Z. Pater

Multi-Wedge Cross Rolling of Balls

The multi-wedge cross rolling process of forming balls is described. The process tool for rolling 8 balls with a diameter of 35 mm is presented. The course of the rolling process, distributions of forming forces as well as maps of effective strain and temperature in the obtained balls are presented by finite element modeling (FEM). Experimental tests of simultaneous forming of 4 balls with a diameter of 22 mm conducted in laboratory conditions at Lublin University of Technology have proved that the balls obtained in multi-wedge cross rolling are of good quality and can therefore be used in both ball mills and rolling bearings.

Cross-Wedge Rolling of Shafts With an Eccentric Step

A new concept for forming eccentric shafts on the basis of the cross-wedge rolling (CWR) process was presented. This concept was based on the application of special guides, which, by acting on a billet, lead to its controlled movement in the vertical direction. This movement made possible eccentric cutting of tools into the billet. FEM calculations and experimental rolling tests clearly confirmed the effectiveness of the proposed forming method.

Cross-Wedge Rolling

The present study discusses the process of cross-wedge rolling (CWR), which is a modern way of using metal to form axially symmetric products. The work discusses in detail such problems as the CWR process principle and application fields of the process, main parameters of the process, advantages of CWR, CWR methods, kinematics of material flow, rolling radius, diameter increase of rolled parts, states of strain and stress, material–tool contact surface, unit pressure on contact surface, forces in the CWR process, CWR process limitations (uncontrolled slipping between material and tool, necking of formed parts, and internal cracking), wedge tool construction, choice of wedge angles, wedge tool construction methods, technological allowances and production tolerance, description of CWR technological methods, examples of applications of the CWR technology, and, finally, CWR machines.

Analysis of the Helical-Wedge Rolling Process for Producing a Long Stepped Shaft

Helical-wedge rolling (HWR) is a forming process wherein the wedges are helically wound on the roll face. Developed at the Lublin University of Technology (Poland), the HWR process has been successfully applied to produce balls. The present paper describes an example of application of the HWR process for producing a long stepped shaft. The design of the process is discussed and the tools necessary for its realization are described. The developed rolling concept was positively verified by a numerical simulation. The distributions of effective strains and temperatures in a shaft are given, and the variations in forming forces and torques are presented. Particular emphasis is given to the problem of production accuracy of the shaft.

Numerical Modeling of Cross — Wedge Rolling of Hollowed Shafts

In this article, the results of numerical calculations and experimental work of the cross‐wedge rolling (CWR) processes of hollowed shafts, realized with mandrels and without them, are presented. The results of numerical calculations for the CWR process of three rolls were also provided. On the basis of the calculations it was stated that the method of forming with the use of three rolls is the most appropriate for forming of hollowed shafts. This because in this process there is no excessive and irremovable ovalization of the normal cut, often observed in the process of rolling with two tools.

Cross rolling of parts with non-circular cross section

The aim of this paper is to present the possibilities of forming by means of cross rolling method (CR) of the parts with cross section different from circular one. In the paper the methodology of profiled tools forming is provided. These tools application allows for obtaining of parts with cross section in the shape of square, hexagon, oval, etc. The correctness of the worked out forming conception was confirmed by the results of numerical calculations and experimental research. Experiments were made in laboratory rolling mill LUW-2, parts from steel C45 type were rolled in hot forming conditions. Uniquely, it was stated that using profiled tools, parts in the form of stepped axles and shafts which have steps of non – circular cross section can be formed with satisfactory precision. The application in industrial conditions of profiled tools will allow for enlarging scope of CR technological possibilities and decreasing of material consumption.

Cross-Wedge Rolling of Driving Shaft from Titanium Alloy Ti6Al4V

This paper deals with the issue of the helicopter SW4 rear gear driving shaft forming. It was assumed that this shaft will be made from titanium alloy Ti6Al4V and it will be formed by means of cross-wedge rolling technology (CWR). It was also assumed that rolling will be realized in double configuration, which will guarantee axial symmetry of forming forces. The conception of tools guaranteeing the CWR process realization and numerical analysis results verifying the assumed CWR process parameters of the subject shaft were presented. Tests of shaft rolling in laboratory conditions at Lublin University of Technology were made, in the result of which the possibility of forming by means of CWR of a driving shaft, manufactured from titanium alloy Ti6Al4V, of the helicopter SW4 rear gear was verified.

Plastometric tests for plasticine as physical modelling material

Abstract This paper presents results of plastometric tests for plasticine, used as material for physical modelling of metal forming processes. The test was conducted by means of compressing by flat dies of cylindrical billets at various temperatures. The aim of the conducted research was comparison of yield stresses and course of material flow curves. Tests were made for plasticine in black and white colour. On the basis of the obtained experimental results, the influence of forming parameters change on flow curves course was determined. Sensitivity of yield stresses change in function of material deformation, caused by forging temperature change within the scope of 0&C ÷ 20&C and differentiation of strain rate for ˙ɛ = 0.563; ˙ɛ = 0.0563; ˙ɛ = 0.0056s−1,was evaluated. Experimental curves obtained in compression test were described by constitutive equations. On the basis of the obtained results the function which most favourably describes flow curves was chosen.

AN INNOVATIVE METHOD FOR FORMING BALLS FROM SCRAP RAIL HEADS

The paper describes a new method for forming grinding media balls from scrap rail heads. This forming method involves the following operations: cutting the rail head to the desired length combined with lateral pressing of the produced workpiece; flashless die forging and sizing of balls in a helical impression. The proposed method was verified by numerical simulation which involved the modeling of a forming process for producing 80 mm diameter balls. As a result of the modeling, it was possible to examine the changes in the workpiece shape during each forming operation, the variations in loads and torques, as well as the distribution of temperatures enabling performing another forming operation, i.e. quenching. The results confirm that the designed method can be used to produce balls.

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.