It is an object of the present invention to provide a cutting tool which permits the cutting operation to be performed at a distance from where the user of the cutting tool is situated. Such a tool is particularly suitable where the body that has to be cut is in a location which is difficult to reach, or where for reasons of safety it is undesirable for the user to be located in the proximity of where the cutting operation is performed.

The cutting tool is particularly suitable for cutting electric cables or wires which are suspended between pylons, such as high-tension wires, but also other types of elongated bodies such as wires or lines may be suitable objects to be cut. Even though the tool is particularly suitable for enabling the user to perform the actual cutting operation when he is located at a distance from the object to be cut, the tool can also be used to perform more ordinary cutting operations where the user is near the object to be cut.

With regard to cutting down wires or cables suspended between pylons, it has been shown that personnel performing the cutting down operation are particularly prone to accidents. The operator normally climbs up the pylon and carries out the cutting operation from there. The stability of the pylons is to some extent dependent on the span between the pylons, and when the wires between the pylons are cut, this results in an increased risk of instability in the pylon in which the operator is located. This applies particularly when the operator has cut the last wire and the pylon is no longer supported by the span in the wires.

The invention according to the independent patent claim indicates a tool which makes it unnecessary for the operator to be located up in the pylon during the actual cutting operation and accidents can thereby be prevented. The tool is characterised by the features defined in the characteristic of the independent patent claim.

From US 4283851 a tool is known that can be used for cutting wires and electric cables. The tool consists of a scissors device and a hydraulic or pneumatic piston which guides the tool's cutting movement. The tool's cutting movements according to the invention are generated as a result of an actuator which is initiated by detonation of an explosive charge. Compared to the tool in US 4283851 the invention appears to be easier to carry, the tool has fewer parts and is more compact. The hydraulic or pneumatic cylinder employed in the tool in US 4283851 requires a hydraulic or pneumatic power source.

If cables have to be cut, for example, in inaccessible terrain, it is desirable to employ a tool which is easy and light to carry. When using the tool according to US 4283851 it is also necessary to bring along a power source in addition to wires and equipment for transferring the hydraulic medium or the air to the cylinder. The equipment described in US 4283851 is therefore not particularly mobile and will be felt to be both heavy and difficult to handle. In contrast to the equipment in US 4283851, the tool is constructed in such a manner that an. external power source and the associated equipment become superfluous. The invention has a compactness and weight that make it very well suited for carrying, and it will therefore-be well suited for use in terrain which it is difficult to reach and where the operator himself has to carry the tool that is to be used.

Yet another cutting device is known from US 2716813, wherein an explosive charge is employed to trigger a cutting movement. The actual cutting tool according to the invention, however, is of a somewhat different design to the cutting tool disclosed in US 2716813.

The tool according to the invention comprises a scissors device and an actuator, which is connected to the scissors device and which is activated by detonation of an explosive charge. Thus there is no need for an external power source in the invention, and all that has to be carried are extra explosive charge casings which do not add significantly to the total weight the operator has to carry. The tool may preferably be made of a low-weight material such as aluminium or titanium.

The tool's scissors device comprises two scissors halves which are hinged together in such a manner that each scissors half has two free ends. The first end is equipped with cutting surfaces. The two scissors halves are hinged together and can be rotated about the hinge point and moved between an open position where the scissors halves'cutting surfaces are moved away from each other and a closed cutting position where the scissors halves'cutting surfaces are moved towards each other. The cutting surfaces may be composed of hard metal insets which are affixed to the scissors device, where the insets may, for example, be replaceable.

The tool according to the invention is further equipped with an actuator which is connected to the scissors device. The actuator is activated by detonation of an explosive charge, where the explosion is initiated by remote control. The detonation of the explosive charge causes the scissors halves'cutting surfaces to be moved towards each other and the cutting operation is carried out.

The actuator is secured relative to one of the scissors halves'second ends (the ends of the scissors device corresponding to"the handle ends"). In a preferred embodiment of the invention the actuator comprises a cylinder with a cylinder cavity where a piston with piston rod is mounted. The end of the piston rod protrudes through an opening in the cylinder and is connected to the second of the

scissors halves'second ends ("the handle ends"). Movement of the piston in the piston cavity results from the detonation of the explosive charge. The piston stroke causes the second ends of the scissors halves to be moved away from each other and the scissors halves'cutting surfaces moved towards each other.

In yet another embodiment the actuator comprises a firing pin which is preferably spring tensioned and mounted in a bore in a holding piece. The firing pin is held in position by a split-pin which is mounted in a split-pin opening in the holding piece.

The bore of the holding piece leads into a receiving opening where the cylinder is releasably attached. Furthermore, an explosive charge casing with an explosive charge is held in position in the cylinder cavity in the path the firing pin will follow when the split-pin is released. The explosive charge is therefore located between the piston and the firing pin immediately in front of the firing pin, but preferably slightly offset in the radial direction viewed in the firing pin's path direction. The firing pin strikes the explosive charge with a force that is sufficient to cause an explosion, with a resulting pressure increase that moves the piston and thereby also the piston rod further out through the opening in the cylinder.

A person skilled in the art will realise that the detonation of the explosive charge will be able to be implemented in. various ways as the design and arrangement of the tool's individual parts such as the scissors device and the actuator may be varied within the scope of the attached patent claims.

