Unit Manufacturing Processes Issues and Opportunities in Research (1995) / Chapter Skim
Currently Skimming:
6 Deformation Processes
6 Deformation Processes
Pages 79-92
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 79... ...
and is plastically deformed between tools, or dies, to obtain the desired final geometry and tolerances with required properties (Altar, 19831. A sequence of such processes is generally used to form material progressively from a simple geometry into a complex shape, whereby the tools represent the desired geometry and impart compressive or tensile stresses to the deforming material through the tool-material interface, as illustrated in Figure 6-1 for the cases of extrusion and deep drawing.
|
From page 80... ...
The workpiece undergoes large plastic deformation resulting in an appreciable change in shape or cross section. · The portion of the workpiece undergoing permanent plastic deformation is generally much larger than the portion undergoing elastic deformation.
|
From page 81... ...
In addition to shape change, forming processes also alter the metallurgical structure of the workpiece and may be used to enhance material properties. Such improvements may eliminate the need for heat treatment and provide property combinations that were previously unattainable.
|
From page 82... ...
Energy transfer occurs within the plastic deformation zones as heat and external forces are transferred to the workpiece material by fanning equipment through the tooling and the interfaces between the tooling and workpiece. ~ In forging, the entire workplace may undergo plastic deformation nearly simultaneously.
|
From page 83... ...
selecting equipment and tooling designs based on the prediction of the forces and stresses necessary to execute the forming operation. Incoming Material Billet or Sheet Blank Material properties under processing conditions (i.e., flow stress of the deforming material under various temperature, strain, and strain-rate conditions)
|
From page 84... ...
Surface condition Thermal/physical properties Initial conditions Microstructure evolution Product/Final Material Geometry Dimensional accuracy/tolerances Surface finish Microstructure and properties Deformation Zone Deformation mechanics Kinematics Stress state Temperature Tooling Geometry Surface conditions/coatings Material/heat treatment/hardness Temperature Conditions at Tool/ Material Interface Lubricant Heat transfer Process Equipment Speed/production rate Force/energy capabilities Rigidity and accuracy Resources and Environment Available manpower Air, noise, and waste water pollution Plant and production facilities and control must be known in order to analyze, simulate, and optimize a deformation process. The flow properties of the incoming material are determined by its chemical composition and previous thermal and mechanical treatment history.
|
From page 85... ...
on the subsequent forming operations.2 Information essential for the prediction of microstructure evolution during deformation processing using process modeling must be developed and made 2 Development and application of material preparation processes, typically mass-change processes, are improving dimensional control of incoming materials.
|
From page 86... ...
To date, research efforts have had limited success in developing knowledge-based systems to aid in part designs and process sequence selection for improved formability. Current major trends in manufacturing products by deformation processing include: deformation-formed parts with complex geometries, such as gears with formed teeth, trunnions, and universal joint components (Pale et al., 1992)
|
From page 87... ...
Advances in the development and use of finite-element methods to solve nonlinear plastic deformation problems have led to practical solutions for twodimensional deformation processes (Kobayashi et al., 1989~. Work is now being done to extend process models that are based on finite-element methods to estimate parameters such as elastic defection of tooling, tool life, distortion of the formed part, and microstructure and properties of formed parts and to predict the occurrence of workpiece defects (Knoerr et al., 1992~.
|
From page 88... ...
Studies are being conducted to measure and predict lubricant behavior and heat transfer at the tool-material interface in support of lubricant coatings development based on an understanding of mechanisms of erosive tool wear. This is an extremely important area, since tool life directly influences the economics of deformation processes.
|
From page 89... ...
expanded capability to measure material behavior, friction, and part Listed below are research opportunities to advance the state of the art in deformation unit processes. · Research efforts are needed to generate, evaluate, and systematically store flow stress and formability data for both sheet and billet materials under actual processing conditions (i.e., high temperature, strain, and strain-rate regimes)
|
From page 90... ...
· Research is needed to establish tooling design guidelines for reducing tool stresses, improving lubricant distribution, and influencing metal flow in dies. Work is needed to link the tool stresses, calculated by using f~nite-element programs, to tool fracture and fatigue criteria that are obtained experimentally for various tool materials and configurations.
|
From page 91... ...
53~0 in Vol. 20 of the Proceedings of the North American Manufacturers Research Conference held May 1992 in Pullman, Washington.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.