GB2124121A - Dry type continuous wire drawing process and machine - Google Patents

Abstract

A dry type continuous wire drawing process and machine 20 which can enhance productivity by conducting in- line a wire drawing operation, including the steps of flaw detection and wire repair. The wire 11 to be drawn is mechanically descaled using a descaling unit 26 and is then coated with a lubricant. The wire thus coated is drawn through a drawing die 38. At the coating step, the wire is first coated with lime powder in a bath 28 and then with metallic soap in baths 30, 32. After the drawing operation, any flaw in the surface of the wire is detected by a flaw detector 40. The position of such a surface flaw is identified from the running speed or distance of the wire and the detecting instant. Any such surface flaw located is removed by a flaw remover 42 if possible. The resultant wire is wound up on a take-up roller 44. Any surface flaw which cannot be removed is marked. An internal defect in the drawn wire is detected using ultrasonic waves. The internally detected portion is also marked. All of these steps are conducted in-line. <IMAGE>

Description

SPECIFICATION Dry type continuous wire drawing process and machine BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a dry type wire drawing machine for continuously drawing a wire rod or a steel bar (which will be shortly referred to as a "wire").

Description of the prior art In a general example of a secondary working operation for a wire to be cold-forged into bolts or nuts, the wire is pickled so that it may be descaled. Next, the descaled wire is treated with a lubricant and is then subjected to a primary drawing operation. After that, the drawn wire is annealed to spheroidize the cementite so as to give a high cold-forgeability. The wire once drawn is pickled and treated with a lubricant at a second stage and is then secondarily drawn by the so-called "skin pass".

In the prior art, the pickling treatment, the surfacing treatment for lubrication, and the lubricating treatment are conducted by the batch-type process, by which a coiled wire is hung by means of a C-shaped hook so that it may be consecutively immersed in and transferred to and from the respective treating liquid baths. As a result, the batch-type process suffers from problems: that the productivity is so low as to raise the cost; that an additional cost for disposing the respective treating liquids is high because the environmental pollution has to be considered; that satisfactory working circumstances are not always provided because the treatments are of the wet type; and that inspection of the product over the whole length is difficult.

Here, liquid zinc phosphate is used as lubrication surfacer of the prior art, and a liquid which is prepared by dissolving either powdered metallic soap or a mixture of lime and metallic soap is used as the lubricant.

However, the cost for this process is high. Moreover, the wire to be cold-forged is subjected to the surfacing treatment with a lubricant, i.e., zinc phosphate having an excellent lubricity although this lubricant is expensive, because the lubricant used for the drawing treatment effects, as it is, the lubrication required for the cold-forging treatment.

For the more and more severe requirement for qualities in recent years, on the other hand, flaw detection and repair of the drawn wire become more and more important treatments. Generally speaking, however, the in-line flaw detection and the automatic wire repair are so remarkably difficult that they have been conducted exclusively off-line. Once the drawn wire has been taken up, more specifically, its flaw is either subjected, at a finishing step, ta detection by the use of a nondestructive or destructive flaw detector or visually detected by human eyes if it is located in the surface. Then, the flawed portion is manually repaired by means of a grinder or the like.Despite of this fact, the off-line method of the prior art is so inefficient and uneconomical that it is tremendously troublesome, that spaces for the facilities are additionally required, and that the transporting works are complicated.

Upon elimination of the aforementioned surface flaw, on the other hand, it is being recently developed that the flawed surface portion is cut only a predetermined length all over the circumference, in view of the fact that the yield is reduced by the general example of the prior art because the wire is either peeled off its whole length over the whole circumference by means of a die or cut by means of a cutting tool on the same principle as that of a lathe. Despite of this development, reduction in the yield cannot be avoided because the wire is cut all over the circumference even partially of the longitudinal direction.

The Inventors have succeeded in completing the present invention by earnestly repeating the experiments and researches while aiming at, as has been described hereinbefore: a first target that the batch-type treating process should be replaced by the continuous drawing process because it has a problem in efficiency and so on; a second target that the dry type process is desired from the standpoint that the wet type process cannot provide satisfactory working curcumstances but raises the cost for the facilities so that it is not acceptable; and a third target that the steps from the flaw detection to the repair are made in-line.

SUMMARYOFTHE INVENTION It is, therefore, an object of the present invention to provide dry type continuous wire drawing process and machine which are enabled to retain satisfactory working circumstances, while eliminating the problem of disposal of waste liquids, and to enhance the productivity to reduce the cost by continuously conducting the wire drawing treatment.

According to a feature of the present invention, there is provided a dry type continuous wire drawing process comprising: the step of descaling a wire to be drawn; the step of coating the descaled wire with a lubricant; and the step of drawing the lubricant-coated wire through a drawing die, wherein the improvement resides: in that the descaling step includes a mechanical sub-step of conducting the descaling treatment in a mechamical manner; and in that the lubricant-coating step includes a sub-step of coating the descaled wire with lime powder, and a sub-step of coating the lime-coated wire with metallic soap powder, whereby all the three major steps are conducted under dry and continuous conditions.

According to another feature of the present invention, there is provided a dry type continuous wire drawing process comprising the step of running a wire to be drawn, which is rewound from a pay-off stand, on a line including: the step of mechanically descaling the wire being run; the step of coating the surface of said wire with a powdered lubricant surfacer; the step of coating the surfacer-coated wire with a powdered lubricant; the step of drawing the lubricant-coated wire through a drawing die; the step of detecting a flaw in the surface of the drawn wire; the step of locating the surface flaw from the running speed or distance of the drawn wire and the detecting instant of the surface flaw and removing the located surface flaw; and the step of winding up the drawn wire.

