Showing papers on "Stamping published in 2008"

Virtual cutting and optimization of three-axis milling processes

Abstract: This paper presents generalized process simulation and optimization strategies to predict and improve the performance of three-axis milling operations. Cutter-part engagement conditions are extracted from a solid modeling system, which can handle free form part surfaces found in dies and molds. The cutting force distribution along the engaged cutting edge-part surface is evaluated based on the laws of mechanics of milling. By integrating the distributed force along the cutting edge, total forces, torque and power are either predicted analytically using closed-form solutions, or numerically if the cutting tool shape is discontinuous. Simulation results are then used in a constraint-based optimization scheme to maximize the material removal rate (MRR) by calculating acceptable feedrate levels. The proposed virtual milling system is demonstrated experimentally in milling a stamping die with free form surfaces.

Analytical prediction of springback based on residual differential strain during sheet metal bending

Abstract: As the springback of sheet metal during unloading may cause deviation from a desired shape, accurately predicting springback is essential for the design of sheet stamping operations Finite-element

Non-isothermal stamp forming of continuous tape reinforced all-polypropylene composite sheet

Abstract: This paper describes the thermoforming behaviour of a self-reinforced composite based on co-extruded polypropylene (PP) tapes. In contrast to traditional continuous woven glass fabric reinforced polypropylene (GF/PP) materials, where the sole mode of deformation is either inter- or intraply shearing, all-PP composites have an additional mode of deformation as here the fibres (or in this case tapes) can still be deformed. The importance of this additional deformation mode is investigated in a range of stamping experiments in combination with 3D strain mapping experiments. Non-isothermal thermoforming experiments revealed that all-PP woven fabric laminates based on flat tapes deform in a different manner to traditional GF/PP. Although the main mode of deformation of both all-PP and GF/PP for the investigated dome parts was intraply shearing, a much lower energy was required to deform the all-PP laminate. Whenever possible, deformation of the tape by drawing should be avoided as it requires higher energy which may lead to higher residual stresses in the final part. However, tape drawing may prove an essential benefit when complex shapes are involved.

Application of an integrated CAD/CAE/CAM system for stamping dies for automobiles

Abstract: The globalization and competition in the automobile industry makes it necessary to reduce the time spent on product development Therefore, computer aided product development has become one of the most important techniques in the automobile industry According to the concurrent engineering concept, an integrated CAD/CAE/CAM system for automobile stamping die development is established The system is based on 3D surface construction CAD software STRIM, CAD/CAE software CATIA, stamping formability analysis software DYNAFORM, CAM software CADCEUS, a stamping design knowledge-based system, and a product database This paper uses the development of trunk lid outer panels as an example to showcase the power of the system, in which the different development stages can be performed simultaneously The system can greatly reduce the development time and cost, improve the product quality, and push products into the market in a relatively short time

Organic thin film transistors and polymer light-emitting diodes patterned by polymer inking and stamping

Abstract: To fully realize the advantages of organic flexible electronics, patterning is very important. In this paper we show that a purely additive patterning technique, termed polymer inking and stamping, can be used to pattern conductive polymer PEDOT and fabricate sub-micron channel length organic thin film transistors. In addition, we applied the technique to transfer a stack of metal/conjugated polymer in one step and fabricated working polymer light-emitting devices. Based on the polymer inking and stamping technique, a roll-to-roll printing for high throughput fabrication has been demonstrated. We investigated and explained the mechanism of this process based on the interfacial energy consideration and by using the finite element analysis. This technique can be further extended to transfer more complex stacked layer structures, which may benefit the research on patterning on flexible substrates.

Direct Nanoscale Patterning of Metals Using Polymer Electrolytes

Abstract: Disclosed herein are electrochemical fabrication platforms for making structures, arrays of structures and functional devices having selected nanosized and/or microsized physical dimensions, shapes and spatial orientations. Methods, systems and system components use an electrochemical stamping tool such as solid state polymeric electrolytes for generating patterns of relief and/or recessed features exhibiting excellent reproducibility, pattern fidelity and resolution on surfaces of solid state ionic conductors and in metal. Electrochemical stamping tools are capable high throughput patterning of large substrate areas, are compatible with commercially attractive manufacturing pathways to access a range of functional systems and devices including nano- and micro-electromechanical systems, sensors, energy storage devices, metal masks for printing, interconnects, and integrated electronic circuits.

