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Title:
A PLANT FOR FORMING AN ELONGATED METAL STRING
Document Type and Number:
WIPO Patent Application WO/2009/002257
Kind Code:
A1
Abstract:
The present invention comprises a plant (100), for continuously forming a dimension- reduced elongated metal string (B) from a elongated metal workpiece (A). The metal work piece (A) is covered with a powder lubricant (C) at a covering station (11), and dimension- reduced at a downstream machining station (12). Said covering station (11) is co-ordinated with a high voltage generator (13), which electro-statically charges the powder parts in the lubricant, providing a homogeneous, lubricant cover (C) of said metal work piece (A). The electrostatic charge of the powder parts is allocated an appropriate potential according to the properties of the lubricant and the fact that melting temperature of the lubricant is lower than the temperature in the dimensionreducing machining station.

Inventors:
HAGA FREDRIK (SE)
LANDGREN BO (SE)
RUTKS REINOLD (SE)
Application Number:
PCT/SE2008/050742
Publication Date:
December 31, 2008
Filing Date:
June 23, 2008
Export Citation:
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Assignee:
HAGA FREDRIK (SE)
LANDGREN BO (SE)
RUTKS REINOLD (SE)
International Classes:
B21C9/00; B21C9/02; F16N15/00
Foreign References:
NL1004158C21998-04-10
GB2048145A1980-12-10
DE2433006A11975-02-06
US4445351A1984-05-01
GB1320133A1973-06-13
US5511403A1996-04-30
JPH07275922A1995-10-24
JPH04304298A1992-10-27
Attorney, Agent or Firm:
LINDBLOM, Erik, J. et al. (Box 6107, Stockholm, SE)
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Claims:

CLAIMS

1. A plant (100) for, from an elongated metal work piece ("A"), "continuously" being able to form a dimension-reduced elongated metal string ("B"), having a number of treatment, covering and/or machining stations, counted in the direction of transportation ("F") of the metal work piece, where a first treatment station (11), in the form of a covering station, is adapted to covering the metal work piece ("A") with a lubricant ("C"), structured to powder form, while a downstream situated machining station (12) is adapted to dimension-reducing the elongated metal work piece, surrounded by the powdered lubricant, to said elongated metal string ("B"), said first covering station (11 ) being co-ordinated with a high voltage generator (13) for, via an electrostatic charge of the powder parts in the lubricant, providing opportunities for a homogeneous, or in any case substantially homogeneous, lubricant cover on said metal work piece, characterized in that an electrostatic charge of said powder parts takes place via a control unit (14), initially within or connecting to said treatment station, and/or placed ahead of said covering station, within an additional treatment station (9) and is there allocated such a potential that the powder parts connect to said metal work piece ("A"), to a thickness that is controllable, depending on the structure and/or thickness of the metal work piece, that the potential is chosen to the electrostatic properties allocated the utilized lubricant ("C"), the charge properties thereof and/or the specific capacitance thereof and that said powder formed lubricant ("C") is allocated a melting temperature below the temperature that is generated in said dimension-reducing machining station (12).

2. Plant according to claim 1 , characterized in that to said control unit (14), an information-carrying signal is connected, corresponding to a selected powder formed lubricant.

3. Plant according to claim 2, characterized in that to said control unit, an information-carrying signal is connected, corresponding to a chosen particle size and/or a chosen mixture of particle sizes and/or particle materials.

4. Plant according to claim 1 , 2 or 3, characterized in that to said control unit, an information-carrying signal is connected, corresponding to a chosen powder fraction.

5. Plant according to claim 1 , characterized in that to said control unit, an information-carrying signal is connected, corresponding to a vibrating means, such as a vibration motor.

6. Plant according to claim 1 , characterized in that to said control unit, an information-carrying signal is connected, corresponding to a value for a high voltage to a precharging chamber.

7. Plant according to claim 1 or 6, characterized in that to said control unit, an information-carrying signal is connected, corresponding to a value for electrostatic charge within a covering station.

8. Plant according to claim 1 , characterized in that to said control unit, an information-carrying signal is connected, corresponding to a value for an electrostatic charge of a focusing electrode within a chamber, serving as a covering station, for a focusing of the powder material in a covering against the metal work piece.

9. Plant according to claim 1 or 8, characterized in that a treatment station and/or a covering station is put under a negative pressure, such as by seals against said metal work piece as well as against a metal work piece, covered by a powder formed lubricant.

