GB2201971A - Apparatus for preheating and/or annealing a wire-like metallic billet stock - Google Patents

Abstract

Apparatus for preheating and/or annealing a wire-like metallic billet stock (D), is provided including a series of rotatable spaced apart rollers (KR1, UR2, KR3, KR4, KR5, AR6) around each of which the stock (D) can be passed, in contact therewith and with a reverse in travel direction of the stock, for direct resistance heating of the stock via at least some of the rollers (KR3, KR4, KR5) in the series to which electric current is suppliable, wherein at least two of the rollers (KR1,3 or 5) or (UR2, KR4 or AR6) have individual drive means (8) each having a drive shaft (21,22), with the two drive shafts, and hence the rollers carried thereby, being disposed obliquely relative to each other at an angle of alpha 1 + alpha 2, and the drive means including means for varying the peripheral rotational speeds of the driven rollers to adjust each driven roller peripheral speed automatically to the relevant contacting billet stock speed thereby to minimise slip between the roller and contacting stock, for example by torque adjustment. <IMAGE>

Description

APPARATUS FOR PREHEATING AND/OR ANNEALING A WIRE-LIKE METALLIC BILLET STOCK This invention relates to apparatus for preheating and/or annealing a wire-like billet stock, such as a wire of relatively large cross-section.

Apparatus for the preheating and/or annealing of metallic billet stock, particularly wires, are known employing a series of resistance heating, driven rollers over which the wire is passed in contact with the rollers and reversed in travel direction at each roller. Drive for these rollers usually takes place from a common driving point, particularly through mechanical reduction systems rigidly disposed in a space so that once the ratio of the rotary speeds of the rollers has been fixed, it is no longer capable of being altered.

However as the wire passing through such known apparatus becomes heated, there is a lengthening of the wire from roller to roller and this may vary considerably according to the temperature level and the properties of the material being treated. In the case of copper wire, annealing generally aims at a final temperature of about 500or to 5500C and the temperature rise which occurs in the individual heating paths as well as the lengthening of the wire which it produces are at least approximately compensated for by the design of the transmission. - Any deviation from the required final temperature or the choice of a different wire material will, however, result in a different amount of wire lengthening so that the peripheral speed of the wire and the contacting rollers will no longer be the same.Then, the wire will either be inadmissibly stretched and in many cases over-stressed until it breaks or it will run with more or less considerable slip over the rollers which will lead to increased wire wobble and thus increased sparking.

This will result in damage to the wire surface which should not be underestimated, and also to increased wear and tear on the contacting rollers and can, furthermore, lead to unacceptable spark disturbance.

There is thus a need for a generally improved apparatus for reheating and/or annealing a wire-like metallic billet in which the wire is continuously heated or annealed in the most protective way possible, with the minimum of bending load and with minimum or no sliding over the rollers. Such an apparatus preferably is easily adaptable to all manner of applications, is simple in operation and easy to maintain.

According to the present invention there is provided an apparatus for preheating and/or annealing a wire-like metallic billet stock, including a series of rotatable spaced apart rollers around each of which the stock can be passed, in contact therewith and with a reverse in travel direction of the stock, for direct resistance heating of the stock via at least some of the rollers in the series to which electric current is suppliable, wherein at least two of the rollers have individual drive means each having a drive shaft, with the two drive shafts, and hence the rollers carried thereby, being disposed obliquely relative to each other at an angle of +or2, and including means for varying the peripheral rotational speeds of the driven rollers to adjust each driven roller peripheral speed automatically to the relevant contacting billet stock speed thereby to minimise slip between the roller and contacting stock.

For a better understanding of the present invention, and to show how the same may be carried into effect; reference will now be made, by way of example, to the accompanying drawings, in which: Fig. 1 is a perspective diagrammatic view of billet stock being guided through an apparatus according to a first embodiment of the invention, Fig. 2 is a block circuit diagram of the heating and/or annealing apparatus of Fig. 1 with three annealing paths, and with contacting and directionreversing rollers as well as a draw-off roller being shown in an in-line disposition for convenience, Fig. 3 is a side view from the front of the apparatus of Figures 1 and 2 according to the invention, Fig. 4 is a plan view, from above of the apparatus of Fig. 3, Fig. 5 is an end elevational view of the arrangement and construction of the rollers which are inclined by an angle i 1 as well as the electrical connections to a poly-phase current transformer, Fig. 6 is a transverse sectional view taken along the line VI-VI in Fig. 3 through the rollers inclined by an angler 2r Fig. 7 is an end view showing on an enlarged scale a subframe with rollers inclined at an angle o(1, Fig. 8 is an end view showing on an enlarged scale a subframe with rollers inclined at an a ngle d 2, and Fig. 9 is a perspective view of a further embodiment of apparatus of the invention with protective gas and cooling housings.

