U.S. patent application number 11/789717 was filed with the patent office on 2008-01-24 for molding method and molding apparatus.
This patent application is currently assigned to Kabushiki Kaisha Yutaka Giken. Invention is credited to Kazunori Koide, Katsumi Okamoto.
Application Number | 20080016933 11/789717 |
Document ID | / |
Family ID | 38840899 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080016933 |
Kind Code |
A1 |
Okamoto; Katsumi ; et
al. |
January 24, 2008 |
Molding method and molding apparatus
Abstract
The present invention relates to a molding method of reducing a
diameter in an end portion of a metal tube to be characterized in
having a step of rotating a metal tube around an axial core or
rotating a frame in which a plurality of ring-shaped tools are
arranged, and moving the axial core of the ring-shaped tool away
from the axial core of the metal tube while moving the metal tube
or the frame, thereby reducing the diameter in an end portion of
the metal tube.
Inventors: |
Okamoto; Katsumi;
(Hamamatsu-shi, JP) ; Koide; Kazunori;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
TOWNSEND & BANTA;c/o PORTFOLIO IP
PO BOX 52050
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Kabushiki Kaisha Yutaka
Giken
Hamamatsu-shi
JP
|
Family ID: |
38840899 |
Appl. No.: |
11/789717 |
Filed: |
April 25, 2007 |
Current U.S.
Class: |
72/252.5 ;
72/367.1 |
Current CPC
Class: |
B21D 41/04 20130101 |
Class at
Publication: |
072/252.5 ;
072/367.1 |
International
Class: |
B21B 39/20 20060101
B21B039/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2006 |
JP |
JP 2006-138793 |
Claims
1. A molding method of reducing a diameter in an end portion of a
metal tube comprising the following steps: a step of arranging a
plurality of ring-shaped tools arranged with an axial core which is
in parallel to an axial core of the metal tube having the end
portion to be reduced in the diameter and having an inner periphery
brought into contact with an outer periphery of said metal tube, in
a radial direction of a frame having an axial core which is in
parallel to the axial core of the metal tube; a step of arranging
said plurality of ring-shaped tools in such a manner that an axial
core of each of the ring-shaped tools is in parallel to the axial
core of the metal tube and an inner periphery is brought into
contact with the outer periphery of said metal tube or is not
brought into contact therewith, and a step of arranging so as to
pinch the metal tube; and a step of rotating said metal tube around
the axial core or rotating the frame in which a plurality of
ring-shaped tools are arranged, and moving the axial core of the
ring-shaped tool away from the axial core of the metal tube while
moving the metal tube or the frame, thereby reducing the diameter
in the end portion of the metal tube.
2. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 1, wherein the method reduces the
diameter in the end portion of said metal tube in a tapered shape
having an axial core coinciding with the axial core of the metal
tube, by previously bringing the axial core of said metal tube into
line with the axial core of the frame.
3. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 1, wherein the method reduces the
diameter in the end portion of said metal tube in a tapered shape
having an axial core which is eccentric from the axial core of the
metal tube, by previously make the axial core of said metal tube
eccentric from the axial core of the frame.
4. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 1, wherein the method reduces the
diameter in the end portion of the metal tube in a tapered shape
having an axial core which is eccentric with respect to the axial
core of the metal tube, by rotating said metal tube around the
axial core or rotating the frame in which a plurality of
ring-shaped tools are arranged, moving the metal tube or the frame
in a direction in which the ring-shaped tools reach the end portion
of the metal tube, and moving the axial core of the ring-shaped
tools away from the axial core of the metal tube while moving the
axial core of the metal tube away from the axial core of the frame
in parallel.
5. A molding method of reducing a diameter in an end portion of a
metal tube while inclining at least a partial axial core of the end
portion to be reduced in the diameter with respect to an axial core
of the metal tube, at a time of reducing the diameter in the end
portion of the metal tube, comprising the following steps: a step
of arranging a plurality of ring-shaped tools rotating in a state
in which an inner periphery is brought into contact with an outer
periphery of the metal tube, in a radial direction of a frame and
structuring an axial core of said frame and the axial core of the
metal tube in such a manner as to be relatively changeable; a step
of setting the axial core of said frame to a previously set angle
with respect to the axial core of the metal tube and arranging said
plurality of ring-shaped tools in such a manner that the inner
periphery of each of the ring-shaped tools is brought into contact
with the outer periphery of the metal tube or is not brought into
contact therewith, a step of arranging so as to pinch the metal
tube in said plurality of ring-shaped tools, thereafter rotating
said metal tube around the axial core or rotating the frame in
which a plurality of ring-shaped tools are arranged, and moving the
metal tube or the frame, and moving the axial core of the
ring-shaped tool away from the axial core of the metal tube while
relatively changing the axial core of the frame and the axial core
of the metal tube or without changing, in the process of moving
said metal tube or the frame, thereby reducing the diameter in the
end portion of the metal tube.
6. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 5, wherein the method reduces the
diameter in the end portion of said metal tube in a tapered shape
having an axial core inclined with respect to the axial core of the
metal tube, by previously bringing the axial core of said metal
tube into line with the axial core of the frame, and relatively
moving the axial core of the frame and the axial core of the metal
tube in parallel in the process of moving the metal tube or the
frame as well as rotating said metal tube around the axial core or
rotating the frame in which a plurality of ring-shaped tools are
arranged.
7. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 5, wherein the method reduces the
diameter in the end portion of said metal tube in a tapered shape
having an axial core inclined with respect to the axial core of the
metal tube by previously inclining the axial core of the metal tube
and the axial core of the frame relatively, and maintaining the
incline between the axial core of the metal tube and the axial core
of the frame in the process of moving the metal tube or the frame
as well as rotating said metal tube around the axial core or
rotating the frame in which a plurality of ring-shaped tools are
arranged.
8. A molding method of reducing a diameter in an end portion of a
metal tube according to claim 5, wherein the method reduces the
diameter in the end portion of said metal tube in a tapered shape
having an axial core inclined with respect to the axial core of the
metal tube, by setting the axial core of the metal tube and the
axial core of the frame to a previously set angle, and relatively
changing the angle between the axial core of the metal tube and the
axial core of the frame together with the movement of said metal
tube or the frame, in the process of moving the metal tube or the
frame as well as rotating said metal tube around the axial core or
rotating the frame in which a plurality of ring-shaped tools are
arranged.
9. A molding apparatus for reducing a diameter in an end portion of
a metal tube, comprising: a plurality of ring-shaped tools rotating
in a state in which an inner periphery is brought into contact with
an outer periphery of the metal tube; a frame arranging and holding
said plurality of ring-shaped tools in a radial direction; a tool
moving member provided in said frame and moving the individual
ring-shaped tool within a surface which is orthogonal to an axial
core of each of the ring-shaped tools; a drive member rotating said
frame; a grip member arranged so as to face to said frame and
gripping the metal tube to be reduced in diameter in the end
portion; and a supply car mounting said grip member and structured
such as to be movable in a direction of moving said grip member
mounting said grip member close to or away from said frame, and an
orthogonal direction to said direction.
