BE543211A - - Google Patents

Description

       

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   The present invention relates to wire drawing, and more particularly it relates to a process and a wire drawing apparatus improving lubrication and reducing the energy required to perform the work.



   When drawing or drawing metal rods or wires to reduce their diameter, the deformation of the metal is achieved primarily by subjecting them to stress beyond their draw limit using applied forces of outside (tension or compression).

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 In normal threading operations5, 14% of the forces used primarily constitute a combination of tensile and compressive forces, as the rod or wire pulls through a narrow die hole, which exerts pressure. compressive force to reduce the diameter of this wire.



   In some cases, it is customary to apply, in addition to the initial drawing tension, which may
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 be referred to as "reverse pull", and that is, a braking force which is applied to the wire before it enters the die, so that the pulling force must be increased to a corresponding extent to overcome both this braking force or reverse traction and the forces resulting from the compression effect of the die ensuring the reduction in diameter.



   Passing the yarn through the die causes considerable friction and consequently energy losses; it also causes rapid wear of the die. It is therefore always desirable to lubricate the die to reduce friction losses and wear. It has long been observed that the compressive force to be exerted by the die
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 can be reduced by subjecting the wire to "pre-stress" before it passes through this die. The above reverse pull is one form of pre-stress, but another form which has been suggested is the application of a force. wire compression in the area immediately in front of the die.



   Various methods of lubrication have been proposed, the lubricants used mainly being formed

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 by oils (liquid lubricants), greases and tallows (semi-solid lubricants) and powdered soaps (solid lubricants).



     When using liquid lubricants and semi-solid lubricants, which transform themselves into liquids under the effect of the fraction heat generated in the die, it has been found that an improvement in the working conditions can be obtained. If liquid can be transferred under pressure to the area immediately ahead of the die, several proposals have been made to provide this pressure lubrication.

   This is how pa was suggested. example the use of a closed chamber in which the lubricant under pressure is pumped by force applied from the outside, so that a certain quantity of lubricant passes through the die with the wire
This procedure is not always satisfactory and it requires in each case an additional device and power ...



   It has also been observed that the movement of the wire can be used per se in certain cases to ensure the injection of the lubricant into the die. For the study of the behavior of the lubricant in the application, we will use the expression "upstream" to denote an opposite direction, 1 that corresponding to the displacement of the wire, and the expression "downstream. "to denote a direction which corresponds to that of the movement of the wire.



     It is known that, if the thread passes through a tube with an internal diameter slightly greater than the initial external diameter of the thread and comprising an orifice of

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 throttled outlet forming a die, this wire acts as the movable element of a pump if the end of the tube situated upstream is immersed in a liquid lubricant. When the wire enters the tube, it entrains by suctioning the liquid lubricant and thus creates a pressure in this lubricant upstream of the die. It has been suggested that inlet tubes of this type be used to ensure the
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 pressure lubrication of the die.



   - It has always been assumed up to now that the real deformation of the wire must be ensured by physical contact between the internal surface of the die and the outside of the wire, and all the efforts tending to reduce the resulting energy losses of the friction-corresponding to this physical contact were simply pointed in sight. to establish a certain. degree of lubrication in the die itself.



     . The research which led to the invention has, however, made it possible to observe that it is possible, in certain cases, to remove the physical contact between the yarn and the die and thus reduce to an extent
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 appreciable energy used for wire drawing.Llinvention, eB't4o'na materialized in a working process
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 of a wire drawing machine of the type comprising a tube ay4a4h throttled outlet through which ,,. ; , i '....;

   : .- the ',., L e under the effect of traction, and in which-. 1 4 tî le.; L5 'momVement of the wire is used to make penetrate the.utiant in the tube and to generate a pressure dE4o ,,, e lubricant, this process consisting in providing between the clearance left between read ìl'and the tube, tube length, diameter of the throttled outlet hole, wire travel speed, pull

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 EMI5.1
 wire drawing in this wire and. la v.s4as.t 'noß'enn7, v r .d lubricant during en passage dal, 4pl, lo tubes tion such that.all of these factors ooo & retf.t for in `` quJ,' 'in the lubricant which is. found in tube ,,.; <e () /.$# fi j j ';

   z 'point located upstream of the orifice, 6 tr'> sufficient pressure for the fluid to cause
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 a plastic creep of the wire, from a.gn, cü, e r a section, straight is reduced before it .n reaches 3, gze Itorifico of choked output.
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  Research has shown that, when etching, a wire of known diameter at a known speed also passes through a tube of inner diameter and length. known having a constricted outlet orifice whose inner diameter is not greater than the initial outer diameter of the wire, and when a lubricant of
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 known viscosity is supplied at the ambient pressure and temperature at the end of the tube situated upstream, the pressure generated in the lubricant being present; inside the tube can be calculated by hydrodynamic principles known per se.



   The experiments carried out have shown that the wire does not in fact follow the geometric axis of the tube, but that it takes an eccentric position in it, coats
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 position being a shovel for which it meets the least resistance when it passes through the lubricant under pressure.



