Cutting – Cutting motion of tool has component in direction of moving... – Tool carrier shuttles rectilinearly parallel to direction of...
Reexamination Certificate
2000-01-19
2002-03-19
Ashley, Boyer (Department: 3724)
Cutting
Cutting motion of tool has component in direction of moving...
Tool carrier shuttles rectilinearly parallel to direction of...
C083S054000, C083S300000, C083S454000, C083S466100, C083S692000, C083S862000, C083S917000
Reexamination Certificate
active
06357327
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a method of cutting a metal pipe and an apparatus for cutting a metal pipe orthogonally to a central axis line thereof and capable of effectively cutting even a metal pipe coated with a resin coating layer at an outer peripheral face thereof.
2. Description of the prior arts
FIG. 5
shows a conventional apparatus of this kind for cutting a metal pipe and a metal pipe
1
to be cut, is held from directions orthogonal to a central axis line of the metal pipe
1
such that a cut position thereof is sandwiched at portions forward and rearward from the cutting position by holding holes
8
a
and
9
a
generally in a semicircular shape respectively formed at opposed faces of a pair of holding members
2
a
and
3
a
capable of being opened and closed opposedly in the horizontal direction and other pair of holding members
2
b
and
3
b
spaced apart from the pair of holding members in the axial direction of the metal pipe
1
.
Further, in respect of the metal pipe
1
, there is arranged a cut-off blade
5
for cutting off a portion of a pipe wall of the metal pipe
1
at a position of cutting the metal pipe
1
orthogonally to a central axis line of the metal pipe
1
and movably in an arrow mark X direction which is a direction of a tangential line of an outer peripheral face thereof. Further, there is arranged a cut blade
6
which is movable in an arrow mark Y direction constituting a direction orthogonal to the central axis line for cutting to penetrate the metal pipe
1
at a deficient wall portion where a portion of the pipe wall has been cut off by the cut-off blade
5
. Accordingly, the arrow mark X direction and the arrow mark Y direction constitute an angle of substantially 90 degree.
According to the conventional apparatus of cutting the metal pipe
1
having such a constitution, portions of the metal pipe
1
forward and rearward from the cut position are fixedly held by the holding holes
8
a
and
9
a
of the holding members
2
a
and
3
a
and the holding members
2
b
and
3
b
and successively, the cut-off blade
5
is firstly moved in the direction orthogonal to the central axis line of the metal pipe
1
indicated by the arrow mark X direction of
FIG. 5
relative to the metal pipe
1
and a portion of the pipe wall of the metal pipe
1
is cut off in the tangential direction by the cut-off blade
5
.
Successively, the cut blade
6
is moved from the direction orthogonal to the central axis line of the metal pipe
1
indicated by the arrow mark Y direction of
FIG. 5
and at the deficient wall portion of the metal pipe
1
where a portion of the metal wall has been cut off, the metal pipe
1
is cut by the cut blade
6
from the deficient wall portion.
However, according to the conventional apparatus of cutting the metal pipe
1
, in cutting of f a portion of the pipe wall in the tangential direction by the cut-off blade
5
, when angular moment is applied on the metal pipe
1
in the clockwise direction by the cut-off blade
5
as shown by an arrow mark M direction in FIG.
6
and the angular moment exceeds frictional force based on static frictional coefficient between peripheral faces of the holding holes
8
a
and
9
a
and the metal pipe
1
, the metal pipe
1
is rotated at insides of the holding holes
8
a
and
9
a.
When such a rotation by the angular moment in the arrow mark M direction is caused, not only scratch marks are produced at the outer peripheral face of the metal pipe
1
but also the metal pipe
1
is stopped at a cut-off position which is not in parallel with the arrow mark X direction but is inclined to the X direction by an angle as shown by
FIGS. 7A and 7B
as a result of the cut-off operation by the cut-off blade
5
.
Further, when cutting operation is started by the cut blade
6
under the state, the cutting operation is started from a portion of the metal pipe
1
where a portion of the pipe wall is not cut off or a portion thereof where an extremely small amount of the pipe wall is cut off and accordingly, burrs cannot be produced symmetrically in the left and right direction relative to the cut blade
6
and an extremely irregular or deformed cut face is constituted.
Further, even when the cut-off step is finished without rotating the metal pipe, in finally cutting the metal pipe by the cut blade
6
, there is brought about a state in which a lower side of the cut face of the metal pipe
1
is more roughened and deformed than an upper side thereof since the cutting operation is finished while the lower side of the cut face is being pressed by burrs from an inner face of the metal pipe.
In order to prevent various problems posed by rotating the metal pipe
1
from causing in the cut-off step, conventionally, widths of holding the metal pipe
1
by the holding members
2
a
and
3
a
and the holding members
2
b
and
3
b
, are widened, a circle formed by inner peripheral faces of the holding holes
8
a
and
9
a
is deviated from a completely round circle into an ellipse having a longer length in the vertical direction and an outer peripheral face of the metal pipe
1
is held while deforming the metal pipe
1
into the elliptical shape while exerting strong tightening force to the holding members
2
a
and
3
a
and the holding members
2
b
and
3
b
to thereby carry out the cut-off operation.
Accordingly, there poses a problem in which particularly in the case of a thin-walled one of the metal pipe
1
, at a vicinity of the cutting portion of the metal pipe
1
after having been cut to penetrate, as shown by
FIG. 8
, the metal pipe
1
is frequently deformed in an elliptical shape deviated from a completely round circle.
Further, in the case of a resin-coated metal pipe
11
produced by providing a resin coating layer
7
on the outer peripheral face of the metal pipe
1
, the resin coating layer
7
is cut off in the tangential direction along with a portion of the pipe wall of the metal pipe
1
by the cut-off blade
5
and successively, the cutting operation by the cut blade
6
is started from a position of the deficient wall portion where the portion of the pipe wall is cut off. At an instance at which the cut blade
6
exerts shear force from above the resin-coated metal pipe
11
, the resin coating layer
7
having Young's modulus far smaller than that of the metal pipe
1
is deformed to compress at insides of the holding holes
8
a
and
9
a
on the side of the deficient wall portion and the cutting operation is progressed under the state. As a result, at a final portion, that is, immediately before finishing the cutting operation, an inner peripheral end face of the metal pipe
1
is partially deformed toward an outer side and as shown by
FIG. 9
, a shear droop portion
10
is produced at the portion of cutting the metal pipe
1
and a highly accurate cutting operation may not be carried out.
SUMMARY OF THE INVENTION
The invention relates to a method of cutting a metal pipe for cutting a metal pipe orthogonally to a central axis line of the metal pipe and an apparatus, capable of effectively cutting even a metal pipe coated with a resin coating layer at an outer peripheral face thereof.
The invention has been carried out in view of a current situation of cutting by a conventional apparatus of cutting a metal pipe or a resin-coated metal pipe of this kind, described above, and it is an object of the invention to provide a method of cutting a metal pipe or a resin-coated metal pipe with high accuracy by preventing the metal pipe or the resin-coated metal pipe from being rotated, preventing burrs in cutting from being caused and preventing a cutting face from being deformed and preventing shear droop caused by a resin coating layer of the resin-coated metal pipe from being produced, and an apparatus to implement the same.
In order to achieve the above-described object, according to a first aspect of the invention, there is provided a method of cutting a metal pipe which is a method of cutting the metal pipe orthogonally to a centr
Shiozaki Fumihiko
Usui Masayoshi
Watanabe Fujio
Ashley Boyer
Casella Anthony J.
Hespos Gerald E.
Usui Kokusai Sangyo Kaisha Limited
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