Wyniki wyszukiwania - Biblioteka Nauki

1

FEM modelling of a helical wedge rolling process for axisymmetric parts

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Pater Z. , Tomczak J.

Advances in Science and Technology. Research Journal

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2018

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tom Vol. 12, no 1

115--126

EN

The paper reports the results of a numerical analysis of helical-wedge rolling (HWR), a new metal forming method developed at the Lublin University of Technology. The numerical analysis was performed for three axisymmetric parts: a rotary cutter body, a stepped shaft and a ball pin. The numerical modeling was performed using the commercial simulation software Forge NxT 1.0. The paper examines changes in workpiece shape as well as variations in effective strains, temperatures, damage function, force parameters (on the rolls and guides), and torques acting on the rolls. It has been found that due to its advantages (low material losses and high efficiency), the new helical-wedge rolling process can be used as an alternative to currently employed methods for producing axisymmetric products.

2

Nowy proces walcowania skośnego prętów o przekroju kołowym z główek złomowanych szyn kolejowych

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Tomczak J. , Bulzak T. , Pater Z.

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tom Vol. 86, nr 3

67--71

PL

W artykule przedstawiono wybrane wyniki modelowania numerycznego procesu kształtowania prętów o przekroju kołowym z główek złomowanych szyn kolejowych. Do realizacji technologii zaproponowano dwuetapowy proces walcowania. W pierwszym etapie główki szyn zgniatane są w walcarce wzdłużnej w wykroju sześciokątnym, co pozwala na uzyskanie w miarę regularnego kształtu przekroju poprzecznego wstępniaka. W drugim etapie wstępniak zostaje poddany procesowi walcowania skośnego w trójwalcowej walcarce skośnej. Obliczenia procesu walcowania przeprowadzono metodą elementów skończonych w programie FORGE NxT. W trakcie symulacji określono kinematykę płynięcia materiału, wyznaczono rozkłady temperatury, intensywności odkształceń, kryterium zniszczenia wg Cockrofta-Lathama, a także przebieg parametrów siłowych podczas walcowania. Uzyskane wyniki obliczeń wskazują na możliwość wytwarzania zaproponowaną technologią prętów o wysokiej jakości z główek odciętych od wyeksploatowanych szyn kolejowych. Zaletą proponowanej technologii jest możliwość walcowania prętów o przekroju kołowym w szerokim zakresie średnic jedynie w dwóch przepustach.

EN

The paper presents selected results of the numerical modelling of a new rolling process for producing circular-section rods from heads of scrap railway rails. The proposed technique involves two-stage rolling. In the first stage, the rail heads are roll formed in a longitudinal rolling mill with a hexagonal impression, which ensures obtaining a relatively regular shape of the cross section of the billet. In the second stage, the billet is subjected to skew rolling in a three-roll skew rolling mill. The numerical modelling of the rolling process was performed by the finite element method using FORGE NxT. The following were determined in the simulation: the kinematics of metal flow, the distributions of temperatures and effective strains, the Cockcroft-Latham ductile damage criterion, as well as variations in the force parameters during rolling. Obtained results demonstrate that the proposed technique can be used to form high-quality rods from heads of scrap railway rails. An advantage of the proposed rolling method is that it enables the production of circular-section rods with a wide range of diameters by means of only two roll passes.

3

Numerical simulation of a cross-wedge rolling process in a mill with horizontally stacked rolls

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Pater Z. , Bulzak T. , Tomczak J.

Mechanik

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2022

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tom R. 95, nr 5-6

54--58

EN

This paper presents simulations of the cross wedge rolling (CWR) process of a railway axle. It is assumed that the rolls are arranged horizontally, which should facilitate both the loading of the charge and the unloading of the rolled product. Simulations were performed in the Forge® programme, based on the finite element method (FEM). It was found that the adopted rolling scheme and design of wedge tools ensures the achievement of a correctly formed railway axle, free of internal (cracks) and external defects (overlapping, bending). The force parameters determined in the simulations can be used in the design works of the rolling mill guaranteeing the railway axle forming process.

