The present invention relates to a pipe cutting apparatus and, more specifically, to an apparatus for cutting for example a water or sewer pipe and bevelling the ends thereof.

BACKGROUND OF THE INVENTION

Typically water or sewer pipes are manufactured of a polymeric material, e.g., polyvinyl chloride (PVC), wherein one end of the pipe is a female end defining a socket and the other end of the pipe is a male end having a bevelled or chamfered outer circumference. The pipes are typically manufactured in standard diameters and lengths and several of the pipes may require cutting in the field to provide pipes having the necessary length.

Commonly a rubber gasket is used to seal the joint where two pipes are connected. The gasket is captured within an annular pocket formed on the female end of one of the pipes. The male end of the other pipe engages the radially inner surface of the gasket to form the seal. The male end of a standard length pipe will typically include a taper or bevel so that the gasket is not rolled out of the pocket or damaged when the male end is inserted during the installation process. When a pipe must be cut to a custom length in the field, the original chamfered or bevelled male end is typically cut off and a new male end is formed. Workers will often try to bevel the edge of the male end of such custom length pipes in the field to avoid damage to the gasket. The use of hand held cutting or grinding tools, however, will often result in an irregular beveled edge. After the pipe system has been installed, governmental requirements often require that the system be pressurized and satisfy specific pressure decay parameters. If the system does not pass the pressurization test, the leaks causing such failure must be found and corrected. Oftentimes, the source of such leaks is a damaged or displaced gasket at the junction of two pipes. The cost of finding and repairing such leaks can be very significant. Accordingly, a reduction of the frequency of such leaks is highly desirable. Prior art cutting devices are described in US patent nos 5,027,681 ; 6,938,313; and 4,412,401. Meanwhile, these devices are not suited for accurately cutting and bevelling plastic pipes. The object of the present invention is to provide a new portable apparatus especially intended for cutting and bevelling tube or pipes, in particular plastic tubes/pipes, by means of which apparatus the problems described above are avoided and which apparatus is easy to use, while the cutting or bevelling takes place quickly and accurately. This object is achieved by means of the apparatus of the present invention, mainly characterized in that the elements to rotate and support the tube/pipe are formed of the upper supporting rollers along with pivotable and supporting guiding wheels, in combination with a displaceable cutting tool that both cuts and bevels the tube/pipe. In this way, a reliable and cheap manually operated apparatus is provided for cutting and bevelling a tube/pipe, in particular a plastic tube/pipe.

SUMMARY OF THE INVENTION

The present invention provides a pipe cutting apparatus that securely holds a pipe for working the pipe in a safe and controlled manner and which can be used to cleanly and precisely cut and bevel pipes, in particular PVC pipes. However, the apparatus can also be used for cutting and bevelling of copper, steel or stainless steel pipes as well as other plastic pipes.

The invention comprises, in one form thereof, an apparatus for cutting and bevelling a pipe, such as a plastic pipe. The apparatus includes a lower frame having two lower supporting rollers for rotatably supporting the pipe when placed thereon. Also provided is an upper frame having two upper supporting rollers for further rotatably supporting the pipe when placed on the lower supporting rollers and the upper supporting rollers are lowered to the pipe. The upper frame is part of a clamping assembly for clamping the pipe in a secured position between the supporting lower and upper rollers. In order to rotate the pipe means for rotating one or more of the upper or lower rollers are provided.

Important for the apparatus of the present invention is at least one guide wheel, arranged for example between either the two upper rollers or lower rollers; preferably between the two lower rollers. The guide wheel is resiliently and rotatably forced/urged towards the surface of the pipe when the pipe is placed between the upper and lower supporting rollers. The wheel is pivotable in order to longitudinally guide the pipe forth and back between the lower and upper supporting rollers. The present inventor has surprisingly found that such a guide wheel is required, not only for guiding the pipe between the upper and lower rollers in its longitudinal direction, but also for rotating the pipe in a fixed position relative to the cutting tool used according to the present invention.

In contrast to prior art devices the apparatus according to the present invention uses a cutting tool having a cutting edge and a separate bevel-cutting edge. When the cutting tool, and especially its bevel-cutting edge, is pressed against the surface of the pipe it exerts a force on the pipe that would move it backwards, unless the above mentioned guide wheel is resiliently and rotatably forced/urged towards the surface of the pipe. Hence, the present invention makes use of the combined action of the forces emanating from the lower and upper rollers in conjunction with the guide wheel to counteract the forces exerted by the cutting tool. In order to perfectly control these forces the drive wheel may be pivoted (twisted) relative to the surface of the pipe in order to compensate for the varying force exerted by the cutting tool as it is pressed against the surface of the pipe during the cutting and bevelling procedure.

With other words the guiding wheel can be pivoted, so that the axis of rotation of the guiding wheel will be not parallel (inclined) in respect to the axes of rotation of the supporting rollers or the pipe. Therefore the guiding wheel can be moved between a first position, in which the axis of rotation of the guiding wheel is parallel to the axes of rotation of the supporting rollers, and a second position, in which the axis of rotation of the guiding wheel is not parallel to the axes of rotation of the supporting rollers.

