PIPE CUTTER

Abstract: A free-standing pipe cutter has a stand formed of three legs (13-15), supporting a split clamping sleeve (10), part of which is secured to a guide sleeve (12) for a rotary cutter assembly (11) rotatable on an annular path, so that a cutter blade (32) engages a pipe (20) clamped by the sleeve, the cutter blade being advanced during such rotation to cut the pipe progressively more deeply, in use, by rotation of a manual operating member (36, 37) relative to the cutter. The legs of the stand are capable of being re-positioned to convert the pipe cutter from right handed operation to left-handed operation or vice versa.

Description: " PIPE CUTTER" This invention relates to a pipe cutter, particularly for non-metallic pipes, such as those made of plastics materials. Presently on construction sites and the like plastics pipe of a diameter of 100 mm and upwards, used, for example for drainage and sewer applications, is usually cut to length by means of a hacksaw. Chamfering of a pipe end for external reception of a O-ring seal is also carried out using the hacksaw or by manipulating the end against a rough surface. These relatively crude operations are carried out as a result of the absence of a suitable purpose-made cutter device for use with non-metallic pipe. Pipe cutters, generally in the form of hand held tools, designed specifically for metallic pipes are normally of no use with non-metallic pipes, often due to deformation of the non-metallic pipe during the cutting operation. An object of the invention is to provide a pipe cutter which overcomes the above mentioned problems . According to a first aspect of the invention there is provided a pipe cutter which is free-standing and comprises clamp means carried on a stand intended to engage the ground or equivalent surface. Preferably the stand is in the form of a tripod with two legs thereof connected together by a brace intended for use as a horizontal foot-rest when the pipe cutter is in use. Desirably said two legs and the other leg respectively are connected to identical members secured to the clamp means, so that the legs can be arranged to provide a right or left handed pipe cutter as required. According to a second aspect of the invention there is provided a pipe cutter having clamp means in the form of a part-flexible, split annular clamping sleeve, means for operating the clamping sleeve between an open position, in which a pipe to be cut can be inserted therein, and a closed position, in which the inserted pipe is tightly held by the clamping sleeve, and guide means defining an annular path about which rotary cutter means are guided, in use, upon angular movement of said cutter means to cut the pipe, part of said clamping sleeve being secured to said guide means. Preferably the annular path is defined by an external annular surface of the guide means, which surface is engaged by an inner annular surface of the rotary cutter means. Desirably the rotary cutter means has cutter blade adjustment means for moving the cutter blade radially inwardly as the cutting of the pipe takes place, in use. The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a pipe cutter of the invention being used to cut a pipe; Figure 2 is an enlarged, cross-sectional side view of the pipe cutter, with part of a pipe to be cut also being shown; Figure 3 is an exploded view of part of rotary cutter means of the pipe cutter; Figures 4A and 4B are respective opposite side views of part of the pipe cutter; and Figures 5A - 5C show a bracket for securing legs to a clamping sleeve of the cutter, and one leg and two legs secured to the bracket respectively. Figure 1 shows a pipe cutter of the invention having an annular clamping sleeve 10, a cutter assembly 11 rotatable on a guide sleeve 12, connected to the clamping sleeve 10 as will be described, and three support legs 13, 14, 15 respectively arranged to support the clamping sleeve on the ground or other equivalent surface, so that the pipe cutter is free-standing. The provision of a specially designed stand is important in that known hand held pipe cutters have not proved effective, largely because of the difficulty involved in both holding the clamp tube and also operating the cutter. This is a consequence of the torque application point being spaced from the position at which the tube is held. By making the pipe cutter and a ground engaging stand as an integrated entity, with the stand being carefully designed to give the correct support for both very long and also very short pipes, an effective pipe •cutter is produced. The clamping sleeve 10, shown in Figure 2 and also in Figures 4A and 4B is made of metal and is