Pipe cutting tool

A self contained power driven, adjustable tube cutting tool is disclosed. Within the main tool housing is a rotatably mounted C-shaped body having an adjustable automatic cutter feeding and retract mechanism therein, operable by the rotational movement of the body about the pipe axis. Opposing a set of pipe backup rollers is a cutting wheel attached to post slidable through the center bores of two mating cylindrical bodies all on a common longitudinal axis. The mating faces are spirally configured through a single rotational turn to create linear expansion and contraction of the bodies as one, integrally attached to a ratchet wheel, rotates while the other does not. A spring biased pawl couples the non-rotational body to the sliding post. The ratchet wheel engages a second spring biased driving pawl pivotally attached to a cylindrical sliding roller body which protrudes from the periphery of the cutting wheel body. A stationary semicircular cam track is fixed within the main tool housing adjacent to the cutting wheel body periphery. As the body is rotationally driven the roller follows the profile of the cam track and hence the driving pawl moves in a radial direction inward to the pipe axis engaging and rotating the ratchet wheel, thus the two cylindrical bodies are then expanded and move the post and cutter in radially towards the pipe axis as it cuts.

BACKGROUND--FIELD OF INVENTION 
The present invention relates generally to portable pipe cutting tools, and 
more specifically to hand held, fully adjustable, automatic feed and 
retract tools intended for use in confined spaces. 
BACKGROUND--DESCRIPTION OF PRIOR ART 
Portable tube cutting tools are well known and can be either hand operated 
or power driven. 
The prior known portable pipe cutting devices typically have a rotatable 
body with an opening forming a C-shape to receive the pipe to be cut. 
Attached within the body usually are support rollers to back up the pipe 
as it is being cut and opposing cutting means such as a cutting wheel or 
blade type cutting tool fastened to a cutting arm. Some of the previously 
known devices have an arm with cutting tool that is self feeding into the 
wall of the pipe. Prior art portable pipe cutters that are self feeding 
are described in U.S. Pat. No. 4,890,385 to VanderPol (1990) also self 
retracting and operable by an auxiliary power source such as an electric 
drill. However, this device accommodates only a single size pipe. Other 
prior known self feeding tube cutting tools are U.S. Pat. No. 4,493,150 to 
Garcia et al (1985) which is a very complex device thereby very expensive 
to manufacture and also requiring a separate driving motor. U.S. Pat. No. 
4,416,062 to Cummings (1983) is a hand operated tool also very complex. A 
further prior known self feeding device is U.S. Pat. No. 4,305,205 to 
Girala (1981) a tube cutter assigned to NASA and extremely complex and 
hence would be prohibitively expensive to manufacture. The Girala device 
is hand operated but can optionally be coupled to an auxiliary power 
driving source. U.S. Pat. No. 4,149,312 to Arnot (1979) and U.S. Pat. No. 
3,651,569 (1972) also to Arnot disclose a self feeding cutting means which 
is hand operable. Also a self feeding tube cutter is U.S. Pat. No. 
2,007,122 to Briegel (1935). A hand operated device. 
It can be noted that the majority of the prior art pipe cutting devices are 
of very complex design and hence very expensive to manufacture. The 
devices that can be power driven, thereby eliminating the physical 
exertion normally associated with manual operation, all require an 
attaching auxiliary motor. The prior known pipe cutting devices are 
cumbersome and slow to adjust with respect to manually advancing the 
cutting tool or wheel to place it on the marked cut off spot on the pipe 
or tube to be cut. This is particularly true when they are being manually 
adjusted while the tool is placed over an installed pipe that is confined 
in a place where space is limited. 
OBJECTS AND ADVANTAGES 
Accordingly, it is therefore an object of the present invention to provide 
the user with a tube cutting device that is "user friendly", convenient to 
use, quickly adjusting and with a cutting wheel that is both automatic 
feeding and retracting. This cutting mechanism would be part of a small 
lightweight, self contained electric motor powered tool intended for use 
in the field of building construction and building maintenance for use on 
installed pipe. 
