BACKGROUND OF THE INVENTION Conventional hand-operated pipe cutters are conveniently used for cut- ting installed pipe, but as far as is known no currently available power tool has that capability. Moreover, the use of manual pipe cutters requires, in any event, considerable titlle and effort.

SUMMARY OF THE INVENTION The broad objects of the present invention are to provide a power- operated pipe cutter, especially a hand-held tool, and a cutting head therefor, which can readily be used to cut pipe and which can reduce significantly the time and effort required to cut both in-place pipe and also separate lengths of material.

Additional objects of the invention are to provide such a pipe cutter and cutting head which are of relatively incomplex construction and which can readily be manufactured at relatively low cost.

It has now been found that certain of the foregoing and related objects of the invention are attained by the provision of a cutting head comprising : a support member having a supporting portion ; a mounting member supported by the supporting portion of the support member for rotation about a central axis, the mounting member having at least a first channel extending inwardly from the periphery thereof for permitting lateral insertion of a pipe, for dis- position on the central axis of the head ; cutting means mounted on the mount- ing member for rotation therewith and comprising at least two contact ele- ments disposed generally diametrically of the axis and along opposite sides of

the first channel, the cutting means being constructed for varying the spacing between the two contact elements so as to permit such lateral insertion of a pipe therebetween and to enable the contact elements to engage opposite sides of a pipe disposed on the central axis, at least one of the contact elements be- ing a cutting element; and a power-transmission arrangement comprising driven means on a peripheral portion of the mounting member and drive means interengaged with the driven means, the power-transmission arrange- ment including at least one component that effectively spans the entrance to flie first channel at the periphery of the mounting member for enabling con- stant delivery of power to the mounting member.

In certain preferred embodiments the drive means will be constructed to engage the peripheral portion of the mounting member at at least two loca- tions for effecting rotation whereof, the locations being spaced from one an- other a distance greater than the width of die entrance to the channel in the mounting member. The mounting member will usually comprise at least one substantially circular plate, with the peripheral portion (constituting the driven means) comprising a circumferential marginal portion diereoll ; the"at least one"plate may be a sprocket, and die mounting member may comprise an assembly in which a second plate, attached to the sprocket, mounts the cutting means.

In most instances the driven means will comprise an array of teeth ex- tending along the circumferential marginal portion of tlie"one"plate. The cooperating drive means will typically comprise an endless chain disposed to cause a segment thereof, wliich is longer than die first channel entrance widdi <BR> <BR> and which provides tlle"at least one component, "to be in constant engage- ment with the array of teetli. Alternatively, the drive means may comprise a plurality of gears or pillions providing die"at least one component,"one of wliich gears is disposed at each of the two spaced locations referred to. The

drive means may also comprise an endless belt disposed to cause a segment thereof to be in constant driving engagement with me circumferential mar- ginal portion of the"one"plate, which portion is constructed for driven en- gagement by the belt segment.

In other preferred embodiments the"at least one component"of the cutting head will comprise a peripheral segment piece that is dimensioned and configured to effectively span the first channel entrance, the mounting mem- ber being cooperatively constructed for displaceably positioning the segment piece in such a spanning relationship. The segment piece may for example be slidably mounted on the mounting member, and may comprise a further marginal portion of a substantially circular mounting member when so posi- tioned across the channel entrance.

The cutting means employed in the cutting head will preferably include mounting means comprised of a pair of confronting portions, each supporting at least one contact element, and self-centering adjustment means operatively connected to the confionting portions for varying the spacing between the contact elements, the adjustment means being effective for simultaneously moving the contact elements toward and away from one another through sub- stantially equal distances. Biasing means, acting effectively upon at least one of the contact elements (e. g., the cutting wheel, or a jaw supporting it), will normally serve to urge the diametrically opposed contact elements toward one another.

