Note: Descriptions are shown in the official language in which they were submitted.
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A JOINTING APPARATUS OF THERMO PLASTIC PIPES
BACKGROUND OF THE INVENTION
The present invention relates to a jointing apparatus for jointing
thermo plastic pipes by using frictional heat caused by vibration.
Recently, polyethylene pipe, which is a thermo plastic pipe, is
coming to be used commonly for gas piping or water piping. Because,
the polyethylene pipe is excellent not only in corrosion resistance, but
also in earthquake resistance due to its large extensibility. In such a
situation, a method for jointing thermo plastic pipes more effectively and
securely and an apparatus for this method are demanded increasingly.
As a conventional method for jointing polyethylene pipes, a butt
welding method using a flat-plate-shaped hot plate, a socket welding
method using a socket, or the like is used. The butt welding method
consists in heating respective extremities of pipes to be jointed by means
of a hot plate heated to a high temperature having a larger cross-section
than the pipe diameter, thereafter removing the hot plate, butting end
faces of the pipes to be jointed and welding under pressure. As
representative methods of the socket welding method, there are a method
for welding similarly to said butt fusion method using a hot plate having
a shape that corresponds with a shape of a used socket and a method for
welding by using a socket having an implanted electric heating element
wire such as Nichrome wire and supplying this electric heating element
wire with electricity to heat the external surface of the pipe and the
internal surface of the socket and thereby weld them.
Besides, jointing methods for butting and jointing plastic pipes,
by using frictional heat generated on butting junction faces of plastic
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pipes by turning the pipes in reverse directions to each other, in place of
using a hot plate or an electric heating element as mentioned above, are
disclosed in Japanese Patent Publications No. Hei 2-13619, No. Shou
63-39415 and others. The art disclosed in the Japanese Patent Publication
No. Hei 2-13619 is to obtain a connecting joint without requiring burring,
by using friction caused by rotation. In Japanese Patent Publication No.
Shou 63-39415, a terminal portion of a socket is pressed to the front end
of a plastic pipe to obtain friction caused by rotation so that the shape of
the terminal portion of the socket may be independent of the diameter of
the plastic pipe and easier molding of the socket can be expected.
On the other hand, Japanese Patent Laid-Open No. Shou 62-
35830 proposes a method for manufacturing a support with a cap. This
method is to weld the outer circumference of a support body and a cap
only at required points without using a specific heating device, by
introducing an extremity of the support body into a cavity of the cap
made of synthetic resin mold, and turning the outer circumference of the
support body relatively to the cap. Japanese Patent Laid-Open No. Shou
62-248236 describes a jointing method of thermo plastic pipes of
different diameter by frictional heat. Besides, Japanese Patent Laid-Open
No. Hei 02-248236(Japanese Patent Publication No. Hei 5-36225) also
proposes a jointing method using frictional heat between plastic
materials.
Moreover, the Inventors have already proposed a basic method
for jointing plastic pipes by applying rectilinear vibration to generate
frictional heat and applied for a patent by filing Japanese Patent
Applications No. Hei 7-19665, No. Hei 7-240522 and No. Hei 8-68989.
In a butt welding method or a socket welding method using a hot
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plate mentioned above, as a hot plate is used repeatedly, soil deposited
on the hot plate sticks to the pipe end face so that junction surfaces come
to include impurities resulting in junction defects.
Moreover, with the electric heating of a hot plate, it takes long
time about 700 sec from the beginning of electric supply to the plate to
the completion of welding, resulting in low labor effectiveness. When a
socket having an electric heat element wire such as Nichrome wire
implanted therein is used, it is necessary to provide a socket including a
heat element wire every time a couple of pipes are to be jointed and a
great number of sockets should be prepared provoking some questions
from economical point of view. Further, since it takes about 1700 sec
from the beginning of electric supply to the completion of welding, a -
labor effectiveness problem is caused especially when a number of pipes
are to be jointed.
In the case of the butt jointing of pipes by using heat generated
by rotational friction as described, for example, in Japanese Patent
Publication No. Hei 02-13619, a large amount of energy is necessary for
rotating the entire pipes to be jointed.
