|Title of Invention||
PACKAGING PROCESS CAPABLE OF PROVIDING A PRE-STRAIGHTENED METAL WIRE IN A CYLINDRICAL DRUM
|Abstract||The packaging process capable of providing a pre-straightened metal wire in a cylindrical drum said wire is a copper alloy having a diameter smaller than 6 mm and mechanical strength of between 400 MPa and 750 MPa in such a way that said unwound wire is rectilinear with deformation of less than 5 mm per metre and can supply a trimming machine directly.|
FIELD OF INVENTION
The invention relates to the packaging process capable of providing a pre-straightened metal wire in a cylindrical drum when the said wire is a copper alloy wire in the form of coils for uses which may necessitate, in particular, straightening of the wire prior to use.
The generic term "wire" will only be used hereinafter to designate the assembly of long semi-finished products which can be delivered in the form of coils, even those of non-circular section.
STATE OF THE ART
The packaging of pre-straightened steel wire for the supply of automatic welding machines is already known. In current welding machines, the wire is supplied continuously through a sheath. To increase the autonomy of machines, the wire is packaged in 250 kg barrels. By pre-straightening the wire before placing it in barrels, a product without residual or awkward turns is obtained when unwinding. This allows the friction of the wire in the sheath to be limited on the one hand and allows the straightness of the free portion of wire at the weld point (the "stick-out" - having a length of about 30 mm) to be guaranteed on the other hand.
Pre-straightening is achieved in the following manner (see figure 1):
- the wire unwound from a reel passes through a series of straightening rollers and is driven by a large-diameter capstan which allows the wire to maintain its straightness;
- two pairs of non-motorised rollers located in two perpendicular planes passing through the axis of the wire and set into a rotational movement round the wire apply torsion to the wire.
The wire is then guided by a drum until it is deposited in a spiral in the bottom of the barrel,
- the barrel,descends as it is filled so the space between the
free surface of the wire and the base of the drum remains
- after filling of the barrel, a plastic washer is applied to the
upper turn of the wire and is attached to the bottom of the
barrel by means of an elastic band, allowing the product to be
held in position.
This art is applied to markedly work-hardened steel welding wires having mechanical strength typically between 600 and 1,200 N/mm2 and a diameter ranging from 0.8 to 1.6 mm.
The art of pre-straightening allows the pre-straightened wire to slide correctly in a sheath having a length of several tens of metres, allowing a movable welding station to be supplied from a heavy wire storage unit which itself remains stationary.
The invention aims to improve, in particular, the current
technology of micro-trimming of semi-finished products made of
copper alloy, in particular brasses. There are two types of
machine or method in micro-trimming:
Type 1 : those where machining is carried out, in particular, by
a rotating tool, the material remaining stationary,
Type 2 : those where the stationary tool is applied to a rotating
material as described, for example, in the Patent Application
To ensure optimum precision in high-speed machining, it is desirable for the material to be in rotation, the tool remaining stationary. This means that the material must be in the form of relatively short sections (generally of 3 to 4 m) and sufficiently straight to be set into rotation.
To make up these sections, also known by the name "rod", one or other of the following two methods is usually adopted;
The rods are produced by the wire manufacturer using straighteners. The micro-trimming machine is thus equipped with a "rod reservoir" known as a "rod feeder" intended to supply the micro-trimming tool with rods.
This technique has drawbacks:
* Owing to the existing rod feeder and trimming lathe technology,
the straightness of the rods should be perfect, otherwise the
rods will jam in the rod feeder, or they will cause vibrations
when being set into rotation, these vibrations being a source of
unacceptable geometric defects on the machined parts.
To ensure perfect straightness of the rods, the brass rod manufacturer has to use relatively expensive specific wire-straightening machines (straighteners) and, furthermore, the rate of straightening is much lower than that of extrusion or drawing, greatly reducing productivity. For these two reasons, this method is associated with high costs.
