US2383113A - Means for uniting parts - Google Patents

Description

Aug 21, 1945- i H. J. DAILY 2,383,113

MEANS FOR UNITING PARTS Filed Jan. 16. 1942 ATTORN EY Patented Aug. 21, 1945 MEANS FOR UNITING PARTS Hampton Jennings Dailey,-Bloomield, N. J., as-

signor to Westinghouse Electric Corporation, -East Pittsburgh, Pa., a corporation of Pennsylvania Application January 16, 1942, Serial No. 426,965

8 Claims.

This invention relates to means for uniting parts and more especially to an electrical means for uniting bulbous glass parts.

It is common practice in the manufacture of electronic devices to provide a glass enclosure or envelope, and as the present invention has particular utility in connection therewith, the exempliiication illustrated and described will be directed thereto, but with the understanding other uses, embodiments, materials and configurations may be employed. Accordingly, it may be said that various electronic devices employ different sizes and shapes of stems and enelopes, but in most instances require sealing or uniting of the envelope portion to the stem portion of the glass after iirst mounting the various electrodes on the stem. This sealing has heretofore been accomplished by melting or fusing the glass of the two parts at abutting edges with heat from a gas flame. Several disadvantages arise in use of such a dame as a melting means. One is the detrimental effect of the prolonged high temperature upon the electrode or other internal parts of the device, especially where physically close to the joint or line of sealing.` Another disadvantage arises irom the fact a flame-seal is non-homogeneous; the glass melts to a softer consistency and fusing temperature at the outside of its wall and is apt to leave a lessflrmly sealed part or even a crevice at the inner side of the wall. Furthermore, use of a iiame for sealing introduces the necessity of lengthy annealing stages which is also accompanied by oxidation occurring on metallic parts in the device. These and other disadvantages of use of flame-sealing have presented a problem which this invention has successfully solved.

The objects of the invention may accordingly be generalized as the provision of a means for overcoming the difficulties and disadvantages lnvolved in connection lwith name-sealing as heretofore employed.

More specifically, an object of the present invention is to obtain a uniform seal for the entire thickness of the abutting portions being sealed.

Another object of the invention is to avoid oxidation and other detrimental effects upon parts within the envelope.

Yet another object of the invention is to promote rapidity of sealing and reduction of annealing requirements.

A further object of the invention is to obtain a smooth joint and one wherein no material increase of thickness results.

A-still further object of the invention is to take advantage of electrical heating in glass of the RI2 effect and to reduce dielectric losses adverse to efficient current use.

Additional objects of the invention will appear as the description progresses, either by direct statement thereof or by implication from the-context.

In the accompanying drawing wherein like numerals of reference indicate similar parts throughout the several views;

Figure 1 is a sectional View of a portion of an envelope sealed in accordance with my invention and shown as part of an electron discharge device;

Figure 2 is a similar partial section of the envelope in process of being sealed and showing the sealing means associated therewith and making initial contact with the envelope;

Figure 3 is a cross-sectional view on line III- III of Fig. 2; andl Figure 4 is a sectional view similar to Fig. 2 and showing the sealing means as having completed the sealing of the joint.

'In the speciiic embodiment of the invention illustrated in said drawing, an electron discharge device is shown of the type having a bowl-like base portion I0 the upper outer edge of which is, in the finished device, sealed with respect-to an envelope portion II and forming a bulbous enclosure. The base portion Iii is provided with a tubulation l2 for exhaust and other purposes, and also is provided with suitable terminal prongs I3 and lead-in posts Iii sealed with respect to the base. Certain of the posts carry a transverse plate I5 which of necessity is near the region Where the glass has to be sealed. The plate shown constitutes a mounting for a grid I6. Other electrodes, namely a cathode I'I and anode I8 are shown associated with said grid as usual.

In normal manufacture, the several prongs, posts, plate and electrodes are assembled with respect to each other and the glass base I0. Then the envelope portion II is applied with the margin of its open en`d contiguous to the upper edge of the base. at I9 is then to be sealed by my improved means. It is to be understood that the base and envelope are suitably carried coaxially of eaclr other as usual in the lamp machine M so as to be simultaneously rotated on their common axes. Next the junction to be sealed is provided a burner 20 for applying a llame '2| to the glass of the envelope and base contiguous to the'junction I9. That burner, representative of as many as may be desired around the envelope at the stage set- The junction thus presented ting of the machine, is for purposes of preheating the glass in the region of the junction.

