WO2007023696A1

WO2007023696A1 - Direct heat treatment method and equipment of hot rolled wire rod

Info

Publication number: WO2007023696A1
Application number: PCT/JP2006/315924
Authority: WO
Inventors: Tatsuya Inoue
Original assignee: Sumitomo Electric Industries, Ltd.
Priority date: 2005-08-23
Filing date: 2006-08-11
Publication date: 2007-03-01
Also published as: JP2007056300A

Abstract

Direct heat treatment method and equipment of hot rolled wire rods which can increase the control width of a cooling rate. In the direct heat treatment method of hot rolled wire rods where a loose coil-like hot rolled wire rods (200) are cooled with refrigerant (100), the loose coil-like hot rolled wire rods (200) are not cooled by immersing them into stored refrigerant but cooled by exposing them to refrigerant flow. As compared with conventional heat treatment method where jet flow of refrigerant is supplied by supplying refrigerant flow directly to the hot rolled wire rods (200) exposed to outside the refrigerant, the control width of a cooling rate can be increased. Consequently, heat treatment can be carried out at a cooling rate equivalent to that of molten lead with gas-liquid mixture water employed as refrigerant, and a plurality of cooling zones of different cooling conditions can be provided in the longitudinal direction of the heat treatment process.

Description

Specification

Method and apparatus for direct heat treatment of hot rolled wire rod

Technical field

The present invention relates to a method and apparatus for direct heat treatment of a hot-rolled wire rod. In particular

The present invention relates to a direct heat treatment method and apparatus for a hot-rolled wire rod which can widen the control range of the cooling rate and can form a plurality of cooling zones having different cooling rates in the longitudinal direction of the heat treatment line.

Background art

[0002] A direct heat treatment method of a steel wire using boiling water or hot water as a refrigerant is known, in which a hot rolled wire is wound into a ring shape, and the center of the ring is made into a roll coil shape with a constant pitch offset. (For example, Patent Document 1 and Patent Document 2). As shown in FIG. 10, the refrigerant 100 controlled to a predetermined temperature is stored in the refrigerant tank 10, and the loose coil-shaped hot-rolled wire rod 200 supplied from the laying head 40 is immersed in the refrigerant 100. The heat treatment is performed while the wire rod 200 is conveyed by the conveyor 12 in the refrigerant tank. At that time, a jet of boiling water or a gas-liquid mixed flow is injected from the nozzle 32 immersed in the refrigerant 100 in the refrigerant tank 10, and the refrigerant 100 in the refrigerant tank 10 is made to flow to alleviate the dispersion of the refrigerant temperature. The cooling unevenness of the wire rod 200 is suppressed.

Patent Document 1: Japanese Patent Application Laid-Open No. 60-228619

Patent Document 2: Japanese Patent Application Laid-Open No. 6-207224

Disclosure of the invention

Problem that invention tries to solve

In the above-mentioned prior art, usually, the size of the refrigerant tank is fixed, and the cooling rate of the steel wire is adjusted by the time for which the steel wire is immersed in the coolant, that is, the conveying speed of the steel wire. However, there are various limitations in the adjustment of the cooling rate due to the change of the transfer rate.

(1) In the refrigerant immersion type in which the steel wire is immersed and passed through the refrigerant, there is a problem that the control range of the cooling rate is narrow. In the refrigerant immersion type, the minimum cooling rate is equal to the cooling rate in the refrigerant, and the cooling rate can not be reduced more than that. Therefore, the cooling rate is There is a limit to the problem. On the other hand, in this refrigerant immersion type, even if the nozzle force is also used to inject boiling water to perform stirring by forced convection of the refrigerant, it is difficult to cause the cooling rate to reach the molten lead as well. There are also limitations.

(2) In the refrigerant immersion type, the diameter of the wire that can be cooled is limited depending on the size of the refrigerant tank. Since the cooling rate changes depending on the wire diameter, it is necessary to adjust the cooling rate according to the wire diameter. However, since the length of the cooling tank is constant, the diameter of the wire that can be cooled is restricted by the method of adjusting the cooling speed by changing the transport speed of the steel wire. Therefore, even if a large diameter wire is to be cooled at a sufficient speed, the longer the diameter of the larger diameter wire, the longer the cooling tank is required.

(3) In the refrigerant immersion type, it is substantially impossible to change the cooling rate of the wire in the longitudinal direction of the refrigerant tank. As described above, in the refrigerant immersion type, the control range of the cooling rate is narrow. Furthermore, even if forced convection of the refrigerant is performed by spouting the nozzle force gas-liquid mixed hot water etc. arranged in the refrigerant, the cooling speed depends on the arrangement direction and the arrangement density of the nozzles or the injection flow rate of the gas-liquid mixed flow. It is difficult to precisely control the cooling rate by changing these cooling conditions. Therefore, it is practically impossible to provide a plurality of cooling zones having different cooling rates in the longitudinal direction of the refrigerant tank, such as a recuperation zone and a quenching zone.

(4) It is difficult to uniformly cool the steel wire. When a jet is blown to the steel wire or air is jetted from below the steel wire in the refrigerant, especially in the case of a small diameter wire with a diameter of 7 mm or less, the wire will be lifted by the jet or air and causing troubles in conveying the steel wire. Due to the variation of the cooling rate, the loose coiled steel wire tends to be deformed. In addition, in the case of a subeutectoid or hypereutectoid composition and such a composition that does not transform into a single structure like the eutectoid eutectoid component, the phenomenon in which the loose coiled steel wire warps during eutectoid transformation is remarkable. Again, it is the cause of steel wire transport troubles.

