IMPROVEMENTS IN DIE-STOCKS AND TAPS
Year: 1884

page_text: I, BRUNO WESSELMANN, of Hamburg, Germany, Engineer, do hereby declare the
nature of said Invention for "IMPROVEMENTS IN DIE-STOCKS AND TAPS " to be as
follows:-
This Invention relates to improvements in screw-taps and in dio-stocks with
loose dies, and the objects of iny improvements are; first, to compose the dies
and taps of discs placed one above the other in axial direction; and, second, to
provide devices for adjusting the depth of the screw-thread in conjunction with
the aforesaid.
The dies are composed of discs placed one above the other inside the ring of the
stock, and pressed together by suitable devices. Inside the ring of the stock are
projections, which engage into corresponding recesses of the discs, thus preventing
the latter from rotating. The screw-thread on the interior of the discs is cut out
in order to form a number of cutting teeth, which may be arranged either exactly
one above the other or alternately.
When the thread has to be cut deeper as is usually the case, or when the discs
may become worn, the upper disc may be provided with a small radial slit, thus
forming a spring-part, which can be pressed towards the center of the disc by a
screw, or equivalent device, such as by attaching a bearing to the stock ring. A
pair of knives, chisels or cutters is placed therein, and connected by a slide-piece.
A screw serves to press them toward the interior of the stock ring, which latter is
provided with suitable openings or apertures. A spring wound around the knives
or chisels and pressing against the slide-piece is thereby compressed and consequently
will withdraw the knives or chisels, when the screw is loosened. Evidently, the
perforations of the stock-ring, where the knives or chisels pass through, are inclined
according to the pitch of the thread, viz., for a right-hand-thread, towards one side,
and for a left-hand thread towards the other.
The screw-tap, also, may be composed in a similar manner of cutting discs, which
have an outside thread. A bolt joints the discs provided with a central perforation
in such a manner, advantageously, that between each pair of cutting discs is placed
a smooth disc of smaller diameter, in order to facilitate the removing the chips. A
nut presses all the discs tightly together. The teeth of the cutting discs may also
be arranged alternately.

page_text: I, BRUNO WESSELMANN, of Hamburg, Germany, Engineer, do hereby declare the
nature of my invention for "IMPROVEMENTS IN DIE-STOCKS AND TAPS," and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement:-
This invention relates to improvements in screw taps and in die-stocks with
removable dies; and the objects of my improvements are, first, to compose the dies
and taps of discs placed one above the other in axial direction; and, second, to
provide the die-stocks with devices for adjusting the depth of the screw thread.-
I attain these objects by the mechanism illustrated in the accompanying
drawings, in which
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Figure 1 is a top view of a die stock, and Figure 2 a vertical section thereof;
Figure 3 shows top views of the discs composing a die; Figure 4 is a top view and
Figure 5 a vertical section at the line C D, Figure 4, of a die stock for right hand
thread, with a modified adjusting device; Figure 6 is a top view of the same die-
stock, arranged for cutting a left hand thread; Figure 7 is a vertical section
thereof at the line E. F, Figure 6; Figure-8 is a sectional side elevation at the
Jine 1 K, Figure 4, of the bearing for the adjustable cutters; and Figure 9 is a
cross section thereof at the line GH, Figure 4; Figures 9ª and 9b show the forms
of the adjustable cutters. Figure 10 represents the tap, and Figure 11 a plan of a
disc composing such tap.
Similar letters refer to similar parts throughout the several views.
The dies are composed of a number of cutting discs a, placed one above another
inside of the ring of the stock, and they are clamped and held together by means
of the nut b, which latter screws into the ring x above the discs, or other suitable
devices may be employed for this purpose. On the inside of the ring of the
stock there are lugs or projections c, which engage with corresponding notches or
recesses in the edges of the discs a, for the purpose of locking the latter and
preventing them from turning.
On the interior of each of the discs there are formed the several sets of screw
cutting teeth, and the discs aro so located within the ring x, that the teeth of
one disc alternate with those of the next, though they may come in line with
each other.
In order to provide for adjustment of the cutting teeth for cases where it is
desired to cut deeper than usual, or whero the discs become worn, one of the discs
is made adjustable. The upper disc a', as illustrated in Figure 1, is provided with
a radial slit, so that it becomes an open spring ring; one end can be pressed towards
the centre of the disc by means of the adjusting screw d. By turning the screw
in, the cutting teeth carried by that end of the disc are made to project farther into
the open centre of the disc, thus causing them to cut deeper.
The same effect can be attained by the device shown in Figures 4, 5, 6, 7 and 9.
A bearing or extension g, attached to the stock ring x, carries a pair of cutters c of
the shape as illustrated by Figure 9. These cutters are attached to a sliding
block i, sliding within tho bearing g, and the screw bears against the block, and
is employed to adjust said cutters which project through a suitable opening e¹
in the stock ring and an oblique slit in the cap ring or washer p. The opening e'
is inclined according to the pitch of the thread, a coiled spring f, encircling the
cutters e, is interposed between the stock ring and the slide block i and operates to
withdraw the cutters when the scrow his unscrewed.

page_text: A modification of the form of such cutters is shown by Figure 9b. The cutters
are in this case made with oblique cutting edges &³, and they are placed with the
lines of their cutting edges reversed so that they cross each other. By turning the
die stock in one direction for cutting a thread, only one of the cutters comes into
action, but by re-turning the die stock in the reverse direction, the other cutter
will cut, thus producing a very clean and sharp screw thread. These cutters are
separately adjustable; consequently two adjusting screws and two retracting
springs are used, one for each cutter.
It will be understood that the same tool is adapted to be used for cutting both
right and left hand threads, and to this end two openings c' in the stock ring are
provided, which are to be inclined according to the pitch of the thread, viz.; for a
right hand thread towards one side, and for a left hand thread in the opposito
direction, as it is illustrated by Figure 7, and the cutter holder g is made reversible,
and employed in the manner as will bo understood from Figures 4 and 6 of the
drawing.
The tap as shown in Figure 10 is composed in a similar manner of cutting
discs, which are provided with outside thread. A triangular or polygonal or
keyed bolt, with a square head, joints the discs 1, provided advantageously with
central triangular or otherwise corresponding openings, in such a manner that
between each pair of cutting discs is placed a smooth disc m of smaller diameter,
in order to facilitate the removing of the chips or fragments. Such alternately
The teeth
smooth and threaded discs are clamped together by means of a nut n.
of the cutting discs may also be arranged alternately in axial direction.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. In die-stocks the combination of discs a arranged axially one above the other
with the stock ring and nut b or its equivalent, substantially as set forth.
2. In die-stocks the combination of the slotted disc a' with the screw d and solid
discs a within the stock ring a, substantially as and for the purpose specifiod.
3. In die-stocks the combination of the stock-ring with the reversible cutter
holder g and the adjustable cutters e or their equivalents as illustrated by Figure 9b,
substantially as and for the purpose specified.
4. In screw taps the combination of screw cutting discs and smooth discs m
with the bolt and nut n, substantially as set forth.