10. A molding apparatus for reducing a diameter in an end portion
of a metal tube according to claim 9, wherein the molding apparatus
further comprises a revolving member provided in said frame or the
grip member arranged so as to face to said frame and relatively
changing the angle formed by the axial cores.
11. A molding apparatus for reducing a diameter in an end portion
of a metal tube according to claim 9, wherein a plurality of
ring-shaped tools held by said frame are arranged at a uniform
angle around the axial core of said frame.
12. A molding apparatus for reducing a diameter in an end portion
of a metal tube according to claim 11, wherein a plurality of
ring-shaped tools held by said frame are arranged at positions
facing at 180 degree.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and an apparatus
for reducing a diameter in an end portion of a metal tube, and more
particularly to a molding method of reducing a diameter in a
tapered shape while holding an axial core coinciding with an axial
core of a metal tube, or reducing a diameter in the tapered shape
while holding the axial core which is eccentric with respect to the
axial core of the metal tube, and further reducing a diameter in
the tapered shape by inclining the axial core of the reduced
diameter portion with respect to the axial core of the metal tube,
and a molding apparatus which can achieve the molding method.
[0003] 2. Description of the Related Art
[0004] It has been executed to reduce a diameter in an end portion
of a cylindrical metal tube so as to mold in a tapered shape by
employing a rotational molding method. As the rotational molding
method, there are a spinning molding method, an eccentric
rotational molding method and the like, as described in Pipe
Working Method, Second Edition (Publishing Office: Nikkan Kogyo
Shinbun: Sep. 30, 1998).
[0005] The spinning molding method is structured such as to reduce
a diameter in an end portion of a metal tube by employing a roller
which is brought into contact with an outer peripheral surface of
the metal tube to be reduced in the diameter, bringing the roller
into pressure contact with the outer peripheral surface of the
metal tube, and moving the roller close to an axial core of the
metal tube as well as relatively moving the metal tube and the
roller along the axial core of the metal tube while rotating the
metal tube or rotating the roller around the axial core of the
metal tube serving as a center of rotation.
[0006] In this spinning molding method, it is necessary to make a
molding load in an axial direction small in order to prevent a
buckling of the metal tube from being generated. Accordingly, it is
preferable to be employed at a time of reducing a diameter in a
thin metal tube, however, since a working rate at one time is
small, it is necessary to repeat a working step of moving the
roller from a start point of the diameter reduction to an end point
at several times, so that there is a problem that a limit is
generated in shortening of a working time.
[0007] The eccentric rotational molding method is structured such
as to reduce a diameter in an end portion of a metal tube by
employing a rotatable conical tool, arranging an axial core of the
conical tool in parallel to an axial core of the metal tube so as
to bring a conical surface of the conical tool into pressure
contact with the end portion of the metal tube, and moving the
conical tool in a direction in which the axial core of the conical
tool moves close to the axial core of the metal tube along the
axial core or in a direction in which the axial core of the conical
tool moves away from the axial core of the metal tube in parallel,
while rotating the metal tube.
[0008] In this eccentric rotational molding method, there is
obtained an advantage that it is possible to enlarge a molding load
with respect to the axial direction, it is possible to basically
mold by one work, and a molding speed becomes high.
[0009] As an apparatus for molding the diameter reduction in the
tube while bringing out the advantage mentioned above, there has
been proposed a technique described in Japanese Patent No. 2548799.
In this technique, the tube is molded so as to reduce the diameter
from the end portion by making a center of rotation of a metal mold
having a conical hole and being rotatable eccentric from a center
axis of the tube, moving the end portion of the tube in a direction
of the metal mold along the center axis while bringing the end
portion of the tube into pressure contact with the conical hole and
rotating the tube. In the technique of Japanese Patent No. 2548799,
it is possible to mold so as to reduce the diameter not only in the
end portion of the tube but also over an optional length.
SUMMARY OF THE INVENTION
[0010] As mentioned above, in the case of employing the spinning
molding method at a time of reducing the diameter in the end
portion of the metal tube, there is a problem that the molding
speed becomes slow, and the limit is generated in the shortening of
the working time.
[0011] Further, the technique described in Japanese Patent No.
2548799 is advantageously employed at a time of molding so as to
reduce the diameter in the end portion of the tube, however, there
is always a requirement of developing a more rational molding
method. Particularly, in the technique in Japanese Patent No.
2548799, there is a risk of generating a problem that a molding
load applied to the tube becomes large by enlarging an offset
amount between the center of rotation of the metal mold and the
center axis of the tube, and the buckling is generated.
Accordingly, there is demanded to develop a technique in which a
molding speed is fast so as to intend to shorten a working time
without generating a buckling.
[0012] In order to solve the problem mentioned above, in accordance
with a first aspect of the present invention, there is provided a
molding method of reducing a diameter in an end portion of a metal
tube including the steps of arranging a plurality of ring-shaped
tools arranged with an axial core which is in parallel to an axial
core of the metal tube having the end portion to be reduced in the
diameter and having an inner periphery brought into contact with an
outer periphery of the metal tube, in a radial direction of a frame
having an axial core which is in parallel to the axial core of the
metal tube, arranging the plurality of ring-shaped tools in such a
manner that an axial core of each of the ring-shaped tools is in
parallel to the axial core of the metal tube and an inner periphery
is brought into contact with the outer periphery of the metal tube
or is not brought into contact therewith, and arranging so as to
pinch the metal tube, and thereafter rotating the metal tube around
the axial core or rotating the frame in which a plurality of
ring-shaped tools are arranged, and moving the axial core of the
ring-shaped tool away from the axial core of the metal tube while
moving the metal tube or the frame, thereby reducing the diameter
in the end portion of the metal tube.
[0013] In the molding method mentioned above, it is preferable to
reduce the diameter in the end portion of the metal tube in a
tapered shape having an axial core coinciding with the axial core
of the metal tube, by previously bringing the axial core of the
metal tube into line with the axial core of the frame. Further, in
the case of reducing the diameter in the tapered shape having the
axial core which is eccentric from the axial core of the metal
tube, it is preferable to previously make the axial core of the
metal tube eccentric from the axial core of the frame. Further, in
the case of reducing the diameter in the end portion of the metal
tube in the tapered shape having the axial core which is eccentric
with respect to the axial core of the metal tube, it is preferable
to rotate the metal tube around the axial core or rotate the frame
in which a plurality of ring-shaped tools are arranged, move the
metal tube or the frame in a direction in which the ring-shaped
tools reach the end portion of the metal tube, and moving the axial
core of the ring-shaped tools away from the axial core of the metal
tube while moving the axial core of the metal tube away from the
axial core of the frame in parallel.
