外文翻译--小动力掘进机在不同岩石面挖掘隧道的实验结果

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1、翻译部分英文原文AbstractIn this paper, the experimental results of a 45-kW and 15-t roadheader excavating a gallery with two different types of rock at the face using two different cutting heads are shown. It is proved that the roadheader works properly with both cutting heads. In comparison with other resu

2、lts in the literature, the principal parameters, i.e. specific energy, cutting rate and tool wear, are at a level that can be considered satisfactory taking into account the low power of the roadheader. On the other hand, the influence of the number of picks, which is the main difference between the

3、 two cutting heads, on the operational parameters is shown.2003 Elsevier Science Ltd. All rights reserved.Keywords: Roadheaders; Cutting head design; Specific cutting energy; Cutting rate; Tool wear1. Introduction: experience in using of roadheaders in a mineThe coal basin in the NW of Spain (Areces

4、et al.,1994) forms a syncline in which the coal seams are moderately inclined (30358) at the NW fold axis and almost vertical (70908) at the SE fold axis. Carboniferous material occurs under a flat Permian overburden,150 m thick.The use of roadheaders in this mine was a consequence of mechanisation

5、of the work. Coal mining by the long-wall method with powered roof supports makes rapid advance of the access roads necessary. On the other hand, the two alternatives for mining very thick coal seams, i.e. room-and-pillar in flat seams and sublevel caving in vertical seams, also makes the use of roa

6、dheader driving galleries in the coal seams necessary Several types of roadheaders are used in the mine for these different works:a. One roadheader (Fig. 1) of 60 t in weight, with a 250-kW ripping cutting head, especially designed for this type of mine in the context of research project (Anon., 199

7、1; Torano et al., 1992; Torano, 1994) with the objective of driving galleries of 10-m cross- 2 sections in coal seams of 1.01.5 m in thickness (with approx. 50% of the section in hard rock of uniaxial compressive strength up to sc120 MPa);b. Two roadheaders (Fig. 2) of 24 t in weight, with a 110-kW

8、ripping cutting head mainly used in driving galleries with medium hard rock (c60 MPa) or in croom-and-pillar mining;c. Two roadheaders (Fig. 3) of 12.5 t in weight with a milling cutting head of 45 kW, only used in advancing of galleries in coal (soft rock); the conveyor type means the roadheader ha

9、s a 2.8-m width and because of this it can only be used for advancing galleries in coal seams of 3.0 m in thickness (mainly in the mining method termed sublevel caving); andd. One roadheader (Fig. 4) of 15.5 t in weight with a 45-kW milling-type cutting head, developed with this narrow design especi

10、ally for this mine (Torano et al., 1997) for its application in driving galleries in 2.0-m-thick coal seams (minimum 1.70 m) in which previous roadheaders could not be used.The study described here was carried out in the context of this project. During the advance of galleries in 2.0-m-thick coal se

11、ams, it was sometimes necessary to excavate the rock of the seam walls, the strength of which was almost over the limit of the cutting capacity of the roadheader. It was decided to investigate if, under these conditions, the operation or cutting parameters were acceptable using two different cutting

12、 heads in the test.2. Test description2.1. Test objectivesThe aim was to determine the possibility of driving these galleries by means of a 45-kW roadheader, comparing two different cutting heads excavating the same type of rock in similar operating cycles. The main difference between the two cuttin

13、g heads was the number of picks: the first cutting head had 36 picks, while the new one had only 24 (Fig. 5).Because of the lower number of cutting tools in contact with the rock, the torque transmitted by the motor was trans formed to a larger tangential force in the pick, which allows higher -stre

14、ngth rock to be cut. Stress concentration is the major factor in rock fragmentation. The parameters to measure (according to classic studies on this theme; Fowell and McFeat-Smith, 1976;Gehring, 1989) are the cutting rate (volume of rock excavated per time unit in m3/s), specific energy (ener- 3 gy

15、necessary to excavate a unit of volume in MJ/m3 ) 3 and the tool wear or specific pick consumption (picks or pick mass lost excavating a unit of volume of rock in picks/m3 or g/m3 ). All parameters were measured 3 3 when the roadheader was excavating coal and rock, as well as when it was performing

16、other parts of the cycle.2.2. Description of the excavated faceThe coal seam mined by the sublevel caving method was vertical and its average thicknesswas2.0 m. With the aim of carrying out the test in the worst conditions, the test zone used was in an area with a seam thickness of less than 2.0 m.

