Method and apparatus for the manufacture of an annular flange from metal strip

Abstract

 In the manufacture of an annular flange from a metal strip (1), the strip is held in a cylindrical shape in a channel (6) of a turntable (5) and an edge of the strip so held is bent preferably by forming. The flange is particularly suitable for packaging of steel coils.

Description

[0001] The invention relates to a method for the manufacture of an annular flange from a metal strip. Such a flange is for example intended for use in packing cylindrical products such as coils of steel. The invention also relates to an apparatus and a turntable for use in the manufacture of such a flange.

[0002] The flanges used in practice for packing coils of steel are manufactured by a method illustrated by Figs. 1a-d described below, in which a metal strip is first deformed into an angle bar by bending or an angle bar is directly taken as a starting point. The angle bar is deformed by feeding one of its two faces through two toothed wheels which are set in such a way that they create a flange. The diameter of the flange so formed depends on among other things the gap between and the oblique alignment of the toothed wheels and on the deformation properties of the strip.

[0003] This method is suitable particularly for manufacturing a series of flanges of the same diameter one after the other, after the correct settings have been found following the preparation of a number of test flanges. Evidence of this is also to be seen in the fact that flanges manufactured in this way intended for packing coils of steel are sold in a set range of sizes, the diameter sizes available commercially increasing in set increments.

[0004] In practice packing stations keep a stock of flanges with varying diameters and for each coil to be packed the closest flange size is then sought out. In most cases, since the diameters of rolled coils vary infinitely, the closest available flange size will not achieve an optimum fit around the coil to be packed.

[0005] Increasing the choice by reducing the increments in the size range does offer a solution to this problem but in practice may not be feasible because storage space at packing stations is generally too limited. Manufacturing the correct size in situ by the known method is also found to be impractical because there is always a restriction with the known method in relation to the resulting flange size, a restriction that is caused on the one hand by the manner of manufacture and on the other hand by the variation occurring in the deformation properties of the strip material used.

[0006] Another known method of making an annular flange is to deform a flat annulus of metal by bending one edge portion, as illustrated by GB-A-1404671 and GB-A-2147231.

[0007] The object of the invention is to provide a method and an apparatus by which flanges of the desired size may be manufactured reproducibly and efficiently. Preferably different sizes can be easily selected.

[0008] The method in accordance with the invention is characterized by the steps of :

(a) holding the strip by holding means in a cylindrical shape; and

(b) bending an edge portion of the strip held in said cylindrical shape to form said annular flange.

This provides a method for the manufacture of the flange with a reproducible resultant flange size; the flange size is no longer the unpredictable result of flattening and stretching between two toothed wheels, but emerges directly from the cylindrical shape in which the strip is held by the holding means.

[0009] The circular shape of the strip need not be exact, since there is usually some tolerance for the final shape of the flange.

[0010] In the method, simultaneously a plurality of strips may be held in the holding means and their edges bent together. This achieves a multiplication of the manufacturing capacity at very low cost.

[0011] In the method of the invention, the bending is preferably carried out by forming. In this context forming is understood to be the gradual deformation of the cylindrical strip, which is preferably rotating, into a flange by pressing it against a rotating forming tool. This method is particularly suited to automation, notably where carried out with the aid of the apparatus of the invention to be described.

[0012] The apparatus in accordance with the invention is characterized by holding means having a channel extending in a curved path for holding at least part of the strip in a circular shape, and bending means movable relative to the channel so as to bend an edge portion of the strip projecting from the channel to form the annular flange.

[0013] Preferably the channel is carried by a turntable.

[0014] This achieves the effect that the strip is free to rotate so that deforming may take place through rotation while the strip is held in a cylindrical shape so that the resultant flange size emerges predictably from the cylindrical shape.

[0015] The channel may be exactly circular, e.g. a complete circle, in which case the apparatus may further comprise means for feeding the strip into the channel tangentially and at an angle to the radial plane of the channel.

[0016] Alternatively the channel may have a spiral shape, which is not strictly circular, so that the diameter of the annular flange can be controlled by locating the strip at a location of the spiral channel of a desired diameter. In this case, the apparatus may have means for feeding the strip into the spiral channel comprising a clamp for the strip which is relatively movable radially and tangentially with respect to the channel. This spiral shape achieves the effect that the resultant flange size is infinitely adjustable by holding a strip of the correct length in a position in the spiral which corresponds with the desired flange diameter. The theoretical deviation from a pure circular shape occurring from the spiral shape can be so slight that it is negligible.

[0017] In a preferred embodiment of the apparatus in accordance with the invention, the bending means is tooling of the forming type. This forming tooling may comprise a set of conical rollers between which the projecting part of the strip fits, the conical rollers being movable radially in relation to the channel.

[0018] It should be noted that similar forming tooling is known from GB-A-2147231B. This patent specification deals with the manufacture of a lid with a bent edge.

[0019] The apparatus may comprise a yoke with a movable slide fitted to it on which the conical rollers are placed.

[0020] Preferably, during operation, the gap between the conical rollers is less than twice the thickness of the strip multiplied by the number of flanges to be manufactured simultaneously.

[0021] The invention also extends to the turntable for use in the method or the apparatus in accordance with the invention, having a channel of curved shape for receiving the strip.

[0022] Embodiments of the invention will now be described with reference to the drawings.

[0023] Figures 1a, 1b, 1c and 1d show strip, angle bar, deforming tool and flange in method steps used in current known practice.

[0024] Figures 2a, 2b and 2c show strip, deforming tool and flange in steps in a method embodying the invention.

[0025] Figures 3a, 3b and 3c show method steps and another apparatus in another embodiment of the invention.

[0026] Figure 3d shows the holder used in Figures. 3a-c, with additional parts, and Figure 3e is detail A of Figure 3d.

