This invention relates to a method and to a machine for applying edge protectors on the edges of a coil

Coils, for example coiled cold rolled steel strip, are usually wrapped with paper or the like Their edges will easily be damaged and the damage can be on many turns, that is, over a considerable length of the strip Therefore, it is desirable to have a robust edge protector outside the wrapper Also unwrapped coils need edge protectors It is known in the art to apply manually pre-made edge protectors and fix them with straps

It is an object of the invention to make the application of edge protectors simpler and less costly To this end, the invention has been given the characteristics stated in the claims

The invention will be described with reference to the drawings that show a machine for applying edge protectors as an example of the invention

Figure 1 is a side view of the machine

Figure 2 is a side view seen as indicated by the arrows 2-2 in Figure 1 , but some detail in

Figure 1 are not shown

Figure 3 is a perspective view of a wrapped coil

Figure 4 is an enlarged view of a limit switch that is indicated in Figure 1

The machine shown on the drawings has two rollers 12, 13 arranged to carry a coil 14, for example a coiled cold rolled strip The rollers 12, 13 are coupled to a non-illustrated mo¬ tor that can rotate them, thereby rotating the coil 14 The rollers 12, 13 can be part of a walking beam device 15 for transporting the coil 14 along the axis of the coil The coil 14 and its central hole 16 is shown in Figure 1 Three coils 1 7, 18, 19 with smaller radii are also indicated in order to illustrate that the machine can be used for different coils sizes

The machine has a frame 22 that carries a strapping machine 23 that includes a part 24 that are inserted in and through the central hole 16 of the coil 14. The frame 22 and the strap¬ ping machine 23 are not shown in Figure 2.

A steel frame compises two similar beams 3 1 (only one can be seen on the drawings) that are coupled together by means of two cross beams 33, 34. The beams 31 are pivotally carried by two supports 35, 36 on a base plate 37 that is fixed to the floor. The entire frame 31 -34 will thus be pivotable by means of a hydraulic cylinder 38 about an axis I that is parallel with the rotation axes of the rollers 12, 13. The cross beams 33,34 make guides for two roll-forming units 41 , 42 that are displaceable along the guides 37, 34 by means of non-illustrated motors, for example hydraulic motors.

Flat steel strips 45, 48 are decoiled from coils 46, 47 to the roll-forming units 41 , 42. Each roll-forming unit 41 , 42 has a number of stations 51 , 56 with rollers 51 -56 that succes¬ sively bend the flat strip longitudinally into an L-section. Suitably, there is also a punch at the lower end of each roll-forming unit in order to punch a row of holes in the flat strip 45, 48 along the line which will then be the corner of the profile so that there will be holes through which water can escape. In their outer ends, each roll-forming unit has a curving roller 57, Figure 1 , that curves the L-shaped strip into a bow that substantially coincides with the bow of the coil 14 as can be seen in Figure 1 .

The downward bent edges 58 of the strips 45, 48 will then have crimps 59. The crimping makes it possible to elastically vary the radius of the curved strips 45, 48 within certain limits. Thus, the curving roller 57 can have a number of defined positions, for example four positions adapted to the four coils 14, 17, 18, 19 that are indicted in Figure 1 and still all coil diameters will be covered At the outer ends of each roll-forming unit 41 , 42, there is a hydraulically actuated cutter 61 , 62 and a position indicator 63, 64,

One of the position indicators 63, 64 is shown in Figure 4. It compises a wheel 65 on a lever 66 The wheel is arranged to be in contact with the end face of the coil 14. The lever 66 actuates a switch 67, and a gas spring 68 is arranged to present a force of for example

700 N The lever 66 does not actuates the switch 67 until the lever has swung a prede¬ termined angle Each roll-forming unit 41 , 42 has also a photo cell 69 for indicating the presence of a coil 14

The application of an edge protector will now be described

The roll-forming units always start from their upright home positions in which they are out of the way for the largest coil permitted

The photo cells 69, 70 sense the coil and controls the movement of the roll-forming units 41 , 47 towards each other or away from each other so that they will be moved into posi¬ tions just outside the coil 14 before they are pivoted down against the coil 14 Then, the roll-forming units 41 , 42 are moved towards the end faces of the coil 14 and when the switches 67 in the position indicators 63, 64 switches, the wheels 65 of the position indicators remain biased against the respective end face of the coil 14 with the biasing force, for example 700 N, emanating from the gas springs 68

The roll-forming units 63, 64 are now in their working positions and their roll-forming stations 51 -56 bend the strips 45, 48 into L-formed sections and curves them after they have been bent At the same time as the bent and curved strips 45, 48 are produced, they are pushed onto the edges of the coil 14 and the rollers 12, 13 rotates the coil 14 with a corresponding periferal velocity

When the ends of the strips 45, 48 have passed the top of the coil 14, the coil and the roll- forming units 41 , 42 are stopped The strapping machine 23, 24 now applies tightly a strap through the central hole 16 of the coil 14 and over the top of the coil Such a strap 75 is shown in Figure 3 Then, the coil 14 is again rotated simultaneously with the roll-forming units 41 , 49 producing and applying edge protecting strips 45, 48 This sequence is re¬ peated until the strips 45, 48 extend around the coil 14 with an overlap Before the appli¬ cation of the last strap, the cutters 61 , 62 cut off the strips 40, 48 The last and the first strap may be close to each other for keeping the first and last ends of the strips 45, 48 in

place. The strap close to the first end of the strips 45, 48 may be omitted since the strap on the overlap will hold both ends of the strips 45, 48. Alternatively, the strap on the overlaps can be omitted if, as a final operation, straps are applied along the edge protecting strips 45, 48 to hold down the outer ends of the strips 45, 48 In this case, the cutting may be

actuated after the application of the last strap longitudinally on the coil but before the application of the circumferential strap.

Sometimes, the entire edges of the coils need not be protected. Then, the edge protectors can be applied over just a part of the periphery of the coil.

In Figure 3, a packed coil 14 is shown that has edge protectors 45, 48, a protector 72 for the central hole, an annular end face protector 73, for example an annular fibre board, and four straps 74-77. Because the wheels 65 of the position indicators 63, 64 are forced against the end faces of the coil 14, any wrapper will be forced against the end faces of the coil 14 so that the edge protectors 45, 48 will be tight against the coil. Particularly when there is an end face protector 73 outside the paper as shown in Figure 3, a great force is needed to press the crimps and wrinkles under the protector 73 flat.

Suitably, the machine is automatised so that the entire operation of applying the edge protectors and the strapping is carried out in an automated sequence. The invention can be applied to other coils than steel coils, for example paper coils.