US2401638A - Method of vacuum sealing - Google Patents

Description

June 4, 1946. c. HERZOG E TA.L

METHOD OF VACUUM SEALING 2 Sheets-Sheet l /IIIIIIIIL Filed July 19, 1943 C'arlflerzo a nd PauZA.Hau-ck.

June 4, 1946. I c. HERZOG gm 2,401,638

' METHOD OF VACUUM SEALING Filed July 19' 1943 2 Sheets-Sheet 2 VA CUUM UN 144C (ll/M ON v I p.16: $2.113 tym f'j V4cuum VACUUM 0N 5/101- OFF -3 92 60: rZ Harte an a? Paul AhHau ck.

Patented June 4, 1946 z,4q1,63s'

UNlTED j srArEs PATENT orrica 0..., 11:13:11: fmi ffif, m...

by mesne assignments, to

N- themselves as joint tenants Application July 19, 1943, Serial 110.0534? l The present invention relates to a method of vacuum sealing receptacles.

An important object of the invention is to provide a method of the above mentioned character for vacuum sealing receptacles having metallic parts, metallic receptacles and glass receptacles. A further object of the invention is to provide a method of the above mentioned character for sealing radio vacuum tubes, thermionic tubes and lamps, such as fluorescent lamps, without the use of the usual exhaust tubes attached to the same, whichmay be formed of metal or glass.

A further object of the invention is to provide a method of the above mentioned character which will eliminate the long exhaust tube used in vacuum sealing, 95% of which is usually thrown away. after the sealingoperation is completed. A furtherobject ol the invention is to provide a method of the above mentioned character which will eliminate the use of the compression rubber 14 Claims. (Cl. 226-202) Figure 8 is a central vertical longitudinal section through one end or a fluorescent'lamp and associated vacuum connection,

Figure 8 is a Plan view of the fluorescent lamp,

Figure 9 is a central vertical section through the based the fluorescent lamp, parts broken away,.show ing the use of a cold forming tool and the fusing of the pellet to the base,

Figure 10 is a similar view showing the vacuum connection fused to the upper end of the pellet, with thevacuum cut oil, I

Figure 11 is a similar view showing the vacuum connection fused to the pellet and the vacuum connection and base cold and the vacuum turned on and the plunger raised,

Figure 12 is a similar view, showing the vacuum I connection heated and moved downwardly to close the bore of the pellet, the plunger being nipple of the usual vacuum machine, which nipple receives the exhaust tube carried by the envelope.

Other objects and advantages of the'invention will be apparent during the course of the following description.

In the accompanying drawings forming a part or this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a central vertical longitudinal seca recess or depression formed in the top of the metallic shell, before the base is applied to the shell,

Figure 2 is a similar view, parts broken away, showing a tubular solder material pellet placed within the recess,

Figure 3 is a similar view, parts broken away, showing a cold forming tool engaging the tubular solder material pellet,

Figure 4 is a similar view, parts broken away,

showing the base applied to the metallic shell and a tubular metallic exhaust connection engaging the tubular solder material pellet.

Figure 5 is a similar view, parts broken away. showing the tubular exhaust connection moved downwardly to. close the tubular pellet,

Figure 6 is a similar view, showing the tubular exhaust connection raised andseparated from the tubular pellet, I y

Figure 7 is a central vertical section, parts bro ken away. through a tin can equipped with a recessand tubular pellet for vacuum sealing the same,

in the lowered position and the vacuum on and the base cold, Figure 13 is a similar view, with the parts in the same position with the vacuum connection the pellet filled with additional sealing wax. tion through a radio vacuum tube shell, showing In Figures 1 to 6 inclusive, the numeral l0 designates a metal shell or envelope of a radio vacuum tube or the like. This shell has an upper closed end or part II, provided preferably centrally thereof with a cylindrical inwardly formed portion l2, producing a recess IS. The top of the cylindrical portion I2 is open while its bot-- .and this bore has a length considerably greater than its diameter. Satisfactory results are ob-j tained byhaving thelen'gth of the bore substantially twice that of the diameter of such bore. By employing a tubular pellet having an elongated bore,the lower portion or bottom of the pellet may be chilled or rendered solid or main- .dure.

portion is ing a main bore 22 in communication with a source of vacuum. This bore 22 is in communication with a port 23, communicating with a recess 24 formed in the forward end of the tubular connection 2|. The recess 24 isconcentric with the port 23 and is frustro-conical in vertical cross section, providing a face or wall which tapers upwardly, as shown.

