US3501347A - Removing scale from wire and similar strip material - Google Patents

Description

March 17, 1970 H. KENMORE 3, 7

REMOVING SCALE FROM WIRE AND SIMILAR STRIP MATERIAL Filed Aug. 22, 1966 s Sheets-Sheet 1 52 FIG?) INVENTOR. Herber1 Kenmore March 17, 1970 H. KENMORE REMOVING SCALE FROM WIRE AND SIMILAR STRIP MATERIAL Filed Aug. 22, 1966 3 Sheets-Sheet 2 FIG.6

I March 17, 1970 H. KENMORE 3,501,347

REMOVING SCALE FROM WIRE AND SIMILAR STRIP MATERIAL Filed Aug. 22, 1966 3 Sheets-Sheet 5 FIG.8

EMPTY LIMING RINSING RlNSlNG WATER RINSING RINSING DESCALING DESCALING FIG.7

DESCALING DESCALING DESCALING DESCALING l/Illl/II;

Lmwpmd IN VEN TOR. H erberf Kenmore United States Patent US. Cl. 134-14 Claims ABSTRACT OF THE DISCLOSURE A process of pickling wire by passing the wire in the form of a helix in and out of one or more pickling baths a multiplicity of times, the wire speed being at least 50 meters per minute so that the scrubbing action of the pickling liquid promote-s the removal of scale; the wire being continuously removed from the pickling bath at the end of the treatment, so that each portion of the wire is subjected to the pickling liquid for the same period of time. Preferably, the wire is subjected to a mechanical operation for breaking the scale before being formed into the helix for the pickling treatment. After passing the pickling bath the wire is passed through water rinsing baths and preferably coating baths. Such baths are operated hot, so that the heat of the 'wire and a passage through air dries the coating. The hot rinse water is fed counter-current, eventually ending in a pickling bath.

This invention relates to a process of continuously treating long lengths of wire and similar linear products with chemical liquids and more particularly it relates to the chemical wire treatments of the type which includes the step commonly referred to as pickling, in which heat scale is dissolved from the wire by aqueous chemical solutions.

In another application, Ser. No. 574,203, filed concurrently herewith, now Patent No. 3,399,702 there is disclosed and claimed at least a portion of the apparatus employed in the present process.

In the present specification and claims the term wire is used in its generic sense to include all types of one dimensional material of substantially uniform cross sectional shape regardless of whether that shape is round as in conventional wire or of some other configuration.

The conventional method of pickling wire for many years past has been to load one or more wire coils or bundles onto a hook or similar holding device and immerse the bundles in a series of baths, one or more of which may be described as a pickling bath. A typical treatment will require three or four baths including one for acid pickling, one for water rinsing, and one for soap rinsing, and one for surface coating. In the normal batch treating process the wire is in contact with the acid for 10-30 minutes. After each water rinsing bath it is necessary to subject the bundles to a strong water hosing treatment to remove remnants of acid held by surface tension between closely spaced regions of the wire coils of the bundles. This process is very wasteful of water, does not treat all portions of the bundle equally and has other disadvantages. After being pickled, and in order to protect the surface from immediate oxidation and prepare it for drawing the wire is immersed in an aqueous, borax, lime, soap or phosphate bath and then, after being removed from the bath, dried in an oven to coat the wire with a layer of the lime, borax, soap or phosphate. Wire for drawing must include a layer of lime or similar material to hold the lubricant and form a barrier film between the wire and the surface of the die. Coatings of lime etc., applied by dipping and baking are not uniform and excess lime is set free from the wire in the form of dust so that spaces provided for the pickling of wire by conventional processes are filled and covered with dust.