The confronting portions will usually comprise separate jaws, with the adjustment means advantageously comprising a threaded member having op- posite end portions in operative engagement with elements on the jaws for simultaneously moving them in opposite directions. Alternatively, die jaws may have confronting toothed rack portions thereon in operative engagement with a pfiiioii (constituting the adjustment means) rotatably hiteiposed there-

between, again for simultaneously moving the jaws in opposite directions.

Means will desirably be provided for causing the adjustment means to opera- tively engage tlle support member for advancing and retracting the confront- ing portions of the mounting means, upon rotation of the mounting member in one or the other direction.

In certain embodiments, the supporting portion of the support member will be constructed for partially surrounding a pipe, and will have at least a second channel extending inwardly from the periphery of me support member for permitting lateral insertion of a pipe thereinto for disposition on the cen- tral axis of the head.

Preferably, however, the supporting portion will comprise a forward marginal portion on me support member. In such instances me mounting member may comprise at least one substantially circular plate, the peripheral portion referred to may comprise a circumferential marginal portion of the <BR> <BR> "one plate, "and the supporting portion of the support member may form an arcuate channel constructed to seat and engage the circtunferential marginal portion of the one plate of the mounting member.

Other objects of the invention are attained by the provision of a power- operated pipe cutter comprising the cubing head herein described. The cutter will additionally include a body on which the head is disposed, and a motor in operative engagement with the drive means of the power transmission ar- rangement employed. In most instances the cutter will be integrated for fully portable hand-held use, albeit stand-alone units, to which a separate motor or power pack may be coupled, may also be provided ; ilie tool may be either battery operated or driven by line current. The cutter may or may not in- clude a clutch feature, winch can provide additional protection against the stripping of threads, breakage of teeth, etc.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic side elevational view depicting a power- operated, hand-held pipe cutter embodying the present invention; Figure 2 is a diagrammatic j&ont view of the pipe cutter of Figure 1 ; Figure 3 is a rear view of the cutting head of Figures 1 and 2, drawn to an enlarged scale; Figure 4 is a side elevational view of the same cutting head, drawn to the scale of Figure 3 and with the support member fragmentarily illustrated ; Figure 5 is a fragmentary elevational view of the opposite side of the cutting head of the foregoing figures, showing a drive train suitable for use therein ; Figures 6 through 8 are fragmentary diagrammatic views depicting al- ternative drive arrangements suitable for use in the cutting head of the inven- tion; Figure 9 is a diagrammatic side elevational view of a second form of cutting heads embodying the invention.

Figures 10 and 11 are side elevational views corresponding to Figure 4, depicting additional cutting heads embodying the invention, in which a preferred form of support members (fragmentanly illustrated) are employed ; Figure 12 is a fragmentary view of a cutting head similar to that of Figure 11, drawn to a further enlarged scale and having a clutch mechanism incorporated into the jaw-adjusting mechanism ; and Figure 13 is a fragmentary elevational view, in partial section, of the portion of the cutting head depicted in Figure 12.

DETAILED DESCRIPTION OF THE PREFERRED AND ILLUSTRATED EMBODIMENTS Turning initially to Figures 1 and 2 of the drawings, therein illustrated is a power-operated pipe-cutting tool embodying the present invention. The tool consists of a body, generally designated by the numeral 10, upon which are mounted a cutting head, generally designated by the numeral 12, and an electric motor generally designated by the numeral 14; a variable speed elec- hic motor, having forward and reverse capability, will typically be used.

Switch 16 controls energization and direction of the motor 14, and hence of the cutting head 12.

As seen in Figures 3 and 4, the cutting head 10 includes a support member 18, to which is attached a circumferential ring or flange 20. The support member 18 is formed with a channel 22 extending inwardly from the periphery thereof, and the flange has a gap at 21, which registers with the channel 22. A circumferential shoulder 23 is formed in the support member 18, and serves to seat a circular mounting plate 24 for rotation thereon, the plate being retained by the flange 20; means (not shown) is provided for lu- bricating the mating surfaces of the member 18, the flange 20, and me plate 24.

