Improvements in Devices for Facilitating the Connection of Articles of Stone or other Material by Means of Screws.
Year: 1899

page_text: Date of Application, 25th Nov., 1899
Complete Specification Left, 23rd Aug., 1900-Accepted, 29th Sept., 1900
Improvements in Devices for Facilitating the Connection of Articles of
Stone or other Material by Means of Screws.
I, WILHELM FRIEDRICH LOFFELHARDT, of Hansaplatz 9, Hamburg, in the
Empire of Germany, Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention relates to devices for use in securing screws in holes formed in
hard material such as stone wood or the like, the characteristic feature being
the special construction of locking plates provided with teeth upon both sides
thereof, one or more of these plates being inserted in the holes into which the
screw is to be held.
These plates which may advantageously be made of hoop-iron or the like are
provided upon each face with teeth or projections formed by stamping or other-
wise which are bent outwardly said teeth or projections being so arranged as
to point in opposite directions to each other with regard to the position of the
plate in the hole, and in this manner several of such plates may be disposed in
the hole into which the screw is to be driven, so as to form a passage having
its external teeth directed towards the walls of the hole, while the internal
teeth are arranged to form a kind of interrupted screw-thread, with which the
screw engages.
By driving the screw into its place, one set of the teeth or projections take
into the threads of the screw, which latter forces the plates slightly apart, and so
cause the other set of teeth or projections thereof to grip into the walls or surface
of the hole. If the screw is intended to secure two parts of similar or different
materials together, such as wood and stone, and has been passed through the
wood and into the stone so far as to press the said wood against the hole and
thus form a bearing for the screw-head, the further driving of the screw then
causes the plates to advance until they come in contact with the wood and thus
cause the teeth or projections to become more and more strengthened outwards
and strongly press' them into the walls or surface of the hole, so as to form an
exceedingly secure means of uniting the two parts together.
In order to enable the inner teeth to form a large contact surface with the
threads of the screw they may be set at an angle to suit the pitch thereof.
Instead of forming the plates in separate parts they may be connected together
at the rear end or longitudinally so as to form a single piece, and if desired the
teeth may be formed at the narrow edges of the plates; the number of plates
used varying according to circumstances.
Dated this 25th dow of November 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: Improvements in Devices for Facilitating the Connection of Articles of
Stone or other Material by Means of Screws.
I, WILHELM FRIEDRICH LOFFELHARDT, of Hansaplatz 9, Hamburg in the
Empire of Germany, Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:
The present invention relates to improvements in devices for facilitating the
attachment of screw bolts when inserted in a brick or stone wall or the like;
and the object of the same is to procure a secure and reliable fastening of the
screw-bolt when the latter is driven into its place.
I attain this object by the means illustrated in the accompanying sheet of
drawings in which-
Figure 1 is a side elevation,
Figure 2 an edge view,
Figure 3 a back or rear view and
Figure 4 an end or top view of an improved device embodying my invention.
Figure 5 is a side elevation.
Figure 6 an edge view, and
Figure 7 an end or top view of a modification of my improved device.
Figure 8 is a section through a brick or other hard material with a screw
attached or fastened therein by means of a pair of the improved dowel plates.
Figure 9 is a cross section on the line I-II (Figure 8).
The improved device consists of a thin metal plate a¹ (Figures 1-4) which
is suitably shaped in cross section and provided, upon both of its sides, with a
series of inclined projections or teeth b, c, said teeth being so arranged that
those on one side point or extend in opposite direction to the teeth on the other
side, or the edge face or faces respectively.
In order to fasten a screw f (see Figures 8 and 9) in hard material, for
instance in a brick d, a hole e is made in the said brick into which hole are
inserted one or more of my improved plates. The plate or plates are to be
inserted into the hole in such a manner that the inner teeth point towards the
bottom or end of the hole and the outer teeth towards the entrance of the hole,
said inner teeth thus forming a sort of discontinuous or interrupted female screw-
thread.
In the examples shown by Figures 8 and 9 there are inserted into the hole c
two dowel plates a¹ having teeth 61 el projecting respectively from their opposite
faces in opposite directions. On screwing a screw-bolt f into the screw-thread
formed by the plates a¹ the teeth b₁ engage the male threads of the screw, which
latter forces the plates apart and so causes the outer teeth c¹ thereof to press
against and grip into the walls of the hole e. When the screw f has been
screwed home as far as to press the body or object g to be attached to the brick,
against the outer face or wall of the brick, the further screwing home of the
screw f, since the object g or the like, forms a bearing or abutment for the
screw-head f¹, causes the plates to advance, that is to say, to slightly move
towards the entrance of the hole. By this longitudinal displacement of the said
plates the teeth 61 as well as the teeth e¹ are more and more straightened up in
opposite directions; the latter being thereby at the same time strongly pressed
against or into the walls of the hole e in order to secure a firm and reliable
hold of the plates, and therefore of the screw in the brick d.
When plates having no outer teeth are used, (such as shewn in Figures 5 to 7)

page_text: the said plates are pressed with their outer sides or edges against the inner
walls of the hole and held therein by friction which latter may be inoreased by
serrating or rifling that side of the plate destined to come in contact with the
walls of the hole; as this is self-evident it therefore needs no further descrip-
tion and illustration.
In order to enable the inner teeth of the dowel, that is to say the teeth acting
against the male thread of the screw, to have a great contact surface with the
said male thread they may be set at an angle to suit the pitch thereof, as shewn
in the drawing.
Instead of forming the plates in separate parts, two or more plates may be
connected at the rear end so as to form a single piece consisting of two or
more plates the free front ends of which are capable of being spread apart by a
screw screwed into such plate. As this construction is easily to be under-
stood from the above an illustration of the same is unnecessary.
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. A device for securing a screw or the like in a hole in a hard material,
consisting of one or more sheet metal plates having separated teeth projecting
from opposite faces and inclined in opposite directions, those on one face set to
form an interrupted screw-thread for and of greater depth than that of the
thread on said screw, so that when the latter is screwed home the teeth on
opposite faces of the dowel plate or plates will be drawn in opposite directions,
substantially as described and illustrated by the accompanying drawings and
for the purpose specified.
2. A device for securing a screw or the like in a hole in a hard material,
consisting of one or more sheet metal plates having separated teeth set to form
an interrupted screw thread for and of greater depth than that of the thread
on said screw, so that when the latter is screwed home the said teeth will be
drawn in a direction opposite to the path of the screw. substantially as described
and illustrated by the accompanying drawings and for the purpose set forth.
3. A device for securing screws or the like in a hole in walls of brick or
stone, comprising a metal dowel having a flexible screw-thread adapted to be
engaged by the thread of the screw, and of greater depth than that of said screw,
whereby when the latter is screwed home the thread on the dowel is drawn
towards the head of the screw, for the purpose set forth.
4. As an article of manufacture, a device consisting of a sheet metal plate
having comparatively wide and long teeth set to form an interrupted spiral
thread, for the purpose set forth.
5. As an article of manufacture, a device comprising a sheet metal plate
having comparatively wide and long teeth set to form an interrupted screw-
thread projecting from one face, and substantially similar teeth inclined in an
opposite direction and projecting from the opposite face of said plate, substan-
tially as described and illustrated by the accompanying drawings and for the
purpose specified.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.