FR2729373A1 - PACKAGING IN FUT OF PRE-DRESSED COPPER ALLOY WIRE - Google Patents

Abstract

A pre-straightened metal wire consisting of a copper alloy and having a diameter of less than 6 mm and a mechanical strength of 400-750 MPa is packaged in a cylindrical drum in such a way that, when it is unwound, the wire is straight, with a sag of less than 5 mm per metre, and can be fed directly to a bar turning machine.

Description

PACKAGING IN FUT OF PRE-DRESSED COPPER ALLOY WIRE
FIELD OF THE INVENTION
The invention relates to the packaging of pre-dressed copper alloy wires, in the form of barrel crowns, and for uses which may require, in particular, straightening of the wire before use.

The generic generic “wire” will be the only one used in the following to designate all of the long deai-products available under strong crowns, even those of non-circular section.

STATE OF THE ART
We already know the packaging of pre-erected steel wire to feed the autosatic welding tachines.

In current welding machines, the wire is fed continuously through a sheath. To increase autony nachines, the wire is packaged in 250 kg drums. By pr * - drawing the wire before the ease in barrels, we obtain during the unwinding, a product without residual spiral or left. This allows, on the one hand to limit the friction of the wire in the sheath, and on the other hand to guarantee the straightness of the portion of free wire at the welding point (the "stick-out" - length about 30 mm) .

Pre-dressing is obtained as follows (see Figure 1): - the wire unwound from a reel, passes through a series of dresser rollers, and is driven by a large-diameter capstan retaining its straightness, - then two pairs of non-motorized rollers, located in two perpendicular planes passing through the axis of the wire and rotated around the wire, give the latter a twist. The wire is then guided by a drum until its spiral deposition in the bottom of a drum, - the drum descends 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 filling the barrel, a plastic washer is applied to the upper turn of the wire, which is attached to the bottom of the barrel by means of an elastic band, which keeps the product in place.

This technique is applied to wires for welding in highly hardened steel, of mechanical strength typically between 600 and 1200 N / 2 and of diameter ranging from 0.8 to 1.6 mm.

The pre-dressing technique allows the pre-erected wire to slide correctly in a sheath of several tens of meters long, which makes it possible to align a mobile welding station from a heavy wire storage unit, which it remains fixed.

PROBLEM
The invention aims to improve notably the current technology of micro-turning of semi-finished products in copper alloy, notably brass.

In bar turning, there are two types of machines or methods - those where the machining is carried out notas by a rotating tool, the material being fixed, - those where the fixed tool applied to a rotating material, against for example described in patent application WO 81/01378.

To ensure optimum precision of high speed machining, it is desirable that the material is in rotation, the tool remaining stationary. This requires that the material is in the form of sections of relatively short length (generally 3 to 4 m) and sufficiently straight so that they can be rotated.

To constitute these sections, also designated under the dull "bar", one usually proceeds according to one or the other of the two following methods:
Method A: Bars are made by the wire producer using straighteners.

The micro-turning machine is then combined with a "bar tank" called wesbarreurw intended for supplying the micro-cutting tool with bars.

This technique has drawbacks: * due to the existing technology of bar feeders and turning lathes, the straightness of the bars must be perfect, otherwise the bars get stuck in the bar feeder, or else they cause vibrations during ease rotation, source of unacceptable geoaetric defects on machined parts.

To ensure perfect straightness of the bars, the producer of brass bars must use specific relatively costly wire dressing machines (straighteners), and moreover the dressing rate is significantly lower than that of wire drawing or drawing, this which greatly reduces manufacturing productivity. For these two reasons, this method has high costs.

* the capacity of the bar feeders being limited to a few tens of bars, the autonomy of the towers 1 is also consequently. It is therefore necessary to regularly recharge the hoists after a few hours, which penalizes productivity at the bar turner.

* in view of the space requirements during the transport and handling of the bars, their length is limited (about 4m). This penalizes the ease of use, because there is, for each bar used, a drop of about 200 mm, or 5% of the length.

Method B:
The producer packages the yarn in crowns, the unit weight of which is generally 250 kg. The crowns are placed in cylindrical cardboard barrels, iron at the base by a wooden base, and at the top by a low lid in wood or metal.