At high temperatures, such as can be accomplished by flame 2l, glass becomes a partial conductor for electrical current. I utilize this phenomenon for a useful purpose. The junction is fused into a joint, numeral I9 designating the area of junction and joint. A combined partial length of junction and joint is involved in transition from status of junction to status of joint, this cliange of status occurring between two brushes 22, 22 which are appropriately remote from each other both electrically and physically in a direction lengthwise of said junction and joint. As high a frequency as is practical to generate is applied across the said brushes, here depicted as accomplished by transformer 23. The circuit includes the portion of the heated glass intervening between the brushes, and due to the RI effect in the glass, the glass at the combined partial length of junction and joint between the brushes becomes heated. In order to take advantage of the heating eifect in the glass, not only of the RP effect, I prefer to use the said highest practical frequency, as stated, so as to take advantage of the dielectric losses which are proportional to frequency.

The electric current thus flowing in the glass heats the glass to the fusing temperature, thereby obtaining a unified joint between the two parts. Since the current flows throughout the thickness of the glass, the seal effected at the inner periphery is as secure and continuous as the seal at the outer circumference. Furthermore the heating by current flow and opposing resistance in the glass obtains intense heat where needed, evenly distributed and highly effective for sealing purposes without producing oxidation or other deleterious effects on the electrodes or other parts of the device. A shorter sealing time is required than with the prior art method and apparatus and less annealing is necessitated.

`The specific apparatus here disclosed for accomplishing the method, comprises a movable support, shown as an arm 2l pivoted at 25 with the aforementioned brush 22 carried by the end of the arm nearest the Joint to be sealed. Suitable hlectrical insulation 26 is interposed between the arm and brush. The other end of the arm 24 has"an adjusting bolt 21 therethrough adapted to be engaged by a retractable spring actuated plunger 2l. Spring 29 actuating the plunger is representative of any suitable means for applying desired pressure to the brush into contact with the glass. It will be appreciated that the glass softens when heated, and accordingly pressure of the brushes is limited to avoid undesired deformation of the envelope and base. If desired, air pressure can be admitted through tubuiation I2 to sufficient extent to counteract the mechanical pressure of the brushes and prevent undesired indentation of the glass wall while soft.

The facial contour of the brush which is in contact with the glass during forming operation is preferably shaped to conform to the desired shape of envelope and base at the joint. In the present instance I have shown the facial contour of the v engaging portion to be, in section, concave, so that,

with the gloss softened and rotating, a rounded peripheral shoulder is produced on the envelope. l'he final glass shape desired will be that of the concave face of the brush.

The brush preferably provides a current conducting area It and a.4 non-conducting area 3|. Since the heating will take place in the glass over a wider area than the conducting contact surface 2,sss,11a

of the brush, the non-conducting areas avoid increasing the heated area and obtain a smoothing guiding contact with a part of the glass which is cooler and more resistant to pressure.

Accordingly the portions 0f the brush, at top and bottom thereof, preferably are comprised of electrically insulative and heat resistant material and each forms a continuation of the glass engaging face or area of the metallic or conductive part of the brush and along the edges of the brushes paralleling the junction and joint. This arrangement accomplishes a smoothing engagement without carrying the conductive and heating contact over as extensive an area. 4It is appropriate to mention at this point that the parts to be sealed do not have to be at a corner, but a Joint may be made wherever desired, the face areas of the brush being shaped accordingly.

In operation, the electronic or other device is applied in the lamp-making machine and rotated and revolved as familiar to those skilled in the art. At each stage of the revolving cycle, an appropriate fabricating step is performed. It is preferably to apply flame or flames 2l to the junotion area at one stage of revolution and there preheat the glass. The electrical brushes may, if desired, be in contact with the glass during this preheating stage and continue the heating immediately the glass becomes hot enough to pass the applied high frequency current. However, it is within the scope of the invention to apply the preheating by flame 2i at one stage of the rotative cycle of the machine, and apply the high frequency current heating at the following stage. The important factor is that the high frequency current flows in the glass for the full thickness of the wall thereof so that a homogeneous seal is obtained without any crevice occurring. The current flow within the glass itself concentrates the heating effect in the glass and with least detrimental effect upon closely associated metallic parts, such as plate I5, and furthermore heats quickly and requires minimum annealing time or attention.

