Experimental study on the influence of cutting distance on the rock-breaking features of pick-shaped cutter
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摘要: 镐型截齿是掘进机、采煤机等矿山机械上应用最广泛的截齿类型。在实际截割过程中,镐型截齿主要工作于多齿耦合截割工况下,截割间距是该工况下的重要参数。针对截割间距对破岩过程影响的研究未考虑干涉截割的弱化作用的问题,提出一种多齿耦合截割时截割力的计算方法。针对石灰岩、红砂岩和2种模拟岩样开展了全尺寸单齿截割试验,对比分析自由截割和干涉截割的破岩过程。试验采集了截割力数据并进行了降噪处理,同时收集了截割碎屑,分析了截割间距对截割载荷、截割碎屑粒度、截割能耗、截割沟槽的影响规律。试验结果表明:① 截齿截割力随截割间距增加而增大,并逐渐接近自由截割状态,且干涉截割与自由截割条件下的截割力比值与截割间距/截割深度之间存在较好的线性关系,相关系数均大于0.95。说明干涉截割条件下截齿的截割载荷可利用自由截割载荷进行估算,进而得到了基于已有峰值截割力模型的干涉截割条件下的截割力估算方程。② 分别采用碎屑粒度指数(CI)和截割比能耗(SE)评价截割试验的碎屑粒度分布和截割能耗。随截割间距增大,CI呈先增大后减小的趋势,而SE呈先减小后增大的趋势。③ 当截割间距较小时,截割沟槽干涉显著,截割沟槽间残余岩脊较小,截割载荷较小,但由于截割沟槽干涉会产生较多细小碎屑,消耗较多能量,所以能耗升高;随着截割间距增大,残余岩脊增大,截割力增大,但由于已有截割沟槽对岩石的弱化作用且截割沟槽间干涉较少,形成的大块碎屑占比增大,所以截割能耗降低;随着截割间距进一步增大,截割沟槽间无干涉,且已有截割沟槽对岩石的弱化作用降低,截割力增大,碎屑粒度减小,截割能耗上升,截割状态逐渐趋近于自由截割。Abstract: The pick-shaped cutter is the most widely used cutter type in mining machinery such as roadheader and coal mining machine. In the actual cutting process, the pick-shaped cutter mainly works under the multi-tooth coupling cutting condition. The cutting distance is an important parameter under this working condition. At present, research on the influence of cutting spacing on the rock-breaking process has not considered the weakening effect of interference cutting. A calculation method for cutting force during multi-tooth coupling cutting is proposed to solve the above problem. Full-size single-tooth cutting tests are carried out on limestone, red sandstone and two simulated rock samples, comparing and analyzing the rock-breaking processes of free cutting and interference cutting. The experiment collects cutting force data and conducts noise reduction processing and collects cutting debris to analyze the impact law of cutting spacing on cutting load, cutting debris coarseness, cutting energy consumption, and cutting grooves. The experimental results show the following points. ① The cutting force of the cutter increases with the increase of cutting distance and gradually approaches the free cutting state. Moreover, there is a good linear relationship between the cutting force ratio under interference cutting and free cutting conditions and the cutting distance/cutting depth. The correlation coefficients are greater than 0.95. The cutting load of the cutter under interference cutting conditions can be estimated using the free cutting load. The cutting force estimation equation under interference cutting conditions based on the existing peak cutting force model is obtained. ② The coarseness index (CI) and specific energy (SE) are used respectively to evaluate the particle size distribution and cutting energy consumption of the cutting experiment. As the cutting distance increases, CI shows a trend of first increasing and then decreasing. SE shows a trend of first decreasing and then increasing. ③ When the cutting distance is small, the interference between the cutting grooves is significant, the residual rock ridges between the cutting grooves are small, and the cutting load is small. However, due to the interference between the cutting grooves, more small debris is generated. It consumes more energy and increases energy consumption. As the cutting distance increases, the residual rock ridge increases, and the cutting force increases. However, due to the weakening effect of existing cutting grooves on the rock and less interference between cutting grooves, the proportion of large debris formed increases, and the cutting energy consumption decreases. As the cutting distance further increases, there is no interference between the cutting grooves. The weakening effect of the existing cutting grooves on the rock decreases. The cutting force increases, the coarseness decreases, and the cutting energy consumption increases. The cutting state gradually approaches free cutting.