According to still another feature of the present invention, there is provided a dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire; lubricating surfacertreating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubrication treating means; a drawing die for drawing the wire which has been subjected to the lubrication; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; and take-up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

According to a further feature of the present invention, there is provided a dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire; lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubrication treating means; a first drawing die for drawing the wire which has been subjected to the lubrication; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said surface flaw detectorforsending a repair signal to said automatic repairing means; a second drawing dieforfurther drawing the repaired wire; and take-up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

According to a further feature of the present invention, there is provided a dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire; lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubrication treating means; a first drawing die for drawing the wire which has been subjected to the lubrication; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; a second drawing die for further drawing the repaired wire; a second surface flaw detector for detecting the surface flaw left in the repaired wire; an unrepaired flaw marker for marking the unrepaired flaw portion of said wire in response to an instruction from the control unit which is made receptive of the signal from said second surface flaw detector; and take up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure { is a schematic view showing the arrangement of a dry type continuous wire drawing machine exemplifying the present invention; Figure 2 is an enlarged schematic section showing the construction of the lubricant layers of a wire to be drawn according to the present invention; Figure 3 is similar to Figure 1 but shows another embodiment of the present invention; Figure 4A and 4B are schematic views showing the construction of a line downstream of the wire drawing step and upstream of the drawn-wire taking-up step, the former corresponding to the line having only the primary drawing step whereas the latter corresponding to the line having the primary and secondary drawing steps;; Figure 5 is a schematic section illustrating the repaired wire which is to be secondarily drawn; Figures 6A and 6B are similar to Figures 4A and 4B but show other embodiments of the present invention; and Figures 7A and 7B, 8A and 8B, 9A and 9B, and lOA and 10B are also similar to Figures 4A and 4B, respectively but show other embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Since the present invention contains a number of preferred embodiments, the description will be made first upon the basic construction upstream of the primary drawing step and then upon a variety of modes of steps downstream of the primary drawing step.

Referring first to Figure 1, a wire 11 to be drawn is held in such a state on a pay-off stand 22 of the dry type continuous wire drawing machine 20 according to the present invention that it is wound thereon in a coiled shape, and is then fed to a drawing line. This feed is performed by guiding the leading end of the wire 11, which has been shapened at a preceding step. The wire 11 thus unwound from the pay-off stand 22 is guided to run via a leveler 24 of vertical and horizontal (i.e., V-H) construction through a shot blaster 26 acting as the descaling means. In this shot blaster 26, suitable shot particles and their suitable shooting density are so set that an oxide film and soon may be peeled from the surface of the wire 11.

Next, the wire 11 is guided through a lubricant surfacer bath 28, a reinforcing lubricant bath 30 and a pre-die lubricant bath 32 which are arranged in tandem in the recited order and equipped with at their respective exits with a lubricant surfacer applying die 34, a reinforcing lubricant applying die 36 and a wire drawing die 38. These baths 28 and 32 are respectively filled up with lime powder as the lubricating surfacer, the reinforcing lubricant such as sodium stearate, and the pre-die lubricant such as a mixture of calcium or sodium stearate and slaked lime.

The wire 11 passes through the lubricating surfacer bath 28 after it has been descaled, and is then guided through the lubricating surfacer applying die 34. During this passage, the wire 11 is coated with the lime powder 11A (Figure 2). Then, since the bore diameter of the applying die 34 is predetermined at a value slightly larger than that of the target wire 11, both the lime powder 1 1A, which has just been applied, and the surrounding lime powder are in turn squeezed between the bore wall and the surface of the wire 11, while this wire 11 is running through the bore of the applying die 34, so that the lime powder 1 1A is pressure-applied to the surface of the wire 11.The lime powder 11 A functions as the surfacer of lubricants 11 B and 11 C, as shown in Figure 2, and to enhance the coating properties of both the reinforcing lubricant 11 B and the pre-die lubricant 11 C, which are to be subsequently applied. On the other hand, not only the slaked lime but also quick lime can be used as the lime powder. However, the slaked lime is preferred because hygroscopicity of the quick lime frequently raises a handling problem. The particle size of the lime powder is desired to be not smaller 2 microns.

Next, the wire 11 passes through the reinforcing lubricant bath 30 and the reinforcing lubricant applying die 36. During these passages, the reinforcing lubricant 11 B is pressure-applied likewise the aforementioned case of the lime powder 11 A to the surface layer of the lime powder 11 A which has already been pressure-applied to the wire 11. Sodium stearate is used as the reinforcing lubricant 11 B. If the sodium stearate used has a particle size not larger than 2 microns, its coating density is reduced by the so-cailed "Tunnel effect" resulting from the passage through the fluffy powder so that the lubricating effect becomes insufficient. It is, therefore, preferable that the particle size of the sodium stearate be at least 2 microns.

On the other hand, the application of the reinforcing lubricant 11 B should preferably be performed but can be omitted in the case of drawing a wire having a low strength.

After that, the wire 11 is guided into the pre-die lubricant bath 32. This bath 32 is filled up with a mixed lubricant of calcium or sodium stearate and lime as that pre-die lubricant 11 C, which is to be pressure-applied to the surface layer of the wire 11. Next, the wire 11 is subjected to a (primary) drawing treatment at a predetermined working ratio by the action of the drawing die 38.

Here, with closer refenece to Figure 2, the lubricating surfacer 11A, the reinforcing surfacer 11 B and the pre-die lubricant 11C will be described in more detail in the following. The lubricating surfacer 11A is slaked lime having a particle size not smaller than 2 microns, as has been described hereinbefore. On the other hand, the reinforcing lubricant 11 B is selected from the so-called "metallic soap" group consisting of calcium, sodium, zinc and aluminum stearate. Moreover, the pre-die lubricant 1 C is a mixed one of the calcium or sodium stearate of the metallic soap, and slaked lime.The mixing ratio of the stearate and the remainder, i.e., and the slaked lime is usually 50 and 80 % (in weight) forthe former and 20 to 50 for the latter and can change the melting point of the lubricant 11 C as a whole if it is varied. On the other hand, the coating density is at least 5 g/m2 for the lubricating surfacer 11 A, at least 1 g/m2 for the reinforcing lubricant 11 B, and at least 2 g/m2 for the pre-die lubricant 11 C and has to be totally set at least 10 g/m2.

In the embodiment thus far described, the dies 34,36 and 38 are exemplified by bored ones but may be replaced by roller ones.