10. Plant according to claim 1 , characterized in that the electrostatic charge of said powder parts is, via a control unit, within said covering station and/or placed ahead the same covering station, within an additional treatment station, allocated such a potential that the powder parts connect to said metal work piece to a chosen thickness, which depends on the structure and/or thickness of the metal work piece, the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/or the specific capacitance thereof and that said powder formed lubricant is al-

located a melting temperature below the temperature that is generated in said treatment station.

Description:

TITLE OF INVENTION: A plant for forming an elongated metal string.

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a plant for producing or forming, by means of the same and a number of process steps included therein, an elongated and machined metal string.

More particularly, it is a question of carrying out, by a plastic machining or deformation of a metal string, in the form of a metal material, such as a sheet-metal plate, a strip and/or a wire as a metal work piece, a rolling or a wire drawing of the metal material in a cold state.

The plant, in accordance with the present invention, is in that connection adapted to from an elongated metal work piece, here designated "continuous", forming a dimension-reduced elongated metal string, in the form of a semifinished product or a finished product, during utilization of a number of, counted in the direction of transportation of the metal work piece and/or of the metal string, process steps orientated within the plant, in the subsequent description designated as serially orientated treatment and/or machining stations.

In that connection, a treatment station may be adapted to covering the metal work piece with a lubricant, structured to a powder form, to enable and/or improve the function of a machining station orientated and situated downstream, especially adapted to, via a wire drawing in a cold state, dimension-reducing the elongated metal work piece, surrounding the powdered lubricant, to said elongated metal string.

The lubricant should now be applied around utilized metal work piece before it is subjected to a dimension-reducing machining, wherein said treatment station should be co-ordinated with a high tension generator for, via an electrostatic charge of the powder parts within the lubricant, providing electrical fields to afford opportunities for a homogeneous, or in any case substantially homogeneous, lubricant covering of said metal work piece.

BACKGROUND OF THE INVENTION

Methods, arrangement/arrangements and constructions related to the above-mentioned technical field and having a function and a nature, which meet requirements made are previously known in a plurality of different embodiments.

Such as examples of the background art and the technical area or field to which the invention relates, different sets of plants may be mentioned to, from an elongated metal work piece, in a cold state "continuously" be able to produce a dimension-reduced elongated metal string, having a number of treatment and/or machining stations orientated, counted in the direction of transportation of the metal work piece, where a treatment station is adapted to covering the metal work piece with a lubricant, structured to liquid state or powder form, while a downstream situated machining station should be adapted to dimension-reducing the elongated metal work piece, surrounding the liquid or powdered lubricant, to said elongated metal string, in the form of a sheet-metal plate, a strip and/or a wire.

Such a treatment station, for an application of a lubricant in liquid state, is shown in more detail in figure 1 of the Patent Publication NL-C-1 004 158, and which has be-

en appended to the present application also as Figure 1 , with an intention to making clear the relevant background art of the technique.

Figure 2 of said patent publication shows and describes an arrangement, where a powder formed lubricant should be supplied to a metal work piece, during the utilization of a fluidizing bed.

It is furthermore known to supply a powdered and/or powder formed lubricant by providing, within said treatment station, opportunities for a co-ordinated application of the lubricant against the metal work piece by means of a high voltage generator, in order to, via a chosen electrostatic charge of the powder parts, the powder particles and/or the powder fractions within the lubricant, try to provide opportunities for a homogeneous, or in any case substantially homogeneous, lubricant covering of said metal work piece.

It is furthermore known to in different process steps preparing, by a surface treatment, a metal work piece before it is subjected to a lubricant covering, where said treatment primarily may consist of an applied covering on a pickled surface by means of salt crystals, such as, for instance, borax.

The contents of the following patent publications also belong to prior art;

JP-7 275 922 shows and discloses an electrostatic application of a lubricant or a drawing means to form a wire.

The patent publications GB-A-2 048 145; DE-A-2 433 006; US-A-4 445 351 and GB-A-1 320 133 provide different variants related to the technical field of the present invention.

It is also known that certain selected powdered and/or to powder grounded and formed lubricants have, for the lubricating application, good electrostatic properties, as well as specific charge properties and as well as afford a specific capacity or capacitance.

It is also per se previously known different methods to be able to establish a value for the electrostatic properties of a blank, the charge properties thereof and/or the specific capacity or capacitance of the blank.

Thus, it is previously known to measure a decay time and specific capacitance for a material and in this respect reference is made to the publication "Journal of Electrostatics" 54 (3/4), March 2002, page 223, with "New Approaches for Electrostatic Testing of Materials".

