Field of the Invention
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The present invention relates to a method and apparatus for diametrically
expanding a desired portion, such as a middle portion, of metal shafts which
can be solid like bars or tubular like pipes.
Background Art
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It is common practice to obtain a metal shaft having a locally increased
diameter by machining a blank shaft of a relatively large diameter. However,
this machining process disadvantageously takes time, and what is worse, tends
to waste metal as cutting chips.
-
In general, the mechanical power transmission shafts require the provision
of components such as gears, cams, and sprockets whose diameter is larger than
that of the shafts. In order to provide the metal shafts with these components,
a mechanical method is not economical where the metal flesh of a shaft is
machined to form gears as integral parts. An alternative way is to produce
those component parts on a separate process, and join them to the shafts by
welding or bolting. This method is not efficient. Therefore, a metallurgical
process was proposed for forcing a metal shaft to diametrically expand in a
desired portion, and cutting gears or cams there. However, it has been
considered to be impracticable to put the proposed metallurgical method in
practice.
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The inventor of the present application invented a method of expanding the
diameter of a metal shaft in its middle portion through rotation, bending and
compression, which is disclosed in Japanese Patent No. 1,993,956. This
metallurgical method has overshadowed the conventional mechanical method, and
made it possible to form gears or cams in the diametrically expanded portion of
a metal shaft.
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According to the previous invention referred to above, the metal shaft is
subjected to rotation and bending under a sufficient compression until a
diametrically expanded portion is obtained, and after the shaft is bent back,
the rotation and bending are stopped. If the compressive force is too large, the
shaft must be held firmly to withstand it. In contrast, if it is too low, an
increased number of rotations is required until a desired shape is obtained,
thereby taking a long time before the desired portion of the shaft is
diametrically expanded. A further disadvantage is the lack of precision
involved in a pair of rotary holders provided in the apparatus, one having a
biasing means for bending the work, and the other having a pressing means for
causing one holder to approach the other.
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Accordingly, one object of the present invention is to provide a method
and apparatus capable of performing a local diametral expansion of a metal shaft
efficiently and accurately.
-
Another object of the present invention is to provide a method and
apparatus capable of careful inspection of deformation likely to occur in a
metal shaft in view of the insufficient analysis on the mechanism of the
diametral expansion of a metal shaft.
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A further object of the present invention is to provide a method and
apparatus capable of diametrically expanding a portion of a metal shaft to a
collar-like shape of any size.
-
A still further object of the present invention is to provide a method and
apparatus capable of diametrically expanding a metal shaft with no detrimental
torsion in the metal shaft, which would otherwise decrease the tensile strength
of the metal shaft after the diametral expansion is finished. The torsion
results from the fact that one of the rotary holders is subjected to a torque
which is transmitted to the other holder through the solid work.
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Another object of the present invention is to provide a method and
apparatus capable of diametrically expanding a metal shaft with use of a
conventional lathe.
Summary of the Invention
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The present invention provides a method for diametrically expanding a
predetermined part of a metal shaft, including the steps of holding the shaft
between a pair of holders spaced at a distance (D); rotating the work around
its axis, moving one of the holders toward the other holder so as to compress
the work; biasing one of the holders in a direction which crosses the axis of
the other holder, so as to bend the work and build up bulged portions accruing
inside the bent portion around the periphery of the work within the distance
(D) until a desired expansion is achieved; and straightening up the work,
wherein the compression is constantly applied to both the inner and outer sides
of the work to be bent, and the rotation is initiated at the latest immediately
after the bending is started, and the straightening-up is performed under the
continued compression and rotation.
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In this case, the compression is relatively low at the initial stage of the
diametral expansion, and increases in accordance with the advance of the
expansion.
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The present invention also provides an apparatus for carrying out the
above-mentioned method, including a driving rotary section and a driven rotary
section arranged at a predetermined distance, each of the rotary sections
comprising holders for securing a work therebetween; a driver for operating the
driving rotary section; a pressing device for axially compressing the work held
by the holders; and a biasing device for declining the axis of the work; wherein
the pressing device applies the compression to one of the rotary sections, and
the biasing device declining the other rotary section.
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According to another aspect of the invention, the apparatus includes a
driving rotary section and a driven rotary section arranged at a predetermined
distance, each of the rotary sections comprising holders for securing a work
therebetween; a driver for operating the driving rotary section; a pressing
device for axially compressing the work held by the holders; and a biasing
device for declining the rotary section so as to cause the work to decline with
respect to its axis; wherein either the driving rotary section or the driven
rotary section is arranged rotatably around a pivot provided in a direction
perpendicular to the axis of the work, and the rotatably arranged rotary section
is supported by the pivot so as to enable the simultaneous inspection of the
inner and outer sides of the bent portion of the work.
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As a further preferred embodiment the apparatus can be provided with a
slidable frame on the base plate, and a rotary framework rotatably connected to
the slidable frame through a bearing, and wherein the driving rotary section is
secured to the base plate and the driven rotary section is secured to the rotary
framework.
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As another preferred embodiment, especially suitable for processing a work
having a relatively large diameter, the apparatus includes a driving rotary
section and a driven rotary section arranged at a predetermined distance, each
of the rotary sections comprising holders for securing a work therebetween; a
driver for operating the driving rotary section; a pressing device for axially
compressing the work held by the holders; and a biasing device for declining the
rotary section so as to cause the work to decline with respect to its axis;
wherein the pressing device applies the compression to one of the rotary
sections, and the biasing device declining the other rotary section.
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In this case, the apparatus can be provided with a displacing device for
shifting the center of rotation between the holders in accordance with a sliding
distance covered by the pressing device.
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As a further preferred embodiment the apparatus includes a pair of rotary
sections; a holder provided in each of the rotary sections for holding a work;
a sliding device for causing at least one of the rotary sections to move toward
and away from the other rotary section; a biasing device for declining at least
one of the rotary sections with respect to the axis of the other rotary section;
a driver for rotating the work held by the holders around its axis; and a
transmission for transmitting the torque of one rotary section to another so as
to effect the synchronous rotation of the two rotary sections.
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More specifically, the transmission includes a rotating division in which
rotatable brackets are provided, having a pair of splines interposed between
them, the splines comprising gears engaged with follower gear provided in the
rotating division, thereby transmitting a torque of one of the rotating division
to the other.
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As a more practical embodiment the apparatus includes a driving rotary
section provided with a first work holder and being capable of rotating the
work held by the holder; a driven rotary section provided with a second work
holder on an opposite side to the holder of the driving rotary section and being
capable of moving toward and away from the driving rotary section; a biasing
device for declining the second holder with respect to the axis of the first
holder; and a pressing device for pressing the driven rotary section toward the
driving rotary section; wherein the driving rotary section is driven by an
arrangement in which the first work holder is connected to a chuck of a lathe so
as to utilize the torque of the lathe.