17、A three-segment steel set support was used, the gallery being of 2.50 m in width at the low part and 3.0 m high. In Fig. 6 sketches of the excavated faces with the 36-pick (7.74 m ) and 24-pick 2 cutting heads (7.97 m ) are shown. 2 The coal seam was 1.70 and 1.90 m thick, respectively. It was forme

18、d by two veins: on the right the coal was soft (c5 MPa), while on the left the coal was c strong (c=1015 MPa) without rock between them. C The left wall was of siltstone (sometimes sandstone) with a compressive strength of s s60 MPa, fracture c spacing ofc=1015 cm and an RMR (Rock Mass 0 Ratio, Bien

19、iawski, 1976) value of approximately 3540. The SiO content in the rock was18% and the mean 2 grain size 18 mm. The Schimazek index wasat an average value of Fs0.194 N/m3m. The right wall was also sandy siltstone, but more fractured and it broke because of the discontinuities rather than the pick act

20、ion. Fig.7 shows the roadheader and the gallery.2.3. Test and measurementsThe test for each of the two cutting heads consisted of advancing 1.35 m (equal to the distance between steel sets) in three passes of 0.45 m each, since this was the dimension of the cutting head. While the roadheader was exc

21、avating, the instantaneous power and other electrical parameterswer e recorded by means of a data logger (Fig. 8).In each case, the cross-section was measured and the excavated volume was calculated in order to determine the energy consumption and tool wear. All the picks were changed for new one si

22、n each test and were weighed before and after the trial in order to determine the tool consumption during excavation. The pick mass lost in each test is more realistic than the number of picks changed for a longer period, because many picks can be lost due to other causes. The operating method was a

23、s follows: in the first pass (cutting the first 0.45 m) the different types of rock were cut separately; after this, the next two passes were carried out as in a typical cycle in the mine. Thus, the results for the two cutting heads could be compared in the ideal case, in which rock was cut separate

24、ly, or in the other case of a more realistic excavation. Information about the cutting of two coal veins and the left rock wall can be obtained from the first pass. The results for cutting of the right rock wall were less interesting because of its tendency to fall down due to discontinuities, which

25、 made its excavation easier.2.4. Test with 36-pick cutting headThe record of the instantaneous power consumption during the complete trial with the 36-pick cutting head is shown in Fig. 9.The total-interval average power is approximately 35 kW (less than the nominal power of the motor), although the

26、re are periods of 23 s during which values of 60 kW, representing an overload of more than 30%, are reached. Moreover, peaks of 100 kW are also observed. However, these peaks, produced when a pick hits on a hard rock zone, are instantaneous and are not significant. The cycle started with cutting of

27、the soft coal vein, working from top to bottom. This is common, because the first cut is the most difficult one due to the rock being more confined, and thus the soft rock is selected for starting the operation. This first cut then allows easier excavation of the other parts of the face, starting wi

28、th the right rock wall, followed by the hard coal vein and finishing with the left rock wall. When the cutting head is working, two different parts can be observed in the recording. One, for which high power is required, corresponds to the typical cutting operation (the head is against the face, cut

29、ting a significant volume of rock), the results of which are easy to compare in different tests. The other part corresponds to periods during which the head is carrying out other operations that require lower power. In this case, the results are not easily comparable because the power is only slight

30、ly higher than the power required for head rotation. These operations involve, for example, moving waste to help the conveyor work, attacking local points without excavating a significant volume of rock in order to give the final gallery profile, or moving the machine arm without contacting the face

31、 (in this case, head rotation is the only movement). These operations are developed according to the conditions and can be carried out during excavation of part of the face, or after excavating the complete section. In this study, the power consumption in cutting and other operations has been evalua

32、ted separately. The new 36 picks placed on the cutting head weighed 30 017 g before the trial and 30 001 g afterwards, i.e. the overall mass loss was16 g.2.5. Test with new 24-pick cutting headThe complete power record of the 24-pick head test is shown in Fig. 10.The average power for the complete p

33、eriod is similar to the other case, 35 kW, but the time spent at work is less (30 vs. 35 min, without computing stop periods).It can also be observed that the overloads endure for a longer time. In this case, the excavation cycle was slightly different, having worked the right rock wall in two phase

34、s: the first after excavating the soft coal vein and the second at the end of the cycle, when the final gallery profile was cut. The 24 new picks weighed 19 985 g before the trial and 19 961 afterwards, i.e. mass loss was 24 g.3. Results3.1. Cutting rate and specific energyThe results for the two di

35、fferent heads were analysed in two ways: first, comparing results for the first pass separately for different kinds of rock; and second, comparing the overall results of the three passes needed to advance 1.35 m. The results of the first pass can be observed in Tables 1 and 2. In the calculations, t

36、he time while the head was cutting the face and during other operations have been taken into account separately. The variables involved are: cross-section S (m ); advance A (m); time 2 t (min); average power P (kW) consumed during the period; energy consumed E (MJ); cutting rate C (m y 3 R h); and s

37、pecific energy S (MJ/m3 ). 3 E In Figs. 11 and 12, histograms of the power required are shown. Two types of rock were chosen as examples: the soft coal and the rock of the left wall. The high frequency at 20 kW that can be observed in the his to grams corresponds to operations different to cutting.

