The present invention also relates to a method of removing impurities or waste products, such as slag, from a carrier member which is employed for supporting a workpiece being processed and which, during the processing, is given a layer or a more or less lumped or irregular coating of adhering waste products.

BACKGROUND ART In the laser cutting of sheet material, the sheet which is to be cut is placed on a carrier arrangement comprising a plurality of mutually approximately parallel carrier members. The carrier members are in the form of elongate rails standing on edge and whose upper edges undulate in shape so that there are formed, along a carrier member, a plurality of support points. The carrier members or rails are disposed with a few centimetres'mutual spacing so that the support points on all carrier members lie in a common plane. At their lower edges, the individual carrier members are united to one another to form a continuous unit which forms the carrier arrangement.

On cutting using laser, a jet of molten metal, slag or other waste products occurs which departs at high speed downwards from the underside of the cut metal sheet. Naturally, these waste products impinge on the rails when an incision line passes over such a rail, the jet of waste products striking the rail from above and adhering to it.

After a certain period of cutting, the carrier arrangement will be so severely polluted that its flatness can no longer be guaranteed. The accumulation of waste products may also be so severe that direct disruption to the cutting operation occurs.

In order to restore the carrier arrangement to its pristine condition, it must be regularly cleaned of adhering waste products, a process that has hitherto been carried out manually using hoes, picks, scrapers and similar implements. Such work is extremely time-consuming and in practice entails that a laser cutter may need to be rendered inoperative for several hours in order to have time to carry out the necessary cleaning of the carrier arrangement.

The carrier arrangement may, on numerous occasions, be of considerable dimensions so that it will be difficult and inconvenient to reach from the edge of the carrier arrangement into its centre. This means that the cleaning work will be extremely fatiguing and inconvenient.

Usually, the rails included in the carrier arrangement are made of copper, which is a soft and relatively fragile material. This entails that the risk of damage to the rails cannot be underestimated if the cleaning operation is carried out using, for example, picks, hammers or chisels.

The above-described problem is not only topical in laser cutting, but instead corresponding problems are encountered also in other types of processing, such as cutting with gas, certain types of grinding operations, cutting with a cutting disc, etc.

PROBLEM STRUCTURE The present invention has for its object to obviate the problems from which the prior art technology suffers. In particular, the present invention has for its object to realise a possibility of carrying out the cleaning of the carrier members in a rapid and convenient manner so that operational down times for the laser cutter will be minimal at the same time as the cleaning operation is facilitated and the risk of damage to the individual carrier members is eliminated.

SOLUTION The objects forming the basis of the present invention will be attained in respect of the apparatus if this is characterised by a guide member which is disposed to be moved along the carrier member, a cleaning device movable in relation to the guide member and having at least one movement component which is directed from the carrier member towards the guide

member, the cleaning device having engagement means disposed to engage with waste products adhering on the carrier member.

Concerning the method, the objects of the present invention will be attained if the method is characterised in that a cleaning device is moved along the carrier member and is caused to engage with and act on waste products adhering thereon at least in one direction which is substantially opposed to the direction in which the waste products were deposited on the carrier member.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 is a vertical front elevation of an apparatus according to the present invention; Fig. 2 is a vertical side elevation of the apparatus of Fig. 1; Fig. 3 is a cross section through a carrier member which has been subjected to cleaning in a first embodiment of the present invention; Fig. 4 is a top plan view of the apparatus of Figs. 1 and 2; Fig. 5 is a partial view from above of the apparatus of Fig. 4; and Fig. 6 is a cross section through a carrier member which is in the process of being cleaned in a second embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT It will be apparent from Figs. 1 and 2 taken together that the cleaning apparatus has a bottom plate 1 which fulfils the function of a guide member and which is disposed to guide the apparatus according to the present invention along a carrier member or a rail which is to be cleaned. The bottom plate 1 is of such a width that it can rest on more than one rail, preferably

three rails in the carrier arrangement in which the rails are included. In the bottom plate 1, there is secured a shaft or operating handle 2 which is of such a length that the apparatus according to the present invention may conveniently be moved in at least to the centre of the carrier arrangement which is to be cleaned when the operator of the apparatus according to the present invention stands beside the carrier arrangement. In such instance, the bottom plate 1 slides on the carrier arrangement and in the longitudinal direction of the individual carrier members which are to be cleaned.