To make these crowns, the producer of brass wire exerts on the wire, just before packaging in barrels, a slight plastic deformation intended to give it a natural curvature, with a diameter close to that of barrels. This is necessary so that the positioning of the turns is carried out regularly, in order to eliminate the risks of tangling during handling and transport, and therefore the risks of jamming of the wire during the unwinding.

At the bar turner, the wire is extracted from the barrel using a special reel, then it passes through a swirling frame with keys which straightens it, and it is then cut to length by shears. Bars are thus obtained which can also be rotated for bar turning.

Compared to method A, method B has the following advantages: * the preparation of each bar is carried out in mask time, during the turning of the previous bar. Thus, dressing, much faster than bar turning, does not cause any loss of productivity.

* a drum contains approximately 10,000 s of wire, representing several thousand bars. Thus, the tower autoncaie is multiplied by a factor of the order of 100 compared to that of method A.

 * the bar length limit is no longer linked to transport and packaging requirements, but to the space available in the bar turning workshop. It is thus possible, at least theoretically, to machine longer bars, and thus to reduce implementation (drop rate less than 5%).

Method B has therefore found increasing favor among micro-turners, in particular those who work on large series where the need for high productivity is imperative.

However, method B has the following disadvantages: a) unlike method A, where the producer of brass wire is equipped with a limited number of straighteners to produce bars, the bar turner must install a large number (a straightener for each round). The dressers must therefore be of a relatively simple model, except to represent an extremely high investment.

b) however, due to the use of "simple" dressers, the dressing is much less careful than in method A, the bars which may have an arrow arrow of several centimeters. The turners partially remedied this defect by modifying the tower feeder: the bar being machined is enclosed in an oil-filled sheath. The oil bath allows the bar to self-center during rotation. straightness of the bars is not perfect, the precision of bar turning is not optimal (range of 10 ul: nominal value + 10 m, nominal value -10pa, or nominal value +/- 5 PI as appropriate).

c) method B is permitted for wires which are relatively easy to dress, since the wires of high diameter and high mechanical strength cannot be trained properly.

Groins, method B cannot be applied to wires with a dianeter greater than 3 se, or even less in the case of wires with high mechanical strength (typically of the order of 700 N / mm2.

d) method B, when machining parts of great length, and in particular when the machining is obtained by rotation of the tool, leads to parts which may have too much residual deflection, that the dressing device n 'was unable to eliminate ("the memory of brass" for those skilled in the art): arrow of the order of 0.15 mm for a piece 40 mm in length, while the tolerance is 0.07. In this case, it is necessary to submit beforehand the wire crown to an additional heat treatment consisting of a partial recrystallization of the alloy, which causes a significant additional cost. This heat treatment, combined with method B, allows and obtain very long pieces (40-) with an arrow of 0.05 r.

The invention aims to propose a packaging of copper alloy wire, typically brass, which eliminates the drawbacks previously indicated for processes A and B, in particular those listed under a) to d) for process B, namely : 1) removal of a straightening machine per turn, 2) obtaining a higher precision turning at higher speed, 3) Blargisserent of the range of usable threads towards the high diameters and / or the faded mechanical resistances.

4) elimination of the heat treatments necessary to manufacture parts of great length.

Furthermore, the packaging according to the invention, which solves the problems encountered at the bar turner, does not significantly increase the constraints at the yarn producer.

DESCRIPTION OF THE INVENTION
A first object and of the invention is constituted by a cylindrical barrel packaging of pre-erected metal wire characterized in that said wire is a copper alloy, of diameter less than 10 -, and of mechanical strength between 400 MPa and 750 MPa, so that 9 c that said unwound wire is straight, with an arrow less than 5 mm per meter, and can directly feed a turning machine.

According to a second method of using this first object, said unwound wire, rectilinear with an arrow less than 5 - feeds a bar turning machine provided with a straightener.

In this case, at the exit from the straightener, the wire has an arrow less than 0.5 m / m, a level which may be necessary for high precision machining.

As a copper alloy, brass is preferred, taking into account the use (bar turning) which is made of the pre-erected wire of this first object, but Corsican this will be indicated below, other alloys more " hard "or more" brittle "than brass are usable.