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In this case the pressing device is preferably placed between a base plate
and a slidable frame, and wherein the base plate is provided with a tapered
shaft, the tapered shaft and the first work holder being connected to the
lathe, thereby compensating a repulsive force involved in operating the
pressing device within the base plate.
Brief Description of the Drawings
-
- Figs. 1a to 1d are schematic views explaining the process of performing a
method according to the invention;
- Fig. 2 is a plan view of an apparatus according to the invention;
- Fig. 3 is a side view of the apparatus shown in Fig. 2;
- Fig. 4 is a cross-sectional side view of a rotary holder incorporated in
the apparatus shown in Fig. 2;
- Fig. 5 is a plan view of the rotary holder shown in Fig. 4
- Fig. 6 is a plan view of an apparatus according to another embodiment of
the invention;
- Fig. 7 is a side view of the apparatus shown in Fig. 6;
- Fig. 8 is a cross-sectional side view of the apparatus shown in Fig. 6;
- Fig. 9 is a cross-sectional side view of a driving rotary section
incorporated in the apparatus shown in Fig. 6;
- Fig. 10 is a cross-sectional side view of a driven rotary section
incorporated in the apparatus shown in Fig. 6;
- Fig. 11 is a plan view of a feeder incorporated in the apparatus shown in
Fig. 6;
- Fig. 12 is a perspective view of chucks incorporated in the apparatus shown
in Fig. 6;
- Fig. 13 is a side view of a modified version of chucks incorporated in the
apparatus shown in Fig. 6;
- Fig. 14 is a schematic view of the apparatus shown in Fig. 6 when it is in
the process of performing the diametral expansion;
- Fig. 15 is a plan view of the apparatus shown in Fig. 6 when the process is
finished;
- Fig. 16 is a plan view of an apparatus according to a further embodiment of
the invention;
- Fig. 17 is a cross-sectional side view of the apparatus shown in Fig.16;
- Fig. 18 is a plan view of a slidable framework and a rotary framework
(shown in imaginary lines) incorporated in the apparatus shown in Fig. 16;
- Fig. 19 is a cross-sectional side view of the arrangement shown in Fig. 18;
- Fig. 20 is a schematic view explaining the process of performing the
diametral expansion according to the embodiment shown in Fig. 16;
- Fig. 21 is a plan view of a still further embodiment of the invention;
- Fig. 22 is a cross-sectional side view of the apparatus shown in Fig.21;
- Fig. 23 is a perspective view of another embodiment of the invention;
- Fig. 24 is a plan view of the apparatus shown in Fig. 23;
- Fig. 25 is a cross-sectional side view of the apparatus shown in Fig.23;
- Fig. 26 is a plan view of a slidable framework and a sliding device
incorporated in the apparatus shown in Fig. 23;
- Fig. 27 is a plan view of a rotary frame and a biasing device incorporated
in the apparatus shown in Fig. 23;
- Fig. 28 is a cross-sectional view taken along the line A-A in Fig. 24;
- Fig. 29 is a cross-sectional view of a transmission incorporated in the
apparatus shown in Fig. 23;
- Fig. 30 is a plan view of an apparatus according to a further embodiment of
the invention;
- Fig. 31 is a schematic view of the apparatus shown in Fig. 30 when it is in
the process of performing the diametral expansion;
- Fig. 32 is a perspective view of an apparatus according to a still further
embodiment of the invention;
- Fig. 33 is a plan view of the apparatus shown in Fig. 32;
- Fig. 34 is a cross-sectional side view of the apparatus shown in Fig. 32;
- Fig. 35 is a cross-sectional side view explaining the process of performing
the diametral expansion according to the embodiment shown in Fig. 32;
- Fig. 36 is a side view of a lathe connected to the apparatus shown in Fig.
32;
- Fig. 37 is a cross-sectional side view of an apparatus according to a still
further embodiment of the invention;
- Fig. 38 is a plan view of the apparatus shown in Fig. 37;
- Fig. 39 is a cross-sectional side view explaining the process of performing
the diametral expansion;
- Fig. 40 is a schematic cross-sectional view explaining the first step of
performing the diametral expansion where a work is mounted on the apparatus;
- Fig. 41 is a schematic cross-sectional view explaining the second step
where the work is subjected to rotation, compression and bending;
- Fig. 42 is a schematic cross-sectional view explaining the third step where
the work is subjected to the continued rotation, compression and bending;
- Fig. 43 is a schematic cross-sectional view explaining the fourth step
where the work is subjected to straightening up under the continued rotation and
compression); and
- Fig. 44 is a cross-sectional view of a finished diametrically expanded
portion of the work.
-
Detailed Description of the Preferred Embodiments
-
Referring to Figs 1a, 1b, 1c and 1d, respectively, the principle underlying
the present invention will be described:
-
A pair of holders are co-axially arranged or aligned to hold a work (W)
between them, wherein the work (W) can be solid or tubular. The holders are
spaced by a distance (D) (Fig. la). Then, compression is axially applied until
the work (W) is inwardly bent between the holders, and rotation is imparted to
it as shown in Fig. 1b. The bending diametrically expands a portion in the work.
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The applied compression negates a possible pull which would otherwise act on
the work, and therefore is stepped up. The rotation is effective to equal the
diametral expansion around the periphery of the work (W). To this end, it is
preferable that the work (W) is rotated while being subjected to the
compression. The rotation can be started at any time.
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The work (W) kept in the above-mentioned conditions is rotated several
times. The sides of the diametrically expanded portion extends to each holding
part, and are subjected to the compression. In this way the compression is
stepped up. This means that the initial compressive force can be low, thereby
reducing the holding force of each holder upon the work (W). As the compression
is continued, the compressive force increases to shorten the operation hour
(Fig. 1c). After the desired diametral expansion is finished, the work (W) is
bent back until it becomes straight while the compression and rotation are
repeated as shown in Fig. 1d. After the work (W) is straightened up, the
rotation and compression are stopped, wherein either stoppage can be earlier
than the other.
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Referring to Figs. 2 to 5, a first preferred embodiment of the present
invention will be more particularly described:
-
The illustrated apparatus is a collar forming apparatus (hereinafter
'apparatus') 1 which is provided with a stand 2 on a floor, a rotary framework 3
axially slidable on the stand 2, a driving rotary holder 4 mounted on the
rotary framework 3 and driven by a motor 5, and a driven rotary holder 6
located on the opposite side to the driving rotary holder 4, a biasing device 7
for declining the driven rotary holder 6 with respect to the axis of the driving
rotary holder 4, and a pressing device 8 for pressurizing the driving rotary
holder 4 toward the driven rotary holder 6; in other words, for compressing the
driving rotary holder toward the driven rotary holder 6.
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The stand 2 is composed of pillars 10 which are mounted on base plates 9,
and parallel rails 11 spacedly arranged between which the pressing device 8 is
fixed to a first support 12 at a front section of the apparatus 1. The driven
rotary holder 6 is fixed to a second support 13 in the middle of the apparatus
1. The second support 13 is provided with a bore 13a in which a pivot 14 rests
so as to allow the holder 6 to rotate.
