Research on the coefficient of friction of becorit K22 and K25SB linings

The article presents the method and results of experimental tests of the coefficient of friction between a steel rope and friction lining. The BECORIT K22 and BECORIT K25SB floor coverings were tested. The tests were carried out in accordance with the recommendations of the new German standard: DIN 21258 - Lubricants and impregnating agents for drive discs and transport ropes in mining - safety and testing requirements. The authors in this article emphasize that the Becorit K22 and K25SB linings are used for the wheels of propeller drums of mining machines. Characterized by high coefficients of friction (μ ≥ 0.25), also in cases of extreme weather conditions on the surface. The chemical properties of BECORIT linings ensure their resistance to swelling in the event of different oils and lubricants as well as mine waters. The material of which the claddings are made ensures very good machinability during rolling of rope grooves with the use of turning or milling tools. BECORIT K22 plastic cladding is particularly suitable for use in hoisting machines, where the rope base forms a large overlap angle on the wheel grooves (max 1°31'), which causes its lateral wear faster. BECORIT K22 material in this case provides a higher service life compared to other materials. Due to the way they are mounted on the wheel, they are made as 1-piece (monolith) or bipartite. In this article, moreover, the structure and principle of operation of the measuring station on which the tests were carried out are presented in great detail

The use of flat steel-polymer supporting ropes in mining multi-pole hoisting devices

The paper presents the development of a series of flat steel and polymer bearing ropes using a polyurethane polymeric material (the name of NPSP - flat steel-polyurethane). These ropes are intended for mining extraction devices with friction drive (multi-mill drive wheel, multi-rope drums with a number of ropes from 3 to 12 pieces). The authors of this article have presented a comparison of the drive power of a selected multi-mine mine hoist device with a classic steel round rope with the same extractor in which steel and polymer flat carrying ropes were used. The article also presents the development of mining construction of hoisting equipment, which includes the use of new rope ropes. Very positive results from exploitation in Polish mining of flat steel-rubber balance ropes (durability up to 12 years) can be the basis for the use of such ropes as supporting ropes. Flat steel-polymer supporting ropes, in which the matrix can be rubber or polyurethane or other plastic material, could contribute to increasing the durability of load-bearing ropes due to anti-corrosion protection as well as to reduce the dimensions of drive wheels and rope hoisting machines, and thus to lower the power of the winding machine (as a result of reducing the moments of inertia of the propeller, propulsion and rope). It is also worth mentioning that the NPSP carrying ropes can work directly on steel coatings of propeller drums with proper positioning, created by clamping elements (wood, plastic or aluminum blocks)

Strenghth analysis of hip joint replacement revision implant

The subject of the article is the evaluation of the strength of revision implants made of titanium or tantalum alloy, used during bone reconstruction of a hip joint while potentially using additional stabilizing screws, necessary due to significant bone loss. The article provides a preliminary strength analysis of implants, indispensable for further evaluation of strength limitations due to the risk of implant damage depending on the structure and number of additional screw holes. In the human locomotor system, the hip joint is the joint with the most load, hence the main problem is to establish an adequate load model which ought to be assumed for the needs of implant strength analysis. It is found necessary to perform a short, analytical review of the existing hip joint load models from the point of view of choosing the proper one, considering evaluation of implant strength by means of numerical studies using FEM. Differences in the implant load distribution depending on the used material are shown