A further object of the present invention is to provide a tube cutting 
device that will easily adapt to use in confined areas. 
In another aspect of the present invention, it provides the advantage of a 
way to quickly adjust the tool to accommodate different size pipe. 
A further object of the present invention is to provide a simplified 
mechanism with which to automatically advance and retract the cutting 
means thereby reducing the manufacturing expense of the tool. 
A still further object of the present invention is to provide a tool that 
is portable, small, lightweight and when placed around a pipe or tube to 
be cut, can instantly adjust the cutting wheel to clamp snuggly up against 
the tube wall ready to be cut. 
It is an additional object of the present invention to provide a tube 
cutting mechanism that can be completely contained within a small tool 
housing having its own driving electric motor. 
Further objects and advantages of this invention will become apparent from 
a consideration of the drawings and ensuing description.

DETAILED DESCRIPTION--FIGS. 1 TO 22 
Referring now to the drawings, specifically FIG. 1, there is illustrated a 
perspective view of a hand held, power driven, pipe cutting tool 
incorporating a fully adjustable, automatic cutter feeding and retract 
mechanism in accordance with a preferred embodiment of the present 
invention. 
A C-shaped cutting wheel body 8 is rotatably mounted within the main tool 
housing 10 (FIGS. 2 and 3). Integrally part of the sides of the cutting 
wheel body 8 are semi-circular tracks 68 which support the body with a 
plurality of rollers 70 fixed to the main tool housing 10 and equally 
spaced around a circle that is concentric with the peripheral circular 
shape of the cutting wheel body 8 and having concentric centers. 
Contained within the cutting wheel body 8 is a simple cutting wheel 
advancing and retract mechanism (shown in FIGS. 4 and 22). 
The mechanism has four basic main part assemblies (shown in an exploded 
view with parts in perspective FIG. 4). The first primary part assembly 28 
comprises a rotatable cutting wheel 2 attached to an arm 32 joined to a 
post 34 which has a plurality of grooves 48 thereon. The second part is a 
non-rotating cylindrical body 44 with a spiral configuration on the face 
circumjacent to its bore at one end and with a pivotally mounted spring 43 
biased pawl 46. The third part is a rotatable cylindrical body 45, joined 
to a ratchet wheel 42, which also has a spiral configuration on the face 
circumjacent to its bore at one end which correspondingly mates with the 
similarly spirally configured face of the non-rotating body 44. Ratchet 
wheel 42 is limited to one rotational direction by pawl 37 and biasing 
spring 39 (shown in FIG. 13). Fourth is a slidable cylindrical body 38 
with a spring 72 biased guide pin 64 and spring 35 biased driving pawl 40 
attached at a first end and with a roller wheel 36 attached to the second 
end. 
Also within the cutting wheel body 8 (shown in FIG. 5) are two pipe backup 
rollers 74 retained within an adjustable backup roller body 16. The 
rollers 74 are positioned directly opposing the cutting wheel 2. The 
backup roller body 16 is retained in its passageway within the cutting 
wheel body 8 by an adjusting backup roller body support 14 pivotably 
mounted on an axis coinciding with the centerline of a pivot shaft 12 
having a hex socket within its end. The pivot shaft is joined to the 
backup roller body support 14 which is offset to provide two preset 
positions of the backup rollers 74 relative to the pipe axis. A tension 
spring 76 biases the backup roller body 16 against the flat surfaces of 
the backup roller body support 14. The pivot shaft 12 is located and 
retained in the cutting wheel body 8 by two holes in the passageway walls 
on the same axis as the pivot shaft 12 and parallel to the rotational axis 
of the cutting wheel body 8. 
A stationary semicircular cam track 62 (shown in FIG. 6) is fixed within 
the main tool housing 10 adjacent to the cutting wheel body 8 periphery 
and positioned on the same plane as the cylindrical roller body 38 so that 
it aligns with the roller follower 36. Cam track 62 profile will engage 
roller follower 36 for 90 degrees (one quarter of a revolution) rotation 
of cutting wheel body 8 with respect to main tool housing 10. 
