Coupling vibration analysis of auger drilling system

In the process of drilling coal, the kinematics of drill-rod is quite complicated. The drill-rod not only vibrates in longitudinal, transverse and torsional direction, but also random impacts and contacts coal wall. Considering the drilling load of drill-bit and coal, contact impact of the drill-rod and coal wall, the drill-rods are dispersed into a number of finite elements. At the same time, the nonlinear dynamic model of drill-rod system coupling longitudinal, transverse and torsional vibration is set up. The simulations of the dynamic model are researched under the conditions of different hardness coal (2.7, 3.7, 4.65). In order to decrease the vibration of auger drill, the stabilizer is added onto the drilling mechanism. And the underground experiments are done at 2404 working face of Xie-Zhang Coal Mine in Shan-Dong Province of China. The results indicate that the transverse vibration radius, the longitudinal vibration frequency and amplitude all decrease with the rock hardness. The maximum transverse vibration radius shows an exponential relation with the drilling depth under the condition of the same rock. Under the same condition, the drilling depth of auger drill with stabilizer is 1.39 times that with no stabilizer, and the drilling pressure decreases about 2/3

Fault diagnosis of pump valve spring based on improved singularity analysis

The fracture of pump valve springs is another typical fault of emulsion pump with high pressure and large discharge, which greatly influences the volumetric efficiency of emulsion pump. The fault diagnosis on pump valve springs of emulsion pump was analyzed based on the singularity analysis of continuous wavelet transform. The improved method for Lipschitz index was presented with better robustness and efficiency based on the Least Square Method. The criterion for the fracture of pump valve was confirmed. Diagnostic results indicate that it is accurate and effective of the improved method to locate the singularity of signals, identify the moment when the valve disc impacts on base or lift limiter and judge the fault diagnosis of pump valve

Interference model of conical pick in cutting process

The load on conical pick is affected by many factors such as pick geometry and installation angle. In order to decrease the wear and vibration of pick in the cutting process by choosing proper impact angle, the interference mathematical models of straight and revolving cutting were established according to coal cutting theory. Based on this, coal cutting experiment was carried out with different impact angles β, different head face radii of pick body R and different cutting depths d to verify the mathematical model. The results indicate that the picks cutting into coal with a certain installed angle are prone to interfere with coal in the cutting progress. There is a crsitical impact angle, and it is different under different cutting conditions. The critical impact angle decreases with the head face radius of pick body R and cutting depth d. On the condition of given pick geometry and movement parameters, the cutting force of picks or cutting torque of cutting header decreases with the impact angle. When the impact angle of the pick is larger than the critical angle, the load on pick will increase prominently

Vibration characteristic analysis of the multi-drilling mechanism

For enhancing drilling efficiency and controlling drilling direction, it is necessary to predict and control dynamic behavior of drilling mechanism effectively. In view of the coupling vibration and low drilling efficiency of auger drilling machine, a dynamic coupling model of multi-drilling mechanism was established to analyze the vibration characteristics under different coal hardness, drilling depths and rotating speeds. Simultaneously, the vibration tests of drilling process were conducted on the coal cutting test bed, and the results correspond with the simulation results. The results show that: the vibration displacement magnitude and fluctuation of multi-drilling mechanism increase with the coal hardness, while decrease then increase with the drilling depth, and increase then decrease with the rotating speed. The increases of coal hardness and drilling depth result in difficulty for coal cutting. The cutting torque decreases with rotating speed, while there is little influence on the feeding resistance

Fault diagnosis of pump valve spring based on improved singularity analysis

The fracture of pump valve springs is another typical fault of emulsion pump with high pressure and large discharge, which greatly influences the volumetric efficiency of emulsion pump. The fault diagnosis on pump valve springs of emulsion pump was analyzed based on the singularity analysis of continuous wavelet transform. The improved method for Lipschitz index was presented with better robustness and efficiency based on the Least Square Method. The criterion for the fracture of pump valve was confirmed. Diagnostic results indicate that it is accurate and effective of the improved method to locate the singularity of signals, identify the moment when the valve disc impacts on base or lift limiter and judge the fault diagnosis of pump valve