   These experiments have further shown that in these
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 oonditipne known, the pressure generated in the lubricant is txauvart inside the tube can 81i be calculated by the following formula, in which: L is the length of the tube in centimeters,

 <Desc / Clms Page number 6>

 
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 H is the play, radial, that is, the dîìér>; n = e between the initial radius of the wire and the internal radius of the tube,. In centimeters.



   V is the speed of the wire through the tube, in .centimeters per second.



   Z is the average viscosity of the lubricant in the tube, expressed in poises (dynes-sec / om2), 'and P is the pressure of the lubricant inside the tube in the area immediately ahead of the die, in dynes per square centimeter;
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 .P ç: 3.40 ZVL - 1I 'On.' will easily be understood that the viscosity of the lubricant will vary in each case over the length of the tube.



  At the inlet, the temperature and pressure are low.
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 As the lubricant advances through the tube, the temp6: aL-burc., Increases, which tends to reduce the viscosity. At the same time, the pressure rises, which tends to increase the visco-
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 site. The determination of which of these two opposing effects predominates depends on the dimensions chosen for the apparatus and the product, and on the ratio between H and the radius of the wire.
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  The essential peculiarity of the.xvnt3.on lies in the fact that it is established in the lubricant this hole
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 before in the tube a pressure reached .t a value such that it is, in fact, sufficient to cause plastic creep of the metal of the wire, in order to deform 'the latter and reduce its cross section *'
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 The greatest resulting advantage 1, wl.t3nvv.ota y, is obtained when the pressure wb reaches a d. ** $. D SMf: Ms to reduce the diameter of the wire of the wire, r a value less than the imi7irior diameter of Tr '..fairy.

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 throttled outlet forming a die.

   Under these conditions, the wire passes through the die while being completely surrounded by a film of lubricant which prevents any physical contact between this wire and the die. It will be appreciated that, under these conditions, die wear is extremely reduced, the required draw or draw force being markedly lower, and the quality of the yarn being improved.
The research carried out has shown at the same time that it is still possible to obtain considerable advantages by proceeding according to the invention with a yield slightly less than the maximum yield.



  In the latter case, the pressure is sufficient to deform the wire but the degree of deformation is slightly less, and the diameter of the wire is reduced so that it is a fraction greater than the inside diameter of the orifice. Under these conditions, there is slight physical contact between the constricted outlet and the wire, which ensures final fractional reduction as well as burnishing of the wire, but a considerable amount of lubricant passes through. the die and the compressive force required to achieve this final fractional reduction is considerably less than that usually required in conventional type apparatus.



   To obtain maximum efficiency, with total hydrodynamic lubrication, that is to say that the film of lubricant completely separates the wire from the constricted orifice forming the die, it is necessary, as tests have shown. ,   that the

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 pressure of the fluid in the lubricant either in the part immediately upstream of the constricted outlet orifice, and when it is added to the value of the tensile stress of the wire generated by the fluid friction at l inside the tube and by the reverse traction exerted on the wire (if this inverso traction is used) at least equal to the value of the standard stress of 0.1% of the wire, measured by a tensile test.



   The 0.1% standard strain of the yarn is defined as the stress or force necessary to cause permanent elongation of the yarn representing 0.1% of its length.



   The principles on which the invention is based can be applied both to liquid and semi-solid lubricants, such as oils, and to lubricants formed by powdered soap, such as those normally used in the art of washing. so-called "dry" drawing. However, there are important differences in the equipment used. It is therefore necessary to study the behavior of the lubricant in each case.



   If we consider first of all the liquid lubricant, the apparatus used comprises, as already indicated, a tube of predetermined dimensions, mnui at the end situated downstream of a constricted outlet orifice forming the die. When the wire penetrates the tube by pulling, the die first acts in the normal way by physical contact, but as the wire drawing speed increases to a predetermined rate, the pressure increases, and after the conditions of total hydrodynamic lubrication of the. sector reach your

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   that is, 'the conditions in which any physical constact between the die and the wire is suppressed the lowered drawing force, as can be seen,

   up to a minimum value.



   It has already been indicated that the wire takes an eccentric position in the tube, following the path of least resistance. Research has shown that when the pressure increases, some of the lubricant comes out of the tube backwards, leaving this tube on the side opposite to that from which the wire exits. There is therefore a partial circulation which tends to push back and out of the tube small particles of oxidized deposit or other material, which are thus detached from the surface of the wire during its deformation.



   For. To be able to study the behavior of a lubricant formed by a solid soap, it is first of all necessary to explain the usual dry drawing techniques used up to now. In these techniques, it was customary to apply the soap to the moving wire in the form of a powder. Again, the movement of the yarn is used to drive the powdered soap to the die, and special apparatus is employed to compress the powdered soap to form a light coating around the yarn.



   The apparatus usually used in dry drawing techniques of the usual type comprises, in general, the usual diameter reduction die, combined with a reservoir for powdered soap, usually referred to as a "soap box". , placed on the wire in front of the die at a certain distance

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   of it. The thread passes through the walls of the soap boot and passes through the soap powder. When it leaves this soap box, it passes in certain cases through a member called the "soap nozzle", which is a funnel-shaped orifice having a bore with a wall converging inwards in the direction of movement of the wire.