38、In the case of the first pass of the 24-pick head, it cuts the left rock wall at the end of the cycle and no other operations were needed. In Tables3 and 4 the results for the overall three passes are summarised. In Fig. 13 a histogram corresponding to the complete cycle for both cases is shown. In

39、a working cycle that can be considered as typical, the net cutting rate reached with both heads was approximately 25 m yh (gross rate 20 m yh considering other 3 3 operations as well ). The results are in accordance with other research studies (summarised in Cornejo, 1988; Torano, 1992). This is the

40、 cutting rate estimated in excavating a medium abrasive rock with a compressive strength s s30 MPa. C If the complete section of the gallery was of 60-MPa rock, the cutting power needed to achieve this cutting rate would be approximately 100 kW. Since only part of the cross-section was rock, a 45-kW

41、 roadheader could be used. The same conclusion is reached on analysing the cutting rate achieved in the different types of rock: the results for cutting rock (net rate 15 m yh or gross rate 3 10 m yh, taking into account other operations) and for 3 cutting coal (net rate 50 m yh or gross rate 30 m y

42、h) 3 3 are in accordance with other research work. It is interesting to point out that the cutting rate is more than 20% greater using the 24 pick-head instead of the 36-pick head, in accordance with recent experiences (Pichler, 2000).Relating to the specific energy, the same considerations can be m

43、ade. The values found for both types of head in the typical working range, 5.07.5 MJ/m3 , are 3 in accordance with results from other studies. This is approximately the specific energy needed to cut rock with s s45 MPa and containing -30% abrasive min- cerals (Cornejo, 1988).The values achieved for

44、different types of rock, 3.5 MJ/m3 for soft rock (coal) and ;1015 MJ/m3 for 3 3 hard rock, are in line with other studies (perhaps slightly high in the case of coal).In this case, the results are also better using the 24-pick head, with energy consumption being approximately 15% less than for the 36

45、-pick head (in agreement with Pichler, 2000).3.2. Tool wear (pick consumption)In this trial it was not possible to determine directly the pick consumption, because no pick was totally worn when cutting this small volume of rock. Never the less, the mass loss during the test allows us to estimate the

46、 rate at which one head would wear out a larger number of picks than the other. The results are shown in Table 5. From Table5 it is inferred that the tool consumption would be approximately 45% greater using the 24-pick head compared to the 36-pick head. Taking into account the pick weight (approx.

47、833 g) and assuming that it is not useful after losing 510% of its mass, then consumption of 1.53 and 2.23 g/m3 is 3 equivalent to 0.0360.018 and 0.053-0.026 picks /m3 , 3in accordance with other published results (when the specific energy required is 1015 MJ/m3 , tool con- 3 sumption of 0.0400.050

48、picks /m3 is common ). 3 These results are in accordance with the day-to-day work of this roadheader: the number of tools lost is nearly 45% greater with the 24-pick head than with the 36-pick head, as shown in Table6.This level of pick wear is high compared to soft mineral excavation (mining potash

49、, Ortega, 1996, or mining coal, Bermudez, 1995). Nevertheless, it is not excessive in the case of excavating rock (Anon., 2000),which demonstrates again that it is possible to use this kind of roaheader in advancing this type of gallery.4. ConclusionsFrom the tests carried out and from experiences i

50、n the mine, the following conclusions can be inferred: Analysing only the excavation of rock (the most critical material), the cutting rate using the 24-pick head is approximately 1020% greater than for the 36-pick head and the specific energy is clearly lower. Analysing a normal working cycle, in w

51、hich the complete face is excavated, the cutting rate reached with the 24-pick head is 20% greater, with less specific energy needed. One disadvantage is that cutting tool consumption is 4050% greater with the 24-pick head. Another disadvantage observed, for which the effects were not quantified, is

52、 the greater level of vibrations in the roadheader. In general, the use of a head with a lower number of picks would involve a balance between greater advancement in the rock and greater pick consumption. In the case of this mine, the use of the 24-pick head is clearly advantageous (because of the 2

