June 14*» 1938.
M. L. SCHULTE
2,120,577
MACHINE SCREW ANCHOR
Filed March 5 ,
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1937
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INVENTOR
23/ '
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BY
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dl??foé?ff
ATTORNEY
‘2,120,517
Patented June 14, 1938
UNITED STATES
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‘PATENT OFFICE
2.120.517
MACHINE sonnw ANCHOR
Max L. Schulte, Ridgewood, N. J., assignor to The
Rawlplug Company, Inc., New York, .N. Y.
Application March 5, 1937, Serial No. 129,198
9 Claims. (Cl. 72-105)
This invention relates to an expansible an
chor, particularly adapted for machine screws
or studs having‘machine screw threads thereon,
and the like. Such anchors are used in attach—
ing various devices or ?ttings to materials like
stone, brick, concrete or other hard materials
which have to be drilled to receive the screw or
stud anchor, which devices are expanded or
10
caulked into place.
In drilling suchhard materials, the drills have
to be frequently sharpened and they wear down
rather rapidly in diameter, so that in the use of
the same drill, the hole gradually becomes smaller.
For each size of screw or bolt anchor there
15 is. a “best” size of-drill, the diameter of the
anchor and that of the drill being chosen to give
the best holding power by the anchor in the kind
of material in which the anchor is used.
'
In the smaller sizes of anchors, the ?ts are usu
20 ally closer; that is to say, the diameter of the
drill and diameter of the anchor are very near
each other, so --that after the hole has been
drilled, the anchor can be readily pushed into
position for the ?nal caulking operation. How
25 ever, as has been stated, as the drill wears, the
hole becomes smaller, so that the anchor used
_ cannot be put into the hole without using con
siderable force, which cannot be. used without
distorting the mouldable metal of the anchor,
30 thereby rendering insertion into the hole im
practical. Considerable force should be ‘applied
only after the anchor is inserted into the hole,
and then applied by means of the caulking tool.
It is therefore the object of my invention to
35 provide an anchor which will compensate ‘for
the wear on the drill.
Other ancillary objects will appear from a read
40
ing'of the speci?cation, taken in connection with
the annexed drawing, wherein:
Figure 1 is a perspective, elevational view of
my improved form of anchor.
Figure 2 is a vertical, sectional view through
the anchor on the plane 2——2 of Figure 1.
45
Figure 3’is an end view of the anchor in a hole
drilled with a new drill of standard size, and _
Figure 7 shows a further modi?ed form 01' the
same member.
.
Figure 8 shows a modi?ed form of expanding
member and which, in many cases, is the pre- ,
ferred form.
0
Figures 9 and 10 show further modi?ed forms
of an expansible member in which the outer sur
face projections may take different shapes.
Figure 11 shows a still further modi?ed form‘
of expansible member in which the outer surface 0
is broken up into a series of cones of increas
ing diameter toward the caulking end of the
anchor.
I
'
In the various views, wherein like numbers
refer to corresponding‘ parts, I is an expansible 15
member having a plurality of ?utes 2 around
the peripheral surface of said member. The
member 1 fits telescopically over the expand
ing member 3, one end of which has a tapered
surface 4 extending at least part-way of the
length of the member 3. Preferably the tapered 9"’
surface ‘4 is provided with knurls 5 that extend
generally longitudinally of the member 3, and
as shown in Figures 1 and 2. the member I has -
one end normally ?tting onto the tapered sur
face 4 into engagement with the knurls 5. For
shipping and handling purposes, the two mem»
hers I and 3 are forced together su?iciently to
hold them in gripping relationship, so that the
anchor may be handled as a unit.
30
The hole-entering end of the expanding mem
ber 3 is provided with a ?ange 6v which, as shown
in Figure 8, is preferably extended at 1 radially
beyond the beginning of the tapered surface 4,
for the purpose of presenting more resistance to
5
the withdrawal of the anchor by the pull applied‘
thereto through the screws holding the load
or device held in place by the screws. The ?ange
6 also has a tendency to retard the ?ow of the
softer expansible metal over the inner end of the 40
expanding member during the'caulklng opera
tion.
.
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~
In either construction of Figure 2 or 8, the
?ange 6 is of smaller diameter than the outer
boundary surface of the ~?utes 2, and preferably 45
of smaller diameter than that of a drill suitable
before the anchor has been expanded or caulked ‘for
a given anchor at the end of the life of the
'
_Figure 4 is a view similar to Figure 3, but drill. By way of illustration but not of limita
50 showing a condition where the hole has been tion, this diameter may be from V54" to 31;"
smaller, depending on the size’ of the anchor to
drilled with a worm drill.
into ?nal position.
Figure 5 is a view, of the anchor shown in
Figure 4 as it is being inserted into ‘a hole.
Figure 6 shows a modi?ed form of the ex
55 pansible member comprising part of the anchor.
and the use to which it is to be put. The object
of this will be directly explained.
In Figure 3, a hole 8 is shown in the material
9, and the-anchor shown in Figure 1 is shown in
position therein.
In this case, the diameter ‘
2,120,577
2 .
across the edges of the ?utes 2 is no greater
than the diameter of the hole 8, so that the
the anchor .while it is being inserted in the hole.
What I claim is:
anchor may be very readily passed into position.
1. A machine screw anchor comprising an in
ternally threaded expanding member having an
exterior surface at one end tapering toward the
other end, and an expansible member telescop
ically ?tting over the expanding member, with‘
one end engaging said tapered surface, and hav
ing a plurality of surfaceprojections whose outer
and greatest peripheral boundary normally cor
After the anchor is put in place, a tool, having
a pilot thereon to enter the tapped hole l0 in
the expanding member 3, is applied to the outer
end of the expansible member I, usually of lead,’
and by hammer blows on the end of the tool,
which has an annular shank to ?t substantially‘
10 the entire end of the member I, the member I
is driven onto the tapered surface 4 and is caused
to expand into gripping engagement with the
wall of the hole.
