MXPA97004982A - Barrel conditioning, prevenerez copper alloy thread - Google Patents

Abstract

The present invention relates to a conditioning process for obtaining a pre-wired metallic wire in a cylindrical barrel, characterized in that: a) the strand to straighten a series of spinning rollers, being dragged by a large-diameter winch that retains the yarn rectidud, b) after said yarn undergoes a stress when passing through two pairs of non-motorized rollers, located in two perpendicular and animated planes of a rotation movement around the yarn, c) the yarn, guided by a drum that has the same movement of rotation, is deposited in spiral in the bottom of the barrel, d) the barrel descends as it fills up, in such a way that the interval between the free surface of the thread and the base of the drum remains constant, the thread being an alloy of copper, of diameter less than 6mm, and mechanical strength comprised between 400 MPa, so that said winding wire is rectilinear, with a twist per meter inf erior to 5 mm, and can feed a tronza machine

Description

BARREL CONDITIONING, OE PREHEADED COPPER ALLOY THREAD FIELD OF THE INVENTION The invention relates to the conditioning of yarns of pre-stressed copper alloys, in the form of crowns in barrels, and with a view to uses that can mainly use a straightening of the yarn before use. The generic term "thread" will only be used in the following to designate the set of long semi-finished products, available in the form of a crown, as well as those of non-circular section.

FIELD OF THE INVENTION It is already known to prepare pre-strand wire, steel, to feed the automatic welding machines. In current welding machines, the wire is fed continuously through a conduit. To increase the autonomy of the machines, the yarn is conditioned in barrels of 250 kg. When pre-straightening the thread before the REF: 24546 placement in barrels, is obtained after the winding, a product without coil remaining or twisting. This allows, on the one hand, to limit the friction of the wire in the duct, and on the other hand to guarantee the straightness of the free wire portion at the welding point (the "adhesion - of about 30 mm length). as follows (see Figure 1): - the yarn wound from an impeller or reel, passes through a series of straightening rollers, and is dragged by a large-diameter winch, retaining the thread its straightness, then two pairs of rollers Non-motorized, placed in two perpendicular planes pass through the axis of the thread and driven by a rotation movement around the thread, they print a twist.The thread is then guided by a drum to its spiral deposit in the bottom of a barrel, - the barrel descends little by little as it fills, so that the interval between the free surface of the wire and the base of the drum remains constant, - at the end of the drum filling, it is applied a plastic washer on the top thread of the thread is attached to the bottom of the barrel by means of an elastic material, which allows to keep the product in its place. This technique is applied to the wires for welding a strongly cold rolled steel, of mechanical resistance typically comprised between 60-Q and 1200 N / mm2 and of diameter ranging from 0.8 to 1.6 mm. The pre-straightening technique allows the pre-straightened thread to slide correctly in a conduit several tens of meters in length, which allows feeding a mobile welding post from a heavy wire storage unit, where it remains fixed.

