US1339998A - Shaped filament - Google Patents

Description

D. K. WRIGHT.

SHAPED FILAMENT. APPLlCA-TlON FILED SEPT. 10, m1.

Inventor: Dan iel K.W g

Patented May 11, 1920.

UNITED s'raras PATENT OFFICE.

DANIEL x. wmiinr,

OF PATERSON, NEW JERSEY, ASSIGNQB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SHAPED FILAMENT.

Patented May 11, 1920.

Original application filed April 115, 1914, Serial No. 832,121. Divided and this application filed September 10, 1917. serial No. 190,512:

To all whom it may concern:

Be it known that I, DANIEL K. WRIGHT, a citizen of the United States, residin at Paterson, county of Passaic, State of ew Jersey, have invented certain new and useful Improvements in Shaped Filaments, (division of my application filed April 15, 1914, which has matured into Patent 1,265,575, issued Ma 7,el9l8,) of which the following is a speci cation.

My invention relates to the manipulation of metallic bodies in the form of wires or filaments, and more especially to the shaping or forming of metal filaments before they are mounted in incandescent lamps. V

In U. S. Letters Patent Nis l,013,572, granted to Ruppert lV. Sum-an on January 2, 1912, there is described a method for producing shaped filaments of tungsten in which the wire composing the filament is wound on a form or shaping device and heated to a temperature of from 1000 to 1250 centigrade in a furnace. In this case the entire length of the filament and the form on which it is wound are heated to a uniform temperature. I have discovered, however, that if the process is carried out in such a way that the straight portions of the filament are heated to a much higher temperature than that mentioned in the patent and the bends are less highly heated the filament retains its shape much better than when all portions are brought to the same temperature as described in the patent. I am able to accomplish this result simply and economically by passing an electric current through the wire between the points where it makes contact with the form on which it is wound. By this method the operation is carried on much more quickly than by the method of the above mentioned patent and it is not necessary tomse a form composed of metal having a high fusing point as the form itself is not heated to any great extent.

My invention and the advantages thereof will be best understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a perspective v'i-w of a shaping device adapted for use in carrying out my invention and having a wire wound thereon: Fig. 2 is a viewLot' a shaped filament and Fig. 3 shows a lamp mount with the filament in place thereon.

The shaping device shown in Fig. 1 consists of a base 1 which may be of metal, or

if desired, may be of suitable insulating .material. This base carries near its ends two elements 2, 3 in the shape of round pins rigidly connected thereto, which ma be of any suitable conducting material. 'l hese pins should have a smooth clean surface in order to provide good contact with the wire and are preferably of large cross-section in comparison with the wire. If the base is of conducting material at least one of these pins should be insulated therefrom. This may be done by an insulating fiber bushing 4 as shown.

In the production of simple sinuous zigzag filaments with this shaper the wire 5 of uniform crosssection is wound back and forth between the pins 2 and 3 in the following manner; starting from the end 6 it is first carried around the pin 3 in a clock wise direction then around the pin 2 in a" conliter-clockwise direction, then around the pin 3 again in a clockwise direction, etcl, so that when viewed from above the elongated coil of wire presents the ap )eara nce of a crossed belt or the figure 8. n practice the turns of wire are wound close together to ccono'mize space though in the drawing, for the sake of clearness, the turns are shown as considerably separated. The end 6 of the wire may be secured by wrapping around the cleat 7 attached to the end of the base. ll'hile for the sake of clearness the opposite end of the wire is slfe as simply exten'ding past the pin 2 a short distance this end also may be secured by wrai-ipingaround the cleat 7.

When the winding of the desired .amount of wire on the shaper has been completed the pin 3 and base 1 are connected to a source of current by suitable contacts shown conventionally at 11 and a sufficient amount of current allowed to pass through the wire on the shaper to heat it to a white heat which in the case of tungsten may be a temperature of about 2000" C. This heating should be carried on in a vacuum or an atmosphere of a non-oxidizing gas to prevent oxidation of the wire. In practice I find it most convenient to place the shaper in a bell jar filled with a mixture of hydrogen and nitrogen known as forming" gas. \l'ith this arrangement it will be seen that the portions of the wire which are bent around the pins will carry but a very small part of the current flowing through the straight portions and also because of their contact with the comparatively large mass of metal of the pins will not be appreciably heated. When heated in this way I find that the straight portions of the wire lose much of their original resiliency and become more flexible and that the tendency of the wire to kink upon its removal from the shaper is entirely eliminated. By this treatment however the bends are given a permanent set but are still to resilient that when. the convolutions are removed from the pins and separated the filament readily takes and retains the form shown in Fig. 2.

The length of time required to complete this operation is very short. In most cases the desired result is accomplished by passing current through the wire for one quarter of a second. \Vhile I have shown only a few turns of wire on the shaper it will usually be found desirable in practice to wind enough wire on the shaper at one time to provide filaments for a large number of lamps. A wire which has been treated in this way may even be Wound upon a spooland. upon unwinding, it will, by reason of the fact that the bends are given a permanent set, tend to assume the form shown in Fig. 2.

The shaped filament may easily be removed from the shaperand placed on the supportin frame or spider 8 as shown in Fig. 3. he distance between the pins 2 and 3 having been properly chosen for the support to be used the bends in the filament will engage the hooks of the light resilient holders 9 and the ends may be secured to the leadin -in conductors 10 in any desired manner. iy this means it will be at once apparent that it will be possible to provide a plurality of filaments of equal length. Each filament will be composed of sections of equal length and when mounted on the supports the tension on all sections will be equal. If desired, the filaments may be transferred directly from the shaper to the frame.

have shown and described a method for shaping a single form of filament it will be apparent that the same method may equally well be applied to the fprming of filaments of various shapes by Slllljtble modifications in the shaping device use What I claim as new and desire to secure by Letters Patent of the United States, is

I 1.. A shaped wire of uniform cross section having certain portions which are more flexible than other portions and adapted to be mounted in an incandescent lamp to form a continuous filament having a plurality of loops.

2. A shaped continuous filament of tungsten of uniform cross-section comprising a res lient bend separating straight portions which are more flexible.

3. A continuous tungsten wire of uniform cross-section having uniformly distributed along ltS length comparatively short resilient portions separated by longer more flexible portions.

4. A continuous tungsten wire of uniform cross-section having distributed along its length comparatively short resilient portions separated by longer more flexible portions, said resilient portions having a permanent set in the form of a beml adapted to pass over the usual support for an incandescent lamp filament, and the length of the more flexible portions being such that the wire is adapted to be readily placed on supports to form a filament for an incandescent lamp.

5. A continuous tungsten wire of uniform cross-section having distributed along its length a plurality of comparatively; short resilient portions separated by longer more flexible portions, said resilient wrtrons him mg a permanent set in the tom: of a ben adapted to pass over the'usual support for an incandescent lamp filament, and the length of the more flexible portions being such that the wire is adapted to be readily placed on supports to form a filament for an incandescent lamp, said wire having a large enough number of resilient and more flexible portions to form a continuous incandescent lamp filament having a plurality of loops.

In witness whereof, I have hereunto set my hand this (5th day of Septemben 191T.

DANIEIJ K. WRIGHT.

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