Analysis and Improvement of the Stability of the Hoisting System of DGZ-150B Jet-grouting Drilling Rig

The DGZ-150B multi-tube omnidirectional jet drilling rig (see Fig.1) is the main construction equipment for the multi-tube rotary jet method. The drilling rig has two main functions in the construction process: power head rotation and power head lifting. The stability of these two functions will affect the construction quality. In the construction process, the lifting mode of the power head is step-by-step lifting, and step-by-step lifting is to increase every time according to the construction parameters. Stepped lifting requires the power head to stay in a certain position for a period of time to keep the position unchanged for high-pressure grouting. Generally, in the construction process, the step distance is 25 or 50 mm. Due to the short step distance, high-pressure grouting is not required in the lifting process, and the lifting time is required to be as fast and stable as possible to improve production efficiency and avoid cement slurry waste.

1. Mechanical structure of the hoisting system and hydraulic system design

1.1 Mechanical structure of the hoisting system

As shown in Figure 1, the hoisting system of the drilling rig mainly consists of four main parts: the power head, bracket, column, and hoisting cylinder.

1.2 Design of the initial lifting hydraulic system

The hydraulic principle of the initial lifting system of the drilling rig is shown in Figure 2. It consists of an oil tank, constant pressure variable pump, three-way or four-way reversing valve, descending speed control valve, ascending speed control valve, and lifting hydraulic cylinder. hydraulic cylinders, etc.

The constant pressure variable pump provides power for the whole system, and the three-way or four-way directional valve controls the descending and ascending of the power head. The speed of descending and ascending is adjusted by the descending and ascending speed control valves. The three-position, four-way directional valve uses an O-shaped valve spool to keep the hydraulic cylinder stopping and not falling.

In the step lifting work, firstly, the three-position four-way reversing valve moves to the right to make the rodless cavity into oil, the rod cavity back to oil, the power head lifts the set distance value, the three-four-way directional valve back to the middle position, the cylinder stops lifting and keeps not falling. The cylinder stops lifting and keeps falling.