PL

Przedstawiono symulacje procesu walcowania poprzeczno-klinowego (WPK) osi kolejowej. Przyjęto, że walce ułożone są poziomo, co powinno ułatwić zarówno załadowanie wsadu, jak i wyładowanie odwalcowanego wyrobu. Symulacje wykonano w programie Forge®, bazującym na metodzie elementów skończonych (MES). Stwierdzono, że przyjęty schemat walcowania oraz konstrukcja narzędzi klinowych zapewniają uzyskanie prawidłowo ukształtowanej osi kolejowej, wolnej od wad wewnętrznych (pęknięć) i zewnętrznych (zawalcowań, wygięć). Określone w symulacjach parametry siłowe można wykorzystać w pracach projektowych walcarki zabezpieczającej proces kształtowania osi kolejowych.

4

Numerical and experimental study on forming preforms in a CNC skew rolling mill

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Pater Z. , Tomczak J. , Bulzak T. , Walczuk-Gągała P.

Archives of Civil and Mechanical Engineering

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2022

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tom Vol. 22, no. 1

art. no. e54, 2022

EN

This paper relates to a study on the formation of elongated preforms in a CNC skew rolling mill. First, a numerical analysis was performed to investigate forming processes for three different parts: a scraper, a connecting rod, and a hook. The shapes and dimensions of preforms were designed, and rolling and closed-died forging processes for producing these parts were simulated numerically. Distributions of temperature, effective strain and damage function were determined for rolled preforms. Loads and torques in the rolling process were measured. It was found that the forming process of preforms performed in a CNC skew rolling mill was characterized by relatively low force parameters in relation to the dimensions of formed parts. Numerical simulations of the forging process showed that all forged parts had the required shape, which indicates that the preforms were designed correctly. Following the numerical analysis, experiments were performed in which the preforms were rolled under laboratory conditions (in a scale of 1:2). Experimental results demonstrated that the rolled parts had no internal defects (cracks) and were characterized by high dimensional accuracy.

5

Walcowanie śrubowo – klinowe

80%

Bulzak T. , Tomczak J. , Pater Z.

Hutnik, Wiadomości Hutnicze

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2020

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tom Vol. 87, nr 1-2

22--24

PL

Walcowanie śrubowo-klinowe (WŚK) jest technologią stosowaną w produkcji wyrobów osiowosymetrycznych. W procesie tym wykorzystuje się narzędzia klinowe, które wcinają się w kształtowany materiał wprawiając go w ruch obrotowy. Rozszerzający się klin powoduje stopniowe redukowanie średnicy wsadu do średnicy wyrobu finalnego. Klin do walcowania śrubowo-klinowego jest nawinięty wzdłuż linii śrubowej na powierzchni walca. Rozwiązanie to pozwala kształtować wyroby osiowosymetryczne w sposób ciągły z jednego odcinka pręta. Proces charakteryzuje się bardzo dużą wydajnością i znajduje największe zastosowanie w produkcji stalowych kul. W artykule opisano konstrukcję walcarek stosowanych w procesie walcowania śrubowo-klinowego. Przestawiono również na przykładach możliwości technologii walcowania śrubowo-klinowego. Opisano proces walcowania kul stosowanych na mielniki do młynów kulowych. Przedstawiono proces walcowania prętów z wyrobów o przekroju niesymetrycznym takich jak główka szyny kolejowej. Pokazano również możliwości walcowania odkuwek osiowosymetrycznych na przykładzie walcowania sworzni kulistych.

