Planetary Rolling Research Articles

Обработка резьбы инструментом с осевым колебанием резьбообразующих профилей

A method for planetary thread rolling with a prefabricated tool with oscillation of the thread-forming surfaces is proposed. It indicates the possibility of obtaining a thread in an aluminum alloy AMg6M with a profile corresponding to the profile of a metric thread. An experimental design of a prefabricated tool with the possibility of angular adjustment of two disks has been developed. The influence of the disk displacement angle relative to each other on the force during planetary thread rolling and the microhardness of its lateral sides was carried out. The value of the disc offset angle is set, which provides the minimum force during rolling. A comparison was made of the microhardness of thread flanks obtained by thread milling and planetary rolling using disks without oscillation and with oscillation of thread forming surfaces. The research results could be useful for designers in the design of deforming thread forming tools and for technologists in the assess process of the possibility of using planetary thread rolling.

Process Optimization of Planetary Rolling of Bismuth-Containing Austenitic Stainless Steel

Process Optimization of Planetary Rolling of Bismuth-Containing Austenitic Stainless Steel

Prediction and Prevention of Cracks in Free-Cutting Stainless Steel Bar Forming

A three high planetary mill is used to produce bismuth-containing stainless-steel bars with high production efficiency. However, due to the influence of bismuth metal properties, the selection of processing parameters must be optimized to avoid the generation of cracking in the bar core. To solve this contradiction and find a suitable processing zone, the thermal simulation experiment of bismuth-containing stainless-steel material was carried out first to determine the constitutive relationship of the material. Three-roll planetary rolling experiments were carried out to determine the crack-producing region. Based on the Brozzo ductile fracture criterion, the fracture threshold of bismuth-containing austenitic stainless-steel bars in three-roll planetary rolling was determined by the finite element (FE) simulation. Five key process parameters were selected, with five factors and four levels of the orthogonal test designed. Through FE simulations, the possibility of cracking of stainless-steel bars with bismuth austenites in different technologic conditions was judged, and a set of optimal technologic parameters was obtained. Based on range analysis, the influence of various process parameters on bar cracking was discussed. Then, based on the dynamic material model and Murty criterion, the processing map of free-cutting austenitic stainless containing bismuth was established. It was found that the optimum process parameters were consistent with the processable range of the hot-working chart. Finally, the field rolling was carried out with the optimum process parameters, showing that there was no crack in the bar.

The planetary rolling process of forming the internal thread

Forming process of internal thread is an advanced manufacturing process. A new planetary rolling process for forming the internal thread is proposed. The structures of rolling system and working process are described in detail. The finite element model of forming internal thread is established, and the forming experiments are conducted by a homemade experimental rig. The material displacement, microstructure, strain, and microhardness are investigated by finite element model and experiment. The results show that the formed internal thread meets requirements and the results of simulation and experiment are consistent. Through the planetary rolling process, the microstructure is stretched and forms the fibrous tissue at the bottom of tooth space of the internal thread. The maximum deformation is located at the bottom of tooth space, and the deformation characteristics are corresponding to the microstructure distribution. At the bottom of tooth space, the microhardness and the equivalent strain are also largest. The maximum microhardness of formed internal thread is improved 37.6%. The new planetary rolling process can improve the production performances and simplify the processing equipment.

