Press Line Research Articles

Contactless feeder for electrically conductive sheet metals

Today, the cyclic feeding of sheet metals in metal forming machines is realized by means of mechanical roll or grip feeders. The limited feeding forces as well as the restricted dynamics and the potential for damaging the sheet surface as a result of mechanical contact often restricts the production rate of the entire press line. At the IFUM, a new contactless feeding system has been developed, based on the asynchronous linear motor, with which high feeding forces can be applied to the electrically conductive sheet metal contactless by means of electromagnetic forces. In this paper, the feeder’s operation characteristics depending on the sheet material properties and also on their geometry are presented. According to simulations and experiments the feeding forces could be significantly increased in comparison to reachable forces in case of using roll feeders.

Friction and lubrication modeling in sheet metal forming simulations of a Volvo XC90 inner door

The quality of sheet metal formed parts is strongly dependent on the tribology, friction and lubrication conditions that are acting in the actual production process. Although friction is of key importance, it is currently not considered in detail in stamping simulations. This paper presents a selection of results considering friction and lubrication modeling in sheet metal forming simulations of the Volvo XC90 right rear door inner. For this purpose, the TriboForm software is used in combination with the AutoForm software. Validation of the simulation results is performed using door inner parts taken from the press line in a full-scale production run. The results demonstrate the improved prediction accuracy of stamping simulations by accounting for accurate friction and lubrication conditions, and the strong influence of friction conditions on both the part quality and the overall production stability.

Friction and lubrication modelling in sheet metal forming simulations of the Volvo XC90 inner door

The quality of sheet metal formed parts is strongly dependent on the friction and lubrication conditions that are acting in the actual production process. Although friction is of key importance, it is currently not considered in detail in stamping simulations. This paper presents project results considering friction and lubrication modelling in stamping simulations of the Volvo XC90 inner door. For this purpose, the TriboForm software is used in combination with the AutoForm software. Validation of the simulation results is performed based on door-inner parts taken from the press line in a full-scale production run. The project results demonstrate the improved prediction accuracy of stamping simulations.

The Influence of Speed and Press Factor on Oriented Strand Board Performance in Continuous Press

Three-layer cross-oriented strand boards, OSB type 3 of 10 mm thick, were industrially manufactured from a mixture of wood species including 50% softwoods, 25% beech, and 25% low hardwoods, using a continuous press line. The effects of line speed and press factor on physical and mechanical properties of OSB/3 (exterior grade) were evaluated, keeping nearly constant the face-core adhesive ratio. The manufactured boards were classified into five groups depending on the pressing parameters. The experimental results showed that all mechanical properties increased, with increasing press factor and decreasing line speed. The ratios of bending strength (MOR) and the modulus of elasticity (MOE) parallel to perpendicular were 1.73 to 1.89 and 2.18 to 2.24, respectively. No significant differences in thickness swell and water absorption were observed. The lowest density was achieved at higher speed, although there was no large variation in densities between groups. Thickness swelling and internal bond after boil test exceeded the EN 300 standard requirements for OSB/3 moisture resistance, excepting a few boards. The results revealed that a correlation between speed and press factor is necessary in order to improve mechanical properties and to keep the physical performance of boards within a limited range of values.

Optimization of Production Takt for Automatic Press Line Based on Synchronous Motion of Press and Robot

Motion synchronization is a new pattern in robot and press collaboration. In this paper, a synchronous motion algorithm of robot and press to improve production takt of automatic press line is proposed. First of all, we investigate the influence of different velocity and acceleration on identical trajectory of Fanuc handing robot with 6-degree of freedom (DOF), finding the robot trajectory is independent of the velocity, and is essentially coincident in the same acceleration. Moreover, we present a synchronous motion algorithm on the basis of the trajectory invariance and the velocity formula. The algorithm is approached from the point of view of path planning, takt optimization goal and design formulas. It can automatically adjust robot velocity by eliminating the waiting time at the loading and unloading passage. Finally, the results of simulation experiments have demonstrated the efficiency of the proposed algorithm. It can effectively get around robot frequent clutches and the brakes to achieve the goal of optimizing production takt.

