Metal deforming – By relatively movable offset tool-faces – With tool motion in fixed path
Reexamination Certificate
2001-11-16
2004-04-06
Ostrager, Allen (Department: 3725)
Metal deforming
By relatively movable offset tool-faces
With tool motion in fixed path
C073S383000, C073S387000
Reexamination Certificate
active
06715334
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus and a method for manufacturing a thick-walled bent pipe.
BACKGROUND ART
As for a metal elbow for piping, those with an elbow body
111
being attached to a piping block
113
or the like with a fastening nut
112
as shown in
FIG. 11
is used conventionally. Both ends of the elbow body
111
are threaded, and one thread is screwed into the piping block
113
or the like and fastened with the nut
112
, while a pipe not shown is attached to the other thread. The elbow body
111
can be freely oriented to the piping and fixed by being fastened with the nut
112
. The elbow body
111
is provided with parallel plane portions
111
s
and
111
s
so that the elbow body
111
can be fixed with a spanner or the like when it is attached. Further, the elbow body
111
is bent at substantially 90 degrees, which reduces the protruding amount from the piping block
113
or the like, thus requiring less piping space.
In a section of the elbow body
111
, two fluid paths
111
d
and
111
d
cross each other at substantially 90 degrees as shown in FIG.
12
. Further, since the elbow needs to be threaded, a margin to cut needs to be secured, which makes a material for the elbow thick-walled. In addition, it is necessary to secure pressure resistance of an elbow in order to respond to high-pressurization of the fluid devices in recent years, and the wall thickness of the elbow body
111
after being worked becomes larger.
Accordingly, it is difficult to manufacture the elbow body
111
as shown in
FIG. 12
by bending a thick-walled metal pipe at a small radius, because the pipe is crushed or the wall thickness of the pipe is reduced. Consequently, a material of the elbow is made by cutting out a thick metal plate and forming it into a right-angle elbow, then the material is drilled from both sides thereof to make the fluid paths
111
d
and
111
d
crossing each other at substantially 90 degrees, and thereafter screw thread cutting is performed for both ends to thereby manufacture the elbow body
111
.
However, in the above manufacturing method, the process of cutting the material includes two drilling operations and two screw thread cutting operations, which results in too many working steps, and thus the number of steps of preparing the material is large. Further, in the drilling work, burrs caused by the drilling work occur at a crossing portion of the fluid paths
111
d
and
111
d
crossing each other at substantially 90 degrees. Thus, an operation of removing the burrs has to be performed, and the deburring operation is not easy and takes time, since burrs in the inner parts of small holes have to be removed. Further, many cutting operations increase cutting amount of the material, thus reducing yields. Consequently, manufacturing cost is increased.
As a solution to the above disadvantages, an apparatus for manufacturing a thick-walled bent pipe described in Japanese Patent Application Laid-open No. 2000-343136 is proposed. This apparatus includes an upper die
210
having a presser die
212
and an upper guide
211
having a guide surface
211
a
in a circular arc form for guiding a pair of lower dies
221
and
222
, as shown in FIG.
10
. The apparatus also includes a pair of lower dies
221
and
222
having sliding plane
220
c
and
220
c
in a circular arc form, and a lower guide
230
having sliding planes
230
a
and
230
a
for mounting a pair of the lower dies
221
and
222
thereon. In connection with a descent of the upper die
210
, the sliding planes
220
c
and
220
c
in the circular arc form of a pair of lower dies
221
and
222
abut to and slide along the guide surface
211
a
in the circular arc form of the upper guide
211
of the upper die
210
. At the same time as this, lower end portions
220
f
and
220
f
of a pair of the lower dies
221
and
221
abut to and slide along the sliding planes
230
a
and
230
a
of the lower guide
230
. Sliding in this manner makes the structure in which a pair of the blower dies
221
and
222
are respectively rotatable opposite to each other.
According to this apparatus, a pair of the lower dies
221
and
222
rotate along the guide surface
211
a
in the circular arc form of the upper die
210
, having a center of rotation O
1
while they are facing to each other. Thereby, changes in the distances between both the end surfaces of the thick-walled pipe material
111
a
and the center O
1
of rotation at the start of bending and at the completion of bending are reduced, thus making it possible to form a thick-walled elbow material that is a thick-walled bent pipe with less variations in size.
As a result, the thick-walled pipe can be cut and used as an elbow material, thus making it unnecessary to prepare a forged material. Further, since a thick-walled pipe can be used, drilling for making slender holes to form fluid passages is unnecessary. Further, deburring at the crossing portion of the drilled holes, which is conventionally performed, is made unnecessary. Furthermore, since the thick-walled pipe is round in the outer shape, the margin to cut for screw thread cutting is reduced. Accordingly, a special drill is not needed, drilling work and deburring work are not needed, and cutting amount for screw threading work is reduced, whereby the time required for work, and tool cost can be substantially reduced, and the yield of the material can be improved.
However, since the upper guide
211
of this apparatus has the guide surface
211
a
in the circular arc form, the guide surface
211
a
in the circular arc form has to be worked by cutting a block to produce the upper guide
211
, which requires a large amount of work and makes the work complicated, and as a result, work cost becomes high. Since the upper guide
211
is in a block form, it has heavy weight, which is inconvenient in handling. Further, the sliding surfaces
220
c
and
220
c
in the circular arc form of a pair of the lower dies
221
and
222
abut to and slide along the guide surfaces
211
a
in the circular arc form of the upper guide
211
of the upper die
210
, and thus the sliding surfaces
220
c
and
220
c
and the guide surfaces
211
a
in the circular form are worn or seize if they are used for a long period of time.
SUMMARY OF THE INVENTION
The present invention is made in view of the above-described disadvantages, and its object is to provide an apparatus for manufacturing a thick-walled bent pipe with a simple structure at low manufacture cost, which has durability and is capable of manufacturing an elbow material for piping with higher size accuracy with use of a thick-walled pipe material, and a method of manufacturing a thick-walled bent pipe with use of the manufacturing apparatus.
In order to attain the above object, the apparatus for manufacturing a thick-walled bent pipe according to the present invention is an apparatus for manufacturing a thick-walled bent pipe comprising a presser die and a lower die, and has the constitution in which
the lower die comprises a pair of bottom dies having meshing means and
a pair of the bottom dies are allowed to rotate opposite to each other by meshing means, in connection with a descent of the presser die.
According to the above constitution, the apparatus for manufacturing a thick-walled bent pipe has a simple structure, and therefore it has durability at low production cost. In addition, it can manufacture thick-walled elbow materials with high size accuracy.
Further, in the apparatus for manufacturing the thick-walled bent pipe,
a pair of the bottom dies may be provided with stoppers abutting to both end surfaces in a longitudinal direction of a material to be formed.
According to the above constitution, bending work is performed with the thick-walled pipe material being restrained so as to have a set length by the presser die, the lower die and the stoppers of the lower die, thus making it possible to form a thick-walled elbow material of an accurate size.
The apparatus for manufacturing the thick-walled bent pipe may further compris
Fukushima Hiroyasu
Kimura Yoichi
Armstrong, Kratz, Quintos Hanson & Brooks, LLP.
Goetz John S
Ostrager Allen
Tokiwa Seiki Co., Ltd.
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