The present invention has been made in view of the above-described circumstances, and one of its objects is to provide a direct heat treatment method and apparatus for a hot-rolled wire rod which can expand the control range of the cooling rate. is there.

[0010] Another object of the present invention is to vary the cooling rate of the wire in the longitudinal direction of the refrigerant tank. It is an object of the present invention to provide a direct heat treatment method and apparatus of a hot rolled wire rod that can Means to solve the problem

[0011] The present invention achieves the above object by supplying a coolant flow to the hot rolled wire rod from outside the coolant rather than generating a jet flow in the coolant stored in the coolant tank.

The direct heat treatment method of the hot-rolled wire according to the present invention can be roughly classified into three types: a type in which the hot-rolled wire is not immersed in the refrigerant; a type in which the hot-rolled wire is partially immersed; Wrinkling is also a method of direct heat treatment of a hot-rolled wire rod that uses a coolant to cool the loose-rolled hot-rolled wire rod. And, each of the types is characterized by having the following configuration.

In the direct heat treatment method of the non-immersion type hot rolled wire according to the present invention, a loose coil-shaped hot rolled wire is exposed to a refrigerant flow and cooled without being immersed in the stored refrigerant.

The direct heat treatment method of the partial immersion type hot rolled wire rod of the present invention is characterized in that the loose coiled hot rolled wire rod is partially exposed from the liquid surface of the stored refrigerant, and the liquid surface of the refrigerant is partially exposed. External Force Cools by exposure to a supplied coolant stream.

[0015] The direct heat treatment method of the full immersion type of the present invention hot rolled wire rod is supplied from the outside of the liquid surface of the refrigerant in a state in which the loose coiled hot rolled wire rod is immersed in the stored refrigerant. Cool by exposure to refrigerant flow.

Among the methods of the present invention, in the non-immersion type and partial immersion type heat treatment methods, the coolant flow is directly supplied to the hot-rolled wire exposed to the outside of the refrigerant such as air or partially exposed from the refrigerant. Thus, the control range of the cooling rate can be made wider compared to the conventional heat treatment method in which the temperature of the refrigerant flow is directly transmitted to the wire and the jet flow is immediately supplied from the refrigerant. In particular, according to the non-immersion type and the partial immersion type, the control range of the cooling rate can be extended to both increasing and decreasing the cooling rate. Specifically, in the case of the 13 mm diameter wire, the control range of the cooling rate is about 10 to 20 ° C. Zsec in the conventional heat treatment method, whereas the control range of the cooling rate is 0.05 ° C. Zsec in the method of the present invention. It can be about 50.0 ° C. Z sec. As the wire diameter becomes larger (smaller), the upper limit of the cooling rate becomes lower (higher).

[0017] In addition, even with the complete immersion type, with regard to the reduction of the cooling rate, the conventional method Although there is no difference between them, with regard to increasing the cooling rate, cooling by the refrigerant flow from outside the refrigerant can be made substantially comparable to that of the non-immersion type and partial immersion type. The control range of the cooling rate can be made wider than that of the conventional heat treatment method in which the jet is supplied. Specifically, in the case of a 13 mm diameter wire, the control range of the cooling rate can be set to about 5.0 ° C./sec to 40.0 ° C./sec. In the case of the complete immersion type, since the wire is surely immersed in the refrigerant, a part which does not touch the refrigerant does not partially occur.

On the other hand, the direct heat treatment apparatus for the hot rolled wire according to the present invention can be roughly classified into three types: one in which the hot rolled wire is not immersed in the cooling medium; is there. All of them are a direct heat treatment apparatus for a hot-rolled wire rod having a refrigerant tank and a conveying means for conveying a loose coil-shaped hot-rolled wire rod in the refrigerant tank to the upstream side of the heat treatment process downstream. . And each of each type is characterized by having the following composition.

The direct heat treatment apparatus of the non-immersion type hot rolled wire rod of the present invention transports the hot rolled wire rod in the refrigerant tank without being immersed in the refrigerant by the transport means. And it has a refrigerant supply means which supplies a refrigerant flow to the hot rolling wire rod.

The direct heat treatment apparatus of the partial immersion type hot rolled wire rod of the present invention transports the hot rolled wire rod by the transport means in a state of being partially exposed from the liquid surface of the refrigerant stored in the refrigerant tank. And it has a refrigerant | coolant supply means which supplies a refrigerant | coolant flow to the hot rolling wire from the outer side of the liquid level of a refrigerant | coolant.

The direct heat treatment apparatus of the complete immersion type of the present invention hot rolled wire rod transports the hot rolled wire rod immersed in the refrigerant stored in the refrigerant tank by the transport means. And, it has a refrigerant supply means for supplying a refrigerant flow to the heat rolled wire from outside the liquid surface of the refrigerant.

Among the apparatuses of the present invention, the non-immersion type and partial immersion type heat treatment apparatuses use the refrigerant supply means to perform hot rolling exposed outside the refrigerant such as the atmosphere or partially exposed from the refrigerant. The refrigerant can be supplied directly to the wire. Accordingly, the control range of the cooling rate can be made wider compared to the conventional heat treatment apparatus which supplies the jet stream from the refrigerant.