[0027] In the several Figures, the same reference numerals indicate corresponding parts. In the known method of Figures 1a-d a metal strip 1 in Fig. 1a is deformed by bending into an angle bar 2 when straight and flat as shown in Fig. 1b. By drawing this angle bar between two profiled wheels 2a,2b in the manner indicated in Fig. 1c, an annular flange 3 is formed which serves for example for packing coils of rolled steel as shown in Fig. 1d, which shows two flanges 3 at the ends of a coil 16.

[0028] In the method of the invention of Figs. 2a-c, first a metal strip 1 is fed in from a coil 4 in the vicinity of the apparatus (Fig. 1a). The flange-forming apparatus consists essentially of a holder in the form of turntable 5 with a complete circular channel or groove 6 in one face and bending means in the form of forming rollers 8,9. As shown in Fig. 2b the strip is fed into the channel 6 at a slight downward angle to the radial plane of the channel while simultaneously the holder is rotated so that the strip enters the channel 6 tangentially. The length of the strip is somewhat greater than the outside circumference of the channel 6 so that head and tail of the strip overlap one another. To make this overlap possible, the width of the channel is made slightly greater than twice the thickness of the strip.

[0029] The strip is now lying edgewise in the channel 6 and has an edge portion projecting out of the channel. In practice it may be necessary to press the strip against the underside of the channel using a suitable pressing means not shown in the drawing. Next the forming tool which has a pair of conical forming rolls 8,9 with a gap between them is brought into position and moved with a controlled movement radially inwards while the holder 5 rotates. For details of this forming process reference should be made to the content of the aforementioned patent specification GB-A-2147231B. It should be noted that here the shortest distance between the two forming wheels 8 and 9 which in accordance with GB-A-02147231 should be slightly less than the thickness of the strip, in the present case is slightly less than twice the strip thickness in order to make possible passage of the overlapping part of the flange in during formation.

[0030] After a few revolutions the strip part projecting above the holder is fully bent and the flange 3 of Fig. 2c is formed. The inner of the overlapping ends 13 of the metal is slightly contracted and the angle between the front (annular) part and the sleeve (cylindrical) part of the flange is somewhat greater than 90°, depending on the deformation properties of the strip.

[0031] In the embodiment of Figs. 3a-e, the strip 1 is fed tangentially into a holder having a turntable 14 containing a spiral channel 10 with the turntable 14 at standstill. After the strip has been fed in over a part of its length into the channel 10 (Fig. 3a), the strip is further advanced by simultaneous rotation of the turntable 14 so that the strip moves along the outside of the holder until a position is reached as shown in Fig. 3b. The strip is held in this position by for example guide rollers 11 on the turntable.

[0032] Next the head of the strip is held firmly by a clamping device 12 which is shown schematically in Fig. 3b and is freely movable radially and fixed tangentially relative to the turntable 14, while simultaneously the turntable 14 is rotated in the opposing direction. By holding the head of the strip while rotating the turntable 14, the strip is moved towards the centre of the spiral 10; travelling stops when the strip arrives at the desired flange diameter. The length of the strip is determined by the desired flange diameter. Then forming takes place by moving the forming tool 7 which is a pair of forming rollers, as shown in Fig. 3d in the direction of the arrow along a yoke 15 on which the tool 7 is supported by a carriage. In practice, the yoke 15 is made in such a way that it may be taken away for removal of the manufactured flange. During this, the direction of rotation of the turntable 14 may be reversed again, in order to prevent any relative motion of the strip relative to the turntable 14.

[0033] The clamping device 12 may also be suspended on the yoke 15 as shown in Fig. 3d. The turntable 14 is for example composed of a spider frame of crossing beams on which a twin spiral of curved pieces of strip steel is welded.

Claims

1. A method for forming an annular flange (13) from a length of metal strip (1) by bending the strip, characterised by the steps of :

(a) holding the strip (1) by holding means (5,10) in a cylindrical shape; and

(b) bending an edge portion of the strip held in said cylindrical shape to form said annular flange (13).

2. A method according to claim 1, wherein said holding means has a spiral channel (10), and said holding step (a) is performed by bringing the strip to a location in the spiral channel where the strip forms an approximate circle of a predetermined diameter.

3. A method according to claim 1 or claim 2 wherein a plurality of annular flanges (13) are formed by holding and bending a plurality of strips (1) simultaneously.

4. An apparatus for forming an annular flange (13) from a length of metal strip (1) characterized by holding means having a channel (6,10) extending in a curved path for holding at least part of the strip in a circular shape, and bending means (8,9) movable relative to the channel (6,10) so as to bend an edge portion of the strip projecting from the channel to form said annular flange.

5. An apparatus according to claim 4, wherein said channel (6,10) is carried by a turntable (5,14).

6. An apparatus according to claim 4 or claim 5, wherein said channel (6) is circular.

7. An apparatus according to claim 6 further comprising means for feeding said strip (1) into said channel (6) tangentially and at an angle to the radial plane of the channel.

8. An apparatus according to claim 4 or claim 5, wherein said channel (10) has a spiral shape, so that the diameter of the annular flange can be controlled by locating the strip (1) at a location of said spiral channel (10) of a desired diameter.

9. An apparatus according to claim 8 having means for feeding said strip into said spiral channel (10) comprising a clamp (12) for said strip which is relatively movable radially and tangentially with respect to the channel (10).

10. An apparatus according to any one of claims 4 to 9, wherein said bending means comprise a pair of rollers (8,9) having a bending gap therebetween, said pair of rollers being movable radially relative to said channel (6,10).

11. A turntable (5,14) for use as holding means for the strip (1) in the method of claim 1 or the apparatus of claim 4, having a strip-receiving channel (6,10) extending in a curved path.

Drawing