Press-working of Metals by Oberlin Smith

Author:Oberlin Smith
Language: eng
Format: epub
Publisher: Wiley
Published: 1896-03-25T05:00:00+00:00

Fig, aSa. Fro. 283.

be this thickness, m, at the points n, o, and^, as the metal would then exactly fill between at all points. Practically, however, it is better to give an embossing-die clearance at such points as « and o, letting the metal follow the " tight points " to suit itself, as in the picture. This is desirable, because some of the metal may be a little too thick, or dirt may

:umulate in the dies, in either of which cases there would "be a jam between the points n and Oy which would prevent the dies coming down home, or which, at any rate, would require a great deal more pressure to do the work. Another reasoi> for this clearance is the practical difficulty of the die-maker being perfectly sure that there is space enough everywhere^ unless he follows the method here given, of being sure there is enough by having too much. It is customary to give a little clearance at / also, but this is not of so much importance, as contact at that point would simply prevent the flat surfaces from coming together quite so tight.

A simple method devised by the writer, and long practiced by those working under his instructions, for ascertaining the clearance of forming and embossing dies is to lay pieces of small lead wire, whose diameter may be about two times niy across the dies at the. various points requiring a test. Between these points small pieces of the sheet-metal to be used, whose thickness is /«, are laid upon the lower die to act as blockings so that the proper stopping-point of the upper die may be insured. The press ram is then brought hard down, with the result of the lead being smashed out to the varying thicknesses, represented by the spacing of the dies, and as shown in Fig. 283. It is evident that all such points as n and o ought to be thicker than m, and this is generally easily determined by the eye. Such points as/ must, of course, never be less than m^ and may be a little more.

Cutting-Forming-Embossing.

Almost all the various processes of forming and embossing may be combined with cutting, and with each other, wherever the work is of suitable shape. The tools for conducting such operations are usually called ** combination dies," although the term is not very definite, being sometimes used, as before described, for the combining of two or more sets o£

PRESS-WORKING OF METALS.

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