[0023] In addition, even with the complete immersion type, with regard to the reduction of the cooling rate, the conventional method Although there is no difference, with regard to increasing the cooling rate, cooling by means of the refrigerant flow of the refrigerant external force can be made substantially comparable to the non-immersion type or partial immersion type by using the refrigerant supply means. . Therefore, the control range of the cooling rate can be made wider compared to the conventional heat treatment apparatus which supplies the jet flow from the refrigerant.

In this heat treatment method or apparatus, it is possible to use, as the refrigerant, boiling water or hot water, or a gas-liquid mixed refrigerant obtained by mixing a liquid such as these with a gas such as air. The refrigerant temperature is controlled to 85 ° C. or more and 100 ° C. or less, more preferably 90 ° C. or more and 95 ° C. or less. By this cooling, the hot-rolled wire is transformed into a structure consisting essentially of austenite. The refrigerant used for cooling the hot-rolled wire rod is discharged from the refrigerant tank and returned to the temperature adjustment tank, and after the temperature is adjusted, the refrigerant is supplied again to the refrigerant tank. Thereafter, the refrigerant is similarly circulated between the temperature control tank and the refrigerant tank.

Usually, the refrigerant whose temperature has been adjusted to a predetermined temperature in the temperature adjustment tank is supplied as a refrigerant flow to the hot-rolled wire rod conveyed in the refrigerant tank by the refrigerant supply means.

The temperature control tank has a function of adjusting the refrigerant discharged from the refrigerant tank to a predetermined temperature. For example, one having a container having a capacity equal to or higher than that of the refrigerant tank and a heat exchange means for adjusting the refrigerant temperature can be used. As described above, this temperature control tank controls the refrigerant temperature to 85 ° C. or more and 100 ° C. or less, more preferably 90 ° C. or more and 95 ° C. or less. The refrigerant adjusted to a predetermined temperature by the temperature adjustment tank is supplied to the refrigerant tank by the refrigerant supply means.

[0027] The refrigerant supply means is good as long as the refrigerant flow can be supplied to the hot rolled wire. For example, as the refrigerant supply means, one having a pump for transmitting the refrigerant from the temperature adjustment tank to the refrigerant tank and a nozzle for injecting the refrigerant to the hot rolling wire in the refrigerant tank can be used. In addition, instead of the nozzle for injecting the refrigerant, it simply has a supply port for the refrigerant flow, and the refrigerant flow is supplied to the inside of the cooling medium tank like this supply Roka waterfall, and the hot rolled wire is passed through the waterfall. You may cool it as you like.

At that time, it is preferable that the nozzle and the supply port be provided on the upper portion of the hot-rolled wire rod to be conveyed. In the case of the non-immersion type, by supplying a coolant flow from the top, the coolant on the hot-rolled wire rod naturally falls downward along the surface of the wire rod by gravity, and the coolant is spread all around the wire rod. Can provide effective cooling. Partial immersion type or immersion type Even in this case, since the flow of the refrigerant flow supplied from the outside of the refrigerant extends to the steel wire portion immersed in the refrigerant, effective cooling can be performed as in the non-immersion type. In the case of the partial immersion type and the immersion type, in particular, when a refrigerant flow different in temperature from the refrigerant stored in the refrigerant tank is supplied, the effective cooling rate can be controlled.

Of course, in the case of the non-immersion type, the downward force refrigerant flow of the wire may be supplied without being immersed in the refrigerant. In the case of the partial immersion type and the immersion type, in addition to supplying the refrigerant flow from above, the refrigerant flow may also be supplied from below the wire immersed in the refrigerant, that is, from within the refrigerant. At that time, it is preferable to adjust the flow rate of the coolant flow so that the wire does not lift up due to the downward force of the coolant flow.

Further, it is preferable that the refrigerant supply means be configured to supply the refrigerant to a portion that is more than a portion where the overlapping of the hot rolled wire rod is small. For example, a nozzle or a supply port may be directed to a portion where the hot rolled wire rod has a large amount of overlap, or the number of nozzles or supply ports directed to the portion having a large number of overlapping may The number of nozzles and supply ports may be increased. By using such a refrigerant supply means, it is possible to suppress uneven cooling in the places where the wire rods overlap and where the overlap is small.

Preferably, the refrigerant supply means is configured to be able to mix a liquid refrigerant with a gas at a predetermined mixing ratio. For example, connecting the gas refrigerant supply means which supplies gas with respect to a nozzle is mentioned. By mixing the gas with the liquid refrigerant at a predetermined mixing ratio, the cooling capacity of the refrigerant can be changed, and the refrigerant temperature control with higher accuracy can be enabled. It is also possible to supply refrigerants having different gas mixing ratios at the places where the wire rods overlap and where the wires overlap.

On the other hand, a container having a refrigerant tank can be suitably used. For example, it is possible to use a refrigerant tank having a bottom surface, both side surfaces, both end surfaces and an open top. In the case of the non-immersion type, the refrigerant tank used in the method or apparatus of the present invention does not need to store the refrigerant. That is, the refrigerant tank may have a structure in which the bottom surface is substantially removed. In the case of the partial immersion type or the complete immersion type, it is preferable to have a heating means for adjusting the temperature of the refrigerant stored in the refrigerant tank to some extent. The set temperature of the heating means may be the same or different in each cooling zone when a plurality of cooling zones are provided as described later. In the case of complete immersion type, The heat treatment is preferably performed by controlling the position of the liquid surface of the refrigerant so that the maximum distance from the liquid surface of the refrigerant to the hot-rolled wire rod is 6 cm or less. If the maximum distance force to the hot rolled wire is 3⁄4 cm or less, the immersion depth into the refrigerant is small, so the flow action by the refrigerant flow supplied from outside the refrigerant, that is, from the outside of the liquid surface of the refrigerant is sufficient. And effective cooling can be performed.