SUMMARY OF THE PRESENT INVENTION TECHNICAL PROBLEM

If attention is paid to the circumstance that the technical considerations, which a person skilled in the relevant technical field has to do to be able to present a solution to one or more technical problems raised, are, on one hand, initially a necessary understanding of the measures and/or the sequence of measures that have to be taken, and on the other hand a necessary selection of the means that is/are required, then the subsequent technical problems would, in view of this, be relevant in the creation of the present subject matter of invention.

Therefore, in view of the prior art, as it has been described above, it should be seen as a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required to at a plant, to from an elongated cold metal work piece "continuously", be able to produce a dimension-reduced elongated metal string, by means of a number of treatment and/or machining stations, counted in the direction of transportation of the metal work piece, where a treatment station is adapted to covering the metal work piece with a lubricant, structured to a powder form, while a downstream situated treatment station should be adapted to dimension-reduce the elongated metal work piece, surrounding the powdered lubricant, to said elongated metal string, in the form of a semifinished product or a finished product, said treatment station being co-ordinated with a high voltage generator, for providing, via an electrostatic charge of powder parts, powder particles and/or the powder fractions in the lubricant, opportunities for a homogeneous, or in any case substantially homogeneous, lubricant covering of said metal work piece and providing opportunities to be able to select

the electrostatic and or mechanical properties of the powder shaped lubricant in such a combination that said dimension-reduction can take place in an efficient and functionally safe way and with a dimension-reduction that, if required, can be regarded exceeding what till now has been regarded as possible and having a surface structure of high quality.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required to allow a chosen total electrostatic charge of said powder parts within a covering station and one during utilization of focusing electrode, to take place within, in any case, two separated process steps.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for providing a covering process of a lubricant structured to a powder form to the outer surface of the metal work piece, which does not require a preliminary surface treatment, such as an initial pickling process and if required, a subsequent covering on the surface by means of salt crystals, such as borax.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for, via a control unit, to start with within a treatment station which is placed ahead of a first treatment station, where a covering of the metal work piece takes place with a lubricant formed to a powder form, allowing the powder parts to get allocated such a potential that the powder parts connect to and attach to said metal work piece to a thickness that is controllably depending on the structure and/ or thickness of the metal work piece and the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/or the specific capacitance thereof and that said powder formed lubricant in addition should be allocated a melting temperature below the temperature that is generated at said machining station from a cold metal work piece, which is dimension-reduced to a metal string.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will

be required for connecting an information-carrying signal to said control unit, the signal structure of which is intended to unambiguously represent the significative properties that will correspond to a selected and utilized powder formed lubricant.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent the special properties that are associated with a chosen particle size and/or a chosen mixture of particle sizes and/or utilized particle materials.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent the significative properties that can be allocated a chosen powder fraction.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent the significative peculiarities that should be associated via vibrating means, to be able to control a dosage equipment, where said means, in a practical application, may be allocated the form of a vibration motor.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent a selected value for a high voltage level, feedable to a precharging chamber and/or a chosen construction for the same precharging chamber.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will

be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent a selected total value for a chosen electrostatic charge of chosen particles.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for connecting, to said control unit, an information-carrying signal, the signal structure of which is intended to represent a selected value for a electrostatic charge generated by an especially formed focusing electrode within a covering station for a focusing of the charge of the powder material in a covering against a selected metal work piece and the cross-section and/or length thereof within the station.

There is a technical problem to be capable of realizing the significance of, the advantages associated with and/or the technical measures and considerations that will be required for allowing one or more of the covering stations and/or one or more of the treatment stations being put under a negative pressure, such as by means of seals against said metal work piece and a metal work piece, covered by a powder formed lubricant.

THE SOLUTION

The present invention is, in that connection, based on the known technique provided by way of introduction concerning a plant, for "continuously" being able to form, from an elongated metal work piece, a dimension-reduced elongated metal string, having a number of treatment and/or machining stations, counted in the direction of transportation of the metal work piece, where a first treatment station, in the form of a covering station, is adapted to covering the metal work piece with a lubricant structured to powder form, while a downstream situated machining station is adapted to in a cold state dimension-reducing the elongated metal work piece, surrounding the powdered lubricant, to said elongated metal string, said treatment station being co-ordinated with a high tension or voltage generator, for providing, via an electrostatic charge of the powder parts, the powder particles and/or the powder fractions within the lubricant, opportunities for a homogeneous, or in any case

substantially homogeneous, lubricant cover of said metal work piece with or without a preliminary surface treatment.

In order to be able to solve one or more of the above-mentioned technical problems, the present invention more especially provides that the known technique should be supplemented with allowing the electrostatic charge of said powder parts, via a control unit, within said treatment or covering station and/or placed ahead of this station in an additional treatment station, being allocated such a potential that the powder parts, connect to said metal work piece, is to be to a thickness, which becomes depending on the structure and/or thickness of the metal work piece, the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/or the specific capacitance thereof and that said powder formed lubricant should be allocated a melting temperature below the temperature that is generated at said machining station reducing the cross-section.