The wire 11' having been drawn is guided to enter a flaw detector 40 such as a rotary probe type eddy current flaw detector, as shown in Figure 1. The wire 11' has not only its intrinsic material flaw but also a handling flaw and/or a die flaw which has been caused by the seizure or the like when the wire 11' is passing through the drawing die 38. Thus, the flaw of any type is detected continuously in-line by the flaw detector 40 so that the flawed portion may be removed by a flaw remover 42 in response to a flaw detection signal coming from that detector 40.

The wire 11' thus having been subjected to a series of treatments is wound up by the action of a take-up roller 44. The wire 11' is then transferred to a subsequent step for a secondary drawing operation. However, the wire 11' may be shipped without any treatment as a wire to be cold-forged, if it is used for applicaitons in which no strict quality requirement is made as to the surface skin and so on.

In the foregoing embodiments, the shot blaster 26 is used as the mechanical descaler for mechanically effecting the descaling operation. As shown in Figure 3, on the contrary, the shot blaster 26 may be replaced by a roll bender 24'. This roll bender 24' has a function to repeatedly bend and elongate the wire 11' so that the scale layer may be fissured and peeled off, and acts as the ieveler. The drawing weight percentage of the roll bender 24' is suitably selected. Incidentally, it is quite natural that the roll bender 24' and the shot balster 26 may be used together as the mechanical descaler.

The present apparatus is of the dry type and performs the continuous drawing treatment. As is different from the conventional batch-type treating system which is inefficient and uneconomical, the continuous wire drawing system according to the present invention can enjoy a line speed as high as about 120 m/min., for example, so that the treating efficiency can be remarkably improved.

On the other hand, if the flaw detector 40 and the flaw remover 42 are disposed on the continuous wire drawing iine, quick treatments can be achieved, as is different from the batch-type system of the prior art in which may flaw detecting and repairing troubles are incorporated.

The present invention adopts the dry type in the case of the continuous wire drawing treatment. There is known to the prior art the concept per se of disposing a dry type pre-die lubricant upsteam of the drawing die so that the wire may be drawn after it has been coated with that lubricant. On the other hand, however, it is not known already that the treatment with the lubricating surfacer and, if necessary, the treatment with the reinforcing lubricant be conducted in a dry manner. According to the present invention, moreover, the lime powder is used as the lubricating surfacer. In the prior art, zinc phosphate, which is expensive but is excellent in lubricating properties, is used as the lubricating surfacer. The zinc phosphate cannot be applied to the present invention which resorts to the dry type treatment, because it is liquid.Therefore, the lime powder is used in place of the zinc phosphate. The drawn wire, which is prepared by the surfacing treatment with the lubricant of the lime powder and by the dry type lubrication, is not always superior, as for the conditions of the surface skin, to the drawn wire which is prepared by the wet type lubrication, which is conducted as a representative of the prior art by a series of the pickling step - the surfacing step with zinc phosphate - the lubricating step with the mixture of lime and metallic soap. Despite of the fact, the primary drawing treatment is a preliminary one preceding a secondary drawing treatment, and the conditions or the like of the surface skin can be improved before long by the secondary drawing step. Here, the simplified process according to the present invention can sufficiently achieve the aforementioned objects and is rather rational.

The best advantage that can be attained thanks to the dry type system is the abilities of shortening the line length and reducing the cost for the facilities. For example, it is intended to conduct the continuous treatment by the wet type system, the surfacing treatment with the lubricant and the lubricating treatment require a considerable reaction time for attaining a predetermined film thickness so that accordingly elongated facilities are indispensable. On the contrary, the dry type system can enjoy the aforementioned advantage because it requires at most the small-sized baths and the dies therefor. Moreover, the working circumstances are improved because no acid is used.Generally speaking, still moreover, either the sodium stearate or the mixture of lime and calcium stearate is of powdered type and is dissolved according to the prior art before it is used for the wet type treatment. In the dry type system, on the contrary, the above-specified material may be used, as it is, so that it is remarkably excellent in handling.

As has been described hereinbefore, the process of the present invention can conduct the drawing operations remarkably economically partly because these operations are performed in dry and continuous manners and partly because the surfacing treatment with the lubricant is performed by means of the inexpensive lime powder. Therefore, the process of the present invention can enjoy an advantage that the lubricating surfacer and the reinforcing lubricant have excellent coating properties because they are squeezed and pressure-applied by means of the dies.

The present invention will be described in detail in the following in connection with the examples thereof.

Example 1 The drawing operation was conducted by using the wire drawing line or facilities having a construction similar to those of Figure 1. The wires used was an As-rolled material made of 0.4 % C carbon steel and having a diameter of 14.0 mm. This material wire was drawn under the following conditions: (a) Descaling condition Shot blast was conducted by shooting steel balls having a mean diameter of 0.3 mm with a shooting density of about 300 kg/m2.

(b) Lubricaling condition The surfacing operation with a lubricant was conducted by the use of lime powder having a means particle diameter of 15 microns. The reinforcing lubrication was conducted by the use of sodium stearate having a means particle diameter of 12.5 microns. The pre-die lubrication was conducted by the use of a mixture of lime and calcium stearate.

(c) Drawing condition A drawn wire having a diameter of 11.6 mm was prepared art a running speed of 41 m/min. and in a reduction of area of 26.2 % by using a drawing die having a die angle of 2 a = 20 degrees.

(d) Flaw detecting condition The flaw was detected at a phase angle of 130 degrees and with a frequency of 64 KHz by the use of a rotary probe type eddy current flaw detector.

The comparison between the drawing system of the present invntion of a reference, in which only the pre-die lubrication was conducted, is presented in Table 1. In this Table, the die life indicates the drawing weight of the wire until the drawing die seizes, and freedom of the seizure means excellent lubrication of the wire.

TABLE 1 Lubricating condition Die life Ref.1 only C 1,000- 2,000kg Test 1 A + C 30,000 - 45,000 kg Test 2 A + B + C 50,000 - 70,000 kg Wherein A: Surfacing treatment for lubrication (with lime) B : Lubricating treatment for reinforcement (with sodium stearate) C : Pre-die lubricating treatment In view of the above Table 1, it is concluded that the productivity of drawing could be improved according to the present invention.

