Cold Orbital Forging Research Articles

Kinematics and dynamics simulations of cold orbital forging machines based on ADAMS

The vibration of cold orbital forging (COF) machines is detrimental to the quality of the forged part. Therefore, it is necessary to carry out kinematics and dynamics analyses, study the vibration of the COF machine, and provide effective methods for reducing the vibration. In terms of kinematics and dynamics analyses, the mathematical modeling and model solving processes are complicated, and it takes a long time to obtain the kinetic and vibration performances of the COF machine. In this study, the kinematics and dynamics models of the COF machine were investigated. Subsequently, automatic dynamic analysis of mechanical systems (ADAMS) was applied to conduct kinematics and dynamics simulations. The simulation process was convenient and time-saving, and the simulation of the COF machine was effectively verified by conducting an experiment. Based on the simulation results, the kinetic and vibration performances of the COF machine were studied. In addition, a structure optimization method for the COF machine is proposed. Based on the singularity stability theory, the Hopf bifurcation and chaos phenomena are less likely to occur on the optimized COF machine, and therefore the vibration of the optimized COF machine is stable. Meanwhile, the structure optimization method was proven to be effective in reducing the vibration of the COF machine, which improves the quality of the forged part.

LMS/RLS/OCTAVE Vibration Controls of Cold Orbital Forging Machines for Improving Quality of Forged Vehicle Parts

Cold orbital forging (COF) as an advanced incremental metal-forming technology has been widely used in processing vehicle parts. During the COF process, the vibration on the COF machine injures the service life of the machine and the quality of the forged part. The study of the vibration control of the COF machine is therefore necessary. In this study, the dynamic model of the COF machine is established, and the vibration performances of some key positions are obtained using Matlab&Simulink software. Subsequently, the vibration performances are effectively verified by conducting a vibration test experiment. Based on the dynamics model of the COF machine and Matlab&Simulink software, least-mean-squares (LMS), recursive least-squares (RLS) and OCTAVE vibration-control algorithms are applied to reduce the vibration. Comparing the vibration performances of the COF machine, these vibration-control algorithms are useful for reducing the vibration of the machine, which improves the service life of the machine and the quality of the forged part. Based on the vibration performances of the COF machine, the effects of LMS and RLS vibration controls are better than the OCTAVE, and they also obviously reduce the vibration of the COF machine. The vibration-control algorithms are first to be applied to reduce the vibration of the COF machines in this study, which will be beneficial to future research on the vibration controls of metal-forming machines and other mechanical systems.

Research on the vibration model and vibration performance of cold orbital forging machines

The vibration of cold orbital forging (COF) machines is a major issue for the quality of forging parts. It is therefore necessary to investigate the vibration of COF machines and provide some effective methods for reducing the vibration. In this paper, horizontal and vertical dynamic models of COF machines are established. These dynamic models are then effectively verified by conducting experiments. By using dynamic models of the COF machine, the vibration performance of the COF machine is investigated. To investigate methods for reducing the vibration of the COF machine, the effects of some key parameters on the vibration of the COF machine are studied, which include the eccentricities and rotation angular speeds of the inner eccentricity ring and the outer eccentricity ring, the amplitude and frequency of external excitation, and the equivalent stiffness and equivalent damping between swing shaft and bearing. Investigative conclusions can be drawn: During the COF process, vertical vibration is more drastic than horizontal vibration. A larger absolute difference between the eccentricities of the inner eccentricity ring and the outer eccentricity ring contributes to reducing the horizontal vibration of the COF machine. A larger equivalent stiffness and a larger equivalent damping between the swing shaft and bearing, a smaller amplitude and a smaller frequency of the external excitation contribute to reducing the vertical vibration of the COF machine.

Static and Dynamic Analysis of a 6300 KN Cold Orbital Forging Machine

In cold orbital forging (COF) processes, large stress, displacement and vertical vibration of the COF machine are bad for the quality of the part and the fatigue life of the COF machine. It is necessary to investigate the static and dynamic performance of the COF machine and provide methods for reducing the stress, displacement and vertical vibration of the COF machine. In this paper, finite element analysis, theoretical analysis, numerical simulation and experimental analysis were applied to study the static and dynamic performance of a 6300 KN COF machine. The static and dynamic analyses were verified effectively by carrying out strain and vertical vibration test experiments. In the static analysis, the large stress and displacement positions of the COF machine were mainly distributed near the working table and the junction between the working table and the column. Large stress and displacement will be bad for the quality of the part and the fatigue life of the COF machine. Structural optimizations of the COF machine include ribbed plates on the working table and beam. This structural optimization method of the COF machine obviously reduced the stress and displacement of the COF machine. When the angular velocities of the eccentric rings were 8π rad/s, the vertical vibration of the swing shaft is a low-frequency vibration. The existence of absorber obviously reduced the vertical vibration of the COF machine.

