JPS636740A - Manufacture of tungsten coil filament for bulb - 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 [Technical Field of the Invention] The present invention relates to an improvement in a method for manufacturing a tungsten coil filament used as a light source filament in a bulb, such as a non-fluoridated incandescent light bulb.

[Technical background of the invention and its problems]

Tungsten coil filaments, which are used as light sources for bulbs such as halogen-containing incandescent light bulbs, are made by winding tungsten wire around a primary mandrel made of molybdenum or other material.The primary coil is then wound around a secondary mandrel made of steel or other material. Some use a double coil filament with a secondary coil formed.

The tungsten double coil filament is wound around the secondary mandrel to form a secondary coil, and then the secondary mandrel is pulled out and placed in a dry hydrogen atmosphere at 1,600°C and 8°C with the primary mandrel still inserted. It was heat treated at a temperature of A temperature of around 1,600'C is necessary to maintain the coil shape of the double-coil filament, but this temperature causes molybdenum in the primary mandrel to diffuse into the tungsten filament and blacken the glass pulp of the light bulb. There was a problem that it could cause Furthermore, the double coil filament shrinks during the heat treatment, making it difficult to maintain a constant length between the individual filaments. Furthermore, after the above heat treatment, the primary mandrel is melted and subjected to electrical heat treatment in a forming gas containing, for example, 25% by volume hydrogen and the remainder nitrogen. If the temperature of the filament is slowly raised during this heat treatment, an optimal tungsten coil filament with large crystal grains can be obtained, but if there is nothing to support the coil filament during this heat treatment, large deformation will occur in the coil portion. However, if the temperature is raised rapidly in a short period of time to avoid deformation of the coil part, the tungsten crystal grains become smaller and the sr
Although initial deformation of the filament can be prevented when the bulb is turned on, the problem is that the deformation progresses over time.

[Purpose of the invention]

The present invention has been made to solve the above problems.

To provide a method for manufacturing a tungsten filament for a bulb, which prevents deformation when the tungsten filament is lit as a light bulb, etc., and has stable dimensions with extremely little blackening of the bulb, etc. The purpose is to

[Summary of the invention]

The present invention involves the steps of: winding a primary coil in which tungsten wire is wound around a primary mandrel; winding the primary coil around a secondary mandrel; removing the secondary mandrel; and inserting the secondary coil into a jig coil; Primary heat treatment is performed while the coil is inserted into the jig coil.

This is a method for producing a tungsten filament for a tube, characterized by comprising the steps of performing a primary mandrel bath, performing a secondary heat treatment, and then removing the secondary coil from the jig coil.

[Embodiments of the invention]

The details of the manufacturing method of the present invention will be explained.

In order to manufacture a tungsten double coil filament for use in a bulb, e.g.
1 (length 200 tttx weight 17.50cm) of tungsten wire is passed through a molybdenum primary mandrel Ki times (% mandrel 460) Lte 1 with a diameter of 0.35 jIx
A secondary coil is manufactured, and the diameter of the primary coil is 1.1 mm.
Winding on the secondary mandrel of punishment steel (% mandrel 2
19) A secondary coil was manufactured and the secondary mandrel was removed. The secondary coil from which the secondary mandrel was removed was inserted into a tungsten jig coil with a diameter Q of 40 mx, which was wound so that the inside matched the predetermined pitch and outer diameter of this coil. The attached figure is a front view showing a state in which the jig coil is pivoted and inserted into the jig coil, with a part of the jig coil cut away.

It is a figure which abbreviate|omits the coiling of a primary coil and shows.

In other words, a primary coil (1) formed by winding a tungsten wire (not shown) around a primary mandrel, and a secondary coil (2) formed by winding it around a secondary mandrel are placed in a jig coil (3). The jig coil (3) is inserted in a rotational manner matching the pitch of the jig coil (3). Then, while the secondary coil (2) shown in FIG. 1 remains inserted into the jig coil (3), heat treatment is performed by heating it to 1,500'CK in a dry hydrogen atmosphere in a hydrogen furnace. Next, the primary mandrel is melted with the secondary coil (2) inserted into the jig coil (3), and then the secondary coil (2) is inserted into the jig coil (3).
For example, 25% by volume of hydrogen,
Heat the remaining nitrogen to 2,200°C in 3 ohm gas. Secondary recrystallization of the tungsten filament is completed by heating in the forming gas. After that 2
The method for producing a tungsten filament of the present invention involves rotating the secondary coil (2) and separating it from the jig coil (3). This is because the first heat treatment involves inserting the coil into the coil and shaping the coil, the first melting of the mandrel, and the second heat treatment.

For example, by gradually raising the temperature during secondary heat treatment, the double coil filament does not deform, and the tungsten crystal can be made longer, and the coil filament remains fitted in the jig coil even during heat treatment. , so the coil filament does not shrink.

Note that in the above embodiment of the present invention, the coil filament 2
The next heat treatment temperature was 1,500°C.

Since the heat treatment is performed within the jig coil, it can be shaped without any problem even at a low temperature of about 1,300'C, and therefore, there is no diffusion of warp densities from the mandrel into the tungsten filament, and blackening can be prevented.

In addition, the secondary and secondary heat treatments are not limited to the methods described in the above embodiments, and may be indirect heating of the coil filament in a furnace or direct heating by passing electricity through the filament, and the surrounding atmosphere may be hydrogen, forming gas, or It can also be used in a vacuum.

Furthermore, the present invention manufactures a long jig coil.

After processing a long coiled filament, it may be cut into a predetermined size to obtain a single filament.

In addition, the present invention has been explained using a tungsten filament for an incandescent light bulb for general lighting containing nitrogen as an example.
It is highly effective when applied to the filaments of other light bulbs, and can also be applied to the tungsten filaments of other bulbs such as discharge lamps.

Also, the diameter of the tungsten filament.

The diameter of the mandrel and the diameter of the jig coil wire are not limited to those in the embodiments (in short, it is sufficient that the jig coil has an inner diameter and pitch that match the predetermined dimensions of the coil filament.

〔Effect of the invention〕

The present invention includes a process of winding a primary coil of tungsten wire around a primary mandrel and winding it around a secondary mandrel, and then rotating and inserting the secondary coil into a jig coil from which the secondary mandrel is removed. Primary heat treatment is performed while the coil is inserted into the jig coil.

A method for manufacturing a tungsten coil filament for tubes, comprising the steps of performing primary mandrel melting, secondary heat treatment, and then separating the secondary coil from the jig coil, the method comprising: Since the coil is heat treated while inserted into the jig coil, there is no deformation of the double coil shape.

Moreover, since the heat treatment temperature can be lower than that of conventional traps, it is possible to prevent the molybdenum of the mandrel from diffusing into the tungsten. It is possible to perform secondary recrystallization during forming while maintaining the dimensions with a jig coil, and furthermore, it has the excellent effect that deformation of the filament does not occur due to the elongation of crystal grains during recrystallization.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a partially cutaway front view showing a tungsten filament inserted into a jig coil in the middle of a tungsten filament manufacturing process according to one embodiment of the tungsten filament manufacturing method of the present invention. ]...Primary coil, 2...Secondary:l3...Jig fill

Claims (1)

[Claims] A process of winding a primary coil of tungsten wire around a primary mandrel and winding it around a secondary mandrel, removing the secondary mandrel, and inserting the secondary coil into a jig coil, and a process of rotating and inserting the secondary coil into a jig coil. A tube for a tube comprising the steps of performing primary heat treatment, primary mandrel melting, and secondary heat treatment while inserted into the jig coil, and then removing the secondary coil from the jig coil. Method of manufacturing tungsten coil filament.