Increasing the efficiency of trenchless laying machines using vibrating knives

Abstract

Modern requirements for the laying of underground communications consist of a combination of high construction rates with low energy consumption. The highest rate of laying linear objects is ensured by knife-type cable and pipe-layers, which are designed for their trenchless burial - this is when a narrow slot is cut in the soil, through which a cable or pipeline is launched. A feature of this process is the need to use large traction forces, which are determined by the resistance forces of the soil when cutting it. Accordingly, the cutting resistance of the soil depends on the dimensions of the width and depth of the gap and the physical and mechanical properties of the soil. Finding ways to reduce forces for deep cutting of soils is an important problem. One of the ways to improve the efficiency of trenchless laying machines is to equip them with vibrating knives. It is known that when the knife oscillates in the vertical direction, it leads, depending on the soil and the speed of movement, to a 30…60% decrease in traction resistance. But the use of more complex vibration movements of the knives allows reducing the traction resistance during deep cutting of soils by 70…90%. It is well-known that various designs of mechanical drive are used to implement the process of vibration of knives. These are complex devices that, together with the entire machine, require calculations. Therefore, studying the forced vibration of the knives of pipe deepeners is an urgent task, which is aimed at reducing the energy consumption of the process of soil deep cutting and improving the overall performance of knife machines for trenchless laying of underground utilities. To achieve the goal, the paper considered possible variants of the vibration oscillation of the knives and provided calculation dependencies for determining the resistance of soil cutting by active knives; also the dependence for determining the maximum average drive power of a centralized unbalanced vibrator was given. At the same time, the dimensions of the gap obtained, the physical and mechanical properties of the soil and the technical characteristics of the vibrator were taken into account.The obtained recommendations can be used when designing trenchless laying machines using vibrating knives.