Field of the Invention
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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
[0022]
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
[0023] Referring to Figs 1a, 1b, 1c and 1d, respectively, the principle underlying the present
invention will be described:
[0024] 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.
[0025] 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.
[0026] 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.
[0027] Referring to Figs. 2 to 5, a first preferred embodiment of the present invention
will be more particularly described:
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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).
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] The work (W) is withdrawn out of the holders simply by loosening the nut 22.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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).
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] The number of split chuck 118 pieces can be two as shown in Fig. 12 or three as shown
in Fig. 13.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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 θ 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).
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] In this embodiment the hydraulic cylinder is employed for a pressing device but instead
of it, a screw type feed system can be used.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] Referring to Fig. 31, the procedure for performing the diametral expansion of a shaft
by using this embodiment will be described:
[0080] 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).
[0081] 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).
[0082] 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)).
[0083] 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)).
[0084] 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.
[0085] 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.
[0086] 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).
[0087] 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.
[0088] 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.
[0089] 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.
[0090] 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.
[0091] 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.
[0092] 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.
[0093] 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).
[0094] 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.
[0095] 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:
[0096] 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.
[0097] 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.
[0098] The distance (D) can be varied between a few tens of millimeters and a few hundreds
of millimeters.
[0099] 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.
[0100] 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.
[0101] 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.
[0102] 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.
[0103] 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.
[0104] 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.
[0105] 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.
[0106] 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.
[0107] 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.
[0108] 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.
[0109] 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.
[0110] 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.
[0111] 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.
[0112] 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.
[0113] 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.
[0114] 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).
[0115] 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 °
.
[0116] 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.
[0117] 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.
[0118] 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.
[0119] Advantages of the Present Invention
[0120] 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.
1. A method for diametrically expanding a metal shaft, comprising 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.
2. The method according to claim 1, wherein the compression is relatively low at the
initial stage of the diametral expansion, and progressively increases as the diametral
expansion advances.
3. An apparatus for diametrically expanding a metal shaft, comprising:
a driving rotary section (4) and a driven rotary section (6) arranged at a predetermined
distance, each of the rotary sections comprising holders for securing a work between
them;
a driver (5) for operating the driving rotary section (4);
a pressing device (8) for axially compressing the work held by the holders; and
a biasing device (7) for declining the axis of the work;
wherein the pressing device (8) applies the compression to one of the rotary sections
(4) and (6), and the biasing device (7) declining the other rotary section (4) or
(6).
4. An apparatus for diametrically expanding a a metal shaft, comprising:
a driving rotary section (103) and a driven rotary section (105) arranged at a predetermined
distance, each of the rotary sections comprising holders for securing a work therebetween;
a driver (104) for operating the driving rotary section (103);
a pressing device (109) for axially compressing the work held by the holders;and
a biasing device (108) for declining the axis of the work;
wherein either the driving rotary section (103) or the driven rotary section (105)
is arranged rotatably around a pivot (107a) provided in a direction perpendicular
to the axis of the work, and the rotatably arranged rotary section is supported by
the pivot (107a) so as to enable the simultaneous inspection of the inner and outer
sides of the bent portion of the work.
5. The apparatus according to claim 4, further comprising a slidable frame (106) provided
on the base plate (102), and a rotary framework (107) rotatably connected to the slidable
frame (106) through a bearing, and wherein the driving rotary section (103) is secured
to the base plate (102) and the driven rotary section (105) is secured to the rotary
framework (107).
6. An apparatus for diametrically expanding a metal shaft, comprising:
a driving rotary section (205) and a driven rotary section (225) arranged opposite
each other, each of the rotary sections comprising holders for securing a work between
them;
a driver (214) for rotating the work held by the holders around its axis;
a first slidable pressing device (206) for causing the driven rotary section (225)
to move toward and away from the driving rotary section (203);
a biasing device (230) for rotating the driven rotary section so as to decline with
respect to the axis of the holder of the driving rotary section;
a second slidable pressing device (226) for shifting the axis of a pivot rotated by
the biasing device (23) toward and away from the driving rotary section; and
a displacing device for shifting the center of rotation between the holders in accordance
with a sliding distance covered by each of the first pressing devices (206) and the
second pressing device (226).
7. An apparatus for diametrically expanding a metal shaft, comprising:
a driving rotary section (205) and a driven rotary section (225) arranged opposite
each other, each of the rotary sections comprising holders for securing a work therebetween;
a driver (214) for rotating the work held by the holders around its axis;
a biasing device (230) for rotating either the driving rotary section (205) or the
driven rotary section (225) with respect to the axis of the holder of the other rotary
section;
a first slidable pressing device (206) and a second slidable pressing device (226)
for moving the driving rotary sections (205) and (225) toward and away from the axis
of a pivot (223) rotated by the biasing device (23); and
a displacing device for shifting the axis of the pivot between the holders in accordance
with a sliding distance covered by each of the two pressing devices (206) and (226).
8. An apparatus for diametrically expanding a metal shaft, comprising:
a pair of rotary sections (325) and (326);
a holder provided in each of the rotary sections for holding a work;
a sliding device (311) for causing at least one of the rotary sections to move toward
and away from the other rotary section;
a biasing device (319) for declining at least one of the rotary sections with respect
to the axis of the other rotary section;
a driver (332) for rotating the work held by the holders around its axis; and
a transmission (336) for transmitting the torque of one rotary section to another
so as to effect the synchronous rotation of the two rotary sections (325) and (326).
9. The apparatus according to claim 8, wherein the transmission (336) comprises a rotating
division in which rotatable brackets (338) are provided, having a pair of splines
(339) interposed between them, the splines comprising gears (340) engaged with follower
gear (333) provided in the rotating division, thereby transmitting a torque of one
of the rotating division to the other.
10. An apparatus for diametrically expanding a metal shaft, comprising:
a driving rotary section (407) provided with a first work holder and being capable
of rotating the work held by the holder;
a driven rotary section (415) provided with a second work holder on an opposite side
to the holder of the driving rotary section (407) and being capable of moving toward
and away from the driving rotary section (407);
a biasing device (428) for declining the second holder with respect to the axis of
the first holder; and
a pressing device (409) for pressing the driven rotary section (415) toward the driving
rotary section (407);
wherein the driving rotary section is driven by an arrangement in which the first
work holder is connected to a chuck of a lathe (M) so as to utilize the torque of
the lathe (M).
11. The apparatus according to claim 10, wherein the pressing device (409) is placed between
a base plate (403) and a slidable frame (416), and wherein the base plate (403) is
provided with a tapered shaft (402), the tapered shaft and the first work holder being
connected to the lathe (M), thereby compensating a repulsive force involved in operating
the pressing device within the base plate.