   The surface of the moving wire picks up powdered soap from the soap box and entrains the soap into the aforementioned nozzle and compacts it, so that it adheres more closely to the surface of the wire. There is sufficient clearance between the narrowest part of the nozzle and the wire to allow this wire to entrain through this nozzle a substantially continuous coating of compacted soap. which then remains applied to the thread until it reaches the die, and which acts as a lubricant in that die.



   It will be understood that the fitting itself is not used in any case as a drawing die and then ... that its minimum diameter is greater than the initial diameter of the wire. It simply serves as a device applying a coating of solid lubricant to the wire. , upstream of the sector.



   In the usual plow wire drawing techniques, it is known to coat the wire with lime before it dyes the soap box, in order to neutralize the effect of the acids used at an earlier stage to remove the thread of its oxidized film.



   Research has shown that if one uses a lubricant formed by a soap powder without modification of the mouth of the tube 'the inlet to form a nozzle at
Soap, lubrication is less effective than with

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 usual techniques. On the other hand, if this modification consists simply in applying a customary bype soap nozzle to the mouth of an inlet tube, such a modification
The fication is not in itself sufficient, since the dimensions of the usual nozzle do not allow sufficient compacting of the soap.



   While in the usual nozzle the soap is compacted to a certain degree to form a cake, and is spread over the wire as a film, the film is not extremely adherent since the pressure for compacting is not very high.



   In order to be able to successfully apply the principles of the invention to lubrication with powdered soap, this soap must be subjected to a much higher pressure than that prevailing in the usual nozzle. This pressure must first be sufficient to compact the powdered soap tightly, so as to form a homogeneous solid mass around the moving yarn and to exert a continuous compacting effect. The friction exerted on the moving wire then causes a considerable increase in the temperature within this mass. 'As a result the soap is transformed. into a coherent viscous mass which exhibits the properties of a fluid and which can achieve plastic creep.



   Very little is known at the present time as to the behavior of soap when so transformed by heat and high pressure, and its precise state under these conditions is not completely known. The expression “quasi-fluid” will therefore be used throughout the description to denote a lubricant formed by a powdered soap.

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 which has undergone the aforementioned transformation by the chalaur.

   the temperature change caused by the passing of the yarn with friction through the solid mass 1, transforms the soap on the downstream side of this solid mass into a mass with a quasi-fluid momentum The soap retains this state is then drawn through the tube while remaining on the wire; it also retains it until it has passed through the orifice of constricted section forming the die.

   When it leaves the die, the soap film quickly cools and solidifies to form a coating which adheres tightly to the wire, which now has a smaller diameter.
The important difference that has been observed between the behavior of a solid lubricant formed by powdered soap and a liquid lubricant such as oil is that the phenomenon of reverse flow "out of the box. tub does not seem to occur when using soap as a lubricant.



   There is therefore reason to believe that the solid mass of compacted soap, which is continuously formed in the nozzle, exerts an equally continuous compressing or pushing back effect on the soap in its quasi-state. .



  . fluid and prevents appreciable reverse flow,
The invention therefore relates to a method of drawing or drawing using an apparatus having a tube with a throttled outlet and in which the movement of the wire is used to introduce the lubricant into this tube. , this process consisting of stimulating powdered saven as lubricant, which must be applied to the wire before it enters the tube, and

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 to ensure the supply of powdered svon by penetration of the wire, under the effect of traction, in a compacting nozzle which surrounds this wire,

   which is integral with the tube or which is connected to it in a pressure-tight manner and which is designed to cause the compacting of the soap into a homogeneous solid mass surrounding the wire upstream of the zone in which this nozzle joins the tube , so that the passage of the yarn through this mass increases its temperature to a sufficient degree to transform the soap opening on the downstream side of the mass into a semi-fluid mass, the movement of the wire through the mass. tube can thus be used here again to entrain the quasi-fluid soap in this tube and generate, in the quasi-fluid soap located in the tube, sufficient pressure to deform. the wire by a hydrodynamic effect in the area immediately in front of the die.



   The properties of the different soaps which are used for wire drawing are not necessarily constant. Their composition varies, as does their faculty to be taken, or carried away by the moving eye. Their "softening range" (that is, the range of temperatures in which the change from solid to near-fluid state occurs) varies. also. Their viscosity at a given temperature is therefore variable depending on the soap used.

   Thus, the behavior of a particular soap may not always be predetermined with sufficient precision to allow any formulation, such as that mentioned above. to be applied with a certainty of immediate sucking.

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     The general application of the principles of the invention to a lubricant formed by a soap exhibiting in the quasi-fluid state a much higher viscosity than that of an oil or a grease makes the advantages which should result therefrom obvious. The higher viscosity should theoretically allow operation with a shorter tube, with greater clearance between tube and wire, and at higher temperatures than may otherwise be achieved with an oil-formed lubricant. This results in a more compact construction set.



   It is evident that the pressure settings in the tube necessary to produce rather critical hydrodynamic lubrication conditions can be obtained by modifying the value of one or more of the various variable factors which intervene, namely: reverse pull (if used), lubricant viscosity, tube length or clearance between tube and wire, and wire drawing speed.



   Reverse traction is not always desirable because it increases the energy required for wire drawing.



