Are you interested in concrete mixer tankers? And what is the working principle of the concrete mixer trailers? You can learn all knowledge of concrete mixers from this article.
Concrete Mixer Trailer
Dip angle of tank 14, 12,10 °
Speed 12-20 (r/min)
How the work priciple of cement concrete mixer trailer?
The entire mixing tank of the concrete mixer trailer is an asymmetric double cone with a variable cross-section, and an unequal-length joint cone faces from the largest diameter to the two ends. The bottom cone is short and the end is closed; the upper cone is long and the end is open.
Figures 1 is a schematic longitudinal sectional view passing through the axis of the mixer. Figures 1a and b are the two parts of the agitated drum. The diagonal lines in the figure indicate the remaining spiral blades, α is the spiral rising angle, and β is the angle between the stirring axis and the plane of the chassis. During work, the mixing drum rotates around its own axis, and the concrete wall is rotated along the circumference due to the frictional force and internal adhesion of the cylinder wall and the blades. After reaching a certain height, the concrete wall is moved by its own gravity. Flip and slip down. Due to the continuous rotation of the mixing drum, the concrete is continuously being lifted and slides downward, and is guided by the spiral track determined by the cylinder wall and the blades, resulting in a composite movement along the tangential and axial directions of the mixing drum. So that the concrete is pushed all the way to the end of the spiral blade.
When the mixing drum is shown in Figure 1a, when the tank is rotating forward, the concrete will be continuously pushed to the bottom of the mixing drum by the blade. Obviously, the concrete that reaches the bottom of the cylinder will be pushed back by the end wall of the mixing cylinder. In this way, based on the above movement, the axial rolling motion of the concrete upper and lower layers is increased, and the concrete is in this complex motion state. Get stirred. When the mixing drum is shown in Figure 1b, when the tank is reversed, the spiral direction of the blades is also reversed. At this time, the concrete is guided by the blades to move toward the mixing mouth until the mouth of the barrel is discharged. In short, the rotation of the mixing drum drives the spiral movement generated by the continuous spiral blades, so that the concrete obtains a "tangential" and "axial" composite movement, so that the mixing drum of the concrete mixer truck has the function of stirring or discharging.
Figures 1. Working priciple of concrete mixer
According to the structure and working principle of the mixing drum, the working conditions of the mixing trailer can be described as follows:
1) Loading. Driven by the driving device, the mixing drum rotates in a "forward direction" at a speed of about 6-10 r / min. The concrete or mixing material enters the mixing drum from the conduit through the hopper, and flows to the middle and lower part of the mixing drum under the guidance of the spiral blade.
2) Stir. For the concrete mixture added to the mixing drum, during the driving of the mixing conveyer or at the scene, the mixing drum is rotated "forward" at a speed of 8-12r / min, and the mixing material is turned down by the rotating cylinder wall and blades. Stir.
3) Stir. For ready-mixed concrete added to the mixing drum, the mixing drum only needs to be rotated "forward" at a speed of 1-3r / min during transportation. At this time, the concrete is only slightly disturbed to maintain the homogeneity of the concrete.
4) Unloading. Change the direction of rotation of the mixing drum and obtain a "reverse" speed of 6-12r / min. The concrete flows to the mouth of the drum and is discharged through a fixed and movable discharge chute.
At present, the spiral blades in the stirring barrel of the stirring conveyer truck adopt two practical blade spiral forms, namely Archimedes spiral curve and logarithmic spiral curve. Archimedes spiral curve, that is, a constant pitch spiral. The characteristic of this curved blade is that the distance between the blades spirally surrounding the cylinder wall in the axis direction of the mixing cylinder remains constant, but the spiral rise angle of the blades varies inversely with the diameter of the cross section of the mixing cylinder, as shown in Figure 2a . Logarithmic spiral, that is, a constant-inclined spiral. The helical rise angle of this blade is always the same, but the pitch varies directly in proportion to the diameter of the mixer, as shown in Figure 2b. By adopting such a spiral blade, it is relatively easy to take into account the performance requirements of stirring and unloading by selecting a moderate spiral rising angle.