The cylindrical portion |2 forming the recess 13 'is preferably formed upon the metallic shell l while this shell is being produced, but the invention is in no sense restricted to this proce- The shell l0 provided with the recess I3 is now suitably supported in a vertical position with its top I uppermost, and the tubular solder material pellet I1 is inserted within the recess l3, and the shell l0 and pellet I! being cold or at room temperature. When the pellet I1 is inserted within the recess l3, its bottom. contacts with and is supported by the upper end of the tapered head M. The bore of the tubular pellet is larger perature. When the lower end of the tubular pellet I! was heated, as explained, the heat treatment is regulated or stopped before the upper this heat treatment, the upper endof the pellet l1 and tool is may be chilled by blowing cold air upon thesame, and this will prevent. the upper end being sweated or fused to the tool I8.

The above described operations are performed upon the shell l0 previous to the assembly of the base and; elements carried'by the base with the shell. The base which may be formed of glass, is now applied to the lowerend of the shell l0, Figure 4, in'any well known manner and forms an air-tight Joint therewith. Thisbase carries the usual parts of a radio vacuum tube. I

The base 25' is applied to the shell in, as stated, and the shell I 0 is again vertically supp rted with its top. uppermost, and the tubular exhaust connection2| is arranged above the tubular pellet l1 and moved downwardly so that the tapered upper formed end of the pellet enters the tapered recess 24, these parts being correspondingly tathan the port l5 and is slightly larger than the upper end of the tapered head l4, so that the upper reduced end of the head l4 extends for a short distance into the bore of the tubular pellet.

The top of the tubular pellet projects above the top H, as shown.

The cold forming tool I8 is now positioned over the'tubular pellet l1 and its pin I! inserted into "the bore of the tubular pellet, while the top of the tubular pellet contacts with the upwardly ta- I the tubular pellet prevents the tubular pellet from collapsing and maintains its bore open during this cold forming. The downward pressure. upon the tubular pellet, causes its bottom to slide down 7 the inclined face It or the head I4, whereby the top end of the head |4 projects further into the bore of the tubular pel1et.,'.Thisprevents the liability of any small particles of the solder material from the tubular pellet entering the shell "I. After the cold forming step, the downward pressure upon the tool I8 is removed, and only.

pered so that the end fits snugly within the recess. The tapered recess 24 is tinned with solder and engages the upper tapered end of the tubular pellet and is held in firm engagement therewith. Heat is, now applied to the tubular suction or vacuum connection 2|, preferably atabout the point B, Figure 4, and passes by conduction to the engaging faces of the recess 24 and the tubular pellet, and this heat causes the top of the pellet to be fused to the wall ofthe recess 24, forming a solid air tight connection between the tubular vacuum connection 2| and the shell Hi. The tubular vacuum connection 2| and the tubular pellet ll are now cooled to room or atmospheric temperature, which may be effected by blowing air thereon. With the tubular vacuum connection 2| thus rigidly secured to the tubular pellet and forming an air tight connection therewith, the

vacuum valve of the vacuum pump is now opened of vacuum, heatis again applied to the tubular vacuum connection 2|, preferably at about the point B, Figure 4', and passes by conduction to the top 'of the tubular pellet Lcausing the upper portion of the pelletto plastlclze. While this occurs, the tubular vacuum connection 2| is moved downwardly, to follow up the flow of the 'fplasticized solder at the top of the pellet, and

- and downwardly, thereby closing the upper end-of the bore II, by forming a bridge Figure 5.

' This inward moving or forming of the plasticized material toward the center of the bore I1 is effected by the frustro-conical or taperedrecess 24,,

suitably heated, at about the point A, and this heat is transferred by conduction to the lower 'cnd of the tubular pellet, and this lower end is then sweated to the inclined face of the head M pellet and the shell I 0, which are sweated or fused together, are cooled to room or atmospheric temwhen .the connection 2| is moved downwardly. At the same time that the tubular vacuum connection 2| is being heated, the top of the shell l0 is chilled or cooled to prevent the lower portion or bottom of the pellet from plasticizing. This cooling-may be effected by blowing cold air upon :the shell II) at about the point A, Figure 5. Since heat is applied by conduction to thetop of the As soon. as the vacuum connection 2| vacuum and the port 23.