[0033] A discharge port of the refrigerant is formed on any of the surfaces constituting the refrigerant tank, and the discharged refrigerant is supplied to the temperature control tank and adjusted to a predetermined temperature. For example, an outlet may be formed on the upstream end surface or bottom surface of the refrigerant tank. By providing the outlet of the refrigerant on the upstream side of the refrigerant tank where the hot rolled wire rod is charged, the refrigerant whose temperature has risen in contact with the wire rod can be efficiently discharged to the outside of the refrigerant tank.

Further, in the case of the immersion type, in particular, by providing the discharge port on the bottom surface of the refrigerant tank, it is possible to discharge the low temperature refrigerant stagnating at the bottom of the refrigerant tank. The outlet on the bottom is preferably constructed so that the temperature of the refrigerant tends to rise, and the location of the outlet is larger than that of the other locations. For example, when the temperature of the refrigerant is likely to rise due to transformation heat generation of the steel wire or the like in the vicinity of 2 m from the upstream side in the refrigerant tank, the area of the bottom outlet at the point where this temperature tends to rise is It can be mentioned to make it bigger. With such a configuration, the refrigerant in the portion where the temperature rise of the refrigerant tends to occur is efficiently discharged, and more effective cooling is enabled.

[0035] In such a coolant tank, a transfer means for transferring the hot-rolled wire rod from the upstream side to the downstream side of the heat treatment step is provided. In the case of the non-immersion type, at least a part of the wire rod is immersed in the refrigerant in the case of the non-immersion type, and in the case of the partial immersion type or the full immersion type, the conveyer can be transported without being immersed in the refrigerant. There is a conveyor that can be driven by Usually, in the transport means, the introduction portion and the discharge portion to the refrigerant tank are inclined, and the middle between the introduction portion and the discharge portion is horizontally formed. At that time, the inclination angle of the introducing part is preferably within 60 ° with respect to the horizontal plane. By suppressing the inclination of the introduction part in the transport means, it is possible to suppress the occurrence of transport troubles due to the displacement of the wire on the transport means. The more preferable value of this inclination is 45 ° or less.

Heat treatment of the cooling zone having the above-described refrigerant tank, transport means and refrigerant supply means It is preferable to provide a plurality in the longitudinal direction of the process. By providing a plurality of cooling zones, heat treatment can be performed under different conditions for each cooling zone. Also, between the cooling zones, etc. shall be taken as the recuperation zone, and the wire rod cooled in the cooling zone shall be recuperated in the recuperation zone.

Effect of the invention

According to the method and apparatus of the present invention, in the case of the non-immersion type and the partial immersion type heat treatment method, the refrigerant is directly applied to the hot-rolled wire exposed to the outside of the refrigerant such as air or partially exposed from the refrigerant. By supplying the stream, the control range of the cooling rate can be made wider than in the conventional heat treatment method in which the jet stream is supplied from the refrigerant. In the case of the complete immersion type, the cooling by the external refrigerant and the refrigerant flow can be made substantially comparable to those of the non-immersion type and the partial immersion type, and the control range of the cooling rate can be expanded similarly. Along with this, the following effects can be achieved.

(1) It becomes possible to carry out heat treatment at a cooling rate comparable to molten lead.

(2) A plurality of cooling zones having different cooling conditions can be provided in the longitudinal direction of the heat treatment step. For example, it is possible to easily provide a rapid cooling zone having a high cooling rate, or provide a recuperation zone to recuperate the wire rod once cooled.

(3) Even in the case of a thick or wire rod, a cooling rate suitable for the wire diameter can be obtained without increasing the length of the cooling tank.

(4) It is possible to obtain an appropriate cooling rate and reduce the variation in cooling, and to obtain a steel wire with excellent mechanical characteristics. In particular, it becomes easy to control the strengthening of the wire and the mechanical performance.

Brief description of the drawings

FIG. 1 is a schematic configuration view of a non-immersion type present invention device.

FIG. 2 is a schematic perspective view showing an arrangement relationship between wires and nozzles in a refrigerant tank of the apparatus of FIG.

FIG. 3 is a schematic cross-sectional view showing an arrangement relationship between wires and nozzles in a refrigerant tank of the apparatus of FIG.

[Fig. 4] Arrangement of the wire and the nozzle in the refrigerant tank of the device of the present invention in which the nozzle is also provided below the wire It is a schematic cross section which shows positional relationship.

[Fig. 5] Fig. 5 is a schematic cross-sectional view showing an arrangement relationship between a wire and a nozzle in a refrigerant tank of a partial immersion type device.

[Fig. 6] Fig. 6 is a schematic cross-sectional view showing an arrangement relationship between a wire and a nozzle in a refrigerant tank of a complete immersion type device.

FIG. 7A is a schematic plan view of a heat treatment line configured by the device of the present invention.

FIG. 7B is a schematic plan view of a heat treatment line configured with a comparative example device.

FIG. 8A is a histogram showing tensile strength distribution of a wire obtained by heat treatment in a comparative example device.

