Note: Descriptions are shown in the official language in which they were submitted.
'~he present invention l~el7ltes to a safety pipe.
It is ~referabLe but not limlted that the present
invcntion is appLic~ble to ;~ saf`ety pipe coup-
ling in a h~1draulic pi~ing sy~tem. More speci-
fically, the present invention relates to a
safety pipe coupling wi-th a sealing ring for
use in pipe connections, which sealing ring has
an outer 73nd an inner forwardly converging conical
frontpart and two or more cutting edges at the
inner ~urface having differerlt diameters when the
connection is complete-~, which sealing ring is
inserted between a connecting piece, which has
an inner conical surface, and a pressure member
being made as a screw C71~. On tightening the
pressure member or nut ~xially along the stationa-
ry end of' the pipe the sealing ring will be moved
in forward direction 73nd therewith ~orced to cllt
into the wall of the pipe by its cutting edges
and pushing up material of the wall.
A known sealing ring of this kind is provided
with two OI` more cutting e(1ges in succession
having dif'ferent diameters. 'rhe rearwardly inner
surface following t~le cutting edge, which is in
relation to the moving direction rearwardly po-
sitioned, is provided with a conical inner surface
adjoining a cylindrical inner surface of the rear-
wardly part Or the se7lLing ring, which lies plasti-
cally 73gainst the outer surface of the pipe when
the connection is completed~ whereby no exact
stop can be ~`elt by the assembler. It is conse-
quently extremel~y dit`l`icuLt l`or the assembler to
tighten the connection correctly and a dangerous
~?9~
strip of the screw conn~ction may occur.
It is an object of the ~recient invention to
overcome these deficiencies and to provide a
safety pipe coupling with a sealing rin~ main-
taining the necessar,y strength factors and showing
a progressive increase of` the cutting resistance
when the connec-tion is corrlpleted and furthermore
damping any oscillations so that a break or crack
in the area Or the sealing connection by mechani-
cal oscillations will be prevented.
~he present invention therel'ore provides a safety
pipe coupling - as above - which is characterized
by a sealing ring - when the connection is com-
pleted - havirlg a limiting edge at the area
behind the conical converging front~art and
in rnoving direction behind the,cutting edges
at the inner surfac~f?, which limiting edge
having ~ frontsurf'-lce bein~ in vertical direction
to the surface of the p; pl? and the limiting
edge is foll~wed by a cyLindrical inner sur-
f'ace.
According to the invention the limiting edge be
comes effective during the last stage of assemb-
iing. When the cylindrical inner surface is
connected to a convex curved surface which changes
its diameter so that it increases as illu.strated
in the embodiment, it,- makes sure that the convex
curvt?~ surl'ace wi~h its irlcreasinK diameter of
the scaling ring is dlrn~)irlg~ the ~ipe surface
50ftly but str~ongly, S(J t,~l:lt, - in case of nhe
i24
occurence ol mechAnica~ oscillations - a suffi-
ci~n~ dlllnr)irip; o~ oscillatiorls is achieved to
prevent a break or crack in tin area of the
sealing connection.
The diameter Or the l~ing of the second cutting
edge of the se~linr, rill~ is adv~ntageously larger
than the corresponding diameter Or the first cut-
ting edge. A progress,ive incre~se of the cutting
resistance is effected by this feature followed
by the operation ot` the limiting edge which results
a steep increase of the cutting resistance. m e
thickness of the sealing ring immediately behind
the frontsurface of the lirniting edge is advantage-
ously correspondent to the h~lf of the difference
of the diameter betwe~n the largest diameter of
the cone of the connecting piece and the outer
diameter of the pipe. A maximum effectiveness
of the limiting edge is achieved by this rule of
proportioning. The inner diameter of the pressure
member - being lormed as a screw cap - in the
non-~hreaded area of the pressure head being
larger than the outer diameter of the pipe surface,
whereby the non-t;hreade(l plrt of the pressure head
has a cylindrical or a f`unnel-shaped countersinking.
By this featurè according to the invention an in-
clination of the pipe is possible - when the con-
nection is completed - so l;o Ichicve A superior
damping of oscillationci.
