Page 140 - Ship Construction.DJ Eyres 6Ed

Ch13-H8070.fm Page 129 Wednesday, October 18, 2006 6:56 AM
Plate and Section Preparation and Machining 129
generally consist of a single drilling head mounted on a radial arm which
traverses the drill bed.

GUILLOTINES Smaller ‘one-off’ plate shapes such as beam knees, vari-
ous brackets and flat bar lengths may be cut in a hydraulically operated
guillotine. Plate feed to the guillotine is usually assisted by the provision of
plate supporting roller castors, and positioning of the cut edge is by hand.
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PRESSES Hydraulic presses may be extensively used in the shipyard for a
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variety of purposes. They are capable of bending, straightening, flanging,
dishing, and swaging plates (see Figure 13.2). All of the work is done with
the plate cold, and it is possible to carry out most of the work undertaken by
a set of rolls. This is done at less capital cost, but the press is slower when
used for bending and requires greater skill.

PLATE ROLLS Heavy duty bending rolls used for rolling shell plates,
etc., to the correct curvature are hydraulically operated. Two lower rolls are
provided and are made to revolve in the same direction so that the plate is
fed between them and a slightly larger diameter top roll which runs idly (see
Figure 13.3). Either or both ends of the top roll may be adjusted for height,
ึ

PLATE SWAGING PLATE FLANGING OR
BENDING

EDGE CURVING PLATE STRAIGHTENING

FIGURE 13.2 Gap presses