GB2042379A

GB2042379A - Method of producing semifinished nickel products

Info

Publication number: GB2042379A
Application number: GB8004833A
Authority: GB
Original assignee: HURDELBRINK G
Current assignee: HURDELBRINK G
Priority date: 1979-02-14
Filing date: 1980-02-13
Publication date: 1980-09-24
Also published as: FR2448945A1; CH642874A5; FR2448945B1; DE2905508C2; DE2905508A1; GB2042379B

Abstract

To reduce the cost of producing nickel strips, wires and other elongated forms of semifinished nickel products from electrolytically deposited nickel cathode plates and, at the same time, improve the purity of the products, the plates are converted directly into bars, which may be drawn and/or rolled, without a melting operation, by cutting and welding the plates. The plates may first be rolled to reduce their thickness. The plates may be cut into strips which are butt-welded end to end or the plates may be welded together to form wide strips which are then cut lengthwise to form the bars. Welding may be by nickel electrodes of high purity the electrodes being semifinished by the method of the invention.

Description

SPECIFICATION Method of producing semifinished nickel products The invention relates to a method of producing semifinished nickel products and concerns a method of producing nickel strips, wires and other elongated forms of semifinished nickel products of high purity, starting from plateform nickel cathodes which have been electrolytically deposited.

A hitherto known and widely practised method of producing pure nickel strips and so on provides for comminuting the cathode plates which are then melted in an electric furnace at temperatures above 1 600 C and cast into blcoks of up to 5 tin weight, so as then to obtain bars from the blocks, which are first again heated in a pusher-type furnace to about 1 200 C, in a rolling operation, as a starting product for a rolling or drawing treatment in a rolling mill.This expensive transformation of the raw material into bars results from the unfavourable form of the raw material caused by its electrolytic production; the nickel cathodes produced by electrolysis have a plate form (of about 950 x 920 x 10 mm for example), which is unsuitable for direct conversion into elongated shapes by rolling or drawing. The bars required for rolling or drawing are, therefore, conventionally produced by melting and then rolling down the cut blocks obtained from the melt. A disadvantage of this processing, which has hitherto been regarded as inevitable, is not only the heavy expenditure on labour and energy but also, in particular, the difficulty of keeping down the additional inevitable contamination by scaling during the melting and rolling operations.

It is the object of the invention to provide a cost-favourable, inexpensive method of producing nickel strips, wires and other elongated forms of semifinished nickel products from nickel cathode plates which leads, at the same time, to a greater purity of the semifinished product.

According to the invention, the method comprises converting the cathode plates directly into bars, without a melting operation, by at least the steps of cutting and welding, and then subjecting the bars to a rolling and/or drawing process.

With the method according to the invention, a conversion of the plate form into elongated bar form may be provided in a "cold" process in a surprisingly simple manner, in that the cathode plates are brought to the cross-sectional dimensions of the bar to be produced, during the cutting step, and are converted into the elongated bar by welding the cut parts together end to end.

The method of the invention refutes prejudices that the electrolytically deposited nickel has a non-homogeneous construction unsuitable for further direct "cold" processing and only becomes capable of being rolled and drawn after melting.

The cutting step and the welding step can be performed in either order, depending upon the machinery available, that is to say, narrow strips can first be cut out of the plates and then welded together to form long bars which can be rolled, or the plates can be welded together to form continuous wide strips before cutting or splitting takes place, so as to divide the wide strips into long bars which can be rolled. This leads first to a saving in labour and energy so that the costs of the method can be reduced to less than one third of the prior art method in which the plates are melted and cast into blocks or bars.

Even more significant are the advantages of the method according to the invention with regard to the purity of the product. Whereas by the conventional method, degrees of purity of 99.6 to 99.8% of nickel are obtained, a limiting value which can only be achieved with the utmost effort, and which cannot be exceeded with tolerable expense because of the contamination of the material in the melting and rolling operation in the electric furnace and in the rolling mill, now, using the method of the present invention, the possibility is opened up of achieving degrees of purity considerably above 99.90% and even more than 99.97% of nickel. Thus, analytical values considerably above the limiting values of rolled and drawn semifinished products hitherto produced can be achieved.At the same time, as is known, with greater purity, the material also gains considerably in its mechanical properties, which are important and desirable for the further processing of the material.