[0014] Further, in accordance with a second aspect of the present
invention, there is provided a molding method of reducing a
diameter in an end portion of a metal tube while inclining at least
a partial axial core of the end portion to be reduced in the
diameter with respect to an axial core of the metal tube, at a time
of reducing the diameter in the end portion of the metal tube,
including the steps of: arranging a plurality of ring-shaped tools
rotating in a state in which an inner periphery is brought into
contact with an outer periphery of the metal tube, in a radial
direction of a frame and structuring an axial core of the frame and
the axial core of the metal tube in such a manner as to be
relatively changeable, setting the axial core of the frame to a
previously set angle with respect to the axial core of the metal
tube and arranging the plurality of ring-shaped tools in such a
manner that the inner periphery of each of the ring-shaped tools is
brought into contact with the outer periphery of the metal tube or
is not brought into contact therewith, arranging so as to pinch the
metal tube in the plurality of ring-shaped tools, thereafter
rotating the metal tube around the axial core or rotating the frame
in which a plurality of ring-shaped tools are arranged, and moving
the metal tube or the frame, and moving the axial core of the
ring-shaped tool away from the axial core of the metal tube while
relatively changing the axial core of the frame and the axial core
of the metal tube or without changing, in the process of moving the
metal tube or the frame, thereby reducing the diameter in the end
portion of the metal tube.
[0015] In the molding method mentioned above, it is preferable to
reduce the diameter in the end portion of the metal tube in a
tapered shape having an axial core inclined with respect to the
axial core of the metal tube, by previously bringing the axial core
of the metal tube into line with the axial core of the frame, and
relatively moving the axial core of the frame and the axial core of
the metal tube in parallel in the process of moving the metal tube
or the frame as well as rotating the metal tube around the axial
core or rotating the frame in which a plurality of ring-shaped
tools are arranged.
[0016] Further, in the molding method mentioned above, it is
preferable to reduce the diameter in the end portion of the metal
tube in a tapered shape having an axial core inclined with respect
to the axial core of the metal tube by previously inclining the
axial core of the metal tube and the axial core of the frame
relatively, and maintaining the incline between the axial core of
the metal tube and the axial core of the frame in the process of
moving the metal tube or the frame as well as rotating the metal
tube around the axial core or rotating the frame in which a
plurality of ring-shaped tools are arranged.
[0017] Further, in the molding method mentioned above, it is
preferable to reduce the diameter in the end portion of the metal
tube in a tapered shape having an axial core inclined with respect
to the axial core of the metal tube, by setting the axial core of
the metal tube and the axial core of the frame to a previously set
angle, and relatively changing the angle between the axial core of
the metal tube and the axial core of the frame together with the
movement of the metal tube or the frame, in the process of moving
the metal tube or the frame as well as rotating the metal tube
around the axial core or rotating the frame in which a plurality of
ring-shaped tools are arranged.
[0018] Further, in accordance with the present invention, there is
provided a molding apparatus for reducing a diameter in an end
portion of a metal tube, including a plurality of ring-shaped tools
rotating in a state in which an inner periphery is brought into
contact with an outer periphery of the metal tube, a frame
arranging and holding the plurality of ring-shaped tools in a
radial direction, a tool moving member provided in the frame and
moving the individual ring-shaped tool within a surface which is
orthogonal to an axial core of each of the ring-shaped tools, a
drive member rotating the frame, a grip member arranged so as to
face to the frame and gripping the metal tube to be reduced in
diameter in the end portion, and a supply car mounting the grip
member and structured such as to be movable in a direction of
moving the grip member close to or away from the frame, and an
orthogonal direction to the direction.
[0019] In the molding apparatus mentioned above, it is preferable
to have a revolving member provided in the frame or the grip member
arranged so as to face to the frame and relatively changing the
angle formed by the axial cores.
[0020] Further, in the molding apparatus mentioned above, it is
preferable that a plurality of ring-shaped tools held by the frame
are arranged at a uniform angle around the axial core of the frame,
and it is further preferable that they are arranged at positions
facing at 180 degree.
[0021] In accordance with the molding method on the basis of the
first aspect of the present invention, since the structure is made
such as to arrange a plurality of ring-shaped tools in the outer
periphery of the metal tube to be reduced in diameter and make the
axial core of the ring-shaped tool eccentric with respect to the
axial core of the metal tube, it is possible to execute a rational
eccentric rotational molding with respect to the metal tube by the
individual ring-shaped tools. In other words, since the eccentric
rotational molding method can enlarge the molding load in
comparison with the spinning molding method, the eccentric
rotational molding method has a feature capable of making the
molding speed faster. In particular, it is possible to enlarge a
total of the molding loads applied to the metal tube by bringing a
plurality of ring-shaped tools into contact with the metal tube so
as to simultaneously mold. Accordingly, it is possible to improve a
diameter reducing rate. Therefore, it is possible to intend to
shorten a working time. Further, it is possible to lighten the load
applied to the individual ring-shaped tool, and it is possible to
secure a high molding precision.
[0022] Further, it is possible to reduce the diameter in the end
portion of the metal tube in the tapered shape having the axial
core coinciding with the axial core of the metal tube, by attaching
a plurality of ring-shaped tools to the frame, bringing the axial
core of the metal tube into line with the axial core of the frame,
and molding while keeping this state. Further, it is possible to
reduce the diameter in the tapered shape having the axial core
which is eccentric from the axial core of the metal tube, by making
the axial core of the metal tube eccentric from the axial core of
the frame, and molding while keeping this state. Further, it is
possible to reduce the diameter in the end portion of the metal
tube in the tapered shape having the axial core which is eccentric
from the axial core of the metal tube, by moving the axial core of
the ring-shaped tools from the axial core of the metal tube while
moving the axial core of the metal tube away from the axial core of
the frame in parallel.
[0023] Further, in accordance with the molding method on the basis
of the second aspect of the present invention, since the structure
is made such as to arrange a plurality of ring-shaped tools in the
outer periphery of the metal tube to be reduced in diameter and
make the axial core of the ring-shaped tool eccentric with respect
to the axial core of the metal tube, it is possible to execute a
rational eccentric rotational molding with respect to the metal
tube by the individual ring-shaped tools. In other words, since the
eccentric rotational molding method can enlarge the molding load in
comparison with the spinning molding method, the eccentric
rotational molding method has a feature capable of making the
molding speed faster. In particular, it is possible to enlarge a
total of the molding loads applied to the metal tube by bringing a
plurality of ring-shaped tools into contact with the metal tube so
as to simultaneously mold. Accordingly, it is possible to improve a
diameter reducing rate. Therefore, it is possible to intend to
shorten a working time. Further, it is possible to lighten the load
applied to the individual ring-shaped tool, and it is possible to
secure a high molding precision.
[0024] Further, since the structure is made such as to attach a
plurality of ring-shaped tools to the frame and make the axial core
of the frame and the axial core of the metal tube relatively
changeable, it is possible to set the axial core of the frame to a
desired angle with respect to the axial core of the metal tube.
Accordingly, it is possible to reduce the diameter in the end
portion of the metal tube in the tapered shape having the axial
core inclined at the desired angel with respect to the axial core
of the metal tube, by setting the axial core of the frame to the
previously set angle with respect to the axial core of the metal
tube, and molding in this state.