V the closing of the exhaust valve, the closed end creases downwardly of the pellet,'-which is further aided by the chilling of the lower portion of the pellet.- The lower portion of the pellet remains permanently set or solid, while the upper portion increases in plasticity toward the top, and has a maximum plasticity at the top which is in"thermal'contact with the tubular vacuum connection 2|. When the upper portion of the pellet is moved inwardly and downwardly to close the bore l1 and form the bridge H, the closed end. or

bridge Il -is brought into close relationto the chilled lower portion of the pellet l1, and this tends to further chill the bridge l1 so that it is rendered solid throughout the major portion of its vertical dimension, extendingiromits bottom I to substantially its upper face, while the upper face which contacts with the connection 2| remains piasticized. ,"Ihe bore of the tubular pellet is therefore closed at the top but remains open at the bottom. Since the same degree of vacuumis now placed upon opposite sides of the closed end The numeral 23 designates the glass tube or envelope of-a fluorescent lamp, having a glass base 33. Secured to the base 33 are contacts 3|, carrying mount wires 32. Thisglass base is provided centrally thereof with an exterior recess 33, having an opening 34 in its bottom.

or bridge l1 of the pellet, there is no tendency for such closed end to be drawn down into the shell by the vacuum therein.

has moved downwardly and. closed the upper end of the tubular pellet by forming the bridge I1, the

The numeral 33 designates the bodyl rtion of a tubular vacuum connection,.having a pipe 33 connected in its side and which leads to a vacuum p p.

pipe 33, to supply the vacuum, or cut the same oil. 'At its lower end, the-body portion 3315 provided with asleeve- 31, provided at its lower end with a head 38, having a frustro-conical or upwardly tapered face 33. A cylindrical. opening 43 is formed in the head 33 and receives a plunger 4|. This plunger is provided withan intermediate enlarged portion grooves, The plunger 4| extend through an opening 44 and is provided with a connection 43, by means of which the plunger may be raised and lowered with relation to the body portion 35. The

plunger passes through a packless gland 48, as

vacuum connection 2| and shell l0 are chilled by blowing cold air upon the same at the points B and A, respectively, andthe closed pellet "is set and this occurs While the vacuum is still turned on. After the closed pellet has set, thevacuum valve is closed, subsequently to which an upward lifting force is applied to the vacuum connection 2 I, and 'while this is done, the vacuum connection is heated at about the point B and this .heat passes by conduction to the top of the pellet I1, and this produces a plastic or molten layer or film at the top of the pellet, while the remainder of the pellet remains set, and when this occurs the vacuum connection 2| separates from the pellet. We also contemplate the use of a slightly different method. As soon as the vacuum connection 2| has moved downwardly to close the upper end of the tubular pellet and form the bridge I1,

as explained, Figure 5, and while the upper end of the pellet is still plastic, the vacuum connection 2| is raised and separated from the tubular pellet,

and simultaneously with the raising of the vacuum connection, the vacuum valve is closed, cutting ofl communication between thesource of Simultaneously with or bridge H of the tubular pellet is chilled and set-throughout its entire vertical dimension by the lack of heat in the shell and by an additional blast of cold air applied to the top of the pellet.

The pellet should be rendered completely solid or set simultaneously with the breaking. of the vacuum'in the connection 2| exteriorly of the pellet,

so that the vacuum within the shell will not draw particles of solder down into the shell, where they'would cause harmful results. All of the steps of the method remain identical with those hereinbefore described.

In Figure 7'1, isshown a receptacle such as a. tin

can 26', which has been vacuum sealed in accordance with our method. This tin can has a top 21 provided with a recess 28, corresponding to the recess 13, and receiving the tubular pellet II which has been treated in accordance'witheither method described in to 6 inclusive. I

Attention is now called to Figures 8 to 15 in-I elusive.

connection with Figures l and the vacuum valve is closed and the vacuum shown. When the plunger 4| is in the lowermost position, it enters the opening 43 and closes the same and the lower end of'the plunger is then substantially flush with the-face 33, the plunger and face then producing a continuous surface.

lar, pellet having an upper tapered end 50 which was previously formed thereon. Downward pres.-

