Die Design Fundamentals. Vukota Boljanovic
1.31 Serrations applied in a broaching die.
1.4.7 Broaching
Figure 1.31 shows serrations applied in the edges of a stamping. These would be broached in a broaching die. Broaching operations are similar to shaving operations. A series of teeth removes the metal instead of just one tooth, as in shaving. Broaching must be used when more material is to be removed than could effectively be done with one tooth.
1.4.8 Horning
Horn dies are provided with an arbor or horn over which the parts are placed for secondary operations such as seaming (Figure 1.32). Horn dies may also be used for piercing holes in the sides of shells.
1.4.9 Side Cam Operations
Piercing a number of holes simultaneously around a shell (Figure 1.33) is done in a side cam die. Side cams convert the up-and-down motion of the press ram into horizontal or angular motion when the nature of the work requires it.
Figure 1.32 The seam on this part is done as a secondary operation in a horn die.
Figure 1.33 The holes are pierced simultaneously in a side cam die.
1.4.10 Bending
Bending dies apply simple bends to stampings. A simple bend is one in which the line of bend is straight. One or more bends may be involved (Figure 1.34). Bending dies are a large and important class of press tool.
1.4.11 Forming
Forming dies apply more complex forms to workpieces. The line of bend is curved instead of straight and the metal is subjected to plastic flow or deformation (Figure 1.35).
Figure 1.34 Stamping bent in a bending die.
Figure 1.35 Stamping formed in a forming die.
Figure 1.36 Shell drawn from a flat sheet.
1.4.12 Drawing
Drawing dies transform flat sheets of metal into cups, shells, or other drawn shapes by subjecting the material to severe plastic deformation. Figure 1.36 shows a rather deep shell that has been drawn from a flat sheet.
1.4.13 Curling
Curling dies curl the edges of drawn shells to provide strength and rigidity (Figure 1.37). The curl may be applied over a wire ring for increased strength. You may have seen the tops of sheet metal pails curled in this manner. Flat parts may be curled also. A good example is a hinge in which both members are curled to provide a hole for the hinge pin.
Figure 1.37 Lip on this drawn shell produced in curling die.
Figure 1.38 Bulge in this drawn shell produced in bulging die.
1.4.14 Bulging
Bulging dies expand the bottom of previously drawn shells (Figure 1.38). For example, the bulged bottoms of some types of coffee pots are formed in bulging dies.
1.4.15 Swaging
In swaging operations, drawn shells or tubes are reduced in diameter for a portion of their lengths (Figure 1.39). The operation is also called “necking.”
1.4.16 Extruding
Extruding dies cause metal to be extruded or squeezed out, much as toothpaste is extruded from its tube when pressure is applied. Figure 1.40 shows a collapsible tube formed and extruded from a solid slug of metal.
Figure 1.39 Drawn shell that has been swaged.
Figure 1.40 Drawn shell that has been extruded.
1.4.17 Cold Coining
In cold forming operations, metal is subjected to high pressure and caused to flow into a predetermined form. In coining (Figure 1.41), the metal is caused to flow into the shape of the die cavity. Coins such as nickels, dimes, and quarters are produced in coining dies.
1.4.18 Progressive Operations
Progressive operations are those in which progressive dies perform work at a number of stations simultaneously. A complete part is cut off at the final station with each stroke of the press. Figure 1.42 shows part and strip produced in a progressive die.
1.4.19 Sub Press Operations
Sub press dies are used for producing tiny watch, clock, and instrument components, represented by the watch needles shown in Figure 1.43. Sub presses are special types of die sets used only for such precision work.
Figure 1.41 Cold-coining part in which metal flow is caused by high pressure.
Figure 1.42 Part and strip produced in a progressive die.
1.4.20 Assembly Operations
Assembly dies represent an assembly operation in which two studs are riveted at the ends of a link (Figure 1.44). Assembly dies assemble parts with great speed; they are being used more and more.
From the foregoing, you can perhaps appreciate what a wide field die design engineering really covers. You must have come to realize that it is indeed a pleasant and interesting occupation, one which will stimulate your mind in much the same manner as the working out of fascinating puzzles. In addition, you will come to find that is a very profitable one.
Figure 1.43 Typical precision parts produced in sub press dies.
Figure 1.44 Part produced in an assembly die.
As you study the chapters that follow, you will be introduced, step by step, to the