GB2058629A

GB2058629A - Lubrication in Metal-working Processes

Info

Publication number: GB2058629A
Application number: GB8026704A
Authority: GB
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 1979-08-15
Filing date: 1980-08-15
Publication date: 1981-04-15
Also published as: CA1162596A; FR2462945A1; FR2462945B1; DE3030876A1; GB2058629B; JPS5630023A

Abstract

During a metal-working operation, e.g. rolling or drawing, a lubricant with electrically charged particles is attracted to the working tool(s) or workpiece by an electric field. The field is generated by creating a D.C. circuit between the tool(s) and workpiece or between the tool(s) and lubricant. In one form, positively charged rollers 15 and 16 are lubricated by an emulsion contained in troughs 19 and 20 containing negative poles 21 and 22. In use, the electric field resulting in the lubricant emulsion causes anionically charged lubricant particles to adhere on the rollers 15 and 16 with the result that increased lubrication is achieved during the rolling operation. The lubricant may be an anion type emulsion (emulsified by triethanolamine oleate with a 10% concentration and average particle size of 5 or 0.9 microns). <IMAGE>

Description

SPECIFICATION Method and Apparatus for Controlling Lubrication in Lubricated Plastic-working of Metallic Material This invention relates to a method and apparatus for plastic-working a metallic material and is particularly concerned with increasing the amount of a lubricant material intervening between a working tool and a workpiece to ensure smooth plastic-working operations.

In plastic-working (e.g. rolling or drawing) of a metallic material, it is conventional practice to employ as a lubricant either a non-emulsion type lubricant oil which is generally called "neat oil" or an emulsion type lubricant oil which is obtained by adding water to neat oil to achieve a cooling effect.

The degree of lubricating effect depends on the quantity of lubricant oil which intervenes between the workpiece and a tool (such as a working roll or drawing die). The most important factor which dictates the amount of lubricant oil which does this is the adherence of the lubricant oil to the working tool and the work.

Known emulsion type lubricant oils are in most cases oil-in-water emulsions which are inferior to neat oil in adherence to the workpiece or tool. This is especially so in the case of stable lubricant emulsions having a small oil concentration only.

Various attempts have been made to improve the adherence of the lubricant oil, for example, by chemically modifying the lubricant or by varying the particle size of the emulsion, but none of them has been satisfactory.

Improved adherence can in particular be obtained by using an emulsion of a relative large particle size but such emulsions are unfortunately unstable and incapable of effecting uniform and stable lubrication.

An additional problem associated in particular with lubricant emulsions is that it has been difficult to control the adherence of lubricant oil to an extent optimum for all the various widely differing working conditions and lubricant types.

According to one aspect of the invention, there is provided a method of plastic working of a metallic workpiece by a working tool which method comprises applying said tool to said workpiece to effect said working whilst said workpiece and/or said tool forms a pole of an electric field produced in a body of lubricant oleaginous emulsion which is in contact with the contacting surfaces of said tool and said workpiece and which, whilst influenced by said field, contains oleaginous particles so charged electrically as to migrate to and adhere on said pole.

The emulsion may be an anion type emulsion containing negatively charged particles of lubricating material. The emulsion when of this type may in particular be an aqueous emulsion of triethanolamine oleate. Alternatively, the emulsion may be of cation type, comprised of positively charged lubricant particles.

The emulsion may and commonly will contain charged lubricant particles when remote from electric field potentials. However, the emulsion may conveniently be one in which the emulsified particles are neutral until application thereto of an electrical potential of, for example, 75 volts for several minutes.

In a particular embodiment of the invention, the method produces a drawn product and comprises drawing a body of metallic material through a die with the die and the die-contacting surfaces of said body in contact with a lubricant electrically in contact with a first pole of a DC power source and comprising an electrically conductive oleaginous emulsion containing electrically charged lubricant particles, the body of metallic material being electrically in connection with a second opposed pole of said DC power source so that an electrical field is generated in said lubricant to cause passage of said lubricant particles to said body of metallic material during the working. The drawn product may be a wire or a tube.