Water-Air Spray Cooling of Extruded Profiles: Process Integrated Heat Treatment of the Alloy EN AW-6082

Quenching by spray cooling in the press line is a promising way to harden Al-Mg-Si alloys with regard to reducing profile distortion. For alloys such as EN AW-6082, high cooling rates are required. A device for spray cooling by means of water and compressed air was integrated into a 10 MN horizontal, hydraulic, short-stroke extrusion press. Various spray parameters were investigated. By using 32 water-air nozzles having a total water deposition rate of about 15 L/min and extruding with a profile velocity of 2.5 m/min, high mechanical properties were imparted to 30 mm diameter extruded rods. This arrangement ensures the extruded alloy is cooled to almost room temperature. Comparable properties can be achieved by water quenching, although the water consumption will be tenfold higher. The distribution of water deposition density on the profiles’ surfaces was determined. It was shown that an adjustment of the water-air pressure ratio allows the final temperature of the profiles to be controlled over a wide range. Minimization of temperature gradients in the cross section of complex profiles allows profile distortions to be reduced.

Springback Simulation of the Process Chain Press Line Forming and Roller Hemming Processes

In recent years the process simulation of entire manufacturing chains in sheet metal forming has gained more ground on its way to be established in the validation of feasibility and the meeting of quality targets. Nowadays, especially the simulation of manufacturing automotive sheet metal components such as doors, hoods roofs etc., using the finite element analysis, belongs to state of the art in the development process of sheet metal components. The different joining technologies in the bodyshell work, such as riveting, welding etc., can be simulated by numerical methods. Rarely are any of these methods linked to the forming simulations of the previous process step. Further developments in this field should deal with new strategies, linking both the forming simulation and the joining simulation. Regarding the process chain press line forming and bodyshell work, the prediction of springback of closure assemblies is of special interest, and thereby new strategies for springback compensation have to be developed in an early stage of product development. Until now, only few experiences have been gained concerning application of method to calculate springback of an assembly, so far a reliable comparison between simulation and reality is required. For this reason in this paper a closer examination of an automotive hood assembly was carried out to develop and to validate a corresponding simulation model. Based on close-to-production experiments and optical surface measurements of outer skin components (doors, bonnets, trunk lids etc.) and their assembly prior start of series production, a new simulation strategy was developed for a consistent process chain for the press plant and bodyshell work. The assembly in this example was comprised of an inner and outer panel. For forming objectives of both parts, finite element simulations were conducted, including secondary forming operations, as for instance trimming and flanging including individual unloading sequences. In a following simulation step both parts were joined together by roller hemming. Finally, a springback analysis of the assembly was also conducted. The simulation method illustrates the possibility of predicting springback of assemblies. Furthermore, the experiments and simulations show, that the springback of the assembly leads to different final shapes than those obtained from individual components. With this method it is possible to predict the final shape and the influence of the individual components on shape and dimensional accuracy, aiding the optimization of the assembly process.

An efficient algorithm for press line optimisation

Automated manufacturing processes such as automotive tandem press lines include time dependent complex control functions. All motions and critical interactions between moving parts must be synchronised to avoid collisions and reach high production rate. It is even for a skilled operator hard to optimise these processes on-line. Therefore, a hardware-in-the-loop simulation including real industrial control systems and its control code establish an essential tool for optimisation. Additionally, an efficient optimisation algorithm is required to reach a useful simulation-based optimisation method. This paper proposes a new optimisation algorithm starting with the Lipschitzian algorithm DIRECT as global search and then switches over to the Nelder-Mead simplex algorithm for local convergence. During the switch over, the new algorithm determines all local candidates of the set of points evaluated by DIRECT and starts multiple Nelder-Mead local searches in each of these. An optimisation study for an automotive press line shows that the proposed algorithm combines the benefits of the Lipschitzian and the simplex algorithms in an efficient way. The importance of multiple local searches from all local candidates found is also shown in the study. Based on the same number of function evaluations, it is also shown that this algorithm reaches improved press line performances compared to the stochastic differential evolution algorithm.