What is described in Japanese Patent Laid-Open No. Shou 62
35830 is not for a butt jointing of both polyethylene pipes but of entirely
different pipes; so it is difficult to apply this method to butt jointing of
both polyethylene pipes. Because, in the method described in said
document, the junction strength is ensured by inserting a mandrel into a
cavity in a way to increase contact area in order to enlarge the junction
surface, while such enlarged junction surface is not allowed in butt
jointing.
On the other hand, when polyethylene pipes of an identical
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diameter are to be jointed, the contact area is small so that the method
described in Japanese Patent Laid-Open No. Shou 62-248623 can not
ensure a sufficient reliability, because of low mechanical strength per
unit area obtained by the method. As a result, in practice, the jointing
strength is increased by increasing the contact area through the use of
pipes having different diameters.
The invention of Japanese Patent Laid-Open No. Hei 02-248236
(Japanese Patent Publication No. Hei 5-36225) is an example of friction
jointing of solid rods using mechanical rotation; however it is also
difficult to ensure junction strength for the jointing of pipes (hollow
cylinder), having small junction cross section, causing a reliability
problem.
On the other hand, vibration jointing methods and apparatus of
Japanese Patent Applications No. Hei 7-19665, No. Hei 7-240522 and No.
Hei 8-68989 already filed by the Inventors are to verify a laboratory
level principle and are not practical enough to be applied on jobsites.
Besides, a method for generating frictional heat by orbital movement of
pipe end faces, by using electromagnets (or permanent magnets), is
proposed in Japanese Patent Application No. Hei 7-196625, but the
adoption of electromagnets complicated the apparatus itself excessively.
In other words, conventional apparatus have not be well devised
from structural point of view, as a vibration jointing apparatus
appropriated to be used in the practical field, such as a piping jobsite for
gas, water or the like.
SUMMARY OF THE INVENTION
The present invention intends to solve these inconveniences and
has the object of obtaining a jointing apparatus of thermo plastic pipes,
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which can be practicaly used on jobsites or the like, and form a good
junction easily in a short period of time. The following apparatus is
proposed to solve the problems mentioned above.
According to the first embodiment, a jointing apparatus
comprises a clamp means for holding a pair of thermo plastic pipes
coaxially, a pressurizing means for bringing into contact under a pressure
end faces to be jointed of said pair of thermo plastic pipes held by said
clamp means and an orbital vibration generator means attached adjacent
to one or both pipe end portions) of said pair of thermo plastic pipes for
affording orbital vibration to said pipe end portion.
Said orbital vibration generator means comprises a crank shaft
having a shaft portion and a crank portion whose axes are eccentric, a
motor for giving rotation to the shaft portion of said crank shaft, a
bearing attached to the crank portion of said crank shaft and an orbital
vibration clamp for holding said pipe end portion, formed integrally with
the outer ring of said bearing to move integrally with said bearing.
Moreover, said orbital vibration clamp is supported at least with
three points.
According to the jointing apparatus of the first embodiment, its
size or weight can be appropriated for the jobsite use in piping work for
gas, water or the like and its labor effectiveness can be improved
remarkably.
Besides, frictional heat generated by orbital vibration allows a
sure junction within a very short period of time of 1 min or less.
In the second embodiment, a jointing apparatus comprises a
clamp means for holding a pair of thermo plastic pipes coaxially, a
pressurizing means for bringing into contact under a pressure end faces
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to be jointed of said pair of thermo plastic pipes held by said clamp
means and a rectilinear vibration generator means attached adjacent to
one or both pipe end portions) of said pair of thermo plastic pipes for
affording rectilinear vibration to said pipe end portion.
Moreover, said rectilinear vibration generation means comprises
an actuator for performing rectilinear reciprocating movement by
receiving output from a hydraulic servo-valve and a rectilinear vibration
clamp for holding said pipe end portion, linked to said actuator.
Besides, the vibration frequency of said actuator is 100 to 150
Hz.
According to the jointing apparatus of the second embodiment,
similarly to the apparatus of the first embodiment, its size or weight can
be appropriated for the jobsite use in piping work for gas, water or the
like and its labor effectiveness can be improved remarkably.