[0025] Further, it is possible to reduce the diameter in the end
portion of the metal tube in the tapered shape having the axial
core inclined with respect to the axial core of the metal tube, by
relatively inclining the axial core of the metal tube and the axial
core of the frame, and maintaining the incline between the axial
core of the metal tube and the axial core of the frame in the
process of moving the metal tube or the frame while rotating the
metal tube or the frame.
[0026] In other words, it is possible to form the reduced diameter
portion which is inclined with respect to the axial core of the
metal tube in the end portion of the metal tube, by changing a
relation between the axial core of the metal tube and the axial
core of the frame to which a plurality of ring-shaped tools are
attached.
[0027] In the molding method in accordance with the present
invention, it is preferable that at least a part of the axial core
of the reduced diameter portion obtained by reducing the diameter
in the end portion of the metal tube is inclined with respect to
the axial core of the metal tube. For example, it is possible to
reduce the diameter in such a manner as to bring the axial core at
a predetermined length in the metal tube side in the reduced
diameter portion into line with the axial core of the metal tube,
and incline the axial core of a continuous position with the
predetermined length portion with respect to the axial core of the
metal tube. Further, it is possible to make the axial core in the
predetermined length portion of the end portion in an open side in
the reduced diameter portion in parallel to the axial core of the
metal tube.
[0028] Further, the molding apparatus in accordance with the
present invention can preferably execute the molding method
mentioned above, and can reduce the diameter in the end portion of
the metal tube in the desired shape.
[0029] Further, in the molding apparatus mentioned above, in the
case of arranging a plurality of ring-shaped tools held to the
frame at the uniform angle around the axial core of the frame,
particularly, at the positions facing at 180 degree, it is possible
to prevent the buckling of the metal tube in accordance with the
molding, and it is possible to achieve the diameter reducing work
having a high molding precision.
[0030] Further, the molding method or the molding apparatus in
accordance with the present invention is advantageously executed at
a time of working an exhaust gas converter of a motor vehicle, and
particularly includes a terminal diameter reducing work of a
position to which the flange is attached for connecting the exhaust
gas converter and an exhaust gas silencer, at a time of working the
exhaust gas converter. There has been known that a dimensional
precision of a diameter in the work mentioned above, largely
affects a weld quality of the weld bonded flange, however, since
the present invention can quickly and precisely work the weld
portion as mentioned above, there can be obtained an effect that it
is possible to reduce a generation of a poor weld in the weld
bonded portion without extending a time required for the diameter
reducing work.
[0031] Further, the molding method or the molding apparatus in
accordance with the present invention is advantageous at a time of
working the exhaust gas converter of the motor vehicle. In other
words, it is possible to smoothly and precisely execute the work of
reducing the diameter in the end portion of the metal tube, by
arranging an assembly obtained by winding a mat around a ceramic
catalyst carrier in an inner portion of the metal tube, prior to
working the end portion of the metal tube so as to reduce the
diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a side elevational view schematically explaining a
structure of a molding apparatus.
[0033] FIG. 2 is a plan view schematically explaining the structure
of the molding apparatus.
[0034] FIG. 3 is a view explaining a structure of a ring-shaped
tool.
[0035] FIGS. 4A and 4B are views explaining a principle of a
molding method in accordance with the present invention.
[0036] FIGS. 5A and 5B are views explaining a shape of a reduced
diameter portion in which a diameter is reduced in accordance with
a first molding method of the present invention.
[0037] FIGS. 6A to 6C are views explaining a shape of a reduced
diameter portion in which a diameter is reduced in accordance with
a second molding method of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] A description will be given below of a preferable embodiment
of a molding apparatus in accordance with the present invention
with reference to the accompanying drawings, and also given of a
molding method. FIG. 1 is a side elevational view schematically
explaining a structure of a molding apparatus. FIG. 2 is a plan
view schematically explaining the structure of the molding
apparatus. FIG. 3 is a view explaining a structure of a ring-shaped
tool. FIGS. 4A and 4B are views explaining a principle of a molding
method in accordance with the present invention. FIGS. 5A and 5B
are views explaining a shape of a reduced diameter portion in the
case that an axial core of a metal tube and an axial core of the
reduced diameter portion are inclined. FIGS. 6A to 6C are reference
views explaining a procedure of reducing a diameter in an end
portion of the metal tube.
Embodiment 1
[0039] First, a description will be given of the principle of the
molding method in accordance with the present invention with
reference to FIGS. 4A and 4B. The molding method in accordance with
the present invention is structured such as to arrange a plurality
of ring-shaped tools rotatably structured in such a manner as to be
brought into contact with the metal tube while pinching an outer
periphery of the metal tube to be reduced in diameter, and press
the outer periphery of the metal tube by an inner periphery of the
individual ring-shaped tool by moving the metal tube and the
ring-shaped tools along an axial core (which is inclined at a
previously set angle with respect to the axial core of the metal
tube) of the reduced diameter portion as well as moving the axial
core of the ring-shaped tool away from the axial core of the metal
tube, while relatively rotating the metal tube and the ring-shaped
tools, thereby reducing the diameter of the metal tube.
[0040] For example, an inner periphery of a ring-shaped tool 2
structured rotatable (rotatable on its own axis) around an axial
core 2a serving as a center is brought into contact with an outer
periphery of a metal tube to be reduced in diameter. At this time,
it is assumed that a distance between the axial core 2a of the
ring-shaped tool 2 and an axial core 1a of the metal tube is OF-A
shown in FIG. 4A. If the ring-shaped tool 2 is rotated around the
axial core 1a of the metal tube under this state, a circle 3 having
a diameter .PHI.D is formed by a circular arc of the ring-shaped
tool 2, as shown in the same drawing, however, the circle 3 is
identical to an outer diameter of the metal tube 1, and the
diameter reduction of the metal tube is not executed in this
state.
[0041] Next, as shown in FIG. 4B, the distance of the axial core 2a
of the ring-shaped tool 2 from the axial core 1a of the metal tube
is changed to OF-B which is larger than OF-A, and if the
ring-shaped tool 2 is rotated around the axial core 1a in this
state, a circle 4 having a smaller diameter .PHI.d than the
diameter (D is formed by the circular arc of the ring-shaped tool
2, as shown in the same drawing. At this time, a changing amount of
the ring-shaped tool 2 comes to a molding load applied to the metal
tube, and an outer diameter of the metal tube is reduced in
diameter from .PHI.D to .PHI.d.
[0042] As mentioned above, it is possible to reduce the diameter in
the end portion of the metal tube, by continuously changing a
displacement amount of the axial core 2a of the ring-shaped tool 2
from the axial core 1a of the metal tube, and continuously changing
the metal tube or the ring-shaped tool 2 along the axial core
1a.
