Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1997-03-25
2002-06-11
Vo, Peter (Department: 3729)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S888300, C029S527400, C264S320000, C425SDIG004, C277S353000, C277S549000, C277S562000, C277S572000, C277S575000
Reexamination Certificate
active
06401322
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a sealing apparatus having a composite material consisting of a sealing lip formed of a resin material and a sealing portion formed of a rubber-like elastic material, and a method of manufacturing thereof.
A conventional sealing apparatus is manufactured by accumulating a number of parts, as shown in
FIGS. 23
,
24
, followed by caulking.
The sealing apparatus
100
shown in
FIG. 23
is assembled by continuously baking a rubber lip
102
and a peripheral gasket
103
direct to a peripheral side metal ring
101
followed by vulcanization forming, inserting a resin formed sealing member
104
and an assembly reinforcing metal ring
105
, and mechanically caulking the end portion
101
a
on the sealed fluid side O of the peripheral side metal ring
101
, opposite to the atmospheric side A. A sealing apparatus
200
is assembled, as shown in
FIG. 24
, by installing a sealing ring
202
onto the outside of a peripheral side metal ring
201
, inserting a rubber lip
203
, a resin sealing member
204
, a flat washer-shaped metal ring
205
, and a dust lip
206
to the inside thereof, and mechanically caulking the end portion
201
a
on the sealed fluid side O of the meal ring
201
, opposite to the atmospheric side A. The sealing apparatus
100
significantly reduced the number of parts items, compared with the sealing apparatus
200
, which has lead to the facilitation and reduction in cost of the manufacture.
However, some problems were encountered in assembling the sealing apparatuses of
FIGS. 23 and 24
, including the generation of powder or metal powder from a surface coat in addition to the complicated and expensive caulking process of the periphery in the aspect of process, and the rusting by breakage of the surface treatment coat, the reduction in sealing function by the adhesion of the above powder to a product, and the like in the aspect of quality of product. Further, the exposed peripheral metal surface often damaged the associated housing, affecting the sealing property.
Further another conventional sealing apparatus is shown in FIG.
25
. This sealing apparatus
300
shown in
FIG. 25
, which seals the clearance between concentrically relatively moving housing
310
and shaft
311
separately to the atmospheric side O and the sealed side M, mainly comprises an L-shaped sectional metallic reinforcing ring
301
for holding the form of the sealing apparatus
300
, a first sealing member
302
formed of a rubber-like elastic body which is vulcanization formed on the reinforcing ring
301
, and a second sealing member
303
formed of a resin material which is fixed so as to be nipped by the reinforcing ring
301
and the first sealing member
302
.
The reinforcing ring
301
has a fitting portion
301
a
for fixing the sealing apparatus
300
onto the inside surface of the housing
310
and a flange portion
301
b
extending radially inward from the fitting portion
301
a
, and the fitting portion
301
a has a peripheral sealing portion
302
a
formed integrally with the first sealing member
302
on its outside surface.
The sealing portion of this sealing apparatus
300
is formed on two members compositely constituted, enabling the use under a severe condition where it is difficult to satisfy high sealing performance over a long period only with a lip formed of a general rubber-like elastic Body.
Namely, the sealing portion is provided with a first sealing lip
302
b
of the first sealing member
302
and a second sealing lip
303
a
of the second sealing member
303
, and a different characteristics are imparted to the respective lips to make the sealing portion more functional.
In this conventional apparatus, a material having high wear resistance or heat insulating characteristic by PTFE (ethylene tetrafluoride), for example, is adapted as the resin material for the second sealing lip
303
a
, so that the second sealing lip
303
a
has a holding function for minimizing the wear or deformation even when energized to the sliding surface of a shaft
311
by a high pressure on the sealed side M in the operation of the sealing apparatus
300
(mainly the rotation of the shaft
311
), and preventing the reversion or movement of the first sealing lip
302
b
, whereby the sealing performance can be held over a long period.
A thread groove
303
b
for generating a pumping effect is formed on the surface opposed to the sliding surface of the shaft
311
of the second sealing lip
303
a
, and it is worked so as to return to the sealed side M the sealed fluid which is apt to flow out from the sliding surface of the shaft
311
onto the atmospheric side A during the rotation of the shaft
311
, thereby holding high sealing performance.
On the other hand, for the first sealing lip
302
b
of a rubber-like elastic body, the sealing of the sealed fluid in the stoppage of the shaft
311
is rather an important function in this prior art, although the sealing property by itself is necessary in the rotation of the shaft
311
.
Thus, such a conventional apparatus is constituted so that the characteristics of two different materials can be brought out and skillfully utilized to attain high sealing property.
FIGS. 26
a
and
26
b
are views illustrating a method of manufacturing the sealing apparatus
300
shown in FIG.
25
. For the detailed description, refer to Japanese Patent Application No. 2-27386 by the present applicant.
In
FIG. 26
a
, a mold
400
mainly comprises a lower mold
401
and an upper mold
410
. The lower mold
401
is divided into a first mold
402
defining the bottom surface, a second mold
403
defining the radially outer wall surface, and a core
404
defining the radially inner wall surface. The outside surface of he core
404
has a male screw portion
404
a
cut therein.
On the other hand, the lower surface of the upper mold
410
has an annular projecting portion
411
to be inserted into the lower mold
401
. When the mold is clamped, an annular cavity
420
is formed between the projecting portion
411
and the lower mold
401
.
The vulcanization forming of the sealing apparatus
300
is performed in the following manner.
A reinforcing ring
301
, and a rubber material
302
′ as the second sealing member
303
and the first sealing member
302
are arranged in the lower mold
401
in this order.
As the second sealing member
303
, a resin material such as PTFE is preliminarily formed into an L-shaped section by cutting work. Although it can be also considered that the second sealing member
303
formed of a material having a flat washer shape or funnel-like washer shape, for example, is used instead of the cutting work into the L-shaped section, and formed into the L-shaped section by mold clamping, problems such as the slippage of the forming position, the insufficient pressurization of the thread groove
303
b
caused by the consumption of the pressure for forming it for the formation of the L-shaped section, and the like must be taken into consideration in this case, because the second sealing member
303
is energized to the reinforcing ring
301
and the male screw portion
404
a
of the core
404
through the rubber material
302
′.
The mold is then clamped as shown in
FIG. 26
b
followed by heating and pressurization. The rubber material
302
′ is fluidized within the cavity
420
, carried along the surfaces of the second sealing lip
303
a
of the second sealing member
303
and the reinforcing ring
301
, and spread to the whole area within the cavity
420
.
The second sealing lip
303
a
of the second sealing member
303
softened by heat is then pressed onto the surface of the male screw portion
404
a
by the pressure of the fluidized rubber material
302
′ to form the thread groove
303
b
corresponding to the male screw portion
404
a.
After the completion of the vulcanization forming, the mold is opened to take out a molding, and the excessive portion of the first sealing member
302
is properly cut, thereby completing the sealing apparatus
300
.
In such a c
Jacobson & Holman PLLC
NOK Corporation
Tugbang A. Dexter
Vo Peter
LandOfFree
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