Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THEI INVENTION
This invention relates to an apparatus for cutting
and chamfering synthetic resin pipes having irregular ~- non-
circular cross sections.
In the prior art pipe cutting apparatuses cutting
and chamfering members are mounted on a rotating drum which
surrounds the pipe and rotates around the periphery thereof.
The cutting members are brought into contact with the
~ peripheral surface of the pipe, and such members are rotated
; in order to cut the pipe and chamfer the end face thereof.Such apparatuses are designed to accommodate just normal
or circular pipes, however, and are thus ineffective for
pipes having irregular shaped cross sections, such as an
ellipse or an egg-shape. Because the rotating cutting members
in such conventional apparatuses orbit around the center axis
of the pipe, the cutting edges cannot follow along the surface
of a pipe having an elliptical and egg-shaped cross section.
SUMMARY OF THE INVENTION
' 20 An object of the present invention is thus to provide
a pipe cutting and chamfering apparatus whose cutting edges -
ar~ capable o~ smoothly following the peripheral surface of a
pipe having an irregular shaped cross section, such as an
ellipse or an egg-shape.
According to the invention, a pair of swing levers
and fluid pressure drive cylinders therefor are pivotally ~
mounted on a travelling drum which surrounds the pipe, and -
rotates around the periphery thereof. Each s~ing lever lS ~.
connected to a piston rod of one of the fluid pressure cylinders,
35 and mounts a pipe contacting guide roller and a rotatably ~ ~;
driven cutting member. Pressure variations in the cylinders
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1 are absorbed by accumulators, whereby the cuttiny members are
driven into contact with and smoothly follow the uneven
contours of the pipe surface.
BRIEF DESCRIPTION OF THE DRAWINGS ~ . `
In the drawings:
FIG. 1 shows a front view, partly in schematic form,
: of an apparatus for cutting pipes according to a first embodiment
of the present invention,
FIG. 2 shows a partial sectional side view of the
cutting apparatus shown in FIG. 1 during a cutting operation,and
FIG. 3 shows a front view of a pipe cutting apparatus
. according to a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS : `
As shown in FIGS. 1 and 3, a frame member 1 surrounds
a synthetic resin pipe 3 having an oval or egg-shaped cross -
section continuously delivered by an extruder (not shown). `
The frame member is movable along the extrusion axis on tracks
or rollers 2, in accordance with the extrusion speed of the .
` 20 pipe 3O A drum 4 is rota~ably suppor~ed by rollers 5 and 5' ~ .
on the frame member 1, and can be rotated around the periphery ~ ~ :
`1 ~ of the pipe 3 hy a drive apparatus (not shown). Swing levers - .
6:and 6' are pivotally supported by journals 7 and 7' mounted .:
on the rotating drum 4. One end of each swing lever is
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:pivotally connected to a piston rod of a fluid pressure
cylinder 10 or 10'. Motors 8 and 8' for rotating cutting.
: members 9 and 9' through belt or chain drives are mounted at `.` - :
the journals 7 and 7' (FIG. 1) of the swing levers 6 and 6'. :
The cutting members 9 and 9' are attached to the other ends of -`:
.
: 30 Lhe swing levers on the same axles as guide rollers 11 and 11', ~ ;
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1 such axles being paralleled to the center axis of the
rotating drum 4. The guide rollers serve as followers, and
engage the sides o~ the pipe 3 during a cutting operation
(See FIG. 2). The cutting member 9 is used for chamfering,
and the cutting member or disc 9' is used for severing.
Counterweights 12 and 12' balance the swing levers
6 and 6' with respect to their pivotal fulcrums at journals
; 7 and 7', but such counterwei~hts may be omitted depending
on -the apparatus design. The fluid pressure cylinders 10 and 10'
1~ are pivotally mounted at their one ends on the drum 4. The
levers 6 and 6' are thus driven about their journals 7 and 7'
in accordance with the reciprocation of the piston rods,
whereby the cutting members 9 and 9' may be made to continuously
- follow the irregular surface of the pipe 3.
