JP2004332107A5 - - Google Patents

Description

According to a third aspect of the present invention, the steel wire to be supplied is a hot-rolled wire, and one end of the wire is pulled out in the axial direction of the coil in a state where the coil is allowed to stand and supplied to the line. It consists of one drawing die (including a stacking die) and a capstan, and the wire material is drawn out by the wire material feeding device and formed into a true circle, an ellipse, or an oval shape. A continuous heat treatment method according to the first or second invention.

According to a fourth aspect of the present invention, when the cross-sectional area detected and calculated between quenching and tempering is out of a specified range, or when a surface defect is detected in the same section, the tempering temperature is set to a predetermined value for the relevant portion. more 50 ° C. or higher, a first or second or third continuous heat treatment method according to the invention is characterized in 100 ° C. to cause excessive softening is changed to a high temperature of below.

Next to該線material 2 typically solenoid type high frequency heating primary heating device 6 made of a coil through upper _C3 point A, 50 ° C. or more, is heated to 0.99 ° C. or less and held briefly. The temperature is near the lower end of the normal temperature range suitable for quenching. The metal structure of the material becomes austenite. Next, the wire 2 passes through a secondary heating device 8 composed of a normal solenoid type high frequency heating coil, is heated to 50 ° C. or more and 250 ° C. or more above the primary heating temperature, and further softens. Stretching occurs due to tension.

Claims (1)

In the line-type continuous heat treatment method in which a steel wire is run in a straight line and heated, quenched, and tempered for the entire length under the same conditions, 1) tension is applied to the wire to increase the cross-sectional area of the wire at a high temperature portion by 20% or more. 2) The method of applying the tension is performed by the speed difference between two wire feeding devices arranged on the upstream side of the heating and the downstream side of the quenching, and 3) the method of heating is performed. a _C3 point over 50 ° C. or more, after the primary heating to 0.99 ° C. or less, in the upstream side nearest the cooling-the hardened position high frequency induction heating by the primary heating temperature from 50 ° C. or higher, quickly to a high temperature of 250 ° C. or less 4) The quenching cooling rate and cooling time are set to be larger than those required for dieless drawing and quenching, respectively. 5) The method of adjusting the cross-sectional dimensions of the product is before and after reduction. Cross section of The ratio is made by inverse proportion to the speed ratio of the both wire feeder, continuous heat treatment method for steel wire rod, characterized in that.