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The rotary framework 3 mounted on the stand 2 includes side frames 15
axially arranged, transverse frames 16 fixed on the top of the side frames 15,
and a stand 17 on which a motor is mounted. The rotary framework 3 is crosswise
limited by the side frames 15, and vertically limited by the transverse frames
16. In this way the axial movement of the rotary framework 3 is effected along
the rails 11. Preferably, a lower framework 18 is provided in a lower part of
the framework 16.
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The driving rotary holder 4 is provided on the rotary framework 3. The
holder 4 includes a supporting sleeve 20 rotatably carried within a sleeve 19
secured to the rear framework 16. The supporting sleeve 20 is provided with a
chamber 20a whose end is outwardly tapered at an angle is α ° toward the other
holder 6, and also provided with a threaded portion 20b on and around the
tapered end. The chamber 20 houses chucks 21 each of which has a tapered
outside wall corresponding to the tapered inside wall of the chamber 20a. The
chuck 21 is obtained by splitting the body into a plurality of portions and
forcefully inserted in the chamber 20a. The end portion of the holder 20 is
covered with a fastening nut 22 with its inner space 21a being open. The work
(W) is forced into the inner space 21a, and becomes held therein.
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The rotary holder 4 is associated with a driving means 5, which is an
electric motor 23 in the illustrated embodiment, to receive a driving force
therefrom. The motor 23 has an output shaft provided with a driving gear 24
engaged with a driven gear 25 located in the front end of the holder 20.
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Being arranged opposite the driving rotary holder 4, the driven rotary
holder 6 has the same structure as the holder 4. The holder 6 is fixed to a
rotary plate 26 connected to the pivot 14 which is carried in the bore 13a of
the second support 13. In this way the holder 6 is rotated in such a manner
that it become biased with respect to its axis. The holders 4 and 6 are
aligned, and ratable around the pivot 14.
-
The biasing device 7 is provided to rotate the driven rotary holder 6. It
includes a nut 28 rotatably connected to a bracket 27 of a rear end of the
rotary plat 26, a motor 30 secured to a rotary plate 29 provided on the rails
11, the output shaft of the motor 30 having a thread portion 21 engaged with the
nut 28. The rotation of the motor 30 in either direction causes the thread
portion 21 to rotate around the rotary plate 26, but the nut 28 does not rotate
because of its fixation to the bracket 27. In this way the driven rotary holder
6 is rotated in a horizontal plane. The biasing device 7 is not limited to this
embodiment but can be a version in which the rotary holder 6 is rotated around
the pivot 14 with the addition of a link-system pressing device or a fluidsystem
pressing device which causes the work (W) to become biased by applying a
force to it in a directon which crosses the axis of the work (W).
-
The pressing device 8 is provided in the rear lower part of the driving
rotary holder 4. This device 8 compresses the driving rotary holder 4 toward
the driven rotary holder 6. It is constructed with a double-acting hydraulic
cylinder 32 secured to the stand 2 at one end and to the slidable framework 3
at the other end. Instead of the hydraulic cylinder 32, a hydraulic jack or a
fluid cylinder can be employed.
-
No controller is illustrated in the drawings for the motors 23 and 30, and
the hydraulic cylinder 32 but it can be designed to optionally set the rotations
per minute of each motor 23 and 30 and a pressure provided by the cylinder 32.
The angle of the biasing device 7 can be adjusted as desired.
-
In making a desired local diametral expansion, the rotary holders 4 and 6
are aligned, and the chucks 21 of both holders are spaced at a predetermined
distance (D) between which a work (W) is placed, and held by the nut 22.
-
The hydraulic cylinder 32 is operated so that the work (W) is bent until it
is compressed. Then the motor 30 is driven to further bend the work (W) at 3
to 7°. The time for driving the motor 30 is optional.
-
The rotation continues several times, thereby causing the local diametral
expansion to grow and at the same time, subjecting its surrounding to the
compressive pressure. Therefore, no slip occurs between the work (W) and the
chucks 21 in spite of an increase in compression. Owing to the increased
compressive pressure, the local diametral expansion can be finished in a short
time.
-
When the local diametral expansion is finished, the work (W) is bent back
to straighten up. Then the motor 23 and the hydraulic cylinder 32 are
deenerzied.
-
The work (W) is withdrawn out of the holders simply by loosening the nut
22.
-
As evident from the foregoing description, the apparatus of the invention
does not require a large force for holding the work (W), thereby allowing the
employment of a simplified mechanism. In addition, owning to the separate
provision of the presser and the biasing device, a high degree of precision is
achieved in the local diametral expansion.
-
Figs. 6 to 15 show another embodiment of the present invention. The
illustrated apparatus 101 is provided with a stand 102 on a floor, a driver
section 103 mounted on the stand 102 driven by a driving unit 104, a driven
rotary section 105 located opposite supported by a slidable framework 106 and a
rotary framework 107, a biasing device 108 provided between the framework 106
and the rotary framework 107 to cause the work (W) to become biased, and a
pressing device 109 provided in the rear end of the driven rotary section 105.
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The stand 102 includes pillars 111 erected on plates 110, and frames 112
arranged in parallel along the length of the apparatus on the top of the pillars
1 11, a driving means mount 113 in and between front ends of the frames 112, a
driving rotary section mount 114 in its rear end, and a nut 115 for slidable use
in the rear end of the mount 114.
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The driver section 103 includes an outer sleeve 116 in which an inner
sleeve 117 is rotatably carried. The inner sleeve 117 has female threads on
its inside wall which is tapered at α° at the end. The inner sleeve 117 houses
a pair of chucks 118 for holding the work (W). The chuck 118 is made by
splitting one body into a plurality of chuck pieces, each of which is tapered
at α°. A hollow core 119 is inserted in the inner sleeve 117 such that it can
push the inner sleeve by a hollow bolt 120. By fastening the bolt 120, the
chucks 118 are moved by the core 119, so that the tapered top ends of the chucks
118 are restricted to press the work (W).
-
The driving unit 104 includes a driven gear 121 in the front end of the
inner sleeve 117, and the driving means mount 113 includes a motor 122 whose
output shaft having a thread 123 engaged with the driven gear 121.
-
Opposite the driver section is 103 provided a driven rotary section 105 secured
to the rotary framework 107, which is provided on the framework 106 arranged
between the frames 112.
-
The framework 106 is provided with a feeder 124 designed to cause the
driven rotary section 105 to approach or separate from the driver section 103.
The feeder 124 is provided with a pair of bearings 125 and 126 on opposite ends
between which a feed screw 127 is carried in engagement with a nut 115 provided
on the stand 102. The feeder screw 127 is rotatable in either direction,
thereby causing the framework 106 to move along the length of the apparatus.