Wire-like metallic billet stock to be treated, hereinafter referred to briefly as 'wire' is designated D. As shown in Figure 1 it enters apparatus of the invention for preheating and/or annealing at De and leaves it at Da. The wire D runs initially onto a contacting roller KR1 and leaves it after making half a loop around it (i.e. a reverse in direction), whereupon it arrives at direction-reversing roller UR2. From here, the wire is reversed in direction and passes to contacting roller KR3 where it is reversed in direction and passed on to contacting rollers KR4 and KR5 at each of which it is reversed in direction from roller KR5 the, wire D passes to a draw-off roller AR6 where it is again reversed in direction and passed to the wire outlet Da.

As can be seen from Fig. 1 the rollers are spaced apart laterally and longitudinally with respect to their rotational axes so that the wire D passes through the apparatus in zig-zag fashion.

At least two of the rollers have individual drive means 8 each having a drive shaft 21,22. The drive shafts 21,33 and hence the rollers carried thereby, are disposed obliquely relative to each other at an angle of d1 +0(2.

Means are provided for varying the peripheral rotational speeds of the driven rollers to adjust each driven roller peripheral speed automatically to the relevant contacting wire D speed to minimise slip between the roller and contacting wire D. Thus the wire D is passed through the apparatus in a manner such that it is only stressed in a single bending direction.

Each drive means 8 and associated roller mounting 9 are carried on a first 10, 10a of two elongated sub-frame parts. In the illustrated embodiments there are six driven rollers and six drive means 8. The contacting rollers KR1, KR3 and KR5 form a sub group and are inclined at an angle Ot lof about 100 to the vertical V, with respect to their diameters, so that their top edges are inclined rearwardly towards the carrying sub-frame parts and remainer of the apparatus. On the other hand, the contacting roller KR4, the direction-reversing roller UR2 and the draw-off roller AR6 form a second group and have their top edges inclined forwardly away from the remainder of the apparatus by the angle 2 of about 10 to the vertical V. The size of the angle 41 orOl2 depends essentially upon the diameter and width of the rollers.

In Fig. 2, all the rollers are, for convenience, shown in line.

Reference numeral 7 denotes a three-phase transformer, the individual phases being designated R, S, T. Phase R is connected to the contacting roller KR3 while phase T is connected to the contacting roller KR4 and phase S is connected to the two contacting rollers KR1 and KR5. In this way annealing paths G1, G2 and G3 are formed in known manner.

Figs. 3 to 6 show the mechanical construction of the apparatus according to the invention. The individual contacting rollers KR1, KR3 KR4 and KR5, like the draw-off roll roller AR6 and the direction-reversing roller UR2, are mounted with their drive means 8 and roller mountings 9 on sub-frames 10, 10a, which may already have corresponding angles surfaces 11 and 12. In respect of the horizontal or the vertical V, the angles surfaces 11 and 12 assume an angled ore 2 of about 100 as can be seen from Figs. 5 or 6.

Bus bars 13 serve to carry electric current from the transformer to the indivual rollers for direct resistance heating.

It would be possible per se to achieve the intended oblique position of the rollers with a single sub-frame shape if the sub-frames were in each case rotated through 1800. This would however severely hinder free access to the operating side of the machine.

In order, however, to allow access to the relevant operating side of the machine and at the same time the adjustment or adaptation of the angle of inclination to the angled surfaces 11 and 12, it is preferable that the subframes 10 and 10a consist of at least two parts 23 and 24 and for these to be pivotally connected at 25 at one end which is nearer the rollers KR1, UR2, KR3, KR4, KR5 and AR6, while on the end of the sub-frame which is remote from the rollers, they are interconnected in the desired position by at least one supporting element 26. The number of supporting elements 26 will be governed by the anticipated loadings. As illustrated in Figs. 6 and 7 each element 26 is a bolt pivotally mounted at one end on the sub-frame part 24 and adjustably engaging at its other end the sub-frame part 23.