Example 2 The drawing operation was conducted by the use of the line construction similar to that of Figure 3. The bending roll unit used was constructed such that two series of five rolls having a diameter of 90 mm were arranged vertically and horizontally. The drawing weight of the wire by that roll bender was 10 %. On the other hand, the roller die was used. The results are tabulated in Table 2.

TABLE 2 Lubricating condition Die life Ref.2 only C 1,500 - 3,000 kg Test 3 A + C 40,000 - 60,000 kg Test 4 A + B + C 55,000 - 70,000 kg wherein: A, B and C indicate those of the Table 1.

From the above results, it is found that the die life was improved as compared with that of the shot blast system of Example 1. This improvement was caused by the back tension which had been generated by the bending operation. By this operation of the bending roll, more specifically, a tension in the direction opposite to the running direction was applied to the wire 11. As a result, the surface pressure to be exerted upon the die 38 was so reduced that the life was improved.

Example 3 The line construction was similar to that of the Example 2, but the drawing weight of the wire by the roll bender 24' was 32 %, and the drawing step was conducted simultaneously with the descaling step. In operation, the material wire having a diameter of 14 mm was drawn to have a diameter of 12.2 mm in a reduction of area of 24 %. As a result, another drawing step using a bored die reduced the area of the wire by about 10 %, that it to say, the wire having the diameter of 12.2 mm was drawn to one having a diameter of 11.6 mm. The results are presented in Table 3 and reveal that the die life was remarkably improved thanks to further increase in the back tension.

TABLE 3 Lubricating condition Die life Ref. 3 only C 5,000 - 10,000 kg Test 5 A + C 70,000 - 90,000 kg Test 6 A+B+C 100,000 - 120,000 kg wherein: A, B and C also indicate those of Tables 1 and 2.

On the other hand, the wire thus drawn has not only its intrinsic material flaw but also a hadling flaw and/or a die flaw which has been caused by the seizure or the like while passing through the drawing die. Of the material flaws, moreover, an internal one cannot be repaired. Still moreover, some surface flaws can be neither be repaired nor be suitable for the handling.

The drawn wire is treated along an identical line by the following modes according to the present invention.

Figure 4A shows another embodiment of the present invention. A wire speed meter 46 is provided to meter the running speed of the aforementioned wire 11' which has been drawn. The speed signal of the wire speed meter 46 is fed to a control unit 48 so that it may be used for the speed control through a later-described take-up roller. Downstream of the speed meter 46, there is disposed a surface flaw detector 50 which is of an eddy current type or the like. The surface flaw state signal from that surface flaw detector 50 is also fed to the control unit 48 so that an automatic repairer 52 disposed at the subsequent step of the surface flaw detector 50 may operate to eliminate the flawed surface portion in accordance with an instruction of the control unit 48. The wire thus repaired is wound up on the take-up roller 54.Next, the wire 11' thus wound is transferred to a subsequent step for a secondary drawing operation, as will be described with reference to Figure 4B. As shown in Figure 4B, the repaired wire 11' is further subjected to the secondary drawing treatment to have its surface skin improved by means of a secondary drawing die 56 until it is wound up on the take-up roller 54. In an alternative, the once-drawn wire 11' may be shipped, as it is, for a cold-forging treatment if it is applied to a usage in which no strict reguirement for the quality of the surface skin is required.

Here, the speed or distance meter 46 meters the running speed or distance of the wire 11' having been primarily drawn. The position in which the speed or distance meter 46 is to be disposed may be basically be located, as seen from Figures 4A and 4B, downstream of the drawing die 38 (which should be referred to Figures 1 and 3) or the surface flaw detector 50. Alternatively, the running speed of the wire 11' may be metered in terms of the number of revolutions per minute of the take-up roller 54. The wire running speed may be arbitrarily selected but is set at 60 to 80 m/min. for a wire diameter of 10 to 15 mm, at 40 to 60 m/min.

for a wire diameter of 15 to 20 mm, or at 10 to 15 m/min. for a wire diameter of 20 to 25 mm, for example.

The surface flaw detector 50 may be exemplified by an ultrasonic one but is preferably embodied by an eddy current one in view of the points of its detecting power and stability. The flaw detector 50 not only locates the flaw, namely, detects the circumferentially angular position and the longitudinal position of the flaw but also meters the depth of the flaw or the like. In this instance, the longitudinal position of the flaw is judged by the control unit 48 on the basis of the signal coming from the speed meter 46.

The surface flaw thus detected is automatically repaired by the automatic repairer 52 in response to an instruction from the control unit 48. In the automatic repairer 52, a surface flaw repairing tool such as a honing stone, a belt grinder or a cutting, peeling or shaving too, or preferably the internal honing stone 52, as shown, is made to revolve around the drawn wire 11' so that it may be promptly brought into abutment against the surface of the drawn wire 11' as soon as the flawed surface portion reaches the position of the internal honing stone 52. In case this repairing tool is circumferentially displaced from the position of the surface flaw, on the other hand, the repaireing operation is started after the repairing tool is turned into position.If necessary, a plurality of repairing tools may be disposed circumferentially of the drawn wire 11'.

Moreover, the repair range is made slightly larger than the length, depth and width of the surface flaw under consideration. From the standpoint of the yield, still moreover, the repair should be conducted not all over the length and circumference of the surface flaw bur only that flawed surface portion in the circumferential direction.

When in operation, let the case be considered in which the repairer 52 cannot follow the running speed of the wire 11'. If a surface flaw is detected, the take-up roller 54 is decelerated or halted through the speed control circuit of a winding motor accompanying the take-up roller 54 in response to an instruction of the control unit 48, at the instant when that flawed portion reaches the repairer 52, so that the wire sending operation may be decelerated or interrupted to facilitate the repairing operation. After this repair, the wir'e running speed is returned to its original value.

