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Results of a study on the quality of conical picks for public procurement purposes

Bołoz Ł.

New Trends in Production Engineering

2018

Vol. 1, Iss. 1

687-693

The article presents the results of a study on the quality of conical picks for the purposes of tender procedures in accordance with the public procurement law in Poland. The pick studies presented here are one of the few that in practice allow the selection of an offer based on objectively determined numerical indicators defining the quality of the product and not only on the basis of price. Thanks to this, the contracting party can decide the relevance of price and quality in their evaluation of a pick. The geometrical and material parameters required in a tender, if not met, are the basis for rejecting a given offer of picks. The numerical parameter influencing the final evaluation of the offer is the picks' rate of wear. Conical picks are tools for mining minerals, rocks, asphalt or concrete. They are used in many industries, especially in mining, construction and road engineering. In difficult working conditions, the durability of knives is limited to as little as several hours. Several dozen picks work on a cutting unit at the same time, and taking into account the price of a knife which oscillates around several dozen euros, significant operating costs are incurred. Therefore, the selection of tools with an optimum price-quality ratio is crucial. The article presents the results of studies on geometric parameters, material parameters and the rate of wear of 48 sets of picks conducted for a tender consisting of 14 tasks. The tender was conducted for 6 underground mines of a coal company. Five producers submitted their offers for selected tasks in the tender.

Identyfikacja cech geometrycznych skrawów wykonanych nożami kombajnów górniczych z wykorzystaniem skanera laserowego

Cheluszka P., Dziędziel J.

Przegląd Górniczy

2015

T. 71, nr 4

72--82

W artykule podjęto temat analizy cech geometrycznych skrawów wykonywanych nożami stożkowymi (stycznymi obrotowymi) w aspekcie modelowania ich kształtu dla potrzeb komputerowej symulacji procesu urabiania kombajnami chodnikowymi i ścianowymi. Dokonany został pomiar geometrii skrawów wykonanych nożem stożkowym w bloku cementowo-piaskowym na stanowisku do skrawania skał w laboratorium Instytutu Mechanizacji Górnictwa. Komputerowa rekonstrukcja kształtu skrawów zrealizowana została w oparciu o digitalizację ich powierzchni z wykorzystaniem skanera laserowego. Umożliwiło to przeprowadzenie obszernych analiz wartości podstawowych parametrów geometrycznych skrawów objętych pomiarem. Wyniki pomiarów skonfrontowano z wartościami teoretycznymi uzyskanymi w oparciu o powszechnie stosowane modele skrawów w celu określenia stopnia dopasowania teoretycznego (modelowego) kształtu skrawu do kształtu rzeczywistego.

This paper presents the analysis of geometrie features of cuts made by point pivots (tangential tools) in the context of shape modeling for the purpose of computer simulation of heading machines and longwall shearers mining process. Geometry measurements of the cuts made by a point pivot in a cement-sand block were taken at the stand for rock machining in the laboratory of the Mining Mechanization Institute. The computer reconstruction of the cuts' shape was performed by digitizing their surfaces with the use of a laser scanner. This allowed to carry out comprehensive analyses of the values of basic geometric parameters of the cuts subjected to measurements. The results were compared with the theoretic values obtained on the basis of widely-applied cut models in order to determine the extent of matching the theoretic (model) cut shape with the real shape.