  The 'change in viscosity' is more easily achieved with a liquid lubricant than with a soap, since a liquid lubricant can, if necessary, be diluted to reduce its viscosity, while a soap cannot. to be "diluted" in this way. The speed used can be changed, but these variations must be considerable to cause an appreciable change in pressure, and with variations in tube length or clearance, they can only be known by disassembling the apparatus and replacing the tube. tube.

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   It is of course essential to achieve constant pressure conditions in any apparatus when hydrodynamic lubrication is employed in the area forward of the die and usually in the die itself.



   If the lubricant pressure is too low to cause plastic flow of the metal, then wire deformation must be ensured by physical contact with the die. It is obvious that, under these conditions, no improvement is obtained over the usual drawing methods. In fact, the device does not operate on a hydrodynamic basis.



   The experiments carried out have shown that, if the pressure of the fluid is too high in the apparatus, it can drop of itself continuously by passing "jets" of lubricant at substantially regular and relatively short intervals to. through the industry. Excessive pressure causes sudden deformation of the wire beyond what is desired. This momentarily increases the clearance between the wire and the constricted outlet, allows a jet of pressurized lubricant to escape, and lowers the pressure. If this occurs continuously, the irregular pressure causes passage through the constricted exit orifice of a thread having alternately constrictions and bellies, which is undesirable.



   Although the pressure of the lubricant in the area in which the wire undergoes hydrodynamic deformation. is critical and the permissible pressure variations are small for a given group of working conditions, it has however been found that using a

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 nozzle and a tube with a lubricant formed by a powdered soap, the apparatus, object of the invention, has a self-adjusting faculty which allows satisfactory operation over an appreciable range of working conditions.



   This self-adjusting faculty is due to the fact that there is an increase in the pressure in the nozzle, and consequently an increase in the temperature caused by the passage of the wire with friction through the solid mass. , this increase in temperature accelerates the conversion of the soap between the solid state and the quasi-fluid state. In. As a result, the effect of settlement or repression is reduced and the result. You reduce the compaction pressure, so that the hydrodynamic pressure in the quasi-fluid soap is reduced as a result of the reduction in its viscosity, itself due to a rise in temperature. Conversely, if the pressure drops, the temperature also drops and the viscosity increases, so that the pressure is restored.



   Independently of the self-adjusting qualities of the apparatus, it has been observed that it is possible to regulate the pressure of the quasi-fluid soap by adding to the powdered soap and by dispersing therein a pulverulent substance. (hereinafter referred to as "filler material") intended to reduce the frictional force between the soap and the wire and between the soap and the bore of the tube, such that 1 :, pressure build-up speed in the quasi-fluid soap and, consequently, the final pressure obtained, are reduced.

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   Investigations have also shown that lime and talc are particularly satisfactory fillers, although experiments can show that other non-abrasive powdery substances have, when added to soap,. powder and after uniform dispersion therein, an identical or even better effect,
The experiments carried out have also shown that the use of lime as a filler must be carefully controlled, since an excess of filler can reduce the effect of "dragging" or "taking" the soap by the yarn in. a canvas measurement that an appropriate compacification is no longer obtained in the nozzle, and,

   that as a result .the device does not function at all. This detrimental effect manifests itself in. especially if, for some other reason, the wire has received a thick lime coating before it penetrates into the soap bundle. This thick coating tends to become concentrated in the nozzle and cause plugging thereof so that an insufficient amount of powdered soap penetrates it.

   In order for the apparatus to function satisfactorily, therefore, the filler material must be uniformly dispersed throughout the mass of powdered soap in the box or thirst entrained in the correct proportions with the soap. powder until the nozzle.



   It will be understood that if a small amount of filler material is added to the powdered soap, it can be used to increase the effective viscosity of the quasi-fluid soap, and hence to increase the effective pressure. However, a material exees

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   load has the opposite effect, because even if it is not sufficient to prevent compacification, it can reduce the flow properties of the quasi-fluid soap to such an extent that it ceases to behave like a fluid during the establishment of hydrodynamic pressure.



   Research has also shown that variations in the hardness of the soap affect the operation of the appliance. When using harder (metallic) soaps like lithium and barium soaps, a relatively short tube can be used. If, on the contrary, softer soaps are used; like sodium stearates, the length of the tube must be increased significantly. This is a natural consequence of the difference in viscosity - between the various types of soap when they are in a state, near-fluid. '
In addition, the particle size or grain size of the soap powder is important.

   Research!:; have shown that lion cannot satisfactorily use very fine powdered soap particles such as those corresponding to a grain size of about 0.4 mm for example ;, because they will then clog up the 'nozzle. It has also been found that too large powdered soap particles, such as those up to about 1.3 mm, for example, are not appropriately entrained.



   As a result and according to the invention, the powdered soap is chosen, from the particle size point of view, from a range corresponding to particles included. Miter 1.2 mm and 0.4 mm approximately; For most applications (wires or rods with a diameter between -6.4 and 3.25 mm).

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 a powder formed of 0.25 0.4 mm particles gives satisfactory results.