'
The longitudinally arranged knurls 5 are to
15 prevent the hard metal cone or expanding mem
ber 6 from turning in the soft expansible metal,
such as lead, when the fastening screw is turned
up tight in the anchor. The knurls may also
assist in spreading the expansible member I.
20
As shown in the various ?gures, the ?utes 2
have been exaggerated in size to better illustrate
the idea. In practice, these ?utes are very much
smaller and greater in number than those shown
in the different views.
In Figure 5, the hole 8 has been made with a
drill that is worn down in diameter, but there
still is a clearance for the ?ange 6 on the expand
ing member. However, it will be seen that the
edges of the flutes 2 strike the peripheral edge
30 of the hole 8, but a slight pressure or tapping on
the outer end of the member I will cause the
edges of the ?utes 2 to either be sheared off or
rolled over as indicated at H in Figure 4. After
responds to a standard drill size, the said mem
bers being positioned so that at least one end
of the expanding member must go into the an
chor hole in advance of the expansible member,
the expanding member having its hole-entering 15
end, adjacent said tapered surface, smaller in
diameter than the maximum diameter of the ex
pansible member, as and for the purpose de?ned
herein.
2. A machine screw anchor as set forth in claim 20
1, further characterized in that the said tapered
surface has knurls thereon for the purposes de
scribed.
3. A machine screw anchor as set forth in claim
1, further characterized in that the hole-entering
end of the expanding member has an annular
?ange adjacent the tapered surface.
4. A screw anchor comprising an internally
threaded expanding member having an external
taper adjacent one end, and an expansible mem 30
ber normally telescopically ?tting over the ex
panding member onto the taper, the' said mem
bers being positioned so that at least one end
the insertion of the anchor, it is then caulked - of the expanding member must go into the an
35 into place as previously described.
The hole-entering end of the expanding mem
ber 3 has a relatively large counter-bore or recess
l2 therein with a tapered opening l3 leading into
the recess I 2. The purpose of this recess and
40 the opening I3 is to provide a receptacle or
' chamber for thedust and chips which may be
in the hole when the anchor is caulked into place.
If it were not for this large recess, some of the
dust and chips might be forced into the threaded
45 hole 10, which would cause trouble in applying
the screw or stud used to hold the device or
attachment to the surface in which the anchor
has been located.
\
The ?utes may be-- arranged in a number of
50 ways; for example, in Figure 6 the ?utes or cor
- rugations are shown arranged in a helical man
ner on member I, the-pitch of the helix being
varied as desired.
In Figure 7 the ?utes or corrugations are
55 transversely arranged.- \
In Figure 9 the ?utes take the form of pointed
projections l4.
In Figure 10 the vprojections may be polygonal
in shape, small pyramidal squares I5 being
60- shown, but in any case, these ?utes or project
ing portions permit forcing the anchor into a
hole in masonry or the like of closer dimensions
than the anchor, without distorting the same.
In Figure 11, the,projecting portions are -in
the form of substantially transversely spaced
?utes i6 which increase in diameter toward the
drive end of ‘the anchor, so that only the last
few or outer ?utes will engage the wall of the
70 hole and be turned over or collapsed in the spaces
behind them. With this arrangement, exceed
ingly little force need be applied to the anchor
while inserting it in the hole, and then only at
the very end of the inserting operation, so that
75. there can be absolutely no chance of distorting
chor hole in advance of the expansible member,
said expansible member having on its outer sur~
face a plurality of projecting collapsible portions,
the outer boundary of at least the projecting
portions of greatest diameter being larger in di
ameter than the hole-entering end of the expand- .-,
ing member as and for the purposes described.
5. A screw anchor as set forth in claim 4, fur
ther characterized in that at least a part of the
taper has longitudinally extending knurls there
on,v with a ?ange between the knurls and the 45
adjacent extremity of the expanding member.
6. A screw anchor as set forth in claim 4, fur
ther characterized in that the projecting portions
are in the form of substantially transversely
spaced ?utes of increasing diameter toward the
drive end of the anchor.
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'7. A screw anchor as set forth in claim 4, fur
ther characterized in that the projecting portions
are such that the screw anchor will not be dis
torted on being inserted into a hole made with
a worn drill which in its normal size would make
a hole that would allow the anchor to be easily
inserted therein.
,
8. In a screw anchor for the purposes de
scribed, including an internally threaded expand 60
ing member carrying an expansible member in
telescopic relationship, the said members being
positioned so that ‘at least one end of the ex
panding member must go into the anchor hole
in advance of the expansible member, means
for compensating for wear of the drill used in
making a hole for the anchor, said means com
prising collapsible projecting portions on the
outer peripheral surface of the expansible mem
ber, while the hole-entering end of the expanding 70
member is normally smaller in diameter than
that of a standard drill of a suitable size for the
chosen anchor, at the end of its life of service.
9. A screw anchor for the purpose described
including an internally threaded expanding mem
2,120,577
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her and a cooperative expansible member, the
said members being positioned so that at least
ing collapsible projecting portions on its outer
one end of the expanding member must go into
surface whereby greater variations may be per- '
the anchor hole in advance of the expansible
member, the hole-entering end of the expanding
member being of smaller diameterthan the hole’,
and smaller than the largest diameter of the
expansible member, the expansible member ha???
mitted in the diameter of the hole made in
masonry or the like for a given size anchor.
MAX L. SCHUL'I'E.