* As the capacity of rod feeders is limited to a few tens of rods, the autonomy of the lathes is consequently also limited. It is therefore necessary to re-load the rod feeders regularly after a few hours, adversely affecting the productivity of the trimmer.
* Owing to the requirements concerning bulk during transportation and handling of the rods, the length of the rods is limited (about 4 m). This adversely affects implementation because, for each rod used, there is a loss of about 200 mm, that is 5% of the length.
The manufacturer packages the wire in coils of which the unit
weight is generally 250 kg. The coils are placed in cylindrical cardboard barrels, closed at the bottom by a wooden base and at the top by a, removable wooden or metal lid.
To make up these coils, the brass wire manufacturer exerts on the wire, just prior to packaging in barrels, slight plastic deformation intended to give it natural curvature having a diameter close to that of the barrels. This is necessary so the turns are positioned evenly to eliminate risks of entanglement during handling and transportation and therefore risks of jamming of the wire when unwinding it.
At the trimmer, the wire is extracted from the barrel using a special unwinder, then it passes into a rotating stand with keys which straightens it and it is then cut to length by shears. Rods which can be set into rotation for trimming are thus obtained.
Method B has the following advantages over method A:
* Each rod is prepared in masked time, during the trimming of the previous rod. Therefore, straightening which is much faster than trimming does not lead to a loss of productivity.
* A barrel contains about 10,000 m of wire representing several thousand rods. The autonomy of the lathes is therefore multiplied by a factor of about 100 relative to that of Method A.
* The rod length limit is no longer linked to the requirements of transportation and packaging but to the space available in the trimmer's workshop. It is thus possible, at least theoretically, to machine longer rods and thus to reduce the amount used (wastage less than 5%).
Method B has therefore found increasing favour with micro -trimmers, in particular those carrying out mass production where the need for high productivity is imperative.
However, method B has the following drawbacks:
a) Contrary to method A where the brass wire manufacturer is equipped with'a limited number of straighteners to produce rods, the trimmer has to install a large number of them (one straightener for each lathe). Straighteners therefore have to be of a relatively simple model otherwise they necessitate extremely high investment.
b) However, owing to the use of "simple" straighteners, straightening is much less careful than in method A and the rods commonly have a deformation of several centimetres. Trimmers have partially overcome this defect by modifying the lathe supply device: the rod being machined is enclosed in an oil-filled sheath. The oil bath allows the rod to centre itself during rotation. However, as the straightness of rods is not perfect, the precision of trimming is not optimal (range of 10 urn: nominal value + 10 urn, nominal value - 10 urn or nominal value +/- 5 μm as the case may be).
c) Method B is limited to wires which are relatively simple to straighten as large-diameter wires having high mechanical strength cannot be straightened correctly. Thus, method B cannot be applied to wires having a diameter greater than 3 mm, or even less in the case of wires having high mechanical strength (typically of the order of 700 N/mm2) .
d) The use of wire when machining very long parts and, in particular, when machining is achieved by rotation of the tool, leads to parts having excessively great residual deformation which the straightening device has not been able to eliminate ("the memory of the brass" for a skilled person): deformation of the order of 0.15 mm in a 40 mm long part whereas the tolerance is 0.07 mm. This problem arises on both types of trimming machine: those where the material remains stationary (type 1) and those where the material rotates (type 2) . In this case, it is necessary to subject the coil of wire to a
preliminary complementary heat treatment involving partial recrystallization of the alloy which increases costs in a manner which is not negligible. This heat treatment allows very long parts (40 mm) to be obtained with a deformation of 0.05 mm.
The object of the invention is to propose a packaging for copper alloy, typically brass, wire which overcomes the aforementioned drawbacks of methods A and B, in particular those enumerated in a) to d) with regard to method B, that is:
1) elimination of straightening with a lathe,
2) obtaining of a cut of higher precision or at higher speed,
3) widening of the range of wires which can be used to large diameters and/or high mechanical strengths,
4) very significant reduction or elimination of the residual deformation of very long parts, without preliminary heat treatment.
