Mannesmann Piercing Research Articles

MODELLING OF MATERIAL FLOWS IN PIERCING TECHNOLOGY

The article summarises the modelling of the technological process of Mannesmann piercing in the configuration of the GreatMannesmann rolling mill in the Tube Mill of Třinecké Železárny using the approach of both mathematical modelling and numerical simulation. In accordance with the mathematical model of the given process, the formation of the cavity during the rolling in the numerical range is replaced by pre-drilling a billet of a specific size given by the mathematical model. The numerical simulations have shown an absolutely fundamental effect of the distribution of the initial temperature field of the billet on the actual piercing process. The billet with the initial inhomogeneous temperature field was subject to very strong transverse oscillations and significant spiral structures appeared in the distribution of all physical quantities. When simulating the piercing process on the Mannesmann piercer in the Tube Mill of Třinecké Železárny, parameterised by a mathematical model so as to take into account in the best possible approximation the influence of the cavity initiation sequence during the actual piercing, the simulation results were completely consistent with the predictions of the mathematical model of the submitted process calibration.

ROLE OF SYMMETRY IN OPTIMIZATION OF FEM SIMULATION CALCULATIONS

At the studying the Mannesmann piercing process, we unify two approaches to the problem solving. Namely, the commercial FEM software procedure and the mathematical model of the process via the mathematical model of the considered FEM-simulation bound by certain unifying symmetries. Such phenomenon seemingly exists only if the FE-mesh is initiated to be physically interpreted. We shortly outline, how to come to the slightly modified Cahn-Hilliard equation as to the mathematical model of the FE-simulation possessing quasi-symmetry given by a lattice of colloidal assembly formed by the chosen FE-mesh. Separation of two cylindrical surfaces of the pierced product together with the inpainting role of the piercing plug are described with respect to the background given by the Navier-Stokes equations related to the flow between the both surfaces. Influence of the involved groups related to the considered quasi-symmetry is illustrated by the convergence/divergence of the Newton-Raphson number in the CPU-time.

On One Controllability of the Schrödinger Equation as Coupled with the Atomic-Level Mannesmann Effect

In this paper we outline a certain way of understanding of macroscopically uncontrollable emergence of the so called Mannesmann effect by means of its induced controllable quantum-mechanical background. In other words, we factually present a modus operandi of how to avoid macroscopic models of specific atomic-level cavity origin based consequently on a classical fracture mechanics theory. Under such circumstances, the target solution of the controllable microscopic model cannot be determined, since it can obviously arise only as a macroscopic state of the structurally disturbed rolled metal semi-product during the Mannesmann process. We obtain this irrelevance of the target solution, using a very special kind of control of the famous Schrödinger equation employed as a fundamental model equation here. We show contextually that such control follows from some very elementary aspects of the group theory conditioning a physical meaning of the Schrödinger equation written in a controllable form. We specially emerge primary cyclic groups of symmetry of special solutions to the Schrödinger equation. Their imaginary part is given by a control satisfying the Klein-Gordon equation which can be driven (through a specific avoidance of the cyclic group Z4) into a connection with the characteristic series of primary cyclic groups and/or torsion groups respectively. We obtain a physically controllable special results representing a strange correspondence between a certain LET (Linear Energy Transfer) and “quantum-like” tunnelling interpreted for some “everyday” objects, particularly for the considered Mannesmann piercing process with a torsion known from metallurgy. The process violations are shown and further reflected via a standard finite element method (FEM) simulation.

Computer Simulation of Mannesmann Piercing of Aluminium Alloy Ingots

The piercing of aluminium ingots (made by permanent mold gravity casting) is done in a Mannesmann rolling mill with supporting shoe using plugs of various shapes with a spherical working part: an entire plug, a plug with cavity, and a hollow plug. The calibrating segments of the plugs have identical diameters. The piercing is carried out at an ingot temperature of 400°C. The influence of the plug shape on the variation in the outer hollow shell diameter and wall thickness along the shell length, as well as shell density over the length, is investigated. Hollow shells were cut into 15 equal rings to measure density using hydrostatic weighing. Experimental investigations are simulated with the help of the finite-element method (FEM) computer software. Ingot fabrication by permanent mold gravity casting is simulated using the ProCAST software and piercing—using the QForm software. The variation in the hollow shell diameter, wall thickness, and shell density along the length is also evaluated by computer simulation. Experimental and simulation data are compared to verify the adequacy of acquired models in the QForm. The difference in density does not exceed 2% and, for hollow shell dimensions, 20%. These results make it possible to establish the influence of the piercing plug shape on the accuracy of the shells and their density. It is most preferable to use a hollow plug or a plug with a cavity from the viewpoint of dimension accuracy of fabricated shells. Each of these piercing schematics makes it possible to densify the entire hollow shell volume to the true density, except for the near-edge domains, where the density is lower by 1%.

FEM SIMULATION OF MANNESMANN PIERCING OF ALUMINUM ALLOY INGOTS

Mannesmann piercing of ingots, which were made of aluminum alloy by casting, was done using plugs of different shape: entire plug, plug with cavity and hollow plug. Plugs had same diameter of calibrating segment. Piercing was carried out at 400 °C ofbillets. Influence of plugs’ shape on variation of hollow shells’ diameter, wall thickness and density along their length was estimated. Hollow shells were cut into 15 equal rings to measure density using hydrostatic (Archimedean) weighing. Experimental operations were simulated using FEM computer software. Casting was simulated using ProCAST, piercing — using QForm. Variation of hollow shells’ diameter, wall thickness and density along their length was estimated after simulation had been done. Experimental and simulation data were compared to check FEM simulation accuracy. Difference between experiment and simulation for density was not more than 2 %, for hollow shells’ dimensions — 20 %. Conducted investigation allowed estimation of how plug’s shape affects hollow shells’ dimensions accuracy and density. It was established that hollow plug or plug with cavity, in terms of dimensions accuracy and density variation, are preferable for piercing. Each of plugs being used, provides manufacturing of hollow shells with maximum density for all volume except close to hollow shell’s edges domains, where density is 1 % less than maximum value.

