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Abstract
Industrial summary The history of press machines is very long among industrial machinery, but its evolution has been very slow. For example, the driving mechanism and the slide motion of press machines have not shown remarkable advance in the last 40 years since a link mechanism and a link motion were introduced through the technical cooperation of European and American advanced countries in the 1960s. In this sense, the recent appearance of servo presses was an epoch-making event that would change and expand the possibility of press production techniques.
... Slide motion and driving mechanism of such presses have not shown appreciable advancing in the last forty years. In 1960s, link-motioned mechanisms were introduced throughout the technical collaboration of European and American scientists [8]. In today's industrial foundation, sheet metal working with dies and press machines serves as one of the most advantageous manufacturing systems for production of sheet metal components [9]. ...
... However, high energy consumption is a significant problem in press industry. Servo presses are not suitable for use at huge working energies due to the fact that they do not incorporate energy storage devices such as an accumulator in a hydraulic press or a flywheel in a mechanical press [8]. Therefore, studies have been focused on increasing the actuator power capacity of controllable servo presses. ...
... Figure 2.2 Motions of conventional press and servo mechanical press [28] Motion selection screen in SDE model servo presses of Amada (Figure 2.3) provides selection of various motions for crank, soft, link, pulsating, programmable, pendulum, coining, and iterative [30]. Flexible motion of servo presses is presented as free-motion concept stated by Miyoshi [8]. Aida's ServoPro Press [31,32] has knuckle and crank motion, slow down at top of stroke, short stroke, and dwell at BDC curves. ...
Due to precision, flexibility, simplicity in construction, easy control, higher speed and lower energy consumptions, servo presses have recently become popular in metal forming applications. Servo press technology combines the advantages of hydraulic and conventional mechanical presses without their drawbacks. This study presents design, construction and demonstration of a servo crank press system for metal forming operations. The research involves kinematics and motion optimization, dynamic modeling, structural design and analysis, servo motor selection, automation and control, and operational performances of the servo press. The press used in this work has a load capacity of 50 ton and stroke capacity of 200 mm. Firstly, optimized trajectories of ram scenarios are generated. Then dynamic modeling using Lagrange approach is presented. Next structural model is constructed, and Finite Element Analysis (FEA) of press parts are performed within safety limits. A servo motor with a reduction unit is selected based on dynamic model. After that a new automation system is developed, and Cascade Feed-Forward (CasFF) control is applied. Moreover, four motion scenarios (crank, dwell, link, and soft motion) are employed for the performance assessment of press. Finally, the dynamic model is verified by the experimental results. The research study is carried out under support and grant of an industrial project, aiming to provide know-how to industry and researchers.
... In addition to different stamping processes, there are other reasons for changing the stroke of the press, such as increasing production efficiency and reducing noise [11,12]. In Fig. 11, the dotted line shows the motion of the conventional press, and the solid line shows the motion of the servo press. ...
... Here, DPV is the difference between the values of adjacent peaks and valleys. V n is the value of the valley of the n-th Fig. 11 Flexibility of sliding motion in servo drive (or free motion) presses [11] waveform in the entire process. P n-1 is the peak value of the last waveform in the entire process. ...
Stamping tools play an important role in the stamping process, which directly influences product quality and production efficiency. To evaluate and manage these tools, tool lifetime expressed in terms of the number of times of tool reciprocating motion is an indispensable parameter. Traditional methods for counting tool movements employ mechanical counting devices with presses. In this paper, a new counting method based on the acceleration signals of tool movement is presented that involves installing an acceleration sensor on the tool itself. In order to reduce the effect of noise signals, a Butterworth low-pass filter was first applied to the collecting signals. Then, based on the analysis of the filtering signals of four typical tool motion modes, DPV and T in the return segment of every cycle, also termed uniqueness, are introduced as the threshold parameters. Finally, a count algorithm based on the dynamic threshold values is studied to count tool movement. To verify the accuracy of the counting method, eight typical motion modes of stamping tools were tested. The results show that the proposed method is effective for counting tool movements in various tool motion modes.