It might be expected that a process for continuously moving the wire strand through a series of pickling treatments such as disclosed in U.S. 2,680,710 or US. 3,002,537 wherein the wire is formed to the shape of a helix and passed through the baths like a screw, would be superior to the conventional process described above. The processes and apparatuses described in said patents are capable of producing pickled wire with greater uniformity than said conventional processes but such patented processes cannot compete economically with the conventional batch-type of pickling processes. For example, a typical batch treating process will load two tons or more of wire bundles onto a hook and treat such bundles simultaneously to a series of 3 or 4 baths at a throughput rate of about 10 tons per hour. The apparatus of 3,002,537 when operated at its maximum permissible speed of about ft./min., for example, treats only about 1 ton of /8" wire per hour. In both of said patents, the wire is pushed through a coiling device which forms it into a helix of a predetermined uniform diameter and a predetermined uniform pitch and the helix is fed continuously to one or a pair of horizontal supporting rollers supported over a bath structure so that the stored coils on the supporting rollers pass through a series of baths. In both of said prior patents, one main limitation preventing higher speeds is the inability to push the wire through the apparatus at speeds greater than about 100 ft./min. without substantial slipping. Slippage never takes place evenly throughout the length of a wire so that slippage necessarily results in loops or individual coils of uneven diameter. Excessive vibrations also take place at higher speeds with the apparatus of said prior patents, especially with respect to US 2,680,710 which has only one horizontal supporting roll for the helix, but vibrations also interfere with the two-roller device of 3,002,357 when speeds in excess of about 100 ft./min. are attempted creating excessive and uneven wear of the surface regions thereof and causing subsequent failure.

Among the objects of the present invention is to provide an improved process for forming a wire into a rotating helix and passing the helix at high speeds of rotation through a series of treating baths while supported on one or more horizontal rollers.

Among other objects of the invention is to provide an economical process for continuously and uniformly treating wire by passing it through cleaning liquids (including corrosive type scale-removing liquids) at very high speeds Among other objects of the invention is to provide a method for removing scale from wire, which is economically competitive with the batch process.

Among still further objects of the invention is to provide an improved process for treating steel wire with acidic liquors to clean the surface thereof while maintaining contact between the wire and the acidic materials for the minimum time required to clean the same thereby avoding hydrogen embrittlement.

Among other objects of the invention is to provide an improved process for continuously pickling and coating wire with lime, etc. to preserve its clean surface and prepare it for drawing.

One phase of the invention is based on the discovery that certain types of devices heretofore employed for drawing or pulling wire without slippage can also be employed for pushing or forwarding and forming wire into a helix of substantially uniform coil size at very high speeds and still without slippage of the wire, or, in other words, at substantially uniform high speeds. Ex-

amples of such devices which can be converted to high speed wire pushing and forming devices without slippage are disclosed in French Patent No. 89,447 and Kitselman US. Patent No. 3,106,345.

High speed operation of a helix-forming and storing device such as described above creates new problems in the continuous process of treating wire which, in order to avoid repetitions, will be discussed in detail below in connection with the solution of said problems. Briefly, however, these problems relate generally to the avoidance of friction between the rapidly moving wire and the separating walls of the treatment tanks and the reduction of vibration of rapidly rotating parts of the apparatus. On the other hand, the high speed continuous operation makes it possible to make more effective use of water, and in fact substantially eliminates waste water. The high speed of operation also makes it possible to eliminate oven drying of the wire after applying a coating of borax, lime, phosphate or similar material which is necessary if the descaled, cleaned wire is to be redrawn.

Briefly, the process of the invention involves the steps of forming the wire into the shape of a travelling helix with a horizontal axis and forwarding the wire helix through a treating zone at wire speeds of 50 500 meters per minute, providing a series of tanks below the travelling helix so that the wire loops move in and out of the treating liquid held in the tanks and pass through the series of baths held in the tanks in succession, treating the wire to the scrubbing action of heated, aqueous, corrosive liquid held in at least one of said tanks, rinsing said wire with water in at least two tanks, said water being fed counter-currently in said rinse water tanks and being supplied together with drag-out liquid to supply water lost by evaporation, etc., from the corrosive liquid tanks.

Preferably also, the amount of heat scale to be removed from the wire is reduced by mechanically removing and/or breaking up the scale-layer just prior to forming the wire into the form of the travelling helix.