The apparatus of this invention can also be used for producing 'white' or clean wires. For this, all that is necessary (see Fig.9) is for the obliquely disposed contacting rollers KR4 and KR5 and the draw-off roller AR6 to be accommodated in housings which are hinged to open, with protective gas passing into the protective gas path through a pipeline 15 and into the protective gas housing 16 and thence into the pipeline 17. The housing 18 serves as a cooling tank. This latter is connected by a pipeline 19 to a cooling tank housing 20 which contains the draw-off roller AR6. From here, the wire D leaves the apparatus according to the invention in its treated form.

By providing self-contained drives for the contacting rollers and the draw-off roller, an extremely accurate wire tension can be set and maintained. To this end the individual drive motors of the contacting rollers and draw-off roller are linked in an electrical torque synchronisation circuit.

With this circuit the rotary speed of the individual drive unit motors self adjusts corresponding to the variation of wire stock speed resulting from temperature variation to maintain the set torque value.

As the drive means 8 and attached rollers form a block construction, the heating and annealing apparatus can be arranged in either a right-hand or a left-hand version, i.e. the wire can pass through the apparatus from the right-hand side towards the left-hand side or vice versa. Furthermore, gentle treatment of the wire is achieved in that the bending stress on the wire is kept minimal by using contacting and direction-reversing rollers of relatively large diameter while their disposition is such that the wire is always bent in just one single direction. By virtue of the fact that the wire runs straight onto the obliquely positioned contacting and directionreversing rollers, no contra banding of the wire is required so that it is only necessary to employ a relatively low driving output. Furthermore, all the rollers are at the same height so that no operating aids are needed. Finally, thanks to its open construction, the apparatus of the invention is designed for easy servicing.

Claims (12)

1. Apparatus for preheating and/or annealing a wire-like metallic billet stock, including a series of rotatable spaced apart rollers around each of which the stock can be passed, in contact therewith and with a reverse in travel direction of the stock, for direct resistance heating of the stock via at ~ least some of the rollers in the series to which electric current is suppliable, wherein at least two of the rollers have individual drive means each having a drive shaft, with the two drive shafts, and hence the rollers carried thereby, being disposed obliquely relative to each other at an angle of 41 2, and including means for varying the peripheral rotational speeds of the driven rollers to adjust each driven roller peripheral speed automatically to the relevant contacting billet stock speed thereby to minimise slip between the roller and contacting stock.

2. Apparatus according to claim 1, wherein the means for varying the peripheral rotational speeds of the driven rollers is a torque adjustment means operable to adjust the torque exerted by the drive means.

3. Apparatus according to claim 1 or claim 2, having six rollers, all of which have individual drive means.

4. Apparatus according to any one of claims 1 to 3, wherein 91 equals equals approximately 100.

5. Apparatus according to any one of claims 1 to 4, wherein the amount by which the rollers are spaced apart is at least partially variable so that the annealing path lengths between the rollers are adjustable.

6. Apparatus according to any one of claims 1 to 5, wherein the rollers and the obliquely disposed drive shafts are located so that a billet stock being treated is passed through the apparatus in a manner such that it is only stressed in a single bending direction.

7. Apparatus according to any one of claims 1 to 6, wherein each drive means and associated roller mounting are carried on a first of two elongated sub-frame parts, which first sub-frame part is pivotally connected to the second sub-frame part at the end of the first and second parts which is nearer the rollers and is spaced from the second part at the end of the first and second parts remote from the rollers by at least one supporting element which is adjustable to provide the desired angle (lor (2.

8. Apparatus according to claim 7, wherein each supporting element is a bolt pivotally mounted at one end in the second part and adjustably engaging at its other end, the first part.

9. Apparatus according to claim 7 or claim 8, wherein each pair of subframe parts are adjustable to enable the billet stock to be passed through the apparatus in a forward or in a reverse direction.

10. Apparatus according to anyone of claims 4 to 9 when appended to claim 3, wherein the rollers are spaced apart laterally and longitudinally with respect to their rotational axes so that the billet stock being treated passes around the rollers through the apparatus in zig-zag fashion.

11. Apparatus according to claim 10, wherein the last and penultimate rollers in the direction of travel of- the billet stock are each housed in an associated cooling tank housing, and wherein the roller immediately preceeding the penultimate roller is housed in a protective gas housing, all three housings being interconnected by pipelines.

12. Apparatus for preheating and/or annealing a wire-like metallic billet stock, substantially as hereinbefore described and as illustrated in Figures 1 to 8 or Figure 9 of the accompanying drawings.