'rhe invention will be more readily understood from
the following descrir)tiorl of An embodiment thereof
given b~ w~y of evl~Mple with r(?ferenc~? to the
> _
accom~anyirlg dr,~willl,s, irl ~!hi.Ch:
~`ig. 1 shows a view takerl in longitudin.ll section
through an ~Ipprr half Or the pipe connection
with senlin~ rin~ ,~ccordin~ ~o the invention
in its initial con~ition,
Fig. 2 shows a view t,~ken i.n longitudinal cection
through the em~odirrlerlt ol` Fi.~r. 1 when the
connection is comE,Ieted.
As shown in the drawing, the connecting piece 1
has an inner conical surface 2 to take up the sealing
ring ~, which is E)ushed on the pi~e 4. The pipe end
which is to be connected fits against an abutment 5
in the connecting piece ~.
~len the connection i5 assfmbled, the pressure
member ~- being ma(le ~s n srrew C~p i.S tightened
thereb~ abuting its front conical surface 13 against
the c~nical bevel 1,~ of the sea].ing ring 3, which
bevel hAs a conical angl.e ol 90, and pushing the
sealirlg ring 3 in ~3 ~ial d i I`eCtiOn Or the pipe 4 to
the l~ll si(3e :in tnl (Ir~w~
q'he s~aling ring ') i.s provided wi.th two ~ifferent
and successively arrclnged lirst and secorld cutting
edges 7 ~nd 8 ~nd in i~s ini~ l condition, shown
in ~iK. 1, the first CUt~illg e(lge 7 being at the
front side of the seelillg ri.ng is provided with
a sru,lller inside diemetel th~n the followin~
second clltting edge ~3, So l.hat the CUttillg edge 7
is cuttin~ into the surl ace of the pip~ initially.
'l`i1ere is a def`inite rel.atioll ~e~weerl tile depth of
1~22{i24
cutting and the A:istance ~etween the two cutting
edges.
The cutting edge ~ is followed by the limiting
edge 11 with its front si~e vertically directed
to the surface of the pipe 4. The sealing ring 3
is provided from the limi~ing edge with a surface
Or cylin~rical shape ch~nging into a convex curved
surface 10 at the en(l of` the sealing ring with
increasing di~meter reprecenting a trumpet like
exit 13.
As illustrateA in Fig. 2, the sealing ring 3 may
be slightly ~eflected bec~us~ of the compression
force of the pressure member anA form a small
space 19, and the convex curved surface 10 does
not disturb the tight contact of the sealing
ring ~ against the pipe 4.
Due to the axial movement of the sealing ring 3
and the decrease of the Aiameter of the outer
conical surface 2 theref`rom resulting, the cutting
edge 7 is penetrating into the surface of the
pipe 4 displacing some of the ~aterial 15 of the
pipe.
The cutting edge '~ is f`ollowed by the cutting
eAge ~ within a Ae~`inite proportion.
At his stage of assembling the limiting edge 11
causes a blocking effect between the conical inner
surface of the connecting plece 1 and pipe 4, so
.... . .
that no lurther axial movement of the sealing
~ing 3 can ~c achi(ve(1. At ~his con(7ition the
limiting edge 11 is in the are.l of the largcst
diameter 16 of the conical surface 2 causing a
strong pressure on the pipe. In other words,
the thickness of the sealing ring 3 immediately
behind the limiting edge 11 is the half of the
difference between the largest diameter and the
outer diameter Or the pipe 4.
The limiting edge 11 is efrecting a resistance
clearly observable to the assembler at the last
stage of asse~bling, so that further tightening
of the screw cap 6 is only possible by using
ver~ strong power. ~le assembler therefor re-
ceives an outstanding indication when the con-
nection is completed. The geometrical shaping
of the limiting edge 11 makes it reliable that
the convex curved surface and the trumpet-like
exit at the end 1~ of the sealing ring 3 remains
unchanged. ~herefore the pipe 4 is damped sleeve-
like softly and strongly under the action of
pressure on the 90 conical bevel 12 as well as
of the sealing ring 3 and the screw cap 6.
The non-threaded area 20 positioned at rear
portion of the pressure member 20 has a funnel-
shape (solid linc) or cylindrical (broken line)
countersinking which has a larger diameter of that
of the pipe 4 as illustrated in Figs. 1 and 2.
The pipe surface 4 can be inclined as shown by
the angle 1r~ in Fig. 2. ~y this reason mechanical
_ 9 _
~l;2ZG2~
oscillatic)ns can be (~amped in this way and a
brenk of` the eonrlection is avoided in the area
o~^ the sealing ring.
1~
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