The cold drawing process takes places very quickly and during the conversion of mechanical energy into the heat energy the work peace and the tool heat up considerably. In order to achieve a stabile drawing process, it is necessary to keep tracks of the temperature growth of the work piece and the tool. The tool temperature has to be below the established limits, and it is regulated by the amount of the coolant, which is at the same time also a lubricant. The expressions for the temperature growth calculation in the conditions of adiabatic processes that can also be applied to the deep drawing process with the reduction of the wall thickness, due to the high deformation rate, have been presented in the work. The heat balance equation enables the determination of the coolant mass which will maintain the stabile tool temperature, what is confirmed by the experimental researches.

In the project phase of one multi-stage metal forming process special attention should be placed on maximal logarithmic strain φmax which can be achieved in one operation. Value of this strain has direct impact on number of needed operations (forming steps), number of heat treatments between certain steps, duration of the whole process, quality of the workpiece and on the die life. Amount of φmax in one forming process can be determined theoretically, based upon the stress state analysis, and by experiment. Experimental investigation within this paper have shown that stability of one multi – stage process like ironing, depends to great extent on re-distribution of strain values between the single dies. Improper distribution can lead to the cracks at the workpieces and other production failures.

In this paper we describe simulation of deep drawing process with discretized drawbeads. Due to CAD modelling simplicity and computational efficiency, in case of shallow parts drawing it is usual to use analytical or equivalent drawbead model. Unfortunately, in some cases, particularly in deep drawing of non-symmetric parts with increased depth, this simulation approach cannot lead to accurate predictions. Besides its complexity, more reliable results can be obtained by discretised model. We present such a drawbead model with triangular shell elements. By comparing numerical and experimental results, we show that discretized drawbead model leads to better predictions of deformations and deep drawing force.

Deep drawing of complex, non-symmetric shapes is often related with problems with wrinkling and excessive thinning. Draw beads can be useful addition to drawing tool in such situations but its shape and positions are difficult to determine in advance. In this paper we describe experimental procedure of deep drawing force measurement in order to verify numerical simulation of deep drawing process of non-symmetric part using draw beads. Forces obtained by numerical simulations are compared with the ones obtained by specially developed resistance strain gage force sensors. We have analysed results and gave some recommendations.

Presence of neutralizing antibodies to Coxsackie B viruses (CBV) 1-5 were examined in 2885 human sera by the neutralization test. The most frequently detected antibodies were to B4 viruses (in 1495 sera--51.82%) and to B3 (1371--47.52%). Antibodies to other serotypes were found in lower percentage: to B1 in 387 samples (13-41%), to B2 in 404 sera (14%) and in B5 in 332 sera (11.5%). Presence of neutralizing antibodies to human CBV in heart diseases were also analysed in 67 serum pairs. In this group of examinees the antibody titer dynamics was found in 41.79% sera.