The cause of the flow failure phenomenon of concrete pump truck

The turbulent flow of the concrete pump truck during each commutation process usually shows a significant flow-break-flow phenomenon, which is commonly referred to as the current interruption phenomenon.

There are three reasons for the stagnation phenomenon:

1 When the main cylinder runs to the end of the stroke, the commutation signal is sent to the reversing cylinder for reversing, and then the main system oil passage is reversed, and the main cylinder moves in the opposite direction, the process takes at least 0.2s;

2 The inhalation efficiency of the inhaled cylinder is usually only 85% to 95%, inevitably inhaling a small amount of air, which will be a short flight;

3 When the reversing cylinder is in the direction of outward output, the pressure is increased and there is a certain compressibility, which is also a short flight. Due to the commutation and the two-stage idle travel time, a shut-off problem occurred during the pumping process.

The solution to the interruption flow in the pumping process of placing boom concrete pump is to shorten the commutation time as much as possible and to speed up the running speed of the main cylinder piston at the beginning of the commutation, and to achieve continuous pumping before the helium pressure is completely released in the pipeline and the distribution valve, as far as possible reduce the backlash caused by the outflow separation and the release of the helium pressure in the pipeline and the distribution valve during the commutation process. Through the selection and setting of the control mode of the main oil pump, the problem of interrupted flow of the helium transport can be effectively solved, the commutation shock is reduced, and the pumping performance of the helium pump is greatly improved.

At present, concrete boom pump trucks generally have a turbulent flow cut phenomenon at the moment of pumping commutation. This kind of shut-off phenomenon has two major hazards. One is that it is easy to cause cockroach segregation, and some of the cockroaches are dehydrated into dry hard cockroaches to cause blockage, especially in pumping. This is especially true for the slumping of the slump; the second is the release of the helium pressure in the reversing line and the distribution valve, which has an impact on the hydraulic system of the pump, causing damage to certain components and increasing energy loss. The damage is obvious when the flow is pumped vertically upwards, especially at a height of more than 50 m.