Since the various details of construction and steps involved in the method, as well as the precise relation and functioning of parts are subject to variation and change without departing from the inventive concept or scope of the invention, it is intended that all matter contained in the specification or illustrated inthe drawing, shall be interpreted as exemplaryv and not in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein shown and described and all statements of the scope of the invention herein set forth as a matter of language which might be said to` fall therebetween.

I claim:

1. A means for sealing a junction between glass parts of a bulbous enclosure to formy a closed joint .thereat, comprising means for making electrical contact with the glass contiguous to the junction and joint and at parts separated lengthwise of the junction and joint, said means having a surface portion for making surface contact with the glass on both sides oi the joint, and. said means having electrically nonconducting areas toward the glass and forming part of said surface for making guiding contact with the glass.

2. A means for sealing a junction between glass parts of a. bulbous enclosure to form a closed joint thereat, comprising means for making electrical contact with the glass contiguous to the junction and joint and at pax-ts separated lengthwise of the junction and joint, said means having a surface portion for making surface contact with the glass on both sides of the joint, and said means having electrically non-conducting areas toward the glass at edges of said surface portion making guiding contact wi-thv the glass and at a part of said surface portion most remote from the joint-engaging part of said means.

' 3. A means for sealing a junction between glass parts of .a bulbous enclosure to form a closed joint thereat, comprising means for making electrical contact with the glass contiguous to the junction and joint and at parts separated lengthwise of the junction and joint, said means having a conducting portion for making surface contact with the glass on both sides of and in parallelism to the joint, and said means having electrically non-conducting areas at edges of said conducting portion toward Ithe glass and paralleling said conducting portion in parallelism to the junction, said non-conducting areas being in surface continuation with the surface contacting area of the electrically conductive portion of said means.

4. A means for sealing a junction between a glass envelope and a glass base to iorm a closed joint thereat, comprising in combination with means for rotating the junction and joint, means for making electrical contact with the glass contiguous to said junction and joint, means for supplying high frequency current to said con-- tact means and progressively along 'the junction and joint for heating Ithe said glass contiguous to and progressively of said junction and joint to fusing temperature, and meansfor pressing the electrical contact means toward the juncture at the area of contact with the glass contiguous to and progressively of the junction and toward and progressively of .the joint at the area of contact with the glass contiguous to the joint for simultaneously fusing the glass next the joint and smoothing the joint as fused.

5. A means for sealing a junction between a glass envelope and a glass base .to form a closed joint thereat, comprising in combination with means for rotating the junction and joint, means for making electrical contact with the glass contiguous to and at parts separated lengthwise of said junction and joint, means for supplying high frequency current to said contact means to flow through the glass separating said contact means lengthwise of the junction and joint for heat-.-

l trical contact with .theglass contiguous to the junction and joint and at parts separated lengthwise of a combined partial length of the junction and joint, said means having a portion making surface contact with the glass on both sides of the junction and joint, and said means having electrically non-conducting areas in contact with the glass in parallelism .to and spaced from the joint, and means for pressing the electrical contact means .toward the joint for simultaneously fusing the glass next the joint and smoothing the joint as fused.

7. A means for sealing a junction between glass parts of a bulbous enclosure to form a closed joint thereat, comprising means for making electrical contact with the glass contiguous to the junction and joint and at parts separated lengthwise of the junction and joint, said means having a portion making surface contact with the glass on both sides of the joint, and said means so having electrically non-conducting areas toward the glass at edges of said portion making contact with the glass in parallelism to and spaced from the joint, and means for pressing the electrical contact means toward the glass for simultaneously fusing the glass next the joint and smoothing the joint as fused.

8. A means for sealing a junction between glass parts of a bulbous enclosure to form a closed joint thereat, comprising means for making electrical contact with the glass contiguous to the junction and joint and at parts separated lengthl wise of the junction and joint, said means having a portion making surface contact with the glass on both sides of the junction and joint, and said means having electrically non-conducting areas at edges paralleling the junction and toward the glass, said non-conducting areas being in surface continuation with the surface contacting area of the electrically conductive portion thereof, and means for pressing :the electrical contact means toward the glass for simultaneously fusing the glass next the joint and smoothing the joint as fused. v

HAMPTON JENNINGS DAILEY.

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