December 2010

These papers were presented at X. International Symposium FORM 2010, Brno


MM (Modern Machinery) Science Journal, December 2010
K. Podaný, R. Samek, K. Matousek
Brno University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Dept. of Metal Forming and Plastics, Brno, Czech Republic

The paper deals with characteristics of plasticity and strength of tubes materials. Tested where samples with and without the seam weld, annealed and without annealing. Ideal position of the welded wall was studied with respect to neutral axis shift. This being closely connected with the mode of bending when super imposed forces are added. Analysis of the bending forces mechanics and bending stress distribution was also discussed. Examined were also the cross section distorsions and the stabilizing effect of sharp edges.

Keywords: tube bending, material characteristics, square cross section, weld position, section distorsion, bending forces
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MM (Modern Machinery) Science Journal, December 2010
M. Slais, M. Forejt, M. Knebl
Brno University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Dept. of Metal Forming and Plastics Brno, Czech Republic

This paper deals with innovation possibilities in the measurement of dynamic forces that act on the specimen during the Taylor anvil test. The goal of this work is to decrease the influence of unwanted noises in the pulse record. The Quartz Force Link piezoelectric sensor by Kistler was used to compare the waveform of shock loading with signals recorded by foil resistance strain gauges by Hottinger. The impact loading was produced by impact of specimen on the measuring rod.

Keywords: Taylor Anvil Test, high strain rate, impact loading, strain gauges
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MM (Modern Machinery) Science Journal, December 2010
E. Spisak, J. Hudak, M. Tomas
Department of Technologies and Materials, Faculty of Mechanical Engineering, Technical University in Kosice Slovak Republic

Contribution deals with process formability evaluation of TRIP and HSLA steels, that were compared to typical deep drawing quality steel DC06. Process formability evaluation was performed by cupping test. Limit drawing ratio was used as a process formability criterion and drawing forces were measured during cupping test. There was used experimental-mathematic method for limit drawing ratio identification. HSLA steel H220PD with thickness 0,80 mm, TRIP steel RAK40/70 with thickness 0,75 mm and drawing quality steel DC06 with thickness 0,85 mm were used as experimental materials.

Keywords: deep drawing, process formability, AHSS steel, limit drawing ratio
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MM (Modern Machinery) Science Journal, December 2010
P. Fila1, M. Balcar1, L. Martinek1, P. Suchmann2, J. Krejcík3, L. Jelen4, E. Psik5
1 ZDAS, a. s., Zdar nad Sázavou,Czech Republic
2 COMTES FHT a.s., Plzen, Czech Republic
3 SVUM, a. s., Praha, Czech Republic
4 Vitkovice – vyzkum a vyvoj – technické aplikace, a. s.,
Ostrava – Vitkovice, Czech Republic
5 Kovarna VIVA, a. s., Zlin, Czech Republic

Tool steels used for forging dies are mostly made from medium and high alloyed steels. In terms of their use at forging these steel grades are divided to grades for hammer dies and steel grades for forging press dies. In case of grades for hammer dies high toughness is required above all and alloying conception depends on it (mostly based on nickel with chromium, molybdenum and possibly vanadium). In case of forging press dies the spectrum of the available properties is wider and individual steel grades are more dissimilar from each other according to usage of specific type of die or forging. Basically in these cases of dies an optimal combination of hot strength, toughness, resistance to tempering and other properties are required. This article presents new alloying conceptions of steel grades for dies concerning the grade 1.2343, which are produced in the company ŽĎAS, a.s. By modification of chemical composition and by corresponding metallurgical processing followed by special forging process very good combination of hardness toughness and abrasion resistance was reached. Dies are tested in production conditions in the forging plant Kovárna VIVA a.s. and the lifetime is on average approx. by 50 – 100% higher then that of the standard tool steel grade X38CrMoV5–1, (W.Nr. 1.2343).

Keywords: tool steel, die forging, hardness and abrasion resistance, resistance to wear.
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MM (Modern Machinery) Science Journal, December 2010
B. Masek, D. Aisman, P. Hronek, H. Jirkova, S. Jenicek
University of West Bohemia, The Research Centre of Forming Technology – FORTECH Plisen, Czech Republic

Innovative technological processes can help us to obtain unconventional structures with specific mechanical properties, even from conventional materials. Forming metal alloys in the semi-solid state is one of many ways. With thixoforming the tool steel X210Cr12 was treated with rapid solidification from the liquid phase. The microstructure after processing in the semi-solid state is 96% globular austenite formations surrounded by a carbide network. The aim of the experiment was to test the new technological process and to describe the obtained microstructure and its stability. The stability of the microstructure was tested under various thermal constraints and mechanical loading. The hardness of the austenite component after thixoforming was about 320 HV 0.05; hardness of the carbide network was about 550 HV 0.05.

Keywords: thixoforming, Semi-Solid forming, rapid cooling, metastable austenite, tool steel
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