GB2214846A

GB2214846A - Method and apparatus for treating wire

Info

Publication number: GB2214846A
Application number: GB8803992A
Authority: GB
Inventors: Russell John Chiplen; Antony Robert Franks; Neil Hamilton Mcbroom; Jeremy Nigel Speed
Original assignee: Allied Steel and Wire Ltd
Current assignee: Allied Steel and Wire Ltd
Priority date: 1988-02-20
Filing date: 1988-02-20
Publication date: 1989-09-13
Also published as: GB8803992D0

Abstract

Wire is treated to increase its formability by drawing the wire along a serpentine path so as to apply a predetermined strain to the wire as it follows the path. The strain applied to the wire may result in a reduction in the cross-sectional area of the wire of up to 6 per cent. The wire is drawn by capstan 1 through rollers 6 of mechanical stress relieving apparatus 2 prior to feeding the wire to a rail making machine 3. <IMAGE>

Description

METHOD OF AND APPARATUS FOR TREATING WIRE The present invention relates to a method of and an apparatus for treating wire and more particularly but not exclusively relates to the treatment of wire which is intended for cold heading, such as in a nail making process, so as to increase the formability of the wire.

It is known that during cold working such as in wiredrawing, steel hardens and the ductility (or formability) is reduced. This is exacerbated if the aging process occurs. When wire is to be drawn for making nails, it is also known that if the wire is drawn to a small diameter dependent on the material employed and whether or not aging occurs there is insufficient residual ductility or formability in the wire to enable a sound nail head to be formed during cold forming because a lack of ductility within the wire causes the head to split.

It is an object of the present invention to provide a treatment for wire which increases the formability of the wire in an economical manner.

According to one aspect of the present invention there is provided a method of treating wire which comprises drawing the wire along a serpentine path so as to apply a predetermined strain to the wire.

The strain applied to the wire may result in a reduction in the cross-sectional area of the wire of up to 6 per cent, preferably from 0.5 to 2.5 per cent.

The wire may be drawn along the serpentine path by means of a capstan around which the wire is wrapped. Preferably the serpentine path is defined by a plurality of rollers, the intermesh between the rollers being variable so as to enable adjustment of the predetermined strain applied to the wire.

According to a second aspect of the present invention there is provided an apparatus for treating wire comprising a plurality of rollers defining a serpentine path for the wire so as to apply a predetermined strain to the wire as it follows the path.

The rollers may be provided with peripheral grooves.

The apparatus may include a capstan for drawing the wire along the serpentine path.

Preferably the apparatus includes means for adjusting at least one of the rollers so as to alter the serpentine path and the predetermined strain. Five rollers may be provided.

A guide may be provided for guiding the wire to the rollers.

The invention also relates to a nailmaking apparatus which incorporates apparatus for treating wire as hereinbefore defined.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying figure which shows one embodiment of an apparatus for treating wire in accordance with the present invention.

Tests were carried out with wire made from two steels, A and B. Steel A is a rim substitute steel produced by the basic oxygen process and steel B is a rim substitute steel produced by the electric arc process.

The chemical analysis of these steels in per cent by weight is as follows: C Si S P Mn Cu Steel A 0.05 0.02 0.012 0.014 0.29 0.01 Steel B 0.05 0.08 0 033 0.017 0.40 0.15 Ni Cr Mo Sn Al N Fe Steel A 0.03 0.06 0.01 0.01 0.01 0.002 balance Steel B 0.06 0.05 - 0.026 - 0.008 balance Steel B has a higher level of silicon and residual elements which in turn give rise to an increased strength in the wire and lower residual ductility. It would therefore be expected that the tendency of nail heads to split when made from Steel B is greater than when made of Steel A and this is indeed the case as shown in the following Examples 1 and 2.

The wire ages after it is drawn and with aging carbon and nitrogen diffuse to the dislocations formed after the cold working of the drawing operation and serve to pin the dislocations. Aging thus leads to reduced residual ductility or formability and increased splitting of the nail heads.

We have found that it is possible to work soften the wire which frees the dislocations and improves the formability.

This leads to reduced splitting of the nail heads, but of course it is necessary to use the wire before aging takes place again. Although it is preferable to use the work softened wire as soon as the softening has taken place, for example in a continuous process, it is also possible to use the wire in a batch process within about a day or so of the work softening process and preferably within about 12 hours.

