The present invention regards a pipe cutter, for cutting pipe with a clean cut, while at the same time having a detachable, mobile apparatus.

There exist several models and types of pipe cutters, some of which are described in for instance US 4,845,849, which described a pipe cutter with a guided cutter blade. This pipe cutter is manually operated by a main handle, connected to a screw arranged in a frame structure, wherein in a cutting blade is mounted, being moved by turning the screw. The frame structure has a hinged lower part which opens. This solution is a manually operated system, and the power in the cutting action is limited. The frame structure is not adaptable to different pipe sizes. This pipe cutter does not provide a proper fixation for the pipe to be cut. The alignment is inaccurate and there is no protection against deformation of the pipe during cutting.

Another kind of pipe cutter may be found in US 5,012,579, which described a cutting machine with a machine body with a groove for holding the pipe and a plate like cutter blade. The cutting blade is manually operated by handle with a gear wheel in one end in engagement with a pitch rack arranged to the cutting blade. The cutting blade is formed with an apex in the cutting edge, which gives a cleaner cut, than a straight cutting edge. This cutting machine is for one pipediameter only, and the protection against deformation during cutting is not satisfactory.

A main aim of the present invention is to provide a pipe cutter, which is reliable, easy to move and use and is versatile.

Another aim is to provide a pipe cutter which can be used with different kind of driving tools, easily fitted to different kinds of pipes and which may be used on already laid pipes for instance in trenches.

It is a further aim to provide a cutter which cuts the pipes without deforming them or producing shavings during the cut.

These aims are achieved with a pipe cutter according to the following claims.

According to the invention it comprises the device for cutting tubular elements as pipes made for instance of plastic, a detachable frame structure and a cutting blade. The cutting blade has favourable a cutting edge with an apex, which is the first point of the cutting blade to contact the pipe to be cut during the cutting action. The cutting blade performs a guillotine cutting action in one plane mainly parallel to a main plane of the frame structure. The frame structure has at least two mainly parallel leg elements and a joining element securely connected to one end of each leg element, forming a U-shaped part of the frame structure. The joining element may also of course be connected to the leg elements midway at the leg elements. Along at least one leg element on each side of the cutting blade there is arranged a drive device, which at least two drive devices are synchronised with regards to both power and movement of at least one holding element for the cutting blade. At least one of the driving devices comprises means for engagement with a driving tool and or for activation of the drive device.

The detachable frame further comprises at least one detachable plate element, connected to the leg elements at a part of these away from the joining element, and with the cutting blade between the joining element and the plate element. This means that the legs may be positioned on each side of the pipe to be cut. Thereafter attaching the plate elements closing in the pipe between the plate elements and the cutting blade. According to the invention comprises the plate element in one edge facing the cutting blade comprises a recess complementary to the form of the pipe which should be cut. The plate element(s) forms two supporting areas for the pipe to be cut on opposite sides of the plane for the movement of the cutting blade. This may be achieved by having at least two plate elements one on each side. of the leg elements in abutment against the leg elements, which is a favourable solution according to the invention. Another possibility is to have a plate element with a larger thickness, with a recess running mainly from one leg element to the other leg elements, thereby forming a recess wherein the cutting blade may be moved, and the material of the plate elements left on each sides of the recess forms the two supporting areas.

According to a favourable embodiment of the invention for cutting pipe elements with a diameter up to around 350 mm, the drive devices are at least two screws mounted in bearings, preferably at the ends of the screws. A chain wheel is arranged at each screw and a chain element is arranged running around the chain wheels, synchronising the movements of the screws and thereby the speed of movements and power on the cutting blade. At least a nut is arranged running along each screw which is in connection with at least one holding element for the cutting blade and at least one of the screws comprises means for engagement with a driving tool.

In another embodiment for use of the device for cutting pipes with a diameter larger than approximately 350 mm, the drive devices are fluid operated piston cylinders. The fluid may be hydraulic or pneumatic. The drive devices may be synchronised in several ways, by having a common pump, regulating valves for connection to an external fluid source, one pump to each drive device which are regulated, or other way.

