In several cases it is difficult to provide suitable devices for protection of the operator of especially machines having working tools cutting chips as it is important to protect the operator not only from unintentional touching of the tool but also from being hit by chips during the cutting operation. A safety device is neither to be of such a type that the work of the operator being more difficult as in such a case there is a vast rise for that the operator is trying to eliminate the _f protective measures by disabling the safety device by removing the same or any other measure taken by the operator.

The task forming the basis of the present invention is to provide an improved device giving a higher grade of protection than previously known devices.

This task is achieved according to the present invention in that the device disclosed by way of introduction is characterised in that a cover being switchable between a protective position, in which the cover provides a shield between the tool and the material in the vicinity of the same and the surrounding at least in the direction of the operator, and a rest position, in which the cover allow the operator availability to the place of machining. The cover having open sides to allow long matrial pieces to extend past the same to the place of machining and also eventually from the same. The cover is curved around an axis extending substantially parallel to the material piece, and in it ^' s working position provides an extention of a fixed rear cover. The fixed rear cover is curved on substantially the same way as the switchable cover, which in it ^' s rest position is placed above the fixed rear cover. The switchable cover is connected to a mechanism for switching of the same between the working position and the rest position.

The mechanism comprises a piston and cylinder means, of which the cylinder being mounted on a fixed stand, and of which the piston is connected with a carriage for movement on a guide bar mounted on the stand, which carriage is provided with two cable wheels on the same shaft, wherein a cable fixed on the stand extends over one of the wheels to a cable wheel mounted on the stand below the carriage and from this to a substantially horisontally on a part of the stand above the front edge of the rear cover mounted cable wheel and to a first cable mount at the rear edge on the switchable cover and wherein a second cable fixed on the stand extend to the other wheel on the carriage and from this to a cable wheel at the upper end of the stand and to a cable wheel on the stand in level with the upper side of the covers to another cable mount closer to the front edge of the switchable cover than the first cable mount. The piston and cylinder means is interconnected in a safety arrangement allowing running of the tool only when the switchable cover is in the working position.

The device realised by the present invention does not in any way delay the work of the operator or neccessary measures at the machine but yet give a full protection between the operator and the cutting tool. The work table and the tool are available by a long wood piece in a machine in accordance with the present invention without any any advertent influence on the desired protection. When the device according to the present invention is in a rest position the work table is as available as if the machine did not have the device according to the present invention, whereby the rise for that the operator should try to eleminate the device has been minimised in most possible extention. A device in accordance with the present invention does not in any way influence the working capacity of the machine.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings. Fig 1 is a side view of an embodiment of a device in accordance with the

present invention. Fig 2 is a view in the direction of the arrows A-A in fig 1.

Refering to the drawings, the embodiment of the present invention shown therein is mounted on a crosscut saw, of which only the saw table 1 and the cutblade 2 are shown schematically. Preferably the crosscut saw is of the type having high capacity and is controlled numerically or by a computer. The cutblade 2 is liftable and lowerable through a slot in the saw table 1 and also the cutblade 2 may be rotable universally for cutting in different angles.

A stand 3 is mounted on an exhaustion cover 4 with hose connectors 5 and 6. The stand 3 is in the form of a column inclined a few degrees in over the work table 1 and carrying a horisontal part 7 via a strut 8. The free end of the horisontal part 7 of the stand 3 is carrying a substantially horisontal cable wheel 9. A cable wheel 10 is mounted on the stand 3 in level with the horisontal part 7. A piston and cylinder assembly 11 is mounted on the column of the stand 3. The end of the cylinder of the assembly is fixed on the column of the stand 3 and the piston end is provided with a carriage 12 moveable along a guide bar 13 mounted on the column of the stand 3 between an upper mount 14 and a lower mount 15. At the upper end of the column of the stand 3 a cable wheel 15 is mounted in alignment with the cable wheel 10 and an outer cable wheel 16 on the carriage 12. The cable wheel 16 is mounted on the same shaft as an inner cable wheel 17 in alignment with a further cable wheel 18 mounted on the column of the stand 3 below the cable wheel 10.

An adjusting screw 20 has an upper mount 19 on the upper end af the column of the stand 3 and a lower mount 21 for an adjusting screw 22. A first cable 23 in the form of av steel wire covered with plastic extends from the adjusting screw 22 for stretching of the cable 23, via the cable wheel 17 to the cable wheel 18 and therefrom to the cable wheel 9 and therefrom to a cable mount 24 at the rear edge of an switchable cover 25. A further

cable 26 in the form of a steel wire covered with plastic extends from the adjusting srew 20 for stretching of the cable

26 over the cable wheel 16 to and over the cable wheel 15 and therefrom to the cable wheel 10 and is fixed in a cable mount

27 closer to the front edge of the cover 25 than the cable mount 24.

Fig 1 shows clarily that the switchable cover 25 is curved around the blade 2 and extends above a rear fixed cover 28 having a curved part and a straight part, said straight part extends down to the exhaustion cover 4 and is supported by a plate 29. The cover 25 is switchable between the position shown with solide lines in fig 1 and the position shown with broken lines in fig 1. Suitably the cover 25 is made of plexiglass or the like and a clamp strip 30 is provided on the front edge of the cover 24 and en strip 31 of cellular rubber is provided on said edge as support against the work table 1 in the work position.

The curved part of the fixed rear cover 28 is provided with a guide 32 on each side for guiding the cover 25. The guides 32 are carrying bearing mounts 33 and 34 for bearings, in which the cover is running. Suitably these bearings are groove ball bearings but even other types of bearings are suitable.

Before an operator of the machine may start rotation of the cutblade 2 and set the same in working position the cover 25 has to be switched to the position shown with broken lines in fig 1. First thereafter it is possible for the operator to start rotation of the cutblade 2. The cover 25 is switched to said position by pressurization of the piston and cylinder assembly for movement of the carriage 12 from the position shown on the drawings to an upper position along the guide bar 13. During this movement the cable wheel 17 will pull the cable 23 via the cable wheel 18 and the cable wheel 9 and thereby the cover 25 will swing above the cover 28 to the position shown with dotted lines in fig 1. At the same time the cable 26 will

run over the cable wheels 10,16 and 15 for removing slack in the cable during the movement of the cover 25 from the position shown with solide lines in fig 1 to the position shown with dotted lines in fig 1.

Naturally it is possible to reverse the switching mechanism in such a way that pressurization of the piston and cylinder assembly 11 is required for replacement of the cover 25 to it ^' s rest position, whereby the cover 25 always will be set in the protective or safety position if the pressure in the piston and cylinder assembly is released unintentionally. Both in fig 1 and 2 is clarily shown that the work table 1 is completely free and available universally when the cover 25 is in the rest position shown with solide lines in fig 1. Suitably the piston and cylinder assembly 11 is of pneumatic type and valves may be arranged in such a way that pressurization is required for replacement from both the rest position and the working position.

The present invention should not be considered as restricted to that described above and shown on the drawings, many modifications being conceivable without departing from the spirit and scope of the appended claims.