... The servo press provides flexible punch motions for production needs that considerably improve stamping technology. For example, an enhanced forming result can be obtained by utilizing a suitable punch speed and a dwelling duration to avoid faults such as cracks, wrinkles and spring-backs (1) (2) . The tool life may be extended by slowing down the punch speed to lessen the impact (3) , along with reducing the stamping noise as well (4) . ...
... The tool life may be extended by slowing down the punch speed to lessen the impact (3) , along with reducing the stamping noise as well (4) . In addition the adjustable punch stroke is helpful for raised productivity (1) . In summary formability, long tool life, low noise and high productivity can be achieved by applying the servo press on stamping operations. ...
The servo press with a flywheel is able to provide flexible motions with energy-saving merit, but its true potential has not been thoroughly studied and verified. In this paper, such the ``hybrid-driven'' servo press is focused on, and the stamping capacity and the energy distribution between the flywheel and the servomotor are investigated. The capacity is derived based on the principle of energy conservation, and a method of using a capacity percentage plane for evaluation is proposed. A case study is included to illustrate and interpret that the stamping capacity is highly dependent on the programmed punch motions, thus the capacity prediction is always necessary while applying this kind of servo press. The energy distribution is validated by blanking experiments, and the results indicate that the servomotor needs only to provide 15% to the flywheel torque, 12% of the total stamping energy. This validates that the servomotor power is significantly saved in comparison with conventional servo presses.
... In 1960s, link-motioned mechanisms were introduced throughout the technical collaboration of European and American scientists. 8 In today's industrial foundation, sheet metal working with dies and press machines serves as one of the most advantageous manufacturing systems for production of sheet metal components. 9 Sheet metal forming involves a variety of integrated techniques. ...
Servo presses have recently come into prominence for sheet metal forming operations due to their flexibility, controllability, and simplicity. Minimum energy consumption and maximum tool life are their significant characteristics, leading to considerable reductions in manufacturing costs. This article presents technological review on design and applications of servo presses. The characteristics of servo presses are described and compared to conventional and hydraulic presses. Mechanisms used in servo presses and their motion concepts are evaluated with design features. The industrial background of mechanisms is reported with typical examples from leading press manufacturers. A new classification of the servo presses is presented according to mechanisms and drivers. Besides, ranking of press types according to power control and mechanisms is determined. Servo presses with slider-crank mechanism design are preferred due to their distinctive characteristics.
... Examples include conventional mechanical press, multi-link mechanical press, hybrid driven press, hydraulic press and servo press. Among these stamping technologies, servo presses possess a lot of advantages (Miyoshi, 2003). For example, they have programmable stoke and slide velocity, the ability to dwell in the stroke, and bottom-dead-centre (BDC) accuracy in microns (Landowski, 2004). ...
A control system is developed for controlling a newly designed 300-ton servo press. The control goal is to drive the punch to track various desired trajectories, and to ensure the accurate repeatability of its bottom-dead-centre (BDC). Two major difficulties are encountered in designing the system. The first one is the nonlinear kinematics of the force-amplification mechanism. The second is the tight synchronization requirement of two servomotors. To cope with these problems, techniques such as kinematics buffers, cascaded feedback loops and cross-coupling method have been used. The control algorithms are implemented using six PID channels on a Turbo PMAC2 motion control card and are tested with experimental models. Satisfactory performance is obtained from the test results.
... In an AC servo press, no clutch brake and flywheel are used and the number of gears transmitting power and oil used for these mechanisms are reduced. The most important feature is that the motion of the ram/slide is flexible and thus new forming processes and new functions could be realized [15]. Compared with the hydraulic servo presses, much more accurate motion is possible and the noise due to oil pump is not caused. ...
The historical trend of Japanese precision forging is reviewed first, and then the results of research and development in recent 15 years are introduced. New forging methods such as enclosed die forging, divided flow method, forging utilizing friction, controlling of elastic deformation of die, extrusion against pressure supported tool, forging of sheet metal are explained. Some topics related with servo controlled mechanical press, finite element simulation and tribology are also presented.
