US2989806A

US2989806A - Flexible conduit cutting apparatus

Info

Publication number: US2989806A
Application number: US61755A
Authority: US
Inventors: James F Davis
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-10-10
Filing date: 1960-10-10
Publication date: 1961-06-27
Anticipated expiration: 1978-06-27

Description

June 27, 1961 2,989,806

J. F. DAVIS FLEXIBLE CONDUIT CUTTING APPARATUS Filed Oct 10, 1960 5g immm mil-n" v JAMES F DAVIS INVENTOR.

AGENT United States Patent 2,989,806 FLEXIBLE CONDUIT CUTTING APPARATUS James F. Davis, 638 Howard St., Glendale 6, Calif. Filed Oct. 10, 1960, Ser. No. 61,755 '10 'Claims. (Cl. 3090.5)

The present invention relates generally to a flexible conduit cutting apparatus and relates more particularly to such an apparatus that is adapted to several all or portions of sections of metal types of coiled electrical conduit or conduit shielding.

In electrical wiring of the type commonly used in dwellings, factories, farms and the like, it is the practice to encase or shield such wiring in metal conduits. Such conduits may be either of the solid types or may be of the flexible variety constructed from a continuous helical wrap of interlocking metallic material. The solid conduit presents no problems when cut; however, it is extremely difiicult to cut the described flexible conduit, inasmuch as dangerous sharp edges are created when using pinch type cutters and the material is diflicult to hold when using a hand saw type cutter. Furthermore, this flexible conduit or cable material must be cut in a particular manner to separate sections thereof, meet electrical standards and to prevent undesirable unwinding of the material. Still further, this flexible conduit material is often supplied with integral conductors therein and the depth of cut through the conduit must be controlled to avoid contact with the conductors and damage thereto.

Prior attempts toward the construction of various types of tools for cutting flexible conduit have taken the form of hand saws, pinch cutting devices and the like. Power tools have also been suggested; however, these structures have been heavy, expensive and difficult to use. It is necessary that such a tool be of such a nature as to enable easy ownership by individuals, be simple in construction and operation, be free from maintenance problems, operate efficiently and be of a portable nature enabling use by skilled and unskilled electricians.

It is therefore one important object of the present invention to provide an improved cutting apparatus for flexible conduit material.

It is another important object of the invention to provide a cutting apparatus for flexible conduit that is simple in construction, reliable in operation, efficient in use' and which is portable and adapted for use by electricians.

Still another object of the invention is to provide a cutting apparatus for flexible conduit wherein means are provided for supporting the material to be cut in a desired location and attitude and for cutting all or a portion of the conduit without the necessity for complex manual aligning of the conduit.

A further important object of the invention is to provide a novel flexible conduit apparatus that may be classed as a power hand tool and wherein a trigger mechanism associated with a handle serves to provide actuation means for advancement of a cutting wheel and wherein a mechanical movement amplifier is employed to enable limited necessary movement of the trigger.

Another object of the invention is to provide a flexible conduit cutting apparatus having a rotatable cutting wheel together with means for advancing and retracting the wheel and for protecting an operator from accidental injury during use of the apparatus.

Other and further important objects of the invention will become important and apparent from the disclosures in the following detailed specification, appended claims and accompanying drawing, wherein:

FIGURE 1 is a side elevational view of the present flexible conduit cutting apparatus;

FIG. 2 is an enlarged longitudinal sectional view of the apparatus;

FIG. 3 is a transverse fragmentary sectional view through the block and frame portion of the apparatus, as dtaken substantially as indicated by line 3-3, FIG. 2; an

FIG. 4 is a fragmentary sectional view showing the conduit holding and supporting mechanism and the means for driving a cutting wheel and taken substantially as indicated by line 4-4, FIG. 2.

With reference to the drawing wherein like numerals refer to like components, the present cutting apparatus for flexible conduit material is shown as indicated generally at 10. As shown in FIGS. 1, 2 and 4, the apparatus is adapted for use with flexible conduit indicated at C. The conduit C is in the form of a helical wrap of interlocking strips of metallic material to form a continuous tube. While the conduit shown is of the plain type, it is to be noted that the present apparatus may be used with electrical conduit having integral conductors without injury to these conductors.

With reference primarily to FIG. 2, the present cutting apparatus 10 includes a frame 11 that is generally longitudinally elongated and which has a handle portion 12 integraly depended from one end thereof. The handle portion 12 is suitably shaped to provide a hand grip and has a hollow interior area 13. The frame 11 is provided with longitudinal ways 14 on lateral sides thereof which serve to support and guide a guide block 15. The guide block 15 has suitable grooves 16 that are adapted for disposition over the ways 14 and are slidable thereon. The guide block 15 is spaced from an upper surface of the frame 11 as at 17 to reduce frictional loads tending to retard movement of the block on the frame and the ways 14. The guide block 15 has a planar upper surface 18 and an inclined lower surface 20. The frame 11 also has an inclined surface 21. The

inclined surfaces

20 and 21 laterally cross each other.