PROPOSED PROBLEM The invention seeks to improve mainly the current technology of micro-parting of semi-finished products of copper alloy, mainly brass. In the micro-tronzado, there are two types of machines or methods: Type 1: those where the machining is done mainly by a rotary tool, the material being fixed, Type 2: those where the fixed tool is applied to a material in rotation , as for example described in the patent application WO 81/01378. To ensure optimum machining precision at high speed, it is desirable that the material be in rotation, leaving the tool fixed. This requires that the material be presented in the form of pieces of relatively small length (generally 3 to 4) and sufficiently straight that they can be put into rotation. To constitute these pieces, also designated under the term "bar", one usually proceeds according to one or the other of the following two methods: Method A: The bars are manufactured by the wire producer with the help of straighteners. The micro-tronzado machine is then provided with a "bar deposit" called "shipper", intended for the feeding of the tool of micro-tronzado in bars. This technique has the following disadvantages: * due to the fact of the existing technology of the shippers and of the bucking turns, the straightness of the bars must be perfect, otherwise the bars get stuck in the shipper, or they cause vibrations at the time of the rotation, source of unacceptable geometric faults on the machined parts. To ensure a perfect straightness of the bars, the producer of brass bars must use specific machines for straightening relatively expensive wire (straighteners), and on the other hand the rate of straightening is significantly weaker than that of the drawing or drawing, which greatly decreases manufacturing productivity. For these two reasons, this method has high costs. * the capacity of the shippers is limited to a few dozen bars, the autonomy of the laps is also a consequence. It is therefore necessary to regularly reload the shippers after a few hours, which penalizes the productivity in the tronzado. * with regard to the imperatives of the accumulation at the time of transport of the maintenance of the bars, the length of these is limited (approximately 4 m). This penalizes putting into operation, since there is, for each bar put into operation, a decrease of approximately 200 mm, ie 5% of the length. Method B: The producer conditions the yarn in crowns, whose unit weight is generally 250 kg. The crowns are placed in the cylindrical cardboard barrels, closed at the base by a wooden base or pedestal, and at the top or head by a movable wooden or metal lid. To form these crowns, the producer of brass threads exerts on the yarn, just before the conditioning in barrels, a slight plastic deformation destined to confer a natural curvature, of diameter close to that of the barrels. This is necessary so that the placement of the turns is carried out in a regular manner, in order to eliminate the risks of entanglements at the time of handling and transport, and thus of the risks of jamming of the thread at the time of winding. In the cutter, the thread is extracted from the barrel with the help of a special winder, since it passes in a frame that surrounds the touches it straightens, and is then cut longitudinally by a shear. In this way bars are obtained which can be put into rotation for parting.

With regard to method A, method B has the following advantages: * the preparation of each bar is operated in hidden time, during the bucking of the preceding bar. In this way, straightening, much faster than bucking, does not cause any loss of productivity. * a barrel containing approximately 10,000 meters of yarn, representing several thousands of bars. In this way the autonomy of the lathes is multiplied by a factor of the order of 100 in relation to that of the method A. * The length limit of the bars is not linked to the transport and conditioning constraints, but to the place available in the workshop of the tronzado. In this way it is possible, at least theoretically, to machine the longer bars, and thus reduce the start-up (proportions of decreases less than 5%). Method B has thus enjoyed a huge preference in microtronzadores, in particular those that work on large series where the need for high productivity is imperative. However, method B presents the? following drawbacks: a) contrary to method A, where the producer of brass wires is equipped with a limited number of straighteners to produce the bars, the splitter must be installed in a large number (one straightener for each turn). The straighteners should therefore be of a relatively simple model, except for representing an extremely high investment. b) However, due to the fact of the use of "simple" straighteners, the straightening is much less careful than in method A, with the bars now being able to represent a twist of several centimeters. The splitters have partially alleviated this defect by modifying the feeding device of the lathes: the bar in the process of machining is enclosed in a case or envelope filled with oil. The oil bath allows the bar to self-center at the moment of rotation. This results, however, in that the straightness of the bars is not perfect, that the precision of the cut-off is not optimal (margin of 10 μm: nominal value + 10 μm, nominal value -lOμm, or nominal value ± 5 μm according to to the case) . c) method B is limited to relatively easy to straighten threads, the threads of diameter and high mechanical strength can not be straightened correctly. In this way, method B can not be applied to threads with a diameter greater than 3 mm, or even less in the case of threads of high mechanical strength (typically of the order of 700 N / mm2). d) the use of yarn, when machining long pieces, and particularly when the machining is obtained by rotation of the tool, leads to pieces that may have a very large residual twist, which the straightening device has not reached to be eliminated ("the memory of the brass" for the expert in the field): twist of the order of 0.15 mm for a piece of 40 mm in length, while the tolerance is 0.07 mm. This problem occurs on the two types of tronzado machines: those where the material is fixed (type 1) and those where the material is in rotation (type 2). In this case, it is necessary to previously submit the yarn crown to a complementary thermal treatment, consisting of a partial recrystallization of the alloy, which causes a non-negligible cost overrun. This thermal treatment allows to obtain pieces of great length (40 mm) with a twist of 0.05 mm. The invention is directed to propose a conditioning of copper alloy wire, typically of brass, which eliminates the drawbacks indicated above for methods A and B, in particular those listed under subparagraphs a) to d), for method B, namely: 1) the elimination of a lathe for lathe, 2) the obtaining of a higher precision truncated or greater speed, 3) expansion of the range of threads usable towards the high diameters and / or the high mechanical resistance, 4) very significant reduction or suppression of the residual twist on the pieces of great length, and this, without previous thermal treatment. On the other hand, the conditioning according to the invention, which solves the problems encountered in the cutter, does not significantly increase the twists in the yarn producer.