The upper limits of diameter and mechanical resistance of the pre-erected wire result in particular from the need to limit the energy e sagasinée by the pre-erected wire during the setting in barrel. Beyond a certain threshold, the stored energy would be too important to be contained by the frame of a barrel, and could even present a danger in the event of a barrel rupture, leading to the total release of constraints.

The Applicant was surprised to find that a packaging of thread according to the invention made it possible to choose: * either to feed bar turning machines according to method B without using the straightening machines with rotating frame, which constitutes a considerable simplification of the adjustment and maintenance of these machines, and a significant reduction in investment, * either to supply bar turning machines according to method B using the straightening machines with rotating frame, which allows on the one hand, widening the range of wires usable according to method B by authorizing the use of wires 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 to considerably improve the machining precision with a range of 5 pa: nominal value + 5pm, nominal value -5ps, or nominal value +/- 2.5 depending on the case, and which also allows reduce tool wear and the frequency of breakage of wicks: the average quantity of brass turned per lick thus went from 2000 kg to 5000 kg.

In all cases, the invention solves a problem of productivity and / or level of quality of great economic importance. Furthermore, the solution to this probe could not be anticipated or suggested by the loyalties mentioned in the prior art and relating to the conditioning of steel wires for welding.

Indeed, on the one hand, for the ho-e of the profession of the turning of brass, the wire dressing is perceived Corsican an essential operation, inseparable from the machining according to close B. The possibility of eliminating the wire dressing cannot come to the mind of this skilled person.

On the other hand, this person skilled in the art is different from that of welding, and a means known in the field of welding on steel wires cannot constitute a teaching of gEntrel or a teaching of a neighboring field for 1 'ho-e of the profession of bar turning of brass wires.

Finally, given the difference in the problem to be solved, even if the professional in bar turning had known the use of pre-drawn steel wire in the welding field, he could never have imagined that the means used for a steel wire to slide in a sheath are sufficient to allow the formation of a bar by eliminating the wire straightening.

Another object of the invention consists of the packaging in a barrel of press metal wire characterized in that said wire is a wire for EDM generally comprising an outer layer of Cu-Zn alloy, with a diameter between 0.15 mm and 0.35 -, and of mechanical strength between 500 MPa and 1100 MPe, so that the said unwound wire is straight, with an arrow less than 30 mm per meter.

The structure of wires for EDM is described in numerous patents, for example in European application No. 526 361-A1 to the applicant's noe.

The Applicant has found that the solution found with the wire for bar turning also applies to the wire for EDM. In this case, the technical problem to be solved is as follows: when there is a break in the wire, the wire must thread automatically, so that EDM can continue without the need for manual intervention .

For this, the EDM wire must not have any memory effect which means that the end of a wire initially in coil or in crown, tends to form a loop winding on itself.

Thus, after breakage of the wire, the end of the wire retains its Corsican trajectory if there had been no breakage of the wire.

Until now, the problem has been solved by heat treating the wire and / or by straightening it before winding.

The invention allows the elimination of these treatments, and avoids the use of coils, with the constraints linked to their use.

On the one hand, the use of spools limits the quantity of thread per spool (standard weight of 5 kg), even if this quantity tends to increase. On the other hand, above 15 kg, the coils must be mounted on a motorized reel, which generates both additional costs and vibrations incompatible with the precision of EDM machining.

Finally, the problem of recycling these plastic coils arises with increasing acuity. A coil cannot be used more than 3 or 4 times at most, given the very important constraints to which it is subjected during winding and which tend to dislocate it, then it must be destroyed.

The barrel packaging according to the invention provides a particularly elegant solution to these problems: * drums of significant unit weight can be used without motorized reel, * the barrels can be reused a large number of times, since the packaging operation does '' does not cause significant mechanical constraints, * the drums can be made of recyclable materials cuts the cardboard and steel.