Such as proposed embodiments, falling within the scope of the fundamental idea of the present invention, it is in addition provided that to said control unit, there should be connected an information-carrying signal, corresponding to the electrostatic conditions existing for a selected powder formed lubricant.

To said control unit, there should furthermore be connected an information-carrying signal, corresponding to a chosen particle size and/or a chosen mixture of particle sizes and/or particle materials.

To said control unit, there should furthermore be connected an information-carrying signal, corresponding to a chosen powder fraction and to said control unit there should furthermore be connected an information-carrying signal, which can be associated a vibrating means, to be able to control a dosage equipment, where said means in the practical application may be allocated the form of a vibration motor.

To said control unit, an information-carrying signal is connected, corresponding to a value for a chosen total electrostatic charge.

To said control unit, there should in addition be connected an information-carrying signal, corresponding to values for a sequentially desired electrostatic charge.

To said control unit, an information-carrying signal is connected, corresponding to a value for a high voltage to a treatment station in the form of a precharging chamber.

To said control unit, an information-carrying signal is also connected, corresponding to a value for an electrostatic charge of a focusing electrode contained within a covering station and/or within a precharging chamber, serving as a treatment station, for a focusing of a precharged powder material for a solid covering against the metal work piece.

According to the provisions of the invention, it is provided that a treatment station, such as a charge chamber and/or a covering station having the focusing electrode thereof, should be possible to be put under a negative pressure, by, among other things, seals against said metal work piece and against a metal work piece covered by a powder formed lubricant.

Furthermore, it is provided that the electrostatic charge of said powder parts can, via a control unit, within said treatment or covering station and/or placed ahead of this treatment station in an additional treatment station, be allocated such a potential that the powder parts connect to and adhere to said metal work piece to a thickness, which depends on the structure and/or thickness of the metal work piece, the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/or specific capacitance and that said powder formed lubricant should be allocated a melting temperature below the temperature that is generated in said treatment station.

ADVANTAGES

The advantages that foremost may be regarded as characteristic of the present invention and the special significative features provided thereby are that, in this way conditions have been created for at a plant, in order to be able to "continuously" form, from a cold elongated metal work piece, a dimension-reduced elongated metal string, having a number of treatment and/or machining stations, counted in the

direction of transportation of the metal work piece, where a covering station, serving as a treatment station, is adapted to covering the metal work piece with a lubricant structured to powder form, while a downstream situated machining station is adapted to dimension-reducing the elongated metal work piece, surrounding the powdered lubricant, to said elongated metal string, said covering station being co-ordinated with a high voltage generator, for providing, via an electrostatic charge of the powder parts in the lubricant, opportunities for a homogeneous, or in any case substantially homogeneous, lubricant cover of said metal work piece.

According to the invention, the electrostatic charge of said powder parts, via a control unit, within said covering station and/or placed ahead of this station in an additional treatment station, should be possible to be allocated such a potential that the powder parts, connect to or adhered to said metal work piece, exposes a thickness, which depends on the structure and/or thickness of the metal work piece, the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/ or the specific capacitance thereof and that said powder formed lubricant is allocated a melting temperature below the temperature that is generated in said treatment station for a dimension-reduction, to thereby be able to provide opportunities for a simple and efficient forming or production of a dimension-reduced metal work piece.

Especially, it is provided that the dimension-reduction can take place without a preliminary surface treatment of the metal work piece, before this blank is covered with a powder formed lubricant.

What foremost can be regarded as characteristic of the present invention is defined in the characterizing clause of the subsequent claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

A known technique and a presently proposed embodiment, having the significative features associated with the present invention, will now, for the purpose of exempli-

fying, be described more in detail, reference being made to the accompanying drawing, wherein;

Figure 1 shows the known technique, according to the Patent Publication NL-C- 1 004 158 and figure 1 shown therein, and having utilized reference designations or numerals given within parenthesis,

Figure 2 shows in a block diagram a plant having different process steps, in accordance with provisions, which are given in accordance with the present invention,

Figure 3 shows in a block diagram form a control unit which, in accordance with the present invention, should control the functions within the plant and the process steps thereof and

Figure 4 shows in side view a construction of a treatment station, in the form of a precharging chamber and a treatment station, in the form of a covering station, through which an untreated wire, as a metal work piece, is passing in order to via an electrostatic charge of powder particles be able to leave a charging chamber as a lubricant covered metal work piece, before a treatment takes place in a machining station or a dimension-reducing unit, in the form of a draw plate (drawing stone or nozzle).