Research on Radio Frequency Identification Technology in Automated Press Line

Automated press line is a kind of very important device in the production of automobiles, and its production quality and efficiency have a direct influence on the production efficiency and quality of automobiles. Automated pressing is the effective measure and major way to increase the productivity and improve the working conditions. Some pressing workshops is taken as examples in this paper to research into the working requirements of radio frequency identification (RFID), the interference in the process of identification, the selection of RFID reader, the selection of label, device purchasing, and the connection with computers, so as to make a comparison between the moulds and manage the moulds.

Time-synchronised hardware-in-the-loop simulation — Applied to sheet-metal press line optimisation

This paper presents an off-line process parameter tuning method, focussing on complex control functions for automated manufacturing systems. The proposed method is based on a combination of simulation-based optimisation and time-synchronised hardware-in-the-loop simulation. Real industrial control systems, e.g., PLCs, are included in the simulation, executing the unchanged control code from the manufacturing plant. This approach allows all plant control functions to be included, even time-critical feedback loops and vendor secret blocks such as motion control. Consequently, the method suggested manages the problems identified in previously presented simulation-based approaches. Furthermore, a case study of an automotive sheet-metal press line has been performed to verify the proposed method, with successful results.

프레스 라인 적정 로트 크기의 결정에 관한 사례 연구

This paper develops a mathematical model which searches an optimum lot size of a press line, and applies this model to the scheduling of the press line. This mathematical model is not a widely studied cost model but a model which considers the utilization of the press line under a lean production system. In this paper, the optimum lot size is a minimum lot size which does not exceed the total work time of the press line. A production volume and the priority of the production in the press line are adjusted using this optimum lot size. A mathematical model developed in this paper will allow determining the optimum lot size easily in case of variable production environments such as an introduction of a new product and a fluctuation of production volume of each item. Therefore, our model will make a better scheduling of the press line and will enhance the utilization of it.

進化する高速サーボプレスタンデムライン

進化する高速サーボプレスタンデムライン

Optimization of Motion Control in High-Speed Servo Press Line

Honda Engineering Co., Ltd. developed an innovative servo press line that achieves the world’s highest level of productivity in producing deep-drawn automotive body panels. The innovative press production system was made so that the press forming conditions and panel transfer motions are adjusted to the dies very accurately for each part to be produced. The servo press line is planned to be expanded to Honda’s production plants on a global scale while allowing further evolution.

Improving setup time in a Press Line – Application of the SMED methodology

The market environment in which companies are included nowadays has dramatically changed with the reduction of tax barriers, which consequently increased the competitiveness. Competing in an international market is now a reality for all enterprises and in consequent, the effect of globalization is even more felt. Therefore, companies have once again to gather efforts and reduce their production costs through waste elimination and productivity increase.SMED (Single Minute Exchange of Die), a tool created by Shigeo Shingo allows waste reduction in productive processes, making it more efficient and flexible. This approach proposes waste elimination through the reduction of non-production time in each machine, more precisely, the reduction of the time needed for tool change in a machine (or setup time). Its application has a special incidence in the automotive sector and in the plastic industry. In this article, SMED will be apply to a press line in the automotive industry in which the use of a Gantt chart in SMED's time study will be proposed in order to consider parallelism between operations.

