Showing papers on "Forging published in 2001"

Friction Stir Processing: A New Grain Refinement Technique to Achieve High Strain Rate Superplasticity in Commercial Alloys

Abstract: Friction stir processing is a new thermo-mechanical processing technique that leads to a microstructure amenable for high strain rate superplasticity in commercial aluminum alloys. Friction stirring produces a combination of very fine grain size and high grain boundary misorientation angles. Preliminary results on a 7075 Al demonstrate high strain rate superplasticity in the temperature range of 430-510 °C. For example, an elongation of >1000 % was observed at 490 °C and 1 × 10 -2 s -1 . This demonstrates a new possibility to economically obtain a superplastic microstructure in commercial aluminum alloys. Based on these results, a three-step manufacturing process to fabricate complex shaped components can be envisaged: cast sheet or hot-pressed powder metallurgy sheet + friction stir processing + superplastic forging or forming.

Metal Forming Analysis

Abstract: 1. Mathematical background 2. Introduction to the finite element method 3. Finite elements for large deformation 4. Typical finite elements 5. Classification of finite element formulations 6. Auxiliary equations: contact, friction, incompressibility 7. Thermo-mechanical principles 8. Sheet metal formability tests 9. Steady state forming problems 10. Forging analysis 11. Sheet forming analysis 12. Recent research topics.

Improvement of hot forging manufacturing with PVD and DUPLEX coatings

Abstract: The application of a DUPLEX treatment, which included low pressure pulsed plasma nitriding of AISI H11 tool steel dies and PVD BALINIT® FUTURA-TiN/TiAlN multilayered coating, was studied as a possible technology to improve the process of hot forging of steel components. The quality of the DUPLEX treatment was determined by laboratory analyses of coated test plates, which were treated together with the hot forging dies. Surface roughness, Vickers microhardness including in-depth measurements, coating thickness and adhesion parameters determined by the REVETEST method and microanalysis (SEM and EDS), were investigated. Performance tests were made in real working conditions in the UNIOR hot forging industry in Zrece, Slovenia, and included three types of technological processes: (a) form milling of graphite electrodes (to produce dies by the electrical discharge machining process with cemented carbide cutters improved with a BALINIT® Diamond coating); (b) hot forging of steel components (with two step forging dies fixed in a 1650 t eccentrically driven press, improved with the DUPLEX treatment); (c) hole punching in forged parts (with dies made of ASP30 tool steel and improved with a standard PVD TiN coating). The hole punching in forged parts and milling of graphite electrodes were performed successfully in practice for many years. In hot forging, the first positive results were obtained after three experimental studies in the last two years. Optimisation of the parameters of the DUPLEX treatment is still needed before this technology can be introduced into regular manufacturing operations for hot forged steel parts.

Improvement of hot-working processes with PVD coatings and duplex treatment

Abstract: Optimisation of manufacturing processes in mechanical engineering which involve working temperatures higher than 600°C and high surface loads, e.g. pressure die-casting, hot extrusion and hot forging, is today under intensive investigation worldwide. Traditional production procedures and the enormous quantities of products in these industries are serious limitations to the introduction of any kind of improvement to moulds, tools and dies with PVD coatings and duplex treatment. Thus, the simulation of selected tribo-systems is practically impossible and any performance testing of new technologies must therefore be carried out in real industrial manufacturing. In this paper we discuss the properties of surface improvements relevant to these topics. These comprise PVD CrN, TiAlN and FUTURA TiN/TiAlN multilayer coatings, and duplex treatments, including plasma nitriding (PN) and all three PVD coatings. We studied the applications of CrN, PN+CrN and PN+TiAlN in aluminium pressure die-casting, CrN in hot extrusion of Al and FUTURA and PN+FUTURA coating in hot forging of steel parts. Performance tests were carried out in various industrial plants in Slovenia. The results show that an improvement in tool or die life (cost saving) of up to several 100% is not the decisive factor. More important for these traditional industries are better reproducibility of the surface quality of the products, an increase in the manufacturing reliability in heavy machining, a decrease in manufacturing interruption (down-time) and finally, the protection of the environment.

Rail welderhead shear apparatus

Abstract: A flash butt rail welding welderhead combines in a single unit, the ability for the three functions of rail pulling, flash butt forging and maintaining the “after forged” displacement without any change in platen position such that shearing may be accomplished in three stages, a single stage, multiple stages or a progressive stage, all while maintaining clamping and stretching force on the rails.

Metal superplasticity enhancement and forming process

Abstract: A shaped metallic component is formed by friction stirring at least a segment of a single piece of bulk metal to impart superplasticity thereto and thereby yield a single superplastic metal blank from the single piece of bulk metal. The metal blank is then deformed by a metal deformation process such as forging, rolling, drawing, bending, extruding, gas forming, punching, and stamping.

Macro-fiber process for manufacturing a face for a metal wood golf club

Abstract: A near-net shape titanium club face for a metal wood golf head is manufacturing with improved product structure and performance. More specifically, the invention provides a metal wood golf club head face consisting of layers of grain fibering by controllable grain flow along face-orientation and surface contours, similar to composite structures, for improved directional strength, impact strength and toughness, as well as hitting face thickness design flexibility for improved hitting sound and increased coefficient of restitution without sacrificing face performance and durability. The hitting face is made by precision hot-die forging in closed dies through large (α+β) forge deformation to net or near-net shape from a β-treated work piece. Alternatively, the process may be applied to aluminum alloys or steels.

