FR2470170A1 - PROCESS FOR PRODUCING METALLIC WIRES FOR REINFORCING RUBBER OBJECTS - Google Patents

Abstract

THE INVENTION CONCERNS A METHOD AND A DEVICE FOR MANUFACTURING STEEL WIRES FOR THE REINFORCEMENT OF RUBBER OBJECTS. THIS IS A PROCESS ACCORDING TO WHICH A LAYER OF ZINC IS DEPOSITED ON A BRASS WIRE SUITABLE FOR WIREDING AND THEN THE WIRE IS THREADED TO BRING IT TO THE DESIRED DIAMETER, CHARACTERIZED BY THE FACT THAT A QUANTITY OF ZINC INCLUDED BETWEEN 0.1 AND 1 GRAM PER KILO OF STEEL AND THAT WE CARRY OUT THE WIRING IN CONTINUOUS WITH THE ZINC PLATED OPERATION. IMPLEMENTATION DEVICE INCLUDING A ZINC PLATED CELL ARRANGED IMMEDIATELY UPSTREAM OF A WALKER. APPLIES IN PARTICULAR TO THE MANUFACTURE OF STEEL WIRE FOR THE REINFORCEMENT OF TIRES.

Description

2 47 0170

  The present invention relates to a method for manufacturing metal wires for reinforcing rubber articles

  such as tires. More particularly, it concerns the

bonding of coated steel wires.

  For the reinforcement of rubber articles, it is

  bends steel wires covered with a layer of brass. The lay-

  your main function is to ensure proper adhesion

  between rubber and steel and it also plays an important role

  bearing during drawing. Normally a brass is used

carrying 60% to 75 X copper.

  Studies have shown that to have good adhesion, with certain types of gums, especially aging, it needed a brass with a layer richer in zinc surface.

  This zinc gradient can be obtained in different ways.

  For example by alternately depositing on steel wire layers of

  copper and zinc, the last layer being zinc, then thermo

  diffusion. If the thermodiffusion is not total, we obtain a layer richer in surface zinc. Another process, object of French Patent 2,393,856 is to deposit on the covered wire

  a brass of current composition, a thin layer of zinc.

  After drawing, a brass of non-homogeneous composition is obtained,

rich in zinc on the surface.

  With such treatment, one actually gets a good

  behavior of adhesion to aging. However, this

  assigned has disadvantages. The presence of a layer rich in zinc surface causes disturbances to wire drawing. The cited document states that the optimal zinc deposit is approximately

  0,06 g per kilogram of yarn and that problems occur

  spinning from 0.1 g of zinc per kilogram. Nevertheless, the document reports a zinc deposition rate of up to x 10-5 mg per mm 2 of application area which, for the smaller diameter wire mentioned in the patent, corresponds to a

amount of 0.3 g per kilo.

  However, further tests have shown that the best adhesion results are obtained only for amounts of zinc greater than 0, 1 g / kg and preferably between 0.3

  and 0.7 g / kg. But, in this case, drawing problems

  come very sharp and make this operation quite im-

possible industrially.

  On the other hand, it has been noted, in particular, for amounts of zinc omitted between 0.1 and 0.3 g / kg and above these values, that drawing problems are accentuated with

  the duration of wire storage prior to wire drawing. Thus, the difficulties

  cults are more important when the wire is drawn for example two months after zincing that when drawn for example the same day. The explanation that we give to this phenomenon is that it is formed at the brass-zinc interface, by diffusion under ambient conditions, layers of intermediate phases, fragile, indeformable and which even under very thin

  make the wire intractable under industrial conditions.

  (Many breaks, heavy die wear). This phenomenon is

  all the more marked as the zinc layer is important.

  The present invention proposes to provide a novel process for reconciling both good adhesion to aging and drawing in good

industrial conditions.

  It relates to a method of manufacturing a steel wire

  for reinforcing rubber articles such as pneumatic

  that a layer of zinc is deposited on a brass wire suitable for drawing and the wire is drawn to bring it to the desired diameter characterized by the fact that a quantity of zinc of between 0.1 g and 1 g per kilogram of steel wire and

  the drawing is carried out continuously with the zinc-plating operation.

  Preferably, the amount of zinc deposited is included

between 0.1 and 0.6 g / kg of steel.