Accumulators 13 and 13' lessen the fluid pressure
variations in the cylinders 10 and 10', and keep the pressing
force of the cutting members 9 and 9' and guide rollers 11 and -
11' at a constant level during a cutting operation. The
- accumulators 13 and 13' are coupled to the fluid extension
or expansion lines of the cylinders 10 and 10' through
respective spool control valves.
In operation, a continuously extruded synthetic
resin pipe 3 having an oval or egg-shaped cross section is
engaged by a gripping mechanism (not shown) provided on the
frame member, at a desired position, whereby the frame member
advances or travels with the movement of the pipe 3 on the
tracks or rollers 2. At the same time,the drum 4 i5 rotated
in the direction of arrow A, and the fluid pressure cylinder
,
,: 10 i5 operated to extend its piston rod in the direction of ~ -~
arrow B, whereby the cutting member 9 contacts the surface o
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the pipe 3. The member 9 is rotated by the motor 8, and
guided on the peripheral surface of the pipe 3 by its associated
guide roller 11, whereby the member 9 travels smoothly over the
outer peripheral surface of the pipe 3 and makes a chamfered
cut therein~ Since the lever 6 is well-balanced with respect
to its supporting journal 7 and since the accumulator 13
absorbs fluid pressure fluctuations in the cylinder 10, the
pressure exerted by the guide roller and cutting member against
the outer peripheral surface of the pipe 3 is substantially
constant. Thus, even though the pipe has an irregular rather
than a normal circular cross section, the chamfering edge of
the cutting member 9 moves smoothly over the outer peripheral
surface of the pipe.
. After the chamfering cut has been made in the pipe
to the depth shown in FIG. 2, which requires just a single
complete rotation of the drum 4, the fluid pressure cylinder ~. ;
10 is operated in reverse so that its piston rod retracts and
the cutting end of the lever 6 swings away from the pipe 3.
The drum 4 is then rotated in the reverse direction, and the .:
~ fluid pressure cylinder 10' is operated to extend its piston ~.
rod and thereby swing the cutting member 9' and guide roller . ~
11' into contact with the surface of the pipe. ::
As shown in FIG. 2, the cutting disc enters the pipe :
along the straight or perpendicular edge of the chamfered cut,
and severs the pipe by closely following the outer peripheral
~ surface thereof. ~ ::
.~ In the same manner as described above with respect to
. ~
~the cutting member 9, since the swing lever 6' is well-
balanced and the accumulator 13' absorbs pressure variations in
the cylinder 10', the force exerted against the pipe by the
cutting member 9' is substantially constant, and it travels ;
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1 smoothly over the outer peripheral surface of the pipe. After
the drum ~ has completed a rotation and the pipe has been severed,
the cylinder 10' is operated in reverse to retract its
piston rod and swing the cutting member 9' and guide roller
11' away from the pipe 3. The gripping mechanism is then
opened to release the pipe, and the rrame member 1 is returned
to its original position. The series of operations involving
the movement of the frame member, the actuation of the fluid
pressure cylinders 10 and 10', and the rotation of the drum 4
10 and the cutting members 9 and 9', are automatically :~
controlled by a conventional, programmable mechanism (not shown).
Although separate chamfering and cutting members have
been disclosed, it will be apparent that a single member can
be used for both chamfering and cutting. In such a case, ~ :~
onIy one swing lever and fluid pressure cylinder is needed.
Furthermore, the drum has been disclosed as rotating in
opposite directions for chamfering and cutting, but this is not
necessary and is primarily a function of the design of the
accumulators 13 and 13'. -~
~ In the manner described above, the end face of the
pipe 3 is completely cut and chamfered If such process is
performed repeatedly, the extruded synthetic resin pipe 3 can
be effecti~ely and automatically cut into predetermined lengths
: with chamfered end faces.
The embodiment of the invention shown in FIG. 3 is
different from that of FIG. 1 in that the motors 8, 8', the
cutting members 9, 9', and the guide rollers 11, 11' are
positioned between the journals 7, 7' and the fluid pressure
cylinders 10, 10', and the counter weights 12, 12' are mounted ~
30 on the far ends of the levers 6, 6'. : :
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It will be appreciated, o~ course, that while the
invention has been disclosed as being particularly adapted for
the cutting of pipes having irregular shaped cross-sections,
normal or round pipes can be cut and chamfered with equal
facility.
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