Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention pertains to a hand-held
pipe cutter adapted to cut hollow tubular pipes.
BACKGROUND OF THE INVENTION
Hand-held pipe cutters are known. For
example, Canadian patent 1,086,045 issued September 23,
1980 to A. Courty describes a tube cutter with a
ratchet handle and a C-shaped head defining a lateral
opening through which a tube may be inserted. A knob
is rotated to tighten the jaw against the tube
contacting a cutting wheel. The handle is actuated
back and forth along a limited angle of rotation to
rotate step-by-step the cutting wheel around the tube.
Such conventional pipe cutters are manually
operable and require the user to work in a given free
area where the back-and-forth actuation of the device
renders it difficult to cut certain pipes which are
difficult to access.
OBJECTS AND STATEMENT OF THE INVENTION
It is an object of the present invention to
provide a cutter for pipes which is simple to use and
can carry out the cutting operation in a much quicker
fashion than conventional manually-operated pipe
cutters.
It also an object of the present invention to
provide a pipe cutter which can be used in areas where
the pipe to be cut is very limited. Once the pipe is
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grasped, it can be cut.
The present invention therefore relates to a
hand-held electric pipe cutter which comprises, in its
broadest aspect, a body having a handle portion and a
head portion; an electric motor mounted in the head
portion, a rotatable C-shaped pipe receiving and
cutting jaw also mounted in the head portion and
defining a lateral opening to receive a pipe to be cut;
and rotational drive transmission means mounted between
the motor and the jaw for rotating the jaw. The jaw
consists of first cylindrical housing means including
first gear means engageable with the drive transmission
means, the first cylindrical means defining a cam
surface. The jaw also includes second cylindrical
housing means including second gear means engageable
with the drive transmission means and cutting means
engageable with the outer surface of a pipe received in
the jaw. The second cylindrical housing means include
a cam following means adapted to ride on the cam
surface of the first housing means. The gear ratio of
the first and second gear means on the first and second
housing means is predetermined to provide the first
housing means with one full rotation in addition to the
predetermined number of rotations of the second housing
means whereby the cutting means progressively penetrate
and cut into the pipe as both first and second housing
means are rotated.
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In one form of the invention, the second
housing means include two segments, one of which
displays a rotatable cutting blade while the other
includes roller means which contact the pipe to be cut
and forces it against the cutting blade as the housing
means are rotated.
In another embodiment of the invention, the
two segments are radially movable relative to one
another and spring means are provided for returning the
blade to its initial position after the pipe is cut.
The handle portion of the pipe cutter may
define a housing for receiving one or more batteries.
Alternatively, the pipe cutter may be connected to an
electrical outlet.
Other objects and further scope of
applicability of the present invention will become
apparent from the detailed description given
hereinafter. It should be understood, however, that
this detailed description, while indicating preferred
embodiments of the invention, is given by way of
illustration only, since various changes and
modifications within the spirit and scope of the
invention will become apparent to those skilled in the
art.
IN THE DRAWINGS:
Fig. 1 is a perspective view of a hand-held
electric pipe cutter made in accordance with the
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present invention;
Fig. 2 is a perspective view of the pipe
cutter showing components of the head portion and of
the handle portion;
Fig. 3 is an exploded view showing the
various components of the C-shaped jaw mounted in the
head portion of the pipe cutter;
Fig. 4 is a fragmentary front view, inside
the jaw, showing the assembled components; and
Fig. 5 is a side view showing the cutting
blade engaging a pipe to be cut.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to Fig. 1, there is shown a
hand-held pipe cutter, generally denoted 10, defining a
gun-shaped body formed of two symmetrical half-portions
12 and 14 which are secured together by means of a
series of screws 16. Body 10 displays a head portion
18 and a handle portion 20.
Referring to Fig. 2, an electric motor 22 is
mounted inside the head portion 18. The motor drives a
shaft 24, one end of which is provided with a
frustro-conical gear wheel 26. A C-shaped jaw 28 is
operatively connected to the electric moLor through a
gear arrangement that includes a large gear wheel 30
appropriately driven by gear wheel 26 and driving a
pair of gear wheels 32 and 34. Gear wheel 34 is
coupled with a gear wheel 36 by means of a shaft 38
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while gear wheel 32 is similarly coupled to another
gear wheel (not shown). Hence, gear wheels 34 and 36
are paired while gear wheel 32 is paired with the
non-illustrated gear wheel. The separation between the
pairs of gears wheels (for example, between wheel 32
and 34) is greater than the opening of the jaw to
maintain continuous drive between the jaw and the drive
transmission assembly.