... The further development of servopress seems to be restricted by the power available from commercial servomotors. For the purpose of developing high capacity servopress, numerous press manufacturers have implemented many different approaches [9][10][11][12][13] such as high torque and low round servomotors, driving mechanism with force-multiplier effect and redundant actuation. Here, the redundant actuation means two or more servomotors were used to drive a common ram of press. ...
This paper proposes a so-called multi-servomotor parallel driven scheme to construct high capacity mechanical presses. The
design method is based on the combination of dual screw actuation unit, parallel mechanism with kinematic redundancy (PMKR)
and toggle mechanism with symmetric arrangement. Here, the dual screw actuation unit, which consists of two ball screws driven
by two servomotors respectively, acts as a linear actuator. By connection with PMKR, several actuators are incorporated to
generate large driving force to push the ram of press via toggle mechanism. To get more power from more linear actuation units,
three kinds of 2-, 3-, 6-degree of freedom (DoF) PMKRs with linear actuators are proposed. A 2-DoF PMKR example is studied,
and its load capability and accuracy performance are illustrated. Finally, three schematics of 4-, 6- and 12-servomotor mechanical
presses are presented. These schemes demonstrate the feasibility of the design method to develop high capacity mechanical
presses driven by multi-servomotor.
KeywordsMechanical presses–Dual screw actuation unit–Parallel mechanism with kinematic redundancy–Multi-servomotor driven
At present, the servo press is developing vigorously. This paper focuses on the main drive system of the servo press. Different from conventional main drive systems (single-sided output servo motor; unilateral bias fixed installation; large belt wheel or large gear transmission), the novel main drive system adopts a two-side output integrated servo motor (floating and central installation). The integrated servo motor is connected with the symmetrical toggle booster mechanism through a planetary roller screw pair, making full use of the resources of the integrated motor and transmission structure. By removing the large belt wheel, the moment of inertia of the novel main drive system can be greatly reduced. Furthermore, the novel main drive system has excellent mechanical and motion characteristics (Low-speed forging, high-speed return). More importantly, the novel main drive system through simple mechanical combination in parallel, constituting multiple sets of the novel main drive system, can be applied to servo presses of different tonnages (small, medium, and large). It facilitates the standardization and serialization of the main drive system, and it has the characteristics of large-scale industrialization and low-cost manufacturing. Accordingly, theoretical analysis and simulation are carried out for the novel main drive system, and a new servo press synchronously driven by two sets of the novel main drive systems is designed and manufactured for motion characteristics experiments and sheet blanking tests. The results manifest that the novel main drive system can achieve the above objectives and has feasibility and practicability.
This paper focuses on the quality improvements on clinching joints using a servo press with a Radial basis function neural network and a sliding mode (RBFS) control strategy. Bottom thickness, which is affected by the press punch position, is usually used to monitor clinching joint quality. Traditional clinching presses are driven by pneumatic pistons or motors that provide feedback on punch force or motor position. However, this feedback is indirectly related to the joint bottom thickness. Clinching workers who set the control parameters on these presses depend on tests and statistics. Thus, this paper presents a servo press system that utilizes punch position feedback to directly control the joint bottom thickness. Transmission errors are considered for the movement accuracy of the servo press. A mathematical model of the servo press is established for analyzing. An algorithm, which combines RBF neural network and sliding mode, is proposed and applied for press position tracking. This algorithm adopts an RBF neural network to approximate the nominal model of the press system. The update law of the algorithm is based on the Lyapunov function used to prove the stability of a closed-loop system. The sliding mode controller compensates for the neural network error and disturbance. Finally, experiments are executed on the servo press with an RBFS controller. To evaluate the performance of the proposed method, a fuzzy PID controller is also applied to the press for comparison. The results indicate that the servo clinching press system with RBFS efficiently and accurately control the clinching jointing process.