There are several ways of connecting the plate elements to the leg elements, preferably is it an easy and simple way which makes the changing of the plates quick and without the use of specific tools. According to the invention is one favourable solution to have the plate element(s) connected to each leg, by means of a hook like tap insertable in a groove or hole in the plate element, and locked to the leg elements by means of at least one locking pin insertable in a locking recess in one side edge of the plate element(s). The locking pin is favourable connected to the leg element by an elastic element, for thereby always be connected to the frame and not lost. Another more important benefit is that the elastic element keeps the locking pin safely within the locking recess, which has an inner point of the recess closest to the connection point of the elastic element to the leg element. The groove or hole in the plate element for insertion of the hook like tap also has a form which positions the plate element in relation to the leg elements. This is important to get the centre line of the recess in the plate element facing the cutting blade aligned with the movement line of the apex of the cutting blade. In the embodiment with two plate elements the locking pin is locking two plate elements in relation to each other and in abutment against the leg elements.

The two plate elements positioned on each sides of the leg elements are favourably positioned with a relationship of the distance between the centre points in the plate elements to the diameter of the pipe to be cut, of between 1 :6 and 1 :9, preferably 1 :7 and 1 :8.

The recess in the plate element(s) for the pipe to be cut has a first section away from the edge of the plate elements, mainly equivalent to the outer form of a half cross section of the pipe to be cut. Preferably the second section of the recess is elongated beyond the half cross section in order to leave stabilizing shoulders for support of the object to be cut.

In one embodiment of the invention comprises the frame structure comprises at least one additional detachable second plate element, arranged at least partly between the first plate element and the cutting blade in a retracted position of the cutting blade, the function of which is to enable extra support of the object to be cut.

In order to reduce weight of the cutting device the plate element(s) are formed with a pattern of through going holes or grooves. These holes or grooves are specifically positioned in areas of low stress in the material of the plate elements during use.

In the preferred embodiment the leg. elements are substantially hollow profiles and the drive devices are arranged mainly within the hollow profile. And in the embodiment with screws as the drive device, the nut and or a bushing attached to the nut has an outer form corresponding to the internal form of the hollow leg elements. And the leg elements are formed with a slit for guiding of the holding element and or a connecting piece attached to the holding element for the cutting blade.

The invention shall now be explained in more detail with an embodiment with reference to the drawings where: Fig. 1 is a perspective view of a pipe cutter according to the invention,

Fig. 2 shows one part of the frame structure in a cutter according to fig. 1 , showing the drive mechanism,

Fig. 3 is a perspective view of a leg of the cutter in fig. 1,

Fig. 4 is a cress section of a screw of the cutter in fig. 1,

Fig. 4b is a more detailed sketch of a part of fig. 4,

Fig. 5, is a perspective sketch of a nut and a holding element for the blade of the cutter in fig. 1 , and

Fig. 6 is a perspective view of a plate element of the cutter in fig. 1.

A pipe cutter according to the invention, as shown in fig. 1 comprise a frame structure 1 and a cutting blade 2 guided in the frame structure 1. The frame structure 1 comprises two leg elements 3 and a joining element 4, joining the leg elements 3 at one end of these. At the other ends of the leg elements 3 there are arranged two plate elements 12. Each plate element is connected to both legs 3, and the two plates 12 are arranged on opposite sides of the leg elements 3. The plate elements are arranged connected to the leg elements 3, by means of a hook like tap 14, connected to the leg elements 3 and inserted in a groove 15 in the plate element 12, and a locking pin 16 inserted in lock recesses 17 in the plate elements, locking the two plate elements 12 to each other in tight abutment to opposite sides of the leg elements 3.

The cutting blade 2 is of a kind with an apex in the cutting edge. The blade 2 is guided and held in the frame structure 1 with a holding element 10, one of each side of the cutting blade. The plate elements 1 have a recess 13 in the edge facing the cutting blade 2, for aligning and supporting the pipe which should be cut. A centre line of the recess 13 is aligned with the moving line of the apex of the cutting blade during the cutting motion. This is to make sure a symmetrical, plane and clean and balanced cut.