   In a way! OJ "l genero.e ', ulie, particle size greater than 1.06 1; n'ii p 1 f! .T not', '' satisfactory for the châl.r'Sé. L "i A judicious mode of determining the conditions,> 1 1 r '1,1 of work required, when the quality of the soap is not
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 lit., .. j, not exactly known, consists of. f;

  eLü.o. a preliminary calculation, based on the assumed viscosity of the
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 soap when it is in the quà-fluido state ot on the diameter of the types of threads to be drawn 8. The reel valve is then adjusted with a tube of suitable length and clearance to obtain a slightly higher pressure to that necessary to deform the wire.
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 then run with pure ppudre soap (nc diluted by a filler) at a speed which
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 on the production of an iretJïx surface yarn; or wrinkled. Then the chosen filler material is added to
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 powdered soap to reduce the pressure "jusgu t'à co '',: '', 1 '. l Iw: 1r, that the surface irregularities of the wire r, spâro; 3,' qx '.



  ,
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 The apparatus is then operated in a n3 fashion. (maintaining the same ratio '' between the part 'of :, 1 \ il'. ',. <' "'', load and soap 'in: powder) up to the'., '..,. e, 1 es'3ai 'TJ or until the use of a 110uveau.J.ot, $, soap powder with non-oôhnùɵ properties;.> "' i Research has shown cuu; ,, tv, z ,,, 1 resu.Lth 'Research has mon) rf qj,' q4 ,,, results of the use of the 'powder soap comttt6.' lubricant under hydi'oêl lubricating conditions; yn.miy ' 11, lies in the fact that the device iJ 1110n,; l, oenoiblc t'1, 'l to dimensional variations cue' t, han s the case of the use of a liquid lubricant.

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  Another avztae of the use of a very viscous iuùiifx) 1i lies in the fact that Al allows M6 much more latitude, rwMde in the irregularity in * '' cross section of the rod or wire to be drawn, without sf4,. give priority to the hydrudynan.iquos do llçqpparill properties. : "j Given the low clearances acl, which can be obtained when fusing with a liquid lubricant, any appreciable irx6guarity of the cross section of the wire breaks the film of lubricant and makes contact with the tube, thus destroying the tube. hydrodynamic effect. The larger permissible clearances with a lubricant formed by a soap powder allow much greater irregularities of this type.

   This advantage is particularly apparent when the apparatus is used for the initial reduction of the diameter of rods or wires of average diameter as they pass through the first hole (roughing) of a drawing bench with several holes: out of ' the use of a device '. according to the invention instead of an ordinary die, such an improvement in the lubrication conditions can be obtained that the following holes do not need to receive additional lubricant because of the presence of the film which adheres tightly to the yarn to the exit of the first hole.

   It was observed * '' that, even under these conditions, the wear of all the dies of the. machine was reduced in an appreciable proportion, quintupling or tenfold in some cases the useful life of the dies.



   Another advantage of using a lubricant '
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 high viscosity lies in the ± # <1.t that one can use temperatures and nr: won bc.¯ucot more

 <Desc / Clms Page number 21>

 
 EMI21.1
 high (provided, of course, to modify (1 (, corresponding fgeon the arrangement of the device pqur akGn.e increased resistance and to use, if 17.t'3G'C; ,, o: cil. 7. "t a suitable cooling system) which allows
 EMI21.2
 therefore to use higher working speeds, Li high corresponding to a better efficiency.



   The description which follows, given with reference to the appended drawings given without limitation, will make it possible to better understand the invention.
Fig. 1 is a schematic sectional view of a
 EMI21.3
 drawing or wire drawing tube according to the invention provided with a throttled outlet opening suddenly forming a die of the tube.
 EMI21.4
 'Fig. 2 is a view in section s Èdmatiquo aitiiie variant of the drawing tube provided with a constricted outlet orifice made separately from the tube, but mounted in
 EMI21.5
 conditions achieving with this one-etariah6it6 to the pressure.



   Fig. 3 is a schematic sectional view cor-
 EMI21.6
 responding to a variant of what the zig showed. 2, '1 the apparatus represented by figs. 1 # 2i '' 3 suitable> '"' <lei for use with liquid lubricant.



  Fig. 4 shows the head d.ëtirao "oomport: nt a nozzle and a tube, 'and study rn view 4.r lwu; al: ln.Liorr of uyi lubricant formed; by a soap powder"' laT ' ., j the pretsier hole (degroissue) of a Machina in Li, 1 ± 1 1 <ji y ptsieus, treis and; Ct.e pyM't'bT.'o inLe.'chy'biiii of dies and a.z-LLy.s. the Interior of 1 Summer.



  The S-ILT. 5 shows, a f itj-'è're rmwj6b * Lrôo rwb. i i'é ae Fà.îisablo in 1a bé.be J'éti. ag r'epr'és <Tt sr ia ti, g,,

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The apparatus shown in fig.l comprises an inlet tube 1 having a predetermined length and internal diameter µ, provided with a constricted outlet port The inside diameter of the tube 1 decreases towards the constricted outlet port 2, and the mouthpiece 3 = the
 EMI22.1
 this orifice is flared. A flange of: .ixac-lon 4 is shown on the tube, but it is obvious that any other suitable fastening device can be used.
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  The apparatus shown in fig. 2 comprises a choked outlet elézonent 5, which has the foxme @ of an ordinary die, arranged in a frame 6 having, a 'flared mouth 7 and fixed by a fitting, 8 on the end of a tube 9. Thus the throttled outlet element 5 is maintained, applied strongly against a
 EMI22.3
 round..e, d 1 étanehéitê 10 carrying out a tooint. 4 / çnche 'to the fluid between the die 5 and the tube.