Stamping device and method of manufacturing article

Abstract: PROBLEM TO BE SOLVED: To reduce a stroke on the X-Y surface of an X-Y stage included in a stamping device. SOLUTION: The stamping device forms a resin pattern in a shot by curing a liquid resin while keeping pressing a mold against the liquid resin arranged in the shot of a substrate in a Z-axis direction. The stamping device includes: a scope for measuring positioning misalignment on the X-Y plane between a mold mark formed in the mold held by a mold chuck and a substrate mark formed on the substrate held by a substrate chuck; a dispenser for arranging the liquid resin in the shot; and a reference mark provided on the X-Y stage. The X-Y stage includes its travel range so that the dispenser can arrange the liquid resin in all shots of the substrate held by the X-Y stage, and the reference mark is provided at a position on the X-Y stage capable of measuring positional misalignment to the mold mark within the travel range of the X-Y stage by a scope. COPYRIGHT: (C)2010,JPO&INPIT

Modelling the effect of forming history in impact simulations: evaluation of the effect of thickness change and strain hardening based on experiments

Abstract: Stamping processes induce plastic strain and changes in the thickness, shape and mechanical behaviour of sheet metal parts. Simulated crash tests on vehicles should theoretically take these changes into account in order to be as realistic as possible, but this is not actually feasible because the calculations required would be too time-consuming. Crash-modelling calculations, therefore, have to be based on simplifying hypotheses about the geometry and the mechanical behaviour of body parts. This study deals with the influences of such hypothesis on the impact behaviour of a 1-mm-thick steel dome bulged plastically at different thick strain levels ranging from -37% to -6% and impacted by an instrumented projectile with 13 m/s initial speed. Experimental results are compared to several impact finite element simulations based on different simplifying hypotheses about the geometry of the bulge and the strain hardening of the sheet metal and performed with the LS-DYNA finite element code.

Surface structure stamping method for manufacturing e.g. safety and/or valuable document, involves providing stamping device with stamping tool having contact area, where contact area is larger than upper side or lower side of substrate

Abstract: The method involves providing a substrate (10), and stamping a surface structure (23) into an upper side and/or a lower side of the substrate with a stamping device (14) under application of a stamping pressure and under usage of ultrasonic. The stamping device is provided with a stamping tool (15) with a contact area (22), where the contact area is larger than the upper side or the lower side of the substrate. The stamping tool is designed as a sonotrode connected with an ultrasonic source i.e. piezoelectric crystal. The substrate is conveyed to the stamping device by a conveyor. An independent claim is also included for a device for stamping surface structure in a substrate.

Principle and applications of multi-point matched-die forming for sheet metal:

Abstract: To reduce the cost and cycle time in fabrication of the conventional stamping die, a new forming technology, so-called multi-point matched-die forming (MPMDF), has been developed based on the discretization of the die. In MPMDF, the fixed shape matched-dies of conventional stamping are replaced by a pair of opposed matrices of movable punch elements. Using multi-point matched-dies generated by punch matrices, a variety of three-dimensional sheet parts of different shapes can be produced. Taking advantage of the flexibility of the multi-point die, new sheet forming techniques have been developed, which realize the formation of parts of large size and with large deformation. In this paper, the principle of MPMDF and the new forming techniques are described, new MPMDF equipment is introduced, and typical application examples are presented.

Semiconductor device package having features formed by stamping

Abstract: Embodiments of the present invention relate to the use of stamping to form features on a lead frame of a semiconductor device package. In one embodiment, portions of the lead frame such as pins are moved out of the horizontal plane of a diepad by stamping. In certain embodiments, indentations or a complex cross-sectional profile, such as chamfered, may be imparted to portions of the pins and/or diepad by stamping. The complexity offered by such a stamped cross-sectional profile serves to enhance mechanical interlocking of the lead frame within the plastic molding of the package body. Other techniques such as selective electroplating and/or formation of a brown oxide guard band to limit spreading of adhesive material during die attach, may be employed alone or in combination to facilitate fabrication of a package having such stamped features.

A processing method of titanium alloy closing end

Abstract: The invention discloses a processing method of a titanium alloy end socket. The invention is characterized in that a stamping component is protected by utilizing a clamping plate, a suitable ram head and a suitable lift-ring are selected, and the specified stamping temperature, the stamping speed and the stamping times are given to perform hot stamping processing to a work piece, and an inner profile and an outer profile of the product after the hot stamping is ensured to meet the requirement of subsequent processing; the hot processing is performed after the stamping. The invention mainly used for the processing of the titanium alloy end socket of the casing of a satellite tank, the end socket material processed is smooth, the shape is well, and the percent of pass is high.