DESCRIPTION OF THE INVENTION A first objective of the invention is constituted by a conditioning process, in order to obtain a pre-straightened metallic wire in a cylindrical barrel, in which, a) the strand to be straightened passes through a series of straightening rollers, being dragged by a capstan of large diameter that retains the straightness of the thread, b) then said yarn undergoes a torsion when traversing two pairs of non-motorized rollers, located in two perpendicular planes, and driven by a rotation movement around the thread, c) the yarn, guided by a drum that has the same movement of rotation, is deposited in spiral in the bottom of the barrel, d) said barrel descends little by little as it fills up, in such a way that the interval between the free surface of the thread and the base of the drum it remains constant, said yarn being a copper alloy, of a diameter less than 6 mm, and of mechanical strength comprised between 400 MPa and 750 MPa, so that the yarn devan It is rectilinear, with a twist per meter of less than 5 mm, and can feed a cutting machine. According to a second method of using the yarn obtained with the process according to this first object of the invention, the yarn wound, rectilinear with a twist of less than 5 mm, feeds a cutting machine provided with a straightener. In this case, at the exit of the straightener, the thread presents a twist of less than 0.5 mm / m, a level that may be necessary for high precision machining. As the copper alloy, brass is preferably chosen, taking into account the use (the parting) that is made of pre-straightened yarn of this first object, but as will be indicated below, other alloys more "hard" or more are usable. "brittle" than brass. The upper limits of diameter and mechanical strength of the pre-straightened yarn result mainly from the need to limit the energy accumulated by the pre-straightened yarn at the time of barrel placement. Beyond a certain threshold, the accumulated energy will be very important to be contained by the armor of a barrel, and may also present a danger in the event of rupture of a barrel, involving the total release of tensions. The applicant has had the surprise to note that a yarn preparation according to the invention will make it possible to choose: * or to feed the cutting machines according to method B without using the rotating frame straighteners, which constitutes a considerable simplification of the arrangement and of the maintenance of these machines, and a significant reduction of the investment, * or else feed the cutting machines according to method B, using the rotary frame straighteners, which allows, on the one hand, to widen the zone of usable threads of according to method B, allowing the use of yarns of larger diameter, up to 10 mm instead of 3 mm, and of higher mechanical strength, up to 750 MPa instead of 650 MPa, and on the other hand, considerably improve the accuracy of the machined with a zone of 5 μm: nominal value + 5 μm, nominal value - 5 μm, or nominal value ± 2.5 μm, according to the case, and what also allows reduce the machining of the tools and the frequency of breaks of the wicks: the average amount of brass cut by wick is thus from 2000 kg to 5000 kg. In any case, the invention solves a problem of productivity and / or quality level of great economic importance. On the other hand, the solution to this problem can not be anticipated or suggested by the means mentioned in the state of the art, and relating to the conditioning of the steel wire for welding. In fact, on the one hand, for the person skilled in the art of the cutting of brass, the straightening of threads is perceived as an indispensable operation, inseparable from machining according to method B. The possibility of suppressing the straightening of the thread can not occur to someone with experience in the technique. On the other hand, this expert in the field is different from that of welding, and a known means in the field of welding on steel wires can not constitute a general teaching or teaching of a close domain for the expert in the field of cutting brass threads. Finally, taking into account the difference of the problem to be solved, even if the expert in the field of tronzado has known the use of pre-straightened steel wire in the field of welding, he will never have been able to imagine that the means used for a steel wire can slide in a conduit, be enough to allow the formation of a bar suppressing the straightening of the thread. Another object of the invention is constituted by a conditioning process, in order to obtain a pre-straightened metallic wire in a cylindrical barrel, in which, a) the strand to be straightened passes through a series of straightening rollers, being dragged by a large capstan diameter that retains its straightness to the thread, b) after said thread undergoes a torsion when crossing two pairs of non-motorized rollers, located in two perpendicular planes and driven by a rotation movement around the thread, c) the thread, guided by a drum that has the same movement of rotation, is deposited in spiral in the bottom of the barrel, d) the barrel descends as it is filled, so that the interval between the free surface of the thread and the base of the drum is constant, the wire is a wire for EDM that comprises externally a layer of Cu-Zn alloy, with a diameter between 0.15 mm and 0.35 mm, and resistance mechanics comprised between 500 MPa and 1100 MPa, so that said winding wire is rectilinear, with a twist per meter of less than 30 mm. The structure of the wires for EDM is described in numerous patents, for example in the European application No. 526,361-A1 in the name of the applicant. The applicant has verified that the solution found with the cutting wire will also be applied to the wire for EDM. In this case, the technical problem to solve is the following: at the moment that there is a thread breakage, the thread must be threaded automatically, so that the EDM can be continued without the need for manual intervention. For this, the wire EDM should not have a memory effect, whatever the end of a thread initially in a coil or in a crown, tending to form a loop that rolls on itself. In this way, after the thread is broken, the end of the thread retains its trajectory as if there had been no breakage of the thread. To date, the problem has been solved by thermally treating the yarn and / or straightening it before winding. The invention allows the suppression of these treatments, and avoids the use of coils, with the tensions linked to their use. In fact, on the one hand the use of coils limits the amount of yarn per coil (standard weights of 5 kg), the same if this quantity tends to increase. On the other hand, beyond 15 kg, the coils must be mounted on a motorized wire feeder, which at the same time generates cost overruns and vibrations incompatible with the precision of machining by electroerosion. Finally, the problem of recycling of these reels, made of plastic material, imposes itself with an enormous acuity. A coil can not serve more than 3 or 4 times at the most, taking into account the very important stresses to which it is subjected during the winding and tends to dislocate it, then it must be destroyed. The barrel conditioning according to the invention provides a particularly elegant solution to these problems: * barrels of important unit weight can be used without motorized winder, * the barrels can be reused a large number of times, since the conditioning operation does not cause important mechanical stresses, * the barrels can be composed of recyclable materials such as cardboard and steel. In the conditioning processes according to the invention, and in order to avoid the risks of corrosion under tension of the wire, said barrel can be a hermetic barrel, and possibly contain other means (desiccant sacks, products capable of fixing the ammonia, protective products of adsorbents on the surface of the yarn), to avoid these risks. In the case where the metallic thread is made of brass, the invention allows to ensure a hermetic storage of the pre-straightened wire crown (15), which avoids the risks of corrosion under tension of the thread ("season cracking" in English), in humid atmosphere or in the presence of ammonia. Other means can also be used to further limit these risks: the placement of desiccant sacks, or of products capable of fixing the ammonia, or of adsorbent protection products on the surface of the wire, thermal insulation of the barrels, which limits the impact of environmental temperature variations.