[0043] Accordingly, it is possible to form two circles around the
axial core 1a, for example, by arranging a plurality of (for
example, two) ring-shaped tools 2 along the axial core 1a of the
metal tube so as to be close to each other, and rotating the
ring-shaped tools 2 around the axial core 1a of the metal tube in a
state in which the distances of the axial cores 2a of the
respective ring-shaped tools 2 from the axial core 1a are
different. In this case, it is possible to execute the diameter
reduction with respect to the metal tube by pressing inner
peripheries of two ring-shaped tools 2 to the outer periphery of
the metal tube by moving the ring-shaped tools 2 in a direction in
which the axial core 2a moves away from the axial core 1a of the
metal tube, while rotating the metal tube on its own axis or
rotating two ring-shaped tools 2 around the axial core 1a.
[0044] Further, it is possible to form approximately one circle
around the axial core 1a by forming contact positions of two
ring-shaped tools 2 with respect to the metal tube in a protruded
shape, arranging the protruded portions so as to be close to each
other, and rotating the ring-shaped tools around the axial core 1a
of the metal tube in a state in which distance of the axial cores
2a of the respective ring-shaped tools 2 from the axial core 1a
become equal. In this case, it is possible to execute the diameter
reduction with respect to the metal tube, by pressing the extremely
close positions in the direction of the axial core 1a in the outer
periphery of the metal tube by two ring-shaped tools 2 so as to
pinch, by moving two ring-shaped tools 2 in a direction in which
the axial cores 2a simultaneously move away from the axial core 1a
of the metal tube. Accordingly, it is possible to apply a greater
molding load to the individual ring-shaped tool 2 while preventing
a buckling which may be generated in the metal tube, and it is
possible to improve a molding efficiency.
[0045] As mentioned above, in accordance with the present
invention, the diameter reduction molding is simultaneously
executed with respect to the metal tube by two ring-shaped tools 2.
Accordingly, it is possible to set a magnitude of the molding load
applied to the individual ring-shaped tool 2 to a suitable value,
it is possible to achieve a secure molding by one step. In other
words, it is possible to improve a working rate by applying the
same molding load to each of the ring-shaped tools 2, and it is
possible to set the molding load in such a manner that a coarse
molding is executed by the preceding ring-shaped tool 2 and a
finish molding is executed by the subsequent ring-shaped tool
2.
[0046] In this case, in the same drawing, the diameter .PHI.D of
the circle 3 comes to twice as much as a value obtained by
subtracting the distance OF-A between the axial core 1a and the
axial core 2a from a radius of the ring-shaped tool 2. In the same
manner, the diameter .PHI.d of the circle 4 comes to twice as much
as a value obtained by subtracting the distance OF-B between the
axial core 1a and the axial core 2a from the radius of the
ring-shaped tool 2. Accordingly, it is possible to reduce a
diameter of a circle formed by the circular arc of the ring-shaped
tool 2 (reduce a diameter in the end portion of the metal tube), by
changing an interval (enlarging the interval) between the axial
core 2a of the ring-shaped tool 2 and the axial core 1a of the
metal tube.
[0047] A speed which moves the axial core 2a of the ring-shaped
tool 2 away from the axial core 1a of the metal tube can be
appropriately set in correspondence to a condition such as a
material, a thickness or the like of the metal tube, and can not be
definitely set.
[0048] The number of the ring-shaped tool is not particularly
limited, but it is preferable that at least two ring-shaped tools
are provided. In particular, the pressing positions of the
ring-shaped tools 2 to the metal tube face to each other by
arranging two ring-shaped tools 2 on a diameter centering on the
axial core 1a of the metal tube (at positions facing at 180
degree). Accordingly, it is possible to prevent the buckling which
may be generated in the metal tube so as to apply a greater molding
load. This case is advantageously employed at a time of molding
with respect to the metal tube in which the thickness is thin and
the risk that the buckling is generated is high.
[0049] Particularly, in the case that three or more ring-shaped
tools are arranged, it is preferable to set the moving directions
of the respective ring-shaped tools to an equal angle within a
surface orthogonal to the axial core 1a of the metal tube, and set
such that the applying methods of the molding loads are balanced at
a time of executing the molding work with respect to the metal
tube. In this case, the total of the molding loads applied to the
metal tube becomes large at a degree that the number of the
ring-shaped tool is increased. Accordingly, this structure is
advantageously employed in a case of molding a thick metal
tube.
[0050] In the present invention, since the inner periphery of the
ring-shaped tool is brought into contact with the outer periphery
of the metal tube to be reduced in diameter, it is necessary that
the inner diameter is larger than the outer diameter of the metal
tube. Further, since it is necessary that the ring-shaped tool is
brought into contact with the outer periphery of the metal tube so
as to rotate on its own axis, it is preferable to form a whole of
the ring-shaped tool as a rolling bearing structure.
[0051] It is not limited whether the metal tube is rotated or a
plurality of ring-shaped tools 2 are rotated, at a time of molding
the metal tube. Whichever may be rotated, no special problem is
generated. Particularly, in the case that a plurality of
ring-shaped tools are rotated, there is generated a risk that a
dynamic balance is not secured, however, in this case, since the
rotating speed at a time of rotating is not large, there is not
generated any problem.
Embodiment 2
[0052] Next, a description will be given of a structure of a
molding apparatus A in accordance with the present embodiment with
reference to the accompanying drawings. The molding apparatus A
shown in the drawing is structured such that a diameter reduction
can be executed at an axial core inclined with respect to the axial
core 1a of the metal tube 1 in the end portion of the metal tube 1,
by gripping the metal tube 1 to be reduced in diameter in the end
portion, arranging two ring-shaped tools 11 and 12 in the outer
periphery of the end portion of the metal tube 1, and moving the
ring-shaped tools 11 and 12 in a direction crossing to the axial
core 1a as well as moving the metal tube 1 in a direction moving
the metal tube 1 away from or close to the ring-shaped tools 11 and
12, while rotating the ring-shaped tools 11 and 12.
[0053] The molding apparatus A has a supply car 22 mounted to a
pair of rails 21, and the supply car 22 is structured such as to be
driven by a supply car driving apparatus 23 constituted by a servo
motor 23a and a ball spline 23b so as to be movable in directions
of arrows a and b along an installing direction of the rail 21.
Accordingly, it is possible to move the supply car 22 at a desired
speed in the direction of the arrow a or the direction of the arrow
b along the rail 21, by driving the servo motor 23a.
[0054] A carriage 26 mounting a chuck 25 forming a grip member
detachably gripping the metal tube 1 is arranged in the supply car
22, and the carriage 26 is driven by a carriage driving apparatus
27 constituted by a servo motor 27a and a ball spline 27b so as to
be movable in directions of arrows c and d corresponding to a
direction orthogonal to the installing direction of the rail 21 and
a direction moving close to or away from the ring-shaped tools 11
and 12 (a frame 31 mentioned below). Accordingly, it is possible to
move the carriage 26 at a desired speed in the direction of the
arrow c or the direction of the arrow d corresponding to the
orthogonal direction to the rail 21, by driving the servo motor
27a.