Preform designing approach in cold orbital forging of flange gear

Flange gear has a complex geometry and its volume distribution along the axial direction changes suddenly. This makes it difficult to be formed by a single step using a simple cylinder workpiece and the preform is necessary. This research aims at proposing a preform designing approach in cold orbital forging of flange gear. A three-dimensional finite element model of cold orbital forging of flange gear is first constructed. Then, the cold orbital forging processes are simulated under different preform geometries and the insufficient filling and folding defects are studied. At last, the preform is optimized and the defects are eliminated. The experiments are also performed and the preform designing approach in cold orbital forging of flange gear is verified.

A Novel Cold Rotary Forging Method of Producing Multiple Racks Using One Set of Punch

When producing racks by cold rotary forging, the top punch and the rack teeth definitely intervene and thus the top punch has to be amended, which makes the technical designing processes difficult and complex (Han et al., 2016, “Cold Orbital Forging of Gear Rack,” Int. J. Mech. Sci., 117(10), pp. 227–242). In this study, a novel cold rotary forging method of producing racks is put forward to avoid the interventions between the top punch and the racks. Thus, the top punch need not be amended and the technical designing processes correspondingly become simple. In light of this presented method, a novel idea for cold rotary forging of producing multiple racks using one set of punch is motivated. The concrete researches are as follows: First, the mathematical models are developed and three kinds of key forging conditions in cold rotary forging of racks are calculated to avoid the interventions between the top punch and the racks. The first one is the condition that the top punch and the rack teeth do not intervene. The second one is the condition that the top punch and cylindrical surfaces of racks do not intervene. The third one is the condition that the top punch can be successfully constructed. On the basis of these three kinds of key forging conditions, the workpiece is optimized and the cold rotary forging processes of racks with constant and variable transmission ratio are examined using finite element (FE) simulations. The experimental researches are also conducted. The results show that for both racks with constant and variable transmission ratio, the obtained key forging conditions are effective and the presented cold rotary forging principles of producing multiple racks using one set of punch are feasible.

Process optimization method for cold orbital forging of component with deep and narrow groove

During cold orbital forging of component with deep and narrow groove, the metal flow is complex and it may lead to some defects of underfilling and folding. Moreover, the stress state of the tool, which has a long and thin boss corresponded to the deep and narrow groove of component, is poor and thus the life span of the tool is low. Aimed at these issues, this paper presents a process optimization method for cold orbital forging of component with deep and narrow groove. Firstly, three kinds of metal flow modes are presented according to the preform and tool geometries. Then, the cold orbital forging processes under three kinds of metal flow modes are analyzed by FE simulations and the mechanisms for forging defects of underfilling, folding and poor stress state of the tool are revealed. It is found that the horizontal stress imbalance of the long and thin boss of the tool is the main reason for its poor stress state. To improve the stress state of the tool, a new idea is motivated, i.e., it is through controlling the metal flow to balance the horizontal stress of the long and thin boss of the tool. Finally, the optimization method for the preform and tool is presented to eliminate the forging defects. The experiments are also carried out to verify the presented process optimization method.

Comparison of some mechanical properties and micro-topography of a component with non-axisymmetric geometry manufactured by cold orbital and hot forging

Orbital forging is an incremental bulk metal forming process which makes possible to produce complex parts for different applications, mostly in automobile, electrical and machine tools industries. Compared to conventional forging methods this technology offers many techno-economical advantages.Present paper is aimed at analyzing and comparing mechanical properties in terms of hardness and tensile strength, as well as microstructure of a non-axisymmetric steel component (U-cross joint) manufactured by two different technologies: cold orbital forging and conventional hot forging.The Vickers test method was employed for hardness testing of both types of forgings. Hardness was measured at different points and relevant cross sections with the goal to obtain fine distribution of this parameter. In the next step, based on the measured hardness values, tensile strength was calculated using the hardness-strength correlation. Metallographic examinations of the surface structure as well as micro-hardness measurement of the ferrite phase were also carried out at the different cross sections of the components. Observed microstructure was analyzed and associated with the results of mechanical testing. Furthermore, a numerical analysis of the investigated cold orbital forging process was performed using commercial software package Simufact.forming and Finite Element (FE) approach.