DESCRIPTION OF THE FIGURES Figure 1 represents a schematic section of a straightening pre-straightening device (1) comprising successively: * a winding system (4) of strand to be pre-straightened (1), and its winding regulation pad ("dancer" in English) (5), * 4 series of 7 flat straightening rollers, the second series being oriented 90 ° from the first, the third series being oriented at 45 ° to the right and the fourth series at 45 ° to the left. Only the third series (6) has been represented in Figure 1, * a large diameter winch (1000 mm) (7), in order to provide a straight line to the winch outlet, * two pairs of cylindrical rollers with grooves, mounted on the same rotating plate (8), which tightens the thread and it imposes a counter-distortion by means of rotation of said plate, * a drum (16) driven by the same rotation movement as that of the plate (8), allowing the guidance of the pre-straightened wire (2) in the barrel (3), and the forming a crown (15) of pre-straightened yarn, * a barrel (3) and a means of lowering the barrel (9), so that the base of the drum (16) rotates up to the crown or (15) of the crown. pre-strand formed in the barrel, and by its suitable diameter, imposes sensibly the inner diameter of said crown (15). Figure 2 shows in section the final conditioning of the crown (15) of strand pre-straightened, so that it does not have entanglement of turns of thread during transport: A plastic washer (10) is kept plated against the top of the crown (15), thanks to the hooks (11), an elastic (12), and a rigid rod (13) hooked by a ring (14) in the bottom of the barrel (3). The hooks (11), the elastic (12) and the rigid rod (13) are placed to hold the thread during transport and storage before use. These are high, at the time of the use of the thread, in order to allow the turns to be wound.