The rear end of the feeder screw 127 is connected to an output shaft of a motor
128 provided on the framework 106. The energization of the motor 128 drives
the feeder screw 127.
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The biasing device 108, designed to cause the work (W) to become biased
with respect to its axis, rotates the rotary framework 107, which is integral
with the driven rotary section 105, in a horizontal plane on the top surface of
the frames 112. The biasing device 108 includes a pivot 107a in a bore 106a
produced in the framework 106 such that the rotary framework is rotatable around
the pivot 107a. A nut 129 is fitted in an opening 106b in the rear end of the
framework 106, and a motor 131 is provided on a bracket 130 secured to the
rotary framework 107. The output shaft of the motor 131 is provided with a
thread portion 132 which is engaged with he nut 129. The rotation of the motor
131 in either direction causes the thread portion 132 to rotate in a clockwise
or anti-clockwise direction. Since the nut 129 is rotatably connected to the
framework 106, the nut 129 does not move, and the thread portion 132 rotates the
rotary framework 107. In this way the driven rotary section 105 rotates in a
horizontal plane around the pivot 107a. The biasing device 108 is not limited
to this embodiment, but can be a version in which the driven rotary section 105
is rotatable around the pivot 107a under a linkage pressing system or a fluid
cylinder, thereby applying force to the work (W) at right angle to its axis,
thereby causing the work to become biased.
-
The driven rotary section 105, secured to the upper part of the rotary
frame 107, includes an outer sleeve 133 in which an inner sleeve 134 having an
inside space 134a is rotatably housed. The inner sleeve 134 has an inside wall
tapered at β° at its front end. The inner sleeve 134 houses chucks 135 for
holding the work (W). The chucks 135 are produced by splitting a hollow
cylinder into a plurality of chuck pieces whose outsides are tapered at β°.
The chuck pieces are compressed by the pressing device 109, thereby holding the
work (W) in a restricted space 134a.
-
The number of split chuck 118 pieces can be two as shown in Fig. 12 or three as
shown in Fig. 13.
-
The pressing device 109, provided in the rear end of the driven rotary
section 105 to push the driven rotary section 105 toward the driver rotary
section 103 by means of a hydraulic cylinder 136 provided on the rotary
framework 107. The hydraulic cylinder 136, designed to push the holder 134
toward the driver rotary section 103, has a piston rod 136a engaged with an
inner bearing 137 around which an outer bearing 138 is provided in engagement
with the inner sleeve 134, so as to avoid transmitting the rotation of the
inner sleeve 134 to the piston rod 136a. As alternatives of the pressing device
109, a hydraulic jack or a fluid cylinder can be employed.
-
No controller for the motors 122, 128, 131 and the hydraulic cylinder 136 is
illustrated in the drawings, but it can be designed to optionally set the
rotations per minute of each motor and a pressure provided by the cylinder.
The angle of the biasing device can be adjusted as desired.
-
Instead of constructing the biasing device such that it rotates the work
in a horizontal plane, the rotary pivot is constructed such that it vertically
rotates around the horizontal axis perpendicular to the work (W), thereby
enabling an operator to inspect the state of the diametral expansion in progress
from the side of the apparatus.
-
In making a desired local diametral expansion by using the apparatus
101, the driver rotary section 103 and the driven rotary section 105 are
arranged such that the inner sleeves 117 and 134 are aligned. The work (W) is
inserted between the chucks 118 opened by loosening the hollow bolt 120 to
expand the chucks 118. Then the target portion for the local diametral
expansion is specified by placing that portion flush with the end face of the
chucks, followed by fastening the bolt 120 to hold the work (W) in the chucks
118. Then, the feeder 124 is operated to move the driven rotary section 105
toward the driver rotary section 103, and allows the work (W) to become held by
its chucks 135, wherein the driver rotary section 103 and the driven rotary
section 195 are appropriately spaced. Then the motor 112 is operated to rotate
the inner sleeve 117, thereby causing the work (W) held by the chucks 118 to
rotate. The driven chucks 135 are also rotated. The work (W) is axially
pressured by the pressing device 109, and the driven rotary section 105 becomes
biased by the biasing device 108 as shown in Fig. 14. In this way, when both
the pressing device 109 and the biasing device 108 are put into operation, the
work (W) held by the chucks 118 and 135 are rotated and compressed in its bent
position. The rotating speed can be a few tens of times per minute, and the
bending angle can be 3° to 7°. The amplitude of pressure depends upon the
diameter of the work. In general, a local diametral expansion is possible with
a pressure equal to about 20% to 30% of the stress at which a single metal shaft
reaches a yield point as taught in Technical Reports entitled "Study on
Diametral Expansion of a Bar" (Vol. 34 by Nih'hama Technical Academy).
-
In this way the work (W) is subjected to rotation, bending, and pressuring
between the chucks 118 and 135, thereby effecting a local diametral expansion of
this part of the work. As the local diametral expansion advances, the distance
between the chucks 118 and 135 becomes short while the work is constantly
subjected to pressuring. If the pressure is reduced at this moment, the
outside and the inside around the bent portion are alternately subjected to
bending and straightening, thereby resulting in the breakdown of the work (W).
After the desired local diametral expansion is finished, the biasing device 108
is returned to its original position (i.e. where the rotary sections 103 and 105
are aligned) while the rotation and pressuring are repeated. As a result, the
work (W) having a diametrically expanded portion is obtained as shown in Fig.
15. Finally, the rotation and compression are stopped, and the work (W) is
taken out of the chucks 135.
-
Figs. 16 to 22 show a further preferred embodiment of the present
invention. The illustrated apparatus 201 is provided with a stand 202 on a
floor on which pillars 203 are erected to support a rectangular framework 204.
A driving rotary section 205 is mounted on the front part of the framework 204
(the left-hand part in Fig. 16), and a mount 207 for a slidable pressing device
206 is fixed to the rear part of the framework 204. The framework 204 includes
grooves 208a on opposite side 208.
The driven rotary section 205 includes a cylindrical sleeve 211 rotatably
supported on a sleeve body 210 secured to a member 209 of the framework 204,
the sleeve 211 being provided with a follower gear 212. The sleeve 211 houses
chucks 213 designed to hold a work (W). The sleeve 211 and the chucks 213 are
provided with tapered portions for the same reason referred to above.
-
A motor 214 is provided in a lower part of the sleeve 211 as a power source
for rotating the work (W), having an output shaft being provided with a gear
215 engaged with the follower gear 212.
-
A slidable framework 216 moves toward and away from the driving rotary
section 205, as the case may be. The framework 216 is substantially
rectangular, and its side frames 217 are provided with projections to be fitted
in the groove 208a of the frame 204. Between the side frames 217 is provided
an intermediate member 218 with an inside space 218a. The frame 204 is slid by
a double-acting hydraulic cylinder 219 provided between the mount 207 and the
intermediate member 218. The hydraulic cylinder 219 is supported by a holder
220 secured to the slidable framework 216. The contraction and expansion of
the hydraulic cylinder 219 cause the framework 216 to move to and fro along the
length of the apparatus 201.