In a further embodiment a rolled product is produced by a method comprising rolling a body of metallic material with one or more rollers electrically connected to a DC power source to form a pole thereof and electrically in contact at the nip of the roller(s) with an electrically conductive lubricant which comprises an oleaginous emulsion, containing electrically charged lubricating particles, a member being provided in electrical contact with said lubricant and with the DC power source to form a further pole thereof thereby producing in said lubricant an electrical field through which lubricant particles migrate so as to concentrate at said roller nip to provide increased lubrication between the roller(s) and the body of metallic material.

In a second aspect, the invention provides an apparatus for use in plastic working of a metallic workpiece which apparatus comprises a working tool for application to said metallic workpiece to effect working thereof, means for applying a lubricant oleaginous emulsion to at least one of said workpiece and tool so that in use of the apparatus the contacting surfaces of said tool and workpiece bear an intervening film of said emulsion, and means for coupling to said apparatus a source of electricity to produce an electric field in said emulsion with one or both of said contacting surfaces forming a pole of said attractive to electrically charged particles of lubricant material in said emulsion.

Conveniently, the means for applying the emulsion comprises an application nozzle for directing a supply of said emulsion onto said working tool and/or said workpiece or comprises means defining a container for containing a body of said emulsion in contact with said working tool or said workpiece.

For example, a member may be provided which in use of the apparatus functions as a second pole of said electric field and which optionally forms at least part of the means defining said emulsion container.

The apparatus may in particular comprise a die through which to draw a body of metallic material to produce a wire, said die functioning in use of the apparatus as a first pole of said electric field, and means in use functioning as a second pole of said electric field and defining a container through which, in use, said body passes in electrical contact with lubricant oleaginous emulsion then contained in said container.

In an alternative drawing apparatus, the apparatus comprises means defining a lubricant reservoir and functioning in use of the apparatus as a first pole of said electric field, a die comprising a member including an aperture and a plug having a portion received with radial clearance in said aperture to define a die throat and a portion extending into said reservoir to form a second pole of said field at the same polarity as said first pole, a third opposed pole being provided for contact with a hollow cylindrical body of metallic feed material to be worked received over said plug in use of the apparatus to define a first body of lubricant oleaginous emulsion between said feed material and plug and a second body of said emulsion between said feed material and said first pole with separate electrical fields being produced in each such body to attract charged lubricant particles to the inner and outer surfaces of the body of feed material.

Alternatively, the apparatus may be a rolling apparatus comprising a roll, which in use of the apparatus froms a first pole of said electric field, a cooperating tool surface defining a nip with said roll, a reservoir which in use contains lubricant oleaginous emulsion in electrical contact with said roll, and a pole plate disposed in said reservoir for electrical contact with said emulsion in use of the apparatus.

In a preferred form, rolling apparatus may comprise a pair of rollers disposed in relation to each other so as to define a nip therebetween, a trough for containing a body of said lubricant in contact with one or said rollers so that lubricant is conveyed to the nip in use by rotation of said roller, a plate disposed in said reservoir so as in use of the apparatus to make contact with said lubricant to complete a DC electrical circuit with said lubricant, said roller and a D.C. power source connected electrically to said plate and said roller.

In rolling apparatus according to the invention a conductive slide member may be provided for contact with a roll and connected to a terminal of a DC power source.

Particularly preferred rolling apparatus comprise rolling means including a roller serving in use of the apparatus as a first pole of an electric field and a nip through which to pass said workpiece, a lubricant container for containing in contact with the roller a lubricant oleaginous emulsion under the influence of said field and containing electrically charged lubricant particles attracted to said first pole, one or a plurality of second pole pieces disposed in said container, for lubricant contact, in spaced apart relationship preferably along an axis spaced from the roller and extending along the length of the roller axis, one or more sensors for sensing dimensional characteristics of the rolled product and for transmitting signal(s) representative of such characteristics and means responsive to such signal(s) for changing the intensity of said electric field in order so as to change the extent to which the charged lubricant particles are caused to pass to the first pole as to effect a desired change in dimensional characteristics.