As is seen is Figure 5 (a covering panel, normally provided, having been removed to expose underlying features), a drive sprocket 26 is attached to the inner, or back, side of the mounting plate 24; generally, the sprocket 26 will be spaced slightly from the plate 24 and of somewhat smaller diame- ter (as illustrated) to best accommodate a drive chain. The plate 24 and flic sprocket 26 are slotted at 28 and 29, respectively, such that the resulting channel matches the channel 22 of the support member 18 when the mount- ing assembly (plate 24 and sprocket 26) are rotated to a position of registra- tion therewith. As will be appreciated, me channels 22,28, and 29, and me

gap 21 in the flange 20, enable a pipe section"P"to be inserted laterally into the throat of the cutting head 12 for positioning on its central axis"A".

A pair of journal bloclcs 30 mount the opposite ends of an adjustment screw, generally designated by the numeral 32, upon the outer, front surface of the plate 24. The screw 32 has two threaded end portions 34,36, which extend in opposite directions and which carry right-hand and left-hand threads, respectively, and a take-off gear 38 is affixed centrally thereon.

Also mounted on the plate 24 is an adjustment knob 40 which includes a shaft 42 carrying a worm gear section 44, the latter being in meshing engagement with the take-off gear 38 such that turning of the knob 40 will effect rotation of the screw 32.

Each of two jaws 46,48 has a mounting end portion 50,52 provided with a threaded aperture 53,55, respectively, the threads having opposite pitch directions to cooperatively engage the threaded end portions 34,36 of the screw 32. As will be apparent, turning the knob 40 in one or the other direction will effect rotation of the adjustment screw 32, thereby serving to increase or decrease the spacing between the jaws 46 and 48. A shallow slide channel 37 is formed into the front face of the plate 24, and serves to slidably engage lateral elements of the portions 50,52 for guiding translation of the jaws 46, 48.

The periphery of the knob 40 may be disposed to engage (e. g. , by simple friction) an inner surface 19 of the flange 20 in such manner that rota- tion of the plate assembly 24, 26 will advance or retract the jaws (depending upon the direction of rotation), causing mem to automatically close upon the pipe P, in the initial phase of the cutting operation, and to withdraw from the pipe after the cut has been made; limit means (not shown in these figures) may be incorporated into such a mechanism so as to prevent over-tightening of the jaws upon the pipe.

The upper jaw 46 is slotted at 54 so as to slidably seat the axle 56 of a cutting wheel 58 for limited movement in a radial direction. A pair of ten- sion springs 60 (only one of which is seen, and which are desirably recessed into the sides of the jaw 46) apply constant biasing force upon me shaft 56, urging the cutting wheel 58 toward the central axis of the head ; albeit nor- mally advantageous, the springs 60 may be eliminated if preferred, such as to reduce manufacturing cost.

The lower jaw 48 carries a pair of rollers 62, which are mounted in a substantially diametrical relationship to the cutting wheel 58 for engagement of the opposite sides of a pipe P positioned for cutting. As will be evident, rotation of the plate assembly 24,26 will cause the cutting wheel 58 to cut through the inserted pipe, in cooperation with the rollers 62 ; as cutting pro- ceeds the biasing force of the springs 60 will ensure sufficient advance of the wheel 58 for effecting complete severance, albeit the self-centering adjust- ment mechanism may also be tightened to apply a higher level of force. It will be appreciated that the composition of the cutting wheel 58 will be suita- <BR> <BR> bly selected based upon the nature of the material (i. e. , metal or plastic) to be cut, and that cutting and contact elements other than wheels (e. g., fixed blades or other sharp elements) and rollers (e. g., fixed bearing surfaces) may be employed as appropriate.

As illustrated in Figures 5 through 8, various means may be utilized to effect rotation of the plate 24. In all instances however it will be appreciated that the power transmission arrangement is so constructed that drive force is delivered constantly to the mounting assembly despite the periodic presenta- tion of channels and gaps during its rotation.