DESCRIPTION OF THE FIGURES
FIG. 1 represents a diagrammatic section of a device for pre-dressing a wire to be pre-dressed (1) which successively comprises: * a system for unwinding (4) a wire for pre-dressing (1), * a small capstan motorized (5) * deur series of flat dresser rollers, 90- to each other, non-motorized, * a large diameter capstan (760) (7), * two pairs of non-motorized rollers, 90- 'from each other and rotated around the wire, * a drum (16) driven in a rotary movement, allowing the pre-erected wire (2) to be guided in the fat ( 3), and the formation of a crown (15) of pre-erected wire, * a barrel (3) and a means of lowering the barrel (9) so that the bottom of the drum (16) is always just above the crown (15) of pre-erected wire formed in the barrel, and by its own diameter, substantially imposes the internal diameter of said crown (15).

FIG. 2 represents in section the final packaging of the crown (15) of pre-erected wire, so that there is no tangling of the turns of wire during transport:
A plastic washer (10) is held pressed against the upper part of the crown (15), thanks to hooks (11), an elastic band (12), and a rigid rod (13) hooked by a ring (14) at the bottom barrel (3).

OTHER OBJECTS OF THE INVENTION
Another object of the invention is, as shown in FIGS. 1 and 2, the preparation of a prepress wire packaging (2) described above in which, so as to obtain a metal wire pre-erected in a cylindrical barrel (3), in which, a) the pre-dressing wire (1) passes through a series of dressing rollers (6), being driven by a large diameter capstan (7) retaining its straightness over the wire, b) then said wire undergoes a twist crossing two pairs of non-motorized rollers (8) located in two perpendicular planes and rotated around the wire, c) said wire (2), guided by a drum (16) of the same movement of rotation, is deposited in a spiral in the bottom of the barrel (3), d) said barrel (3) descends as it fills so that the interval between the free surface of the wire and the base of the drum remains constant.

The Applicant has therefore adapted a known process & the preparation of pre-dressed wire according to the invention.

In the case where the metal wire is made of brass, the invention makes it possible to ensure hermetic storage of the pre-erected wire crown (15), which avoids the risks of corrosion under stress of the wire (season cracking in English), in a humid atmosphere or in the presence of ammonia. Other means can also be used to further limit these risks: placement of desiccant sachets, or products capable of fixing the ammonia, or protective products adsorbing on the surface of the wire, insulation of the drums making it possible to limit the impact of variations in ambient temperature.

Other objects of the invention are constituted by the use of a packaging of pre-erect wire according to the invention to directly supply wire to machining machines, in particular lathes and lathe cutters, or form by cold striking, and by the use of a pre-erected wire packaging according to the invention to supply wire to an electroerosion machining machine.

The invention also includes the use of a conditioner of any pre-erected metal wire, whether it is steel wire, or a non-ferrous alloy other than copper, for directly feeding wire into machines for machining, in particular lathes and lathe cutters, or cold-forming machines. Indeed, the Applicant has been able to verify the applicability to steel wire, of the ooncept developed with copper alloys, such as brasses, and explained previously.

EXAMPLES OF REALIZATION
EXAMPLE 1
A crown (15) of pre-erected wire (2) has been prepared. This wire had the following characteristics: - corposition: brass at 36% Zn and 3% Pb - diameter: 1.825 - - mechanical resistance: 620 MPa
We used the device shown in Figure 1.

Corsican dresser (6) was used two pairs of dresser rollers 90- from each other.

The running speed of the wire was 250 m / min and the speed of rotation of the pair of rollers (8) and the drum (16) was 130 revolutions / sin.

This wire was packed in drums (3) of 250 kg useful, Corsican shown in Figure 2.

We tested on a "TORNOS" (R) type lathe the pre-trained wire (2) obtained, with and without the use of a rotating frame dresser: - without the use of a rotating frame, bars of 4 were obtained m presenting 4 - of arrow per meter. This deflection value is substantially that obtained with a bar obtained, according to method B, after a dressing operation on a frame turning with keys of a wire of the same nature and geometrical characteristics.

- After using a rotating frame, bars of 4 were obtained having a maximum value of 0.5 mm of deflection per meter, which corresponds substantially to a level of straightness of bars obtained according to method A.

The lower the deflection per meter, the less vibration there is when rotating the bar at high speed, and the greater the precision of the machining, or, optionally, the faster the machining speed.

