Profile Design of the Grooved Die and Rolling Force Prediction in the Cold Pilger Rolling Process

The objective of this study was to design the die groove profile and predict the rolling force produced when employing the variable curvature rolls and mandrel for manufacturing seamless pipes using the cold pilger rolling process. The parameters of the key process design were the diameter of the initial tube and final product, as well as the feed amount, reduction area, principal deformation zone, and roller radius. The rolling forces during the pilger rolling process were theoretically calculated to enable their prediction, and the characteristics of the cold pilger rolling process were identified. The calculated values were in close agreement with the experimental data. The die groove design is important in the prediction process because the dimensional accuracy of the tubes and the life of the dies are highly dependent on this design. The presented design method can be successfully applied to fulfill this objective. The tube shape and adequate tolerance can be attained by using the proposed design method. The mechanical properties of the pipe are evaluated by calculating the Q factor.

New material-saving technologies of pipe rolling on pilgrim units

In this work, based on the analysis of the process of hot pilger rolling of pipes of a wide range of sizes and grades from a round continuous cast billet, new and improved existing metal-saving technologies have been developed to reduce metal losses in the pilger head.Using scientific and patent sources of information in the field of pilger rolling and its mathematical modeling with the calculation of tables for rolling pipes of a wide range of sizes from a round continuous-cast billet with a diameter of 385-470 mm, metal losses into technological scrap on a pilgerstan are determined: a seed and a pilger head.On the basis of the results of the theoretical determination of metal losses in the process scrap on the pilgerstan: the seed and the pilger head, a forecast was made to reduce the weight of the pilger head, which was used to develop new material-saving technologies for pilger rolling of pipes, both thick-walled with D / S = 6 - 12.5, and thin-walled with D / S = 12.5 - 40. Metal losses in the pilger head are the main factor of increased metal consumption coefficients on pilger units, which reduces their competitiveness in comparison with other units when using round continuously cast billets as a starting material.The forecast for the reduction of metal losses in the pilger head made for the first time makes it possible to estimate the reserves for reducing the mass of the pilger head both by eliminating the underflow of the liner and trimming of the pipe end adjacent to the pilger head, and by means of individual parts of its profile part and predicting its decrease to the minimum possible size, ensuring the removal of the pipe from the mandrel using a gate device.To reduce the weight of the pilger head when rolling thick-walled pipes, it is recom-?ended to use improved technologies for butt-end rolling and rolling of the pilger head on the free section of the mandrel.The results of the studies and the proposed new material-saving technologies can be used on pilgrim units when rolling thick-walled (D / S = 6 - 12.5) and thin-walled (D / S = 12.5 - 40) pipes of a wide range of brands (carbon, alloyed, highly alloyed and special) from both continuous casting machine and forged and centrifugally cast billets, as well as ingots.

A deformation mode in a cold rolling condition to provide the necessary texture of the Ti-3Al-2.5V alloy

Purpose. Providing deformation conditions in order to obtain the required texture of pipes made of Ti-3Al-2.5V alloy based on the choice of rational values of the tool calibration parameters gauges and mandrels during cold pilger rolling of pipes for the required Q-factor distribution along the deformation cone. Methodology. The research methods were based on the existing dependence, which describes the influence of the distribution of the ratio of true reduction along the deformation cone along the wall thickness and along the average diameter, on the distribution of the Q-factor value. The calculation of calibration and all deformation parameters of the Cold Reducing tube process was based on a number of existing theoretical and empirical dependencies included in the generally accepted and adapted methods of their computation. To perform calculations, we created the software product Q-Factor. Cold pilger tube rolling. Findings. The influence of the initial taper of the mandrel with a curvilinear generatrix and the sweep of the groove ridge, the degrees of steepness of the generatrix of the mandrel and the sweep of the groove ridge, the value of the feed on the distribution of the Q-factor along the compression zones and pre-finishing of the deformation cone were investigated by calculation. The use of slope degrees n, equal to 1.5, i.e. less than values of crest slope degree had the most significant effect on obtaining the Q-factor close to equilibrium distribution along the length of wall reduction and pre-finishing zones. A method of multifactor calibration of the tool for cold pilger rolling of pipes is proposed, which makes it possible to select rational values of the initial taper of the mandrel with a curved generatrix, the degree of slope of the sweep of the groove ridge and the mandrel, and to create conditions in the wall compression zone for obtaining the required type of metal texture of cold-rolled pipes made of titanium alloy Ti-3-2.5V. At the same time, in the prefabrication zone, in all investigated cases, there is a drop in the Q-factor values below one. Originality. New knowledge was obtained about the influence of the rolling route and the full complex of tool calibration parameters in the process of cold pilger rolling of pipes on the distribution of the Q-factor along the length of the deformation cone. Practical value. A method for determining the modes of deformation with an extended compression zone and without a pre-finishing zone is proposed and tested with positive results. This method provides a distribution of the Q-factor along the reduction zone of the deformation cone which is close to uniform distribution and with values above one. The results obtained make it possible to select the conditions for obtaining the required type of metal texture of cold-rolled pipes from titanium alloy Ti-3Al-2.5V using the software product Q-Factor. Cold pilger tube rolling.

Minimizing the Dynamic Loads in Pilger Rolling Mill Forholler

For the newly proposed pneumohydraulic drive of workpiece return movement it is researched relations, analysis was carried out and recommendations of selecting values of the initial pressure in the pneumatic chamber, ensuring a rational ratio between the periods of acceleration and deceleration were obtained. A mathematical model and program were created for the calculation of the law of motion of the brake rod with floating piston device using the system variable throttling the flow of the working fluid along the movement in the brake chamber. Based on the developed model the numerical analysis is made to assess the impact of the inner surface of the brake axle box on the final rate of the brake piston, as well as the effect of the location and change in the area of additional throttling apertures therein on the trend values of the maximum braking acceleration of moving masses. An algorithm of determining the constants and variables control law of motion, minimizing the maximum values of dynamic loads per cycle movement of the workpiece is obtained. It is shown that the proposed framework of the rod system of the workpiece return movement in the working cage with a floating piston ensures reduce the moving masses and increases the rigidity of the movable rod. The calculated relations for the definition of effort mobile carriage prop, providing gapless its support with mechanism of feed limit, are obtained.