Figure 5 shows one form of drive power transmission arrangement suitable for use in die cutting head of the invention. It utilizes an endless chain 64, trained about a simple gear 66 and die larger element 68 of a com-

pound gear, the latter gear including a smaller coaxial element 74 that is en- gaged by the threaded end portion 76 of a worm shaft 72, which is in turn connected (by means not shown) directly or indirectly to the drive motor 14.

It will be appreciated that the width W of the channels 28 and 29 in the plate 24 and sprocket 26, respectively, is of lesser dimension than the length L of the segment of the chain 64 which engages the teeth 25 of the sprocket 26. When me mouth of the channel 29 is presented to the drive chain 64, therefore, the contacting segment spans the channel and ensures the constant delivery of power for effecting rotation of the mounting plate 24.

Figure 6 shows an alternative power transmission arrangement which utilizes an endless chain (or belt) 77, trained about the larger element 78 of a pair of compound gears, the smaller elements 80 of which mesh with the teeth 25 of me sprocket 26. The drive train includes a pinion 75, which is operatively connected (by means not shown) to the motor 14.

Figure 7 illustrates another arrangement in which compound gears are driven by a common shaft, generally designated by the numeral 84 and se- cured in journal blocks 30. The shaft 84 has threaded opposite end portions 86 (with the same pitch direction) in meshing engagement with the larger elements 78 of the two drive gears, the smaller elements 80 of which mesh with the teeth of the sprocket 26. A pinion 88, affixed centrally on the shaft 84, is driven by a worm shaft 90 operatively connected (by means not shown) to the motor 14 and supported, at its inner end, by another journal block 30.

The arrangement shown in Figure 8 is similar to that depicted in Fig- ures 6 and 7, with the exception that a gear 94 drives the compound gears 78, 80 directly. As will be appreciated, in each of the arrangements depicted in Figures 6 through 8 the compound gears are spaced circumferentially a dis- tance greater man the width W of die sprocket channel 29. Again, tills ar- rangement ensures that power is constantly delivered to the sprocket notwith-

standing the gap at the mouth of its channel. Other mechanical components, suitable for use in these power transmission arrangements, will be evident to those skilled in the art and may of course be added or substituted, as appro- priate ; for example, bevel gears may be utilized for making right-angle con- nections.

Figure 9 of the drawings illustrates another embodiment of the inven- tion, in which a displaceable segment piece 96 is employed to effectively bridge the mouth of the sprocket channel 29 (it will be appreciated that, here too, a covering panel has been removed). The segment piece 96 is slidably mounted against the rear surface of the mounting plate 24', and is constrained by guide elements 98 for movement between an opened position (depicted in full line in the Figure) and a closed position (depicted in dotted line), secure- ment in closed position being effected by engagement of upstanding boss 100 on the plate 24'in aperture 102 in the piece 96. An array of teeth 27 extend along an outer edge of the segment piece 96, and cooperate with the teeth 25 of the sprocket 26 so as to ensure constant force delivery from a drive chain or gear system (not shown in dlis Figure).

The power transmission arrangement utilized comprises a compound gear having a smaller element 80 in engagement with a worm shaft 90, and a larger element 78 in engagement with the teeth of the sprocket 24'and seg- ment piece 96. As will be appreciated, because the segment piece 96 bridges the sprocket channel 29 only a single point of power delivery is required.

In furdier respect of Figure 9, a second form of self-centering mecha- nism is illustrated in which relatively short parallel legs 104,106 of L-shaped components provide confronting jaw portions on which are mounted, respec- tively, the wheel 58 and the rollers 62. The relatively long parallel legs 108, 110 of the L-sliaped components carry, on their inner surfaces, toodied rack portions 112, which mesh widi die interposed piton element 114 of a hand

knob, only the shaft 116 of which is seen. As will be evident, rotation of the knob will cause the cutting wheel 58 and the substantially diametrical pair of rollers 62 to move toward or away from one another through equal distances, again to ensure sell-centering contact upon a pipe section disposed therebe- tween ; the L-shaped components are biased toward one another, by a high- tension spring or equivalent means (not shown), thereby maintaining a con- stant, uniform cutting force upon an interposed pipe.