Mannesmann piercing of ingots by plugs of different shapes

The purpose of the research reported here was to establish how plug shape influences the size and porosity of hollow shells produced by Mannesmann piercing of an ingot. Ingots were cast from 6060 aluminium alloy and then pierced with a solid plug, a plug with a cavity or a hollow plug. Computer simulation of these processes was carried out using ProCast and QForm software and showed that a hollow plug should produce hollow shells with minimal porosity. However, the results of the experimental piercing revealed that the hollow plug in fact produced hollow shells with higher porosity than that of shells produced using either of the other two plugs. This appears to be consequence of the hollow plug losing stability.

Experiments and Simulation on Mannesmann Piercing Process in the Drill Steel Manufacture

Steel drill rods are employed in the mining industry to drill blast holes in rock, for them a high-quality metal surface and accurate geometrical parameters are essential. Drill steel is a special material exclusively designed for drill rods. To estimate the microstructure and dimensional stability of drill steel, a rigid plastic finite element method (FEM) was applied in examining the Mannesmann piercing in the drill steel manufacture. The three-dimensional thermal-force coupling FEM models were computer-generated with different plug positions. The metal deformation during the piercing process was analyzed in detail. The stress-strain state of the metal ahead of the plug was simulated to obtain formation characteristics during the Mannesmann piercing. The effect of the plug position on force and strain rates was also studied with simulation. The results demonstrate that the dimensional stability of hollow drill rods can be enhanced by advancing the plug position.

Effects of Feed Angle on Mannesmann Piercing in Drill Steel Production

Drill steel is a special steel specifically tailored for drilling rods. To understand the microstructure properties and dimensional accuracy of the drill steel, a rigid plastic finite element method was used to analysis Mannesmann piercing in steel drilling production. The three-dimensional thermal force coupling FEM models were computer generated with different feed angle. The metal deformation during the piercing process was analyzed in detail. The influence of feed angle on deformation, force, velocity and strain was obtained through simulations.

Effects of Plug Position on Mannesmann Piercing in Drill Steel Production

To enhance the microstructure properties and dimensional accuracy of drill steel, rigid plastic finite element methods were used to analysis the Mannesmann piercing in drill steel production. The three-dimensional thermal-force coupling FEM models were built with different plug position. Influence of plug position on the force and strain rate is got through simulation. The results show that the dimensional accuracy of drill steel hollow can by increased by the amount of increase plug position.

On the modelling of complex 3D bulk metal forming processes via the pseudo‐concentrations technique. Application to the simulation of the Mannesmann piercing process

AbstractThe modelling of complex 3D metal forming processes using the flow formulation, implemented via the pseudo‐concentrations technique, requires the development of robust computational strategies for dealing with the velocity and pseudo‐concentration boundary conditions in the zone where the blank–tools contact is developed. A new algorithm, designed to fulfil those requirements, is presented in this paper.The Mannesmann piercing process is a metal forming operation used in industry for manufacturing metal seamless pipes. The results of the Mannesmann process finite element simulation are particularly dependent on the accuracy and stability of the algorithm used to describe the contact boundary conditions between the forming tools and the blank. The validation of the finite element model is performed by comparing the numerical predictions obtained using the new algorithm with the results of industrial tests. Copyright © 2005 John Wiley & Sons, Ltd.

Simulation of Mannesmann piercing process by the three-dimensional rigid-plastic finite-element method

Simulation of the Mannesmann piercing process is performed for the first time by the three-dimensional rigid-plastic finite-element method. Firstly, a method of analysis is proposed for the steady-state formulation in the case that the sides of the finite elements cannot be made to coincide with the streamline of the material flow. Secondly, the simulation of the Mannesmann piercing process is performed under the variation of rolling conditions such as the feed angle, the minimum roll gap, the maximum plug diameter, the plug advance and the guide shoe diameter, and the effects of the rolling conditions on various rolling properties such as the outer diameter, the inner diameter, the roll force, the mandrel force, the equivalent strain distribution and the equivalent strain rate distribution are demonstrated. Finally, the results of the analysis are compared with the results of an experiment using Plasticine. The dimension in the rolling condition of the experiment is scaled to one-third of the dimension in the rolling condition in an actual Mannesmann piercing process. The analytical results agree with the experimental results and the validity of the method of analysis is confirmed.

COMPARISON OF DOUBLE AND SINGLE PIERCING PROCESS IN SEAMLESS STEEL TUBE MANUFACTURE

An investigation work was made on the influence of the piercing process on the rotary forging effects, redundant shear deformations and power consumption. In this work, a study was made to compare the double and single piercing process with reference to the Mannesmann piercing mill and the cone-type piercing mill developed by the authors. If the conventional double piercing process employing the Mannesmann piercing mill is replaced by the single piercing process employing the cone-type piercing mill, the rotary forging effects and redundant shear deformations can be inhibited, and then, the materials with poor workability, such as stainless and high alloy steel can be pierced without inside bore defects. Furthermore, from the viewpoints of the piercing power and power consumption, the single piercing process employing the cone-type piercing mill is very economical. As a result, the single piercing process employing the cone-type piercing mill provides the best economical advantage with respect to both capital and running costs.

マンネスマンせん孔機による継目なし鋼管の製造について

マンネスマンせん孔機による継目なし鋼管の製造について