  The application of zinc is preferably carried out

  electrolytic deposition, during the passage of the wire in an electric bath

  trolytically appropriate. It is possible to use all types of bath known in galvanizing: cyanide bath, basic non-cyanide bath, acid bath, pyrophosphate bath, etc.

  preferably non-toxic baths.

  The fermentation is done according to the usual methods

  electrolytic coding, or thermodiffusion fermentation.

  A standard brass containing 60% to 75% copper is used.

  quantity deposited being between 2 g / kg and 7 g / kg of steel.

  Optionally, a slight etching can be carried out before zincing.

  Steel is a patented hard steel commonly used for this type of application. The diameter of the treated son is preferably between 0.80 and 1.90 mm, but can also be outside

  of these limits. Wire drawing, which takes place continuously with the zin-

  pledge, is performed under normal conditions with respect to all parameters (speed, number of passes, number of channels, nature and shape of the dies, lubricant .... etc ..). Speed

  is preferably between 10 and 25 m / s.

  The method can be implemented by a device according to the invention comprising an electrolytic zinc coating cell associated with a drawing machine. Preferably, according to the invention, the device comprises a galvanizing cell controlled by the progress of the drawing machine. According to the servo system, the current

  electrical power is established at start-up only when the

  leuse has reached normal walking speed; the circuit is

  cut automatically when the drawing machine stops.

  Advantageously, according to the invention, the direct current supply is effected, from the alternative network, to the

  medium of a regulated current rectifier. This system is

  tageux compared to the system with constant voltage. Indeed, by the polarization phenomenon, a deposit is formed at the anode, which increases the resistance of the circuit. If the voltage is

  constant, the intensity decreases as resistance

  tance increases and the amount deposited, which is proportional to the intensity, also decreases. We have an irregular deposit. According to the invention, servo-control and power supply

  constant result in a regular deposit, so a regular product.

  But the invention will be better understood with the help of examples

  ples and figures below, given by way of illustration but not limitation - Figure 1 schematically represents a device for the

  implementation of the method according to the invention.

  FIG. 2 is a graph showing the advantages of the invention

tion.

  FIG. 3 is a graph of the variation of the composition of the brass, as a function of the depth, for treated threads

according to the invention.

  The device according to FIG.

  an electrolytic galvanizing cell 1, and a drawing machine 2 dis-

  posed downstream, partially shown. The zinc-coating cell 2 comprises a tank 3 containing the bath which is crossed by the wire F

  brass. The brass wire is fed from a furnace coil

  4. The bath circulates in closed circuit by means of a pump 5

  from a tank 6. It is fed into the tank 3 by the con-

  end of 7 and it evacuates at both ends of the tray 3 by

  ducts 8 and 9 which bring it back to the tank 6. The anode is

  placed by a basket 10 in which zinc pellets have been deposited, the wire F is connected to the cathode via the axes of the guide wheels 11 and / or 12 located at the entrance and to the

  3. The wire is pulled through the tray, through the trough

  spinning machine 2. At the outlet of the bath, the galvanized wire is rinsed in a tray 14. The wire then continues continuously in the drawing machine 2, of which only two dies 15 and two drawing capstans 16 have been represented. The wire drawn in the conditions usual is

  received on any appropriate support not shown. The device

  additionally carries means not shown to control the

  walk of the galvanizing cell at the walking of the wire-drawing machine.

  According to these means, the galvanizing cell starts only

  when the drawing machine has reached normal operating speed.

  The operation of the galvanizing cell stops at the same time

  than the drawing machine. The device also comprises means.

  not shown, of known type of power supply with inten-

Regulated.

  In order to highlight the advantages of the invention, a series of tests has been carried out, they are the subject of the following examples

Example 1 -

  This example relates to adhesion performance tests

aging.

  The adhesion test is carried out on a strand and proceeds as follows: A gum is used to make calendered sheets with the test strand and these sheets are aged for 5 weeks at 211 ° C. and at 65 ° C. relative humidity, in a strictly controlled atmosphere. At the "zero" time and every week, a rubber-wrapped strand is taken and placed in a standard US adhesion test tube.

  ASTM D 2229-73 made itself in gum A. The adhesion is measured

  by the method according to the standard above.

  The results are shown in Table 1 below.

  and on the graph according to Figure 2, on which the old time

  lissement T is worn in abscissae and the adhesion expressed in

decanewtons, on the ordinate.

