IMPROVEMENTS IN MACHINERY FOR THE MANUFACTURE OF SCREW NUTS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Charles Stiff at the Office
of the Commissioners of Patents on the 31st December 1878.
WILLIAM CHARLES STIFF, of Birmingham, in the County of Warwick, Merchant
and Manufacturer. "IMPROVEMENTS IN MACHINERY FOR THE MANUFACTURE OF
SCREW NUTS."
My Invention consists of the improvements in machinery for the manufacture of
screw nuts herein after described, by which machinery blanks having cylindrical
holes in them may be manufactured, the said blanks being afterwards made into
finished screw nuts by having screw threads cut in their cylindrical holes. Or the
said machinery, by modifications as herein after described, may be employed to
manufacture screw nuts having screwed holes in them.
My said improvements consist essentially in the combination of dies and tools
actuated by hydraulic, steam, or other power, so constructed and worked that by
their operation the heated end of a rod of iron or steel is cut off from the rod and
compressed in a die of the figure of the screw nut to be made, the cutting off and
compression of the metal being effected by a punch. The punch is cylindrical if
the nuts are to be made with cylindrical holes in them, and has a screw thread on
it if screwed holes are to be made in the nuts.
The said dies and tools are constructed and arranged essentially as follows:-
Two cylindrical dies with enlarged ends or heads are situated in the same (pre-
ferably horizontal) axial line. One is fixed, and the other is capable of advancing
towards and receding from the fixed one. In the moveable die is an axial hole of
the diameter of the rod from which the nut is to be made, and in the head of this
die is a cavity or mould, which I will call the nut cavity, having the figure of the
exterior of the nut to be made. The other die carries a cylindrical punch. The
cool end of the rod from which the nut is to be made is inserted in the moveable
die, which is then made to approach the fixed die. The punch in the fixed die
forces back the rod into the cylindrical holes in the moveable die until only sufficient
The motion of
of its heated end protrudes from the nut cavity to form the nut.
the rod is arrested at the required point by a rod or ejector working in the rear
ת

page_text: end of the moveable die. The further motion of the moveable die causes the punch
to force or upset the beated end of the rod into the nut cavity, first partially filling
the said cavity with the plastic metal, and afterwards making the cylindrical hole
therein. The final motion of the moveable die effects the cutting off of the nut
from the rod by the cutting edge of the front of the punch, and the edge of the
hole at the base of the nut cavity. The ejector yields slightly to admit of the
receding motion of the rod during the cutting off process; at the same time the face
of the head of the fixed die, against which the metal above the level of the nut
cavity is pressed, forms the top face of the nut. The retiring moveable die carries
the nut with it, as well as the punch in its interior, until the stem of the latter is
withdrawn from its die; the ejector now comes into action, and the further retiring
motion of the moveable die effects the ejection of the nut and punch from the nut
cavity, and the rod of iron or steel from the cylindrical hole in the moveable
die.
When the hole in the nut is to be screwed the following modifications are made:
-The punch is cylindrical only at its front end, the rear acting part having a screw
thread, the counterpart of that to be made in the nut; and provision is made to
allow a slight retiring motion in the screw punch after the cutting off of the metal
from the rod has been effected. By this arrangement the screw punch is made to
travel with the nut cavity during the compression of the heated metal into the
screw threads of the screw punch by the pressure of the head of the fixed die.
The arrangement of the dies and tools described may be duplicated, so as to
make a double acting machine, the advance motion of the parts at one end being
coincident with the retiring motion of the parts at the other end. Two or more
sets of dies and tools may be stationed at each end of the machine. The rods from
which the screw nuts or nut blanks have been cut may be made into screw bolts or
otherwise utilized.
Although I prefer to employ rods of iron or steel of a length sufficient after a
screw nut or nut blank has been cut off to form a screw bolt, yet short rods con-
taining little more metal than suffices to form the screw nut or nut blank may be
employed. In this case the short heated rod is inserted in the hole in the moveable
die a sufficient distance to hold it, and give it a central position, the rod being
supported by the ejector. The punch acts in forming the nut in the manner
already explained, its final advance being arrested by a thin wad of chilled metal.
The ejector is then allowed to retire sufficiently to permit the punch to cut out
the wad, thus leaving a clear hole either for a nut blank or a screwed nut, as
required.
When long rods are employed screw nut or screw nut blanks are made without
the production of scrap or waste pieces.