Transient dynamical analysis of strain signals in sheet metal stamping processes

Abstract: On-line monitoring of stamping processes can be carried out based on various sensors, such as force, strain, acceleration, proximity, and acoustic emission sensors. The strain sensor signal is the most favourite because of its effectiveness and acquisition cost as well as it contains rich information about the stamping process. The key problem of stamping monitoring is how to extract features from the strain signal to effectively detect the faults. The strain signal, however, is a transient signal that depends on many factors. In this paper, it is intended to address some new methods to analyse the transient strain signal with the objective of decomposing it in order to understand the dynamics of the stamping process and extract a malfunction signal for fault detection. A latent process model method, which is a combination of a time-varying auto-regression model and a dynamic linear model, is initially presented. Continuous wavelet transforms and a new discrete wavelet transform (maximum overlap discrete wavelet transform) are then addressed to project the transient signal into a time scale plan to represent the dynamical behaviour in a different way. Empirical mode decomposition is finally employed to decompose the transient signal into a finite and often small number of intrinsic mode functions (IMF). The advantage of this new method is that it is adaptive and highly efficient. The performance of the methods employed in this paper is reviewed using two real strain signals in a sheet metal stamping process. It is found that these methods can efficiently provide the energy–frequency–time distribution of the transient strain signal.

Sheet metal punching device

Abstract: A metal plate stamping device at least comprises a convex die, a concave die opposite to the convex die and a blank holder sheathed on the outside of the convex die for butting against and fixing the metal plate on the surface of the convex die, wherein the blank holder is provided with bumps on the surface close to the die cavity of the concave die and toward a direction of the concave die, an insulating layer is arranged on the bonding surface of the die cavity of the concave die and the concave and the blank holder at corners away from the interface of the die cavity and the bonding surface, and the metal plate stamping device also comprises a high-energy pulse power supply which is connected with the blank holder and the concave die at both terminals. A current path is formed through the bumps of the blank holder, the metal plate and the corners of interface of the convex die cavity and the bonding surface, so that the high-energy pulse current can be applied among the bumps of the blank holder, the maximal deformation region of the metal plate and the corners of the concave die, thereby achieving electro-plasticity effect in the metal plate stamping process, obviating heating the entire mold, further reducing the power consumption and achieving less mold deformation.

Process parameters influence on friction coefficient in sheet forming operations

Abstract: In conventional sheet forming processes, such as stamping or drawing, significant contact phenomena take place between workpiece and die surfaces. Especially, relative motion and normal loads generate friction which influences some aspects of processes such as material flow, tools wear and life and total force needed to complete the process. In the current paper an experimental test campaign has been carried out using a large scale pin-on-disk device designed and realized by the Authors to investigate the influence of pressure, sliding velocity and temperature. The purpose is to test the developed device and to find which and how these parameters mostly affect friction. The pin-on-disk test consists of two specimens, a pin and a plate representing respectively die and workpiece, which are compressed by means of a known force and then moved one over the other. Compression and friction forces are sampled during the tests and the friction coefficient is estimated as the ratio of these two forces. The tested materials are H13 die steel on FeP04 and AZ31 sheets.

Experimental investigation of formability of woven textile composite preform in stamping operation

Abstract: This paper presents experimental stamping operation on woven textile composite preform made of commingled E-glass fibers reinforced Polypropylene (PP) with strain measurement by conductive fiber sensors. A series of stamping tests are implemented in the university lab at room temperature, from which a previously proposed theoretical criterion of wrinkling is validated. Through the measured shear distribution and evolution, the deformation behaviour of textile fabric is found to be a result of cooperation of both mould shape and initial sample orientation, helping to build up a simplified model of the composite sheets during their hot forming process. Finally, the stamping parameters were optimized according to the experimental and theoretical work.

Experimental tool of woven reinforcement forming

Abstract: An experimental device of dry preforms stamping was designed and carried out for the first stage of the RTM process. This tool was developed to test the feasibility to obtain specific double curved shape constituted with dry fabric reinforcement. Optical strain measurement can quantify defects on the composite piece. It is just enough to change the desired punch-die set of the preform. This tool could be used to validate numerical simulation of the process.

Simulation of dissimilar tailor-welded tubular hydroforming processes using EAS-based solid finite elements

Abstract: Developments in the numerical simulation of the hydroforming process of tubular metallic components, tailor-welded before forming, are presented. Both technologies, tailor-welded joining operations and hydroforming processes, are well known in industry, although most commonly separately used. Tailor-welded joining operations are usually encountered in plain sheets, subsequently formed by stamping. Tube hydroforming processing, on the other hand, is frequently associated with parts consisting of uniform thickness, material properties, and dimensions. The present analysis focuses on the influence of process parameters, such as the position of the weld-line and initial thickness values, in the innovative process of combining tailor-welded tubes (with distinct thickness values) and hydroforming. Particular attention is posed on the relation of imposed axial displacement vs. imposed hydraulic pressure into the tube, forming parameters that are not known a-priori in the manufacturing of a new part. Another point of practical interest is the numerical simulation of the weld-line movement, after forming is complete. The finite element method is directly employed in the numerical simulation by means of innovative solid elements suited for incompressibility applications, and included by the authors into the commercial program ABAQUS as user-elements. The obtained results can then lead to a better understanding, along with design tools, for the process of hydroforming of tailor-welded tubular parts, accounting for dissimilar thickness of the basic components.