Example 1 (Comparative) A wire of 2.67mm diameter was drawn from Steel A and was made into both plain nails and clout nails. The average number of splits per nail head in the clout nails was 1.54 times that observed in the plain nails.

Plain nails require less deformation than clout nails and one would expect on production from the same material a lower average number of splits per head for plain nails.

Example 2 A wire of 2.67mm diameter was drawn from Steel B and was made into both plain nails and clout nails. The average number of splits per nail for the plain nails was 2.3 times that for the nails produced from Steel A. The average number of splits per nail head for the clout nails was 2.2 times that for the nails produced from Steel A.

Once again the plain nails showed a lower average number of splits per head than the clout nails. The relatively higher number of splits with Steel B compared with Steel A reflects the poorer surface quality and ductility of the Steel B.

In order to improve the ductility of the wire to make it easier to deform and to reduce the average number of splits the wire was passed around a capstan 1 and was drawn by the capstan as shown in the figure through a mechanical stress relieving apparatus 2 prior to feeding the wire to a nail making machine 3. The capstan 1 is not strictly necessary but is one example of means to pull the wire through the stress relieving apparatus. The stress relieving apparatus 2 comprises a plurality of rollers 6 of which two rollers are mounted on an adjustable platform and to give different intermesh settings 4 which give varying degrees of deformation and hence impart different amounts of strain.

The rollers 6 may have a groove around their peripheries to assist in maintaining the wire in position. A guide 5 guides the wire to the rollers 6.

Example 3 The apparatus shown in the figure was used to produce both plain nails and clout nails from Steel A and from Steel B.

The results are given in the following Table:

Intermesh Steel A Steel B (mm) Plain Clout Plain Clout w 0 100 100 100 100 (comparative) 5 64 75 i 77 75 10 63 53 73 68 15 54 44 67 59 20 47 41 55 55 25 34 29 51 39 28 1 22 41 37 TABLE - SPLITS INDEX The splits index which is representative of the number of splits in the nail heads compared with that at zero intermesh (zero strain) shows that the quality of the nails produced rises as the intermesh between the rollers increases for both Steels A and B and for both plain and clout nails indicating that passing the wire between the intermeshed rollers results in a greater formability of the steel.

Claims

1. A method of treating wire which comprises drawing the wire along a serpentine path so as to apply a predetermined strain to the wire.

2. A method according to claim 1, wherein the strain applied to the wire results in a reduction in the cross-sectional area of the wire of up to 6 per cent.

3. A method according to claim 2, wherein the strain applied to the wire results in a reduction in the cross-sectional area of the wire of from 0.5 to 2.5 per cent.

4. A method according to claim 1, 2 or 3, wherein the wire is drawn along the serpentine path by means of a capstan around which the wire is wrapped.

5. A method according to any preceding claim , wherein the serpentine path is defined by a plurality of rollers, the intermesh between the rollers being variable so as to enable adjustment of the predetermined strain applied to the wire.

6. A method of treating wire substantially as hereinbefore described with reference to the accompanying drawing.

7. An apparatus for treating wire comprising a plurality of rollers defining a serpentine path for the wire so as to apply a predetermined strain to the wire as it follows the path.

8. An apparatus as claimed in claim 7, wherein the strain applied to the wire results in a reduction in the cross-sectional area of the wire of up to 6 per cent.

9. An apparatus as claimed in claim 8, wherein the strain applied to the wire results in a reduction in the cross-sectional area of the wire of from 0.5 to 2.5 per cent.

10. An apparatus as claimed in claims 7, 8 or 9, wherein the rollers are provided with peripheral grooves.

11. An apparatus as claimed in any one of claims 7 to 10 and including a capstan for drawing the wire along the serpentine path.

12. An apparatus as claimed in any one of claims 7 to 11 and including means for adjusting at least one of the rollers so as to alter the serpentine path and the predetermined strain.

13. An apparatus as claimed in any one of claims 7 to 12 and including five rollers.

14. An apparatus as claimed in any one of claims 7 to 13 and including a guide for guiding the wire to the rollers.

15. An apparatus for treating wire substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.

16. Nail making apparatus incorporating apparatus for treating wire as claimed in any one of claims 7 to 15.