longitudinally split along its length, as shown as 16. The inherent flexibility of the sleeve is such as to open the split. Complimentary parts of a toggle mechanism 17 are disposed adjacent respective opposite sides of the slit, and this toggle mechanism can be operated to reduce or close the split by contracting the sleeve 10. Any suitable form of toggle mechanism, such as an over-centre mechanism, can be used and the mechanism shown in Figure 1 is thus only illustrative. In the embodiment shown in the drawings, the split is at the centre of the part of the sleeve which is directed forwardly, in use, of the pipe cutter. As viewed in Figure 1, and also as in Figure 2, part of the periphery of the right hand end of the sleeve 10 is welded, as indicated at 18, or otherwise secured, to the guide sleeve 12. This left hand end of the guide sleeve 12 extends generally axially relative to the sleeve, but as shown in Figure 2 the internal diameter of this end part is slightly greater than the internal diameter of the clamping sleeve in its clamping position, so that there is a slight clearance between this internal surface of the guide sleeve 12 and an inserted and clamped pipe. The opposite end of this guide sleeve 12 is turned radially outwardly to form a radial flange 19 as shown in Figure 2. Peripherally this guide sleeve 12 is, like the clamping sleeve 10, made of metal. As shown best in Figures 4A and 4B, the clamping sleeve 10 is welded to the guide sleeve 12 around the lower semi-circular part of the sleeve 10 at its right hand edge. Figure 4A shows that the welding 18 starts at the bottom of the split and extends to the bottom part of the sleeve which is visible at the front of the pipe cutter. Figure 4B shows that the welding extends at the rear of the sleeve up to approximately 180° from the lower part of the split at the front of the sleeve. The welding would normally not be continuous over this arc, but would be sufficient securely to join the lower half of the clamping sleeve 10 to the guide sleeve 12. Thus the upper half of the clamping sleeve 10 is free to flex on operation of the toggle mechanism 17 to close the split down as mentioned above. In fact most of the flexing will, in practice, occur at the free end of the s.leeve adjacent the upper edge of the split shown in Figure 4A. This upper half of the sleeve will be slightly spaced at its right hand edge, as viewed in Figure 4A from the-guide sleeve 12, although the gap has been somewhat exaggerated for clarity in Figures 4A and 4B, it being sufficient that this part of the sleeve is free to move on operation of the toggle mechanism. Accordingly, when a pipe 20 is inserted with the toggle mechanism not operated, it passes with clearance into the sleeve 10 and sleeve 12, with the interior surface of at least part of the upper portion of the clamping sleeve 10 being radially aligned with the interior surface of the adjacent part of the sleeve 12. Operation of the toggle mechanism 17 closes the clamping sleeve to the position shown in Figure 2 where the pipe is tightly engaged in the sleeve 10. The cutter assembly 11 is made up of a main rotatable cutter plate 21, a rear connecting plate 22 and an adjustable cutter 23 in a guide housing 24. Figure 3 shows the cutter plate 21 which is metallic and has a large part of its periphery of circular form, but is formed with an outward extension portion 25 which supports the housing 24 for the cutter 23. The circular part of the plate 21 has a central circular aperture 26 therein, this aperture being slightly larger in diameter than the pipe intended to be cut by the pipe cutter, in use, as shown in Figure 2, so that the pipe can pass through this aperture with clearance. The guide housing 24 is an elongate member having a cross section of inverted lipped-channel shape, the channel being generally square or rectangular. A series " of accurately positioned holes 27 are provided in plate 21 to locate the guide housing relative to the aperture 26, corresponding holes 28 in the lips 29 of the housing being, in use, aligned with the holes 27 so that the housing can be secured to the plate 21 by means of screws 30 through the aligned holes 27 and 28. These screws can be secured by any suitable means, and indeed the housing could be fixed to the plate by other means, such as rivets . The adjustable cutter 23 is made up of a metallic block 31 at one end of which is a longitudinally directed cutting blade 32 formed as a continuation of one side 33 of the block. A transverse cutting or chamfer blade 32a is formed at an adjacent side of the. block at 90° to said one block side 33, this being formed at, for example, an angle of