It will be apparent from the Figures that the cleaning apparatus has a cleaning device 3 which is disposed on the underside of the bottom plate and which extends through an aperture therein. The cleaning device 3 is connected to a drive motor 4 by means of which it may be set in reciprocating motion transversely of the plane of extent of the bottom plate, i. e. in a direction upwards and downwards in Figs. 1 and 2 and transversely of the upper edge of a carrier member (not shown).

It follows from the foregoing that the cleaning device at least has one movement component which is directed from the carrier member to the guide member, i. e. the bottom plate 1. The cleaning device has engagement means 5 in the form of teeth which are disposed to engage with waste products 6 (Fig. 3) adhering on the carrier member in order to exercise a force against the waste products which is counter-directed to the direction in which the waste products were deposited on the carrier member 7. The above-described force action on the waste products 6 entails that they are subjected to a shearing force where the shearing plane is approximately parallel with opposing side surfaces of the carrier member 7.

It will be apparent from Figs. 1 and 3 that the cleaning device 3 is in the form of a fork which straddles the carrier member 7 and which has the teeth 5 disposed on the sides of the fork prongs facing towards one another, while the front and rear sides of the cleaning device 3 are completely smooth. The free space between the fork prongs 8 and 9 measured between the tips of the teeth 5 amounts to approx. 1.2-1. 7 times the thickness of the carrier member 7, preferably approx. 1.4 times this thickness. The term front side is here taken to signify the left-hand side of the cleaning device 3 in Fig. 2, while the rear side consists of the right-hand side of the cleaning device in Fig. 2, since, in normal operation, the apparatus according to the present invention is moved in the direction of the arrow 10 from right to left in Fig. 2. This notwithstanding, cleaning may also be carried out when the operators pulls the apparatus

according to the present invention towards him, i. e. in a direction opposite to that of the arrow 10.

It will be apparent from Fig. 3 that the teeth have upper engagement surfaces 11 which are transversely directed, preferably approximately at right angles to the movements of the cleaning device 3 according to the arrow 12. The teeth 5 further have lower surfaces 13 which make an acute angle with the direction of movement 12. Those edges, of the upper engagement surface 11, which are located most proximal the carrier member 7 are adjacent a narrow, vertical surface 14 which, in the normal position of use of the apparatus according to the present invention, is substantially parallel with the adjacent side surface of the carrier member 7. The extent in the vertical direction of the vertical surfaces 14 is slight in relation to the pitch of the teeth 5.

It will be apparent from Figs. 1 and 2 that the bottom plate 1 has an upwardly folded front portion 15 whose purpose is to facilitate the advancement of the apparatus according to the present invention in accordance with the arrow 10 along the carrier member 7 even though the upper edge of the carrier member is per se undulating and is moreover coated with waste products 6 which may have an uneven upper edge and which may consist of extremely hard and abrasive materials. In order to reduce the friction between the carrier member 7 and the waste products 6 adhering thereon, the bottom plate 1 has a smooth and even underside and also consists of a hard material, for example spring steel. It should be observed that the bottom plate fulfils the function of a wear plate which, on the one hand, is subjected to a grinding or scratching action from the waste products and which, on the other hand, is placed under stress by vibrating or impacting reaction forces from the engagement of the cleaning device 3 with the waste products 6. These vibrating or impacting reaction forces are transversely directed in relation to the plane of the bottom plate or wear plate 1.