The handle 12 has a forwardly directed opening 22 in which a trigger 23 is positioned. The trigger is limited in its possible movement from the handle by means of tabs 2A that engage the inner surface of the handle 12. Thetrigger 23 is pivotally connected to a lever 25 as at 26, the lever 25 being pivotally secured to the handle 12 as at 27. An upper end of the lever 25 is pivotally secured to a link 28 as at 30, the link 28 extending forward over. a rear portion of the frame 11. The free end of the link 28 rota-tably supports a roller 31 on a shaft 32, with the roller 31 being disposed in contact with the

inclined surfaces

20 and 21 of the block 15 and the frame 11 respectively. The roller 31 is urged into contact with the

surfaces

20 and 21 by means of a tension spring 33 that is connected between the link 28 and the frame 11. The block 15 is urged rearwardly by means of a pair of tension springs 34 that are connected between the block 15 and the frame 11. Rearward movement of the block 15 relative to the frame 11 is limited by engagement with the roller 31 and the limit of movement of the trigger 23 as defined by the tabs 24. The springs 34 exert a greater force than the spring 33.

It may thus be seen that upon inward movement of the trigger 23, the lever 25 will be moved to move the link 28 and the roller 31. Movement of the roller 31 serves to move the block 15 on the frame 11 with the roller 31 being maintained in constant contact with the

inclined surfaces

20 and 21. With movement of the trigger from the solid to the dotted line positions thereof, the block 15 will also be moved from the indicated solid to the dotted line positions. 'It is to be noted that a greater distance of movement of the block is obtained for a given distance of movement of the trigger, due to the particular construction and the interaction of the roller 31 with the

inclined surfaces

20 and 21.

The surface 18 of the guide block 15 serves to support an electric motor 35 that is secured thereto by means of bolts 36, for example. The motor 35 is connected to a source of electrical energy by leads 37 which extend through the handle 12. A switch 38 in the handle 12 serves to energise the motor 35. The motor 35 has an output shaft 40, FIG. 4, that is journalled in and enclosed by a housing 41. The housing 41 is depended from and secured to the motor 35. As shown in FIG. 4, a gear enclosure 42 is formed on the free end of the housing 41. The enclosure 42 serves to encase a pair of

bevel gears

43 and 44, the gear 43 being mounted on the output shaft 40 and the gear 44- being mounted on a stub shaft 45 that is journalled in the enclosure 42. The axis of the stub shaft 45 is normal to the axis of the output shaft 40. One end of the stub shaft 45 remote from the gear 44 extends beyond the enclosure 42 and has a cutting wheel 46 secured thereto. While the cutting wheel is shown as having a plurality of teeth, it is to be understood that an abrasive wheel or the like may be used without departing from the spirit and scope of the invention. It may thus be seen that operation of the motor 35 will serve to rotate the cutting wheel 46.

As shown, a conduit supporting member 47 is secured to the frame 11 at the end thereof remote from the handle 12. The supporting member is retained in position by means of screws 48 which engage the frame 11. The member 47 extends outwardly and upwardly from the frame 11 and has a free end that is bifurcated as at 50 and semicircularly grooved as at 51 for reception of the conduit C. The grooves 51 serve to support the conduit C at an angle to the axis of rotation of the cutting wheel 46, whereby to dispose the individual convolutions of the conduit at the proper angle to the cutting wheel 46 for the severing of at least one of the metallic convolutions and thus separating the conduit. It is also to be noted that the conduit is positioned in the grooves 51 in such a manner as to dispose only an upper portion thereof in the path of the cutting wheel 46. When different sizes of conduits are used, different supporting members 47 are employed to position the particular conduits in the desired locations. The conduit C is retained in the grooves 51 by means of a bifurcated finger 52 that is of spring material and is attached to the surface 18 of the guide block 15 by means of screws 53, or the like. The ends of the finger 52 are positioned on lateral sides of the cutting wheel 46 and the bifurcation 50 in the supporting member 47 provides clearance for the wheel.

Accordingly, when the trigger 23 is depressed, the guide block 15 will be advanced, also advancing the motor 35 and the rotating cutting wheel 46 to sever a selected portion of the flexible conduit C. When the trigger 23 is released, the tension springs 34 return the cutting wheel, block, linkage and the trigger to their original positions.