[0055] The chuck 25 detachably gripping the metal tube 1 is mounted
via a rotating table 28 serving as a revolving member provided in
the carriage 26 constructing the supply car 22. The structure of
the rotating table 28 is not particularly limited, but may be
formed as a general structure which has a driving means (not shown)
and is used as a rotating tool. The chuck 25 is fixed to a center
of rotation of the rotating table 28, and is structured such as to
freely revolve in directions of arrows e and f in accordance with
the rotation of the rotating table 28. Accordingly, it is possible
to revolve the chuck 25 at a desired speed in the direction of the
arrow e or the direction of the arrow f around the center of
rotation by driving the driving means (not shown).
[0056] In the supply car 22 structured as mentioned above, it is
possible to set a revolving angle of the chuck 25 to a desired
angle and set a position within a plane of the chuck 25 to a
desired position, as shown in FIG. 2, by synchronizing operations
of the supply car driving apparatus 23, the carriage driving
apparatus 27 and the rotating table 28.
[0057] Two ring-shaped tools 11 and 12 are arranged so as to face
at 180 degree on a straight line 31b passing through a center 31a
of a ring-shaped frame 31, as shown in FIG. 3, and are attached to
a rod 32a of a hydraulic cylinder 32 forming a tool moving member
attached to the frame 31. A pair of guide bars 33 are provided in
an inner peripheral surface of the frame 31 in parallel to the
straight line 31b of the frame 31 in correspondence to the
respective ring-shaped tools 11 and 12. Further, the structure is
made such that each of the ring-shaped tools 11 and 12 is guided by
the corresponding guide bar 33, whereby each of the axial cores 11a
and 12a can accurately move on the straight line 31b with respect
to the center 31a of the frame 31 (the axial core of the frame 31).
Further, the guide bar 33 has a function of countering a thrust
load applied to each of the ring-shaped tools 11 and 12 at a time
of molding with respect to the metal tube 1, in addition to a
function of guiding the moving direction of each of the ring-shaped
tools 11 and 12.
[0058] The ring-shaped tools 11 and 12 have a function of
transmitting the molding load applied from the hydraulic cylinder
32 as well as being brought into contact with the outer periphery
of the metal tube 1, and have molding rings 11b and 12b structured
such as to rotate on its own axis on the basis of a contact
friction with the metal tube 1. The inner surfaces of the molding
rings 11b and 12b may be formed in a tapered shape, however, in
this case, there is a risk that a general-purpose property of a
working condition including a taper angle formed in the metal tube
1 is deteriorated.
[0059] Accordingly, the present embodiment is structured such that
the molding can be executed by forming rims 11c and 12c in which
end portions in one side are protruded, and bringing the rims 11c
and 12c into pressure contact with the outer periphery of the metal
tube 1. In particular, in the present embodiment, the rims 11c and
12c formed in the molding rings 11b and 12b of the ring-shaped
tools 11 and 12 are arranged in such a manner as to be capable of
being adjacent to each other, and the structure is made such as to
be capable of simultaneously molding extremely close positions of
the metal tube 1 by the respective rims 11c and 12c. Since the
ring-shaped tools 11 and 12 are structured as mentioned above, it
is possible to apply the molding load to the metal tube 1
approximately on the straight line 31b, and it is possible to
prevent the bucking from being generated.
[0060] Each of the molding rings 11b and 12b is rotatably supported
to the bearing member 13 attached to the rod 32a of the hydraulic
cylinder 32, thereby being structured such as to freely rotate on
its own axis. In other words, a ring-shaped case 13a is attached to
the rod 32a of the hydraulic cylinder 32, a bearing 13b is arranged
in the case 13a, and the molding bearings 11b and 12b are pressure
inserted to an inner ring of the bearing 13b. A fitting portion 13c
fitted to the guide bar 33 is formed at a predetermined position on
an outer periphery of the case 13, and the fitting portion 13c is
fitted to the guide bar 33, whereby it is possible to move each of
the ring-shaped tools 11 and 12 along the straight line 31b in
accordance with the drive of the hydraulic cylinder 32.
[0061] Further, flanges 11d and 12d are respectively provided in
the molding rings 11b and 12b, and the structure is made such as to
transmit the thrust load applied to the molding rings 11b and 12b
to the bearing member 13 via the flanges 11d and 12d at a time of
molding with respect to the metal tube 1. Accordingly, the thrust
load generated at a time of reducing the diameter of the metal tube
1 by each of the ring-shaped tools 11 and 12, is transmitted to the
frame 31 from the molding rings 11b and 12b via the fitting portion
13c of the bearing member 13, and the guide member 33.
[0062] The frame 31 attaching the ring-shaped tools 11 and 12
thereto is fixed to one end portion of a spindle 36 rotatably
supported with respect to a bridge groove 35. A pulley 37a is fixed
to the other end portion side of the spindle 36, and a belt 37d is
wound between the pulley 37a and a pulley 37c fixed to a driving
mechanism 37b including a motor, a variable speed gear and a speed
reduction gear. Accordingly, it is possible to rotate the frame 31
at a desired rotating speed, by driving the driving mechanism
37b.
[0063] In this case, the present embodiment utilizes the hydraulic
cylinder 32 at a time of moving the ring-shaped tools 11 and 12
along the straight line 31b of the frame 31, however, it is not
necessary to limit to the hydraulic cylinder, but it is possible to
employ any structure as far as the structure can achieve a
reciprocating linear motion as well as transmitting the molding
load necessary for reducing the diameter of the metal tube 1 to
each of the ring-shaped tools 11 and 12.
[0064] In the molding apparatus A structured as mentioned above, it
is possible to incline the axial core 1a of the metal tube 1
gripped to the chuck 25 with respect to the axial core 31a of the
frame 31 by synchronously actuating the supply car driving
apparatus 23, the carriage driving apparatus 27 and the rotating
table 28, thereby revolving the chuck 25, and it is possible to
bring an intersecting point between the axial cores 1a and 31a into
line with the straight line 31b formed in the frame 31. Further, it
is possible to move the metal tube 1 inclined with respect to the
axial core 31a of the frame 31 along the axial core 1a, while
executing the diameter reducing work with respect to the metal tube
1.
[0065] Further, it is possible to reduce the diameter while
continuously changing the angle of incline of the axial core 1a of
the metal tube 1 with respect to the axial core 31a of the frame
31, by continuously actuating the supply car driving apparatus 23,
the carriage driving apparatus 27 and the rotating table 28.
[0066] Further, in the molding apparatus A mentioned above, the
structure is made such that the rotating table 28 is provided in
the chuck 25, and the angle of the chuck 25 is changed by the
rotating table 28, however, the structure is not limited to this
structure, but the structure may be made such that the rotating
table is provided in the frame 31 and the axial core 31a of the
frame 31 is inclined with respect to the axial core 1a of the metal
tube 1. In this case, it is preferable to structure such as to be
capable of integrally revolving the driving systems 37a to 37d of
the frame 31 including eth frame 31 and the spindle 36 by setting
the rotating table in an uprising portion of the bridge groove
35.
Embodiment 3
[0067] Next, a description will be given of an embodiment of a
first molding method in accordance with the present invention.
