Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Tensioned along the longitudinal axis by a coaxial force...
Reexamination Certificate
2002-01-28
2003-01-14
Wilson, Neill (Department: 3679)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Tensioned along the longitudinal axis by a coaxial force...
C411S383000, C411S396000, C411S552000, C411S916000
Reexamination Certificate
active
06506007
ABSTRACT:
BACKGROUND ART
Combination of bolt and nut is widely used as a fundamental fastening elements. The bolt has a head portion formed as a larger outer diameter portion at one end of the shaft, and an outer thread formed on the circumference of the shaft for engaging with inner thread of the nut. The objects are fastened between the head portion and the nut, and the fastening force between them is adjusted by tightening the nut, and the fastening length is adjusted by using washer or spacer.
In a smelting reduction plant and the like, it is preferable to make a bottom portion of a reduction furnace separable, because interior of the bottom portion is covered with a firebrick lining which needs periodical repair. This separable construction of the furnace makes the plant more cost effective than to install two furnaces so that one furnace can be repaired while the other furnace is in operation. The smelting furnace in the commercial plant has a large volume, and a large number of fastening bolts are needed for connecting the bottom portion to the furnace body with flanges. Air tightness is required at the flange connecting portion because the smelting reduction furnace is operated under high internal pressure of several kgf/cm2 G, and quick replacement of the bottom portion is also required to prevent drop of plant operating efficiency. When conventional bolts and nuts are used for fastening flanges, a large number of bolts and nuts should be fastened uniformly to keep air tightness, and unfastened for releasing flanges.
FIG. 11
shows a prior art of a bolt disclosed in Japanese Utility Model Laid-Open No. Sho 63-157407, which is fastened utilizing hydraulic pressure. A guide base
1
a
is secured on a rest bar
3
by fastening a clamp
2
, and by unfastening the clamp
2
the rest bar
3
is slidable along the rest bar
3
in the direction perpendicular to the surface of the drawing. A fastening shaft
4
for creating fastening force is inserted into a piston
5
combined with a cylinder
8
. When the hydraulic pressure is applied to create a hydraulic space
6
at the abutted portion of piston
5
and cylinder
8
, a lock nut
7
attached on the end of the shaft
4
is pushed apart by the piston
5
in the axial direction of the shaft
4
. A reaction force of the piston
5
against the lock nut
7
is applied on the clamp
2
by the cylinder
8
.
Upper half of
FIG. 11
shows the condition when no hydraulic pressure is applied. In this condition, the end surface of the cylinder
8
is fastened by a fastening nut
9
attached on the circumference of the piston
5
. When the hydraulic pressure is applied to create hydraulic pressurizing space
6
between the abutted portions of the piston
5
and the cylinder
8
, as shown in lower half of the
FIG. 11
, the piston
5
is moved in the direction away from the head portion of the fastening shaft
4
, and a gap G is formed between end surfaces of the cylinder
8
and the fastening nut
9
. Under such condition, the lock nut
7
is pushed by the piston
5
away from the head portion
4
to extend the shaft
4
in axial direction. When the gap G is formed, the fastening nut
9
is rotated to come into contact again with the end surface of the cylinder
8
. Relative movement between the piston
5
and the cylinder
8
is then restricted by the fastening nut
9
, and the position of the lock nut
7
shown in the lower half of the
FIG. 11
can be maintained after the hydraulic pressure is released. A convex nut
12
and a concave nut
13
are disposed between the clamp
2
and the cylinder
8
, and a spacer
14
is disposed between the end surfaces of the piston
5
and the lock nut
7
.
By using a bolt shown in
FIG. 11
, a large number of bolts can be securely fastened utilizing hydraulic pressure. Another prior arts of such bolts utilizing hydraulic pressure for fastening are disclosed in Japanese Laid-Open Patent Publication No. Hei 2-262971 and Japanese Laid-Open Patent Publication No. Hei 5-79302. The former includes means for creating fastening force in a turn buckle by extending the bolt with hydraulic pressure, and means for locking the fastened condition after the hydraulic pressure is released. The latter includes tension nuts connected at both ends of the bolt, and one tension nut is pulled up by a hydraulic cylinder to create prescribed fastening force, and the pulled up condition is retained by fastening a nut.
By applying bolt designs disclosed in Japanese Laid-Open Utility Model No. Sho 63-157407, Japanese Laid-Open Patent No. Hei 2-262971 or Japanese Laid-Open Patent Publication No. Hei 5-79302 for fastening objects such as flanges, a large number of bolts can be fastened simultaneously utilizing hydraulic pressure, but it is difficult to unfasten the objects by loosening the bolts. In the prior art of Japanese Laid-Open Utility Model No. Sho 63-157407 shown in
FIG. 11
, the gap G is formed again between the fastening nut
9
and the cylinder
8
by the application of additional hydraulic pressure in the hydraulic space
6
, and the fastening nut
9
can be loosened by hand. However, the lock nut
7
is pushed strongly against the end of the piston
5
, and a considerable amount of torque will be needed to loosen the lock nut
7
from the fastening shaft
4
. The clamp
2
cannot be removed from the guide base
1
a
and the rest bar
3
without removing the lock nut
7
from the fastening shaft
4
. When the fastening shaft
4
together with the combination of piston
5
and cylinder
8
as shown in
FIG. 11
is applied for fastening flanges, the flanges cannot be separated without removing the lock nut
7
from the fastening shaft
4
.
Fastening and unfastening operation of the bolt can be automatically done by rotating the nut with a hydraulic motor or other means. However, this method has following disadvantages:
(1) The equipment becomes expensive;
(2) Complicated and expensive hydraulic apparatus is needed;
(3) Large installation space is needed when the hydraulic apparatus is relatively large, and the installation becomes difficult due to the interference of the apparatus when the flange has a large diameter and needs a large number of bolt for fastening.
Manual fastening and unfastening operation of ordinary bolt and nut has following disadvantages:
(1) Manual operation becomes difficult when the bolt has a large diameter;
(2) Insertion and withdrawal of the bolt is difficult due to its heavy weight;
(3) Even when the clamp is manually operable, long time is needed to perform the entire operation of fastening or unfastening a large number of bolts, lowering plant operation efficiency;
(4) Fastening force of the bolt is required to be adjusted precisely for respective fastening operation by a torque wrench or other means.
The object of the present invention is to provide a fastening bolt with a simple structure with easy fastening and unfastening operation, and with no adjustment of the fastening force is required in respective fastening operation.
DISCLOSURE OF INVENTION
The fastening bolt of the present invention is for fastening an object between a head portion formed on one end of the shaft and a nut attached on the threaded portion formed around the shaft, characterized in that the fastening bolt includes a hydraulic pressure application means for applying a hydraulic pressure to extend the shaft between the head portion and the threaded portion of the bolt when the object is fastened between the head portion and the nut, and for releasing the fastened condition of the object, and the head portion is formed in a hammer shape by a removably attached cotter which extends in the direction perpendicular to the axis of the shaft.
According to the present invention of the above structure, the shaft of the fastening bolt can be extended between the head portion and the nut where the object is fastened by the application of hydraulic pressure, and when the shaft is extended, the nut can easily be loosened for releasing the fastened condition. By tightening the nut when the shaft is extended, large fastening force is
Kishimoto Mitsuharu
Koza Yukihiko
Nomoto Hiroki
Yajima Kenichi
Kawasaki Jukogyo Kabushiki Kaisha
Marshall Gerstein & Borun
Wilson Neill
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