OTHER OBJECTIVES OF THE INVENTION Other objects of the invention are constituted by the use of a pre-straightened yarn conditioning according to the invention for directly feeding yarn the machining machines, in particular lathes and tronzadores, or cold-blow forming, and by the use of a pre-straightened yarn conditioning according to the invention for feeding yarn to a spark-erosion machining machine. The invention also comprises the use of a conditioning of any pre-straightened metal wire, whether it is steel wire, or non-ferrous alloy other than copper, to feed wire directly to the machining machines, in particular the lathes and tronzadores, or cold forming machines. In effect, the applicant has been able to verify the applicability to steel wire, of the concept developed with copper alloys, such as brass, and discussed above.

EXAMPLES OF REALIZATION EXAMPLE 1 A crown (15) of pre-straightened yarn (2) has been prepared. This thread has the following characteristics: - composition: brass of 36% Zn and 3% Pb - Diameter: 1,825 mm - Mechanical strength: 620 MPa The device shown in Figure 1 was used. It has been used as a straightener (6), 4 series of 7 flat straightening rollers, oriented relative to one another (+ 90 ° / -45 ° / + 45 °). The sliding speed of the thread is 250 m / min and the speed of rotation of the pair of rollers (8) and the drum (16) is 130 revolutions / minute. This thread has been conditioned in the barrel (3) of 250 useful kg, as shown in Figure 2. This barrel must have a sufficiently high diameter so as not to impose a curvature on the yarn that will go beyond its elastic limit. Typically, this diameter will be 510 mm in the case of a small diameter wire (less than 1 mm), of 580 mm in the case of a medium thread (diameter of the order of 1.8 mm), and of 620 mm in the case of a thread of the order of 3 mm. The previously obtained strand (2) obtained with the use and without the use of a rotary frame straightener has been tested on a "TORNOS" (R) type cutter: - without the use of a rotating frame, bars of 4 m have been obtained. They present 4 mm of twist iura per meter. This twist value is appreciably that obtained with a bar obtained according to method B, after an operation of straightening on a rotating frame with touches of a thread of the same nature and geometric characteristics. After the use of a rotating frame, bars of 4 m have been obtained that have a maximum value of 0.5 mm twist per meter, which corresponds substantially to a level of straightness of the bars obtained according to method A. be the twist per meter, there are fewer vibrations at the time of rotation at high speed of the bar, and the precision of the machining is greater, or, at choice, the machining speed is higher. Typically, the accuracy currently available with a twist bar close to 4 mm / m is 10 μm, while that accessible with a twist bar of 0.5 mm / m or less is of the order of 5 μm.

Similarly, if the machining speed is considered at constant precision, the productivity gain is approximately 15% when going from a bar of 4 mm / m twist to a bar of 1 mm twist or less. The applicant has carried out numerous other tests varying the nature of the copper alloy and its geometric or mechanical characteristics, the machining techniques and the geometry of the machined parts. In particular, it has been observed that, in the case of the machining of long pieces (typically 40 mm), the pre-straightened yarn according to the invention will allow to avoid the heat treatment of crowns, necessary to erase "the memory of the brass" , and obtain, without thermal treatment, pieces with a 0.05 mm twist, for a tolerance of 0.07 mm. The applicant has also used the pre-straightened yarn according to the invention to manufacture parts, no longer by machining, but by cold striking. It has even been observed that, in the case of long pieces, typically from 30 to 50 mm, the problem of twisting is also found, due to the remaining deformation caused at the time of the bending preceding the placement in the barrel, and lead to rejection of the final part, despite repeated replacements of the straightening device. In this case also, the pre-straightened yarn of example 1 has allowed to considerably limit the value of the twist. A typical example of pieces obtained by cold striking, taking into account the narrow geometric tolerances, are the anodes of alkaline batteries. The tests have also been carried out on wires of different diameters (tests with brass wires of 3 and 6 mm in diameter), and of different mechanical strengths: "hard" or "brittle" alloys such as the bronze with lead (Cu-Sn-Pb), or the lead alpaca (Cu-Zn-Ni-Mn-Pb), in the limits, as they will appear in claim 1. These limits result from the need to obtain a twist less than 5 mm / m for the rod subjected to rotation for machining (method B). Threads that are too thick and / or too strong are used, this results in a residual twist that exceeds that limit value of 5 mm / m from the bar.

