Deep-drawing

Fig. 13. Various forming operations (a) backward extmsion (b) deep drawing (c) spinning (d) bending (e) stretching (f) stamping (g) coining (h)...

Alloying elements such as nickel, chromium, molybdenum, and copper, which may be introduced with scrap, can increase the hardenability, although only slightly, because the concentrations are ordinarily low. However, the heat-treating characteristics may change, and for appHcations in which ductihty is important, as in low carbon steels for deep drawing, the increased hardness and lower ductiHty imparted by these elements may be harmful. 

Tin, even in low amounts, is harmful in steels for deep drawing. For most appHcations, however, the effect of tin in the quantities ordinarily present is negligible. 

Much can be predicted from these parameters. Linear correlations have been estabhshed between the R value and the drawabhity parameter, LDR. Thus higher R values are associated with better deep drawabhity. AR, on the other hand, predicts the height and location of ears. Eor example, larger absolute values of AR predict higher ears during deep drawing cup shapes. 

An additional virtue of many copper alloys is the capacity for deep drawing such as cartridge cases and flexible beUows. C260 and C510 are weU known for their drawabiHty. Be—Cu that is drawn and then aged is used for beUows that have exceUent fatigue life. 

Neutral cleaners (non-caustic based) These are ethylene oxide condensates, and easily emulsify the mineral oils and greases. They are more useful for sheet-metal components, which contain no lead compound lubricants (as used for deep-drawing operations), and are also suitable for non-ferrous... 

Plastic instability is very important in processes like deep drawing sheet metal to form car bodies, cans, etc. Obviously we must ensure that the materials and press designs are chosen carefully to avoid instability. 

Mild steel is a good material for deep drawing in the sense that it flows a great deal before necking starts. It can therefore be drawn very deeply without breaking (Fig. 11.7). 

At first sight, the same is true of aluminhim alloys. But because they are heavily alloyed (to give a high yield strength) their ductility is low. If expense is unimportant, this does not matter, some early Rolls-Royce cars (Fig. 27.6) had aluminium bodies which were formed into intricate shapes by laborious hand-beating methods, with frequent annealing of the aluminium to restore its ductility. But in mass production we should like to deep draw body panels in one operation - and then low ductility is much... 

Slides Necked tensile specimens of metals deep drawing operations and deep-drawn cans, etc. 

Austenitic steels have a number of advantages over their ferritic cousins. They are tougher and more ductile. They can be formed more easily by stretching or deep drawing. Because diffusion is slower in f.c.c. iron than in b.c.c. iron, they have better creep properties. And they are non-magnetic, which makes them ideal for instruments like electron microscopes and mass spectrometers. But one drawback is that austenitic steels work harden very rapidly, which makes them rather difficult to machine. 

An analysis of the brass tube is performed to assess the likely eapability using CA. Referring to the proeess eapability map for deep drawing shown in Figure 2, and determining the material, m, and geometry, g, variability risks gives ... 

Dried granules may be injection moulded, blow moulded and extruded without undue difficulty with melt temperatures of 220-260°C. The moulding shrinkage (0.003-0.004 cm/cm) is very low and a somewhat greater than normal draft may be required in deep draw moulds. 

Aloru, S., Bartoli, P., Leoni, M. and Memmi, M,. In Proc. Ini. Deep Drawing Research Group Conference. Amsterdam, Netherlands, 1985, Hoogoven IJmuiden BV, Paper 19. Davis, G.D, Groff, G.B., Biegert, L.L, and Heaton, H, J. Adhes., 54, 47 (1995). 

Tiefebene,/. low plain, lowland, tiefeingreiiend, a. penetrating thoro(ugb tiefen, v.t. deepen deep-draw. cup. Tiefen-gestein, n. plutonic rock, lehre, /., -messer, m. depth gage. -schSrfe, /. (Pho tog.) depth of focus. 

Tiefung,/. deepening deep-drawing, cupping depression. 

Tin coatings are ductile and are able to contribute a lubricating effect in the deep drawing of steel. The presence of the thin alloy layer in flow-melted tinplate coatings does not impair this property appreciably but bright electrodeposited coatings may be less ductile than others. 

Two general types of sheet steel are in current use, viz. cold-rolled mild steel and decarburised steel. A typical analysis for cold-rolled steel is 0-1% C, 0-5% Mn and 0-04% S. It can be obtained in regular, deep drawing or extra-deep drawing grades. This type of steel is normally used with a ground-coat including cobalt and nickel, as shown in Table 16.1. 

We use plug assisted thermoforming when we wish to make thick-walled products or thin-walled, deep draw products. The principal steps of the process are illustrated in Fig. 16.2. The first two stages are similar to those of vacuum forming. Once the sheet has been clamped, a plug made from a material with low heat conductivity is thrust downwards into the cavity,... 

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