Turning now to Figure 5, since the surface of the wire 11' has its portion a removed up to a depth of about 0.1 to 0.5 mm, there is left a scar 11 'a unless otherwise treated, which is not satisfactory for the intended application of the product. In order to eliminate that repair scar 11 'a so that the wire 11' may have a uniform diameter all over its circumference, therefore, the wire 11' once drawn is secondarily drawn by means of the secondary drawing die 56. This secondary drawing die 56 has a construction similar to that of the primary drawing die 38 and may be of bored or roller type. Before this secondary drawing step, the wire 11' can be subjected, if necessary, to a treatment with a lubricant. That secondary drawing die 56 is disposed downstream of the automatic repairer 52.In case an internal defect is to be detected and marked, as in later-described embodiments of the present invention, or in case such one of the surface flaws detected by the surface flaw detector 50 as cannot be automatically repaired is to be marked, it is necessary that the secondary drawing die 56 be positioned before the marking step, namely disposed upstream of the internal defect marker or the unrepaired flaw marker. This is because there is a fear that the mark may possibly be erased by the drawing operation if the marking operation is conducted before the drawing operation.

Figure 6A shows another embodiment of the present invention. In case the flawed surface portion detected by the flaw detector 50 has a depth exceeding about 0.2 mm or a number of flaws existing in an identical portion so that it is not within the capacity of the automatic repairer 52, it is either repaired as deeply as possible or left unrepaired and marked by an unrepaired flaw marker 58 in response to an instruction of the control unit 48. The flaw or flaws left unrepaired are repaired off-line after the wire 11' has been wound up.

In this instance, the unrepaired flaw marker 58 is desirably made to revolve around the drawn wire 11' so that it can cover the whole circumference. In an alternative, a plurality of unit markers are disposed in the circumferential direction so that the flaw or flaws may be marked by the unit marker or markers arranged at the corresponding sections. The marking operation can be conducted such that the flaws are discriminated either in different colors or by the rates of injection in accordance with the depths or kinds thereof.

In a modification shown in Figure 6B, the secondary drawing die 56 is interposed between the automatic repairer 52 and the unrepaired flaw marker 58.

Turning to Figure 7A showing a further embodiment of the present invention, an ultrsonic flaw detector 60 of submerged type is disposed downstream of the automatic repairer 52 thereby to detect an internal defect, which cannot be repaired, so that the internally defected portion may be marked by an internal defect marker 62 disposed downstream of the ultrasonic flaw detector 60, which has a construction similar to that of the unrepaired flaw marker 58 and which is made operative in response to an instruction of the control unit 48.

The internally defected portion thus detected is scrapped or unused after the drawn wire has been wound up.

Figure 7B shows a modification of the embodiment shown in Figure 7A. In this modification, the secondary drawing die 56 is disposed downstream of the automatic repairer 52, and an ultrasonic flaw detector 60 of submerged type is disposed donwstream of the secondary drawing die 56.

In the case of the above modification, the secondary drawing die 56 may alternatively be interposed between the ultrasonic flaw marker 60 and the internal defect marker 62, as is different from the arrangement exemplified in Figure 7B. In this particular case, the defected portion detected by the ultrasonic flaw detector 60 has to be memorized by the control unit 48, and the drawing weight of the wire drawn by the secondary drawing die 56 has to be calculated so that such a surface portion of the wire 11' as corresponds to the aforementioned defected portion may be marked.

Figure 8A shows a further embodiment of the present invention, which is different from the line of Figure 7A in that the unrepaired flaw marker 58 is interposed between the automatic repairer 52 and the ultrasonic flaw detector 60.

Turning to Figure 8B showing a modification of the embodiment of Figure 8A, the unrepaired flaw marker 58 is interposed between the secondary drawing die 56 and the ultrasonic flaw detector 60, as is different from the line of Figure 7B.

Alternatively to the illustrated arrangements, the unrepaired flaw marker 58 may be disposed downstream of the ultrasonic flaw detector 60 whereas the secondary drawing die 56 may be interposed between the automatic repairer 52 and the ultrasonic flaw detecor 60 or the unepaired flaw marker 58. The drawing weight of the wire 11' has to be taken into consideration during the marking operation by the unrepaired flaw marker 58 in the former case and during the marking operations by the unrepaired flaw marker 58 and the internal defect marker 62 in the latter case.

Figure 9A shows a further embodiment of the present invention, in which a second surface flaw detector 50' is disposed downstream of the automatic repairer 52 so that it may detect whether or not there is a portion left unrepaired by the automatic repairer 52. The portion, if left unrepaired, is indicated by the unrepaired flaw marker 58.

In Figure 9B showing a modification of the embodiment of Figure 9A, the second surface flaw detector 50' is disposed downstream of the automatic repairer 52 and the secondary die 56 so that it may detect whether or not there is any flaw left unrepaired by the automatic repairer 52 and so that the unrepaired flaw, if any, may be indicated by the unrepaired flaw marker 58.

Figure 1 OA shows a further embodiment of the present invention, in which the ultrasonic flaw detector 60 and the internal defect marker 62 are added, downstream of the unrepaired flaw marker 58, to the line having a construction similar to that of the embodiment of Figure 9A.

Figure 1 OB shows a modification by which the secondary drawing operation is conducted in the embodiment of Figure 1 OA. In the modification of Figure 1 OB, the ultrasonic flaw detector 60 and the internal flaw marker 62 are also added, downstream of the unrepaired flaw marker 58, to the line having a construction similar to that of Figure 9B likewise Figure 1 OA.

In the modifications of the embodiments of Figures 9A and 10A, too, the secondary drawing die 56 may be disposed in an arbitrary position likewise the other embodiments if it is disposed downstream of the automatic repairer 52 and upstream of the markers 58 and 62.

The embodiments of Figures 1 OA and 1 OB are the most proper because they can cover all the operating steps inclusive, but the embodiments of Figures 7A and 7B are the most practical if the cost for the facilities are taken into account.

In the embodiments thus far described, it is desired that the respective devices or components of the line be arranged in the shown order. However, it is possible, for example, to detect the surface flaw after the internal defect has been detected in advance or to change the position of the marker or markers. It is also possible to sumultaneously detect the internal defect and the surface flaw. This can be exemplified by the process resorting to the discriminatin of the waveforms of an ultrsonic flaw detecting signal.