Especially preferred rolling apparatus comprise rolling means including a roller which functions as a first pole of the hereafter specified electric field in use of the apparatus and a nip for receipt of said workpiece for rolling, a reservoir which in use contains a lubricant oleaginous emulsion comprising electrically charged lubricant particles influenced by said electric field so as to pass to and adhere on said roller pole, a plurality of second pole pieces spaced apart in said reservoir along an axis spaced from the roller and extending lengthwise with respect to the roller axis, a plurality of sensors respectively for sensing dimensional error in the rolled product in respect of particular respective portions of the transverse dimension of the rolled product, means for transmission of signals representative of dimensional error and means responsive to such signals to change the potential of one or more of said second pole pieces so as effect such variation of the adhered lubricant particles as to remedy the dimensional error in respect of subsequently rolled product.

The invention will now be described with reference to the accompanying drawings which illustrate by way of example the apparatus and method of the invention. In the drawings Figures 1, 3, 4, 5, 7 and 8 are graphs showing experimental data; Figure 2 is a schematic diagram of lubricated rolling apparatus according to the invention; Figures 6 and 9 are schematic diagrams showing different forms of lubricated drawing apparatus according to the invention; Figure 10 is schematic diagram of lubricated rolling apparatus according to the invention, operated with divided control of lubrication; Figure 11 is a graphic illustration of the pattern of the divided lubrication control obtained using apparatus as shown in Figure 10: and Figures 12 to 14 are graphic illustrations similar to Figure 11 but showing patterns of more finely divided lubrication control attainable by the method of the invention.

A preliminary experiment was conducted in,which a steel plate and a copper plate were immersed in a lubricant oil bath holding an anion type emulsion lubricant (using triethanolamine oleate and having an emulsion concentration of 10 wt. % and an average particle size of 5 microns) and a diversity of voltages were applied for various immersion times across the steel and copper plates (serving as positive and negative pole, respectively). The resulting amounts of adhered lubricant oil are shown in Figure 1. As is clear therefrom, the adherence of lubricant oil to the steel plate increases both with the voltage and the time of immersion. For example, at an immersion time of 10 seconds, the adherence of the lubricant oil at 50V is about 10 times greater than that at zero voltage.This increase in adherence is considered to be attributable to the attraction of negatively charged particles in the emulsion to the positive pole formed by the steel plate.

The adherence of a cation type emulsion lubricant can also be increased by applying a voltage across a cathodic steel plate and an anodic copper plate.

In a similar experiment using a nonion type emulsion lubricant oil and a non-emulsion type lubricant oil, it has been confirmed that the adherence does not increase to any appreciable degree at low voltages but remarkably increases when a relatively high voltage is applied for a substantial duration. For example, the adherence amounted to about 8 g/m2 when 1 OOV was applied for 8 minutes; this is four times as great as the adherence at zero voltage (about 2 g/m2). It is believed from the above results that the application of voltage causes electrolytic dissociation of substances such as R--COOH usually contained in lubricant oils to form ionized groups.The dissociation is believed to be represented by the following:- 2R-COOH+2e--t2R-C00-+H, The method of the invention was experimentally applied to a lubricated rolling operation using an apparatus as shown in Figure 2. The apparatus shown in the figure comprises working rolls 1 5 and 16, lubricant oil feed nozzles 1 7 and 18, and lubricant oil pools 1 9 and 20. Pole plates 21 and 22 are immersed in the lubricant oil pools 19 and 20 in opposed face-to-face relationship with the working rolls 15 and 16 respectively. The roll 15 and pole plate 21 are connected to a DC power source 23, while the roll 16 and pole plate 22 are connected to another DC power source 24. A steel strip 14 is fed to the nip of rolls 1 5 and 16.

The lubricant oil used in the rolling operation was an anion type emulsion (emulsified by triethanolamine oleate and having a concentration of 10% and an average particle size of 0.9 microns).

In order to determine the adherence of the lubricant oil to the working rolls at various different voltages, the amounts of lubricant oil adhered at various times over a short period of contact between lubricant oil and the rolls were measured.

It has been confirmed that the amount of adherence tends to increase with increased applied voltage even over very short contacting times. The results are shown in Figure 3.

Figure 4 shows the amounts of adherence of the same lubricant oil measured after a contact time of 0.5 seconds after application of currents of various densities. It is clear from Figure 4 that the adherence of the lubricant oil increases with the current density.