In particularly, when plastic pipes are cutted and bevelled the force applied to the upper support roller will cause a certain ovality of the pipe, so that without the use of the guiding wheel, the pipe will move in its longitudinal direction. In order to control said movement and to stop said movement in the correct position, the guiding wheel is used, since an inclination of the axis of rotation of the guiding wheel being in contact with the pipe will assert an additional force to the pipe in the longitudinal direction. Therefore, any longitudinal movement of the pipe can be accelerated, decelerated or even stopped by means of an appropriate pivoting of the guide wheel. In a preferred embodiment the apparatus comprises two guide wheels which are resiliently and rotatably forced/urged towards the surface of the pipe. It can be an advantage, when both guide wheels have identical axes of rotation. In one embodiment of the present invention the apparatus includes a clamping assembly for clamping the pipe in a secured position between the lower and upper supporting rollers. The clamping assembly includes a lever arm pivotally mounted to a frame. A clamping member is disposed on the lever arm and pivoting motion of the lever arm moves the clamping member between a clamping position in which the clamping member engageably secures the pipe between the lower and upper rollers and a disengaged position in which the clamping member is spaced apart from the pipe on the frame allowing the pipe to be inserted and removed. A biasing member having a first end secured relative to the frame and a second end operably coupled to the lever arm biases the clamping member toward the pipe when the clamping member is positioned proximate the clamping position and biases the clamping member away from the pipe when the clamping member is positioned proximate the disengaged position.

An advantage of the present invention is that by securely clamping the pipe it can reduce imprecision in the cutting and bevelling of the pipe caused by warping in the pipe or slippage of a wet pipe. Features of the present invention that facilitate the secure clamping of the pipe, individually and in combination, include the use of the lower frame having two lower supporting rollers for rotatably supporting the plastic pipe when placed thereon; the upper frame having two upper supporting rollers for further rotatably supporting the plastic pipe when placed on the lower supporting rollers and the upper supporting rollers are lowered thereto; and two guide wheels, arranged between the two lower rollers, being resiliently and rotatably urged towards the surface of the plastic pipe when said pipe is placed between the upper and lower supporting rollers, said wheels being turnable in order to longitudinally guide the pipe forth and back between the lower and upper supporting rollers. In another aspect of the present invention there is provided a method for cutting and bevelling a plastic pipe, said method comprising the steps:

• providing a lower frame having two lower supporting rollers for rotatably supporting the plastic pipe when placed thereon;

providing an upper frame having at least one upper supporting roller for further rotatably supporting the plastic pipe when placed on the lower supporting rollers and the upper supporting roller is lowered to the pipe; providing means for rotating one or more of the upper or lower rollers so as to rotate the plastic pipe;

providing at least one guide wheel, being rotatably urged towards the surface of the plastic pipe when said pipe is placed between the upper and lower supporting rollers, said wheel being pivotable in order to longitudinally guide the pipe forth and back between the lower and upper supporting rollers; and

providing a displaceable cutting tool having a cutting edge and a separate bevel- cutting edge;

wherein

the pipe is clamped between the upper and lower rollers so as to obtain an ellipsoidal cross section;

the cutting tool is pressed against the surface of the rotating pipe while the guide wheels are pivoted so as to compensate for the force exerted by the cutting tool, whereby the pipe is held in the same position during cutting and bevelling.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an overall view of the apparatus for cutting and bevelling a plastic pipe of the present invention.

Figure 2 is a side view of the apparatus.

Figure 3 is an overall view of the apparatus, where the pipe to be cut and bevelled is in place.

DETAILED DESCRIPTION OF THE INVENTION Overall views of a pipe cutting apparatus (1) in accordance with the present invention are shown in FIGS. 1 and 3, whereas Figure 2 is a side view of the apparatus.

In a preferred embodiment shown in Figures 1-3 the apparatus (1) includes a lower frame (10) having two lower supporting rollers (2) for rotatably supporting the pipe (6) when placed thereon along with an upper frame (9) having upper supporting rollers (3) for further rotatably supporting the pipe (6) when in place (see Figure 3). The upper frame (9) is part of a clamping assembly (10) for clamping the pipe (6) in a secured position between the supporting lower (2) and upper (3) rollers. In order to rotate the pipe (6) means for rotating one or more of the upper or lower rollers are provided (not shown).

Two guide wheels (4) are arranged between the two lower rollers (2). The guide wheels (4) are resiliently and rotatably forced/urged towards the surface of the pipe (6) when the pipe (6) is placed between the upper (3) and lower (2) supporting rollers. The wheels (4) are pivotable in order to longitudinally guide the pipe (6) forth and back between the lower (2) and upper (3) supporting rollers. In Figures 1 and 3 two upper rollers (3) are provided for directly supporting the pipe (6) and are mounted in a frame (9) that can be lifted or lowered via a lever arm (10). Two lower rollers (2) are also provided to ensure a lower support of the pipe (6). The apparatus (1) include at least one driven roller, while the other are non-driven rollers or followers. Guide wheels (4) are also provided to ensure that the pipe (6) is held in the same position during the cutting and bevelling procedure. The guide wheels (4) as well as the upper (3) and lower

(2) rollers directly engage and support the pipe (6). The upper rollers (3) that are mounted via a frame (9) on a lever arm (10) where, together with lever arm, they form a pipe clamping member. The lever arm (10) is pivotally mounted to the frame (9) and move the upper rollers

(3) into and out of engagement with a pipe (6). Figure 3 shows the upper rollers (3) in a clamping position with the rollers engaged with the pipe (6) that rests on the lower rollers (2).

The apparatus has a cutting tool (5) which is displaceable and has a cutting edge and a separate bevel-cutting edge. In a preferred embodiment the apparatus has at least two cutting edges which can be used selectively dependent on the material of the pipe. For example, the apparatus can comprise a capstan turntable with at least two positions allowing the use of the different cutting edges. The cutting tool can be located between the two upper supporting rollers.