Virtual manufacturing for press line monitoring and diagnostics

Virtual manufacturing, or manufacturing simulation, can be divided into three domains: product domain, process domain, and resource domain. This paper focuses on the use of virtual manufacturing for press line monitoring and diagnostics. It contains an introduction to virtual manufacturing, divided into a general part on modelling and simulation, verification, validation and acceptance, and the division into the three domains, as well as a specific part on the use of simulation in these domains for sheet metal products, processes and processing equipment. The main software tools discussed in this paper are discrete event simulation and computer-aided robotics; the designed and implemented machine service support system is an example of advanced use of three-dimensional (3-D) graphical simulation in the resource domain. This system offers remote on-line monitoring and diagnostics functions as well as media player-type functions such as replay that allow a service and maintenance expert to analyse disturbances that occur at remote locations. A key feature of the system is 3-D graphical simulation with I/ O synchronisation. This type of system is particularly useful for system integrators and machine builders that install press lines and press cells world-wide and need to guarantee a high level of availability of the installed machinery.

Tribological Properties of Hybrid Process DLC Coating against Magnesium Alloy

The tribological properties of hybrid process DLC (Diamond-like carbon) coating against magnesium alloy are examined in order to understand the basic friction and wear properties of DLC coatings against magnesium alloy and partially to simulate the drawing process in real transfer press line. The tests are conducted using simple ball or pin on disc system with various combination of uncoated/DLC-coated WC-Co (cemented carbide) and AZ31B specimen in room/elevated temperature and dry/lubricated environments. As the result, DLC coating has excellent tribological properties against AZ31B magnesium alloy at 250/260°C, which is the actual hot-working drawing condition of AZ31B sheet, in both dry and lubricated environment. DLC coating prevents possible adhesion between AZ31B and WC-Co at elevated temperature in less lubricated or nearly dry contact condition.

Grey target theory based equipment condition monitoring and wear mode recognition

Grey target theory is a newly developed method in grey system theory. Calculating with grey target theory, pattern recognition, mode gradation and optimal mode selection can be performed. Oil samples from one auto press line and one 16V280ZJA diesel engine were analyzed by analytical ferrograph. For every wear particle in every analytical result, the size and quantity were quantified together. And some corresponding series have been established. Grey target theory was applied and a “bull's-eye” was constructed. By calculating the approaching degrees, wear modes have been graded, in conjunction with the running conditions of the press line and the diesel engine for given operation modes. The order of existing wear modes from severe to benign has also been assessed. The results agree with the experts’ analysis. This is the first time that grey target theory has been applied in oil monitoring for wear mode recognition.

Auto producer opts for in-line plant

GERMAN automotive component manufacturer Menzolit-Fibron has installed a Dieffenbacher direct process press line for the production of composite underbody panels for the Volkswagen Group. This is a short news story only. Visit www.reinforcedplastics.com for the latest plastics industry news.

CONTROL SYSTEM VERIFICATION BY EMULATION: AN APPLICATION TO OFF-LINE PRESS LINE THROUGHPUT RATE OPTIMIZATION

This study is part of a research project aims at off-line programming and verification of industrial control systems. In this paper, an off-line method for press line throughput rate optimization and control system verification is proposed, implemented and evaluated. The main tool is a virtual press station, developed by the first author, consisting of an emulated control system for a feeder/extractor robot which communicates with 3D-simulated production equipment. Moreover, several virtual press stations have been coupled and synchronized in a virtual press line. An important feature of the system is that the virtual robot controller is emulated, yielding an exact representation of the control logic and the possibility to run the entire system in virtual real time. The application considered is a sheet metal forming process where it is difficult to achieve maximum capacity utilization. There is much to gain if the control logic is improved and the throughput rate is increased. For this purpose, an automated robot motion optimization method is implemented and evaluated, using the virtual press line.

Chosen Aspects of Building Robotized Lines (Two Practical Examples)

The paper describes the robotized medium size press line and the TV-tubes graphite coating line, designed and build in Poland. The chosen aspects i.e. basic user requirements and exploitation experience are also presented and discussed in connection with the positive results obtained.