   The apparatus shown in fig. 3 is amended in this. sense that the frame 11 is carried by the end of the
 EMI22.4
 tube 9, and that. 1 t 5 "constricted element is logo in this. Mount and is applied against the end of the tube, with the interposition of an ethanol washer 12, the elements being held in place by a nut 13 screwed into the mount. .



   In all cases, the inner 'diameter' of the tube
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 must be calculated) - "according to the above formula, as a function of the initial diameter of the thread 14 to be drawn,
 EMI22.6
 of the length of the -tube ', of the viscosity of the 1, eyeJrà.ì <; nt used, and of the drawing speed, as indiu .erarxt.

   These measurements and calculations should also depend on the bu-tr. ; L Li :: t.Tl ':, 1 Z..S

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 should be varied according to whether it is desired to establish within the tube sufficient lubricant pressure to ensure all of the reduction in diameter of the wire in a single stage or in two stages. The lubricant is supplied to the tube. open end of the tube, using the wire to entrain this lubricant into the tube.

   Since some increase in temperature will occur as a result of the friction of the fluid, it may be necessary to provide cooling from the outside, for example by providing a water cooling system. the device. In addition, given the internal diameter and length of the tube, it may be necessary to
 EMI23.1
 the convenience of manufacture, to establish, a tube in several sections, -in which case the sections, can be joined together by joints able to withstand the appropriate internal pressure.



   It will be understood that the viscosity of the lubricant has
 EMI23.2
 of paramount importance. Although a tzi.l m3.nal has the advantage that its viscosity increases with pressure, so that the required pressure can be established more easily, it is more usual in the operations of drawing, to use a water-based lubricant.
 EMI23.3
 



  Experiments may need to be done to determine the type of r, luid, v; u3,., aonvien. .e better. If a lubricant formed by mineral oil is used,
 EMI23.4
 it may then be necessary to clean the wire before it undergoes another tr.ierr.ent. In each c;.>, The following wire stretches ..2lvrti, n will not be hbill: <n1,

 <Desc / Clms Page number 24>

 and if a finish is required, an auxiliary polishing operation should be used.



   The following table gives typical examples of tube sizes which provide satisfactory results for drawing copper and mild steel at the indicated speeds using lubricants formed from mineral oils having the viscosities also indicated. But one could equally well use other dimensions which have appropriate relations between them. Thus, for example, if the clearance between the wire and the tube is smaller or if a more viscous lubricant is chosen, the length of the tube can be reduced. The values indicated in the table were obtained by experiments which show their interest, but they are given only by way of nonlimiting.

 <Desc / Clms Page number 25>

 



  Soft copper wire.
 EMI25.1
 
<tb> Diameter: <SEP> Speed <SEP> of <SEP> Viscosity <SEP> of <SEP> lu- <SEP>: <SEP> Diameter <SEP>: <SEP> Length <SEP> of
<tb>
 
 EMI25.2
 of the briîiant drawing wire (poises): inside tube (cm)
 EMI25.3
 
<tb> (cm) <SEP> (cm / sec) <SEP> to <SEP> 25 <SEP> C <SEP> and <SEP> to <SEP> the <SEP>:

   <SEP> of the <SEP> tube
<tb>
<tb>
<tb> pressure <SEP> atm. <SEP> (cm)
<tb>
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<tb> 0.200 <SEP> 200 <SEP> 4.0 <SEP> 0.212 <SEP> 12.0
<tb>
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<tb> 0.200 <SEP> 500 <SEP> 1.0 <SEP> 0.212 <SEP> 17.5
<tb>
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<tb>
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<tb> 0.140 <SEP> 200 <SEP> 4.0 <SEP> 0.150 <SEP> 8.0
<tb>
<tb>
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<tb> 0; 140 <SEP> 500 <SEP> 1.0 <SEP> 0.150 <SEP> 10.0
<tb>
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<tb>
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<tb>
<tb> 0.080 <SEP> 200 <SEP> 4.0 <SEP> 0.087 <SEP> 5.0
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 0, 080,500 l, 0 z 0, 087 6, 2, ... 1i
 EMI25.5
 
<tb> <SEP> mild steel <SEP> wire
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 0.200 '' 200 4, 0 0.212 1, 0 0, 200 50b.: 1.0 0, 212 '19, 5 xr 0.140 200 0.150 Oel4O 200 4.0 0.150 9e5 0.140 500, 0.150 i 11.5 t,
 EMI25.7
 
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 s s':

   :::.



   The fluid pressures which are involved during the application of the method, object of the invention, can be easily calculated from the aforementioned formula, and it can be indicated as a general indication that, for the When drawing mild copper, a fluid pressure of the order of 700 kg / cm2 is required to ensure deformation and satisfactory hydrodynamic lubrication, while for drawing mild steel the fluid pressure required is l of the order of 1400 kg / cm2.