-
On top of the framework 216 is a rotary framework 221, which secures a pair
of rails 224 provided with a groove 224. The rails 224 are provided with a
hydraulic cylinder 227 at their rear ends through a mount 228, which functions
as a pressing device 226 for a driven rotary section 225, hereinafter referred
to. The rotary framework 221 is rotatably connected to the slidable framework
216.
-
The driven rotary section 225 is located opposite the driving rotary
section 205 on the framework 221. The driven rotary section 225 has the same
construction as the driving rotary section 205, wherein like reference numerals
denote like components. The sleeve 210 of the driven rotary section 225 is
slidable along the rails 224 on the framework 221 through engagement of a
projection of a member 229 in the grooves 224a. A hydraulic cylinder 227 as the
pressing device 226 is provided. The contraction and expansion of the cylinder
227 causes the driven rotary section 225 to move to and fro along the length of
the apparatus.
-
In this embodiment the hydraulic cylinder is employed for a pressing device
but instead of it, a screw type feed system can be used.
-
The reference numeral 230 denotes a biasing device 230 which includes a
member 231 rotatably fitted in an inside space 220a of the holder 220 in the
framework 216, ad a nut 22 rotatable in an inside space 224b produced in the
rails 224 with the additional provision of a motor 233 whose output shaft is
provided with a male thread portion 234 engaged with the nut 232. The rotation
of the motor 233 in either direction causes the male thread portion 234 to
rotate, followed by the movement of the nut 232. In this way the rotary
framework 221 is rotated around a pivot 223, thereby causing the driven rotary
section 225 on the rotary framework 221 to rotate.
-
No controller is illustrated in the drawings for the motors 214 and 233 and
the hydraulic cylinder 219, 227. However, these motors 214, 233 are designed to
control their clockwise or anti-clockwise rotations on their own, and the
hydraulic cylinders 219, 227 to control the amount of their movement on their
own.
-
In this embodiment the work (W) is rotated through the driving rotary
section 205 driven by the motor 214. The driven rotary section 225 is caused
to move toward and away from the driving rotary section while being biased by
the biasing device 230 with respect to the axis of the driving rotary section
205. When the pivot 223 approaches the driving rotary section 205, the driven
rotary section 225 is caused to approach the pivot 223 by the second pressing
device 226. This means that the axis of the pivot 223 can be appropriately
located between the two chucks 213 of the holders 205 and 225 by adjusting the
sliding distance of the pressing devices 206 and 226.
-
In this embodiment the operation of the apparatus 201 is initiated by
aligning the two rotary sections 205 and 225. Then, the work (W) is inserted
between the chucks 213 in the holders 205 and 225. The motor 214 is energized
to rotate the work (W). The pressing devices 206 and 226 are operated to
compress the work (W), and biasing device 230 is operated to bend it, wherein
the compressive force is such that no pull occurs around the bent portion or at
least a load to the work (W). If the compressive force is weak, the work (W) is
subjected to repeated compression and extension, and is finally liable to
fracture. A desired local diametral expansion of the work (W) is finished, the
rotary sections 205 and 225 are aligned by the biasing device 230 while the
compression and rotation are continued so as to straighten up the work.
Finally, the work (W) is taken out of the holders 213 by contracting either of
the pressing device 206 or 226.
-
As shown in Fig. 20, the driven rotary section 225 approaches the driving
rotary section 205 by the pressing device 206 which causes the framework 216 to
approach the driving rotary section 205. Furthermore, the driven rotary
section 225 approaches the pivot 223 by the framework 221 by the pressing device
226. This means that the approach of the driven rotary section 225 to the pivot
223 causes the driven rotary section 225 to approach the pivot 223. In this
way the axis of the pivot 223 as the point of bend is located in the middle
between the chucks 213. This ensures that the local diametral expansion of the
work occurs in the middle between the chucks 213. This prevents the loss of
the expanding force.
-
Figs. 21 and 22 show a further preferred embodiment, where, instead of the
driving rotary section 205 secured to the framework 204, the intermediate member
218 for the pivot 223 is secured to the framework 204, and the framework 221 is
rotatably connected to the intermediate member 218. In addition, the driven
rotary section 225 is arranged to move toward and away from the pivot 223 on the
rotary framework 221, and the slidable framework 216 is constructed to move
toward and away from the pivot 223 along the sides 208 of the framework 204,
and the driving rotary section is secured to the slidable framework 216. In
this embodiment the axis of the pivot 223 is adequately located between the
chucks 213 by adjusting a distance over which the pressing devices 206 and 226
have slid. Figs 21 and 22 like reference numerals designate like elements and
components to those of the above-mentioned embodiments, and therefore, a
description will be omitted for simplicity.
-
When the sliding distances of the pressing devices 206 and 226 are
equalized, the axis of the pivot as the point of bend is advantageously located
in the middle between the chucks 213 for effecting a diametral expansion of a
metal shaft.
-
Figs. 23 to 29 show a still further preferred embodiment. The illustrated
apparatus 301 is provided with stands 302 on which pillars 303 are erected to
support a rectangular framework 304. A groove 305a is provided between the
opposite sides 305 of the framework 304 along the length of the apparatus 301.
The framework 304 is provided with a motor mount 306 and a front bracket 307 in
its front section, and a rear bracket 308 in its rear section. The reference
numerals 309 designate reinforcements.
-
Between the sides 305 are arranged a slidable framework 310 and a sliding
device 311 for causing the framework 310 to slide along the length of the
apparatus 301. The slidable framework 310 includes side frames 312 having a
projection 312a fitted in the groove 305a, and an intermediate member 313 having
an opening 313a vertically formed and a support 314 for the sliding device 311.
-
The sliding device 311 is provided in the form of a double-acting hydraulic
cylinder 315 on the side of the intermediate member 313. The hydraulic cylinder
315 is supported by the support 314, and is secured to the rear bracket 308.
In this way the extension and contraction of the hydraulic cylinder 315 cause
the slidable framework 310 to slide along the length of the apparatus 301. The
hydraulic cylinder 315 can be substituted by other suitable means such as a
screw-base system feeder.
-
A rotary framework 316 is carried on the slidable framework 310. The
rotary framework 316 includes a plate member 317, and a rotary pivot 318
rotatably fitted in the inside space 313a. A biasing device 319 is provided in
a rear section of the rotary framework 316. The biasing device 319 includes a
plate 320 in which inside spaces 320a are produced to accept shafts 321a, with
a feed nut 321 having a female thread 321b inside.
-
The slidable framework 310 includes an inside space 312b in its sides 312
in which a mount 322 is provided on which a motor 323 is mounted. The motor 323
has an output shaft is provided with a male thread 324 engaged with the feed
nut 321. In this way the rotation of the motor 323 in either direction causes
the feeder nut 321 to move toward and away from the motor 323 whereby the rotary
framework 316 is rotated around the pivot 318.