A volume decomposition approach to machining feature extraction of casting and forging components

Abstract: This paper reports a method for machining feature extraction of forging and casting components. It employs a volume decomposition approach to map machining removal faces into machining processes. The geometric reasoning from the characteristic surfaces produced by machining operations forms the basis of the recognition process. There are three phases in the mapping process: (1) Boolean decomposition of the final part model and raw part model; (2) identification of machined faces (M-faces) and concatenation of M-faces into groups (M-group); and (3) mapping M-groups into all feasible machining process types. This recognition technique is process oriented, which is able to overcome the limitation of new feature additions. This approach is also able to deal with some types of feature intersecting. The results can be used directly for process planning of complicated geometric parts, e.g. casting and forging components.

Real-Time Process Characterization of Open Die Forging for Adaptive Control

Abstract: Open die forging is a process in which products are made through repeated, incremental plastic deformations of a workpiece, Typically, the workpiece is held by a manipulator. which can position the workpiece through program control between the dies of a press. The part programs are generated with an empirically derived parameter, called the spread coefficient, whose value is subject to some contention. In this work, we demonstrate how process information can be used in real time to derive the actual spread coefficient for a given workpiece as it is being formed. These measurements and calculations occur in real time, and can be used to regenerate part programs to optimize the forming process, or can be used to adaptively control each incremental deformation of the workpiece.

Rotary forging and quenching apparatus and method

Abstract: A rotary forging and quenching apparatus and method forms and rapidly cools an axial-symmetric object from a spin formable material. The process uses a preheated billet which is clamped between opposed fixture mandrels which have a circumferential die shape and with quench solution channels running through the fixtures. The mandrels are spun and at least one contour roller of a mating circumferential die shape is brought into bearing contact against the billet in order to spin-form the material into the desired die shape. The mandrel and peripheral margin of the spinning billet are flooded with a quench solution coolant while being spin formed. This process streamlines the manufacturing of wheels or other axial-symmetric parts like cylinders, hemispheres, cones, etc. Typically, parts that require heat treatment, like aluminum alloys, will benefit from this process. The process minimizes the distortion encountered in heat treatment and eliminates the need to add extra material to ensure final dimensions. This reduces material, machining and manufacturing costs.

Forging characteristics of AZ31 Mg alloy.

Abstract: Characteristics of open die forging in an AZ31 Mg alloy and a relation between microstructure and mechanical properties of the forged alloy have been investigated for an as-received specimen and an extruded specimen, where the as-received specimen consisted of both elongated coarse grains and equiaxed small grains, and the extruded specimen consisted of only equiaxed small grains. Each specimen was forged at 323 to 673 K . In addition, tensile tests of the forged specimens were carried out at room temperature and the microstructure was observed using an optical microscope. In the forging tests, the specimens could be forged from 18 mm to 2.5 mm in thickness at forging temperatures of more than 423 K . In particular, the specimen could be forged without surface cracks when the grains were refined by extrusion prior to forging. However, for the as-received specimen, some cracks were observed at the edge of the specimens forged at less than 573 K . Therefore, it is suggested that the microstructure of the pre-forged specimens needs to be homogeneous, in order to attain a good surface quality, when forging is carried out at temperatures less than 573 K . The grain size of the forged specimens decreased with decreasing forging temperature. It should be noted that a very small grain size of about 3 \\micron was attained by forging at 473 K . The tensile strength and the 0.2% proof stress of the forged specimens increased with decreasing forging temperature due to grain refinement by forging.

Method for processing a striking plate for a golf club head

Abstract: A method for producing a forged striking plate for a golf club is disclosed herein. The forging process involves multiple heating and pressing of a metal bar to obtain a final face member configuration. The heating of the metal bar is performed at temperatures below 1000° C. for less than twenty minutes. The final face member configuration has a striking plate with regions of variable thickness. The metal bar is preferably composed of a forged titanium material.

High-strength porous silicon nitride fabricated by the sinter-forging technique

Abstract: Porous silicon nitride with aligned fibrous grains was fabricated by sinter-forging technique, where uniaxial pressure was applied to achieve a specific density after soaking at elevated temperatures. Fibrous silicon nitride grains were formed during the soaking, and the grains were aligned by the subsequent forging. As the result, a specimen with strongly aligned fibrous silicon nitride grains was successfully fabricated. The specimen with a relative density of 76% exhibited high bending strength of 778 MPa.

Shape optimization of axisymmetric preform tools in forging using a direct differentiation method

Abstract: A method for computing shape sensitivity in the frame of non-linear and non-steady-state forging is presented. Derivatives of tool geometry, velocity and state variables with respect to the shape parameters are calculated by a direct differentiation of discrete equations. Because of the important part played by the accuracy of finite element calculations, an efficient transfer method is used between meshes during remeshings and the contact algorithms are carefully differentiated. The resulting inverse design procedure is successfully applied to two industrial examples of forging of automobile parts, with fold-over and piping defects occurring during the intermediate designs. It makes it possible to suggest reasonable preform shapes, with or without any available knowledge of the forging process. Copyright © 2001 John Wiley & Sons, Ltd.