3 Fundamentals of press design

6 Solid forming (Forging)
6.1 General
Processes and parts
The terms sheet metal forming and solid forming are based on practical
industrial application, and subdivide the field of forming technology
into two distinct areas. This distinction is made in addition to the definitions
established by DIN 8582 “Forming” (cf. Fig. 2.1.3). Solid forming
entails the three-dimensional forming of “compact” slugs (for
example sheared billets), while the sheet metal forming method generally
processes “flat” sheet metal blanks to create three-dimensional hollow
structures with an approximately constant sheet metal thickness.
The forces exerted during solid forming are substantially higher than
those necessary for sheet metal forming. As a result, it is necessary to
use relatively rigid compact-design machines and dies. Solid forming
involves not only the processes of extrusion, indentation and drawing
which are dealt with in most detail here, but also for example rolling,
open die forging (cf. Fig. 2.1.4) or closed die forging (cf. Fig. 2.1.5).
The processes cold extrusion and drawinginvolve forming a slug or billet
placed in a die, most commonly for the production of discrete parts.
Hot extrusion uses a basically similar forming mechanism to create
semi-finished products such as rods, tubes and sections. The basic processes
involved in cold extrusion (Fig. 6.1.1) are classified depending on their
forming direction as forward, backward and lateral extrusion and also
according to the final form of the workpiece as rod (solid), tube and cup
extrusion. When producing solid parts, the classical operations of cold
extrusion technology are supplemented by processes like upsetting and
ironing (Fig. 6.1.2). The shape variety of parts formed from slugs or bil-
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998