Furthermore, the packaging according to the invention, which solves the problems encountered by the trimmer does not substantially increase the constraints for the wire manufacturer.
DESCRIPTION OF THE INVENTION
The invention firstly relates to the packaging of pre-straightened metal wire in a cylindrical barrel characterized in that said wire is a copper alloy having a diameter smaller than 10 mm and mechanical strength of between 400 MPa and 750 MPa in such a way that said unwound wire is rectilinear with deformation of less than 5 mm per metre and can supply a trimming machine directly.
According to a second condition for use of this first subject, said unwound wire, which is rectilinear with deformation of less than 5 mm, supplies a trimming machine equipped with a straightener. In this case, on leaving the straightener, the wire has a deformation of less than 0.5 mm/m, a level which may
be necessary for high precision machining.
Brass is preferably selected as copper alloy owing to the use (trimming) which is made of the pre-straightened wire of this first subject, but other alloys which are harder or more brittle than brass can be used, as mentioned hereinafter.
The upper limits of diameter and mechanical strength of the pre-straightened wire result, in particular, from the need to limit the energy stored by the pre-straightened wife as it is being placed in a barrel. Beyond a certain threshold, the energy stored would be too great to be contained by the reinforcement of a barrel and could even present a danger in the event of breakage of a barrel, leading to the total liberation of stresses.
The applicants have surprisingly found that a wire packaging according to the invention made it possible, as desired:
* either to supply trimming machines according to method B
without using rotary stand straighteners, which represented a
considerable simplification in adjustment and maintenance of
these machines and a significant reduction in investment,
* or to supply trimming machines according to method B using
rotary stand straighteners, which allows the range of wires which
can be used according to method B to be widened while allowing
the use of wires having a larger diameter up to 10 mm instead of
3 mm and a higher mechanical strength up to 750 MPa instead of
650 MPa, on the one hand, and allows the precision of machining
to be considerably improved with a range of 5 urn: nominal value
+ 5 urn, nominal value - 5 μm or nominal value +/- 2.5 urn, as the
case may be, on the other hand, allowing the wear of tools and
the frequency of breakages of bits to be reduced: the average
quality of brass cut per bit has therefore increased from 2000 kg
to 5000 kg.
In all cases, the invention solves a problem of productivity and/or of level of quality of great economic importance. Furthermore, the solution to this problem could not be anticipated nor suggested by the means mentioned in the state of the art relating to the packaging of steel wires for welding. In fact, on the one hand, for a person skilled in the trimming of brass, the straightening of wire is perceived as an essential operation inseparable from the machining according to method B. The possibility of eliminating wire straightening would not occur to this skilled person. Moreover, this skilled person is different from a person skilled in welding, and a means known in the field of steel wire welding cannot constitute general teaching or teaching in a neighbouring field for a person skilled in the trimming of brass wires.
Finally, in view of the difference in the problems to solve, even if a person skilled in trimming was aware of the use of pre-straightened steel wire in the field of welding, he could never have imagined that the means used to enable a steel wire to slide into a sheath would be sufficient to allow the formation of a rod while eliminating straightening of the wire.
The invention also relates to the packaging of pre-straightened metal wire in a cylindrical barrel, characterized in that said wire is a wire for spark-erosion generally comprising an external layer of Cu-Zn alloy having a diameter of between 0.15 mm and 0.35 mm and mechanical strength between 500 MPa and 1100 MPa in such a way that said unwound wire is rectilinear, with deformation of less than 30 mm per metre.
The structure of the wires for spark-erosion is described in numerous patents, for example in European Patent No. 526 361-Al in the name of the applicants.
The applicants have found that the solution involving the wire for trimming also applied to the wire for spark-erosion. In this case, the technical problem to solve is as follows: when the
wire breaks, the wire should automatically follow on so spark-erosion can take place without the need for manual intervention. To this end,, the spark-erosion wire must not have any memory effect which causes the end of an initially wound or coiled wire to tend to form a loop which winds round itself. Thus, after breakage of the wire, the end of the wire maintains its trajectory as if the wire had not broken.