 <Desc / Clms Page number 26>

 



     . the. drawing head shown in fig. 4 is mainly formed of three elements joined in a pressure-tight manner, namely a nozzle, a tube and a die. These elements are placed in a die holder fitted with a cooling jacket and designed so as to be able to replace the usual die holders and to allow interchangeability of the dies and nozzles within the same head, in order to allow dimensional modifications according to the material to be drawn and the working speed.



   An outer casing 15, of usual external shape, receives a monturē16 held in place by a nut 17, via hermetic seals 18 and 19. An annular water chamber 20 is connected in the usual way to a device ( not shown) ensuring water circulation. If desired, water cooling can be provided along the entire length of the nozzle and tube.



   The frame 16 receives the die itself 21, and the pressure tube 22 and the compression nozzle 23 are mounted in axial alignment with the die. The elements 21, 22 and 23 are held together firmly by a retaining nut 24, and a pressure sealing washer 25 is provided between the die 21 and the pressure tube 22.



   As an example of dimensions considered appropriate, the following particular dimensions may be cited: - (1) The diameter of the tube is equal to the maximum diameter. mum of the rod or wire, plus 0.254mm. Thus, for example, for a mild steel rod having a diameter

 <Desc / Clms Page number 27>

 nominal 5.38 mm, the tube diameter is then
5.38mm + 0.254mm = 5.634mm).



   (2) For a wire of medium diameter (eg about 2 mm), the diameter of the tube should be equal to. maximum wire diameter (nominal diameter plus maximum tolerance), plus 0.126 mm.



   (3) The length of the parallel or cylindrical part of the tube should vary from 15.24 mm, to 25.4 mm., Depending on whether hard or soft soap is used. , (4) The radius of the flared part of the nozzle must not be less than 50.8 mm ..



   (5) This flared part must be connected progressively to the parallel part of the tube.



   (6) The maximum diameter of the mouth of the fitting should be approximately three times the diameter of the rod or wire entering it.



   To ensure uniform admission of the soap into the drawing head, the mouth of the nozzle must protrude therefrom, and penetrate into the mass of powdered soap in the soap box. If the inlet to the nozzle is obstructed by the die retaining nuts or by the walls of the soapbox, then plugging or occlusion of the inlet of the nozzle may occur. and, consequently, a reduction in the quantity of powder admitted.

   Given the increased consumption of soap (the nozzle consumes more soap than a usual die) the soap box must be of sufficient size to receive about 1.5 or 2 kg of powder, otherwise the worker must refill the soap box more often than cola seems wise. '' Soap boxes worn

 <Desc / Clms Page number 28>

 by some machines are, on this subject, from an agency-
 EMI28.1
 ment not appropriate. In fact, c er1i: .... illG; ::; ; 1:; ';: ,, 11: -11 1,: ühûl1 not for obtaining a 1 Ltûrii: w G1.01¯ 5 ..: G1: = .ī ¯.llLv with normal dies .



   The arrangement described in Figs. 4 and 5 is intended for use with hard (metallic) soaps. If it is necessary to use softer soaps, such as sodium stearates, the length of the parallel part of the nozzle should be increased, for example from 50 to 100%. In order for the nozzle to work correctly, all of the powdered soap that enters it must then enter the die.



   The degree of "soaping" can be adjusted in various ways. If the soap powder in the box is diluted with a very fine filler like lime, the amount of soap entrained in the nozzle, and therefore the amount applied to the wire, is lower. The same result is obtained by a moderate addition of very fine soap.



   The amount of soap entrained can also be changed by changing the dimensions of the nozzle, for example by shortening the tube, reducing the radius of curvature of the flared portion, and increasing the diameter of the nozzle. Each of these factors causes a reduction in the amount of soap passing through the chain.



   If desired, the tube and die
 EMI28.2
 can force an er .: (;; ".: 1) == - 'j.:', '. lJûiGC ^" .u:' al ') [1. LÔ .1.c 1 "fig. 5, ce e n s r- i b 4 ,, #;: .. l'.¯ ': - L1ri.t; dcf- .41 r -t ...



  : - .. t 22 on the -1 ". 4.

 <Desc / Clms Page number 29>

 



   Still other modifications may be made to the described embodiment within the scope of technical equivalence without departing from the invention.



   CLAIMS
1. A drawing process applied to an apparatus of the type comprising a tube provided with a constricted outlet orifice through which the metal wire is passed, the movement of the wire being used to introduce lubricant into the tube, this process consisting in ti-.

     tre 'characteristic, to be given to the clearance between the wire and the rood screen and between this wire and the restricted exit orifice, at the speed of movement of the wire, the drawing traction imposed on the wire and on' the average viscosity of the lubricant, such a relationship that these different factors cooperate to produce hydrodynamic lubricating conditions in which sufficient fluid pressure to cause plastic flow of the wire is generated in the lubricant , so that the right section of this wire is reduced.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