The adherence of the lubricant oil has a great influence on the load for the rolling operation. In this connection, the effects of applied voltages on the rolling load (rolling lubrication) were tested by a rolling operation according to Figure 2 and under the following conditions: Rolling material: Aluminium having dimensions of 1.5 mmtX50 mmw (coil) Rolling temperature: 3600C (at roll entrance) Rolling reduction: 60% Rolling speed: 25.7 m/min.

Roll diameter: 155 mm Lubricant oil: 3% emulsion of aluminium hot rolling oil Size of pole plate: 20 mmhx65 mmW Figure 5 shows the results of the rolling test. The rolling load is as high as 11 tons in an ordinary lubricated rolling operation at zero voltage but is reduced to about 9 tons at 20 V and to less than 6 tons at 50 V. In Figure 5, the last portion of zero voltage curve plots data resulting from application of 50 volts initiated at the arrowed point. The voltage applied half-way of the rolling operation has a certain degree of load reducing effect which, however, is lower than that obtained by applying the same voltage from the start (an additional voltage application time of slightly less than 2 minutes).

As shown in Figure 2, the lubricant oil pools are provided to one side of the working rolls 15 and 1 6 and electric current is conducted between the working roll and immersed pole plates 21 and 22. It is also possible, however, to use the nozzles 1 7 and 18 as negative poles, continuously spouting the lubricant oil toward the surfaces of the working rolls. In such a case, it is preferred to employ nozzles which have an increased width along the length of the working rolls. It is also possible to use the rolling strip as a positive pole, locating the electrode plates (negative poles) vis-a-vis with the upper and lower sides of the entering strip 14 and providing the lubricant oil in the spaces between the rolling strip and the respective negative electrode plates.

The method of the present invention can be applied to lubricated drawing by using an apparatus as shown in Figure 6, in which indicated at 1 is a wire rod being drawn, at 2 a die, at 3 a die holder, at 4 a cylindrical member internally defining a lubricant oil chamber 4a, at 5 an insulating joint member joining the die holder 3 and the cylindrical member 4 together, at 6 an insulating wire guide member, at 7a a lubricant oil inlet, at 7b a lubricant oil outlet, and at 8 a compressed air blow-in hole through which to introduce compressed air to prevent leakage of the lubricant oil through the gap between the wire guide member 6 and the wire. The die holder 3 and cylindrical member 4 are connected to a DC power source 9.Electric current is conducted between the die holder 3 and the cylindrical member 4, forming the positive and negative poles, by the drawn wire 1 and the lubricant oil circulated in chamber 4a via the inner peripheral surface of the cylindrical member 4.

An aluminium alloy wire rod of 3.2 mmAx 120 mma was drawn by an apparatus as shown in Figure 6, using an anion type emulsion lubricant oil (concentration: 10 wt.%) and applying a varying voltage of O to 50 volts. The adherence of the lubricant oil to the wire over contacting times of 5 and 10 seconds was measured. The results are shown in Figure 7.

As is clear from Figure 7, the adhered lubricant oil has an average film thickness of less than 5 ym at zero voltage but it increases sharply with applied voltage. The film thickness is 54 y at 50 volts (contact time 5 seconds) and is 70 ,um at 50 volts (contact time 10 seconds). Thus, the adherence of the lubricant oil to the wire 1 is drastically increased by conducting electric current between the wire and the inner peripheral wall of the cylindrical member 4 in a manner to produce a potential difference between the wire and the lubricant oil. It will also be seen from Figure 7 that the adherence for a particular applied voltage increased with contact between the wire and the lubricant oil.Therefore, the adherence of the lubricant oil can be controlled to a value optimum for particular drawing conditions by adjusting the voltage of the DC power source 9 (Figure 6), thereby ensuring a very smooth drawing operation. The adherence of the lubricant oil is also closely related with the load required for the drawing operation and the rate of wire seizure.The effects on reducing the drawing load (increasing lubrication in drawing) and the rate of wire seizure of the application of voltage were tested under the following conditions:- Lubricated drawing machine: Length of lubricant chamber 4a: 100 mm Inner diameter of lubricant chamber 4a:13.2 mm Diameter of die: 2.9 mm Lubricant oil: Anion type 10 wt.% or 3 wt.% emulsion of neat oil Wire rod: Aluminium alloy 3.2 mm in diameter Drawing reduction: 18% Drawing speed: 1-10 m/min.