DESCRIPTION OF PRIOR ART ACCORDING TO NL-C-1 004 158.

With a reference to figure 1 , the known technique is shown there, according to the Patent Publication NL-C-1 004 158 and figure 1 shown therein.

From this, it is seen that the reference designation or reference numeral (1 ) relates to a drawing stone, carried by means of a support (3) and a frame (2).

A dimension-reduced wire (8) is fed to a roll or bobbin (9), carried by a support (10).

Here a spray device (14) is provided with spray nozzles (15), (16), carried by supports (17), (18), and which are fed with liquid lubricant, via each a conduit (19), (20).

Figure 2 in this patent publication provides the utilization of a fluidized bed during the utilization of electrodes to distribute a powder formed lubricant along the metal work piece.

Other reference designations or reference numerals in figure 1 relate to details in the mentioned patent publication and should accordingly be distinguished from the reference designations and numerals that in the following are utilized to illustrate the present invention.

DESCRIPTION OFA PRESENTLY PROPOSED EMBODIMENT

It should then by way of introduction be emphasized that in the subsequent description of a presently proposed embodiment, which has the significative features associated with the invention and which is elucidated by the figures shown in the appended drawings, we have selected terms and a particular terminology with the intention to thereby primarily allow to make evident the inventive idea.

It should, however, in this connection be taken into consideration that expressions selected here should not be seen as limiting solely to the terms utilized and selected here, but it should be understood that each term selected in this manner should be interpreted so that it, in addition, comprises all technical equivalents operating in the same or substantially the same way, in order to, in this way, enable the achievement of the same or substantially the same intention and/or technical effect.

Thus, with a reference to the appended figures 2 to 4 not only the present invention is shown schematically and in detail, but also the significative peculiarities associated with the invention have been made concrete, by the presently proposed embodiment described more in detail in the following and hereunderbelow.

Thus, the figure 2 allows showing, in a block diagram form, a plant 100 for being able to form, from an elongated metal work piece "A" continuously and in a cold state, a dimension-reduced elongated metal string "B", having a number of treatment, covering and/or machining stations, counted in the direction of transportation "F" of the metal work piece and of the metal string, where a treatment station 11 , in the form of a covering station, is adapted to covering the metal work piece "A" with a lubri-

cant "C", structured to a powder form while a downstream situated and arranged machining station 12 is adapted to dimension-reducing the elongated metal work piece "A", surrounded by the powdered lubricant "C", to said elongated metal string "B", said covering station 11 being co-ordinated with a high voltage generator 13, for providing an electrostatic charge of the powder parts in the lubricant "C", causing opportunities for a homogeneous, or in any case substantially homogeneous, lubricant cover on said metal work piece "A".

The figure 2 now allows illustrating the presence of a container 1 , of a homogeneous lubricant, a mill 2 for milling the same lubricant as well as a screen arrangement 3 to separate a desired lubricant fraction and lubricant granular size to a container 4.

A buffer container 5 and a vibrating feeder 6 are arranged to lead the powder fractions to an additional container 8.

An electrostatic precharging of the particles will take place in a treatment station 9 or a precharging chamber 9 significative of the invention, as well as be fed pre- charged to the covering station 11 , in which a focusing electrode 10 is installed.

The metal work piece "A" becomes, after said covering station 11 , covered with a layer of lubricant "C" and is fed to a drawing stone 12, to leave said drawing stone 12 as a dimension-reduced metal string "B'", surrounded by a thin layer "C" of a melted grease or lubricant.

The electrostatic charge of said powder parts is, via a control unit 14, within or connecting to said covering station 11 and/or placed ahead of the same covering station 11 in an additional treatment station 9, allocated such a total potential that the powder parts connect to said metal work piece "A" to a thickness, which depends on the structure and/or thickness of the metal work piece, the electrostatic properties allocated the utilized lubricant, the charge properties thereof and/or the specific capacitance thereof and that said powder formed lubricant "C" is allocated a melting temperature, which by an adapted value should be below the temperature that is

generated during a chosen dimension-reduction and a chosen speed within said machining station or drawing stone 12.

To said control unit 14, in connection with figure 3, an information-carrying signal 14a is connected, corresponding to a selected powder formed lubricant "C".

The cable or connection that should carry this information-carrying signal 14a should have a signal pattern significative of one or more of and in any case the following criteria:

A The physical and chemical properties of the lubricant.

B The electrostatic properties of the lubricant.

C The charge properties of the lubricant.

