JP2024049757A - Wire rod bending evaluation method - Google Patents

Abstract

[Problem] To provide a method for evaluating bending of a wire during cooling using a simulated wire in order to determine the necessity of processes for suppressing or straightening bending. [Solution] A method for simulating the bending of a wire during cooling. The method is characterized in that a simulated wire simulating a wire is placed along the upper surface of a surface plate, the simulated wire and the surface plate are heated to the same temperature, and then the simulated wire is cooled from above the surface plate to a predetermined length from one end thereof, causing bending only in the vicinity of the one end, and the relationship between the temperature difference between the top and bottom surfaces of the simulated wire and the bending of the one end is measured. [Selected Figure] Figure 1

Description

The present invention relates to a method for evaluating bending of wire during cooling, and in particular to a method for evaluating bending of wire using a simulated wire.

After steel is processed into wire, it is prone to bending (warping), especially during the cooling process. For this reason, it has been proposed to provide a device on the production line that detects bending of the wire and to provide a process for suppressing bending or straightening the bending as necessary.

For example, Patent Document 1 discloses a method for optically measuring the curvature (warping) of a wire being transported on a production line. Light is irradiated from one side of the wire, while two optical sensors on the other side, spaced a specified distance apart in the longitudinal direction of the wire, receive the light and dark areas of the light that passes through the edge of the wire and detect the edge position. It is said that the amount of curvature can be measured from this parallax. In addition, because bending occurs in both the horizontal and vertical directions of the wire, the above-mentioned measurements are carried out in each direction.

Japanese Patent Application Laid-Open No. 57-211003

As in Patent Document 1, the temperature difference between the top and bottom sides of the wire, or between both sides, will cause bending due to differences in thermal expansion. However, even when bending due to such differences in thermal expansion occurs, if the wire is cooled to a temperature where the entire wire becomes uniform, the bending will be eliminated as long as it is within the elastic deformation range. In other words, when determining whether or not a process for suppressing or straightening bending, and the equipment used for this, it is necessary to determine whether the bending is within the elastic deformation range of the wire. For this purpose, it was considered to evaluate the wire in a simulated manner in advance.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a method that uses a simulated wire as a method for evaluating the bending of wire during cooling in order to determine the need for processes such as bending suppression and bending straightening.

The method of the present invention for simulating and evaluating the bending of a wire during cooling is characterized in that a simulated wire simulating the wire is placed along the upper surface of a surface plate, the simulated wire and the surface plate are heated to the same temperature, and then the simulated wire is cooled from above the surface plate from one end to a predetermined length position by air blast cooling, causing bending only in the vicinity of the one end, and the relationship between the temperature difference between the top and bottom surfaces of the simulated wire and the bending of the one end is measured.

This feature makes it possible to determine the need for processes to prevent or straighten bending during actual operation by measuring with a dummy wire.

In the above-mentioned invention, the gas may be directed toward the top surface of the simulated wire from a slit provided in a gas pipe arranged parallel to the simulated wire from the one end to the predetermined length position, thereby cooling the wire through a blast of air. It may also be characterized by providing a partition plate that prevents the gas from flowing from the predetermined length position toward the other end of the simulated wire. With this feature, the vicinity of one end of the simulated wire can be uniformly cooled, allowing for stable measurements.

In the above-mentioned invention, the temperature difference between the top surface and the bottom surface of the simulated wire may be determined by measuring the temperature difference between the top surface of the simulated wire and the upper surface of the surface plate. With this feature, the temperature of the upper surface of the surface plate, which has a large heat capacity, can be converted into the temperature of the bottom surface of the simulated wire, and the temperature can be measured by a non-contact optical temperature measuring means such as a thermoviewer, making it possible to perform simple and stable measurement.

In the above-mentioned invention, the simulated wire and the surface plate may be heated in a furnace and cooled by air blast outside the furnace. Also, the surface plate may have a V-groove on the top surface thereof, and the simulated wire is placed inside along the V-groove. With this feature, the surface plate, which has a particularly large heat capacity, can be easily heated, and the rolling of the simulated wire due to movement inside and outside the furnace can be suppressed, enabling simple and stable measurement.

In the above-mentioned invention, the bending of the one end may be determined by taking a video of the side of the base plate and measuring the amount of lift of the one end from the top surface of the base plate. This feature allows the bending to be measured without contact, making it possible to perform simple and stable measurements.

In the above-mentioned invention, the temperature difference corresponding to the elastic deformation limit for the amount of lift may be obtained. With this feature, it is possible to specifically determine the necessity of processes for suppressing bending or straightening bending in actual operation by measuring using a simulated wire.