The cutting wheel rapid traversing mechanism 18 (shown in FIGS. 7, 8 and 9) 
comprises a slidable T-shaped body 20, its first end shaped to conform to 
the curvature of the cutting wheel body 8 and a second end coupled to a 
first end of a push-pull type cable 22. The cable 22 second end is coupled 
to a trigger mechanism 4. 
The first end of T-body 20 (shown in FIG. 8 and 9) has a pivotally attached 
swing arm 54. A compression spring 56 is retained between first end 54a of 
the swing arm 54 and the body 20. Compression force of spring 56 is 
sufficient to overcome the compression force of a cutting wheel arm 32 
retract spring 30 re-retained in the cutting wheel body 8. A second end 
54b of swing arm 54 attaches to a roller 26. 
The slidable T-body 20 (shown in FIG. 7) has a biasing compression spring 
78 retained about its round shank. The body 20 is retained by and slides 
through a suitable bushing 24 which is retained within the main tool 
housing 10. 
The cutting wheel body 8 has a conforming C-shaped driving spur gear 80 
suitably attached to one side (shown in FIGS. 2, 3, 10, and 11). Gear 80 
meshes with twin spur gears 82 and 83. Twin spur gears 82 and 83 mesh with 
spur gear 84 which is fastened to the same shaft as is bevel gear 86 
(shown in FIGS. 10, and 11). Large bevel gear 86 then meshes with bevel 
pinion gear 88 suitably attached to the electric motor 60 shaft preferably 
built into tool grip handle. Electric motor 60 is preferably controlled by 
a trigger mechanism 58. 
The electric motor 60 is preferably of the type which, when connected to an 
electronic motor controller, is capable of stopping the motor 60 and hence 
the cutting wheel body 8 rotational movement after a predetermined number 
of revolutions so that it will be in its initial position. 
OPERATION OF INVENTION 
Generally the tool is held in one hand and then the slot or opening in the 
main tool housing 10 is placed around the tubing or pipe to be cut off so 
that the pipe is within the slot or opening (shown in FIG. 1). The user 
then squeezes trigger 4 which instantly traverses the cutting wheel 
tightly against the wall of the pipe to be cut. A second trigger 58 is 
then squeezed activating an electric motor to rotationally drive a 
C-shaped cutting head 8 within the main tool housing 10 that automatically 
feeds the cutting wheel 2 into the tubing wall and when the tube has been 
severed automatically retracts the cutting wheel 2 and stops the cutting 
head in its initial position. 
More specifically, the user must first adjust the pipe backup rollers to 
accommodate either large or small diameter pipe (as can be seen in FIG. 
5). One of the purposes of this adjustment is to enable the cutting wheel 
body 8 to rotate on a concentric axis relative to the pipe central axis. 
The backup rollers are adjusted to accommodate a larger diameter pipe in 
FIG. 5. To adjust for a smaller diameter pipe an alien wrench is inserted 
through a hole 6 located in the main tool housing 10 (as shown in FIG. 1) 
and engages the hex socket in the end of the pivot adjusting shaft 12 
enabling the backup roller body support 14 to be rotated 180 degrees. When 
this is done the backup roller body 16 slides within its passageway 
radially inward in a direction towards the central axis of the pipe and 
ultimately the backup roller body 16 is positioned against a predetermined 
off-set flat position of body 14 for a smaller diameter pipe. 
Next when the tool is positioned over the pipe to be cut a first trigger 4 
is then squeezed (see FIG. 7) to actuate the cutting wheel rapid traverse 
mechanism 18 to instantly traverse the cutting wheel 2 firmly against the 
wall of the tube to be cut. 
More specifically, to traverse the cutting wheel 2 to contact the wall of a 
larger size pipe to be cut (see FIG. 9), the T-shaped body 20 advances 
until it makes contact with the periphery of the cutting wheel body 8. 