Thus, according to the present invention, since the flaw detection and auromatic repair of the drawn wire are conduted in-line, it is possible not only to achieve reduction in the number of the repairing steps, spare of the space for installation and elimination of the transporting works but also to treat the drawn wire at a high speed so that a flawless wire can be shipped with remarkably effective warranty.

The present invention will be described in more detail in connection with the Examples 4 to 6 which are directed to the line having only the primary drawing step.

Example 4 The drawing operation was conducted by using the wire drawing facilities having a construction similar to those of Figures 1 and 7A. The wire used was an As-rolles material made of 0.4 % C carbon steel and having a diameter of 14.0 mm. This wire was drawn under the following conditions: (a) Descaling condition Shot blast was conducted by shooting steel balls having a mean diameter of 0.3 mm with a shooting density of about 300 kg/m2.

(b) Lubricating condition The surfacing operation with a lubricant was conducted by the use of lime powder having a mean particle diameter of 15 microns. The reinforcing lubrication was conducted by the use of sodium stearate having a means particle diameter of 12.5 microns. The pre-die lubrication was conducted by the use of a mixture of lime and calcium stearate.

(c) Drawing condition A drawing wire having a diameter of 11.6 mm was prepared at a running speed of 41 m/min. and in a reduction of area of 26.2 % by using a drawing die having a die angle of 2a=20 degrees and a bearing portion of a length of 0.5 d (wherein letter d designates the diameter of the die).

(d) Flaw detecting condition The surface flaw was detected at a phase angle of 130 degrees and with a frequency of 64 KHz by the use of a rotary probe type eddy current flaw detector. On the other hand, the internal defect was detected with a frequency of 20 MHz by the use of a submerged type ultrasonic flaw detector.

(e) Automatic repairing condition The automatic repair was conducted by dividing the circumference of the wire into thirty six sections and by reparing only the local section, in which the surface flaw is detected, with the inner wall of a rotary honing stone having a cylindrical shape.

The comparison between the drawing system of the present invention and a reference of the prior art, in which only the pre-die lubrication was conducted, is presented in Table 4. In this Table, the die life indicates the drawing weight of the wire until the drawing die seizes, and freedom of the seizure means excellent lubrication of the wire.

TABLE 4 Lubricating Die Flaw detecting condition life power (1) (2) Prior art only C 1,000 - 2.000 kg Inven- A+C 5,000- 5/100 mm 0.2 mm tion 1 1 6,000 kg Inven- A + B + C 10,000- 5/100 mm 0.2 mm tion 2 12,000 kg wherein: (1) indicates lower limit of depth of surface flaw detectable; and (2) indicates internal defect detectable.

wherein: A, Band C indicate those of the Table 1.

Incidentally, the results of investigating the coating density of sodium stearate for different mean particle diameters are presented in Table 5. The particles of the sodium stearate having a means diameter less than 2 microns were adversely affected by the so-called "tunnel effect" so that they could not coat the wire at a satisfactory density thereby to fail to meet the practicai purpose.

TABLE 5 Particle diameter Coating density 2 to 3 microns 0.8g/m2 5 to 7 microns 4.1 g/m2 In view of the foregoing Table 4, it is concluded that a drawn wire of high quality could be produced according to the present invention.

Example 5 The drawing operation was conducted by the use of the line having a construction similar to that of Figures 2 and 7A. The bending roll unit used was constructed such that five rolls having a diameter of 90 mm were arranged vertically and horizontally. The drawing weight of the wire by that roll bender was 10 %. On the other hand, the drawing die used was of roller type. The results are tabulated in Table 6.

TABLE 6 Lubricating Die life Flaw detecting condition power Bored die Roller die (1) (2) Prior art only C 1,500 - 100,000 3,000 kg 150,000 kg Inven- A+ C 7,500- 120,000- 5/100 mm 0.2 mm tion 1 9,000 kg 170,000 kg Inven- A+B+C 15,000 - 150,000 - 5/100 mm 0.2 mm tion 2 30,000 kg 200,000 kg wherein: A, B and C indicate those of the Table 1.

From the above results, it is found that the die life was improved as compared with that of the shot system of the Example 4. This improvement was acquired by the back tension which has been generated by the bending operation. By this operation of the bending roll, more specifically, a tention in the direction opposite to the running direction was applied to the wire 11. As a result, the surface pressure to be exerted upon the die was so reduced that the die life was improved.

Example 6 The line construction was similar to that of the Example 5, but the drawing weight of the wire by the roll bender was 32 %, and the drawing step was conducted simultaneously with the descaling step. In operation, the material wire having a diameter of 14 mm was drawn to have a diameter of 12.2 mm in a reduction of area of 24 %. As a result, another drawing step using a bored die (which was identical to that of the Example 4) reduced the area of the wire by about 10 %, that is to say, the wire having a diameter of 11.6 mm. The results are presented in Table 7 and reveal that the die life was remarkably improved thanks to further increase in the back tension.

TABLE 7 Lubricating Die Flaw detecting condition life power (1) (2) Prior art only C 10,000 20,000 kg Inven- A+C 50,000 - 5/100 mm 0.2 mm tion 1 60,000 kg Inven- A + B + C 100,000 - 5/100 mm 0.2 mm tion 2 120,000 kg Detaii description of the present invention will also be made in connection with Example 7 which is directed to the line having both the primary and secondary drawing steps.

Example 7 The drawing operation was conducted by using the wire drawing facilities having a construction similar to those of Figures 1 and 6b. The wire used was an As-rolled material made of 0.4 % C carbon steel and having a diameter of 16.0 mm. This wire was drawn under the following conditions: (a) Descaling condition Shot blast was conducted by shooting steel balls having a mean diameter of 0.3 mm with a shooting density of about 300 kg/m2.

(b) The surfacing operation with a lubricant was conducted by the use of line powder having a mean particle diameter of 15 microns. The reinforcing lubrication was conducted by the use of sodium stearate having a mean particle diameter of 12.5 microns. The pre-die lubrication was conducted by the use of a mixture of line and calcium stearate.