Study on cooling process of copper tube after three-roll planetary rolling

Copper tubes are efficient heat exchange parts in refrigeration industry, and their quality has a bearing on the grade of corresponding products. The cooling process of copper tube after three-roll planetary rolling is a key step in the production of copper tube by the casting and rolling method, and its cooling effect matters to the quality of copper tube products. Aiming at the characteristics of motion of a rolled piece in the through water cooling with a cooling water jacket, the method of “stepwise” moving cooling water jacket was used in this paper to achieve equivalence to the motion of the rolled piece, realizing finite element simulation of the whole process of three-roll planetary rolling and cooling of copper tube. The velocity field and pressure field of the fluid in the cooling water model were analyzed, and it was found that there existed a flow “dead zone” with the velocity below 8 m/s, there was a “negative pressure” phenomenon, and there were more eddy currents occurring. Through the study on the temperature field during the cooling process of the rolled piece, it was found that there was a phenomenon of non-uniform temperature distribution in the cooling process of the rolled piece. With the maximum temperature difference at each monitoring point in the cooling process of rolled piece as the evaluation criterion for the uniformity of temperature distribution in the cooling process of rolled piece, the process parameters affecting the rolled piece cooling effect, including the size of water inlet, the size of water outlet, and the pressure of entering water, were studied respectively, and the optimum process parameter values for improving the quality of rolled pieces were finally obtained. The accuracy of the model was verified by comparatively analyzing the metallographic microstructure and microhardness between the factory produced sample and the thermally simulated sample.

Research on Effects of Rolling-Drawing Deformation on Performance of Cu-10Ni-1Fe-1Mn Alloy

Evolution laws of structure and performance of Cu-10Ni-1Fe-1Mn alloy in the process of continuous casting-planetary rolling-drawing deformation were studied by OM, SEM, TEM, Brinell Hardness tester and universal material testing machine. Results demonstrated that the alloy ingot is composed of thick dendrites. The ingot makes grain crushing and dynamic recrystallization after planetary rolling. The hot rolling samples still have abundant fine recrystallization textures after multi-pass drawings. Due to roller-core head or internal-external mold opposite pressure, dislocations in different regions of sample move along the glide plane, forming a macroscopic slip band. Two adjacent macroscopic slip zones which move toward opposite directions compose the folded structures after the deformation. Refined crystalline strengthening, solution strengthening of Fe, Ni and Mn, work hardening, and iron-containing particle precipitation are major causes of alloy strengthening. SEM analysis of tensile fracture demonstrated that the material still maintained good plasticity after rolling and drawing deformation. However, material plasticity declined with the increase of cold processing-induced deformation.

Cracks of Cu-Cr-Zr Alloy Bars under Planetary Rolling

The paper investigated grain sizes and cracks between the edge and the center of Cu-Cr-Zr alloy bar through macrostructure and microstructure. A crack in the center was explored by images of transverse and longitudinal sections with scanning electron microscope (SEM). Results show that the grain size in the edge is obviously finer than that in the center as completely dynamic recrystallization occurs easily; the microcrack of about 40 μm is formed in the center by second phase particles. Some bcc type precipitates Cr and intermetallics such as Cu51Zr14 and Cu5Zr are the source of microcracks initiation owing to coarse grains decreasing the strength. Therefore, refining of grains in the center is necessary to prevent microcracks. The formation mechanism of cracks can be explained by a dislocation model of microporosity nucleating, growing and polymerizing (MNGP).

The effect of roll with passive segment on the planetary rolling process

In three-roll planetary rolling process, there is secondary torsion phenomenon that may lead to rolling instability. This article proposed a new idea to alleviate the secondary torsion phenomenon by dividing the secondary torsion segment out of the roll as an independent and passive one. To study the performance of the roll with passive segment, the three-dimensional finite element models of planetary rolling process using actual roll or new roll with passive segment involving elastic–plastic and thermal–mechanical coupling were established by the software ABAQUS/Explicit, and a series of analysis had been done successfully. The rolling temperature and rolling force of planetary mill were in good agreement with the measured results, which indicated that the finite element method would supply important reference merit for three-dimensional thermo-mechanical simulation of the three-roll planetary rolling process. Comparing the simulation results of the two models, the results indicated that the change in the roll structure had just a little influence on the metal deformation, temperature, and rolling force, but it lessened the secondary torsion deformation effectively and improved the outside roundness of the rolled tube slightly. The research provided a new idea for the roll design of three-roll planetary mill (PSW).

