Grzegorz Winiarski

Theoretical and Experimental Research on a Method for Producing a Triangular Rosette-Shaped Flange

The paper presents a new method for forming a hollow shaft with a triangular rosette-shaped flange on its end. The part being investigated is used as a propeller shaft in helicopters. The product must be monolithic, therefore it cannot be produced by methods which consist in joining a flange with a tube. Up till now, such shafts have been produced by machining from solid barstock, the process which generates material losses exceeding 90%. The application of the proposed flanging method results in a significant reduction in both material and labour consumption, which leads to lower production costs. Due to beneficial texture of the shaft flange, shafts produced by this method exhibit better strength properties than shafts produced by machining. The paper presents the results of a numerical analysis of the flanging process, performed using DEFORM-3D software. Also, experimental tests were conducted using a three-slide forging press. Theoretical and experimental results obtained confirm the effectiveness of the new method for forming this part.

Theoretical analysis of the forging process for producing hollow balls

Hollow balls are used in the production of various machines and devices. The tech- nology for producing hollow balls by metal forming technologies poses numerous difficulties connected with the forming of a hollow billet. The billet, which is usually in the form of a rod, is subject to such processes as forging, helical rolling or cross- wedge rolling. The paper discusses a new method and conditions for producing a hol- low ball. It was assumed that the ball would be produced in two forging operations: an initial forging operation and finish forging operation. The presented results are based on the FEM numerical analysis conducted using DEFORM-3D. It was assumed that the billet material was made from AISI 304 stainless steel used to produce balls for ball valves. Both the shape progression during the forging process and variations in the forming force were analyzed. Based on the conducted analyses, it can be claimed that hollow balls can be produced using the proposed forging method.

Investigation of the Effect of Forging Temperature on the Microstructure of Grade 5 Titanium ELI

The paper reports the experimental results of an investigation of the effect of forging temperature on the microstructure and hardness of Grade 5 titanium ELI. A growing interest in the use of titanium alloys in implantology results from their unique properties. Grade 5 titanium ELI is widely used in medicine for producing a variety of implants and medical tools such as hip, knee and shoulder joints; bone plates; pacemaker casing and its components; screws; nails; dental materials and tools. In the first part of the paper the properties of Grade 5 titanium ELI are described and examples of medical applications of this alloy are given. In a subsequent section of the paper, forging tests performed on this biomaterial in a temperature range from 750°C to 1100°C are described. Following the forging process, the results of the titanium alloy’s microstructure and hardness are reported. The experimental results are used to determine the most suitable forging temperature range for Grade 5 titanium ELI with respect to its microstructure.

A study of a new screw press forging process for producing aircraft drop forgings made of magnesium alloy AZ61A

Purpose The aim of this study was to develop a die forging process for producing aircraft components made of magnesium alloy AZ61A using a screw press. Design/methodology/approach The proposed forging technique was developed based on the results of numerical and experimental research. The required forging temperature was determined by upsetting cylindrical specimens on a screw press in order to examine both plasticity of the alloy and quality of its microstructure. The next stage involved performing numerical simulations of the designed forging processes for producing forgings of a door handle and a bracket, both made of magnesium alloy AZ61A. The numerical modelling was performed using the finite element method-based on simulation programme, Deform 3D. The numerical results revealed that the forgings are free from material overheating and shape defects. In addition to this, the results also helped determine the regions which are most prone to cracking. The final stage of the research involved performing ...

FLOW STRESS MODEL FOR COLD-FORMED 40HM CONSTRUCTIONAL STEEL

The paper presents the results of research undertaken to investigate cold forming process for 40HM constructional steel suitable for heat treatment. In the first part of the paper, mechanical properties of this steel and its industrial applications are described. The second part of the paper presents the results of the analysis of flow curves for two kinds of steel specimens: those that were subjected to annealing and those that did not undergo any heat treatment. It was found that the application of heat treatment had a significant effect on improving the forming conditions for this steel at room temperature. The experimental flow curves obtained in a compression test were described by constitutive equations illustrating the dependence between flow stresses and strain value. In order to determine the equation coefficients, the Generalized Reduced Gradient method implemented in Microsoft Excel was used. Based on the obtained equations, a material model will be developed to perform numerical simulations of cold forming for 40HM steel, using FEM-based software that aids the design of metal forming technologies. Keyword: flow stress, 42CrMo4 constructional steel, cold forming.