sure is'applied to the tool 48, while the glass base I 33 is heated, and this heat passes by conduction to the tubular pellet, heating and plasticizing the outer surface or periphery of the tubular pellet and fusingthe same tothe wall of the recess 33 and the base of the same to form a vacuum tight joint between these parts. Before the upper end of the tubular pellet 41 has fused to the cold tool 48, this cold tool is moved'upwardly and separated from the pellet. Instead of using thecold tube 48, as described, the tubular vacuum connection, Figure 10, may be used.- If this is done, the sleeve 31 would be cold and brought down into engagement with the upper tapered end 50 of the tubular pellet, 4 1 and exert a downward pressure upon the same, while the base was heated. This action will fuse the pellet to the walls of the recess 33. ,After the pellet is thus arranged within the recess 33 by the use of the cold tool 48 and fused 'to the wall of the recess 33, the face 33 of the sleeve 31 is brought into contact or engagement with the end so of the pellet,and the base so is 1 chilled, by blowing cold air upon the same while the sleeve 31 is heated and the plunger 4| is in the lowermost position to cover the opening 43 also cut off by the plunger I. This heat passes by conduction through the sleeve 31 to the upper end of the tubular pellet, which has previously set, and the upper 'end of the tubular pellet is plasticizedand is fused to the face 33- of the sleeve 31, Figure 10. The sleeve 31 and base 3|) are now.

A suitable valve (not shown) is con-' nected to the pipe 36 for opening and closing the- 42, having longitudinal oi. the

claims. 7

Having thus described the invention, what is 7 chilled by blowing cold air upon the same so that the pellet 41 and its end which is fused to the face 88 are set, and the vacuum valve is now opened and the plunger 4! is raised to uncover the opening 40, Figure 11, whereby the envelope 28 is placed in communication with the source of vacuum'and properly evacuated. While the I vacuum connection towardthe receptacle to aid pellet and the vacuum connection while said vacuum valve remains open,.the' plunger ll is' moved downwardly to enter and cover theopening Al and the sleeve 31 is heated while the base 30 is chilled. The heat passes by conduction through the sleeve I! to the upper end of the tubular pellet which plasticizes this upper end,

and when this occurs, the sleeve 31 and plunger ll are moved downwardly and press the plasticized upper end of the tubular pellet downwardly and inwardly closing the upper end of the bore oi the tubular pellet by forming a bridge 41, the

in closing the tubular pellet, causingthe closed tu'bular pellet to set, applying atone. to the vacuum connection in a direction from the receptacle, and again heating the outer end ofthe pellet to produce a plasticized layer betweenthe force is applied to the vacuum connectiom 2. The method of vacuum sealing a receptacle having a metallic part, comprising bringing a tubular solder material pellet into contact with the metallic part and placing the bore of the tubular pellet in communication with the interiorof the receptacle, heating the contacting portions of the metallic part and pellet to cause them to fuse together and causing the same to subsequently cool, bringing a metallic tubular vacuum connection into contact with "the tubular pellet lower end of the plunger 4i and the face 38 forming: a continuous surface for this purpose. The

lower end of the tubular pellet remains set due to its contact with the cold wall oi-the recess 33 and the lower end of the bore ll! of the tubular pellet remains open. The vacuum valve remains open during this operation. This operation is shown in Figure 12.

Withthe sleeve 31 in the lowered position and tubular pellet closed, as described, the sleeve 31 is chilled and the base is chilled and the pellet is set, while the vacuum valve remains open,

the plunger II in the lowered position and the 13. The vacuum valve is now closed while the plunger ll remains in the lowered position with the sleeve 31', and a lifting force is applied to the sleeve 31, Figure 14, and sleeve 31 is now heated, .while heat passes by conduction to the upper closed end of the tubular pellet, providing pellet, and when this occurs the sleeve 31 rises and separates from the tubular pellet. When the sleeve 31 is thus separated from the tubularand placing the same into communication with the bore of the tubular pellet, heating the .con-

tacting portions of the tubular vacuum connection and the pellet to causethemto iuse together and then allowing such partsto cool, evacuating the receptacle through the connected tubular vacuum connection and tubularpellet, heating the tubular pellet to plasticize the same, moving the tubular vacuum connection toward the receptacle to close the'tubular pellet, and separating the vacuumconne'ction from the closed pellet. 3. The method of comprising bringing the end of a tubular solder material pellet into contact ,with'the metallic part and placing the more of they tubular pellet in communication withthe opening, heating; the

a plastic or molten him at the top of the closed.

pellet a recess II is formed above the closed pellet ing wax 52, as shown'in Figure 15.

Attention is called to the fact that the solder material I! and the sealing was 41 are both formed of thermoplastic material. The thermoand this recess is filled flush with a layer oi sealplastic material of which the pellet is made, must have a lowermelting point than the envelope to which it is attached, and a higher melting point than the temperature at which the device operates or is used in its final application.