Up until now, the problem has been solved by subjecting the wire to a heat treatment and/or by straightening it prior to winding. The invention allows these treatments to be eliminated and avoids the use of reels with the constraints associated with their use. In fact, on the one hand, the use of reels limits the quantity of wire per reel (standard weight of 5 kg) even if this quantity tends to increase. On the other hand, beyond 15 kg, reels have to be mounted on a motorized unwinding device, leading both to excess costs and to vibrations which are incompatible with the precision of spark-erosion machining.
Finally, the problem of recycling these reels made of plastics material is becoming increasingly acute. A reel cannot be used more than three or four times at most owing to the very significant stresses to which it is subjected during winding and which tend to distort it, then it has to be destroyed.
The packaging in a barrel according to the invention provides a particularly convenient solution to these problems:
* barrels having a high unit weight without a motorized unwinding device can be used,
* the barrels can be reused a large number of times because the packaging operation does not create significant mechanical stresses,
* the barrels can be composed of recyclable materials such as cardboard and steel.
Figure 1 is a, schematic section through a wire pre-straightening device comprising a pre-straightener (1) which includes, in succession:
* an unwinding system 4 for wire to be pre-straightened 1 and its dancer 5,
* four series of seven flat straightening rollers, the second series being orientated at 90° from the first series, the third series being orientated at 45° to the right, and the fourth series at 45° to the left. Only the third series (6) has been shown in figure 1,
* a large-diameter capstan (1000 mm) 7 so as to supply a wire which is straight on leaving the capstan,
* two pairs of rollers comprising grooved cylindrical rollers mounted on the same rotating plate 8, gripping the wire and imposing counter-torsion on it by rotation of said plate,
* a drum 16 set into the same rotational movement as said plate 8, allowing the pre-straightened wire 2 to be guided in the barrel 3 and a coil 15 of pre-straightened wire to be formed,
* a barrel 3 and a means for lowering the barrel 9 in such a way that the bottom of the drum 16 is always just above the coil 15 of pre-straightened wire formed in the barrel and by its inherent diameter, imposes substantially the internal diameter of said coil 15.
Figure 2 is a section through the final packaging of the coil 15 of wire which has been pre-straightened in such a way that the turns of wire are not entangled during transportation. A plastic washer 10 is held against the upper part of the coil 15 by means of hooks 11, an elastic band 12 and a rigid shaft 13 attached by
a ring 14 to the bottom of the barrel 3. The hooks 11, the elastic band 12 and the rigid shaft 13 are positioned so as to hold the wire during transportation and storage prior to use. They are removed during use of the wire to allow the turns to unwind.
FURTHER SUBJECTS OF THE INVENTION
As illustrated in figures 1 and 2, the invention also relates to the preparation of a packaging for pre-straightened wire 2 described hereinbefore in which, in order to obtain a pre-straightened metallic wire in a cylindrical barrel 3,
a) the wire to be pre-straightened 1 passes through a series of straightening rollers 6 while being driven by a large-diameter capstan 7 maintaining the straightness of the wire,
b) said wire is then subjected to torsion while passing through two pairs of non-motorized rollers 8 situated in two perpendicular planes and set into a rotational movement round the wire,
c) said wire 2 guided by a drum 16 with the same rotational movement is deposited in a spiral in the bottom of the barrel 3,
d) said barrel 3 descends as it is filled so the space between the free surface of the wire and the base of the drum remains constant.
The applicants have therefore adapted a known process to the preparation of pre-straightened wire according to the invention.
If the metallic wire is made of brass, the invention allows hermetic storage of the coil of pre-straightened wire 15, preventing the risks of season cracking of the wire in a moist atmosphere or in the presence of ammonia. Other methods can also be employed to limit these risks: installation of drying sachets
or of products capable of fixing the ammonia or of protective products which are adsorbed on the surface of the wire, insulation ,of the barrels allowing the impact of ambient temperature variations to be limited.