EXAMPLE 2 A crown (15) of pre-straightened wire (2) for EDM has been prepared. This thread, according to that described in the example of the European application 0, 526/361-Al, will present the following characteristics: - composition: Cu-Zn37 - diameter: 0.25 mm - mechanical strength: 910 MPa This thread according to the invention has been tested on the EDM machine, in relation to a standard wire. A standard yarn comprises a thermal or mechanical straightening treatment before winding. The yarn in barrels according to the invention behaves similarly to that of the bobbin yarn, heat treated or mechanically straightened, according to the prior art.

ADVANTAGES OF THE INVENTION The invention solves the problems encountered in various types of users and in various types of materials: those of the tronzado and those of the EDM, and also those of the conformation by cold blows. In each case, the improvement lies either in the production rate of the pieces for all uses, for example in the connections, and thus in the productivity, or on the superior final quality of these pieces, or either on the lower level of investment for the manufacturer, or on a combination of these advantages. In the case of tronzado, the invention is a synthesis of known methods, previously designated by A and B, after the elimination of the disadvantages related to each of these methods: * As in method A, the client who practices the tronzado you do not have to worry about the straightening of the bars, or, at the same time, the customer who practices the EDM does not have to worry about the presence of remaining coil in the case of thread breakage. * Nevertheless, as in method B, the thread supplier does not have to put heavy media into operation. In effect, the pre-straightening means put into operation are easily integrated at the end of the drawing line without reducing the productivity of the drawing, nor increase production costs, and on the other hand these constitute a much smaller investment than the industrial straighteners. Overall, if a pre-straightening means is necessary in the thread producer, on the contrary, it is no longer necessary to have a straightening machine for each lathe, which constitutes a considerable economy. In this way, the straightening operation can be decomposed in two stages: one of pre-straightening, carried out by the thread producer. This operation is carried out at high speed (typically, from 4 to 8 meters / second), compatible with the high drawing speeds, necessary to ensure high productivity. one of finishing straightening, which is optional, carried out by the user. This finishing straightening, careful, is performed at low speed (typically 0.1 to 0.5 meter / second), allowing a good quality of straightening with a low cost device. In this case, a slow speed does not constitute an impediment, since the straightening is carried out in masked time, the limiting factor being located at the machining level, on the contrary, as already underlined, the economic character of the straightening device it is imperative, even equipping the tronzado in each of its lathes, of a device of this type.In the worst case, according to the invention, the straightening operation, optimizes the pair quality / productivity, allowing the involved, the thread producer and the user, work at their respective characteristic speeds.As other advantages of the invention, it should be noted: * the possibility of using threads of much more mechanical strength, which have a better ability to bucking than the more "soft" threads, the chips are thinner (0 »05 mm instead of 0.5 mm typically) and easier to evacuate. * the almost elimination of the risks of rupture at the time of shipment. of the yarn, since there is no longer plastic deformation of the yarn, when on average, it has been observed in the prior art, a break per barrel of 250 kg of yarn. * The sharp decrease in vibrations, related to a minor twist, also involves a lower rate of breakage of tools: with the invention, the consumption of wicks is passed from a wick for 200 kg of yarn to a wick for 5000 kg of yarn .

