Coal Cutter Research Articles

95/04447 ZG45SI2Mn2MoVRE steel used in cast cutter picks for coal cutters

The influence of changes in crystallographic texture on the Hall–Petch (H–P) relationship for an Mg alloy was investigated. First, the texture variations were facilitated by changing the uniaxial tensile loading orientation with respect to the normal direction of the rolled Mg plate. With a strong plane texture of the as-received material, the initial dominant deformation mechanisms were systematically varied from the basal slip and prismatic slip to extension twinning, as well as combinations thereof. Second, different grain sizes were produced for each loading orientation through isochronal annealing at various temperatures up to 773 K while closely monitoring grain size and texture distributions. The experimental results are presented for the grain growth kinetics during annealing, changes in yielding behavior as a function of grain size and initial texture, and H–P relationship as a function of the texture. Moreover, the effects of changes in texture and dominant deformation mechanism on H–P parameters – namely, friction stress, σo, and strength coefficient, kσ – are discussed. Finally, H–P relationships for each individual deformation mode including basal, prismatic and pyramidal slips as well as extension twin are identified.

95/01145 Effect of heat treatment processes on the strength of brazed joint of coal cutter

95/01145 Effect of heat treatment processes on the strength of brazed joint of coal cutter

Mechanisms of coal fragmentation by a continuous miner

An analysis of coal fragmentation due to the action of a continuous miner is presented. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). The rotary coal cutter provided the versatility of varying the operating and in-situ parameters to provide information on the effects of generating 37 μm (0.0015 in) particles. In these tests, coal blocks with an approximate dimension of 50.8 ×35.6×20.32 cm (20×15×8 in) were first subjected to confining pressures equivalent to in-situ conditions. The blocks were then cut by the rotary cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as (1) penetration of bit into coal, (2) penetration resistance (thrust and cutting pressures), (3) rotating velocity of cutting head, and (4) acoustic emission activity in the coal block were monitored. During the test, all the cut products were collected for size distribution analysis. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using a camera attached to an optical microscope. The results led to a better understanding of the mechanisms of the fragmentation process during coal cutting and the effect of operating parameters, in-situ conditions and coal type on the size distribution of the cut product.

The Coal Cutter as a Seismic Source in Channel Wave Exploration

The detection of faults in coal seams using underground seismic techniques is now well established. In this paper we propose the use of the coal cutter as a seismic source. Coal production, far from being disrupted by hole drilling and shot firing, is an integral part of the technique.

Early applications of electricity to coal minning

Electricity as a source of motive power was first used in UK coal mines during the 1880s. The paper describes some of these early applications, with particular emphasis on the operational and safety problems which confronted electrical engineers of the period. The development of certain types of apparatus, including coal cutters, cables and switchgear is traced. Reference is also made to flameproofing and intrinsic safety, and the formulation of mining legislation governing the use of electricity in mines.

Slim-line coal cutter : Anonymous Mine and Quarry, V3, N6, June, 1974, P19

Slim-line coal cutter : Anonymous Mine and Quarry, V3, N6, June, 1974, P19

Progress in design and development of automatic vertical steering systems for underground coal cutters

Although control systems for steering coal cutters through undulating coal seams have been in use since the early 1960s, it is only since Webb's paper (Proceedings of the 3rd UKAC control convention, April 1968) in 1968 that the 3-dimensional dynamic nature of the process has been appreciated. The process model, previously expressed in terms of two independent variables, I and n, is here converted into a model in the single independent variable v. This, for the first time, permits analytical stability studies and proves the fundamental instability of analogue control, which arises from the profound effects of the coal-sensor delay. The technical case for stored-data digital control is therefore one of the main objectives of the paper.

Fundamental Research on Coal Cutting

For the purpose of determining the workability of coal face underground, the authors have carried out fundamental experiments on coal cutting in the laboratory. In this report, the authors are going to describe the relations between the cutting resistance and cutting conditions, i.e., depth of cut, bit angle, cutting speed, bit wear, and physical properties of coal. From these experimental results, the authors learned that the magnitude of cutting resistance of coal cutter or coal planer at the coal face underground could be generally anticipated.