Besides, frictional heat generated by rectilinear vibration allows
a sure junction within a very short period of time of 1 min or less.
Any of the first and the second embodiments prevents
contamination defects which are encountered in hot plate method, a
conventional jointing method, in a way to ensuring a high reliability of
the junction.
Moreover, as it is unnecessary to prepare a number of sockets in
which heat elements are buried as in conventional socket fusion jointing
method, an excellent effect from economical point of view is achieved.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a side view showing a jointing apparatus according to a
first embodiment.
Fig. 2 is a view along A-A of Fig. 1.
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Fig. 3 is an enlarged view of a portion B of Fig. 1.
Fig. 4 illustrates orbital vibration of a thermo plastic pipe.
Fig. 5 is a top view showing a jointing apparatus according to a
second embodiment.
Fig. 6 is a side view of the jointing apparatus according to the
second embodiment.
Fig. 7 shows a rectilinear vibration clamp of the jointing
apparatus according to the second embodiment.
Fig. 8 shows a fixed side clamp of the jointing apparatus
according to the second embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now the preferred embodiments according to the present
invention will be described referring to the attached drawings.
It concerns an orbital vibration type jointing apparatus wherein
an orbital vibration is applied to a junction surface of a thermo plastic
pipe.
Fig. 1 is a side view showing a jointing apparatus according to a
first embodiment, Fig. 2 is a view along A-A of Fig. 1, and Fig. 3 is an
enlarged view of a portion B of Fig. 1. In these drawings, references 10
and 11 indicate a pair of thermo plastic pipes to be jointed, where 10 is a
moving side thermo plastic pipe and 11 a fixed side thermo plastic pipe.
A pair of upset driving shafts 2 and a pair of moving clamp
guide shafts 3 are laid across between a first support 1 a and a second
support 1 b fixed to a base 1 and, at the same time, a moving side clamp 4
for holding and fixing the moving side thermo plastic pipe 10 is attached
to the upset driving shaft 2 and the moving clamp guide shaft 3. A fixed
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side clamp 5 for holding and fixing the fixed side thermo plastic pipe 11
is attached to the first support 1 a. Further, a vibration driving motor 6 is
attached to the base 1 and the output of this motor 6 is transmitted to a
crank shaft 8 via a belt 7 from a motor shaft 6a. Besides, 14 indicates an
AC servo-motor or a hydraulic cylinder for moving the upset driving
shaft 2, 15 a moving guide for supporting the movement of the moving
side thermo plastic pipe 11, 16 and 16' bearings rotatably supporting
crank shafts 8 and 8' respectively at the support 1 a. Here, the bearings 16
and 16' of the same type and also the crank shafts 8 and 8' of the same
type are used.
As shown in Fig. 3, the crank shaft 8 is composed of a shaft
portion 8a and a crank portion 8b where the axes of the shaft portion 8a
and the crank portion 8b are eccentric by a distance r (deviation amount
r). A bearing 9 for transmitting the rotation of the shaft center of the
crank portion 8b is attached around the outer circumference of the crank
8b and an orbital vibration clamp 13 is formed integrally with the bearing
9 around the outer ring of this bearing 9. As shown in Fig. 2, the orbital
vibration clamp 13 includes a damper 13a for holding the end portion of
the fixed side thermo plastic pipe 11. Besides, two other crank shafts 8'
supported rotatably and a bearings 9' (of same type as the bearing 9) are
arranged so as to form a equilateral triangle or an isosceles triangle to the
crank shaft 8 and the bearing 9, for supporting the orbital vibration clamp
13 at three points. It may also be supported at three or more points.
Next, the process to joint thermo plastic pipes using this
apparatus will be described. Here, jointing is performed using 200U
polyethylene pipe described in JIS K6774 as thermo plastic pipe.
First, the moving side thermo plastic pipe 10 is mounted on the
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moving side clamp 4 and the fixed side thermo plastic pipe 11 is mounted
on the fixed sided clamp 5. The protruded length (protruded length of the
junction end face from the orbital vibration clamp 13 or the moving side
clamp 4) of the moving side and fixed side thermo plastic pipes 10, 11
are adjusted , then the respective clamps 4, 5, 13 and the moving guide
are tighten to fix the pipes 10, 11.