2.-. Wire drawing process consisting in using the wire as a movable element of a pump moving inside a tube having a predetermined length and having a certain clearance with the wire, this tube having an orfice throttled outlet, ensuring the conveyance through the thread of a lubricant having a predetanted viscosity and its penetration into the tube and to stretch the thread under a predetermined tension at a speed sufficient to generate in the lubricant a pressure of the fluid such that it causes, in combination with the drawing traction, a deformation that is substantially <Desc / Clms Page number 30> EMI30.1 permanent of. wire in a zone if-killed in auwnl, 1f '"). the tightened outlet orifice, so that we téa.Lig a hy lubrication (7irod5rm-inic total of the tllue and - UtM total or partial lubrication of 1 ariliuc:. 3. A method according to claim 1 or, wherein the degree of deformation of the wire corresponds to that obtained with a standard stress of 0.1. 4. A method according to claim 1 or 2, wherein the pressure generated in the tube and the drawing tension exerted thereon produce; together the entire reduction in cross section of the front wire, its passage through the exit orifice EMI30.2 strangled ,, which ensures liyàroàynéu lubrication; > 1.jb¯ie total of both the tube, and the throttled outlet, 5. - The method of claim 1 or 2, wherein the pressure generated in the tube, and the tension exerted on the wire together provide a reduction. initial of the, cross section of the thread the contact by, friction between a die formed by the constricted part formed at the end of the tube and the outer surface of the wire reassuring a final reduction of the cross section of this wire, so that total hydrodynamic lubrication of the tube and partial lubrication of the constricted part are carried out. EMI30.3 6 <.- "- Process 'following claim 1, consi; .ietnï: fL uGi.i: z powdered soap' as lubricant dev-tnb Itre al3p.ir.u: to the rod or to the wire before its , pc: nétr.ti oc in the tube, and to ensure the supply of soap in EMI30.4 p <R <) 'r' p-tr feed through the wire to m <Desc / Clms Page number 31> compacting nozzle which surrounds the wire and which is integral with the tube or makes a pressure-tight connection with it, this nozzle being designed so as to compact the soap to form a homogeneous solid mass around the wire upstream of the zone in which the nozzle joins the tube, so that the passage of the wire with friction through this mass increases its temperature to such a degree that the soap on the downstream side of the mass assumes a quasi-fluid state , the movement of the wire through the tube thus being able to be used in addition to assure the conveyance of the quasi-fluid soap along the tube and to generate 'in the quasi-fluid soap which is in the tube a sufficient pressure to deform the wire 'by hydrodynamic effect in the. part immediately in front of the die. 7. A method according to claim 6, comprising controlling the pressure of the quasi-fluid soap by adding to the powdered soap and dispersing therein an amount of powdered filler material. 8. A method according to claim 6, wherein the amount of powder filler material is such as to reduce the friction entrainment between the soap powder and the wire and between this soap powder and the bore of the tube, so that the rate of pressure build-up in the near-fluid soap and hence the final pressure therein is reduced. 9. A method according to claim 6, wherein the amount of powdered filler material is such as to act to increase the effective viscosity of the quasi-fluid soap and hence the viscosity. <Desc / Clms Page number 32> effective pressure. 10.- Apparatus for carrying out the method of claim 6 for drawing a rod or a metal wire with a formed lubricant. by powdered soap, this apparatus comprising a tube the bore of which is slightly greater than the initial diameter of the wire or rod to be drawn by passing through this tube, a constricted outlet orifice or die, provided at the downstream end of the tube, and an outwardly flared nozzle provided at its upstream end, the whole device being pressure-tight and forming a single-piece drawing head or a head made up of several assembled elements, the shape and dimensions of the nozzle and the tube being such that first of all there is a compacting of the powdered soap entrained in this tube by the movement of the wire and thus the continuous formation of a homogeneous mass of solid soap in the zone in which the nozzle joins the tube or upstream of this zone, then the branching of this soap, on the downstream side of this mass, and a substance in the quasi-fluid state, the entrainment downstream of this soap in the state, quasi-fluid by the fit,. and finally the establishment, in the quasi-fluid soap in the tube, of a pressure sufficient to deform the wire by an effect hydrodynamics in the area in front * of the die, EMI32.1 11. Apparatus according to claim 1, wherein the initial mouthpiece diameter of 11ijiit-ae rep, r, is at least dxt ci and denies the diameter. of Lùtige or strand with etixf-r, 1 & lor.fleur ..: .i.ax, aga <Desc / Clms Page number 33> flared, between its mouth and the zoïle in which it joins the parallel part of the tube, being at least equal to three times the diameter of this rod or this wire, the general internal profile of the nozzle considered according to an axial section being progressively converge, the shape of the nozzle being chosen such that it causes the compacting of the powdered soap which is entrained therein by the movement of the wire, thus continuously forming a homogeneous mass of solid soap in the zone in which this nozzle joins the tube 'or upstream of this zone, the temperature of this mass being raised by the friction of the wire passing through it to a degree such that the soap is transformed from the downstream side of the mass into a substance in a quasi-fluid state, the dimensions of the tube being in such a relation, with respect to the diameter of the wire or the rod, that it occurs , in the soap in the quasi-fluid state entrained downstream in the tube, a pressure sufficient to deform the wire by a hydrodynamic effect in the zone EMI33.1 located immediately avnnih ào the iî1ià Q.