FIG. 8B is a histogram showing tensile strength distribution of the wire obtained by heat treatment in the example device.

FIG. 9A is a graph showing the temperature history of the wire in heat treatment by the comparative example device.

FIG. 9B is a graph showing the temperature history of the wire in heat treatment by the example device.

FIG. 10 is a schematic block diagram of a comparative example device.

Explanation of sign

[0040] 10 refrigerant tank 11 outlet 12 conveyor

20 temperature control tank 30 refrigerant supply means 31 pump 32 nozzle

40 laying heads 50A, 50B horizontal conveyor

60 cooling zone 61 first cooling zone 62 second cooling zone

100 refrigerant 200 hot rolled wire

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

Example 1 Non-immersion Type

FIG. 1 is a schematic block diagram of the heat treatment apparatus of the present invention. This apparatus has a refrigerant tank 10, a temperature control tank 20 for adjusting the temperature of the refrigerant discharged from the refrigerant tank 10, and a refrigerant supply means 30 for supplying the refrigerant of the temperature control tank 20 to the refrigerant tank 10. The refrigerant supply means 30 has a pump 31 and a nozzle 32. A laying head 40 is provided upstream of the refrigerant tank 10, and the hot rolled wire rod 200 delivered from the head 40 is immersed in the refrigerant 100 of the refrigerant tank 10 to perform heat treatment. The refrigerant tank 10 is a container-like tank having an open top, and is composed of both end surfaces, both side surfaces, and a bottom surface. Among these, the discharge port 11 of the refrigerant is formed on the upstream side of the bottom surface. Further, the refrigerant tank 10 is provided with a heating means capable of adjusting the temperature of the refrigerant introduced into the refrigerant tank 10 to some extent.

In addition, inside the refrigerant tank 10, a conveyor 12 for conveying the hot-rolled wire rod 200 is disposed. The conveyor 12 is connected to the horizontal conveyors 50A and 50B provided between the laying head 40 and the refrigerant tank 10 and on the downstream side of the refrigerant tank 10, and the hot-rolled wire rod 200 fed from the head 40 is It is introduced into the refrigerant of the tank 10 to perform heat treatment, and then the wire rod is sent out of the refrigerant tank 10. In this example, a conveyor 12 is used in the refrigerant tank 10, in which the upstream side has a high slope on the upstream side and the low side on the downstream side, the middle stage is horizontal, and the downstream side has a low slope on the upstream side and a high slope on the downstream side. The inclination angle of the former and latter stages is 20 °.

On the other hand, the temperature control tank 20 has a capacity equal to or greater than that of the refrigerant tank 10, and is an open at the top. The adjustment tank 20 is located just below the refrigerant tank 10 and is disposed so that the refrigerant 100 from the outlet 11 of the refrigerant tank 10 can be received at one end side of the adjustment tank 20. Further, a pump 31 is connected to the other end side of the adjustment tank 20 via a pipe, and driving of the pump 31 circulates the refrigerant in the adjustment tank 20 to the refrigerant tank 10 side. Although not shown, heat exchange ^ for adjusting the refrigerant in the temperature control tank 20 to a predetermined temperature is provided in the temperature control tank 20.

The refrigerant, which has been adjusted to a predetermined temperature from the adjustment tank 20 and sent, is jetted from the nozzles 32 arranged to face the bottom surface of the refrigerant tank 10. The nozzles 32 are disposed opposite to each other on the conveyor 12 in the refrigerant tank, and are configured to be able to mix the hot water from the adjustment tank 20 with air at a predetermined ratio and jet it. That is, by supplying the refrigerant 100 with an almost upward force to the hot-rolled wire rod 200, it is possible to suppress the occurrence of transport troubles due to the disturbance of the pitch of the wire rod 200 and the like.

Further, the nozzles 32 are arranged at intervals in the width direction of the refrigerant tank 10, and the refrigerant can be intensively supplied to the loose-coil hot-rolled wire rod 200 at a location where there are many overlaps. It is being done. Here, as shown in Figure 2 and Figure 3, three wires along the wire transport direction Nozzles 32 are arranged in parallel. In each of the nozzles, the more overlapping portions of the hot-rolled wire rod 200 can supply more refrigerant than other portions where the number of injection ports of the refrigerant is large.

Then, as shown in FIG. 1 and FIG. 3, the refrigerant 100 supplied from the nozzle 32 is stored in the bottom of the refrigerant tank 10 to a certain extent. The liquid level of the stored refrigerant 100 is below the conveyor 12 positioned. That is, the hot-rolled wire rod 200 is held on the compensator 12 without being immersed in the stored refrigerant 100, and is cooled by the refrigerant flow supplied exclusively by the nozzle 32. Since the refrigerant 100 in contact with the wire 200 is intended to fall downward by gravity, it can be spread over the entire outer periphery of the wire 200, and the wire 200 can be cooled uniformly without unevenness. Therefore, cooling can be performed by injecting a jet from the nozzle 32 disposed in the stored refrigerant 100 to the wire 200, and the control range of the cooling rate can be expanded widely compared to the conventional cooling method ( Figure 10).

In such an apparatus, the hot-rolled wire rod 200 sent from a rolling line (not shown) is cut into a ring by the laying head 40, and the center of the ring is a predetermined pitch. In the form of an offset loose coil, supply to the horizontal conveyor 50A.

