Papers by Keyword: Mandrel

Abstract: The present article discusses the cylindrical mandrel wear change during rolling using MISIS - 130 D mill depending on the type of rolled billets materials used. The research on the mandrel wear of the screw rolling mill during pipes elongation was carried out using the finite element method (FEM). The results of the wear modeling showed that the depth of the metal removed on the mandrel surface during stainless steel pipes elongation was higher as compared to alloyed and carbon steel pipes. The significant wear of the mandrel during stainless steel pipe rolling can be explained by the rise in the applied metal force resulting from the introduction of alloying components such as chromium and nickel into rolled billets materials. Consequently, the obtained modeling results can allow predicting the service life of working tools.

Abstract: In the forging industry, rolling is used to produce ring forgings, which are widely used in power and nuclear engineering. According to the technical conditions and established practice, large ring forgings are made using the operations of precipitation, piercing and rolling out with a striker on the mandrel.

Abstract: The article discusses the effect of epilamated coatings during mandrelling. The picture of the change in contact stresses in the DEFORM-3D system is presented. It was established that a decrease in the coefficient of friction from 0.9 to 0.6 leads to a decrease in the number of foci and areas of contact stresses, as well as temperature analysis showed that a decrease in the friction forces reduces heat transfer in the cutting zone by about 40 ° C.

Abstract: The paper discusses the specific aspects of hot rolled seamless pipes manufacture using pipe rolling plants including screw-rolling mills. The method of accuracy enhancement of pipe dimensions, as well as external and internal surface quality improvement, is proposed. The article specifies the results of computer and physical modeling of the pipes mandreling process. The application of the mandreling process within the cage using different diameter mandrels is shown. We managed to decrease the typical mark caused by the metal deformation, due to the screw-rolling mill and to manufacture pipes with more accurate dimensions, as a result of the mandreling process modeling. The results of the physical experiment on mandreling the shell pierced at the screw-rolling mill showed a positive effect from the process of hollow billet cold treatment using the mandrel.

Abstract: A theoretical investigation of the influence of the profile radius of the deforming roller on the limiting degrees of deformation in the process of flow forming is performed. Analytical and graphical dependencies allowing to determine the limiting degrees of deformation are obtained depending on the ratio of the profile radius of the roller to the initial thickness of the workpiece wall. The main practical ways of using the obtained dependences are considered. The results of the theoretical study are in good agreement with the known experimental data. The developed engineering technique can be used in designing the process of flow forming of cylindrical blanks by a torus roller.

Abstract: A 2D axi-symmetric finite element model for tube hot extrusion process has been established by consideration of the billet transfer, glass lubrication, constitutive equation of IN690 superalloy and modified Archard wear model. The influence of extrusion process parameters on the stress state and wear conditions of the mandrel surface has been investigated. The results show that under the optimal extrusion process parameters of the extrusion speed of 250 mm/s, the friction factor of 0.05 and the billet preheating temperature of 1250 ̊C, the mandrel can be reused 200 times when it is fixed and 500 times when it moves with the ram.

Abstract: Thermo-mechanical process simulation of an industrially pultruded rectangular hollow profile is presented. Glass/polyester is used for the continuous filament mat (CFM) and the uni-directional (UD) layers. The process induced residual distortions together with the temperature and degree of cure are predicted using a three dimensional (3D) thermo-chemical model sequentially coupled with a 2D quasi-static generalized plane strain mechanical model. The predicted deformation pattern at the end of the process is found to agree quite well with the one observed for the real pultruded parts in a commercial pultrusion company. In addition, the predicted warpage behaviour is further analysed by adjusting the mandrel length as well as including the mandrel heating. Using the proposed process model, the effect of the mandrel configurations on the quality of the pultrusion is investigated in terms of temperature, degree of cure and distortions.These unwanted residual distortions may lead to not meeting the desired geometrical tolerances e.g. warpage of pultruded window frames and hollow profiles as well as spring-in of L-shaped profiles, etc.

Abstract: Based on Abaqus/Explicit operation platform, a finite element model of Yantai Baosteel Φ460mm PQF mill was established to study the mass scaling factors influence of the rolling process. The experimental results show that mass scaling factor has smaller impact on the temperature. Distortion of rolling force and Mises stress gradually occurs with the increase of mass scaling factor. Under the premise of ensuring the calculation accuracy, a best mass scaling factor is found to improve the computational efficiency of the model.

Abstract: The cold-working expansion methods are extensively used in the aerospace and mechanical industry to obtain forced couplings of steel bushings into holes made on mechanical components, by means of the passage of an oversized mandrel. This work describes a calculation algorithm, able to correlate the selected interference level, as the difference between the maximum radius of the mandrel and the inner radius of the bushing, to the residual stresses expected on the hole surface. The designer, taking into account the different design choices already made, can choose the optimal interference, estimating the uncoupling resistance and the fatigue strength of forced components. Two original and different systems bushing-mandrel, in low and high interference, have been tested for determining the characteristics of fatigue resistance in the finite life part of the Wohlers diagram.The results have been compared with previously estimated data, getting a good agreement of the series. The increase of the adopted interference value determine a corresponding increase of residual stresses on the hole, both in the radial than in the circumferential direction, and an appreciable and predictable improvement of the fatigue strength of components.

Abstract: A Soft bending pipe is widely used for freezing equipment and shipbuilding. This pipe has some problems such that outside wrinkle, crack, phenomenon of thinning wall. However, the bending machine that can completely solve the problems is not yet. In this study, we have manufactured the self-made mandrel to guarantee both roundness and thickness of the pipe in the bending process for a soft pipe such as a copper pipe. The mandrel consisted of a ball, stick and connection pin. Also, we have manufactured the bending machine that can decrease friction between the pipe and the bending die. The experiment was tried to verify the performance of the mandrel and the pusher to the thickness guarantee of the pipe.