T-body 20 is advanced by squeezing a first trigger mechanism 4 coupled to 
the second end of the push-pull type cable 22 having its first end coupled 
to the second end of body 20 thereby sliding it through its bushing 24 
within the main tool housing 10. Then simultaneously the roller 26 applies 
pressure to the periphery of the cutting wheel arm 32 as it rolls along 
the peripheral surface it overcomes the compression return spring 30 
pressure and hence the cutting wheel arm post 34 slides through its bore 
within the cutting wheel body 8 allowing the cutting wheel 2 to make 
contact with the wall of the pipe to be cut. Also, concurrently when the 
T-body 20 makes contact with the periphery of the cutting wheel body 8, it 
also contacts the roller 36 attached to the first end of the slidable 
cylindrical body 38 (FIGS. 4,8,9,12 and 13). The roller 36 (shown in 
phantom lines in FIGS. 8 and 9) attached to a first end of the roller body 
38, moves with the roller body 38 within its bore in a direction 
perpendicular to the cutting wheel body 8 rotating axis. Then, 
concurrently, the spring 35 biased driving pawl 40 attached to a second 
end of the roller body 38 engages a tooth in the ratchet wheel 42 (shown 
in FIGS. 13 through 21.). Hence, then the ratchet wheel 42 will rotate 
opening a gap within the mating surfaces of the non-rotating cylindrical 
body 44 and the rotating cylindrical body 45 (shown in FIG. 14). Then, 
concurrently, the spring 63 biased ratchet pawl 46 pivots and engages one 
of a plurality of grooves 48 in the cutting wheel post 34 and thereby will 
retain the cutting wheel arm 32 with the cutting wheel 2 against the wall 
of the pipe to be cut. 
Further cycling of the trigger mechanism 4 then will produce further 
rotation of the ratchet wheel 42 which is an integral part of the rotating 
body 45. As body 45 rotates about the axis of the cutting wheel arm post 
34, concurrently the post 34 will slide longitudinally through the bore of 
rotating body 45 because body 45 is retained as a flat face circumjacent 
to its bore (at opposite end of spiral configuration) bears against a like 
face 50 in body 8 (as shown in FIG. 22). As body 45 rotates its spiral 
face mates with the like spiral face of the non-rotating body 44 thereby 
producing a lengthening or linear expansion of the bodies 52 as shown in 
FIG. 16. The non-rotating body 44 coupled to the cutting wheel arm post 34 
by the spring 43 biased pawl 46 (as shown in FIG. 15) will then draw the 
cutting wheel sufficiently tight against the wall of the tube to be cut. 
It is additionally noted that, concurrently with the aformentioned trigger 
cycling, swing arm 54 pivots because the compression spring 56 force is 
overcome as the movement of the cutting wheel 2, its arm 32 and post 34 is 
limited because of a larger pipe diameter. 
The same mechanical movement takes place when the cutting wheel rapid 
traverse mechanism accommodates a smaller diameter pipe (shown in FIG. 8) 
with one exception. The compression spring 56 force bearing against the 
first end 54a of the swing arm 54 is greater than the compression spring 
30 force to retract the cutting wheel 2, its arm 32 and post 34 therefore 
the swing arm 54 will not pivot as the cutting wheel 2 traverses further 
in the direction of the central pipe axis to accommodate a smaller 
diameter pipe. 
Once the tool 10 has been positioned around the pipe to be cut off and the 
first trigger mechanism 4 cycled enough times to sufficiently clamp the 
cutting wheel against the wall of the pipe then the first trigger 4 is 
released. Now the second trigger 58 is squeezed activating the electric 
motor 60, (shown in phantom lines FIGS. 7, 10 and 11) which then drives, 
through a gear train (shown in FIGS. 10 and 11), the cutting wheel body 8 
continuously through a 360 degree rotational axis. Within the cutting 
wheel body 8 there is an automatic cutting wheel feeding and retract 
mechanism operable by the rotational movement of the cutting wheel body 8 
about its axis. 
