JPH0762449A - Method for carrying hot-rolled wire rod - Google Patents

Abstract

PURPOSE:To eliminate the unevenness of a mechanical characteristic because of no obtaining of the uniform cooling speed due to overlapping of a wire rod, at the time of applying heat treatment to the wire rod in a loose coil-state by dipping into cooling medium. CONSTITUTION:In the method for carrying the wire rod on plural rolls 2 by dipping the hot-rolled wire rod in the loose coil state into the cooling medium, the wire rod 1 is continuously carried while vertically moving by adjusting the roll diameter and the roll interval. By this method, the overlapping of the wire rod is relaxed and the heat treatment having uniform cooling speed can be applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying method for introducing a hot-rolled wire in the form of a loose coil into a cooling medium for heat treatment, and particularly to a uniform length and cross section of the loose-coil-shaped wire. The present invention relates to a transportation method capable of cooling.

[0002]

2. Description of the Related Art Conventionally, as a method of conveying a wire in the above heat treatment, there are a method using a roller table and a method using a swivel conveyor. The roller table holds and conveys the wire material 1 substantially horizontally on the roller conveyor 3 linearly arranged as shown in FIG. 4, and the swiveling conveyor is an arc-shaped roller conveyor 3 as shown in FIG. Similarly, the wire rod 1 is conveyed above.

[0003]

However, neither method is sufficient for uniformly cooling the wire. That is, when the roller table is used, since the wire material has a loose coil shape, the steel material density can be high or low depending on the overlapping degree of the wire material. Therefore, there is a problem that the cooling rate in the loose coil varies, and the mechanical characteristics and the metallographic structure vary in the length direction of the wire.
In this respect, the swirling conveyor conveys the wire rods in an arc shape to gradually shift the overlapped wire rods, thereby achieving a uniform cooling rate. However, the speed and degree of shifting the wire are small,
At present, it is not always possible to obtain a uniform cooling rate.

[0004]

The present invention has been made to solve the above problems, and is characterized by continuously moving a loose coil hot-rolled wire rod during conveyance,
The purpose is to alleviate the overlapping of the wires and to cool them uniformly.

For continuous vertical movement of the loose coil hot-rolled wire, the roll diameter and roll interval (distance between roll centers) of the roller conveyor are set to predetermined values with respect to the ring diameter of the loose coil wire. It can be realized. The diameter d of the wire used is generally about 5 ≦ d ≦ 16 (mm).

A specific example will be described below with reference to the drawings. FIG. 1 is an explanatory view of the method of the present invention when the loose coil-shaped wire 1 is conveyed on a conveyor as seen from the side of the roll 2. As shown in the drawing, a plurality of rotating rolls are arranged at predetermined intervals, and a loose coil-shaped wire is conveyed on the rolls. Here, the rolls 2 are arranged at intervals such that each ring of the loose coil is not horizontally supported by two adjacent rolls and does not fall from between the rolls. Therefore, the wire rod 1 is conveyed in a wavy shape while continuously moving up and down as shown in the figure. The roll diameter D and the roll interval L are as shown in FIG.

In an actual heat treatment, such a conveyor is arranged in a cooling tank for storing a cooling medium such as hot water,
The loose-coil wire is sequentially conveyed and immersed in a cooling medium to be cooled. Therefore, the overlapping of the loose coil-shaped wire rods is relaxed, and in particular, it becomes possible to heat-treat a portion having a high wire rod density such as both ends (edges) of the ring in a direction orthogonal to the wire rod advancing direction at a uniform cooling rate.

[0008]

Example The wire was actually heat-treated by the above method. The chemical components are C: 0.82, Si: 0.2, Mn:
0.70, Cr: 0.05 (wt%), a 13 mmφ hot rolled steel wire was formed into a loose coil with a ring diameter of 1200 mm, precooled to 850 ° C., and then conveyed while moving up and down as described above. And cooled with boiling water. Roll interval L = 800 mm, roll diameter D = 500 mm, and transport speed = 400 mm / sec. Then, as shown in FIG. 3, the ring was divided into approximately eight equal parts (to), and the variation of the tensile strength of each part was examined. , Are located in the wire rod advancing direction, and are located in a direction orthogonal to the wire rod advancing direction. The results are also shown in FIG.

As shown in the graph of FIG. 3, average tensile strength =
1350N / mm ^2, showed good results with standard deviation = 11N / mm ^2. For comparison, the same heat treatment was carried out by the conventional method in which the wire rod was not vertically moved and was held while being held substantially horizontally, but the standard deviation in the variation in tensile strength was about 20 N / mm ² .

Further, the above wire (ring diameter 1200 mm) is conveyed by changing the roll diameter D and the roll interval L variously,
I checked the transportation situation. The results are shown in Table 1. As an evaluation criterion, a poor conveyance indicates a case where the wire is conveyed almost horizontally and cannot move up and down sufficiently, and a non-conveyance indicates a case where the wire rod falls into the gap between the rolls.

[0011]

[Table 1]

As shown in the table, the roll diameter D and the roll interval L are 300 <D ≦ 600 mm, 600 ≦ L ≦ 1000.
mm, the gap L1 between adjacent rolls (see FIG. 2)
When L1 <500 mm, it was confirmed that the wire can be reliably moved up and down and conveyed. Note that Sample No. 1 is a conventional transportation method.

[0013]

As described above, according to the method of the present invention, the loose coil-shaped wire rods are conveyed while being moved up and down, whereby the overlapping of the wire rods is alleviated and the wire rods are cooled uniformly over the entire length and cross section. Can be applied. Therefore, it is effective for manufacturing a wire rod having a small variation in mechanical properties.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method of the present invention.

FIG. 2 is an explanatory diagram showing roll diameters and roll intervals.

FIG. 3 is a graph showing variations in tensile strength in a ring of a wire rod obtained according to an example of the present invention.

FIG. 4 is an explanatory diagram of a transportation method using a conventional roller table.

FIG. 5 is an explanatory view of a transportation method using a conventional swivel conveyor.

[Explanation of symbols]

 1 wire rod 2 roll 3 roller conveyor

Claims (2)

[Claims] 1. A method of immersing a loose-coil-shaped hot-rolled wire rod in a cooling medium and carrying the wire rod. In order to alleviate overlapping of the wire rods, the wire rods are fed while continuously moving up and down, A method for transporting hot-rolled wire rods, characterized in that contact and separation are repeatedly caused at overlapping portions of the wire rods. 2. A method of immersing a loose-coil-shaped hot-rolled wire rod in a cooling medium and transporting the hot-rolled wire rod, wherein the roll diameter is different from the ring diameter of the loose-coil wire rod in order to reduce overlapping of the wire rods. And a roll interval is adjusted so that the wire rods are continuously moved up and down, and the wire rods are repeatedly contacted and separated from each other, and the hot-rolled wire rods are conveyed.