The drive mechanism for moving the cutting blade comprises of several elements. As shown in fig. 2 are the holding elements 10 holding the cutting blade 2, guided in a slit 22 in the leg elements- 3. The leg elements 3 are hollow square section elements, wherein there is arranged a screw 5, as shown in fig. 4 in each of them. The screw is arranged in bearings 6 at both of its ends. One end also has an extension, protruding outwards from the frame structure, as an engagements means 11, for engagement with a driving tool. At a first end of each of the screws 5 there is arranged a chain wheel 7. As seen from fig. 2 there is around these two chain wheels 7 arranged a chain element 8, keeping the movement of both screws coordinated. The chain element 8 is kept in tight engagement with the chain wheels 7 by a tension element 23 arranged at the joining element 4. The drive mechanism is arranged as a part of the joining elements 4 and covered by an outer cover, for safety reasons and preventing the drive mechanism to get tangled in foreign objects.

The holding element 10 for the cutting blade 2 is arranged in connection with a nut 9 arranged on each of the screws 5. When a driving elements is in engagements with the engagement means 11 of one of the screws 5 and start turning the screw 5, the other screw 5 will due to the connection via the chain wheels and chain element move simultaneously and coordinated, (and move the nuts on (both) screw and) thereby securing a precise movement of the cutting blade both in the cutting plane and transverse to the plane.

The nut 9 arranged on the screw is an. elongated nut with an outer square form, corresponding mainly to the internal form of the leg elements 3. There is of course the possibility of having a more common nut connected to a bushing with an outer form mainly corresponding to the internal form of the leg elements. The nut 9 is as shown in fig, 5 attached to a connecting piece 27 connected to the holding element 10. The connecting piece is guided in a slit 22 in one side of the leg element 3, facing the blade element 2. The elongated nut 9 with internal threads 28 also comprises several bushing holes 29, for fastening bushing elements 20, as best shown in fig. 4B. The tight fit of the nut 9 and or bushings 20 within the leg element 3 and a tight fit of the connecting piece 27 in the slit 22 give a firm guiding of the cutting blade along the frame structure.

The leg elements 3 have in their opposite end of the joining elements 4 two plate elements 12, one arranged on opposite sides of the leg elements 3. A plate element 12 is shown in fig. 6. A plate element 12 has in one edge a recess 13, specifically designed for one outer cross section profile of a pipe to be cut. The recess 13 has a first inner section mainly equal to the outer form of a half cross section of the pipe to be cut. The second section of the recess 13, facing the edge is an elongation in . straight line of the first section in a direction towards the cutting blade, so for a circular pipe would the recess compromise a half circle in the end and the ends of the circle extended in the direction of the cutting blade so that the pipe easily may be introduces in the recess but that the recess at the same time supports the pipe for an area a bit more than the half circle. The extension towards the cutting blade is for smaller pipes up to around 315 mm in diameter approximately 10 mm and may be larger for larger pipes. The plate element 12 further has grooves 15 for interaction with the hook like taps 14 connected to the leg elements 3, and locking recesses 17 in the side edges for interaction with a locking pin 16, which lock the two plate elements 12 to each other in tight abutment against the leg elements 3 in between the plate elements 12. By having this easy mounting and dismounting of the plate elements 12 to the leg elements 3, it is easy to adapt the cutting device to the size of the pipe to be cut, by changing the plate elements. The cutting devise can also easily be mounted around an already laid pipe, for instance in a trench or pipe channel. The plate elements 3 favourably also have holes 24, to both make the handling of the plate elements 3 easier, and also reduce the weight of the plate elements and the cutting device. These holes can be of any shape or not be present at all.

This gives an cutting devise which do not deform the pipe when cutting it, is easy to use also for already laid pipes, which is easily adaptable to different pipe sizes and shapes etc

The invention has now been explained with an embodiment, it is possible for a skilled person to make alterations and modification to the described embodiments which is covered by the invention as defined in the following claims. These alterations may for instance be to form the recess for a pipe with a square cross section, to have four separate leg elements with a piston cylinder arranged between pairs of legs, the plate elements may be square and have different diameter recess for pipes on different edges with attaching system adapted to turn the plate elements, there may be two chain elements running on two chain wheel attached to the screws, etc.