Further, the upset driving shaft 2 is turned and displaced by
means of the AC servo-motor or the hydraulic cylinder 14 to advance the
moving side thermo plastic pipe 10 and the moving side clamp 4, then the
10 moving side thermo plastic pipe 10 is pressed to the fixed side thermo
plastic pipe 11 with a given upset force. The upset force can be
controlled by the flowing current value for the AC motor 14 or by the
servo-valve for the hydraulic cylinder.
Next, the vibration driving motor 6 is activated to orbitally
15 vibrate the orbital vibration clamp 13 with a given frequency. Namely,
the rotation of the motor shaft 6a is transmitted to the crank shaft 8 via
the belt 7. Here, deviation vibration generated by the eccentricity of the
axial center of the shaft portion 8a and crank portion 8b of the crank
shaft 8 is translated into the orbital vibration by the orbital vibration
clamp 13 as shown in Fig. 4. This is because, the bearing 9 separates the
rotation of the crank shaft 8 itself and the rotation due to the eccentricity
of the crank shaft 8 and only the orbital vibration of the crank shaft 8 is
transmitted to the orbital vibration clamp 13 via the outer ring of the
bearing 9. The orbital vibration clamp 13 shall not rotate in respect of the
shaft center of the crank shaft 8, because it is supported at three points by
the crank shaft 8 and the two other crank shafts 8', 8'.
When the end face of the fixed side thermo plastic pipe 11
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vibrates orbitally in respect of the end face of the moving side thermo
plastic pipe 10 by means of the orbital vibration clamp 13, frictional heat
is generated at the junction end faces of the thermo plastic pipes to fuse
them. Fused plastic is discharged from the junction end face toward the
circumference as burr. When the upset amount, namely fusion amount,
attains a given value, the vibration is automatically stopped by servo-
control. Then, after a given cooling time, say after about 10 sec,
respective clamps are opened and the thermo plastic pipe are taken out to
complete the jointing of a pair of thermo plastic pipes.
As a result, when polyethylene pipes are jointed as mentioned
above, the jointing performance of the polyethylene pipes is excellent
enough. In this case, the specifications of the rotating portion for
jointing are as follows. These specifications represent only an example.
Orbital rotation speed at vibration clamp portion : 7200 r.p.m.
(120 cps)
Deviation amount : 0.75mm
Weight of driving portion : about 30Kg
Max. acceleration : about 44G
Vibration driving motor
- Capacity : S.SKW x 2p
- Speed : 3600 r.p.m. (increased by two times through timing
belt)
- Driving : Inverter power supply
By the way, respective clamps for fixing the thermo plastic pipe
can be changed appropriately according to the pipe diameter to be
jointed.
As the deviation amount r should be adjusted according to the
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pipe diameter to be jointed, crank shafts having different deviation
amount r are selected and used conveniently according to the pipe
diameter to be jointed.
It concerns a rectilinear vibration type jointing apparatus for
rectilinearly vibrating the junction face of a thermo plastic pipe using a
hydraulic servo mechanism. It is characterized in that the apparatus body
is reduced in size and weight by reducing the exciting force through the
reduction of vibration frequency, as the vibration inertia is proportional
to the square of vibration frequency. This allows reduction of the body
weight to the order of about 800kg.
Fig. 5 is a top view and Fig. 6 is a side view of the jointing
apparatus according to the second embodiment 2. In these drawings,
references 10 and 11 indicate a pair of thermo plastic pipes to be jointed,
where 10 is a moving side thermo plastic pipe and 11 a fixed side thermo
plastic pipe. 21 is a hydraulic actuator vibrating at the frequency of
100Hz to 150Hz, 22 is a rectilinear vibration clamp linked to the
hydraulic actuator 21 to hold and vibrate the junction end portion of the
fixed side thermo plastic pipe 11 and 23 is a hydraulic servo-valve for
driving the hydraulic actuator 21. 24 is a moving side clamp for fixing
the moving side thermo plastic pipe 10 and 25 is a fixed side clamp for
fixing fixed side thermo plastic pipe 11. 27 is a hydraulic upset
cylinder to bring the junction end face of the moving side thermo plastic
pipe 10 into contact under a pressure with the junction end face of the
fixed side thermo plastic pipe 11, and 28 is a linear guide for displacing a
bed 29 by means of the upset cylinder 27.
