Buckles – buttons – clasps – etc. – Bale and package ties – hose clamps – Metal bands
Reexamination Certificate
2000-02-24
2001-01-30
Brittain, James R. (Department: 3626)
Buckles, buttons, clasps, etc.
Bale and package ties, hose clamps
Metal bands
C024S0200CW, C024S0200TT, C072S324000, C072S379200
Reexamination Certificate
active
06178601
ABSTRACT:
FIELD OF INVENTION
This invention relates to so-called open clamps using a plastically deformable ear for tightening the clamp, and more particularly to a mechanical connection in the overlapping band portions of such clamps with the use of at least one hook performing a guide function in one band portion engaging in at least one aperture in the other band portion.
BACKGROUND OF THE INVENTION
So-called open clamps made from band material, usually galvanized steel or stainless steel, which utilize a plastically deformable “Oetiker” ear for tightening the clamp have been commercially available and highly successful for many years. Before tightening the clamp by plastic deformation of the “Oetiker” ear, the overlapping band portions must be mechanically connected, for example, by spot-welding or preferably by one or more hook-shaped members in the inner of the overlapping band portions engaging in one or more apertures in the outer overlapping band portion. One or more so-called guide hooks, sometimes also called suspension hooks, which are bent out of the clamping band about a transverse axis after a substantially U-shaped cut in the longitudinal direction of the clamping band, have been used for many years for that purpose.
FIGS. 1 through 3
illustrate a so-called open clamp with such a guide hook
21
extending obliquely outwardly from the inner band portion
11
b
and engaging in one of several apertures
22
in the overlapping outer clamping band portion
11
a,
as disclosed in U.S. Pat. No. 3,321,811. Though the present invention is theoretically applicable to any tightening device which requires a mechanical connection before tightening can be commenced, it is of particular significance and advantage when used with open clamps that are tightened by plastic deformation of a so-called “Oetiker” ear generally designated in
FIG. 1
by reference numeral
13
and consisting of generally outwardly extending parallel leg portions
14
and
15
interconnected by a bridging portion
16
, normally provided with a reinforcing groove or pan-shaped depression (not shown) as described, for example, in U.S. Pat. No. 5,282,205. The problem encountered with the prior art mechanical connections using only one such guide hook
21
was the likelihood of reopening of the mechanical connection in the course of the application of tightening forces which cause the hook
21
to bend back into a clamp re-opening position
21
′ (FIG.
3
). To reduce the likelihood of reopening of the clamp owing to a bent-back guide hook, a combination of a guide hook
31
and deep-drawn support hook(s)
32
was proposed for such clamps in U.S. Pat. No. 4,299,012, whereby upon application of tightening forces by plastic deformation of the ear
13
, the outer band portion
11
a,
guided along the inclined surface of the guide hook
31
, would be drawn toward the inner band portion
11
b
to assure engagement of support hooks
32
in their apertures
35
(FIG.
4
). In turn, this permits improved absorption of the higher tightening forces by the support hooks. This prior art arrangement proved highly successful. Nonetheless, if the speed of the increase of the tightening forces, for example, with the use of pneumatic tools, exceeds a certain value, depending also on clamping band material, thickness of the clamping band and length of the guide hook determining the lever arm, it may happen that the guide hook bends back before the overlapping band portions have come close enough to one another to cause engagement of the support hooks in their respective apertures.
Such open clamps are made from flat steel band material and are usually deformed into more or less circular shape to facilitate installation over the hose and engagement of the guide hook in its aperture before tightening can be commenced by plastic deformation of the “Oetiker” ear. However, such predeformation is likely to cause spring stresses to be set up in the clamping band which seek to return the clamping band to a more straight configuration, i.e., seek to reopen the clamp by disengagement of the outer band portion
11
a
from the guide hook. Thus another pre-existing problem was the likelihood of reopening when the outer band portion
11
a
slides again outwardly over the edge of the free end of the guide hook under the spring forces. This danger is the greater the shorter the guide hook. On the other hand, the longer the guide hook, the greater the lever arm seeking to bend the hook into the guide-hook reopening position. To counteract these contradictory effects, it has been proposed heretofore to bend the free end of the guide hook as shown at
21
a
in FIG.
5
. This improves the problem but does not completely eliminate the same.
SUMMARY OF THE INVENTION
The present invention proposes to obviate the aforementioned problems of the prior art by providing in the guide hook an abutment surface which effectively prevents reopening of the mechanical connection by stopping the outer band portion provided with the hook-engaging aperture from sliding out over the free edge of the guide hook and which at the same time assures with greater certainty the early and timely absorption of the tightening forces by the support hook(s). The abutment surface may thereby be formed in any known manner, for example, by cold-deformation and deep-drawing or by bending, whereby the abutment surface extends at least approximately parallel to the longitudinal direction of the outer clamping band, preferably substantially coplanar with the longitudinal direction of the outer clamping band portion. In a preferred embodiment, the abutment surface is formed directly in the guide hook by a double-bending of the hook so that a section of predetermined length extends at least approximately parallel to the longitudinal direction of the outer clamping band in its preassembled condition, i.e., with the guide hook engaging its aperture before tightening.
The abutment surface facing the outer band portion in accordance with this invention is thereby preferably located at such a radial distance from the outer surface of the inner band portion that at the beginning of the tightening of the clamp, the support hooks are able to engage immediately into force-absorbing engagement in their apertures or already are in such a position. This can be realized by making this radial distance between the abutment surface and the outer surface of the inner band portion at least slightly larger than the thickness of the clamping band but smaller than the height of the support hook. As the outer band portion is slipped over the guide hook in the inward direction during preassembly, it will reach a position where the edge of the aperture for the guide hook, which is nearer the free end of the outer band portion, can slide under the abutment surface, thereby establishing the desired pre-assembly.
This preassembly must not be confused with the prior art preassembly in so-called earless clamps as exemplified by U.S. Pat. No. 4,492,004 (
FIG. 6
) and U.S. Pat. No. 5,274,886 (
FIG. 7
) which involve completely different structures, functions and purposes from those of the present invention. Whereas in the open clamps with “Oetiker” ears as tightening means, a mechanical connection between overlapping band portions must be established before tightening of the clamp can be started by plastic deformation of the ear, in these so-called earless clamps, no mechanical connection is required nor possible until the clamp has been fully tightened to the point where it has reached the predetermined final clamping force, at which time only the hooks in the inner band portion can engage in the correspondingly located apertures in the outer band portions. Stated differently, in the open clamps to which the invention applies, the initial diameter of the clamp is determined by the circumferential length of the clamping band from the mechanical connection by way of the ear circumferentially again to the mechanical connection thereby including the length of the gap under the ear. Tightening is achieved by reducing th
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