Typically, the accuracy commonly accessible with a spreader bar close to 4 mm / m is 10 pu, while ocelle accessible with a spreader bar 0.5 mm / m or less is of the order of 5 µm.

Similarly, if we consider the machining speed & constant precision, the productivity gain is around 15% when we go from a 4 / - arrow bar & a 1 I arrow bar or less.

The Applicant has carried out numerous other tests by varying the nature of the copper alloy and its geometric or mechanical characteristics, the machining techniques, and the geometry of the parts machined.

In particular, she observed that, in the case of the machining of very long pieces (typically 40), the pre-braided wire according to the invention made it possible to avoid the thermal treatment of the crowns necessary to erase "the memory of brass" , and to obtain, without heat treatment, parts with a deflection of 0.05 mm, for a tolerance of 0.07 mm.

The Applicant has also used the pre-drawn wire according to the invention to manufacture parts, no longer by machining, but by cold stamping. It also observed that, in the case of very long pieces, typically from 30 to 50 -, the problem of deflection also arises, due to the residual deformation caused during the bending preceding the placing in barrels, and can lead to discard of the final part, despite repeated adjustments of the dressing device.

In this case also, the pre-erected wire of the example made it possible to considerably limit the value of the arrow.

A typical example of parts obtained by cold stamping, taking into account tight geometrical tolerances, are the anodes of alkaline batteries.

The tests also focused on wires of different diameters (tests with brass wires of 3 and 6 - in diameter), and of different mechanical strengths: "hard" or brittle alloys such as bronze were successfully tested lead (Cu-Sn-Pb), or lead nickel silver (cu-
Zn-Ni-Mn-Pb), within the limits as they appear in claim 1.

These limits result from the need to obtain a deflection of less than 5 me / m for the bar subjected to rotation for machining (method B).

If wires that are too large and / or too strong are used, this results in a residual deflection greater than this limit value of 5 mm / m of bar.

EXAMPLE 2
We prepared a crown (15) of pre-erected wire (2) for electrical erosion. This wire, conforming to that described in the example of European application 0 526 361-A1, had the following characteristics: - composition: Cu-Zn37 - diameter: 0.25 mm - mechanical resistance: 910 MPa
This wire according to the invention was tested on an EDM machine, compared to a standard wire. A standard wire includes a thermal or mechanical dressing treatment before winding.

The barrel wire according to the invention behaved in a manner similar to that of the coil wire, heat treated or drawn up mechanically, according to the prior art.

ADVANTAGES OF THE INVENTION
The invention solves problems encountered with several types of users and in several types of trades: those of bar turning and those of electro-erosion, and also those of nise in shape by cold striking.

In each case, the improvement relates either to the rate of manufacture of parts for all uses, for example the connector technology, and therefore productivity, or to the superior final quality of these parts, or to the lower level of investment. to make them, or a combination of these advantages.

In the case of bar turning, the invention is a synthesis of the known methods, previously designated by A and B, after eliminating the drawbacks linked to each of these methods.

* copy in method A, the client practicing bar turning does not have to worry about the dressing of the bars, or, at the same time, the client practicing electro-krosion does not have to worry about the presence of a sticky whorl wire breakage.

* however, as in method B, the yarn supplier does not have to use heavy resources. In fact, the pre-dressing means used are easily integrated at the end of the wire drawing line without reducing the productivity of the wire drawing, or increasing the production costs, and moreover they constitute a much lower investment than industrial dressers.

Overall, if a pre-dressing means is still necessary at the yarn producer, on the other hand, it is no longer necessary to have, at the bar turner, a dresser for each turn, which constitutes a considerable saving.

As other advantages of the invention, it is necessary to indicate: * the possibility of using wires of greater mechanical resistance, which have a better aptitude for turning than the "softer" wires, the shavings being finer (0.05 - instead of 0.5 - typically) and easier to evacuate.

* the virtual elimination of the risks of breakage during the straightening of the wire, since there is no longer any plastic deformation of the wire, whereas on average, it was observed in the prior art, a rupture by barrel of 250 kg of wire.

