This invention relates to the slotting of a work- piece such as an aluminium extrusion which may then be

A- 5 stretched to form an expanded panel.

A single head slotter is described in our International Australian patent application PCT/AU84/00234. In that machine, a multi-rib and web work-piece of repeating "H" section is secured to the work 10 table of the slotter and a router is then sequentially positioned between adjacent ribs to form the desired slot therebetween.

Although such a machine has the advantage of being easily adapted to cut a variety of arrays of slots, it is 15 not particularly suitable for the machining of a large number of work-pieces all having the same array of slots. In the production of expanded panels of a height of say 1.2 metres, it is appropriate to commence with an extrusion of 3.6 metres long which can be cut into three 20 panels either before or after stretching. Thus, the extrusion work-piece will need to be slotted with three repeating arrays of slots. For each panel, there may be a short slot at each end between first and second ribs and a long slot between the second and third ribs and so on 25 across the panel, with the short and long slots overlapping one another.

It is an object of this invention to provide a multi- head machine for cutting such an array of slots in a work- piece as the work-piece travels through the machine. 30 DISCLOSURE OF THE INVENTION

According to the invention there is provided a machine for forming a predetermined array of slots in a work-piece comprising:- i) a work table, 35 ii) feed rollers for driving the work-pieces over the work table.

iii) a multi-head cutter adapted to engage the work- piece as it is driven by the feed rollers and to form therein a plurality of slots of predetermined length and disposition, and, iv) means for moving the multi-head slotter into and out of cutting engagement with the work-piece.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings in which:

Fig. 1 is a perspective view of a slot forming machine according to one embodiment of the invention, and. Fig. 2 is an enlarged perspective view of the cutting station of the machine shown in

Fig. 1. BEST MODE OF CARRYING OUT THE INVENTION

The multi-head slotter shown in the drawings has a loading table 10 upon which the work-piece to be machined is placed. The loading table 10 has a plurality of conveyor rollers 11 to assist the manual feeding of the work-piece into the cutting station 12. First and second sets of feed rollers 13 and 14 are driven by a feed drive motor 15 through a gear box 16 by chain drive 17. The multi-head cutter 18 is mounted on a cutter carriage 19 that is pivotally and slidably mounted on a transverse bar 20 carried by the framework of the machine. In this instance, the cutter head 18 has nine carbide tipped blades profiled to give a radius effect at the ends of each slot. Beneath the carriage 19 there is a drive motor 21 which is coupled to the multi-head cutter 18 by belt drive 22. As is indicated in the drawings, the cutter head 18 is mounted beneath the work table of the machine which has appropriately positioned and dimensioned appertures to enable the cutter blades to engage the work- piece. A cover 23 is located above the cutting station.

The cutter head 18 is moved towards and away from the cutting station by a piston/cylinder arrangement 24 acting upon the free end of the cutter carriage 19. A swarf bin 25 is located beneath the cutting station. To the right of the cutting station 12 there is an exit table 30 which has conveyor rollers to assist movement of the work-piece. The exit table carries an indexing bar 31 which has mounted thereon adjustable stop blocks 32, 33 and 34. The indexing bar 31 is rotated by an indexing head 35 coupled to an indexing cylinder 36 whereby a selected stop block 32, 33 or 34 may be positioned in the path of the emerging work-piece. A feed cylinder 37 is actuated by the work-piece when it reaches the end of its travel to stop the feed drive motor 16. The leading end of the work-piece engages reversing block 41 which is moved in forward and reverse directions by the chain 42 that is coupled to the chain drive 17.

When the leading edge of the work-piece approaches the first set of feed rollers 13, the automatic sequence of the machine is brought into operation. The power driven feed rollers 13, 14 locate the work-piece and hold it in the correct position for slotting this is achieved by using feed rollers with a profile that suits the particular shape of the work-piece. The cutter 18 is raised from below the work table to engage the work-piece and, in this instance, simultaneously cuts nine slots in the work-piece as it is driven forward by the feed rollers 13, 14. For example, these slots may commence at the end of the work-piece and may be positioned between the first and second and the third and fourth ribs of the work-piece and so on across its transverse dimension. In the context of an expanded fence panel, these first cut slots would be short slots. When the work-piece strikes the first pre-set stop block 32, the cutting head is retracted from the work table and the cutter carriage is indexed sideways on the

bar 20 by the cylinder 40 so that the cutters will be positioned between the second and third and fourth and fifth ribs and so on across the transverse extent of the work-piece. At the same time, if the slots are to be overlapped the automatic operation of the feed rollers is adapted to reverse so that the work-piece is moved slightly back towards the entry guide.

The cutter head 18 is then raised from below the work table to engage the work-piece which is driven forward by the feed rollers 13 and 14 a sufficient amount to provide slots of required length.

When the work-piece strikes the second pre-set stop block 33, the cutter head 18 will again retract and the carriage will index back to its original position so that a third array of the short slots may be cut in line with the first array of short slots.

The diameter of the cutter blades on the cutter head 18 may be of the same dimension as the length of the short slots and in this case the work-piece will not be moved whilst the short slots are being cut. In the case of long slots, the work-piece will be moved forward by a sufficient amount to allow the cutters to cut the desired length of slot.

Chamfer rollers may be provided to engage the cut slots to iron down the burrs ready for removal by a deburring machine.

A cutter lubricant is pumped to the cutting station and is returned with swarf to the swarf box 25 where it is separated and returned to the lubrication sump. The entry feed rollers 13 and the exit feed rollers 14 are powered by the electric motor 15 (which is separate from the main drive) through a clutch to achieve the required intermittent forward and reverse feed motion. It will be appreciated, that by appropriate forward and reverse movement of the work-piece during non-cutting operations and by either moving the work-piece or holding

it stationery during cutting operations any predetermined array of slots may be cut in the work-piece. Although in this instance the cutter blades are spaced to engage between, say, the first and second and third and fourth ribs, they may be spaced together so as to engage between adjacent ribs should this be required for a particular array of slots.

Various modifications may be made in details of design and construction of the machine without departing from the scope and ambit of the invention.