In order to protect the operator from accidental injury when operating the present apparatus, a cover 54 is positioned over the retracted and extended positions of the cutting wheel 46 and over the motor 35, block 15 and linkage defined by the lever 25 and the link 28. The cover 54 is secured in position by means of screws 55 secured to the frame 11.

It may thus be seen that the present cutting apparatus for flexible conduit serves to accomplish the cutting action with a minimum of parts and with the efficient and reliable operation that is to be expected from simplified construction. The simplified construction also enables inexpensive manufacture of the apparatus and easy ownership by the average electrician. The apparatus is also extremely portable and need not be used only in a shop or other fixed location. The conduit is securely retained in position during cutting thereof and may be easily inserted in and removed from the supporting structure. The apparatus is also rugged in construction to withstand the normal usage to which it is put. The few coacting components need little maintenence attention and little lubrication thus to insure long life for the apparatus.

Having thus described the invention and the present embodiment thereof, it is desired to emphasise the fact that many modifications may be resorted to in a manner limited only by a just interpretation of the following claims.

I claim:

1. A cutting device for flexible electrical conduit comprising, in combination: a frame structure; handle means disposed from said frame structure; a guide block slidably carried by said frame structure; a manually actuable trigger carried by said handle means; a mechanical linkage disposed between said trigger and said guide block whereby, upon actuation of said trigger, to move said guide block on said frame; an electric motor mounted on said guide block, said motor having an output shaft; a housing disposed about said shaft and secured to said motor; a cutting wheel rotatably carried by said housing and operably connected for driving rotation with said shaft, said wheel being extensible beyond an end of said frame upon movement of said guide block; and means carried by said frame for supporting said conduit in a path of said wheel.

2. A cutting device according to claim 1 wherein said frame and said guide block each have facing inclined surfaces, said linkage having a member engaging said surfaces whereby to amplify a distance of travel of said guide block relative to a distance of linear movement of said linkage member.

3. A cutting device according to claim 2 wherein said member of said linkage comprises a roller engageable with said inclined surfaces.

4. A cutting device according to claim 3 wherein a cover encloses said linkage, said motor and said wheel, said cover being attached to said frame and extending over an extended position of said wheel.

5. A cutting device according to claim 3 wherein spring means are provided between said guide block and said frame for returning said block after movement by actuation of said trigger.

6. A cutting device according to claim 1 wherein said guide block is guided relative to said frame by ways carried by said frame and engageable with grooves in said guide block.

7. A cutting device according to claim 1 wherein said supporting means for said conduit includes members spaced on lateral sides of said path of said wheel and in angular relation relative to a normal of said path whereby to support said conduit at said angle.

8. A cutting device according to claim 1 wherein bifurcated leaf spring means are carried by said frame and cooperable with said supporting means for retaining said conduit in said supporting means.

9. A cutting device according to claim 8 wherein said supporting means is disposed at an angle to a normal of said path of said wheel.

10. In a cutting device for flexible electrical conduit, the combination of: an elongated frame structure having longitudinal ways thereon; a handle disposed from said frame structure; a guide block slidably carried by said frame structure and having grooves engageable with said ways; opposed inclined surfaces on said guide block and said frame; trigger carried by said handle; a pivoted linkage carried by said frame and disposed between said trigger and said guide block, said linkage having a roller on an end thereof, said roller being disposed at a junction of said inclined surfaces; spring means disposed between said guide block and said frame for biasing said guide block toward said roller, actuation of said trigger serving slidably to move said guide block through said linkage; an electric motor mounted on said guide block remote from said frame; said motor having an output shaft; a journal housing disposed about said motor shaft and secured to said motor; a cutting wheel carried by said housing and rotatably disposed with an axis thereof normal to an axis of said shaft; a right angle 5 gear drive between said shaft and said wheel, said wheel being extensible beyond an end of said frame upon movement of said guide block; supporting means for said conduit, said supporting means being carried by said frame and disposed to support said conduit at an angle to an axis of rotation of said cutting wheel; a bifurcated leaf spring carried by said frame adjacent said supporting means and having an end portion engageable with said conduit whereby to retain said conduit in said supporting means and in a path of travel of said wheel; and a cover guard carried by said frame and enclosing said linkage, said motor and an extended and retracted position of said wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,942,766 OBanion Ian. 9, 1934 2,031,470 Eck et al Feb. 18, 1936 2,l7|6,646 Thatcher Oct. 17, 1939 2,202,085 Brown May 28, 1940 2,654,941 Schlemer Oct. 13, 1953 2,674,027 Kosinski Apr. 6, 1954