The hot-rolled wire rod 200 on the horizontal conveyer 50A is sent to the conveyer 12 in the refrigerant tank 10 and is brought into contact with the refrigerant flow supplied from the nozzle 32 to be cooled. By this cooling, the hot-rolled wire 200 is transformed to a structure consisting essentially of austenite.

Then, the heat-treated wire rod 200 is sent out from the refrigerant tank 10 and transported by the horizontal conveyor 50 B, and then supplied to the next process.

According to such an apparatus, since the hot-rolled wire rod 200 is cooled by the refrigerant flow without being immersed in the refrigerant 100, the control range of the cooling rate can be expanded compared to the conventional case. Along with that, improvement of the mechanical properties of the wire can be realized.

As another modification, as shown in FIG. 4, the nozzle 32 may be disposed below the conveyor 12 so that the downward force of the hot-rolled wire rod 200 can also jet the refrigerant flow. . In this case, the coolant flow can be applied to the hot-rolled wire rod 200 as well, so that efficient cooling can be expected. However, in order to inject the refrigerant flow from the lower side of the wire 200, it is preferable to inject the refrigerant flow with a degree of force that the wire 200 is pushed up by the refrigerant flow and does not run wild on the conveyor 12. (Example 2: Partial Immersion Type)

Next, the partial immersion type of the present invention will be described based on FIG.

In the first embodiment, the hot-rolled wire rod conveyed by the conveyor is not immersed in the refrigerant in the refrigerant tank and is cooled by the refrigerant flow supplied exclusively with the nozzle force, but in this example, the hot-rolled wire rod 200 The difference is that a part of is immersed in the refrigerant 100. The other configuration is the same as that of the first embodiment, so the description will be omitted.

That is, as shown in FIG. 5, a large amount of the refrigerant 100 of the embodiment is stored in the refrigerant tank 10, and the liquid surface of the refrigerant 100 is positioned approximately midway in the thickness direction of the hot-rolled wire rod 200. doing. Such partial immersion of the wire 200 can be easily realized by adjusting the balance between the amount of refrigerant supplied from the nozzle 32 and the amount of refrigerant discharged from the refrigerant tank 10. And, even with the hot-rolled wire rod 200 in such a partially immersed state, the hot-rolled wire rod 200 is substantially cooled by the flow of the refrigerant supplied from the nozzle 32, so the same degree of cooling as in Example 1 is performed. Temperature range of speed can be realized.

(Example 3: Complete immersion type)

Next, the complete immersion type of the present invention will be described based on FIG.

In Example 2, a part of the hot-rolled wire rod conveyed by the conveyor was immersed in the refrigerant in the refrigerant tank, but in this example, all of the hot-rolled wire rod 200 was immersed in the refrigerant. Is different.

That is, as shown in FIG. 6, more refrigerant 100 than in Example 2 is stored in the refrigerant tank 10, and the liquid surface of the refrigerant 10 is located above the hot-rolled wire rod 200. In this example, the amount of refrigerant stored was such that the maximum distance between the liquid surface of the stored refrigerant 10 and the loose-coil hot-rolled wire rod 200 was 3 cm. Also in the case of this example, the adjustment of the refrigerant storage amount is performed by adjusting the balance between the refrigerant supply amount from the nozzle 32 and the refrigerant discharge amount from the discharge port of the refrigerant tank 10.

Even in such a fully immersed hot-rolled wire rod 200, since the immersion depth in the refrigerant 100 is shallow, the momentum of the refrigerant flow supplied from the outside of the refrigerant is the entire hot-rolled wire rod 200. In addition, the hot-rolled wire rod 200 can be cooled by the refrigerant flow supplied from the nozzle 32 to obtain a cooling state very similar to the cooling state. In particular, in order to increase the cooling rate V, an adjustment width comparable to that of the first embodiment or the second embodiment can be obtained. Test Example 1

The heat treatment of the hot-rolled wire rod was performed using the comparative example devices shown in the above-described example devices (FIG. 1, FIG. 5, FIG. 6) and FIG. In the example apparatus, as shown in FIG. 7A, a heat treatment line having two cooling zones, ie, the first cooling zone 61 on the upstream side (the laying head 40 side) and the second cooling zone 62 on the downstream side, was configured. Each of the cooling zones 61, 62 is configured with the same type of embodiment apparatus, and in the first cooling zone, the wire is cooled, and in the second cooling zone, cooling is more relaxed than in the first cooling zone. On the other hand, in the comparative example device, as shown in FIG. 7B, a heat treatment line having a single cooling zone 60 was configured. The conditions of the heat treatment equipment used in these heat treatment lines are as follows.

Examples 1 to 3

Refrigerant tank length in first cooling zone = approx. 4 m

Refrigerant tank capacity in the first cooling zone = approx. 6 m ³

Refrigerant tank length in second cooling zone = approx. 4 m

Refrigerant tank capacity in second cooling zone = approx. 6 m ³

Distance between the first cooling zone and the second cooling zone = approximately 1.05 m

The maximum immersion distance to the wire is also 3cm

Comparative Example

Refrigerant tank length = about 24 m

Refrigerant tank capacity = about 20 m ³

Specific heat treatment conditions are shown in Tables 1 to 4. Table 1 shows the conditions for heat treatment using a non-immersion type embodiment device, Table 2 shows the conditions for heat treatment using a partial immersion type embodiment device, and Table 3 shows a complete immersion type embodiment device. Table 4 shows the conditions in the heat treatment using the device of the comparative example. Also, the tensile strength of the obtained steel wire was measured. The measurement results are also shown in Tables 1 to 4. In these tables, the meaning of each term is as follows.

