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Determination of Coal Cutting Forces Using the Cutting Head of POU-BW/01-WAP Device

Biały Witold, Fries Jiri, Galecki Greg

Multidisciplinary Aspects of Production Engineering

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2021

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Vol. 4, Iss. 1

281--289

EN

The paper presents a method for measuring and recording the forces involved in the coal cutting process. Moreover, a method for visualization of all forces involved in the cutting process was described. In the following part, the construction and principle of operation of a device for determination of forces involved in the cutting process (coal mining), referred to by the author as POU-BW/01-WAP, are presented. Resistance extensometry was used to measure the forces. This is the only device in the world that determines two of three force components that take part in the cutting process. For this purpose, two independent measuring blocks were used, which are strain gauges of force: cutting (Fs) and knife pressure (Fd). In order to register these forces, a real mining knife used in longwall shearer drums was applied – i.e. tangential-rotary. The equipment has the ATEX certificate allowing for operation in real conditions as a device intended for use in potentially explosive atmospheres – in accordance with the directive 94/9/EC. It has received many awards at world fairs for inventions and innovative solutions.

2

Technological Forecasting of Deformations in Flat Parts

Ivanova Tatiana N., Biały Witold, Fries Jiri, Nordin Victor

Multidisciplinary Aspects of Production Engineering

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2020

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Vol. 3, Iss. 1

1--12

EN

The deformation of a part occurring in the process of grinding directly influences its exploitation and quality parameters. The instability of shape and size, which occurs due to an imbalance of residual stress, can be the one of the major causes of deformation of a part. The decrease in stress slows down the deformation process. Considering the regularities of heat source intensity dependence on the grinding modes, it can be asserted that with increasing grinding depth and grinding wheel hardness, the value increases and it decreases with a growth in a speed of the part and the use of cooling. The higher the heat removal is and the better lubricant properties of the liquid are, the more significant the decrease in is. Changing these values allows regulation of the residual stresses. As a result of the research on determination of deformations, it is recommended to reduce thermal deformations by considering the geometric size of a plate to be machined, linear expansion coefficient of plate material and an allowance for nonflatness from thermal deformations. The value of nonflatness from thermal deformations is directly proportional to linear expansion coefficient of plate material and its square overall dimensions. At the same time, the value of nonflatness is inversely proportional to the plate thickness.

3

Research and development of laser engraving and material cutting machine from 3D printer

Durna Antonin, Fries Jiri, Hrabovsky Leopold, Sliva Ales, Zarnovsky Jozef

Management Systems in Production Engineering

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2020

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nr 1 (28)

47--52

EN

This article deals with the adjustment of a 3D printer for laser engraving and material cutting. The print head can be fitted with a solid laser diode module, which achieves a compact size while retaining its useful power. Two paths lead to the use of such a concept. It is possible to equip the existing print head with a module, which also brings a number of disadvantages such as, for example, the reduction of the printing space or the need for a suitable mounting design. A more elegant solution is to consider this in the design of a 3D printer and design a system to exchange the print heads for 3D printing and laser engraving. Such a solution allows full utilization of the workspace and simple installation of the effector for the required type of work. According to the installed power of the laser diode, it is possible not only to engrave but also cut material such as thin wood, veneer or acrylic glass. The use of such a machine is not only for graphic elements but for the creation of various stencils, boxes or simple models, which can be made up of plastic-burning pieces. The laser module is controlled by a driver, which is designed for the device. This is connected to a 3D printer control board. It is, therefore, necessary for the control board to have at least two pins, which can be controlled after adjusting the control firmware. Most laser modules are normally equipped with an adjustable lens, which is used to concentrate the focus of a laser for the given distance against the worktop. Thus, the modified 3D printer can perform its function as a multi-purpose CNC machine, while a basic platform similar for both devices is used.

4

Gravitation Auger Water Separator from a Suspension of Wet Bulk Material

Hrabovský Leopold, Durna Antonin, Fries Jiri, Režnar Jiří

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

58--67

EN

The paper deals with the problem of water separation from a mixture of wet loose material using a worm, or auger, dewaterer, whose working element is a full auger with variable thread pitch, rotating in a fixed trough. The extrusion of water from the wet material suspension, consisting of a mixture of mineral wool tufts and granules, is effected in the auger dewaterer by entraining and compressing the wet bulk material through the threads, the varied pitch of the conical screw, and the rotation of the auger.The thread faces and thread edges of an improperly designed screw of the auger dewaterer by Advanced Metal Powders s.r.o. showed notable wear from the applied pressure of the packed wet bulk material (passing through the threads of the different pitch of the conical auger). Finding the cause of the severe abrasion and preventing excessive further wear of the auger was the subject of theoretical calculations and experimental verification tests, whose main conclusions are presented in this paper. The paper gives the relations that allow calculation of the volume of bulk material in individual sections of the auger dewaterer. The calculated values from these relationships, were verified and compared with the values read from the 3D CAD system for designing SolidWorks Premium 2012 SP 5.0 models.The percentage compression values of the loose material in the threads of differential pitch of the conical auger of the unsuitably designed auger-screw dewaterer by Advanced Metal Powders s.r.o. allowed us to define recommendations that, applied, would ensure malfunction-free operation of the auger-screw dewaterer.

5

Influences on plasma cutting quality on CNC machine

Kudrna Lukas, Fries Jiri, Merta Marek

Multidisciplinary Aspects of Production Engineering

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2019

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Vol. 2, Iss. 1

108--117

EN

This article discusses plasma cutting technology and its influences on the quality of the resulting cut. Plasma or a plasma arch consists of positive and negatively charged particles, excited and neutral atoms and molecules. As it contains free particles, it is electrically conductive and thus subject to the effects of the electrical and magnetic field. The basis of CNC machine design is described in the article, which has at least 3 axes (x, y, z), but there are also more technologically demanding applications, such as pipe cutting, profile and cutting using chamfer to prepare surfaces for welding, where these multi-axis devices are frequently used. The principle of plasma cutting and the plasma cutting phase is described in this article. The materials that can be divided by a plasma arc are described in detail, including graphs displaying the dependence of sheet thickness on the cutting speed. The article describes and lists the gases that are used in plasma-arc cutting, such as oxygen, argon, hydrogen and nitrogen. Important components of plasma cutting technology are the parameters that can be adjusted and set before the cutting so that the cut is of good quality. The most comprehensive chapter deals with the influences that affect plasma cutting quality. Cutting quality can be influenced by a number of factors. Everything starts with the proper choice of a CNC machine and a plasma source. The quality also depends on the expertise and experience of the machine operator and the setting of the plasma cutting parameters. This issue of influences on the plasma cutting quality is based on long-term experience in the field of the thermal cutting process.

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Computer systems supporting the management of machines/equipment in hard coal mines. Case study

Biały Witold, Fries Jiri

Management Systems in Production Engineering

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2019

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nr 3 (27)

138--143

EN

Computer systems supporting the management of machines operation and maintenance in companies have been successfully applied in many branches of industry. Over the last few years these systems have been considerably transformed. It also seems that using them for operating mining machines in hard coal mines is inevitable, as maintenance generates high production costs. If implemented, the systems will allow for optimization of stocks, spare parts and materials, supplies, outsourced services as well as maintenance-repair works. Application of a system supporting the management of mining machines/equipment will also enable a better, more effective use of employees. As a result of these actions, the time needed for preparations and repair will be shortened, which will translate directly into the economic effects of mines.