Suitable aqueous solutions for removing scale will depend somewhat on the metal of which the wire or its surface layers consist. However, sulfuric, hydrochloric, nitric or citric acids are common ingredients of such solutions and there are also many proprietary mixtures of pickling compositions. The wire may be of various types of steel, copper and its alloys, aluminum, etc.

The bath in which pickling or removal of oxide layers takes place is operated at about 70l00 C. and the temperatures of subsequent baths are so adjusted so that the wire which is heated in the pickling bath, never cools oflf, so that when the wire leaves the lime, borax or other coating bath and proceeds to an empty bath, the lime or borax solution thereon dries very rapidly.

As mentioned above, a typical batch process for pickling steel wire will treat about tons per hr. of wire in a treatment comprising three or four treating baths and a spraying or hosing to remove residual acid. For example, the hooks employed to dip the coils in and out of the treating baths carry about two tons of wire. A recent account of an ultramodern, so-called continuous process entitled Continuous Spray Pickling of Copper Rod Coils and capable of treating about 12 tons per hour of copper wire is disclosed in Wire & Wire Products, Oct. 1965, vol. 40, No. 10, pages 1521-1524 and 1633. In said process, 265 lb. bundles (called coils in the article) of copper wire are loaded onto a walking beam type of conveyor one at a time and are passed through a tunnel wherein they are treated to an acid pickling spray while passing over a distance of 35 ft., allowed to drain for ft, through a water spray and drain for 12 ft., then through a soap spray for 10 feet. The entire line is 80 ft. long without its subsidiary equipment. Said process is not continuous in the same sense as the process of the present disclosure because the former still treats wire in the form of a bundle. The 12 ton output is considered a good output for a copper rod pickling device, especially since, according to the article, it handles the complete output of a rolling mill. The apparatus of said article includes means for recovering acid and the copper dissolved from the bundles, and elaborate means for disposing of waste water none of which is recovered.

According to the present process no waste rinse water is produced, the rinse water at the end of its counter-current passage being employed to makeup for the loss of water by evaporation from the hot pickling compartments. Also according to the present system liming or similar treatment is added without the necessity of adding a baking treatment to dry the lime solution on the wire.

Other and more detailed objects and advantages of the present invention will become apparent from the following specification and appended claims when taken in connection with the accompanying drawings in which:

FIG. 1 is a top plan view of the apparatus for carrying out the process.

FIG. 2 is a plan view of the treating tank of FIG. 1 without the wire helix therein.

FIG. 3 is a detail view, somewhat exaggerated, to show the means for avoiding friction between the wire of the helix and the walls of the treating baths.

FIG. 4 is a detail view showing how wire is fed to and off of the high speed forwarding device.

FIG. 5 is a side view of a device similar to the device of FIG. 4 but somewhat modified.

FIG. 6 is a detail view of a modified form of apparatus utilizing the device of FIG. 5.

FIG. 7 is a cross sectional view of the apparatus taken. on line 77 of FIG. 1.

FIG. 8 is a partial plan view of the bath structure illustrating the spacing of partitions for a pickling process which is different from the spacing in FIGS. 1 and 2.

. In the descaling apparatus of FIG. 1, the wire is unwound from a supply source 10, passed over guide rollers 11, 12 and over a mechanical descaling or scale breaking device 13, 14. While passing over rollers 13 and 14 the wire may be brushed with roller brushes to remove scale loosened by the bending operation. An important function of device 13, 14, however, is to crack or break the scale to make it more susceptible to attack by the pickling liquid.

From the mechanical scale breaker 13, 14 the wire passes to a straightener device 15, 16 which is not essential in this particular apparatus but is often desirable. The straightener device also acts as a guide in cases where the scale removing device is at some distance from the high speed forwarding and coiling device 20. Wire in helical form 9 coming from the forwarding device 20 is fed upwardly with respect to device 20 onto the pair of horizontal supporting rollers 40, 41. While stored in the supporting rollers 40, 41, the wire helix dips into the tanks 50 which is subdivided into a plurality of separate tanks (see FIG. 2) by partitions 51-60 extending at right angles with respect to the sides 61, 62 thereof. The partitions 51-60 do not necessarily extend at right angles to the sides 61, 62 but since the tank structure is adjustably mounted and since it is easier to provide partitions that extend at right angles to the side, they are shown in this 'Way. From the end of storage rolls 40 and 41 the wire is wound onto spool 70.