It is to be understood that the forms of our invention herewith shown and described are to be taken as preferred examples of the same, and that various changes in the shape, size, and ar- I rangement of parts may be resorted to, and that.

changes may be made in the order of the steps of the method, without departing from the spirit invention or the scope ot the subioined claimed is:

l. The method of vacuum sealing-a receptacle having an opening, comprising attaching a tubular thermoplastic pellet .to the receptacle for rel-mm: a vacuumtight ioint and .placing the bore 01- the pellet in"communication with the nected tubular connection and tubular pellet,

contacting portions of the metallic part and e'pellet to cause them to fuse together, then causing the contacting-portions to cool, bringing the end of a metallic tubular vacuum connection into contact with the outer opposite end of the tubular pellet, heating, the contacting portions 01' the tubular connection and pellet to cause them to fuse together, then allowing such parts to cool,

evacuating the shell through the connected tubular connection and tubular pellet, again heating the outer endof the tubular pellet to plasticize the same, moving the tubular connection toward the shell to apply pressure to the plasticised outer end of the tubular pellet to close the same,

moving the tubular connection from the tubular pellet while simultaneously cooling the outer closed end of the pellet. 1

4. The method of vacuum sealing a shell having a metallic part, comprising bringing the end of a tubular solder material pellet into contact with the metallic Part and placing the bore. of the tubular pellet into communication with the interior of the shell, heating, the contacting por-. tions and pellet to fuse them together, then causing the contacting portions to cool, bringing the end of a metallic tubular vacuum connection into contact with the outer opposite end or the tubular pellet, heating the contacting portions of the tubular connection and pellet tome them together, then allowing such contacting portions to cool, evacuating the shell through the conagain, heating the outer end of the tubular pellet to plasticize the same whilecooling the. inner end of the tubular pellet to prevent the same being plasticized, moving the tubular connection toward the shell to aid in closing the bore of the tubular pellet by the plasticised solder, moving the tubular connection-from the tubular pellet vacuum"sealingv ashell having a metallic part provided with an opening,

I cooling the outer end of the pellet so that it sets.

5. The method of vacuum sealing a shell having a metallic part provided with a recess having an apertured head, comprising inserting a tubular solder material pellet into the recess so that its inner end contacts with the head, applying pressure 'to the outer'en'd of the tubular pellet to cold form its inner end to correspond to the shape of said head and cold form its outer end into a selected shape, applying heat to the contacting inner end of the pellet and the head to cause these portions to fuse together, then causing these portions to cool, causing the outer formed end of the tubular pellet to enter a correspondingly shaped recess in a tubular vacuum connection; heating the outer formed end of the tubular pellet so that it becomes fused to the wall of the recess, causing these parts to cool, then evacuating the shell through thetubular connection and tubularpellet, again applying heat to the outer end 01' the tubular pellet to' plasticlze the same, then moving the tubular connection axially toward the tubular pellet to aid in closing its bore, then moving the tubular connection axially from the tubular pellet to separate the same therefrom while simultaneously stopping the evacuation of the shell through the tubular connection and tubular pellet and simultaneously cooling the outer end of the pellet so that it sets. a

6. The method of vacuum sealing a shell having a metallic part provided with a recess having an apertured head, comprising inserting a tubular solder material pellet into the recess so that its inner end contacts with the head, applying heat to the shell adjacent to the recess so that the inner end of the pellet is heated by conduc- 10 a ticized portion to close the bore of the tubular pellet, and separating the vacuum connection from the closed pellet while the tubular pellet remains attachedto the receptacle;

8. The method of vacuum sealing a receptacle,

comprising arranging a tubular thermoplastic pel1et with its borein communication with the" interior of the receptaclaefiecting a fused vac uum tight joint between the pellet and the wall of the receptacle, bringing a tapered end wall of a tubular vacuum connection into contact with the outer free end wall of the tubular pellet and effecting a fused vacuum tight joint between such 7 end walls, evacuating the receptacle throughthe connected vacuum connection and tubular pellet, heating the outer portion of the tubular pellet to plasticize the same, mo'ving'the tubular vacuum connection toward the receptacle to cause the tapered end wall of the tubular. vacuum connec-' tion to crowd the plasticized material inwardly andclose the bore of the tubular pellet, and sepa-V pellet in communication with the interior of the receptacle, fusing a tubular vacuum connection tion and fused to the head, then causing theseparts to cool, then evacuating the shell through the tubular connection and tubular pellet, again applying heat to the tubular connection adjacent to the pellet to cause the outer endof the pellet to be heated and plasticized, then movingthe tubular connection axially toward the tubular pellet to aid in closing its bore, then moving the tubular connection axially from the tubular pellet to separate the same therefrom while simultaneously stopping the evacuationof the shell through the tubular connection and tubular pellet and simultaneously cooling the outer end of the pellet so that it sets;