(c) Drawing condition A drawn wire having a diameter of 13. 5 mm was prepared at a running speed of 41 m/min. and in a reduction of area of 28.9 % by using primary and secondary dies having a die angle of 2a = 20 degrees and a bearing portion of a length of 0.5 d length (wherein letter d designates the common diameter of the two dies). Moreover, the distribution of the reduction of area at the primary and secondary drawing dies was set at 16 mm > 15 mm (i.e., a reduction percentage of 12 13.5 mm (i.e., a reduction percentage of 19 %) in diameter.

(d) Flaw detecting condition The surface flaw was detected at a phase angle of 130 degrees and with a frequency of 64 KHz by the use of a submerged type ultrasonic flaw detector. On the other hand, the internal defect was detected with a frequency of 20 MHz by the use of a submerged type ultrasonic flaw detector.

(e) Automatic repairing condition The automatic repair was conducted by dividing the circumference of the wire into thirty six sections and by automatically repairing only the local section, in which the surface flaw exists, with the inner wall of a rotary honing stone having a cylindrical shape.

The comparison between the drawing system of the present invention and a reference of the prior art, in which only the pre-die lubrication was conducted, is presented in Table 8. In this Table, the die life indicates the drawing weight of the wire until the drawing dies seizes, and freedom of the seizure means excellent lubrication of the wire.

TABLE 8 Lubricating Die Flaw detecting condition lifetime power (1) (2) Inven- A4C 20,000- 5/100 mm 0.2 mm tion 1 30,000 kg Inven- A+B+C 40,000- 5/100 mm 0.2 mm tion 2 50,000 kg wherein: A, B and C indicate those of the Table 1.

In view of the above Table 8, it is concluded that the productivity of drawing could be improved according to the present invention.

Moreover, the results of investigations of the repair scar removing effect by the secondary drawing step are tabulated in Table 9.

TABLE 9

0.05 mm 0.10 mm 0.15 mm 0.20 mm 0.25 mm 7% 0 0 0 0 0.01 mm 19% 0 0 0 0 0 Wherein (3): Flaw repair depth (a) (4): Area reduction by secondary drawing As is apparent from the above Table 9, it is found that the repair scar was sufficiently remedied by the secondary drawing operation, and that the repair scar reaching as deep as 0.5 mm could be completely removed if the reduction of area in the secondary drawing poeration exceeded 19%.

Thanks to the in-line secondary drawing operation, moreover, the reduction of area at each drawing die can be made so low that the die life can be remarkably elongated. At the same time, the skin of the drawn wire can be outstandingly improved, as compared with the system conducting only the primary drawing operation. Incidentally, the distribution of the reduction of area between the primary and the secondary drawing operations should be selected in accordance with the material used while considering tensile thinning of the finished wire (which is caused by the influence of the reduction of area of the primary drawing operation as a back tension upon the secondary operation).

Claims (35)

1. A dry type continuous wire drawing process comprising the steps of: (1) descaling a wire to be drawn; (2) coating the descaled wire with a lubricant; and (3) drawing the lubricant-coated wire through a drawing die.

wherein descaling step (1) includes a mechanical sub-step of conducting the descaling treatment in a mechanical manner; and in that the lubricant coating step (2) includes a sub-step of coating the descaled wire with lime powder, and a sub-step of coating the lime-coated wire with metallic soap powder, with all the steps (1) to (3) being conducted under dry and continuous conditions.

2. A wire drawing process as claimed in claim 1, wherein the mechanical descaling step (1) further includes a sub-step of shot-blasting surface of the wire to be drawn.

3. A wire drawing process as claimed in claim 1, wherein the mechanical descaling step (1) includes a sub-step of bending the wire to be drawn.

4. A wire drawing process as claimed in claim 1,2 and 3, wherein said lime powder has a mean particle diameter equal to or smaller than 50 microns.

5. A wire drawing process as claimed in claim 1,2,3 or 4, wherein the lime powder coating sub-step is conducted by running the wire to be drawn through a bath containing lime.

6. Awire drawing process as claimed in claim 5, wherein the lime powder coating sub-step is conducted by means of a lime coating die, which is fitted in the exit of said bath for allowing the wire to run and which has an internal diameter larger by 0.1 to 0.2 mm than the diameter of the wire to be drawn, so that the line coating sub-step may be ensured by running said wire through said lime coating die.

7. A wire drawing process as claimed in claim 1, wherein the coating density of the lime on the surface of the wire to be drawn is equal to or higher than 5 g/m.

8. A wire drawing process as claimed in any of claims 1 to 7, wherein the metallic soap coating sub-step is conducted by running the lime-coated wire through a bath containing metallic soap.

9. Awire drawing process as claimed in claim 8, wherein the metallic soap coating sub-step and the wire drawing step are incorporated into a single step by fitting said drawing die in the exit of a bath containing metallic soap for allowing said wire to run therethrough and by running the wire to be drawn through said drawing die.

10. A wire drawing process as claimed in any of claims 1 to 9, wherein the coating density of the metallic soap on the surface of the wire to be drawn is equal to or higher than 2 g/m.

11. A wire drawing process as claimed in any of claims 1 to 10, wherein the lubricating coating step (2) further includes the sub-step of coating the lime-coated wire with powder of sodium stearate before the metallic soap coating sub-step.

12. A wire drawing process as claimed in claim 11, wherein the powder of the sodium stearate has a mean particle diameter equal to or larger than 2 microns.

13. A wire drawing process as claimed in claim 11, wherein the sodium stearate coating sub-step is conducted by running the lime-coated wire through a bath containing sodium stearate.

14. A wire drawing process as claimed in claim 13, wherein the sodium stearate coating sub-step is conducted by means of a sodium stearate coating die, which is fitted in the exit of said bath for allowing the wire to run therethrough and which has an internal diameter larger by 0.1 to 0.2 mm than the diameter of the lime-coated wire, so that the sodium stearate coating sub-step may be ensured by running said lime-coated wire through said sodium stearate coating die.

15. A wire drawing process as claimed in claim 11, wherein the coating density of the sodium stearate on the surface of said lime-coated wire is equal to or higher than 1 g/m.