EN

Helical wedge rolling (HWR) is a technology used for manufacturing axially-symmetric products. Wedge tools used in this process cut into the formed material and, as a result, set it in rotational motion. The widening wedge causes the diameter of the billet to gradually decrease. The wedge used in the helical wedge rolling process is wound along the helix on the surface of the roll. This method allows one to manufacture axially symmetric products uninterruptedly from one section of a rod. The process is highly effective and is most widely applied in production of steel balls. The design of rolling mills used in the helical wedge rolling process was described. The article presents examples of the possibilities of helical wedge rolling. The process of rolling balls used as milling elements in ball mills was described. The process of rolling rods from products with asymmetric cross-section, such rail heads was presented. Moreover, the possibility of rolling axially symmetric forgings was presented on the example of ball pin.

6

The Problem of Material Fracture Prediction in Cross Rolling Processes

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Pater Z. , Tomczak J. , Bulzak T. , Zniszczyński A.

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tom Vol. 12, no 4

184--189

EN

The paper deals with the problem of material fracture prediction in metal forming processes. It was found that the application of well-established solutions for ductile fracture prediction to the modelling of cross rolling processes leads to serious errors. These errors result from the fact that the limit value of the damage function determined via uniaxial tensile and compression tests is too low. Therefore, it is necessary to devise a new test in which the state of stress is similar to that in a cross wedge rolling process characterized by the occurrence of alternating compressive and tensile stresses.

7

Walcowanie śrubowe kul na gorąco i ciepło – analiza porównawcza

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Bulzak T. , Tomczak J. , Pater Z.

Hutnik, Wiadomości Hutnicze

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2019

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tom Vol. 86, nr 10

305--308

PL

Artykuł przedstawia rozważania dotyczące procesu walcowania śrubowego kul łożyskowych. Analiza teoretyczna oparta jest na wynikach symulacji numerycznych. Symulacje numeryczne przeprowadzono w oprogramowaniu Forge NxT. Przeprowadzone symulacje dotyczyły walcowania kul ∅42 mm ze stali 100Cr6. W zaplanowanych badaniach dokonano analizy wpływu temperatury walcowania. Przenalizowano stan odkształcenia podczas walcowania w różnych temperaturach. Wyznaczono parametry siłowe procesu walcowania w niższych temperaturach. Określono zużycie energii potrzebnej do nagrzewania wsadu przy walcowaniu na ciepło oraz gorąco. Przeprowadzono również analizę porównawczą zużycia walców śrubowych w zależności od temperatury walcowania. Zwrócono uwagę na jakość kształtowanych elementów oraz utrudnienia wynikające z walcowania w niższych temperaturach.

EN

The article presents considerations regarding the process of helical rolling of balls bearings. Theoretical analysis is based on the results of numerical simulations. Numerical simulations were carried out in the Forge NxT software. The simulations carried out concerned rolling of ∅42 mm balls made of 100Cr6 grade steel. The planned studies have analyzed the influence of the rolling temperature. The state of strain during rolling at different temperatures was carried out. The force parameters of the rolling process at lower temperatures were determined. The energy consumption needed to heat the billet during warm and hot rolling was determined. Comparative analysis of the wear of helical rollers was also carried out depending on the rolling temperature. Attention was paid to the quality of balls elements and difficulties resulting from rolling at lower temperatures.

8

Multi-Variant Analysis of the Cross Wedge Rolling Process for Producing Railcar Axles

80%

Pater Z. , Tomczak J. , Bulzak T. A.

Advances in Science and Technology. Research Journal

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2023

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tom Vol. 17, no 5

208--219

EN

This study investigates the cross wedge rolling (CWR) process for manufacturing a rail axle in a scale of 1:6. Three cases of the rolling process are modelled numerically: standard rolling, wasteless rolling and rolling from a preform. The rolling cases under analysis are compared in terms of material and energy consumption, forming loads as well as propensity to internal and external defect formation. Using the Cockcroft-Latham criterion and the limits of this criterion determined by the rotary compression test, an assessment was made of the propensity of the material to fracture during the rolling processes analysed. Based on numerical results, standard CWR is selected for experimental verification. Obtained experimental results confirm that CWR is an effective method for producing railcar axles that are free from both internal and external defects. The experimental and numerical results obtained confirm that cross wedge rolling technology can be successfully used under industrial conditions for the production of long axles or shafts.