-
Rotors 325 and 326 are aligned on the front bracket 307 and the plate
member 317. Each of the rotors 325 and 326 includes a rotable inner sleeve 329
in an outer sleeve 328. The inner sleeve 329 is provided with the tapered
portion on the inside wall with which chucks 331 are engaged. The chucks 331
are formed by splitting a sleeve member having a tapered portion matching with
that of the inner sleeve 329 into several chuck pieces.
-
A driving device 332 is provided to drive a holder 330 of the rotor 325,
the driving device including a follower gear 333 in the inner sleeve 329. The
inner sleeve 329 of the other rotor 326 has a similar follower gear 333. There
is provided a motor 334 whose output shaft is provided with a driving gear 335
engageable with the follower gear 333 so as to transmit a torque to the rotor
325. The torque transmitted to the follower gear 333 is transmitted to the
rotor 326 through a transmission 336, which includes metals 337 secured to the
outer sleeves 328, and brackets 338 rotatably fitted in an inside space 307a
produced in a front framework 307 of a framework 304 and an inside space 317a in
the plate member 317 of the rotary framework 316. The bracket 338 is provided
with bearings 338b which carry a pair of splines 339 having teeth 340 engaged
with the follower gears 333. The transmission 336 transmits a torque of the
rotor 326 to the other rotor 325 as the former moves in either direction or is
biased, through engagement of the follower gears 333 and gears 340.
-
No controller for the hydraulic cylinder 315, the motors 323 of the biasing
device 319, and the motor 332 for driving the apparatus is illustrated in the
drawings but any other controlling means can be employed singly or in
combination if it can start and stop them as desired.
-
In this embodiment a single driving force is transmitted to the rotors 325
and 326 but a modified version as shown in Fig. 30 is also possible in which a
motor 341 is provided on the rotary framework 316, with its output shaft having
a driving gear 342. The driving gear 342 is engaged with the follower gear 333,
and the motors 334 and 341 are controlled by a controller (not shown), thereby
effecting the synchronous rotation of the rotors 325 and 326.
-
Referring to Fig. 31, the procedure for performing the diametral expansion
of a shaft by using this embodiment will be described:
-
The chucks 331 are aligned and a work (W) is inserted between them. The
chucks 331 firmly holds the work (W) under the tapered structure of the inner
sleeve 329. The distance between the chucks 331 is maintained at D. Then the
motor 334 is energized to cause the work (W) to rotate around its axis, and the
rotor 326 is caused to approach the rotor 325 until a compressive force P is
applied to the work (W). At this stage, the bracket 338 of the transmission
336 is caused to approach the other bracket in accordance with the sliding of
the slidable framework 310, thereby shortening the distance of the two brackets.
The spline 339 is also shortened, wherein the rotors synchronously rotate
because of engagement of the gears 340 with the follower gears 333, as shown in
Fig. 31(a).
-
Subsequently, the biasing device 319; that is, the motor 323 is energized
to rotate the male thread 324 so as to disengage the feeder nut 321 from it,
thereby allowing the rotary framework to rotate around the pivot 318. In this
way the rotor 326 secured to the rotary framework 316 is rotated in a biased
position with respect to the axis of the rotor 325. The brackets 338 of the
rotors 325 and 326 are rotated such that the axes of the bearings 338a are
aligned, and because of the constant engagement of the follower gear 333 with
the gear 340, the synchronous rotation of the rotors 325 and 326 is maintained
as shown in Fig. 31(b).
-
While the work (W) is rotated, a bulged portion in the work gradually grows
around the periphery of it and finally becomes diametrically expanded as
desired. The distance between the chucks 331 is shortened, and the compressive
force diminishes. As it becomes smaller than a pull occurring outside the bent
portion of the work (W), it is subjected to straightening, and is liable to
breakage. To avoid the breakage, the work is kept under the compression (Fig.
31(c)).
-
Upon the achievement of the desired diametral expansion the motor 323 is
reversibly rotated, and the chucks 331 are aligned so as to straighten the work
(W) under the continued compressive force P. In this condition the work is
rotated several times, thus obtaining a straightened work. Then the rotation
and application of the compressive force are stopped, and the work is taken out
by separating the rotor 325 from the rotor 326 or vice versa by the hydraulic
cylinder 315. The work (W) is readily released from the chucks 331, as shown in
Fig. 31(d)).
-
Figs. 32 to 36 show another preferred embodiment in which a lathe is
employed. A diametrically expanding apparatus 401 is connected to a lathe (M)
(not shown in Figs. 32 to 35) through a structure in which a base plate 403 is
provided for supporting a tapered shaft 402 designed to receive a tail stock of
the lathe (M). The base plate 403 consists mainly of parallel side frames 404
along the length of the apparatus, and a front transverse frame 405 and a rear
transverse frame 406. An outer sleeve 408 is secured to the front transverse
frame 405 for supporting a driving rotary section 407, and the tapered shaft
402 is secured to the rear transverse frame 406 in alignment with the tapered
shaft 402. A pressing device 409 is supported on a mount 410 secured to the rear
transverse frame 406.
-
The driving rotary section 407 consists of an arrangement in which an inner
sleeve 411 rotatably carried in the outer sleeve 408. The inner sleeve 411
houses chuck sleeves 412 for holding a work (W) in a space whose side wall is
tapered at α°. The inner sleeve 114 is provided with a male thread
engageable with a female thread of a ring 413, wherein the engagement of the
threads prevents the inner sleeve 411 from deviation along the length of the
apparatus. The front part of the apparatus mentioned above is connected to a
chuck (T) of the lathe (M) so as to transmit a torque of the lathe (M) to the
driving rotary section 407. In order to secure the transmission of the torque,
the front end of the inner sleeve 411 is made multi-angular in accordance with
the number of pawls of the lathe chuck; in the illustrated example, triangular
in accordance with the three pawls. A cornered shape is effective to transmit a
torque with the minimum loss.
-
The chuck sleeves 412 includes an inside space 412a in which the work (W)
is placed, and it is split into several chuck pieces so as to hold the work (W)
among them. After the work (W) is inserted into the chuck pieces, it is secured
by the nut 414 at its rear section. More specifically, the chuck sleeves 412
are pushed backward along the tapered angle at α° by being tightened by the
nut, and the space surrounded by them is restricted to hold the work (W).
-
A driven rotary section 415 is located opposite the driving rotary section
407, and is rotatably mounted on the slidable framework 416 so as to rotate
vertically. The slidable framework 416 slides on the side frame 404 along the
length of the apparatus. The slidable framework 416 includes slide members 418
secured to side frames 417 between which a front transverse frame 419 and a
rear transverse frame 420 are arranged. More specifically, the slidable
framework 416 has a sliding surface in the outside of the side frame 417 and the
bottom surface of the sliding member 418, and slides along the side frame 404
of the base plate 403.