採炭

As in about ten years the new mining machines and technics were imported, the mining method in Japan were changed remarkably.Natural condition of coal seam in Japan (1956)Working depth (Average) 334.7m(Maximum) 836mAverage thickness of seam 1.71mAverage thickness of coal 1.31mOutput from coal face 48.281Mill. t.About 65% of output is worked by longwall method. About 36% of output is gotten by blasting, and 36% by coal picks in coal face, but coal cutters are used pretly well. Hobels are used in Emukae, Takashima, Kogayama and Mitsubishi-Bibai. 55% of output is conveyed Panzer conveyor at coal face.Hydraulic stowing is carried out at Onoura and pneumatic stowing is used at Yamano, Akabira and Sakito coal mines. Slicing method for thick seam is carried out at Hojo and Takashima coal mines.We must decrease the number of coal faces in one pit and increase the output per one coal face, and use the practical working time effectively.

コール・カッタの切削に要する動力の算定

コール・カッタの切削に要する動力の算定

Mechanisation of Industry

IN an article in the Royal Jubilee number of Engineering published on May 3, Sir Richard Red-mayne says that the mechanisation of industry tends to increase both the wages and the time available for leisure of the operatives, and thus increases their material welfare without the application of what are known as ‘revolutionary methods'. He illustrates this progress by what is happening in the coal-mining industry. The hewing of coal by pick and filling it into a tub by shovel, in a more or less confined space, is work of the most arduous nature. The great expansion during recent years of mechanical coal cutters has made this work comparatively easy. In 1900 only 1-5 per cent of the British coal output and 25 per cent of the output of the United States was cut mechanically. In 1932 this had risen to 38 per cent in Britain and 68 per cent in the United States. In the Ruhr coalfield the mechanical pick has found great favour; in 1913 only 2-2 per cent was cut mechanically, now 90 per cent is, 84 per cent being cut by mechanical picks and 6 per cent by mechanical coal cutters. The transport of the cut coal from the coal face to the shaft bottom was almost as laborious as ‘getting’ the coal. Now, owing to the perfection of electrically actuated plant, not only is the haulage on the main roads carried out electrically, but in the secondary roads also it is replacing horses and ponies. So far as creation of wealth and increase of leisure and comfort of the mass of mankind are concerned, the engineer has taken a leading part. During the last 130 years, wages in coal-mining have risen 3-2 times and the daily time of labour has been decreased 37 per cent, the return on the capital remaining on the average stationary. The chief beneficiary under the system of mechanisation has been the manual worker. There is no doubt that the rationalisation of industry tends to decrease the number of employees, but Sir Richard Redmayne thinks that the lowering of the price of the commodity, its more effective distribution leading to the increase of new industries, together with the increase in wages and leisure creating an increased demand, will result in more than the absorption of the overplus of labour.

Cardiff Engineering Exhibition

THE thirteenth annual exhibition at Cardiff, held under the auspices of the South Wales Institute of Engineers, opened on November 21 and closes on December 1. The main object of these exhibitions is educational and also to encourage industry by bringing the manufacturers of machinery and plant into touch with the users. Whilst mining appliances were well represented, almost every branch of engineering activity has received attention. An outstanding feature of this year's display was an exhibition coal mine, equipped by the Coal Face Machinery Exhibitor's Associationan association which comprises nearly all the manufacturers of coal face machinery in Great Britain. It was installed not as an advertisement of any particular plant, but to show the possibilities of mechanisation at the coal face, and to keep mining engineers and others interested and informed of the most recent developments in this respect. The mine consists of a main roadway, a machine-mined heading and a longwall face, in which are placed examples of coal face machinerylongwall coal cutters and shearing machines, jigger and belt conveyors, dust filters and pneumatic drills. In the roadways and face, modern methods of supporting roof and sides are shown. The Department of Scientific and Industrial Research had a valuable exhibit illustrating some of the research activities of the National Physical Laboratory, the Fuel Research Station, the Chemical Research Laboratory and other scientific bodies. Thus, fatigue of metals, lubrication research, electric welding, alignment of machine tools, steel casting, micro-structure of metals, corrosion of metals, hydrogenation of coal, smokeless fuel and industrial applications of X-ray analysis, were among the topics illustrated. An interesting exhibit consisted of turned objects made of some of the latest plastic materials derived from coal, and intended to display the artistic possibilities of such materials.

Electricity as applied to mines

The paper deals in a very general way with the use of electricity in collieries. The types of generators, motors and cables are explained, and the factors governing the use of each particular type are discussed. A brief outline of the mechanical plant used in conjunction with motors is given, including pumps, haulages, coal cutters and winders. Diagrams are given of a typical haulage, as used extensively in this country, a turbine pump, a disc coal cutter and a small electric winder.