Servo mechanical press is a complicated system with several transmission processes. The friction and other nonlinear factors are critical problems of servo press controlling. This paper focuses on the performance improvements of position tracking on servo press. In order to carry out the researches, first, the mathematic model which expresses the mechanical transmission processes is built to analyze the servo screw press system. Then an algorithm which combined neural network and fuzzy sliding mode (RBFFS) was proposed and applied on the position tracking of servo press. Finally, the simulation and experiment results indicate that the RBFFS control algorithm is effective and capable for servo press controlling.
The mechanical press is a machine which applies forming force on materials, mainly on metals. A die is placed into the press to mold the material during the stamping process. The eccentric mechanical presses with driving crank has a simple operation, but the slide upstroke and down stroke speeds are fixes and determined by the impact reduced speed on the material (the blank). However, these machines can be retrofitted attaching a servo-drive and PID controls to improve productivity. The objective of this work is to present a hybrid drive approach for controlling and improving the press speed and the stroke rate for eccentric presses, but keeping a die impact reduced speed on the metal sheet. The cost for transforming into a hybrid servo-press is around 20% of a direct drive servo-press.
This paper proposes a novel high capacity servo press system with two servo motor inputs and high ratio force amplifier mechanism for metal forming. First, the press structure was expressed. The force amplifier was made of seven-bar mechanism which possesses quick-return character and high ratio force amplifier. The symmetric structure balanced the force in horizontal direction, and dispersed the forces on two transmission routes. In theoretical study of the new structure, kinematic and dynamic analyses were obtained by examining the geometry of the structure. The performance of press was discussed by example demonstration. Finally, the kinematic experiments and metal forming experiments were carried out on the prototype machine by using grating scale system. The measured data match the theoretical calculation well, which validates the feasibility of this new press mechanism.
Servo-actuated presses may provide maximum pressing force at any ram position in the same manner that hydraulic presses do, while offering several benefits in terms of precision, energy-conversion efficiency, and simplicity, due to their lack of hydraulic circuitry and oil. Several press builders have developed servo-actuated presses; however, issues relating to overconstrained multi-axis architecture have been disregarded. This study proposes an innovative method to avoid overconstrained architectures in multi-axis presses, by implementing a family of modular parallel mechanisms that connect multiple servo-axes to the press ram. Parallel mechanisms, which can be applied in several fields of robotics and industrial automation, exhibit important benefits for the application at hand, including high-load capacity, stiffness, and compactness. A biaxial industrial servo press prototype with a nonoverconstrained and modular architecture was built and presented as a proof of concept. Each axis comprises a servomotor, a gearbox reducer, and a ball-screw transmission. It is shown that such a press may be constructed from commercially available components, achieving high energy efficiency and high press force with relatively simple construction. A direct comparison with an equivalent hydraulic-press model is carried out, thus highlighting the servo press energy efficiency.
Heat transfer coefficient (HTC) is one of the most important and difficult-to-obtain parameter in high temperature environment. Contact pressure and workpiece surface roughness are among important parameters that affect the heat transfer in elevated temperature forming of sheets. In this study, HTCs are investigated experimentally by using a servo-drive press. With the flexibility that the servo-drive press offers, effect of various blank holder pressures on temperature change is determined. Before and after surface roughness conditions of aluminum and magnesium (from two different manufacturers) alloy sheets are compared. Experimental setup was modeled using deform 2D, and measured temperature curves were compared with the finite element analysis (FEA) predictions and a window of heat transfer coefficients were determined for warm forming of sheets. Determined heat transfer coefficients were implemented in a nonisothermal deep drawing FE model in deform 2D and results were compared with experiments. Good agreement was obtained between FEA predictions and experiments.
This paper studies the problem of finite frequency H∞ filter design for switching linear parameter varying (LPV) systems with disturbance frequency affected by system parameters. A set of switching filters are designed, each suitable for a specific parameter subregion and a specific finite frequency performance index, the frequency range of each performance index depends on the parameter subregion. The hysteresis switching logic is adopted, and the design problem is finally formulated into linear matrix inequality (LMI) which can be computed efficiently with LMI Control Toolbox. A numerical example is given to illustrate the effectiveness of the proposed method.