Differences between traditional cold forging and cold orbital forging of a spur bevel gear

Abstract Cold orbital forging, as an advanced incremental forming process, has been widely researched and used to fabricate the spur bevel gear. However, the mechanism of cold orbital forging is quite different from that of traditional cold forging, which leads to the different forming laws and different properties of forged gear. In this paper, cold orbital forging and traditional cold forging of a spur bevel gear are simulated under the same conditions in the Deform-3D software platform. The filling process, geometric characteristics of forged gear, effective stress distribution, effective strain distribution, gear tooth accuracy are comprehensively clarified and compared. The results show that, comparing with traditional cold forging of a spur bevel gear, cold orbital forging can increase the degree and homogeneity of plastic deformation and improve the gear tooth accuracy.

Orbital Cold Forming Technology - Combining High Quality Forming with Cost Effectiveness - A Review

Objectives: This review presents a short communication of cold orbital forging process, its characteristics and compare with classical forging. Methods/Statistical Analysis: Orbital forging have special progressive motion permits the contact space between tool and workpiece to be smaller and thus, lowers forming load and friction. Therefore orbital forming in some cases makes it potential to provide the specified part in exactly one operation, whereas in classical forging quite one operation would be needed. Findings: Cold orbital forming is more useful and preferable in comparison to other manufacturing processes as we can manufacture more number of gears with better surface finish in less time. Thus, cold orbital forming has much higher efficiency. The process is less time consuming and saves labor costs too. Hence, better finished gears can be manufactured in bulk and it also turns out to be more economical than the other manufacturing processes. Current review illuminates the techno economical advantages of the orbital forming process and how advantageous it is over classical forming process. Application/Improvements: This review includes the forming time and distribution of stress and strain on the workpiece and also the die.

Cold orbital forging of gear rack

At present, gear rack is manufactured mainly by cutting method while its precision plastic forming method has not been reported. This paper proposes an innovative cold orbital forging method for manufacturing gear rack, in which the complicated teeth of gear rack are forged by the highly dynamic rocking tool under straight line path. Firstly, a universal method for designing the rocking tool under straight line path is proposed according to the forming mode and contacting mode between the rocking tool and component, i.e., one side of the component is ultimately overall formed by the overall contact (it is achieved by the incremental deformation) between the corresponding side of the rocking tool and component. Based on this universal method, the rocking tool in cold orbital forging of gear rack is accurately designed. Secondly, the mathematical model and method for interference examinations between the rocking tool and gear rack are developed and the interference amount and interference zone are calculated. Thirdly, to eliminate the interference between the rocking tool and gear rack so as to guarantee the forming accuracy of gear rack, a dynamic envelope forming principle is proposed and an innovative forming mode of gear rack is correspondingly developed, i.e., all the time-varying interference zones in the rocking tool are cut one by one and the ultimate tooth surface (planar) of gear rack is incrementally formed by the local contact between a series of modified surfaces (nonplanar) of the rocking tool and tooth surface of gear rack. Based on this proposed dynamic envelope forming principle, the mathematical model and method for modifying the rocking tool are developed and the dynamic envelope forming of gear rack is achieved successfully. The FE simulations and experiments of cold orbital forging of gear rack are conducted. The results demonstrate that the proposed cold orbital forging method for manufacturing gear rack in this paper is effective and cold orbital forging shows great potential in manufacturing gear rack.

Effect of key factors on cold orbital forging of a spur bevel gear

Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the great importance of the final step to gear forming and its complication with interactive factors, this work aims at examining the influence of key factors on the final step in cold orbital forging of a spur bevel gear. Using the finite element (FE) method and control variate method, the influence rules of four key factors, rotation velocity of the upper tool, n, feeding velocity of the lower tool, v, tilted angle of the upper tool, γ, friction factor between the tools and the billet, m, on the geometry and the deformation inhomogeneity of the cold orbital forged gear are thoroughly clarified. The research results show that the flash becomes more homogeneous with increasing v, increasing m, decreasing n or decreasing γ. And the deformation of the gear becomes more homogeneous with increasing v, decreasing n or decreasing γ. Finally, a corresponding experiment is conducted, which verifies the accuracy of FE simulation conclusions.