Turning now in detail to Figures 10 through 13 of the drawings, there- in illustrated are preferred embodiments of the cutter of the invention. As in the preceding figures, elements depicted that are common to the embodiments previously described bear the numbers already assigned, and a cover plate has again been removed from the head depicted in Figure 10.

The cutter heads of these embodiments utilize a mounting plate, gener- ally designated by the numeral 120, which is formed with a circumferential array of teeth 122 and a marginal circular groove 124 formed into both of the opposite sides of the plate. The support members, generally designated by the numeral 126, comprise front and rear panels 128, 130, which terminate, respectively, at a leading arcuate edge 129 and a leading rectilinear edge 131, and both extend only a short distance beyond Hie circumferential margin of the mounting plate 120. A channel 134 is defined between the panel 128, 130, and serves to receive the marginal edge portion of the plate 120. Con- fronting arcuate ribs 132 project inwardly from me panels 128, 130, and are received in the grooves 124 formed in die plate 120, thereby serving to ro- tatably support the plate on the support member 126; a portion 136 of the lower panel 12 extends beyond the leading edge 129 of the upper panel 128 and thereby provides additional support for the plate 120. It will be appreci- ated that me marginal edge portion of the plate 120 could alternatively be formed with a circumferential-rib (or like structure) seated and engaged

within corresponding grooves formed into the surfaces of the panels 128, 130.

In the embodiment of Figures 11-13, an arcuate friction element 138 is secured to the top surface of the upper plate 128, and is engaged by a fiiction wheel 140 mounted upon a shaft 142. The shaft 142 is in turn supported by a journal block 144, and carries a worm element 146 on one end, which is fil meshing engagement with the adjustment screw 32. A first clutch disk 148 is secured to the shaft 142, and cooperates with a second, movable clutch disk 150 to clamp the friction wheel 140 therebetween. For this purpose a coil spring 152 is disposed about the shaft 142 with its opposite ends bearing upon washers, 154, one of which washers lies against the adjacent clutch disk 150 and the other of which lies against an adjustment wing nut 156; the nut 156 is threadably engaged on me threaded end portion 158 of the shaft 142.

As will be appreciated, me friction wheel 140 is clamped between the clutch disks 148 with sufficient force (the level of which is of course con- trolled by the position of the wing nut 156) to cause the shaft 142 to rotate, as driven by engagement of the wheel 140 with me motion element 138 as the plate 120 rotates through me support member 126. Tills will cause the screw 32 to turn in one or the other direction (intermittently, when the wheel 140 is in contact with the element 138), depending upon the direction of rotation of the plate 120, advancing or retracting the jaws 46,48 so as to effect cutting or withdrawal of the cutting element 58, as appropriate. When the jaws have either advanced or retracted sufficiently to encounter resistance to further movement, the friction wheel 140 will slip on the shaft 142 and thereby pro- vide one form of limit means referred hereinabove.

It will also be appreciated from the foregoing description that, albeit usually beneficial, die cutter need not include a clutch, reliance for the avoid- ance of damage being dependent instead upon die skill and care of die opera-

tion or upon the use of a motor having an incorporated clutch. Also, forms of clutches other titan that which is illustrated in Figures 12 and 13 can of course be utilized, as will be evident to those skilled in the art. For example, an adjustable clutch having a range of torque settings, of me kind mat is in widespread current use on screwdrivers and like electrically powered hand tools, could be incorporated into the instant pipe cutter if so desired.

Thus, it can be seen that the present invention provides a power- operated pipe cutter, especially a hand-held tool, and a cutting head therefor, which can readily be utilized to cut installed pipe and which can reduce sig- nificantly the time and effort required to cut both in-place pipe and also sepa- rate lengths of material. The pipe cutter and cutting head are of relatively incomplex construction, and can readily be manufactured at relative low cost.