The invention also relates to the use of a pre-straightened wire packaging according to the invention to supply machine tools directly with wire, in particular lathes and trimming machines, or cold-hammering machines, and to the use of a pre-straightened wire packaging according to the invention to supply an spark-erosion machine tool with wire.
The invention also covers the use of a packaging for any pre-straightened metal wire, whether a wire of steel or of a non-ferrous alloy other than copper, for supplying wire directly to machine tools, in particular lathes and trimming machines or cold hammering machines. In fact, the applicants have been able to check the applicability to steel wire of the concept developed with copper alloys such as brasses and described hereinbefore.
A coil 15 of pre-straightened wire 2 was prepared. This wire had
the following characteristics:
composition : brass containing 36% of Zn and 3% of Pb
diameter : 1.825mm
mechanical strength : 620 MPa
The device shown in figure 1 was used. Four series of seven flat straightening rollers orientated relative to one another (+ 90° / -45° / + 45°) were used as straightener 6. The speed of travel of the wire was 250 m/min and the speed of rotation of the pair of rollers 8 and of the drum 16 was 130 rpm. This wire was packaged in a barrel 3 having a useful weight of 250 kg, as shown in figure 2. This barrel must have a sufficiently great diameter not to impose on the wire curvature exceeding its yield stress.
Typically, this diameter will be 510 mm in the case of a small diameter wire ( The pre-straightened wire 2 obtained was tested on a "TORNOS" (R) type trimming machine, with and without using a rotary stand straightener:
without using a rotary stand, 4 m rods having 4 mm of deformation per metre were obtained. This deformation value is substantially the same as that obtained with a rod obtained by method B after an operation of straightening a wire having the same nature and geometric characteristics on a rotary stand with keys.
after using a rotary stand, 4m rods having a maximum deformation value of 0.5 mm per metre were obtained, corresponding substantially to a degree of straightness of rods obtained by method A.
The slighter the deformation per metre, the fewer vibrations during high speed rotation of the rod and the higher the precision of machining or, as desired, the higher the speed of machining. The precision currently obtainable with a rod having deformation of about 4 mm/m is typically 10 urn, whereas that obtainable with a rod having deformation of 0.5 mm/m or less is about 5 urn. Similarly, if the speed of machining with constant precision is considered, the gain in productivity is about 15% when passing from a rod having 4 mm/m of deformation to a rod having 1 mm of deformation or less.
The applicants have 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, they have observed that, when machining very long parts (typically 40 mm), the pre-straightened wire according to the invention allowed the heat treatment of the coils necessary to delete "the memory of the brass" to be avoided and allowed parts having deformation of 0.05 mm with tolerance of 0.07 mm to be obtained without heat treatment.
The applicants have also used the pre-straightened wire according to the invention to manufacture parts, not by machining but by cold hammering. They also found that, in the case of very long parts, typically of 30 to 50 mm, the problem of deformation also arises, owing to the residual deformation caused during the bending preceding placing in the barrel, and can lead to rejection of the final part despite repeated adjustment of the straightening device. In this case also, the pre-straightened wire in the example has allowed the deformation value to be limited considerably. The anodes of alkaline batteries are a typical example of parts obtained by cold hammering, owing to the close geometric tolerances.
Tests were also carried out on wires having different diameters (tests with brass wires having diameters of 3 and 6 mm) and different mechanical strengths: "hard" or "brittle" alloys such as lead bronze (Cu-Sn-Pb) or lead copper-nickel-zinc alloy (Cu-Zn-Ni-Mn-Pb) were successfully tested within the limits, as shown in claim 1. These limits result from the need to obtain deformation of less than 5 mm/m in the case of the rod subjected to rotation with a view to machining (method B) . If wires which are too thick and/or too strong are used, the resultant residual deformation is higher than this limit value of 5 mm/m of rod.