Operation of the electric motor 22 is carried
out by means of a battery 40 which is housed in the
handle portion 20. An actuator 42 is provided for
operating motor 22; means may be provided to vary the
speed of the electric motor by varying the depression
of the actuator 42 in the handle 20. Also, a button 44
is provided to reverse the rotation of the electric
motor, if needed
Alternatively, the cutter may be connected to
an electrical outlet.
Referring to Figs. 3 and 4, the various
components of the jaw 28 will now be described. It
comprises a first cylindrical housing 46 defining a
C-shaped configuration and displaying over its outer
wall, a series of teeth 48. The inner wall of the
housing displays a cam surface 50, the function of
which will be described hereinafter.
The jaw also comprises a second cylindrical
housing 52, having a C-shaped configuration, its outer
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wall displaying a series of teeth 54.
Inside housing 52 are received two
diametrically opposed segments 55 and 56. The lower
segment 56 is pivotable about pin 57 and relative to
the upper segment 55. The latter defines an inner
cavity displaying a shape to receive therein the top
surfaces of a roller support 60 to which is mounted a
series of rollers 62, 64 and 66 extending in parallel
axial alignment with the central axis of the jaw. A
screw 61 secures the roller support to segment 55. The
lower segment 56 has a cavity 68 in which is rotatably
retained a circular cutting blade 70. The lower
segment 56 also includes a cam follower 72 mounted on a
pin 73 fixed to the side wall of the segment; this
follower is adapted to roll along the cam surface 50 of
the first housing 46 when the components are assembled.
The two housings 46 and 52 are spaced from
one another by means of an assembly of three segments
74, 75 and 76. Cavities 78 and 80 are defined in
segments 74 and 76 and have a shape corresponding to
that of cavity of the upper segment 55 so as to also
receive the roller support 60 therein.
The assembly of the various components shown
in figure 3 will now be given.
Elements 75 and 76 are inserted in the
housing 46 by positioning the extremity 100 of segment
75 and the extremity 102 of segment 76 in the annular
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recess 104 on the inside wall of the housing 46.
Segment 75 is secured to segment 74 by means of a
series of screws 82. Then, the support roller 60 is
placed within the cavity of the upper segment 55 and
secured by means of screw 61. The various segments 74
and 75, 76 received in housing 46 are secured together
by means of screws 84. The relative rotational
connection of housings 46 and 52 is due to the annular
edges 100 and 102 which are engaged in recess 104.
Also, this engagement allows rotation of housing 46
relative to housing 52 and all of its assembled
segments.
In the operation (see Fig. 5) of cutting a
pipe 106 laterally inserted in the C-shaped jaw, the
motor 22 causes the rotation of the two housings 46 and
52. However, the difference in teeth ratio between
wheels 34 and 36 causes a different rotation of the two
housings. This gear ratio is such that, for a full
rotation of housing 52, housing 46 makes slightly more
than one rotation so that for a complete cutting
operation, where, for example, housing 52 has made
twelve rotations, housing 46 will have made thirteen
rotations, so that, during the twelve rotations of
housing 52, the cam follower 72 has slightly moved on
the cam surface 50 thereby progressively forcing blade
70 into the pipe to be cut. Therefore, at the end of
the operation, the blade is in its most closed position
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on the tube so that the latter is completely cut. The
cam follower then returns to its original position on
the cam surface (i.e. radially outward of the central
axis of the jaw), when the two lateral openings of the
housings come once again in registery, spring 58
assisting in the returning of segment 56 against the
inner wall of the housing 52.
Although the invention has been described
above in relation to one specific form, it will be
evident to a person skilled in the art that it may be
refined and modified in various ways. For exemple, cam
followers of various outer diameters may be mounted on
pin 73 so as to cut pipes of varying diameters. It is
therefore wished to have it understood that the present
invention should not be limited in interpretation
except by the terms of the following claims.
