JPS5846571A - Tubular tungsten wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tungsten wire for bulbs, and particularly to a tungsten wire suitable for filaments for incandescent light bulbs.

Generally, filaments for tubes are made of a thin wire made of a strong metal with a high melting point, such as tungsten, and depending on the application, rhenium or other dopants are also added to this wire (hereinafter referred to in this specification). (Generally referred to as tungsten wire, including tungsten alloy wire and wires with dopants added.)

If the tungsten wire is significantly deformed due to heat, it may be coiled and incorporated into a bulb as a filament when lit. This will cause the coil to meander, elongate the pitch, or cause the pitch to become clogged, making it difficult to maintain the specified illuminance. Not only was this deformation unsustainable, but this deformation caused local overheating, which caused premature wire breakage.

The present invention was made to solve these problems, and involves bending a tungsten wire of a predetermined wire diameter into a V shape, and opening the open end to 10 to 30% of the length of the leg. When the tip is gradually heated to the secondary recrystallization temperature while being fixed in the horizontal direction, the hanging length of the tip is 1 of the length of the leg.
It is an object of the present invention to provide a tungsten wire for a tube, which is characterized by having a tungsten wire of /3 or less.

The amount of droop at the tip of the tungsten wire bent into a V shape in the present invention is measured as follows.

That is, as shown in FIG. 1, a tungsten wire 1 of a predetermined wire diameter, for example, MG90, is bent by 180" to a length Y (for example, about 90 m), and the cut ends 2.6 are
is fixed horizontally at a distance of about 10 to 30% (for example, 16 cm) of Y, and then gradually heated to the secondary recrystallization temperature (until recrystallization is completed), and at this time, the other end 4 Hanging length
The value of is set aside.

The heating conditions at this time were from 1700°C to 220°C.
It is preferable to raise the brightness temperature to 0° C. (secondary recrystallization temperature) while holding the temperature at 100° C. intervals for 1 minute.

Note that it is desirable that the tungsten wire be formed in advance in hydrogen at a temperature below the recrystallization temperature (for example, held at 1600° C. for 5 minutes).

In the present invention, the hanging length X at this time is limited to a value of 1/3 or less of Y, but this is because if the value of X exceeds 1/3 Y, the amount of thermal deformation of the wire becomes too large. This is because, for the reasons mentioned above, a light bulb with a long life and stable efficiency cannot be obtained.

Furthermore, for the same reason, it is desirable that the tungsten wire used in the present invention has a tensile strength (tensile strength) of 50 I or more per MG.

Next, examples will be described.

Example AlB, C, selected from MGIO tungsten wire
A hairpin with a length of 130cm was made using 4 samples of D, the end was opened to 221111, held vertically, and heated in hydrogen for 1
After molding, apply a weight of 20 II at 000℃ for 5 minutes, hold the open end horizontally, 161El apart, and fix Y at 90-, and raise the temperature from 1700℃ to 2200℃ while holding for 1 minute at every 100℃.゛ Drooping length of the tip
was measured. In addition, the results of measuring the tensile strength of these samples are shown in the following table ζ:

Next, these samples were formed into a coil shape, which was assembled into a tube, and the presence or absence of deformation of the filament after the flushing test was examined. These results are shown in the same table.

As described above, the tungsten wire that meets the conditions ζ2 of the present invention is less deformed by heat. Further, the tungsten wire according to the present invention was incorporated into a 100V40W general light bulb, and the lifespan fluctuation rate was investigated, and as a result, it was improved by 5 to 10% compared to a light bulb using a comparative example tungsten wire.

Incidentally, such a large difference sometimes appears between tungsten wires having the same wire diameter, and this is thought to be due to the following reasons.

That is, the strain that occurs during the manufacturing process of the tungsten wire is released by the brushing process that occurs during the lamp manufacturing process, but it is thought that the larger the strain, the greater the thermal energy required to release the strain, and the easier it is to deform. From this point of view, it has been confirmed through experiments by the inventors that the strain of the tungsten wire can be expressed by the wire's tensile strength ζ: It has good properties and satisfies the above-mentioned X/Y ratio of 1/3 or less.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method of measuring drooping length in the present invention. FIG. 2 is a graph showing the preferred range of tensile strength depending on the wire diameter of the tungsten wire. 1 ... Tungsten wire (7317) Representative patent attorney Noriyuki Chika (and 1 other person)

Claims (1)

[Claims] t A tungsten wire having a predetermined wire diameter is bent into a V shape,
When the open end is opened by 10 to 30% of the length of the leg and fixed horizontally, the hanging length is 1 of the length of the leg when gradually heated to the secondary recrystallization temperature. A tungsten wire for tubes characterized by having a wire of 3 or less. 2. The heating rate to the secondary recrystallization temperature is 100% per minute.
The tungsten wire b for a tube according to claim 1, which is a percentage of °C.