THE FORWARDING AND HELIX-FORMING DEVICE As already mentioned the forwarding device 20 is of the type shown in Patents No. 589,447 or No. 3,106,354 and comprises a rotor device 31 containing a peripheral groove 32 which has at least one sloping side so that wire fed to the groove 32 sinks therein until it is wedged between both sides thereof. An idler pulley 33 is provided spaced somewhat from rotor 31. The rotor 31 i positively rotated (at a high spee din this invention) by a suitable shaft 34. The idler pulley 33 is free to rotate about or with shaft 35. As shown in FIGS. 4, 5, 6 and 7, the

rotor 31 is positioned below the horizontal helix storage rollers 40, 41 and the axis of rotor 31 is below the axis of the helix held by storage rollers 40, 41. Other proximater positions of the rotor and its axis with respect to the storage rollers can be employed. Upon being delivered from the groove 32 of rotor 31, the wire retains the helical form imparted thereto during its last passage around in the groove of rotor 31 but expands in diameter by a constant amount depending on the characteristics of the wire itself, but which is between 15 and 30% of its diameter within rotor groove 31. The fact that the diameter of the helix formed by the device is greater than the diameter of rotor 31 is taken advantage of by positioning the storage rollers 40, 41 with their feeding-on ends above the rotor 31 while permitting the rollers 40, 41 to be driven by shafts 42, 43 which are rotatably held in bearings 44-47 fixed to a supporting structure which extends over but is completely separate from the structure which supports the tanks 50. The spacing distance of the helix storage rollers 40, 41 above the coil forming and forwarding device 30 is not extremely critical so long as the helical curvature imparted to the wire is not disturbed to the extent that the curvature becomes nonuniform. As shown in FIG. 6, for example, the large portions of rollers 40, 41 may be completely above the periphery of the device 30, whereas in FIGS. 4 and 5 only the smaller drive shafts 42 and 43 of the rollers 40, 41 are above the periphery of device 30.

The wire is guided onto the forwarding and coiling device 30 in such a way as to substantially eliminate slippage by passing the Wire 9 first into groove 32, thence over idler 33 and back into groove 32. As the wire in the groove passes under the oncoming wire 9, it is pressed further into the groove 32 and is wedged thereby so that no substantial slippage takes place. In the arrangement shown in FIG. 4, the oncoming wire overlaps the wire which has preceded it over an arc of approximately 100-120 which is very satisfactory. A greater overlap can be obtained without changing the position of pulley 33 by passing the wire around pulley 33 so that it crosses in returning back to rotor 31, as shown in dotted lines in FIG. 4. Obviously the degree of overlap can also be changed by changing the position of pulley 33.

THE HORIZONTAL, HELIX-STORING ROLLERS The horizontal, helix-storing rollers 40, 41 are driven at the same surface speed as the speed imparted to the wire helix 9. Separate controls are provided for adjusting the speed of rotor 31 and adjusting the speed of storage rollers 40 and 41. Apparatus with separate controls for the wire feeding device and the storage rollers has been disclosed in prior patents (2,680,710, for example) and details of the separate controls are not shown here.

As already stated, rollers 40, 41 are driven through shafts 42, 43 mounted on the end supports 71, 72 which are spaced beyond the ends of the bath structure 50. In the apparatus of FIG. 1, the shaft 42 is rotated through a chain-driven gear 73 and shaft 43 is driven by a belt or chain 74 connected between shafts 42 and 43. The opposite end of shafts 42, 43 are held in bearings 75, 76, respectively. If desired, the rollers 40, 41 could be driven from the end adjacent bearings 75, 76. The weight of the wire supported by the rollers 40, 41 is substantial. Thus if the helix which is temporarily stored on the rollers contains 200 turns of steel wire and is about 100 cm. in diameter, the weight of the stored portion of the helix is about 800 lbs. This weight is shared by the two rollers 40, 41 and is fairly evenly distributed over the length thereof. Nevertheless, there is a tendency for such rollers to sag under the load and, therefore, to vibrate when rotated at high speeds. The rollers 40, 41 must be made fairly large primarily to avoid excessive angular speeds thereof.