D The specific capacitance of the lubricant.

E Present and chosen high voltage within a precharging chamber 9.

F Present chosen high voltage within a treatment or covering station 11 for a focusing electrode 10, applying the lubricant against the metal raw material.

G Present chosen high tension within the longitudinal orientation of the covering station 11 and an elongated focusing electrode 10 orientated therein as well as the constructive design of the focusing electrode within the station 11.

H The structure of the metal work piece "A", what relates to the outer dimensions thereof.

I The structure of the metal work piece "A", what relates to the outer surface thereof.

J The metal structure of the metal work piece "A".

K The speed "F" of the metal work piece "A" through the covering station 11.

L The length of the covering station 11.

M Chosen dimension-reduction by the drawing stone 12

To said control unit 14, an information-carrying signal 14b is connected, corresponding to a chosen particle size and/or to a chosen mixture of particle sizes and/or chosen particle materials.

To said control unit 14, an information-carrying signal 14c is connected, corresponding to a chosen powder fraction.

To said control unit 14, an information-carrying signal 14d is connected, corresponding to a vibrating means for being able to control a dosage equipment, where said means in the practical application may be allocated the form of a vibration motor.

To said control unit 14, an information-carrying signal 14e is connected, corresponding to a value for a chosen electrostatic charge.

To said control unit 14, an information-carrying signal 14f is connected, corresponding to a value for a chosen high voltage, feedable to a precharging chamber 9.

In accordance with the present invention, it is especially provided that the covering station 11 having the focusing electrode 10 thereof should be able to act under a negative pressure and on that occasion with a seal 11a, for the metal work piece "A", and a seal 11b for a metal work piece "A", covered by means of a powder formed lubricant "C".

Figure 3 shows in a block diagram form the control unit 14, which in accordance with the present invention should control the functions within the plant.

In the preceding, a selection of criteria have been indicated to control the process through the plant 100.

It is within the scope of the invention to provide also other criteria than the above- mentioned ones.

More particularly, it is a question of being able to adjust the supply of utilized powder-shaped or dust-shaped lubricant, the selection of high voltage values within a precharging or precharging zone 9, the selection of high voltage values within the covering station 11 for a focusing electrode 10 formed therein and the selection of dimension-reduction within the drawing stone 12, for providing a plant where requisite lubrication effect is retained also in great dimension-reductions against slender

or thin metal strings "B ' ", during long work cycles and during relatively high feed speed.

Figure 4 shows in side view the principles of a construction of a covering station 11 or a charging chamber co-ordinated with said focusing electrode 10 and a charging chamber 9 placed ahead and where figure 4 intends to in addition illustrate the utilization of an untreated wire, as a metal work piece "A", where said wire is passing in order to via an electrostatic charge of powder particles be able to leave the same charge chamber 11 as a lubricant covered "C" metal work piece "A", before a treatment takes place in a dimension-reducing unit 12, in the form of a draw plate (drawing stone or nozzle), and where a dimension-reduced metal string "B ' " becomes surrounded by a thin layer of a dimension-reduced lubricant "C".

The invention provides that a pre-treatment of the metal work piece "A" can be carried out if required, even if the invention provides that such a cleaning pre-treatment in the normal case is not requisite.

Such a cleaning may then initially take place in a pickle while a subsequent treatment normally can take place using a saline solution e.g., a borax solution, for creating a roughness that is required in order for a sufficient quantity of lubricant should be possible to be brought with the wire into the draw plate 12 and give sufficient lubrication.

By means of this invention, the main object is to be able to eliminate this pre-treatment step and thereby be able to reach a more inexpensive production as well as an even higher production capacity and a higher quality of the metal string related thereto.

The lubricants, which can be possible to use, have to have well defined electrostatic properties.

These properties are primarily measured using a decay time meter, such as a meter marketed under the trade mark "JC1155", values for the decay time, from maximum

value (peak value) down to "1/e" and 10 %, respectively, of maximum value, being of decisive importance and will then be possible to be established in seconds.

The present invention is based on the understanding that these properties should have values between 0,1 and 10 000 sec, such as more especially between 10 and 1000 sec.

In addition, a value should be established of occurring specific capacitance (capacitance loading) to guarantee that a loading amount present for the function can be supplied to the lubricant structured in powder form.

The lubricants feasible for this should have a sufficiently long decay time to be possible to be applied to the wire or the metal raw material "A" and retain sufficiently great adhesive force upon passage out from the covering station 11 and into the draw plate 12.

With the aid of, among other things, the electrostatic properties, the covering can be controlled so that correct level of the high voltage is selected in relation to particle size, wire speed as well as desired layer thickness of the covering.