In this paper, a synchronization control technique of dual-servo motor driven press system is proposed. An independent cascade PID control technique has been applied to the conventional press system for advancement of control stability. However, it is not easy to reduce synchronous error using the independent cascade PID control technique when some different load disturbances are involved in each motor. The eccentric error of the slide caused by the problem degrade the control performance of the BDC(Bottom Dead Center). In order to achieve reduction of the synchronous error between two servo motors and accurate position control simultaneously, a new control scheme comprised with cascade PID control loop and cross-coupling loop is proposed. In simulation using Matlab SIMULINK, the AC servo system is designed. The control performance of proposed technique is compared with conventional control technique to the model of AC servo system. Also, the sub-scale model of dual-servo motor driven press system which can replicate the slide motion is constructed for experimental verification for the performance of the proposed control technique. The cross-coupling control technique reveals more precise and stable performances in the position and synchronization controls.
The objective of this paper is to study performance of triangular elbow transmission mechanism for servo press. Then kinematics models are deduced and given. Kinematics curves along slider motion direction are drawn. Moreover, under the same driving condition, the effects of different link ratios on slider output motion are examined and compared with common six bar transmission mechanism in the article. Through motion curves comparison, it can be seen that this triangular elbow mechanism has significant force increasing effect and good quick-return characteristics. In addition, we carried on triangular elbow servo press virtual design and simulation. The case study provides more visual and reliable decision basis for designer. The results would be useful reference for optimization design of transmission mechanism.
The characteristic feature of precision forging is reviewed first, and then the results of the development of precision forging in Japan since 1960 together with some recent examples of product are introduced. New forging methods such as enclosed die forging, divided flow method, extrusion against pressure supported tool, forging of sheet metal, forging utilizing friction and controlling of elastic deformation of die are explained. Some topics related with the newly developed servo-controlled mechanical presses are also presented.
Servo press is a new developing trend in forming equipments. Aiming at the nonlinearity, time lag and time variability existing in servo system, the fuzzy PID control method was applied to conduct the position servo press control system. A fuzzy PID controller was built up to achieve the PID parameter setting of regulator by using the Borland C++ Builder. The experimental results of step response and sinusoidal signal response show that this method could effectively raise the response speed, reduce overshoot and steady-state errors, and have powerful ability of restraining external disturbance. The control algorithm using fuzzy PID control has the better performance than that of traditional PID controller, which is an effective control algorithm to improve servo press's position control.
Based on analysis of press working characteristics, some of the main kinematics requirements for working mechanisms of servo mechanical presses were put forward: fast in empty stroke, slow and uniform in working stroke and big force gain. Crank link and knuckle-straight link are the most common working mechanisms in mechanical presses. To meet the requirement of servo mechanical presses, another mechanism, knuckle-triangle link, was designed. The kinematics simulations of the three mechanisms for a 1600kN press were conducted by dynamic software ADAMS. Knuckle-triangle link had the most uniform and lowest slide's average velocity and biggest force gain within the working stroke. For the same nominal pressure of 1600kN, the required input torque of knuckle-triangle link was 9108Nm. In comparison with crank link and knuckle-straight link, the crank's input torque was reduced by 84% and 76% respectively without considering the influence of friction and inertia. In conclusion, knuckle-triangle link mechanism is more suitable for large-tonnage servo presses.
This article proposes a new type of multi-actuated mechanical press with parallel topology to develop high stamping capacity. Four active limbs actuated by servomotor deliver forces and motions to moving platform, and the passive limbs are driven by moving platform to push or pull the ram. This four-input-single-output system realizes multiple actuations without causing being over-constrained. Due to infinite number of solutions for the inverse kinematics, selection of actuation schemes for given ram trajectories is more crucial. Further, the principle of virtual work is used in the inverse dynamic problem. By choosing the pose variables of moving platform as generalized coordinates to describe the manipulator system, the linear form of dynamic models is derived. A typical deep-drawing process with nominal 25,000 kN capacity and 1200 mm stroke is simulated, and the required driving torques are computed. These performance analyses provide a basis to the design of the control law or the estimation of servomotor parameters for the mechanical press.