about 120° to cutting blade 32. The end of the block remote from its end where the blade 32 is formed, has an internally screw threaded hole 34 extending centrally into it and into this is engaged an externally threaded end 35 of an adjustment member having a stem 36 with a gripping knob 37 at its end. The stem has an annular slot 38 spaced a short way from the beginning of the threaded end 35 and into this projects a generally D- shaped projection 39 formed by pressing down material of the base of the channel forming the housing 24. By this means the adjustment member is held against longitudinal movement r rotational movement by means of the knob, however, being permitted. Accordingly, rotation of the stem 36 causes rotation of the threaded end 35, with consequential radial sliding movement of the block 31, and thus the cutting blade 32, towards or away from a pipe 20 held by the clamping sleeve. The rear connecting plate 22 has at its right hand end, as viewed in Figure 2 , a radially extending flange part 40. The plate 22, like the plate 21, is of metal and is circular, having a diameter equal to the diameter of the circular part of the plate 21 referred to above. As shown in Figure 2, the upper part of the plate 22 is aligned with the part of the outer periphery of the plate 21 which is. circular and as indicated by the lines 41, these two plates are connected together by any suitable means, such as members equivalent to the screws 30 through aligned holes in the two plates respectively, the flange 40 engaging against the opposite side of the plate 21 to which the housing 24 is secured. The plate 22 extends radially inwardly relatively to the sleeve 10 and also axially rearwardly relative to the side of the plate carrying the housing 24, and this provides a space between the plates 21 and 22 into which the flange 19 is received. The other end of the plate 21 extends generally axially and from this end a portion of the plate 22 extending towards the flange part 40 matches the shape of the outer surface of the flange 19 and is arranged relative to said surface of the flange 19 so that it bears thereon, in use, as the cutter assembly 11 is rotated, in use. Thus the outer surface of the flange 19 which the plate 22 uses as a bearing defines an exact annular path for the cutter assembly and thus the cutter 32 at its tip defines an exact circle so as accurately to cut a circular pipe 20. Figure 5A shows a bracket 42 formed as a metallic pressing, two of said brackets being secured, preferably by welding, to the lower half of the clamping sleeve 10, as shown in Figures 1 and 2, to connect the legs 13, 14 and 15 to the clamping sleeve to form the free-standing pipe cutter of the invention. As can be seen in Figure 5A, and also in Figures 5B and 5C, the bracket 42 has a cross section generally in the form of a lipped channel, the channel having a base 43 with sides 44, the lips 45 having slightly turned over ends 46 extending back towards the base 43. At one end of the bracket, which is lowermost in use, as shown in Figure 2, the base is cut away for a short distance. The lips 45 have respective central holes 47 therein and aligned holes 48 are provided in the sides 44 respectively at a position where the base is cut away, as shown in Figure 5A. One bracket 42 is welded to a front of the lower half of the clamping sleeve 10 at a position substantially as shown in Figure 1, the bracket being secured as shown in Figure 5C with the ends 46 directed rearwardly. Another bracket 42 is similarly secured to the rear of the bottom half of the clamping sleeve 10, as shown in Figure 2 , the bracket being secured as shown in Figure 5B with the ends 46 directed towards the front of the pipe cutter, i.e. with the ends 46 of the two brackets facing each other. The legs 13 and 14 are attached to the front bracket as shown in Figure 5C, by nuts and bolts passing through the holes 47 and corresponding holes through the respective legs. As shown in Figure 1 these two legs are preferably integrally formed together in one piece with a lower connecting brace part 49 which is intended for use as a horizontal foot-rest with the pipe cutter is in use for a user to apply force, thereby overcoming the problem mentioned herein in relation to a user being able both to hold a pipe being cut and also apply sufficient force to operate a cutting device at the same time. The arrangement shown with the brace and the splayed legs 13, 14 is particularly advantageous. The leg 15 is connected to the rear bracket as shown in Figure 5B, the leg 15 being secured in the channel rather than at opposite sides thereof as is the case with the support legs 13 and 