This type of pulverized lubricant is most often inclined to be charged electrostatically during all handling, such as during dosage, milling, screening, vacuum transportation etc., which make them difficult to handle in a controlled and repeatable way.

Thereby, within the plant 100, the use is required of ionized antistatic equipments to overcome these problems and the utilized lubrication means have properties that make it feasible to actively be possible to be discharged.

In figure 2, the reference designation (*) has been introduced for those stations where an active discharge can be regarded as being requisite to prevent a concentration of charged particles, such as positively or negatively charged particles.

When the precharged particles within the precharging chamber 9 reach the focusing electrode 10, the particles have already a predetermined loading amount, which re-

suits in a surface potential within the covering station 11 , which is determined by the shape, size and specific capacitance of the particles.

Based on this data, the precharging chamber 9 can allocate the particles a prechar- ging (negative or positive potential) chosen in advance.

The electrostatic effects can be additionally enhanced, by the fact that the focusing electrode 10 (or several electrodes) is to be surrounding the wire or the metal work piece "A" by great accuracy and this will be able to control the quantity of particles that should cover the wire, as well as via the control electronics 14 of the system as well as at a constant-holding of the thickness of the covering, this can also be realised via changes of the wire speed "F".

When these particles pass over to the covering station 11 , an electrostatic field occurs within this station 11 of the same polarity as in the precharging chamber 9 by means of the focusing electrode 10.

The total electrostatic field within the covering station 11 is thereby adjustable via the precharging chamber 9 as well as via the focusing electrode 10.

The figure 4 intends to illustrate that a chosen focusing electrode 10 is orientated as a helix shape on the inside of the station 11 , but within the scope of the invention it is also possible to structure the focusing electrode 10 with a smaller diameter to closer surround the metal work piece "A".

The focusing electrode 10 could also be associated with other constructive shapes with an intention to get an evenly distributed or a varying electrostatic field. Nothing prevents to associate the focusing electrode 10 to a helix shape having a varying diameter, such as a diameter increasing or decreasing counted in the feeding direction "F".

Furthermore, it is important that variations of temperature and relative air humidity outside the system and the plant are not allowed to influence the function.

This is guaranteed by letting the system, with the appurtenant stations, be entirely closed, except upon entry and exit passage of the metal work piece "A" or the wire as well as upon a replenishment of lubricant "c" at the container 1.

The system and the plant 100 is primarily meant to operate with normal air but functions also excellently with another gas or gas mixture. A suitable gas may on that occasion be nitrogen gas, in case that a covering "C" needs to be applied in an inert gas atmosphere.

The covering method within the plant 100 is in addition useful for a traditional cold wire drawing, especially suitable for a cold drawing of wire that should be provided with a lubricant film and thereby be possible to be delivered with a covering lubricant film to a customer.

By an absence of each drawing means carrier, the lubricant film will be homogeneous and have a reduction toward a minimum of impurities.

The plant 100 may be installed with one or more drawing units co-ordinated to one and the same wire drawing machine, wherein said drawing units can communicate with each other via the control unit 14, so that especially important properties can be controlled via a subsequent unit, as function of production parameters from a preceding unit and vice versa.

Upon a typical test, using the method according to the invention within a plant, a conventional drawing means was used with a great variation of particle sizes between 1 μm and 500μm, upon a drawing of a second-rate wire of stainless steel.

The high voltage for the respective precharging 9 of the lubricant, as well as the focusing electrode 10 in the station 11 may each one consist of an approx. 15 kV direct-current voltage.

Tests and experiments have been carried out, to a limited extent, to thereby be able to demonstrate the technical effect associated with the invention.

In one of these tests, it was manifested that it is within the scope of the invention to afford four consecutive dimension-reductions, after an application of a lubricant or drawing means only before the first dimension-reduction.

It was shown that the precharged lubricant, in the form of powder, came to form a homogeneous thin film without impurities, since no drawing means carrier was used.

The solidified drawing means film from the first dimension-reduction was sufficient to give requisite lubrication in the second dimension-reduction, etc.

In spite of the wire or metal work piece that was used was of second-rate quality, the quality of the produced metal material became higher than upon a corresponding drawing in the conventional manner, with a marked good roundness and mainly entirely without visible grindings on the accordingly manufactured wire surface.

The equipment and/or the plant 100 may advantageously be modularly built up by a number of different parts and units, which are integrated with each other and adapted to be possible to be associated new wire drawing machines as well as to be possible to retrofit existing production machines.