One unexpected feature of the invention relates to the discovery that exceptionally good scrubbing action is obtained by passing the wire in and out of the liquid baths at speeds of at least about 50 meters per minute. At the same time speeds of over 300 meters/min. have been attained with this apparatus and with better mechanical wire-supplying means to the apparatus, etc., it is reasonably expected that the operation speed can be increased to about 500 meters/min., or more.

With conventional forwarding rollers 40, 41 of about 50 cm. circumference such as customarily employed with the apparatus of 3,002,537 for example, the minimum angular speed of rotation required to feed the wire at 50 meters/min. is rpm. and is excessive. For the high speed of operation of the present invention, the minimum diameter of the storage rollers depends on the speed of the wire and the diameter of the helix and said diameter should be suflicient to provide a surface speed which is equal to the speed of the wire when the angular speed thereof is not more than 250 rpm. (revolutions per minute). For a speed of 100 meters/min. and a helix diameter of 100 cm. the circumference of the storage rollers should be at least 400 mm., which means a diameter of about mm. For a speed of 250 meters/min. the circumference should be at least 1 meter (diameter about 325 mm.). The maximum diameter of the supporting rollers is limited by the diameter of the helix. Thus with two supporting rollers the diameter of each has to be less than half the diameter of the helix especially since the inner adjacent surfaces of two supporting rollers move in opposite directions. With a single supporting roller, the diameter thereof may approach the diameter of the coil. In the device which has been operated at about 300 meters/min., the diameter of the forming device 31 is 800 mm., the diameter of the helix obtained thereby is 1100 min., and the diameter of each of the two supporting rollers is 400' mm. (or about /2 the diameter of the forming rotor 31). If the minimum diameter requisite for the size of the storage rollers 40, 41 is not observed, excessive vibration of the rollers takes place as the speeds set forth are attained whereupon the uniformity of the helix is not maintained. At speeds of about meters/ min., two such machines can descale approximately the same amount of wire as a batch type descaling apparatus, the two machines take up less floor space and together require less attention than the single batch type device and at the same time produce a superior product.

As shown in FIG. 2, there is also associated with the storage rollers 40, 41 a guide mechanism 80 containing a plurality of fingers 81 to be inserted between adjacent coils of the stored helix.

Where the wire is to be treated electrolytically in one or more of the separate baths, by being made the cathode or anode, the current may be fed to the wire through one of the rollers 40, 41 in the way shown in US. Patent No. 3,073,773 or 3,109,783.

THE TANK STRUCTURE As already indicated the tank structure 50 is positioned and anchored independently of the supporting structure for the helix-propelling means (including the helix-forming device 20 and storage rollers 40, 41). Furthermore, as shown in FIG. 7, the tank structure is adjustably mounted so that it can be shifted at a slight angle with respect to the axis of the helix and the rollers 40, 41 as shown in exaggerated form in FIG. 3. Thus in the device shown in FIG. 7 the tank structure is formed as one long body with partitions 5160 extending at right angles to the sides 61, 62. At the high speed of rotation of the stored helix 9 it is impossible to predetermine the angle of pitch of the wire coils so that no advantage is obtained by sloping the partitions 5160 at a slight angle different from 90. The tank structure 50 is, therefore, mounted on roller means 83, 84. In the apparatus shown one such roller means 83 or 84 is provided for each corner of tank structure 50 although two such devices at one end in combination with a pivoting structure at the opposite end could be employed or a larger number of such roller supporting means could be employed. Thus the tank structure is positioned at a slight angle with respect to the axes of rollers 40, 41 rather than parallel thereto and is adjusted to the proper position as illustrated in FIG. 3 after the helix shape has been developed. In the device shown, wedges 85 and 86 are employed to fix the tank structure in place when properly positioned. Since one or more of the tanks may include electrodes for anodic or cathodic cleaning or for electroplating or electropolishing, or ultrasonically vibrating means, etc., a sheet of insulating material 87 (such as synthetic rubber) is inserted between the roller means 83, 84 and the tank structure 50 to avoid leakage of electrical energy. More refined means may be employed to adjust the position of the tank structure.