More specifically, as the cutting wheel body 8 is rotationally driven by 
the gear train (FIG. 10 and 11), the roller 36 attaching to a first end of 
the cylindrical sliding body 38 protrudes from the periphery of the 
cutting wheel body aligning with and follows along the profile of the 
stationary cam track 62 fixed within the main tool housing 10 (as shown in 
FIG. 6). The roller body 38 alignment with respect to cam track 62 (shown 
in FIGS. 6 and 12) is maintained by a guide pin 64, which also serves to 
support the compression return spring 72 for the roller body 38, that is 
retained in a slot (not shown) within body 8. 
As roller 36 follows the profile of the stationary cam track 62 and as it 
follows it to its profile peak, the roller body 38 moves within its bore 
in a direction perpendicular to the cutting wheel body 8 rotational axis 
(FIG. 6). Then, concurrently, the spring 35 biased driving pawl 40 
attached to a second end of the roller body 38 engages a tooth in the 
ratchet wheel 42 (shown in FIGS. 13 through 21). Hence, then the ratchet 
wheel 42 will rotate cylindrical body 45 and as its spiral face mates with 
the like spiral face of the non-rotating body 4A thereby produce a 
lengthening or linear expansion of the two bodies 52 along the coaxially 
shared longitudinal axis of the cutting wheel post 34 (as first shown in 
FIG. 14). The cutting wheel post 34 being coupled by the pawl 46 to the 
non-rotating body 44 then will move the cutting wheel 2 incrementally 
0.009 of an inch deeper into the wall of the pipe being cut upon each 
revolution of the cutting wheel body 8 as the non-rotating body 44 moves 
incrementally in the direction of the arrow shown in subsequent 
incremental movements (shown in FIGS. 16,17,18, and 19). 
Then, just after the pipe has been cut off, the rotational body 45 will 
have completed one revolution and as the peak end of its spiral 
configuration continues to rotate past the peak end of the spiral 
configuration of the non-rotating body 44 then the bodies will be 
contracted (shown in FIG. 20) by the force of the compression return 
spring 66 (shown in FIG. 22). Concurrently the spring biased pawl 46 is 
then forced to release the cutting wheel post 34 as it is forced past the 
edge of the spiral configuration near its peak of the rotating body 45 
during contraction (shown in FIG. 21) which is a partial cut-away side 
view of FIG. 20. Then as the cutting wheel post 34 is released, 
concurrently, the cutting wheel 2 returns to its retracted position. 
Concurrently as the cutting wheel 2 retracts the electric motor 60, 
connected to an electronic controlling device, will stop the cutting wheel 
body 8 rotational movement after a predetermined number of revolutions 
thereby positioning the opening in the cutting wheel body 8 so that it 
will coincide with the opening in the main tool housing 10 and be in its 
initial position at the end of each cut-off cycle. 
SUMMARY, RAMIFICATIONS AND SCOPE OF INVENTION 
Thus the reader will see that the subject invention can be used quickly and 
conveniently to cut pipe and tubing, and also installed pipe where space 
is very restricted because it is a self contained, small, light weight 
device. In addition, it provides a way to instantly adjust the tool for 
pipe size with one simple half turn adjustment and to instantly traverse 
the cutting wheel snuggly against the wall of the tubing to be cut by 
simply pulling a trigger. Preferably, the cutting wheel body within the 
main tool housing is driven rotationally by an electric motor controlled 
by squeezing a second trigger in tandem location with the first. Said 
cutting wheel body has a simple automatic cutting wheel feeding and 
retract mechanism within it. Further, by virtue of simple design the 
mechanism can be inexpensively manufactured. 
Although the mechanism of the present invention is preferably power driven, 
a similar mechanism can alternately be contained in a modified embodiment 
of the present invention and be alternately completely manually operated. 
While the above description contains many specifications, these should not 
be construed as limitations on the scope of the invention, but rather as 
an exemplification of one preferred embodiment thereof. Many other 
variations are possible. For example to cut plastic pipe. Accordingly, the 
scope of the invention should be determined not by the embodiments 
illustrated, but by the appended claims and their legal equivalents.