Voltage: 0--40 V Rod draw: Drawbench (1) Effect of Reducing Drawing Load The application of voltage manifested a distinctive effect of reducing the drawing load by 625% as shown in Figure 8, the effect being greater with an anion type emulsion having an oil concentration of 10 wt.%.

(2) Effect of Lessening Rod Seizure Rod seizure occurred in non-conducting drawing operations both at a drawing speed of 6 m/min with a 10% emulsion and a drawing speed of 3m/min with a 3% emulsion. Upon applying a voltage of 40 volts, drawing operations under the same conditions proceeded smoothly without rod seizures.

As is clear from these test results, the lubricating method of the present invention also contributes to reduce the drawing load while precluding rod seizure.

The method of the invention can also be applied to pipe drawing and apparatus for so doing is shown in Figure 9. In Figure 9, at 1' is a pipe being drawn, at 2 a die, at 4 a cylindrical member, at 10 a conductive press roller for applying current to the pipe 1', and at 11 a plug which controls the inside diameter of the drawn pipe. The plug 11 is supported by a rod 1 2 fixed concentrically within the die 2.

The cylinder 4 is provided with a lubricant oil inlet 7a for supplying a lubricant oil around the outer periphery of the pipe 1 ' while the support rod 12 is internally provided with a lubricant oil supply passage 13 for supplying the lubricant oil around the inner periphery of the pipe 1'. The cylindrical member 4 and press roller 10 are connected to a DC power source 9 for conducting current during the drawing operation between a negative pole formed on the inner periphery of the cylinder 4 and the outer periphery of the support rod 12 and a positive pole formed on the inner and outer peripheries of the pipe 1'. In this embodiment, the lubricant oil of anion type emulsion is effectively adhered on the inner and outer peripheries of the pipe 1' forming a positive pole to ensure smooth drawing free of pipe seizures.

Referring now to Figure 10, there is shown a rolling mill for controlling the shape of a rolling strip utilizing the conductive lubrication of the present invention. In this embodiment, working rolls 37a and 37b are directly contacted with a lubricant oil 32 in troughs 38a and 38b which are located along the lengths of the respective rolls 37a and 37b, so that the lubricant oil 32 is fed in the rolling direction as the working rolls 37a and 37b are rotated. Located within the lubricant oil troughs 38a and 38b are a number of pole plates 39a-1 to 39a-3 and 39b-1 to 39b-3 which are positioned in face-to-face relation with the working rolls. The working rolls 37a and 37b and the above-mentioned pole plates are opposed poles of an electric circuit for producing an electric field in the lubricant oil 32 between the opposed poles.In this particular embodiment, the pole plates 39a-1, 39b-1, 39a-3 and 39b-3 which face the opposite end portions of the working rolls are connected to a common power source 41 b through a voltage regulator 40b, separately from the intermediate pole plates 39a-2 and 39b-2 which are connected to another power source 41 a through a voltage regulator 40a, to control the lubrication independently in the middle and opposite end portions of the working rolls 37a and 38b. A number of detectors 42-1 to 42-3 are located across the width of the rolled strip A to detect its shape and dimensions, the opposite end detectors 42-1 and 42-3 being connected to the voltage regulator 40b while the middle detector 42-2 being connected to the voltage regulator 40a.

Upon commencing the rolling operation, a voltage is applied between the respective opposing poles to pull the lubricant oil electrically toward the working rolls thereby to adjust the adherence of the lubricant oil on the working rolls. Even if the adherence is uniformly controlled along the lengths of the working rolls, there sometimes occur variations in the degree of lubrication which cause elongations in the middle portion of the rolling strip or undulations along the opposite longitudinal sides of the strip A.