Analysis and Quantification of Grain Size of Various DHP Copper Tubes Manufacturing Processes

Deoxidized High Phosphorus (DHP) Copper tubes are frequently used in numerous industrial and household applications. To ensure the acceptability of DHP copper tubes prepared by various industrial processes, the quality of the DHP copper tubes must be evaluated and one of the best ways to do so is to examine the microstructure and metallography and quantify grain size. In this paper the authors considered the average grain size of copper tube samples made traditionally as well as by the planetary rolling and CastTube process. Because of the small thickness of the CastTube samples, in certain circumstances traditional methods of grain counting were not plausible and a new procedure for grain counting needed developed. This paper is about the development and evaluation of grain sizes in continuously cast tube samples using both the planimetric procedure (ASTM E112) and a new method, which will be herby, referred to as the total grain counting method. This paper also concludes that there is a large difference in the grain size of tubes with different manufacturing methods.

FEA of Planetary Pipe Rolling Process for Stainless Steel

Planetary Pipe rolling process for AISI 304 stainless steel has been studied by using finite element method. Three-roll Mannesmann method is applied to this study. Commonly, rolling process has started from the cold working and finished to the hot one. The rolling process can provide excellent combinations of cost and process reduction than existing one. The process includes various and complex parameters. Each of the process parameters affects forming result. Therefore, all of the process parameters should be considered in FEA.

Three-Roll Planetary Rolling Mill Motion Analysis and Test Research

Against defects of three-roll fixed axis rolling mill caused by rolled piece rotating in process of rolling, presented three-roll planetary rolling scheme, designed the planetary transmission system structure, expounded planetary mill rolling process, analyzed movement relationship between planet carrier, roll and rolled piece according to planetary gear train transmission principle. The rolls do planetary motion and spinning motion both, the former acts on the rolled piece to make it do clockwise rotation movement, the latter acts on the rolled piece to make it do anti-clockwise rotation. The actual movement of rolled piece is combination of the two motions. The theoretical analysis and calculation shows that in rolling process of planetary mill, the speeds of above two kinds of motions are very close, directions are opposite. Due to rolls are inclined compare to the rolled piece, as a result rolled piece does axial movement with a speed of vsinα, radial rotation speed is 0.0029 times of planet carrier rotational speed. Thanks to complexity of extrusion and friction between rolls and rolled piece, the actual speed of rolled piece is approximately zero. Prototype rolling test has verified correctness of theoretical analysis and calculation.

유성압연기를 사용한 스테인리스 강관 압연공정의 유한요소해석

유한요소법을 통하여 유성압연기에 의한 스테인리스 강관 압연공정을 연구하였다. 3개의 롤에 의한 만네스만 공법을 압연공정에 적용하였다. 보통 유성압연은 냉간가공으로 시작하여 열간가공으로 종료되며, 기존의 압출공정에 비해 공정단축과 생산비절감의 장점을 갖고 있다. 압연공정은 다양하고 복합적인 공정변수를 가지고 있으며, 각각의 변수들은 성형결과에 영향을 미친다. 따라서 유성압연의 다양한 공정변수가 해석에 고려되어야 한다. 본 연구에서는 스테인리스 강관성형의 가능성과 생산성을 검토하였고, 소재예열 및 자전속도, 제품두께 변화를 해석에 반영하였다. 스테인리스 강관 압연공정은 성공적으로 시뮬레이션 되었고 최적의 압연조건을 결정하는데 유용할 것이다.

Study on plastic behaviours of CuNi10Fe1Mn alloy tubes under cast-roll process

The cast-roll process (CRP) is widely used in ACR (air conditioning and refrigeration copper tubes), which can increase the yield and greatly reduce the cost. However, there are few studies of CuNi10Fe1Mn alloy tubes on CRP. The purpose of this paper is to provide the based datum for study of CuNi10Fe1Mn alloy tubes. The paper explored the three major processes of horizontal continuous casting, planetary rolling and drawing, and studied the macrostructure, microstructure, mechanical properties and activation energy for deformation of planetary rolling. The results demonstrate that: the CuNi10Fe1Mn alloy tubes have good properties, so it is feasible to be produced by CRP; CRP can refine grains, which is one of the several strengthening methodologies developed to restrict the dislocation motion; the power of planetary rolling mill may be increased approximately 2.0–3.0 times than that of C12200; the rolled tubes of CuNi10Fe1Mn alloy still could be drawn by three passes deformation without an intermediate annealing.