A coil 15 of pre-straightened wire 2 was prepared for spark-erosion. This wire, like the one described in the example of European Application 0 526 361-Al, had the following characteristics:
This wire according to the invention was tested on an spark-erosion machine in comparison with a standard wire. A standard wire involves a thermal or mechanical straightening treatment prior to winding.
The wire in barrels according to the invention has behaved in a similar manner to a thermally treated or mechanically straightened wound wire according to the prior art.
ADVANTAGES OF THE INVENTION
The invention solves the problems encountered with many types of user and in many types of trade: those of trimming and those of spark-erosion, and also those of shaping by cold hammering.
In each case, the improvement relates to the rate of manufacture of parts for all uses, for example connection, and therefore the productivity, or to the higher final quality of these parts, or to the lower level of investment to manufacture them, or to a combination of these advantages.
In the case of trimming, the invention is a synthesis of known methods, designated hereinbefore by A and B, after elimination of the drawbacks associated with each of these methods:
* As in method A, the customer carrying out trimming does not have to worry about the straightening of the rods or, concurrently, the customer carrying out spark-erosion does not have to worry about the presence of residual turns in the case of a breakage of the wire.
* For all that, as in method B, the wire supplier does not
have to use heavy means. In fact, the pre-straightening means employed can easily be integrated at the tail end of a drawing line without reducing the productivity of drawing, or increasing the production costs and, moreover, they involve a far smaller investment than industrial straighteners.
Overall, although the wire manufacturer still requires a pre-straightening means, on the other hand the trimmer no longer requires a straightener for each lathe, and this represents a considerable saving.
Thus, the straightening operation can be broken down into two stages:
a pre-straightening stage, carried out by the wire manufacturer. This operation is carried out at high speed (typically from 4 to 8 m/s) compatible with the high drawing speeds required to ensure high productivity.
a final straightening stage which is optional and is carried out by the user. This careful final straightening is carried out at low speed (typically from 0.1 to 0.5 m/s), allowing a high quality of straightening with an inexpensive device. In this case, a low speed does not represent a handicap because straightening is carried out in masked time, the limiting stage being associated with machining. On the other hand, as already emphasized, the economic nature of the straightening device is imperative as the trimmer has to equip each of his lathes with a device of this type.
By breaking down the straightening operation in this way, according to the invention, the relationship between quality and productivity is optimized while allowing the two parties involved, the wire manufacturer and the user, to work at their respective characteristic speeds.
Other advantages of the invention include:
* the possibility of using wires having higher mechanical
strength and better suitability for trimming than "softer" wires, the swarf being finer (0.05 mm instead of 0.5 mm typically) and easier to remove
* the almost total elimination of the risks of breakage during straightening of the wire as there is no more plastic deformation of the wire whereas, on average, a breakage per barrel of 250 kg of wire was observed in the prior art
* the pronounced reduction in vibrations associated with slighter deformation also leads to a lower fate of breakage of tools: with the invention the consumption of bits fell from 1 bit per 2000 kg of wire to 1 bit per 5000 kg of wire
* the possibility of supplying the machine tools or wire shaping machines from barrels situated not at the foot of the machines as in the prior art, but on a site remote from these machines, for example a storage depot from which sheaths would direct said wire to the machine tools since, as also known, a pre-straightened wire can circulate in a sheath
Such a configuration reduces the bulk of each machine and reduces the circulation and handling of barrels and the risks of accidents or impacts.
* the possibility of packaging "hard" or "brittle" alloys in
These alloys are poorly suited or unsuitable for packaging in barrels either because they have a high yield stress and necessitate a very great force to reach the elastic range during the bending preceding placing in barrels and during the straightening following unwinding or because they have a very narrow plastic deformation range with the result that limited plastic deformation such as bending or re-straightening is sufficient locally to exceed the limit of elongation at break and thus to cause repeated breakage of the wire. Thus, pre-straightened wires made of alloys having the composition Cu-Sn-Pb
("lead bronze") and Cu-Zn-Ni-Mn-Pb ("lead copper-zinc-nickel") could be packaged in barrels.