In an embodiment of the invention the tool may be equipped with a rigid body, for example in the form of a telescopable rod attached to the scissors device. By means of the rod the operator will lift the tool up to the object to be cut and place it in the correct position, for example at the correct height, if it is a high-tension cable that has to be cut. The tool will preferably be arranged in such a manner that the scissors device is returned to an open position after cutting is completed, with the result that the tool has a starting position where it is ready for use. This return motion of the cutting surfaces can be achieved by the tool being equipped with a resetting body in the form of a spring which is attached to each of the scissors halves'second ends.

In addition the tool may be provided with guide devices which the operator uses to direct the object to be cut in towards the scissors device's cutting surfaces. The guide devices are preferably composed of guide cords attached to the scissors halves'first free ends.

In order to perform the actual cutting operation, it is necessary to equip the tool with means to enable the explosion to be initiated. In a preferred embodiment of the invention the explosion is initiated by the split-pin being removed from the split-pin opening in the holding piece. In yet another preferred embodiment a release cord is attached to the split-pin. The user can easily initiate detonation of the charge by pulling the release cord, thereby removing the split-pin. A person skilled in the art

will appreciate that other devices and remote control principles than split-pin and release cord may be employed in order to initiate detonation of the explosive charge. One example that may be envisaged is where a signal that is transmitted to a receiver in the tool can be employed to control the detonation of the explosive charge.

Furthermore, at least one of the scissors halves'second ends ("the handle ends") may be provided with a holder for the actuator, and where the resetting body is a spring, it may be attached at its ends to the holder.

It should also be mentioned that the cylinder is designed with a vent for exhaust and the piston rod is provided with a damping body preferably in the form of an O-ring in order to cushion the impact between the cylinder and the piston when the piston rod is moved all the way out through the opening in the cylinder.

The invention will now be described in connection with a preferred embodiment of the invention as illustrated in the attached figures, in which: Fig. 1 is a principle drawing of the tool in an open position.

Fig. 2 is a principle drawing of the actuator in axial section.

Fig. 3 is a principle drawing of the tool in cutting position.

Fig. 4 illustrates the tool in operation.

Figure 1 illustrates the tool comprising a scissors device 1 and an actuator 2. The scissors device 1 is composed of two scissors halves 3,4 which are hinged together at a hinge point 5. By rotating the two scissors halves in a scissors movement, the two scissors halves are moved in parallel planes. Each of the scissors halves has a first end 3 a, 4a with cutting surfaces and a second end ("handle end") 3b, 4b where the actuator 2 is attached. In figure 1 the tool is shown in its open position where the scissors device's cutting surfaces are moved away from each other and positioned around an electric cable 5 which is the object to be cut in this illustrated example. The actuator 2 is illustrated attached to one of the scissors halves'second ends 4b by means of a holder 6. The actuator has a cylinder 10 with a piston rod 7 and a holding piece 11. The piston rod 7 is attached to the second of the scissors halves'second ends 3a. There is also illustrated a spring 8 which is attached at its. ends to the holder 6 and the scissors halves'end 3a respectively. The spring arranges for the scissors device 1 to be returned to its open position after the cutting is completed. To the scissors halves'ends 3a and 4a there are attached guide cords 9 which are employed for positioning the tool around the cable 5a.

In figure 2 the actuator 2 is illustrated in axial section in the same position as in figure 1. In the holding piece's 11 bore 11'there is mounted a firing pin 12 which is stretched by a spring 13. The firing pin 12 is kept in the stretched position by a

split-pin. 14 mounted in a split-pin opening 15 and passed through an opening in the firing pin 12. A release cord 16 is attached to the split-pin 14.

When the user pulls the release cord 16, the split-pin is removed from the split-pin opening 15 and the firing pin 12 is inserted in the bore 11'by means of the force from the spring 13. The firing pin 12 strikes an explosive charge 17 which is secured in an explosive charge casing 18 in the cylinder's 10 cavity. It can be seen in figure 2 that the cylinder 10 is attached in a receiving opening which is an extension of the bore 11'. The explosive charge is positioned slightly offset in the radial direction relative to the firing pin 12. The impact between the firing pin 12 and the explosive charge 17 results in an explosion and a subsequent pressure increase behind the piston 7'. The piston rod 7 is thereby moved further out through an opening 22 in the cylinder 10 (this is illustrated by dotted lines in figure 2). The piston rod 7 is equipped with damping means in the form of an O-ring 19 which will have a cushioning effect when the piston 7'strikes the cylinder's internal wall when the piston is fully displaced. The cylinder is also provided with a vent 20.

Furthermore, the cylinder 10 may be released from the receiving piece 11 for refilling explosive charge.

When the actuator's piston rod 7 has obtained substantially full stroke, the scissors device is moved to the position illustrated in figure 3. As a result of the piston stroke the second ends 3b, 4b are moved away from each other and the first ends 3a, 4a are moved towards each other in cutting position. The cable 5 illustrated in figure 1 is thereby severed. It can be seen in figure 3 that the spring 8 has been extended and is therefore ready to pull the scissors device back to its starting position as soon as the force on the piston rod decreases.

Figure 4 illustrates a user or operator in the process of cutting a high-tension cable.

The tool 1, 2 is attached to the end of a telescopic rod 20, which can be adjusted in its axial direction-and which can thereby be adapted to the height of the high- tension cable above the ground. The release cord 16 is also illustrated in figure 4.