7. The method of vacuum sealing a receptacle j .having a recess accessible from the exterior, said recess having a bottom provided with an open ing, comprising arranging a tubular thermoplastic pellet within the recess, effecting a fused vacuum tight joint between the pellet and the wall of the'recess. bringing the end wall of a tubular vacuum connection into contact with the outer free end wall of the tubular pellet and effecting a fused vacuum tight joint between such end wa ls evacuating the receptacle through the connected vacuum connection and tubular pellet,

with the outer end of the tubular pelle for forming a vacuum-tight joint, evacuating he receptacle through the tubular connection and tubular pellet, applying heat to the tubular connection and thereby-causing the tubular connection to heat the outer end of the tubular pellet by conduction and plasticize such outenend, moving the tubular. connection toward the receptacle to'close the tubular pellet, causing the closed end of the pellet to set, breaking the vacuum within the tubular connection, and separating the tubular connection from the tubular pellet.

v 10. The method of vacuum sealing a receptacle, comprising effecting a, fused vacuum-tight joint between a tubular thermo-plasti'c pellet and the "receptacle and placing the bore of the tubular pellet in communication with the interior oi the receptacle, eflecting a fused vacuum-tight joint between a tubular vacuumconnection and the free end 01' the tubular pellet, evacuating the receptacie through the connected vacuum connection and tubular pellet, heating the tubular.

pellet to plasticize a portion of the'same, moving the vacuum connection inwardly toward the re ceptacle to' aid in closing the tubular pellet, and separating the vacuumconnection from the. closed pellet at a point adjacent to the free endof the tubular vacuum connection while the'tubular.

between the end of'a tubular vacuum connection 7 and the free end of thetubular pellet, evacuating V the receptacle through the connected vacuum connection and tubular pellet, heating the outer end of the tubular pellet to plasticize the same,

heating the tubularpellet to plasticizea portion ward the receptacle and thereby causing the plasof the same, moving the vacuum connection .to-.

moving the vacuum connection inwardly toward the receptacle to close the. bore of the tubular pellet by the plasticized outer portion, andfseparating the vacuum connection, from the outer closed end of the pellet.

12. The method of vacuumsealing a receptacle,

r a n g comprising fusing to the receptacle for forming a vacuum tight joint 2. tube having a lower fusing point than the receptacle and placing the bore of the tube in communication with the interior of the receptacle through the connected tube and tubular connection, heating the outer end of the tube to plasticize the same,'moving the tubular vacuum connection toward the receptacle for aid- .ing in closing the tube, and separating the tubular vacuum connection from the tube at a point ad- Jacent to the free end of the tubular vacuum connection while the tube remains attached to the receptacle.

aeeaese same, moving the tubular vacuum connection toward the receptacle for aiding in closing thetube and shortening the tube, and separatingthe tubu-. lar vacuum connection from the tube while the tube remains attached to the receptacle.

14. The method of vacuum sealing a receptacle, comprising placing 'a tube having a lower fusing point than the receptacle into contact with the receptacle heating the receptacle and thereby heating the tube by conduction and fusing the same to the receptacle for forming a vacuum tight Joint and placing the bore of thetube in communication with the interior of the receptacle,

13. The method of vacuum sealing a receptacle.

comprising fusing atube having a lower fusing point than the receptacle to the receptacle for forming a vacuum tight joint and placing the bore of the tube in communication with the interior of the receptacle, fusing the free end of placing the free end of a tubular vacuum connection having a higher fusing point than the tube in contact with thelouter free end of the tube, heating the tubular vacuum connection and causing the same to heat the outer end of the tube by conduction and thereby fusing the tube to the tubular vacuum connection and placing the bore of the tube in communication with the.bore of the tubular, vacuum connection, evacuating the receptacle through the connected tube and tubular connection, again heating the tubular vacuum connection to cause the same to heat the tube by conduction and plasticize the same, moving the tube to the end of a tubular vacuum connection having a higher fusing point than the tube for forming a vacuum tight joint and placing the bore of the tube in communication with the bore of the tubular vacuum connection, evacuating the receptacle through the connected tube and tubular connection, heating the tube to plasticize the ceptacle for aiding in closing the tube, and separating the tubular vacuum connection from the the tubular vacuum connection toward the reouter free end of the tube while the tube remains attached to the receptacle.

a CARL HERZOG.

PAUL A. nation.

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