In the case of spark-erosion, the advantages afforded by the invention are also important:
* by elimination of thermal or mechanical straightening treatments
* possibility of a higher unit weight and' therefore greater autonomy, the weight of wire per reel typically being 5 kg whereas the weight per barrel is not limited.
* elimination of reels necessitating motorised unwinding devices and having to be destroyed after a limited number of rotations whereas the barrels can be re-used a great number of times.
Finally, whatever the use of the pre-straightened wire according to the invention, the applicants have found that the packaging according to the invention allowed the quantity of wire to be multiplied by 2 with an equal size of barrel, relative to the traditional packaging of wire in a barrel (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 have to be relatively "aerated" so as to limit the problems of entanglement when unwinding, whereas all the turns are completely blocked in a compact heap in the case of the invention.
1. Packaging process capable of providing a pre-straightened metal wire in a cylindrical drum,
a) the wire to be pre-straightened passes through a series of straightening rollers, being drawn by a large diameter capstan keeping the wire straight;
b) the said wire is then twisted passing through two pairs of free wheel rollers located in two perpendicular planes, and driven by a rotation movement around the wire;
c) the said wire, guided by a drum with the same rotation movement, is deposited in a spiral in the bottom of the drum;
d) the said drum lowers as it fills up, such that the spacing between the free surface of the wire and the bottom of the drum remains constant;
the said wire being a copper alloy with diameter less than 6 mm and mechanical strength between 400 MPa and 750 MPa, such that the said unwound wire is straight, with a sag per meter of less than 5 mm, and can be used to feed a free machining equipment.
2. Packaging as claimed in claim 1, wherein the said copper alloy is a brass.
3. Packaging process capable of providing a pre straightened metal wire in a cylindrical drum comprising:
a) the wire to be pre-straightened passes through a series of straightening rollers, being drawn
by a large diameter capstan keeping the wire straight;
b) the said wire is then twisted passing through two pairs of free wheel rollers located in two
perpendicular planes, and driven by a rotation movement around the wire;
c) the said wire, guided by a drum with the same rotation movement, is deposited in a spiral in
the bottom of the drum;
d) the said drum lowers as it fills up, such that the spacing between the free surface of the
wire and the bottom of the drum remains constant.
the said wire being a wire for electro-erosion, comprising an external cost of Cu-Zn alloy with a diameter of between 0.15 mm and 0.35 mm and mechanical strength of between 500 MPa and 1100 MPa, such that the said unwound wire is straight, with a sag per meter of less than 30 mm.
4. Process as claimed in any one of claims 1 to 3, wherein the said drum is a sealed drum to prevent risks of stress corrosion of the said wire, and may also contain other means (drying agent sachets, products that could fix ammonia, adsorbent protective products on the wire surface) to prevent these risks.
ABSTRACT-PACKAGING PROCESS CAPABLE OF PROVIDING
A PRE-STRAIGHTENED METAL WIRE IN A CYLINDRICAL DRUM
The packaging process capable of providing a pre-straightened metal wire in a cylindrical drum said wire is a copper alloy having a diameter smaller than 6 mm and mechanical strength of between 400 MPa and 750 MPa in such a way that said unwound wire is rectilinear with deformation of less than 5 mm per metre and can supply a trimming machine directly.
|Indian Patent Application Number||1751/CAL/1995|
|PG Journal Number||02/2014|
|Date of Filing||28-Dec-1995|
|Name of Patentee||TREFIMETAUX|
|Applicant Address||11 BIS RUE DE I'HOTEL DE VILLE 92400 COURBEVOIE|
|PCT International Classification Number||B65H 54/76|
|PCT International Application Number||N/A|
|PCT International Filing date|