The pickling liquid in tank 51 is maintained at 70- 100 C. by means of steam coils (not shown). The steam drawn from the coils is condensed to form hot water which is added as the make-up water for the rinsing baths. The final lime or borax coating bath is also preferably heated so that the wire never cools off after leaving the pickling bath 51. Thus, advantage is taken of the fact that the wire is heated in pickling bath 51 by not permitting the wire to cool until the heat can be employed to dry the coating applied to the wire.

FIG. 6, in addition to illustrating that the helix-forming device 30 may be somewhat further spaced from the storage rollers 40, 41 than shown in FIGS. 4 and 5, illustrates another modification wherein two helices are formed simultaneously and fed to storage rollers 40, 41 simultaneously. The two wires, after being treated, are withdrawn at different angles from the discharge end of the rollers 40, 41 (not shown) in FIG. 6.

Positioned above the tank structure 50 is a hood 90 (see FIG. 7) which is preferably adjustable to various distances above the tank 50, by suitable means not shown. The hood contains one or more openings 91 to which exhaust pipes (not shown) are connected for withdrawing vapors evaporating from the system.

The tank structure and immersion method of treating the wire is eminently suited for the inclusion of ultrasonic means to promote cleaning and/or electrochemical treatment. For example, ultrasonic units of the type which are available in sealed containers can be introduced into one or more of the treatment baths.

EXAMPLE 1 FIGS. 1 and 2 disclose an arrangement for pickling steel wire wherein the wire from bundle 10 is passed over guide rollers 11, 12, through scale breaker 13, 14, straightening unit 15, 16 and onto the capstan and helix-forming device 31, 33. The helix formed by device 31, 33 expands and is fed onto storage rollers 40, 41. The helix is continuously fed along storage rollers 40, 41 below which the tank structure 50 is positioned. Approximately /3 of the suspended helix dip into the liquids held in the various partitions of tank structure 50. The helix after expansion is about 1 meter in diameter or 3.1 meters in circumference. (Depending on the wire, the expansion may be about 1530% of its diameter, for example.) The first compartment 51 is about 125 inches long; the turns of the helix are spaced approximately 1 inch apart (center-to-center) so that 125 turns of the helix are simultaneously entering and leaving the pickling liquor in the bath 51 and over 375 meters of wire are being simultaneously treated. The liquid in bath 51 is heated to 70- 100 C. by means of steam coils (not shown). At a speed of wire movement of 215 meters per minute the wire is under acid treatment for less than 1.8 minutes. This amount of treatment fully removes scale which has been cracked in scale breaker 13, 14. Tanks 52, 53, 54, 55, 56 and 57 are water rinsing tanks, the first containing 4 turns of the helix, tank 57 being shown as slightly larger than the others and containing 6 turns of the wire. Tank 58 contains a hot lime, borax or phosphate solution to coat the wire with a thin layer of lime, borax or phosphate, respectively. Preferably, the aqueous liquid in tank 58 is at nor near the boiling point and the wire as it reaches said bath is still hot from the pickling bath treatment. On leaving tank 58 the wire helix passes through empty tanks 59 and 60 wherein excess liquid from tank 58 is discharged and the surface coating liquid is rapidly evaporated from the hot wire leaving a thin film of the desired lime, borax or phosphate coating. For subsequently drawing the wire, a layer of lime, etc. is essential to hold the lubricant and provide a barrier film between the wire and the surface of the drawing dies. Heretofor, lime, borax or a similar coating has been applied by dipping the coils in an aqueous solution thereof and then baking in an oven to evaporate the water. Such a process produces excess lime on the surface which is discharged as dust in the atmosphere. In the process described in this example, no oven drying is necessary because at least the acid pickling bath 51 rinses 52-58 and the coating bath 58, are run hot, the acid dissolution of the scale is exothermic further heating the wire so that the wire as it leaves bath 58 has a temperature near the boiling point of water. In addition, all excess droplets of water are discharged in compartments 59 and 60 so that only the thin layer of water on the surface has to be evaporated.