  1 a - Indicator - The indicator consists of a 4 x 0, 25 S 12.5 strand, that is to say constituted by 4 0.25 mm diameter wires twisted in S at a pitch of 12.5 mm . The 0.25 mm diameter wire is obtained by drawing a 1.25 mm diameter wire of patented hard steel. Before wire drawing, the 1.25 mm diameter wire was coated with a brass layer, at the rate of 5.8 g of brass per kilo of steel wire, brass comprising 66 X copper and 34% zinc. After wire drawing, a brass wire 0.25 in diameter containing 5 g / kg of brass at 65.8% of copper and 34.2% of zinc is obtained. The loss of 0.8 '; in weight of brass is a normal loss that is often found in wire drawing. From this wire, we therefore manufacture a strand 4 x 0.25 S 12.5 and practice

the adhesion test on this strand.

  The results are shown in Table 1 below and on the graph according to FIG. 2: curve A. 1 b - The above adhesion test is carried out on a strand made from a first wire treated according to FIG. invention. The starting wire is identical to that of Example 1a, that is to say 1.25 mm diameter wire coated with a 66% brass and

  34% zinc with 5.8 g of brass per kilogram of steel wire.

  Next, according to the invention, zinc is applied to the brass at the rate of 0.15 g of zinc per kilogram of steel wire. We obtain

  a wire before entering the drawing machine having 5.95 g of re-

  per kilogram of steel wire and the average composition of which is 64.5% Copper and 35.5%. Zinc. The wire is drawn continuously with zinc coating, under the conditions of the invention. A thin wire with a diameter of 0.25 mm coated with 4.8 g / kg of a brass of overall composition of 65% copper and 35% zinc is obtained. From this wire, a strand 4 x 0.25 S 1.25 is manufactured as in the example

  1a and the same adherence test is applied to this strand.

  The results are shown in Table 1 and on the

  graph in Figure 2: curve B. There is already a clear

  improvement of the resistance to aging.

  1 c - The adhesion test above is carried out on a

  strand made from a second wire according to the invention.

  The starting thread is identical to that of Examples 1a and 1b. Then, according to the invention, a zinc coating is carried out, the amount of zinc being 0.5 g / kg of steel wire. A wire having a coating quantity of 6.3 g / kg, the overall composition of which is 60.5% copper and 39.5% zinc, is obtained before entering the drawing machine. The wire is drawn continuously with zinc coating, under the conditions of the invention. After wire drawing, a thin wire with a diameter of 0.25 mm coated with 5.6 g / kg of a brass of overall composition 62 Z Copper is obtained. From this fine thread, a strand of 4 x 0.25 S 12.5 is made as in

  Examples 1a and 1b and the adhesion test is applied.

  The results are shown in Table 1 and in the graph in Figure 2: Curve C. There is a significant improvement in

adhesion to aging.

  Table 1 - The above examples are times of

  storage of the calendered sheets before making tires.

  It is found that the improvement of the grip of aging adhesion increases with the amount of zinc applied in

area.

  The amount of zinc applied to the surface prior to

  lage, partially mixes with brass during wire drawing,

  by mechanical phenomena and partial thermodiffusion.

  A finished wire coated with a brass of inhomogeneous composition, richer in surface zinc, is obtained, as shown by the surface analyzes made in photoelectron spectroscopy.

  ESCA (Electron Spectroscopy for Chemical Analysis).

  The graph according to FIG. 3 gives, as a function of the depth: "peel depth", the value of the atomic percentage of copper measured from peaks of intensity corresponding to the levels of electronic energy 2 p 3/2. The analysis relates to three son: control wire according to Example 1a, and son according to the examples

1 b and 1 c.

  It is found - generally for the three son, the composition of the brass evolves according to the depth: the copper content increases with the depth then practically stabilizes from about 500, for the son treated according to the invention, the brass is -More poor in Copper surface: closer to the results adhesion -in decanewtons daN

  Sxemples Time O 1 week 2 weeks 3 weeks 4 weeks 5 weeks

  less 38 21.2 18.2 16.2 17.3 17 1 b. 37 28.3 26 8 24.2 23.8f 21.2 1 c 36 d 32.8 31 308 30.4 306 of adhesion above, this confirms that the grip of adhesion

  aging increases with the surface zinc content.

Example 2 -

  This example is intended to highlight the fact that wire drawability is not affected by the coating of

  when, in accordance with the invention, the

continuous with zinc coating.

