Factory and industrial management . y the Mar-tin open-hearth basic process. The plates employed in Bavarian prac-tice have, for flanged work, a tensile strength of 32 to 38 kilogrammesper square millimetre with a minimum elongation of 25 per cent, thesum of the two values being 62 minimum. The rest of the shell plateshave a tensile strength of 36 to 42 kilogrammes per square millimetrewith a minimum elongation of 22 per cent, the sum of the two being,in minmum, 61. Tests Include bending the plates through an angle yi2 THE ENGINEERING MAGAZINE. of i8o degrees, hot and cold, and bending, after
Factory and industrial management . y the Mar-tin open-hearth basic process. The plates employed in Bavarian prac-tice have, for flanged work, a tensile strength of 32 to 38 kilogrammesper square millimetre with a minimum elongation of 25 per cent, thesum of the two values being 62 minimum. The rest of the shell plateshave a tensile strength of 36 to 42 kilogrammes per square millimetrewith a minimum elongation of 22 per cent, the sum of the two being,in minmum, 61. Tests Include bending the plates through an angle yi2 THE ENGINEERING MAGAZINE. of i8o degrees, hot and cold, and bending, after hardening, around amandrel to a diameter equal to twice the thickness of the plate. Teststrips 10 centimetres wide, and red-hot, must enlarge 1^/2 times theirbreadth under the hammer without showing crack or other flaw. Therivets of mild steel have a tensile strength of 34 kilogrammes persquare millimetre with 20 per cent elongation, the minimum sum ofthe two values to be 54. The bending tests are the same as for thel)oiler FIG. 6. MAFFEI-BUILT SPECIAL BOILER-DRILLING PLANT. The plate-working shop at Maffeis is a fine building replete withbending rolls, planers and drills; but it is in a small annex to the oldboiler-makers shop that we find an interesting machine tool speciallydesigned by Maffei for drilling the stay holes of very large modernfireboxes. A snap-shot view of this in Figure 6 shows that the fire-box is clamped down by the throat sheet to a revolvable drilling machine is permanently fixed to the side of the boiler multiple drilling heads, with the operators platform, move up ordown the vertical slides, the controlling gear enabling rapid settingof the cutting tools to the punch marks on any part around the wholecontour and height of the box. The inner box is of copper of thepurest quality— per cent minimum—and of 21 kilogrammes persquare millimetre tensile strength; 42 to 45 kilogrammes sectionalcontraction in minimum, and 38 p
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Keywords: ., bookcentury1800, bookdecade1890, booksubj, booksubjectengineering