The incorporation of the scale cracking device 13-14 into the system, as already stated, is of especial advantage because it reduces the cost of the acid without having to be perfect. It has been found, for example, that when operating with sulfuric acid at 70 C. without the scale removing device 13-14, the requirement for acid is about 20 kg. of acid per ton of wire treated. By the inclusion of device 13-14, the amount of acid is only 2 kg. per ton of wire. Similar savings have been noted with hydrochloric acid. Thus not only is there a saving in the amount of fresh acid required by the process but about of the normal waste recovery or disposal of used pickling liquors is saved.

The water in compartments 52-57 is fed countercurrent. Fresh water being added to compartment 57 and being fed consecutively to compartments 56, 55, 54, 53 and 52. Eventually all the drag-out acid from compartments 51 is conducted back to compartment 52 and the wash water from compartment 52 is fed to compartment 51. Since the pickling bath in 51 is run hot, being heated by steam heat exchange coils, the hot water drawn from the steam heating equipment for the bath 51 or other heated baths provides hot, pure, make-up water for the last water rinse bath 57. Thus, no recovery process for contaminated wash water is required. The acid solution of bath 51 is circulated, iron compounds are removed and acid is added as needed before recirculation but, as stated above, only about 2 kg. of acid per ton of wire is required when the mechanical scale remover 13, 14 is incorporated into the system and only this reduced amount of acid is treated for recovery or waste disposal.

EXAMPLE 2 FIG. 8 illustrates a successful high speed process for descaling steel wire. In the bath structure shown, the first descaling bath contains about loops of the helix, is followed by six smaller descaling baths which may contain the same or different descaling liquids at the same or different temperatures. Where the baths contain the same descaling solution, the liquids thereof can be fed counter-currently with respect to the direction of movement of the wire by providing openings for flow of liquid from one bath to the next of a series of baths, the openings being progressively lower from the last bath to the first thereof. The descaling baths in all the processes are advantageously operated at temperatures of 70100 C. and lose water by evaporation; the first rinsing bath is allowed to overflow into the last descaling bath to make up for water lost by evaporation. Liquid is withdrawn from the main descaling bath continuously or from time to time, so that salts from the descaling reaction can be removed therefrom and so that the eifectiveness of the pickling liquid can be restored and reintroduced into the bath.

Besides the effects of improved scrubbing as shown with the steel rod of Example 1, there is an improvement in resultant properties of the scale-free product owing to the fact that each region of the steel wire is in contact with the liquid for a limited time only and hydrogen embrittlement is, therefore, avoided. In this process, the wire is forwarded at speeds of 4 meters/sec. or over 7 tons per hour for a wire. About 130 loops dip in and out of the hot descaling bath during the treatment in about 70 seconds which is only a small fraction of the time that the wire is in contact with the acid in the standard batch processes.

EXAMPLE 3 Substantially the same process as disclosed in Example 1 or 2 is employed for the pickling of copper rod. It is not always possible to feed the softer copper rod at as fast a speed as the steel wire. Thus a copper rod is fed into a main pickling bath and one or more subsequent pickling baths, containing a 10-20% copper sulfate pickling solution at 70 C. The wire is coiled and fed at a speed of about 240-300 ft/min., each portion of the wire is passed through the pickling bath 130 times. The agitation and scrubbing which this speed of feeding in and out of the bath effects results in better cleansing than can be obtained by the batch type process. The scrubbing action created by this high speed also unexpectedly removes the greater part of wet copper dust which ordinarily sticks to the surface of copper rods pickled by the batch process, which dust, a monovalent copper oxide, cannot be removed by normal chemical treatment. This monovalent copper oxide greatly impairs the quality of drawn copper wire. Empty baths are provided along the series to collect drag-out liquid, such liquid being thrown ofi? of the wire by centrifugal force. Approximately 3 tons per hour of copper rod are pickled by this process.