16. A dry tape continuous wire drawing process comprising: (1) the step of running the wire to be drawn, which is rewound from a pay-off stand, on a line including; (2) the step of mechanically descaling the wire being run; (3) the step of coating the surface of said wire with a powdered lubrication surfacer; (4) the step of coating the surfacer-coated wire with a powdered lubricant; (5) the step of drawing the lubricant-coated wire through a drawing die; (6) the step of detecting a flaw in the surface of the drawn wire; (7) the step of locating the surface flaw from the running speed or distance of the drawn wire and the detecting instant of the surface flaw and removing the located surface flaw; and (8) the step of winding up the drawn wire.

17. A wire drawing process as claimed in claim 16, wherein said line further includes: (9) the step of marking such one of the surface flaws detected at the step (6) as cannot be removed at the step (7).

18. A wire drawing process as claimed in claim 16, wherein said line further includes: (10) the step of detecting an internal defect in the drawn wire with ultrasonic waves; and (11) the step of marking the internally defected portion detected.

19. A wire drawing process as claimed in claim 16, wherein said line further includes; (12) the step of adjusting the winding speed in accordance with the surface flaw detection signal of said step (16)therebyto ensure the flaw removal of said step (7).

20. A wire drawing process as claimed in claim 16, wherein said line further includes: (13) the step of detecting again a surface flaw after said step (7) and marking the flawed portion detected.

21. A wire drawing process as claimed in claim 16, wherein the surface flaw removing operation of said step (7) is conducted by running said drawn wire through the bore of a ring-shaped internal honing stone so that said wire may be brought into contact with and ground by the internal wall of said honing stone.

22. A dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire; lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; a pre-die dry type lubrication treating means; a drawing die for drawing the wire which has been subjected to the lubrication; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; and take-up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

23. A dry type continuous wire drawing machine as claimed in claim 22, further comprising an unrepaired flaw marker for marking that one of the surface flaws detected, which cannot be automatically repared, in response to an instruction from said control unit.

24. A dry type continuous wire drawing machine as claimed in claim 22, further comprising: ultrasonic flaw detecting means for detecting an internal flaw of the repaired wire; and an internal defect marker for marking that surface of said wire, which corresponds to the internally defected portion, in response to an instruction from said control unit made receptive of the internal defect signal from said ultrasonic flaw detector.

25. A dry type continuous wire drawing machine as claimed in claim 24, further comprising: reinforcing-lubricant treating means having a pressure-applying die for pressure-applying a reinforcing lubricant to said lubricating surfacer; and a wire speed or distance meter for metering the running speed or distance of said wire, wherein said take-up means has such a variable take-up speed as can be decelerated, when a flaw is repaired, in response to the speed or distance signal of said wire speed or distance meter.

26. A dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire; lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubrication treating means; a drawing die for drawing the wire which has been subjected to the lubrication; a first surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire.

a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; a second surface flaw detector for detecting a surface flaw left in the repaired wire; an unrepaired flaw marker for marking the unrepaired flawed portion of said wire in response to an instruction from the control unit which is made receptive of the signal from said second surface flaw detector; and take-up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

27. A dry type continuous wire drawing machine as claimed in claim 26, further comprising: ultrasonic flaw detecting means for detecting an internal defect of the repaired wire; and an internal flaw marker for marking that surface of said wire, which corresponds to the internally defected portion, in response to an instruction from said control unit made receprive of the internal defect signal from said ultrasonic flaw detector.

28. A dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn therefrom; mechanical descaling means for removing scale from said wire.

lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubrication treating means; a first drawing die for drawing the wire which has been subjected to the lubrication; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; a second drawing die for further drawing the repaired wire; and take-up means for takin, up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

29. A dry type continuous wire drawing machine as claimed in claim 28, further comprising: an unrepaired flaw marker for marking the unrepaired flaw portion of said wire in response to an instruction from the control unit which is made receptive of the signal from said second surface flaw detector.

30. A dry type continuous wire drawing machine as claimed in claim 28, further comprising: ultrasonic flaw detecting means for detecting an internal flaw of the repaired wire; and an internal flaw marker for marking that surface of said wire, which corresponds to the internally defected portion, in response to an instruction from said control unit made receprive of the internal defect signal from said ultrasonic flaw detector.

31. A dry type continuous wire drawing machine as claimed in claim 30, further comprising: reinforcing-lubricanttreating means having a pressure-applying die for pressure-applying a reinforcing lubricant to said lubricating surfacer; and a wire speed or distance meter for metering the running speed or distance of said wire, wherein said take-up means has such a variable take-up speed as can be decelerated, when a flaw is repaired, in response to the speed or distance signal of said wire speed or distance meter.

32. A dry type continuous wire drawing machine comprising: a pay-off stand for supplying a wire to be drawn thereform; mechanical descaling means for removing scale from said wire; lubricating surfacer treating means having an applying die for pressure-applying a powdered lubricating surfacer to the surface of said wire; pre-die dry type lubricating treating means; a first drawing die for drawing the wire which has been subjected to the lubricating treatment; a surface flaw detector for detecting the surface flaw state of the drawn wire; automatic repairing means for removing the flawed surface portion of said drawn wire; a control unit made responsive to a surface flaw state signal from said surface flaw detector for sending a repair signal to said automatic repairing means; a second drawing dieforfurther drawing the repaired wire;; a second surface flaw detector for detecting the surface flaw left in the repaired wire; an unrepaired flaw marker for marking the unrepaired flaw portion.of said wire in response to an instruction from the control unit which is made receptive of the signal from said second surface flaw detector; and take-up means for taking up the repaired wire, wherein the components of said machine except said control unit are consecutively arranged in series.

33. A dry type continuous wire drawing machine as claimed in claim 32, further comprising: an internal defect marker for marking that surface of said wire, which corresponds to the internally defected portion, in response to an instruction from said control unit made receptive of the internal defect signal from said ultrasonic flaw detector.

34. A dry type continuous wire drawing process substantially as hereinbefore described with reference to the accompanying drawings.

35. A dry type continuous wire drawing machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.