* The possibility of feeding the machines for processing or forming the yarn from barrels located, no longer at the foot of the machines as in the prior art, but in a place away from these machines, for example, a storage room from which the ducts will direct the thread to the processing machines, because, like that which is known by others, a pre-straightened thread can circulate in a duct. A configuration of this type decreases the dimensions of each machine, reduces the circulation and maintenance of the barrels, and the risks of accidents or crashes. * the possibility of conditioning barrels of "hard" or "brittle" alloys. These alloys are badly intended, or in no way, to the conditioning in barrels, either because they have a high yield strength, because they require a very important effort to achieve elastic control, at the time of the camber preceding the placement in barrels , and at the time of straightening after the winding, either because they present a zone of very narrow plastic deformation, in such a way that a limited plastic deformation, such as a cambering or a re-straightening, sufficient to locally exceed the limit of elongation to the rupture and in this way cause repeated breaks of the thread. In this way, the pre-stressed alloy threads of Cu-Sn-Pb composition ("lead bronze"), and Cu-Zn-Ni-Mn-Pb ("alpaca to lead") have thus been able to be conditioned in barrels In the case of EDM, the advantages provided by the invention are equally important: * by eliminating the thermal or mechanical treatments of the straightening, * the possibility of a higher unit weight and thus of a greater autonomy, the weight of the Thread per bobbin is typically 5 kg, while the weight per barrel is not limited. * the elimination of the coils, which need motorized rewinders, and which, after a limited number of rotations, must be destroyed, while the barrels can be reused a large number of times. Finally, whatever the use of the pre-straightened yarn according to the invention, the applicant has observed that the conditioning according to the invention will allow, at an equal barrel size, to multiply by two the amount of yarn, in relation to the packaging of traditional barrel yarn (500 kg according to the invention instead of 250 kg according to the prior art). This is because, in traditional conditioning, the turns must be relatively "aerated" in order to limit the problems of entanglement to the winding, while all the turns are completely blocked and with a compact stack in the case of the invention .

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (7)

1. A conditioning process for obtaining a pre-straightened metallic wire in a cylindrical barrel, characterized in that: a) the strand to be straightened passes through a series of straightening rollers, being dragged by a large-diameter winch that retains its straightness, b) after that said yarn undergoes torsion when crossing two pairs of non-motorized rollers, located in two perpendicular and animated planes of a rotation movement around the yarn, c) the yarn, guided by a drum that has the same movement of rotation, is deposited spiral in the bottom of the barrel, d) the barrel descends as it is filled, so that the interval between the free surface of the wire and the base of the drum remains constant, the wire being a copper alloy, of smaller diameter to 6 mm, and of mechanical strength comprised between 400 MPa and 750 MPa, so that said winding wire is rectilinear, with a twist per meter less than 5 mm, and can feed a cutting machine.

2. The method according to claim 1, characterized in that the copper alloy is a brass.

3. The conditioning process in order to obtain a pre-straightened metallic wire in a cylindrical barrel, characterized in that: a) the strand to be straightened passes through a series of straightening rollers, being dragged by a large diameter winch that retains its straightness, b) after said yarn undergoes torsion when passing through two pairs of non-motorized rollers, located in two perpendicular and animated planes of a rotation movement around the yarn, c) the yarn, guided by a drum having the same rotation movement, it is spirally deposited at the bottom of the barrel, d) the barrel descends as it is filled, in such a way that the interval between the free surface of the wire and the base of the drum remains constant, the wire being a wire for electroerosion comprising externally a layer of Cu-Zn alloy, with a diameter between 0.15 mm and 0.35 mm, and of mechanical strength between 500 MPa and 1100 MPa, m A winding thread that is rectilinear, with a twist per meter less than 30 mm.

4. The method according to any of claims 1 to 3, characterized in that, in order to avoid the risks of corrosion under tension of the wire, said barrel is a hermetic barrel, and possibly contains other means (desiccant bags, products susceptible to fix the ammonia, protective products that are adsorbed on the surface of the yarn) to avoid these risks.

5. The use of a barrel preparation obtained according to any of claims 1 to 2 or according to claims 1 to 2 and 4, characterized in that it is for feeding directly from wire the processing machines, in particular lathes and tronzadores, and tools of cold blow.

6. The use according to claim 5, characterized in that the wire is a steel or non-ferrous alloy wire.

7. The use of a barrel conditioning, obtained according to claim 3, or according to claims 3 and 4, to feed wire a EDM machine.