These conditions are immediately detected by the detectors 42-1 to 42-3 and the voltage regulators 40a and 40b are operated to adjust counter-actively the voltages to be applied to the respective pole plates. More particularly, in a case where the lubrication in the opposite end portions of the rolling strip is deficient, the voltage to the pole plates 39a-1, 39b-1,39a-3 and 39b-3 is increase to increase the adherence of the lubricant oil to the opposite end portions of the working rolls. On the other hand, when the lubrication in the middle portion of the rolling strip is deficient, the voltage to the pole plates 39a-2 and 39b-2 is boosted to Increase the adherence of the lubricant oil to the middle portions of the working rolls.By so doing, uniform lubrication is maintained along the length of the working rolls to allow production of rolled plates of high quality which are free of elongations in the middle portion or undulations along the longitudinal edges thereof.

The separate control of the adherence of the lubricant oil in the middle and opposite end portions of the working roll can be expressed by a control pattern of Fig. 11. In a case where more than 5 sets of a pole plate and a detector, each connected to a power source and a voltage regulator of a separate control circuit, are juxtaposed in the transverse direction, it becomes possible to control the adherence of the lubricant oil in a more finely divided pattern as shown in Figs. 12 to 14. The pole plates are located within the lubricant oil troughs 38a and 38b in the embodiment of Fig. 10. However, they may be omitted by using the upright wall portions of the troughs 38a and 38b which are disposed via-á-vis with the respective working rolls.

Further, the terminal end of each electric control circuit which is directly connected to the working roll in the embodiment of Fig. 10 may be connected to a conductive slide member which is positioned in contact with a working roll slidably relative to the rotation of the working roll, thereby to prevent current leakage to a roll bearing or chock. Such conductive slide member is preferred to be formed of graphite or a material which is highly conductive and resistant to abrasive wear.

It will be appreciated from the foregoing description that the lubricating method of the present invention has a high practical value particularly in lubricated drawing or lubricated rolling operations.

To summarize the effects accruing from the method of the present invention: (a) The adherence is increased irrespective of the kind of the lubricant oil (anion-, cation- or nonion type), and with a lubricant oil of anion type emulsion the adherence can be drastically increased by application of a relatively small voltage.

(b) The adherence of lubricant oil to a working tool (e.g., a die ar roll) can be controlled by adjusting the applying voltage or current, providing optimum lubrication with use of a lubricant oil of a given concentration depending upon the nature of the work and conditions of a drawing or rolling operation.

(c) Even if the lubricant oil undergoes a change during plastic-working operation (e.g., a change in particle size or concentration of the emulsion), it is possible to control the adherence counteractively, constantly permitting the plastic-working operation to proceed stably.

(d) Seizure of a work Is suppressed to a minimum, coupled with other advantageous effects such as prolongation of the service life of dies and working rolls, lessened drawing or rolling loads, higher quality of drawn or rolled products.

While particular preferred embodiments have been described, it is to be understood that the invention is not limited by the particular details shown and various modifications and alterations can be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of plastic working of a metallic workpiece by a working tool which method comprises applying said tool to said workpiece to effect said working whilst said workpiece and/or said tool forms a pole of an electric field produced in a body of lubricant oleaginous emulsion which is in contact with the contacting surfaces of said tool and said workpiece and which, whilst influenced by said field, contains oleaginous particles so charged electrically as to migrate to and adhere on said pole.

2. A method as claimed in Claim 1 wherein said workpiece and/or said tool form part of a DC electrical circuit completed by said electrical field and a DC power source.

3. A method as claimed in Claim 1 or Claim 2 wherein said workpiece is drawn through a die.

4. A method as claimed in Claim 3 wherein said die defines an aperture through which said workpiece is drawn as a continuous wire of solid cross-section.

5. A method as claimed in Claim 3 wherein said die defines an annular aperture through which the workpiece is drawn as continuous pipe.

6. A method as claimed in Claim 1 or Claim 2 wherein said tool is a pair of rolls.

7. A method as claimed in any preceding claim wherein the lubricant is an oleaginous emulsion whose internal phase oleaginous particles are anionic or cationic in the absence of an externally applied electrical field.

8. A method as claimed in Claim 7 wherein the emulsion comprises is triethanolamine oleate.

9. A method as claimed in Claim 7 or Claim 8 wherein the applied electrical field has a potential difference of at least 10 volts.