Steel billet heating temperature: temperature at which steel billet is heated during rolling

Final rolling temperature: rolling material temperature at the outlet of final rolling mill

Wrinkling temperature: Rolled material temperature when winding with a laying head Refrigerant tank temperature: Set temperature of refrigerant tank (common to the first cooling zone 'second cooling zone) Refrigerant temperature: Set temperature of temperature control tank

Flow rate: Total drainage flow rate from each refrigerant tank

Tensile strength: The tensile strength of the sample obtained from multiple positions in the longitudinal direction of the wire is measured, and the average value of the measured values is shown.

[table 1]

[Table 2]

Sample No. Wire diameter Steel grade Steel piece Final rolling Boiling Refrigerant tank (mm) Heating temperature / plate 3⁄4t Remarks

(° C) (.c) (.c) (° C)

2-1 11.5 SWRH 82 B 1100 980 800 90.0 The Invention

2-2 11.5 SWRH 82B 1100 980 900 90.0 The present invention

2-3 11.5 SWRH 87 B 1100 980 900 90.0 The Invention

2-4 13.0 SWRH 82 B 1100 980 800 88.0 The Invention

2-5 13.0 SWRH 82 B 1100 980 900 88.0 The Invention

2-6 13.0 SWRH 87B 1100 980 900 88.0 The Invention

2-7 16.0 SWRH 82 B 1100 980 800 88.0 The Invention

2-8 16.0 SWRH 82 B 1100 980 900 88.0 The Invention

2-9 16.0 SWRH 87 B 1100 980 900 88.0 Inventive Sample No. Cooling zone Second cooling zone Tensile force

: Fudan

fV medium temperature air-mixing / shari / "medium"; plate air-mixing: 县

All Shiri (MPa)

(.C) presence (m ³ / min) (.c) presence (m min)

2-1 90.0 Yes 1.5 99.0 None 1.5 1221

2-2 90.0 Yes 1.5 99.0 No 1.5 1236

2-3 90.0 Yes 1.5 97.0 No 1.5 1257

2-4 88.0 Yes 2.0 97.0 None 2.0 1239

2-5 88.0 Yes 2.0 97.0 None 2.0 1245

2-6 88.0 Yes 2.0 97.0 None 2.0 1250

2-7 85.0 Yes 2.5 95.0 Yes 2.2 1233

2-8 85.0 Yes 2.5 95.0 Yes 2.2 1240

2-9 85.0 Yes 2.5 95.0 Yes 2.2 1248 3] Formula 4 No. Wire diameter Steel grade Steel piece Final rolling Take-up Refrigerant tank

, Mm) Heating temperature / plate Remarks

(.C) (.C) (° o (° C)

3-1 11.5 SWRH 82 B 1100 980 800 90.0 The Invention

3-2 11.5 SWRH 82 B 1100 980 900 90.0 Invention

3-3 11.5 SWRH 87 B 1100 980 900 90.0 The Invention

3-4 13.0 SWRH 82 B 1100 980 800 88.0 The Invention

3-5 13.0 SWRH 82 B 1100 980 900 88.0 The Invention

3-6 13.0 SWRH 87 B 1100 980 900 88.0 The Invention

3-7 16.0 SWRH 82 B 1100 980 800 88.0 The Invention

3-8 16.0 SWRH 82 B 1100 980 900 88.0 The Invention

3-9 16.0 SWRH 87 B 1100 980 900 88.0 Invention Formula No. 1st Cooling Zone 2nd Cooling Zone Tensile Strength

IV medium; plate air-mixing: 罢

/ Sri, not; dish air-mixing; Jl sri (MPa)

Presence of (° C) Presence (m ³ / min) (° C) Presence (m ³ 〃)

3-1 90.0 Yes 1.5 99.0 No 1.5 1204

3-2 90.0 Yes 1.5 99.0 None 1.5 1210

3-3 90.0 Yes 1.5 97.0 No 1.5 1238

3-4 88.0 Yes 2.0 97.0 None 2.0 1212

3-5 88.0 Yes 2.0 97.0 None 2.0 1230

3-6 88.0 Yes 2.0 97.0 None 2.0 1226

3-7 85.0 Yes 2.5 95.0 Yes 2.2 1218

3-8 85.0 Yes 2.5 95.0 Yes 2.2 1223

3-9 85.0 Yes 2.5 95.0 Yes 2.2 1226 [Table 4]

As apparent from the above table, when the non-immersion type device shown in Table 1 is used, a steel wire having the highest tensile strength is obtained, and in the following order, the partial tensile type and the complete immersion type have higher tensile strength steels. It can be seen that a line is obtained. On the other hand, in the heat treatment using the device of the comparative example, it is found that the steel wire has a much lower tensile strength than the heat treatment using any of the devices of any of the examples.

Further, when the tensile strength of the samples obtained from a plurality of positions in the wire longitudinal direction was measured, the variation in tensile strength of each sample was examined. Here, the tensile strength of the steel wire obtained by the heat treatment using the non-immersion type device (corresponding to sample No. 1 -1) and the heat treatment using the comparative example device (corresponding to sample No. 4-1) The distribution was examined. The results are shown in Figure 8.