The precharge unit 9 as well as the charging chamber 11 having the focusing electrode 10 have been allocated an impact resistant outer cover of an electrically conducting material and are ground connected to meet requirements of personal safety, as well as to prevent that they attract each type of airborne impurities.

The equipment and/or the plant 100 consist of the following modules;

The lubricant "c" is primarily a powdered material according to the description of the plant 100 above, and is filled in a storage container 1 , which also is used for a collection of surplus medium brought back from the rest of the plant 11 , 12.

From the container 1 , the material is brought to a vibrating screen 3, which fractionates the medium to desired particle sizes, after which the desired fraction is led fur-

ther to a buffer container 4 for particle-shaped lubricant. The fraction of particles that consists of too great particles, is transported to a mill 5 for a milling process, after which the medium is brought to the storage container 8.

The transportation of lubricant from the mill as well as the transportation of surplus material "c" from the covering chamber 11 (the drawing box 12) takes place by vacuum transportation, the material being separated from the air flow in a cyclone.

In the bottom of the buffer container 8, there is a vibrating feeder 8', which is controlled by the control system 14 of the plant, so that the amount of lubricant automatically can be varied, according to the current recipe and rate of production, by varying both frequency and amplitude. The vibrating feeder 8' is equipped with ionization equipment to ensure that the lubricant is fed forward without being charged electrostatically, an even material flow being provided as well as formation of greater aggregates of particles being prevented.

The material is dosed continuously from the vibrating feeder 8' into an initial charge unit 9 placed ahead, which in the opposite end thereof is connected to the charging chamber 11. The lubricant is drawn into the connection of the suction conveyor to the covering chamber.

The lubricant is charged upon passage past a first charging electrode 9b, which is fed 13b from a separately controllable high voltage source.

After that, the lubricant passes past one or more focusing electrodes 10, which with or without the help of additional blow air are used to influence the shape and expansion of the particle flow upon the passage thereof into the charging chamber or the covering station 11.

Focusing electrodes 10 and blow air are separately and variably adjustable to enable a production according to different recipes and by varying wire speeds.

In the covering chamber or the covering station 11 , the lubricant is transferred to the wire "A", connected with earth potential on one hand, by the fact that the lubricant

particles, because of the difference of potential, move toward the wire "A", but above all the particles are controlled in an accurately controlled manner within the electrostatic field, which initially has been created by the charging electrode 9b and by the subsequent focusing electrode 10, which here constitutes and covers the greater part of the inside of the charging chamber 11.

The charging chamber 11 consists of an entry side, where the wire "A" passes in through an end portion, which has been provided with a flexible material 11a, which enables the wire "A" to pass but limits an air passage or airflow into the chamber 11.

On the end portion of the exit side, before the wire reaches the draw plate 12, there is a bellows seal 11b, which can join tightly against the metal work piece "A" having the lubricant layer "C" and/or a draw plate device 12.

Between the end portions, in the direction of motion "F" of the wire, a connecting wall (not shown) is suggested, which preferably has a cylindrical or slightly conical shape.

The inside of such a wall consists of one or more charging or focusing electrodes, which are fed by high voltage from an outer high voltage generator 13, which is controlled by the control system 14 of the plant, so that the field variably can be adapted according to the current recipe, as well as in relation to the speed of the wire.

The longitudinal outer wall of the covering chamber 11 is well isolated from the focusing electrode 10 applied on the inner wall.

Lubricant is supplied, after passage via the precharge unit 9, to the covering chamber 11 through one or more entry holes, perpendicularly to the direction of motion of the wire, but not necessarily perpendicularly to the wire.

Possibly surplus material "c" leaves the chamber 11 through a vacuum connection near the bellows of the covering chamber 11 , and is brought via the suction conveyor and a cyclone back to the storage container 1. The cyclone as well as the

storage container is provided with ionized antistatic equipment, to enable a correct feed of the lubricant as well as to prevent each aggregate formation.

With a renewed reference to figure 3, there is schematically illustrated a control unit 14, and where said control unit 14 is fed with the information occurring, among other things, on cables 14a-14f.

Each one of these cables co-operates with signal-receiving circuits and memories, which are arranged to be connected to a calculation unit 14', which calculation unit 14' is, via algorithms and software, adapted to, depending on entered criteria, controlling, via a cable 13', a high voltagr unit for said precharging chamber 9 and/or controlling, via a cable 13", a high voltage unit for said focusing electrode 10.

The invention is of course not limited to the embodiment given above as example, but may be subjected to modifications within the scope of the general idea according to the invention, illustrated in the subsequent claims.

Particularly, it should be taken into consideration that each unit and/or category shown can be combined with any other unit and/or category shown within the scope in order to be able to attain the desired technical function.