14. The leg is secured by a nut and bolt arrangement, the bolt passing through the aligned holes 48 and also similarly aligned holes in the tubular leg 15. As will be appreciated from Figure 2 and Figure 5A, the cutting away of part of the base at the location of the holes 48 enables the leg 15 to be pivoted forwardly, as viewed in Figure 1, when required, to facilitate both transport and storage of the pipe cutter when not in use, the edge of the base at the end of the cut away portion defining a stop for the pivoting of the leg about the bolt which, as shown in Figure 5B, passes through it and provides a pivoting point. To prevent the leg 15 pivoting freely when it is desired to move the pipe cutter without altering the leg positions, a retaining spring means, such as a Terry washer could be provided. This would enable easy release and engagement of a leg 15 as and when required. By using the same bracket 42 at both the front and rear of the lower part of the clamping sleeve 10, it is possible to change the handing of the pipe cutter in a very easy manner, in that it is merely necessary to undo the nuts and remove the bolts shown in Figures 5B and 5C to allow removal of the legs, the connected legs 13 and 14 then being engaged with the rear bracket at opposite sides of the channel, the leg 15 being engaged with the front bracket in the channel by way of its pivot bolt now passing through the aligned holes 48 in this front bracket. Thus the arrangement of legs is reversed so that in fact a left-handed operator can operate the cutter assembly whilst at the same time using the brace 49 as a horizontal foot rest, the leg 15 still being pivotable towards what, for a left handed operator, would now be the 'front' of the pipe cutter, the Terry washer being similarly provided as previously described for right handed operation of the cutter. The legs are preferably hollow steel tubes. In use, it is intended that the pipe cutter is used on a fairly flat, level surface, so that the legs are firmly supported. The cutter can handle pipes up to about 2 meters without the pipe needing support, but with pipes longer than this an accessory in the form of a tripod could be used to support its free end. The pipe 20 to be cut is, as previously described, slid into the clamping sleeve with the toggle inoperative, the pipe passing through the sleeve 12 and the aperture 26 in the plate 21. When the length of pipe to be cut has been determined and the pipe correctly positioned, the toggle' is operated so that the sleeve very tightly clamps the pipe in position. As stated the relationship between the split clamping sleeve and the guide sleeve 12 is such that once the pipe is tightly clamped the guiding of the cutter assembly 11 by the sleeve 12 is accurate in that the cutter 32 follows a circular path when the assembly 11 is rotated. Next, the knob 37 is rotated to cause the block 31 to slide along its guide housing until the cutting blade 32 engages the pipe 20. The cutter assembly 11 is then rotated by means of the knob 37 so as to begin the cutting of the pipe as the blade 32 produces a groove 50 therein. Thereafter the blade 32 is advanced further as the rotation of the cutter assembly continues, producing an ever deeper groove, until the groove breaks to the pipe interior and the pipe is cut. The block can then be further advanced so that chamfer blade 32a engages the cut end of the pipe so that further rotation of the cutter assembly produces a desired chamfer, this normally being required to seat an O-ring seal when the cut pipe has its end received in a further pipe or the like. The blade 32a could be omitted if not required. Thereafter the knob 37 is rotated to move the block 31 back in its housing so that the blade 32 is clear of the pipe. The toggle mechanism is then operated to "open" the clamping sleeve and the pipe held in the sleeve, having been accurately cut, and possibly provided with a chamfer at its end, in a single operation, is removed. Although intended to be sold assembled, the pipe cutter could be supplied in kit form. The cutter arrangement is designed for minimum backlash and an adjustment of for example, 4mm for wear is allowed. It is not intended that the cutting end chamfer blades will be renewable, but this may be possible, despite the low cost of replacing the whole product. It is intended that one pipe cutter is used to cut one size (diameter) of pipe only, there being really only two standard sizes of plastics drainage pipe present which are greater than 100 mm, and thus not conveniently not cuttable by a hacksaw. However the pipe cutter may be adaptable to enable it to cut (and chamfer) more than one size.