As is clear from this graph, the center of the tensile strength distribution is the direction of the steel wire (FIG. 8B) obtained by the non-immersion type device than the steel wire (FIG. 8A) obtained by the comparative device. However, the superiority of the heat treatment using the device of the present invention can be confirmed. In addition, it can also be seen that the distribution width of tensile strength can also suppress the dispersion of smaller product characteristics with the steel wire obtained by the non-immersion type device.

Furthermore, the temperature of the wire and the cooling time in the heat treatment (corresponding to sample No. 1-1) using the non-immersion type device and the heat treatment (corresponding to sample No. 4-1) using the comparative example device I also investigated the relationship. The results are shown in the graph of FIG.

In the heat treatment using the device of the comparative example, as shown in FIG. The temperature decreases, and during the cooling stage, a rise in line temperature occurs depending on the steel wire composition. After that, it shows the temperature history where the line temperature drops sharply again at the second stage of cooling. At that time, the tendency of lowering the line temperature at the front stage of cooling (cooling rate) and the tendency of lowering the line temperature at the rear stage of cooling are almost the same. In other words, it is possible to obtain different cooling rates in the first and second stages of cooling.

On the other hand, in the heat treatment using the non-immersion type device (Example), as shown in FIG. 9B, the linear temperature drops sharply in the former stage of cooling more than the heat treatment in the comparative example device. . Further, although the rise in line temperature occurring depending on the steel wire composition occurs in the middle stage of cooling is the same as in the case of the heat treatment in the device of the comparative example, the degree of temperature rise is mitigated. And, in the latter stage of the cooling, it is understood that the linear temperature is lowered more gently than in the case of the heat treatment in the device of the comparative example. That is, at that time, the line temperature decrease tendency (cooling rate) at the former stage of cooling and the line temperature decrease tendency at the latter stage are different, and it is clear that different cooling rates can be obtained between the former stage and the latter stage. .

Next, using the complete immersion type example device, the same heat treatment was performed in which the maximum distance from the liquid surface of the refrigerant to the wire was 6.0 cm, 2.0 cm, and 0.5 cm. It was found that the tensile strength was superior to the obtained steel wire.

Industrial applicability

The method and apparatus of the present invention are expected to be utilized in the heat treatment of steel wires, particularly in the field of manufacture of hard steel wire rods, piano wires and the like.

Claims

The scope of the claims

[1] A direct heat treatment method of a hot rolled wire rod for cooling a loose coiled hot rolled wire rod by a refrigerant,

The method for direct heat treatment of a hot-rolled wire rod, wherein the hot-rolled wire rod is cooled by being exposed to a refrigerant flow without being immersed in the stored refrigerant.

[2] A direct heat treatment method of a hot rolled wire rod for cooling a loose coiled hot rolled wire rod by a refrigerant,

The hot-rolled wire rod is cooled by being exposed to a refrigerant flow jetted from the outside of the liquid surface of the refrigerant in a state in which the liquid surface force of the stored refrigerant is partially exposed. Direct heat treatment of rolled wire rod.

[3] A direct heat treatment method of a hot rolled wire rod for cooling a loose coiled hot rolled wire rod by a refrigerant,

The above-mentioned hot rolled wire rod is exposed to a refrigerant flow jetted from the outside of the liquid surface of the coolant while being immersed in the stored coolant, and is cooled. Method.

[4] The method for direct heat treatment of a hot-rolled wire rod according to claim 3, characterized in that the liquid surface force of the stored refrigerant is also 3⁄4 cm or less of the maximum distance force to the immersed hot-rolled wire rod.

[5] The cooling zone according to any one of claims 1 to 4, wherein a plurality of cooling zones in which the hot-rolled wire rod is exposed to a coolant flow and cooled are formed, and the cooling conditions of each cooling zone are different. Direct heat treatment method for hot rolled wire.

[6] A direct heat treatment apparatus for a hot-rolled wire rod, comprising: a refrigerant tank; and conveying means for conveying a loose coil-shaped hot-rolled wire rod from the upstream side to the downstream side of the heat treatment step in the refrigerant tank; The means includes a refrigerant supply means for conveying the hot rolled wire in a refrigerant tank without being crushed by the refrigerant in the refrigerant tank and supplying the refrigerant flow to the hot rolled wire. Heat treatment equipment.

[7] The refrigerant tank and the loose coiled hot rolled wire rod in the refrigerant tank from the upstream side of the heat treatment process A direct heat treatment apparatus for a hot-rolled wire rod, comprising a transfer means for transferring downstream, the transfer means being in a state where the hot-rolled wire rod is partially exposed from the liquid surface of the refrigerant stored in the refrigerant tank. Transport

A direct heat treatment apparatus for a hot-rolled wire rod, comprising a coolant supply means for supplying a coolant flow to the hot-rolled wire rod from the outside of the liquid surface of the coolant.

[8] A direct heat treatment apparatus for a hot-rolled wire rod, comprising: a refrigerant tank; and conveying means for conveying a loose coil-shaped hot-rolled wire rod from the upstream side to the downstream side of the heat treatment step in the refrigerant tank; The means transports the hot-rolled wire rod in a state of being immersed in the refrigerant stored in the refrigerant tank,

[9] The heat treatment apparatus for direct heating of a hot-rolled wire rod according to any one of claims 6 to 8, characterized in that a plurality of cooling zones having the refrigerant tank, transport means and refrigerant supply means are provided in the longitudinal direction of the heat treatment step. .