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Key words:
- spiral drum /
- coal rock cutting /
- pick-shaped cutter /
- cutting distance /
- interference cutting /
- free cutting /
- cutting grooves /
- cutting depth
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表 1 岩样物理力学特性
Table 1. Properties of rock samples
岩石
类型单轴抗压
强度/MPa抗拉强
度/MPa弹性模
量/GPa泊松比 密度/
(kg·m−3)石灰岩 116.4 8.2 46.3 0.32 2650 红砂岩 76.3 6.6 22.4 0.19 2140 模拟岩样 I 13.3 1.12 12.1 0.23 1390 模拟岩样 II 18.0 1.65 15.3 0.24 1660 表 2 截割间距及截割深度参数设置
Table 2. Parameter setting of cuting distancet and cutting depth
岩石类型 d/mm s/d 石灰岩 2, 3, 4, 5 1~10 红砂岩 5, 10 2~6 模拟岩样I 5, 10, 15, 20 1~7 模拟岩样 II 5, 10, 15 1~10 表 3 干涉截割时截割三向力均值
Table 3. Mean cutting three-way force in interference cutting tests
s/mm FX/kN FY/kN FZ/kN 自由 7.61 1.21 9.57 20 3.10 −2.05 5.55 30 3.61 −1.41 6.04 40 4.32 −1.45 6.54 50 5.63 −1.49 7.46 60 5.95 −0.72 7.82 70 6.34 −0.65 8.14 表 4 各岩样不同截割参数下截割力比值fr
Table 4. Cutting force ratios fr under different cutting conditions
石灰岩 红砂岩 模拟岩样I 模拟岩样II d s/d fr d s/d fr d s/d fr d s/d fr 2 1 0.43 5 2 0.60 5 2 0.24 5 2 0.50 3 0.63 3 0.70 3 0.68 4 0.76 5 0.58 4 0.73 4 0.56 6 0.91 7 0.70 5 0.82 6 0.85 8 0.83 10 0.89 6 0.81 7 1.04 10 1.01 3 1 0.43 10 2 0.54 10 1 0.21 10 2 0.46 3 0.55 3 0.78 2 0.38 3 0.60 5 0.62 5 0.75 2.5 0.41 4 0.72 7 0.81 6 1.00 3 0.44 5 0.79 10 0.99 4 0.47 6 0.88 5 0.65 4 1 0.51 15 1 0.39 15 1.33 0.41 3 0.68 2 0.42 2 0.47 5 0.88 3 0.65 2.67 0.57 7 0.92 4 0.86 3.33 0.74 10 1.01 4 0.78 4.67 0.83 5 1 0.53 20 1 0.41 3 0.63 1.5 0.51 5 0.85 2 0.56 7 0.96 2.5 0.57 10 0.96 3 0.75 3.5 0.87 表 5 截割碎屑粒度分布及CI和SE汇总
Table 5. Summary coarseness distribution and CI and SE
截割间距/mm 不同截割间距下碎屑粒度占比/% CI 总质量/g SE/(MJ·m−3) >25 mm >15 mm >10 mm >5 mm >3.2 mm >1.43 mm >0 自由 47.4 62 68.7 78.8 83.0 88.0 100 528 940 10.4 20 20.7 44 55.3 68.5 75.5 82.3 100 446 309 13.3 30 38.1 57.1 66.4 76.7 81.9 87.4 100 508 641 7.5 40 53.4 67.5 73.7 82.9 87.2 91.1 100 556 944 6.1 50 53.6 67 75.5 84.1 87.6 91.4 100 559 1 253 6.0 60 52.9 67.6 74.8 84.3 88.3 92 100 560 984 8.0 70 49.7 63.3 70.5 80.6 85.1 89.4 100 539 886 9.5 -
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