Study on Working Performance of Multi-impact Drum

Abstract

The current depletion of high-quality coal seams, hard coal mining had become the norm, while the traditional mechanical cutting methods were inefficient. A multi-impact cutting technology was proposed, which was to design a hydraulic system inside the drum. A hydraulic control system was formed by the hydraulic impact pick driver set by the ranging arm and the cutting motor to realize the reciprocating impact movement of multiple picks. The impact of picks was used to make the coal synchronously pre-crack, thereby reducing the difficulty of hard seam mining. In this paper, by analyzing the working process of the multi-impact drum, the corresponding mechanical model was established and the overall research plan was determined. A simplified drum model was established using CATIA, a coal model was established in EDEM based on the physical and mechanical properties of hard coal, and a simulation experiment composed of the cutting drum and coal model was based on orthogonality. The test method explored the working performance of the multi-impact drum under the action of multiple factors in cutting different media, using different impact frequencies and different drum speeds. The results showed that the coal breaking rate was used as the evaluation index, the order of the influencing factors was: A>C>B (coal hardness> drum speed> impact frequency), and the optimal plan combination was A2B1C3 (coal wall hardness was f5, impact frequency was 4Hz, drum speed was 40r·min -1 ); taking cutting specific energy consumption as the evaluation index, the order of influencing factors was: C>A>B (drum speed>coal hardness>impact frequency), the optimal plan combination was A2B1C3 (coal wall hardness was f5, impact frequency was 4Hz, drum speed was 40r·min -1 ). The matrix analysis method was further introduced to calculate that the order of the influence of each factor on the index value of the orthogonal test was C>A>B (drum speed>coal hardness>impact frequency), when the coal hardness was f5, the impact frequency was 4Hz, and the drum speed was 40r·min -1 , the working performance of the multiimpact cutting drum was the best. Under the same working conditions (coal hardness was f5, drum speed was 40r·min -1 ), a comparative simulation experiment of the traditional drum was carried out. Compared with the simulation results, the coal falling amount of the multi-impact drum was about 24.86% higher than that of the traditional drum, and the cutting specific energy consumption of the multi-impact drum was 0.7423kW·h/m 3 , which was about 21.67% lower than that of the traditional drum. Finally, a simplified multi-impact drum industrial cutting test was carried out. The test results showed that the cutting resistance of the multi-impact drum was about 17.22% lower than when there was no impact. Considering that the simplified multi-impact cutting drum had a reduced impact pre-cracking effect on the coal, it can be considered that the results of the industrial test and the discrete element simulation test were still relatively consistent. The multi-impact cutting drum had good working performance under hard coal conditions.

The Informativeness of Relative Performance Information and Its Effect on Effort Allocation in a Multitask Environment

“…While her experiment manipulates a form of RPI, she calls it “peer performance information” to emphasize that the importance of this information in her study is not merely to communicate relative differences. Rather, Zhang () predicts and finds that, when participants perform similarly on a difficult task, peer‐performance feedback enhances group cooperation in a subsequent task. That is, Zhang () finds that information that reveals similar efforts to meet a common challenge can facilitate a sense of group bonding.…”

“…Rather, Zhang () predicts and finds that, when participants perform similarly on a difficult task, peer‐performance feedback enhances group cooperation in a subsequent task. That is, Zhang () finds that information that reveals similar efforts to meet a common challenge can facilitate a sense of group bonding. While Zhang's experiment is far removed from the setting operationalized by HMNT, I mention her study to illustrate that RPI need not only be about competition.…”

“…First, while HMNT construct a laboratory setting in which anything other than equal effort across the two experimental tasks is suboptimal by design, it is unclear why RPI‐induced changes in effort allocation would necessarily be suboptimal in settings that benefit from specialization to master difficult tasks and/or remediation to achieve at least rudimentary performance on easy tasks. Second, I sense that the literature to date has tended to overemphasize the “R” in RPI, meaning that RPI need not only fuel competition by emphasizing relative differences, but can also facilitate team bonding by celebrating workers' accomplishments (e.g., Zhang ).…”

Numerical and Experimental Study on Crushing Properties of Hard Coal Using Impacting-Cutting Technique

“…e oil in the hydraulic tank of shearer is transported to the drum and the picks by the drive through pipes in turn. e reciprocating impact motions of picks are realized by the drive's control of the oil delivery direction [24].…”

“…Laser crushing is difficult to control the energy range, and it may change the properties of coal, which will lead to a physical failure. In response to these problems, an impacting-cutting technique was proposed by the author's research team [24]. e coal cutting characteristics of a single pick with impact function were studied, and the kinematic model of the pick with impact motion was analyzed.…”