10. A method as claimed in Claim 9 wherein the potential difference of the field is from 10 to 50 volts.

11. A method as claimed in Claim 9 or Claim 10 wherein the electrical field is applied for at least 3 seconds prior to the working.

12. A method as claimed in any one of Claims 9 to 11 wherein the electrical field has a current density of at least 0.75 mA/cm2.

13. A method claimed in Claim 12 wherein the current density of the field is approximately 2 mA/cm2 or more than 2 mA/cm2.

14. A method as claimed in any one of Claims 1 to 6 wherein the lubricant is an oleaginous emulsion whose internal phase oleaginous material is essentially non-ionic and dissociatable electrolytically under applied field conditions to form ionic particles.

15. A method as claimed in Claim 14 wherein the electrical field has a potential difference of at least 50 volts and is applied for at least 5 minutes prior to the working.

1 6. A method as claimed in Claim 1 5 wherein the applied field has a potential difference of at least 100 volts applied for at least 8 minutes prior to the working.

1 7. A method for electrically increasing the degree of lubrication in lubricated plastic-working of a metallic material, the method comprising incorporating a working tool and/or a work into a DC circuit to form a pole in face-to-face relation with an opposite pole; and conducting current between said poles to produce an electric field in an emulsion type lubricant oil prevailing therebetween, said lubricant oil thereby being caused to be electrically pulled toward said working tool and/or said work to increase the adherence of said lubricant oil to said working tool and/or said work.

1 8. A method of producing a drawn product of metallic material which method comprises drawing a body of metallic material through a die with the die and the die-contacting surfaces of said body in contact with a lubricant electrically in contact with a first pole of a DC power source and comprising an electrically conductive oleaginous emulsion containing electrically charged lubricant particles, the body of metallic material being electrically in connection with a second opposed pole of said DC power source so that an electrical field is generated in said lubricant to cause passage of said lubricant particles to said body of metallic material during the working.

19. A method of producing a rolled metallic product which method comprises rolling a body of metallic material with one or more rollers electrically connected to a DC power source to form a pole thereof and electrically in contact with an electrically conductive lubricant which comprises an oleaginous emulsion containing electrically charged lubricating particles, a member being provided in electrical contact with said lubricant and with the DC power source to form a further pole thereof thereby producing in said lubricant an electrical field through which lubricant particles migrate to the roller(s) to provide a concentration thereof at the roller nip to provide increased lubrication between the roller(s) and the body of metallic material.

20. A method as claimed in Claim 1 and substantially as hereinbefore described with reference to Figure 2, Figure 6, Figure 9 or Figure 10 of the accompanying drawings

21. A plastic worked product whenever made by a method as claimed in any preceding claim.

22. An apparatus for use in plastic working of a metallic workpiece which apparatus comprises a working tool for application to said metallic workpiece to effect working thereof, means for applying a lubricant oleaginous emulsion to at least one of said workpiece and tool so that in use of the apparatus the contacting surfaces of said tool and workpiece bear an intervening film of said emulsion, and means for coupling to said apparatus a source of electricity to produce an electric field in said emulsion with one or both of said tool and workpiece forming a pole of said field attractive to electrically charged particles of lubricant material said emulsion so that the amount of lubricant in the film on the contacting surfaces is increased.

23. An apparatus as claimed in Claim 22 wherein the working tool comprises a die or one or more rollers.

24. An apparatus as claimed in Claim 22 or 23 wherein the means for applying the emulsion comprises an application nozzle for directing a supply of said emulsion onto said working tool and/or said workpiece or comprises means defining a container for containing a body of said emulsion in contact with said working tool or said workpiece.

25. An apparatus as claimed in Claim 24 wherein a member is provided which in use of the apparatus functions as a second pole of said electric field and which optionally forms at least part of the means defining said emulsion container.

26. An apparatus as claimed in Claim 25 and comprising a die through which to draw a body of metallic material to produce a wire, said die functioning in use of the apparatus as a first pole of said electric field, and means in use functioning as a second pole of said electric field and defining a container through which, in use, said body passes in electrical contact with lubricant oleanginous emulsion then contained in said container.