  2 a - The control wire is the brass wire of diameter

  1.25 mm, according to Example 1a, subjected to a drawing in the con-

  usual conditions to obtain a wire with a final diameter of 0.25 mm.

  The test consists of measuring the mileage of wire drawn before

  to change the sectors, given the usual tolerances

  in the diameter of the finished wire. Mileage, for the wire

  witness, is expressed as the basic figure 100.

  B) The treated yarn is the yarn according to Example 1b, i.e. the yarn 1 coated with 0.15 g / kg of zinc. he

  is drawn continuously with zinc coating under

  ticks in control line 2 a. The length drawn before change

  dies, brought back to base 100 is 120.

  2 c - The treated yarn is the yarn according to Example 1 e, that is to say the yarn 1 coated with 0.5 g / kg of zinc. he

  is drawn continuously with galvanisation under identical conditions.

  ticks over the wire 2 a. The length drawn before change

  dies, brought back to base 100 is 95.

  2 d - using a wire which has undergone a treatment of the type known from French Patent 2,393,856. The starting wire is the

  bristled wire according to Example 1a, coated with 0.35 g / kg of zinc.

  After galvanizing, the wire is stored for 15 days, then drawn under the same conditions as the control wire 2 a. The drawn length before the change of the dies, brought back to the base 100,

  is 5 to 10. In addition, it is found that the thread is very irregular.

  to bind and that breaks are frequent. Wire drawing in

  industrial conditions can not be realized.

  Example 2 shows that, unlike the known processes, there are no particular drawing difficulties or increased difficulties with the amount of zinc deposited

  on the surface if, in accordance with the invention, the

  continuous with zinc coating. On the other hand, if we draw, in

  discontinuous, in accordance with the prior art, there are large

  drawing difficulties which are increasing with the rate of

  zinc deposited and intermediate storage time.

  Examples 1 and 2 taken together clearly demonstrate the advantages of the invention: - no difficulty in drawing for zinc deposits up to 1 g / kg of steel, - holding the adhesion to aging, clearly improved

  compared to the known art, thanks to more important zinc deposits

up to 1 g / kg of steel.

Example 3

  This example aims to highlight, improve

  maintenance of adhesion to aging.

  The test is carried out as follows: With the wire to be tested, a calendered sheet is produced with a rubber B. Test specimens are produced, each being made by cutting two pieces of said sheet, which is

  place one on top of the other, crossed at 900. An old

  in a drying oven at 350C and 98 7% relative humidity,

  to reproduce storage conditions under

  Pical. The specimens are aged respectively zero,

  3, 6, 9, 15 days after which they are vulcanized. After vul-

  cannulation, the two pieces of tablecloth are separated by

  from zero to five depending on the recovery of

  rubber adhering to the threads: five corresponding to a covering

  maximum and zero at no recovery.

  The control wire is obtained from a 1.25 steel wire -

  of diameter, coated with copper brass at a rate of 4.7 g / kg.

  This wire is drawn under the usual conditions until the dia-

  meter 0.25 mm. A 0.25 mm diameter wire coated with a 64.5% copper brass at a rate of 4 g / kg is obtained. A strand 4 × 0.25 × 12.5 was made from this wire as in the previous examples and subjected to the test above; we obtain the following results

Table 2 -

  Days 0 3 6 9 15 Note 5 3 1 0.0 The test is then subjected to a wire manufactured by the

process according to the invention.

  The starting wire is a brass-plated steel wire with a diameter of 1.25 ms, the quantity of brass is 4.5 g / kg and its composition

  69.5% copper and 31.5% zinc. On this brass wire,

  Zinc plating at a rate of 0.4 g of zinc per kilogram of steel. The wire after galvanization and before entry into the drawing machine is coated with a quantity of brass of 4.9 g / kg comprising 63.8 Z globally

  of copper. The galvanized wire is drawn continuously according to the invention.

  After drawing, a brass wire of final diameter 0.25 m is obtained, the amount of brass being 4.1 g / kg and its overall composition 7. of copper and 35% of zinc. This wire is comis strand 4 x 0.25 S 12.5, which is subjected to the test described above we obtain the following results

Table 3 -

  Days 3 6 9 15 Note 5 5 5 5 4 We notice a very important increase of the behavior

  adhesion to aging with the thread manufactured by the

assigned according to the invention.