Experiment on Conical Pick Cutting Rock Material Assisted with Front and Rear Water Jet

Conical picks are one kind of cutting tools widely used in engineering machinery. In the process of rock breaking, the conical pick bears great cutting force and wear. To solve the problem, a new method, conical pick assisted with high pressure water jet, could break rock effectively, and four different configuration modes of water jet were presented. In this paper, based on the analysis of the different water jet configuration’s advantages and disadvantages, experiments on front water jet, new typed rear water jet, and the combination of those two water jet configuration modes were conducted to study the assisting cutting performance and obtain the quantitative results

Characteristics of gas-solid two-phase flow in axial and swirling flow pneumatic conveying

U svrhu povećanja kapaciteta i učinkovitosti pneumatskih sustava prenošenja razvijen je generator vrtložnog protoka za postizanje pneumatskog prenošenja čestica vrtložnim protokom (SFPC). Provedena je numerička simulacija pneumatskog prenošenja čestica aksijalnim protokom (AFPC) i pneumatskog prenošenja čestica vrtložnim protokom (SFPC) primjenom Lagrange metode praćenja čestica (LPTM) u kojoj su uzete u obzir interakcije plinske faze i čvrste faze. Analizirane su raspodjele koncentracije čestica i brzine čestica. Rezultati pokazuju da se vrtložnim protokom poboljšala raspodjela koncentracije čestica i da je najprije porasla a zatim se smanjila brzina čestica kod pojačanog vrtložnog protoka; ipak se brzina čestica povećala za više od 40 % u odnosu na brzinu u AFPC. Vrtložni je protok pokazao optimalno ponašanje kod intenziteta vrtloženja od približno 0,3. Intenzitet vrtloženja brže se smanjivao s eksponencijalno većom aksijalnom brzinom plina. Rezultati eksperimenata o gubitku tlaka u AFPC i SFPC pokazali su da postoji optimalna brzina plina u AFPC koja je minimalizirala gubitak tlaka. Optimalna se brzina plina povećavala s količinom protoka mase; gubitak tlaka u SFPC najprije je porastao a zatim se smanjio s pojačanjem vrtloženja. Maksimalni gubitak tlaka u SFPC bio je veći od onoga u AFPC dok je vrtložni intenzitet bio 0,35; 0,376; 0,38, a količina protoka mase 1,5 kg/s; 1,9 kg/s; 2,5 kg/s. Gubitak tlaka u SFPC bio je manji nego u AFPC dok je intenzitet vrtloženja bio veći od određene vrijednosti.To improve the capacity and efficiency of pneumatic conveying systems, a swirling flow generator was developed to achieve swirling flow pneumatic conveying (SFPC) for particles. A numerical simulation of axial flow pneumatic conveying (AFPC) and swirling flow pneumatic conveying (SFPC) for particles was carried out using the Lagrange particle tracking method (LPTM), in which the interactions of the gas phase and solid phase were taken into account. The distributions of particle concentration and particle velocity were analysed. The results indicate that the distribution of particle concentration was improved by swirling flow and that of the particle velocity increased first and then decreased with swirling flow intensity; however, the particle velocity still increased by more than 40 % relative to the velocity observed in AFPC. Swirling flow exhibited the optimal behaviour when the swirling intensity was approximately 0,3. The swirling intensity decayed faster with greater axial gas velocity exponentially. The results of pressure loss experiments in AFPC and SFPC showed that there was an optimal gas velocity in AFPC that minimised the pressure loss. The optimal gas velocity increased with mass flow rate; the pressure loss in SFPC first increased and then decreased with swirling intensity. The maximum pressure loss in SFPC was larger than that in AFPC while the swirling intensity was 0,35; 0,376; 0,38 and the mass flow rate was 1,5 kg/s; 1,9 kg/s; 2,5 kg/s. The pressure loss in SFPC was lower than that in AFPC while swirling intensity was higher than a certain value

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake