Quality assessment of conical picks for public procurement purposes

W artykule przedstawiono wyniki badań jakości handlowych noży styczno-obrotowych na potrzeby realizacji procedur przetargowych zgodnie z prawem zamówień publicznych w Polsce. Przedstawione badania noży są jednymi z nielicznych, które w praktyce pozwalają na wybór oferty na podstawie obiektywnie wyznaczonych liczbowych wskaźników określających jakość produktu a nie jedynie na podstawie ceny. Dzięki temu zamawiający może decydować jaki udział w ocenie oferty stanowić ma cena a jaki jakość. Wymagane w przetargu parametry geometryczne oraz materiałowe, w przypadku braku spełnienia są podstawą do odrzucenia danej oferty noży. Parametrem liczbowym wpływającym na ocenę końcową oferty jest szybkość zużycia noży. Przedstawiono wyniki badań parametrów geometrycznych, materiałowych oraz szybkości zużycia 48 kompletów noży, przeprowadzone dla przetargu składającego się z 14 zadań. Przetarg przeprowadzono dla 6 kopalni podziemnych jednej ze spółek węglowych. Do wybranych zadań w przetargu swoją ofertę zgłosiło 5 producentów.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. 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

Use of the iLogic Autodesk Inventor tool in the process of designing self-propelled drilling rigs

In the article, a practical example of using the Autodesk Inventor Professional iLogic tool for designing self-propelled drilling rigs has been presented. Self-propelled drilling rigs are advanced mining machines with a complex structure. At the design stage, most of the structural changes affect the stability, manoeuvrability and coverage area of the machine. Working on detailed machine models is timeconsuming and unnecessary in the initial phase of the project. Therefore, a parametric 3D model of a two-boom drilling rig has been developed. It enables a quick analysis of selected machine properties depending on a number of significant parameters. The most important dimensions, masses and centres of gravity of each subassembly are entered by transparent editing windows. Next, model tests are carried out taking into account the pass through a face end of a given width as well as the coverage area of a face with specific dimensions. At each stage of model tests, the location of the machine's centre of gravity against the stability triangle background is analysed. In addition, the model allows entering the longitudinal and transverse angles of inclination of the working as well as determining the distance of the centre of gravity from the tipping edge. The model is a practical tool that makes it possible to easily determine the inner and outer turning radius as well as the working area of the machine while constantly controlling its stability. Due to the use of simplified geometry of subassemblies, the changes in parameters result in an instantaneous change of the model and allow a quick analysis of their impact

Digital Prototyping on the Example of Selected Self-Propelled Mining Machines

The changing requirements and needs of users as well as the demand for new mining machinery solutions pose a challenge for designers. Time spent on the design phase of a new machine is often reduced to a minimum. Small lot production and sometimes single piece production entails the necessity to frequently design and manufacture commercial copies, which are also prototypes. The only effective solution is to apply available CAD and CAE programs enabling digital prototyping. Their use allows for making a complete machine in a virtual environment. The virtual model is subjected to tests aimed at eliminating collisions, optimizing the construction as well as obtaining a lot of information concerning the load, kinematics, dynamics, stability and power demand. Digital prototyping enables avoiding the majority of errors whose detection and elimination in a real object is time-consuming and expensive. The article presents examples of the application of broadly understood computer aided designing of self-propelled mining machines, produced by Mine Master. The effects of applying the modelling, FEM strength analysis, static and dynamic simulations, modelling of drive systems have been demonstrated. The methods used to validate computer models and verify the parameters of finished machines have also been discussed

Support system for articulated drilling rigs stability evaluation

Samojezdne maszyny górnicze takie jak kołowo-oponowe wozy wiercące charakteryzują się budową przegubową oraz wyposażone są w wysięgniki z organami roboczymi wysuniętymi daleko poza obrys podwozia. Taka konstrukcja powoduje, że maszyny te są podatne na utratę stateczności. Stąd też konieczne jest analizowanie rozkładu mas oraz ich szeroko pojętej stateczności podczas całego procesu projektowania, przy uwzględnienie wielu czynników wynikających ze sposoby i warunków ich pracy. Jednak brak jest odpowiednich modeli obliczeniowych pozwalających na przeprowadzenie badań analitycznych dla maszyn o takiej konstrukcji. W artykule przedstawiono autorski system wspomagający szybką ocenę stateczności jedno i dwuwysięgnikowych wozów wiercących. Model pozwala na przeprowadzenie analiz bez konieczności rozwiązywania równań różniczkowych występujących w modelach dynamicznych oraz bez stosowania badań modelowych za pomocą narzędzi CAD/CAE. Opracowany model obliczeniowy został zweryfikowany przez porównanie uzyskanych wyników z wynikami z pełnego modelu dynamicznego, z wynikami badań modelowych przeprowadzonych w programie CAD/CAE oraz z wynikami badań empirycznych nacisków kół i podpór na podłoże dla wybranego wozu wiercącego. Na podstawie weryfikacji i walidacji tego modelu stwierdzono jego pełną poprawność oraz przydatność. Model został wykorzystany do opracowania praktycznego i łatwego w obsłudze arkusza obliczeniowego. Następnie przeprowadzono badania analityczne stateczności wybranego wozu wiercącego. Model obliczeniowy jak i arkusz kalkulacyjny stanowią podręczne narzędzie wykorzystywane podczas procesu projektowania przez jedną z polskich firm produkujących wozy wiercące.Underground mining machines, such as wheel-tyre drilling rigs, are articulated and equipped with booms that project far beyond the undercarriage. Such a structure makes these machines prone to lose stability. Hence, it is necessary to analyse the distribution of masses and geometry as well as their broadly understood stability during the entire design process, taking into account many factors resulting from the manner and conditions of their operation. However, there are no ap-propriate computational models that would enable carrying out analytical tests for machines with this kind of construction. The article presents the author's support system which allows a quick assessment of the stability of single- and twin-boom drilling rigs. The model makes it possible to perform analyses without having to solve differential equations present in dynamic models or using model studies based on CAD/CAE tools. The developed computational model was verified by comparing the obtained results with the results of the full dynamic model, the results of model tests carried out in the CAD/CAE program and the results of empirical tests of wheel and jack pressures on the ground for the selected drilling rig. Based on the verification and validation of this model, it was found to be fully correct and useful. The model was used to prepare a practical and user-friendly calculation sheet. Next, analytical tests of the stability of the selected drilling rig were carried out. The computational model and the spreadsheet provide handy tools used during the design process by one of the Polish companies producing drilling rigs

Methods to increase conical picks’ durability

Noże styczno-obrotowe są to narzędzia skrawające stosowane w wielu branżach, zwłaszcza górniczej, drogowej i budowlanej. Kontakt z urabianą calizną powoduje ich ciągłe zużycie. W artykule omówiono rozwiązania konstrukcyjne noży styczno-obrotowych, ich budowę, wymiary oraz stosowane materiały. Opisano zabiegi techniczne stosowane w celu zwiększenie ich trwałości, jak również regeneracji. Omówiono również autorskie, objęte zgłoszeniem o patent na wynalazek, sposoby wydłużenia czasu pracy noży w trudnych warunkach. Pierwsze z tych rozwiązań dotyczy zapewnienia niezakłóconego ruchu obrotowego noża w uchwycie. Zastrzeżenia patentowe obejmują nowatorskie łożyskowanie obrotowe dodatkowej tulei zintegrowanej z uchwytem, która umożliwia ciągły obrót noża. Uchwyt przeznaczony jest do mocowania klasycznych noży handlowych. Wymiana noża odbywa się bez ingerencji w węzeł łożyskowy. Drugie rozwiązanie dotyczy sposobu zabezpieczenia części roboczej noża za pomocą specjalnego elementu z materiału trudnościeralnego. Element ten stanowi ostrze noża o geometrii odbiegającej od standardowo stosowanych słupków z węglików spiekanych. W rozwiązaniu tym ostrze ma kształt odpowiadający formie zużycia noża styczno-obrotowego, przez co jego stalowy korpus nie zużywa się.Conical picks are cutting tools used in many branches, in particular in the mining, road construction and building branch. Contact with the excavated face causes their constant wear, which is an unfavourable but unavoidable process. In the article various solutions of conical picks, their construction, dimensions and materials used have been discussed. Technical procedures applied to increase the durability of conical picks and their regeneration as well as methods of extending the life of picks working in difficult conditions have been presented. Two author’s methods of extending the life of picks working in difficult conditions, covered by a patent application, have also been presented. The first solution involves ensuring an uninterrupted rotational movement of the pick in the holder. Patent claims include an innovative method of equipping the additional sleeve integrated with the holder with a rotational bearing, which enables a continuous rotation of the commercial pick. The pick replacement does not require interfering with the bearing assembly. The second solution concerns the manner of protecting the working part of the pick by means of a special element made of an abrasion resisting material. This element is the pick tip, the geometry of which varies from the commonly applied posts made of sintered carbide. In this solution, the tip has a shape corresponding to the form of conical pick’s wear, which causes that its steel body does not wear

Influence of the drill bit tip geometry on the rotary drilling process performed with a hand-held hydraulic drill

In the mining and construction industries, hand drills are used to carry out many processes related to excavation and auxiliary works. Hand drilling is commonly applied for making small diameter holes, especially in hard-to-reach places. In the case of manual drilling, an important parameter is drilling resistance, especially torque. Drilling tools are subject to wear, which has a negative impact on the process of drilling, including resistance and efficiency. A blunt tool lowers the drilling speed and puts more strain on the operator. The article presents the results of laboratory tests of selected parameters of the drilling process carried out with a hydraulic rotary drill. The tests were performed with the use of new drill bits as well as drills characterized by a various degree of wear. The tests were carried out for popular, frequently applied rotary drilling tools, on a unique laboratory stand that enabled setting the feed force and measuring the torque, rotational speed, drilling path, drilling speed as well as the in and out pressure of the drill. A number of characteristics were determined as a function of time and depth of the drilled hole. It was found that tool blunting affects the drilling process in various ways, whereas the intensity of this influence is determined by the type of blunting. The test results can provide a basis for developing a criterion for replacing a drill bit with a new one

The results of rock mechanical properties testing with respect to mining methodsl

W artykule przedstawiono tematykę związaną z często pomijanym wpływem kierunku urabiania na generowane opory urabiania skał. Na etapie prac związanych z rozpoznaniem złoża lub doborem sposobu eksploatacji przeprowadzane są badania określające własności mechaniczne calizny. Najczęściej przeprowadza się badania wytrzymałości na jednoosiowe ściskanie oraz czasami urabialności skał. Bardzo często wyniki tych badań silnie zależą od kierunku ich realizacji. Ponadto w zależności od sposobu urabiania (frezowanie, struganie, wiercenie) oraz miejsca pobierania próbek (ocios ściany, czoło lub ocios chodnika) kierunek skrawania zazwyczaj nie jest zgodny z kierunkiem realizacji badań. W artykule zwrócono uwagę na występujące w praktyce kierunki skrawania oraz przedstawiono, opracowane w tym celu dla górnictwa podziemnego, zalecenia dotyczące kierunku prowadzenia badań w celu prawidłowego określenia własności calizny. Zaprezentowano również autorskie wyniki badań węgla kamiennego, soli kamiennej oraz piaskowców, łupków i dolomitów, przeprowadzonych w trzech prostopadłych kierunkach. Ponadto dokonano przeglądu literatury w tym aspekcie, prezentując wybrane badania. Wyniki badań potwierdzają występowanie kilkukrotnych, czasami prawie pięciokrotnych, różnic wartości własności mechanicznych w zależności od kierunku obciążania. Wiedza dotycząca planowanego kierunku skrawania oraz kierunku realizacji badań jest warunkiem koniecznym prawidłowej interpretacji wyników i doboru techniki urabiania, rodzaju narzędzi, parametrów procesu oraz spodziewanej efektywności i energochłonności.The paper is concerned with the influence of cutting direction on rock cutting resistance, which is a frequently neglected issue. Investigations into the mechanical properties of unmined rock are carried out at the stage of works involving deposit identification or mining method selection. The most frequently performed tests include uniaxial compressive strength and, sometimes, mineability of the unmined rock. The results of these tests are strongly correlated with the direction in which they have been carried out. Additionally, depending on the method of mining (cutting, planning, drilling) and the site of sampling (sidewall, face), the direction of cutting is usually inconsistent with the direction of testing. In the article, the author has drawn attention to the commonly applied directions of cutting and presented recommendations on the direction of testing to be followed in underground mining plants in order to properly determine the unmined rock properties. The results of author’s research into hard coal mine, rock salt and sandstones, shales and dolomites, conducted in three perpendicular directions have also been quoted. Furthermore, the subject literature in this field has been reviewed and selected investigations presented. The research results confirm that depending on the cutting direction, there may be considerable, even fivefold differences in the value of mechanical properties. Knowing the planned cutting direction and the direction of testing is a necessary condition for interpreting the results in a proper way, choosing a suitable mining technique, the type of tools and process parameters, as well as achieving the projected efficiency and energy consumption

The analysis of shaft sinking progress as a function of technical and organizational parameters

In underground mines, where the deposit is located at considerable depths, mining shafts are key excavations. The project of making the deposit available requires selection of appropriate shaft sinking technology adapted to geological and hydrological conditions and natural hazards. Shafts can be made using the classic drilling and blasting technique or mechanical cutting of the shaft face. Mechanical cutting requires the use of a mining machine, which together with machines for loading and hauling the output and protecting the side walls is a shaft complex. Drilling using mechanized shaft complexes allows for high efficiency and work safety. To improve the efficiency of drilling, it is particularly important to implement many processes in parallel. The article presents an analysis of the progress of shaft sinking with a mechanized complex as a function of technical and organizational parameters. The analysis concerned a new generation cutting shaft complex, developed for the needs of shaft sinking for one of the Polish hard coal mines. The calculations were carried out for a shaft with a maximum diameter of 9.5 m and a total depth of 830 m. The article briefly presents a new solution for the shaft complex. There are presented results of calculations of daily drilling progress and total time of shaft sinking for the developed working technology of this complex. The efficiency of the complex depends on many factors related to technical parameters of individual machines and devices forming the complex and organizational parameters, hence a multi-variant analysis was carried out

Conical Picks for Undeground Mining

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

Directions for increasing conical picks’ durability

Conical picks are cutting tools used in many branches, in particular in the mining, road construction and building branch. Contact with the excavated face causes their constant wear, which is an unfavorable but unavoidable process. Milling heads of working machines are equipped with several dozen conical picks, and mining in abrasive or hardly accessible rocks can reduce their life to a few hours. It is in the interest of both users and producers to increase their durability, as tools replacement, apart from purchase and logistic costs, results in machine downtimes. In the article various solutions of conical picks, their construction, dimensions and materials used have been discussed. Technical procedures applied to increase the durability of conical picks and their regeneration as well as methods of extending the life of picks working in difficult conditions have been presented. Two author’s methods of extending the life of picks working in difficult conditions, covered by a patent application, have also been presented. The first solution involves ensuring an uninterrupted rotational movement of the pick in the holder. Patent claims include an innovative method of equipping the additional sleeve integrated with the holder with a rotational bearing, which enables a continuous rotation of the pick. The tool equipped with a bearing generates much lower movement resistance than the standard mounting. The holder is designed to mount classic commercial picks. What is important, the pick replacement does not require interfering with the bearing assembly. The second solution concerns the manner of protecting the working part of the pick by means of a special element made of an abrasion resisting material. This element is the pick tip, the geometry of which varies from the commonly applied posts made of sintered carbide. In this solution, the tip has a shape corresponding to the form of conical pick’s wear, which causes that its steel body does not wear. Moreover, there is a possibility of applying a mobile, rotational mounting of the tip to the body