Example 4 -

  It also aims to highlight, holding

  adhesion to aging. This is an aging test

  in an autoclave, in the presence of moisture, at 120 ° C

  8 hours under a pressure of about 2 bar. The adhesion is me-

  tested according to ASTM D 2229-73 on test specimens

  The controls consist of two strands 4 x 0, 25 S 12.5 and 5 x 0.25 S 9.5, the strands of which were obtained by drawing a

  brass wire 1.25 mm in diameter. The tests are ef-

  made on strands of identical construction to the

  stitued by son obtained by the same method as the control son with, as a difference, the application of zinc coating according to the invention. The results are shown in the following table

(Table 4)

  In this table - the column "construction" gives the conformation of the strands, - the column "brass: wire AZ" concerns the brass wire Before

  Zinc and gives the amount of brass deposited in g / kg

  to the steel, and the percentage of copper in this brass, the column "Zn addition" gives the amount of zinc deposited, in g / kg with respect to the steel, in the case of son according to demand, the column "brass: wire AT" gives the quantity of brass after galvanizing and Before wire drawing and the overall percentage of copper of this brass, - the column "brass: strand" gives the quantity of brass remaining after drawing and the overall percentage of copper of this brass, - in the "Adherence" column measured according to ASTM D 2229-73,

  A0 denotes the initial adhesion, before autoclaving and

  At the adhesion after 8 hours of autoclave, expressed in dae.

  èN go 0- N * Test Construction Brass: wire AZ Addi- Brass: wire AT Brass strand Adehrence Zn g / kg 7% Cu t Ois / k% Cu g / kg% Cu A A Zn oa

L ,,. ... ...... _

  41 5.6 66.5 5.6 5.6.5 4.5 65.7 47.0 18.0

witness

[.. ,,,

  42 5 x 0.25 S 9.5 5.3 69.4 0.35 5.65 65 5.1 67 53.5 33.5

  43 4.2 68.8 0.35 4.55 63.5 3.6 65.2 50, C 34.5

: - ,; AT -,,. , <'' .... _ _,:,; '"

  44 4.8 67.5 0 4.8 67.5 3.9 68 40.5 13

4 x 0.25 S.12.5.request

  4.2 68.8 0.35 4.55 63.6 3.9 65.5 43, 25

ii i i j i i

COMMENTS

  On the first control beam 41, there is a significant drop in adhesion between the initial adhesion and after

passage in the autoclave.

  On the strand 42, made from treated yarns according to the invention, it can be seen that if the adhesion to zero time is

  of the same order as for the strand 41, on the other hand the fall of

  aging is much lower.

  We can make the same remarks for the 45 strand

parried to witness 44.

  There is also a slight drop in adhesion

for the strand 43.

  The examples above clearly highlight the advantages

  embodiments of the invention which makes it possible to hold the adhesive

  improved aging compared to known processes,

  combined with good wire-drawing.

  The invention is applicable to steel wires for the purpose of

  forcing rubber articles, in particular to strengthen

of tires.

R E V E E D I C A T I 0 N S

  l / - Method of manufacturing a steel wire for the purpose of

  forcing rubber articles such as pneumatic, according to which a layer of zinc is deposited on a wire which is suitable for drawing, and then the wire is drawn to bring it to the desired diameter.

* re, characterized by the fact that a quantity of zinc is deposited

  between 0.1 and 1 gram per kilogram of steel and

  continuous drawing with the zinc plating operation.

  2 / - Process according to claim 1, characterized in that the amount of zinc deposited is between 0.1 and

0.6 grams per kilogram of steel.

  3 / - Method according to one of claims 1 and 2, carac-

  the fact that the application of zinc is carried out by de-

electrolytic pot.

  4 / - Method according to one of claims 1 to 3, carac-

  made by the fact that the zinc coating is applied on a brass wire

  whose quantity of brass is between 2 grams and 7 grams

my per kilogram of steel.

  / - Device for implementing the method according to

  one of claims 1 to 4, characterized by the fact that

  comprises an electrolytic zinc coating cell arranged upstream

a drawing machine.

  6 / - Device according to claim 5, characterized in that the operation of the galvanizing cell is slaved to the

walking the drawing machine.

  7 / - Device according to claim 6, characterized in that the power supply of the cell of

  galvanizing, is at controlled intensity. -