JPS6242684B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a manufacturing method for obtaining a wire rod having a uniform wire diameter. In order to obtain a wire having a predetermined wire diameter by wire drawing, the wire is passed through a wire drawing die having a hole diameter corresponding to the predetermined wire diameter. However, even if the processing conditions are constant in this wire drawing process, the diameter of the rear end of the resulting wire may be smaller than a predetermined wire diameter. In particular, in hot processing, especially for wire drawing processing at high temperatures such as high melting point metals such as tungsten and molybdenum, even if the heating conditions of the wire rod and the heating conditions of the wire drawing die are kept constant. This phenomenon often occurs. As a result of repeated research focusing on this point, the inventors have developed a manufacturing method that makes it possible to obtain a wire with a uniform wire diameter over the entire length by keeping the actual processing conditions constant, rather than the apparent processing conditions. This is what we discovered. That is, the present invention is characterized in that the wire drawing process is performed while keeping the temperature of the wire drawing die constant from the start to the end of the wire drawing process of the wire rod to be processed. Particularly in hot wire drawing processing, which is performed by heating the wire drawing die, the wire drawing process is performed while keeping the temperature of the wire drawing die constant by controlling the heating means of the wire drawing die during the wire drawing process. It is characterized by The method of the present invention will be described in more detail. During wire drawing, if you closely observe the temperature of the wire drawing die, you will find that even if the drawing speed is constant and the surrounding temperature is constant, the wire in the die comes into contact with the wire due to friction with the passing wire immediately after the start of the process. It is thought that the temperature of the part increases locally, maintains equilibrium in this state at a certain temperature, and then maintains that state until the wire drawing is completed. An increase in the local temperature of the wire drawing die changes the hole diameter of the wire drawing die. In other words, if the temperature of the part of the wire drawing die that comes into contact with the wire increases locally at the start of wire drawing, the temperature of the outer surface of the die remains constant and the outer diameter does not change, so the hole diameter of the wire drawing die becomes smaller. It is presumed that this state will continue from then on and the diameter of the obtained wire will become smaller. The present invention focuses on the conditions that are thought to occur in such wire drawing dies, and provides a method for making the wire diameter of the obtained wire uniform over the entire length without causing these phenomena. It is. That is, as the temperature of the inner diameter portion of the wire drawing die increases, the heating conditions from the outside of the wire drawing die are changed to eliminate the phenomenon of a decrease in the hole diameter of the wire drawing die. Specifically, for example, the burner that heats the wire drawing die is composed of a main burner and an auxiliary burner, and when the wire drawing process starts, the main burner and the auxiliary burner are used to heat the wire drawing die, and the temperature of the inner diameter of the wire drawing die increases. By stopping the auxiliary burner when this happens, the wire drawing process can be performed while keeping the temperature of the wire drawing die constant. Examples will be described below. The method of the present invention was applied to tungsten wire that was subjected to hot wire drawing. As shown in the figure, diameter 1~
A 4mm tungsten wire 1 is passed through a heating furnace.
After heating to 800 to 1200°C, wire drawing was performed using a wire drawing machine 4 through a wire drawing die 3. When starting the wire drawing process, the wire drawing die is heated by the heating burner 5 and the auxiliary burner 6 to maintain the wire drawing die temperature.
The temperature was maintained at 450 to 500°C, and after a predetermined period of time, the auxiliary burner was stopped. By doing this, when the auxiliary burner is stopped, the temperature of the wire drawing die is maintained at a predetermined temperature of 450 to 500°C due to heat increase due to friction with the passing tungsten wire and heat conduction from the tungsten wire. A nearly constant temperature is maintained until the wire drawing is completed. When a tungsten wire drawn by the method of the present invention described above was compared with a tungsten wire drawn conventionally by constant die heating, the following results were obtained.

[Table] As is clear from the above table, the wire rod according to the present invention was uniform over the entire length, whereas the wire rod according to the conventional method had a smaller wire diameter from the middle part to the end. Become. In this embodiment, a heating burner and an auxiliary burner are provided as heating means for the wire drawing die, but heating means such as an electric heater may also be used. The use of an auxiliary burner is advantageous in that it can use the same heating source as the heating furnace, which normally uses combustion gas as the heating source. A heating means using an electric heater or the like has the advantage that the heating state can be easily controlled. In addition, in this example, the auxiliary burner was stopped after a predetermined time elapsed from the start of wire drawing based on the fluctuations in the wire diameter that were known in advance, but the temperature of the wire drawing die was continuously measured. A more preferable effect can be obtained if the wire drawing die is heated in such a way that the temperature of the wire drawing die is more accurately kept constant in accordance with the measured temperature.

[Brief explanation of the drawing]

The figure shows an embodiment of the present invention. 1...Tungsten wire, 2...Heating furnace, 3...
... wire drawing die, 4 ... wire drawing machine, 5 ... heating burner, 6 ... auxiliary burner.

Claims (1)

[Claims] 1. By reducing the heating amount of the wire drawing die from the start of wire drawing to the middle of wire drawing, the temperature of the wire drawing die is kept constant from the start to the end of processing a workpiece having a wire diameter of 1 mm or more. A method for producing a high melting point metal wire having a uniform wire diameter, the method comprising performing wire drawing while maintaining a uniform wire diameter. 2. A heating means for heating the wire drawing die and an auxiliary heating means for assisting this heating are provided, and the heating means and the heating auxiliary means are used at the start of the wire drawing process, and the heating auxiliary means is controlled during the wire drawing process. A method for producing a high-melting point metal wire having a uniform wire diameter according to claim 1, wherein the heating conditions of the wire die are changed to keep the temperature of the wire drawing die constant. 3. The method for producing a high melting point metal wire having a uniform wire diameter according to claim 1 or 2, wherein the workpiece is a tungsten wire or a molybdenum wire.