Effects Of Mandrel Research Articles

Influencing Variables of Drawing Process using Magnesium Tubes

The present work examines the deformation of magnesium tubes using drawing process. During examination, absence of wrinkling and cracking is witnessed at 303k. The effect of mandrel on the cross section of the extruded tubes, wall thickness and spring-back of the bent tube are vividly discussed. Results show that presence of mandrel decreases the cross section of distortion and the spring back angle. Further, the present investigation clarifies the thinning rate of tube wall thickness. It is found that at the bending angle of 90° largest distortion is witnessed.

Numerical simulation and experimental studies of mandrel effect on flow-compaction behavior of CFRP hat-shaped structure during curing process

CFRP hat-shaped structure is a typical stiffened structure used in aerospace field. In this work, aimed to provide a theoretical basis for manufacturing CFRP hat-shaped structure, the multi physical field coupling model considering influence of mandrel was established. Effect of mandrel on resin flow and fiber compaction during curing process was studied by simulation and experiment. Results showed that temperature and curing degree affected by mandrel can be negligible in hat-shaped structure, and the distribution of temperature and curing degree was relatively homogeneous. However, the behavior of resin flow and fiber compaction during curing process was not uniform. There was a larger gradient among resin flow, pressure, fiber volume fraction and laminate thickness. Presetting a suitable hole in mandrel can effectively improve the uniformity of resin flow and fiber compaction. By simulation analysis and optimization, the acceptable aperture of 11.5–12.5mm was obtained. Finally, the model and simulation developed in this study was validated by experiment. The reliability coefficient of 93.4–99.6% was obtained, which indicated a good agreement between simulation and experiment.

Formability limits and process window based on fracture analysis of 5A02-O aluminium alloy in splitting spinning

Splitting spinning or rotary flow splitting is an advanced forming process for manufacturing axisymmetric integrated parts with bifurcated features and unique characteristics of high-performance and low-weight. During the process, under the kinematic effects of mandrel rotational movement and roller radial feed, plastic deformation occurs accompanied usually by undesirable fracture, which reduces the formability limit (FL). In this study, the kinematic effects on the FL of a 5A02-O aluminium alloy in the splitting spinning process were systematically investigated by finite element simulation based on a modified Lemaitre criterion and physical experiments. The results show that at a given roller feed speed or mandrel rotational speed (forming speed), the FL has a nonlinear relationship with forming speed, which increases firstly and then decreases. With the increase of forming speed, the maximum FL decreases, which appears at the larger forming speed. These variations of FL show that there exists a combined effect of the roller feed speed and mandrel rotational speed, thus a ratio between them, named as the roller feed ratio, is then used to investigate FL. It is found that there exists a critical roller feed ratio of approximately 2 mm/rev, independent of the speeds of roller and mandrel. Below this critical value, the FL increases with the roller feed ratio. While over the critical value, the FL decreases. In addition, the decrease of FL becomes more remarkable with the increase of mandrel rotational speed. Furthermore, the variations of stress triaxiality and tensile plastic strain were analyzed to see their effects on FL. The analyses show that the decrease of tensile plastic strain with the increasing roller feed ratio is dominant the increase of FL below the critical roller feed ratio value. The increase in the stress triaxiality is dominant in the decrease of FL when the roller feed ratio is over the critical value in combination with not too high forming speed, whereas both increases are dominant in the decrease of FL when it is over the critical roller feed ratio value in combination with high forming speed. Based on the kinematic effects of mandrel and roller, the process windows of the splitting spinning process were obtained to improve the FL. It is found that under the condition of the roller feed ratio within 1–2.5 mm/rev, the mandrel rotational speed within 8–100 rev/min and the roller feed speed within 0.5–4 mm/s are helpful to get high FL values. The experiments were carried out to verify the prediction on the FL and the process window. The research provides an in-depth understanding of FL and its affecting factors, and thus lays a basis for process optimization and process parameter configuration.