The use of such semifinished products is widespread. Thus, these are used for welding electrodes, for electrodes for shielded arc welding, for anodes for electroplating, for television tubes, electric lamps, sparking plugs, in the optical industry and also for components for the electrical industry. These fields of application predominantly require pure nickel in wire form. In addition, pure nickel strips are required for the production coins, for chemical apparatus, for fittings or for packings and tools. The high and increasing requirements from this field of application can be met to a much greater extent and at a favourable cost by using the present invention.

Fundamentally, various welding processes are suitable for the welding of the bar sections in the method of the present invention; preferably, however, the bar sections are connected to one another by butt-welding. Butt-welding can be carried out rationally and with high quality, for example using automatic flash butt-welding machines.

The welding together of the cathode plates is also possible using welding electrodes. The extreme purity of semifinished nickel products of the invention leads to welding electrodes of nickel with which, surprisingly, a welding of nickel plates is rendered possible (hitherto only usual using titanium electrodes). Thus, in the method of the invention, welds may be achieved using almost pure nickel electrodes so as not to introduce impurities.

If necessary, to achieve a more uniform malleability of the bars, required for their further processing, the bars may be subjected to a heat treatment, at least in the region of their welds, so that fractures in the region of the welds is eliminated during working of the bars by rolling or drawing.

The cutting or splitting can be carried out, for example with known roller splitting machines, the parallel roller knives dividing the plates into strips in one operation.

The plates can be subjected to a rolling operation before being divided into strips so as to reduce the thickness of the plates and facilitate the splitting of the plates into strips.

Specific embodiments of the present invention will now be described by way of example and not by way of limitation.

EXAMPLE I A nickel cathode plate, formed by electrolytic disposition has dimensions of 950 mmX 920 mm x 10 mm. The plate is cut up in a shearing or splitting machine into strips 10 mm wide to form bars with a cross-section measuring 10 mm X 10 mm and the bars are supplied to a butt-welding machine which welds the bars together end to end. The elongated bar leaving the welding machine is subjected to a drawing operation in a drawing machine which produces the required semifinished product in wire form in conventional manner. The semifinished product is then wound up into coils of 100 kg in weight for example.

EXAMPLE II Raw material in the form of nickel plates as used in Example I are cut into strips 200 mm wide using a shearing or splitting machine, to produce bars with a cross-section measuring 200 mm X 10 mm. These bars are supplied to a butt-welding machine which welds the bars together end to end. The elongated bar produced is then subjected to a rolling operation in a rolling machine and rolled out to form coin strips which are then wound into coils of 2 t in weight for example.

EXAMPLE Ill Nickel cathode plates formed by electrolytic disposition have dimensions of 950 mm x 925 mm x 10 mm. The plates are rolled out as a whole in order to reduce them to sheet form of a specific thickness. These sheets, up to 10 m long, are split, after which the bars so formed are connected end to end by welding. The bars produced are subjected to further rolling to reduce their thickness and finally wound into sheet nickel coils (up to 2 t in weight) on spools.

EXAMPLE IV Nickel cathode plates having the dimensions given in Example I are lined up and welded together at their abutting ends to form strips about 920 mm wide and 10 mm thick.

The welding is effected using nickel electrodes of high purity such as can be achieved by the present invention. The strips are then passed through a roller splitting plant which divides the strips into bars. The bars are then rolled out to form a required semi-finished product in the usual manner.

Claims

1. A method of producing nickel strips, wires and other elongated forms of semifinished nickel products of high purity, starting from plate form nickel cathodes which have been electrolytically deposited, the method comprising converting the cathode plates directly into bars without a melting operation by at least the steps of cutting and welding and then subjecting the bars to a rolling and/or drawing process.

2. A method as claimed in claim 1 in which the cathode plates are first cut or split into strips and the strips are welded together end to end.

3. A method as claimed in claim 1 in which the cathode plates are welded together to form wide strips which are then cut or split lengthwise.

4. A method as claimed in claim 1, 2 or 3 in which the welding step is effected by buttwelding.

5. A method as claimed in claim 3, in which the cathode plates are welded together using high purity nickel welding electrodes.

6. A method as claimed in any preceding claim in which the bars are subjected to heat treatment at least in the region of the welds.

7. A method as claimed in any preceding claim in which the bars have a width of about 10 mm and are drawn into wires.

8. A method as claimed in any preceding claim 1 to 6 in which the bars have a width of 100 mm to 200 mm and are rolled into strips.

9. A method as claimed in any preceding claim in which the cathode plates are rolled to reduce their thickness prior to cutting and welding.

10. A method of producing nickel strips, wires and other elongated forms of semifinished nickel products of high purity substantially as hereinbefore described with reference to Example I or Example II or Example Ill or Example IV.