![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
The high-power hydraulic rock drill is the key to the development of modern hydraulic drill rig. With the increase of power and frequency of new type rock drill, the rebound of drill tool will be obvious during drilling, which will seriously affect the structural safety and operation efficiency. For this phenomenon, it is necessary to research the characteristics of double damping system to absorb the rebound energy of drill tool. A new model of incident stress wave is revised on the basis of rectangular wave. By combining the reflected stress wave with the model of damping system, the pressure fluctuation of damping system is analysed. Based on the theory of stress wave transmission, the rebound model of drill tool is established, and the transmission law of incident wave and reflection wave in drilling process is analysed. The stress wave experiment was designed and the incident wave shape was obtained by testing. Based on the experimental results, the incident wave in the rebound model is corrected by Fourier transform principle. The accumulator model and the double damping internal structure model are established. The two parameters that can independently change the energy absorption effect of the double damping system are summarised.
Nomenclature
| T | = | Stress wave period |
| τ | = | Stress wave duration |
| l | = | Piston length |
| c | = | Stress wave velocity |
| σi | = | Incident and reflected stress wave |
| ρi | = | Density of the i medium |
| ci | = | Wave velocity of stress wave in the i medium |
| An | = | The neck section area of accumulator |
| Ph | = | The working pressure of accumulator |
| me | = | The mass of accumulator equivalent to the simplified neck model |
| x2 | = | The equivalent mass (me) displacement |
| ce | = | The equivalent viscous coefficient of accumulator |
| ke | = | The equivalent stiffness coefficient of accumulator |
| ρ | = | The oil density |
| Lm | = | The pipeline length |
| Ln | = | The neck length |
| La | = | Pressure chamber length |
| Am | = | The pipeline section area |
| Aa | = | The pressure chamber section area |
| mg | = | The diaphragm mass |
| k | = | The isentropic coefficient |
| PH | = | The accumulator inflation pressure |
| Pd | = | The accumulator average working pressure |
| VH | = | The initial volume of accumulator |
| cn | = | The viscous friction coefficient of neck |
| cm | = | Viscous friction coefficient of connecting pipe |
| ca | = | Viscous friction coefficient of pressure chamber |
| Qd | = | The damping flow |
| Qd1 | = | The 1st damping chamber flow |
| Qd2 | = | The 2nd damping chamber flow |
| ΔQd1 | = | The 1st damping chamber compressed flow |
| ΔQd2 | = | The 2nd damping chamber compressed flow |
| Ad1 | = | The section area of damping piston in 1st damping chamber |
| Ad2 | = | The section area of damping piston in 2nd damping chamber |
| xd | = | The displacement of the damping piston |
| Vd1 | = | The oil volume of the 1st damping chamber |
| K | = | The elastic modulus of the oil |
| Pd1 | = | The pressure of the 1st damping chamber |
| Vd2 | = | The oil volume of the 2nd damping chamber |
| Pd2 | = | The pressure of the 2nd damping chamber |
| F | = | The rebound force of drilling tool |
| md | = | The mass of damping piston |
| cs | = | The viscous friction coefficient of oil |
| Fds | = | The viscous friction force |
| Fdl | = | The hydraulic seizing-up force |
| μ | = | The oil kinematic viscosity |
| Ld1, Ld2 | = | The length of fit between damping piston and front and rear guide sleeve |
| dd1, dd2 | = | The diameter of fit between damping piston and front and rear guide sleeve |
| ε | = | The eccentricity |
| δ | = | The annular clearance at connection between 1st and 2nd damping chambers |
| γ | = | The hydraulic seizing-up force coefficient. |
| η | = | The resistance coefficient, |
| Ad4 | = | The section area of the pipeline connecting the 1st damping chamber with the accumulator |
Disclosure statement
No potential conflict of interest was reported by the author.
Additional information
Funding
Notes on contributors
Yelin Li
Yelin Li, born in April 1986, received his doctor's degree in engineering from Beijing University of science and technology in January 2016, and his research direction is the design and testing of drilling machinery.