-
The driven rotary section 415 includes an outer sleeve 422 in which an
inner sleeve 423 is rotatably carried, the outer sleeve 422 having a pivot 421.
The inner sleeve 423 is provided with a male thread in its rear section, and an
inside space 423a having a side tapered at β°. The inside space 423a houses
chuck sleeves 424 and a sleeve 425. The chuck sleeves 424 are pushed forward by
tightening the nut 426 provided in a rear section, so that the chuck sleeves are
split into several chuck pieces among which the work (W) is held.
-
A hydraulic cylinder 427 as a pressing device 409 is provided between the
mount 410 of the base plate 403 and the front transverse frame 419 of the
slidable framework 416. No controller for regulating the hydraulic cylinder or
no switch are illustrated. When the work (W) is to be compressed held by the
driving rotary section 407 and the driven rotary section 415, the hydraulic
cylinder 427 is extended so as to shorten the distance between them. A
repulsive force involved in the compression is set off in the base frame, so
that no load is applied to the lathe (M). Instead of the single-acting cylinder,
a double-acting cylinder can be employed, which enable the finished work (W) to
be readily taken out of the apparatus.
-
The driven rotary section 415 is provided with a biasing device 428 for
biasing the work (W). The biasing device 428 includes a bracket 429 in which an
inside space 429a receives a rotating shaft 430 having a female thread. The
rotating shaft 430 has a threaded rod 432 provided with a handle 431. The
threaded rod 430 is rotated by the handle 431. At this stage, because of the
abutment of the lower end of the threaded rod 432 with the top surface of the
rear transverse frame 420 the threaded rod 432 is prevented from upward and
downward movement but the rotary shaft 430 is caused to move up or down
together with the outer sleeve 422. In this way the driven rotary section 415
is vertically rotated around the pivot 421.
-
The
apparatus 401 is operated as follows:
- The inner sleeve 411 of the driving rotary section 407 is connected to the
chuck (T) of the lathe (M). At the same time, the tapered shaft 402 is connected
to the tail stock of the lathe (M).
- Subsequently, the driving rotary section 407 and the driven rotary section
415 are aligned, thereby setting the biasing device 428 free. The work (W) is
inserted between the chuck sleeves 412 and 424 spaced at a predetermined
distance (D). The work (W) is firmly held by tightening the nuts 414 and 426.
-
-
The lathe (M) is driven to operate the hydraulic cylinder 427 so as to
rotate the work (W) and compress it between the chuck sleeves 412 and 424.
-
While the work (W) is subjected to rotation and compression, the handle 431
is operated to rotate the driven rotary section 415. At this stage, the
distance (D) is shortened, and therefore, the diametral expansion advances. The
continued compression is effective to protect the work (W) from breaking owning
to bending back. When a desired diametral expansion is finished, the rotary
sections 407 and 415 are returned to a position where they are aligned under
the maintained rotation and compression. When the work (W) is straightened up,
the rotation and compression are stopped, followed by the withdrawal of the
work (W).
-
In this embodiment, the torque is given by a lathe which is protected from
an unfavorable repulsive force of the compression. This ensures that all-purpose
lathes can be employed.
-
In the embodiments referred to above the work (W) is a solid metal shaft
but it can be hollow like a pipe. Now, referring to Figs. 37 to 44, the
diametral expansion of a metal pipe will be described:
-
In general, if a machine or a device must be partly be elastic or hermetic,
expansion joints or bellows for flexible pipes are used. A process for making
bellows is known in the art; one example is described in Japanese Patent
Publication 3-42969 which teaches the method of injecting a bulged fluid
pressure into a metal pipe. As the internal pressure is increased, the pipe is
expanded in accordance with the contour of the mold. However, a disadvantage is
that the expanded wall becomes thin. The present invention is directed to
diametrically expand metal pipes without reducing the thickness of the expanded
portion.
-
A work (W) is held by a pair of rotary holders aligned at a distance (D).
The rotary holders are similar in structure to a chuck of a lathe. If the work
(W) is short, a chuck sleeve which can compress one end of the work (W) is used.
-
The distance (D) can be varied between a few tens of millimeters and a few
hundreds of millimeters.
-
In this situation at least one of the rotary holders is rotated to rotate
the work (W). The rotating speed depends upon the material and the size of the
work, covering a few to a few hundreds of rotations per minute. If the speed
is slow, the diametral expansion takes time, and if it is too fast, it is
difficult to follow pressure to a plastic deformation, thereby resulting in the
possibility of breakage due to fatigue.
-
Then the work (W) in rotation is subjected to compression, which is applied
in a known manner such as a hydraulic jack or a hydraulic cylinder. The
strength of the compressive force depends upon the material, the diameter, and
the thickness of the work (W). However, in this embodiment the compressive force
can be smaller than that required in the bulge process.
-
While the work (W) is subjected to rotation and compression, it is bent by
biasing one of the holders with respect to the axis of the other holder. As a
result, the work (W) is bent while being in rotation. The angle of bend is a few
to a few tens of angle; if it is too small, a desired diametral expansion is
not obtainable. If it is too large, the work (W) is likely to become damaged.
-
If the work (W) is bent while it is in rotation, a large compressive force
acts upon the inside of the bent portion, thereby causing plastic deformation to
arise there. Because of the plastic deformation, the work (W) deforms in a
direction in which the compressive force escapes; that is, the work (W)
diametrically expands. Because of the rotation the plastic deformation spreads
around the periphery of the work (W). At this stage it is important to apply a
compressive force to outside the bent portion. If a pull acts upon this outside
of the work (W), the work (W) is alternately subjected to extension and
contraction, and finally fractures owing to fatigue. As the work (W)
diametrically expands, the distance (D) between the holders becomes short.
Accordingly, the pressure is constantly applied to one of the holders to move
toward the other holder, so as to continue to apply the compressive force to
the periphery of the work (W). In this way, because the work (W) is subjected to
compression and bending while it is in rotation, the compressive force can be
smaller than that required in the bulge process.
-
After the desired diametral expansion is finished, the work (W) is
straightened up by returning the rotary holders until they are aligned again
under the continued compression applied inside and outside the bent portion. If
the compression is reduced, the work (W) is liable to fracture owing to
expansion and contraction. After the straightening is finished, the
application of the compressive force is stopped, followed by the withdrawal of
it.
-
Because of the rotation and bending applied to the work (W) while being
subjected to compression axially applied to the work (W), it becomes shorter
than before the diametral expansion is performed. This means that the shortened
portion is absorbed in the expanded part, thereby increasing the thickness of
the expanded metal flesh. This is advantageous over the bulge processed pipes.
-
Referring to Figs. 37 to 44, the illustrated apparatus 501 includes a pair
of side walls 503 erected on base plates 502 on the floor, and a rectangular
framework 504 which is provided with a driving rotary holder 505.