 * the strong reduction in vibrations linked to a lesser deflection, also leads to a lower rate of tool breakage with the invention, the consumption of wicks went from 1 wick for 2000 kg of wire to 1 wick for 5000 kg of wire.

* the possibility of feeding the machining or wire shaping machines from drums located, not at the foot of the corme machines in the prior art, but in a place remote from these machines, for example, a storage room from which sheaths direct said wire towards the machining machines, since, as was otherwise known, a pre-erected wire can circulate in a sheath.

Such a configuration reduces the size of each machine, reduces the circulation and handling of drums, and the risk of accidents or shocks.

* the possibility of packaging in barrels 'hard' or 'brittle' alloys. These alloys are ill-suited, or not at all, to packaging in barrels, either because they have a high elastic limit and they require a significant sorted effort to reach the elastic range, during the bending preceding the placing in barrels, and during straightening following the unwinding, either because they have a very narrow plastic deformation range, so that a limited plastic deformation, such as bending or straightening, is sufficient to locally exceed the elongation limit at breaking and thus causing repeated breakage of the wire.

Thus, pre-straightened wires made of a Cu-Sn-Pb ("lead bronze"), and Cu-Zn-Ni-Mn-Pb ("lead nickel silver") corposition alloy could thus be packaged in barrels.

In the case of electro-erosion, the advantages provided by the invention are also important: * by eliminating thermal or mechanical dressing treatments, * possibility of a higher unit weight and therefore greater autonomy, the weight of wire per spool being typically 5 kg, while the weight per drum is not limited.

* elimination of the reels, which require motorized reels, and which, after a limited number of rotations must be destroyed, while the drums can be reused a large number of times.

Finally, whatever the use of the pre-erected wire according to the invention, the Applicant has observed that the packaging according to the invention makes it possible, for equal barrel size, to double the quantity of wire, relative to the packaging traditional barrel wire (500 kg according to the invention instead of 250 kg according to the prior art). This is due to the fact that, in traditional packaging, the turns must be relatively 'ventilated' so as to limit the problems of entanglement during reeling, while all the turns are entirely blocked and with a compact stack in the case of the invention.

Claims (9)

1. Packaging in cylindrical barrel of pre-erected metal wire characterized in that said wire is a copper alloy, of diameter less than 6 mm, and of mechanical strength between 400 MPa and 750 MPa, so that said wire unwound or straight, with an arrow per meter less than 5 rpm, and can directly feed a turning machine. 2. Conditionnexent according to claim 1 wherein said copper alloy is brass. 3. Packaging in cylindrical barrel of pre-erected metal wire characterized in that said wire is a wire for EDM externally comprising an alloy layer Cu-Zn, of diameter between 0.15 - and 0.35 sa, and of mechanical resistance between 500 MPa and 1100 MPa, so that said unwound wire is straight, with an arrow per meter less than 30 mm . 4. Packaging according to any one of claims 1 to 3 wherein, so as to avoid the risks of stress corrosion of said wire, said barrel is a sealed barrel, and optionally contains other means (sachets, products capable of fix the aoniac, absorbent protective products on the surface of the wire) to avoid these risks. 5. Preparation of a package according to any one of claims 1 to 4 in which, so * obtain a pre-erected wire in a cylindrical barrel, in which, a) the wire to pre-dress through a series of dresser rollers , by being driven by a large diameter capstan retaining the straightness of the wire, b) then said wire is subjected to a twist crossing two pairs of non-motorized rollers located in two perpendicular planes and driven in a rotational movement around the wire, c ) said wire, guided by a drum having the same rotational movement, is deposited in a spiral in the bottom of the barrel, d) said barrel descends as it fills so that the interval between the free surface of wire and the base of the drum remains constant. 6. Use of packaging according to any of. Claims 1, 2 and 4 for directly supplying wire to machining machines, in particular lathes and lathe-turning machines, or cold striking tools. 7. Use of a packaging according to claim 3 for supplying wire to an electroerosion machining machine. 8. Use of a cylindrical barrel packaging of pre-erected metal wire to feed directly into the wire of the machining machines, in particular lathes and lathe cutters, cold striking tools. 9. Use according to claim 8 wherein said metal wire is a steel wire or a non-ferrous alloy.