Estimation methods and analysis of kinematical errors of planetary rolling screw motion drives

Estimation methods and analysis of kinematical errors of planetary rolling screw motion drives

Microstructure and Properties of Copper Tube During Three-Roll Planetary Rolling

During three-roll planetary rolling, the microstructure of copper tube with initial columnar grains develops into an equiaxed grain structure due to the large rolling deformation and high rolling temperature. The microstructure of copper tubes significantly influences formability and properties due to the three-roll planetary rolling operation. It is very important to understand the microstructural evolution for such special processing. It was found that dynamic recrystallization occurred at the concentrating deformation zone, followed by rapid grain expansion that gradually stabilized. Corresponding with the transformation of microstructure, the hardness of the tube billet reduced gradually away from the roller's concentrating deformation zone. The changing of roller velocity is responsible for the extreme evolution of the microstructure in the concentrating deformation zone. Therefore, the properties of copper tubes can be controlled by concentrating the deformation zone. This research can facilitate the application of planetary rolling to the manufacture of tubes for low formability materials.

Prediction of 3-D temperature field of TP2 copper tubes in three-roll planetary rolling process

The calculation method and three-dimensional thermo-mechanical coupling model were established for the planetary rolling process of TP2 copper tubes. The distribution rules of temperature field of TP2 copper tubes were obtained by simulation analysis. The temperature of the TP2 copper tubes increases from room temperature to about 700 °C in three-roll planetary rolling, which would reduce the rolling force, and improve the performance of the rolled copper tubes. The temperature of TP2 copper tubes during rolling was in good agreement with the measured results, which indicates that the finite-element method would supply important reference merit for 3-D thermo-mechanical simulation of TP2 copper tubes in the three-roll planetary rolling process.

Microstructure simulation of copper tube and its application in three roll planetary rolling

The three roll planetary rolling of copper tubes is a single pass and large deformation process. In the present paper, the temperature of the copper tube exceeds its recrystallisation temperature as a result of the heat energy generated from severe deformation and friction work. Therefore, the grain size and mechanical properties of the copper tube change fiercely. The constitutive equations of the copper tube were also derived and used as a material model. The dynamic recrystallisation and grain growth models of the copper tube were developed. The grain distribution rules of the copper tube were obtained by integrating the microstructure evolution model into finite element simulation. The grain sizes of the copper tube under different parameters were predicted by artificial neural network. It is in good agreement with the measured results, which can be used in optimising the properties of the rolled copper tube.

Analytical and experimental study on the spiral marks of the rolled product during three-roll planetary rolling processes

In this study, the effects of various rolling conditions, such as inclined angle, offset angle, roll shapes, etc., upon the depth of the spiral marks on the surface of the rolled product and the rolling forces are discussed numerically by the finite element method. Experiments using a self-designed testing machine with work-rolls of three different kinds of roll shapes were conducted. The depth of the spiral marks was measured. From the comparisons between the analytical and experimental results, it is known that a smoother surface on the rolled product can always be obtained with convex-shaped rolls. Whereas, prominent spiral marks probably appear for two-stage conical rolls and spherical-headed rolls under an ill-set rolling condition. These analytical and experimental results can offer useful knowledge for the design of the roll shapes and the pass schedule during three-roll planetary rolling processes.

Experiments of Three-Roll Planetary Rolling

Experiments of Three-Roll Planetary Rolling

Experimental and numerical analyses on three-roll planetary rolling process

This study conducts experiments on a planetary three-roll experimental apparatus and uses plasticine as the working material. Certain rolling characteristics were observed and compared with the data from finite element simulation, which include diameter of workpieces after deformation, the pitch length and threaded angle of spiral marks, and the cavity at the leading end of rolled plasticine. The comparison confirms the correctness of the simulation model for PSW.