Fig. 7 shows a rectilinear vibration clamp connected to the
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hydraulic servo mechanism. The rectilinear vibration clamp 22 is linked to
the hydraulic actuator 21 driven by the hydraulic servo-valve 23. This
ring-shaped rectilinear vibration clamp 22 is composed of two parts 22a,22b
and one of two parts is releasably attached to the other by means of a bolt
22c
or the like, and thereby the thermo plastic pipe can be held conveniently.
Furthermore, this rectilinear vibration clamp 22 can be changed and used
appropriately according to the pipe diameter to be joined.
Fig. 8 shows the fixed side clamp 25. Basically, the fixed side
clamp 25 is composed of a hydraulic cylinder 25a and a clamper 25b opened
and closed by the cylinder 25a, to open/close the clamper 25b by
extending/retracting the arm of the hydraulic cylinder 25a in order to hold
and fix the pipe. This clamper 25b is also exchanged appropriately according
to the pipe diameter to be joined. Such structure is same for the moving side
clamp 24 having a hydraulic cylinder 24a and a clamper 24b.
Here, it is further devised as follows to improve the labor
effectiveness.
( 1 ) The body structure is made capable of generating the vibration
laterally so that plastic pipes can be introduced into/extracted from the
respective clamps laterally. This allows extracting the plastic pipe easily
from the body in case of trouble, for instance.
(2) The clamping by the clampers 24b,25b can be set in three states
(on, off, slight clamping) by the hydraulic valve; and also, the protruded
length (protruded length of the junction end face from the moving side clamp
24 or the rectilinear vibration clamp 22) of thermo plastic pipes can be set
easily by using the inching of the upset operation.
Next, the process to join thermo plastic pipes using this
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apparatus will be described. Here, the jointing is performed using 200U
polyethylene pipe described in JIS K6774 as thermo plastic pipe.
First, the moving side thermo plastic pipe 10 is mounted on the
moving side clamp 24 laterally along the axial direction, and the fixed
side thermo plastic pipe 11 is mounted laterally on the fixed side clamp
25 along the axial direction. The protruded length of the moving side and
fixed side thermo plastic pipes 10, 11 is adjusted, then tighten the
respective clamps 22, 24, 25 to fix the pipes 10, 11.
Then, the moving side thermo plastic pipe 10 is brought into
contact with the fixed side thermo plastic pipe 11 and pressed thereto
with a given upset force by using the upset cylinder 27. At the same
time, rectilinearly the rectilinear vibration clamp 22 is rectilinearly
vibrated via the hydraulic actuator 21 by using the hydraulic servo-valve
23. The hydraulic servo-valve 23 vibrates rectilinearly the junction end
face of the fixed side thermo plastic pipe 11 through the hydraulic
actuator 21 and the rectilinear vibration clamp 22. Thus, frictional heat is
generated at the junction end faces of the thermo plastic pipes to fuse
them. Fused plastic is discharged from the junction end face toward the
circumference as burr. When the upset amount, namely fusion amount,
attains a given value, the servo-control stops the vibration automatically.
Then, after a given cooling time, say after about 10 sec, respective
clamps are opened and the thermo plastic pipe is taken out to complete
the jointing of a pair of thermo plastic pipes.
When polyethylene pipes are joined as mentioned above, the
joint performance of the polyethylene pipes is excellent enough. In this
case, the vibration conditions of the apparatus are as following. These
conditions represent only an example.
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Amplitude : 0 to 2 mm peak to peak
Wave form: Sinusoidal
_ Power level: Capable of continuous operation at
120Hz x 2mmP-P
Vibration frequency : 100 to 150Hz
The apparatuses described above in the first and the second
embodiments are also applicable to all other thermo plastic pipes such as
polyethylene pipe, polybudene pipe.