First, a description will be given of a molding procedure in the
case that a main tube of the metal tube 1 and the axial core of the
diameter reducing portion are in line with each other with
reference to FIG. 5A. The molding method corresponds to a basic
procedure at a time of reducing the diameter in the end portion of
the metal tube 1, and makes it possible to easily understand the
embodiment mentioned below.
[0068] The supply car 22 is moved in the direction of the arrow a
or the direction of the arrow b by driving the supply car driving
apparatus 23, and the axial core of the chuck 25 (the axial core 1a
of the metal tube 1) is brought into line with the axial core 31a
of the frame 31. At the same time, the axial core of the chuck 25
is brought into line with the axial core 31a of the frame 31 by
driving the rotating table 28.
[0069] The axial cores 11a and 12a of the respective ring-shaped
tools 11 and 12 are moved so as to be approximately brought into
line with the axial core 31a of the frame 31, by driving the
hydraulic cylinder 32 attached to the frame 31. The movement is
executed for the purpose of passing the metal tube 1 through the
rims 11c and 12c provided in the molding rings 11b and 12b of the
respective ring-shaped tools 11 and 12. Accordingly, it makes no
difference whether or not the axial cores 11a and 12a of the
respective ring-shaped tools 11 and 12 are accurately brought into
line with the axial core 31a of the frame 31, and in the case that
the outer diameter of the metal tube 1 is sufficiently smaller than
the inner diameter of the rims 11c and 12c provided in the molding
rings 11b and 12b of the respective ring-shaped tools 11 and 12, it
is not necessary to accurately bring them into line with each
other.
[0070] Next, the end portion of the metal tube 1 is passed through
each of the ring-shaped tools 11 and 12 by gripping the metal tube
1 to be reduced in diameter by the chuck 25, and driving the
carriage driving apparatus 27. At this time, a length of the end
portion of the metal tube 1 passed through each of the ring-shaped
tools 11 and 12 is equal to a previously set length of the end
portion to be reduced in diameter. Next, the rims 11c and 12c of
the respective ring-shaped tools 11 and 12 are brought into contact
with the outer periphery of the metal tube 1 by driving the
hydraulic cylinder 32. A preparation for executing the diameter
reduction is finished in this state.
[0071] The frame 31 is rotated at a previously set rotating speed
by driving the driving mechanism 37c. Two hydraulic cylinders 32
are simultaneously driven in accordance with the rotation start of
the frame 31, and the axial cores 11a and 12a of the respective
ring-shaped tools 11 and 12 are moved in such a manner as to move
away from the axial core 1a of the metal tube 1. Since the rims 11c
and 12c apply the molding load to the outer periphery of the metal
tube 1 in accordance with this movement, the end portion of the
metal tube 1 is reduced in diameter. It is possible to reduce the
diameter in the end portion of the metal tube 1, by driving the
carriage driving apparatus 27 in correspondence to the start of the
diameter reduction, and moving the metal tube 1 in the direction of
the arrow c or the direction of the arrow d.
[0072] In the process of the diameter reduction with respect to the
end portion of the metal tube 1 mentioned above, the axial core 1a
of the metal tube 1 and the axial core 31a of the frame 31 are held
in a state of being brought into line with each other. Accordingly,
the axial core of the reduced diameter portion is in line with the
axial core 1a of the metal tube 1. Further, it is possible to set
the taper angle in the end portion of the metal tube 1 by
controlling a moving speed of each of the ring-shaped tools 11 and
12 along the guide bar 33 by means of the hydraulic cylinder 32,
and a moving speed in the direction of the arrows c and d of the
metal tube 1 by means of the carriage driving apparatus 27.
Embodiment 4
[0073] Next, a description will be given of a case of reducing a
diameter in a taper shape having an axial core which is in parallel
to the axial core 1a at an eccentric position (an amount of
eccentricity a) from the axial core 1a of the metal tube 1, with
reference to FIG. 5B.
[0074] First, the axial core 1a of the metal tube 1 is made
eccentric at a previously set amount of eccentricity .alpha. from
the center 31a of the frame 31, by driving the supply car driving
apparatus 23. Further, each of the ring-shaped tools 11 and 12 is
moved by driving the hydraulic cylinder 32.
[0075] Further, the axial cores 11a and 12a of the respective
ring-shaped tools 11 and 12 are moved in such a manner as to be
moved away from the center 31a of the frame 31, by gripping the
metal tube 1 by the chuck 25 so as to pass the end portion through
each of the ring-shaped tools 11 and 12, thereafter rotating the
frame 31 in the same manner as the embodiment 3 mentioned above,
and simultaneously driving two hydraulic cylinders 32. The rims 11c
and 12c can be brought into pressure contact with the outer
periphery of the metal tube 1 so as to reduce the diameter in
accordance with the movement. Further, it is possible to reduce the
diameter in the end portion of the metal tube 1 in the taper shape
around the axial core which is eccentric from the axial core 1a, by
driving the carriage driving apparatus 27 so as to move the metal
tube 1 in the direction of the arrow c or the direction of the
arrow d.
Embodiment 5
[0076] Next, a description will be given of an embodiment of a
second molding method in accordance with the present invention.
First, a description will be given of a case of reducing a diameter
in the end portion of the metal tube 1 while moving the axial core
1a of the metal tube 1 and the axial core 31a of the frame 31 with
time and relatively, with reference to FIG. 6A.
[0077] First, the axial core of the chuck 25 (the axial core 1a of
the metal tube 1) is brought into line with the axial core 31a of
the frame 31 by driving the supply car driving apparatus 23 and the
rotating table 28. Further, each of the ring-shaped tools 11 and 12
is moved so as to be capable of accommodating the metal tube 1 by
driving the hydraulic cylinder 32.
[0078] Next, the end portion is passed through each of the
ring-shaped tools 11 and 12 by gripping the metal tube 1 by the
chuck 25. In this state, the axial core 1a of the metal tube 1 and
the axial core 31a of the frame 31 are in line with each other.
Thereafter, the axial cores 11a and 12a of the respective
ring-shaped tools 11 and 12 are moved in such a manner as to be
moved away from the axial core 31a of the frame 31, by rotating the
frame 31, and simultaneously driving two hydraulic cylinders 32.
The rims 11c and 12c are brought into pressure contact with the
outer periphery of the metal tube 1 in accordance with the
movement, and the diameter reduction is started.
[0079] The metal tube 1 is moved in the direction of the arrow c or
the direction of the arrow d by driving the carriage driving
apparatus 27 in accordance with the start of the diameter reduction
with respect to the end portion of the metal tube 1 caused by each
of the ring-shaped tools 11 and 12, and the drive of the supply car
driving apparatus 23 is simultaneously started. A moving length of
the carriage 26 in the direction of the arrow c or the direction of
the arrow d is set to be equal to the previously set length of the
reduced diameter portion in the end portion of the metal tube 1. It
is possible to pass the center 31a (the straight line 31b) of the
frame 31 through a locus on a line .beta. shown in FIG. 6A by
moving the supply car 22 at the previously set distance .alpha.