-
The driving rotary holder 505 includes an inner sleeve 507 rotatable in an
outer sleeve 506 secured to a member 505a of the framework 504. The inner sleeve
507 is provided with a driven rotary gear 508 at its rear end, and houses chuck
sleeve 509 for holding a work (W) in an inside space 509a axially produced.
The chuck sleeve 509 is provided with a slit portion 509b which is tightened by
a bolt 511 through a fastener 510. In this way the work (W) is firmly held in
the chuck sleeve.
-
A motor 512 is provided under the rotary holder 506, having its output
shaft provided with a driving gear 513 engaged with the driven gear 508.
-
Opposite the driving rotary holder 505 is provided a driven rotary holder
514 which includes a slider 516 slidable along rails 515 on the framework 504.
A ring-shaped rotary framework 517 is rotatably connected to the slider 516 by a
pivot 518. The ring-shaped rotary framework 517 is secured to an outer sleeve
519 in which an inner sleeve 520 is rotatably housed. The inner sleeve 520
houses a chuck sleeve 521, which has the same structure as the chuck sleeve 509,
includes an inside space 521a axially produced to receive the work (W). The
work (W) in the inside space 521a is firmly held by narrowing a slit portion
521b which is tightened by a fastener 522.
-
The slider 516 is provided with a feeder 523 designed to move the driven
rotary section 514 toward and away from the driving rotary section 505. The
slider 516 is provided with a bracket 524 in its rear end on which a bearing 525
is provided. The framework 504A is provided with an opening 526 in its rear
transverse frame 526, and a sleeve 527 secured in its front end. The sleeve 527
is provided with a slit 527a through which a projection 528a of a shifter block
528 is extruded. The shifter block 528 is caused to move to and fro along the
length of the apparatus 501.
-
A feeder rod 529 is rotatably carried by the bearing 525 and the transverse
frame 526. The feeder rod 529 is provided with a male thread portion on its
periphery with which the shifter block 528 is engaged. The feeder rod 529 is
provided with a stop ring 530 at its front end to prevent it from slipping off,
and a handle 531 in its rear end.
-
Below the driven rotary section 514 is provided a pressing device 514,
which causes the driven rotary section 514 to move toward the driving rotary
section 505, in the form of a hydraulic jack 533 provided on the base plate
502. A cam 535 is rotatably supported on the hydraulic jack 533 such that it
can vertically rotate by means of a pivot 534. The cam 535 includes an engager
535a engageable with the rear portion of the slider 516, and a receiver 536 to
receive an upward urge of the jack by coming into abutment with a piston rod of
the jack 533.
-
A biasing device 537 is provided on the driven rotary section 514 so as to
effect the up and down movement of it. The biasing device 537 includes a nut 538
secured to the outer sleeve 519, and a threaded rod 539 engaged with the nut
538. The threaded rod 539 is placed in abutment with the slider 516 it its lower
end, and is provided with a handle 540 in its upper end. The rotation of the
handle 540 causes the threaded rod 539 to rotate, but because of abutment of
its lower end with the top surface of the slider 516 the threaded rod 539 does
not move up or down, and the nut 538 engaged with it moves up and down together
with the outer sleeve 519. In this way the driven rotary section is caused to
rotate vertically.
-
In operation, the two rotary sections 505 and 514 are arranged such that
the respective holders 507 and 520 are aligned, which means that the biasing
device is prevented from its biasing work. A work (W) is held between the
chuck sleeves 509 and 521 wherein a target portion for the desired diametral
expansion is placed in agreement with the rear end of the chuck sleeve 509, and
the a fixing member 510 is arranged at a position of the slit 509b. Then the
work (W) is firmly held by tightening the chuck sleeve 509 with the nut 511.
-
The chuck sleeves 509 and 521. are positioned at a predetermined distance
(D). This distance (D) is based on a calculation that a desired diametral
expansion is achieved. To adjust the distance (D), the handle 531 is operated
to cause the shifter block 528 to move backward until its projection 528a comes
into abutment with the rear end of the slit 527a, and is further operated to
cause the feeder rod 529 to advance gradually. As the top end of the feeder rod
529 is connected to the slider 516, the driven rotary section 514 is advanced
along the rails 515 until the desired distance (D) is reached, where the fastner
522 is fitted in the slit 521b in the chuck sleeve of the driving rotary
section to hold the work (W).
-
Subsequently, the pressing device 532 is operated to axially compress the
work (W), and the motor 512 is operated. The compression is effected by
operating the hydraulic jack 533 and rotating the cam 533 in the direction
indicated by the arrow (Fig. 39). The energization of the motor 512 causes the
work (W) held by the chuck sleeves 509 and 521 to rotate. In this way, the work
(W) is subjected to compression while in rotation. The rotating speed can be a
few to a few tens of rotations per minute. Then, the biasing device 537 is
operated to bend the work (W) at an angle of 3 ° to 7 ° .
-
Experimentally, this embodiment was applied to a carbon steel pipe having
an outside diameter of 22.2mm, and a thickness of 1.6mm so as to expand the
diameter of a middle portion of it up to 27mm covering a width of 7mm around
the periphery. As a result, it has been ascertained from this experiment that
the rotating speed is 4 rotations per minute, the angle of bend is 6 ° , and the
compression is 1 to 2 tons.
-
As is evident from the foregoing description, the work (W) is diametrically
expanded between the chuck sleeves 509 and 521 by being subjected to
compression, rotation, and bending. As the process advances, the original
distance (D) is shortened but the compression continues. If it is stopped, the
work (W) is subjected to detrimental repetition of bending and straightening,
and is liable to fracture. After the desired diametral expansion is finished,
the biasing device is returned to its original position so as to straighten up
the bent portion in the work (W) under the constant compression. Then the
rotation and compression are stopped, and the finished work (W) is taken out of
the apparatus.
-
Initially the work (W) is loosely held between the chuck sleeves 509 and
521 but as the rotation, bending and compression advance, the diametrically
expanded portion is tightly held by the chuck sleeves 509 and 521, thereby
making it difficult to take the work out of the apparatus. Therefore, the
withdrawal of the work (W) is helped by the hydraulic jack 533 in a manner in
which it is slid backward, and the cam 535 is lowered in the opposite direction
to the arrow direction (Fig. 39). The fastener 522 is unfastened, and the
driving rotary section 505 is separated from the driven rotary section 514 to
release the work (W). A pin 541 is drawn , and the frame 504 and the transverse
frame 526 are released so as to allow the driven rotary section 514 to slide
backward until the work (W) is released. Finally, the fixing member 510 is
unfastened, and the work (W) is withdrawn from the driving rotary section 505.
-
Advantages of the Present Invention
-
The present invention makes it easy to diametrically expand a metal shaft
or pipe, whichever it is solid or hollow. Gears and cams can be readily
provided in a desired portion of metal shafts without welding or mass-cutting.
The production of mechanical power transmissions is facilitated.