Multi-axis servo systems have been applied to many machine tools in recent decades, but they are not commonly used for press machines. They are particularly uncommon for small presses because it is still believed that the precision of a small press is dependent on the precision of its components and parts. However, high-precision components and parts are difficult to manufacture and assemble, so the costs of small precision presses are roughly equal to or higher than those of large press machines. Moreover, the accuracy of conventional small presses worsens over long operation times, particularly when dealing with off-center loading frequency. Therefore, we propose a small mechanical press with an adjustable driving system, using a slide and double-axis servo system, for manufacturing small products. Through this proposed design, we expect higher-quality products to be produced for lesser cost than conventional small presses.
The objective of this paper is to perform the optimal design of a novel press system with Stephenson-I mechanism for deep drawing, and validate its feasibility. First, the system is presented and its advantages are discussed. Then, kinematic analysis is conducted by using the vector loop method. Moreover, the kinematic dimensions of the variable coupling are synthesized by using an optimization method. Furthermore, the proposed approach is illustrated by a design example. Finally, the solid model of the proposed design is established, and then kinematic simulation is performed by employing ADAMS software. The results show that proposed new press system is feasible and of better output motion for deep drawing. In addition, it has the advantages of easy manufacture, lower cost, higher precision, and easy adjustability.
We present a two-step calibration methodology of multi-actuated mechanical press with parallel topology and illustrate the method with a case study of a dual-actuated servo press with parallel topology. The kinematic model of the servo press is established firstly. From the total differentials of the kinematic equations, the error sensitivity matrix is obtained to find out linear dependent parameters and the effects of kinematic parameters on the press accuracy are studied. It is found that the press mechanism has the advantage that the press accuracy at the working area is less sensitive to the kinematic parameter errors. The experiment is carried out to measure the motions of the moving platform and slider. By the kinematic error model, the kinematic parameters of the active and passive chains are identified, respectively. Experimental results show that the accuracy of the servo press improves by 82% after kinematic calibration.
Recently several press builders developed gap and straight-sided metal forming presses that utilise the mechanical servo-drive technology. The mechanical servo-drive press offers the flexibility of a hydraulic press (infinite slide (ram) speed and position control, availability of press force at any slide position) with the speed, accuracy and reliability of a mechanical press. Servo drive presses have capabilities to improve process conditions and productivity in metal forming. This paper reviews the servo press designs, servo-motor and the related technologies, and introduces major applications in sheet metal forming and bulk metal forming.
Servo presses are widely used in high-precision, complicated forming process fields and promoted around the world in recent years. It is the trend of forging machinery for its servo motor-based digital heavy haul driven technology. At present, it becomes the hot research field. The structure characteristics of triangular elbow servo press were firstly introduced in the paper. And then the kinematics mathematical model of triangular elbow transmission mechanism was deduced and given. Based on it, this paper provides the slider kinematics analysis by Matlab. The slider motion law under various parameters can be analyzed and compared. The results would be useful reference for optimization design of transmission mechanism. The case study provides more visual and reliable decision basis for designer.
This paper presents first result in the course of studying, development and implementation of synchronizing control method on the dual-servo system. Conventional synchronizing control method is often used for precise slide position control, which concerns cross-coupling in terms of angular position only. However, it is not easy to synchronizing control in case there are some different load disturbances in each motor. In order to achieve satisfactory reduction the synchronous error between two servo motors and accuracy position control at the same time, a new control scheme is comprised with cascade control and an improved cross-coupling control is proposed. The improved cross-coupling control method performs in terms of angular position and velocity simultaneously for high speed and accurate position control. In the simulation servo system, the servo motor model adopts the CE110 Servo Trainer model from TQ Education and Training Ltd. Also different load disturbances are applied to each servo system. Newly proposed cross-coupling control scheme is implemented for synchronizing control of each servo system under different disturbances. The simulation reveals more stable and efficient performance than conventional synchronizing control method.