53、0% increase in cutting rate, an increase in advancement of 1020 my month occurs with wear of only 1020 picks more).On the other hand, these other general conclusions can be inferred: Because all the operating parameters were within normal ranges when using both cutting heads, it can be concluded tha

54、t it is possible to use this type of low-power roadheader in advancing galleries through 2-m coal seams with hard rock walls (besides other advantages such as low investment costs, smaller equipment, etc.) It has been proved that it is possible to use low power roadheaders when advancing small secti

55、ons of galleriesor tunnels (Holzman, 1999) when cutting rock of up to 60 MPa (whenever the proportion of this rock at the face is -30%). Such use would be interesting in general tunnel works (water supply tunnels, drainage piping, etc.) advancing through sedimentary rock mass with some weak rock str

56、ata, as an alternative to the use of other machines or methods (Massignani and Blattler, 2001).中文译文小动力掘进机在不同岩石面挖掘隧道的实验结果J.Torano Alvarez*， M.Menendez Alvarez，R.Rodriguez DiezOviedo 大学矿业学院，西班牙阿斯图里亚斯Oviedo13 独立大街，邮编33004摘要在这篇论文中，实验结果来自一台 45 千瓦的 15 吨掘进机使用二个不同的切割头在两个不同类型的岩石面开凿一个隧道的实验，这证明掘进机的工作效率和掘进头和工作面

57、两个因素都有关系。和其他文献的结果相比较，这篇论文的主要参数，比如特性切割能，切割的速率，工具磨损，是用户是否满足考虑使用小动力掘进机一个参考标准；另一方面，齿数的影响，也就是二个切割头之间的主要差别，在操作参数上被显示。2003年 Elsevier 科学公司版权所关键字：掘进机；切割头设计；特性切割能；切割的速率；工具磨损1.介绍:在一个矿山中掘进机的使用经验这个在西班牙的西北面的煤盆地（Areceset al。，1994）构成一个向斜，煤层在西北面的折叠板快是适当地倾斜（30。35。），而在东南面的折叠板快则是几乎垂直的（70。90。）。石炭纪物质在平的二叠纪的过载之下发生，厚度150m。

58、这个煤矿掘进机的使用是工作机械化的结果，使用大力量的顶板架支撑的长壁开采方法的矿煤要求煤矿的通路必需迅速进步。另一方面，两个开采非常厚的煤层选择的方案，也就是在平面煤层分段支柱开采和在垂直的煤层分段凹陷开采，同样必需要求使用掘进机在煤层开掘出隧道。由于不同的工作许多种不同的掘进机被用于这个煤矿上。一、一台重60吨，截割头功率250kW的横轴式掘进机（图 1），在如下文（匿名的，1991；Torano et al，1992；Torano，1994） 研究计划中的目的是为了在11.5m的薄煤层掘进断面为10m2的隧道（由于大概50%的断面是硬岩石，断面单桥的抗压强度高达c120MPa），这种掘进机

59、就是特别为这种煤矿设计的；二、两台重24吨，截割头功率110kW的横轴式掘进机（图 2），主要用于在半煤岩（c60MPa）或者有空隙的煤层的隧道的掘进；三、两台重12.5吨，截割头功率45kW的纵轴式掘进机（图 3），只用在煤和柔软岩石前进巷道的掘进，运送机的类型意味着这种掘进机的宽度为2.8m，而且因为这个它只能用在掘进3.0m厚度煤层的巷道（这种采矿方法称为分段凹陷）；四、一台重15.5吨，截割头功率45kW的纵轴式掘进机（图 4），发展这种窄掘进机的设计是为了一种特别的煤矿，在这种煤矿里掘进机是为了掘进2.0m厚度煤层（最小处1.7m）的巷道，这种厚度的煤层一般的掘进机没有办法工作。图.

60、1在硬岩石中使用的掘进机图.2在半煤岩中使用的掘进机图.3在软岩石或煤层中使用的宽掘进机图.4在软岩石或煤层中使用的窄掘进机这里描述的研究在这篇论文的上下文被展开。在2.0m厚度煤层巷道进步的同时，为了要挖煤层的壁，掘进机有时必需要挖岩石，岩石的强度几乎超过了掘进机切割能力的的极限，所以决定进行调查，在可接受的操作或切割参数下的条件下，在这个测试中用两个不同的切割头。2.测试描述2.1测试目的通过使用45kW掘进机，比较其采用不同的掘进头，相似的轨迹挖相同类型的岩石的实验，目标是决定挖掘这些巷道的可能性。两个掘进头主要的不同是齿数的不同，其中一个有36个齿，而另外一个只有24个（图.5）。因为