Calculation of kinetic locus of upper tool in cold orbital forging machine with two eccentricity rings

In cold orbital forging machine with two eccentricity rings, the kinetic locus of the upper tool includes two types. The first one is the kinetic locus of one point in the axis of the upper tool, which is produced by the motion of the two eccentricity rings. The second one is the kinetic locus of one point in the working surface of the upper tool, which is produced by the first type of kinetic locus. Both types of kinetic locus of the upper tool is critical to cold orbital forging. The first one has great influences on the deformation of cold orbital forged components and the second one can be used to make the intervention examination between the upper tool and components. So this paper aims at obtaining the kinetic locus of the upper tool in cold orbital forging machine with two eccentricity rings so as to better design and check the cold orbital forging tools. Firstly, a model of analyzing the kinetic locus of the upper tool is developed. Then, the general equations of the kinetic locus of the upper tool, which can describe the kinetic locus of the arbitrary point in the upper tool under all kinds of geometric and kinematic relations between the two eccentricity rings in cold orbital forging machine, are achieved. Finally, the characteristics and applications of the kinetic locus of the upper tool are discussed based on these equations. This study has great significances for adjusting the two eccentricity rings of the machine to control the motion of the upper tool and designing and checking the cold orbital forging tools.

Calculation Method for Rocking Die Motion Track in Cold Orbital Forging

In cold orbital forging, the rocking die performs complex motions on the components and the intervention between them cannot emerge, otherwise the components cannot be shaped successfully. Calculating the rocking die motion track is essential to determining whether there is intervention between the rocking die and components. Thus, this study aims to comprehensively investigate the rocking die motion track in cold orbital forging. For this purpose, an analytical model for calculating the rocking die motion track is first established. Then a universal motion track equation that can denote any geometry and kinematics relationships between the rocking die and components is obtained using this analytical model. To verify the validity of this motion track equation, an experimental study is conducted. The result shows that the calculated rocking die motion track is consistent with the experimental one. According to this valid motion track equation, the characteristics of the rocking die motion track are revealed. Finally, to apply the calculated rocking die motion track for analyzing the intervention between the rocking die and components, two case studies are examined.

Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin

Abstract The orbital forging is one of the metal forming processes which enables the manufacture of products through worm or cold working. A characteristic feature of this technological process is the use of a special wobbling motion of one of the tools in order to reduce the required forming force. This is particularly advantageous during the formation of products in the shape of a disc or a flange pin. Unfortunately, typical constraints of cold orbital forging are: uncontrolled buckling, loss of shape stability (“mushroom effect”) and cracks. They depend on the technological parameters of the process and their cause can be explained on the basis of e.g. workpiece stress state analysis, which is a difficult task due to the complexity of orbital forging process. The article discusses the issues of stress and strain in cold orbital forged parts of the flange pin type, made of AlMgSi aluminum alloy. The results of the presented FEM simulation, verified experimentally, explain the influence of the theoretical aspects of this process on its implementation conditions. It is assumed that orbital forging is performed on the PXW-100A press and the numerical model takes into account all possible variants of the process. Debate boils down to discussing the stress and strain state (e.g. analyzing the stress and strain rate fields) occurring in the workpiece in the context of chosen technological parameters and constrains of orbital forging process

Investigation of the cold orbital forging process of an AlMgSi alloy bevel gear

Orbital forging is a metal forming process in which one of the dies performs a complex rocking motion. It ensures reduction in required load and allows for the cold forming of a workpiece. One of the mechanical parts formed by means of this technology is a bevel gear. However, a numerical analysis of orbital forging bevel gears is very difficult to perform due to the complex rocking motion of the die, which is confirmed by numerous works investigating the orbital forging process. In the present work, investigation results of the cold orbital forging of aluminum alloy bevel gears are presented. In contrast to other works devoted to the process, this study proposes a new procedure for forming bevel gears and the workpiece used has a shape which is different from the previously applied ones. The obtained results apply to both theoretical and technological aspects of orbital forging. The FEM simulation results have been successfully verified in laboratory conditions using the industrial PXW-100A press.