13 is a photograph showing how the bending of a simulated wire is measured during cooling. This is a front view of a slit gas nozzle. FIG. 1 is a graph showing the measurement results of bending of simulated wires made of three types of alloys. 13 is a graph showing temperature changes on the top surface of the dummy wire and the upper surface of the surface plate.

A wire bending evaluation method for simulating and evaluating bending of a wire during cooling according to an embodiment of the present invention will be described with reference to Figs. 1 to 3.

As shown in Figure 1, the method in this embodiment uses a surface plate 1 and a simulated wire 2 placed on its upper surface. In order to simulate the actual wire to be evaluated, the simulated wire 2 preferably has the same component composition as the actual wire and has been given a similar thermal history and processing history. For use in laboratory evaluation, the dimensions of the actual wire, such as thickness and length, may be smaller than those of the actual wire.

The simulated wire 2 is placed on the top surface of the platen 1 and heated to a predetermined temperature in a heating furnace such as a muffle furnace, and then removed from the furnace. Then, cooling gas (see arrow in the figure) is applied from above the platen 1 from one end to a predetermined length position, for air blast cooling. This allows bending to occur only near one end. It is preferable to provide a partition plate 4 for the other end to prevent it from being rapidly cooled. In other words, the gas is prevented from flowing from the predetermined length position at one end to the other end. For this reason, the partition plate 4 is installed directly above the predetermined length position with its normal line approximately parallel to the longitudinal direction of the simulated wire 2.

Referring also to Figure 2, it is also preferable to use a slit gas nozzle 3 for air blast cooling. The slit gas nozzle 3 closes the tip of the gas pipe and has a slit hole 3a on the side that extends along the gas pipe, from which gas is discharged. The slit gas nozzle 3 is then placed parallel to the simulated wire 2 with the slit hole 3a facing downward, and the simulated wire 2 is cooled by discharging gas from above. As the cooling gas is discharged from the slit hole 3a, uniform cooling is possible in the length direction of one end, which results in stable measurement.

Referring to FIG. 3, at this time, the bottom surface 2b of the simulated wire 2 is in contact with the top surface 1a of the platen 1 on which it is placed. Since the platen 1 has a large heat capacity, it is thought that the temperature of the bottom surface 2b is made to be almost the same as that of the top surface 1a. On the other hand, the temperature of the top surface 2a is lowered by air blast cooling, and there is a large temperature difference between the top surface 2a and the bottom surface 2b. Therefore, the thermal expansion coefficients of the top surface 2a and the bottom surface 2b of the simulated wire 2 are different. As a result, the simulated wire 2 bends in a direction that stretches the bottom surface 2b side, which has a larger thermal expansion coefficient. In other words, one end is separated so as to float up from the platen 1 (see dotted line in the figure). At this time, in order to prevent the bending from affecting the other end, the center of gravity of the simulated wire 2 is made to be on the other end side of the specified position to be cooled. In addition, it is preferable to provide a V-groove 11 in the base plate 1 and place the dummy wire 2 inside the V-groove 11 to prevent the dummy wire 2 from rolling when the base plate 1 is moved from the heating furnace, and to stabilize its position and orientation.

Then, by measuring the temperature difference between the top surface 2a and the bottom surface 2b and the bending that occurs, the relationship between the temperature difference and the bending can be obtained. Since it is difficult to directly measure the temperature of the bottom surface 2b, it is advisable to measure the temperature of the top surface 1a by assuming that it is approximately the same as the temperature of the top surface 1a of the base plate 1. For measuring the temperature difference, for example, a non-contact optical thermometer such as a thermo viewer can be used. In addition, as a quantity that directly corresponds to the bending, the amount of lift X, which is the distance moved upward from the initial position of one end, is used. The amount of lift can be measured from an image obtained, for example, by videotaping the side of the base plate 1. In this way, the measurement can be simplified by using a non-contact measuring device. Then, the bending of the wire is simulated and evaluated based on the temperature difference and amount of lift measured for the simulated wire 2.

For example, if the amount of lift is zero after the temperature of the simulated wire 2 has been sufficiently lowered, it is understood that the measured temperature difference only caused bending within the elastic deformation limit. On the other hand, if the amount of lift is not zero after the temperature is lowered, it is understood that the bending remains and plastic strain has occurred. In this way, the amount of lift for bending at the elastic deformation limit and the corresponding temperature difference can be obtained. Based on this, for example, the ease of occurrence of plastic strain can be relatively compared by applying a similar temperature difference to each alloy type, and then the necessity of processes for suppressing or correcting bending of the wire in actual operation can be determined according to the alloy type. In addition, based on the measurement results using the simulated wire, the presence or absence of plastic strain in the case of actual wire dimensions can be estimated by means of numerical analysis, etc.