61、割削工具的较低数目在和岩石的接触，所以传输的扭矩在切割齿里被电动机转换成一个比较大的切线力造形，这样允许强度更大的岩石被切割。接触压力是岩石破碎的主要因素。测量参数（依照在这一个主题上的古典研究，Fowell and McFeat-Smith 1976；Gehring，1989）是切断的速率（单位时间挖的岩石的体积即m3/s），特性切断能（挖单位岩石必需要的能量即MJ/m3），工具磨耗或者叫截割头的消耗（挖单位岩石消耗的截割齿即picks/m3或g/m3）。当掘进机挖煤和岩石或者在环节中作其它的部分的时候，所有的参数都被测量。2.2、被挖面的描述煤矿采用分段凹陷的方法开采是很平常的，这种煤层的

62、平均厚度是2.0m,抱着为了在最坏的条件下进行这个实验的目标，实验区通常在煤层厚度不到2.0m的地方，使用三片段式防护钢组，在低的部分巷道是2.5m宽，高为3.0m。在图.6的截割面草图上36齿（7.74m2）和24齿（7.97m2）的截割情况被表现出来了。煤层是1.71.9m的厚度，分别地，它由两个面组成，在右边煤比较软（c5MPa），但是在左边煤比较硬（c=1015MPa），在它们之间没有岩石。在左壁是有c=60MPa压缩力的砂粉岩，破裂空间为S0=1015cm，岩石比例大约为3540，SiO2在岩石中大约18%，其平均晶粒大约为18um,平均Schimazek分度为F=0.194N/mm

63、。右壁也是砂粉岩，但是更容易破裂，它是因为岩石的比截割齿运动更加不连续。图.7显示了掘进机和和巷道。图.5两个截割头在测试中的比较图.6两个截割头的挖掘图.7截割机和巷道2.3、测试和测量这个测试每个掘进头前进1.35m（等于钢组间的距离），由三段0.45m的小段组成，因为这个长度是掘进头的长度。当掘进机开始挖的时候，瞬是的功率和其它的一些电信号参数被一台数据记录仪记录下来（图.8）。在每个情况下，横断面是标准的，为了得到消耗的能量和工具的磨损，切割体积被计算出来，所有的截割齿在每次测试前都被更换，在使用的前后都要测量质量，以便知道在挖巷道的过程中消耗了多少。截割齿在每个测试中遗失的数目比现实

64、中截割齿在一个较长的时间内更换更有意义，因为由于其他的因素许多截割齿可能失去。操作方法如下：在截割第一个0.45m的时候，不同的岩石分开来截割；在随后的两个测试中，在煤矿中截割一个典型的圆周。如此，两个截割头的截割结果可以在理想的条件下进行比较，如在岩石分开的环境下，或者更现实的挖掘条件。煤道和左壁的切割信息可以从第一个测试中得到，人们对右壁的测试结果不怎么感兴趣，因为它是不连续的，比较容易切割。图.8掘进机在巷道面和数据采集系统图.9截割齿为36的掘进机挖掘瞬时功率2.4、截割齿为36的掘进头的测试截割齿为36的掘进头在整个测试过程中的瞬时消耗的功率的数据在图.9表现出来了。整个过程的平均功

65、率大约是35kW，（小于电动机的额定功率），虽然在其间有23s达到了60kW，表现有超过30%的过量负荷，更有甚者观察到了100kW的尖峰值，然而这个尖峰值是由一个截割齿突然碰到一个很硬的岩石产生的，时间很短，因此不重要。切割环从软的煤层开始切割，从顶部到底部，这是正常的，因为由于岩石被限制了更多的条件，第一次切割就更加困难了，所以软的煤被选为切割开始的地方。第一次切割允许在断面的比较容易切割的软的岩石进行比较容易的挖掘，从右壁开始，接着硬的煤层，最后是左壁的岩石壁。当截割头工作的时候，在记录数据中可以看到两个不同是部分，第一，知道要求的最高功率，符合典型的挖掘操作，结果是比较容易和其它不同是测试进行比较，另一部分符合掘进头在什么情况小需要较小的功率。在这种情况下，结果不容易比较，因为功率只需要比掘进头旋转需要功率稍微大一点。这些操作包括，比如移动废品帮助运输机运动，行进到一个没有开凿出一个足够大的容积能提供最后的巷道的轮廓的地点,或者在不干扰工作面的情况下移动悬臂。依照条件，这些操作被发展成能在挖掘了部分面期间实行，或在开凿完全断面之后实行。在这一项研究中,切割的耗电量和其它的操作被分开进行评估。36个新的掘进头在工作完成之前重30017