, etc.
Double tank
It is composed of upper tank storage room, lower tank feeder, feeding impeller, bell-shaped door, compressed air pipeline, motor, etc. Close the lower bell-shaped door between the upper and lower tanks, and let compressed air flow into the lower tanks. The dry mixture is continuously and evenly sent to the discharge port through the feeding impeller, and compressed air is blown to the nozzle along the conveying pipe.
Spiral
The dry mixture discharged from the hopper is evenly pushed to the blowing chamber by the screw feeder, and the tank is filled with the mixed concrete. 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
There are many material holes in the vertical rotor. During the rotation of the rotor, when the material hole is aligned with the discharge port of the upper hopper, the material is added to the material hole; when the material hole is aligned with the upper blowing port, the compressed air blows the dry mixed material along the conveying pipe to the nozzle.
Drum
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 to the bottom, the mixture enters the blowing chamber, and the compressed air flows along the conveying pipe. Blow to the nozzle.