[Example]
The results of measuring the temperature difference between the top and bottom surfaces (top surface of the surface plate) and the amount of distortion of the above-mentioned simulated wire will be described with reference to Figures 4 and 5. Here, the measurements were performed using simulated wires 2 made of three types of alloys (Alloy A, Alloy B, and Alloy C).

The procedure was as follows: first, the simulated wire 2 was placed in the V-groove 11 of the platen 1, and heated to a specified temperature in a muffle furnace. Next, the platen 1 was removed from the heating furnace and placed in a specified position corresponding to the position of the slit gas nozzle 3 fixed to the workbench, and the partition plate 4 was placed in a specified position approximately at the center of the longitudinal direction of the simulated wire 2 (see Figure 1). Air was blown out as cooling gas from the slit gas nozzle 3, and one end of the simulated wire 2 was cooled by air blast. In addition, while the one end was photographed from the side of the platen 1 with a video camera so that the amount of lifting could be measured, the temperatures of the top surface 2a and the upper surface 1a were measured and recorded with a thermoviewer at specified time intervals from the start of air blast cooling. Using the images from the video camera, the amount of lifting was measured every 30 seconds (every 60 seconds after 240 seconds) from the start of the gas outflow, and the relationship between the time and the amount of lifting was graphed.

Figure 4 shows graphs of the measurement results for alloys A to C. In all cases, the maximum amount of lift was recorded 30 or 60 seconds after the start of air blast cooling, and the amount of lift decreased over time. According to Figure 4 (a), alloy A had a maximum amount of lift of about 2.2 mm, and after cooling, about 1.2 mm of lift remained. According to Figure 4 (b), alloy B had a maximum amount of lift of about 4.0 mm, and after cooling, about 1.8 mm of lift remained. For alloy C, the maximum amount of lift was about 1.7 mm, and after cooling, the amount of lift remained was about 0 mm. In other words, alloy C hardly experienced any plastic strain during cooling.

Figure 5 shows the temperatures of the top surface 2a and upper surface 1a, which were measured at the time after cooling began. As a result, the temperature difference between the top surface 2a and upper surface 1a (referred to as the test piece temperature difference in the figure) at about 45 seconds between 30 and 60 seconds after the maximum amount of lift was measured was approximately 240°C. This temperature difference was equivalent to the temperature difference between the top surface and the bottom surface (the upper surface of the pallet) when the wire rod was cooled on a pallet in the actual production of wire rod.

Although the representative embodiments of the present invention have been described above, the present invention is not necessarily limited to these, and a person skilled in the art will be able to find various alternative embodiments and modifications without departing from the spirit of the present invention or the scope of the appended claims.

1 Surface plate 2 Simulation wire 3 Slit gas nozzle 4 Partition plate

Claims (8)

A method for simulating and evaluating bending of a wire during cooling, comprising the steps of:
A wire bending evaluation method comprising the steps of: placing a simulated wire simulating the wire along the upper surface of a surface plate; heating the simulated wire and the surface plate to the same temperature; cooling the simulated wire from above the surface plate from one end to a predetermined length position by air blast cooling, causing bending only in the vicinity of the one end; and measuring the relationship between the temperature difference between the top and bottom surfaces of the simulated wire and the bending of the one end. The wire bending evaluation method according to claim 1, characterized in that gas is directed toward the top surface of the simulated wire from a slit hole provided in a gas pipe arranged parallel to the simulated wire from the one end to the specified length position, thereby cooling the wire by air jet. The wire bending evaluation method according to claim 2, characterized in that a partition plate is provided to prevent the gas from flowing from the predetermined length position toward the other end of the simulated wire. The wire bending evaluation method according to claim 1, characterized in that the temperature difference between the top surface and the bottom surface of the simulated wire is determined by measuring the temperature difference between the top surface of the simulated wire and the upper surface of the surface plate. The wire bending evaluation method according to claim 1, characterized in that the simulated wire and the surface plate are heated in a furnace and cooled by air blast outside the furnace. A wire bending evaluation method according to any one of claims 1 to 5, characterized in that a V-groove is provided on the top surface of the surface plate, and the simulated wire is placed inside along the V-groove. The wire bend evaluation method according to claim 1, characterized in that the bend of the one end is obtained by taking a video of the side of the surface plate and measuring the amount of lift of the one end from the top surface of the surface plate. 8. The wire bending evaluation method according to claim 7, further comprising the step of: determining the temperature difference corresponding to an elastic deformation limit for the amount of lift.

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