(the amount of eccentricity .alpha.) in the direction of the arrow
b, during the period that the carriage 26 continues the movement
mentioned above, whereby it is possible to mold in a state of
inclining at an angle .theta.a with respect to the axial core 1a of
the metal tube 1.
[0080] Further, when the moving amount of the supply car 22 in the
direction of the arrow b becomes equal to the previously set amount
of eccentricity .alpha., it is possible to mold the reduced
diameter portion having the axial core 1b inclined at the angle
.theta.a with respect to the axial core 1a of the metal tube 1, in
the end portion of the metal tube 1. In the present embodiment, as
shown in FIG. 6A, a boundary line between the metal tube 1 and the
reduced diameter portion is formed within a surface which is
approximately vertical to the axial core 1a of the metal tube
1.
Embodiment 6
[0081] Next, a description will be given of a case of molding a
reduced diameter portion inclined at an angle .theta.b with respect
to the axial core 1a of the metal tube 1, with reference to FIG.
6B.
[0082] First, an angle of incline of the axial core 1a of the metal
tube 1 gripped to the chuck 25 with respect to the axial core 31a
of the frame 31 is set to .theta.b by rotating the rotating table
28, for example, in a direction of an arrow e. Next, the carrier
car 22 is moved, for example, in the direction of the arrow b, in
such a manner that the axial core 1a of the metal tube 1 gripped to
the chuck 25 is in line with the center 31a (the straight line 31b)
of the frame 31, by driving the supply car driving apparatus 23.
Further, each of the ring-shaped tools 11 and 12 is moved so as to
be capable of accommodating the metal tube 1 inclined at the angle
.theta.b by driving the hydraulic cylinder 32.
[0083] Next, the end portion is passed through each of the
ring-shaped tools 11 and 12 by gripping the metal tube 1 by the
chuck 25, thereafter, the axial cores 11a and 12a of the respective
ring-shaped tools 11 and 12 are moved in such a manner as to be
moved away from the axial core 31a of the frame 31, by rotating the
frame 31, and simultaneously driving two hydraulic cylinders 32, in
the same manner as the embodiment 3 mentioned above. The rims 11c
and 12c are brought into pressure contact with the outer periphery
of the metal tube 1 in accordance with the movement, and the
diameter reduction is started.
[0084] It is possible to mold the reduced diameter portion having
the axial core 1b inclined at the angle .theta.b with respect to
the axial core 1a in the end portion of the metal tube 1, by
synchronizing the movement in the direction of the arrow d of the
metal tube 1 caused by driving the carriage driving apparatus 27,
and the movement in the direction of the arrow b of the supply car
22 caused by driving the supply car driving apparatus 23, in a
state of maintaining the angle of incline of the rotating table 28,
after the diameter reduction in the end portion of the metal tube 1
is started. In the present embodiment, as shown in FIG. 6B, a
boundary line between the metal tube 1 and the reduced diameter
portion is formed within a surface inclined at the angle .theta.b
with respect to the axial core 1a of the metal tube 1.
Embodiment 7
[0085] A description will be given of a case of molding while
continuously inclining the axial core 1b of the reduced diameter
portion from a state of bringing the axial core 1b into line with
the axial core 1a of the metal tube 1 to an angle .theta.c, with
reference to FIG. 6C.
[0086] First, the axial core of the chuck 25 (the axial core 1a of
the metal tube 1) is brought into line with the axial core 31a of
the frame 31 by driving the supply car driving apparatus 23 and the
rotating table 28. Further, each of the ring-shaped tools 11 and 12
is moved in such a manner as to accommodate the metal tube 1 by
driving the hydraulic cylinder 32.
[0087] Next, the end portion is passed through each of the
ring-shaped tools 11 and 12 by making the chuck 25 grip the metal
tube 1. Thereafter, the axial cores 11a and 12a of the respective
ring-shaped tools 11 and 12 are moved in such a manner as to be
moved away from the axial core 31a of the frame 31 by rotating the
frame 31 and simultaneously driving two hydraulic cylinders 32. The
rims 11c and 12c are brought into pressure contact with the outer
periphery of the metal tube 1 in accordance with the movement, and
the diameter reduction is started.
[0088] There are synchronously actuated the rotation of the
rotating table 28, for example, in a direction of an arrow e, the
movement of the metal tube 1 in a direction of an arrow d caused by
driving the carriage driving apparatus 27, and the movement of the
supply car 22 in a direction of an arrow b caused by driving the
supply car driving apparatus 23, respectively in accordance with
the start of the diameter reduction applied to the metal tube 1. In
other words, it is possible to continuously increase the angle of
incline of the axial core 1b of the diameter reduced portion with
respect to the axial core 1a of the metal tube 1, by increasing the
angle of incline of the axial core 1b with respect to the axial
core 1a by continuously rotating the rotating table 28 in
correspondence to the increase of the moving distance in the
direction of the arrow d of the metal tube 1 generated by the
carriage driving apparatus 27, and simultaneously increasing the
moving distance in the direction of the arrow b of the supply car
22 by means of the supply car driving apparatus 23.
[0089] Further, in the case that the moving distance in the
direction of the arrow d of the metal tube 1 by means of the
carriage driving apparatus 27, the angle of rotation of the
rotating table 28, and the moving distance in the direction of the
arrow b of the supply car 22 by means of the supply car driving
apparatus 23, respectively reach the previously set times and the
previously set values, it is possible to mold the diameter reduced
portion having the axial core 1b which is inclined continuously to
the angle .theta.c from the original coinciding state with the
axial core 1a in the end portion of the metal tube 1. In the
present embodiment, as shown in FIG. 6C, the boundary line between
the metal tube 1 and the diameter reduced portion is formed within
the surface which is approximately vertical to the axial core 1a of
the metal tube 1.
[0090] In each of the embodiments mentioned above, the description
is given of the case that the end portion of the metal tube 1 is
reduced in diameter in the tapered shape to the terminal end,
however, it is not always necessary to mold in the tapered shape to
the terminal end of the metal tube 1, but the terminal end portion
of the metal tube 1 may be formed in a straight tube shape, as
shown in FIG. 2.
INDUSTRIAL APPLICABILITY
[0091] In accordance with the molding method of the present
invention mentioned above, it is possible to rationally reduce the
diameter in the end portion of the metal tube to be reduced in
diameter by applying the eccentric rotational molding method, and
it is possible to preferably utilize the molding method of the
present invention as a manufacturing means of a seamless diameter
reduced portion in a piping distributing a fluid, in the
manufacturing means of the exhaust gas converter.
[0092] Further, since the molding apparatus in accordance with the
present invention can rationally execute the molding method in
accordance with the present invention, can prevent the buckling
which may be generated in the metal tube to be molded, and can
preferably reduce the diameter by one step, the molding apparatus
in accordance with the present invention can be preferably utilized
in a factory reducing the diameter of the metal tube or the
like.
[0093] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all modifications, equivalent
structures and functions.
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