27. An apparatus as claimed in Claim 25 and comprising a roll, which in use of the apparatus forms a first pole of said electric field, a cooperating tool surface defining a nip with said roll, a reservoir which in use contains lubricant oleaginous emulsion in electrical contact wilth said roll, and a pole plate disposed in said reservoir for electrical contact with said emulsion in use of the apparatus.

28. An apparatus as claimed in Claim 27 and comprising a pair of rollers disposed in relation to each other so as to define a nip therebetween, a trough for containing a body of said lubricant in contact with one of said rollers so that lubricant is conveyed to the nip in use by rotation of said roller, a plate disposed in said trough so as in use of the apparatus to make contact with said lubricant to complete a DC electrical circuit with said lubricant, said roller and a DC power source connected electrically to said plate and said roller.

29. An apparatus as claimed in Claim 25 and comprising means defining a lubricant reservoir and functioning in use of the apparatus as a first pole of said electric field; and a die comprising a member including an aperture and a plug having a portion received with radial clearance in said aperture to define a die throat and a portion extending into said reservoir to form a second pole of said field of the same polarity as said first pole; a third opposed pole being provided for contact with a hollow cylindrical body of metallic feed material to be worked received over said plug in use of the apparatus to define a first body of lubricant oleaginous emulsion between said feed material and plug and a second body of said emulsion between said feed material and said first pole with separate electrical fields being produced in each such body to attract charged lubricant particles to the inner and outer surfaces of the body of feed material.

30. An apparatus for lubricated plastic-working of a metallic material, having means for electrically increasing the degree of lubrication, which apparatus comprises a lubricant oil trough holding an emulsion type lubricant oil in contact with a working tool and/or a work; and a DC circuit incorporating said working tool and/or said work to form a pole (A), an opposite pole (B) being disposed in contact with said lubricant oil and in face-to-face relation with said pole (A) to produce an electric field in said lubricant oil upon conducting a current between said poles (A) and (B) whereby said lubricant oil is electrically pulled toward said working tool and/or said work to increase the adherence of said lubricant oil to said working tool and/or said work.

31. An apparatus for rolling a metallic workpiece and comprising rolling means including a roller serving in use of the apparatus as a first pole of an electric field and a nip through which to pass said workpiece, a lubricant container for containing in contact with the roller a lubricant oleaginous emulsion under the influence of said field and containing electrically charged lubricant particles attracted to said first pole, one or a plurality of second pole pieces disposed in said container for lubricant contact, in spaced apart relationship along an axis spaced from the roller and extending along the length of the roller axis, one or more sensors for sensing dimensional characteristics of the rolled product and for transmitting signal(s) representative of such characteristics and means responsive to such signal(s) for changing the intensity of said electric field in order so to change the extent to which the charged lubricant particles are caused to pass to the first pole as to effect a desired change in dimensional characteristics.

32. An apparatus for rolling a metallic workpiece which apparatus comprises rolling means including a roller which functions as a first pole of the hereafter specified electric field in use of the apparatus and a nip for receipt of said workpiece for rolling, a reservoir which in use contains a lubricant oleaginous emulsion comprising electrically charged lubricant particles influenced by said electric field so as to pass to and adhere on said roller pole, a plurality of second pole pieces spaced apart in said reservoir along an axis spaced from the roller and extending lengthwise with respect to the roller axis, a plurality of sensors respectively for sensing dimensional error in the rolled product in respect of particular respective portions of the transverse dimension of the rolled product, means for transmission of signals representative of sensed dimensional error and means responsive to such signals to change the potential of one or more of said second pole pieces so as to effect such variation of the adhered lubricant particles as to remedy the dimensional error in respect of subsequently rolled product.

33. An apparatus substantially as hereinbefore described with reference to, and as illustrated in, anyone of FIgure 2,6,9 and 10 of the accompanying drawings.

34. A method of working a metallic material workpiece wherein the workpiece and working tool contact surfaces are lubricated by an oleaginous emulsion containing charged lubricant particles which migrate to the workplece and/or tool under the influence of an electrical field so as to increase the amount of lubricant material on said contact surfaces.