Claims: CLAIMS 1. A pipe cutter which is free-standing and comprises clamp means carried on a stand intended to engage the ground or equivalent surface. 2. A pipe cutter as claimed in Claim 1, wherein the stand is in the form of a tripod with two legs thereof connected together by a brace intended for use as a horizontal foot rest when the pipe cutter is in use. 3. A pipe cutter as claimed in Claim 2, wherein said two legs and the other leg respectively are connected to identical members secured to the clamp means, so that the legs can be arranged to provide a right or left handed pipe cutter as required. . A pipe cutter as claimed in Claim 3, wherein each member is of lipped channel form, said two legs being connected to the lips of the channel respectively and said other leg being connected to the channel between sides thereof. 5. A pipe cutter as claimed in any one of Claims 2 to 4, wherein the other leg is pivotable towards said two legs from its normal operating position in use. 6. A pipe cutter as claimed in Claim 6, wherein means are provided for reasonably securing the other leg in its normal in use position. 7. A pipe cutter as claimed in any one of the preceding claims, wherein the clamp means is split clamping sleeve moveable between an open position to receive a pipe to be cut and a locked closed position in which the received pipe is tightly clamped by the sleeve. 8. A pipe cutter as claimed in Claim 7, wherein part of the sleeve is secured to a guide for a rotatable cutter assembly. 9. A pipe cutter as claimed in Claim 8, wherein the cutter assembly has a cutter blade moveable longitudinally of a cutter housing into or out of engagement with a pipe clamped by said sleeve, in use. 10. A pipe cutter comprising clamp means in the form of a part-flexible, split annular clamping sleeve, means for operating the clamping sleeve between an open position, in which a pipe to be cut can be inserted therein, and a closed position, in which the inserted pipe is tightly held by the clamping sleeve, and guide means defining an annular path about which rotary cutter means are guided, in use, upon angular movement of said cutter means to cut the pipe, part of said clamping sleeve being secured to said guide means. 11. A pipe cutter as claimed in Claim 10, wherein the clamping sleeve is secured to the guide means around only half of the sleeve's outer periphery at one of its ends. 12. A pipe cutter as claimed in Claim 11, wherein said securement extends for 180 " from the position of one side of said split, which extends longitudinally of the sleeve, in a direction away from the other side of the split, so that the free longitudinal edge of the split so formed is moveable in a direction to open or close the split by use of said operating means. 13. A pipe cutter as claimed in any one of Claims 10 to 12, wherein the annular path is defined by an external annular surface of the guide means, which surface is engaged by an inner surface of the rotary cutter means. 14. A pipe cutter as claimed in Claim 13, wherein the rotary cutter means includes a longitudinally moveable cutter arranged radially to engage a clamped pipe to be cut, in use, movement of the cutter towards or away from the pipe being effected by rotation of an operating member of the rotary cutter means relative to said cutter. 15. A pipe cutter as claimed in Claim 14, wherein angular movement of the rotary cutter means, in use, is effected by angular movement of the assembly of said operating member together with said cutter. 16. A pipe cutter as claimed in any one of the preceding claims, which is free-standing by means of a stand carrying said clamp means, said stand being intended to engage the ground or equivalent surface. 17. A pipe cutter as claimed in Claim 16, wherein the stand is in the form of a tripod with two legs thereof connected together by a brace intended for use as a horizontal foot rest when the pipe cutter is in use. 18. A pipe cutter as claimed in Claim 17, wherein said two legs and the other leg respectively are connected to identical members secured to the clamp means, so that the legs can be arranged to provide a right or left handed pipe cutter as required. 19. A kit of parts for assembling a pipe cutter as claimed in any one of the preceding claims.

Inventors: GREENSALL KENNETH ARTHUR, POTTER LAURENCE JOHN, GREENSALL, KENNETH, ARTHUR, POTTER, LAURENCE, JOHN
Applicants: GREENSALL KENNETH ARTHUR, POTTER LAURENCE JOHN, GREENSALL, KENNETH, ARTHUR, POTTER, LAURENCE, JOHN
Application year: 1992
Main classification: B23D21
IPC codes: B23D21