Although the invention has been described in Examples 1-3 with special reference to copper and steel wires, it will be understood that all wires prepared by a hot rolling process or a process which includes annealing, have a hard crust which includes a layer of oxides which must be removed before the wire is drawn to increase die life, drawa'bility of the wire and the quality of the finished wire. The term pickling is a generic term for all processes of removing the oxide and/ or crust from wires and similar strip material regardless of the metallic composition of the wire.

The features and principles underlying the invention described above in connection with specific exemplifica tions will suggest to those skilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be limited to any specific feature or details thereof.

I claim:

1. A process for continuously pickling wire which has an oxide or heat scale layer and is in strand form, which process is of the type wherein the wire is passed through at least one pickling bath in the form of a helix, comprising feeding the wire in the form of a helix in and out of said pickling bath a multiplicity of times at a speed of at least 50 meters/min, whereby removal of the heat scale layer by pickling liquid is aided by the continuous in and out movement of the wire and the scrubbing action produced by the friction between the wire and the bath at said high feed rate, and continuously collecting the wire outside of said pickling bath.

2. The process as claimed in claim 1 wherein said process comprises feeding the wire through a plurality of adjacent pickling baths, and feeding the pickling liquid counter-currently, with respect to the direction of movement of the wire, from one bath to the next.

3. The process as claimed in claim 1 comprising passing the wire through at least one water rinsing bath, thence through at least one empty bath to collect dragout liquid from the rinsing bath.

4. The process as claimed in claim 1 comprising mechanically breaking the scale before passing said wire through said pickling bath.

5. The process as claimed in claim 1 comprising passing the wire through a plurality of water rinsing baths after pickling and feeding the water counter-currently in said baths.

6. The process as claimed in claim 5 comprising ultrasonically agitating at least one of the treating and rinsing liquids of said baths as an aid in cleaning the surface of the wire.

7. The process as claimed in claim 5 comprising operating said pickling bath at a temperature of 70-100 C.

8. The process as claimed in claim 7, comprising passing the wire through the water rinse bath while maintaining the wire at a temperature of about 70-100" C. as imparted thereto by said pickling bath, and then through a coating bath selected from the group consisting of aqueous lime, borax, and phosphate coating baths, and thereafter passing at least one turn of the wire helix through an air space whereby to remove excess liquid therefrom and dry the coating thereon with the aid of the heat content of said wire.

9. The process as claimed in claim 7, wherein said water rinsing baths are operated hot thereby promoting evaporation of water from said rinse baths, and comprising feeding the wire through a series of pickling baths operated at 70-100 C., and feeding the aqueous liquid from the first rinsing bath directly into the last of said pickling baths.

10. A process for continuously pickling a plurality of parallel wires which have an oxide or heat scale layer and are in a strand form, which process is of the type wherein each of said wires is passed through at least one pickling bath in the form of a helix, comprising feeding each of said wires in the form of a helix in and out of said pickling bath a multiplicity of times at a speed of at least 50 meters/min, whereby removal of the heat scale layer by pickling liquid is aided by the continuous in and out movement of the Wires and the scrubbing action produced by the friction between the wires and the bath at said high feed rate, and continuously collecting the wires outside of said pickling bath.

References Cited UNITED STATES PATENTS 2,927,871 3/1960 Mancke et a1. 134-15 3,066,084 11/1962 Osterman et a1. 134-15 FOREIGN PATENTS 210,704 8/1960 Germany.

MORRIS O. WOLK, Primary Examiner BARRY S. RICHMAN, Assistant Examiner US. Cl. X.R. 134-15, 41, 42

Images