A Stable Analytic Model for Tilted-Coil Antennas in a Concentrically Cylindrical Multilayered Anisotropic Medium

A set of compact and stable formulations is presented to calculate the response of logging tools employing tilted-coil antennas in anisotropic concentrically cylindrical multilayered formation. The presented formulations can be used to investigate the effect of mandrel, borehole, and invasion. Our formulations are different from previous ones in three aspects. First, the tool mandrel can be cylindrically multilayered, and electrical parameters of each layer are arbitrary. That is to say, the mandrel is not limited to being perfectly metallic. Second, the formation can be either anisotropic or isotropic. Finally, the propagation of electromagnetic wave in an inhomogeneous cylindrical medium is described by the generalized reflection and transmission coefficients without the numerical overflow issue. Numerical results in comparison with those from other approaches have demonstrated the validity and stability of our new formulations.

A study on mandrel role in rotary draw bending of rectangular tube

The mandrel die with cores is a significant factor affecting the forming quality of rectangular tube in rotary draw bending process. A new mandrel die is designed and manufactured, and the analytical formulas for the geometric parameters are deduced quickly and reasonably. 3D elastic–plastic FE model for the rotary draw bending process of rectangular tube employing the new mandrel die is established using ABAQUS. The model is validated to be credible and efficient by comparison with experiments, and the effects of mandrel die on the forming quality are investigated. It is shown that with the increase of core radius, core number and space length between adjacent cores, the thinning ratio increases, while the cross–section distortion ratio decreases. The larger mandrel extension induces larger thinning ratio and cross–section distortion ratio. When the core radius is large, the thickening ratio is small. Therefore, for the rectangular tube with dimensions 24.86 × 12.2 × 1 mm, the core radius 5 mm, extension length 0, space length 10 mm and core number 4 are selected to bend the rectangular tube with minor cross–section distortion and thickness changing ratio.

An Annular Rotating-Die Technique in Extrusion Process: Effect of Mandrel Rotating Speed on Extrudate Swell Behavior of HDPE Parison

Abstract This work aims to propose an annular rotating-die technique which is specifically designed and constructed in order for the mandrel to rotate in the stationary barrel during extrusion. The annular rotating-die was employed to study the effect of the mandrel rotating speeds on the extrudate swell behavior of HDPE parison in single screw extruder at a test temperature of 210°C. The results of experiment found that rotation of mandrel caused significant change in dimension of HDPE parison after it flowed out from the annular rotating-die. It was also found that at the same apparent shear rate, the diameter swell decreased with increasing mandrel rotating speed whereas the thickness swell yielded opposite results. These results could be explained by the change of flow direction during the flow of HDPE melt in the annular rotating-die. Furthermore, the annular rotating-die technique proposed in this research could be applied in adjusting size of diameter and thickness and in predicting thickness of HDPE parison during extrusion with no need to change any production parameter in the polymer extruder.

An annular rotating-die technique in extrusion process: effect of mandrel rotating speed on entrance pressure drop and flow properties of molten HDPE

An annular rotating-die system proposed in this work was specifically designed and constructed so the mandrel could rotate in stationary barrel during extrusion. Effect of mandrel rotating speeds on flow properties and entrance pressure drop of melt HDPE with and without mandrel rotation was monitored in real-time in a single screw extruder. Experimental results showed that the entrance pressure drop decreased steadily with the increase of mandrel rotating speed from 0 to 70 rpm by an average of 45 %. Flow properties of melt HDPE were in accordance with pseudoplastic non-Newtonian behavior. In general, it was found that, at the same wall shear rate, wall shear stress detected in annular rotating-die (mandrel rotation) was lower than that found from normal annular die. The wall shear stress tended to decrease with the increasing mandrel rotating speed from 0 to 70 rpm by an average of 43 %. Possible explanations for the reduction in die entrance pressure drop and flow properties magnitudes for melt HDPE due to mandrel rotating effect were given in connection with the flow pattern of melt HDPE in the annular rotating-die.