Productivity of press lines for the automotive industry can be increased by 10-30% by the introduction of servo drives. Highest productivity is however only obtained by optimally synchronizing presses and loading/unloading equipment (robots). This paper proposes synchronization algorithms which are designed for low-power servo-press drives, in which acceleration and deceleration of the press takes a significant part of the cycle. Deceleration at the end of the cycle is started at a point already taking into account at what moment the loader will have completed its work. During deceleration, the moment at which to re-accelerate for the next cycle is re-calculated based on an actual prediction of loader motion. In a practical implementation, the proposed algorithms for press control are implemented in a robot controller, the same controller which controls the loader robot.
The influence of press ram motion on forging performance for magnesium alloys was examined at elevated temperatures using an upsettability test on a CNC servo press. The forging limit of a wrought AZ31B (Mg–3mass%Al–1mass%Zn) magnesium specimen, forged using applied deceleration of the press ram motion, was found to be 30% higher than the forging limit achieved without press ram motion control. A finite element analysis was conducted to model the experimental results. The calculated temperature distribution was relatively uniform during upsetting with decelerated ram motion, and the maximum equivalent strain was maintained at a low level. Experimental and simulation results suggested that the influence of the press ram motion on the ductility of the Mg specimen could be described by a strain localization model. Furthermore, the ductility of Mg specimens during decelerated ram motion was improved in backward extrusion.
The production processes of forming companies are traditionally characterized by a high productivity. Process chains are developed
with regard to cost efficiency for a predefined lot size. However, the accordingly determined optimal process chain might
become inferior against the background of a changing company environment. This paper presents a feature-based methodology
for the development of production process chains considering changeable company environments. A classification of influences
on production processes is developed which allows the deduction of scenarios describing the interrelation between causes of
change and companies‘ decision making criteria. Based on the value of the possibility to change or expand a process chain
can be determined. The method is applied using the process chain planning for a particulate filter as an example.
Keywords:Process chain development-uncertainty-metal forming
To achieve higher accuracy and lower the noise in punching, AC servo motor was employed in press. The slider-crank mechanism is widely used as the core of the mechanical press. Dynamic model of the slider-crank mechanism was established through Lagrange equation and computed-torque control technology was chosen to regulate the motion of the mechanism in punching process. Simulation results revealed correctness of the theoretical analysis. Experiments performed on the press-hold punching curve showed the effectiveness of the computed-torque control theory in servo press and the noise reduction potential of it.
Servo presses provide flexible punch motions, which satisfy different production needs. To achieve this merit, the control system must maintain the punch motion accurately despite versatile desired trajectories or varied loadings. Against this backdrop, the current paper proposes an iterative learning control (ILC) scheme for a hybrid-driven servo press. A proportional derivative (PD) type ILC controller that contains a closed-loop feedback controller is adopted. The sensitivity Jacobian is introduced into the controlling algorithm as the proportional gain in order to smoothen and increase the error convergence rate. The proposed ILC controller is then developed and verified on a servo press prototype. Experimental validations of a cup-shaped drawing are also carried out. The results show that the proposed ILC scheme effectively made the punch position root-mean-square (RMS) errors converge to less than 0.2 mm within five iterations. The precision was also improved to less than 50 μm that was equivalent to 35–40% of the original level without the ILC.
The objective of this paper is to propose a novel press system with six links for precision deep drawing, and verify its feasibility. First, the system is presented and its advantages are discussed. Then, the kinematic analysis of the system is obtained by examining the geometry of the design. Moreover, kinematic dimensions of the variable coupling are found by using optimization method. Furthermore, the proposed approach is illustrated by a design example, its solid model for the proposed design is established, and then kinematic simulation is performed by ADAMS software. Finally, a prototype and an experimental setup are established, and the experiment is conducted. The results show that the proposed new mechanism is feasible and of reasonable accuracy. In addition, it has the advantages of easy manufacture, lower cost, higher precision, and easy adjustability.
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