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Conical Picks for Undeground Mining

Bołoz Łukasz

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

221--230

EN

Mechanical cutting in underground mining faces increasingly difficult challenges. Deteriorating working conditions result in the development of automation and robotization, and the insufficient durability of cutting tools remains a serious problem. In addition to drilling, the technology of cutting provides a huge market for tools. Currently, mainly conical picks are used in the process of cutting. The cutterheads of shearers are equipped with at least several dozen conical picks, which, due to their workability and abrasiveness, sometimes work for merely a few hours. Hence the interest of users and manufacturers in the development of tools with increased durability. The article briefly presents the applied solutions of conical picks, their construction, dimensions and materials used. Attention was paid to the issues related to the protection applied and its marking. A review and analysis of commonly known construction solutions for picks and holders have also been carried out, and proprietary patent pending solutions for the pick and holder have been presented.

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Conical Pick Production Process

Bołoz Łukasz, Kalukiewicz Antoni, Galecki Greg, Romanyshyn Liubomyr, Romanyshyn Tara, Barrionuevo-Giménez Rafael

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

231--240

EN

One of the basic methods of mechanical rock mining is cutting, which faces increasingly difficult working conditions. Despite the rapid development of machines used in underground and opencast mining as well as in tunnel building, construction industry and road engineering, the problem of insufficient durability of mining tools remains unsolved. In addition to drilling and, to a lesser extent, planing, cutting provides a huge market for tools. Currently, the process of cutting is mainly based on conical picks. The cutterheads of cutting machines are equipped with several dozen, and frequently – more than one hundred conical picks, which, due to their workability and abrasiveness, sometimes work only a few hours. There is a market demand for over two hundred models of conical picks. This is due to the huge variety of shapes and sizes of picks as well as the methods of their mounting in the holder. The article briefly presents various solutions of conical picks, their construction, methods of protection, dimensions and materials used. Next, based on materials produced by ZWM Carbonex, the classic method of their manufacture using the turning technology has been described. The authors have also presented briefly the use of die forging for the large-scale production of picks, applied by Górnicza Fabryka Narzędzi Sp. z o.o.

3

Mechanical and microstructural aspects of C20-steel blades subjected to gas nitriding

Kucharska Barbara, Michalski Jerzy, Wójcik Grzegorz

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

147--156

EN

The paper presents the investigation of conical blades made of unalloyed steel C20 gas-nitrided by the Nitreg method. On the surface of steel blades (with tip angles in the range of 20–170°) an approx. 15 mm-thick nitride layer of was fabricated, which had a bizonal structure of: ɛ (Fe2–3N and Fe3(N,C)1–x) and ɛ + γ′(Fe4N) with a hardness of 1310 HV and 910 HV, respectively. Hardness tests carried out on blade cross-section showed that a 0.7–1 mm thick diffusion layer occurred under the nitride layer. By applying the criterion of effective nitrided layer thickness, gc+50, it was demonstrated that blades with a tip angle of 20° and 30° had been through-nitrided (i.e. nitrided through and through). A static compression test showed that, as a result of nitriding, the compressive strength of the blades had increased by a factor of two.