On the upper side of the bottom plate 1, the apparatus according to the present invention has a base plate 16 which is produced from a lighter material, for example aluminium, and which serves for securing other components included in the apparatus according to the present invention. Thus, the handle 2 is secured in the base plate 16 by screw unions.

In the front end of the base plate 16 (the left-hand end in Fig. 2), there is secured an end plate 17 which is supported by means of side plates 18, one on either side of the cleaning device 3.

In addition, there is also a drive motor 4. Along the upper edge of the end plate 17, there is provided a top plate 19 which serves for securing the drive motor 4.

The two side plates 18 and the end plate 17 form a unit shown in Fig. 5 which serves for securing a guide for the cleaning device 3. The guide comprises two opposing guide blocks 20 and 21 which are manufactured from a durable material possessing low friction in relation to the cleaning device 3, for example a suitable plastic material. Both of the guide blocks 20 and 21 have mutually facing recesses 22 and 23, respectively, which together define an aperture in which the portion 24 of the cleaning device 3 located over the fork prongs 8 and 9 is accommodated. In that the front and rear sides of the cleaning device 3 are smooth, the cleaning device will be well guided in the recesses 22 and 23, whereby flexural forces which occur on displacing the apparatus according to the present invention in accordance with the arrow 10 (or opposite to this direction) will be absorbed by the guide blocks 20 and 21 and will thereby be prevented from having any direct effect on the drive motor 4.

It should be observed that the two guide blocks 20 and 21 do not meet one another but have gaps 25 and 26 between them which correspond to apertures in both the bottom plate 1 and the base plate 16. The purpose of these gasp and apertures is to facilitate the removal of loosened waste products 6 by there being provided in the drive motor a blower which acts against these gaps.

The two guide blocks 20 and 21 are readily replaceable in that they are fixedly clamped between a cross piece 27 and a yoke 28 which, by means of screws 29 and 30, may be tightened against the cross piece 27. In such instance, both of the guide blocks 20 and 21 have free-going bores for accommodating the $crews 29 and 30.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS Fig. 6 shows an alternative of the above-described cleaning device. The cleaning device in the embodiment according to Fig. 6 comprises two discs 31 and 32 which have a space 33 between them. The discs 31 and 32 are circular and are rotary about a common axis of rotation 34 in accordance with the arrow 35.

In the Figure, the two discs are interconnected by the intermediary of a connecting shaft 36 so that together they form a rigid unit.

On their sides facing towards one another at least along a peripheral band, the discs 31 and 32 have teeth 5 which are only partly shown in Fig. 6 but which are intimated by the broken lines 37 and 38. The teeth 5 may have the same design as that described above with reference to Fig. 3. The direction of movement of the teeth 5 in the area where they engage with the waste products 6 on the carrier member 7 is upwards, i. e. from the waste products towards the bottom plate 1 not shown in the Figure.

It will be apparent from the Figure that the width of the free space 33 between the tips of the teeth 5 is greater than the thickness of the carrier member 7. Suitably, the width of the space 33 may amount to approx. 1.2-1. 7 times the thickness of the carrier member 7, suitably approx. 1.4 times this thickness. The same relationship applies concerning the fork-shaped cleaning device in the embodiment according to Figs. 1-5.

In yet a further alternative embodiment, the cleaning device may include a rotary cleaning body disposed on either side of the carrier member 7 and which may be likened to an axial long gear wheel or a shank cutter. The cleaning bodies have axes of rotation which are parallel with the surfaces of the carrier member 7 but which slope in relation to the longitudinal direction thereof so that the lower ends of the cleaning bodies in Fig. 2 would be located to the left of their upper ends located at the bottom plate 1, i. e. would lie first in the direction of rotation according to the arrow 10. The cleaning bodies rotate in opposite directions so that they exercise a force on the affected waste products which is directed up towards the bottom plate 1 but possibly also forwards in the direction of advancement 10.

Also in this embodiment, the free distance between the peripheries of the cleaning bodies is greater than the thickness of the carrier member 7.