9

A helical rolling process for producing ball studs

80%

Tomczak J. , Pater Z. , Bulzak T.

Archives of Civil and Mechanical Engineering

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2019

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tom Vol. 19, no. 4

1316--1326

EN

This paper presents the numerical and experimental results of a study investigating helical rolling of ball studs. First, methods for producing balls studs widely used in the automotive industry are discussed. Then, in light of the discussed manufacturing techniques, a helical rolling process for producing this type of parts is proposed. The idea of rolling stepped parts in skew rolling mills is presented and the design concept for helical tools is described. Next, numerical results of a helical rolling process for ball studs are presented. Theoretical considerations are based on the results of simulations performed by the finite element method using the FORGE NxT simulation software. The simulations involved examining metal flow, thermal parameters and force parameters in the process, as well as predicting material cohesion loss based on the distribution of the Cockcroft-Latham ductile fracture criterion. The numerical results were verified experimentally. In the experiments, the process was investigated with respect to potential failure modes. The correctness of the designed numerical models of helical rolling was assessed based on the shape of produced forgings and the distributions of force parameters. Obtained results demonstrate that helical rolling is an effective technique for producing ball studs, and the design concept for helical tools can be based on the solutions developed for wedge tools used in cross wedge rolling.

10

Prediction of Waviness Values in Skew Rolling Using Machine Learning Methods

70%

Lis K. , Pater Z. , Tomczak J. , Bulzak T. A. , Kusiak T.

Advances in Science and Technology. Research Journal

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2023

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tom Vol. 17, no 5

350--359

EN

Skew rolling with three rolls is used for producing axisymmetric parts. In this method, the tools are spaced every 120° on the circumference of the workpiece. They are also set askew relative to the rolling axis. Cross sectional reduction is made effective by moving the tapered rolls closer to or away from the center line of the workpiece. Experiments were conducted with variable initial conditions of the rolling process to examine surface topography of rolled parts. Obtained experimental results were then analyzed using machine learning methods in order to determine the most effective regression model with the highest coefficient of determination R2 for waviness prediction.

11

Design and technological capabilities of a CNC skew rolling mill

61%

Tomczak J. , Pater Z. , Bulzak T. , Lis K. , Kusiak T. , Sumorek A. , Buczaj M.

Archives of Civil and Mechanical Engineering

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2021

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tom Vol. 21, no. 2

524--540

EN

Results of a study investigating a skew rolling process for elongated axisymmetric parts are presented. Despite the fact that the skew rolling technique for producing such parts was developed and implemented in the mid-twentieth century, there are no studies on this problem. The first part of this paper presents the results of FEM modelling of skew rolling stepped axles and shafts (solid and hollow). The FEM analysis was performed using the MSC Simufact Forming software. The numerical simulation involved the determination of metal flow patterns, the analysis of thermal parameters of the material during rolling, and the prediction of cracking by the Cockcroft-Latham ductile fracture criterion. Force parameters of rolling solid and hollow parts were also determined. The aim of the FEM analysis was to determine initial design assumptions and parameters for the development of the skew rolling mill. Later on in the paper, a design solution of a CNC skew rolling mill for rolling parts based on their envelope profile is proposed. FEM strength test results of a mill stand, obtained with MSC. NASTRAN, are presented. Finally, the performance test results of the constructed rolling mill are presented. The experiments involved rolling real stepped shafts that were modelled numerically. Obtained results show that the proposed skew rolling method has considerable potential. The designed and constructed rolling mill can be used to perform the rolling process according to the proposed method, with the tool and material kinematics being controlled based on the set parameters of a workpiece envelope.