Effect of Mandrel on Cross-Section Quality in Numerical Control Bending Process of Stainless Steel 2169 Small Diameter Tube

The tube numerical control (NC) bending process is a much complex physical process with multifactors coupling interactive effects. The mandrel is the key to improve forming quality and to enhance forming limit. In this study, based on the platform of ABAQUS/Explicit, a 3D elastic-plastic finite element model of NC bending process of 2169 (0Cr21Ni6Mn9N) stainless steel tube was established, key technological problems were solved, and its reliability was validated. Then, simulation and analysis of the processes were carried out, and the influence laws of mandrel types and mandrel parameters on cross-section quality were obtained. The results show that the wall thinning or cross section deformation is serious at the middle part and small in the vicinity of the bending plane or initial bending plane; the wall thinning degree increases or the cross section deformation degree decreases with the increase of mandrel diameter or mandrel extension length; the effect of bulb mandrel on the cross section quality is more significant than that of cylinder mandrel. And the reasonable mandrel types and mandrel parameters are chosen for the 2169 high-pressure hydraulic tube with small diameter. The results may lead to better understanding of mandrel role in the improvement of forming quality and forming limit in the NC bending process.

A single stage hot forging process and die set of alternator poles

A single stage hot forging process and die set of alternator poles are put forward in this paper, the heated billet can be forged by only one press in a special die set, which has a moveable mandrel and ring die. The process is analyzed by finite element method(FEM) and experiment. The effects of mandrel on the mode of metal flow and forging load are discussed. The result shows that a well-shaped product can be forged successfully using a lower forging load than that of conventional precision forging.

Effects of Mandrel, Borehole, and Invasion for Tilt-Coil Antennas

Summary Several recently published studies discuss the concept of inductive resistivity-logging devices with oblique transmitting and/or receiving coils. Both wireline induction and logging-while-drilling (LWD) propagation resistivity-tool concepts have been considered. Directional resistivity measurements and improved anisotropy measurements are among the benefits promised by this type of device. Analyses based on point-magnetic dipole antennas were used to illustrate these potential benefits. The effects of a metallic mandrel, borehole, and invasion were not considered because of the absence of a suitable forward model. This paper characterizes mandrel, borehole, and invasion effects for a variety of candidate tilt-coil devices with antenna array parameters similar to those of the previous studies. The characterization is based on calculations from a new forward model that includes tilted transmitting and receiving coils of finite diameter embedded in a concentric cylindrical structure. Important details of the forward model used in the calculations are also provided.

Ｓｉ３Ｎ４，ＳｉＣセラミックス粉末およびウィスカーの爆発圧縮成形

Explosive compaction of ceramic powders (α-Si3N4, SiC) and whiskers (β-Si3N4, SiC) were performed by using cylindrically axi-symmetric direct method. The mandrel was inserted into the center of container to increase the compacting pressure, and the momentum trap was adopted for avoiding the development of cracks in a compact. Sintering was treated to the explosively compacted ceramics under the various temperature and appropriate atmosphere. The effects of mandrel, momentumtrap and sintering conditions on the compact characteristics has been investigated by means of microhardness test, optical and scanning electron microscopy and density measurement. The obtained reslts are as follows:It was found that the mandrel was very efficient in increasing the compacting pressure. In such a case, the mandrel made of Cu was more effective than that made of Al. In the explosively compacted Si3N4 whisker with Cu mandrel, maximum hardness reached 1400Hv. By adoption of the momentum trap, the cracks in a compact was gradually decreased as the weight of momentum trap increased. The density of the explosively compacted ceramics was incresed by even lower sintering temeparature as compared to conventional temparature. This seemed to be due to the activated condition of compacts by the through of shock waves which moved ceramic particles at high velocity and caused the particle refining and the cleaning of the particle surface.